Volvocine Line

1. Volvocine Line Evolution of Multicellularity in flagellated green algae

2. Chlamydomonas

5. Volvoxsee also Volvocine Evolutionnotes

6. Protozoan Biodiversity A guide to the major groups Species seen in lab are marked with a

9. Bauplan for protozoa • Small size (high SA:V) because of limitations imposed on by diffusion; allows for efficient nutrient assimilation (in photoautrotrophs and mixotrophs), excretion, and gas exchange • Locomotion provided by pseudopodia, cilia or flagella

10. Bauplan for protozoa • Feeding/nutrition: • Photoautotrophs • Heterotrophs • Pinocytosis (cell drinking dissolved nutrients) • Osmotroph - rely on uptake of small organic molecules • Phagocytosis (cells eating solid particles) • Use food vacuoles for intracellular digestion • Some such as those with fixed shapes, may have • Cytostome (“cell mouth”) and • Cytoproct (“cell anus”) • Mixotrophs - heterotrophs or photoautotrophs

11. Bauplan for protozoa • Very sensitive to external stimuli, but do not have a nervous system; some may have sensory cilia • May respond to • Light • Mechanical stimuli • Chemical gradients • Temperature gradients; • Reproduction varies: sexual or asexual (binary fission, multiple fission, budding)

12. Supergroups • Excavata: feeding groove, phagotrophy • Euglenozoa: flagella, Euglena mitochondria • Archaeplastida: algae • Alveolata: alveoli • Stramenopila: very diverse, straw-like hairs on flagella • Rhizaria: plankton, pseudopodia • Amoebozoa: pseudopodia, slime molds • Opisthokonta: single posterior flagellum

14. Phylogeny

15. Supergroup 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

16. Supergroup Excavata Jakoba libera • Flagellated protozoans • Single-celled heterotrophs with flagella • Unwalled cells, pellicle retains shape

17. ZooflagellatesExcavata (clade?) • Primitive flagellates with multiple flagella & feeding groove • Lack Golgi apparatus, mitochondria lacking in some, highly modefied in others • Some important human parasites • Giardia • Trichomonas • Trypanosoma

18. Excavata, continued • Giardia and some other excavates lack mitochondria. • This condition may be primitive or derived. • Two separate haploid nuclei – look like big eyes! • 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

19. Excavata - (excavate - feeding groove that terminates in a cytostome on the cell surface, usually associated with a posteriorly-directed flagellum; not present in all excavate taxa) • Diplomonadida • Giardia • Parabasala • Trichomonads Trichomonas vaginalis • Trichonymphs Trichonympha spp • Euglenozoa • Trypanosomes Trypanosoma spp

20. Diplomonadida and Parabasala • Group that lacks mitochondria • Evolved before eukaryotes acquired mitochondria • But recent evidence may suggest that these groups actually lost their mitochondria • Multiple flagella

21. Diplomonadida* and Parabasala** • Giardia lamblia* • Trichonympha* • Trichomonas vaginalis**

23. Giardia intestinalis (lamblia)

24. Giardia intestinalis

25. 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. • Print out full size slide of life cycle of parasite.

26. Giardiasis • 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.

27. FlagellatesParabasalids • Multiple flagella (hypermastigote) • Parabasal bodies- modified Golgi apparatus • Lack mitochondria • All are symbiotes in animals • Examples: Trichonympha, Trichomonas Trichonympha

28. 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!

29. ParabasalidsTermite symbiotes • Guts of termites, wood roaches, other wood-eating insects. • Digestion of cellulose- ecologically critical function. • Acquisition at hatching and molting. • Mutualism • Mutualistic bacteriainsideTrichonympha et al.digest the wood. Trichonympha

30. Eastern termite: Reticulitermes flavipes12 symbiotic flagellates found in the gut(Yamin, M. A. 1979. Sociobiology, 4: 3-119) • Dinenympha fimbriata • Dinenympha gracilis • Holomastigotes elongatum • Microjoenia fallax • Monocercomonas sp. • Personympha major • Personympha vertens • Spironympha kofoidi • Spirotrichonympha flagellata • Spirotrichonympha sp. • Trichomonas trypanoides • Trichonympha agilis 7. 12. 2.

31. Joseph Leidy 1823-1891 Prominent American biologist- Univ. of Pennsylvania. Vertebrate paleontology, parasitology, other fields

32. Trichonympha

33. Termite gut symbionts Streblomastix Trichonympha

35. ParabasalidsTrichomonads • Commensal or parasitic flagellates with axostyleand parabasal body • Trichomonas vaginalis (far right) in human urogenital tract.

36. 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.

37. Trichomonas vaginalis

39. Euglenids Phylum Euglenozoa Today’s euglenids are a modern rep-resentative of an ancient line of life, so different from other protists that some biologists have suggested placing them in a kingdom of their own.

44. Supergroup Euglenozoa • Supergroup of flagellates named for Euglena • Disk-shaped mitochondrial cristae • Euglenoids have unique interlocking protein strips beneath plasma membrane • Pellicle • Can crawl through mud – euglenoid movement or metaboly

45. Euglenozoa Discicristates Discicristates

46. Euglenozoa • Most euglenoids live in freshwater • Some have chloroplasts that arose by secondary endosymbiosis from a green alga • Contractile vacuoles expel excess water

48. Euglenozoa • Kinetoplastids have an unusually large mass of DNA (kinetoplast) • Trypansosoma brucei • Most are parasites • Have a single giant mitochondrion • Biting insects are vectors • Example:Trypanosomes

50. FlagellatesKinetoplastida • Possess “kinetoplast” region of mitochondrion • Flagellum adheres to cell via “membrane” • Includes important parasites of man and domestic animals: Trypanosoma, Leishmania • Digenetic life cycle (two hosts) • vertebrate • Gut of blood-feeding insect (vector)