The Arcellanids. Kingdom Protozoa. Phylum Amoebozoa 2/4/2016. Gymnamoebae naked, lobose. The Amoebozoa. Chaos Amoeba proteus Acanthamoeba soil and FW

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1 The Arcellanids Kingdom Protozoa The Amoebozoa Phylum Amoebozoa Gymnamoebae naked, lobose Chaos Amoeba proteus Acanthamoeba soil and FW Can cause eye infections 1

2 Phylum Amoebozoa Arcellinids lobose, test-bearing amoebae Arcella Difflugia soil and FW Slime Molds Acellular slime molds Cellullar Slime Molds Dictyostelium Acellular Physarum polycephalum Mastigamoeba longifilum 2

3 Mastigamoebae Mastigamoebae Close evolutionary relationship between cellular slime molds and flagellates (rrna) Disc shaped mitochondria Found in stagnant water: FW and marine Have pseudopods and flagella f Mastigamoeba aspera Entamoeba histolytica Major cause of amebic dysentery 0.5 to 50% of the population Highest infection rate in underdeveloped countries. 1 to 3% of the population of the USA are infected. Infection is associated with poor hygiene. Humans are the principal host; dogs, cats and rodents may be infected. 3

4 trophozoite trophozoite Superphylum Excavata Related to some of Earth s earliest eukaryotes Named for a feeding groove excavated into the cells of many representatives Food particles are taken into cells by phagotrophy Endocytosis and evolutionary basis for endosymbiosis 4

5 Superphylum Excavata Superphylum Excavata Primitive flagellates with multiple flagella & feeding groove Flagellated protozoans Single-celled heterotrophs with flagella Unwalled cells, pellicle retains shape Jakoba libera Lack Golgi apparatus, mitochondria lacking in some, highly modified in others Some important human parasites Giardia Trichomonas Trypanosoma Super Phylum Excavata Giardia and some other excavates lack mitochondria. This condition is probably not ancestral, therefore it is a derived feature. Two separate haploid nuclei look like big eyes! Metamonada Other excavates (e.g. Jakoba) have the most complete mitochondrial genome known - closest to bacterial genome - therefore primitive. Mitochondrial genome of other eukaryotes is greatly reduced by gene transfer to cell nucleus Excavata - (excavate - feeding groove (excavation) that terminates in a cytostome on the cell surface, usually associated with a posteriorly-directed flagellum; not present in all excavate taxa) Giardia intestinalis Clade = Diplomonads Unicellular heterotrophic flagellates with one or two karyomastigonts per cell (flagella or basal bodies in characteristic groups of four often associated with the nucleus) Have lost some typical excavate and fornicate characters Secondary loss of mitochondria Morphology appears derived Metamonada Giardia spp. 5

6 Giardia intestinalis (lamblia) Causal Agents Giardia duodenalis is a protozoan flagellate (Diplomonadida). Giardiasis Water in wilderness areas is often contaminated with cysts from animal feces. Cysts hatch in intestines and release trophozoites. Always boil and/or treat water before drinking. Giardiasis Clade Clinical Features: Disease varies from asymptomatic to severe diarrhea and malabsorption. Acute giardiasis develops after an incubation period of 1 to 14 days (average of 7 days) and usually lasts 1 to 3 weeks. Symptoms include diarrhea, abdominal pain, bloating, nausea, and vomiting. In chronic giardiasis the symptoms are recurrent and malabsorption and debilitation may occur. Chilomastix Chilomastix Causal Agents Chilomastix mesnili, a nonpathogenic flagellate Subphylum Parabasala Mostly symbiotic No mitochondria have Hydrogenosomes instead Ancient or derived? Multiple flagella (hypermastigote) Parabasal bodies- modified Golgi apparatus All are symbiotes in animals Examples: Trichonympha, Trichomonas 6

7 Subphylum Parabasala Class Hypermastigia Termite gut symbionts Trichonympha, Holomastigotes, Spironympha Jacoba Class Trichomonadea Trichomonas vaginalis Class Hypermastigia Termite symbiotes Guts of termites, wood roaches, other woodeating insects. Digestion of celluloseecologically critical function. Acquisition at hatching and molting. Mutualism Mutualistic bacteria inside Trichonympha et al. digest the wood. Trichonympha Eastern termite: Reticulitermes flavipes 12 symbiotic flagellates found in the gut (Yamin, M. A Sociobiology, 4: 3-119) 1. Dinenympha fimbriata 2. Dinenympha gracilis 3. Holomastigotes elongatum 4. Microjoenia fallax 5. Monocercomonas sp. 6. Personympha major 7. Personympha vertens 8. Spironympha kofoidi 9. Spirotrichonympha flagellata 10. Spirotrichonympha sp. 11. Trichomonas trypanoides 12. Trichonympha agilis Joseph Leidy Prominent American biologist- Univ. of Pennsylvania. Vertebrate paleontology, parasitology, other fields Class Hypermastigia Trichonymphs Trichonymphs (phylum Axostylata) are excavates with hundreds of flagella They live in the guts of wood-eating termites and cockroaches Feed on wood particles consumed by the host insect They rely on endosymbiotic bacteria to digest cellulose So insect gets the energy and carbon from bacterial metabolism a long trip from wood! Trichonympha 7

