4/6/2015. Today: The Euks. 1. Fungi 2. Protozoa 3. Multicellular Parasites. Fungi

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1 Today: The Euks 1. Fungi 2. Protozoa 3. Multicellular Parasites Fungi 1

2 Fungal characteristics Cell wall made of chitin = polysaccharide Heterotrophs absorptive nutrition Eukaryotes have true nuclei, can be coencytic = more than one nucleus per cell Unicellular Yeasts and multicellular Molds individual units of mold are called hyphae and many intertwined hyphae is a mycelium = body of the mold Fungal cell wall/cell membrane Chitin Chitin protection against dessication and phagocytosis In cell membrane, the steroid utilized is called Ergosterol stabilizing agent This is the target of many anti-fungal drugs 2

3 Ergosterol Inhibition of Ergosterol synthesis 3

4 Fungal Growth Yeasts Molds Favorable conditions for Fungal Growth Oxygen: most are aerobic; exception = yeast are facultative ph: most fungi prefer slightly acidic conditions (ph ~ 5) Temperature: most fungi prefer room temperature (~25 C); exceptions are human pathogens which prefer body temperature (37 C) Nutrients: fungi secrete enzymes that break down materials in the environment, then absorb them (YUM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) 4

5 Fungal Mutualism Mycorrhiza Symbiotic relationship where both organisms benefit!!!!!! Lichens Sleepy Grass Mycorrhiza Fungal associations with plant roots Fungus gives water and minerals to the plant, and receives sugars in return 5

6 Lichens Associations between fungi and algae (or less commonly cyanobacteria) Water and minerals given in return for sugar Sleepy Grass Association between fungus and blades of grass Fungus gives water and a toxin to the grass that puts grazing animals to sleep (cows/goats/horses) for up to one week Animals learn to avoid this grass 6

7 Fungal Reproduction Yeast: reproduce via budding / mitosis usually; however, sometimes two yeast get together and conjugate / exchange DNA Molds: reproduce via spores = structures that can give rise to new hyphae; spores are formed sexually and asexually A Typical Fungal Life Cycle 7

8 Classification of Fungi Lower Fungi = fungus-like protists --- water molds, slime molds, and chytrids True Fungi --- Zygomycota, Ascomycota, Basidiomycota, and Deuteromycota Review: 5 Kingdoms of Life 1. Animals 2. Plants 3. Fungi 4. Protista: algae, protozoa, lower fungi 5. Monera: Eubacteria and Archae (proks) 8

9 Water Mold (Oomycota) Cellulose in cell wall, not chitin!! Reproduces by spores, but the spores have flagella Example: Phytophora infestans started the great potato blight of Ireland It has plant and animal-like characteristics, But is technically a lower fungi Slime molds Have unicellular and multi-cellular stages Crawls along rocks and logs at 1 inch per day Reproduces via spores 9

10 Chytrids Chytridomycosis Live in water, have flagellated spores Chitin in cell wall Cause diseases in amphibians (e.g. frogs) Zygomycota True Fungus chitin, spores, hyphae, etc. During sexual reproduction, two hyphae fuse and form a large black zygote, which can give rise to new spores Bread Mold 10

11 Ascomycota Spores form in a sac or a cup-like structure called an ascus Examples: 1. Aspergillus contaminates crops like wheat corn peanuts and leaves a toxin there = carcinogen (aflatoxin) 2. Truffle: delicacy that costs big $$$ Aflatoxin 11

12 Basidiomycota Spores form on tiny pedestal-like structures called basidia, which line the hyphae and look like bumps or steps Example: mushrooms -- watch out for Amanita mushrooms which have a deadly toxin (liver poison) Life Cycle of a Typical Basidiomycete 12

13 Amanita Deuteromycota Have no known sexual reproduction Example: trichophyton athlete s foot fungus 13

14 Yeasts Saccharomyces Comparison of Fungi to Plants and Animals 14

15 Later: Fungal Diseases of Humans Aspergillosis Blastomycosis Candidiasis Coccidioidomycosis Cryptococcosis Histoplasmosis Paracoccidiomycosis Sporotrichosis Zygomycosis Protozoa Live near water (usually) Aerobic Saprobes and Parasites Usually unicellular Cause MANY diseases Eukaryotes have a nucleus and organelles Can have some special structures: 1. Contractile Vacuole: moves excess water out of cell 2. Pellicle: rigid outer covering over cell membrane 15

