Genomics of the human Y chromosome and molecular diagnosis

The human Y chromosome carries a few functional genes as against a plethora of non-coding DNA sequences and shows a high degree of geographical and ethnic variations for a range of loci manifested as genetic polymorphisms. Y-chromosome linked sequence tagged sites (STS) and short tandem repeat (STR) marker systems offer infallible tool for gender identification, paternity testing, genome individualization and assessing male fertility status. Population-specific Y haplotypes and Single Nucleotide Polymorphisms (SNPs) are envisaged to be useful in establishing a correlation between diseased phenotypes with genetic polymorphisms. We discuss genomics of the human Y-chromosome and its possible applications in biology, medical and forensic sciences

Biology of protooncogene c-kit receptor and spermatogenesis

Spermatogenesis involves action and interaction of several genes present both on the autosome and sex chromosomes. Protooncogene c-kit receptor is one such autosomal gene implicated with hematopoiesis, melanogenesis and spermatogenesis. A sizable body of literature is available on the regulatory role of this gene, its ligand "stem cell factor" and its functional conservation across the species. Sequences from the extracellular domains of c-kit cDNA show organizational uniqueness across the species conferring species specificity. Studies on fertile and infertile Brown Norway rats enabled identification of mutant mRNA transcript in the testis of infertile animals. These animals showed heavily regressed seminiferous tubules. No such mutant mRNA transcript was detected in the somatic tissues of infertile or normal animals. The mutant mRNA transcript was found in accordance with the regressed seminiferous tubules observed in the testicular histological section of the infertile rats. A perusal of literature and our own study suggest that alternate splicing of c-kit gene gives rise to multiple mRNA transcripts of which at least one is involved in control and regulation of fertility in conjunction with its ligand "stem cell factor" and perhaps other autosomal genes. In this article, we present a brief overview on the organization and expression of protooncogene c-kit receptor and its mutational status in Brown Norway rats (Rattus norvegicus). It is envisaged that information emerging from animal systems will facilitate the overall understanding of the phenomenon of fertility in the human as well