猪激素敏感脂肪酶(HSL)基因的研究概况

激素敏感脂肪酶(HSL)基因影响着脂肪的沉积,它在表达或活性上的轻微变异均有可能影响猪的背膘厚和瘦肉率。从激素敏感脂肪酶的功能及作用机制出发,通过候选基因策略克隆出HSL基因,将其精确定位于猪6号染色体6p1.1-1.2上;进而分析了HSL及其基因的分子结构,比较HSL基因在不同物种间的同源性。不同产肉型猪种间存在HSL基因的多态性,籍此可为了解猪脂肪沉积的基因效应、寻找与背膘厚及瘦肉率相连锁的分子标记提供通途,最终实现利用MAS、MAI等技术手段提高猪的瘦肉率。Abstract:The gene affects the accumulation of lipid and its small variation on the activity or gene expression can influence the lean percentage and backfat traits.Based on the function and acting mechanism,this gene was cloned by candidate approach and located on the porcine chromosome 6P1.1～1.2.The molecular structure of HSL and HSL gene were analyzed.The homologies was attained by comparison between different mammal animals.The polymorphism of the gene in different pig breeds was detected.This will help the understanding of the genic effect on porcine fat deposition.The HSL gene should be regarded as a candidate gene for fatness in pis.It may have a potential use in MAS or MAI to increase the lean percentage of pig.     

Exploration of genes showing intramuscular fat deposition-associated expression changes in musculus longissimus muscle

Marbling, as defined by the amount of intramuscular fat, is an economically important trait in beef cattle. Intramuscular fat deposition is postulated to arise mainly from a series of adipogenic events in intramuscular adipocyte-lineage cells and in the physiological or anatomical milieux surrounding them. This study was designed to investigate gene-expression patterns associated with fat deposition in musculus longissimus muscle, including adipocyte-lineage cells and part of the milieux. Differential-display PCR (ddPCR) was used to examine expression differences between low-marbled and high-marbled steer groups at 8, 10, 12 and 14 months of age, encompassing the time that marbling starts to appear. Seventy-four of 2114 total bands on ddPCR gel-bands were significant (P < 0.05) for the group effect, the interaction effect between group and age, or both the group and the interaction effects. Sequence analysis of 72 of these bands revealed 77 genes, including 35 annotated genes and 42 novel sequences. Among the 35 annotated genes, 6 (BTG2, PDHB, SORBS1, TRDN, TTN and MGP) have been related to changes in intramuscular fat deposition, possibly by exerting effects on adipocyte-lineage cells or on the milieux surrounding them.     

miRNA和lncRNA在动物脂肪沉积中的研究进展

微小RNA(MicroRNA,miRNA)是一类由18–25个核苷酸组成的高度保守的核苷酸序列,它可以特异性结合信使RNA (mRNA)的3′-非编码区域,进而发挥降解mRNA或阻遏mRNA翻译的负调控作用。长链非编码RNA (Long non-coding RNA,lncRNA)是一类长度超过200个核苷酸、不能编码蛋白质或只能编码蛋白质微肽的核苷酸序列,它可以在表观遗传、转录水平和转录后水平调控基因表达。脂肪作为一种重要的储能物质,在调节动物体能量平衡过程中发挥着重要的作用,并与动物产肉量、肉品质等产肉性状密切相关。而脂肪功能的紊乱可导致高血脂、Ⅱ型糖尿病以及一系列心血管疾病发生,因此动物脂肪沉积的分子调控机制备受人们关注。近年来,越来越多的研究发现miRNA和lncRNA在动物脂肪沉积中发挥重要作用。文中就现阶段miRNA和lncRNA在动物脂肪沉积中的研究进展进行综述,以期为进一步揭示动物脂肪沉积的分子调控机制提供理论指导和新思路。     

