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Chapter 26
The Fungi (Eumycota) 12-02-0812-03-08
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Fungal Subdivisionssequence of 18S rRNA and some protein coding genes indicates the Fungi are a monophyletic group with eight divisions
ChytridiomycetesZygomycotaAscomycotaBasidiomycotaUrediniomycetesUstilaginomycetesGlomeromycotaMicrosporidia Figure 26.1
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True fungi
fungus (pl., fungi)Eucaryotic cellspore-bearingchemoorganoheterotrophsreproduce sexually and asexuallybelong to kingdom Fungi (Eumycota) within domain Eucarya
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Some terms
mycologystudy of fungi
mycologistsscientists who study fungi
mycotoxicologystudy of fungal toxins and their effects
mycosesdiseases caused by fungi
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Nutrition and Metabolismmost are saprophytes
obtain nutrients from dead organic materialsecrete hydrolytic enzymes
chemoorganoheterotrophsglycogen is primary storage polysaccharidemost are aerobic
some are facultative anaerobesobligate anaerobic fungi are found in rumen of cattle
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Importancebeneficial impact
decomposersindustrial fermentations
Foods- mushroomfermented foods and beveragessteroids, antibiotics and other drugs
Research (Saccharomyces cerevisiae)model eucaryotic organisms
detrimental impactmajor cause of plant diseasescause of many animals including human diseases
7Table 26.1
Mycotoxicoses
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Distributionprimarily terrestrial
few aquatic speciessome form associations
mycorrhizae – associations with plant rootslichens – associations with algae or cyanobacteria
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Fungal Structure
Thallus- body or vegetative structurecell walls usually composed of chitin
polysaccharide consisting of N-acetyl glucosamine residues
have two reproductive structuressporangia form asexual sporesgametangia form sexual gametes
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Yeastunicellular fungireproduce asexually, often by buddingreproduce sexually by formation of spores
Figure 26. 4
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Moldsfilamentous fungi
hyphae (s., hypha)the filaments of a moldmay be coenocytic (no cross walls) or have septa (cross walls)
mycelium (pl. mycelia)bundles or tangled masses of hyphae
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Dimorphismsome fungi change from yeast form (Y) to mold form (M): YM shiftin plants, M in host and Y outside hostin animals, Y in host and M outside host
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Asexual reproductiontransverse fissionbuddingspore production
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Sexual reproductioninvolves union of compatible nuclei followed by formation of sexual spores (zygospores, ascospores, or basidiospores)zygote formation
several mechanismsfusion of gametesfusion of gametangia
gamete-producing bodiesfusion of hyphae
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ChytridiomycetesOomycetesSimplest, free-living and parasitic formsproduce zoospores with single, posterior, whiplash flagellum asexual and sexual reproductionmany can degrade cellulose and keratin
Allomyces
16 Figure 26.10
Division Zygomycota- Zygomycetes
coenocytic hyphaecontaining numerous haploid nuclei
- most are saprophytesa few are plant and animal parasites
- some of industrial importance
Rhizopus stolonifer, Mucor sppfoods, antibiotics and other drugs, meat tenderizer, and food coloring
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Glomeromycota
Previously considered as zygomycetesmajor importance as endomycorrhizalsymbionts of vascular plants
form intracellular associations within roots of almost all herbaceous plants and tropical trees
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Ascomycotaascomycetes (sac fungi)
during sexual reproduction produce ascus (pl., asci) containing haploid ascospores
