XMR, a dual location protein in the XY pair and in its associated nucleolus in mouse spermatocytes

• Published in: Molecular reproduction and development Vol. 72; no. 1; pp. 105 - 112
• Main Authors: Escalier, Denise, Garchon, Henri-Jean
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.09.2005; Wiley-Liss
• Subjects: Animals; Biological and medical sciences; Cell Nucleolus - genetics; Cell Nucleolus - metabolism; Cell Nucleolus - ultrastructure; Chromatin Assembly and Disassembly - genetics; Chromatin Assembly and Disassembly - physiology; Fundamental and applied biological sciences. Psychology; Gene Silencing - physiology; Male; Mammalian male genital system; meiosis; Mice; Morphology. Physiology; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; spermatocyte; Spermatocytes - physiology; Spermatocytes - ultrastructure; spermatogenesis; testis; Vertebrates: reproduction; X Chromosome - genetics; X Chromosome - metabolism; X Chromosome - ultrastructure; XY body; Y Chromosome - genetics; Y Chromosome - metabolism; Y Chromosome - ultrastructure; Rodentia; Sex chromosome; Meiosis; Nucleolus; testis; In vitro; Vertebrata; Mammalia; Spermatocyte; Mouse; XY body; spermatogenesis; Localization
• ISSN: 1040-452X; 1098-2795
• DOI: 10.1002/mrd.20268

Xlr and Xmr are sex‐specific genes which are expressed during the meiotic prophase I in the mouse. In spermatocytes, XMR concentrates on the asynapsed regions of the XY chromosomes, suggesting that XMR plays a role in sex chromosome condensation and silencing. The present study shows that in the mouse, XMR also concentrates in the nucleolus which is closely associated with the XY chromosome pair. In this species, the formation of a large fibrillo‐granular nucleolus signals the activation of the ribosomal genes, but release of pre‐ribosomal particles is inhibited. Using laser confocal microscopy we characterized the distribution of XMR in the XY body relative to the XY chromatin and the nucleolus. Immunoelectron microscopy showed that XMR concentrates in the fibrillo‐granular component and the granular component (GC) of the nucleolus. In (T[X;16]16H) mouse spermatocytes, the nucleolus displays little or no activity and does not associate with the XY pair. XMR concentrated only on the XY chromosomes in (T[X;16]16H) mouse spermatocytes. These data suggest that XMR could play a role both in the XY pair and the nucleolus associated to the sex chromosomes. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.