微卫星座位与丝羽乌骨鸡蛋用系开产性状相关分析

采用多重PCR扩增结合荧光标记全自动电泳检测技术, 对鸡基因组1号染色体和Z染色体上20个微卫星座位与丝羽乌骨鸡BM、BF两个蛋用新品系180个个体的开产性状进行相关性分析。结果表明: 位于1号染色体上的MCW0068、MCW0200与开产蛋重相关显著(P<0.05); 位于1号染色体上的MCW0068、MCW0208和位于Z染色体上的MCW0128与开产体重相关显著(P<0.05); 而位于Z染色体上的MCW0154与开产体重相关极显著(P<0.01)。     

鲤鱼微卫星标记与体重、体长和体高性状的相关分析

利用47个鲤鱼微卫星标记, 对柏氏鲤和荷包红鲤抗寒品系自交F2代的92个个体基因组DNA进行检测, 得到162个等位基因, 各座位等位基因数2~6个, 片段长度100~444 bp, 有效等位基因数1.3069~4.2288, 杂合度0.2361~0.7677, 位点多态信息含量0.5368。利用统计软件SPSS的GLM程序对47个微卫星标记与鲤鱼体重、体长和体高相关性进行了分析, 结果表明HLJ695、HLJ716、HLJ739、HLJ759、HLJ774、K16与体重、体长和体高相关, HLJ776与体高相关。对同一标记不同基因型间进行多重比较, 找到与3种性状相关的基因型。     

山西瘦肉型猪(SD-Ⅲ系)基因组DNA的AFLP检测研究

用分子标记AFLP对山西瘦肉型猪(SDⅢ-系)进行纯度检测,旨在为评价该猪种的遗传特性提供相关参数。实验共用8条引物,对25头猪进行了基因组DNA的分析,共获得171个AFLP标记,单引物获得的标记数在3个~15个之间,群体相似系数为0.928(0.892~0.978);遗传距离为0.072(0.022~0.108)。结果表明:AFLP适宜于基因组DNA遗传结构检测;SDⅢ-系猪纯度较高。     

高产王浆西蜂DNA分子中的相关基因标志筛选及其鉴定

为了探讨西蜂与高产王浆相关特异基因标记 ,用 12种随机引物 (P1～P12 )对产王浆量不同的4品系西蜂的基因组DNA进行了RAPD PCR分析 ,分别获得了产王浆量高、低不同西蜂的DNA多态性图谱 ,并从P2 引物的DNA多态性图谱中筛选出一差异DNA片段P2 316bp .将P2 316bp差异DNA片段用地高辛标记制备成探针 ,进行Southern杂交鉴定 .实验显示 ,探针与高产王浆西蜂基因组DNA的扩增产物出现了阳性杂交信号 ,而与低产王浆西蜂基因组DNA的扩增产物未出现阳性杂交信号 .结果表明 ,该差异性基因片段P2 316bp是西蜂高产王浆优良性状相关的遗传标记 ,序列为 30 5个核苷酸 .     

镜鲤体重的QTL定位

本研究利用217个微卫星标记和336个SNPs标记对德国镜鲤F2代68个个体基因组DNA进行基因型检测.其中507个标记共组成62个连锁群,覆盖基因组总长度为2 805.85 cM,标记间平均距离为6.31 cM;利用软件MapQTL 4.0采用区间作图法对体重性状进行QTL定位分析.研究结果共检测到14个与体重性状有关的QTLs,分布于9个连锁群.其中BW-5-1有最大的LOD值,为4.46;BW-1-1的LOD值最小,为2.25.单个QTL平均解释表型变异介于14.10%~45.50%之间,其中贡献率大于20%的主效QTLs有9个.通过BLASTX与斑马鱼蛋白质序列数据库进行序列比对,找到了与斑马鱼酰基辅酶A脱氢酶蛋白、胰淀粉酶α2蛋白、Apoeb protein和甘油醛-3-磷酸脱氢酶蛋白同源的分子标记.本研究结果对分子标记辅助育种具有重要应用价值.     