considerable human impactfood spoilage and plant diseasesedible mushrooms, and food and beverage productionModel organism for cell biology, genetics, cancer research
can be filamentous or yeast formfilamentous forms have septate hyphae and asexual reproduction by conidiospores
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Ascomycetes- considerable human impact
Ergot (Claviceps purpurea) and ErgotismErgot alkaloids
LSD (lysergic acid diethylamide), oxytocin, to ease migraine
food spoilage, plant and animal diseasesedible mushrooms, and food and beverage productionresearch
The black Truffle
Morel-Morchella
Truffle-Diamonds of the Kitchen
Chocolate truffleThe highly-prized ingredient used in European cooking which is famous for its unique smell can sell for up to NT$180,000 a kilogram
常春藤解析英語 10-07-2008
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Division Ascomycotaascomycetes – sac fungi
sexual reproduction produce ascus (pl., asci) containing haploid ascospores
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Sexual cycle of Ascomycetes
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Reproduction cycle- Saccharomyces
24Figure 26.13
Asexual reproduction- Aspergillus
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Basidiomycotabasidiomycetes (club fungi)
during sexual reproduction form basidiumhuman impact
decomposersedible mushroomspathogens of humans, other animals, and plants
Cryptococcus neoformans – cryptococcosissystemic infection, primarily of lungs and central nervous system- aseptic meningitis
Amanita phalloides- destroying Angelproduce phalloidin and amanitin neurotoxin
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Life cycle of Basidomycetes
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Urediniomycetes and Ustilaginomycetesplant pathogens causing “rusts” and “smuts’
Ustilago maydis- tumor formation in corn
- some Urediniomycetes are also human pathogens
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Microsporidiaare still sometimes considered protistshave a unique morphology
lack mitochondria, peroxisome, centriole
obligate intracellular parasites that infect insects, fish, and humans
Microsporidian spore
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Chapter 39
Human Diseases Caused by Fungi - Mycoses
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Superficial Mycoses
Piedras- infections of hair shaft
髮癬 鬚癬
毛幹結病
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Cutaneous MycosesDermatomycoses, ringworms, and tineas-distinguished according to causative agent and area of body affected
Tinea Barbae; T. capitis ; T. corporis ; T. cruris ; T. pedis ; T. unguium - onychomycosis
most common fungal diseases, occurring worldwidetreatment, prevention, and control
microscopic examination (under Wood’s light) of skin biopsies and culture on Sabouraud’s
glucose agartopical ointments and antifungal agents
Tineas 癬
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Subcutaneous Mycoses (1)caused by saprophytic inhabitants of soilintroduced in soil-contaminated puncture woundsclinical manifestations
develop slowly over a period of yearsnodules form and ulcerateorganisms spread along lymphatic channels, producing more nodules
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Subcutaneous Mycoses (2)Chromoblastomycosis
formed dark brown nodulesmost infections involved legs and feet
Maduromycosisprevalent in tropicseumycotic mycetoma (madura foot)
Sporotrichosismost common in USAan occupational diseaseextracutaneous sporotrichosis
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Systemic Mycoses (1)most are caused by dimorphic fungi (YM shift)acquired by inhalation of spores from soilpulmonary syndromes- through blood stream to other organsCryptococcus neoformansonly has yeast form- a large capsule
Cryptococosis- worldwide distributionfound in 15% AIDS patientscause pulmonary, skin, bone and CNS infections
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Systemic Mycoses (2)Endemic infections- most are asymptomaticBlastomycosis (Fig. 40.10)
predominant in Mississippi and Ohio river
Coccidioidymycosis (Coccidioides immitis)valley fever or desert rheumatism arthrocinidia and endospore Fig. 40.11
