Relevant bibliographies by topics / BIOLOGICAL STRESS

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  3. Books
  4. Book chapters
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Academic literature on the topic 'BIOLOGICAL STRESS'

Author: Grafiati
Published: 4 June 2021
Last updated: 27 April 2022

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Journal articles on the topic "BIOLOGICAL STRESS"

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Straumanis, John J. "Everyday Biological Stress Mechanisms." Journal of Clinical Psychiatry 64, no. 3 (March 15, 2003): 344–45. http://dx.doi.org/10.4088/jcp.v64n0318b.

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Simm, Andreas, and Lars-Oliver Klotz. "Stress and biological aging." Zeitschrift für Gerontologie und Geriatrie 48, no. 6 (July 24, 2015): 505–10. http://dx.doi.org/10.1007/s00391-015-0928-6.

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Gupta, Sunjai. "Stress—Conceptual and biological aspects." Behaviour Research and Therapy 35, no. 9 (September 1997): 887. http://dx.doi.org/10.1016/s0005-7967(97)84647-5.

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Dishman, Rod K. "Biological Psychology, Exercise, and Stress." Quest 46, no. 1 (February 1994): 28–59. http://dx.doi.org/10.1080/00336297.1994.10484109.

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Ackman, R. G. "Methods in Biological Oxidative Stress." Trends in Food Science & Technology 15, no. 1 (January 2004): 46. http://dx.doi.org/10.1016/j.tifs.2003.09.001.

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Pritchard, John B. "Comparative models and biological stress." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 283, no. 4 (October 1, 2002): R807—R809. http://dx.doi.org/10.1152/ajpregu.00415.2002.

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Eysenck, H. J. "Stress: Conceptual and biological aspects." Personality and Individual Differences 20, no. 6 (June 1996): 810–11. http://dx.doi.org/10.1016/0191-8869(96)83457-x.

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Mathur, R., J. Behari, and K. N. Sharma. "Biological responses of audiogenic stress." International Journal of Biometeorology 30, no. 4 (December 1986): 315–21. http://dx.doi.org/10.1007/bf02189368.

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Bryant, Richard A. "Acute Stress Reactions: Can Biological Responses Predict Posttraumatic Stress Disorder?" CNS Spectrums 8, no. 9 (September 2003): 668–74. http://dx.doi.org/10.1017/s1092852900008853.

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ABSTRACTWhat biological responses characterize those acute trauma reactions that develop into chronic psychiatric disorder? The need to understand the genesis of posttraumatic psychological disorders has resulted in much attention on biological reactions in the initial aftermath of trauma exposure. This review outlines the prevailing biological models of acute stress reaction and critiques the available evidence concerning biological responses to trauma that are associated with subsequent psychological disorder. The roles of peritraumatic dissociation and vulnerability factors for acute stress reaction are also reviewed. The major challenges for research on psychobiological responses to trauma are highlighted.
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Van Den Heuvel, Michael R. "Biological Indicators of Aquatic Ecosystem Stress." Transactions of the American Fisheries Society 133, no. 2 (March 2004): 492. http://dx.doi.org/10.1577/1548-8659(2004)133<0492a:bioaes>2.0.co;2.

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Dissertations / Theses on the topic "BIOLOGICAL STRESS"

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Du, Plessis Keith R. (Keith Roland). "Biological indicators of copper-induced stress in soil." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52719.