京海黄鸡体重性状全基因组关联分析

体重性状是肉鸡重要的经济性状。为了寻找可用于京海黄鸡体重性状遗传改良的分子标记及候选基因,本文以400只京海黄鸡核心群母鸡为基础,测定了0~14周龄体重,利用简化基因组测序技术(Specific-locus amplified fragment sequencing, SLAF-seq)对京海黄鸡体重性状进行全基因组关联研究(Genome-wide association stndy, GWAS),筛选与京海黄鸡体重性状相关的SNPs位点。结果共检测到100个与京海黄鸡体重相关的SNPs位点,其中15个位点效应达到全基因组显著水平(P<1.87E-06),85个位点效应达到全基因组潜在显著水平(P<3.73E-05)。通过筛选每个显著SNP周围1 Mb区域内的基因,共找到9个可能的候选基因,其中FAM124A(Family with sequence similarity 124A)、QDPR(Quinoid dihydropteridine reductase)、WDR1(WD repeat domain 1)和SLC2A9(Solute carrier family 2 (facilitated glucose transporter), member 9) 4个基因可能是影响体重性状的重要候选基因。同时还发现,4号染色体75.6~80.7 Mb区域集中了大部分与京海黄鸡中后期体重性状显著相关的SNPs位点,该区域可能是影响京海黄鸡中后期生长体重的重要候选区域。     

水稻双单倍体群体的分子标记图示基因型分析

利用窄叶青８号（籼稻）／京系１７（粳稻）花培产生的双单倍体群体建立了一个包含１６０个分子标记的遗传连锁图,在此基础上利用ＨＹＰＥＲＧＥＮＥ软件建立了５２个ＤＨ系的图示基因型,并对ＤＨ系的亲本基因组比率和染色体的交换重组频率进行了比较分析。结果表明本实验所用的ＤＨ群体没有显著偏离正态分布,籼粳稻杂交后代中植株的籼粳表现与同工酶、形态指数和基因组比率的分析结果一致,此外还发现ＤＨ群体中出现了大量的交换罕见染色体。利用图示基因型分析发现株高和分子标记ＲＺ９７８和ＲＧ４Ａ相关,生育期和ＲＲＫ０８－１、ＲＧ４７７和ＲＧ５１１相关。本文还就图示基因型分析技术在ＤＨ群体的遗传分析和选择育种中的应用进行了讨论．     

水稻DH群体的分子连锁图谱及基因组分析

利用扩大的籼粳杂交来源（窄叶青８号×京系１７）的水稻（ＯｒｙｚａｓａｔｉｖａＬ．）加倍单倍体（ＤＨ）群体,构建了包含４４４个位点的分子连锁图谱,覆盖水稻基因组１９６２ｃＭ（ｃｅｎｔｉＭｏｒｇｏｎ）,标记间的平均图距小于５ｃＭ。此图谱包括２７６个ＲＦＬＰ标记、３４个ＲＡＰＤ标记、８９个微卫星标记、１０个ＡＦＬＰ标记、２６个端粒重复相关序列（ＴＡＳ）标记以及９个同工酶标记。该遗传图谱与其它的水稻高密度遗传图谱具有较高的可比性,并有自己的特点,适于进行各种持续性的遗传学研究     

玉米花期耐旱导入系群体的构建与评价

以黄早四X齐319回交群体（BC2F1）为试验材料,在花期进行高强度干旱胁迫和耐旱导入系筛选,获得花期耐旱性显著高于亲本材料的玉米耐旱导入系。利用分子标记对其导入片段进行分析结果表明,在全基因组范围内,耐旱群体在36．59％的位点上含有供体亲本的特异标记,尤其在第4、5染色体上分别达到63．94％、56％,显著高于群体平均值;同时发现,导入频率的提高主要集中于染色体的部分区段,其中部分基因组区域与已定位的耐旱性相关QTL相邻或重叠。     

利用RFLP标记分析一对水稻籼粳交双单倍体的基因型

对一对籼(Oryza sativa ssp.indica)粳(O.sativa ssp.japonica)(“圭630”/“02428”)杂种进行花药培养获得81个双单倍体(DH),构建了有233个RFLP标记的水稻遗传连锁图谱。对各DH系的“圭630”等位基因组频率及图示基因型进行了分析。结果表明,该DH群体的平均基因组频率为49％,各DH系分布在29.3％～78.6％之间,集中分布在44％～49％之间;有130个RFLP标记出现显著的偏分离,偏父本与偏母本分离的标记数基本相等;同向偏分离的标记常集中在一些染色体或染色体的某些区段;各染色体的平均基因组频率分布在29％～65％之间,出现明显的偏父或偏母分离;一些DH中出现其特征完全来于某一亲本的染色体,可能与这些染色体在减数分裂期的同源配对和交换有关。     

