Jinxing Hou

Novel polymorphisms of the growth hormone gene and their effect on growth traits in Chinese goats

The polymorphisms of the growth hormone (GH) gene were analyzed in 686 individuals from four goat populations, Three haplotypes (A, B and C) and three observed genotypes (AA, AB and AC) were detected at the P2 locus, and three haplotypes (E, F and G) and three observed genotypes (EE, EF and EG) were also detected at the P4 locus. In addition, five single nucleotide polymorphisms (SNPs)-A112G, C142T (Gly>Ser), C214T (P2 locus), C266A (Pro>His) and C214T (P4 locus, Arg>Trp), were identified by GH gene sequencing and PCR-SSCP analysis. The SNPs loci were in Hardy-Weinberg disequilibrium in three goat populations (P<0.05). Association of polymorphisms with growth traits was done in BG, F1 and F1 populations, which were shown to be associated with growth traits in three goat populations. The SNPs in the goat GH gene had significant effects on growth traits (P<0.05). suggesting that the GH gene is a strong candidate gene that affects growth traits in goat.

Association analysis between variants in KISS1 gene and litter size in goats

BackgroundKisspeptins are the peptide products of KISS1 gene, which operate via the G - protein-coupled receptor GPR54. These peptides have emerged as essential upstream regulators of neurons secreting gonadotropin-releasing hormone (GnRH), the major hypothalamic node for the stimulatory control of the hypothalamic–pituitary– gonadal (HPG) axis. The present study detected the polymorphisms of caprine KISS1 gene in three goat breeds and investigated the associations between these genetic markers and litter size.ResultsThree goat breeds (n = 680) were used to detect single nucleotide polymorphisms (SNPs) in the coding regions with their intron–exon boundaries and the proximal flanking regions of KISS1 gene by DNA sequencing and PCR–RFLP. Eleven novel SNPs (g.384G>A, g.1147T>C, g.1417G>A, g.1428_1429delG, g.2124C>T, g.2270C>T, g.2489T>C, g.2510G>A, g.2540C>T, g.3864_3865delCA and g.3885_3886insACCCC) were identified. It was shown that Xinong Saanen and Guanzhong goat breeds were in Hardy-Weinberg disequilibrium at g.384G>A locus (P < 0.05). Both g.2510G>A and g.2540C>T loci were closely linked in Xinong Saanen (SN), Guanzhong (GZ) and Boer (BG) goat breeds (r2 > 0.33). The g.384G>A, g.2489T>C, g.2510G>A and g.2540C>T SNPs were associated with litter size (P<0.05). Individuals with AATTAATT combinative genotype of SN breed (SC) and TTAATT combinative genotype of BG breed (BC) had higher litter size than those with other combinative genotypes in average parity. The results extend the spectrum of genetic variation of the caprine KISS1 gene, which might contribute to goat genetic resources and breeding.ConclusionsThis study explored the genetic polymorphism of KISS1 gene, and indicated that four SNPs may play an important role in litter size. Their genetic mechanism of reproduction in goat breeds should be further investigated. The female goats with SC1 (AATTAATT) and BC7 (TTAATT) had higher litter size than those with other combinative genotypes in average parity and could be used for the development of new breeds of prolific goats. Further research on a large number of animals is required to confirm the link with increased prolificacy in goats.

Polymorphism of Exon 2 of FShβ Gene and Its Relationship with Reproduction Performance in Two Goat Breeds

Abstract The objectives of the present study were to detect the polymorphism in follicle stimulating hormone beta (FSHβ) gene and investigate the relationship between FSHβ gene and high prolificacy in goats. According to the sequence of ovine FSHβ gene, two pairs of primers were designed to detect single nucleotide polymorphism of exon 2 of FSHβ gene in two goat breeds, Xinong Saanen dairy goat and Boer goat, by PCR-SSCP. The least square mean and genetic variance of different genotypes at polymorphic locus were analyzed, and the selection reaction was forecasted by genetic correlation between marker locus and genetic variance of litter size traits. There was one polymorphic locus occurring in exon 2 (P2) with three genotypes (EE, EF and FF). In Xinong Saanen dairy goat, EE genotype had significantly higher (P