HistoplasmosisIntracellular infections Macrocinidia and microconidiayeastlike cells in macrophage
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Opportunistic Mycoses (Table 39.1)
opportunistic microorganismnormally harmless but becomes pathogenic in compromised hostmalnutrition, alcoholism, cancer, diabetes, leukemia, and others…
Aspergillosisin severely compromised individuals, lungs may fill with mycelia- brocho pulmonary aspergillosisAspergilloma - fungus ballA. flavus and A. fumigatus
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Candidiasis- An important nosocomial infection
produce a diverse spectrum of diseasesoral candidiasis (thrush)paronychia and onychomycosisintertriginous candidiasis
- axillae, groin, and skin foldsnapkin (diaper) candidiasis
candidal vaginitis: when lactobacilli are depleted
listed by CDC as a STD (Sexually transmitted diseases)
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Microsporidia- Microsporidosis
Found mostly in HIV patientsSeveral domestic and feral animals are reservoirsProduce highly resistant sporeCause a wide variety of diseases including hepatitis, pneumonia, skin lesions, diarrhea, weight loss, and wasting syndromes
Fig. 39.27
39
Pneumocystis Pneumonia
Pneumocystis carniipneumonia – PCPP. jiroveci
A protist? - classified into fungi on the basis of rRNA and DNA sequences Occurs exclusively in immunocompromisedpatientscommon in AIDS patients
Fig. 39.28
The Protists
Chapter 25
The Protists
Protistology
most are unicellular
lack the level of tissue organization
usually reproduce asexuallybinary fission
Polyphyletic
an artificial grouping of over 64,000 single-celled life formsprotozoa
chemoorganotrophic protistsprotozoology
algaephotosynthetic protistsphycology
Four major groups
Classified by means of local motionFlagellates, Ciliates, and Amoebae
many protists have cilia or flagella at some point in life cycle formation associated with kinetosomeplays role in motilityalso used to generate water currents for feeding and respiration
Sporozae (Stationary forms)
Distribution
a wide variety of moist habitats- terrestrial and planktonic formsmost are free livingplay role in recycling nitrogen and phosphorusparasitic forms cause disease in humans and domesticated animals
Table 25.1
Nutrition
Photosynthetic protists are aerobicoxygenic photosynthesis with photosystems I and II
Chemoheterotrophic protistsholozoic- acquired nutrients by phagocytosissaprozoic- acquired nutrients by endocytosis, diffusion or carrier mediated transport
osmotrophy –soluble nutrients are assimilated
Mixotrophy
Figure 25.2
Holozoic feeding
Structure
plasmalemma- protist cell membranecytoplasm
ectoplasm and endoplasmcontractile, secretory and phagocytic vacuolesenergy-conserving organelles
Mitochondria hydrogenosomes (anaerobes)
chloroplasts
Encystment and excystment
Cyst (thick-walled resistant resting cell)Encystation
some protozoa secrete resistant covering A dormant form (very low metabolic activity)
Excystmentrelease from cyst triggered by favorable environmental conditions
Reproduction
binary or multiple fission or buddingsexual reproduction
conjugationsyngamyautogamy
Figure 25.3
Giardiasis-food and waterborne disease
International Society of Protistologists
FornicataMost bear flagella and lack mitochondria
Most are harmless symbionts
Some are free-living in waters that are heavily polluted with organic nutrients
Giardia intestinalis- first discovered by van Leeuwenhoek in 1681 in his own stool
Trichomoniasis (abortion) 陰道滴虫症
One of the most common sexually transmitted disease
7 million cases/y in USA and 180 million cases/y worldwide
caused by flagellated Trichomonasvaginalis
Fig. 39.21
Euglenozoa
commonly found in fresh water
Euglena
Fig. 25.5
A red eyespot helps to orient to light
Euglenozoa- Trypanosomes
parasites of plants and animalsleishmaniasis
caused by members of genus Leishmania
includes systemic and skin/membrane damage
Trypanosoma cruzicauses Chagas disease
transmitted by “kissing bugs"
causes damage to nervous system
T. gambiense and T. rhodesiensecause African sleeping sickness
Fig.25.6- Tsetse flies
Leishmaniasis
