The genes encoding the major 42S storage particle proteins are expressed in male and female germ cells of Xenopus laevis

As components of the 42S storage particles (thesaurisomes), thesaurin a and thesaurin b are involved in the long-term storage of tRNA and 5S RNA in previtellogenic oocytes of Xenopus laevis. Thesaurin a and thesaurin b are among the most abundant proteins in previtellogenic oocytes. We show here that the mRNAs encoding thesaurin a and thesaurin b are present not only in previtellogenic oocytes but also in pre-meiotic germ cells (oogonia). These mRNAs can also be detected in spermatogonia and early spermatocytes, and are translated into protein in testis, as they are in ovary. We conclude that male germ cells mimic female germ cells in several aspects of gene activity related to RNA accumulation and metabolism.