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Litter size is a favorable economic trait for the goat industry, but remains a complex trait controlled by multiple genes in multiple organs. Several genes have been identified that may affect embryo survival, follicular development, and the health of fetuses during pregnancy. Jining Grey goats demonstrate the largest litter size among goat breeds indigenous to China. In order to better understand the genetic basis of this trait, six suppression subtractive hybridization (SSH) cDNA libraries were constructed using pooled mRNAs from hypothalamuses, pituitaries, and ovaries of sexually mature and adult polytocous Jining Grey goats, as testers, versus the pooled corresponding mRNAs of monotocous Liaoning Cashmere goats, as drivers. A total of 1,458 true-positive clones--including 955 known genes and 481 known and 22 unknown expressed sequence tags--were obtained from the SSH libraries by sequencing and alignment. The known genes were categorized into cellular processes and signaling information storage and processing, and metabolism. Three genes (FTH1, GH, and SAA) were selected to validate the SSH results by quantitative real-time PCR; all three were up-regulated in the corresponding tissues in the tester group indicating that these are candidate genes associated with the large litter size of Jining Grey goats. Several other identified genes may affect embryo survival, follicular development, and health during pregnancy. This study provides insights into the mechanistic basis by which the caprine hypothalamic-pituitary-gonadal axis affects reproductive traits and provides a theoretical basis for goat production and breeding., (© 2015 Wiley Periodicals, Inc.)

Prolactin receptor (PRLR) gene was studied as a candidate gene for the prolificacy of Jining Grey goats. Five pairs of primers were designed to detect single nucleotide polymorphisms of exon 10 and part of 3'untranslated region (UTR) of PRLR gene in both high fecundity breed (Jining Grey goat) and low fecundity breeds (Liaoning Cashmere goat, Boer goat and Angora goat) by PCR-SSCP. The nucleotide sequence of exon 10 and part of 3'UTR of caprine PRLR gene was spliced in this study for the first time. The length of this sequence was 1,118 bp. This sequence shared 98.33%, 93.92%, 74.52% homology with the published mRNA of PRLR gene of sheep, cow and human separately, and shared 78.29% homology with the published partial genomic sequence of PRLR gene of the alpaca. Only the products amplified by primers P1, P2, P4 displayed polymorphisms. For primer P1, two genotypes (AA and AB) were detected in both Jining Grey goats and Liaoning Cashmere goats, two genotypes (AA and AC) were detected in Angora goats, and only genotype AA was detected in Boer goats. Sequencing revealed two mutations (186G-->A and 220T-->C) of PRLR gene in the genotype AB in comparison to the genotype AA. The former mutation resulted in an amino acid change of Asp-->Asn, and the latter mutation resulted in an amino acid change of Leu-->Pro. Only one mutation (140A-->G) was found in the genotype AC in comparison to the genotype AA, and this mutation did not cause any amino acid change. The difference of the least squares means (LSM) for litter size between AA and AB was non-significant (P>0.05) in Jining Grey goats. For primer P2, two genotypes (DD and DE) were detected in Jining Grey goats, Liaoning Cashmere goats and Boer goats, and only genotype DD was detected in Angora goats. Sequencing revealed two mutations (52G-->A and 122G-->A) of PRLR gene in the genotype DE in comparison to the genotype DD. The former mutation did not cause any amino acid change, and the latter mutation resulted in an amino acid change of Arg-->Gly. The difference of LSM for litter size between DD and DE was non-significant (P>0.05) in Jining Grey goats. For primer P4, two genotypes (FF and FG) were detected in Jining Grey goats, two genotypes (FF and GG) were detected in Liaoning Cashmere goats, only genotype FF was detected in Boer goats, and three genotypes (FF, FG and GG) were detected in Angora goats. Sequencing revealed one mutation (143A-->G) of PRLR gene in the genotype GG in comparison to the genotype FF, and this mutation resulted in an amino acid change of Met-->Val. The Jining Grey does with genotype FG had 0.76 (P< 0.05) kids more than those with genotype FF. These results preliminarily showed that the PRLR gene is either a major gene that influences the prolificacy of Jining Grey goats or a molecular marker in close linkage with such a gene.

