染色体作图

1　基本原理人类对各种生物基因组的研究,无论是研究其结构,还是探讨其功能,都需要确定DNA序列在染色体上的位置,因此,遗传标记在染色体上的定位,即染色体作图是基因组学研究开展的基础。20世纪早期。Morgan以果蝇为研究材料发现了基因连锁规律,自此基因作图的工作才真正开始。基因连锁分析的原理为在某一群体中,位于同一条染色体上的两个位点在减数分裂过程中随同源染色体配对而发生重组。重组率(r)则与两个位点在染色体上的遗传距离(M)具有函数关系(见公式1、2)。1Haldre公式:M=-1n(1-2r)2　　r=1-e-2M22Kosambi公式:M=1n(1 2r1-2r)·…     

通过图像分析方法作出的薏苡定量染色体图

薏苡染色体数目为2n=20,由于中期染色体的长度差异不大,相邻染色体难以区分,而薏苡前中期的染色体相对较长,经DAPI染料染色后染色体上显示明显不同的深染区和浅染区,深染区和浅染区分别相当于染色体上染色质纤维较浓缩和较伸展的区域。前中期染色体上染色深浅不一的染色区可以作为识别薏苡特定染色体的重要标志,也可用于辨别同源染色体。用MetaMorph软件定量分析了薏苡每条前中期染色体上(从短臂到长臂)DAPl信号强度的变化,结合染色体的长度和臂比作为辅助参数,构建了薏苡前中期染色体的定量染色体图。该定量染色体图不仅描述了每条染色体不同区域浓缩程度的不同,而且也反应出不同浓缩区域所占染色体长度的比例。因此该定量染色体图是实际的前中期染色体的一种直观模式,可作为识别薏苡基因组中每条染色体的有力依据。     

科学史视角下"基因在染色体上"的探索过程

摩尔根(Morgan)的红眼、白眼果蝇杂交实验为基因在染色体上提供了实验证据,但并不能完全让人信服.通过梳理科学史上"基因在染色体上"的探究历程,呈现了摩尔根和斯特提文特(Sturtevant)、布里吉斯(Bridges)、杜布赞斯基(Dobzhansky)、佩因特(Painter)等学者在不同角度上的探究成果,以越来...     

中国家猪染色体高分辨G带模式图：—成都会议录（1991年11月）

1976年在英国召开的第一届家畜染色体带型标准化国际会议(Reading会议)上,首次提出了家猪G带模式图.1984年在第六届欧洲家畜细胞遗传学讨论会上,成立了家猪核型标准化委员会.1988年,Gustavsson作为协调者发表了该委员会确定的家猪G带、R带标准化核型.我国家猪染色体显带研究始于1979年(陈文元等),截止现在国内至少有8个单位发表了20多篇论文,涉及21个中国家猪品种和3个国外家猪品种,其中高分辨G带核     

玉米粗线期染色体的高分辨率染色粒图

经温和固定和展片的玉米小孢子母细胞减数分裂的粗线期染色体,在电镜下,着丝粒和大量的电子致密的染色粒清晰可辨。其数量和位置自减数分裂早偶线期至早双线期是稳定和可重复的。为此,我们对粗线期的10条双价体中各条分别进行详细的染色粒分析,构建了一个完整的染色体组的染色粒图。总共识别和定位了达430±12(根据7套染色体组计数平均)染色粒。染色粒图可用于确定原位杂交法定位基因的详细分布区域,染色体重排中断点的定位,识别外源单价体和由于不联会或脱联会而产生的单价体等。     

2678例病人外周血染色体分析Analysis of peripheral Chromosome Examinatiion of 2678 Cases

AnalysisofPeriphcralChromosomeExaminationof2678CasesLiYanhuiSunYanyuZhengJun(TheFirstAffiliatedHospital,DalianMedicalCollege,Liaoning116011)1981－1991年,我室采用人体外周血常规培养和G显带方法,共对2678例各类病人进行了染色体检查。每例计数30个细胞,有异常改变者计数100个细胞,分析核型3个,个别加做其他带型及高分辨显带。就诊对象中流产、死胎、分娩畸型儿者占31．4％,原发及继发闭经者占13．3％,妇科肿瘤者占11．61％;智力低下及两性畸型各占6．65％和3．55％,其他为不育、先天聋哑、婚检对象等。2678例…     