Combined effects of four SNPs within goat PRLR gene on milk production traits

Xinong Saanen (SN, n=323) and Guanzhong (GZ, n=197) goat breeds were used to detect single nucleotide polymorphisms (SNPs) in the coding regions with their intron-exon boundaries of prolactin receptor (PRLR) gene by DNA sequencing, primer-introduced restriction analysis-polymerase chain reaction (PIRA-PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP). Four novel SNPs (g.40452T>C, g.40471G>A, g.61677G>A and g.61865G>A) were identified. The g.61677G>A and g.61865G>A SNPs caused amino acid variations p.Ser485Asn and p.Val548Met, respectively. Both g.40452T>C and g.40471G>A loci were closely linked in SN and GZ goat breeds (r(2)>0.33). In addition, there was also a close linkage between g.61677G>A and g.61865G>A loci in both goat breeds. Statistical results indicated that the g.40452T>C, g.61677G>A and g.61865G>A SNPs were significantly associated with milk production traits in SN and GZ breeds. Further analysis revealed that combinative genotype C1 (TTAAGGGG) was better than the others for milk yield in SN and GZ goat breeds. These results are consistent with the regulatory function of PRLR in mammary gland development, milk secretion, and expression of milk protein genes, and extend the spectrum of genetic variation of the caprine PRLR gene, which might contribute to goat genetic resources and breeding.

Polymorphism identification in the goat KITLG gene and association analysis with litter size.

This study reported the analysis of KIT ligand (KITLG) gene polymorphisms in 681 goats of three breeds: Xinong Saanen (SN), Guanzhong (GZ), and Boer (BG). In addition, the study identified three allelic variants: g.769T>C and g.817G>T in SN and GZ breeds, and g.9760G>C in the three goat breeds. The g.769T>C and g.817G>T loci were closely linked (r(2)  > 0.33). All the single nucleotide polymorphism loci were in Hardy-Weinberg disequilibrium (P < 0.05). Significant associations were found for litter size with all three loci. Therefore, these results suggest that the KITLG gene is a strong candidate gene affecting litter size in goats.

Analysis of Differentially Expressed Genes in Ovaries of Polytocous versus Monotocous Dairy Goats Using Suppressive Subtractive Hybridization

In this study, suppressive subtractive hybridization (SSH) was performed to screen differentially expressed genes in ovarian tissues between polytocous and monotocous goats. From the SSH cDNA library, we obtained 29 differentially expressed sequence tags (ESTs) that have high similarity with known genes in the public database, which were involved in signal transduction, transcriptional regulation, cellular molecular dynamics, cytoskeleton, metabolism and oxidation-reduction. In addition, one novel EST that has no similarity with known genes in the public database was obtained. Eight ESTs, TIMP1, NUCB1, OAZ1, CXXC5, CAPNS2, ATP5A1, Z and RPL5, were further examined for the reproducibility of the SSH data by the real-time quantitative PCR. The results confirmed an increased expression of respective mRNA in ovarian tissues of polytocous goats compared with those of monotocous goats. The study has identified several genes (known or unknown) that may have effect on follicular development, ovulation and egg activation in goats.

Identification and profiling of microRNAs in the ovaries of polytocous and monotocous goats during estrus

MicroRNAs (miRNAs) play critical roles in almost all ovarian biological processes, including folliculogenesis, ovulation, luteal development, and regression. The study identified known and novel miRNAs in the ovaries of polytocous and monotocous goats by combining Solexa sequencing with bioinformatics. In total, 862 known and 53 novel miRNAs were identified in the ovaries of polytocous and monotocous goats. A total of 771 miRNAs were co-expressed in both libraries. One hundred twenty miRNAs in the ovaries of polytocous goats and 24 miRNAs in the ovaries of monotocous goats were specifically expressed. In addition, 445 miRNAs were differentially expressed in the ovaries of polytocous and monotocous goats, of which 348 were upregulated, and 97 were downregulated in the ovaries of polytocous goats compared with the ovaries of monotocous goats (P values < 0.05 and |log2 (fold change)|> 1). The expression levels of 12 randomly selected miRNAs were analyzed by stem-loop real-time quantitative polymerase chain reaction, and the results demonstrated that the expression patterns were consistent with Solexa sequencing results. KEGG analysis showed that GnRH, transforming growth factor-beta, vascular endothelial growth factor, and mammalian target of rapamycin signaling pathways, oocyte meiosis and ovarian steroidogenesis participated in follicular development and ovulation. On the basis of miRNA-mRNA network analysis and luciferase reporter assays, the ggo-miR-4488-p3_1ss10CG, bta-miR-2892-p5_1ss8CG and hsa-miR-4532_L+1R-3 were closely related with prolific traits. The results will help to further understand the role of miRNAs in kidding rate regulation.

