人X染色体35cMYAC重叠群的构建及物理图谱分析

人Ｘ染色体Ｘｐ１１．２－ｐ２１．３区域具有重要的基础遗传学和医学遗传学意义。为了对该区段编码的基因,尤其是疾病基因进行克隆与变异研究,对该区段染色体ＤＮＡ进行了ＹＡＣ克隆并将其依染色体排序,采用了一系列ＤＮＡ位标,尤其是多肽性微卫星序列位标筛选了３个ＹＡＣ方库,得到了１５１个ＹＡＣ克隆,对这些ＹＡＣ克隆进行了物理图谱分析,构建了这一区域的一系列ＹＡＣ重叠群,这些ＹＡＣ重叠群的总跨度约３５摩,基本覆     

哺乳动物性别分化的调控

哺乳动物性别分化调控的分子机制的研究特别是性别分化的层次调控、剂量补偿和性染色体进化这三个领域,已取得快速进展。已经发现Ｙ染色体性别决定区基因（ＳＲＹ）、Ｘ染色体ＤＳＳ－ＡＨＣ决定区基因１（ＤＡＸ－１）、甾类生成因子１基因（ＳＦ１）和Ｗｉｌｍｓ瘤抑制基因（ＷＴ－１）等与哺乳动物性别决定有关。ＳＲＹ启动睾丸分化,但胚胎发育成雄性的其余步骤由事丸分泌的激素控制。ＤＡＸ－１且编码一种女性特异功能的蛋白质,它在男性中被ＳＲＹ所抑制。ＳＦ－１和ＷＴ－１在ＳＲＹ开启之前作用于性腺和肾上腺发育的启动。哺乳动物通过随机失活雌性两条Ｘ染色体中的一条来使Ｘ连锁的基因在两性间的表达水平达到平衡（剂量补偿）。Ｘ染色体失活由Ｘ染色体失活中心（ＸＩＣ）控制。失活的Ｘ染色体专一转录基因（ＸＩＳＴ）是ＸＩＣ的强烈候选者,它可能参与Ｘ失活的启动。对有袋目和单孔目动物性染色体的研究为我们提供了其进化的信息。有证据支持性染色体起源于一对同源常染色体,而ＳＲＹ的祖先基因可能是ＳＯＸ－３。     

点带石斑鱼染色体显带技术及其描绘研究(英文)

点带石斑鱼(Epinephelus malabaricus)属于鲈形目,科、石斑鱼亚科、石斑鱼属,是中国东南沿海暖水性礁栖的名贵海产经济鱼类。采用PHA活体注射结合秋水仙素培养,取点带石斑鱼全肾,低渗处理,空气干燥制片法制作染色体标本,利用Alu I限制性内切酶介导的原位切口平移显带技术,在点带石斑鱼有丝分裂中期染色体上诱导出带纹清晰、分散良好的多重带。结果显示,多数染色体显现出8—10条带纹,最少的一对染色体也有4条带纹,同源染色体带纹基本一致,在每对染色体上的数目及其分布具明显特征性且相对稳定,同时发现不同分裂相的同一号染色体上,特征带纹鲜明一致,带纹数目基本吻合,具有可重复性和可操作性;然后用人X和Y染色体文库特异DNA为探针,对点带石斑鱼的有丝分裂中期分裂相染色体进行了描绘研究。结果表明,点带石斑鱼染色体组中测出了人X染色体特异DNA同源片段的3个保守同线群,分别在点带石斑鱼的第7、第13和第22号同源染色体上,它们的杂交信号最近边距着丝粒的百分比距离分别大约为62.3%、43.4%及44.4%;人X染色质同源片段的大小约占点带石斑鱼基因组的4.63%。但用人Y染色体DNA描绘点带石斑鱼染色体时,没有检测出可见的同源片段。研究结果可以为从低等脊椎动物到人类性染色体的进化过程提供一种新的研究思路。     

新石器时代人骨遗骸中古代DNA的提取及X—Y染色体同源基因片段的PCR扩增

从中国新石器时代人骨遗骸中提取出古代ＤＮＡ。通过聚合酶链式反应技术扩增得到Ｘ－Ｙ染色体上的单考贝同源基因片段。由于扩增的基因片段长度具有性别多态性,从而为古代人骨和牙齿提供了分子生物学的性别鉴定。     

我国东北地区3个群体DYS390多态位点的遗传学研究

研究中国群体Ｙ染色体微卫星位点ＤＹＳ３９０遗传多态性,可以用于追溯人类进化 上的父系祖先,也可以为人类基因组和法医学等研究积累数据。方法 采用ＰＣＲ技术扩增微卫星ＤＮＡ片段,再经变性凝胶电泳及银染方法,对我国东北地区汉族、蒙古族及朝鲜族３个群体的１０２例男性个体的ＤＹＳ３９０位点的遗传多态性进行了研究。结果 除汉族群体发现５种等位基因外,朝鲜族和蒙古族群体均检出４种。在汉族群体中,我们检出１例具２     