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Thesis (MSc)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: The concentrations of copper (Cu) in vineyard soils of the Western Cape range from 0.1 to 20 ppm. However, more than 160 tons of the fungicide copper oxychloride are annually being sprayed on these vineyards. This has raised concerns that Cu may accumulate in these soils, resulting in a negative impact on the soil biological processes, especially since the soils in the Western Cape are slightly acidic, making Cu more mobile and available for soil organisms than would have been the case in alkaline soils. The goal of the initial part of this study was therefore to identify those soil microbial communities indigenous to the Western Cape, which are most susceptible to Cu-induced stress as a result of the addition of copper oxychloride. These potential bioindicators of Cu-induced stress were first searched for in uncultivated agricultural soil from Nietvoorbij experimental farm. Consequently, a series of soil microcosms was prepared by adding various concentrations of Cu as a component of copper oxychloride, to each of eight aliquots of soil: 0 (control), 10, 20, 30, 40, 50, 100, 500 and 1000 ppm. The resulting concentrations of exchangeable Cu in these microcosms were found to be 2 (control), 12,23,34,42,59, 126,516 and 1112 ppm. Selected microbial communities in each microcosm were subsequently monitored over a period of 245 days. It was found that the culturable microbial numbers did not provide a reliable indication of the effect of Cu on community integrity. However, analyses of terminal-restriction fragment length polymorphism (T-RFLP) community fingerprints and especially analyses of the whole community metabolic profiles, revealed that shifts in the soil microbial communities took place as the Cu concentration increased. Direct counts of soil protozoa also revealed that the addition of Cu to the soil impacted negatively on the numbers of these eukaryotes. To confirm these findings in other soil ecosystems, the impact of copper oxychloride on whole community metabolic profiles and protozoan numbers were investigated in soils from Koopmanskloof commercial farm and Nietvoorbij experimental farm. These potential bioindicators were subsequently monitored in a series of soil microcosms prepared for each soil type by adding the estimated amounts of 0 (control), 30, 100 and 1000 ppm Cu as a component of copper oxychloride to the soil. The results confirmed the fmdings that elevated levels of copper impact negatively on the metabolic potential and protozoan numbers of soil. Consequently, it was decided to investigate a combination of protozoan counts and metabolic profiling as a potential bioindicator for Cu-induced stress in soil. Data collected from all the microcosms containing exchangeable Cu concentrations ranging from 1 ppm to 1112 ppm was used to construct a dendrogram using carbon source utilization profiles in combination with protozoan counts. It was found that the microcosms grouped into clusters, which correlated with the concentration of exchangeable Cu in the soil. Under the experimental conditions used in this study, the combination of protozoan counts and metabolic profiling seemed to be a reliable indicator of Cu-induced stress. However, this bioindicator must be further investigated in other soil types using other types of stress inducing pollutants. In addition to the above fmdings it was also found that the numbers of soil protozoa was particularly susceptible to Cu-induced stress in soils with a low soil pH. This is in agreement with the fmdings of others on the bio-availability of heavy metals in low pH soils. In these soils, nutrient cycling as a result of protozoan activity, may therefore be particularly susceptible to the negative impact of copper to the soil.
AFRIKAANSE OPSOMMING: Die konsentrasies van koper (Cu) in wingerdgronde van die Wes-Kaap wissel tussen 0.1 en 20 dpm. Meer as 160 ton van die fungisied koper-oksichloried word egter jaarliks op dié wingerde gespuit, wat kommer laat ontstaan het oor die moontlike akkumulasie van Cu in dié grond en die gevaar van 'n negatiewe impak op die biologiese prosesse in die grond. Die gevaar word vererger deur die feit dat die Wes-Kaapse grond effens suur is, wat Cu meer mobiel en beskikbaar maak vir grondorganismes as wat die geval sou wees in alkaliese grond. Die eerste doelstelling van hierdie studie was dus om die mikrobiese gemeenskappe in die grond, wat inheems is aan die Wes-Kaap, te identifiseer wat die meeste vatbaar is vir Cu-geïnduseerde stres as gevolg van die toevoeging van koper-oksichloried. Hierdie potensiële bioindikatore van Cu-geïnduseerde stres is eerstens gesoek in onbewerkte landbougrond van die Nietvoorbij-proefplaas. 'n Reeks grondmikrokosmosse is gevolglik berei deur verskillende konsentrasies Cu, as 'n komponent van koperoksichloried, by elk van agt hoeveelhede grond te voeg naamlik 0 (kontrole), 10,20, 30, 40, 50, 100, 500 en 1000 dpm. Die gevolglike konsentrasies van uitruilbare Cu in hierdie mikrokosmosse was 2 (kontrole), 12, 23, 34, 42, 59, 126, 516 en 1112 dpm. Geselekteerde mikrobiese gemeenskappe in elke mikrokosmos is vervolgens oor 'n tydperk van 245 dae bestudeer. Daar is gevind dat die kweekbare mikrobiese tellings nie 'n betroubare aanduiding kon gee van die uitwerking van Cu op gemeenskapsintegriteit nie. Die ontledings van terminale-restriksie fragment lengte polymorfisme (T-RFLP) gemeenskapsvingerafdrukke en veral van die metaboliese profiele van die totale gemeenskap, het getoon dat verskuiwings in die grondmikrobiese gemeenskappe plaasgevind het met 'n toename in Cu-konsentrasies. Direkte tellings van grondprotosoë het ook aangedui dat die toevoeging van Cu tot die grond 'n negatiewe uitwerking op die getalle van hierdie eukariote gehad het. Om dié resultate te bevestig, is die impak van koper-oksichloried op die metaboliese profiele van totale gemeenskappe en protosoë-getalle in ander grond-ekosisteme vervolgens bestudeer deur grond van die kommersiële plaas Koopmanskloof en die Nietvoorbij-proefplaas te gebruik. Dié potensiële bioindikatore is vervolgens bestudeer in 'n reeks grondmikrokosmosse, wat vir elke grondtipe voorberei is deur die toevoeging van beraamde hoeveelhede van 0 (kontrole), 30, 100 en 1000 dpm Cu as 'n komponent van koper-oksichloried. Die resultate het die bevindings bevestig dat verhoogde vlakke van Cu 'n negatiewe uitwerking het op die metaboliese potensiaal en op die protosoëgetalle in die grond. Daar is gevolglik besluit om 'n kombinasie van protosoë-tellings en metaboliese profiele te ondersoek as 'n potensiële bioindikator van Cu-geïnduseerde stres in grond. Data van al die mikrokosmosse wat uitruilbare Cu bevat, wisselend van 1 dpm tot 1112 dpm, is gebruik om 'n dendrogram te konstrueer wat koolstofbronbenuttingsprofiele in kombinasie met protosoë tellings gebruik. Daar is gevind dat die mikrokosmosse groepe vorm wat korrelleer met die konsentrasie uitruilbare Cu in die grond. Onder die eksperimentele kondisies wat in dié studie gebruik is, wil dit voorkom of die kombinasie van protosoë-tellings en metaboliese profiele 'n betroubare indikator van Cugeïnduseerde stres is. Hierdie bioindikator moet egter verder in ander grondtipes en met ander tipes stres-induserende besoedeling ondersoek word. By bogenoemde bevindings is daar ook gevind dat die getalle grondprotosoë besonder gevoelig is vir Cu-geïnduseerde stres in grond met In lae pH. Dit is in ooreenstemming met die bevindings van andere met betrekking tot die bio-beskikbaarheid van swaar metale in grond met 'n lae pH. In dié tipe grond mag nutriëntsiklering as gevolg van protosoë aktiwiteit besonder gevoelig wees vir die negatiewe uitwerking van koper in die grond.
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Karlsson, Louise. "Stress : From a biological, social, and psychological perspective." Thesis, Högskolan i Skövde, Institutionen för biovetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-16104.

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Over the years stress has been a term lacking one clear and specific definition. In general, the term stress has been used mostly as an explanation of a response or reaction to a stressor. A stressor can be of both physiological and behavioral character. The experience of stress can occur both due to a real or a perceived stressor. In this literature review, the concept of stress is viewed with insights from biological, psychological, and social perspectives. The stress response is described biologically with the central nervous system (CNS), the brain, and the hypothalamic-pituitary-adrenal (HPA) axis. Social and psychological stress are concepts related to how stress is perceived by the mind and due to social surroundings which is described in relation to social support, self-efficacy, the locus of control and cognitive appraisal. Dealing with stress can be done through coping which refers to the individual capacity to handle a stressor and has generally been divided into two categories, active/passive coping and problem-focused/emotion-focused coping. Depending on the individual resources to cope with a stressor and the ability to decrease the stress response when needed, the long-term effects of stress can therefore vary between individuals. It has been found that positive coping (known as reducing stress) can increase the anterior cingulate cortex (ACC) volume and decrease anxiety and depression. The prefrontal cortex (PFC), the hippocampus, and the amygdala are closely linked to the ACC and affect emotions, learning, and memory related to the stress response.
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Hecht, Vivian (Vivian Chaya). "Biophysical responses of lymphocytes to environmental stress." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103693.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biological Engineering, 2016.
Cataloged from PDF version of thesis. "February 2016."
Includes bibliographical references (pages 139-151).
Cellular biophysical properties both reflect and influence cell state. These parameters represent the consequences of the interactions of multiple molecular events, and thus may reveal information otherwise obscured when measuring individual pathways in isolation. Previous work has demonstrated how precise measurements of certain of these properties, such as mass, volume, density and deformability using a suspended microchannel resonator (SMR) can help characterize cellular behavior and physiological role. Here, we expand upon this previous work to demonstrate the necessity of measuring multiple parameters simultaneously to fully determine cellular responses to environmental perturbations, and describe a situation in which changes to density and size promote survival under conditions of limited nutrient availability. We first investigate the relationship between cell density, volume, buoyant mass, and passage time through a narrow constriction under a variety of environmental stresses. Osmotic stress significantly affects density and volume, as previously shown. In contrast to density and volume, the effect of an osmotic challenge on passage time is relatively small. Deformability, determined by comparing passage times for cells with similar volume, exhibits a strong dependence on osmolarity, indicating that passage time alone does not always provide a meaningful proxy for deformability. Finally, we find that protein synthesis inhibition, cell cycle arrest, protein kinase inhibition, and cytoskeletal disruption result in unexpected relationships between deformability, density, and volume. Taken together, our results suggest that measuring multiple biophysical parameters can detect unique characteristics that more specifically reflect cellular behaviors. We next examine how cellular biophysical changes occurring immediately after growth factor depletion in lymphocytes promote adaptation to reduced nutrient uptake. We describe an acute biophysical response to growth factor withdrawal, characterized by a simultaneous decrease in cell volume and increase in cell density prior to autophagy initiation, observed in both FL5.12 cells depleted of IL-3 and primary CD8+ T cells depleted of IL-2 and differentiating towards memory cells. The response reduces cell surface area to minimize energy expenditure while conserving biomass, suggesting that the biophysical properties of cells can be regulated to promote survival under conditions of nutrient stress.
by Vivian Hecht.
Ph. D.
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Lamb, Angharad. "Mathematical Modelling of the Biological Stress Response to Chronium." Thesis, University of Nottingham, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517846.