Polymorphism and DNA methylation in the promoter modulate KISS1 gene expression and are associated with litter size in goats

Polymorphisms in the promoter region are likely to impact KISS1 gene transcription and reproductive traits. In this study, Guanzhong (GZ, n=350) and Boer (BE, n=196) goats were used to detect polymorphism in the promoter of the goat KISS1 gene by DNA sequencing. In the GZ goats, the g.1384G>A mutation was identified in the promoter of the goat KISS1 gene. Guanzhong goats were in Hardy-Weinberg disequilibrium at g.1384G>A locus (P<0.05). The 1384A allele was predicted to eliminate methylation, AHR-arnt heterodimers and AHR-related factors (AHRR) and myoblast determining factors (MYOD) transcription factor-binding sites. Statistical results indicated that the g.1384G>A SNP was associated with litter size in the GZ goats (P<0.05). Luciferase assay analysis suggested that the 1384A allele increased luciferase activity when compared to the 1384G allele. The RT-qPCR assay also demonstrated that the 1384A allele had greater amounts of KISS1 mRNA than the 1384G allele in homozygous individuals. Functional analysis suggested that this g.1384G>A SNP may be an important genetic regulator of KISS1 gene expression with effects on downstream processes that are modulated by KISS1 gene because of the changes of methylation and transcription factor-binding sites. Therefore, the current study provides evidence in goats for genetic markers that might be used in breeding programs.

Detection and comparison of microRNAs in the caprine mammary gland tissues of colostrum and common milk stages

BackgroundMicroRNAs (miRNAs) have a great influence on various physiological functions. A lot of high-throughput sequencing (HTS) research on miRNAs has been executed in the caprine mammary gland at different lactation periods (common milk lactation and dry period), but little is known about differentially expressed miRNAs in the caprine mammary gland of colostrum and peak lactation periods.ResultThis study identified 131 differentially expressed miRNAs (P < 0.05 and log2 colostrum normalized expression (NE)/peak lactation NE > 1 or log2 colostrum NE/peak lactation NE < −1), including 57 known miRNAs and 74 potential novel miRNAs in the colostrum and peak lactation libraries. In addition, compared with differentially expressed miRNAs in the peak lactation period, 45 miRNAs in the colostrum lactation period were remarkably upregulated, whereas 86 miRNAs were markedly downregulated (P < 0.05 and log2 colostrum NE/peak lactation NE > 1 or log2 colostrum NE/peak lactation NE < −1). The expressions of 10 randomly selected miRNAs was analyzed through stem-loop real-time quantitative PCR (RT-qPCR). Their expression patterns were the same with Solexa sequencing results. Pathway analysis suggested that oestrogen, endocrine, adipocytokine, oxytocin and MAPK signalling pathways act on the development of mammary gland and milk secretion importantly. In addition, the miRNA-target-network showed that the bta-miR-574 could influence the development of mammary gland and lactation by leptin receptor (LEPR), which was in the adipocytokine signalling pathway. Chr5_3880_mature regulated mammary gland development and lactation through Serine/threonine-protein phosphatase (PPP1CA), which was in the oxytocin signalling pathway.ConclusionsOur finding suggested that the profiles of miRNAs were related to the physiological functions of mammary gland in the colostrum and peak lactation periods. The biological features of these miRNAs may help to clarify the molecular mechanisms of lactation and the development of caprine mammary gland.

Association analysis between variants in KITLG gene and litter size in goats.

Xinong Saanen (SN) and Guanzhong (GZ) goat breeds were used to detect single nucleotide polymorphisms (SNPs) in the coding regions with their intron-exon boundaries and the proximal flanking regions of KITLG gene by DNA sequencing and genotyped by PCR-restriction fragment (PCR-RFLP). Four novel SNPs (g.12654G>A, g.12772G>A, g.12829T>C and g.23683C>T) were identified (GenBank accession No. KM609289). It was shown that Xinong Saanen and Guanzhong goat breeds were in Hardy-Weinberg disequilibrium at g.12654G>A, g.12772G>A and g.12829T>C loci (P<0.05). The g.12654G>A, g.12772G>A and g.12829T>C loci were closely linked in both goat breeds (r(2)>0.33). Results of an association analysis indicated that SNPs g.12654G>A, g.12772G>A and g.12829T>C had significant effects on litter size (P<0.05). The combined genotypes of four SNP loci also affected litter size with the C7(GG/GG/CC/CC) genotype in the SN goat breed and C1(AA/GG/CC/CC) and C7(GG/GG/CC/CC) genotypes in the GZ goat breed having the highest litter size. The biochemical and physiological functions, together with the results obtained in our investigation, suggest that C7(GG/GG/CC/CC) could be used in marker-assisted selection to select the individuals with higher litter size in both goat breeds. The results extend the spectrum of genetic variation of the caprine KITLG gene, which might contribute to goat genetic resources and breeding.