Chapter 14 Generation of Body Plan Phenotypes in Early Embryogenesis

This chapter outlines a variety of methods to generate body axis perturbations in Xenopus embryos and give some general guidelines for scoring and analyzing the aberrant phenotypes. It is emphasized that despite the striking similarity in phenotypes which result from treatments, different developmental processes are being affected at the different windows of sensitivity. For example, UV light, known to damage RNA, also disrupts microtubule polymerization. These activities are important at different developmental times, relating to the distribution of maternal determinants (in the oocyte) or to the coordinated assembly of cortical microtubules (in the just-fertilized egg). The ventralizing and dorsalizing effects of the various late-acting agents (for example, TB, suramin, RA, GV sap) undoubtedly stem from their interference with cellular behaviors during the critical morphogenetic period of gastrulation. The various methods illustrated are ultraviolet light, deuterium oxide, lithium, and germinal vesicle sap.