Abdallah B et al. (1996), Thyroid hormone regulation of germ cell-specifi...

XB-ART-18357

Int J Dev Biol 1996 Apr 01;402:507-14.

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Thyroid hormone regulation of germ cell-specific EF-1 alpha expression during metamorphosis of Xenopus laevis.

Abdallah B , Sachs L , Hourdry J , Wegnez M , Denis H , Demeneix B , Mazabraud A .

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In situ hybridization was used to follow the distribution of the mRNAs encoding the somatic form of elongation factor 1 alpha (EF-1 alpha S) and the germinal counterparts of this factor, thesaurin a and EF-1 alpha O, throughout metamorphosis in the gonads of Xenopus laevis tadpoles. EF-1 alpha S mRNA is detected before metamorphosis in both the somatic and germ cells of the gonads. In contrast, thesaurin a and EF-1 alpha O mRNAs are first detected in spermatogonia and oogonia at stages 60-62, corresponding to the climax of metamorphosis and to the peak of circulating thyroid hormone. To determine whether thyroid hormone, the instigator of metamorphosis, is involved in regulating the expression of the germinal gene EF-1 alpha O, Xenopus XTC cells were transfected with an EF-1 alpha O promoter sequence inserted in front of the luciferase reporter gene. Addition of T3 to the cell culture medium induced a dose-dependent increase in transcription from the EF-1 alpha O promoter. This effect was enhanced when the construct was cotransfected with an expression vector for a Xenopus thyroid hormone receptor. Our data show that germ cells switch from a somatic to a germ-cell specific mode of expression during metamorphosis. Furthermore, this switch appears to be induced by thyroid hormone.

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Species referenced: Xenopus laevis
Genes referenced: 42sp50 eef1a1 eef1a1o pc.1

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	Fig. 1. In situ hybridization of an EF-1aS probe to sections of tadpole gonads. Section of stage 55 gonad (premetamorphosis) hybridized with sense (A) or anti-sense probe (B). Gonia (arrows) are distinctly labeled. Section of a testis (C) and of an ovary (D) at stage 62 (metamorphosis) hybridized with anti-sense probe. (E and F) Sections of stage 66 ovary hybridized with anti-sense probe. The hybridization signal in germ cells (arrows) drops noticeably between stage 55 and stage 66. A-C and E. darkfield illumination. 0 and F. bright-field illumination. Scale bars. 50 um
	Fig. 2. In situ hybridization of an EF-1aO probe to sections of tadpole gonads. (A and B) Sections of stage 55 gonad hybridized with anti-sense probe. No significant labeling can be observed. The spots marked pc are due to pigment cells. Section of stage 62 testis (C) and of stage 66 ovary (D) hybridized with anti-sense probe. Spermatogonia and oogonia (arrows) are heavily labeled. A and C, dark-field Illumination. B and D, bright-field illumination Scale bars, 50 um.
	Fig. 3. In situ hybridization of a thesaurin A probe to sections of tadpole gonads. (A and B) Section of stage 55 gonad hybridized with anti-sense probe. No specific labeling can be observed. (C) Section of stage 62 testis hybridized with antisense probe. (D) Section of stage 66 ovary hybridized with anti-sense probe. Spermatogonia and oogonia (arrows) are heavily labeled. A and C, dark-field illumination. B and D, bright-field Illumination. Scale bars, 50 um.