Academic literature on the topic 'Microscopic pathogens'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Microscopic pathogens.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Microscopic pathogens"
1
Basri, Hasan. "Texture Feature Extraction of Pathogen Microscopic Image Using Discrete Wavelet Transform." Jurnal Riset Informatika 5, no. 1 (December 14, 2022): 549–54. http://dx.doi.org/10.34288/jri.v5i1.488.
Full textAbstract:
This study used a case study of Jabon leaves, and the pathogen is one of the causes of disease that attack the leaves of jabon, one of the leaf spots and leaf blight. Discovery of leaf spot disease in different pathogens and leaf blight. The pathogen was obtained from the leaf spot of Curvularia sp. 1 and Pestalotia sp., while the pathogen came from Curvularia sp. 2 and Botrytis sp. Identify the pathogen as soon as possible to minimize its effects. Improper handling can lead to increased virulence and resistance to the pathogen. Improper handling also can cause a disease outbreak (disease epidemic) in a region. This study is the first step in identifying the pathogens responsible for Jabon leaf disease. In this study, the Application of Koch's Postulates method to achieve the purification of pathogens and retrieve the microscopic pathogen image as the data acquisition stage. Furthermore, use of the segmentation stage to separate the object pathogen from the background, and one of the methods used is Otsu Thresholding. The extraction process of pathogen microscopic image using Discrete Wavelet Transform (DWT), DWT extraction results can be obtained using energy and entropy information.
2
Greenstein, Gary, and Alan Polson. "Microscopic Monitoring of Pathogens Associated with Periodontal Diseases." Journal of Periodontology 56, no. 12 (December 1985): 740–47. http://dx.doi.org/10.1902/jop.1985.56.12.740.
Full text
3
Goldsmith, Cynthia S., and Sherif R. Zaki. "Emerging and Reemerging Viral Pathogens: A Microscopic Overview." Microscopy and Microanalysis 7, S2 (August 2001): 172–73. http://dx.doi.org/10.1017/s1431927600026933.
Full textAbstract:
During the 20th century, the advent of vaccines and antibiotics, and continued improvements in urban sanitation and water quality resulted in a dramatic decline in mortality due to infectious diseases. There was a brief period of optimism in the mid-1900's that infectious pathogens would no longer be a significant cause of death in the United States. For a number of reasons, this trend had reversed by the end of the century, and the rates of death caused by infectious diseases began rising. in recognition of this change, the Institute of Medicine issued a report in 1992 that called attention to the major factors contributing to the emergence and reemergence of infectious diseases. Among these were the following: increased human encroachment on wilderness habitats, resulting in changes in the ecosystem and increased contact with animal and insect vectors which may harbor unknown infectious agents; sizable growth in human population, resulting in increased urbanization and crowding; increased global travel; changes in human behaviors; and microbial evolution.
4
Yeroshenko, G. A., O. D. Lysachenko, K. V. Shevchenko, O. V. Kinash, and L. B. Pelypenko. "IMPROVING SKILLS IN MICRODIAGNOSTICS DURING THE COURSES OF MEDICAL AND BIOLOGICAL DISCIPLINES." Актуальні проблеми сучасної медицини: Вісник Української медичної стоматологічної академії 22, no. 2 (September 27, 2022): 108–11. http://dx.doi.org/10.31718/2077-1096.22.2.108.
Full textAbstract:
Microscopic and submicroscopic studies of cyto- and histopreparations are used for high-quality assimilation of theoretical knowledge and practical skills over the courses "Histology, Cytology, Embryology" and "Medical Biology". They are an inseparable part of sessions when medical students learn the structure of cells, tissues, organs and make diagnoses parasitic diseases identifying pathogens and vectors of pathogens, helminth species, etc. Mastering medical and biological disciplines involves the ability to perform accurate study of micropreparations and their structural elements for further use in clinical practice, e.g. when investigating the biopsy samples, diagnosing pathological processes, establishing the causes of infection, or making laboratory diagnosis of parasitic diseases, etc. The main part of practical classes implies the students’ operating with microscopes. The classrooms of the departments are equipped with computers and microscopes with digital video cameras; the images of micropreparations of various magnifications can be visualized onto the screens of monitors, plasma TVs or the large screen by multimedia projectors. Ability to change the spot size setting facilitates better vision and thus better understanding of various histological structures. In practical classes on histology, cytology, and embryology, the theoretical material is consolidated by studying the microscopic structure of cells, tissues, and organs, diagnosing their histological structures, and processing electron microscopy data. Micropreparations of cells, stages of embryo development, extra-embryonic organs, helminths and their eggs are extensively used as material for investigation and analysis. The theoretical knowledge and practical skills acquired by students over the disciplines of a medical and biological profile pave the foundations for a holistic perception of the human body, contribute to improving skills in detecting microscopic structures, develop the ability to diagnose pathogens and vectors of parasitic diseases and are used in solving clinical case-studies.
5
Baidaa G. Ofi, Mohammed H. Abass, and Yehya A. Salih. "First report of Fusarium subglutinans (Wollenw. & Reinking) (1983) as a causative agent of leaf spot disease on broad bean Vicia faba L. in Iraq." University of Thi-Qar Journal of agricultural research 12, no. 2 (October 1, 2023): 41–45. http://dx.doi.org/10.54174/utjagr.v12i2.259.
Full textAbstract:
Broad bean (Vicia faba L.) is one of the most common vegetable crops in Iraq; cultivated in many areas. Broad bean production has been affected significantly by several diseases caused by either bacteria or fungi; among these pathogens Fusarium have a direct impact on faba beans production. The current study was conducted at the laboratories of the College of Agriculture - University of Basrah to identify the fungal pathogens of broad bean leaf spot disease. Isolation of the fungal pathogen was performed on PDA and PCA media; the morphological and microscopic identification revealed the identity of Fusarium subglutinans, followed a molecular diagnosis by ITS universal primers (ITS1 and ITS4) with a similarity percentage of 99%; the gene sequence was deposited at NCBI as LC769974.
Experimental tests confirmed the pathogen's capability to infect the vegetative system of the broad bean plants. This is the first recorded of F. subglutinans being identified as the cause of leaf spotting on broad bean plants, making it a notable discovery in both Iraq and globally.
6
Kupfer, Tom R., Daniel M. T. Fessler, Bozhi Wu, Tiffany Hwang, Adam Maxwell Sparks, Sonia Alas, Theodore Samore, Vedika Lal, Tanvi P. Sakhamuru, and Colin Holbrook. "The skin crawls, the stomach turns: ectoparasites and pathogens elicit distinct defensive responses in humans." Proceedings of the Royal Society B: Biological Sciences 288, no. 1955 (July 28, 2021): 20210376. http://dx.doi.org/10.1098/rspb.2021.0376.
Full textAbstract:
Disgust has long been viewed as a primary motivator of defensive responses to threats posed by both microscopic pathogens and macroscopic ectoparasites. Although disgust can defend effectively against pathogens encountered through ingestion or incidental contact, it offers limited protection against ectoparasites, which actively pursue a host and attach to its surface. Humans might, therefore, possess a distinct ectoparasite defence system—including cutaneous sensory mechanisms and grooming behaviours—functionally suited to guard the body's surface. In two US studies and one in China, participants ( N = 1079) viewed a range of ectoparasite- and pathogen-relevant video stimuli and reported their feelings, physiological sensations, and behavioural motivations. Participants reported more surface-guarding responses towards ectoparasite stimuli than towards pathogen stimuli, and more ingestion/contamination-reduction responses towards pathogen stimuli than towards ectoparasite stimuli. Like other species, humans appear to possess evolved psychobehavioural ectoparasite defence mechanisms that are distinct from pathogen defence mechanisms.
7
Wagner, Patricia, Kerstin Brügemann, Tong Yin, Petra Engel, Christina Weimann, Karen Schlez, and Sven König. "Microscopic differential cell count and specific mastitis pathogens in cow milk from compost-bedded pack barns and cubicle barns." Journal of Dairy Research 88, no. 4 (November 2021): 413–19. http://dx.doi.org/10.1017/s0022029921000844.
Full textAbstract:
AbstractCompost bedded pack barns (compost) as a new free walk housing system favorably influence udder health due to improved animal welfare and lying comfort. On the other hand, unfavorable effects on udder health are possible, due to the open bedded pack and the associated larger bacterial content in moisture. For in-depth farming system comparisons, the present study aimed to evaluate the specific cell fractions and mastitis pathogens in milk from cows kept in compost and in conventional cubical barns (cubicle). For milk sample collection we used a repeated measurement data structure of 2,198 udder quarters from 537 Holstein cows kept in six herds (3 in compost and 3 in cubicle). Differential cell counting was conducted including lymphocytes, macrophages and polymorphonuclear leukocytes (PMN). Specific mastitis pathogens comprised major and minor pathogens. Mixed models were applied to infer environmental and cow associated effects on cell fractions and on prevalences for pathogen infections, with specific focus on system × lactation stage, system × milk yield and system × somatic cell count effects. The interaction between system and lactation stage showed significant differences (P < 0.01) between the systems. A significantly smaller number of bacteriologically positive quarters and lower prevalences for minor pathogens were detected in compost compared to cubicle. Least squares means for pathogen prevalences indicated a quite constant proportion of bacteriologically negative udder quarters across milk yield levels in compost, but a slight increase with increasing milk yield in cubicle. Cell fraction responses in both systems differed in relation to the overall bacteriological infection status and farming system particularities. In conclusion, different cell fractions and specific mastitis pathogens should be considered as an indicator for udder health in different production systems, taking into account cow associated factors (lactation stage, milk yield).
8
Khan, Subhanullah, and Minglin Lang. "A Comprehensive Review on the Roles of Metals Mediating Insect–Microbial Pathogen Interactions." Metabolites 13, no. 7 (July 11, 2023): 839. http://dx.doi.org/10.3390/metabo13070839.
