K. L. Glenn

An alternative method for genotyping of the ACE I/D polymorphism

The mistyping of the angiotensin I-converting enzyme insertion/deletion (ACE I/D) has been well documented, and new methods have been suggested here to improve the genotyping efficiency. Buccal cell samples were collected from 157 young Caucasians, and genotyped using previously known and newly developed PCR amplification genotyping techniques, as well as PCR-RFLP tests for three single nucleotide polymorphisms (rs4327, rs4341 and rs4343). Inconsistent genotyping results were found when using only the PCR amplification genotyping techniques across repeated attempts (8% to 45%), however, individual SNP genotyping was highly consistent (100%). Two SNPs (rs4341 and rs4343) were in complete LD and SNP rs4327 was in high LD with the ACE I/D. The ACE I/D was in HW equilibrium in the portion of the population with consistent genotyping results, whereas the three SNPs were not in HW equilibrium. The mistyping of ACE I/D by only PCR amplification can be improved using alternative methods.

Investigation of QTL regions on Chromosome 17 for genes associated with meat color in the pig

Previous studies have uncovered several significant quantitative trait loci (QTL) relevant to meat colour traits mapped at the end of SSC17 in the pig. Furthermore, results released from the porcine genome sequencing project have identified genes underlying the entire QTL regions and can further contribute to mining the region for likely causative genes. Ten protein coding genes or novel transcripts located within the QTL regions were screened for single nucleotide polymorphisms (SNPs). Linkage mapping and association studies were carried out in the ISU Berkshire x Yorkshire (B x Y) pig resource family. The total length of the new SSC17 linkage map was 126.6 cM and additional markers including endothelin 3 (EDN3) and phosphatase and actin regulator 3 (PHACTR3) genes were assigned at positions 119.4 cM and 122.9 cM, respectively. A new QTL peak was noted at approximately 120 cM, close to the EDN3 gene, and for some colour traits QTL exceeded the 5% chromosome-wise significance threshold. The association analyses in the B x Y family showed that the EDN3 BslI and PHACTR3 PstI polymorphisms were strongly associated with the subjective colour score and objective colour reflectance measures in the loin, as well as average drip loss percentage and pH value. The RNPC1 DpnII and CTCFL HpyCH4III polymorphisms were associated with some meat colour traits. No significant association between CBLN4, TFAP2C, and four novel transcripts and meat colour traits were detected. The association analyses conducted in one commercial pig line found that both EDN3 BslI and PHACTR3 PstI polymorphisms were associated with meat colour reflectance traits such as centre loin hue angle and Minolta Lightness score. The present findings suggested that the EDN3 and PHACTR3 genes might have potential effects on meat colour in pigs, and molecular mechanisms of their functions are worth exploring.

SREBP pathway genes as candidate markers in country ham production

Country hams are dry-cured products from the Southeastern region of the USA. This high value product requires quality fresh meat to avoid later processing problems. The marker SREBF1 is a transcription factor involved in the regulation of fatty acid synthesis and anti-oxidative enzyme transcription. The SREBF1 gene and its regulators, SCAP and MBTPS1, were investigated for associations with several meat quality traits in country hams. After single nucleotide polymorphism (SNP) identification, PCR-RFLP tests were designed for one polymorphism in each of the three investigated genes. Meat quality and physical traits were collected on 299 fresh hams. Significant associations were found with ham yield (MBTPS1, P<0.05 and SREBF1×MBTPS1, P<0.05) and ham circumference (MBTPS1, P<0.05 and SREBF1×MBTPS1, P<0.01), Hunter A colour score on fresh meat (SREBF1, P<0.05), Hunter B colour score on cured meat (MBTPS1, P<0.05 and SREBF1×MBTPS1, P<0.01), moisture (SCAP×MBTPS1, P<0.05) and salt percentage (SREBF1×SCAP, P<0.05). Our findings provide initial evidence that SNPs in SREBF1, SCAP and MBTPS1 are associated with some country ham quality traits. Breeders could use these gene tests to improve their animals, which would in turn improve country ham processing and other desired production goals.