基于转录组测序分析猪子宫内膜妊娠中的关键非编码RNA及其调控通路

【目的】探究调控具有不同产仔数的川乡黑猪和藏猪的猪子宫内膜妊娠过程的相关miRNA、lncRNA及靶基因,进一步揭示影响不同品种猪子宫内膜妊娠相关非编码RNA富集的信号通路。【方法】对平均产仔数为11.35和6.70的川乡黑猪和藏猪第2、5胎次的子宫内膜进行分离,提取RNA,质检合格后进行转录组测序,测序数据经过拼接、比对到miRNA和lncRNA并预测其靶基因,进行GO和KEGG富集分析筛选到调控川乡黑猪和藏猪不同产仔数的候选基因以及信号富集通路。【结果】不同胎次的川乡黑猪和藏猪之间存在多个miRNA、lncRNA及靶基因的差异表达,其中第2胎次具有1571个miRNA和2042个lncRNA差异表达,第5胎次具有1042个miRNA和2096个lncRNA差异表达。进一步根据靶基因的GO和KEGG富集分析发现川乡黑猪在促性腺激素释放激素(GnRH)分泌、ECM受体互作以及Wnt信号通路等的富集程度高于藏猪。同时发现川乡黑猪相比藏猪有醛固酮调节钠重吸收、谷胱甘肽代谢、果糖和甘露糖代谢等过程的富集。此外,已鉴定的关键候选调控基因包括FSHR(Follicle stimulating hormone receptor)、DBX1(Developing brain homeobox 1)、ARID2(AT-rich interaction domain 2)、TNC(Tenascin C)、NT5C2(Neuropilin 2)、LAMC3(Laminin subunit gamma 3)、MADD(MAP kinase activating death domain)等。【结论】高产仔数的川乡黑猪相比低产仔数的藏猪在子宫内膜妊娠过程中有更高的促性腺激素释放激素(GnRH)分泌、ECM受体互作以及Wnt信号通路富集(GO分析结果),同时也有代谢途径的参与(KEGG分析结果)。涉及到的关键调控基因主要有FSHR、DBX1等。本研究为探究非编码RNA在猪子宫内膜妊娠过程中的功能及其分子调控机制提供了新的思路。

饲料中不同蛋黄粉添加量对孔雀鱼繁殖力的影响

本文以孔雀鱼为试验材料,研究了饲料中不同蛋黄粉添加量对孔雀鱼繁殖周期和产仔量的影响。结果表明,饲料中蛋黄粉添加量越高,孔雀鱼繁殖周期越短,处理1(饲喂基础饲料+2%蛋黄粉)、处理2(饲喂基础饲料+4%蛋黄粉)、处理3(饲喂基础饲料+8%蛋黄粉)与CK(饲喂基础饲料)之间差异均显著(P<0.05),但处理1、2、3之间差异不显著(P>0.05);随着饲养时间延长和饲料中蛋黄粉添加量增多,孔雀鱼产仔量增多,处理1、2、3的第3次产仔量均显著高于CK(P<0.05),但处理1、2、3之间差异不显著(P>0.05);处理2的孔雀鱼总产仔量显著高于处理1(P<0.05),虽然处理3的孔雀鱼总产仔量最高,但其与处理2之间差异不显著(P>0.05)。可见,在饲料中添加蛋黄粉可缩短孔雀鱼繁殖周期,提高孔雀鱼产仔量,最适添加量为4%。

