广州地区106例汉族人群MICA和MICB微卫星基因座 单体型研究

利用聚合酶链反应和荧光（6－FAM）自动化检测技术对广东地区汉族106例无亲缘关系样本进行MICA基因外显子5和MICB基因内含子1微卫星基因座多态性及其单体型分布调查。根据群体资料估算两者间的单体型频率、连锁不平衡参数、相对连锁不平衡参数。结果显示,广州地区汉族人群MICA和MICB微卫星基因座基因型分布符合Hardy-Weinberg平衡法则,共检出MICA微卫星基因座 5个等位基因, MICB微卫星基因座14个等位基因。其中MICA A5基因频率最高（0.2877）,A4基因频率最低（0.1321）。MICB CA14等位基因频率最高（0.3255）,CA19、CA28等位基因频率最低（0.0047）,未检出CA27。21种MICA－MICB单体型频率大于1%(连锁不平衡参数>0), 其中单体型A5－CA14 (16.73%), A5.1－CA18 (8.75%), A4－CA26(3.76%),A9－CA15(3.66%)和A6－CA21(2.61%)为强连锁常见单体型（χ2>3.84, P<0.05）。广州地区汉族人群MICA和MICB微卫星基因座多态性和单体型分布有其自身特点,MICA和MICB微卫星基因座适合做为遗传标志,用于人类学、遗传疾病基因连锁分析、法医学亲子鉴定和个体识别等研究领域。Abstract: This study is to investigate genetic polymorphisms and haplotypes of microsatellite locus in the exon 5 of the MICA gene and intron 1 of the MICB gene based on 106 samples of Guangzhou Han Population by polymerase chain reaction and fluorescent technique (6-FAM). The corresponding haplotype frequencies, linkage disequilibria values and relative linkage disequilibria values were estimated based on population data. The results show that the genotype distributions of MICA and MICB microsatellite meet Hardy-Weinberg equilibrium in Guangdong Han population. In total, 5 alleles of MICA microsatellite locus and 14 alleles of MICB microsatellite locus were observed. MICA A5 was the most common allele (0.2877), whereas A4 was the least popular one (0.1321). MICB CA14 was the most common allele (0.3255), and CA19 and CA28 were the least popular ones (0.0047). CA27 was not observed. Twenty-one kinds of MICA-MICB haplotypes occurred at frequencies of more than 1% (linkage disequilibria value>0). The common MICA-MICB haplotypes were A5-CA14（16.73％）, A5.1- CA18 (8.75%), A4- CA26(3.76%),A9-CA15(3.66%) and A6-CA21(2.61%)（χ2>3.84, P<0.05）, and they were strong linkage disequilibria. The polymorphisms and haplotypes distributions of MICA and MICB microsatellite locus in Guangzhou Han population have their own genetic characteristics. The microsatellite locus of the exon5 of the MICA gene and intron 1 of the MICB gene could be used as the genetic markers in the studies of anthropology, linkage analysis of genetic disease genes, individual identification and paternity test in forensic medicine.     

广州地区106例汉族人群MICA和MICB微卫星基因座 单体型研究 The Study on the Haplotype of MICA and MICB Microsatellite Locus In Guangzhou Han Population

