Kobayashi S, Kitamura T, Sasaki H, Okada M
Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan.
Development. 1993 Mar;117(3):885-93. doi: 10.1242/dev.117.3.885.
In Drosophila, it has been postulated that the third intron of the P-element is spliced only in germ-line cells. To test whether this postulate is applicable to pole cells, the progenitor cells of germ line, we carried out a histochemical assay to detect the splicing activity in embryos. The splicing activity was detected in pole cells and primordial germ cells. The activity increased to reach a maximum at 5-6 hours AEL (after egg laying), then decreased to an undetectable level by 8-9 hours AEL. The splicing activity showed a small second peak at 12-15 hours AEL. It was rather unexpected that not all pole cells were capable of splicing the third intron. Almost all pole cells that had the splicing activity at 5-6 hours AEL penetrated the embryonic gonads and differentiated into primordial germ cells. Our findings suggest that pole cells are selected to penetrate the gonads while they are migrating from the proctodeal cavity to the gonads. Furthermore, these results suggest that the machinery to splice the P-element is active in some pole cells, and that this activity is used for processing transcripts of genes that play important roles in the differentiation of pole cells into primordial germ cells.
在果蝇中，有人推测P因子的第三个内含子仅在生殖系细胞中进行剪接。为了测试这一推测是否适用于极细胞（生殖系的祖细胞），我们进行了一项组织化学检测以检测胚胎中的剪接活性。在极细胞和原始生殖细胞中检测到了剪接活性。该活性在产卵后（AEL）5 - 6小时增加到最大值，然后在8 - 9小时AEL时降至检测不到的水平。剪接活性在12 - 15小时AEL时出现一个较小的第二个峰值。并非所有极细胞都能够剪接第三个内含子，这相当出人意料。几乎所有在5 - 6小时AEL具有剪接活性的极细胞都会穿透胚胎性腺并分化为原始生殖细胞。我们的研究结果表明，极细胞在从原肛腔迁移到性腺的过程中被选择穿透性腺。此外，这些结果表明，剪接P因子的机制在一些极细胞中是活跃的，并且这种活性用于处理在极细胞分化为原始生殖细胞过程中起重要作用的基因的转录本。