Use of a novel outbred by inbred F1 cross to detect genetic markers for growth

A unique outbred by inbred F1 resource population was established. The population structure facilitated the unique opportunity of examining gene by genetic background interaction through crossing two modern broiler sires with dams from two unrelated inbred lines, with no selection for growth rate, to produce about 600 F1 chicks. Pools of DNA were generated from the phenotypic extremes (20% high and low) for 8-week body weight for each of the four combinations of sire and dam line. For one sire family, pools were also separately generated for each sex. The pools were genoyped with 25 informative (segregating) microsatellites. This unique F1 cross between outbred and inbred populations allowed use of the inbred alleles as an 'internal control' for polymerase chain reaction amplification quality in DNA pools. Ten microsatellites showed marked differences (P < 0.05) in allele frequencies between high and low pools, suggesting an association between marker and quantitative trait loci (QTL). These differences were verified using selective genotyping. For many markers, differences in allele frequencies between the high and the low pools, or marker effect, varied between the two dam lines and the two sexes, suggesting an interaction between some genes and the genetic background as represented by different dam lines or sexes. The suggestive marker-QTL associations identified in this F1 population demonstrate the efficiency of this population design while different QTL effects in different genetic line crosses and sexes highlight the importance of gene by genetic background interaction in QTL detection.     

Study of interlocus interactions using a series of gene markers in samples from groups with different health status]

Interloci equilibrium between pairs of gene markers in the samples of different health rate in the population of Buryats of Chitinskaya Province was tested. The following methods were used: calculation of interloci correlation coefficients, chi 2-testing of the hypothesis of interloci equilibrium and the modification of principal components analysis on the basis of the matrix of Pearson's coefficients of contingency. In the groups of "extreme" health rate the tendency to increase in interloci disequilibrium was discovered. The reason for this effect is the increase in some phenotype combination frequencies that can be considered as markers of non-specific individual resistance in the environmental condition of the populations studied.     

Identification of chromosomal regions associated with growth and carcass traits in an F3 full sib intercross line originating from a cross of chicken lines divergently selected on body weight

An F₃ resource population originating from a cross between two divergently selected lines for high (D+ line) or low (D− line) body weight at 8-weeks of age (BW55) was generated and used for Quantitative Trait Locus (QTL) mapping. From an initial cross of two founder F₀ animals from D(+) and D(−) lines, progeny were randomly intercrossed over two generations following a full sib intercross line (FSIL) design. One hundred and seventy-five genome-wide polymorphic markers were employed in the DNA pooling and selective genotyping of F₃ to identify markers with significant effects on BW55. Fifty-three markers on GGA2, 5 and 11 were then genotyped in the whole F₃ population of 503 birds, where interval mapping with GridQTL software was employed. Eighteen QTL for body weight, carcass traits and some internal organ weights were identified. On GGA2, a comparison between 2-QTL vs. 1-QTL analysis revealed two separate QTL regions for body, feet, breast muscle and carcass weight. Given co-localization of QTL for some highly correlated traits, we concluded that there were 11 distinct QTL mapped. Four QTL localized to already mapped QTL from other studies, but seven QTL have not been previously reported and are hence novel and unique to our selection line. This study provides a low resolution QTL map for various traits and establishes a genetic resource for future fine-mapping and positional cloning in the advanced FSIL generations.     

An analysis of linkage disequilibrium in the interleukin-1 gene cluster, using a novel grouping method for multiallelic markers.

In population- and family-based association studies, it is useful to have some knowledge of the patterns of linkage disequilibrium that exist between markers in candidate regions. When such studies are carried out with multiallelic markers, it is often convenient to group the alleles into a biallelic system, for analysis. In this study, we specifically examined the interleukin-1 (IL-1) gene cluster on chromosome 2, a region containing candidates for many inflammatory and autoimmune disorders. Data were collected on eight markers, four of which were multiallelic. Using these data, we investigated the effect of three allele-grouping strategies, including a novel method, on the detection of linkage disequilibrium. The novel approach, termed the "delta method," measures the deviation from the expected haplotype frequencies under linkage equilibrium, for each allelic combination. This information is then used to group the alleles, in an attempt to avoid the grouping together of alleles at one locus that are in opposite disequilibrium with the same allele at the second locus. The estimate haplotype frequencies (EH) program was used to estimate haplotype frequencies and the disequilibrium measure. In our data it was found that the delta method compared well with the other two strategies. Using this method, we found that there was a reasonable correlation between disequilibrium and physical distance in the region (r=-.540, P=.001, one-tailed). We also identified a common, eight-locus haplotype of the IL-1 gene cluster.     