16 Diversity among Protozoa Classified according to their movement style; or lack of movement Include: 1. Amoebas 2. Flagellates 3. Ciliates 4. Apicomplexans Protozoa: Nutrition Take 2 different forms depending on nutrient availability: A. Cyst: resistant structure, not dividing, forms when little food around B. Trophozoite: feeding and dividing form 16

17 Amoebas Creep toward food sources using pseudo-pods false feet Squeeze cytoplasm using rings of actin/myosin into temporary projections of the cell membrane Also use pseudopods for endocytosis (feeding) on others Divide: Binary fission (like bacteria) Forams at the White Cliffs of Dover 250MYA this amoeba was very prevalent Have chalky calcium carbonate skeletons 17

18 Flagellates Have a whip-like tail similar in structure to sperm Move toward food sources and ingest them (re: animal-like) Example: Caduceria, lives in the termite gut and digests cellulose in wood chips Trypanosomes moving among RBCs Courtesy: Benjamin Cummings 18

19 Ciliates Have a network of fibers/proteins held under cell membrane; Contract them simultaneously ( beating ) for movement Can sweep food toward a primitive mouth /opening Paramecium Tough: produces toxins that are released to kill other cells; has genes called kappa factors that produce them. Has harpoon-like structures called trychocysts that can be released (defensive filaments). When under stress, they get together and exchange DNA (sexual recombination) 19

20 Trichocysts (Paramecium) Apicomplexans Born with flagella, but lose them after they invade a host cell Have enzymes at top end to help them penetrate host cells Example: Plasmodium, which invades RBCs and causes Malaria 20

21 List of Protozoan Diseases Amoebiasis Primary amoebic meningoencephalitis Giardiasis Trichomoniasis Trypanosomiasis (African Sleeping Sickness) Leishmaniasis Balantidiasis Toxoplasmosis Malaria Babesiosis Cyclosporiasis Multicellular Parasites ANIMALS: WORMS TICKS LICE FLEAS MITES + OTHERS 21

22 Flatworms FLUKES AND TAPEWORMS -- bilateral symmetry: equal L+R halves when cut longitudinally -- digestion is simple: opening with a sac; food down, waste up on same tract -- many are hermaphrodites Flukes Have a sucker at one end to attach to organs Often use snails or fish as intermediate hosts (houses larval stages of worm) May infect humans or other animals as definitive host (houses adult worm) Cause damage when they interfere with normal organ function (numbers are high) 22

23 Fluke Organ Targets Intestines Lungs Liver Blood Bladder Skin Gall Bladder The Life Cycle of the Blood Fluke, Schistosoma mansoni 23

24 The Life Cycle of the Chinese Liver Fluke, Clonorchis sinensis Tapeworms Can reach 45 meters in length Block the intestine and eat nutrients there. Have head = scolex, neck, and a series of ribbon-like segments (proglottids) Final / terminal proglottids house the eggs; break off and eggs are released 24

25 Tapeworm and Undercooked Foods Fish Beef Pork The Life Cycle of the Fish Tapeworm, Diphyllobothrium latum 25

26 Roundworms Very common; occupy soil, water, land, all across the planet Digestion: two openings Separate sexes Infect people via: meats / diapers / pets / fruits + vegetables Roundworm Diseases Trichinosis: associated with pigs Hookworm disease: blood lungs intestine Pinworm disease: live at end of intestinal tract Whipworm disease: have long whip-like tail Anisakiasis: sushi disease; avoid herring/cod Filariasis: worm blocks lymphatics -- elephantiasis EYE WORM!!!! 26

27 Roundworm Disease Targets Intestines Muscles Lymphatic system Skin (ulcers) Eyes The Life Cycle of Trichinella spiralis 27

28 Pinworm Diagnosis The Life Cycle of the Hookworms A. duodenale and N. americanus 28

29 Lymphatic Filariasis Eyeworm (Loa Loa) 29