利用聚合酶链反应和荧光（6－FAM）自动化检测技术对广东地区汉族106例无亲缘关系样本进行MICA基因外显子5和MICB基因内含子1微卫星基因座多态性及其单体型分布调查。根据群体资料估算两者间的单体型频率、连锁不平衡参数、相对连锁不平衡参数。结果显示，广州地区汉族人群MICA和MICB微卫星基因座基因型分布符合Hardy-Weinberg平衡法则，共检出MICA微卫星基因座 5个等位基因， MICB微卫星基因座14个等位基因。其中MICA A5基因频率最高（0.2877），A4基因频率最低（0.1321）。MICB CA14等位基因频率最高（0.3255），CA19、CA28等位基因频率最低（0.0047），未检出CA27。21种MICA－MICB单体型频率大于1%(连锁不平衡参数>0), 其中单体型A5－CA14 (16.73%), A5.1－CA18 (8.75%), A4－CA26(3.76%)，A9－CA15(3.66%)和A6－CA21(2.61%)为强连锁常见单体型（χ2>3.84, P<0.05）。广州地区汉族人群MICA和MICB微卫星基因座多态性和单体型分布有其自身特点，MICA和MICB微卫星基因座适合做为遗传标志，用于人类学、遗传疾病基因连锁分析、法医学亲子鉴定和个体识别等研究领域。Abstract: This study is to investigate genetic polymorphisms and haplotypes of microsatellite locus in the exon 5 of the MICA gene and intron 1 of the MICB gene based on 106 samples of Guangzhou Han Population by polymerase chain reaction and fluorescent technique (6-FAM). The corresponding haplotype frequencies, linkage disequilibria values and relative linkage disequilibria values were estimated based on population data. The results show that the genotype distributions of MICA and MICB microsatellite meet Hardy-Weinberg equilibrium in Guangdong Han population. In total, 5 alleles of MICA microsatellite locus and 14 alleles of MICB microsatellite locus were observed. MICA A5 was the most common allele (0.2877), whereas A4 was the least popular one (0.1321). MICB CA14 was the most common allele (0.3255), and CA19 and CA28 were the least popular ones (0.0047). CA27 was not observed. Twenty-one kinds of MICA-MICB haplotypes occurred at frequencies of more than 1% (linkage disequilibria value>0). The common MICA-MICB haplotypes were A5-CA14（16.73％）, A5.1- CA18 (8.75%), A4- CA26(3.76%)，A9-CA15(3.66%) and A6-CA21(2.61%)（χ2>3.84, P<0.05）, and they were strong linkage disequilibria. The polymorphisms and haplotypes distributions of MICA and MICB microsatellite locus in Guangzhou Han population have their own genetic characteristics. The microsatellite locus of the exon5 of the MICA gene and intron 1 of the MICB gene could be used as the genetic markers in the studies of anthropology, linkage analysis of genetic disease genes, individual identification and paternity test in forensic medicine.     

选择作用下家鸡淀粉酶的遗传多态性研究 ――基因频率分化、相关效应估计和标记辅助选择试验

对“三黄”鸡4个品系的血液淀粉酶(Amy-1)基因频率进行了估计, 结果表明: Amy-1基因频率具有明显的品系特异性, 父系Amy-1A高; 母系Amy-1B频率高。人工选择可能是导致两个具有相同遗传来源的品系（Ⅱ系和Ⅲ系）Amy-1基因频率发生分化的原因。利用线性模型估计了Amy-1基因的加性效应,结果表明：Amy-1B有利于产蛋性能, 而Amy-1A有利于体重和蛋重的提高。标记辅助选择试验结果表明, 选择Amy-1遗传型来改变家禽品系类型是可能的, 但效果有限, 因此, 对Amy-1的选择应结合于综合的选择方案之中。 Abstract　Gene frequencies at Amy-1 locus were estimated in 4 grand-parent lines of yellow broilers. The results indicated that the male lines exhibited higher frequency of Amy-1A while the female lines were featured by higher frequency of Amy-1B. Differentiation in gene frequencies at Amy-1 locus in line Ⅱ and Ⅲ, which were of identical origin, might be attributable to varied history of selection. Estimation of genotypic and gene effects suggested that Amy-1B was associated with higher laying performance, while Amy-1A was favorable for increased body and egg weights. It was also revealed that changing types of poultry lines by means of altering genotypes at locus Amy-1 was feasible, but its effect was limited. Accordingly, it is preferable to incoporate biochemical marker-assisted selection into complex programs of selection.     

