野猪RBP4基因的克隆、表达及变异初步研究

视黄醇结合蛋白是体内一类将维生素A从肝中转运至靶组织以实现维生素A的细胞内转运代谢的特异的运裁蛋白,在协助维生素A发挥生理功能中起着不可替代的作用.它既是一个影响猪的繁殖性状的候选基因,同时也是一个研究维生素A代谢障碍及肥胖症的候选基因.为了进一步揭示其群体遗传变异,寻找新的遗传标记,本研究对野猪(Sus scrofa ussuricus)RBP4基因进行了克隆、表达和序列分析,并对所发现的点突变进行了基于限制性内切酶Msp Ⅰ的PCR-RFLP分析.序列分析表明野猪与大白猪相比存在着4个SNPs;该基因在野猪的肝脏、肾脏、肺、大肠和肌肉中表达,在心脏、胃、脾、小肠和睾丸中不表达;对14头野猪的酶切多态性分析表明该突变位点是多态位点,并且3种基因型的分布符合Hardy-Weinberg定律.     

犬MC1R基因R306ter与毛色性状相关性研究

目的　分析犬MC1R基因中R30 6ter位点多态性与犬毛色表型的相关性 ,为遗传育种 ,培育出更加优良的实验用犬奠定基础。方法　采用PCR SSCP技术 ,对MC1R基因R30 6ter位点进行基因多态性检测 ,分析位点多态性与毛色性状之间的相关性 ,并对该位点进行克隆测序。结果　PCR SSCP分析结果表明 ,R30 6ter位点序列具有多态性 ,表现为C、D二个等位基因和CC、CD及DD三种基因型。对R30 6ter多态性片段克隆测序发现 ,MC1R基因在编码第 30 6位氨基酸的密码子处存在一个由CGA到TGA的终止突变。结论　经统计分析结果表明在杂种犬中MC1R基因多态性与毛色性状不存在显著的相关性 ,这可能是由于外科手术学教学用犬是杂种犬 ,其遗传背景不同所致。由于MC1R基因的R30 6ter位点内存在碱基变异 ,因此在杂种犬中表现出明显的PCR SSCP多态性     

三个绵羊群体MC4R基因多态性及生物信息学分析

旨在探讨绵羊黑素皮质素受体-4(melanocortin-4 receptor,MC4R)的分子机理,采用PCR-SSCP方法对3个绵羊群体(甘肃肉用绵羊新品种群、小尾寒羊和湖羊)的MC4R基因外显子进行多态性检测和生物信息学分析。结果表明,3个绵羊群体均存在3种基因型AA型、AB型和BB型,优势基因型为BB,其中优势等位基因为B;测序结果表明,野生型BB型和突变型AB型相比,AB型个体在该基因编码区第511位点发生G→A突变,第495位发生C→T突变;AA型个体在该基因编码区第511位点发生G→A突变,出现AA的纯合,第495位发生C→T突变,出现CC纯合;3个绵羊群体中小尾寒羊的多态信息含量属于中度多态(0.25PIC0.50),甘肃肉用绵羊新品种群羊和湖羊属于低度多态(PIC0.25);χ2适合性检验表明除湖羊之外,其余2个绵羊品种均处于Hardy-Weinberg平衡状态。生物信息学分析发现MC4R氨基酸序列有明显的疏水性区域,有7个跨膜螺旋区及信号肽,其编码蛋白主要的二级结构元件是α螺旋和无规则卷曲;同源性比对发现绵羊MC4R基因与山羊、牛、野猪、人类及大猩猩的相似度分别为97%、94%、81%、83%及83%,说明MC4R是一个非常保守的蛋白,在绵羊的生长发育中起着重要作用。     

鸡MC4R基因的SNPs及其与屠体性状的相关研究

黑素皮质素受体(MC4R, melanocortin-4 receptor)基因的突变与猪、鼠和人等的食欲、肥胖、生长等性状有关, 而鸡MC4R基因的功能却知之甚少. 利用PCR-SSCP(single strand conformation polymorphism)和DNA测序的方法, 对资源家系F₂代鸡群MC4R基因多态性进行了分析, 发现存在4个单核苷酸多态(SNPs, single nucleotide polymorphisms)位点. 其中, 在MC4R基因5′调控区-524 nt发生了碱基的转换突变(C→T), 导致突变型基因比野生型基因多了一个NF-E2和一个cap转录因子结合位点; 在MC4R编码区(61 nt)发生了碱基的错义突变(G→A), 导致此处蛋白质的氨基酸由甘氨酸变为精氨酸; 在MC4R编码区315和336 nt发生了碱基的颠换突变(G→T)和转换突变(C→T), 这两个突变为同义突变. 通过最小二乘分析SNPs与屠体性状的关系, 结果是突变的BB, DD和FF等基因型与鸡的体重、全净膛重(或半净膛重)、腿肉重等存在显著(P<0.05)或极显著(P<0.01)的关系, 但与腹脂重不显著. 结果表明, MC4R基因可以作为影响和控制鸡体重、生长等屠体性状的主要候选基因.     