基于全基因组重测序解析皮山红羊群体遗传结构及产羔数候选基因研究

[目的]皮山红羊是分布于新疆和田地区的新发现多羔性地方绵羊品种。本研究基于全基因组重测序技术从基因组水平上了解皮山红羊的群体遗传结构及产羔性状受选择信号区域,并对候选基因进行验证。[方法]选择30只连续产2~3羔的经产皮山红羊母羊为高繁组(high fertility, HF),30只连续产单羔的经产皮山红羊母羊为低繁组(low fertility, LF),对这两个群体进行全基因组重测序。应用主成分分析(PCA)、系统进化树、群体遗传结构及全基因组扫描(Fst&θπ)等综合分析法确定候选区域,进一步筛选皮山红羊产羔性状候选基因。采用飞行质谱分型技术对候选基因进行分型验证。[结果]皮山红羊高、低繁殖组群体连锁不平衡(LD)分析衰减曲线相似,系统进化树显示两组群体分化程度不明显。PCA结果显示,两个群体明显聚成一簇,个别个体离群,其位置及相互关系符合进化树结构以及群体结构结果。设置同时达到Top 1%Z(Fst)值和θπ值的窗口为候选区域,共注释229个强选择信号,HF和LF组注释基因分别为86和143个,其中筛选到42个可能与繁殖性状相关的候选基因,如MARF1、CHGA、BMPR1B、IMMP2L、CDK14、ZDHHC3、CCDC71、DSCAML1、LIMK2、P2RY14等。经GO与KEGG通路分析发现,GO功能显著富集在钠离子跨膜转运蛋白活性的调控、凋亡过程的调控、钠离子通道调节剂活性、G蛋白偶联受体结合、G蛋白偶联嘌呤核苷酸受体活性等条目,KEGG显著富集通路主要与信号传递、信号通路、物质代谢等通路有关。分型结果表明,MARF1基因有11个SNPs位点在皮山红羊群体中真实存在,其中,g.14023542 T>A、g.14036507 A>G、g.14046123 C>T位点与群体平均产羔数显著关联,且前2个突变位点呈现强连锁关系(r2>0.3),g.14023542 T>A位点TT基因型具有最多的平均产羔数(1.901±0.675)。[结论]皮山红羊高繁组和低繁组两个群体遗传背景相似,具有一定程度的分化,但分化不明显。MARF1、CHGA、BMPR1B、IMMP2L、CDK14、ZDHHC3、CCDC71、DSCAML1、LIMK2、P2RY14等基因可能是影响皮山红羊产羔性状的候选基因。MARF1基因的3个SNPs位点可作为皮山红羊产羔性状潜在分子选育标记。

不同绵羊群体多羔主效基因FecB的检测

为分析FecB基因在不同绵羊群体中的分布情况以及对产羔数的影响,利用TaqMan探针分型技术检测了27 774只不同绵羊群体的FecB基因,结合12 304只个体的前3胎产羔数据,探索多羔主效基因FecB在提高绵羊繁殖力方面的重要作用。分型结果显示,湖羊群体含有最高的B等位基因频率,达0.90以上,且随着群体中湖羊血统含量的增加B等位基因频率也增加。湖羊、皮山红羊、杜湖杂交羊、杜湖(♂)×湖羊(♀)杂交羊以及利用湖羊培育的鲁中肉羊FecB基因的不同基因型产羔数间均存在极显著差异(P <0.01)。这不仅展示了FecB基因对于绵羊产羔数的重要影响,也显示出通过引入本土绵羊FecB基因改良肉用品种繁殖力的可行性和潜力。

不同产驹数阳原驴血液转录组分析

【目的】筛选影响阳原驴产驹数的关键基因与相关通路,提高阳原驴繁殖性能。【方法】以健康产双驹和产单驹阳原驴静脉全血为样本进行转录组高通量测序,与参考基因组非洲野驴(Equus asinus(ass))比对后筛选差异表达基因,并对差异表达基因进行GO功能及KEGG通路富集分析,筛选与阳原驴产驹数相关的基因。随机挑选5个差异表达基因进行实时荧光定量PCR验证。【结果】与产单驹组相比,产双驹组共筛选出1336个差异表达基因,其中723个上调,613个下调。GO功能富集分析显示,差异表达基因主要在受体活性、信号转导等条目中富集;KEGG通路富集分析显示,卵巢胆固醇生成和雌激素信号通路在富集通路前20位,并筛选出IGF1、IGF1R、INSR和ADCY3共4个与阳原驴产驹数相关的候选基因。实时荧光定量PCR结果与转录组测序结果一致,证实转录组测序结果可靠。【结论】不同产驹数阳原驴差异表达基因富集在卵巢类固醇生成和雌激素信号通路,IGF1、IGF1R、INSR和ADCY3基因参与卵巢激素分泌且均在产双驹组中表达上调。研究结果可为进一步阐明阳原驴不同产驹数的分子机制提供参考。