犬MC1R基因T105A基因座多态性及 与毛色性状相关性的研究The

为了检测犬MC1R基因T105A基因座的多态性,并分析该多态性与犬毛色表型的相关性,抽取111只外科手术学实验用杂种犬血液并提取DNA,记录毛色表型。采用PCR-RFLP技术,对MC1R基因T105A基因座进行基因多态性分析,并对该基因座DNA进行克隆测序;用二元变量相关分析的统计学方法分析基因座多态性与毛色性状之间的相关性。经PCR-RFLP分析结果表明,T105A基因座序列具有多态性,表现为A、B二个等位基因和AA、AB及BB 3种基因型。A、B等位基因频率分别为72.97%和27.03%,基因杂合度（H）为0.39。基因型AA频率为55.86%,BB为9.91%,AB为34.23%。对T105A多态性片段DNA克隆测序后发现,MC1R基因在编码第105位氨基酸的密码子第一个碱基存在由G到A的单碱基突变,该突变导致第105位氨基酸发生由丙氨酸向苏氨酸的改变。统计分析结果表明MC1R基因T105A基因座的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实验用犬是杂种犬,其遗传背景不同所致,尚须在纯种犬群体中进一步研究MC1R基因对毛色的影响。 Abstract: In order to detect the polymorphism of T105A in MC1R gene in dogs and to analyze the relationship between the genetic polymorphisms and phenotypes of dog coat color, the blood samples of 111 cross-breed dogs were taken and their genomic DNAs were extracted. The phenotypes of dog coat color were recorded. The T105A locus of MC1R gene in the canine was detected through the technology of PCR-RFLP. Furthermore, the polymorphic fragments at T105A were sequenced. The relationships between the polymorphism of T105A and coat color trait were analyzed by the statistical methods of bivarate correlation analysis. By the method of PCR-RFLP, the T105A polymorphism was found with two alleles A and B and three genotypes AA, AB and BB. The frequencies of two alleles were 72.97% and 27.03%, respectively. The heterozygosity of T105A locus was 0.39. The frequencies of three genotypes were 55.86%, 34.23% and 9.91%, respectively. According to the results of sequencing, one base change from G to A at the position 105 was found at T105A locus and it altered amino acid at the position 105 from alanine to threonine. According to the statistical analysis, no significant association between the polymorphism of MC1R gene and the coat color was found and the result may be due to the differences of genetic background. Further research on MC1R gene should be done in pure breed dogs.     

云南怒族STR基因座遗传多态性研究

本文选择9个STR基因座和Amelogenin基因座,利用基因测序,采用基因扫描技术,对云南怒族聚集地区84名无关个体血样进行研究,建立了云南怒族9个STR基因座的基因频率数据库。用χ2检验,9个STR基因座基因型分布符合Hardy-Weinberg平衡定律。与其他民族资料一样,本课题所获得的云南怒族9个STR基因座数据是一组有价值的DNA多态性遗传标记资料。为建立我国不同民族STR基因数据库提供了资料。 Abstract:In this study,blood samples were randomly drawn from 84 unrelated Nu individuals.The polymorphism of nine STR loci and Amelogenin locus were determined by DNA GeneScan.The genetic database on the distribution of gene frequency on the nine STR loci was established,statistical results showed that the genotype distributions were in agreement with Hardy-Weinberg equation.Compared with other population,the results in our study were of great value in human DNA genetic data instant method with the characteristics of precision and sensitivity.     

鸡瘦蛋白受体(OBR)基因外显子9单核苷酸多态性分析

瘦蛋白受体属于Ⅰ类细胞因子超家族受体,其在瘦蛋白的信号转导中起着关键的作用。本研究根据瘦蛋白受体基因外显子9的序列设计引物,用PCR-SSCP的方法对高脂系（fatness line,FL）、低脂系(leanness line,LL)、北京油鸡、白耳鸡、石歧杂、矮小黄鸡、小型黄鸡、惠阳胡须鸡、隐性白羽鸡和海兰蛋鸡等品种（系）进行了单核苷酸多态性分析,并检测到了多态性。对两种纯合子片段克隆和测序,结果表明在编码区的1167位碱基发生了突变,由C突变为A,但是编码的氨基酸并没有发生改变。经独立性检验,基因型频率和基因频率分布与品种有关,北京油鸡的AA基因型频率显著高于其他品种;高脂系中A基因频率显著高于低脂系。 Abstract:Leptin receptor is a type I cytokine super family member and plays an important role in leptin functioning signal transduction.This study was designed to investigate the single nucleotide polymorphism (SNP) of OBR gene in various breeds,including Fatness Line (FL),Leanness Line (LL),Beijing Youji,Baierji,Shiqiza,Dwarf Yellow Chickens,Mini Yellow Chickens,Huiyang Huxuji,Recessive White Chickens and Hyline Layer.The primers for exon 9 in OBR gene were designed from the database of chicken genomic sequence and the SNPs were detected by PCR-SSCP method.One SNP (C/A at 1167 in cds) was found among individuals within all breeds.However,the amino acid was not changed because it was a silence mutantion.The result of population genetics analyses showed that the frequency of AA genotype in Beijing Youji was significantly higher than that in other lines.Also,the frequency of A allele in FL was significantly higher than that in LL.     