Full textAbstract:
Insects and microbial pathogens are ubiquitous and play significant roles in various biological processes, while microbial pathogens are microscopic organisms that can cause diseases in multiple hosts. Insects and microbial pathogens engage in diverse interactions, leveraging each other’s presence. Metals are crucial in shaping these interactions between insects and microbial pathogens. However, metals such as Fe, Cu, Zn, Co, Mo, and Ni are integral to various physiological processes in insects, including immune function and resistance against pathogens. Insects have evolved multiple mechanisms to take up, transport, and regulate metal concentrations to fight against pathogenic microbes and act as a vector to transport microbial pathogens to plants and cause various plant diseases. Hence, it is paramount to inhibit insect–microbe interaction to control pathogen transfer from one plant to another or carry pathogens from other sources. This review aims to succinate the role of metals in the interactions between insects and microbial pathogens. It summarizes the significance of metals in the physiology, immune response, and competition for metals between insects, microbial pathogens, and plants. The scope of this review covers these imperative metals and their acquisition, storage, and regulation mechanisms in insect and microbial pathogens. The paper will discuss various scientific studies and sources, including molecular and biochemical studies and genetic and genomic analysis.
9
Nasiłowska, Justyna, Aleksandra Kocot, Paulina Natalia Osuchowska, and Barbara Sokołowska. "High-Pressure-Induced Sublethal Injuries of Food Pathogens—Microscopic Assessment." Foods 10, no. 12 (November 30, 2021): 2940. http://dx.doi.org/10.3390/foods10122940.
Full textAbstract:
High Hydrostatic Pressure (HHP) technology is considered an alternative method of food preservation. Nevertheless, the current dogma is that HHP might be insufficient to preserve food lastingly against some pathogens. Incompletely damaged cells can resuscitate under favorable conditions, and they may proliferate in food during storage. This study was undertaken to characterize the extent of sublethal injuries induced by HHP (300–500 MPa) on Escherichia coli and Listeria inncua strains. The morphological changes were evaluated using microscopy methods such as Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Epifluorescence Microscopy (EFM). The overall assessment of the physiological state of tested bacteria through TEM and SEM showed that the action of pressure on the structure of the bacterial membrane was almost minor or unnoticeable, beyond the L. innocua wild-type strain. However, alterations were observed in subcellular structures such as the cytoplasm and nucleoid for both L. innocua and E. coli strains. More significant changes after the HHP of internal structures were reported in the case of wild-type strains isolated from raw juice. Extreme condensation of the cytoplasm was observed, while the outline of cells was intact. The percentage ratio between alive and injured cells in the population was assessed by fluorescent microscopy. The results of HHP-treated samples showed a heterogeneous population, and red cell aggregates were observed. The percentage ratio of live and dead cells (L/D) in the L. innocua collection strain population was higher than in the case of the wild-type strain (69%/31% and 55%/45%, respectively). In turn, E. coli populations were characterized with a similar L/D ratio. Half of the cells in the populations were distinguished as visibly fluorescing red. The results obtained in this study confirmed sublethal HHP reaction on pathogens cells.
10
Yao, Nan, Satoshi Imai, Yasuomi Tada, Hitoshi Nakayashiki, Yukio Tosa, Pyoyun Park, and Shigeyuki Mayama. "Apoptotic Cell Death is a Common Response to Pathogen Attack in Oats." Molecular Plant-Microbe Interactions® 15, no. 10 (October 2002): 1000–1007. http://dx.doi.org/10.1094/mpmi.2002.15.10.1000.
Full textAbstract:
We have examined the characteristics of cell death induced by pathogen infection in oats with respect to following hallmark apoptotic features: DNA laddering, chromatin condensation, and electron microscopic-bterminal deoxynucleotidyl transferase-mediated UTP end labeling positive response. A wide range of plant pathogens representing different levels of parasitism in susceptible and resistant interactions were used for the inocula, which include (i) an obligate parasite, Puccinia coronata f. sp. avenae (the crown rust fungus); (ii) a facultative biotroph parasite, Magnaporthe grisea (the blast fungus); (iii) pathogenic bacteria, Pseudomonas syringae pv. atropurpurea and P. syringae pv. coronafaciens (the halo or stripe blights of oats); and (iv) Ryegrass mottle virus. Surprisingly, any of the pathogens used induced most of the apoptotic features in oat cells at and around the infection sites, indicating that apoptotic cell death is a common phenomenon in oats during pathogen attack. The localization and the timing of apoptotic cell death during a course of infection were, however, quite different depending on the interactions (compatible or incompatible) and the pathogens (fungi, bacteria, or viruses). Possible roles of apoptotic cell death in the susceptible and resistant interactions are discussed.
Dissertations / Theses on the topic "Microscopic pathogens"
1
Pascault, Alice. "Investigating Candida albicans epithelial infection using a high-throughput microscopy-based assay." Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS277.pdf.
Full textAbstract:
Les infections fongiques représentent un problème émergeant de santé publique dans les pays développés. C. albicans est une levure dimorphique, commensale des muqueuses orales, génitales et intestinales d’une majorité de la population saine. Elle peut cependant conduire à des infections locales, comme les candidoses orales et vaginales voire à des infections systémiques chez les patients immunodéprimés. Si les interactions entre C. albicans et le système immunitaire de l’hôte sont désormais de mieux en mieux connues, l’invasion des épithélia qui est pourtant à l’origine des processus d’infection, demeure mal comprise. Quatre étapes ont été décrites : l’adhésion de la levure aux cellules de l’hôte, suivi par la filamentation qui permet d’obtenir une hyphe capable d’invasion et parfois de dommage infligé aux les cellules hôtes pouvant aboutir à une translocation dans les tissus profonds. Plusieurs facteurs ont été décrits, tant du côté de l’hôte que du pathogène, comme jouant un rôle dans l’invasion des epithelia, incluant les adhésines et invasines fongiques, la toxine candidalysine et l’E-cadherin de la cellule hôte. Une étude récente de notre équipe basée sur une technique de microscopie live à l’échelle cellulaire a permis de déterminer que l’invasion précoce des cellules épithéliales HeLa et Caco-2 peut faire intervenir deux modes d’interaction et donc deux modes de vie fongiques distincts : (1) l’invasion conduisant au dommage cellulaire, au cours de laquelle la membrane plasmique de la cellule hôte est rompue, fréquemment suivie de la mort de la cellule hôte (2) l’invasion au travers de tunnels trans-cellulaires (CaTCT) au cours de laquelle les hyphes envahissent les cellules hôtes entourés de tunnels de membrane cellulaire, sans dommage. Ces tunnels peuvent être multicellulaires et sont constitués de couches membranaires successives. Les mécanismes moléculaires conduisant à la formation de ces tunnels tant du point de vue fongique que du point de vue de l’hôte ne sont pas connus. L’objectif de ma thèse était d’identifier et de caractériser les facteurs d’hôte et du pathogène impliqués dans l’infection des cellules épithéliales Caco-2, qui ne fait intervenir que l’invasion au travers de CaTCT jusqu’à 9 heures d’infection. A cette fin j’ai développé un outil expérimental de microscopie permettant de quantifier de façon objective, universelle (i.e. pouvant s’appliquer à de nombreux modèles fongiques et de cellules hôtes) et à haut débit l’adhésion, la filamentation l’invasion et le dommage cellulaire au cours d’une seule expérience d’infection in vitro. Cet outil a ensuite été utilisé afin d’étudier plusieurs aspects dede la formation des CaTCT : (1) le rôle de la protéine fongique Als3 au cours de l’adhésion et de l’invasion (2) l’origine cellulaire des membranes impliquées dans les CaTCT (3) le rôle de la toxine peptidique candidalysine et des aspartyl-protéases (4) le métabolisme fongique au cours de l’invasion et notamment du métabolisme du glycogène (5) l’immunité de l’hôte au niveau des muqueuses au travers de la secrétion d’IgA. Le protocole mis en place m’a également permis de screener des souches cliniques commensales et issues d’infections systémiques afin de rechercher de nouveaux facteurs de virulence fongiques. Pour conclure, la nouvelle méthode expérimentale développée au cours de ce projet a permis quelques avancées dans la compréhension du processus énigmatique des CaTCT, et pourra servir à de futures études de l’infection de epithelia par C. albicans mais aussi à celles d’autres pathogènesFungal infections are an emerging threat to human health in developed countries. Candida albicans is a dimorphic yeast which colonizes the oral, genital and intestinal mucosa as part of the commensal flora of most of the healthy population. However, it can also lead to local infections such as oral and vaginal thrush and in susceptible patients to severe systemic infections. While much effort has been made in deciphering the interplay between C. albicans and the host at the immunological level, infection begins with invasion of the host epithelium, a process that is only partially understood. At the onset of infection, C. albicans transforms from a yeast to a filamentous hyphal form that can invade and damage epithelial cells, sometimes followed by translocation deeper into host tissues. Several fungal and host molecular factors have been shown to regulate epithelial invasion, including fungal adhesins, invasins and secreted factors such as the fungal toxin candidalysin, as well as host factors such as E-cadherin, which plays a role in C. albicans endocytic uptake. Recent work from our lab based on single cell, live imaging of early invasion into HeLa and Caco-2 cell lines revealed that two invasive lifestyles involving distinct host cellular niches can be exploited by the fungus: (1) Damaging invasion, in which host membranes are breached, leading most often to host cell death; (2) C. albicans trans-cellular tunnelling (CaTCT), in which hyphae extend within host membrane-derived transcellular tunnels without host damage. During CaTCT, hyphae can traverse through several host cells in sequence, leading to the formation of multi-layered tunnel structures. Currently, the molecular factors and cellular mechanisms regulating CaTCT from both the fungal and host sides remain almost entirely undescribed. The objective of my thesis project was to identify and characterize molecular factors and cellular processes regulating early Caco-2 infection by C. albicans, which occurs exclusively via CaTCT for up to 9 hours post-infection. For this purpose, I developed a novel quantitative, high-throughput and universal (i.e. applicable to a wide variety of fungal and host models) experimental imaging assay that uses an automated non-biased approach to provide single cell readouts pertaining to adhesion, hyphal formation, invasion and host damage in a single experiment. I then applied this assay to study several distinct aspects of CaTCT: (1) the function of the fungal Als3 protein in C. albicans adhesion and invasion; (2) the reservoir of host membranes implicated in trans-cellular tunnel formation and extension; (3) the function of the fungal toxin candidalysin and fungal secreted aspartyl proteases (Saps); (4) nutrient uptake and glycogen metabolism ; (5) the role of host secreted IgA in immune defence at the epithelial surface. In order to identify new potential virulence factors, I also employed the assay to screen for differences in epithelial infection between C. albicans clinical strains isolated from commensal and invasive origins. Overall, my work has provided several new insights into the mechanism of CaTCT, which act to further enhance our knowledge of this enigmatic process. Furthermore, the experimental assay developed in this project has important potential applications for future targeted studies and screens relating to C. albicans epithelial infection, as well as infection by other fungal pathogens
2
Galtier, Eloïse. "Etude du dégradosome à ARN de la bactérie pathogène Helicobacter pylori." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC002.