8 Termite gut symbionts Class Trichomonadea Streblomastix Trichonympha Class Trichomonadea Trichomonadea Trichomonas vaginalis Commensal or parasitic flagellates with axostyle and parabasal body Trichomonas vaginalis (far right) in human urogenital tract. Trichomonas vaginalis Trichomoniasis = STD Clinical Features: Trichomonas vaginalis infection in women is frequently symptomatic. Vaginitis with a purulent discharge is the prominent symptom, and can be accompanied by vulvar and cervical lesions, abdominal pain, dysuria and dyspareunia. The incubation period is 5 to 28 days. In men, the infection is frequently asymptomatic; occasionally, urethritis, epididymitis, and prostatitis can occur. 8

9 Heterolobosea Amoebae, amoeboflagellates and flagellates Naegleria Naegleria fowleri Brain-eating amoeba Sinus Rinsing & Neti Pots Ritual Nasal Rinsing & Ablution Public Drinking Water Systems You cannot get infected from drinking water contaminated with Naegleria. You can only be infected when contaminated water goes up into your nose Naegleria fowleri Naegleria fowleri is normally found in the natural environment and is well adapted to surviving in various habitats, particularly warm-water environments. Although the trophozoite stage is relatively sensitive to environmental changes, the cysts are more environmentally hardy. There are no means yet known that would control natural N. fowleri levels in lakes and rivers. 1. Water carries N. fowleri into the nasal cavity. 2. Amoeba attaches itself to the olfactory nerves and eats its way up to the brain through the cribriform plate. 3. The amoeba attack the olfactory bulb, leading to inflammation and infection of the brain. 4. Primary amoebic meningoencephalitis (PAM). Superphylum Excavata Phylum Euglenozoa Class Kinetoplastea Bodo Trypanosoma spp Toxoplasma gondii Subphylum Euglenoida Euglena - photosynthetic Peranema - phagotrophic Astasia - osmotrophic 9

10 Euglenids Phylum Euglenozoa Today s euglenids are the modern representatives of an ancient line of life, so different from other protists that some biologists have suggested placing them in a kingdom of their own. Class Euglenida a Order Euglenia Kinetoplastea and Euglenida Only! a Subphylulm Euglenoida 10

11 Class Euglenida Order Euglenia Flagellates named for Euglena Disk-shaped mitochondrial cristae Discicristates Cristae in most eukaryotes are flattened or tube shaped. Unknown if these cristae function differently. Class Euglenida Discicristates Discicristates Euglenids Euglenoids have unique interlocking protein strips beneath plasma membrane Pellicle Flexible can crawl through mud euglenoid movement or metaboly Unique among eukaryotes Consists of the plasma membrane, a series of proteinaceous strips underneath the plasma membrane, and groups of microtubules associated with each strip. Species with longitudinal strips have rigid cells; no metaboly Species with spirally placed strips are flexible; have metaboly Pellicle Class Euglenida Euglena: many are heterotrophic, some are photosynthetic. Eyespot (stigma): light sensing system. Also there are light-sensing molecules at swollen region at the base of a flagellum. Class Euglenida Most euglenoids live in freshwater Some have chloroplasts that arose by secondary endosymbiosis from a green alga Contractile vacuoles expel excess water 11

12 Euglenids Euglena Photosynthetic species Store paramylon starch in single pyrenoid Have photosensitive eyespot or stigma, that helps orient towards light Heterotrophic species can either absorb nutrients from water or may feed on bacteria Two flagella Long one has mastigonemes and is used for motility Second short flagella is not used for swimming No sexual reproduction ever reported Paramylon starch around pyrenoid Contractile vacuole Euglena gracilis paramylon Click here for movie of metaboly in Euglena Euglena acus slide 12

