997 resultados para 23-226


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This report of the cruise along the Sofala Bank (Mozambique) describes the catch composition and catch distributions of the shallow water shrimp. Biological data are given for Penaeus indicus and Metapenaeus monoceros which represent 77% of the total catch.

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Catch composition and bathymetric distribution of demersal fish caught along the coast of Mozambique between parallels 16 degree 20' and 19 degree 30' S at depths of 11 to 180 metres are given. The shrimp by-catch was also studied.

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This report of the research cruise (7 to 23 June 1981) surveying pelagic marine resources of the Sofala Bank (Mozambique) describes the size composition, distribution, length-weight relationships and sex-ratio of the fish captured. Decapterus russellii, D. macrosoma, Selar crumenophthalmus and Rastrelliger kanagurta represented 21.7% of the total catch. The by-catch was also studied.

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以流式细胞仪分离小麂(Muntiacus reevesi)Y染色体和黑麂(M. crinifrons)Y_(1),Y_(2),X+4和1号染色体,利用DOP-PCR技术富集了分离的各单条染色体。然后,将小麂的Y染色体的DOP-PCR产物经Cy_(3)标记后直接作为涂染探针,应用染色体涂染技术与雌雄黑麂的核型标本进行杂交,确认了黑麂真正的Y染色体为Y_(2)染色体。再以黑麂的Y_(1),Y_(2),X+4和1号染色体的DOP-PCR产物为模板,用人的特异性的SRY基因引物对其进行扩增,结果表明黑麂只有Y_(2)染色体出现了SRY扩增片段。

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Chromosomal homologies were established between human and two Chinese langurs (Semnopithecus francoisi, 2n=44, and S. phayrei, 2n=44) by chromosome painting with chromosome-specific DNA probes of all human chromosomes except the Y. Both langur species showed identical hybridization patterns in addition to similar G-banding patterns. In total, 23 human chromosome-specific probes detected 30 homologous chromosome segments in a haploid langur genome. Except for human chromosomes 1, 2, 6, 16 and 19 probes, which each gave signals on two non-homologous langur chromosomes respectively, all other probes each hybridized to a single chromosome. The results indicate a high degree of conservation of chromosomal synteny between human and these two Chinese langurs. The human chromosome 2 probe painted the entire euchromatic regions of langur chromosomes 14 and 19. Human chromosome 1 probe hybridized to three regions on langur autosomes, one region on langur chromosome 4 and two regions on langur chromosome 5. Human 19 probe hybridized on the same pattern to one region on chromosome 4 and to two regions on langur chromosome 5, where it alternated with the human chromosome 1 probe. Human 6 and 16 probes both hybridized to one region on each of the two langur autosomes 15 and 18. Only two langur chromosomes (12 and 21) were each labelled by probes specific for two whole human chromosomes (14 and 15 and 21 and 22 respectively). Comparison of the hybridization patterns of human painting probes on these two langurs with the data on other Old World primates suggests that reciprocal and Robertsonian translocations as will as inversions could have occurred since the divergance of human and the langurs from a common ancestor. This comparison also indicates that Asian colobines are karyotypically more closely related to each other that to African colobines.

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Forty chromosome-specific paint probes of the domestic dog (Canis familiaris, 2n = 78) were used to delineate conserved segments on metaphase chromosomes of the American mink (Mustela vison, 2n = 30) by fluorescence in situ hybridisation. Half of the 38 canine autosomal probes each painted one pair of homologous segments in a diploid mink metaphase, whereas the other 19 dog probes each painted from two to five pairs of discrete segments. In total, 38 canine autosomal paints highlighted 71 pairs of conserved segments in the mink. These painting results allow us to establish a complete comparative chromosome map between the American mink and domestic dog. This map demonstrates that extensive chromosome rearrangements differentiate the karyotypes of the dog and American mink. The 38 dog autosomes could be reconstructed from the 14 autosomes of the American mink through at least 47 fissions, 25 chromosome fusions, and six inversions. Furthermore, comparison of the current dog/mink map with the published human/dog map discloses 23 cryptic intrachromosomal rearrangements in 10 regions of conserved synteny in the human and American mink genomes and thus further refined the human/mink comparative genome map. Copyright (C) 2000 S. Karger AG, Basel.

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Complete sets of chromosome-specific painting probes, derived from flow-sorted chromosomes of human (HSA), Equus caballus (ECA) and Equus burchelli (EBU) were used to delineate conserved chromosomal segments between human and Equits burchelli, and among four equid species, E. przewalskii (EPR), E. caballus, E. burchelli and E. zebra hartmannae (EZH) by cross-species chromosome painting. Genome-wide comparative maps between these species have been established. Twenty-two human autosomal probes revealed 48 conserved segments in E. burchelli. The adjacent segment combinations HSA3/21, 7/16p, 16q/19q, 14/15, 12/22 and 4/8, presumed ancestral syntenies for all eutherian mammals, were also found conserved in E. burchelli. The comparative maps of equids allow for the unequivocal characterization of chromosomal rearrangements that differentiate the karyotypes of these equid species. The karyotypes of E. przewalskii and E. caballus differ by one Robertsonian translocation (ECA5 = EPR23 + EPR24); numerous Robertsonian translocations and tandem fusions and several inversions account for the karyotypic differences between the horses and zebras. Our results shed new light on the karyotypic evolution of Equidae. Copyright (C) 2003 S. Karger AG, Basel.