Background: Litter size is an important factor that significantly affects the development of the sheep industry. Our previous TMT proteomics analysis found that three key proteins in the ovarian steroidogenesis pathway, STAR, HSD3B1, and CYP11A1, may affect the litter size trait of Small Tail Han sheep. Objective: The purpose of this study was to better understand the relationship between polymorphisms of these three genes and litter size. Material and Method: Sequenom MassARRAY detected genetic variance of the three genes in 768 sheep. Real‐time qPCR of the three genes was used to compare their expression in monotocous and polytocous sheep in relevant tissues. Finally, bioinformatics analysis predicted the protein sequences of the different SNP variants. Result: Association analysis showed that there was a significant difference in litter size among the genotypes at two loci of the CYP11A1 gene (p < 0.05), but no significant difference was observed in litter size among all genotypes at all loci of the STAR and HSD3B1 genes (p > 0.05). However, STAR expression was significantly different in polytocous and monotocous sheep in the pituitary (p < 0.01). Tissue‐specific expression in the ovary was observed for HSD3B1 (p < 0.05), but its expression was not different between polytocous and monotocous sheep. Bioinformatics analysis showed that the g.33217408C > T mutation of CYP11A1 resulted in major changes to the secondary and tertiary structures. In contrast, gene polymorphisms in STAR and HSD3B1 had minimal impacts on their protein structures. Discussion: This may explain why the CYP11A1 variant impacted litter size while the others did not. The single nucleotide polymorphism of the CYP11A1 gene would serve as a good molecular marker when breeding to increase litter size in sheep. Our study provides a basis for further revealing the function of the ovarian steroidogenesis pathway in sheep reproduction and sheep breeding. [ABSTRACT FROM AUTHOR]

To justify the function of miRNAs in reproductive regulation in swine, the expression of miR-145, miR-429 and their related genes were studied in reproductive tissues of sows. Wannan black pig and Yorkshire pigs with extremely high (n=6) and low (n=6) litter size were sampled, and real-time quantitative PCR (qPCR) was performed on tissue samples from ovaries, uterus, oviduct, hypothalamus, and pituitary. The results indicated that miR-145, miR-429, and zinc finger E-box binding homeobox 1 gene (ZEB1) were expressed significantly different in Wannan black pig and Yorkshire pigs. In pigs with different fecundity, miR-145 in the uterus was expressed significantly lower in pigs with high litter size, than in pigs with low litter size. The miR-429 expression in the oviduct and pituitary of pigs with high litter size was significantly higher compared with tissues sampled from pigs with low litter size. The ZEB1 expression in the pituitary was lower in pigs with high litter size in comparison to pigs with low litter size, while luteinizing hormone beta subunit (LHβ) showed the opposite pattern of expression. In conclusion, miR-145 and miR-429 were differently expressed in pigs with high and low litter size and might have a role in affecting litter size of sows. [ABSTRACT FROM AUTHOR]

The prolactin receptor (PRLR) gene was studied as a candidate gene for the high prolificacy of Jining Grey goats. Polymorphisms in intron 1 and intron 2 of PRLR gene were detected in high prolificacy (Jining Grey) and low prolificacy (Boer, Wendeng dairy, Liaoning Cashmere and Beijing) native goats using PCR-SSCP. For intron 1, five genotypes (AA, AH, AK, HH and HK) were identified in Jining Grey goats, and two (AA and AK) in the other four breeds. The Jining Grey does of genotype HH, HK, AH and AK delivered by 0.65, 0.62, 0.59 and 0.57 more kids (P<0.01) than those of genotype AA, respectively. For intron 2, three genotypes (CC, CD and DD) were detected in Boer goats, and two (CC and CD) in the other four breeds. The Jining Grey does of genotype CD delivered by 0.55 (P<0.01) more kids than those of genotype CC. [ABSTRACT FROM AUTHOR]