白颊长臂猿染色体的研究

本文对我国云南南部的白须长臂猿（Ｈ．ｌｅｕｃｏｇｅｎｙｓ）染色体的Ｇ带、Ｃ带、晚复制带及Ａｇ－ＮＯＲｓ进行了较为详细的研究。它的２ｎ＝５２,核型公式为４４（Ｍ或ＳＭ）＋６（Ａ）,ＸＹ（Ｍ,Ａ）。Ｃ带表明一些染色体着丝点Ｃ带弱化;有的染色体出现插入的和端位的Ｃ带;Ｘ染色体两臂有端位Ｃ带,Ｙ染色体是Ｃ带阳性和晚复制的。Ａｇ－ＮＯＲｓ的数目,雌体有４个,雄体有５个,Ｙ染色体上具ＮＯＲ。本文对白颊长臂猿与其它长臂猿间的亲缘关系、核型进化的可能途径进行了讨论。     

利用染色体涂染方法建立人和白眉长臂猿的比较染色体图谱

除人Ｙ染色体外,本文采用生物素标记的人全部整条染色体特异探针与白眉长臂猿有丝分裂中期分裂相进行染色体原位杂交即染色体涂染法以研究人和白眉长臂猿染色体之间的同源性。在白眉长臂猿１８对常染色体上检测出了与人２２对常染色体同源的５９对染色体片段,确定了人和白眉长臂猿之间的精度较高的染色体连锁群。结果表明：自人与白眉长臂猿的祖长分歧以来,大量的染色体间重排（至少发生了３９次易位）和染色体内的重排导致了二者     

人类X染色体Xp11.3—21.3区部分YAC重叠群构建及大尺度物理图谱分析

人类Ｘ染色体短臂１１．３－２１．３区是含有视网膜色素奕性等种遗传基因位点的区域。我们对这个具有重要医学生物学意义的区段进行了ＹＡＣ重叠群构建及大尺度物理作图。用这一区域已知的探讨（ＯＴＣ２ｂＡ３、ＤＭＤｃＤＮＡ），以ＹＡＣ菌落原杂交法及ＰＣＲ法进行了ＹＡＣ的筛选；也采用了法国ＣＥＰＨ和英国ＩＣＲＦ的部分ＹＡＣ，总共得到了７７个阳性ＹＡＣ。对上述ＹＡＣ进行了长度测定。２６对微卫星ＳＴＳ图谱分析，单拷     

应用涂染技术研究人和猕猴染色体的同源性

用２４种人类染色体探针对人和猕猴Ｇ－显带染色体进行涂染。结果显示：人类所有染色体在猕猴的染色体组里都有其同源染色体或染色体片段。     

猕猴、白眉长臂猿、人类染色体普通型脆性部位和G-带的比较研究

以BrdU、FdU、MTX诱导猕猴、白眉长臂猿和人类染色体普通型脆性部位的表达,并对染色体脆性部位和染色体进化的关系以及三种灵长类染色体的同源性进行了比较分析。结果表明,近缘动物染色体同源区内的脆性部位在进化上是保守的,可作为染色体具有共同起源的标志,结合G-带的比较,可以用以阐明近缘动物染色体的同源性和染色体进化。     

Complete homology maps of the rabbit (Oryctolagus cuniculus) and human by reciprocal chromosome painting

Fluorescence in situ hybridization (FISH) was used to construct a homology map to analyse the extent of evolutionary conservation of chromosome segments between human and rabbit (Oryctolagus cuniculus, 2n = 44). Chromosome-specific probes were established by bivariate fluorescence activated flow sorting followed by degenerate oligonucleotide-primed PCR (DOP-PCR). Painting of rabbit probes to human chromosomes and vice versa allowed a detailed analysis of the homology between these species. All rabbit chromosome paints, except for the Y paint, hybridized to human chromosomes. All human chromosome paints, except for the Y paint, hybridized to rabbit chromosomes. The results obtained revealed extensive genome conservation between the two species. Rabbit chromosomes 12, 19 and X were found to be completely homologous to human chromosomes 6, 17 and X, respectively. All other human chromosomes were homologous to two or sometimes three rabbit chromosomes. Many conserved chromosome segments found previously in other mammals (e.g. cat, pig, cattle, Indian muntjac) were also found to be conserved in rabbit chromosomes.     