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Cross-species chromosome painting with probes derived from flow-sorted dog and human chromosomes was used to construct a high-resolution comparative map for the pig. In total 98 conserved autosomal segments between pig and dog were detected by probes specific for the 38 autosomes and X Chromosome of the dog. Further integration of our results with the published human-dog and cat-dog comparative maps, and with data from comparative gene mapping, increases the resolution of the current pig-human comparative map. It allows for the conserved syntenies detected in the pig, human, and cat to be aligned against the putative ancestral karyotype of eutherian mammals and for the history of karyotype evolution of the pig lineage to be reconstructed. Fifteen fusions, 17 fissions, and 23 inversions are required to convert the ancestral mammalian karyotype into the extant karyotype of the pig.

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Cross-species painting (fluorescence in situ hybridization) with 23 human (Homo sapiens (HSA)) chromosome-specific painting probes (HSA 1-22 and the X) was used to delimit regions of homology on the chromosomes of the golden mole (Ghrysochloris asiaticus) and elephant-shrew (Elephantulus rupestris). A cladistic interpretation of our data provides evidence of two unique associations, HSA 1/19p and 5/21/3, that support Afrotheria. The recognition of HSA 5/3/21 expands on the 3/21 synteny originally designated as an ancestral state for all eutherians. We have identified one adjacent segment combination (HSA2/8p/4) that is supportive of Afroinsectiphillia (aardvark, golden mole, elephant-shrew). Two segmental combinations (HSA 10q/17 and HSA 3/20) unite the aardvark and elephant-shrews as sister taxa. The finding that segmental syntenies in evolutionarily distant taxa can improve phylogenetic resolution suggests that they may be useful for testing sequence-based phylogenies of the early eutherian mammals. They may even suggest clades that sequence trees are not recovering with any consistency and thus encourage the search for additional rare genomic changes among afrotheres.

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该研究用12种识别六碱基的限制性内切酶对来自云南省3个地方绵羊品种11个样本的线粒体DNA(mtDNA)进行了限制性片段长度多态性分析(RFLP),结果表明,云南绵羊群体平均核苷歧异度为0.086%,平均遗传距离为0.004,说明mtDNA变异度很低,遗传多样性贫乏,提示云南绵羊可能起源于同一个共同祖先;昭通绵羊与德钦绵羊距离较远,大约分歧于30万年前,德钦绵羊与腾冲绵羊大约分歧于11万年前,而腾冲绵羊与昭通绵羊也于18万年前发生分歧。

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用15种限制性内切酶和人28S、18S rDNA探针构建了懒猴属各物种核糖体DNA重复单位的限制性内切酶图谱。在进化速率较高的非转录间隔区, 在大、中、小獭猴中分别定位了23、24、24个酶切位点。结果表明, 懒猴属内似只有两个有效物种, 即大懒猴和小懒猴, 中懒猴与小懒猴的分化至多到半种级别。

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以人28S,18S DNA为探针,用15种限制性内切酶构建了猕猴属6个种(M.mulatta、M.facsicularis、M.arctoides、M.assamensis、M.thibetana、M.nemestrina)和滇金丝猴(Rhinopithecus bieti),白颊长臂猿(Hylobates leucogenys)核糖体DNA重复单位的限制性内切酶图谱。红面猴(M.arctoides)与熊猴(M.assamensis)拥有完全相同的限制性内切酶图谱。基于内切酶图谱得到了68个信息位点并计算了各种rDNA重复型间的遗传距离。用PHYLIP version 3.5c软件包中的NEIGHBOR和RESTML程序,以滇金丝猴和白颊长臂猿为外群,构建了NJ树和最大似然树。两棵树的拓扑结构不完全一致,但恒河猴( (M.mulatta)和食蟹猴(M.facsicularis)总是位于树的基部。熊猴-红面猴(M.assamensis-M.arctoides)虽然与藏猴(M.thibetana)共享的限制性位点数更多,在NJ树上两类动物也最为接近,但在最大似然树中熊猴-红面猴却与平顶猴(M.nemestrina)聚在一起。因此,rDNA变异的数据尚不能对猕猴类动物进行有效的分组。

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The origin of new exons is an important mechanism for proteome diversity. Here, we report the recurrent origination of new exons in mammalian chromodomain Y-like (CDYL) genes and the functional consequences associated with the acquisition of the new exons

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目的研究蜱类抗血小板集聚的生物活性成分, 了解其与其宿主相互作用的分子机制。方法用葡聚糖 Sephadex G-50 凝胶过滤及高效液相从半饱吸血的中华硬蜱(Ixodes sinensis) 唾液腺中分离纯化具有血小板集聚抑制活性 的蛋白质, 用飞行质谱测定该抑制剂的分子量, 并用兔富血小板血浆研究其血小板集聚抑制活性。结果通过液相分离, 从中华硬蜱唾液腺中得到了一种血小板集聚抑制剂, 用飞行质谱测定该抑制剂的相对分子质量(M r ) 为8 065。该抑制 剂对二磷酸腺苷(ADP) 诱导的血小板集聚表现强烈的抑制活性, 在浓度为10 μg/mL 时, 可以抑制90% 以上的血小板集 聚。结论首次分离获得中华硬蜱唾液腺血小板集聚抑制剂, 该抑制剂对硬蜱顺利获取宿主血餐至关重要。