Hatching of an estuarine crab : characterization, activity, and putative role of a caseinolytic protease
Project/Area Number |
08833009
|
Research Category |
Grant-in-Aid for Scientific Research (C)
|
Allocation Type | Single-year Grants |
Section | 一般 |
Research Field |
海洋生物学
|
Research Institution | Okayama University |
Principal Investigator |
SAIGUSA Masayuki Okayama University, 理学部, 助教授 (80135962)
|
Project Period (FY) |
1996 – 1997
|
Project Status |
Completed (Fiscal Year 1997)
|
Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥1,800,000 (Direct Cost: ¥1,800,000)
|
Keywords | Marine crustanceans / Hatching / Caseinolytic protease / Activity and characterization / Ultrastructure / Embryonic envelope / 吸水 / 活性 / 生化学的性質 / 卵浮化 / 海産カニ類 / 活性物質の精製 / OHSS(胚脱落誘発物質) / カゼインを分解するプロラアーゼ / 酵素 |
Research Abstract |
The zoeas of an estuarine crab Sesarma haematocheir (akate-gani) hatch synchronously within 0.5 - 1 h from a female. Three aspects of hatching were studied : caseinolytic activity, morphological changes of the embryonic envelope structure, and environmental factors. Hatch water (i.e., the filtered medium in whcih zoeas have hatched) contains a caseinolytic protease, and the molecular weight of this protease was estimated on gel filtration. Transmission electron microscopy shows that the envelope (1.8 mum thick) is composed of three distinct layrs : an outer (E1), thick middle (E2), and thin inner (E3) layr. The outer two layrs, that are structurally the main components of the envelope, were not morphologically altered during hatching, but the inner layr (E3) was clearly altered between 11 h and 3 h before hatching, suggesting its digestion. The assay with isolates of the embryonic envelopes and morphological observations also suggested that the envelope is digested by the hatch water. The time of hatching was strongly affected by low water temperatures, and their effects were much stronger to the embryos detached from the female than female-attached embryos. Salinity was ineffective. Mechanisms of hatching based on the digestion of this (E3) layr has been discussed.
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Report
(3 results)
Research Products
(24 results)