猪脂肪及肌肉组织中基因表达信息分析

为探测猪脂肪及肌肉组织中基因表达概况,利用猪EST资源和人类基因序列开展计算机模拟研究,旨在为猪肉质改良的遗传基础分析提供候选信息。执行Blast比对程序以识别人类基因组基因与猪EST序列间的同源性并筛选出高度同源记录,同时编制4个Java程序进行序列检索收集、序列比对结果的过滤筛选以及分类处理。统计分析表明：至少有2002个基因在猪脂肪及肌肉组织中表达,其中1087个基因在脂肪组织表达,1205个基因在肌肉组织中表达,两组织共同表达的基因为290个;筛选出高同源基因,同时分类统计出了114个基础活性基因(脂肪和肌肉组织分别表达80和34个),并选取Top记录进行了描述分析和总结。     

乌金猪FTO基因的克隆和表达分析

目的:克隆乌金猪脂肪和肥胖相关基因(FTO)编码区序列(CDS),分析其序列组成特征及在乌金猪不同组织中的表达情况。方法:采用反转录PCR方法从乌金猪脂肪组织中克隆FTO基因CDS,利用生物信息学方法分析其序列组成特征;采用实时PCR方法分析乌金猪FTO基因mRNA在不同组织中的表达情况。结果:克隆的FTO基因全长1518 bp(已提交至GenBank数据库,登录号为JQ031263),编码由505个氨基酸残基构成的蛋白,推测的相对分子质量为58.16×103,等电点为5.18;乌金猪与牛、羊、人和大鼠的FTO蛋白的氨基酸序列同源性分别为91%、90%、89%和83%;进化树分析显示,推测的乌金猪FTO蛋白的氨基酸组成与牛、羊的亲缘性较近,其次是人、大鼠;推测的氨基酸组成中无跨膜区,无信号肽,为亲水蛋白;分析发现该蛋白有22个磷酸化修饰位点,包括10个丝氨酸蛋白激酶磷酸化位点、7个苏氨酸蛋白激酶磷酸化位点、5个酪氨酸蛋白激酶磷酸化位点,200、246、302位氨基酸残基有糖基化位点;二级结构预测发现该蛋白共有201个螺旋、33个伸展链和271个卷曲结构;实时PCR检测的组织表达谱表明,FTO基因mRNA在乌金猪肝脏组织中的表达量最高,在脂肪、肾、脾中也有大量表达,在心脏、肌肉中的表达量最少。结论:为深入探讨乌金猪FTO基因的生物学功能奠定了重要基础。     

酚类化合物在猪脂肪沉积中的作用

脂肪沉积的数量和部位是影响猪肉品质的重要因素。近年来的研究表明,天然成分在降低皮下和内脏脂肪沉积、提高肌内脂肪沉积方面具有重要作用。并且,天然产物具有绿色、安全、无添加和无残留等优势。而从水果、蔬菜以及草本类植物中提取的酚类化合物是天然成分中的重要一员。本文对酚类化合物在猪脂肪沉积中的作用研究进行了综述,可为利用酚类化合物调控脂肪沉积,改善猪肉品质提供借鉴和参考。     

猪apoC3基因的遗传变异分析

目的:探究猪apoC3基因多态性,为进一步探讨其对脂肪沉积的影响和表达调控等研究提供依据。方法:选取具有不同脂肪沉积特点的3个猪种(可乐猪、贵州白香猪和大约克猪)构建品种DNA池并进行测序,结合各SNP位点测序峰高比值估算等位基因频率,并利用在线软件对不同基因型的转录结合位点及mRNA二级结构进行预测。结果:在3个猪种的apoC3基因中共发现17个SNPs(2个位于5’侧翼区;1个位于外显子3中,为同义突变;1个位于3’非翻译区,其它13个分别位于3个不同内含子中),其中C813G变异增加了一个转录因子GATA-2结合位点,G2280A变异导致mRNA二级结构最小自由能增加0.4kkal/mol。结论:不同猪种间apoC3基因SNPs位点等位基因频率差异较大,而apoC3基因编码区相对保守。     

