Analysis of spermatogenesis & meiosis using knockout mice

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The developmental program of spermatogenesis is a multi-step process which includes mitotic, meiotic, and post-meiotic phases characterized by dramatic shifts in the patterns of gene expression. We examined the function and expression pattern of spermatogenic cell specific genes (mHkl-s and Hsp 70-2) using knock-out mice.Unique type 1 hexokinase (HK1) mRNAs encode a spermatogenic cell-specific sequence region (SSR), but not the porin-binding domain (PBD) necessary for HK1 binding to porin on the outer mitochondrial membrane. Our study (Mori et al., 1998) determined the origin of the multiple Hkl-s transcripts in mouse spermatogenic cells and verified that they are translated in mouse spermatogenic cells. It also showed that a single mHkl gene encodes the mHkl transcripts of somatic cells and the mHkl-sa and mHkl-sb transcripts of spermatogenic cells, that alternative exons are used during mHkl gene expression in mouse spermatogenic cells, and that mHKl-S is translated in mouse spermato … More genic cells and is localized mainly with the fibrous sheath in the tail region.HSP70-2 is a unique member of the mouse 70-kDa heat shock protein family that is synthesized during meiosis in spermatogenic cells. Germ cells in male mice homozygous for a targeted mutation in the Hsp70-2 gene (Hsp7O-2^<-1->) arrest in development and undergo apoptosis at the end of the pachytene spermatocyte stage of meiotic prophase. However, cells with a putative acrosome were present occasionally in histological sections of the testes of juvenile and adult Hsp70-2^<-1-> mice. Our study (Mori et al., 1999) verified that acrosomes were present and investigated the relationship between acrosome formation and the process of meiosis. Our results indicate that not all pachytene spermatocytes in Hsp70-2^<-1-> mice arrest in meiosis, but may divide once or sometimes twice and begin acrosome formation and nuclear condensation. This demonstrates that some aspects of spermatid development can occur without the completion of meiosis in mice. Less