Kaiser Johannes, Went Dirk F
Department of Entomology, Swiss Federal Institute of Technology Zurich, CH-8092, Zurich.
Institute of Animal Science, Swiss Federal Institute of Technology Zurich, CH-8092, Zurich, Switzerland.
Rouxs Arch Dev Biol. 1987 Sep;196(6):356-366. doi: 10.1007/BF00375772.
Embryos of the paedogenetically reproducing gall midge Heteropeza pygmaea develop floating in the haemocoel of a so-called mother larva. The egg membranes remain permeable and the embryos increase in size during embryonic development by taking up nutrients from the haemolymph. Such embryos can be cultured in vitro, i.e. in haemolymph drops obtained from mother larvae. We tested the effects of several drugs known to interact with cytoskeletal elements on different stages of embryonic development, including cleavage and gastrulation. The drugs were added to the in vitro cultures and the effects were studied with time-lapse cine-micrography. Colchicine and vinblastine blocked cleaving eggs in metaphase stage and arrested yolk globule oscillation. In spite of such a block blastoderms once formed continued development through germ band formation and extension and also increased in size. Cytochalasin B did not affect the stage of cleavage; however, it inhibited gastrulation and subsequent morphogenetic processes and also prevented size increase. We conclude that (1) the functioning of microtubules is needed for yolk globule oscillation during cleavage interphases but not for the gastrulation processes subsequent to blastoderm formation and (2) microfilaments do not play an important role in cleavage, at least not for the orderly succession of the cleavage divisions, but are essential for the morphogenetic movements associated with gastrulation. We suggest that during cleavage a limited stock of microtubules and their precursors is responsible for both transport of chromosomes during mitoses and translocation of organelles during interphase. Yolk oscillation seems to be a secondary effect and of minor or no importance for the normal course of embryonic development.
幼体生殖的瘿蚊（Heteropeza pygmaea）胚胎在所谓的母体幼虫的血腔中漂浮发育。卵膜保持通透，胚胎在胚胎发育过程中通过从血淋巴中摄取营养物质而增大体积。这样的胚胎可以在体外培养，即在从母体幼虫获得的血淋巴滴中培养。我们测试了几种已知与细胞骨架成分相互作用的药物对胚胎发育不同阶段的影响，包括卵裂和原肠胚形成。将药物添加到体外培养物中，并通过延时电影显微摄影术研究其效果。秋水仙碱和长春花碱使正在分裂的卵停滞在中期，并使卵黄球振荡停止。尽管有这样的阻滞，一旦形成的胚盘仍通过胚带形成和延伸继续发育，并且体积也会增大。细胞松弛素B不影响卵裂阶段；然而，它抑制原肠胚形成和随后的形态发生过程，也阻止体积增大。我们得出结论：（1）微管的功能在卵裂间期对于卵黄球振荡是必需的，但对于胚盘形成后的原肠胚形成过程不是必需的；（2）微丝在卵裂中不发挥重要作用，至少对于卵裂分裂的有序连续不是必需的，但对于与原肠胚形成相关的形态发生运动是必不可少的。我们认为在卵裂过程中，有限的微管及其前体储备负责有丝分裂期间染色体的运输和间期细胞器的转运。卵黄振荡似乎是一种次要效应，对胚胎发育的正常进程影响很小或没有影响。
