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Introduction to Kingdom Stramenopila

Introduction to Kingdom Stramenopila. Pl P 421/521 Lecture 20. Kingdom Stramenopila. Also “ Straminipila”, colloquial name ‘stramenopiles’ Includes diatoms, chrysophytes, brown algae and some protozoa Phyla of fungal-like organisms: Hyphochytriomycota Labyrinthulomycota Oomycota.

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Introduction to Kingdom Stramenopila

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  1. Introduction to Kingdom Stramenopila Pl P 421/521 Lecture 20

  2. Kingdom Stramenopila • Also “Straminipila”, colloquial name ‘stramenopiles’ • Includes diatoms, chrysophytes, brown algae and some protozoa • Phyla of fungal-like organisms: • Hyphochytriomycota • Labyrinthulomycota • Oomycota

  3. Stramenopiles • Name means “straw hair” and was introduced by D. J. Patterson in 1989 based on tinsel-type flagellum • Presence of filamentous thallus in stramenopiles and Fungi is evidence of convergent evolution http://Microscope.mbl.edu

  4. Convergent Evolution • Evolution of similar features independently in different evolutionary lineages, usually by different developmental pathways

  5. Eukaryotes--From Tree of Life Project http://tolweb.org/tree?group=Eukaryotes&contgroup=Life

  6. Stramenopiles Mitchell L Sogin and David J. Patterson

  7. Phylum Hyphochytriomycota • Occur in soil, fresh water and marine habitats • Saprotrophs or parasites on algae and fungi • Hyperparasites of Oomycete oospores and spores of AM fungi • Closely related to Oomycota

  8. Characters • Cell walls contain chitin and cellulose • Thallus types similar to chytrids • Holocarpic or eucarpic (mono- or polycentric) • Zoospores with one anteriorly inserted tinsel flagellum • Sexual reproduction poorly known • 2 families, 6 genera, 23 species

  9. holocarpic Eucarpic/ monocentric Eucarpic/polycentric zoospore encystment germination Thallus types in hyphochytrids

  10. Hyphochytrium catenoides Eucarpic, polycentric thallus photo by D. J. S. Barr

  11. Phylum Labyrinthulomycota • Called marine slime molds • Parasitic or saprotrophic • On marine organisms such as mollusks, aquatic plants or on organic debris • Labyrinthula zosterae responsible for wasting disease of eelgrass (Zosteramarina)

  12. Characteristics • Ectoplasmic net produced by bothrosomes (sagenogens) • Thallus covered with thin, golgi-derived scales • Biflagellate zoospores with long, tinsel flagellum and shorter whiplash flagellum

  13. Classification • Two families: • Labyrinthulaceae (labyrinthulids) • Spindle-shaped trophic cells glide through ectoplasmic net • Zoospores have eyespots • Thraustochytriaceae (thraustochytrids) • Thallus covered with scales, anchored by ectoplasmic net and converted into zoosporangium • Zoospores lack eyespots, covered with layer of scales

  14. Ectoplasmic net formed from bothrosomes; trophic cells have a single layer of golgi-derived scales Trophic cells surrounded by ectoplasmic net Labyrinthula zoospores contain a dark eyespot, but lack surface scales Zoospores lack an eyespot and are surrounded by a single layer of scales Thraustochytrium thallus wall composed of layered scales formed by golgi apparatus Thraustochytrium

  15. Labyrinthula Ectoplasmic net http://www.botany.uga.edu/zoosporicfungi/labyrint.htm

  16. Labyrinthula trophic cells bothrosome http://www.arches.uga.edu/~charla/labies.html

  17. Eelgrass (Zostera marina) • Eelgrass beds are an important component of coastal areas: • provide habitat to a diversity of animals • Provide food for overwintering waterfowl • Provide erosion protection

  18. Wasting Disease of Eelgrass • Eelgrass populations on both sides of the Atlantic underwent major decline in 1930s • Recovery occurred slowly over 40 year period • Second decline occurred in 1980s • Causal agent identified as Labyrinthula zosterae

  19. Rapid Blight Disease in Turf • Labyrinthula sp. was isolated from cool season turfgrasses including Poa (bluegrass), Lolium (ryegrass) and Agrostis (bentgrass) in 11 states in U.S. and now also in Scotland • First observed in southern CA in 1995 • In Arizona, it is associated with high salinity irrigation water http://www.bspp.org.uk/ndr/july2005/2005-41-2.jpg

  20. Thraustochytrids • Ectoplasmic net and enzymes produced by thraustochytrids can grow into and degrade aquatic plants, mollusk shells, etc. • Schizochytrium and Thraustochytrium are used for commercial production of omega-3-fatty acids

  21. Making food from water--Invisible but invaluable: raised in steel tanks, a tiny marine creature is capable of producing Omega-3 fat, a product in great demand. http://www.ntnu.no/gemini/2005-01e/food.htm

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