van Eeden F, St Johnston D
Wellcome/CRC Institute, Tennis Court Road, Cambridge, CB2 1QR, UK.
Curr Opin Genet Dev. 1999 Aug;9(4):396-404. doi: 10.1016/S0959-437X(99)80060-4.
Recent work on Drosophila oogenesis has begun to reveal how the first asymmetries in development arise and how these relate to the later events that localise the positional cues which define the embryonic axes. The Cadherin-dependent positioning of the oocyte creates an anterior-posterior polarity that is transmitted to the embryo through the localisation and localised translation of bicoid, oskar, and nanos mRNA. In contrast, dorsal-ventral polarity arises from the random migration of the nucleus to the anterior of the oocyte, where it determines where gurken mRNA is translated and localised. Gurken signalling then defines the embryonic dorsal-ventral axis by restricting pipe expression to the ventral follicle cells, where Pipe regulates the production of an unidentified cue that activates the Toll signalling pathway.
近期关于果蝇卵子发生的研究已开始揭示发育过程中最初的不对称性是如何产生的，以及这些不对称性如何与随后定位确定胚胎轴的位置线索的事件相关联。卵母细胞依赖钙黏蛋白的定位产生了前后极性，该极性通过bicoid、oskar和nanos mRNA的定位及局部翻译传递给胚胎。相比之下，背腹极性源于细胞核随机迁移到卵母细胞的前部，在那里它决定了gurken mRNA的翻译和定位位置。然后，gurken信号通过将pipe表达限制在腹侧卵泡细胞中来定义胚胎的背腹轴，在腹侧卵泡细胞中，Pipe调节一种未知信号的产生，该信号激活Toll信号通路。
