Goat DNMT3B: An indel mutation detection, association analysis with litter size and mRNA expression in gonads

DNA methyltransferase 3β (DNMT3B) is a gene encoding a de novo methylation enzyme that is required for DNA methylation during mammalian embryo development. Previous genome-wide association analysis suggested DNMT3B is a candidate gene for goat fertility, but there is no study on the effect of DNMT3B on litter size in goat. The aim of this study was to identify possible insertion/deletion (indel) mutations associated with litter size. Seven putative indels were designed to study their association with litter size, but just one 11-bp insertion variant of intron 22 (the last intron) was found in healthy female Shaanbei white cashmere goats (SBWC goats) (n = 1534). Statistical analysis showed that the 11-bp insertion was related to the first-born litter size (P < 0.01) and the goats with the deletion/deletion genotype had a higher average first-born litter size (P < 0.01). In addition, the expression profile of the DNMT3B mRNA in goat was detected, which revealed significant differences in DNMT3B mRNA expression in the gonads. Additionally, the results of western blotting revealed that the ovaries of mothers of multi-lamb (MML) had a higher level of DNMT3B protein than the ovaries of mothers of single-lamb (MSL). Furthermore, the mRNA of DNMT3B was widely expressed in male goats. Differences in mRNA expression levels were observed in the ovaries of MSL and MML. These findings indicated that the 11-bp indel in DNMT3B was significantly associated with first-born litter size, which can be used for marker-assisted selection (MAS) of goats for breeding.