Full text
3
Lin, Xiaonan. "Chemical and Cellular Defenses against Foreign Pathogens." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10354.
Full textAbstract:
Bacterial and viral infections affect billions of people each year. While bacterial infections are treated by the use of antibiotics, viral infections are eradicated by the immune system. This thesis comprises two parts. Part I presents the reconstitution of enzymes required for the synthesis of the minimal pharmacophore of moenomycin A (MmA), a molecule with antibacterial activity. Part II details single-particle electron microscopy studies of MDA5 alone and in complex with double-stranded RNA (dsRNA). MmA is a natural product antibiotic from Streptomyces ghanaensis that possesses remarkable potency against clinically relevant Gram-positive bacteria. MmA exerts its antibacterial activity by binding directly to peptidoglycan glycosyltransferases, enzymes involved in the synthesis of the glycan strands of peptidoglycan. The genes responsible for MmA biosynthesis have been identified, and a complete biosynthetic pathway has been proposed. Part I of this thesis describes the reconstitution of enzymes required for the synthesis of two trisaccharide scaffolds of MmA that retain antibacterial activity. It also describes the synthesis of unnatural phosphoglycerate lipid acceptors and UDP-amino sugars that can be used to probe the substrate tolerances of key glycosyltransferases in MmA biosynthesis. This work lays the foundation for the synthesis of unnatural MmA analogs that may possess better pharmacokinetic properties than the parent molecule. MDA5 is a helicase that detects viral dsRNA in the cytoplasm of vertebrate cells. Upon dsRNA recognition, MDA5 initiates a series of signal transduction events that activate the innate immune response. Part II of this thesis presents the structures of apo MDA5 protein and the MDA5-dsRNA complex obtained by using single-particle electron microscopy. Two-dimensional averages of apo MDA5 revealed that the protein is very flexible and can adopt multiple conformations. This finding suggests that MDA5 does not adopt an autorepressed conformation in the absence of viral dsRNA. When MDA5 is incubated with dsRNA, the protein assembles onto the dsRNA to form a linear oligomer. Two-dimensional averages and a three-dimensional reconstruction reveal the complex to consist of seven to eight stacked discs per strand of 112 base pair dsRNA. This work lays the foundation for further structural studies aimed at elucidating the mechanism by which MDA5 is activated.Chemistry and Chemical Biology
4
Ijaz, Usman. "Molecular Mapping and Microscopic analysis of Faba Bean- Uromyces viciae-fabae Host-Pathogen Interaction." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18416.
Full textAbstract:
This investigation covered characterisation of various faba bean rust isolates by identifying a differential set in the host; identification of molecular markers linked with rust resistance genes Uvf-2 in Doza#12034 and Uvf-3 in Ac1655 and their validation across diverse backgrounds; and elucidation of the host-pathogen interactions of Uromyces viciae-fabae with faba bean, field pea (Pisum sativum), lentil (Lens culinaris), chickpea (Cicer arietinum), lupin (Lupinus albus and Lupinus angustifolius) and mungbean (Vigna radiata). The differential pathogenicity in the interaction of Vicia faba × Uromyces viciae-fabae led to the identification of nine faba bean rust pathotypes, characterised by the set of twelve genotypes (regarded as differential), and named 0-10, 0-46, 40-31, 40-55, 24-40, 63-53, 63-49, 55-63 and 63-63. This information will help faba bean breeders to carefully deploy rust resistance gene(s) which can effectively insight resistance against pathotypes of targeted environment. Genetic analysis, using pathotype 24-40, revealed monogenic inheritance of rust resistance in faba bean genotypes Doza#12034 and Ac1655, respectively. After genotyping Fiord/Doza#12034 and Fiord/Ac1655 RILs, two closely linked KASP markers KASP_Vf_0703 and KASP_Ac×F165 were mapped on chromosome III and V with Uvf-2 and Uvf-3, respectively and validated successfully in a set of local/exotic faba bean genotypes. These closely linked markers will allow breeders to implement markers assisted selection for both resistance genes. The histopathology of Australian U. viciae-fabae revealed a host range: both faba bean and field pea were competent hosts showing varietal differences to pathogen responses, with differential expression in resistance; lentil showed complete hypersensitive resistance by expressing cell death; and chickpea, lupin and mungbean appeared as non-hosts.
5
Alves, Eduardo. "Xylella fastidiosa adesão e colonização em vasos do xilema de laranjeira doce, cafeeiro, ameixeira, fumo e espécies de cigarrinhas vetoras e formação de biofilme sobre película de poliestireno." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/11/11135/tde-09052003-141508/.
Full textAbstract:
X. fastidiosa é uma bactéria fitopatogênica limitada ao xilema, que tem afetado um grande número de plantas no Brasil e no mundo. Muitos trabalhos já foram realizados sobre esta bactéria, mas pouco se conhece a respeito da adesão, colonização e expressão dos sintomas. Os objetivos deste trabalho foram: a) através do uso da microscopia eletrônica e de luz, determinar e relacionar o número de vasos colonizados de citros, cafeeiro e ameixeira com a sintomatologia em folhas; b) estudar a adesão, migração radial e colonização dos vasos do xilema do pecíolo de folhas de citros pela bactéria; c) estudar algumas variáveis experimentais que afetam a expressão dos sintomas em fumo; d) verificar os sítios de ligação da bactéria em cigarrinhas vetores; e) estudar a adesão e a formação do biofilme por X. fastidiosa em superfície de poliestireno, como uma nova metodologia. Os resultados mostraram em ameixeira e cafeeiro uma relação entre o número de vasos colonizados e a expressão de sintomas necróticos, relação esta que não pode ser observada para citros, o qual apresentava um número de vasos colonizados do pecíolo bem menor que o das outras duas espécies. No estudo da bactéria nos vaso do xilema de citros foi possível verificar as diversas fases do processo de colonização do xilema, bem como a capacidade da bactéria em degradar a parede celular primária da pontuação e migrar para os vasos adjacentes. Neste estudo foi também possível verificar respostas da planta à bactérias caracterizadas pela produção de cristais no lúmen dos vasos do xilema e o acúmulo de goma e hiperplasia de células nas folhas. No estudo com variedades de fumo verificou-se que a cultivar Havana apresentou expressão de sintomas mais intensa que as variedades TNN e RP1 e que o aparecimento dos mesmos não foi influenciado pelo volume de inóculo e pelo local de inoculação, mas sim pela adubação com sulfato de amônio, a qual retardou o aparecimento dos sintomas e reverteu os sintomas inicias em folhas após a aplicação. Em cigarrinhas, células bacterianas com morfologia similar as de X. fastidiosa, foram visualizadas aderidas pela parte lateral na câmara do cibário (sulco longitudinal, parede lateral e membrana do diafragma) de Acrogonia citrina, e Oncometopia facialis, no canal do apodeme de Dilobopterus costalimai e pela parte polar no precibário de O. facialis. Finalmente, no estudo da adesão de X. fastidiosa a película de poliestireno, os resultados revelaram as várias fases da formação do biofilme, aspectos da sua arquitetura, e indicaram que a técnica é uma ferramenta adequada para o estudo da formação do biofilme e também da morfologia das bactérias. Os resultados são discutidos em termos de modelos de adesão e colonização, da bactéria e importância para o conhecimento dos mecanismos de patogenicidade da bactéria em plantas e transmissão pelos vetores.X. fastidiosa is a xylem-limited bacterium that has been affecting a high number of plants in Brazil and in the world. A lot of researches were already accomplished on this bacterium, but little is known regarding the adhesion, colonization and expression of the symptoms in plants. The objectives of this work were: a) through the use of electron microscopy and of light microscopy determine and to correlate the number of xylem colonized vessels of petiole of sweet orange, coffee and plum with chlorosis and leaf scorching in leaves; b) study the adhesion, radial migration and colonization of the vessels of the petiole xylem of sweet orange by the bacterium; c) study some experimental variables that affect the expression of symptoms in tobacco; d) verify the retention sites of the bacterium in sharpshooters; d) study the adhesion and biofilm formation by X. fastidiosa on polystyrene surface. The results showed a relationship between the number of colonized vessels in plum and coffee and the expression of necrotic symptoms. However, that relationship was not observed for sweet orange, which presented a number of colonized vessels smaller than the other two species. In the study of the bacterium in the xylem vessels of sweet orange it was possible to verify the several phases of the colonization process of the xylem as well as the ability of the bacterium to degrade the primary cell wall of the pit and migrate to adjacent vessels. It was also possible to verify responses of the plant to the bacterium characterized by the production of crystals in the lumen of the xylem vessels and gum accumulation and hyperplasia in the leaf cells. Regarding the tobacco varieties it was verified that the expression of symptoms is more intense in the cultivar Havana than in the cultivars TNN and RP1. It was also seen that symptoms expression was not influenced by the inoculum volume or the inoculation place, but it was altered by fertilization with ammonium sulfate, which delayed the beginning of the symptoms and reverted the symptoms in leaves after the application. In sharpshooters, bacterial cells exhibiting morphology similar to X. fastidiosa were visualized attached to the lateral side in the cibarium camera (longitudinal, lateral wall and membrane of the diaphragm) of Acrogonia citrina, and Oncometopia facialis, in the apodemal channel of Dilobopterus costalimai, and in the polar part in the pre-cibarium of O. facialis. Finally, in the study of the adhesion of X. fastidiosa on polystyrene surface, the results revealed the several phases of biofilm formation; aspects of its architecture, and it also indicated that the technique is an appropriate tool to study of the formation of biofilms and also of the bacterial morphology. The results are discussed regarding adhesion models, colonization, and distribution of the bacterium in the plant and the importance of knowing the pathogenicity mechanisms of X. fastidiosa and its transmission by the insect vectors.
6
Morán, Cruz Gabriela. "Luminescent surfaces to fight or detect bacteria." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS214/document.
