Abdallah B et al. (1991), The genes encoding the major 42S storage partic...

XB-ART-24405

Development 1991 Nov 01;1133:851-6.

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

Abdallah B , Hourdry J , Deschamps S , Denis H , Mazabraud A .

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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.

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Species referenced: Xenopus laevis
Genes referenced: 42sp43 42sp50 gtf3a mt-tr trna

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	Fig. 1. In situ hybridization of thesaurin a and thesaurin b probes to sections of ovary and testis. (A) Section of immature ovary hybridized with thesaurin a probe. (B) Section of immature ovary hybridized with thesaurin b probe. (C and D) Sections of mature testis hybridized with thesaurin a probe. (E and F) Sections of mature testis hybridized with thesaurin b probe. Both probes label oogonia (og) and previtellogenic (stage I) oocytes (panels A and B), and the periphery (arrows) of the seminiferous cysts (sc) which contains mostly spermatogonia (panels C-F). The thesaurin b probe also labels early vitellogenic (stage II) oocytes (panel B), and a sub-peripheral region of the seminiferous cysts which contains primary spermatocytes (panels E and F). Intercystic spaces (is) and oocyte nuclei (n) show a moderate to very low signal. A-C and E, dark-field illumination; D and F, bright-field illumination. Scale bars correspond to 50um.
	Fig. 2. Histogram showing the accumulation of thesaurin a (Tha) mRNA, thesaurin b (Thb) mRNA and TFIIIA mRNA in growing oocytes. Thesaurin a mRNA disappears more rapidly than thesaurin b mRNA in early vitellogenic oocytes (375 um in diameter). In contrast, TFIIIA mRNA continues to accumulate in early vitellogenic oocytes.
	Fig. 3. Nuclease protection assay of thesaurin a (A) and thesaurin b (B) cDNAs by RNA from liver (lanes L), ovary (lanes O) and testis (lanes T). Lanes Cl and C2 contain non-digested and non-protected probes, respectively. Lanes M contain DNA fragments of known sizes. Each non-digested DNA probe (lanes Cl) includes the 3' end of thesaurin cDNA linked to a small fragment of the cloning vector (Bluescript). This fragment is not protected against digestion, so that the nuclease-treated probes (lanes O and T) are shorter. The ovary tissue used in this experiment contained only previtellogenic oocytes. The testis tissue contained male germ cells at all stages of maturation.
	Fig. 4. Fractionation of testis and ovary extracts by sucrose density centrifugation, followed by immunodetection of thesaurins a and b (insert). Thirty-two testes and six ovaries from young adults (3 cm from mouth to anus) were homogenized in 5 volumes of 50mM Tris-HCl, 25mM KC1, 5 mM MgCb. The clarified extracts were fractionated by centrifugation through two 15-30% sucrose density gradients (3h at 45000revsmin"1 in a SW50.1 rotor). Aliquots (200 A<1) from testis fractions 10 (42S) and 15 (7S) were concentrated by ethanol precipitation, fractionated by polyacrylamide gel electrophoresis in the presence of SDS, blotted onto nitrocellulose and probed with a 42S particle antiserum (lanes 1 and 2 of insert). Aliquots (8uL) from ovary fractions 10 and 15 were analyzed in the same way (lanes 3 and 4 of insert).