RETROVIRUSES AS PROBES FOR DEVELOPMENT

将通过建立小鼠的早期发育研究 细胞谱系在前原肠胚，并通过 产生影响发育的插入突变， 转基因小鼠 在这项工作中，小鼠胚胎将被逆转录病毒感染， 不同发展阶段 因此，单个细胞 胚胎将被标记为遗传基因， 产生的将用于跟踪细胞谱系在早期 发展 为了便于追踪受感染的细胞， 它们的后代，将逆转录病毒载体导入小鼠胚胎 将编码一种容易识别和无害的基因产物， 作为细菌β-半乳糖苷酶基因。 逆转录病毒将是 引入植入前阶段的胚胎，以及卵 圆柱形阶段胚胎，以建立一个命运图的 在原肠胚形成之前或原肠胚形成时的小鼠胚胎。 特别是 将研究生殖系的起源。 马赛克动物将与野生型动物繁殖， 在胚芽中含有单个前病毒基因组的转基因菌株 线 将对这些菌株进行分析，以研究 亲本印记对转基因表达的影响，并获得 新的逆转录病毒引起的突变。 前病毒将用作 标签来克隆侧翼基因组序列并鉴定 变异基因 这种做法应有助于更好地 了解基因在早期发育中的作用。

Early development will be studied in the mouse by the establishment of cell lineages in the pre-gastrulation embryo, and by the generation of insertional mutations affecting development in transgenic mice. In this work, mouse embryos will be infected with retroviruses at different stages of development. As a result, individual cells of the embryo will be labelled genetically, and the mosaicism thus generated will be used to follow cell lineages during early development. To facilitate tracking of the infected cells and their progeny, retroviral vectors introduced into mouse embryos will encode an easily identifiable and innocuous gene product, such as the bacterial beta galactosidase gene. Retroviruses will be introduced into preimplantation stage embryos, as well as in egg cylinder stage embryos, in order to establish a fate map of the mouse embryo prior to or at gastrulation. In particular, the origin of the germ line will be investigated. Mosaic animals will be bred with wild-type animals to generate transgenic strains containing a single proviral genome in the germ line. These strains will be analyzed to investigate the effect of parental imprinting on expression of the transgene, and to derive new retroviral-induced mutations. The proviruses will be used as tags to clone flanking genomic sequences and to identify the mutated genes. This approach should contribute to a better understanding of genes active during early development.