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Morphogenetic Observations on Monostroma
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Morphogenetic Observations on Monostroma

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    Morphogenetic Observations on Monostroma Morphogenetic Observations on Monostroma Presentation Transcript

    • 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
    • Introduction to the habitat and life cycle
    • Introducing the genus Monostroma Class Ulvophyceae, Order: Codiolales - Morphology
      • Thalli can grow up to 20cm high and are irregularly undulate and folded.
      • Basal part has rhizoids to attach with the substratum.
    • Introducing the genus Monostroma – Cell structure
      • Multicellular thall us consists of single layer of cells.
      • Each cell has one cup shaped chloroplast with single pyrenoid
      50µm 10µm
    • Introducing the genus Monostroma - Habitat
      • Monostroma grows attached to the inter-tidal rocks
      • Found in warm seas of temperate and subtropics
    • Introducing the genus Monostroma - Distribution
      • Arctic : Canada (Arctic) ( Taylor 1957 ).
      • Asia : Japan ( Yamada 1938 ) India ( G.Deshmukhe, 1998 ), Commander Islands ( Selivanova & Zhigadlova 1997 )
      • 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 ).
      • Atlantic Islands : Azores ( Neto 1994 ).
      • 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 ).
      • South America : Chile ( Ramírez & Santelices 1991 ).
      • Africa : Morocco ( Benhissoune , Boudouresque & Verlaque 2001 ).
      • Antarctic and the subantarctic islands : Antarctica ( Papenfuss 1964 ).
    • Life cycle
      • Five different types of Life cycles have been observed
      • On the basis of life-cycle and thallus ontogeny there are some 14 subdivisions of Monostroma are classified
    • Dimorphic sexual
      • Alternation of generations
      • Macroscopic gametophyte,Microscopic sporophyte
      • Monostroma nititum
      • Monostroma latissimum
    • Dimorphic sexual
      • Alternation of generations
      • Macroscopic sporophyte
      • Microscopic gametophyte -discoid thalli
      • Monostroma zostericola
    • Dimorphic asexual
      • Mature thallus and cyst are asexual
      • Quadriflagellate swarmers and quadriflagellate zoospores
      • Monostroma undulatum
    • Monomorphic sexual
      • Alternation of generations
      • Gametophyte and sporophyte are identical
      • Monostroma grevillei
    • Monomorphic asexual
      • Bi/quadri flagellate asexual swarmers develops to thalli
      • No Alternation
      • Monostroma oxyspermum
    • Cultural characteristics
    • Study area, Usa Latitude = 33.436384 Longitude = 133.440371
    • Temperature
      • Temperature was measured with analogue thermometer, in-situ.
      Usa Site 1, May 16
    • Temperature variation
    • Salinity Variation
    • 24 Hrs change in ambient water temperature and salinity at sites on 07-28
    • Tidal graph showing sampling times         曇り 気温(℃) 31 – 26 降水 確率 30 %) 天気
    •  
    •  
    • Thalli collection
    • Seasonal changes in Thalli length: S1 and S2
    • Seasonal changes in Thalli length: S4 and S5
    • Study Area: Ukibuchi Lat 33.035678 , Long: 133.034445
    • Seasonal changes in Thalli length: Ukibuchi
    • Sex ratio at 4 sites
    • Salinity tolerance S1 S4
    • Standardization A1 A2 5 4 3 45 µmolphotons/m 2 /s Light Intensity S1 Thallus PES (S1) Media
    • Salinity tolerance S1 samples were found to be more tolerant to the salinity.
    • Morphogenetic observations in unidentified Monostroma islolated from Usa, Tosa.
    • Summary of findings
      • 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 )
      • Thallus ontogeny appears to be different from M nitidum ( absence of saccate stage intermediate from erect filament to monostromatic membrane)
    • Summary of findings
      • Settled gametes undergo parthenogenesis which is morphogenetically identical to zygote development
      • A unique shunting-bypass is observed for a part of female gamete parthenogenesis , that has not been reported elsewhere.
    • Zygote development illustration
    • Fertilization
      • Anisogamy occurres between gametes released from dioicious thalli.
      10 µm 10 µm
    • Plano zygotes 10 µm
    • Zygote development illustration
    • Zygote settlement and development 10µm 10µm In 48 hrs planozygotes lose flagella and settle down the substratum.
    • Zygote settlement and development 10µm 10µm Distal end swollen to form a new cell, in 7 days by taking various shapes.
    • Zygote settlement and development 10µm 10µm 10µm Pyrinoid In 1 month most are elliptical and starts forming cysts.
    • Sporophyte 10µm 10µm Complete maturation of sporophyte takes very long time, 6-8 months.
    • Sporophyte maturation 10µm 10µm S hape of sporophyte slightly elongate. Upon acquiring motility, zoospores swim away.
    • Zoospore release Have 4 flagella of same length. Does not have eye spots. 10 µm 10 µm
    • Zoospore development illustration
    • Settled zoospore and germination In about 10 Days, first transverse cell division happens. 10 µm 10 µm
    • Development of zoospore, 4 cell stage 15 days old culture. Thalli appears to have 3D structure 10µm 10µm
    • Zoospore development illustration
    • Development of zoospore, 8 cell stage 20 days old (after zoozpore release from sporophyte) culture 10µm 10µm
    • Zoospore development illustration
    • Further development of zoospore 3 dimensional erect filament. 30 days old culture 10 µm 10 µm
    • Formation of microscopic thalli Basal tissue (arrow head) develops into rhizoid. 60 days old culture. 100µm 10 µm
    • Parthenogenesis
      • Settled male and female gametes undergo parthenogenesis, exactly similar to the zygote maturation
      • 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.
    •  
    • Limitations of this study
      • Frequent contamination in the plates by unidentified long filamentous organism
      • Actual cytological development during zoospore release from sporophyte was unable to observe or photograph
    • Prospective research
    • Ongoing experiments
      • Germination frequency and growth rate analyses of sporophyte at various temperature and salinity conditions
      • Statistical analysis of female parthenogenetic bypass
    • Future plans
      • Ultrastructural observations during zygote maturation and zoospore germination
      • Microspectrofluorimetric analysis of nuclear genetic material for the establishment of haploidy/diploidy at various stages
    • Thank you!