新疆四个民族八对遗传性状的基因频率

在调查新疆维吾尔、哈萨克、柯尔克孜、塔吉克族8对遗传性状的基础上分别计算出8对遗传性状在上述4个民族中的基因频率, 并进行了4个民族之间基因频率的比较。比较结果表明:塔吉克与其他3个民族之间基因频率的差异显著,而哈族与柯族之间的差异不显著。 Abstract:Acoording to the investigation of eight pairs of genetic traits among four minorities in Xinjiang (Uygur,Kazak,Kirgiz and Tajik),the gene frequencies of these traits were respectively calculated and compared.The results indicated that the difference of gene frequencies between Tajik and other three populations significant,while it is insignificant between kazak and Kirgiz.     

饲养东北虎的微卫星变异研究

东北虎是世界上濒危动物之一,具有极其重要的研究价值和保护意义。该研究利用10个在东北虎基因组中表现多态性的微卫星基因座（Fca005, Fca075, Fca094, Fca152, Fca161, Fca294, Pti002, Pti003, Pti007和Pti010）对113只饲养东北虎进行了遗传多样性检测。用非变性聚丙烯酰胺凝胶电泳检测微卫星的PCR扩增产物,计算了10个微卫星基因座的等位基因频率、基因杂合度、多态信息含量和有效等位基因数。在113只东北虎样品中,10个基因座的等位基因数为3～6个,其中Fca152最多;等位基因频率处于0.009～0.767之间。基因杂合度值在0.385～0.707间,平均为0.616,多态信息含量值在0.353～0.658间,平均为0.558,有效等位基因数处于1.629～3.409之间,平均为2.784,表明所选用的10个微卫星基因座在研究样品中均为中高度多态性基因座,具有比较明显的遗传变异。113只样品中包括75只毛发样品,23只血液样品和15只组织样品,不同样品的结果比较表明,毛发、血液和组织样品均可以得到清晰的扩增结果。所以,微卫星基因座与非损伤性DNA分析方法可以成功地应用于濒危珍稀动物的遗传多样性研究。 Abstract:. The tiger is one of the most threatened wildlife species since the abundance and distribution of tiger have decreased dramatically in the last century. The wild Amur tiger (Panthera tigris altaica) only distributed in northeast China, the far east area of Russia and the north Korea and its size of wild population is about 450 in the world and 20 in China. Several hundred captive populations of Amur tigers are the main source to protect gene library of tiger and the source of recovering the wild populations. The Breeding Center for Felidae at Hengdaohezi and Ha’erbin Tiger Park in Heilongjiang Province is the biggest captive breeding base in China. How to make clear the genetic pedigree and establish reasonable breeding system is the urgent issues. So we use the microsatellite DNA markers and non-invasive technology to research on the genetic diversity of captive Amur tiger in this study. Ten microsatellite loci (Fca005, Fca075, Fca094, Fca152, Fca161, Fca294, Pti002, Pti003, Pti007 and Pti010), highly variable nuclear markers, were studied their genetic diversity in 113 captive Amur tigers. The PCR amplified products of microsatellite loci were detected by non-denatured polyacry lamide gel electrophoresis. Allele numbers, allelic frequency, gene heterozygosity(He), polymorphism information content(PIC) and effective number of allele(Ne) were calculated. 41 alleles were found and their size were ranged from 110bp to 250bp in ten microsatellite loci, Fca152 had 6 alleles, Fca075, Fca094 and Fca294 had 5 alleles, Fca005 and Pti002 had 4 alleles and the others had 3 alleles in all tiger samples, respectively. The allelic frequencies were from 0.009 to 0.767; The He ranged from 0.385 to 0.707, and Fca294 and Pti010 locus had the highest and lowest value; the PIC were from 0.353 to 0.658, Fca294 and Pti010 locus had the highest and lowest value; and Ne were from 1.626 to 3.409, Fca294 and Pti010 locus had the highest and lowest value, which showed the ten microsatellie loci had high or medium polymorphism in these Amur tigers and had high genetic diversity. At the same time, we only found even bases variability which showed the even bases repeat sequence (CA/GT) maybe the basic unit for length variability of microsatellite in all loci. In this study, the samples were made up of 75 hair specimens, 23 blood specimens and 15 tissue specimens, we obtained the genome DNA from hairs using the non-invasive DNA technology and demonstrated that DNA derived from hair samples is as good as that obtained from blood samples for the analaysis of microsatellite polymorphism. These results imply that microsatellite DNA markers and non-invasive DNA technology can help study the genetic diversity of Amur tiger. This method could be used in the captive management of other endangered species.     

