Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Polyclonal B cell response wikipedia , lookup
Paracrine signalling wikipedia , lookup
Lipid signaling wikipedia , lookup
Proteolysis wikipedia , lookup
Two-hybrid screening wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Biochemistry wikipedia , lookup
Signal transduction wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Taxonomy, biology and physiology of fungi Objectives Introduction of fungi Biology of fungi Physiology of fungi Cell structure, growth and development Nutrition, Temp, UV light, and water Classification of fungi Introduction of fungi Eukaryotic, Heterotrophic (chemoheterotrophic) microorganism No chlorophyll, non-motile Thread of cells (hyphae), transverse cell walls (septate), hyphal anastomosis Storage compound; glycogen Introduction of fungi Other characteristics of fungi the ability to synthesize lysine by the -amino adipic acid pathway (AAA-pathway) possession of a chitinous cell wall plasma membranes containing the sterol ergosterol and microtubules composed of tubulin. Structure Cell wall Plasma membrane Microtubules Nucleus Fungal wall Shape of fungi Protect against osmotic lysis It the wall contains pigments (melanin) protect the cell against ultraviolet radiation or the lytic enzymes of other organisms It can have antigenic properties Cell wall components Predominance of polysaccharides, lesser amounts of proteins and lipids Table 1 Major polysaccharide components of fungal walls Division Oomycota Fibrillar components Cellulose, (1,3)(1,6)-glucans Chytridiomycota Chitin, glucan Zygomycota Chitin, chitosan Matrix components Glucan Glucan Polyglucoronic acid, glucuronomannoproteins Ascomycota/ Chitin, (1,3)-(1,6)deuteromycota glucans Basidiomycota Chitin, (1,3)- (1,6)glucans -(1,3)-Glucan, galactomannoproteins ,, Cell wall components The major polysaccharides of cell wall matrix consist of glucans such as manans, chitosan, and galactans Glucan refers to a group of D-glucose polymers having glycosidic bonds Insoluble -glucans are apparently amorphous in cell wall Mannans, galactomannans, rhamnomannans are responsible for the immunologic response to the medically important yeasts and molds Cell wall components Consisting of chitinous microfibrils embedded in the matrix of small polysaccharides, proteins, lipids, inorganic salts, and pigments Chitin is a (1-4)-linked polymer of N-acetyl-Dglucosamine (GlcNAc) Produced in cytosol (from UDP GlcNAc into chains of chitin by chitin synthetase) The chitin microfibrils are transported to the plasmalemma and subsequently integrated into the new cell wall Cell wall components In addition to chitin, glucan, and mannan, cell walls may contain lipid, protein, chitosan, acid phosphatase, amylase, protease, melanin, and inorganic ions (phosphorus, calcium, and magnesium) The outer cell wall of dermatophytes contains glycopeptides that may evoke both immediate and delayed cutaneous hypersensitivity Plasma membrane The main role of the plasma membrane To regulate the uptake and release of materials Integral membrane protein (chitin syntase, glucan syntase) Signal transduction Plasma membrane Similar to mammalian plasma membrane, differing in having the nonpolar sterol ergosterol, rather than cholesterol regulates the passage of materials into and out of the cell by being selective permeable Several antifungal agents interfere with ergosterol synthesis (i.e., amphotericin B) Microtubules Composed of the protein tubulin, which consists of a dimer composed of two protein subunits. Microtubules are long, hollow cylinders ~ 25 nm in diameter Involved in the movement of organelles, chromosomes, nuclei, and Golgi vesicle containing cell wall precursor Microtubules Assist in the movement of chromosomes during mitosis and meiosis