Strome S, Garvin C, Paulsen J, Capowski E, Martin P, Beanan M
Department of Biology, Indiana University, Bloomington 47405.
Ciba Found Symp. 1994;182:31-45; discussion 45-57. doi: 10.1002/9780470514573.ch3.
Maternal-effect sterile (mes) genes encode maternal components that are required for establishment and development of the germline. Five such genes have been identified in the nematode Caenorhabditis elegans. Mutations in one of the genes result in defects in the asymmetric division and cytoplasmic partitioning that generate the primordial germ cell P4 at the 16-24-cell stage of embryogenesis. As a result of these defects, the P4 cell is transformed into a muscle progenitor and mutant embryos develop into sterile adults with extra body muscles. Mutations in the other four mes genes do not affect formation of the germline during embryogenesis, but result in drastically reduced proliferation of the germline during post-embryonic stages and in an absence of gametes in adults. The failure to form gametes may reflect a defect in germline specification or may be a consequence of reduced germline proliferation. We are currently testing these two possibilities. In addition to the mes gene products, wild-type function of the zygotic gene glp-4 is required for normal post-embryonic proliferation of the germline. Germ cells in glp-4 mutant worms are arrested in prophase of the mitotic cell cycle and are unable to enter meiosis and form gametes. Thus, following establishment of the germ lineage in the early embryo, both maternal and zygotic gene products work in concert to promote the extensive proliferation of the germline and to enable germ cells to generate functional gametes.
母体效应不育（mes）基因编码生殖系建立和发育所需的母体成分。在线虫秀丽隐杆线虫中已鉴定出五个这样的基因。其中一个基因的突变会导致在胚胎发育的16 - 24细胞阶段产生原始生殖细胞P4的不对称分裂和细胞质分配出现缺陷。由于这些缺陷，P4细胞转变为肌肉祖细胞，突变胚胎发育成具有额外身体肌肉的不育成虫。其他四个mes基因的突变在胚胎发育期间不影响生殖系的形成，但会导致胚胎后阶段生殖系的增殖大幅减少，且成虫中没有配子。无法形成配子可能反映出生殖系特化存在缺陷，也可能是生殖系增殖减少的结果。我们目前正在测试这两种可能性。除了mes基因产物外，合子基因glp - 4的野生型功能对于生殖系正常的胚胎后增殖也是必需的。glp - 4突变蠕虫中的生殖细胞在有丝分裂细胞周期的前期停滞，无法进入减数分裂并形成配子。因此，在早期胚胎中生殖系建立之后，母体和合子基因产物共同发挥作用，促进生殖系的广泛增殖，并使生殖细胞能够产生功能性配子。