Sex chromosome homologies between human and fish revealed by the chromosome painting method

Human sex chromosome-specific probes were hybridized to metaphase spreads of three fish species, Monopterus albus Zuiew, Danio rerio and Mastacembelus aculeatus Basilewsky, to reveal evolutionary conservation of sex chromosomal segments between distantly related species of vertebrates. The human X chromosomal paint disclosed 4, 8, and 6 conserved syntenic segments in the karyotypes of the three fish species respectively, which were scattered in several pairs of homologous chromosomes. But no conserved segment was identified in our experiments when the human Y chromosomal probes were used. The evolution of the X chromosome of vertebrates is discussed.     

Cytologic evidence for three human X-chromosomal segments escaping inactivation

Summary Early replication of prometaphasic human sex chromosomes was studied with the bromodeoxyuridine (BrdU)-replication technique. The studies reveal that two distal segments of Xp, including bands Xp 22.13 and Xp 22.3, replicate early in S-phase and therefore may not be subject to random inactivation. Furthermore, the replication of these distal segments of Xp occurs synchronously with those of the short arm of the Y chromosome including bands Yp 11.2 and Yp 11.32. These segments of Xp and Yp correspond well to the pairing segment of the X and Y chromosomes where a synaptonemal complex forms at early pachytene of human spermatogenesis. The homologous early replication of Yp and the distal portion of Xp may be interpreted as a remnant left untouched by the differentiation of heteromorphic sex chromosomes from originally homomorphic autosomes. A third early replicating segment is situated on the long arm of the X chromosome and corresponds to band Xq 13.1. This segment may be correlated with the X-inactivation center postulated by Therman et al. (1979).     

Similarities in the chromosomal distribution of AG and AC repeats within and between Drosophila, human and barley chromosomes

Two simple sequence repeats (SSRs), AG and AC, were mapped directly in the metaphase chromosomes of man and barley (Hordeum vulgare L.), and in the metaphase and polytene chromosomes of Drosophila melanogaster. To this end, synthetic oligonucleotides corresponding to (AG)(12) and (AC)(8) were labelled by the random primer technique and used as probes in fluorescent in situ hybridisation (FISH) under high stringency and strict washing conditions. The distribution and intensity of the signals for the repeat sequences were found to be characteristic of the chromosomes and genomes of the three species analysed. The AC repeat sites were uniformly dispersed along the euchromatic segments of all three genomes; in fact, they were largely excluded from the heterochromatin. The Drosophila genome showed a high density of AC sequences on the X chromosome in both mitotic and polytene nuclei. In contrast, the AG repeats were associated with the euchromatic regions of the polytene chromosomes (and in high density on the X chromosome), but were only seen in specific heterochromatic regions in the mitotic chromosomes of all three species. In Drosophila, the AG repeats were exclusively distributed on the tips of the Y chromosome and near the centromere on both arms of chromosome 2. In barley and man, AG repeats were associated with the centromeres (of all chromosomes) and nucleolar organizer regions, respectively. The conserved chromosome distribution of AC within and between these three phylogenetically distant species, and the association of AG in specific chromosome regions with structural or functional properties, suggests that long clusters of these repeats may have some, as yet unknown, role.     

Homologies between X and Y chromosomes detected by DNA probes: localisation and evolution.

We have isolated and characterized DNA probes that detect homologies between the X and Y chromosomes. Clone St25 is derived from the q13-q22 region of the X chromosome and recognizes a 98% homologous sequence on the Y chromosome. Y specific fragments were present in DNAs from 5 Yq-individuals and from 4 out of 7 XX males analysed. An X linked TaqI RFLP is detected with the St25 probe (33% heterozygosity) which should allow one to establish a linkage map including other polymorphic X-Y homologous sequences in this region and to compare it to a Y chromosome deletion map. Probe DXS31 located in Xp223-pter detects a 80% homologous sequence in the Y chromosome. The latter can be assigned to Yq11-qter outside the region which contains the Y specific satellite sequences. ACT1 and ACT2, the actin sequences present on the X and Y chromosomes respectively, have been cloned. No homology was detected between the X and Y derived fragments outside from the actin sequence. ACT2 and the Y specific sequence corresponding to DXS31 segregate together in a panel of Y chromosomes aberrations, and might be useful markers for the region important for spermatogenesis in Yq. Various primate species were analysed for the presence of sequences homologous to the three probes. Sequences detected by St25 and DXS31 are found only on the X chromosome in cercopithecoidae. The sequences which flank ACT2 detect in the same species autosomal fragments but no male specific fragments. It is suggested that the Y chromosome acquired genetic material from the X chromosome and from autosomes at various times during primate evolution.     

