Differential Gene Expression of Enriched Germ Cells Responding to a Short Heat Stimulus

It is well recognized that the quality of boar sperm is severely influenced by higher temperature in summer, thereby reducing the productivity of semen. cDNA microarray is a high throughput technique frequently used in genome-wide screening for specific genes related a known phenotype or disease. A testis cDNA microarray was established for the investigation of the differentially expressed genes, responding to a short heat stimulus, in enriched germ cells isolated from immature pigs where the first wave of spermatogenesis was just initiated. Two cDNA libraries were constructed from the testis tissues of two mature Duroc boars with or without whole body heat shock treatment. About 27,000 single colonies were randomly picked for one-direction sequencing. After the trimming of vector derived sequences, 22,969 high quality ESTs were obtained, which assembled into 3,207 contigs and 9,541 singletons, representing 12,748 tentative unique transcripts. A porcine testis cDNA microarray was established with single spot of the amplified cDNA plus 20 spots of positive and negative controls. We conducted a cell model experiment to screen the differentially expressed genes responding to a short heat shock. Small population of genes was up- or down-regulated with at least 1.5-fold of differences, including transcriptional factors, kinases, phosphatases, binding proteins and some transcripts with unknown functions. Further examination on these genes might contribute to a clear picture on the heat-tolerance of spermatogenesis in boar and benefit the breeding of boars with elite semen quality in all reasons. Keywords: stress response An enriched germ cells population isolated from the testis of 3-month-old immature porcine were cultured in DMEM/F12 medium with 10% FBS for 1 day and then treated with or without a 1-hour heat shock (39C). Total RNA were extracted after 2-hour recovery at 34C and amplified to antisense RNA(aRNA). The cDNA microarray experiments were carried out with 3 biological repeats and dye swap technical repeats each pair.