| Budget Amount *help |
¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 1986: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1985: ¥4,900,000 (Direct Cost: ¥4,900,000)
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| Research Abstract |
Physiological importance of proteases involved in fertilization of ascidians was examined.
1. Sperm lysins. (1) The timing of action of three sperm proteases, acrosin, spermosin, and a chymotrypsin-like enzyme, in fertilization of the ascidian, Halocynthia roretzi, was analyzed by adding specific protease inhibitors at various times after insemination. The results indicate that both the latter two enzymes function at the early stage of sperm-penetration process through the egg investment, while acrosin does at the late stage. (2) Inhibitory effects of chymostatin and its two analogs on fertilization and on chymotrypsin-like enzyme activity of sperm in three species of ascidians were examined. The results indicate that the sperm chymotrypsin-like enzyme of different inhibitor-susceptibility is indispensable for the fertilization in each of the ascidians.
2. Egg trypsin-like enzyme. (1) A trypsin-like enzyme purified from eggs of the ascidian, H. roretzi, showed proterties similar to those
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of a trypsin-like enzyme found in the fertilization product. (2) The ranking in the potencies of leupeptin and its six analogs as inhibitors of the purified enzyme was well correlated with that in their potencies as inhibitors for the fertilization observed on the basis of chorion elevation. Thus, the trypsin-like enzyme possibly present in the fertilization product participates in the chorion elevation.
3. Prolyl endopeptidase. (1) A prolyl endopeptidase purified from eggs of the ascidian, H. roretzi, by almost the same procedure as that used for the sperm enzyme showed similar properties to those of the sperm one. (2) The ranks of four prolinal-containing peptides in their potencies were in good agreement not only between the inhibitory effect on the egg enzyme and that on the sperm enzyme, but also between the effect on the enzyme activities and that on the fertilization observed on the basis of cell division. Thus, the prolyl endopeptidase is responsible for some biochemical event required in a duration between chorion elevation and cell division. Less
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