排序方式: 共有39条查询结果,搜索用时 0 毫秒
21.
Background
During the development of the central nervous system (CNS), patterning processes along the dorsoventral (DV) axis of the neural tube generate different neuronal subtypes. As development progresses these neurons are arranged into functional units with varying cytoarchitecture, such as laminae or nuclei for efficient relaying of information. Early in development ventral and dorsal regions are similar in size and structure. Different proliferation rates and cell migration patterns are likely to result in the formation of laminae or nuclei, eventually. However, the underlying molecular mechanisms that establish these different structural arrangements are not well understood. 相似文献22.
Efficient four fragment cloning for the construction of vectors for targeted gene replacement in filamentous fungi 总被引:2,自引:0,他引:2
Rasmus JN Frandsen Jens A Andersson Matilde B Kristensen Henriette Giese 《BMC molecular biology》2008,9(1):70
Background
The rapid increase in whole genome fungal sequence information allows large scale functional analyses of target genes. Efficient transformation methods to obtain site-directed gene replacement, targeted over-expression by promoter replacement, in-frame epitope tagging or fusion of coding sequences with fluorescent markers such as GFP are essential for this process. Construction of vectors for these experiments depends on the directional cloning of two homologous recombination sequences on each side of a selection marker gene. 相似文献23.
Florian Ryffel Eric JN Helfrich Patrick Kiefer Lindsay Peyriga Jean-Charles Portais J?rn Piel Julia A Vorholt 《The ISME journal》2016,10(3):632-643
The phyllosphere, which is defined as the parts of terrestrial plants above the ground, is a large habitat for different microorganisms that show a high extent of adaption to their environment. A number of hypotheses were generated by culture-independent functional genomics studies to explain the competitiveness of specialized bacteria in the phyllosphere. In contrast, in situ data at the metabolome level as a function of bacterial colonization are lacking. Here, we aimed to obtain new insights into the metabolic interplay between host and epiphytes upon colonization of Arabidopsis thaliana leaves in a controlled laboratory setting using environmental metabolomics approaches. Quantitative nuclear magnetic resonance (NMR) and imaging high-resolution mass spectrometry (IMS) methods were used to identify Arabidopsis leaf surface compounds and their possible involvement in the epiphytic lifestyle by relative changes in compound pools. The dominant carbohydrates on the leaf surfaces were sucrose, fructose and glucose. These sugars were significantly and specifically altered after epiphytic leaf colonization by the organoheterotroph Sphingomonas melonis or the phytopathogen Pseudomonas syringae pv. tomato, but only to a minor extent by the methylotroph Methylobacterium extorquens. In addition to carbohydrates, IMS revealed surprising alterations in arginine metabolism and phytoalexin biosynthesis that were dependent on the presence of bacteria, which might reflect the consequences of bacterial activity and the recognition of not only pathogens but also commensals by the plant. These results highlight the power of environmental metabolomics to aid in elucidating the molecular basis underlying plant–epiphyte interactions in situ. 相似文献
24.
25.
Alan Winston Alejandro Arenas-Pinto Wolfgang St?hr Martin Fisher Chloe M. Orkin Kazeem Aderogba Andrew De Burgh-Thomas Nigel O'Farrell Charles JN. Lacey Clifford Leen David Dunn Nicholas I. Paton for the PIVOT Trial Team 《PloS one》2013,8(4)
Objective
To describe factors associated with neurocognitive (NC) function in HIV-positive patients on stable combination antiretroviral therapy.Design
We undertook a cross-sectional analysis assessing NC data obtained at baseline in patients entering the Protease-Inhibitor-Monotherapy-Versus-Ongoing-Triple therapy (PIVOT) trial.Main outcome measure
NC testing comprised of 5 domains. Raw results were z-transformed using standard and demographically adjusted normative datasets (ND). Global z-scores (NPZ-5) were derived from averaging the 5 domains and percentage of subjects with test scores >1 standard deviation (SD) below population means in at least two domains (abnormal Frascati score) calculated. Patient characteristics associated with NC results were assessed using multivariable linear regression.Results
Of the 587 patients in PIVOT, 557 had full NC results and were included. 77% were male, 68% Caucasian and 28% of Black ethnicity. Mean (SD) baseline and nadir CD4+ lymphocyte counts were 553(217) and 177(117) cells/µL, respectively, and HIV RNA was <50 copies/mL in all. Median (IQR) NPZ-5 score was −0.5 (−1.2/−0) overall, and −0.3 (−0.7/0.1) and −1.4 (−2/−0.8) in subjects of Caucasian and Black ethnicity, respectively. Abnormal Frascati scores using the standard-ND were observed in 51%, 38%, and 81%, respectively, of subjects overall, Caucasian and Black ethnicity (p<0.001), but in 62% and 69% of Caucasian and Black subjects using demographically adjusted-ND (p = 0.20). In the multivariate analysis, only Black ethnicity was associated with poorer NPZ-5 scores (P<0.001).Conclusions
In this large group of HIV-infected subjects with viral load suppression, ethnicity but not HIV-disease factors is closely associated with NC results. The prevalence of abnormal results is highly dependent on control datasets utilised.Trial registry
ClinicalTrials.gov, NCT01230580相似文献26.
Metopolophium festucae cerealium has at various times caused damage to both grass and cereal crops. Despite this, little work has been done on the relative susceptibility of different grass and cereal cultivars to this aphid. The present work showed that for the cultivars examined the most common ley pasture species (Lolium perenne and Lolium multiflorum) exhibited relatively low levels of antibiotic resistance to M. f. cerealium and that wheat is more susceptible than any of the grass species tested. This enigma, in view of the aphid's low pest status on wheat, is discussed. The resistance in the grasses was greater at the stem elongation stages than at the seedling stage but the ranking was consistent between growth stages. M. f. cerealium exhibited a preference for feeding on emerging and senescing leaves of 10-wk-old grass but on wheat it distributed itself evenly between all available green leaves. 相似文献
27.
Jouvin-Marche E; Cuddihy A; Butler S; Hansen JN; Fitch WM; Rudikoff S 《Molecular biology and evolution》1988,5(5):500-511
The immunoglobulin kappa light-chain constant region gene (C kappa) has
been cloned and sequenced from five wild mouse species. Analysis of these
data has permitted an assessment of single-copy gene evolution during a
limited time period as defined by the genus Mus. Sequence conservation was
found to be as high (or higher) in the 5' and enhancer regions as in the
coding region. The pattern of substitutions throughout these genes suggests
that parallel evolution has occurred frequently and that substitutions at
replacement sites have not decreased significantly, owing to saturation
during this period of approximately 10 Myr. Phylogenetic relationships have
been determined among these wild species as well as among members of the
genus Rattus.
相似文献
28.
Streptococci isolated from the dental plaque of five animal species were identified by physiological and serological methods. Twenty-nine strains of streptococci considered to resemble Streptococcus mitior or Strep. bovis on the basis of physiological data reacted with Lancefield group B or group K antisera respectively in tube precipitation tests. Further serological studies with standardized antigens from known serogroup B and K streptococci revealed that only three of these 29 isolates had been serogrouped accurately and carried the appropriate group antigen. Comparisons were made between the reactivity of the antisera produced by Difco and Wellcome Reagents with acid and autoclaved extracts of the strains. It was shown that the accuracy of serogrouping such isolates could be improved if the tests were made in a gel diffusion system that included a reference antigen. 相似文献
29.
DENT CE 《Proceedings of the Royal Society of Medicine》1955,48(7):574-578
30.