Academic literature on the topic 'Zygomycota'

Morphological properties of sporocarps and spores of <em>Endogone lactiflua </em>(Zygomycota, Endogonales), a fungus for the first time found in Poland, are described and illustrated. <em>Endogone lactiflua</em> was wet sieved and decanted from a sample taken from the zone extending from the upper soil layer to rhizosphere of <em>Pinus sylvestris </em>growing in a forest dune in northern Poland. The recovered spores mainly occurred in large and compact sporocarps, although both small aggregates with a few spores and single zygosporangia of this fungus were also isolated. <em>Endogone lactiflua</em> is the fourth species of the genus <em>Endogone </em>found to occur in Poland. The distribution of the fungus in the world is also presented.

O Reino Fungi é marcado por características peculiares, incluindo seus aspectos morfológicos e fisiológicos e está dividido em filos que são conhecidos como: Ascomycota, Basidiomycota, Glomeromycota, Zygomycota e Chytridiomycota. Os primeiros fungos à conquistarem o ambiente terrestre os Zygomyota, são conhecidos por causar infecções e bolores em alimentos. O Filo Basidiomycota apresentam os fungos mais conhecidos, chamados popularmente de cogumelos. No âmbito escolar uma das finalidades que o ensino adquiriu, é capacitar os estudantes para que consigam ter autonomia e flexibilidade em aprender e o material didático, é o meio que proporciona ao estudante uma compreensão mais clara e abrangente sobre determinados assuntos. Assim, objetivo do trabalho foi produzir dois materiais didáticos abordando de forma específica o grupo dos Zygomycota e Basidiomycota. Os materiais utilizados foram de fácil acesso e baixo custo econômico. Como resultado obteve-se o modelo didático que contém uma parte macro representando o bolor e uma parte micro com as estruturas específicas do fungo que não são visíveis sem auxílio de um microscópio (Zygomycota). Já o segundo trabalho didático elaborado foi uma apresentação tridimensional de um cogumelo (Filo Basidiomycota), representando o píleo, com basidiósporos e a haste. A confecção dos materiais didáticos apresentaram algumas vantagens como fácil e rápida elaboração, pouco gasto econômico, além da vantagem cognitiva, pois, desenvolveu a imaginação, coordenação e criatividade dos alunos, que estavam ainda estudando o conteúdo da disciplina de Micologia e isso fez com que eles pesquisassem mais sobre o tema, não ficando preso somente ao que foi passado em aula.

The chytrids (Chytridiomycota) are morphologically simple aquatic fungi that are unified by their possession of zoospores that typically have a single, posteriorly directed flagellum. This study addresses the systematics of the chytrids by generating a phylogeny of ribosomal DNA sequences coding for the small subunit gene of 54 chytrids, with emphasis on sampling the largest order, the Chytridiales. Selected chytrid sequences were also compared with sequences from Zygomycota, Ascomycota, and Basidiomycota to derive an overall fungal phylogeny. These analyses show that the Chytridiomycota is probably not a monophyletic group; the Blastocladiales cluster with the Zygomycota. Analyses did not resolve relationships among chytrid orders, or among clades within the Chytridiales, which suggests that the divergence times of these groups may be ancient. Four clades were well supported within the Chytridiales, and each of these clades was coincident with a group previously identified by possession of a common subtype of zoospore ultrastructure. In contrast, the analyses revealed homoplasy in several developmental and zoosporangial characters.Key words: zoospore ultrastructure, Chytridiales, molecular phylogeny, Chytridiomycota, operculum.

