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61.
报道中国鳖甲族1新纪录属及1新种:异颚弗鳖甲Freudeia heteromaxillaria sp.nov.,描述了新种的形态特征并附鉴别特征图和整体照片.新种模式标本保存于中国科学院西北高原生物研究所和河北大学博物馆.  相似文献   
62.
A gene density-related difference in the radial arrangement of chromosome territories (CTs) was previously described for human lymphocyte nuclei with gene-poor CT #18 located toward the nuclear periphery and gene-dense CT #19 in the nuclear interior (Croft, J.A., J.M. Bridger, S. Boyle, P. Perry, P. Teague, and W.A. Bickmore. 1999. J. Cell Biol. 145:1119-1131). Here, we analyzed the radial distribution of chromosome 18 and 19 chromatin in six normal cell types and in eight tumor cell lines, some of them with imbalances and rearrangements of the two chromosomes. Our findings demonstrate that a significant difference in the radial distribution of #18 and #19 chromatin is a common feature of higher order chromatin architecture in both normal and malignant cell types. However, in seven of eight tumor cell lines, the difference was less pronounced compared with normal cell nuclei due to a higher fraction of nuclei showing an inverted CT position, i.e., a CT #18 located more internally than a CT #19. This observation emphasizes a partial loss of radial chromatin order in tumor cell nuclei.  相似文献   
63.
棉蚜体色变化的生态遗传学研究   总被引:15,自引:0,他引:15  
赵惠燕  张改生 《昆虫学报》1993,36(3):282-289
调查了不同寄主上棉蚜刀Aphis gossypll自受精卵孵化出的自然种群、室内混合饲养以及单个饲养蚜虫的体色变化。结果表明:不论是自然还是实验种群,是群体还是个体饲养,不论寄主、栽培条件、生育期营养相同与否,棉蚜体色在世代内稳定不变,即出生时是什么颜色保持终生不变;在世代间则随温度升高体色渐变为黄色,温度降低体色逐渐转绿。伏蚜由苗蚜而来。X2检验证实:棉蚜体色变化与营养、寄主种类、光照、光质、栽培条件等无关,仅与温度密切相关,属于同一基因型在不同环境条件下的反应规范。但在太槿上还发现有个别深黄色棉蚜,从卵孵化到迁飞体色不随温度变化,表明棉蚜体色变化中还存在遗传多态现象。胚胎学观察与染色体校型分析结果证实了上述结论与观点。  相似文献   
64.
In situ hybridization has become a standard method for localizing DNA or RNA sequences in cytological preparations. We developed two methods to extend this technique to the transmission electron microscope level using mouse satellite DNA hybridization to whole mount metaphase chromosomes as the test system. The first method devised is a direct extension of standard light microscope level using mouse satellite DNA hybridization to whole mount metaphase chromosomes as the test system. The first method devised is a direct extension of standard light microscope in situ hybridization. Radioactively labeled complementary RNA (cRNA) is hybridized to metaphase chromosomes deposited on electron microscope grids and fixed in 70 percent ethanol vapor; hybridixation site are detected by autoradiography. Specific and intense labeling of chromosomal centromeric regions is observed even after relatively short exposure times. Inerphase nuclei present in some of the metaphase chromosome preparations also show defined paatterms of satellite DNA labeling which suggests that satellite-containing regions are associate with each other during interphase. The sensitivity of this method is estimated to at least as good as that at the light microscope level while the resolution is improved at least threefold. The second method, which circumvents the use of autoradiogrphic detection, uses biotin-labeled polynucleotide probes. After hybridization of these probes, either DNA or RNA, to fixed chromosomes on grids, hybrids are detected via reaction is improved at least threefold. The second method, which circumvents the use of autoradiographic detection, uses biotin-labeled polynucleotide probes. After hybridization of these probes, either DNA or RNA, to fixed chromosomes on grids, hybrids are detected via reaction with an antibody against biotin and secondary antibody adsorbed to the surface of over centromeric heterochromatin and along the associated peripheral fibers. Labeling is on average ten times that of background binding. This method is rapid and possesses the potential to allow precise ultrastructual localization of DNA sequences in chromosomes and chromatin.  相似文献   
65.
Payseur BA, Covert HA, Vinyard CJ, Dagosto M. 1999. New Body Mass Estimates for Omomys carteri, a Middle Eocene Primate From North America. Am J Phys Anthropol 109:41–52. This article included an incomplete Table 2. The final two columns, showing “Intercept” and “SEE” data were omitted. The complete Table 2, with these two columns included, is provided below.  相似文献   
66.