From free chromatin analysis to high resolution fiber FISH

Fluorescentinsituhybridization(FISH)methodologyisoneofthemostpowerfulandversatileexperimentalsystemsforcurrentbiology.Itbridgesthemolecularbiologyandcytologybyprovidingdirectandpreciseresearchtoolsforgenemapping,chromosomalstructurestudyandgenomeanalysis[1].OnemajorbreakthroughforFISHanalysis,istheintroductionoftheconceptandmethodologiesofhighresolutionfiberFISH[2,3].ByFISHdetectingonreleased,lesscondensed,andlinearizedchromatinorDNAfibers,theultrahighresolutionmappingdatacanbegenerate…     

Effects of Nitrogen Source and Bacterial Elicitor on Isoflavone Accumulation in Root Cultures of Albizzia kalkora （Roxb.） Prain

Changes in cellular isoflavone （daidzein and genistein） contents were monitored in root cultures of Albizzia kalkora （Roxb.） Prain after feeding different ratios of NH4^＋/NO3^- and treatment with a biotic elicitor （three strains of Rhizobium sp.）. The NH4^＋/NO3^- ratio appears to be positively correlated with daidzein content in the roots and shows a negative correlation with genistein. Among the three different strains of Rhizobium used, the strain ATCC 15834 caused a 35% increase in daidzein production by infection. In the case of genistein, maximum production （94%） was obtained when cultures were treated on Day 6 by the strains ATCC 15834 and KCTC 1541. The biosynthetic pathway of the two isoflavones apparently reacts differently to the same culture conditions and the same strains of Rhizobium. Therefore, the present data suggest that the production of daidzein and genistein could be modulated by changing the NH4^＋/NO3^- ratio and the application of Rhizobium.     

Complete mitochondrial genome of Oxya chinensis （Orthoptera, Acridoidea）

The complete sequence of Oxya chinensis （0. chinensis） mitochondrial genome is reported here. It is 15,443 bp in length and contains 75.9% A＋T. The protein-coding genes have a similar A＋T content （75.2%）. The initiation codon of the cytochrome oxidase subunit I gene in the mitochondrial genome of O. chinensis appears to be ATC, instead of the tetranucleotides that have been reported in Locusta migratoria （L migratoria） mitochondrial genome. The sizes of the large and small ribosomal RNA genes are 1319 and 850 bp, respectively. The transfer RNA genes have been modeled and showed strong resemblance to the dipteran transfer RNAs, and all anticodons are identical to those of dipteran. The A＋T-rich region is 562 bp, shorter than that of other known Orthoptera insects. The six conserved domains were identified within the A＋T-rich region by comparing its sequence with those of other grasshoppers. The result of phylogenetic analysis based on the dataset containing 12 concatenated protein sequences confirms the close relation-ship of O. chinensis with L migratoria.     

兴义维蚋多线染色体研究（英文）

首次在国内对兴义维蚋Simulium (Wilhelmia) xingyiense的多线染色体进行研究, 并提供其多线染色体标准图。选取兴义维蚋的成熟幼虫, 用改良苯酚品红染色法进行唾腺多线染色体制备, 并进行测量、 描述及分析。结果表明： 兴义维蚋多线染色体数目为3对（2n=6）。Ⅰ号染色体具中央着丝粒, Ⅱ和Ⅲ号染色体均为亚中央着丝粒染色体。核仁组织者区位于Ⅰ号染色体短臂近着丝粒端。巴尔比尼氏环和双泡位于Ⅱ号染色体短臂近中央位置。3对染色体的着丝粒区可形成明显的染色中心。兴义维蚋多线染色体具有多态性的倒位, 倒位频率为0.64。兴义维蚋多线染色体的着丝粒、 核仁组织区、 巴氏环、 双泡等主要特征性结构的位置及形态恒定一致,可作为该种的重要鉴别特征。其多态性的倒位可为该蚋种在细胞水平上进行蚋类分类鉴别和系统发育等研究提供基础资料。     

脂肪细胞分化差异表达基因与其染色体所在遗传图位置的相关性分析

在脂肪细胞分化过程中,有约1／3表达的基因被诱导或抑制。通过分析3T3－L1脂肪细胞分化差异表达基因在染色体遗传图上的位置,对共同表达诱导或抑制的基因群体的调控与它们在染色体遗传图上的位置分布的关系进行分析。结果显示这些共同调控的基因除拥有共同的转录调控因子外,未发现在染色体的位置上和它们的共同调控有相关性。     

