Identification, by differential display RT-PCR and cDNA selection, of genes expressed in human testis.

Spermatogenesis in human males is the process by which spermatogonia develop into spermatozoa, and occurs in the seminiferous tubules of the testis. If this process is disrupted at any stage, the male may become sub- or infertile. Both environmental and genetic factors have been implicated in these cases, and both causes are poorly understood. The aim of this project has been to identify novel genes involved in spermatogenesis by isolating sequences that are expressed either solely or highly in the testis. I have analysed cDNAs using the techniques of Differential Display RT-PCR and cDNA selection. Differential Display is a relatively new technique which has wide applications for identifying tissue or stage-specific transcripts. A subset of mRNAs present in a selected tissue are converted into short cDNA fragments. A comparison of the cDNAs produced from several different tissues (in this case testis, liver, lung, white blood cells, placenta, muscle and brain) allows products specific to one tissue to be identified. Whilst Differential Display will identify testis-specific genes expressed from anywhere in the genome, cDNA selection is basically a hybridization technique which, in this case, was set up to identify sequences in common between those expressed in the testis and those present on the Y chromosome. Using these experimental techniques I have identified previously characterized testis-specific sequences as well as 22 novel sequences and 11 sequences which matched to uncharacterized cDNAs present in the genome database. Several of the latter have been characterized further in terms of expression patterns and chromosomal location.