银鲫(Carassius auratus gibelio)成熟精子染色质的结构和碱性蛋白的研究

银鲫属行雌核发育的遗传系统,其精子入卵后不能形成雄性原核。如同其它种类的精子一样,在精子发生过程中其染色质形成高度浓缩的具有一定结构的DNA和碱性蛋白的复合物。为了研究分析银鲫成熟精子的碱性蛋白、染色质的结构及其与体细胞染色质的异同,我们用聚丙烯酰胺凝胶电泳分析了银鲫精子碱性蛋白的组分,并结合核酸酶解的结果,以电镜铺片和超薄切片法探讨了银鲫染色质的结构。聚丙烯酰胺凝胶电泳分析表明,银鲫精子的碱??性蛋白为含H_1、H_2a、H_2b、H_3及H_4五个主要组分的组蛋白,且与体细胞核组蛋白无明显差异。电镜铺片法观察精子染色质,可见染色质丝的近100A粗细的串珠状结构。小球菌核酸酶水解精子染色质,DNA的琼脂糖电泳呈“阶梯型”电泳条带,证实了银鲫成熟精子保存了核小体基本单元,在低渗处理后的精子超薄切片中,可以见到直径为300A左右的染色质纤维,这个结果提示了精子染色质与体细胞染色体有类似的二级结构。根据以上所得到的结果推测,行雌核发育的银鲫,其精子在入卵后不能原核化,与精子染色质的基本结构及碱性蛋白组分无明显直接关系。

THE STUDIES ON CHROMATIN STRUCTURE AND BASIC PROTEIN COMPOSITION OF MATURE SPERM IN CARASSIUS AURATUS GIBELIO

Carassius aurotus gibelio belongs to gynogene-sis genetic system,and its sperms are not ca-pable of forming male pronucleus in fertilizedegg.During spermatogenesis,like other species,the complex of DNA and basic proteins ishighly condensed.In order to study the chro-matin structure of mature spermatozoa andcompare it with somatic cell chromatin,weanalysed basic protein composition by meansof polyacrylamide gel electrophoresis and in-vestigated the fundamental chromatin structureof sperm nuclei by electron microscopy andmicrococcal nuclease digestion.The results ofPAGE revealed that all of five somatic his-tones,H_1,H_(2a),H_(2b),H_3,and H_4,are presentin the sperm chromatin,and no significantdifference has been detected,sperm chromatinconsits of nucleosome-sized beads (100 A)with typical nucleofilament organization.Onagarose electrophoresis gel,digestion productsof micrococcal nuclease formed "ladder"pattern,which conforms that the spermatozoa chroma-tin has a nucleosome structure.In addition,we observed under EM 300A chromatin fila-ments in sperm nuclei after hypotonic treat-ment.These results suggested that spermchromatin has the secondary structure similarto somatic cell chromatin.we can infer fromabove that the uncapability of male pronucleusformation of C.auratus gibelio sperm has nodirect relation with the basic protein compo-sition and fundamental chromatin structure ofsperm.