Bien que les champignons soient régulièrement utilisés comme modèle d'étude des systèmes eucaryotes, leurs relations phylogénétiques soulèvent encore des questions controversées. Parmi celles-ci, la classification des zygomycètes reste inconsistante. Ils sont potentiellement paraphylétiques, i.e. regroupent de lignées fongiques non directement affiliées. La position phylogénétique du genre Schizosaccharomyces est aussi controversée: appartient-il aux Taphrinomycotina (précédemment connus comme archiascomycetes) comme prédit par l'analyse de gènes nucléaires, ou est-il plutôt relié aux Saccharomycotina (levures bourgeonnantes) tel que le suggère la phylogénie mitochondriale? Une autre question concerne la position phylogénétique des nucléariides, un groupe d'eucaryotes amiboïdes que l'on suppose étroitement relié aux champignons. Des analyses multi-gènes réalisées antérieurement n'ont pu conclure, étant donné le choix d'un nombre réduit de taxons et l'utilisation de six gènes nucléaires seulement. Nous avons abordé ces questions par le biais d'inférences phylogénétiques et tests statistiques appliqués à des assemblages de données phylogénomiques nucléaires et mitochondriales. D'après nos résultats, les zygomycètes sont paraphylétiques (Chapitre 2) bien que le signal phylogénétique issu du jeu de données mitochondriales disponibles est insuffisant pour résoudre l'ordre de cet embranchement avec une confiance statistique significative. Dans le Chapitre 3, nous montrons à l'aide d'un jeu de données nucléaires important (plus de cent protéines) et avec supports statistiques concluants, que le genre Schizosaccharomyces appartient aux Taphrinomycotina. De plus, nous démontrons que le regroupement conflictuel des Schizosaccharomyces avec les Saccharomycotina, venant des données mitochondriales, est le résultat d'un type d'erreur phylogénétique connu: l'attraction des longues branches (ALB), un artéfact menant au regroupement d'espèces dont le taux d'évolution rapide n'est pas représentatif de leur véritable position dans l'arbre phylogénétique. Dans le Chapitre 4, en utilisant encore un important jeu de données nucléaires, nous démontrons avec support statistique significatif que les nucleariides constituent le groupe lié de plus près aux champignons. Nous confirmons aussi la paraphylie des zygomycètes traditionnels tel que suggéré précédemment, avec support statistique significatif, bien que ne pouvant placer tous les membres du groupe avec confiance. Nos résultats remettent en cause des aspects d'une récente reclassification taxonomique des zygomycètes et de leurs voisins, les chytridiomycètes. Contrer ou minimiser les artéfacts phylogénétiques telle l'attraction des longues branches (ALB) constitue une question récurrente majeure. Dans ce sens, nous avons développé une nouvelle méthode (Chapitre 5) qui identifie et élimine dans une séquence les sites présentant une grande variation du taux d'évolution (sites fortement hétérotaches - sites HH); ces sites sont connus comme contribuant significativement au phénomène d'ALB. Notre méthode est basée sur un test de rapport de vraisemblance (likelihood ratio test, LRT). Deux jeux de données publiés précédemment sont utilisés pour démontrer que le retrait graduel des sites HH chez les espèces à évolution accélérée (sensibles à l'ALB) augmente significativement le support pour la topologie « vraie » attendue, et ce, de façon plus efficace comparée à d'autres méthodes publiées de retrait de sites de séquences. Néanmoins, et de façon générale, la manipulation de données préalable à l'analyse est loin d’être idéale. Les développements futurs devront viser l'intégration de l'identification et la pondération des sites HH au processus d'inférence phylogénétique lui-même.
Despite the popularity of fungi as eukaryotic model systems, several questions on their phylogenetic relationships continue to be controversial. These include the classification of zygomycetes that are potentially paraphyletic, i.e. a combination of several not directly related fungal lineages. The phylogenetic position of Schizosaccharomyces species has also been controversial: do they belong to Taphrinomycotina (previously known as archiascomycetes) as predicted by analyses with nuclear genes, or are they instead related to Saccharomycotina (budding yeast) as in mitochondrial phylogenies? Another question concerns the precise phylogenetic position of nucleariids, a group of amoeboid eukaryotes that are believed to be close relatives of Fungi. Previously conducted multi-gene analyses have been inconclusive, because of limited taxon sampling and the use of only six nuclear genes. We have addressed these issues by assembling phylogenomic nuclear and mitochondrial datasets for phylogenetic inference and statistical testing. According to our results zygomycetes appear to be paraphyletic (Chapter 2), but the phylogenetic signal in the available mitochondrial dataset is insufficient for resolving their branching order with statistical confidence. In Chapter 3 we show with a large nuclear dataset (more than 100 proteins) and conclusive supports that Schizosaccharomyces species are part of Taphrinomycotina. We further demonstrate that the conflicting grouping of Schizosaccharomyces with budding yeasts, obtained with mitochondrial sequences, results from a phylogenetic error known as long-branch attraction (LBA, a common artifact that leads to the regrouping of species with high evolutionary rates irrespective of their true phylogenetic positions). In Chapter 4, using again a large nuclear dataset we demonstrate with significant statistical support that nucleariids are the closest known relatives of Fungi. We also confirm paraphyly of traditional zygomycetes as previously suggested, with significant support, but without placing all members of this group with confidence. Our results question aspects of a recent taxonomical reclassification of zygomycetes and their chytridiomycete neighbors (a group of zoospore-producing Fungi). Overcoming or minimizing phylogenetic artifacts such as LBA has been among our most recurring questions. We have therefore developed a new method (Chapter 5) that identifies and eliminates sequence sites with highly uneven evolutionary rates (highly heterotachous sites, or HH sites) that are known to contribute significantly to LBA. Our method is based on a likelihood ratio test (LRT). Two previously published datasets are used to demonstrate that gradual removal of HH sites in fast-evolving species (suspected for LBA) significantly increases the support for the expected ‘true’ topology, in a more effective way than comparable, published methods of sequence site removal. Yet in general, data manipulation prior to analysis is far from ideal. Future development should aim at integration of HH site identification and weighting into the phylogenetic inference process itself.

