几种中国野生菊的染色体组分析及亲缘关系初步研究

通过对不同倍性的几种中国野生菊之间杂种F1减数分裂期染色体的配对分析,对它们的亲缘关系和演化过程进行了研究。观察到甘菊(Dendranthema lavandulifolium)和菊花脑(D.nankingense)是两个亲缘关系较近、但已发生了某种程度分化的二倍体;南京野菊(D.indicum)和尖叶野菊(D.indicum var.acutum)是含有相同染色体组的异源四倍体,毛华菊(D.sestitum)为异源六倍体,它们在减数分裂中期Ⅰ,染色体均能较好地配成二价体构型。尖叶野菊(4x)与菊花脑(2x)、南京野菊(4x)与毛华菊(6x)的F1,染色体配对构型分别接近于9Ⅰ 9Ⅱ和9Ⅰ 18Ⅱ,表明菊花脑或其近缘种是尖叶野菊染色体组之一的供体,南京野菊或其近缘种是毛华菊两个染色体组的供体。本文还对这几种菊属植物的演化过程进行了讨论。     

Bacteriophage OP1, lytic for Xanthomonas oryzae pv. oryzae, changes its host range by duplication and deletion of the small domain in the deduced tail fiber gene

The entire genome of bacteriophage OP₁, lytic for Xanthomonas oryzae pv. oryzae causing bacterial leaf blight of rice, and the partial genomes of related phages were sequenced and analyzed. The OP₁ genome comprises double-stranded, 4785-bp long DNA with 51.1% G + C content. Fifty-nine open reading frames (ORFs) were detected. ORF25 had similarity with the tail fiber gene of phages, whose product is related to host specificity. The ORF25 regions were amplified from four host-range mutants (OP_1h, OP_1hC, OP_1h2, and OP_1h2C) by polymerase chain reaction, and their deduced amino acid sequences were compared. Three mutants (OP_1hC, OP_1h2, OP_1h2C) had duplications of a small domain in the N-terminal portion, although there were slight differences in the position of the duplicated sequences. One mutant OP_1h had substituted amino acids in the duplication region. New mutants isolated in the laboratory (OP_1hC and OP_1h2C from OP₁ and OP_1h2) acquired the ability to lyse strain N5874 belonging to phagovar (lysotype) C. However, they rapidly lost this lytic ability when incubated with other phagovars. This loss was always accompanied by a loss of the characteristic repeats, suggesting that the host range of OP₁-related phages changed mainly through duplication and deletion of a small domain in ORF25. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession numbers AP008979, AB214312 to AB214316     

Finding cardiovascular disease genes in the dog

Recent advances in canine genomics are changing the landscape of veterinary biology, and by default, veterinary medicine. No longer are clinicians locked into traditional methods of diagnoses and therapy. Rather, major advances in canine genetics and genomics from the past five years are now changing the way the veterinarian of the 21st century practices medicine. First, the availability of a dense genome map gives canine genetics a much-needed foothold in comparative medicine, allowing advances made in human and mouse genetics to be applied to companion animals. Second, the recently released 7.5× whole genome sequence of the dog is facilitating the identification of hereditary disease genes. Finally, development of genetic tools for rapid screening of families and populations at risk for inherited disease means that the cost of identifying and testing for disease loci will significantly decrease in coming years. Out of these advances will come major changes in companion animal diagnostics and therapy. Clinicians will be able to offer their clients genetic testing and counseling for a myriad of disorders. In this review we summarize recent findings in canine genomics and discuss their application to the study of canine cardiac health.     

Analysis of Genetic Diversity in Barley Cultivars Reveals Incongruence Between S-SAP,SNP and Pedigree Data