新疆维吾尔族HLA-Cw基因座遗传多态性调查 The Study of HLA-Cw Polymorphism in Uygur Population

采用序列特异性寡核苷酸探针杂交技术（PCR-SSOP）对146位新疆维吾尔族无关个体HLA-Cw基因座进行基因分型,研究该民族HLA-Cw基因座遗传多态性,建立新疆维吾尔族HLA-Cw基因频率数据库。检出18种等位基因,基因频率分布在0.0069~02460,其中HLA-Cw*04、07、08、14基因频率比较高,基因频率分别为02460、0.1151、0.1010、0.1202,共占新疆维吾尔族可检出等位基因的58.23%,PCR-SSOP分型技术使新疆维吾尔族HLA-Cw基因座空白基因频率降至0.0064。经χ2检验,基因型分布符合Hardy-Weinberg平衡定律。建立民族HLA-Cw基因座基因频率数据库,为临床器官移植配型、人类学、法医学提供重要的群体遗传学资料。 Abstract:The HLA-Cw loci polymorphism in Uygur population was investigated using the PCR- sequence specific oligonucleotide probe (SSOP) method,and the genetic database on the distribution of gene frequency of the HLA-Cw loci was established.From 146 individuals of Uygur population,18 HLA-Cw alleles were detected.The gene frequency was from 0.0069 to 0.2460.The four most common alleles were HLA-Cw*04(24.60%)、07(11.51%)、08(1010%)、14(12.02%),and they covered 58.23% of total alleles detected from Uygur population.We have made a survey of HLA-Cw alleles frequencies in a Uygur population,with blank frequency being lowered to 0.0064.The distribution of genotype frequencies met the law of Hardy-Weinberg equilibrium by hi-square test.The frequency data can be used in forensic and paternity tests to estimate the frequency of a DNA profile in the Uygur population,transplant matching and anthropology.     

开发SSR引物方法之研究动态

SSR标记是一种基于DNA长度多态性的分子标记技术,是进行群体遗传结构分析、构建遗传连锁图谱非常有效的工具。由于SSR标记是特异引物标记,必须在知道某个物种DNA序列的前提下,才能设计引物进行PCR扩增,故而存在一个引物开发的问题。从SSR标记的发展历程来看,开发SSR引物的方法有经典的构建与筛选基因组文库的方法、微卫星富集法、省略筛库法和数据库搜索法等四种。本文综述了这四种方法的操作流程及其在实际应用中的优缺点,并对近年来SSR引物在相近的物种间转移使用的情况作了介绍. Abstract: SSRs is one of molecular markers technology based on DNA length polymorphism and an efficient tool for population genetic studies and primary genetic linkage maps construction. Because of a special primer marker, It’s necessary to know a species DNA sequence in order to design primers for PCR testing. That is to say, there is a problem of SSR primer development. For the progress of SSR marker technology, the methods of developing SSR primer could be divided into four kinds: traditional constructing and screening genome library procedure, the SSR richment procedure, avoiding screening genome library procedure and database search procedure. This paper reviewed these four methods’operation processes and their advantages and disadvantages. In addition, transferability of SSR primers in closely related species were introduced in recent years.     

