REGULATION OF INTRACELLULAR CALCIUM IN THE MOUSE EGG - CALCIUM-RELEASE IN RESPONSE TO SPERM OR INOSITOL TRISPHOSPHATE IS ENHANCED AFTER MEIOTIC MATURATION
REGULATION OF INTRACELLULAR CALCIUM IN THE MOUSE EGG - CALCIUM-RELEASE IN RESPONSE TO SPERM OR INOSITOL TRISPHOSPHATE IS ENHANCED AFTER MEIOTIC MATURATION
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DOI：
10.1095/biolreprod51.6.1088
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发表时间：
1994-12-01
影响因子：
3.6
通讯作者：
KLINE, D
中科院分区：
文献类型：
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作者：
MEHLMANN, LM;KLINE, D
受精的不成熟，前期I-逮捕小鼠卵母细胞产生多个Ca 2+瞬变类似的成熟，中期II鸡蛋，但是，第一个Ca 2+瞬变幅度低得多，持续时间短。相反，前期I-逮捕的卵母细胞，成熟的卵母细胞受精后，生发囊泡破裂有第一个Ca 2+瞬变类似的成熟受精卵。未成熟的，prophase逮捕的卵母细胞释放较少的Ca 2+响应于注射肌醇1，4，5-三磷酸（IP 3）比鸡蛋。在高浓度下，巯基试剂，硫柳汞（200 μ M），导致钙振荡在鸡蛋和卵母细胞产生类似的振荡。较低浓度的硫柳汞（25 μ M）不会引起Ca 2+振荡，但确实使卵和卵母细胞中IP 3诱导的Ca 2+释放敏感，因为IP 3诱导的Ca 2+释放在25 μ M硫柳汞存在下增强。在注射2.2 μ M IP 3之前，将卵母细胞在25 μ M硫柳汞中孵育，导致卵母细胞释放与注射2.2 μ M IP 3的卵中释放的一样多的Ca 2+。这些结果表明，未成熟的小鼠卵母细胞具有可释放的Ca 2+的细胞内存储的大小类似于在鸡蛋中的Ca 2+商店，但是，这些商店是IP 3的敏感性较低。IP 3诱导的Ca 2+释放机制的发展可能是成熟的重要组成部分;在卵子受精时，Ca 2+必须升高到足以激活进一步发育的水平，并建立对多精受精的阻断。小鼠卵母细胞在卵母细胞成熟过程中对IP 3的敏感性增加。
Fertilization of the immature, prophase I-arrested mouse oocyte produces multiple Ca2+ transients similar to those of the mature, metaphase II egg; however, the first Ca2+ transient is much lower in amplitude and shorter in duration. In contrast to prophase I-arrested oocytes, maturing oocytes fertilized after germinal vesicle breakdown have first Ca2+ transients similar to those of mature fertilized eggs. Immature, prophase-arrested oocytes release less Ca2+ in response to injection of inositol 1,4,5-trisphosphate (IP3) than eggs. At high concentrations, the sulfhydryl reagent, thimerosal (200 mu M), causes Ca2+ oscillations in eggs and produces similar oscillations in oocytes. A lower concentration of thimerosal (25 mu M) does not cause Ca2+ oscillations, but does sensitize IP3-induced Ca2+ release in both eggs and oocytes, since IP3-induced Ca2+ release is enhanced in the presence of 25 mu M thimerosal. Incubation of oocytes in 25 mu M thimerosal before injection of 2.2 mu M IP3 causes oocytes to release as much Ca2+ as is released in eggs injected with 2.2 mu M IP3. These results indicate that immature mouse oocytes possess intracellular stores of releasable Ca2+ similar in size to Ca2+ stores in eggs; however, these stores are less sensitive to IP3. Development of the IP3-induced Ca2+ release mechanism may be an important component of maturation; at fertilization of the egg, Ca2+ must be elevated to levels sufficient to activate further development and establish a block to polyspermy. Mouse oocytes appear to develop an increased sensitivity to IP3 during the course of oocyte maturation.