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Lu, Buyu. "Hormones of stress and control of adipocyte biological "colour"." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/46849/.

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The family of “stress” peptides that includes CRH and UCNs are emerging as important regulators of the homeostatic mechanisms regulating energy balance and metabolism. These peptides exert well documented central anorectic and thermogenic actions in controlling food uptake and optimise energy losses. Furthermore, CRH acting through specific G-protein coupled receptors, CRH-R1 and R2 can target multiple peripheral tissues such as skeletal muscle and adipose tissue to influence important metabolic pathways. Two types of adipose tissue exist in mammals: WAT and BAT. Since WAT is the largest energy reserve in mammals and BAT can utilize energy through adaptive thermogenesis, one of the goals in this study was to identify the presence of CRH system components in adipose tissue. Real time RT-PCR and immunofluorescence demonstrated that CRH-Rs as well as CRH, UCN-I, and UCN-II are expressed in both WAT and BAT, raising the possibility that CRH and UCNs are important regulators of energy storage and adaptive thermogenesis. Also the functional roles of CRH-Rs in adipose tissue were investigated. Using an experimental paradigm the T37i fibroblast that can differentiate into brown adipocyte, it was demonstrated that CRH at low (nanomolar) but not high (submicromolar) concentrations stimulated a signaling pathway involving the AC/cAMP/PKA/AMPK signaling cascade that regulates downstream phosphorylation of HSL. This was associated with a significant translocation of HSL toward lipid droplets and association with perilipin, as demonstrated with immunofluorescence. Studies applying quantitative RT-PCR also suggested that CRH-R1 appears to regulate genes important for adaptive thermogenesis, whereas CRH-R2 likely regulates brown adipocyte formation. Further analysis using an experimental paradigm the 3T3L1 fibroblast that can differentiate into white adipocyte showed that exposure of 3T3L1 cells to UCN-II (a specific CRH-R2 agonist) or NBI-27914 (a CRH-R1 specific antagonist) were able to induce morphological and biochemical characteristics suggesting adipocyte differentiation to a “beige” phenotype in white preadipocytes/adipocytes. Thus, CRH-R1 and R2 could be of potential importance in maintenance of energy homeostasis. Moreover, in vivo analysis showed that CRH system seems to demonstrate a certain degree of plasticity in response to stress perturbation. For instance, HFD significantly repressed the expression of CRH-Rs and their agonists, whereas food deprivation dramatically increased their expression. The analysis of quantitative RTPCR demonstrated that this activation of CRH system might be associated with induction of ‘beige’ cells in white fat depots. Since CRH-R1 KO mice displayed a lean phenotype and resistance to HFD-induced fat accumulation and these phenotypes can be reversed by supplementation of corticosterone, role of CRH-R2 in adipose tissue of these KO mice was investigated. Data showed that CRH-R2 activation likely induced BAT activity and transdifferentiation from WAT to BAT in CRH-R1 KO mice. Corticosterone reversed these changes in KO mice via potential suppression of CRH-R2.
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Erickson, Erika M. "The growth and stress response characterization of Synechococcus WH8109 cyanobacteria." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/61214.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 60-64).
Oceanic cyanobacteria are amongst the most populous species on the planet and have been found in every ocean around the world. These photosynthetic organisms play a major role in the global carbon cycle. They have adapted to a number of different temperature, light, and nutrient niches. However, as important primary producers in the oceans, these organisms play a vital role which may be threatened by global climate change and pollution. As research on cyanobacterial species progresses, these organisms have been found to show promise as potential sources of biofuel, renewable energy, and agents for bioremediation. In order to utilize these organisms for future engineering applications and basic scientific research, it is important to be able to grow the organism in a stable and reproducible manner. This research characterizes the growth of Synechococcus WH8109 in the laboratory. In the laboratory, cell culture densities of greater than 109 cells/mL with a doubling time of approximately 24 hours were achieved when grown at 28'C with a 24 hour light cycle in sea water and artificial salt water media. Not only did cyanobacteria evolve long before their distant enteric cousins, but they harness nearly all of their energy through photosynthesis. The photosystem is constantly subjected to photo-oxidative damage and degradation. Interesting insight may be gained by studying this complex repair process in the bacterial counterpart to plants, prior to applying these concepts to higher order plant species. Chaperones have been implicated in this repair process. In order to better characterize the stress response of WH8109, I have also isolated the Synechococcus homologue of GroEL using anion exchange and gel filtration chromatography and sucrose gradient centrifugation. The expression levels of this chaperone were analyzed under normal and stress conditions and they have been shown to respond to heat shock and infection.
by Erika M. Erickson.
M.Eng.
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de, la Haba Fonteboa Carlos. "Effects of oxidative stress on plasma membrane fluidity: biological consequences." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/311421.