Polymorphism of heart fatty acid-binding protein gene associatied with fatness traits in the chicken

Fatty acid-binding proteins (FABP) belong to a superfamily of lipid binding proteins that exhibit a high affinity for long chain fatty acids and appear to function in metabolism and intracellular transportation of lipids. The current study was designed to investigate the effects of heart (H)-FABP gene on chicken growth and body composition traits. The Northeast Agricultural University divergent broiler lines for abdominal fat and a broiler X silkie F2 population were used in this study. Body weight and body composition traits were measured in the populations. Primers were designed according to the chicken H-FABP gene sequence. Polymorphisms between parental lines were detected by DNA sequencing. PCR-RFLP and PCR-fragment length polymorphism methods were developed to genotype the populations. The results showed that the H-FABP gene polymorphisms in the two populations were associated with abdominal fat percentage. It implied that H-FABP gene can be a candidate locus or linked to a major gene(s) that affects abdominal fat content in the chicken.     

Polymorphism of Heart Fatty Acid-Binding Protein Gene Associatied with Fatness Traits in the Chicken

Fatty acid-binding proteins (FABP) belong to a superfamily of lipid binding proteins that exhibit a high affinity for long chain fatty acids and appear to function in metabolism and intracellular transportation of lipids. The current study was designed to investigate the effects of heart (H)-FABP gene on chicken growth and body composition traits. The Northeast Agricultural University divergent broiler lines for abdominal fat and a broiler X silkie F₂ population were used in this study. Body weight and body composition traits were measured in the populations. Primers were designed according to the chicken H-FABP gene sequence. Polymorphisms between parental lines were detected by DNA sequencing. PCR-RFLP and PCR-fragment length polymorphism methods were developed to genotype the populations. The results showed that the H-FABP gene polymorphisms in the two populations were associated with abdominal fat percentage. It implied that H-FABP gene can be a candidate locus or linked to a major gene(s) that affects abdominal fat content in the chicken.     

Mapping the <Emphasis Type="Italic">Fas</Emphasis> locus controlling stearic acid content in soybean

Increasing the stearic acid content to improve soybean [ Glycine max (L) Merr] oil quality is a desirable breeding objective for food-processing applications. Although a saturated fatty acid, stearic acid has been shown to reduce total levels of blood cholesterol and offers the potential for the production of solid fat products (such as margarine) without hydrogenation. This would result in the reduction of the level of trans fat in food products and alleviate some current health concerns. A segregating F(2) population was developed from the cross between Dare, a normal stearic acid content cultivar, and FAM94-41, a high stearic acid content line. This population was used to assess linkage between the Fas locus and simple sequence repeat (SSR) markers. Three SSR markers, Satt070, Satt474 and Satt556, were identified to be associated with stearic acid (P < 0.0001, r(2) > 0.61). A linkage map consisting of the three SSR markers and the Fas locus was then constructed in map order, Fas, Satt070, Satt474 and Satt556, with a LOD score of 3.0. Identification of these markers may be useful in molecular marker-assisted breeding programs targeting modifications in soybean fatty acids.     

Introgression of the avian naked neck gene assisted by DNA fingerprints

Theoretical predictions suggest that DNA markers can be useful tools for genomic selection in gene introgression programmes. An experiment was carried out to evaluate the efficiency of using multi-locus DNA markers in an introgression programme designed to transfer the naked neck gene from a donor to a recipient chicken line. The donor line was a commercial egg layer chicken stock heterozygous at the naked neck locus (Na/na⁺), while the recipients were from a Cornish broiler line. These two lines differ markedly in their average body weight, a quantitative trait that can also represent the comprehensive differences between the genomes of the two lines involved. Three groups of naked neck BC₁ individuals were selected according to the following criteria: (i) low band-sharing with their donor grandsires evaluated by multi-locus DNA markers, (ii) high body weight at six weeks of age, and (iii) selection at random as a control group. Birds from each of these groups were mated at random to individuals from the heavier Cornish line to produce three groups of BC₂ individuals whose body weights were recorded weekly from three to seven weeks of age. Results indicated that BC₂ birds obtained from BC₁ parents selected for band-sharing levels and those selected for body weight, performed equally well at 4–7 weeks of age; both were 3.1–3.9% heavier than birds from the randomly selected group. The additional genome recovery of the heavier broiler line, obtained by DNA markers, was found to be in agreement with theoretically predicted values.     