Secretory granules containing a hybrid protein consisting of the regulated secretory protein tissue plasminogen activator and an enhanced form of green fluorescent protein were tracked at high spatial resolution in growth cones of differentiated PC12 cells. Tracking shows that granules, unlike synaptic vesicles, generally are mobile in growth cones. Quantitative analysis of trajectories generated by granules revealed two dominant modes of motion: diffusive and directed. Diffusive motion was observed primarily in central and peripheral parts of growth cones, where most granules diffused two to four orders of magnitude more slowly than comparably sized spheres in dilute solution. Directed motion was observed primarily in proximal parts of growth cones, where a subset of granules underwent rapid, directed motion at average speeds comparable to those observed for granules in neurites. This high-resolution view of the dynamics of secretory granules in growth cones provides insight into granule organization and release at nerve terminals. In particular, the mobility of granules suggests that granules, unlike synaptic vesicles, are not tethered stably to cytoskeletal structures in nerve terminals. Moreover, the slow diffusive nature of this mobility suggests that secretory responses involving centrally distributed granules in growth cones will occur slowly, on a time scale of minutes or longer.  相似文献   
67.
During the 2003–2005 hunting seasons, a total of 120 Cervidae, including 39 red deer (Cervus elaphus hispanicus) and 81 fallow deer (Dama dama), were examined for subcutaneous myiasis. Animals were shot from January to June in southern Spain. Specific antibodies against Hypodermatinae (Diptera: Oestridae) were detected by indirect enzyme‐linked immunosorbent assay (iELISA) using a crude larval extract (CLE) and a purified antigen [hypodermin C (HC)] obtained from first instars of Hypoderma lineatum (De Villers) (Diptera: Oestridae). Hypoderma actaeon Brauer was the only species detected in this study, which represents the first confirmation of this species in fallow deer from Spain. The overall prevalence of animals presenting subcutaneous larvae (14.2%) was considerably lower than the prevalences determined by iELISA with CLE (43.3%) and HC (40.0%). Red deer showed a higher prevalence of Hypoderma than fallow deer. The concordance between larval examination during the hunting season and iELISA using both antigens was low, whereas the concordance between the CLE and HC ELISAs was good. Larval antigens obtained from H. lineatum constitute a good tool for the diagnosis of H. actaeon in Cervidae, especially when the hunting season does not coincide with the maximum presence of larvae on the back.  相似文献   
68.
The Netherlands is "well known" for its nitrogen problems; it has one of the highest reactive nitrogen (Nr) emission densities in the world. It is a small country at the delta of several large European rivers. Ever since the industrial revolution, there has been a growing excess of nutrients and related emissions into the atmosphere (ammonia, nitrogen oxides and nitrous oxide) and into groundwater and surface water (nitrate), leading to a large range of cascading environmental impacts. Vehicular traffic, sewage and animal husbandry are the main sources of oxidized and reduced forms of Nr. This paper provides an overview of the origin and fate of nitrogen in the Netherlands, the various reported impacts of nitrogen, the Dutch and European policies to reduce nitrogen emissions and related impacts. In addition, ways are presented to go forward to potentially solve the problems in a European perspective. Solutions include the improvement of nitrogen efficiencies in different systems, technological options and education.  相似文献   
69.
Sirenomelia or “mermaid syndrome” is a rare congenital anomaly known since antiquity. This congenital anomaly is defined as a polymalformative syndrome that associates major muscle and skeleton abnormalities (unique lower limbs) with visceral abnormalities (unilateral or bilateral renal agenesis, anomalies of the abdominal vascularisation). This phenotype, typical of sirenomelia syndrome, may be more or less severe. The pathogenic mechanisms of this syndrome are still debated and its etiology remains unknown. We report here a new type of sirenomelia that we observed in a fetus belonging to the collection of the Department of Anatomy of Reims, which led us to perform a comprehensive review of the literature on the subject: this type has never been reported and cannot be classified according to the Stocker and Heifetz classification. Moreover, this case also presents a VACTERL association with Thomas syndrome. Birth Defects Research (Part A) 97:123–132, 2013. © 2013 Wiley Periodicals, Inc.  相似文献   
70.
Cell rearrangements shape organs and organisms using molecular pathways and cellular processes that are still poorly understood. Here we investigate the role of the Actin cytoskeleton in the formation of the Drosophila compound eye, which requires extensive remodeling and coordination between different cell types. We show that CYFIP/Sra-1, a member of the WAVE/SCAR complex and regulator of Actin remodeling, controls specific aspects of eye architecture: rhabdomere extension, rhabdomere terminal web organization, adherens junctions, retina depth and basement membrane integrity. We demonstrate that some phenotypes manifest independently, due to defects in different cell types. Mutations in WAVE/SCAR and in ARP2/3 complex subunits but not in WASP, another major regulator of Actin nucleation, phenocopy CYFIP defects. Thus, the CYFIP-SCAR-ARP2/3 pathway orchestrates specific tissue remodeling processes.  相似文献   
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