Breed-specific transcriptome response of spleen from six to eight week old piglet after infection with Streptococcus suis type 2

Different pig breeds have shown differential susceptibility to the pathogen infection; however, molecular mechanisms of the infection susceptibility are not fully understood. Streptococcus suis type 2 (SS2) is an important zoonotic pathogen. To identify the genes responsible for infection susceptibility, pigs from two different breeds (Enshi black and Landrace) were inoculated with SS2 and their spleen transcriptome profiles were investigated in the present study. The differentially expressed genes (DEGs) were analyzed from infected versus control pigs in each breed, and then compared between both pig breeds. Enshi black pig showed more DEGs than Landrace (830 vs. 611) and most of these were due to down-regulated genes (543 vs. 387). However some DEGs were uniquely expressed in one breed, some were expressed in opposite direction in both breeds. A number of candidate genes and pathways are identified which might be involved in susceptibility to SS2, for example, MMP9 and Resistin were only significantly expressed in Landrace. NPG3 and PMAP23 were up-regulated in Landrace whereas down-regulated in Enshi black. LENG8 in control Landrace have inherently higher expression than control Enshi black. IGKV6 is down-regulated in Landrace but up-regulated in Enshi black. Overall, the transcriptome profiles are consistent with the clinical signs, i.e. the Enshi black is more susceptible to SS2 infection than Landrace. This is the first study to identify differential gene expression between indigenous and modern commercial pigs after in vivo SS2 infection using RNA-seq. The significant DEGs in splenic profiles between two pig breeds suggested considerable involvement of genetic background in susceptibility to the SS2 infection in pigs.

Molecular characterization and SNPs analysis of the porcine Deleted in AZoospermia Like (pDAZL) gene

The Deleted in AZoospermia Like (DAZL) gene is expressed in prenatal and postnatal germ cells. In this study, we cloned and characterized the porcine Deleted in AZoospermia Like (pDAZL) gene. We found the full-length coding sequence of the pDAZL encoded a protein of 295 amino acids with a RNA recognition motif (amino acids 41-111) and a DAZ repeat (amino acids 167-120). The deduced protein sequence of pDAZL is 92.5% and 91.5% similar to those of human and bovine, respectively. PCR-MspI-RFLP and PCR-TaqI-RFLP were established to detect an A/G mutation in intron 7 and a C/A mutation in intron 9, respectively. Associations of two SNPs with litter size traits were assessed in Large White (n=275) and DIV (n=128) pig populations, and the statistical analysis demonstrated that CC produced 0.716 more (P<0.05) piglets born alive than CD genotypes in Large White pigs at TaqI locus (C/A mutation in intron 9), and the dominance effect was 0.304 pig per litter (P<0.05). This result suggests that the pDAZL gene might be a good candidate gene of litter size trait and provides some marker information for marker-assisted selection (MAS).