Analysis of replication patterns in chromosomes of normal Chinese hamster and its cell lines

Replication patterns of the normal male Chinese hamster chromosomes and the three cell lines CHW, 1102 and 1103, were determined using fluorescent, plus Giemsa or acridine orange, techniques. The individual chromosomes or chromosomal segments were consistent in the replication patterns of normal Chinese hamster chromosomes and all the transformed cell lines. Late DNA replication was regularly identified in the long arm of the X chromosome, the entire Y chromosome, the short arms of chromosomes 6 and 7, and the paracentromeric regions of chromosomes 8, 9 and 10. A similar consistency was demonstrated in the large late replicating areas of chromosomes X and Y. Each cell line had specific marker chromosomes by which the cell line was identified and their replication patterns have been described. The chromosome analysis in cell line 1103 indicated that chromosomes 2, 3, 8 and 9 were more stable than others, of which chromosome 2 was extremely stable. The markers M4 and M5 in cell line 1103 are very interesting. The cytogenetic behaviour of marker M4 indicated a new phenomenon of translocation by simple association. The marker chromosome M5 indicated that inactivation spread to the early replicating distal region. These cell lines are very useful tools for studying replication patterns and providing a basic understanding of mammalian cytogenetics.     

Evolution of homologous sequences on the human X and Y chromosomes, outside of the meiotic pairing segment.

A sequence isolated from the long arm of the human Y chromosome detects a highly homologous locus on the X. This homology extends over at least 50 kb of DNA and is postulated to be the result of a transposition event between the X and Y chromosomes during recent human evolution, since homologous sequences are shown to be present on the X chromosome alone in the chimpanzee and gorilla.     

Sex Chromosomal Homologies between Human and Fish Karyotypes Revealed by Chromosome Painting

Human sex chromosome-specific probes were hybridized to metaphase spreads of three fish species, Monopterus albus Zuiew, Danio rerioandMastacembelus aculeatusBasilewsky, to reveal evolutionary conservation of sex chromosomal segments between distantly related species of vertebrates. The human X chromosomal paint disclosed 4, 8, and 6 conserved syntenic segments in the karyotypes of the three fish species respectively, which were scattered in several pairs of homologous chromosomes. But no conserved segment was identified in our experiments when the human Y chromosomal probes were used. The evolution of the X chromosome of vertebrates is discussed.     

Extensive DNA sequence homologies between the human Y and the long arm of the X chromosome.

It has been proposed that sequence homology should exist between the short arms of the human sex chromosomes, in the regions pairing at meiosis. Out of 40 clones picked at random from a collection of non-repetitive DNA sequences derived from the human Y chromosome, we have found nine sequences which show very high homology with sequences located on the X chromosome. All nine probes originate from the euchromatic part of the Y chromosome. All the homologous sequences are located within the Xq12-Xq22-24 region. None of them map to the short arm of the X chromosome. We conclude that an important part of the euchromatic region of the Y chromosome is homologous to the middle of the X chromosome long arm, possibly as a result of recent translation event(s).     

Microsatellite variation and evolutionary history of PCDHX/Y gene pair within the Xq21.3/Yp11.2 hominid-specific homology block

To better understand the evolutionary dynamics of repetitive sequences in human sex chromosomes, we have analyzed seven new X/Y homologous microsatellites located within PCDHX/Y, one of the two recently described gene pairs in the Xq21.3/Yp11.2 hominid-specific homology block, in samples from Portugal and Mozambique. Sharp differences were observed on X/Y allele distributions, concerning both the presence of private alleles and a different modal repeat length for X-linked and Y-linked markers, and this difference was statistically significant. Higher diversity was found in X-linked microsatellites than in their Y chromosome counterparts; when comparing populations, Mozambicans showed more allele diversity for the X chromosome, but the contrary was true for the Y chromosome microsatellites. Evolutionary patterns, relying on intragenic PCDHX/Y SNPs, also revealed distinct scenarios for X and Y chromosomes. Greater microsatellite diversity was displayed by African X chromosomes within the most common haplotypes shared by both populations, whereas higher microsatellite diversity was found in Portugal for the ancestral Y chromosome haplotype. The most frequent PCDHY haplotype in Portuguese was the derived one, and it was not found in Mozambicans. TMRCA estimated by the rho parameter resulted in 13,700 years (7,500-20,000 years), which is consistent with a recent, post-Out-of-Africa origin for this haplotype. In conclusion, the newly described microsatellite loci generally displayed greater X-linked to Y-linked diversity and this pattern was also detected with slower evolving markers, with a remarkable differentiation between populations observed for Y chromosome haplotypes and, thus, greater divergence among Y chromosomes in human populations.