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排序方式: 共有72条查询结果,搜索用时 390 毫秒
1.
Transverse alternating field electrophoresis (TAFE) 总被引:3,自引:0,他引:3
The rapid development of electrophoretic technology during the past five years has given us a stream of improvements in the area of pulsed-field separation techniques. This progression has culminated in the conception of TAFE, a simple, high resolution technique providing straight lane geometry and separation of fragments up to 9 million base pairs in length. Pulsed-field techniques will unquestionably play a major role in the forthcoming analysis of the human genome by facilitating restriction mapping and cloning of large fragments. We have no doubt that TAFE will allow scientists to do this type of genetic analysis, faster and better than ever before. 相似文献
2.
In Drosophila neuroblast cells, which give rise to the embryonic nervous system, undergo a limited number of asymmetric cell divisions. These cell lineages result in the formation of clusters of neurons when neuroblasts are isolated and cultured. A significant proportion of these neural cell clusters (NCC) arise from individual precursor cells. The formation of NCC containing more than two neurons is repressed when DNA synthesis is inhibited. Cell division during NCC development was examined by [3H]thymidine autoradiography. The pattern of DNA synthesis by neural cells was that expected based on observations in situ. The pattern in individual NCC was consistent with single precursor origins for more than 80% of NCC, under our conditions of culture. Based on this, we show that the largest neural precursors at gastrulation undergo the most cell divisions in culture. The neuroblast cell division cycle averages approximately 1.5 hr, and is similar to that of blastoderm cells. 相似文献
3.
Doran M Raicu DS Furst JD Settimi R Schipma M Chandler DP 《Bioinformatics (Oxford, England)》2007,23(4):487-492
The capability of a custom microarray to discriminate between closely related DNA samples is demonstrated using a set of Bacillus anthracis strains. The microarray was developed as a universal fingerprint device consisting of 390 genome-independent 9mer probes. The genomes of B. anthracis strains are monomorphic and therefore, typically difficult to distinguish using conventional molecular biology tools or microarray data clustering techniques. Using support vector machines (SVMs) as a supervised learning technique, we show that a low-density fingerprint microarray contains enough information to discriminate between B. anthracis strains with 90% sensitivity using a reference library constructed from six replicate arrays and three replicates for new isolates. 相似文献
4.
The pathogenesis of systemic sclerosis (SSc) is complex and largely unclear. The clinical heterogeneity of the disease and its progression over a number of years makes the choice of endpoints in the design of clinical trials difficult. The overwhelming need in this disease is to diagnose it early and identify those patients who will benefit most from early, aggressive treatment that potentially can alter the clinical disease course. To achieve this, innumerable challenges must be overcome. This article reviews data from recent clinical trials and the lessons derived from retrospective observational studies, databases, and patient registries. Taken together, these observations will help to improve our understanding of the diverse clinical course of SSc and permit refinement of existing outcome measures for the design of future clinical trials, in which the likelihood of observing a positive treatment effect with the drugs at our disposal will be maximized. 相似文献
5.
JG Hansen W Gao J Dupuis GT O’Connor W Tang M Kowgier A Sood SA Gharib LJ Palmer M Fornage SR Heckbert BM Psaty SL Booth SUNLIGHT Consortium Patricia A Cassano 《Respiratory research》2015,16(1)
Background
Vitamin D is associated with lung function in cross-sectional studies, and vitamin D inadequacy is hypothesized to play a role in the pathogenesis of chronic obstructive pulmonary disease. Further data are needed to clarify the relation between vitamin D status, genetic variation in vitamin D metabolic genes, and cross-sectional and longitudinal changes in lung function in healthy adults.Methods
We estimated the association between serum 25-hydroxyvitamin D [25(OH)D] and cross-sectional forced expiratory volume in the first second (FEV1) in Framingham Heart Study (FHS) Offspring and Third Generation participants and the association between serum 25(OH)D and longitudinal change in FEV1 in Third Generation participants using linear mixed-effects models. Using a gene-based approach, we investigated the association between 241 SNPs in 6 select vitamin D metabolic genes in relation to longitudinal change in FEV1 in Offspring participants and pursued replication of these findings in a meta-analyzed set of 4 independent cohorts.Results
We found a positive cross-sectional association between 25(OH)D and FEV1 in FHS Offspring and Third Generation participants (P = 0.004). There was little or no association between 25(OH)D and longitudinal change in FEV1 in Third Generation participants (P = 0.97). In Offspring participants, the CYP2R1 gene, hypothesized to influence usual serum 25(OH)D status, was associated with longitudinal change in FEV1 (gene-based P < 0.05). The most significantly associated SNP from CYP2R1 had a consistent direction of association with FEV1 in the meta-analyzed set of replication cohorts, but the association did not reach statistical significance thresholds (P = 0.09).Conclusions
Serum 25(OH)D status was associated with cross-sectional FEV1, but not longitudinal change in FEV1. The inconsistent associations may be driven by differences in the groups studied. CYP2R1 demonstrated a gene-based association with longitudinal change in FEV1 and is a promising candidate gene for further studies.Electronic supplementary material
The online version of this article (doi:10.1186/s12931-015-0238-y) contains supplementary material, which is available to authorized users. 相似文献6.