Heritable alterations at the adenine phosphoribosyltransferase (APRT) locus in human lymphoblastoid cell lines.

Human lymphoblastoid cell lines derived from WI-L2 exhibit unexpected frequencies of diaminopurine (DAP) resistant mutants. The background mutant fractions of 10(-7) to 10(-8) in untreated cultures are much lower than the frequencies expected for loss of a heterozygous autosomal locus (10(-5) to 10(-6), yet much higher than expected for a homozygous locus (10(-10) to 10(-12). We used aminopterin, adenine and thymidine (AAT) to select DAP-sensitive (DAPS) revertants from one resistant line. The background frequency of DAPR in these revertant cell lines ranged from 3.5 to 6.5 x 10(-4), approximately the square root of 10(-7). Thus these data suggest that both alleles of aprt are inactivated at similarly high frequencies. They also indicate that the DAPS revertants were heterozygotes (aprt +/-) or hemizygotes (aprt +/0) and that WI-L2 was homozygous (aprt+/+). Mutational dose-response studies with X-rays, ethyl methanesulfonate (EMS), and ICR-191 were conducted in 4 of these revertant cell lines. EMS and ICR-191, which induce mainly point mutations, did not induce an increase in mutant fraction. A dose of 200 cGy X-rays, however, induced a frequency of 10(-3). Treatment of DAPR cells with 5-azacytidine induced a significant increase in reversion to DAPS. Southern blot analysis of the aprt gene after digestion with MspI or HpaII also suggests that differential methylation changes may play a major role in the generation of DAP sensitivity and resistance.     

Leptin downregulates heat shock protein-70 (HSP-70) gene expression in chicken liver and hypothalamus

Heat shock protein (HSP)-70 is expressed in normal and stressed cells but is highly stress-inducible. Although leptin has long been suggested to be involved in the regulation of stress response, its interaction with the HSP-70 gene is still unknown, under both unstressed and stressed conditions. The present study has aimed to investigate the effect of leptin on HSP-70 gene expression in normal chicken liver, hypothalamus, and muscle. Continuous infusion of recombinant chicken leptin (8 μg/kg per hour) at a constant rate of 3 ml/h for 6 h in 3-week-old broiler chickens significantly (P < 0.05) decreased food intake and HSP-70 mRNA levels in liver and hypothalamus, but not in muscle. In an attempt to discriminate between the effect of leptin and of leptin-reduced food intake on HSP-70 gene expression, we also evaluated the effect of food deprivation on the same cellular responses in two broiler chicken lines genetically selected for low (LL) or high (FL) abdominal fat pad size. Food deprivation for 16 h did not affect HSP-70 gene expression in any of the studied tissues indicating that the effect of leptin was independent of the inhibition of food intake. Regardless of the nutritional status, HSP-70 mRNA levels were significantly (P < 0.05) higher in the hypothalamus of FL compared with LL chickens consistent with higher mRNA levels for hypothalamic corticotropin-releasing factor. To assess, whether the effects of leptin were direct or indirect, we carried out in vitro studies. Leptin treatments did not affect HSP-70 mRNA levels in a leghorn male hepatoma cell line or quail myoblast cell line suggesting that the effect of leptin on HSP-70 gene expression is mediated through the central nervous system. Furthermore, HSP-70 gene expression was gender-dependent with significantly (P < 0.05) higher levels in male than in female chickens. This work was supported by a research grant (G.0402.05) from the FWO-Flanders (Belgium). No conflicts of interest would prejudice impartiality.     

