Sinha A A, Mizuno N S
Cell Tissue Res. 1977 Sep 26;183(2):191-201. doi: 10.1007/BF00226619.
Ultrastructural analysis of M-band from nuclei of rat liver showed small amounts of chromatin, fragments of inner nuclear membrane, some amorphous nuclear material, and nucleopores. The outer nuclear membrane with its associated ribosomes was removed by Sarkosyl during the preparation of M-band sample. Morphological features of nucleopores and the inner nuclear membrane were confirmed by freez-fracture technique. The gross chemical composition of the M-band was similar to that of nuclear-membrane fractions prepared by other techniques. The M-band contained the greatest proportion of newly-labeled DNA and also supported DNA synthesis in vitro. Electron-microscopic autoradiography of the M-band showed localization of silver grains of thymidine-3H presumably over newly synthesized DNA. The DNA synthesis could not be attributed to spurious attachment of DNA polymerase to M-band during its isolation. It was partially removed from the M-band by treatment with 0.5 M KC1, phospholipase A or C; and completely, by the action of pancreatic DNase. DNA synthesis was greater in M-band fractions isolated from nuclei of 24-hour regenerating liver.
对大鼠肝细胞核的M带进行超微结构分析，发现其中有少量染色质、内核膜碎片、一些无定形核物质和核孔。在制备M带样品过程中，用十二烷基肌氨酸钠去除了带有相关核糖体的外核膜。核孔和内核膜的形态特征通过冷冻断裂技术得以证实。M带的总体化学成分与用其他技术制备的核膜组分相似。M带含有比例最大的新标记DNA，并且在体外也支持DNA合成。对M带进行电子显微镜放射自显影显示，3H-胸腺嘧啶核苷的银颗粒大概定位在新合成的DNA上。DNA合成不能归因于在分离过程中DNA聚合酶与M带的虚假附着。用0.5M氯化钾、磷脂酶A或C处理可使其部分从M带中去除；而用胰脱氧核糖核酸酶作用则可将其完全去除。从24小时再生肝细胞核中分离得到的M带组分中的DNA合成量更大。
