Molecular cloning, tissue expression and SNP analysis in the goat nerve growth factor gene

Population validation of reproductive gene mutation loci and association with the litter size in Nubian goat

Litter size is an important component trait of doe reproduction. By improving it, production efficiency and economic benefits can be significantly provided. Genetic marker-assisted selection (MAS) based on proven molecular indicators could enhance the efficacy of goat selection, as well as litter size trait. Many molecular markers have been identified that they can be used to improve litter size in different goat breeds. However, the presence and value of these markers vary among goat breeds. In the present study, we used the reported loci on other breeds of goat as candidate loci to detect whether these loci appear in this Nubian goat population; then we proceed to genotype and detect surrounding loci (50 bp) by multiplex PCR and sequencing technology. As a result, 69 mutations (59 SNPs and 10 indels) were screened out from 23 candidate genes in Nubian goat population, 12 loci were significantly associated with the litter size of first-parity individuals; 5 loci were significantly associated with the litter size of second-parity individuals; 3 loci were significantly associated with the litter size of third-parity individuals. In addition, five loci were significantly associated with the average litter size. The additive effect value of KITLG: g.18047318 G>A in first parity, KITLG: g.18152042G>A in third parity, KISS-1: g.1341674 C>G in first parity, and GHR: g.32134187G>A in second parity exceed more than 0.40, and the preponderant alleles are G, C, A and G, respectively. Further, linkage disequilibrium analysis of 21 mutation loci shows that 3 haplotype blocks are formed, and the litter size of combination type AACC in KISS-1 gene and AAGG in KITLG gene are significantly lower than that of other combinations genotype in first parity (P<0.05). These findings can provide effective candidate DNA markers for selecting superior individuals in Nubian goat breeding.

Litter Size of Sheep (Ovis aries): Inbreeding Depression and Homozygous Regions

Ovine litter size (LS) is an important trait showing variability within breeds. It remains largely unknown whether inbreeding depression on LS exists based on genomic homozygous regions, and whether the homozygous regions resulted from inbreeding are significantly associated with LS in sheep. We here reanalyze a set of single nucleotide polymorphism (SNP) chip of six breeds to characterize the patterns of runs of homozygosity (ROH), to evaluate inbreeding levels and inbreeding depressions on LS, and to identify candidate homozygous regions responsible for LS. Consequently, unique ROH patterns were observed among six sheep populations. Inbreeding depression on LS was only found in Hu sheep, where a significant reduction of 0.016, 0.02, and 0.02 per 1% elevated inbreeding FROH4-8, FROH>8 and the total inbreeding measure was observed, respectively. Nine significantly homozygous regions were found for LS in Hu sheep, where some promising genes for LS possibly via regulation of the development of oocytes (NGF, AKT1, and SYCP1), fertilization (SPAG17, MORC1, TDRD9, ZFYVE21, ADGRB3, and CKB), embryo implantation (PPP1R13B, INF2, and VANGL1) and development (DPPA2, DPPA4, CDCA4, CSDE1, and ADSSL1), and reproductive health (NRG3, BAG5, CKB, and XRCC3) were identified. These results from the present study would provide insights into the genetic management and complementary understandings of LS in sheep.

Neurotrophins and glial cell line-derived neurotrophic factor in the ovary: physiological and pathophysiological implications

BACKGROUND

Neurotrophins [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4)] and glial cell line-derived neurotrophic factor (GDNF) are soluble polypeptide growth factors that are widely recognized for their roles in promoting cell growth, survival and differentiation in several classes of neurons. Outside the nervous system, neurotrophin (NT) and GDNF signaling events have substantial roles in various non-neural tissues, including the ovary.

OBJECTIVE AND RATIONALE

The molecular mechanisms that promote and regulate follicular development and oocyte maturation have been extensively investigated. However, most information has been obtained from animal models. Even though the fundamental process is highly similar across species, the paracrine regulation of ovarian function in humans remains poorly characterized. Therefore, this review aims to summarize the expression and functional roles of NTs and GDNF in human ovarian biology and disorders, and to describe and propose the development of novel strategies for diagnosing, treating and preventing related abnormalities.

SEARCH METHODS

Relevant literature in the English language from 1990 to 2018 describing the role of NTs and GDNF in mammalian ovarian biology and phenotypes was comprehensively selected using PubMed, MEDLINE and Google Scholar.

OUTCOMES

Studies have shown that the neurotrophins NGF, BDNF, NT-3 and NT-4 as well as GDNF and their functional receptors are expressed in the human ovary. Recently, gathered experimental data suggest putative roles for NT and GDNF signaling in the direct control of ovarian function, including follicle assembly, activation of the primordial follicles, follicular growth and development, oocyte maturation, steroidogenesis, ovulation and corpus luteum formation. Additionally, crosstalk occurs between these ovarian regulators and the endocrine signaling system. Dysregulation of the NT system may negatively affect ovarian function, leading to reproductive pathology (decreased ovarian reserve, polycystic ovary syndrome and endometriosis), female infertility and even epithelial ovarian cancers.