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El estrés oxidativo (OS) es característico de muchas enfermedades y se produce cuando hay un desequilibrio entre oxidantes y antioxidantes, lo cual favorece un estado oxidativo que genera especies reactivas de oxígeno y de nitrógeno. Los lípidos de la membrana plasmática son dianas preferentes del OS y ello tiene como consecuencia la peroxidación lipídica. Este proceso modifica propiedades de la membrana tales como su fluidez, característica física muy importante conocida por modular la localización de las proteínas de membrana y las uniones receptor-ligando. Objetivos: 1) Evaluar el efecto del OS en la regionalización de la fluidez en la membrana plasmática de células vivas tales como macrófagos THP-1 y linfocitos MEC-1, de manera individualizada. 2) Analizar, en estas células, la relación entre la peroxidación lipídica y la fluidez de membrana. 3) Estudiar el efecto del OS sobre la unión receptor-ligando y sobre la fluidez de membrana: lipopolisacárido/receptores de tipo Toll (TLR2/4) en macrófagos y progesterone-induced blocking factor (PIBF)/PIBF-receptor en linfocitos. Material y Métodos: Se estandarizó la metodología two-photon microscopy por primera vez en la Universidad Autónoma de Barcelona, para analizar la fluidez de membrana en células vivas individuales. Conjuntamente se ha desarrollado un nuevo software capaz de medir el tamaño y el número de los dominios lipídicos de membrana. El OS se indujo mediante H2O2 y se empleó la sonda fluorescente Laurdan para detectar las diferencias de fluidez en la membrana plasmática. Se utilizaron LPS y PIBF soluble en macrófagos y linfocitos respectivamente, para analizar interacciones receptor-ligando en condiciones OS. Resultados: En los macrófagos se observó un aumento significativo, dependiente de la concentración de H2O2, en la frecuencia de regiones lipídicas rígidas principalmente compuestas por dominios lipid raft, a expensas de las regiones de fluidez intermedia. Asimismo, se detectó en condiciones de OS, un mayor número, aunque no un mayor tamaño, de dominios lipid raft. La activación de macrófagos con LPS incrementó la frecuencia de regiones fluidas en las membranas, efecto que fue inhibido en condiciones de OS. En cuanto a la función de los macrófagos, se detectó una disminución en la secreción de TNFα en condiciones oxidantes. En los linfocitos se observó un aumentó significativo en la frecuencia de regiones lipídicas rígidas, a expensas de las regiones fluidas, en condiciones de OS. Por otro lado, la unión del PIBF a su receptor, provocó un aumentó en la rigidez de la membrana plasmática debido al clustering de dominios lipid raft. Por el contrario, cuando se indujo OS en linfocitos en presencia de PIBF, se inhibió el clustering de dominios lipid raft y también disminuyó el reconocimiento del receptor de PIBF a su ligando. Conclusiones: 1) Se ha evaluado en células vivas, de forma individual, la dinámica lipídica de la membrana plasmática. 2) Una consecuencia general importante es que, durante el OS, tanto en macrófagos como en linfocitos la membrana plasmática se vuelve más rígida. 3) La fluidez de membrana cambia de forma distinta en los dos tipos celulares estudiados, como consecuencia de las interacciones receptor-ligando: durante la unión LPS-TLR2/4 se observó un aumento en la fluidez de la membrana plasmática de los macrófagos y, por el contrario, durante la unión PIBF/PIBF-R la membrana de los linfocitos se rigidificó, aumentando el clustering de los dominios lipid raft. 4) No obstante, en ambos casos el OS inhibió los cambios en la fluidez de membrana inducidos por la unión receptor-ligando.
Oxidative stress is present in many diseases and it is produced in cells when an imbalance between oxidants and antioxidants occurs, favoring an oxidant status which produce reactive oxygen and nitrogen species. Lipids in plasma membrane are one of the preferential targets giving rise to lipid peroxidation. This process modifies membrane properties such as membrane fluidity, a very important physical feature known to modulate membrane protein localization and receptor-ligand binding. Aims: 1) To evaluate the effect of oxidative stress on plasma membrane fluidity regionalization of single living THP-1 macrophages and MEC-1 lymphocytes. 2) To analyze, in these cells, the relationship between lipid peroxidation and membrane fluidity. 3) To study the effect of oxidative stress on receptor-ligand binding and membrane fluidity: lipopolysaccharide/toll-like receptors (TLR2/4) in macrophages and progesterone-induced blocking factor (PIBF)/PIBF-receptor in lymphocytes. Material and Methods: Two-photon microscopy was standardized for the first time in Universidad Autónoma de Barcelona by our laboratory, to analyze membrane fluidity in single living cells. It was also developed a new software application to analyze membrane lipid domain size and number. Cellular oxidative stress was induced by H2O2; the fluorescent probe Laurdan was applied to evaluate plasma membrane fluidity changes. LPS in macrophages or soluble PIBF in lymphocytes were used to analyze receptor-ligand interactions under oxidative stress. Results: Macrophages showed a significant H2O2 concentration dependent increase in the frequency of rigid lipid regions, mainly attributable to lipid rafts, at the expense of the intermediate fluidity regions. Under oxidative stress conditions, an increase in number, but not in size, of lipid raft domains was detected. Macrophage activation by LPS increase the frequency of fluid regions, which was inhibited by oxidative stress. Concerning macrophage function, secretion of TNFα under oxidative conditions was decreased. Lymphocytes showed a significant increase in the frequency of rigid lipid regions, at the expense of fluid regions, under oxidative stress conditions. Upon PIBF binding to its receptor, lymphocyte plasma membrane became more rigid due to clustering of lipid rafts. However, when PIBF bound lymphocytes were placed in oxidizing conditions, lipid raft clustering was inhibited and PIBF binding to its receptor was also decreased. Conclusions: 1) In single living cells plasma membrane lipid dynamics was evaluated. 2) An important general consequence of oxidative stress is that both in macrophages and lymphocytes plasma membrane becomes more rigid. 3) Receptor-ligand interactions have an effect on membrane fluidity, which vary greatly between the two cell types studied: macrophages and lymphocytes. Upon receptor-ligand binding, macrophage plasma membrane became more fluid while lymphocytes plasma membrane became more rigid. Our results suggest that lipid raft clustering is linked to cell function: upon PIBF binding to its receptor lipid raft clustering occurs in lymphocytes; however, upon LPS/TLR2/4 lipid raft clustering does not occur in macrophages. 4) Nevertheless, the effect induced by receptor-ligand binding on membrane fluidity was inhibited during oxidative stress in both cases.
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O'Keeffe, Stephen George. "The mechanics of growth and residual stress in biological cylinders." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:493473f6-b952-4ce3-a2e5-1a79e97afb7f.

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Biological tissue differs from other materials in many ways. Perhaps the most crucial difference is its ability to grow. Growth processes may give rise to stresses that exist in a body in the absence of applied loads and these are known as residual stresses. Residual stress is present in many biological systems and can have important consequences on the mechanical response of a body. Mathematical models of biological structures must therefore be able to capture accurately the effects of differential growth and residual stress, since greater understanding of the roles of these phenomena may have applications in many fields. In addition to residual stresses, biological structures often have a complex morphology. The theory of 3-D elasticity is analytically tractable in modelling mechanical properties in simple geometries such as a cylinder. On the other hand, rod theory is well-suited for geometrically-complex deformations, but is unable to account for residual stress. In this thesis, we aim to develop a map between the two frameworks. Firstly, we use 3-D elasticity to determine effective mechanical properties of a growing cylinder and map them into an effective rod. Secondly, we consider a growing filament embedded in an elastic foundation. Here, we estimate the degree of transverse reinforcement the foundation confers on the filament in terms of its material properties. Finally, to gain a greater understanding of the role of residual stress in biological structures, we consider a case study: the chameleon's tongue. In particular we consider the role of residual stress and anisotropy in aiding the rapid projection of the tongue during prey capture. We construct a mechanical model of the tongue and use it to investigate a proposed mechanism of projection by means of an energy balance argument.
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Davis, Nick K. (Nicholas K. ). "Epitranscriptomics : translational regulation of metabolism, drug resistance and proteostasis during cellular stress." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/128394.

