绵羊FecB突变对BMPR1B活性及BMP/SMAD通路的影响研究进展

BMPR1B是绵羊中被鉴定的第一个多羔主效基因,但该基因中FecB突变增加绵羊排卵数的分子机制尚未解析。近年来发现BMPR1B活性受小分子抑制蛋白FKBP1A调控,该蛋白充当了BMPR1B及BMP/SMAD通路活性控制开关的关键作用且FecB突变恰好位于FKBP1A与BMPR1B结合位点附近。本文首先总结了BMPR1B和FKBP1A的蛋白结构,阐明二者空间结合区域及FecB突变的位置,进而预测了FecB突变与二者结合强弱的关系,最终提出了FecB突变通过影响BMPR1B与FKBP1A结合强度改变BMP/SMAD通路活性的科学假设,为后续探明FecB突变影响绵羊排卵数的分子机制提供了新思路。

生物钟作用机制及其对动物年节律产生的影响

生物钟几乎存在于所有生命体,是生物适应外界环境的每日周期性变化而产生的内部活动。生物钟在体内受转录-翻译-负反馈环路调控,能调节组织、器官的活动,其正常维持对生物的健康、生长、繁殖等具有重要意义。与之相对,由于环境的四季变化,生物也形成了体内的年周期生理变化,如季节性发情、昆虫滞育等。生物的年节律在外部主要受光周期为主的环境因素影响,在体内则与基因表达、激素含量和细胞组织形态的变化有关。褪黑素是识别外部光周期变化的重要信号,而生物钟在垂体解析褪黑素信号并调控下游信号变化中扮演着重要角色,对环境年度变化的识别和机体年节律的产生具有重要指导作用。本文通过介绍昆虫和哺乳动物的昼夜节律和年节律产生的机制,并结合鸟类的年节律,综述了生物钟对年节律产生影响的作用机制研究进展,以期为今后研究年节律的影响机制提供更广泛的思路。

Expression,structure and function analysis of the sperm-oocyte fusion genes Juno and Izumo1 in sheep(Ovis aries)

Background:JUNO and IZUMO1 are the first receptor-ligand protein pairs discovered to be essential for spermoocyte fusion;their interaction is indispensable for fertilization.Methods:PCR was used to clone the full-length DNA sequence of the Juno gene in sheep.The single nucleotide polymorphism(SNP)loci of Juno were genotyped by Sequenom MassARRAY®.PCR combined with rapid amplification of cDNA Ends were used to clone the full-length cDNA sequence of Juno and Izumo1.Reverse transcriptase-PCR(RT-PCR)and real time-quantitative-PCR(RT-qPCR)were used to analyze the genes’expression in tissues of sheep,and single cell RNA-seq was used to analyze the genes’expression in oocytes,granulosa cells and follicular theca of polytocous and monotocous Small Tail Han ewes.Bioinformatics was used to analyze advanced structure and phylogeny of JUNO and IZUMO1 proteins.Results:The full-length DNA sequence of the Juno gene in sheep was cloned and nine SNPs were screened.We found a significant association between the g.848253 C>A locus of Juno and litter size of Small Tail Han sheep(P<0.05).The full-length cDNA sequence of Juno and Izumo1 genes from Small Tail Han sheep were obtained.We found a new segment of the Izumo1 CDS consisting of 35 bp,and we confirmed the Izumo1 gene has 9 exons,not 8.RT-qPCR showed that Juno and Izumo1 genes were highly expressed in ovarian and testicular tissues,respectively(P<0.01).Single cell RNA-seq showed Juno was specifically expressed in oocytes,but not in granulosa cells or follicular theca,while Izumo1 displayed little to no expression in all three cell types.There was no difference in expression of the Juno gene in oocyte and ovarian tissue in sheep with different litter sizes,indicating expression of Juno is not related to litter size traits.Bioinformatic analysis revealed the g.848253 C>A locus of Juno results in a nonconservative missense point mutation leading to a change from Phe to Leu at position 219 in the amino acid sequence.Conclusions:For the first time,this study systematically analyzed the expression,structure and function of Juno and Izumo1 genes and their encoded proteins in Small Tail Han sheep,providing the basis for future studies of the regulatory mechanisms of Juno and Izumo1 genes.