Evaluation of TFAM and FABP4 gene polymorphisms in three lines of Nellore cattle selected for growth

We analyzed the polymorphisms TFAM HaeIII, TFAM MboI and FABP4 MspA1I in three Nellore lines selected for growth in order to evaluate how selection affects the frequencies of these polymorphisms and evaluate their association with growth and carcass traits in Zebu cattle. Birth, weaning and yearling weights, rump height, longissimus muscle area, backfat thickness, and rump fat thickness were analyzed. The sample was constituted of animals from two lines selected for yearling weight (NeS and NeT), and a control line (NeC), established in 1980, at the S?o Paulo Instituto de Zootecnia. Two hundred and seventy-two heifers were genotyped for TFAM gene SNPs, and 325 heifers were genotyped for the FABP4 SNP. High frequencies were observed for the alleles A (TFAM HaeIII), C (TFAM MboI) and C (FABP4 MspA1I). Significant differences in allele frequencies between NeS and NeT were observed for the TFAM HaeIII, and between the line NeT and lines NeC and NeS for the FABP4 MspA1I SNP. Five haplotypes were observed for the two polymorphisms in the TFAM gene, haplotype AACC being the most frequent. None of the markers separately or according to haplotype was significantly associated with the growth and carcass traits. The low frequencies of alleles that are associated with high marbling scores and thick subcutaneous fat in taurine breeds might explain the low means for these traits in Nellore cattle.     

Post-natal sexual development of testis and epididymis in the rabbit: variability and relationships among macroscopic and microscopic markers

The present work was performed to examine the existence of some relationships between macroscopic and microscopic traits of testis and epididymis in rabbit. The variables studied were live weight (LW), testis length (TL), testis width (TWh), testis weight (TW), testis volume (TV), epididymis length (EL), epididymis width (EWh), epididymis weight (EW), epididymis volume (EV), percentage of seminiferous tubules with presence of lumen (STL), percentage of seminiferous tubules with presence of elongated spermatids (STES), percentage of seminiferous tubules with presence of spermatozoa (STS) and diameter of seminiferous tubules (STD). Measurements began after weaning and continued until males reached 33 weeks of age.Phenotypic correlations between testis and epidydimis traits and the principal component analysis were estimated as the residual correlation from an analysis of variance, including the effects of line, birth-season, age, and the double interactions line × age and birth-season × age.Four principal components (PCs) explained 79% of the total variation. The predominant variables defining the first PC were TL, TW and TV. Epididymis width and STS were located in the second PC. Epididymis weight and EV were important in the definition of the first and third PC. Tubular diameter seems important in the definition of the fourth PC.It has been not found correlation between traits related to either testis or epididymis size and variables related to active spermatogenesis. Therefore, TW and/or TV seemed not to be good markers of maturity.     

Quantitative trait loci affecting body weight and fatness from a mouse line selected for extreme high growth.

Quantitative trait loci (QTL) influencing body weight were mapped by linkage analysis in crosses between a high body weight selected line (DU6) and a control line (DUKs). The two mouse lines differ in body weight by 106% and in abdominal fat weight by 100% at 42 days. They were generated from the same base population and maintained as outbred colonies. Determination of line-specific allele frequencies at microsatellite markers spanning the genome indicated significant changes between the lines on 15 autosomes and the X chromosome. To confirm these effects, a QTL analysis was performed using structured F2 pedigrees derived from crosses of a single male from DU6 with a female from DUKs. QTL significant at the genome-wide level were mapped for body weight on chromosome 11; for abdominal fat weight on chromosomes 4, 11, and 13; for abdominal fat percentage on chromosomes 3 and 4; and for the weights of liver on chromosomes 4 and 11, of kidney on chromosomes 2 and 9, and of spleen on chromosome 11. The strong effect on body weight of the QTL on chromosome 11 was confirmed in three independent pedigrees. The effect was additive and independent of sex, accounting for 21-35% of the phenotypic variance of body weight within the corresponding F2 populations. The test for multiple QTL on chromosome 11 with combined data from all pedigrees indicated the segregation of two loci separated by 36 cM influencing body weight.     

