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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #217875
Title: Genetic variation in the mannosidase 2B2 gene and its association with ovulation rate in pigs.

Author
item CAMPBELL, EMILIE - FORMER USMARC EMPLOYEE
item Nonneman, Danny - Dan
item Kuehn, Larry
item Rohrer, Gary

Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2008
Publication Date: 9/1/2008
Citation: Campbell, E.M., Nonneman, D.J., Kuehn, L.A., Rohrer, G.A. 2008. Genetic variation in the mannosidase 2B2 gene and its association with ovulation rate in pigs. Animal Genetics. 39:515-519.

Interpretive Summary: Ovulation rate is an important component of litter size in pigs. Despite being moderately heritable in pigs, selection for increased ovulation rate is difficult as it is difficult to measure and a sex-limited trait. A QTL for ovulation rate on pig chromosome 8 has been detected in a Meishan-cross resource population. Evaluation of this region yielded a positional candidate gene, mannosidase 2B2 (MAN2B2), for this QTL. The entire coding region of MAN2B2 was sequenced in Meishan and White Composite founder animals of the resource population to identify differences (single nucleotide polymorphisms) between the Meishan and White Composite forms of this gene. Eleven differences that affect the protein product of MAN2B2 were discovered and tested for statistical associations with ovulation rate in three generations of the resource population. The most significant association evaluated was with ovulation rate and the variant in the DNA located at position 1574 of the gene (1574:A/G; P = 0.00002) where the additive effect of the A allele was estimated to be -0.89 ova per cycle. This variant was determined to be more significantly associated with ovulation rate than the breed specific analysis conducted during the QTL discovery phase. The 1574:A/G marker was not associated with ovulation rate in a Duroc-Yorkshire-Landrace composite population. Therefore, either MAN2B2 has a unique epistatic interaction within the Meishan-cross population or the 1574:A/G is not the actual causative genetic variation affecting ovulation rate.

Technical Abstract: Ovulation rate is an important phenotypic trait that is a critical component of litter size in pigs. Despite being moderately heritable in pigs, selection for increased ovulation rate is difficult as it is difficult to measure and a sex-limited trait. A QTL for ovulation rate residing on the p-terminus end of pig chromosome 8 has been detected in a Meishan-cross resource population. Comparative analysis of this region yielded a positional candidate gene, mannosidase 2B2 (MAN2B2), for this QTL. The entire coding region of MAN2B2 was resequenced in the Meishan and White Composite founder animals of the resource population to identify single nucleotide polymorphisms. Eleven polymorphisms that alter the protein product of MAN2B2 were discovered and tested for statistical associations with ovulation rate in three generations of the resource population. The polymorphism located at position 1574 of the message (1574:A/G) was the most significant polymorphism tested (P = 0.00002) where the additive effect of the A allele was estimated to be -0.89 ova. This polymorphism was determined to be more significantly associated with ovulation rate than the breed specific analysis conducted during the line cross QTL discovery. The 1574:A/G marker was not associated with ovulation rate in an occidental population. Therefore, either MAN2B2 has a unique epistatic interaction within the Meishan-cross population or the 1574:A/G is in linkage disequilibrium with the actual causative genetic variation in the Meishan-cross population.