CLASSIFICATION_AND_GENERAL STRUCTURES OF FUNGI.ppt
Transcript
CLASSIFICATION and GENERAL STRUCTURE of FUNGI YEDİTEPE UNIVESITY SCHOOL of MEDICINE 2023 Nilgün Çerikçioğlu YEDİTEPE ALL THE BIOLOGICAL TERMS AND BEHAVIORS ARE OF MEDICAL IMPORTANCE GENERAL CHARACTERISTICS OF FUNGI Fungi (plural), fungus (singular) Mycology The study of fungi More than...
CLASSIFICATION and GENERAL STRUCTURE of FUNGI YEDİTEPE UNIVESITY SCHOOL of MEDICINE 2023 Nilgün Çerikçioğlu YEDİTEPE ALL THE BIOLOGICAL TERMS AND BEHAVIORS ARE OF MEDICAL IMPORTANCE GENERAL CHARACTERISTICS OF FUNGI Fungi (plural), fungus (singular) Mycology The study of fungi More than 150.000 species, identified Only 300 species produce disease in man and animals About a dozen (12..) spp: cause 90% of all fungal diseases •All: EUKARYOTIC •Mostly possess: Rigid CELL WALL •Some are: motile (flagellated) (not related to humans) •NO photosynthesis •Chemotrophic (degrade organic substances) •Optimal pH : 2,2 – 9,6 (molds) 3,0 – 7,5 (yeasts) GROWTH FORMS OF FUNGI (MORPHOLOGY) • 1) • • • MOLDS Large multicellular aggregates of long branching filaments (hyphae) Hyphae: filaments = mycelium Responsible for the fluffy appearance of mold colony Colored Spores Hyphae Hyphae an colored spores Hyphae Germinating Mold Spore (germ tube ) spore germ tube Initial stage (phase) of hypha Spore Germination and Hyphae Production Under microscope field branching According to shape i) Septate hyphae: Filaments - Septa have PORES (flow of cytoplasm and organelles) ii) Aseptate hyphae: No cross walls (Coenocytic hyphae) Septate hyphae According to functions: i)Vegetative Hyphae: - actively growing hyphae (into the medium) • ii) Aerial Hyphae: to pigmented) *Some Aerial hyphal cells reproductive spores (melanin -(reproductive hyphae ) carry reproductive spores - project above the surface into the air - contribute the fluffy appearance of the mold colony turn Aerial Vegetative Aerial hyphae/ reproductive spores Spores (pigmented) Hyphae • • • • Molds grow at 20 – 260C (room temperature) Rate of growth : - saprophitic molds in 2 – 5 days - pathogenic molds in 2 – 4 weeks Topography of the colony: - glabrous - velvety - verrucose - cottony - powdery True Pigmentation - reverse site - some: diffusible **( nonpigmented / nonmelanized hyaline hyphae) Hyaline moulds are fungi that grow predominantly in a filamentous form with colourless hyphae Their spores may be pigmented (black, green..) Septate hyaline hyphae from an infected nail (40x) Dark pigmented hyphae (40x) Mold colony (fluffy appearence ) Pigmented spore Hyaline Hyphae MOLD REPRODUCTIVE SPORES ASEXUAL..........................................SEXUAL • Mostly produced at the ends of aerial hyphae -Hyphal cell transforme into spores - Resistant to unfavourable conditions (protection) - Produced in large numbers (reproduction) - Easily disseminated in nature, in laboratory conditions, in hospital (dissemination) ASEXUAL SPORES DIVIDE INTO TWO MAJOR GROUPS: CONIDIA SPORANGIOSPORES CONIDIA divide into four groups: İ) Chlamydospores *** Their appearence on specific media serve as a first criterion for fungal genus and species identification ii) Arthroconidium ….disease transmision iii) Microconididium…disease transmision iv) Macroconidium***….. Their appearence on specific media serve as a first criterion for fungal genus and species identification A) Conidia (conidium) • Form clusters at the end of aerial hyphae • Light weight, easily disseminated (enhancing spread of fungus) i) Chlamydoconidia - Large, round, thick walled, unicellular structure - Contains: glycogen or lipid energy reserves - Unicellular IDENTIFICATION UNDER MICROSCOPE FIELD ii) Arthroconidia • Hyphal cells undergo thickening of their cell – walls • Fragment away from mother filament, • Forming: Barrel shaped conidia • Easily aerosolized !!! iii) Microconidia • Unicellular • Small spores iv) Macroconidia (typical appearance ) • Multicellular • USEFUL IN IDENTIFICATION UNDER MICROSCOPE FIELD( name of the mold!!!!! ) microco nidia arthroc onidia macroco nidia chlamydo conidia B) • Sporangiospores • Borne at the and of aerial hyphae Sac like structures (sporangium) Contain: sporangiospores Sac ruptures mature spores discharge • Molds with aseptate hyphae grow. • • Black Bread Mold Disease Transmission RUPTURED SPORANGIUM with sporangiospores Teen, 14, died