Full textAbstract:
Le 20ème siècle a vu le recul des maladies infectieuses grâce aux antibiotiques. Cependant leur importante utilisation a rendu certaines bactéries, comme Staphylococcus aureus ou Pseudomonas aeruginosa (multi)résistantes. Un des moyens de lutte est de réduire la consommation d’antibiotiques ou de cibler ceux qui seront actif sur une souche identifiée. Nous souhaitons développer des surfaces et des dispositifs sensibles pour la détection précoce, rapide de bactéries pathogènes dans des fluides. Cela permettra de limiter la contamination et donc l’usage de médicaments. Ce projet regroupe 3 partenaires qui travaillent en synergie en mettant à profit leur expertise en physico-chimie, chimie de synthèse et microbiologie. Des nano-objets fluorescents, biocompatibles, et sensibles à la croissance bactérienne seront immobilisés sur des surfaces de verre. Ils seront rendus sélectifs de bactéries pathogènes par des traitements post-synthétiques. Il s’agit in fine de mettre au point un dispositif de détection miniaturisé et de tester la résistance aux antibiotiques des pathogènes détectésInfectious diseases have recessed during the 20th century thanks to antibiotics. However, some bacterial strains like Staphylococcus aureus or Pseudomonas aeruginosa have become (multi)resistant to antibiotic treatments because of overuse. One way to combat this is to reduce consumption of drugs or to better target those that will eliminate a given strain. We wish to develop sensitive surfaces and devices for the early and rapid detection of pathogenic bacteria in fluids. They will help limit contaminations and the use of drugs. The project gathers 3 partners working in synergy because they combine expertise in physical-chemistry, synthetic chemistry and microbiology. Fluorescent nanoobjects that are biocompatible and sensitive to bacterial growth will be immobilized on glass surfaces. They will be selective for pathogenic bacteria by post-synthetic modifications. The final goal is to build miniaturized sensitive devices that can detect pathogens and further test their resistance to antibiotics
7
Logan, Savannah. "Imaging Vibrio Cholerae Invasion and Developing New Tools for 3D Microscopy of Live Animals." Thesis, University of Oregon, 2019. http://hdl.handle.net/1794/24524.
Full textAbstract:
All animals harbor microorganisms that interact with each other and with their hosts. These microorganisms play important roles in health, disease, and defense against pathogens. The microbial communities in the intestine are particularly important in preventing colonization by pathogens; however, this defense mechanism and the means by which pathogens overcome it remain largely unknown. Moreover, while the composition of animal-associated microbial communities has been studied in great depth, the spatial and temporal dynamics of these communities has only recently begun to be explored.
Here, we use a transparent model organism, larval zebrafish, to study how a human pathogen, Vibrio cholerae, invades intestinal communities. We pay particular attention to a bacterial competition mechanism, the type VI secrection system (T6SS), in this process. In vivo 3D fluorescence imaging and differential contrast imaging of transparent host tissue allow us to establish that V. cholerae can use the T6SS to modulate the intestinal mechanics of its host to displace established bacterial communities, and we demonstrate that one part of the T6SS apparatus, the actin crosslinking domain, is responsible for this function.
Next, we develop an automated high-throughput light sheet fluorescence microscope to allow rapid imaging of bacterial communities and host cells in live larval zebrafish. Light sheet fluorescence microscopy (LSFM) has been limited in the past by low throughput and tedious sample preparation, and our new microscope features an integrated fluidic circuit and automated positioning and imaging to address these issues and allow faster collection of larger datasets, which will considerably expand the use of LSFM in the life sciences. This microscope could also be used for future experiments related to bacterial communities and the immune system.
The overarching theme of the work in this dissertation is the use and development of advanced imaging techniques to make new biological discoveries, and the conclusions of this work point the way toward understanding pathogenic invasion, maximizing the use of LSFM in the life sciences, and gaining a better grasp of host-associated bacterial community dynamics.
This dissertation includes previously published and unpublished co-authored material.
8
Lee, Miin-Huey. "Microscopic, physiological and molecular studies of pathogenesis in Monilinia fructicola, the brown rot pathogen for stone fruits /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
Full text
9
Lavik, John-Paul. "Intravital Microscopy of Borrelia burgdorferi: Delineation of Dissemination Kinetics and Persistence Within Murine Skin." University of Toledo Health Science Campus / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=mco1340104556.
Full text
10
Theodoropoulos, Christina. "Pathogenicity of Plesiomonas shigelloides : interactions with eukaryotic host cells in vitro." Thesis, Queensland University of Technology, 2003. https://eprints.qut.edu.au/37160/6/37160_Digitised%20Thesis.pdf.
Full textAbstract:
Diarrhoea is one of the leading causes of morbidity and mortality in
populations in developing countries and is a significant health issue
throughout the world. Despite the frequency and the severity of the
diarrhoeal disease, mechanisms of pathogenesis for many of the causative
agents have been poorly characterised. Although implicated in a number of
intestinal and extra-intestinal infections in humans, Plesiomonas shigelloides
generally has been dismissed as an enteropathogen due to the lack of clearly
demonstrated virulence-associated properties such as production of
cytotoxins and enterotoxins or invasive abilities. However, evidence from a
number of sources has indicated that this species may be the cause of a
number of clinical infections. The work described in this thesis seeks to
resolve this discrepancy by investigating the pathogenic potential of
P. shigelloides using in vitro cell models. The focus of this research centres
on how this organism interacts with human host cells in an experimental
model.
Very little is known about the pathogenic potential of P. shigel/oides and its
mechanisms in human infections and disease. However, disease
manifestations mimic those of other related microorganisms. Chapter 2
reviews microbial pathogenesis in general, with an emphasis on
understanding the mechanisms resulting from infection with bacterial
pathogens and the alterations in host cell biology. In addition, this review
analyses the pathogenic status of a poorly-defined enteropathogen,
P. shigelloides.
Key stages of pathogenicity must occur in order for a bacterial pathogen to
cause disease. Such stages include bacterial adherence to host tissue,
bacterial entry into host tissues (usually required), multiplication within host
tissues, evasion of host defence mechanisms and the causation of damage.
In this study, these key strategies in infection and disease were sought to
help assess the pathogenic potential of P. shigelloides (Chapter 3). Twelve
isolates of P. shigelloides, obtained from clinical cases of gastroenteritis,
were used to infect monolayers of human intestinal epithelial cells in vitro.
Ultrastructural analysis demonstrated that P. shigelloides was able to adhere
to the microvilli at the apical surface of the epithelial cells and also to the
plasma membranes of both apical and basal surfaces. Furthermore, it was
demonstrated that these isolates were able to enter intestinal epithelial cells.
Internalised bacteria often were confined within vacuoles surrounded by
single or multiple membranes. Observation of bacteria within membranebound
vacuoles suggests that uptake of P. shigelloides into intestinal
epithelial cells occurs via a process morphologically comparable to
phagocytosis. Bacterial cells also were observed free in the host cell
cytoplasm, indicating that P. shige/loides is able to escape from the
surrounding vacuolar membrane and exist within the cytosol of the host.
Plesiomonas shigelloides has not only been implicated in gastrointestinal
infections, but also in a range of non-intestinal infections such as
cholecystitis, proctitis, septicaemia and meningitis. The mechanisms by
which P. shigelloides causes these infections are not understood. Previous
research was unable to ascertain the pathogenic potential of P. shigel/oides
using cells of non-intestinal origin (HEp-2 cells derived from a human larynx
carcinoma and Hela cells derived from a cervical carcinoma). However, with
the recent findings (from this study) that P. shigelloides can adhere to and
enter intestinal cells, it was hypothesised, that P. shigel/oides would be able
to enter Hela and HEp-2 cells. Six clinical isolates of P. shigelloides, which
previously have been shown to be invasive to intestinally derived Caco-2
cells (Chapter 3) were used to study interactions with Hela and HEp-2 cells
(Chapter 4). These isolates were shown to adhere to and enter both nonintestinal
host cell lines. Plesiomonas shigelloides were observed within
vacuoles surrounded by single and multiple membranes, as well as free in
the host cell cytosol, similar to infection by P. shigelloides of Caco-2 cells.
Comparisons of the number of bacteria adhered to and present intracellularly
within Hela, HEp-2 and Caco-2 cells revealed a preference of P. shigelloides
for Caco-2 cells. This study conclusively showed for the first time that
P. shigelloides is able to enter HEp-2 and Hela cells, demonstrating the
potential ability to cause an infection and/or disease of extra-intestinal sites in
humans.
Further high resolution ultrastructural analysis of the mechanisms involved in
P. shigelloides adherence to intestinal epithelial cells (Chapter 5) revealed
numerous prominent surface features which appeared to be involved in the
binding of P. shige/loides to host cells. These surface structures varied in
morphology from small bumps across the bacterial cell surface to much
longer filaments. Evidence that flagella might play a role in bacterial
adherence also was found. The hypothesis that filamentous appendages are
morphologically expressed when in contact with host cells also was tested.
Observations of bacteria free in the host cell cytosol suggests that
P. shigelloides is able to lyse free from the initial vacuolar compartment. The
vacuoles containing P. shigel/oides within host cells have not been
characterised and the point at which P. shigelloides escapes from the
surrounding vacuolar compartment has not been determined. A cytochemical
detection assay for acid phosphatase, an enzymatic marker for lysosomes,
was used to analyse the co-localisation of bacteria-containing vacuoles and
acid phosphatase activity (Chapter 6). Acid phosphatase activity was not
detected in these bacteria-containing vacuoles. However, the surface of
many intracellular and extracellular bacteria demonstrated high levels of acid
phosphatase activity, leading to the proposal of a new virulence factor for
P. shigelloides.
For many pathogens, the efficiency with which they adhere to and enter host
cells is dependant upon the bacterial phase of growth. Such dependency
reflects the timing of expression of particular virulence factors important for
bacterial pathogenesis. In previous studies (Chapter 3 to Chapter 6), an
overnight culture of P. shigelloides was used to investigate a number of
interactions, however, it was unknown whether this allowed expression of
bacterial factors to permit efficient P. shigelloides attachment and entry into
human cells. In this study (Chapter 7), a number of clinical and
environmental P. shigelloides isolates were investigated to determine
whether adherence and entry into host cells in vitro was more efficient during
exponential-phase or stationary-phase bacterial growth. An increase in the
number of adherent and intracellular bacteria was demonstrated when
bacteria were inoculated into host cell cultures in exponential phase cultures.