WIDER IMPLICATIONS

A comprehensive understanding of the expression, actions and underlying molecular mechanisms of the NT/GDNF system in the human ovary is essential for novel approaches to therapeutic and diagnostic interventions in ovarian diseases and to develop more safe, effective methods of inducing ovulation in ART in the treatment of female infertility.

Relative abundance of tissue mRNA and association of the single nucleotide polymorphism of the goat NGF gene with prolificacy

Nerve Growth Factor (NGF) promotes the development of pre-antral ovarian follicles through ovarian innervations and regulation of ovarian response to gonadotropins. The present study was conducted to study the tissue gene expression profile, to characterize the genetic variants, find associations of the NGF gene with prolificacy in the prolific Malabari and less prolific Attappady Black goats because NGF has an important role in reproduction by augmenting ovarian folliculogenesis. Relative abundance of NGF mRNA was greatest in reproductive tissues signifying its role in reproduction. The PCR-SSCP analysis of a 251bp fragment of Exon 3 of the NGF gene from the 277 goats revealed four diplotypes (EE, EF, FF and EG) with respective frequencies of 0.76, 0.22, 0.01 and 0.01. Sequencing of the representative samples revealed one synonymous and one novel non synonymous mutations (g.705G>A and g.715C>T). Statistical analysis indicated that the SNP g.705G>A was associated with litter size in Attappady Black goats (P<0.05) and a PCR-RFLP was designed using the restriction enzyme, BpiI, for rapid screening of the SNP. The results of the present study suggest that the NGF gene is a primary candidate gene affecting prolificacy in goats and may be used for Marker Assisted Selection (MAS) in goats, especially in lowly prolific Attappady Black goats.

Nerve Growth Factor gene ovarian expression, polymorphism identification, and association with litter size in goats

The Nerve Growth Factor (NGF) plays an important role in reproduction by augmenting folliculogenesis. In this study, the coding regions of caprine NGF gene were analyzed to detect single-nucleotide polymorphisms (SNPs), their association with litter size, and the relative ovarian expression of NGF gene in the two indigenous goat breeds of South India viz., the prolific Malabari and less-prolific Attappady Black. The sequence analysis of the third exon containing the entire open reading frame of NGF gene was observed to be of 808 bp with one nonsynonymous mutation at 217th position. Later, polymerase chain reaction (PCR) was performed to amplify a region of 188 bp covering the region carrying the detected mutation. The genomic DNAs from the goats under study (n = 277) were subjected to PCR and single strand conformation polymorphism (SSCP). On analysis, four diplotypes viz., AA, AB, AC, and AD were observed with respective frequencies of 0.50, 0.22, 0.27, and 0.01. Sequencing of the representative samples revealed an additional synonymous mutation, i.e., g.291C>A. Statistical analysis indicated that NGF diplotypes and the SNP g.217G>A were associated with litter size in goats (P < 0.05). Relative expression of NGF gene was significantly higher in the ovaries of goats with history of multiple than single births (P < 0.05). The results of the present study suggest the significant effect of the NGF gene on litter size in goats and identified SNPs would benefit the selection of prolific animals in future marker-assisted breeding programs. The two novel PCR-restriction fragment length polymorphisms designed, based on the detected SNPs, would help in the rapid screening of large number of animals in a breeding population for identifying individual animals with desired genetic characteristics.

Single-nucleotide polymorphism analysis of GH, GHR, and IGF-1 genes in minipigs

Tibetan (TB) and Bama (BM) miniature pigs are two popular pig breeds that are used as experimental animals in China due to their small body size. Here, we analyzed single-nucleotide polymorphisms (SNPs) in gene fragments that are closely related to growth traits [growth hormone (GH), growth hormone receptor (GHR), and insulin-like growth factor (IGF)-1)] in these pig breeds and a large white (LW) control pig breed. On the basis of the analysis of 100 BMs, 108 TBs, and 50 LWs, the polymorphic distribution levels of GH, GHR, and IGF-1 were significantly different among these three pig breeds. According to correlation analyses between SNPs and five growth traits--body weight (BW), body length (BL), withers height (WH), chest circumference (CC), and abdomen circumference (AC)--three SNP loci in BMs and four SNP loci in TBs significantly affected growth traits. Three SNP sites in BMs and four SNP sites in TBs significantly affected growth traits. SNPs located in the GH gene fragment significantly affected BL and CC at locus 12 and BL at locus 45 in BMs, and also BW, WH, CC, and AC at locus 45 and WH and CC at locus 93 in TBs. One SNP at locus 85 in the BM GHR gene fragment significantly affected all growth traits. All indices were significantly reduced with a mixture of alleles at locus 85. These results provide more information regarding the genetic background of these minipig species and indicate useful selection markers for pig breeding programs.