DELOCALIZATION OF VG1 MESSENGER-RNA FROM THE VEGETAL CORTEX IN XENOPUS-OOCYTES AFTER DESTRUCTION OF XLSIRT RNA

The Xlsirts are a family of transcribed repeat sequence genes that do not code for protein. Xlsirt RNAs become localized to the vegetal cort ex of Xenopus oocytes early in oogenesis, before the localization of t he messenger RNA Vg1, which encodes a transforming growth factor-beta- like molecule involved in mesoderm formation, and coincident with the localization of Xcat2 transcripts, which encode a nanos-like molecule. Destruction of the localized Xlsirts by injection of antisense oligod eoxynucleotides into stage 4 oocytes resulted in the release of Vg1 tr anscripts but not Xcat2 transcripts from the vegetal cortex. Xlsirt RN As, which may be a structural component of the vegetal cortex, are a c rucial part of a genetic pathway necessary for the proper localization of Vg1 that leads to subsequent normal pattern formation.