Accurate assessment of genetic similarity is important for plant breeding, germplasm enhancement and conservation of plant genetic resources. A comparative analysis of genome diversity among a group of six-rowed spring barley (Hordeum vulgare L.) cultivars was carried out using sequence-specific amplified polymorphism (S-SAP) and single nucleotide polymorphism (SNP), with the results compared to the kinship coefficients derived from the pedigree data. Mean pair-wise GS values were estimated to be 0.0957 ± 0.144 (Kinship), 0.491 ± 0.189 (SNPs), and 0.602 ± 0.098 (S-SAPs). S-SAP and SNP-based genetic similarity (GS) values were normally distributed but kinship values had a non-normal and skewed distribution. Pair-wise correlation of GS values were lowest for the S-SAP and the SNP matrices (r =; 0.040, p<0.230) and highest for the SNP and pedigree matrices (r =; 0.240, p < 0.001). Analysis of molecular variance (AMOVA) attributed about 90.4% of observed variation to the cultivars within each of the malting and feed groups. Variance component between malting and feed groups was 6.6% for both SNP and S-SAP data suggesting lack of a significant genetic differentiation along this agronomic division. The remaining 3% of variation was attributed to genetic diversity within cultivars. Although both DNA-based marker systems were able to differentiate all barley cultivars, significant difference were observed in the pattern of genetic relationships obtained by the two marker systems and the pedigree data.     

基于两类全基因组距离的EV71型病毒亲缘关系分析

[目的]了解世界各地EV71病毒的亲缘关系。[方法]下载了NCBI数据库所有EV71全基因组序列,以常用的Kimura 2-parameter距离和E距离进行距离矩阵邻接法建树。[结果]基于E距离和Kimura 2-parameter距离构建的进化树结果一致,2种方法均支持EV71进化树反映出的基于全基因组的病毒亲缘关系。[结论]E距离是病毒系统发育应用中另一种颇具潜力的新距离,能为鉴定EV71病毒亲缘关系提供支持。     

基因组学与蛋白质组学课程教学实践与体会

从构建完整的教学内容、灵活运用多种教学方法两方面探讨了基因组学与蛋白质学课程的教学改革。教学内容改革包括教材的合理选用、"宽口径、厚基础、重能力"教学内容的改革、教学内容的优化与更新,多种教学方法的运用包括多媒体与板书相结合、案例教学法、录像教学法、启发式教学法、网络教学法。     

大肠杆菌基因中密码对使用的规律

为了探讨基因组序列的非随机性对密码对使用的影响程度,揭示依赖上下文的密码对偏爱性(CDCB)可能存在的规律,本文主要对大肠杆菌基因组中密码子及其紧邻密码子(密码对)偏爱作了全面的统计分析。结果发现85%的密码子在其紧邻密码子位点有显著依赖上下文的密码对偏爱性,通过密码对与全序列六联体(三联体对)的相对丰度比较发现,大约35%的密码对偏好性不能用基因组的序列组分来解释。当密码子第二和第三位点核苷酸相同,且紧邻密码子相同时,它们的相对丰度有显著相关性。结果表明我们的数据支持依赖上下文的密码子偏好的主要原因是蛋白质合成精确性选择的假设,即本文结果揭示了依赖上下文的密码对偏好性可能存在的规律,从而为今后进一步研究大肠杆菌基因组中密码对使用偏好性提供参考。     

陆地棉与三裂棉、斯特提棉和A111种间杂种F1的形态与细胞学

本文研究了TM-1×三裂棉、江苏棉1号×斯特提棉、泗棉2号×Alll 3个种间杂种F_1的主要形态特征及花粉母细胞减数分裂中期Ⅰ的染色体行为。3个种间杂种F_1的花器官性状大多趋向于父本野生棉,如花冠颜色、花心等;营养器官大多趋向于中间型,如叶色、叶形等。杂种F_1均表现高度不育。减数分裂中期Ⅰ的染色体构型依次为:13.73Ⅰ 12.52Ⅱ 0.03Ⅲ 0.04Ⅳ,28.03Ⅰ 5.38Ⅱ 0.07Ⅲ和33.26Ⅰ 2.87Ⅱ;其染色体组亲和性指数分别为0.9715、0.4192和0.2208。这一结果表明:(1)陆地棉与三裂棉的亲缘关系较近,与斯特提棉的亲缘关系较远,与Alll的亲缘关系更远;(2)泅棉2号×Alll的F_1染色体数为2n=3x=39,其染色体数x=13与棉属相同,其次因Alll原产于澳大利亚,形态上与纳尔逊氏棉、澳洲棉比较接近,因此推测它可能属于棉属的C染色体组种。