Ch 12 The Eukaryotes: Fungi, Algae, Protozoa, and Helminths

Ch 12 The Eukaryotes: Fungi, Algae, Protozoa, and Helminths

Student Learning Outcomes List the defining characteristics of fungi. Identify two beneficial and two harmful effects of fungi. List the defining characteristics of protozoa. Differentiate an intermediate host from a definitive host. List the distinguishing characteristics of the two classes of parasitic helminths, and give an example of each. Provide a rationale for the elaborate life cycles of parasitic worms. Define arthropod vector. Differentiate between a tick and a mosquito, and name a disease transmitted by each.

FUNGI Chemoheterotroph, aerobic (molds) or facultatively anaerobic (yeasts) Mycology: Study of fungi Most fungi decomposers, few are parasites of plants and animals. # of serious fungal infections increasing Fig. 12.1 Review Table 12.2

Characteristics of Fungi Hyphae: Filaments of cells, mostly septate Mycelium: Mass of hyphae. Molds: mostly filamentous. Yeasts: nonfilamentous, unicellular fungi. Budding yeasts divide asymmetrically. Dimorphic fungi: yeasts like 37 C, molds 25 C. Fungal spores differ from bacterial spores. Form from aerial hyphae. Growth in acidic, low-moisture, high osmotic pressure environments. Copyright Metabolize 2010 Pearson Education, Inc. complex carbohydrates (e.g.: lignin).

Economic Effects of Fungi Saccharomyces cerevisiae: Bread, wine, HBV vaccine Trichoderma: Cellulase Taxomyces: Taxol Entomophaga: Biocontrol Paecilomyces: Kills termites Mold spoilage

Fungal Diseases Mycoses 1. Systemic mycosis: infection deep within body, affects many tissues and organs. Histoplasmosis and coccidiomycosis. 2. Subcutaneous mycosis: Saprophytic fungi, e.g.: Sporotrichosis. 3. Cutaneous mycosis = Dermatomycosis: affects keratin-containing tissues (hair, nails, skin). 4. Superficial mycosis: localized on hair shafts and superficial skin cells. Opportunistic mycoses: caused by normal microbiota or fungi that are not usually pathogenic (E.g.: Candidiasis and Pneumocystis pneumonia) usually systemic.

Human eyelash with unknown fungus infection. Minimal damage to skin or underlying tissues. However, impaired IS can encourage the infecting fungus to proliferate.

ALGAE Mostly photoautotrophs, mostly in ocean Diatoms Unicellular, store energy in form of oil Domoic acid Neurological disease Ingestion of mussels that fed on diatomes (also affects birds and sealions) Dinoflagellates (plankton) Some produce neurotoxins: red tide Kills fish, marine mammals, and humans, e.g.: parasitic shellfish poisoning (PSP)

PROTOZOA Unicellular, eukaryotic chemoheterotrophs. Large and diverse group. Few are pathogenic. Found in soil and water and as normal microbiota in animals. Trophozoite: Vegetative form (feeding and growing). Asexual reproduction via fission, budding, or schizogony (multiple fission). Sexual reproduction via conjugation. Some protozoa can produce a cyst that provides protection during adverse environmental conditions.

Medically Important Protozoa 1. Arcaezoa (lack mitochondria) Trichomonas and Giardia 2. Microspora (no mitochondria and no microtubules) diarrhea and keratoconjunctivitis in AIDS patients 3. Amoebozoa (move via pseudopodia) Entamoeba (dysentery) and Acanthamoeba 4. Apicomplexa: not mobile, intracellular Plasmodium, Babesia, Toxoplasma, Cryptosporidium 5. Euglenozoa: Hemoflagellates Trypanosoma

Amoebozoa Move by pseudopods Entamoeba Acanthamoeba

The Life Cycle of Plasmodium vivax 2 3 8 7 6 Fig 12.18

Euglenozoa Move by flagella Hemoflagellates Trypanosoma spp. Sleeping sickness Chagas disease Fig 23..22

HELMINTHS (Parasitic Worm) Kingdom: Animalia Phylum: Platyhelminthes (flatworms) Class: Trematodes (flukes) Class: Cestodes (tapeworms) Phylum: Nematoda (roundworms) few are human parasites Anatomy and life cycle modified for parasitism Adult stage in definitive host. Each larval stage in specific Copyright intermediate 2010 Pearson Education, Inc. host.

Life Cycle of Helminths Monoecious (hermaphroditic) Male and female reproductive systems in one animal Dioecious Separate male and female Egg larva(e) adult

Platyhelminths Dorsoventrally flattened Trematode, or fluke: Oral and ventral sucker attaches to host tissue Cestode, or tapeworm: Scolex (head), proglottids 4 suckers and rostellum with hooks Fig 12.26 Gravid proglottid with uterine branches

Taenia solium Taenia saginata Human definitive host; pig or cattle intermediate host.

Echinococcus granulosus Fig. 12. 27

Human as Human is. Definitive Host Taenia saginata Cysticerci in beef muscle Intermediate Host Echinococcus granulosus Adult in dog

. Nematodes Roundworms have a complete digestive system Eggs infective for humans: Ascaris lumbricoides: Ascariasis. 2 nd most common worm infection in US. (Most common worldwide; > 1 bio infected) Enterobius vermicularis (pinworm). Most common worm infection in US (30% of children, 16% of adults infected)

Pinworm / Enterobius vermicularis Fig12.28

Do test immediately after waking up. Several samples might need to be examined. Since scratching of the anal area is common, samples taken from under the fingernails may also contain eggs. Diagnosing Pinworm Disease pinworm paddle

Larvae Infective for Humans Fig 25.23 Hookworms Ancylostoma duodenale and Copyright Necator 2010 Pearson Education, americanus Inc.

Trichinellosis: The Life Cycle of Trichinella spiralis

The Heartworm Dirofilaria immitis Primarily in dogs and cats human heart failure, also in human lungs Spread via mosquitoes Fig 12.29

ARTHROPODS AS VECTORS Kingdom: Animalia Phylum: Arthropoda (exoskeleton, jointed legs, segmented body) Class: Insecta (6 legs) Lice, fleas, mosquitoes Class: Arachnida (8 legs) Mites and ticks Arthropods that carry diseases are called vectors. Elimination of vectorborne diseases best via control or eradication of vectors.

Arthropod Vectors Mechanical transmission Biological transmission Microbe multiplies in vector Definitive host Microbe s sexual reproduction in vector Fig 12.32