This was demonstrated clearly for 3 out of 4 isolates examined. In addition,
an increase in the morphological expression of filamentous appendages, a
suggested virulence factor for P. shigel/oides, was observed for bacteria in
exponential growth phase. These observations suggest that virulence
determinants for P. shigel/oides may be more efficiently expressed when
bacteria are in exponential growth phase. This study demonstrated also, for
the first time, that environmental water isolates of P. shigelloides were able to
adhere to and enter human intestinal cells in vitro. These isolates were seen
to enter Caco-2 host cells through a process comparable to the clinical
isolates examined. These findings support the hypothesis of a water
transmission route for P. shigelloides infections.
The results presented in this thesis contribute significantly to our
understanding of the pathogenic mechanisms involved in P. shigelloides
infections and disease. Several of the factors involved in P. shigelloides
pathogenesis have homologues in other pathogens of the human intestine,
namely Vibrio, Aeromonas, Salmonella, Shigella species and diarrhoeaassociated
strains of Escherichia coli. This study emphasises the relevance
of research into Plesiomonas as a means of furthering our understanding of
bacterial virulence in general. As well it provides tantalising clues on normal
and pathogenic host cell mechanisms.
Books on the topic "Microscopic pathogens"
1
Mendgen, Kurt, and Dietrich-Eckhardt Lesemann, eds. Electron Microscopy of Plant Pathogens. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-75818-8.
Full text
2
1944-, Mendgen K., Lesemann D. E. 1939-, and International Symposium Electron Microscopy Applied in Plant Pathology (1989 : University of Konstanz), eds. Electron microscopy of plant pathogens. Berlin: Springer-Verlag, 1991.
Find full text
3
Giampiero, Carosi, Filice G, and Rondanelli Elio Guido, eds. Human pathogenic protozoa: Atlas of electron-microscopy. Padova: Piccin, 1987.
Find full text
4
Wright, Lyra A. Rapid identification of periodontal pathogens by means of immunofluorescence microscopy: A critical review. [Toronto: Faculty of Dentistry, University of Toronto], 1990.
Find full text
5
O, Caul E., and Great Britain. Public Health Laboratory Service., eds. Immunofluorescence: Antigen detection techniques in diagnostic microbiology. London: Public Health Laboratory Service, 1992.
Find full text
6
Lesemann, Dietrich-Eckhardt, and Kurt Mendgen. Electron Microscopy of Plant Pathogens. Springer London, Limited, 2012.
Find full text
7
Lesemann, Dietrich-Eckhardt, and Kurt Mendgen. Electron Microscopy of Plant Pathogens. Springer, 2012.
Find full text
8
Lesemann, Dietrich-Eckhardt, and Kurt Mendgen. Electron Microscopy of Plant Pathogens. Springer London, Limited, 2011.
Find full text
9
Ladds, Philip. Pathology of Australian Native Wildlife. CSIRO Publishing, 2009. http://dx.doi.org/10.1071/9780643097933.
Full textAbstract:
Pathology of Australian Native Wildlife brings together in one volume available information on the pathology of Australian native vertebrate wildlife, excluding fish. It provides rapid access to documented information on diseases in Australian wildlife, domiciled either in Australia or overseas.
The book comprises 45 chapters, each detailing pathological changes caused by specific pathogens including viruses, bacteria, fungi, protozoa, helminths and ectoparasites, and other injurious agents and conditions such as toxins and neoplasia affecting terrestrial and marine mammals, birds, reptiles and amphibians. Although the aim is to describe morphological (gross and microscopic) changes, the author also indicates history and clinical signs, thus providing guidance as to which lesions should be specifically searched for, and what ancillary testing might be needed to confirm a diagnosis.
Illustrated throughout with colour photographs, this will be the essential reference for veterinary pathologists and clinicians, as well as wildlife researchers, zoos, wildlife parks, environmentalists, conservationists and students.
Awarded a 2010 Whitley Certificate of Commendation for Zoological Resource.
10
Brown, Danny. Under the Microscope: Microscope Use and Pathogen Identification in Birds and Reptiles. ABK Publications, 2003.
Find full textBook chapters on the topic "Microscopic pathogens"
1
Moore, Jayma A., and Scott A. Payne. "Freeze-Fracture of Infected Plant Leaves in Ethanol for Scanning Electron Microscopic Study of Fungal Pathogens." In Plant Fungal Pathogens, 107–19. Totowa, NJ: Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61779-501-5_7.
Full text
2
Monier, J. M., and S. E. Lindow. "Exploring Pseudomonas syringae Ecology via Direct Microscopic Observations of the Leaf Surface." In Pseudomonas syringae and related pathogens, 29–40. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-017-0133-4_3.
Full text
3
Viret, Olivier, and Katia Gindro. "Fungi and Grapevine Mycobiota." In Science of Fungi in Grapevine, 109–95. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-68663-4_3.
Full textAbstract:
AbstractThe fungi kingdom consists of a vast group of macro- and microscopic eukaryotic organisms characterised by a heterotrophic mode of nutrition and sexual and asexual forms of reproduction. Their history dating back millions of years attests to their remarkable capacity for adaptation, their diversity and their evolutionary plasticity. They encompass an enormous variety of organisms ranging from unicellular yeasts to filamentous fungi which form extensive underground mycelial networks.Fungi are ubiquitous and play a key role in ecosystems as decomposers, symbionts and pathogens. Decomposers are essential for breaking down organic matter in the soil and recycling the nutrients. Symbiotic fungi such as the mycorrhizals establish beneficial mutual relationships with plants. They provide essential nutrients such as phosphorus and nitrogen and receive organic compounds produced by the plant in return. Pathogenic fungi can cause serious diseases in plants, animals and humans. The immense destructive power of phytopathogenic fungi requires effective control measures to minimise their impact on crops. Plants cohabit with a vast array of fungi which form the mycobiome either in (endophytic) or on (ectophytic) the vegetative tissue. These fungi play a vital role in plant health, growth and environmental adaptation. Depending on specific biotic and abiotic factors, some species within the mycobiome can change behaviour and switch from an endophytic to a pathogenic state.Understanding the diversity, role and interactions of the grapevine mycobiome provides new opportunities for sustainable vineyard management. Fungi and plants have cohabited for millennia in a relationship characterised by constantly shifting coevolutionary dynamics that have yet to be discovered.
4
Viret, Olivier, and Katia Gindro. "Introduction." In Science of Fungi in Grapevine, 1–9. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-68663-4_1.
Full textAbstract:
AbstractDomesticated from wild lianas growing in trees, grapevine (Vitis vinifera subsp. vinifera) has been cultivated for over 11,000 years. From its original habitat to its establishment in the steeply sloping regions of Europe to create picturesque landscapes and terraces, to the methodically aligned rows of modern industrial vineyards, the vine has passed through several stages of natural or human-influenced co-evolution. Growers have gradually dispersed grapevine from its genetic centre in the Caucasus and Western Asia throughout Europe and to the rest of the world. Documentation on vine cultivation before the eighteenth century is sparse, particularly regarding diseases and pests which were increasingly discovered through microscopic observation and better understood as they became ubiquitous and increasingly destructive. The European phylloxera crisis at the end of the nineteenth century had disastrous economic consequences and led to radical changes in vine growing. Generations of researchers worked diligently to discover, understand and defeat fungi. Even with regular applications of effective fungicides, pathogen control remains a challenge in all the world’s vine-growing areas. Depending on weather conditions, both Vitis species that are highly susceptible (V. vinifera) and partially resistant (Vitis spp) contend with fungal diseases. The science of fungi in grapevine focuses on the complexity of this group of pathogens, their interactions with the host plant, the structure and anatomy of the grapevine, the plant’s defence mechanisms and resistance genes, the role of fungicides and alternative plant protection products, and the importance of spraying technologies for disease management.
5
Brauge, Thomas, Graziella Midelet-Bourdin, and Christophe Soumet. "Viability Detection of Foodborne Bacterial Pathogens in Food Environment by PMA-qPCR and by Microscopic Observation." In Methods in Molecular Biology, 117–28. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-9000-9_9.
Full text
6
Hardham, Adrienne R. "Confocal Microscopy in Plant–Pathogen Interactions." In Plant Fungal Pathogens, 295–309. Totowa, NJ: Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61779-501-5_18.
Full text
7
Nadal, Marina, and Scott E. Gold. "Assessment of Autophagosome Formation by Transmission Electron Microscopy." In Plant Fungal Pathogens, 481–89. Totowa, NJ: Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61779-501-5_29.
Full text
8
Butter, N. S. "Plant Pathogens and Electron Microscope." In Insect Vectors and Plant Pathogens, 346–72. Boca Raton, FL : CRC Press, Taylor & Francis Group, [2018]: CRC Press, 2018. http://dx.doi.org/10.1201/9780429503641-13.
Full text
9
Milne, Robert G. "Immunoelectron Microscopy for Virus Identification." In Electron Microscopy of Plant Pathogens, 87–102. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-75818-8_7.
Full text
10
Hoch, H. C. "Preservation of Cell Ultrastructure by Freeze-Substitution." In Electron Microscopy of Plant Pathogens, 1–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-75818-8_1.
Full textConference papers on the topic "Microscopic pathogens"
1
George, Simi A., Erik Avaniss-Aghajani, Sarah Hernandez, Euan Mowat, Andrew Gilbert, Mario Martinez, Zachary Schaffer, and Mathew Theurer. "Light waves, hidden clues: how spectroscopy and A.I. can detect pathogens faster." In Advanced Chemical Microscopy for Life Science and Translational Medicine 2025, edited by Garth J. Simpson, Ji-Xin Cheng, and Wei Min, 66. SPIE, 2025. https://doi.org/10.1117/12.3046812.
Full text
2
Park, Jeong-Seon, Myung-Joo Oh, and Soonhee Han. "Fish Disease Diagnosis System Based on Image Processing of Pathogens' Microscopic Images." In 2007 Frontiers in the Convergence of Bioscience and Information Technologies. IEEE, 2007. http://dx.doi.org/10.1109/fbit.2007.157.
Full text
3
Şcerbacova, Tatiana. "Some aspects of developing microbial preparations for plant protection." In 5th International Scientific Conference on Microbial Biotechnology. Institute of Microbiology and Biotechnology, Republic of Moldova, 2022. http://dx.doi.org/10.52757/imb22.32.