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This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: Sc. D., Massachusetts Institute of Technology, Department of Biological Engineering, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
The epitranscriptome -- the naturally occurring system of chemical modifications on ribonucleic acid (RNA) --
is an emerging frontier of research into how changes in the cellular environment are coupled with global rates of protein synthesis. Here we report the development of new analytical and computational approaches to study mechanisms of epitranscriptomic regulation and function in the context of (1) phenotypic antibiotic resistance in bacteria, and (2) proteostasis in eukaryotes. While at least 11 major classes of RNA have been identified to date, this work focuses on transfer RNA (tRNA), the most diversely modified species of RNA that plays a central role in the initiation, elongation and termination of translation. To provide context for investigating the epitranscriptomic regulation of microbial adaptation, we first use multivariate statistical modelling to integrate time-resolved, systems-level analyses of mycobacterial persistence using an in vitro model of tuberculosis infection.
Combining biochemical characterization of cellular pH and redox state, metabolic phenotyping, time-course metabolomics, whole-genome transcriptomics, and quantitative proteomics, we demonstrate that starved Mycobacterium bovis BCG (BCG) adapts to starvation by entering a ketotic state that results from coordinated metabolic shifts towards lipolysis and fatty acid [beta]-oxidation. We also show that management of toxic ketone body intermediates appears to be mediated by cytochrome P450 (CYP)-linked ketolysis and carbon cycling through CO₂ fixation, as evidenced by elevated endogenous reactive oxygen species production during starvation and the sensitivity of starved persisters to well-known CYP poisons. Using this model of mycobacterial pathogenesis, we next describe how BCG responds to nutrient deprivation by reprogramming the tRNA epitranscriptome to mediate selective translation of codon-biased stress response genes.
We discuss how insights from preliminary experiments with a new in-house method, Absolute QUAntification RNA-Seq (AQUA RNA-Seq), will deepen our mechanistic understanding of this alternative genetic code, and also describe a strategy for chemotherapeutic intervention to reverse phenotypic drug resistance. Finally, we detail the development of a new high-throughput platform to identify and quantify the role of the epitranscriptome in translational fidelity in Saccharomyces cerevisiae. Our results indicate that loss of certain tRNA-modifying enzymes induces the aggregation of stress response proteins with amino acid misincorporations that map to specific codon sites.
The research conducted under this thesis (1) advances our fundamental understanding of how genes are regulated at the level of translation, (2) establishes the role of the epitranscriptome in regulating cellular adaptation to physiological stringency, and (3) provides mechanistic insights into how the epitranscriptome can be engineered for the development of new RNA-targeted medicines.
by Nick K. Davis.
Sc. D.
Sc.D. Massachusetts Institute of Technology, Department of Biological Engineering
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Kalkeren, Antje Afien van. "Stress-induced decrease of intestinal barrier functioning: a general biological phenomenon?" [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2002. http://dare.uva.nl/document/65661.

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Books on the topic "BIOLOGICAL STRESS"

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name, No. Methods in biological oxidative stress. Totowa, NJ: Humana Press, 2003.

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Stress: Conceptual and biological aspects. Chichester: Wiley, 1995.

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Hensley, Kenneth, and Robert A. Floyd. Methods in Biological Oxidative Stress. New Jersey: Humana Press, 2003. http://dx.doi.org/10.1385/1592594247.

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R, Lovallo William, ed. Stress & health: Biological and psychological interactions. 2nd ed. Thousand Oaks, Calif: Sage Publications, 2005.

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Stress & health: Biological and psychological interactions. Thousand Oaks, Calif: Sage Publications, 1997.

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Berliner, Lawrence J., and Narasimham L. Parinandi, eds. Measuring Oxidants and Oxidative Stress in Biological Systems. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-47318-1.

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Microbial water stress physiology: Principles and perspectives. Chichester: Wiley, 1990.

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Gutiérrez-López, Gustavo F., Liliana Alamilla-Beltrán, María del Pilar Buera, Jorge Welti-Chanes, Efrén Parada-Arias, and Gustavo V. Barbosa-Cánovas, eds. Water Stress in Biological, Chemical, Pharmaceutical and Food Systems. New York, NY: Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4939-2578-0.

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Social and biological roles of language: The psychology of justification. London: Academic Press, 1985.

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Environmental stress and behavioural adaptation. London: Croom Helm, 1985.

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Book chapters on the topic "BIOLOGICAL STRESS"

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Aggarwal, Anjali, and Ramesh Upadhyay. "Biological Rhythms." In Heat Stress and Animal Productivity, 137–67. India: Springer India, 2012. http://dx.doi.org/10.1007/978-81-322-0879-2_6.

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Kudler, Harold, and Jonathan R. T. Davidson. "General Principles of Biological Intervention Following Trauma." In Traumatic Stress, 73–98. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-1076-9_4.

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Koh, Kyung Bong. "Biological Mechanisms of Somatization." In Stress and Somatic Symptoms, 95–103. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-02783-4_9.

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Mckersie, Bryan D., and Ya’acov Y. Leshem. "The overall implications of biological stress." In Stress and Stress Coping in Cultivated Plants, 1–14. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-017-3093-8_1.

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He, Ming-Liang, Qianya Wan, Dan Song, and Betsy He. "Stress Proteins: Biological Functions, Human Diseases, and Virus Infections." In Oxidative Stress, 77–102. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0522-2_4.

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Marmot, M., and E. Brunner. "Epidemiological Applications of Long-Term Stress in Daily Life." In Everyday Biological Stress Mechanisms, 80–90. Basel: KARGER, 2001. http://dx.doi.org/10.1159/000059277.

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Theorell, T. "Introduction: Biological Markers of Long-Term Effects of Naturally Occurring Stress." In Everyday Biological Stress Mechanisms, 1–6. Basel: KARGER, 2001. http://dx.doi.org/10.1159/000059270.

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Kelly, S. J., and C. Hertzman. "Finding a Stress Measure in the Literature and Taking It into the Field." In Everyday Biological Stress Mechanisms, 7–16. Basel: KARGER, 2001. http://dx.doi.org/10.1159/000059272.

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Cleare, A. J. "Regulatory Disturbance of Energy." In Everyday Biological Stress Mechanisms, 17–34. Basel: KARGER, 2001. http://dx.doi.org/10.1159/000059273.