the destruction of cytoplasmic microtubules interferes with the transport of secretory materials to the cell periphery, which may inhibit cell wall synthesis Nucleus The nucleus is bounded by a double nuclear envelope and contains chromatin and a nucleolus Fungal nuclei are variable in size, shape, and number The number of chromosomes varies with the particular fungus S.cerevisiae ; 18 (n) T.mentagophytes ; 4 (n) The growth of hyphae Apical extension Balance between wall synthesis and wall lysis The apical vesicles (Spitzenkörper) are produced from Golgi bodies and then transported to the tip Spitzenkörper (apical body) The vesicles fuse with the plasma membrane at the tip, and release their contents. enzymes involved in wall synthesis, (chitin syntase, glucan synthase) enzymes involved in wall lysis, enzyme activators, some preformed wall polymers such as mannoproteins Hyphal anastomosis Vegetative hyphal fusion in common in higher fungi Involves the growth of hyphae toward each other Physiology Aeration Nutrition Water Temperature Hydrogen ion Light Aeration The fungi include species that are obligately aerobic (eg. most Zygomycota), obligately anaerobic (eg. rumen fungi) Organisms can obtain energy by oxidative (respiratory) metabolism or by fermentation O2 is used for oxidative metabolism to generate energy. However it is essential for biosynthesis of sterols, unsaturated fatty acids and some vitamins Table 2 Energy metabolism in relation to O2 requirements Obligately oxidative. Obligate aerobes. Exp. Rhodotorula Facultatively fermentative. Energy can be obtained by oxidative and fermentative processed such fungi are likely to be faculative anaerobes. Oxidative metabolism, provides much more energy than fermentative, so higher yields can occur under aerobic conditions. Exp. Mucor, Saccharomyces Obiligately fermentative. Oxygen is not needed for energy production , may be either harmless or toxic. Exp. Blastocladia, Neocallimastix Diagrammatic representation of the mixed-acid fermentation of the rumen chytrid Neocallimastix. Part of the fermentation occurs in the cytosol and hydrogenosome Hydrogenosome: functionally equivalent to the mitochondria of aerobic organisms The nutrient requirement of fungi Carbon needs for the synthesis of carbohydrates, lipids, nucleic acids, and proteins. Simple sugars, polysaccharides, citric acid, glycerol Nitrogen for synthesis of amino acids for proteins, purines and pyrimidines for nucleic acids, glucosamine for chitin, and various vitamins Amino acid, ammonium, nitrate Nutrition C/N ratio (20:1) Other elements P : energy-rich compound metabolism, phospholipid in lipid bilayer K : coenzyme Mg : concer with sporulation S : protein component Trace elements Fe, Cu, Mn, and Zn Nutrition Czapek-Dox medium widely used for the culture of fungi Mineral base: C and energy source: KH2PO4 MgSO4.7H2O KCl FeSO4.7H2O Sucrose (Glu,starch) N source: Water: NaNO3 If a solid medium is required: Agar 1g 0.5 g 0.5 g 0.01 g 30 g 2g 1 litre 20 g Water availability Most fungi require very high water availability (relative humidity), and rapidly dry out or senescence in dry conditions. Water activity (aw) = ps/pw (pure water = 1) DNA is denatured at aw = 0.55 Osmophiles 0.85, Xerophiles 0.80, Halophiles 0.75 The xerotolerant fungi can grow slowly, at water activity of 0.64. Temperature Hydrogen ion Opt. pH 5.0-7.0 Acid-tolerant (pH 2.0) Aspergillus, Penicillium, Fusarium, yeast in stomach of animals Strongly alkaline environment (pH 10-11) F.oxysporum, P.variabile Light Influence on fungal growth in specific cases light does not play a major part in growth and metabolism of fungi A common metabolic effect of light is the induction of carotenoid biosynthesis Morphology Yeast Unicellular, round or oval, size 8-15 x 3-5 µm