The Study Of The Expression Of Gene QSA And The Preparation Of QSA Antigen

It has long been thought that spermatozoa are transcriptionally quiescent, thus the only biological function of mature spermatozoa was delivering the male haploid genome to the oocyte. Despite this, it was found that mature ejaculated spermatozoa contain a complex mRNAs population. In fact, about 3500-5500 mRNA species were detected in human spermatozoa by using complementary DNA (cDNA) microarray. There is evidence that the spermatozoa delivers a unique set of mRNAs to the oocyte at fertilization. Furthermore, the fact that some of these spermatozoal mRNAs are also found in zygotes indicates these transcripts may be functionally important for proper fertilization or embryogenesis. In addition, it has been proven that spermatozoa mRNAs are selectively retained during spermatogenesis. These mRNAs are capable to translate de novo by the mitochondrial ribosomes to replace degraded proteins or for the specific needs of the capacitating spermatozoa.In order to investigate whether the spermatozoa mRNAs are selectively retained in ejaculated spermatozoa and what the possible functions of these mRNAs are, we selected an unknown gene QSA which cloned from human sperm SAGE library as the research object. Then we detected the expression pattern of QSA at the gene level and speculated the possible biological function of QSA accordingly, as well as preparing QSA fusion protein as the antigen, RT-PCR and in situ hybridization (ISH) were performed to detect the expression of QSA mRNA in different tissues of human and mouse. Moreover, the prokaryotic expression plasmid expressing QSA fusion protein was constructed. QSA transcripts were found in mice testis, ejaculated spermatozoa and zygote, but undetectable in mice ovum, blastocyst and other tissues. ISH results showed significantly high level of QSA mRNA in human testis and a number of glandular tissues. Due to the expression pattern of QSA, we speculate that QSA mRNA is selectively retained in capacitated sperm, and it's related to the production or secretion of a hormone. This might imply that QSA mRNA is involved in spermatogenesis or early embryo development. The result provides new evidence indicating that human sperm deliver transcripts that have paternal effects.