| Autor: |
Tojo T; Department of Biology, School of Education, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-50, Japan., Kamata Y; Department of Biology, School of Education, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-50, Japan., Fujiwara A; Department of Biology, School of Education, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-50, Japan., Yasumasu I; Department of Biology, School of Education, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-50, Japan. |
| Abstrakt: |
In sea urchin eggs, 10 μg/mL melittin was found to induce fertilization envelope formation without any increase in [Ca 2+ ] i (the intracellular free Ca 2+ level). On the other hand, 10 μmol/L Br-A23187 and 100 μg/mL SDS induced fertilization envelope formation associated with [Ca 2+ ] i increase. If EGTA was injected into eggs to make an intracellular concentration of 2 mmol/L, [Ca 2+ ] i became quite low and was not altered by melittin, or by Br-A23187 and SDS. In eggs containing EGTA, fertilization envelope formation was induced by melittin even in Ca 2+ -free artificial sea water, but not by Br-A23187 or SDS. Thus [Ca 2+ ] i is essential for induction of a fertilization envelope in sea urchin eggs by Br-A23187 or SDS but not by melittin. Melittin probably activates some Ca 2+ -independent reaction downstream of Ca 2+ -dependent reactions in a sequential reaction system that finally results in fertilization envelope formation. |
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