Construction of a full bacterial artificial chromosome （BAC） library of Oryza sativa genome

We have constructed a full BAC library for the superior early indica variety of Oryza sativa,Guang Lu Ai 4.The MAX Efficiency DH10B with increased stability of inserts was used as BAC host cells.The potent pBelo BACII with double selection markers was used as cloning vector.The cloning efficiency we have reached was as high as 98%,and the transformation efficiency was raised up to 10^6 transformants/μg of large fragment DNA.The BAC recombinant transformants were picked at random and analyzed for the size of inserts,which turned out to be of 120 kb in length on average.We have obtained more than 20,000 such BAC clones.According to conventional probability equation,they covered the entire rice genome of 420,000 kb in length.The entire length of inserts of the library obtained has the 5-to 6-fold coverage of the genome.To our knowledge,this is the first reported full BAC library for a complex genome.     

Preparation and analysis of spermatocyte meiotic pachytene bivalents of pigs for gene mapping

Well-spread meiotic pachytene bivalents were obtained by using the prolonged hypotonic treatment com-bined with high chloroform Carnory’s fixative solution from cells of the testes of domestic pigs. Comparison in the division index and length of pachytene bivalents with metaphase chromosomes showed that those of the former are 5 times higher and 3.42(1.87-5.98) times longer than those of the latter. Comparative studies on chromomere maps of bivalents and mitotic chromosomal G-bands were conducted by using the chromo-some 12 as a example. Sex vesicle and various shapes of synaptic sex chromosomes have been observed.Two-color PRimed IN Situ (PRINS) labeling has been conducted successfully on pachytene bivalents of pigs.     

水稻BAC在玉米有丝分裂染色体上FISH杂交体系的构建

 以水稻细菌人工染色体(BAC)为探针在玉米有丝分裂的细胞学制片上进行荧光原位杂交(FISH),探讨玉米基因组C_ot DNA对BAC探针重复序列的封阻、杂交后洗脱的严谨度、杂交液中FAD的浓度变化、水稻BAC探针的特异性重复序列的封阻对FISH杂交信号特异性的影响.初步形成了一套以水稻BAC探针在玉米有丝分裂染色体上进行BAC-FISH杂交的优化技术体系.研究结果表明：使用玉米基因组C_ot DNA来封阻水稻BAC探针的重复序列玉米基因组C _ot DNA的C_ot值应小于50,同时还需根据不同探针调整C_ot DNA的C_ot值及与探针的比例;而降低杂交液中FAD浓度和适度控制杂交后洗脱的严谨度,尤其是使用水稻BAC探针本身特异的重复序列的封阻对BAC-FISH杂交信号特异性的改善具有较好的效果.     

Construction, Characterization, and Chromosomal Mapping of a Fosmid Library of the White-Cheeked Gibbon （Nomascus leucogenys）

Gibbons have experienced extensive karyotype rearrangements during evolution and represent an ideal model for studying the underlying molecular mechanism of evolutionary chromosomal rearrangements. It is anticipated that the cloning and sequence characterization of evolutionary chromosomal breakpoints will provide vital insights into the molecular force that has driven such a radical karyotype reshuffle in gibbons. We constructed and characterized a high-quality fosmid li- brary of the white-cheeked gibbon (Nomascus leucogenys) containing 192,000 non- redundant clones with an average insert size of 38 kb and 2.5-fold genome coverage. By end sequencing of 100 randomly selected fosmid clones, we generated 196 se- quence tags for the library. These end-sequenced fosmid clones were then mapped onto the chromosomes of the white-cheeked gibbon by fluorescence in situ hy- bridization, and no spurious chimeric clone was detected. BLAST search against the human genome showed a good correlation between the number of hit clones and the number of chromosomes, an indication of unbiased chromosomal distribu- tion of the fosmid library. The chromosomal distribution of the mapped clones is also consistent with the BLAST search result against human and white-cheeked gibbon genomes. The fosmid library and the mapped clones will serve as a valu- able resource for further studying gibbons' chromosomal rearrangements and the underlying molecular mechanism as well as for comparative genomic study in the lesser apes.