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Shimomitsu, T., and Y. Odagiri. "Endocrinological Assessment of Extreme Stress." In Everyday Biological Stress Mechanisms, 35–51. Basel: KARGER, 2001. http://dx.doi.org/10.1159/000059274.

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Conference papers on the topic "BIOLOGICAL STRESS"

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Seiter, Natasha. "Mindful Partnering and Lesser Biological Stress." In 7th International Conference on Spirituality and Psychology. Tomorrow People Organization, 2022. http://dx.doi.org/10.52987/icsp.2022.006.

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Abstract Mindful partnering is a newly conceptualized construct to measure interpersonal mindfulness in the relationship with one's intimate partner. Mindful partnering is characterized by mindful awareness toward one’s partner as well as compassion and acceptance of one’s partner. We hypothesized that higher levels of mindful partnering would be associated with lesser physiological reactivity to relationship conflict (i.e., less biological stress during relationship conflict). Seventeen couple pairs (N= 34) visited the laboratory to complete several tasks, including questionnaires and a conflict discussion in which they discussed the largest areas of conflict in their relationship. Participants had their Respiratory Sinus Arrythmia (RSA), a measure of nervous system activation, measured during the baseline period and conflict discussion. Participants completed the Mindful Partnering Measure (MPM) to measure the extent to which one demonstrates mindful partnering in their relationship with their romantic partner, including the subscales of MPM- Mindful Awareness and MPM- Acceptance/Compassion. Regression analyses suggested that MPM-Mindful Awareness significantly predicted partner’s greater RSA, indicating that 9% of the variance in RSA was accounted for by partner’s MPM- mindful awareness (a small effect), suggesting greater relaxation and a less pronounced stress response. These results suggest that when one’s partner is fully present and attentive, it may relieve the potential stress of marital disagreement. Being present with full attention in this way may soothe a partner’s nervous system by creating a feeling of being fully listened to and understood in the context of conflict. Keywords: Mindfulness, Marriage, Marital Conflict, Respiratory Sinus Arrythmia, Physiological Reactivity
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"Effects of Noise Stress on Liver Function." In International Institute of Chemical, Biological & Environmental Engineering. International Institute of Chemical, Biological & Environmental Engineering, 2015. http://dx.doi.org/10.15242/iicbe.c0615078.

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Wakida, Shin-ichi. "Salivary ISFET sensors for stress monitoring." In Advanced Environmental, Chemical, and Biological Sensing Technologies XV, edited by Tuan Vo-Dinh. SPIE, 2019. http://dx.doi.org/10.1117/12.2518851.

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"Evaluation of Oxidative Stress during Toxoplasmosis in Pregnant Women." In International Conference on Chemical, Agricultural and Biological Sciences. Emirates Research Publishing, 2015. http://dx.doi.org/10.17758/erpub.er915075.

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Zhao, Guoqing, Bin Hu, Xiaowei Li, Chengsheng Mao, and Rui Huang. "A Pervasive Stress Monitoring System Based on Biological Signals." In 2013 Ninth International Conference on Intelligent Information Hiding and Multimedia Signal Processing (IIH-MSP). IEEE, 2013. http://dx.doi.org/10.1109/iih-msp.2013.137.

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Rabin, Yoed, and Paul S. Steif. "Thermal Stress Modeling of the Freezing of Biological Tissue." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0601.

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Abstract The extent of injury of biological tissues by freezing is influenced by many factors such as the cooling rate, the thawing rate, the minimal temperature achieved, the number of repeated freezing thawing cycles, and the presence of cryoprotectants. The mechanisms of cryo-destruction may generally be separated into two groups; the first is related to the freezing process within the phase transition temperature range (typically between 0 and −22°C), while the second group is related to further destruction after phase transition has completed. Destruction mechanisms of the first group are related to heat transfer, mass transfer, and chemical equilibrium in the intracellular and extracellular solutions. Destruction mechanisms after the phase transition has been completed are related to mechanical stresses in the frozen state. Mechanical stresses develop when changes in density occur nonuniformly in the tissue, a consequence of the presence of temperature gradients. The current presentation gives an up-to-date report on ongoing research to model the freezing of biological tissues and to measure their physical properties. The mechanical boundary condition at the freezing front is emphasized in this presentation, and examples for typical cases of cryosurgery and cryopreservation are discussed.
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"Soybean (Glycine Max L.)Growth Enhancement under Water Stress Conditions." In International Conference on Chemical, Agricultural and Biological Sciences. Emirates Research Publishing, 2015. http://dx.doi.org/10.17758/erpub.er915116.

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Enshaeian, Alireza, Matthew Belding, and Piervincenzo Rizzo. "A novel vibration-based method to measure stress in rails." In Health Monitoring of Structural and Biological Systems XVI, edited by Paul Fromme and Zhongqing Su. SPIE, 2022. http://dx.doi.org/10.1117/12.2612296.

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El-Esawi, Mohamed A. "Functional Role of NAC Transcription Factors in Stress Responses and Genetic Diversity of Rice Plants Grown under Salt Stress Conditions." In 1st International Electronic Conference on Biological Diversity, Ecology and Evolution. Basel, Switzerland: MDPI, 2021. http://dx.doi.org/10.3390/bdee2021-09532.

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Cheong, Vee San, Aadil Mumith, Melanie Coathup, Gordon Blunn, and Paul Fromme. "Bone remodeling in additive manufactured porous implants changes the stress distribution." In Health Monitoring of Structural and Biological Systems IX, edited by Paul Fromme and Zhongqing Su. SPIE, 2020. http://dx.doi.org/10.1117/12.2558093.

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Reports on the topic "BIOLOGICAL STRESS"

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Starosciak, Amy K. Effects of Stress and Social Enrichment on Alcohol Intake, Biological and Psychological Stress Responses in Rats. Fort Belvoir, VA: Defense Technical Information Center, May 2010. http://dx.doi.org/10.21236/ad1013421.

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Kim, Kwan-Suk, Eui-Soo Kim, Jacob T. Seibert, Aileen F. Keating, Lance H. Baumgard, Jason W. Ross, and Max F. Rothschild. Genome-Wide Association Analyses of Biological Responses to Heat Stress in Pigs. Ames (Iowa): Iowa State University, January 2015. http://dx.doi.org/10.31274/ans_air-180814-1343.

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Yull, Fiona. Nf-Kappab as a Critical Biological Link Between Psychological Stress and Breast Cancer. Fort Belvoir, VA: Defense Technical Information Center, November 2007. http://dx.doi.org/10.21236/ada476464.

