TRANSLOCATION OF REPETITIVE RNA SEQUENCES WITH THE GERM PLASM IN XENOPUS-OOCYTES

Xlsirts are a family of interspersed repeat RNAs from Xenopus laevis t hat contain from 3 to 13 repeat units (each 79 to 81 nucleotides long) flanked by unique sequences. They are homologous to the mammalian Xis t gene that is involved in X chromosome inactivation. Xlsirt RNA appea rs first in the mitochondrial cloud (Balbiani body) in stage 2 oocytes and is then translocated as island-like structures to the vegetal cor tex at early stage 3 coincident with the localization of the germ plas m. Exogenous Xlsirt RNA injected into oocytes translocates to the loca tion of the endogenous RNA at that particular stage. The Xlsirt RNA re peat sequences are required for translocation and can cause the transl ocation of heterologous unique RNAs to the vegetal cortex.