Fleming JN Nash RA McLeod DO Fiorentino DF Shulman HM Connolly MK Molitor JA Henstorf G Lafyatis R Pritchard DK Adams LD Furst DE Schwartz SM 《PloS one》2008,3(1):e1452
Background
Scleroderma is an autoimmune disease with a characteristic vascular pathology. The vasculopathy associated with scleroderma is one of the major contributors to the clinical manifestations of the disease.Methodology/Principal Findings
We used immunohistochemical and mRNA in situ hybridization techniques to characterize this vasculopathy and showed with morphometry that scleroderma has true capillary rarefaction. We compared skin biopsies from 23 scleroderma patients and 24 normal controls and 7 scleroderma patients who had undergone high dose immunosuppressive therapy followed by autologous hematopoietic cell transplant. Along with the loss of capillaries there was a dramatic change in endothelial phenotype in the residual vessels. The molecules defining this phenotype are: vascular endothelial cadherin, a supposedly universal endothelial marker required for tube formation (lost in the scleroderma tissue), antiangiogenic interferon α (overexpressed in the scleroderma dermis) and RGS5, a signaling molecule whose expression coincides with the end of branching morphogenesis during development and tumor angiogenesis (also overexpressed in scleroderma skin. Following high dose immunosuppressive therapy, patients experienced clinical improvement and 5 of the 7 patients with scleroderma had increased capillary counts. It was also observed in the same 5 patients, that the interferon α and vascular endothelial cadherin had returned to normal as other clinical signs in the skin regressed, and in all 7 patients, RGS5 had returned to normal.Conclusion/Significance
These data provide the first objective evidence for loss of vessels in scleroderma and show that this phenomenon is reversible. Coordinate changes in expression of three molecules already implicated in angiogenesis or anti-angiogenesis suggest that control of expression of these three molecules may be the underlying mechanism for at least the vascular component of this disease. Since rarefaction has been little studied, these data may have implications for other diseases characterized by loss of capillaries including hypertension, congestive heart failure and scar formation. 相似文献7.
AHNAK controls 53BP1-mediated p53 response by restraining 53BP1 oligomerization and phase separation
Indrajeet Ghodke Michaela Remisova Audrey Furst Sinan Kilic Bernardo Reina-San-Martin Anna R. Poetsch Matthias Altmeyer Evi Soutoglou 《Molecular cell》2021,81(12):2596-2610.e7
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8.
Across mammals many vocal sounds are produced by airflow induced vocal fold oscillation. We tested the hypothesis that stress-strain and stress-relaxation behavior of rat vocal folds can be used to predict the fundamental frequency range of the species' vocal repertoire. In a first approximation vocal fold oscillation has been modeled by the string model but it is not known whether this concept equally applies to large and small species. The shorter the vocal fold, the more the ideal string law may underestimate normal mode frequencies. To accommodate the very small size of the tissue specimen, a custom-built miniaturized tensile test apparatus was developed. Tissue properties of 6 male rat vocal folds were measured. Rat vocal folds demonstrated the typical linear stress-strain behavior in the low strain region and an exponential stress response at strains larger than about 40%. Approximating the rat's vocal fold oscillation with the string model suggests that fundamental frequencies up to about 6 kHz can be produced, which agrees with frequencies reported for audible rat vocalization. Individual differences and time-dependent changes in the tissue properties parallel findings in other species, and are interpreted as universal features of the laryngeal sound source. 相似文献
9.
The bacterium Escherichia coli exhibits chemotactic behavior at temperatures ranging from approximately 20 °C to at least 42 °C. This behavior is controlled by clusters of transmembrane chemoreceptors made from trimers of dimers that are linked together by cross-binding to cytoplasmic components. By detecting fluorescence energy transfer between various components of this system, we studied the underlying molecular behavior of these receptors in vivo and throughout their operating temperature range. We reveal a sharp modulation in the conformation of unclustered and clustered receptor trimers and, consequently, in kinase activity output. These modulations occurred at a characteristic temperature that depended on clustering and were lower for receptors at lower adaptational states. However, in the presence of dynamic adaptation, the response of kinase activity to a stimulus was sustained up to 45 °C, but sensitivity notably decreased. Thus, this molecular system exhibits a clear thermal sensitivity that emerges at the level of receptor trimers, but both receptor clustering and adaptation support the overall robust operation of the system at elevated temperatures. 相似文献
10.
Utility of the white gene in estimating phylogenetic relationships among mosquitoes (Diptera: Culicidae) 总被引:2,自引:0,他引:2
The utility of a nuclear protein-coding gene for reconstructing
phylogenetic relationships within the family Culicidae was explored.
Relationships among 13 species representing three subfamilies and nine
genera of Culicidae were analyzed using a 762-bp fragment of coding
sequence from the eye color gene, white. Outgroups for the study were two
species from the sister group Chaoboridae. Sequences were determined from
clone PCR products amplified from genomic DNA, and aligned following
conceptual intron splicing and amino acid translation. Third codon
positions were characterized by high levels of divergence and biased
nucleotide composition, the intensity and direction of which varied among
taxa. Equal weighting of all characters resulted in parsimony and
neighboring-joining trees at odds with the generally accepted phylogenetic
hypothesis based on morphology and rDNA sequences. The application of
differential weighting schemes recovered the traditional hypothesis, in
which the subfamily Anophelinae formed the basal clade. The subfamily
Toxorhynchitinae occupied an intermediate position, and was a sister group
to the subfamily Culicinae. Within Culicinae, the genera Sabethes and
Tripteroides formed an ancestral clade, while the Culex-Deinocerites and
Aedes- Haemagogus clades occupied increasingly derived positions in the
molecular phylogeny. An intron present in the Culicinae- Toxorhynchitinae
lineage and one outgroup taxon was absent in the basal Anophelinae lineage
and the second outgroup taxon, suggesting that intron insertions or
deletions may not always be reliable systematic characters.
相似文献