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Shkolnikova, Maria A., Svetlana A. Shalnova, Vladimir M. Shkolnikov, Victoria A. Metelskaya, Alexander D. Deev, Evgueni M. Andreev, Dmitri A. Jdanov, and James W. Vaupel. Biological mechanisms of disease and death in Moscow: rationale and design of the survey on Stress Aging and Health in Russia (SAHR). Rostock: Max Planck Institute for Demographic Research, June 2009. http://dx.doi.org/10.4054/mpidr-wp-2009-016.

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Tomar, Vikas. An Investigation into the Effects of Interface Stress and Interfacial Arrangement on Temperature Dependent Thermal Properties of a Biological and a Biomimetic Material. Office of Scientific and Technical Information (OSTI), January 2015. http://dx.doi.org/10.2172/1167156.

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Crisosto, Carlos, Susan Lurie, Haya Friedman, Ebenezer Ogundiwin, Cameron Peace, and George Manganaris. Biological Systems Approach to Developing Mealiness-free Peach and Nectarine Fruit. United States Department of Agriculture, 2007. http://dx.doi.org/10.32747/2007.7592650.bard.

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Peach and nectarine production worldwide is increasing; however consumption is flat or declining because of the inconsistent eating quality experienced by consumers. The main factor for this inconsistent quality is mealiness or woolliness, a form of chilling injury that develops following shipping periods in the global fruit market today. Our research groups have devised various postharvest methods to prolong storage life, including controlled atmosphere and delayed storage; however, these treatments only delay mealiness. Mealiness texture results from disruption of the normal ripening process involving disassembly of cell wall material, and creates a soft fruit texture that is dry and grainy instead of juicy and smooth. Solving this problem is a prerequisite for increasing the demand for fresh peach and nectarine. Two approaches were used to reveal genes and their associated biochemical processes that can confer resistance to mealiness or wooliness. At the Volcani Center, Israel, a nectarine cultivar and the peach cultivar (isogenetic materials) from which the nectarine cultivar spontaneously arose, and at the Kearney Agricultural Center of UC Davis, USA, a peach population that segregates for quantitative resistance to mealiness was used for dissecting the genetic components of mealiness development. During our project we have conducted research integrating the information from phenotypic, biochemical and gene expression studies, proposed possible candidate genes and SNPs-QTLs mapping that are involved in reducing peach mealiness susceptibility. Numerous genes related to ethylene biosynthesis and its signal transduction, cell wall structure and metabolism, stress response, different transcription factor families were detected as being differentially accumulated in the cold-treated samples of these sensitive and less sensitive genotypes. The ability to produce ethylene and keep active genes involved in ethylene signaling, GTP-binding protein, EIN-3 binding protein and an ethylene receptor and activation of ethyleneresponsive fruit ripening genes during cold storage provided greater resistance to CI. Interestingly, in the functional category of genes differentially expressed at harvest, less chilling sensitive cultivar had more genes in categories related to antioxidant and heat sock proteins/chaperones that may help fruit to adapt to low temperature stress. The specific objectives of the proposed research were to: characterize the phenotypes and cell wall components of the two resistant systems in response to mealiness- inducing conditions; identify commonalities and specific differences in cell wall proteins and the transcriptome that are associated with low mealiness incidence; integrate the information from phenotypic, biochemical, and gene expression studies to identify candidate genes that are involved in reducing mealiness susceptibility; locate these genes in the Prunus genome; and associate the genes with genomic regions conferring quantitative genetic variation for mealiness resistance. By doing this we will locate genetic markers for mealiness development, essential tools for selection of mealiness resistant peach lines with improved fruit storability and quality. In our research, QTLs have been located in our peach SNPs map, and proposed candidate genes obtained from the integrated result of phenotypic, biochemical and gene expression analysis are being identified in our QTLs as an approach searching for consistent assistant markers for peach breeding programs.
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Zilinskas, Barbara A., Doron Holland, Yuval Eshdat, and Gozal Ben-Hayyim. Production of Stress Tolerant Plants by Overproduction of Enzymatic Oxyradical Scavengers. United States Department of Agriculture, May 1993. http://dx.doi.org/10.32747/1993.7568751.bard.

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Most of the objectives that were outlined in the original proposal have been met with two exceptions. Briefly, our goals were to: (1) constract transgenic tobacco plants which overproduce one or more of the enzymatic oxyradical scavengers and associated ancillary enzymes, including superoxide dismutase, ascorbate peroxidase, glutathione peroxidase, glutathione reductase, and monodehydrascorbate reductase; (2) evaluate the tolerance of these transgenic plants to oxidative stress; and (3) extend these studies to an agronomically important crop such as citrus. As can be seen i the following pages, our objectives (1) and (2) have been achieved, although transgenic lines overexpressing phospholipid hydroperoxidase glutathione peroxidase (PHGPX) were not obtained and our evidence to date suggests that constitutive overexpressing of the enzyme is probably lethal. Howeever, transgenic tobacco expressing the antisense construct for PHGPX were obtained. Tobacco plants overexpressing ascorbate peroxidase and those sensesuppressing monodehydroascorbate reductase are more tolerant to oxidative stress, as mediated by the redox-cycling agent paraquant; in contrast, plants expressing the PHGPX-antisense construct are more sensitive to paraquat. Additional research is warranted on each of the six types of transgenic lines which we generated with regard to their tolerance to saline stress. Until recently, attempts to transform citrus were not very successful, and thus additional attention is currently being directed at objective (3). We are optimistic that use of the plant transformation vector, pBIN, will lead to stable transgenic citrus, as preliminary experiments demonstrate stable expression of the GUS reporter gene. Other important contributions resulting from this BARD project include the biochemical characterization of the first plant phospholipid glutathione peroxidase and the biochemical and molecular analysis of another key antioxidant enzyme, monodehydroascorbate reductase. Overall this BARD-supported project was quite successful, and the biological resource of numerous transgenic lines which have altered levels of antioxidant enzymes should be valuable for years to come.
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Lundgren, Jonathan, Moshe Coll, and James Harwood. Biological control of cereal aphids in wheat: Implications of alternative foods and intraguild predation. United States Department of Agriculture, October 2014. http://dx.doi.org/10.32747/2014.7699858.bard.

