Functional studies on the differentially expressed genes in swine ejaculated spermatozoa during winter and summer seasons

While the existence of specific messenger RNA (mRNA) remnants contained within freshly ejaculated spermatozoa were described in several species, most of these studies were conducted by the use of high-throughput techniques for screening the population of transcripts from the ejaculated spermatozoa, and these studies frequently confronted a major hindrance by the limitation of probes which mostly derived from nucleic acids of either human or mice testicular tissues. In the present study, attempts were made to investigate mRNA remnants from swine ejaculated spermatozoa harvested during both winter and summer seasons. It is anticipated that an available technique platform and a valuable model would be established not only for comparison the global variety of mRNA remnants expressed during both winter and summer seasons but also for meeting those purposes of biomedical research requested.n the initial studies, a non-redundant 5´-end complementary DNA library was generated from swine ejaculated spermatozoa. After sequence quality verification, 4,562 clones remained. These clones were then clustered and assembled into 514 unique sequences including 188 contigs (36.58%) and 326 singletons (63.42%), representing those clusters containing at least two clones and those clusters without having enough similarity with other clones. These unique gene sequences were annotated in gene ontology (GO); they included biological processes (38.7%), molecular functions (39.1%) and cellular components (40.3%). Based on the analysis, a broad spectrum of messenger RNAs existed in swine ejaculated spermatozoa and was closely correlated with nucleic acid binding, structural modifications, and transcriptional regulation. In the microarray analysis, 67 transcripts were differentially expressed with statistical differences between seasons of sperm samples collected, including forty-nine in winter (49/67) and eighteen in summer (18/67), respectively. There were only 33 of these transcripts could be annotated to gene ontology hierarchy with the database of Homo sapiens and their functions mostly were involved in variety of metabolic processes. Moreover, these studies also confirmed that significant differences of gene expression profiles were found in swine spermatozoa when comparisons were made between ejaculates collected during the winter and the summer season under the subtropical area such as Taiwan. he conclusion came to these present studies was that the spermatozoal RNAs provides a useful molecular tool in functional genomic studies of the male reproductive system, in evaluating the testis function and in developing new selection makers for swine industry.