A single nucleotide polymorphism in CAPN1 associated with marbling score in Korean cattle.

BACKGROUND: Marbling score (MS) is the major quantitative trait that affects carcass quality in beef cattle. In this study, we examined the association between genetic polymorphisms of the micromolar calcium-activated neutral protease gene (micro-calpain, CAPN1) and carcass traits in Korean cattle (also known as Hanwoo). RESULTS: By direct DNA sequencing in 24 unrelated Korean cattle, we identified 39 sequence variants within exons and their flanking regions in CAPN1. Among them, 12 common polymorphic sites were selected for genotyping in the beef cattle (n = 421). Statistical analysis revealed that a polymorphism in the 3'UTR (c.2151*479C>T) showed significant association with MS (Pcor. = 0.02). CONCLUSION: Our findings suggest that polymorphisms in CAPN1 might be one of the important genetic factors involved in carcass quality in beef cattle, although it could be false positive association.

Growth hormone-releasing hormone (GHRH) polymorphisms associated with carcass traits of meat in Korean cattle.

BACKGROUND: Cold carcass weight (CW) and longissimus muscle area (EMA) are the major quantitative traits in beef cattle. In this study, we found several polymorphisms of growth hormone-releasing hormone (GHRH) gene and examined the association of polymorphisms with carcass traits (CW and EMA) in Korean native cattle (Hanwoo). RESULTS: By direct DNA sequencing in 24 unrelated Korean cattle, we identified 12 single nucleotide polymorphisms within the 9 kb full gene region, including the 1.5 kb promoter region. Among them, six polymorphic sites were selected for genotyping in our beef cattle (n = 428) and five marker haplotypes (frequency > 0.1) were identified. Statistical analysis revealed that -4241A>T showed significant associations with CW and EMA. CONCLUSION: Our findings suggest that polymorphisms in GHRH might be one of the important genetic factors that influence carcass yield in beef cattle. Sequence variation/haplotype information identified in this study would provide valuable information for the production of a commercial line of beef cattle.

Confirming single nucleotide polymorphisms from expressed sequence tag datasets derived from three cattle cDNA libraries.

Using the Phred/Phrap/Polyphred/Consed pipeline established in the National Livestock Research Institute of Korea, we predicted candidate coding single nucleotide polymorphisms (cSNPs) from 7,600 expressed sequence tags (ESTs) derived from three cDNA libraries (liver, M. longissimus dorsi, and intermuscular fat) of Hanwoo (Korean native cattle) steers. From the 7,600 ESTs, 829 contigs comprising more than two EST reads were assembled using the Phrap assembler. Based on the contig analysis, 201 candidate cSNPs were identified in 129 contigs, in which transitions (69%) outnumbered transversions (31%). To verify whether the predicted cSNPs are real, 17 SNPs involved in lipid and energy metabolism were selected from the ESTs. Twelve of these were confirmed to be real while five were identified as artifacts, possibly due to expressed sequence tag sequence error. Further analysis of the 12 verified cSNPs was performed using the program BLASTX. Five were identified as nonsynonymous cSNPs, five were synonymous cSNPs, and two SNPs were located in 3'-UTRs. Our data indicated that a relatively high SNP prediction rate (71%) from a large EST database could produce abundant cSNPs rapidly, which can be used as valuable genetic markers in cattle.

A large-insert porcine library with sevenfold genome coverage: a tool for positional cloning of candidate genes for major quantitative traits.

A porcine genomic bacterial artificial chromosome (BAC) library was constructed by cloning partial EcoRI-digested high-molecular-weight DNA from a Korean native boar into the EcoRI site of the pBACe3.6 vector. The library consists of about 165,000 clones with an average insert size of 125 kb, representing about seven genome equivalents of coverage. About 130,000 clones (corresponding to fivefold genome coverage) were arrayed in 14 superpools which were organized as four dimensional pools. The library was further characterized by PCR screening of 38 microsatellite probes. An average of 4.84 positive clones were selected per marker. This indicates that the library is unbiased and will be useful for initiating fine scale physical mapping of major QTL in pigs. The library is being used to isolate specific clones by screening with type I and type II marker clones located in the QTL region affecting intramuscular fat content on SSC6.

Identification of genetic polymorphisms in FABP3 and FABP4 and putative association with back fat thickness in Korean native cattle.

The aim of this study was to determine whether single nucleotide polymorphisms (SNP) in the beef cattle adipocyte fatty-acid binding protein 3 and 4 (FABP3 and FABP4) genes are associated with carcass weight (CW) and back fat thickness (BF) of beef cattle. By direct DNA sequencing in 24 unrelated Korean native cattle, we identified 20 SNPs in FABP3 and FABP4. Among them, 10 polymorphic sites were selected for genotyping in our beef cattle. We performed SNP, haplotype and linkage disequilibrium studies on 419 Korean native cattle with the 10 SNPs in the FABP genes. Statistical analysis revealed that 220AG (I74V) and 348+303TC polymorphisms in FABP4 showed putative associations with BF traits (P=0.02 and 0.01, respectively). Our findings suggest that the polymorphisms in FABP4 may play a role in determining one of the important genetic factors that influence BF in beef cattle.

Genomic sequence analysis of a potential QTL region for fat trait on pig chromosome 6.

On pig chromosome 6, the SW71 microsatellite is located in the region corresponding to several quantitative trait loci (QTL), such as those for intramuscular fat content and for body weight at 4 weeks of age. The genomic sequence of approximately 909 kb was obtained from seven BAC clones encompassing the SW71 region corresponding to human 18q11.21-q11.22. By searching the NCBI GenBank using BLASTX and BLASTN, this 909-kb segment was found to contain eight genes, RAB31, TXNDC2, VAPA, APCDD1, NAPG, FAM38B, C18orf30, and C18orf58, and one putative gene (DN119777). The average G + C content in the sequence of this contig was 45.75% and 33 CpG islands were detected. CpG islands were scattered throughout the region in which most of the putative genes were located. Dense CpG islands of approximately 840 bp were observed, including within the 5' UTR and exon 1 of the orthologs of the RAB31, VAPA, APCDD1, and NAPG genes. Comparative analysis of conserved segments of six species showed that K(a)/K(s) ratios of the TXNDC2 gene in collinear and rearranged segments were significantly different at 4.1 and 1.3, respectively. In conclusion, we demonstrated the genomic organization of pig chromosome 6, including the gene order surrounding SW71, which provides important information for comparative mapping. Moreover, the genes revealed in this study may be positional candidate genes associated with QTL on chromosome 6 that affect fat deposition in pigs.