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The overall objective of this proposal is to understand how realistic strategies for incorporating alternative foods into wheat fields affect the intraguild (IG) interactions of omnivorous and carnivorous predators and their efficacy as biological control agents. Cereal aphids are a primary pest of wheat throughout much of the world. Naturally occurring predator communities consume large quantities of cereal aphids in wheat, and are partitioned into aphid specialists and omnivores. Within wheat fields, the relative abilities of omnivorous and carnivorous predators to reduce cereal aphids depend heavily on the availability, distribution and type of alternative foods (alternative prey, sugar, and pollen), and on the intensity and direction of IG predation events within this community. A series of eight synergistic experiments, carefully crafted to accomplish objectives while accounting for regional production practices, will be conducted to explore how cover crops (US, where large fields preclude effective use of field margins) and field margins (IS, where cover crops are not feasible) as sources of alternative foods affect the IG interactions of predators and their efficacy as biological control agents. These objectives are: 1. Determine the mechanisms whereby the availability of alternative prey and plant-provided resources affect pest suppression by omnivorous and carnivorous generalist predators; 2. Characterize the intensity of IGP within generalist predator communities of wheat systems and assess the impact of these interactions on cereal aphid predation; and 3. Evaluate how spatial patterns in the availability of non-prey resources and IGP affect predation on cereal aphids by generalist predator communities. To accomplish these goals, novel tools, including molecular and biochemical gut content analysis and geospatial analysis, will be coupled with traditional techniques used to monitor and manipulate insect populations and predator efficacy. Our approach will manipulate key alternative foods and IG prey to determine how these individual interactions contribute to the ability of predators to suppress cereal aphids within systems where cover crop and field margin management strategies are evaluated in production scale plots. Using these strategies, the proposed project will not only provide cost-effective and realistic solutions for pest management issues faced by IS and US producers, but also will provide a better understanding of how spatial dispersion, IG predation, and the availability of alternative foods contribute to biological control by omnivores and carnivores within agroecosystems. By reducing the reliance of wheat producers on insecticides, this proposal will address the BARD priorities of increasing the efficiency of agricultural production and protecting plants against biotic sources of stress in an environmentally friendly and sustainable manner.
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Miller, Gad, and Jeffrey F. Harper. Pollen fertility and the role of ROS and Ca signaling in heat stress tolerance. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598150.bard.

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The long-term goal of this research is to understand how pollen cope with stress, and identify genes that can be manipulated in crop plants to improve reproductive success during heat stress. The specific aims were to: 1) Compare heat stress dependent changes in gene expression between wild type pollen, and mutants in which pollen are heat sensitive (cngc16) or heat tolerant (apx2-1). 2) Compare cngc16 and apx2 mutants for differences in heat-stress triggered changes in ROS, cNMP, and Ca²⁺ transients. 3) Expand a mutant screen for pollen with increased or decreased thermo-tolerance. These aims were designed to provide novel and fundamental advances to our understanding of stress tolerance in pollen reproductive development, and enable research aimed at improving crop plants to be more productive under conditions of heat stress. Background: Each year crop yields are severely impacted by a variety of stress conditions, including heat, cold, drought, hypoxia, and salt. Reproductive development in flowering plants is highly sensitive to hot or cold temperatures, with even a single hot day or cold night sometimes being fatal to reproductive success. In many plants, pollen tube development and fertilization is often the weakest link. Current speculation about global climate change is that most agricultural regions will experience more extreme environmental fluctuations. With the human food supply largely dependent on seeds, it is critical that we consider ways to improve stress tolerance during fertilization. The heat stress response (HSR) has been intensively studied in vegetative tissues, but is poorly understood during reproductive development. A general paradigm is that HS is accompanied by increased production of reactive oxygen species (ROS) and induction of ROS-scavenging enzymes to protect cells from excess oxidative damage. The activation of the HSR has been linked to cytosolic Ca²⁺ signals, and transcriptional and translational responses, including the increased expression of heat shock proteins (HSPs) and antioxidative pathways. The focus of the proposed research was on two mutations, which have been discovered in a collaboration between the Harper and Miller labs, that either increase or decrease reproductive stress tolerance in a model plant, Arabidopsis thaliana (i.e., cngc16--cyclic nucleotide gated channel 16, apx2-1--ascorbate peroxidase 2,). Major conclusions, solutions, achievements. Using RNA-seq technology, the expression profiles of cngc16 and apx2 pollen grains were independently compared to wild type under favourable conditions and following HS. In comparison to a wild type HSR, there were 2,776 differences in the transcriptome response in cngc16 pollen, consistent with a model in which this heat-sensitive mutant fails to enact or maintain a normal wild-type HSR. In a comparison with apx2 pollen, there were 900 differences in the HSR. Some portion of these 900 differences might contribute to an improved HSR in apx2 pollen. Twenty-seven and 42 transcription factor changes, in cngc16 and apx2-1, respectively, were identified that could provide unique contributions to a pollen HSR. While we found that the functional HS-dependent reprogramming of the pollen transcriptome requires specific activity of CNGC16, we identified in apx2 specific activation of flavonol-biosynthesis pathway and auxin signalling that support a role in pollen thermotolerance. Results from this study have identified metabolic pathways and candidate genes of potential use in improving HS tolerance in pollen. Additionally, we developed new FACS-based methodology that can quantify the stress response for individual pollen in a high-throughput fashion. This technology is being adapted for biological screening of crop plant’s pollen to identify novel thermotolerance traits. Implications, both scientific and agricultural. This study has provided a reference data on the pollen HSR from a model plant, and supports a model that the HSR in pollen has many differences compared to vegetative cells. This provides an important foundation for understanding and improving the pollen HSR, and therefor contributes to the long-term goal of improving productivity in crop plants subjected to temperature stress conditions. A specific hypothesis that has emerged from this study is that pollen thermotolerance can be improved by increasing flavonol accumulation before or during a stress response. Efforts to test this hypothesis have been initiated, and if successful have the potential for application with major seed crops such as maize and rice.
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Gaugler, Randy, Itamar Glazer, Daniel Segal, and Sarwar Hashmi. Molecular Approach for Improving the Stability of Insecticidal Nematodes. United States Department of Agriculture, November 2002. http://dx.doi.org/10.32747/2002.7580680.bard.

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Our overall goal is to improve insecticidal nematodes by genetically engineering strains capable of entering an enhanced state of dormancy that provides improved stability. Objectives: 1. Clone and sequence tps-l homologue from Steinernema carpocapsae. (Revised: A failure to isolate the tps gene group from Steinernema precipitated a redirection to identifying other genes involved in insecticidal nematode desiccation process.) 2. Incorporate cloned tps-l gene into S. carpocapsae to obtain overexpression, thereby, enhancing desiccation tolerance. (Revised: Other stress genes in addition to tps-l genes were cloned and efforts at expression in S. carpocapsae were conducted) 3. Characterize the transgenic strains. No other biological control agent offers more impressive attributes than insecticidal nematodes. However, their potential is limited by the bane of nearly all biological control agents: poor stability. This leads to inadequate shelf-life and ultimately reduced field efficacy. Nematode storage is based on desiccation, yet insecticidal species are only capable of partial desiccation termed quiescent anhydrobiosis. Overwhelming evidence has shown that when the disaccharide compound trehalose is elevated in anhydrobiotic organisms such as yeast, plants, and nematodes it enables these organisms the ability to survive environmental stresses i.e., desiccation. Armed with this information our goal was to improve insecticidal nematodes stability by engineering trehalose overexpression.
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