C. Hudson et Hr. Woodland, XPAT, A GENE EXPRESSED SPECIFICALLY IN GERM PLASM AND PRIMORDIAL GERM-CELLS OF XENOPUS-LAEVIS, Mechanisms of development, 73(2), 1998, pp. 159-168
cDNAs specific to vegetal poles of Xenopus gastrula embryos were used
as a probe to screen a gastrula vegetal pole cDNA library. One of the
novel clones isolated had an RNA expression pattern consistent with it
being a component of germ plasm and it was thus named Xpat (Xenopus p
rimordial germ cell associated transcript). The open reading frame enc
odes a 35 kDa protein with no clear homologies. The RNA is localised t
o the vegetal pole throughout oogenesis and early cleavage. During gas
trulation cells containing this message move internally and at tailbud
stages they migrate in an antero-dorsal direction. Xpat mRNA is not d
etectable once the dorsal mesentery forms. We show that the 3'-UTR is
required and is sufficient for localisation of exogenous RNA to the ve
getal pole of oocytes. We propose that Xpat UTR-containing transcripts
can be localised by the Vgl or late pathway of mRNA localisation duri
ng stage III of oogenesis, but endogenous Xpat appears to be localised
earlier by a mitochondrial cloud mechanism similar to that proposed f
or Xcat-2. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.