Assessment of Serum PRL,MLT,TSH,FSH and LH Concentrations in the Goat (Capra hircus) Exposing to Different Photoperiod Regimes

In many seasonally breeding species, photoperiod is an important factor involved in reproduction. Capra hircus breeds are normally considered short-day breeders. An experiment was carried out to evaluate whether or not photoperiodic regimens influence circulating hormone levels （prolactin, melatonin, thyrotropin stimulating hormine, luteinizing hormone,follicle stimulating hormone） of Henan huai local goat exposing to different photoperiodic regimens. The results showed that plasma levels of prolactin, melatonin, thyrotropin stimulating hormine, luteinizing hormone and follicle stimulating hormone were higher in the 8 L∶ 16 D photoperiodic regimen than that in the 16 L∶ 8 D photoperiodic regimen. Levels of those hormones decreased on day 7 and day 28 when the 16 L∶ 8 D photoperiodic regimen was used continuously. It was concluded that serum concentrations of the hormones increased in summer when short day （8 L∶ 16 D） was used and decreased when the goats were transferred from short day for 42 d to long day exposure for 28 d. We suggest that in summer, levels of hormones changing may be due to short day animals. Changing of related hormones is still determined by the mechanism of internal regulation of short day animal s exposure to light changes. Shortening light may also help increase the reproductive activity of goat and thus increase productivity.

Behavioral Observations on Introduced Hu Sheep in Henan Province,China

Hu Sheep is a local sheep breed in the plain of Taihu, China. Due to the natural conditions in Taihu and human domestication, Hu Sheep is gradually featured with high adaptability, fast growth rate, early maturity and high productivity, which make them to be a unique and rare breed of sheep. In the present study, an experiment was conducted by means of instantaneous scan sampling, focal animal sampling and all-occurrence sampling to learn about Hu Sheep's behavior and activity pattern under certain feeding management and ecological condition. The result showed that the activity time budgets for several behaviors were different between rams and ewes, with respect to feeding (rams 30.60% vs. ewes 33.23%), ruminating (33.43% vs.35.30%); sleeping (19.92% vs. 13.69%), standing (4.13% vs. 5.26%), moving (8.10% vs. 7.46%), and other behaviors (3.86% vs.5.06%). A circadian activity rhythm was shown in some behaviors; e.g., total feeding time was greater in the daytime than at night, whereas resting time showed the opposite tendency. Moving mostly occurred in the daytime, and ruminating mainly occurred at night. Additionally, feeding activity occurred 32.22 times per day in rams and 31.73 times per day in ewes, whereas ruminating activity after feeding occurred 19.83 times per day in rams and 24.34 times per day in ewes. For each food bolus,the average ruminating time was 51.22 s in rams and 49.52 s in ewes, with 68.22 bouts of rumination per day in rams and57.35 bouts of rumination in ewes. By conducting the experiment, we studied and grasped the local Hu Sheep's main behavior and regularity which are of great significance on improving the feeding management and reducing diseases.

Progress on major genes for high fecundity in ewes

The existence of major genes affecting fecundity in sheep flocks throughout the world has been demonstrated.Three major genes whose mutations can increase ovulation rate have been discovered,and all related to the transforming growth factorβ(TGF-β)superfamily.The mutant FecB of bone morphogenetic protein receptor 1B(BMPR1B)has an additive effect on ovulation rate.Six mutations(Fec^(XI),Fec^(XH),Fec^(XG),Fec^(XB),Fec^(XL),Fec^(XR))of bone morphogenetic protein 15(BMP15)related with fertility have been identified that share the same mechanism.All the mutants can increase ovulation rate in heterozygotes and cause complete sterility in homozygotes.Homozygous ewes with two new mutations(FecX^(Gr),FecX^(O))of BMP15 had increased ovulation rate without causing sterility.There are five mutations in growth differentiation factor 9(GDF9)associated with sheep prolificacy where FecG^(E) and FecG^(F) have additive an effect on ovulation rate and litter size.The newly identifiedβ-1,4-N-acetylgalactosaminyltransferase 2(B4GALNT2)gene of FecL is proposed as a new mechanism of ovulation rate regulation in sheep.Woodlands is an X-linked maternally imprinted gene which increases ovulation rate.In addition,several putative major genes need to be verified.This review is focused on the identification of the mutations and mechanisms whereby the major genes affecting ovulation rate.