Full textAbstract:
The basis of microbial means of plant protection against diseases is live cultures of microorganisms with high virulence and their metabolic products. The leading role in the biological control of plant diseases is assigned to microscopic fungi. A special place is occupied by the genus Trichoderma Pers. ex Fr. The advantages are a high growth rate, a wide range of antifungal activity, and simple equipment for cultivation on an industrial scale. The biopreparation production technology constitutes the cultivation of the fungus-producer in a liquid nutrient medium in a bioreactor or on a microbiological shaker for 72-96 hours. An important step in obtaining effective biopreparations is the selection of the optimal nutrient medium for cultivating the bioagent. Modification of nutrient media according to the main sources of nutrition of microorganisms (carbon, nitrogen) promotes the formation of biologically active substances that have an inhibitory effect on phytopathogens. This action can be strengthened or weakened. During the evaluation of the fungicidal action spectrum of the liquid biopreparation Gliocladin-SC (the active substance is the fungus Trichoderma virens Miller, Giddens, and Foster), 18 pathogenic agents of crop diseases causative agents were identified (Scerbacova T., 2019). Several liquid nutrient media were used in the present work. When the medium composition changed according to the carbon source, in addition to chlamydospores, conidia and blastospores were formed. The zones of Sclerotinia sclerotiorum pathogens inhibition growth (Fig. 1) and Botrytis cinerea expanded, and the antifungal effect against pathogens of fruit crops Monilia cinerea and M. fructigena also increased. The preparation fabricated on the base of that nutrient medium was tested on “Krupnoplodnyi” sweet cherries variety to suppress the development of moniliosis. After two treatments with 1% concentration, the disease development reduction efficiency was 91.8% (Scerbacova T. et al., 2015). Media 2(a) Media 10 Media 11 Figure 1. Growth inhibition zones of the pathogen S. sclerotiorum with Gliocladin-SC biopreparation based on media with different compositions In the result of the conducted research, it was found that for the successful application of GliocladinSC biopreparation in plant protection against a wide range of diseases, separate balanced nutrient media for controlling different groups of pathogens are needed.
4
Ibrahim Mohammed, Khetam. "Effect of Silver Nanoparticles on Dermatophytes Isolated from Palms Of Hands & Feet." In XIII. International Scientific Congress of Pure, Applied and Technological Sciences, 41–50. Rimar Academy, 2025. https://doi.org/10.47832/minarcongress13-5.
Full textAbstract:
The dermatophytosis skin infection is caused by filamentous fungi and can caused by some of types of yeasts . The prevalence of these common mycoses is about 20% of the population. These fungi have demonstrated strong resistance to some of the drugs used to treat them in the past few years, it has been noted. Nanoparticles, whether silver nanoparticles or gold nanoparticles, and other types of nanoparticles show great effectiveness against human pathogens , whether bacterial or fungal ,They have the ability to change The cell membrane's structure until it causes its death. The purpose of this research is to test effectiveness of nanoparticles (Ag nanoparticles ) against the fungi that cause skin infections in patients . This has been demonstrated by their high effectiveness against the Trichophyton fungus, as here in this research their effectiveness was studied on fungi isolated from the feet and the hands. Which were diagnosed according to agricultural and microscopic features. The effectiveness of the silver nanoparticles solution was tested at concentrations of 2%, 4%, and 8% against the diagnosed Trichophyton fungus isolated from the skin infected with the fungus. It was found to have a high effectiveness for the silver nanoparticles , especially at the concentration of 8%, which is the highest concentration used against this pathogen compared to the commercial antifungal
5
Yang, Chun-Lin, Nandan Shettigar, and C. Steve Suh. "A Proposition for Describing Real-World Network Dynamics." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-73360.
Full textAbstract:
Abstract This study presents a proposition for describing the dynamics of real-world networks under the general framework of complex networks. Outward behaviors of complex networks are the manifestation of the coupled dynamics at the macroscopic level and the individual dynamics at the microscopic level. At the macroscopic level a law of coupling governs the interactions of network constituents. At the microscopic level, the dynamics of individual constituent is defined by energy that follows normal distribution. Constituent dynamics are bounded by physical constraints. Consequently, network dynamics can be quantified using information entropy which is a function of constituent energy. In real-world networks, differences between individual constituents exist due to differing mechanical properties and dynamics. Consequently, network dynamics are of different layers and hierarchies. Construct of network governing equations formulated under the general framework of complex networks are demonstrated using two real-world networks — a brain network and a lymph node network. Brain network is constructed by the neurons that each connected by the synapse. Brain network dynamics is composed by the law of coupling defined by the synaptic dynamics through the transmitting of neurotransmitters that couples the individual neuron dynamics. Since different classifications exist among neurotransmitters and neurons, the post synaptic neuron can present either inhibitory or excitatory action. The inhibitory and excitatory behavior of the neurons changes the mechanical properties of each neuron and further alters the brain network dynamics. Consequently, the brain network emerges dynamics with different layers. Lymph node network drains fluid from blood vessels, filter the lymph (the interstitial fluid lymphatic system collects from the blood circulation) through lymph nodes, and transport the lymph back to the blood circulation. Lymph node dynamics is composed by the dynamics of lymph transportation along the lymph node network and the individual lymph node dynamics that involves lymphocytes-pathogens interactions (adaptive immune response). In each lymph node, lymphocytes fight off the pathogens which also emerges a network dynamics such as the interaction between T cells and HIV viruses. Finally, the lymph is collected from each lymph nodes and drained back to the blood circulation. As a result, the lymph node network has the dynamics of different hierarchies where the lymphocytes-pathogens dynamics exists within each lymph node at the lower hierarchy is further under the influence of the lymph transportation dynamics among the whole lymph node network on the higher hierarchy. Since the constituent dynamics of the brain network and lymph node network can be defined by energy that follows normal distribution and both are bounded by physical constraints, the network dynamics of both cases can be quantified through information entropy. Features pertaining to the global as well as individual constituent dynamics of the networks are identified that are insightful to the control of such complex networks.
6
Tokmakova, A. S., E. E. Prokhorova, M. K. Serebryakova, and G. L. Ataev. "FUNCTIONAL ACTIVITY OF HEMOCYTES OF PULMONARY MOLLUSCS." In V International Scientific Conference CONCEPTUAL AND APPLIED ASPECTS OF INVERTEBRATE SCIENTIFIC RESEARCH AND BIOLOGICAL EDUCATION. Tomsk State University Press, 2020. http://dx.doi.org/10.17223/978-5-94621-931-0-2020-38.
Full textAbstract:
Hemocytes, the cell of the hemolymph, play a key role in the immune response of pulmonate molluscs to various pathogens including trematode infection. The number of hemocytes is known to increase after immunization but the mechanism of their multiplication remains debatable. In this work we studied the functional and proliferative activity of hemocytes in two species of pulmonate molluscs: Biomphalaria glabrata, Planorbarius corneus. ImageStream technique was used for the study of the hemocyte populations of these molluscan species for the first time. The hemocytes of all the studied species were represented by two main types, granular cells and hyalinocytes. Microscopic and flow-cytometric study of the hemocytes with the use of EdU revealed some EdU-positive cells. However, the analysis of the cell cycle of the hemocytes showed that the amount of DNA in these cells was not increased.
7
Chen, Hong, Assem Abolmaaty, Peng Li, Constantine Anagnostopoulos, Stefan Du¨bel, and Mohammad Faghri. "Heterogeneous Detection of PCR-Amplified Intimin Gene From E. Coli O157:H7 via PDMS Microfluidic Chip." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11796.
Full textAbstract:
E. coli O157:H7 strains represent the most important group of food-borne pathogens. PCR-amplified intimin gene of pathogenic E. coli O157:H7 was detected heterogeneously via a microfluidic chip that consists of streptavidin-coated nanoliter chambers. Biotinylated primers and digoxigenin labeled deoxyuridine triphosphate (dUTP) were incorporated into the amplified intimin (eaeA) gene by an off-chip PCR thermal cycler. The amplified products were injected into the chip where they were immobilized via streptavidin-biotin interaction. Detection of the products using alkaline phosphatase (AP) conjugated anti-digoxigenin was performed with an epi-fluorescent microscope. This assay was capable of detecting 0.06 ng/μL biotin-digoxigenin-dsDNA conjugate distinctly, which is a hundred fold more sensitive than the traditional detection by agarose gel.
8
Fong, Alexandre, George Shu, Barry McDonogh, and Bosoon Park. "Detecting foodborne pathogens with darkfield hyperspectral microscopy." In Hyperspectral Imaging and Applications, edited by Jinchang Ren and Stephen Marshall. SPIE, 2020. http://dx.doi.org/10.1117/12.2584913.
Full text
9
Strnad, Martin. "Adhesins and motility of human pathogen Borrelia burgdorferi." In European Microscopy Congress 2020. Royal Microscopical Society, 2021. http://dx.doi.org/10.22443/rms.emc2020.793.
Full text
10
Kruss, Sebastian. "Near infrared imaging and detection of pathogens with multiplexed nanosensors." In Biomedical Spectroscopy, Microscopy, and Imaging III, edited by Jürgen Popp and Csilla Gergely. SPIE, 2024. http://dx.doi.org/10.1117/12.3017831.
Full textReports on the topic "Microscopic pathogens"
1
Freeman, Stanley, and Russell J. Rodriguez. The Interaction Between Nonpathogenic Mutants of Colletotrichum and Fusarium, and the Plant Host Defense System. United States Department of Agriculture, September 2000. http://dx.doi.org/10.32747/2000.7573069.bard.