Conidiogenesis (budding, binary fission, sexual spores) Budding yeasts Binary fission Morphology Mold Multicellular, hyphae, septate & nonseptate, hyaline & dematiaceous, diameter 4-20 µm Sexual and asexual reproduction Hyaline septate hyphae Dematiaceous septate hyphae Hyaline aseptate hyphae Morphology Dimorphic fungi (thermally dimorphic fungi) Environment/Routine culture media (SDA) 25-300C ---Mold form Sporothrix schenckii Tissue/Enriched media (BHI) 35-370C---Yeast form Morphology Classification of fungi Kingdom Division Subdivision Class Subclass Order Family Genus Species Fungi -mycota -mycotina -mycetae -mycetes -ales -aceae --------------- Classification of fungi Four major division of fungi, base on the type of sexual spores (ascospore, basidiospore, zygospore, oosore), plus another group, which have no know sexual state. Ascomycota Basidiomycota Zygomycota Chytridiomycota Deuteromycota (Imperfect fungi) Sexual reproductive structures, which are referred to as teleomorphs reflect phylogenetic relationships because they are based upon structures that form following meiosis Asexual reproductive structures, which are referred to as anamorphs does not reflect phylogenetic relationships For example, the dimorphic fungus Blastomyces dermatitidis Anamorph : hyphae, conidia at 250C and budding yeast cell at 370C The name B.dermatitidis summarizes these two anamorphs Teleomorph : sexual fruiting body, called a gymnothecium, containing ascospores The name that is used for this sexual form or teleomorph is Ajellomyces dermatitidis Sexual reproduction Gametes or gametic nuclei (n) n (haploid) Meiosis n (monokaryon) Plasmogamy (cell fusion) n+n (dikaryon) 2n (diploid) Zygote (2n) Karyogamy (nuclear fusion) Division Ascomycota Common name: Sac fungi Sexual reproduction: ascospore in ascus Asci may form in fruiting body called an ascocarp Gymnothecium, Cleistothecium, Perithecium, Apothecium Asexual reproduction: conidia, arthospore, budding septate hyphae or yeast Eurotium (Aspergillus)., Arthroderma (Trichophyton) Life cycle of ascomycetes Arthospore Cleistothecium Ascocarp Gymnothecium Perithecium Apothecium Life cycle of the yeast Saccharomyces cerevisiae a c b Division Basidiomycota Common name: Club fungi, mushroom Sexual reproduction: basidiospore Asexual reproduction:budding hyphae with dolipore septum or yeast clamp connection Mushroom: basidiocarp, fruiting body Filobasidiella neoformans (no basidiocarp) or Crytococcus neoformans Clamp connection Life cycle of basidiomycetes Amanita phalloides เห็ดไข่หงส์ เห็ดเกล็ดดาว เห็ดขี้ววั เห็ดยวงขนุน เห็ดกระโดงตีนต่า Division: Zygomycota Common name: Bread molds Sexual reproduction: Zygospore Mating type +, mating type - Asexual reproduction: Sporangiospore, sporangium coenocytic hyphae (aseptate hyphae) Rhizopus sp., Mucor sp., Asidia sp. Life cycle of Rhizopus stolonifer Division: Chytidiomycota Common name: Water molds Sexual reproduction: Oospore Asexual reproduction: Zoospore, zoosporangium, flagella aseptate hyphae Phythium insidiosum Deuteromycota Common name: Imperfect fungi have no known sexual state in life cycle Asexual reproduction : conidia (blastic, thallic) septate hyphae or yeast Human pathogenic fungi: dermatophytes, dimorphic fungi Conidiogenesis Blastic: the conidium originate from a narrow portion of the region which swells before being cut off by a septum Phialophora Cladosporium Curvularia Penicillium Scopulariopsis Blastic conidiogenesis Acropetal conidia Sympodia condia Poroconidia Phialoconidia Anneloconidia Conidiogenesis Thallic: the conidium arise from a broad zone of the region and septa laid down before the conidium swells Candida albicans Geotrichum Microsporum Trichophyton Thallic conidiogenesis Arthoconidia Thallic solitary conidia Chlamydoconidia (chlamydosprore)