虹鳟MC4R基因的PCR扩增及其应用

黑素细胞皮质激素受体(MC4R)是跨膜G蛋白偶联受体。MC4R在人和鼠的体重、能量稳态和采食量的调控中具有重要作用,是第一个发现的与人类显性遗传疾病性肥胖相关的靶位点。虹鳟(Oncorhynchus mykiss)属于冷水性鱼类,具有很好的药用和食用价值,但生长缓慢。本研究根据斑马鱼的MC4R基因保守区的核苷酸序列设计引物,通过PCR扩增出虹鳟的MC4R基因,纯化后测序。本实验测出虹鳟MC4R基因968bp,并发现其与其它鱼类的MC4R进行了同源性分析,构建基因进化树。     

红鳍东方鲀(Takifugu rubripes)MC4R基因的多态性分析

采用PCR-SSCP(single strand conformation polymorphism)技术和DNA测序方法分析红鳍东方鲀MC4R(Melanocortin-4receptor)基因编码区多态性。在MC4R基因编码区48 nt和264 nt均发生了碱基的转换突变(G→A),两个突变位点分别位于M1和M2引物扩增产物中。引物M1扩增产物SSCP分析得到两种基因型:AA基因型和AB基因型,并且AA基因型和A等位基因频率明显高于AB基因型和B等位基因。引物M2扩增产物也得到两种基因型:CC基因型和CD基因型,CC基因型和C等位基因频率明显高于CD基因型和D等位基因。遗传变异结果分析表明,两个突变位点均属于低度多态性,而且群体遗传杂合度较低,反映了该群体的遗传一致性较高。     

鸽黑素皮质素受体3、4(MC3R、MC4R)基因多态性与生长性状的相关分析

利用PCR-SSCP技术和DNA测序方法检测广东石岐肉鸽和哈尔滨地区灰色家鸽MC3R和MC4R基因部分编码区序列的单核苷酸多态性, 分析了MC3R基因T91G突变位点和MC4R基因A903G突变位点导致的基因型与两群体鸽生长和体组成性状的关系。结果表明, 这两个多态位点所导致的基因型对石岐肉鸽活重、屠体重、全净膛重均有显著影响(P<0.05); 另外, 利用这两个突变位点所产生的合并基因型在鸽群体中与生长和体组成性状作最小二乘分析, 结果表明, 两位点合并后的基因型对全净膛重影响显著(P<0.05)。多重比较结果表明, BBAA型全净膛重显著大于AABB型, BBAA型对于体重增长是有利基因型。     

比格犬MC4R基因多态性与体重相关性的研究

为了分析比格犬黑素皮质素受体-4基因多态性与犬体重的关系, 根据犬MC4R基因DNA外显子序列, 设计MC4R基因特异PCR引物1对, 犬DNA经PCR扩增, 克隆和测序, 寻找和确定犬MC4R基因的多态性位点, 分析多态性与犬体重的关系。结果在比格犬MC4R基因中发现2处单碱基缺失突变, 1个单碱基颠换变异, 存在Psh AⅠ酶切位点, 并基于PshAⅠ酶切位点建立了PCR-RFLP技术。统计分析显示犬MC4R基因型与体重显著相关, 可以考虑将MC4R基因作为犬体重的候选基因。     

从江香猪MC4R基因多态性及生物信息学分析

[目的]旨在对3个群体猪MC4R基因进行SNPs筛选,为从江香猪选种选育提供一定的理论基础。[方法]以从江香猪作为研究对象,野猪×从江香猪二元杂交猪和杜×大×长外三元杂交猪作为对照,构建品种DNA池,PCR扩增MC4R基因外显子、内含子和3’非编码区序列,采用直接测序法对3个群体的MC4R基因进行单核苷酸多态性检测,利用生物信息学软件预测不同多态性位点对MC4R基因mRNA二级结构和蛋白质二级结构的影响。[结果]在3个群体中共检测出10个SNPs位点,其中,C860T、G1392A和G1577A位于第2外显子区;G1699A、T1702A、A1870C、G1875A、C2025T、G2073A和A2111T位于3’非编码区序列。C860T为同义突变,G1392A和G1577A为错义突变,分别导致了精氨酸变为组氨酸、天冬氨酸变为天冬酰胺。经分析软件预测,处于第二外显子中的3个SNPs位点对MC4R基因的mRNA二级结构、蛋白质二级结构有一定的影响。[结论]DNA池结合测序技术检测到MC4R基因外显子、内含子和3’非编码区序列共10个SNPs。     

猪资源家系MC4R基因扫描及其与脂肪性状的相关分析

黑素皮质激素受体－4（Melanocortin-4 Receptor,MC4R)是在人类肥胖研究中发现的重要调节因子,它可以与瘦蛋白（Leptin),神经肽Y（Neuropeptide Y,NPY),α－黑素细胞刺激激素（Alpha-melanocyte-stimulating hormone,α-MSH)第一起调节动物体重和采食量。采用PCR－RFLP技术,分析了MC4R基因部分片段在猪资源家系群体中的TaqⅠ酶切片段多态性分析。MC4R基因多态性与生长肥育性状,肉质性状,胴体性状的相关性分析的结果表明,MC4R基因型频率在不同品种群体中的分布不同;MC4R基因与猪胸腰椎间膘厚,臀部膘厚,平均背膘,眼肌宽度,眼肌面积,皮率呈显著性相关。MC4R基因主要以显性作用方式发挥作用,加性作用不显著。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.