Submitted to: BioMed Central (BMC) Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2006
Publication Date: 9/18/2006
Citation: Nonneman, D.J., Wise, T.H., Ford, J.J., Kuehn, L.A., Rohrer, G.A. 2006. Characterization of the aldo-keto reductase 1C gene cluster on pig chromosome 10: possible associations with reproductive traits. Biomed Central (BMC) Veterinary Research. 2:28. 2006. Interpretive Summary: In swine, the rate of pubertal development and successful pregnancy in gilts affects the efficient management of breeding females. Selection for growth rate and leanness in modern commercial pigs has resulted in a delay in the onset of puberty. Age at puberty and weaning to estrus interval (WEI) are related and the primary reason for culling sows is failure to return to estrus after weaning. The q-arm of pig chromosome 10 contains quantitative trait loci (QTL) that affect age of puberty, ovulation rate and number of nipples and a cluster of aldo-keto reductase genes involved in steroid metabolism were mapped to this region. Nucleotide variation in these genes was associated with age of puberty and nipple number in extended generations of the original Meishan-White composite resource population. These polymorphisms are also segregating in commercial breeds and may be useful for selection of breeding females with greater reproductive efficiency in industry populations.
Technical Abstract: The rate of pubertal development and weaning to estrus interval are correlated and affect reproductive efficiency of swine. A QTL for age of puberty has been identified in a Meishan-White composite population on pig chromosome 10q (SSC10) near the telomere, which is homologous to human chromosome 10p15 and contains an aldo-keto reductase (AKR1C) gene cluster with at least six family members. Aldo-keto reductases are tissue-specific hydroxysteroid dehydrogenases involved in interconversion of preferred steroid substrates. Screening the porcine CHORI-242 BAC library with a full-length AKR1C4 cDNA identified 7 positive clones and sample sequencing of 5 BAC clones revealed 5 distinct AKR1C genes (AKR1CL2 and AKR1C1 through 4), which mapped to 126-128 cM on SSC10. Four of the five AKR1C genes were represented in EST libraries. Using the IMpRH7000rad and IMNpRH212000rad radiation hybrid panels, these 5 genes mapped between microsatellite markers SWR67 and SW2067. Comparison of sequence data with the porcine BAC fingerprint map show that the cluster of genes resides in a 300kb region. SNPs were identified in genomic DNA from parents of the resource population and 12 SNPs were genotyped in 191 gilts observed for age at first estrus and 233 females with ovulation rate from the F8 and F10 generations of one-quarter Meishan descendants of the USMARC resource population. Age at puberty, nipple number and ovulation rate data were analyzed for association with MTDFREML using an animal model. One SNP, a phenylalanine to isoleucine substitution in AKR1C2, was associated with age of puberty (p=0.07) and possibly ovulation rate (p=0.15). Two SNP in AKR1C4 were associated with nipple number and another possibly associated with age at puberty (p=0.09). These SNP are also segregating in commercial breeds and may be predictive for reproductive performance.