Localization of ras proto‐oncogene expression during development in Xenopus Laevis

Abstract

The expression of the ras protooncogene was investigated in Xenopus laevis, throughout development, by in situ hybridization using a 35S-labelled antisense RNA probe. During oogenesis, the ras RNA was strongly expressed in the cytoplasm of previtellogenic oocytes and further diluted between yolk platelets; no specific localization of transcripts was observed. The signal density was particularly weak over embryo sections until the tailbud stage. On the other hand, a high level of ras RNA expression was detected on sections through the young tadpoles. An intense labelling was observed in several areas, including the branchial apparatus, gut, somites, nervous system, and lens. It is noteworthy that the heterogeneity of labelling increases as tadpoles grow older. Together, these results are discussed in relation to cellular events appearing throughout the early development.

Activated Ras induces lens epithelial cell hyperplasia but not premature differentiation

“…2). Ras expression has also been detected in the lenses of other species (Zelenka et al, 1989;Andeol et al, 1992;Rao et al, 1997). Surprisingly N-Ras expression was not found in primary embryonic chick lens tissue (Zelenka et al, 1989).…”

Distribution of p21ras during primary palate formation of non‐cleft and cleft strains of mice

“…Ras genes have also been implicated in cell determination in Drosophila eye development (32,33). There-, ras gene expression may be a positive effector for the differentiation of some cells or tissues at precise moments during development (34). The deficient growth of the facial primordia in PJ Sn mice may be caused by the decrease of activity in the signal transduction pathway.…”