Full textAbstract:
The intent of this proposal was to study the interaction between nonpathogenic mutants of Colletotrichum magna and Fusarium oxysporum, and the cucurbit host defense system. We had shown previously that a nonpathogenic endophytic mutant path- 1 of C. magna, caused no visible disease symptoms but protected watermelon seedlings from disease caused by the wildtype isolate and F. o. niveum. Objectives were: 1) Determine the microscopic, biochemical and molecular genetic interaction between "protected" (path- 1 colonized) cucurbit hosts and wildtype isolates of C. magna; 2) Isolate non-pathogenic mutants of F.o. melonis and test feasibility for protecting plants against fungal diseases. We found that path-1 caused no visible disease symptoms in cucurbit seedlings but conferred disease resistance against pathogenic isolates of C. magna, C. orbiculare, and F. oxysporum. Disease resistance conferred by path-1 correlated to a decrease in the time of activation of host defense systems after exposure of path-1 colonized plants to virulent pathogens. This was determined by monitoring the biochemical activity of PAL and peroxidase, and the deposition of lignin. It appears that path-1-conferred disease resistance is a multigenic phenomenon which should be more difficult for pathogen to overcome than single gene conferred resistance. Based on the benefits conferred by path-1, we have defined this mutant as expressing a mutualistic lifestyle. REMI (restriction enzyme-mediated integration) nonpathogenic mutants were also isolated using pHA1.3 plasmid linearized with Hind III and transformed into wildtype C. magna. The integrated vector and flanking genomic DNA sequences in REMI mutant R1 was re-isolated and cloned resulting in a product of approximately 11 kb designated pGMR1. Transformations of wildtype C. magna with pGMR1 resulted in the same non-pathogenic phenotype. A nonpathogenic mutant of F.o. melonis (pathogenic to melon) was isolated that colonized melon plants but elicited no disease symptoms in seedlings and conferred 25 - 50% disease protection against the virulent wildtype isolate. Subsequently, nonpathogenic mutant isolates of F.o. niveum (pathogenic to watermelon) were also isolated. Their protection capacity against the respective wildtype parent is currently under investigation. This research has provided information toward a better understanding of host-parasite interactions; specifically, endophytes, pathogens and their hosts. It will also allow us to assess the potential for utilizing nonpathogenic mutants as biological control agents against fungal pathogens and isolating molecular genetic factors of pathogenicity in Fusarium.
2
Gillor, Osnat, Stefan Wuertz, Karen Shapiro, Nirit Bernstein, Woutrina Miller, Patricia Conrad, and Moshe Herzberg. Science-Based Monitoring for Produce Safety: Comparing Indicators and Pathogens in Water, Soil, and Crops. United States Department of Agriculture, May 2013. http://dx.doi.org/10.32747/2013.7613884.bard.
Full textAbstract:
Using treated wastewater (TWW) for crop irrigation represents an important opportunity for ensuring adequate food production in light of growing freshwater scarcity worldwide. However, the environmentally sustainable approach of using TWW for irrigation can lead to contamination of produce with fecal pathogens that may remain in treated water. The overall goal of this research was to evaluate the correlation between the presence of fecal indicator bacteria (FIB) and that of a suite of human pathogens in TWW, the irrigated soil, and crops. Field experiments were conducted to compare secondary and tertiary TWW with dechlorinated tap water for irrigation of tomatoes, a typical commercial crop, in Israel, a semi-arid country. Human pathogens including bacteria (Salmonella), protozoa (Cryptosporidiumand Giardia), and viruses (Adenovirus [AV Types A, B, C & 40/41] and Enterovirus [EV71 subtypes]) were monitored in two field trials using a combination of microscopic, cultivation-based, and molecular (qPCR) techniques. Results from the field trials indicate that microbial contamination on the surface of tomatoes did not appear to be associated with the source of irrigated waters; FIB contamination was not statistically different on tomatoes irrigated with TWW as compared to tomatoes irrigated with potable water. In fact, Indicator bacteria testing did not predict the presence of pathogens in any of the matrices tested. High concentrations of FIB were detected in water and on tomato surfaces from all irrigation treatment schemes, while pathogen contamination on tomato surfaces (Cryptosporidiumand Salmonella) was only detected on crops irrigated with TWW. These results suggest that regular monitoring for pathogens should take place to accurately detect presence of harmful microorganisms that could threaten consumer safety. A notable result from our study is that the large numbers of FIB in the water did not appear to lead to FIB accumulation in the soil. With the exception of two samples, E. coli that was present at 10³ to 10⁴ cells/100 mL in the water, was not detected in the soil. Other bacterial targets associated with the enteric environment (e. g., Proteusspp.) as well as protozoal pathogens were detected in the TWW, but not in the soil. These findings suggest that significant microbial transfer to the soil from TWW did not occur in this study. The pattern of FIB contamination on the surfaces of tomatoes was the same for all treatment types, and showed a temporal effect with more contamination detected as the duration of the field trial increased. An important observation revealed that water quality dramatically deteriorated between the time of its release from the wastewater treatment plant and the time it was utilized for irrigation, highlighting the importance of performing water quality testing throughout the growing season at the cultivation site.
3
Dickman, Martin B., and Oded Yarden. Genetic and chemical intervention in ROS signaling pathways affecting development and pathogenicity of Sclerotinia sclerotiorum. United States Department of Agriculture, July 2015. http://dx.doi.org/10.32747/2015.7699866.bard.
Full textAbstract:
Abstract: The long-term goals of our research are to understand the regulation of sclerotial development and pathogenicity in S. sclerotior11111. The focus in this project was on the elucidation of the signaling events and environmental cues involved in the regulation of these processes, utilizing and continuously developing tools our research groups have established and/or adapted for analysis of S. sclerotiorum, Our stated objectives: To take advantage of the recent conceptual (ROS/PPs signaling) and technical (amenability of S. sclerotiorumto manipulations coupled with chemical genomics and next generation sequencing) developments to address and extend our fundamental and potentially applicable knowledge of the following questions concerning the involvement of REDOX signaling and protein dephosphorylation in the regulation of hyphal/sclerotial development and pathogenicity of S. sclerotiorum: (i) How do defects in genes involved in ROS signaling affect S. sclerotiorumdevelopment and pathogenicity? (ii) In what manner do phosphotyrosinephosphatases affect S. sclerotiorumdevelopment and pathogenicity and how are they linked with ROS and other signaling pathways? And (iii) What is the nature of activity of newly identified compounds that affect S. sclerotiori,111 growth? What are the fungal targets and do they interfere with ROS signaling? We have met a significant portion of the specific goals set in our research project. Much of our work has been published. Briefly. we can summarize that: (a) Silencing of SsNox1(NADPHoxidase) expression indicated a central role for this enzyme in both virulence and pathogenic development, while inactivation of the SsNox2 gene resulted in limited sclerotial development, but the organism remained fully pathogenic. (b) A catalase gene (Scatl), whose expression was highly induced during host infection is involved in hyphal growth, branching, sclerotia formation and infection. (c) Protein tyrosine phosphatase l (ptpl) is required for sclerotial development and is involved in fungal infection. (d) Deletion of a superoxidedismutase gene (Sssodl) significantly reduced in virulence on both tomato and tobacco plants yet pathogenicity was mostly restored following supplementation with oxalate. (e) We have participated in comparative genome sequence analysis of S. sclerotiorumand B. cinerea. (f) S. sclerotiorumexhibits a potential switch between biotrophic and necrotrophic lifestyles (g) During plant microbe interactions cell death can occur in both resistant and susceptible events. Non pathogenic fungal mutants S. sclerotior111n also cause a cell death but with opposing results. We investigated PCD in more detail and showed that, although PCD occurs in both circumstances they exhibit distinctly different features. The mutants trigger a restricted cell death phenotype in the host that unexpectedly exhibits markers associated with the plant hypersensitive (resistant) response. Using electron and fluorescence microscopy, chemical effectors and reverse genetics, we have established that this restricted cell death is autophagic. Inhibition of autophagy rescued the non-pathogenic mutant phenotype. These findings indicate that autophagy is a defense response in this interaction Thus the control of cell death, dictated by the plant (autophagy) סr the fungus (apoptosis), is decisive to the outcome of certain plant microbe interactions. In addition to the time and efforts invested towards reaching the specific goals mentioned, both Pls have initiated utilizing (as stated as an objective in our proposal) state of the art RNA-seq tools in order to harness this technology for the study of S. sclerotiorum. The Pls have met twice (in Israel and in the US), in order to discuss .נחd coordinate the research efforts. This included a working visit at the US Pls laboratory for performing RNA-seq experiments and data analysis as well as working on a joint publication (now published). The work we have performed expands our understanding of the fundamental biology (developmental and pathogenic) of S. sclerotioז111וז. Furthermore, based on our results we have now reached the conclusion that this fungus is not a bona fide necrotroph, but can also display a biotrophic lifestyle at the early phases of infection. The data obtained can eventually serve .נ basis of rational intervention with the disease cycle of this pathogen.
4
Splitter, Gary A., Menachem Banai, and Jerome S. Harms. Brucella second messenger coordinates stages of infection. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7699864.bard.
Full textAbstract:
Aim 1: To determine levels of this second messenger in: a) B. melitensiscyclic-dimericguanosinemonophosphate-regulating mutants (BMEI1448, BMEI1453, and BMEI1520), and b) B. melitensis16M (wild type) and mutant infections of macrophages and immune competent mice. (US lab primary) Aim 2: To determine proteomic differences between Brucelladeletion mutants BMEI1453 (high cyclic-dimericguanosinemonophosphate, chronic persistent state) and BMEI1520 (low cyclicdimericguanosinemonophosphate, acute virulent state) compared to wild type B. melitensisto identify the role of this second messenger in establishing the two polar states of brucellosis. (US lab primary with synergistic assistance from the Israel lab Aim 3: Determine the level of Brucellacyclic-dimericguanosinemonophosphate and transcriptional expression from naturally infected placenta. (Israel lab primary with synergistic assistance from the US lab). B. Background Brucellaspecies are Gram-negative, facultative intracellular bacterial pathogens that cause brucellosis, the most prevalent zoonosis worldwide. Brucellosis is characterized by increased abortion, weak offspring, and decreased milk production in animals. Humans are infected with Brucellaby consuming contaminated milk products or via inhalation of aerosolized bacteria from occupational hazards. Chronic human infections can result in complications such as liver damage, orchitis, endocarditis, and arthritis. Brucellaspp. have the ability to infect both professional and non-professional phagocytes. Because of this, Brucellaencounter varied environments both throughout the body and within a cell and must adapt accordingly. To date, few virulence factors have been identified in B. melitensisand even less is known about how these virulence factors are regulated. Subsequently, little is known about how Brucellaadapt to its rapidly changing environments, and how it alternates between acute and chronic virulence. Our studies suggest that decreased concentrations of cyclic dimericguanosinemonophosphate (c-di-GMP) lead to an acute virulent state and increased concentrations of c-di-GMP lead to persistent, chronic state of B. melitensisin a mouse model of infection. We hypothesize that B. melitensisuses c-di-GMP to transition from the chronic state of an infected host to the acute, virulent stage of infection in the placenta where the bacteria prepare to infect a new host. Studies on environmental pathogens such as Vibrio choleraeand Pseudomonas aeruginosasupport a mechanism where changes in c-di-GMP levels cause the bacterium to alternate between virulent and chronic states. Little work exists on understanding the role of c-di-GMP in dangerous intracellular pathogens, like Brucellathat is a frequent pathogen in Israeli domestic animals and U.S. elk and bison. Brucellamust carefully regulate virulence factors during infection of a host to ensure proper expression at appropriate times in response to host cues. Recently, the novel secondary signaling molecule c-di-GMP has been identified as a major component of bacterial regulation and we have identified c-di-GMP as an important signaling factor in B. melitensishost adaptation. C. Major conclusions, solutions, achievements 1. The B. melitensis1453 deletion mutant has increased c-di-GMP, while the 1520 deletion mutant has decreased c-di-GMP. 2. Both mutants grow similarly in in vitro cultures; however, the 1453 mutant has a microcolony phenotype both in vitro and in vivo 3. The 1453 mutant has increased crystal violet staining suggesting biofilm formation. 4. Scanning electron microscopy revealed an abnormal coccus appearance with in increased cell area. 5. Proteomic analysis revealed the 1453 mutant possessed increased production of proteins involved in cell wall processes, cell division, and the Type IV secretion system, and a decrease in proteins involved in amino acid transport/metabolism, carbohydrate metabolism, fatty acid production, and iron acquisition suggesting less preparedness for intracellular survival. 6. RNAseq analysis of bone marrow derived macrophages infected with the mutants revealed the host immune response is greatly reduced with the 1453 mutant infection. These findings support that microlocalization of proteins involved in c-di-GMP homeostasis serve a second messenger to B. melitensisregulating functions of the bacteria during infection of the host.