Patterns of ribosomal gene variation in elite commercial chicken pure line populations

The nucleolus organizer region (NOR) encodes the tandemly repeated 18S, 5.8S and 28S ribosomal (r) RNA genes. The NORs of broiler and layer commercial chicken pure lines were studied to establish the type and extent of genetic variation at this important locus. The parameters studied were gene copy number, repeat size, and diversity of NOR-types. The populations were organized into three groups for analysis including brown-egg broiler (13 lines), brown-egg layer (six lines), and white-egg layer (eight lines). The ribosomal gene copy number average of the white-egg layer populations was significantly lower (329 genes) than that of the brown-egg layers (372 genes); the brown-egg broiler ribosomal gene average was intermediate (350 genes). The white-egg layer populations exhibited a ribosomal repeat unit average size of 36 kb, significantly different from the brown-egg layer and brown-egg broiler average repeat unit size of 32.5 and 33.9 kb, respectively. NOR array size was similar among the three groups (6 mb). The brown-egg broiler populations exhibited polymorphic NOR patterns, intra- and interline, whereas the white-egg layer populations were essentially monomorphic for NOR-type; brown-egg layers exhibited an intermediate level of NOR diversity. Some NOR array characteristics may be a function of breed origin as brown-egg commercial populations, both broilers and layers, have similar breed origins and exhibited similarities for predominant repeat unit size as compared with white-egg layer populations. However, the finding that brown-egg broiler lines typically exhibit a greater number of segregating NOR-types than brown-egg layer lines suggests that the selection schemes of broiler vs. layer pure line populations may also have influenced the degree of variation at this gene complex.     

A-FABP基因多态性与肉鸡生长和体组成性状的关联

为探讨A-FABP基因多态性对肉鸡生长和体组成性状的影响,文章选用肉鸡高、低脂双向选择品系第十世代肉仔鸡为实验材料,采用测序、PCR-RFLP、PCR-LP、DHPLC方法进行基因多态性检测和个体基因型分析,通过对8个SNPs进行连锁不平衡分析并选择5个标签SNPs构建单倍型,进而利用单位点和单倍型分别与鸡生长和体组成性状进行关联分析。结果表明,7个SNPs(除SNP 5以外)及单倍型同时对鸡肌胃重、肌胃率有显著影响(P<0.05),而对生长和其他体组成性状无显著影响(P>0.05)。鉴于不同物种A-FABP基因现有的功能研究均没有发现其对消化系统有重要作用,因此该基因是否为影响肉鸡肌胃重和肌胃率的主效基因还有待于进一步研究。     

QTL analysis for resistance to bacterial wilt (Burkholderia caryophylli) in carnation (Dianthus caryophyllus) using an SSR-based genetic linkage map

Bacterial wilt (Burkholderia caryophylli (Burkholder) Yabuuchi et al.) is one of the most damaging diseases during carnation (Dianthus caryophyllus L.) cultivation in Japan. To find molecular markers for use in marker-assisted selection, we constructed a simple sequence repeat (SSR)-based genetic linkage map of carnation using an F₂ population of 90 plants derived from a cross between a highly resistant line (85-11) and a susceptible cultivar (Pretty Favvare). To develop a large number of SSR markers, we constructed four new SSR-enriched genomic libraries and conducted expressed sequence tag analysis. We mapped 178 SSR loci into 16 linkage groups. The map covered 843.6?cM, with an average distance of 6.5?cM between two loci. This is the first report of a genetic linkage map based mainly on SSR markers in the genus Dianthus. Quantitative trait locus (QTL) analysis identified one locus for resistance to bacterial wilt in linkage group (LG) B4. The locus explained 63.0% of the phenotypic variance for resistance to bacterial wilt. The SSR markers CES1161 and CES2643 that were closest to the QTL were efficient markers for selecting lines with resistance derived from line 85-11. A positional comparison using SSR markers as anchor loci revealed that LG B4 corresponded to LG A6 in a previously constructed map. We found that the position of the resistance locus derived from line 85-11 was similar to that of the major resistance locus observed for a highly resistant wild species, Dianthus capitatus ssp. andrzejowskianus.