Polymorphism of FUT1 Gene and Its Relationship with Litter Size in Northeast Hebao Pigs

[ Objective] To analyze the FUT1 gene polymorphism of Hebao pigs and its relationship with litter size and provide reference for conservation, breeding, development and utilization of Hebao pigs. [Method] The DNA was extracted from Hebao pigs＇ ears, and the polymorphism of FUT1 gene was detected by PCR-RFLP. Then the relationship between genotype and litter size was analyzed. [Result] The FUT1 gene had three kinds of genotypes, GG, AG and AA, as indicated by digestion with Hin6 I. The genotype frequency of AA was 0.115 9, and the allele frequency of A was 0.275 4. The average litter size from the 1 = parity to the 5th parity was higher in the individuals with the genotype AA than in those with the genotype AG or GG. And this difference was significant in average litter size of the 3th parity and the 4th parity （ P 〈 0.05）. [ Conclusion ] The FUT-1 gene is polymorphic in Hebao pigs, and the allele frequency is similar to that of foreign Duroc pigs but greatly different from that of other breeds such as Landrace, Large white, and Landrace x Large white pigs. The genotype AA is a prevalent genotype for litter trait.

miR-23a/27a/24基因簇g.65307469G>A突变对大白猪产仔数和启动子活性的影响

[目的]本文旨在研究大白猪miR-23a/27a/24基因簇启动子突变位点多态性与产仔数性状的关系及潜在机制,为母猪繁殖性状的分子育种提供新的潜在遗传标记。[方法]利用混池测序技术筛选猪miR-23a/27a/24基因簇启动子突变位点,直接测序法对大白猪群体(n=345)miR-23a/27a/24基因簇突变位点进行基因分型,计算遗传多样性;用线性模型对突变位点多态性与产仔数性状进行关联性分析;构建不同等位基因类型启动子载体,转染猪卵巢颗粒细胞,通过检测荧光素酶活性分析突变对启动子活性的影响;用生物信息学方法预测不同等位基因类型启动子潜在结合的差异转录因子,用荧光素酶活性分析差异转录因子对不同等位基因类型启动子活性的影响。[结果]在猪miR-23a/27a/24基因簇启动子-648 nt(Chr.2,65307469 nt)处发现1个新的G/A突变,命名为g.65307469G>A。在大白猪群体中发现3种基因型(GG、GA和AA),其中GG为优势基因型(89.57%),G等位基因为优势等位基因(94.64%)。关联性分析发现,GA基因型母猪的总产仔数(TNB)比GG基因型母猪每胎高0.56头(P<0.05)。荧光素酶活性分析结果显示G等位基因类型启动子活性显著高于A等位基因类型(P<0.05)。在不同等位基因类型启动子间发现1个潜在结合的差异转录因子死亡相关蛋白1(THAP1),成功构建猪THAP1基因过表达载体,共转试验结果显示转录因子THAP1对不同等位基因类型启动子活性均无显著影响(P>0.05)。[结论]miR-23a、miR-27a和miR-24是大白猪产仔数性状的候选基因,g.65307469G>A突变抑制miR-23a/27a/24基因簇的启动子活性,但与转录因子THAP1无关。

塔克拉玛干沙漠北缘发现红沙蚺兼记繁殖数量新纪录

2017年5月—2021年10月,在塔克拉玛干沙漠北缘进行动物学野外实习和项目调研过程中,多次发现并采集到一种中小型蛇类。依据2017、2018年采集固定的2号标本及2020年采集到的母蛇,鉴定为红沙蚺(Eryx miliaris)。2020年采集到的母蛇产子16条。本次在塔克拉玛干沙漠北缘发现红沙蚺及其繁殖数量为其分布和繁殖数量新纪录。标本保存于塔里木大学生命科学与技术学院动物学标本室(R-2017-1,R-2018-1)。

