Black S D
Department of Molecular Biology, University of California, Berkeley 94720.
Dev Biol. 1989 Aug;134(2):376-81. doi: 10.1016/0012-1606(89)90109-7.
During gastrulation in Xenopus laevis, the dorsal lip of the blastopore normally appears before the ventral lip. Metabolic gradient models propose that the dorsal lip develops from the region of highest metabolic activity and somehow dominates other regions to prevent them from becoming dorsal. To test these ideas, I applied a temperature gradient of 12 degrees C across the embryo. Localized heating of the prospective ventral vegetal region from early in the first cleavage period until gastrulation causes the blastopore lip to form first by 2 hr at the prospective ventral meridian rather than at the prospective dorsal meridian. Despite this reversal of the timing of blastopore formation, gastrulation is completed, and the neural plate forms at its usual position on the prospective dorsal meridian. This demonstrates that the earliest gastrulating regions of the blastopore do not necessarily become dorsal, nor do they inhibit dorsal development by other regions. It is unlikely that axis polarity is based on regional differences in energy metabolism.
在非洲爪蟾原肠胚形成过程中，胚孔的背唇通常比腹唇先出现。代谢梯度模型提出，背唇是从代谢活性最高的区域发育而来的，并且以某种方式主导其他区域，阻止它们变成背部。为了验证这些观点，我在胚胎上施加了一个12摄氏度的温度梯度。从第一次卵裂期早期到原肠胚形成期，对预期的腹侧植物区进行局部加热，会导致胚孔唇在预期的腹侧子午线处比在预期的背侧子午线处提前2小时首先形成。尽管胚孔形成的时间发生了这种逆转，但原肠胚形成仍完成了，并且神经板在预期背侧子午线的正常位置形成。这表明，胚孔最早进行原肠胚形成的区域不一定会变成背部，它们也不会抑制其他区域的背部发育。轴极性不太可能基于能量代谢的区域差异。
