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Morphogenetic Observations on Monostroma

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Morphogenetic Observations on Monostroma

  1. 1. Occurrence, basic cultural characteristics, sex ratio and morphogenetics of Monostroma in Uranouchi Inlet and Ukibuchi of Tosa Bay, Pacific ocean. Felix bast , Usa Marine Biological Institute, 781-1161, Japan April-August 2006
  2. 2. Introduction to the habitat and life cycle
  3. 3. Introducing the genus Monostroma Class Ulvophyceae, Order: Codiolales - Morphology <ul><li>Thalli can grow up to 20cm high and are irregularly undulate and folded. </li></ul><ul><li>Basal part has rhizoids to attach with the substratum. </li></ul>
  4. 4. Introducing the genus Monostroma – Cell structure <ul><li>Multicellular thall us consists of single layer of cells. </li></ul><ul><li>Each cell has one cup shaped chloroplast with single pyrenoid </li></ul>50µm 10µm
  5. 5. Introducing the genus Monostroma - Habitat <ul><li>Monostroma grows attached to the inter-tidal rocks </li></ul><ul><li>Found in warm seas of temperate and subtropics </li></ul>
  6. 6. Introducing the genus Monostroma - Distribution <ul><li>Arctic : Canada (Arctic) ( Taylor 1957 ). </li></ul><ul><li>Asia : Japan ( Yamada 1938 ) India ( G.Deshmukhe, 1998 ), Commander Islands ( Selivanova & Zhigadlova 1997 ) </li></ul><ul><li>Europe : Britain ( Batters 1902 , Newton 1931 , Burrows 1991 , Hardy & Guiry 2003 ), Ireland ( Adams 1907 , Guiry 1978 , Morton 1994 ), Faroes ( Irvine 1982 , Nielsen & Gunnarsson 2001 ), France ( Feldmann 1954 , Coppejans 1995 ), Helgoland ( Bartsch & Kuhlenkamp 2000 ), Iceland ( Caram & Jónsson 1972 ), Ireland ( Batters 1902 , Adams 1907 , Cotton 1912 , Guiry 1978 , De Valéra et al. 1979 , Morton 1994 ), Italy ( Furnari , Cormaci & Serio 1999 ), Netherlands ( Stegenga & Mol 1983 , Stegenga et al. 1997 ), Norway ( Rueness 1997 ), Sweden ( Tolstoy & Österlund 2003 ). </li></ul><ul><li>Atlantic Islands : Azores ( Neto 1994 ). </li></ul><ul><li>North America : Alaska ( Lindstrom 1977 , Scagel et al. 1989 ), British Columbia ( Scagel et al. 1989 ), California ( Abbott & Hollenberg 1976 , Scagel et al. 1989 ), New Brunswick ( Taylor 1957 ), New York ( Taylor 1957 ), Oregon ( Hansen 1997 ), Quebec ( Taylor 1957 ), Washington ( Scagel et al. 1989 ). </li></ul><ul><li>South America : Chile ( Ramírez & Santelices 1991 ). </li></ul><ul><li>Africa : Morocco ( Benhissoune , Boudouresque & Verlaque 2001 ). </li></ul><ul><li>Antarctic and the subantarctic islands : Antarctica ( Papenfuss 1964 ). </li></ul>
  7. 7. Life cycle <ul><li>Five different types of Life cycles have been observed </li></ul><ul><li>On the basis of life-cycle and thallus ontogeny there are some 14 subdivisions of Monostroma are classified </li></ul>
  8. 8. Dimorphic sexual <ul><li>Alternation of generations </li></ul><ul><li>Macroscopic gametophyte,Microscopic sporophyte </li></ul><ul><li>Monostroma nititum </li></ul><ul><li>Monostroma latissimum </li></ul>
  9. 9. Dimorphic sexual <ul><li>Alternation of generations </li></ul><ul><li>Macroscopic sporophyte </li></ul><ul><li>Microscopic gametophyte -discoid thalli </li></ul><ul><li>Monostroma zostericola </li></ul>
  10. 10. Dimorphic asexual <ul><li>Mature thallus and cyst are asexual </li></ul><ul><li>Quadriflagellate swarmers and quadriflagellate zoospores </li></ul><ul><li>Monostroma undulatum </li></ul>
  11. 11. Monomorphic sexual <ul><li>Alternation of generations </li></ul><ul><li>Gametophyte and sporophyte are identical </li></ul><ul><li>Monostroma grevillei </li></ul>
  12. 12. Monomorphic asexual <ul><li>Bi/quadri flagellate asexual swarmers develops to thalli </li></ul><ul><li>No Alternation </li></ul><ul><li>Monostroma oxyspermum </li></ul>
  13. 13. Cultural characteristics
  14. 14. Study area, Usa Latitude = 33.436384 Longitude = 133.440371
  15. 15. Temperature <ul><li>Temperature was measured with analogue thermometer, in-situ. </li></ul>Usa Site 1, May 16
  16. 16. Temperature variation
  17. 17. Salinity Variation
  18. 18. 24 Hrs change in ambient water temperature and salinity at sites on 07-28
  19. 19. Tidal graph showing sampling times         曇り 気温(℃) 31 – 26 降水 確率 30 %) 天気
