Bioinformatics Analysis Of Whole Blood MRNA Of Bulls With High-or Low-Semen Quality Identified By Microarray Analysis

The objective of this study was to analyze whole blood samples of Simmental and Holstein bulls with different semen quality by gene expression profile chip,looked for key candidate genes related to semen quality.Based on similarities in growth status,twenty Simmental bulls and Holstein bulls were respectively selected and tested for their semen quality,including ejaculate volume,fresh sperm motility,concentration,abnormality rate and effective spermatoza.According to the lever of their semen quality,5 high-semen quality Simmental bulls were treated as XB group,similarly,5 low-semen quality Simmental bulls as XW group,5 high-semen quality Holstein bulls as HB group and 5 low-semen quality Holstein bulls as HW group.We collected the whole blood in jugular vein of Simmental and Holstein bulls,extracted the mRNAs and mixed them within group.Then,the gene chip was used to measure the mRNAs in Simmental and Holstein bulls.Gene expression levels with ≥1.5-fold change and P value ≤ 0.05 between the high-and low-quality semen groups were further analyzed.Furthermore,GO and KEGG were used to analyze the genes enrichment.Finally,RT-PCR was used to confirm the gene chip result.Simmental bulls group:410 differential expression genes were found.Among these,238 genes were up-regulated and 172 genes were down-regulated in the high semen quality group.The gene ontology(GO)search revealed 3 significant terms associated with immune response,membrane components and nucleotide bonding.And the Kyoto Encyclopedia of Genes and Genomes(KEGG)selected the chemokine,NER and GnRH signaling pathways.XPA,MAPK10,and MAP2K1,up-regulated genes in the NER and GnRH signaling pathway,were strongly associated with semen quality-related index which can be used as target genes for further study.Holstein bulls group:235 differential expression genes were found,among which,143 genes were up-regulated and 92 genes were down-regulated in the high-quality semen group.While,these differential expression genes were mainly related to the apoptosis biological processes according to the gene ontology(GO)search.Among these genes,TRADD,BCL2A1,RBM5,DFFB and NR4A1 were strongly associated with semen quality-related index.Also,the Kyoto Encyclopedia of Genes and Genomes(KEGG)selected the Histidine metabolism,RNA transport and TNF signaling pathway.In addition,Real-time PCR(RT-PCR)assays were performed to confirm the microarray results.In summary,the NER,GnRH,TNF signaling and apoptosis may significantly be related with spermatogenesis;XPA,MAPK10,MAP2K1,TRADD,BCL2A1,RBM5,DFFB and NR4A1 can be target genes in the follow-up study.