Inactivation of mammalian X-chromosome during spermatogenesis: Temporal expression of genes in the laboratory mouse.
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Date
1994-12
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Abstract
At zygotene/pachytene stage of meiosis in mammalian testis, the X—Y
heterobivalent is sequesterd into a heterochromatinized body whose genetic inactivity is
shown by lack of uridine incorporation. For the genic level evaluation of the X-inactivation,
activities of three X-linked genes were assayed in testicular cell types in the laboratory
mouse. While hypoxanthine phosphoribosyl transferase is functional at least up to pachytene
stage of primary spermatocytes, glucose-6-phosphate dehydrogenase appears to be active
only in the Sertoli cells. No transcript of the muscle specific muscular dystrophin gene
was obtained from its regular 5' promoter. Thus, inactivation of X-linked genes in testis
occurs at different stages during spermatogenesis, independently of heterochrornatinizati
on of the XY-body. We propose that Xist transcript, the putative regulator of X-inactivation
in female soma, is also the regulator in testis. However, due to its extremely low level
in testis the transcript may regulate by "spreading" in a gradient and affect the genes in
a temporal order. Thus, besides other factors, physical proximity of the genes to Xist may
determine the stage of their inactivation.
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Keywords
X-inactivation, pseudoautosomal, Xist, HPRT, G6PD, mdx
Citation
Parimal Das, Raman Rajiva. Inactivation of mammalian X-chromosome during spermatogenesis: Temporal expression of genes in the laboratory mouse. Journal of Biosciences. 1994 Dec; 19(5): 513-528.