  20. 22. Thalli collection
  21. 23. Seasonal changes in Thalli length: S1 and S2
  22. 24. Seasonal changes in Thalli length: S4 and S5
  23. 25. Study Area: Ukibuchi Lat 33.035678 , Long: 133.034445
  24. 26. Seasonal changes in Thalli length: Ukibuchi
  25. 27. Sex ratio at 4 sites
  26. 28. Salinity tolerance S1 S4
  27. 29. Standardization A1 A2 5 4 3 45 µmolphotons/m 2 /s Light Intensity S1 Thallus PES (S1) Media
  28. 30. Salinity tolerance S1 samples were found to be more tolerant to the salinity.
  29. 31. Morphogenetic observations in unidentified Monostroma islolated from Usa, Tosa.
  30. 32. Summary of findings <ul><li>Unknown monostroma is observed to be having dimorphic diplo-haplontic life-cycle (alternation of generation) with microscopic sporophyte and macroscopic gametophyte (similar to M nitidum ) </li></ul><ul><li>Thallus ontogeny appears to be different from M nitidum ( absence of saccate stage intermediate from erect filament to monostromatic membrane) </li></ul>
  31. 33. Summary of findings <ul><li>Settled gametes undergo parthenogenesis which is morphogenetically identical to zygote development </li></ul><ul><li>A unique shunting-bypass is observed for a part of female gamete parthenogenesis , that has not been reported elsewhere. </li></ul>
  32. 34. Zygote development illustration
  33. 35. Fertilization <ul><li>Anisogamy occurres between gametes released from dioicious thalli. </li></ul>10 µm 10 µm
  34. 36. Plano zygotes 10 µm
  35. 37. Zygote development illustration
  36. 38. Zygote settlement and development 10µm 10µm In 48 hrs planozygotes lose flagella and settle down the substratum.
  37. 39. Zygote settlement and development 10µm 10µm Distal end swollen to form a new cell, in 7 days by taking various shapes.
  38. 40. Zygote settlement and development 10µm 10µm 10µm Pyrinoid In 1 month most are elliptical and starts forming cysts.
  39. 41. Sporophyte 10µm 10µm Complete maturation of sporophyte takes very long time, 6-8 months.
  40. 42. Sporophyte maturation 10µm 10µm S hape of sporophyte slightly elongate. Upon acquiring motility, zoospores swim away.
  41. 43. Zoospore release Have 4 flagella of same length. Does not have eye spots. 10 µm 10 µm
  42. 44. Zoospore development illustration
  43. 45. Settled zoospore and germination In about 10 Days, first transverse cell division happens. 10 µm 10 µm
  44. 46. Development of zoospore, 4 cell stage 15 days old culture. Thalli appears to have 3D structure 10µm 10µm
  45. 47. Zoospore development illustration
  46. 48. Development of zoospore, 8 cell stage 20 days old (after zoozpore release from sporophyte) culture 10µm 10µm
  47. 49. Zoospore development illustration
  48. 50. Further development of zoospore 3 dimensional erect filament. 30 days old culture 10 µm 10 µm
  49. 51. Formation of microscopic thalli Basal tissue (arrow head) develops into rhizoid. 60 days old culture. 100µm 10 µm
  50. 52. Parthenogenesis <ul><li>Settled male and female gametes undergo parthenogenesis, exactly similar to the zygote maturation </li></ul><ul><li>A ratio of female gametes undergo shunting-bypass such that they directly develop into thalli with out sporophytic stage. This process have not been observed in male gametic parthenogenesis. </li></ul>
  51. 54. Limitations of this study <ul><li>Frequent contamination in the plates by unidentified long filamentous organism </li></ul><ul><li>Actual cytological development during zoospore release from sporophyte was unable to observe or photograph </li></ul>
  52. 55. Prospective research
  53. 56. Ongoing experiments <ul><li>Germination frequency and growth rate analyses of sporophyte at various temperature and salinity conditions </li></ul><ul><li>Statistical analysis of female parthenogenetic bypass </li></ul>
  54. 57. Future plans <ul><li>Ultrastructural observations during zygote maturation and zoospore germination </li></ul><ul><li>Microspectrofluorimetric analysis of nuclear genetic material for the establishment of haploidy/diploidy at various stages </li></ul>
  55. 58. Thank you!

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    Jan. 13, 2013

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