Reproductive Biology of a Blue-tail Skinks(Plestiodon)Population from a Temperate Forest,East-central Puebla,México

We studied the cycles of reproduction and fat bodies of a blue-tailed skink population of an undescribed species of the Plestiodon brevirostris group.Sexual maturity is attained by females and males as they both reach about 59 mm of SVL.Vitellogenesis started in June-July,with ovulation occurring during late-October to mid-November,and parturition in mid-spring.Litter size varied from two to six,with a mean of 3.86±0.15 embryos in uterus,and showed a positive correlation with female body mass and SVL.During gestation,a significant increase in the average wet mass of embryos in uterus was evident.In comparison,there were no notable changes in the average dry mass.Juvenile growth data suggest that sexual maturity,both males and females,is reached at 16-17 months of age.Testicles and epididymides exhibited maximal weight during August-September.Testicular regression occurred in September.Mating apparently takes place from mid-summer to early fall.Lipids stored in female fat bodies are used for vitellogenesis and for nutrition during the winter months.In males,the stored lipids appear to be used in reproductive activities during the mating season.

高纤维食物对黑线仓鼠哺乳期能量收支的影响

繁殖期是小型哺乳动物最重要的生活史阶段之一,哺乳期是母体能量需求最高的时期。为满足后代的能量需求,母体通常显著增加能量摄入,达到最大持续能量摄入(maximal sustained energy intake,mSusEI)。动物消化道形态和消化机能具有可塑性,然而消化系统是否限制了哺乳期mSusEI,尚不确定。本文以高纤维食物饲喂哺乳期黑线仓鼠(Cricetulus barabensis),通过测定体重、摄食量、摄入能和消化率、代谢率、泌乳能量输出,以及消化系统重量和消化酶活性等,分析哺育不同胎仔数的母体能量摄入与繁殖输出,比较在不同能量需求的条件下,消化酶活性的变化。结果发现,黑线仓鼠哺乳期的能量收支与其哺育后代的数量有关,哺乳期mSusEI未受高纤维食物的显著影响。饲喂高纤维食物未影响摄入能,但显著降低了消化能和消化率,母乳能量输出也显著减少,不能满足后代幼体的能量需求,导致幼体发育变缓。高纤维食物使胃、小肠、大肠和盲肠重量显著增加,小肠淀粉酶、麦芽糖酶和氨基肽酶活性显著增强,但未受胎仔数的显著影响。结果表明,哺乳期mSusEI的瓶颈可能来自消化系统,支持中心限制假说。由于“中心限制”的存在,食物中纤维素含量升高可能会降低动物繁殖价值。

不同因素对公猪精液品质和母猪繁殖性能的影响

为了探究不同因素对公猪精液品质和母猪繁殖性能的影响,选取广西某种公猪站62头加系杜洛克公猪、74头长白公猪、221头大白公猪以及288头杜洛克母猪、247头长白母猪、1951头大白母猪为试验群体,通过混合线性模型与方差分析探究品种、采精月份、采精月龄和采精间隔等因素对采精量、精液密度、精子活力、有效精子数的影响,并分析情期有效精子输入量、精子活力、配种季节、品种、母猪胎次对母猪受胎率、窝产总仔数的影响。结果:大白公猪采精量和有效精子数均高于长白公猪与杜洛克公猪(P<0.05或P<0.01),杜洛克公猪精液密度显著高于长白公猪与大白公猪(P<0.05);春季精液密度最高,夏季有效精子数最少,秋冬季采精量和有效精子数最高(P<0.05或P<0.01);公猪月龄越小采精量越低且有效精子数越少(P<0.01);3个品种公猪采精量及精液密度和精子活力随采精间隔的延长均总体呈升高趋势,采精间隔为5 d时综合性能最佳。情期内有效精子输入量指标显著影响杜洛克母猪的受胎率和窝产总仔数(P<0.05),精子活力指标显著影响杜洛克、长白、大白母猪受胎率、窝产总仔数和窝产活仔数(P<0.05),但情期内有效精子输入量的增加不会增加长白母猪与大白母猪的窝产总仔数(P>0.05)。综上,品种、采精月份、采精月龄和采精间隔均会影响公猪精液质量,提高情期内有效精子输入量可提高杜洛克母猪受胎率和窝产总仔数,提升精子活力可提升杜洛克、大白和长白母猪受胎率与窝产总仔数。

