The Retention Situation Of Y-Encoded MRNA In The Mature Spermatozoa

Since mRNA was found existing in mature spermatozoa in the middle of twentieth century, it had made a great progress in the research of the mRNA in sperm. Up to now, scientists have estimated that about 3500~5000 mRNAs were retained in human ejaculated spermatozoa, and indicated that they may play important roles in the process of chromosome recombination, gene imprinting and spermatogenesis. In order to explore the possible mechanism of mRNA retention in the mature spermatozoa and investigate the possible functions of sperm mRNA, the expression of a panel of Y-encoded genes in mature spermatozoa of mouse and human were studied in this paper.Reference to the data of mouse testis SAGE library, we chose 10 important mouse Y-encoded genes and designed their primers. After capacitation, sperm collected from epididymis were purified using swim-up method. Then we extracted total sperm RNA and also total RNA of other 3 tissues including testis, male brain and female brain. Following, RT-PCR (Reverse Transcription-Polymerase Chain Reaction) analysis was performed to detect mRNA of those genes in those tissues using their specific primers. In order to confirm our results, FISH (Fluorescence In Situ Hybridization) were then performed to analysis the detail location of Dby and Smcy in mature spermatozoa. Furthermore, a similar investigation of the 9 selected human Y-encoded genes expression patterns in the four human tissues, including human ejaculated spermatozoa, testis, male lymphocytes and ovary had also been done.The RT-PCR results showed that 10 selected mouse genes'mRNAs were all undetectable in female brain and some of them were detected in male brain. Moreover, all of them were detected in testis but only Dby mRNA was detected in mature spermatozoa. FISH analysis of Dby and Smcy revealed that positive signals were found in the post-acrosome region of nearly 50% of the mouse spermatozoa using Dby probes. However, no signals were detected when using Smcy probes. And the similar research on human showed that mRNA of those Y-encoded genes was undetectable in ovary and all of them were detected in male lymphocytes. Six genes'mRNAs were detected in testis and three genes'mRNAs were detected in the human mature spermatozoa.Our results indicated that Y-encoded genes'mRNAs were reserved selectively in mature spermatozoa. Among the selected genes, mRNA of Dby was retained in mouse mature spermatozoa and mRNAs of DBY,SRY and RPS4Y1 were retained in human mature spermatozoa. Mouse sperm FISH research also confirmed our result. So it was concluded that mouse Dby mRNA may have important functions during the process of fertilization, and the selectively retained Y-encoded mRNAs in human mature spermatozoa may also have extensive roles in early embryonic development.