碩士
元智大學
化學工程與材料科學學系
98
Glucosamine (GlcN) is widely used as a supplement in a daily life to provide more cartilage building blocks to the body and relief of osteoarthritis pain. Recently, the needs of the microbial production of GlcN have significantly increased since GlcN production using chemical extraction and hydrolysis of shellfish derived chitin could not satisfy market needs gradually. This study covered 3 main topics, such as (1) determination of fungal glucosamine using HPLC with 1-napthyl isothiocyanate derivatization and microwave heating, (2) optimization of GlcN production using a wild-type fungi, Aspergillus sp. BCRC 31742, and (3) the screening process of subdivision Zygomycotina fungi as a candidate strain to produce GlcN cultivated in submerged fermentation. In this study, a rapid and reliable method for the determination of fungal glucosamine (GlcN) from Aspergillus sp. BCRC 31742 was developed. The hydrochlorination process using microwave evidently reduced reaction time needed for GlcN analysis. The analytical method consisted of two steps: (i) the hydrochlorination of fungal cells and (ii) the derivatization process. Fungal GlcN hydrochloride was reacted with 1-napthyl isothiocyanate (1-NITC) as the derivatizing agent to enhance the sensitivity of GlcN and so to achieve high resolution. Particularly, this method was specific for quantification GlcN hydrochloride at the wavelength of 230 nm. The standard deviation and relative error of the analytical results were less than 5%. By using microwave heating, the reaction time of hydrochlorination process was significantly shortened from 24 h to 3 min. Thus, the overall time needed for analyzing GlcN from fungal sources could be reduced from 5 h (thermal method) to 2 h (microwave method). This study also indicated the production of GlcN using wild-type fungi, Aspergillus sp. BCRC 31742. Several parameters for cultivation were studied (e.g., pellet diameter, working volume, agitation rate and stimulating factors). The fermentation conditions with pellet diameter of 2.15 mm, working volume of 50 mL (250 mL T-flask) and incubation at 30oC, shaken at 200 rpm and pH 7.0 yielded the highest biomass of 33.82 g/L, with the GlcN concentration of 7.05 g/L. Methanol (1.50% v/v) was found to be the optimal stimulating factor tested amongst others, which could increase the GlcN concentration up to 7.48 g/L. For stimulatory effect of glutamic acid and ethanol could only increase the GlcN concentration slightly. Those GlcN concentrations for glutamic acid and ethanol were 7.07 g/L and 7.07 g/L, respectively. Screening of fungi from Zygomycotina subdivision resulted in Absidia coerulea as the promising fungi. Furthermore, fermentation aspects and medium compositions of Absidia coerulea were studied as the preliminary optmization. Optimum conditions for cultivation aspects were: (1) fermentation conditions: initial medium pH 3.50; working volume, 50 mL; agitation, 200 rpm; temperature, 30oC; inoculum concentration, 10% (v/v), whereas for (2) medium compositions (g/L): glucose, 25; peptone, 20; yeast extract, 1; (NH4)2SO4, 5; KH2PO4, 1; NaCl, 1; MgSO4.7H2O, 5; and CaCl2, 0.1. Addition of crude chitosan (5.0 g/L) into fermentation medium significantly increased both GlcN and biomass concentration from 2.31 g/L (control) to 2.85 g/L and 15.45 g/L to 22.46 g/L, respectively.