Perreault S D, Barbee R R, Elstein K H, Zucker R M, Keefer C L
Reproductive Toxicology Branch, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711.
Biol Reprod. 1988 Aug;39(1):157-67. doi: 10.1095/biolreprod39.1.157.
To assess the structural stability of mammalian sperm nuclei and make interspecies comparisons, we microinjected sperm nuclei from six different species into hamster oocytes and monitored the occurrence of sperm nuclear decondensation and male pronucleus formation. The time course of sperm decondensation varied considerably by species: human and mouse sperm nuclei decondensed within 15 to 30 min of injection, and chinchilla and hamster sperm nuclei did so within 45 to 60 min, but bull and rat sperm nuclei remained intact over this same period of time. Male pronuclei formed in oocytes injected with human, mouse, chinchilla, and hamster sperm nuclei, but rarely in oocytes injected with bull or rat sperm nuclei. However, when bull sperm nuclei were pretreated with dithiothreitol (DTT) in vitro to reduce protamine disulfide bonds prior to microinjection, they subsequently decondensed and formed pronuclei in the hamster ooplasm. Condensed rat spermatid nuclei, which lack disulfide bonds, behaved similarly. The same six species of sperm nuclei were induced to undergo decondensation in vitro by treatment with DTT and detergent, and the resulting changes in nuclear size were monitored by phase-contrast microscopy and flow cytometry. As occurred in the oocyte, human sperm nuclei decondensed the fastest in vitro, followed shortly by chinchilla, mouse, and hamster and, after a lag, by rat and bull sperm nuclei. Thus species differences in sperm nuclear stability exist and appear to be related to the extent and/or efficiency of disulfide bonding in the sperm nuclei, a feature that may, in turn, be determined by the type(s) of sperm nuclear protamine(s) present.
为了评估哺乳动物精子核的结构稳定性并进行种间比较，我们将六种不同物种的精子核显微注射到仓鼠卵母细胞中，并监测精子核解聚和雄原核形成的发生情况。精子解聚的时间进程因物种而异：人类和小鼠的精子核在注射后15至30分钟内解聚，毛丝鼠和仓鼠的精子核在45至60分钟内解聚，但公牛和大鼠的精子核在同一时间段内保持完整。在注射了人类、小鼠、毛丝鼠和仓鼠精子核的卵母细胞中形成了雄原核，但在注射了公牛或大鼠精子核的卵母细胞中很少形成。然而，当公牛精子核在显微注射前用二硫苏糖醇（DTT）进行体外预处理以减少鱼精蛋白二硫键时，它们随后在仓鼠卵质中解聚并形成原核。缺乏二硫键的浓缩大鼠精子细胞核表现类似。用DTT和去污剂处理后，相同的六种精子核在体外被诱导发生解聚，并通过相差显微镜和流式细胞术监测由此产生的核大小变化。与在卵母细胞中发生的情况一样，人类精子核在体外解聚最快，其次是毛丝鼠、小鼠和仓鼠，经过一段时间的延迟后是大鼠和公牛精子核。因此，精子核稳定性存在物种差异，并且似乎与精子核中二硫键的程度和/或效率有关，这一特征反过来可能由存在的精子核鱼精蛋白类型决定。