不同厂商烯丙孕素对后备母猪同期发情及繁殖性能影响的研究

本研究旨在探讨不同厂商的烯丙孕素对后备母猪同期化发情及繁殖性能的影响。通过给后备母猪饲喂3个不同厂商(A、B和C)的烯丙孕素14 d或18 d,观察母猪的配种分娩指标以及繁殖性能指标。结果显示,A厂商烯丙孕素处理18 d的效果优于14 d的效果,与对照组相比,饲喂A厂商烯丙孕素18 d可以显著提高后备母猪的发情率、受胎率、分娩率、窝总产仔数和窝产健仔数(P<0.05),显著降低母猪的空胎率(P<0.05);饲喂B厂商烯丙孕素14 d可以显著提高后备母猪的发情率(P<0.05),其繁殖性能与对照组无显著差异(P>0.05);饲喂C厂商烯丙孕素14 d和18 d的效果相近,均可显著提高母猪的发情率(P<0.05),且饲喂18 d可以提高窝总产仔数,显著提高窝产健仔数(P<0.05)。该研究为后期养猪场选择烯丙孕素提供数据依据。

混合精液输精对母猪繁殖力影响的研究

为探究一个情期内输单头公猪精液与两头公猪混合精液对母猪繁殖力的影响,对泉州市某规模化猪场繁殖性能相对稳定的3~6胎“长×大”经产发情母猪随机分成两组,第1组为单精组(186头),输单头杜洛克公猪精液;第2组为混精组(155头),输两头杜洛克公猪混合精液。饲养至分娩,测定繁殖力。结果表明使用混合两头公猪精液配种对母猪的受胎率、分娩率均有提高,窝均产总仔数和窝均产健仔数均极显著高于使用单头公猪精液配种(P<0.01)。使用混合两头公猪精液输精可显著提高母猪繁殖力。

Heritabilities and genetic and phenotypic correlations of litter uniformity and litter size in Large White sows

Litter uniformity, which is usually represented by within-litter weight coefficient of variation at birth （CVB）, could influence litter performance of sows and the profitability of pig enterprises. The objective of this study was to characterize CVB and its effect on other reproductive traits in Large White sows. Genetic parameters and genetic correlation of the reproductive traits, including CVB, within-litter weight coefficient of variation at three weeks （CVT）, total number born （TNB）, number born alive （NBA）, number born dead （NBD）, gestation length （GL）, piglet mortality at birth （Mo）, piglet mortality at three weeks （M3）, total litter weight at birth （TLW0）, and total litter weight at three weeks （TLW3） were estimated for 2 032 Large White litters. The effects of parity and classified litter size on CVB, CVT, TNB, NBA, NBD, GL, M0, M3, TLW0, and TLW3 were also estimated. The heritabilities of these reproductive traits ranged from 0.06 to 0.17, with the lowest heritability for CVB and the highest heritability for TLW0. Phenotypic and genetic correlations between these reproductive traits were low to highly positive and negative （ranging from -0.03 to 0.93, and -0.53 to 0.93, respectively）. The genetic correlations between TNB and CVB, and between M0 and CVB were 0.32 and 0.29, respectively. In addition, CVB was significantly influenced by parity and litter size class （P〈0.05）. All the results suggest that piglet uniformity should be maintained in pig production practices and pig breeding programs.

