Iwao Yasuhiro, Miki Akiko, Kobayashi Michiko, Onitake Kazuo
Biological Institute Faculty of Science Yamaguchi University 753 Yamaguchi, Japan.
Biological Institute Faculty of Science Yamagata University 990 Yamagata, Japan.
Dev Growth Differ. 1994 Oct;36(5):469-479. doi: 10.1111/j.1440-169X.1994.00469.x.
An extract obtained from Cynops sperm induced the activation of both Cynops and Xenopus eggs with accompanying changes in the potential of the egg membrane that were quite similar to those caused by the Cynops sperm. The activation-inducing properties of the extract were abolished by treatment with proteinase K or by heating (60°C, 15 min) and were associated with a protease activity against peptidyl Arg-MCA substrates. The activation of Xenopus eggs by the extract was inhibited by those substrates, or by protease inhibitors, aprotinin or leupeptin. The protease activity was localized in the acrosomal region of Cynops sperm. The activation of Xenopus eggs by the extract was prevented when the exterior concentration of Ca ions, [Ca ] , was reduced to 1.5 μM, but it was enhanced when [Ca ] was increased to 340 μM. The activation of Xenopus eggs by the extract was not affected by positive clamping when [Ca ] was 340 μM. These results suggest that the sperm extract contains a protease that causes an increase in the influx of Ca ions that results in voltage-insensitive activation of the egg.
从蝾螈精子中提取的一种提取物可诱导蝾螈和非洲爪蟾卵母细胞激活，同时伴随着卵膜电位的变化，这些变化与蝾螈精子引起的变化非常相似。用蛋白酶K处理或加热（60℃，15分钟）可消除提取物的激活诱导特性，且其与针对肽基精氨酸-甲基香豆素酰胺（peptidyl Arg-MCA）底物的蛋白酶活性相关。提取物对非洲爪蟾卵母细胞的激活作用受到这些底物或蛋白酶抑制剂抑肽酶或亮抑肽酶的抑制。蛋白酶活性定位于蝾螈精子的顶体区域。当细胞外钙离子浓度[Ca²⁺]降至1.5 μM时，提取物对非洲爪蟾卵母细胞的激活作用受到抑制，但当[Ca²⁺]升至340 μM时，激活作用增强。当[Ca²⁺]为340 μM时，正向钳制对提取物激活非洲爪蟾卵母细胞的作用没有影响。这些结果表明，精子提取物含有一种蛋白酶，该蛋白酶可导致钙离子内流增加，从而引起卵母细胞的电压不敏感激活。