5
Bacharach, Eran, W. Ian Lipkin, and Avigdor Eldar. Identification of the etiological agent of tilapia disease in the Lake of Galillee. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7597932.bard.
Full textAbstract:
Background to the topic. Tilapines serve as the second most important group of farmed fish worldwide. Massive mortality of wild and cultured tilapia has been observed recently in Israel but the pathogen of this disease has not been identified. We proposed to identify the agent responsible for disease. Major conclusions, solutions, achievements. We characterized the lesions in diseased fish and found that the brain was one of the affected organs. We found conditions to isolate from brains of diseased fish the etiological agent of the tilapia disease and to propagate it in cell culture. This led to the identification of the pathogen as a novel RNA virus, which we named Tilapia Lake Virus (TiLV). Electron microscopy of TiLV revealed virion-like particles and ether/chloroform-sensitivity assays demonstrated that TiLV is enveloped. Low passage TiLV, injected intra-peritoneally to tilapia, induced a disease with over 80% mortality. Cohabitation of healthy with diseased fish demonstrated that the disease is contagious, and that mortalities occur within few days. Fish surviving initial mortality were immune to further TiLV infections, suggesting the mounting of protective immune response. Screening cDNA libraries and high throughput sequencing determined the sequence of TiLV genome. This demonstrated that TiLV is indeed a novel virus and allowed the design of a PCRbased diagnostic test. Implications, both scientific and agricultural. The characterization of a novel, emerging RNA virus that imposes major threat to the tilapia industry, enables the specific identification of the virus in tilapines. This allows prompt screening and surveillance of TiLV, epidemiological studies, and disease containment. This also potentially opens the way for the development of vaccines against TiLV.
6
Droby, Samir, Michael Wisniewski, Ron Porat, and Dumitru Macarisin. Role of Reactive Oxygen Species (ROS) in Tritrophic Interactions in Postharvest Biocontrol Systems. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7594390.bard.
Full textAbstract:
To elucidate the role of ROS in the tri-trophic interactions in postharvest biocontrol systems a detailed molecular and biochemical investigation was undertaken. The application of the yeast biocontrol agent Metschnikowia fructicola, microarray analysis was performed on grapefruit surface wounds using an Affymetrix Citrus GeneChip. the data indicated that 1007 putative unigenes showed significant expression changes following wounding and yeast application relative to wounded controls. The expression of the genes encoding Respiratory burst oxidase (Rbo), mitogen-activated protein kinase (MAPK) and mitogen-activated protein kinase kinase (MAPKK), G-proteins, chitinase (CHI), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and 4-coumarate-CoA ligase (4CL). In contrast, three genes, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), were down-regulated in grapefruit peel tissue treated with yeast cells. The yeast antagonists, Metschnikowia fructicola (strain 277) and Candida oleophila (strain 182) generate relatively high levels of super oxide anion (O2−) following its interaction with wounded fruit surface. Using laser scanning confocal microscopy we observed that the application of M. fructicola and C. oleophila into citrus and apple fruit wounds correlated with an increase in H2O2 accumulation in host tissue. The present data, together with our earlier discovery of the importance of H₂O₂ production in the defense response of citrus flavedo to postharvest pathogens, indicate that the yeast-induced oxidative response in fruit exocarp may be associated with the ability of specific yeast species to serve as biocontrol agents for the management of postharvest diseases. Effect of ROS on yeast cells was also studied. Pretreatment of the yeast, Candida oleophila, with 5 mM H₂O₂ for 30 min (sublethal) increased yeast tolerance to subsequent lethal levels of oxidative stress (50 mM H₂O₂), high temperature (40 °C), and low pH (pH 4). Suppression subtractive hybridization analysis was used to identify genes expressed in yeast in response to sublethal oxidative stress. Transcript levels were confirmed using semi quantitative reverse transcription-PCR. Seven antioxidant genes were up regulated. Pretreatment of the yeast antagonist Candida oleophila with glycine betaine (GB) increases oxidative stress tolerance in the microenvironment of apple wounds. ROS production is greater when yeast antagonists used as biocontrol agents are applied in the wounds. Compared to untreated control yeast cells, GB-treated cells recovered from the oxidative stress environment of apple wounds exhibited less accumulation of ROS and lower levels of oxidative damage to cellular proteins and lipids. Additionally, GB-treated yeast exhibited greater biocontrol activity against Penicillium expansum and Botrytis cinerea, and faster growth in wounds of apple fruits compared to untreated yeast. The expression of major antioxidant genes, including peroxisomal catalase, peroxiredoxin TSA1, and glutathione peroxidase was elevated in the yeast by GB treatment. A mild heat shock (HS) pretreatment (30 min at 40 1C) improved the tolerance of M. fructicola to subsequent high temperature (45 1C, 20–30 min) and oxidative stress (0.4 mol-¹) hydrogen peroxide, 20–60 min). HS-treated yeast cells showed less accumulation of reactive oxygen species (ROS) than non-treated cells in response to both stresses. Additionally, HS-treated yeast exhibited significantly greater (P≥0.0001) biocontrol activity against Penicillium expansum and a significantly faster (Po0.0001) growth rate in wounds of apple fruits stored at 25 1C compared with the performance of untreated yeast cells. Transcription of a trehalose-6-phosphate synthase gene (TPS1) was up regulated in response to HS and trehalose content also increased.
7
Glazer, Itamar, Alice Churchill, Galina Gindin, and Michael Samish. Genomic and Organismal Studies to Elucidate the Mechanisms of Infectivity of Entomopathogenic Fungi to Ticks. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7593382.bard.
Full textAbstract:
The overall goal of this research was to elucidate the factors affecting early development of Metarhizium spp. (previously named M. anisopliae) on ticks or tick cuticle extracts and the molecular basis of these early infection processes. The original objectives were: 1. Characterize the pre-penetration events (adhesion, germination and appressorium formation) of spores of M. anisopliae strains with high or low virulence during tick infection. 2. Create GFP-expressing strains of M. anisopliae tick pathogens having high and low virulence to compare their progress of infection by microscopy. 3. Use microarray analyses, primarily with existing M. anisopliae EST sequences in GenBank, to identify and characterize fungal genes whose expression is regulated in response to host cuticle extracts. Objective 3 was later modified (as approved by BARD) to use RNAseq to characterize the early stages of fungal gene expression during infection of intact host cuticles. This new method provides a massively larger and more informative dataset and allows us to take advantage of a) recently published genomes of Metarhizium robertsii and M. acridum for RNAseq data analysis, and b) newly developed and highly efficient cDNA sequencing technologies that are relatively low cost and, therefore, allow deep sequencing of multiple transcriptome samples. We examined pre-penetration and penetration events that differentiate high and low virulence strains of Metarhizium spp., focusing on spore adhesion, germination, appressorium formation, and penetration of tick integuments. Initiation of fungal infection was compared on susceptible and resistant tick species at different tick developmental stages. In vitro studies comparing the effects of protein and fatty acid profiles from tick cuticle extracts demonstrated that resistant tick cuticles contain higher concentrations of specific lipids that inhibit fungal development than do susceptible tick cuticles, suggesting one mechanism of Ixodidae resistance to fungal entomopathogens (Objective 1). We used molecular markers to determine that the three M. anisopliae strains from Israel that we studied actually were three distinct species. M. brunneum is highly virulent against the tick Rhipicephalus annulatus, M. pingshaense and M. robertsii are intermediate in virulence, and M. majus is of low virulence. We transformed all four Metarhizium species to express GFP and used them in pathogenicity assays against diverse tick species. Key findings were that a) resistant ticks inhibit Metarhizium infection prior to hemocoel invasion by reducing fungal viability on the cuticle surface (Objective 2), as was supported by the in vitro studies of Objective 1, and b) Metarhizium kills susceptible ticks after cuticle penetration but prior to hemocoel colonization. Transcriptome studies of the most virulent species, M. brunneum, are in progress and include analyses of ungerminated conidia and conidia germination and development on a low nutrient medium or on susceptible R. annulatus exoskeleton (Objective 3). We anticipate these studies will contribute to identifying fungal genetic factors that increase virulence and speed of kill and may help reveal tick chemistries that could be included in biocontrol formulations to increase efficacy. Methodologies developed to screen tick cuticle extracts for ability to support conidia germination and development may help in the selection of wild fungi with increased virulence against resistant ticks. The overall knowledge gained should contribute not only to the improvement of tick control but also to the control of other blood-sucking arthropods and related plant pests. Use of bio-based agents for controlling arthropods will contribute to a healthier, more sustainable environment and serve a growing number of organic food farmers.