Analysis of PRLR and BF Genotypes Associated with Litter Size in Beijing Black Pig Population

This study is aimed at using the DNA mutations in the prolactin receptor （PRLR） and properdin （BF） genes to determine associations between the genotype and litter size in the Beijing Black pig population. A total of 321 Beijing Black pig sows were genotyped using the polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） method, with the Alu I and Sma I for PRLR and BF genes, respectively. Two different alleles of PRLR and BF genes were identified： allele A （0.25） and B （0.75） of the PRLR gene, allele A （0.13） and B （0.86） of the BF gene. The association analysis between the genotypes and the litter size were estimated with the method of the general linear model. The analysis results of PRLR showed that in first parity, sows with genotype AA had a larger litter size than sows with genotype AB and BB, but the difference was statistically not significant. In later parities, statistically significant （P 〈 0.05） differences were seen between sows with genotypes AA and AB, and BB of the PRLR gene. The associated analysis results between genotypes and litter size （total number born, TNB, and number born alive, NBA） showed that there were no significant differences in the first parity sows with different genotypes of the BF gene, but significant differences appeared in NBA between the sows of genotypes AB and BB, in later parity, for which significantly higher values were observed in the offspring of heterozygotes. Considering the consistent genotypic effect on the litter size of both sows in first parity and later parity, it was concluded that the locus of the PRLR gene, digested with Alu I, could be the gene maker for the litter size in Beijing Black pigs.

Contribution of soil fauna to the degradation of recalcitrant components in Cinnamomum camphora foliar litter in different-sized gaps in Pinus massoniana plantations

Forest gaps are important in forest dynamics and management, but little is known about how soil fauna influence the degradation of recalcitrant litter components in different-sized forest gaps. This investigation uses litterbags with two different mesh sizes (0.04 and 3 mm) to control the meso- and microfauna entering the bags to quantify the contribution of soil fauna to the degradation of recalcitrant components (including condensed tannins, total phenol, lignin and cellulose) during litter decomposition. The experiment was conducted in seven different forest gap sizes in Pinus massoniana plantations over 1 year. One closed-canopy site (CC) and forest gap sizes of 100, 225, 400, 625, 900, 1225 and 1600 m^2 were created in a P. massoniana plantation in the Sichuan basin of China;the CC was treated as the control. Cinnamomum camphora foliage from local native trees was used in all forest gap experiments. We found the following:(1) Gap size had significant effects on the degradation rates (E) of condensed tannins and lignin and on the contributions of soil fauna;medium-sized gaps also presented high degradation rates. Soil fauna obviously contributed to the degradation of recalcitrant foliar litter components in medium-sized gaps.(2) The highest contribution to degradation (40.98%) was recorded for lignin, and the lowest contribution (0.29%) was recorded for condensed tannins. The results indicate that medium-sized gaps (900 m^2) were conducive to the degradation of recalcitrant litter components by soil fauna.

Study on the Effect of ESR and FSH β Genes on Litter Size in Local Northeast Three Pig Breeds

The method of PCR RFLP was used to analyze the effects of ESR and FSH β genotypes on the litter size,especially the corresponding changes with the difference of genotype distributions in the Min,Sanjiang and Junmu I pigs.The results show that the ESR and FSH β genes are the major genes of litter size;the heterozygous genotype for ESR as well as for FSH β locus has a more litter size than others.However,the combined genotype ABDD means a more litter size than other genotypes,the frequencies of the heterozygous genotypes in Sanjiang and Junmu I are lower than in Min which maybe one of the most important reasons for the little litter sizes of those two breeds.