13 Peranema Peranema - notice the pellicle Anatomy similar to Euglena without the chloroplasts and pyrenoids. Peranema e Peranema is a predator, capturing and engulfing smaller euglenids. Two rods, located in the mouth area, are used to hold prey during engulfment. In the euglenid line, as in most other flagellated protists, individuals divide longitudinally. Division begins with duplication of the basal body at the base of the flagellum creating a cell with two flagella that then splits right down the middle. Class Kinetoplastea Unique microtubular cytoskeleton Free living, symbiotic & parasitic Most are parasites Affect animals, plants and other protozoans Have a single giant mitochondrion Biting insects are vectors Example: Trypanosomes Class Kinetoplastea Includes important parasites of man and domestic animals: Trypanosoma, Leishmania Digenetic life cycle (two hosts) vertebrate Gut of blood-feeding insect (vector) 13

14 Class Kinetoplastea Possess kinetoplast region of mitochondrion Kinetoplastids: also have a peroxisome Contains glycolytic enzymes Glycolysis may not occur in the cytosol! Flagellum adheres to cell via membrane Trypanosomes (Kinetoplastids) Trypanosomes are colorless, mostly pathogenic parasites They reproduce asexually by mitosis Kinetoplast contains extranuclear DNA Trypanosoma brucei (gambiense) causes African sleeping sickness T. cruzi causes Chagas disease of Central and South America and now potentially in the U.S. Red blood cells Tsetse fly Tsetse Fly Vectors of trypanosome diseases Kissing bug Trypanosome with undulating membrane Flagellum Trypanosomes in blood smear 25 µm 14

15 Trypanosoma cruzi Chagas disease Figure 5.27 Trypanosomiasis T. cruzi life cycle Transmitted to man via feces of bug Intracellularreproduces asexually, forming pseudocysts. Return to bloodstream and picked up by bug with blood meal. Do not show antigenic variation. Triatomine refers to the subfamily Triatominae of the family Reduviidae Chagas Disease Clinical Features: A local lesion can appear at the site of inoculation. The acute phase is usually asymptomatic, but can present with manifestations that include fever, anorexia, lymphadenopathy, mild hepatosplenomegaly, neurological disorders, & myocarditis. Most acute cases resolve over a period of 2 to 3 months into an asymptomatic chronic stage. The symptomatic chronic stage may not occur for years or even decades after initial infection. Its manifestations include cardiomyopathy; pathologies of the digestive tract such as megaesophagus and megacolon; and weight loss. Chronic Chagas disease and its complications can be fatal. Charles Darwin may have contracted this disease in Chile during his voyage on the H.M.S. Beagle, which resulted in his infirmity in later life. Trypanosomiasis American trypanosomiasis (Chagas disease) T. cruzi insect host: Triatoma (Order Hemiptera) Trypanosoma cruzi million persons are infected 100 million are at risk 50,000 deaths annually leading cause of heart disease in South and Central America 15

16 Kinetoplastida Trypanosoma T. rhodesiense and T. gambiense cause African sleeping sickness in man. T. brucei causes nagana in ungulates (hoofed mammals). Insect host: tse-tse flies, Glossina Trypanosomiasis African sleeping sickness Often fatal if untreated. Anemia, fever, edema due to swollen lymph nodes. Neurological symptomsdementia, lethargy, paralysis. Controlled in past decades by anti-tse-tse programs- now increasing again. 300,000 cases/year African Sleeping Sickness 1. Bite reaction 2. Parasitemia Attacks of fever which starts 2-3 weeks after the bite 3. CNS stage Changes in character and personality 4. Terminal stage is marked by wasting and emaciation 5. Death results from coma, intercurrent infection or cardiac failure African trypanosomes Quick-change artists - antigenic variation Fluctuating parasite numbers Antigenically distinct forms. VSG (variant surface glycoprotein) coats cell surface. Cells switch between different versions of VSG. Shed VSG causes problems VSG 16

17 Kinetoplastida Leishmania Vector: biting sandflies, Phlebotomus (Order Diptera) Zoonosis = mainly parasite of animals that also infects man Reservoir hosts- various mammals- rodents, carnivores (including dogs) Leishmania sp. amastigotes in a Giemsa-stained tissue scraping. Leishmania sp. amastigotes; touch-prep stained with Giemsa Leishmaniasis Intracellular - infects macrophages in mammal hosts. Visceral leishmaniasis suppresses immune response by destroying macrophages in lymph nodes, liver and spleen Cutaneous leishmaniasis causes skin ulcers. Mucosal leishmaniasis causes ulcerations of mouth, nose million clinical cases/year- estimate 12 million infected. >90% of the world's cases of visceral leishmaniasis are in India, Bangladesh, Nepal, Sudan, and Brazil. 17

18 Leishmaniasis Treatment Systemic therapy (parenteral by IV) Systemic therapy (oral) Local (topical, heat, cold) Problems Toxicity of drugs Recurrence of resistant disease Non-human reservoirs ex. dogs 18