Cause by flagellated protozoa and transmitted by sand flies from animals (canines and rodents)Leishmania braziliensis cause mucocutaneous leishmaniasis in tropical America
Produce lesions involving the mouth, nose, and skin and results in extensive scarring and disfigurement
L. donovani: endemic in areas within northern China, estern India, the Mediterranean countries, the Sudan, and Latin America
produces visceral leishmaniasis
L. tropica and L. mexicanainfections produce relatively small red papule at the site of insect bite eventually develop into crustated ulcers
Fig. 39.8
Tryanosomiasis 錐形虫症
African sleeping sickness
no suitable drug vaccines are not useful (phase variation of the protein coat to evade the immunologic response)
American trypanosomiasis
heart disease and other disorders no treatment available
Fig. 39.9
Amoebozoa
use of pseudopodia for locomotion and feeding
shape of pseudopodslobopodia – roundedfilopodia – long and narrow reticulopodia – form a netlike mesh
most amoebae reproduce by asexual divisionFree-living forms Inhabit almost any environment
Fig. 25.8 Amoeba proteus
Amebiasis- amebic dysentery
Fig. 39.22
Entamoeba histolyticaendemic in warm climates100,000 death/ y worldwidehighly variable symptoms:
asymptomatic infectionfulminating dysentery (exhaustive diarrhea accompanied by blood and mucus, appendicitis, and abscess in liver, lung, or brain)
Eumycetozoa- “Slime Molds"
have been classified as plants, animals or fungi
Myxogastria-acellular slime molds
Plasmodium
Figure 25.9
Cell cycle
Dictyostelia- Cellular Slime Molds
Figure 25.10a
Dictyostelium discoideum
- A model organism
- formation of cellulose-walled macrocyst (> 40 genes involved in biosynthesis and degradation of cellulose)
- 33.8 Mbp genome
Apicomplexans
Apical complexparasitic life cycles
both sexual and asexual phases
clonal and sexual stages are haploid (except for zygotes)sporozoite is the motile, infective stage
most important member is Plasmodium, the cause of malaria
Figure 25.15
Life cycle of Plasmodium vivax
Asexual cycle in erythrocyte
- anemia, and hypertrophy of spleen and liver
Sexual cycle in mosquito
Fig. 39.5
Malaria- caused by the sporozoa Plasmodium
Human malaria caused by 4 species: P. falciparum, P. malariae, P. vivax, and P.ovale
300 million people infected / y, > 1 million deaths/ y in Africa, and ~1000 cases reported/ y in USA
transmitted by female Anopheles mosquito
shaking chills, then burning fever followed by sweating
Malaria- erythrocyte cycle
Toxoplasmosis 弓形虫症
Toxoplasma gondiiFound in nearly all animals and most birds
Cats are the host for completion of the sexual cycle
Animals shed cysts in the feces and the cysts enter another host by nose or mouth
also transmitted by the ingestion of raw or undercooked meat, congenital transfer (causing congenital defects- ~3000/ y in USA or death), blood transfusion, or a tissue transplant
most cases are asymptomatic
cause severe diseases in immunosuppressedpatients
a major cause of death in AIDS patients
Fig. 39.20
Cryptosporidosis 隱孢子囊虫症
Cryptosporidium (hidden spore cysts)
found in 90% of sewage samples, in 75% of river waters, and in 28% drinking waters
cause outbreak of waterborne diseases with 10 to 100 oocysts (remain viable for 2 to 6 months in a moist environment)
Cause prolonged, sever, and life threatening dirrhea in immunocompromised patients (AIDS)
Fig. 39.23
Dinoflagellates
large group found in marine plankton
cause phosphorescence and toxic blooms
symbiotic forms live in association with reef building corals
Ciliophora
found in both benthic and planktonic communities in water and soil systemsuse many cilia as locomotory and feeding organellesreproduction
asexual by transverse binary fissionsexual by conjugation (Fig. 25.18) Fig. 25.17
Chloroplastidaoften referred to as green algaehave chlorophylls a and b, and carotenoidsmany have cellulose cell wallsexhibit a diverse morphology
Chlamydomonas
a haploid nucleus, large chloroplast, conspicuous pyrenoid, and a stigma (eyespot, for phototaxis)
osmoregulation controlled by two small contractile vacuoles at flagella base reproduces by sexual and asexual reproduction