Characterization of Porcine Matrix Metalloproteinase 23 (pMMP-23) Gene and Its Association with Litter Size Traits

The matrix metalloproteinase 23 （MMP-23）, which might play a role in ovulation in mammals, was one of the promising candidate genes for litter size traits in pigs. In the present research, partial sequence of porcine MMP-23 （pMMP-23） gene, including exons 2-8 （GenBank： EU360790）, was obtained. Real-time PCR analysis revealed that pMMP-23 gene was highly expressed in ovary. PCR-Sau3A I-RFLP and PCR-Acc II-RFLP assay were established to detect a C/T mutation in exon 3 （EU360790： g. 269C〉T） and an A/G mutation in exon 4 （EU360790： g. 505A〉G）, respectively. Association study for these two SNPs with litter size was assessed in three independent populations （Minzhu, Landrace I and Landrace II）. Statistical analysis demonstrated that for second and subsequent litters, TT sows produced more TNB than CC pigs in Landrace breed （P〈0.05） at g. 269C〉T locus, and the additive effect was significant （P〈0.05）; GG sows produced more TNB and NBA than AA pigs in Minzhu （P〈0.01） and Landrace breeds （P〈0.05） at g. 505A〉G locus, and the additive effect was significant （P〈0.01 or P〈0.05）. Our study suggested that the pMMP-23 gene might be a novel candidate gene for litter size traits, and g. 505A〉G locus might be a useful molecular marker for marker assisted selection （MAS）.

Erythropoietin Receptor Gene (EPOR) Polymorphisms are Associated with Sow Litter Sizes

The erythropoietin receptor （EPOR） has shown to play an important role in fetal survival by promoting the maturation of red blood cells in many studies of uterine capacity and litter size in swine. In this study, we screened the porcine EPOR gene for mutations and identified five single nucleotide polymorphisms （SNPs）： g.705G〉T in intron 1, g.2 373C〉T in intron 4, and g.2 882C〉T, g.3 035A〉G, and g.3 132A〉T in intron 6. We then genotyped 247 Beijing Black （BB） sows and compared the polymorphism data with the litter sizes of 1 375 parities among the sows. At first parity, there was no association of g.2 882C〉T and g.3 132A〉T with litter sizes. However, the CT sows in g.2 882C〉T had 2.13 higher total number born （TNB） （P〈0.01） and 1.81 higher number born alive （NBA） （P〈0.01） than the CC sows and the heterozygous sows in g.3 132A〉T had the highest litter size when compared to the two homozygotes for the later parities （P〈0.05）. In the g.3 035A〉G SNP, for the later parities, the TNB of the sows with the GG genotype was 3.81 higher （P〈0.01） and the NBA was 2.75 higher （P〈0.01） than that with the AA genotype but no difference at first parity. The G allele of the EPOR g.705G〉T SNP was associated with a greater litter size at both the first parity （P〈0.05） and later parities （P〈0.01）. Furthermore, we determined the allele frequencies for this SNP among five Chinese indigenous pig breeds （Erhualian, Laiwu Black, Meishan, Min, and Rongchang） and three western commercial pig breeds （Duroc, Landrace, and Large White）. The G allele of the EPOR g.705G〉T SNP was significantly more common in the more prolific Chinese breeds. These results indicated that the EPOR could be an important candidate gene for litter size and g.705G〉T can serve as a useful genetic marker for improving litter size in both first and later parities in swine.

Identification of Novel Polymorphisms in Porcine Ring Finger Protein 4 and Matrix Metalloproteinase 9 Genes and Association Analysis with Litter Size Traits

Reproduction trait plays an important role in pig production. Identification of molecular markers that are linked to litter size may contribute to the genetic development of porcine reproduction traits. In this study, porcine ring finger protein 4 （pRNF4） and Matrix metalloproteinase 9 （pMMP-9） were selected as candidate genes on the basis of their physiological roles in reproduction. Two single-nucleotide polymorphisms （416C〉T in pRNF4 and - 1257G〉A in pMMP-9） that could be detected by PCR restriction fragment length polymorphism （PCR-RFLP） were discovered and tested for statistical associations with litter size traits in three populations. For 416C〉T, TT genotype was associated with a significantly higher （p〈0.05） number of live births than those recorded for CC sows and the additive effect was significant （p〈0.05） in Qingping and Min Pigs populations in later parities. For -1257G〉A, inconsistent results were found in three populations. The results suggested that T allele in pRNF4 gene might confer a high prolificacy in breeding and further studies were needed to confLrm the results.