Kobayashi Satoru, Sato Kimihiro, Hayashi Yoshiki
Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, Myodaiji, Okazaki, Japan.
Zoolog Sci. 2005 Sep;22(9):943-54. doi: 10.2108/zsj.22.943.
Germ cells, represented by male sperm and female eggs, are specialized cells that transmit genetic material from one generation to the next during sexual reproduction. The mechanism by which multicellular organisms achieve the proper separation of germ cells and somatic cells is one of the longest standing issues in developmental biology. In many animal groups, a specialized portion of the egg cytoplasm, or germ plasm, is inherited by the cell lineage that gives rise to the germ cells (germline). Germ plasm contains maternal factors that are sufficient for germline formation. In the fruit fly, Drosophila, germ plasm is referred to as polar plasm and is distinguished histologically by the presence of polar granules, which act as a repository for the maternal factors required for germline formation. Molecular screens have so far identified several of these factors that are enriched in the polar plasm. This article focuses on the molecular functions of two such factors in Drosophila, mitochondrial ribosomal RNAs and Nanos protein, which are required for the formation and differentiation of the germline progenitors, respectively.
生殖细胞以雄性精子和雌性卵子为代表，是在有性生殖过程中从上一代向下一代传递遗传物质的特化细胞。多细胞生物实现生殖细胞与体细胞正确分离的机制是发育生物学中存在时间最长的问题之一。在许多动物群体中，卵细胞质的一个特殊部分，即生殖质，由产生生殖细胞（生殖系）的细胞谱系继承。生殖质包含足以形成生殖系的母体因子。在果蝇中，生殖质被称为极质，在组织学上通过极颗粒的存在来区分，极颗粒充当生殖系形成所需母体因子的储存库。到目前为止，分子筛选已经鉴定出其中几种在极质中富集的因子。本文重点关注果蝇中两种此类因子的分子功能，即线粒体核糖体RNA和纳米蛋白，它们分别是生殖系祖细胞形成和分化所必需的。