Bovine gene polymorphisms related to fat deposition and meat tenderness

Leptin, thyroglobulin and diacylglycerol O-acyltransferase play important roles in fat metabolism. Fat deposition has an influence on meat quality and consumers' choice. The aim of this study was to determine allele and genotype frequencies of polymorphisms of the bovine genes, which encode leptin (LEP), thyroglobulin (TG) and diacylglycerol O-acyltransferase (DGAT1). A further objective was to establish the effects of these polymorphisms on meat characteristics. We genotyped 147 animals belonging to the Nelore (Bos indicus), Canchim (5/8 Bos taurus + 3/8 Bos indicus), Rubia Gallega X Nelore (1/2 Bos taurus + 1/2 Bos indicus), Brangus Three-way cross (9/16 Bos taurus + 7/16 Bos indicus) and Braunvieh Three-way cross (3/4 Bos taurus + 1/4 Bos indicus) breeds. Backfat thickness, total lipids, marbling score, ribeye area and shear force were fitted, using the General Linear Model (GLM) procedure of the SAS software. The least square means of genotypes and genetic groups were compared using Tukey's test. Allele frequencies vary among the genetic groups, depending on Bos indicus versus Bos taurus influence. The LEP polymorphism segregates in pure Bos indicus Nelore animals, which is a new finding. The T allele of TG is fixed in Nelore, and DGAT1 segregates in all groups, but the frequency of allele A is lower in Nelore animals. The results showed no association between the genotypes and traits studied, but a genetic group effect on these traits was found. So, the genetic background remains relevant for fat deposition and meat tenderness, but the gene markers developed for Bos taurus may be insufficient for Bos indicus.     

PPAR基因与脂肪代谢调控

过氧化物酶体增值剂激活受体(PPARs)基因属于类固醇/甲状腺/维甲酸受体超家族,有3个亚型,即：PPAR-α、PPAR-β和PPAR-γ。PPARs具有多种生物学功能,如增强机体对胰岛素敏感性,调节体内糖平衡等,尤其在脂肪分化、生成等多方面起到重要作用,是目前的研究热点,文章从PPARs基因的结构,表达及功能等方面讨论了其与脂肪代谢调控的关系。     

Transcriptional regulation of acetyl-CoA carboxylase α isoforms in dairy ewes during conjugated linoleic acid induced milk fat depression

Feeding trans-10, cis-12 CLA to lactating ewes reduces milk fat by down-regulating expression of enzymes involved in lipid synthesis in the mammary gland and increases adipose tissue lipogenesis. Acetyl-CoA carboxylase α (ACC-α) is a key regulated enzyme in de novo fatty acid synthesis and is decreased by CLA. In the ovine, the ACC-α gene is expressed from three tissue-specific promoters (PI, PII and PIII). This study evaluated promoter-specific ACC-α expression in mammary and adipose tissue of lactating cross-bred Lacaune/Texel ewes during milk fat depression induced by rumen-unprotected trans-10, cis-12 CLA supplement. In all, 12 ewes arranged in a completely randomized design were fed during early, mid and late lactation one of the following treatments for 14 days: Control (forage+0.9 kg of concentrate on a dry matter basis) and CLA (forage+0.9 kg of concentrate+27 g/day of CLA (29.9% trans-10, cis-12)). Mammary gland and adipose tissue biopsies were taken on day 14 for gene expression analysis by real-time PCR. Milk fat yield and concentration were reduced with CLA supplementation by 27%, 21% and 35% and 28%, 26% and 42% during early, mid and late lactation, respectively. Overall, our results suggest that trans-10, cis-12 CLA down-regulates mammary ACC-α gene expression by decreasing expression from PII and PIII in mammary gland and up-regulates adipose ACC-α gene expression by increasing expression from PI.