after catching rare fungal infection from breathing in mould / SUMMARY SEXUAL SPORE IN MOLDS Zygospor In: ASEPTATE HYPHAL MOLDS Zygospores Mold spores are important for human health 2) YEASTS (BLASTOSPORES / BLASTOCONIDIA)) • • • • • • Large, single (unicellular) cells 5 – 8 m (diameter) (cocci 0.2-2.0 µm) Spherical or ellipsoidal Most reproduce by budding (Bud: blastospore) (ASEXUAL) Bud (daughter cell ) breaks away from mother cell New buds may develop Bud, daughter cell Mother yeast cell SIZES OF YEASTS 2-10 μm (spherical) (Average) 20-30 μm (cylindrical) Larger than cocci (0.5- 2 μm) MOTHER YEAST BUD •If single buds fail to separate from the mother; chains of buds are formed , become elongated , pseudohyphae are produced (mistaken for the true hyphae of molds under microscope field)) Budding yeasts Pseudohyphae and buds in clinical sample Budding yeasts and pseudohyphae in patient’s urine sample • Some yeasts produce additional specific structures!!!**************** - Germ tube formation: (dimorphism) * A short, hypha – like structure … *May turn into Long / branching true hyphae (as happening in the molds) (yeast – to – true hyphae transition) * Germ tubes (initial step for true hyphae production) Elongated buding yeasts Budding yeasts Pseudohyphae, and budding yeasts Constrictions between the elongated buds True hyphae Budding yeasts Deep Tissue section • • • Yeasts grow best at 300 – 370C Produce : colonies on solid media (as bacteria ) Colonies: cream – colored (pink, red, occasionally) BLASTOSPORES =BUDS= YEASTS and HYPHAL FORMS OF YEASTS ARE: ...ASEXUAL**** Sexual Spores of Yeasts Basidiospores: Some yeasts can produce in nature and in tissue MOLDS DO NOT PRODUCE!! Basidiospores of yeasts • SEXUAL REPRODUCTİON COMMON İN YEAST / MOLDS (ASCOSPORES) Diploid yeast cells and some molds can produce Ascus / Ascospores • • *Ascus (sac) ruptures are released ascospores Ascus and ascospores in tissue MONOMORPHISM (monomorphic fungi) Fungi grow ONLY in yeast or mold morphology (monomorphic fungi) DIMORPHISM (dimorphic fungi ) VIRULENCE FACTOR ADAPTATION******) Many species of fungi grow in mold / hyphal / or yeast form According to conditions (temperature, nutrients, CO2 concentration, pH)… (FOR • • e.g: mold yeast e.g: yeast true hyphae [Candida albicans true septate hyphae] SUBCELLULAR STRUCTURE OF FUNGI *Cell Wall / Slime (the outer most layers) *Cell membrane (under the cell wall) *Cytoplasmic content All are medically important!!!!! slime-biofılm Almost all the fungi produce slime / biofilm In tissue On biomaterials Yeast CAPSULE Capsule Cell Wall Chitin N- acetyl - glucosamin polymers Glucan: glucose polimer Mannan: mannose polimer • Antigenic (polysaccharides) • Responsible from: attachement to human cells (mannan) • Glucan Target for antifungal drugs !!!(glucan) Cell Membrane • • • • • Bilayer membrane Phospholipids + proteins Fungal membrane also contains STEROLS Mainly in: ergosterol form Target for antifungal drugs.!!! Cytoplasmic content • Several nuclei • Endoplasmic reticulum Mitochondria Ribosomes (80s) (60 + 40) Golgi apparatus • Plasmids Fungal viruses • Secondary metabolites. - Mycotoxins (Carcinogens) (aflatoxin) - Anticancer substances - Pharmacologic compounds (penicillin ) CLASSIFICATION AND GENERAL CHARACTERISTICS OF FUNGI 1- CLASSIFICATION OF FUNGI • Classification according to: - sexual spore types - morphology of hyphae • Oomycotina Zygomycota sexual and asexual Ascomycota cycles Basidiomycota Deutoromycota Only asexual cycle. (Fungi imperfecti) a) OOMYCOTA (CHROMYSTA) • Water molds (not human related)************ Produce flagellated (motile) sexual oospores • • • • Mostly: unicellular Have NO cell wall !!! Not associated with humans b) ZYGOMYCOTA • • • Characterized by: aseptate fungi Asexual : sporangiospores Sexual: Zygospores Include – black bread mold (Rhizopus nigricans) zygospore c) ASCOMYCOTA • • • Sexual: ascospores Produced by: molds / Some Yeasts The largest fungal groups (e.g. Penicillium, Aspergillus, Candida..) Some fungi produce ascospores in tissue during infection d) BASIDIOMYCOTA (some yeasts) • Mostly produce sexual spores (basidiospores) • İnfection: acquired through inhalation of basidiospores or desiccated yeast cells from the environment. basidiospore e) DEUTOROMYCOTA • (fungi Imperfecti) Have NO sexual cycle e.g: Some Candida species