Cytogenetic comparison of the sensitivity to mutagens in mice selected for high (HA) and low (LA) swim stress-induced analgesia

Sensitivity to mutagens was studied in mouse lines selectively bred for high analgesia (HA) and for low analgesia (LA) induced by 3-min swimming in 20 degrees C water. Apart from pain-related traits HA mice also manifest, as compared to the LA line, higher emotionality in various behavioural tests, and cope worse with the hypothermic challenge of swimming in cold water. In the present study HA mice appeared more susceptible to the mutagenic effect of whole-body gamma-radiation and mitomycin-C injection. Both treatments caused higher frequencies of chromosomal aberrations and micronucleus in bone marrow cells in the HA than in the LA line. The results are discussed in terms of a genetic correlation between animals' susceptibility to environmental stressors and the mechanism of mutagenesis. As shown by our recent molecular study, the selection for magnitude of swim analgesia has differentiated the parental outbred population into two distinct genotypes characterised by specific minisatellite and microsatellite sequences for each line, which may be genetic markers of particular traits. We conceive that the breeding strategy, along with the differentiation of stress-related phenomena, has altered the frequencies of genes controlling DNA repair in each line.     

Correlated genetic trends for production and welfare traits in a mouse population divergently selected for birth weight environmental variability

The objective of this work was to study the changes that, selecting for environmental variability of birth weight (BW), could bring to other interesting traits in livestock such as: survivability at weaning (SW), litter size (LS) and weaning weight (WW), their variability assessed from standard deviations of LS, standard deviation of WW (SDWW) and also the total litter weight at birth (TLBW) and total litter weight at weaning. Data were registered after eight generations of a divergent selection experiment for BW environmental variability in mice. Genetic parameters and phenotypic and genetic evolution were assessed using linear homoscedastic and heteroscedastic models in which the traits were attributed to the female, except BW and WW that were in some models also attributed to the pup. Genetic correlation between the trait and variability levels was −0.81 for LS and −0.33 for WW. Clear divergent phenotypic trends were observed between lines for LS, WW and SDWW. Although animals were heavier in the high line, TLBW and at weaning was greater in the low line. Despite the negative genetic correlation that was obtained, SDWW was also higher in the high line. Heritabilities were 0.21 and 0.06, respectively, for LS and SW. Both phenotypic and genetic trends showed clear superiority of the low line over the high line for these traits, but inferior for WW. Heteroscedastic model performed similar to the homoscedastic model when there was enough information. Considering LS and survival, the low line was preferred from a welfare point of view, but its superiority from the productivity perspective was not clear. Robustness seemed higher as shown by a low variation and having a benefit to the animal welfare, but this still remains unclear. It was concluded that low variation benefits the welfare of animals.     

Influence of genetic background and heterozygosity on meiotic recombination in Arabidopsis thaliana.

Plant breeding relies on genetic variability generated by meiotic recombination. Control of recombination frequencies is not yet possible, but would significantly extend the options for plant-breeding strategies. A prerequisite would be variability of recombination frequencies. In this study, 15 transgenic kanamycin (KR) and hygromycin (HR) resistance gene insertions mapping to the five Arabidopsis thaliana chromosomes were used as genetic markers. Recombination frequencies were determined from the frequencies of resistance phenotypes within populations segregating for linked KR and HR markers. Recombination frequencies of marker pairs were compared among these four ecotypes, among F1s in both reciprocal forms derived from these ecotypes, and between F1s and their parent lines. On average, the recombination frequencies in F1 crosses were substantially higher (up to 2-fold) than in the homozygous parental ecotypes. A strong negative correlation between genetic similarities of ecotypes and recombination frequencies was detected for two adjacent marker pairs located on the long arm of chromosome 3, but not for marker pairs in other genomic regions. Our results suggest that heterozygosity influences recombination in plant breeding, and cannot be ignored in genetic mapping of genomes.