排序方式: 共有39条查询结果,搜索用时 281 毫秒
21.
D. HEINEKE F. KAUDER W. FROMMER C. KÜHN B. GILLISSEN F. LUDEWIG & U. SONNEWALD 《Plant, cell & environment》1999,22(6):623-628
Acclimation of plants to an increase in atmospheric carbon dioxide concentration is a well described phenomenon. It is characterized by an increase in leaf carbohydrates and a degradation of ribulose 1, 5-bisphosphate carboxylase protein (Rubisco) leading in the long term to a lower rate of CO2 assimilation than expected from the kinetic constants of Rubisco. This article summarizes studies with transgenic plants grown in elevated pCO2 which are modified in their capacity of CO2 fixation, of sucrose and starch synthesis, of triosephosphate and sucrose transport and of sink metabolism of sucrose. These studies show that a feedback accumulation of carbohydrates in leaves play only a minor role in acclimation, because leaf starch synthesis functions as an efficient buffer for photoassimilates. There is some evidence that in elevated pCO2 , plants grow faster and senescence is induced earlier. 相似文献
22.
Maged1, a new regulator of skeletal myogenic differentiation and muscle regeneration 总被引:1,自引:0,他引:1
Tuan HN Nguyen Mathieu JM Bertrand Christiane Sterpin Younes Achouri Olivier RY De Backer 《BMC cell biology》2010,11(1):57
Background
In normal adult skeletal muscle, cell turnover is very slow. However, after an acute lesion or in chronic pathological conditions, such as primary myopathies, muscle stem cells, called satellite cells, are induced to proliferate, then withdraw definitively from the cell cycle and fuse to reconstitute functional myofibers. 相似文献23.
CA Siegrist C van Delden M Bel C Combescure C Delhumeau M Cavassini O Clerc S Meier K Hadaya PM Soccal S Yerly L Kaiser B Hirschel A Calmy;HN Study Group;Swiss HIV Cohort Study 《PloS one》2012,7(7):e40428
Background
Memory responses require immune competence. We assessed the influence of priming with AS03-adjuvanted pandemic vaccine (Pandemrix®) on memory responses of HIV patients, kidney recipients (SOT) and healthy controls (HC).Method
Participants (HIV: 197, SOT: 53; HC: 156) were enrolled in a prospective study and 390/406 (96%) completed it. All had been primed in 2009/2010 with 1 (HC) or 2 (patients) doses of Pandemrix®, and were boosted with the 2010/2011 seasonal influenza vaccine. Geometric mean titres and seroprotection rates were measured 12 months after priming and 4 weeks after boosting. Primary and memory responses were directly compared in 191 participants (HCW: 69, HIV: 71, SOT: 51) followed during 2 consecutive seasons.Results
Most participants (HC: 77.8%, HIV: 77.6%, SOT: 66%) remained seroprotected at 12 months post-priming. Persisting A/09/H1N1 titers were high in HIV (100.2) and HC (120.1), but lower in SOT (61.4) patients. Memory responses reached higher titers in HIV (507.8) than in HC (253.5) and SOT (136.9) patients. Increasing age and lack of HAART reduced persisting and memory responses, mainly influenced by residual antibody titers. Comparing 2009/2010 and 2010/2011 titers in 191 participants followed for 2 seasons indicated lower post-2010/2011 titers in HC (240.2 vs 313.9), but higher titers in HIV (435.7 vs 338.0) and SOT (136 vs 90.3) patients.Conclusions
Priming with 2 doses of Pandemrix® elicited persistent antibody responses and even stronger memory responses to non-adjuvanted seasonal vaccine in HIV patients than 1 dose in healthy subjects. Adjuvanted influenza vaccines may improve memory responses of immunocompromised patients.Trial Registration
ClinicalTrials.gov NCT01022905相似文献24.
FRANK BAUMANN JIN-SHENG HE† KARSTEN SCHMIDT PETER KÜHN THOMAS SCHOLTEN 《Global Change Biology》2009,15(12):3001-3017
We investigated the main parameters [e.g. mean annual air temperature , mean annual soil temperature, mean annual precipitation, soil moisture (SM), soil chemistry, and physics] influencing soil organic carbon (Corg), soil total nitrogen (Nt) as well as plant available nitrogen (Nmin) at 47 sites along a 1200 km transect across the high‐altitude and low‐latitude permafrost region of the central‐eastern Tibetan Plateau. This large‐scale survey allows testing the hypothesis that beside commonly used ecological variables, diversity of pedogenesis is another major component for assessing carbon (C) and nitrogen (N) cycling. The aim of the presented research was to evaluate consequences of permafrost degradation for C and N stocks and hence nutrient supply for plants, as the transect covers all types of permafrost including heavily degraded areas and regions without permafrost. Our results show that SM is the dominant parameter explaining 64% of Corg and 60% of N variation. The extent of the effect of SM is determined by permafrost, current aeolian sedimentation occurring mostly on degraded sites, and pedogenesis. Thus, the explanatory power for C and N concentrations is significantly improved by adding CaCO3 content (P=0.012 for Corg; P=0.006 for Nt) and soil texture (P=0.077 for Corg; P=0.015 for Nt) to the model. For soil temperature, no correlations were detected indicating that in high‐altitude grassland ecosystems influenced by permafrost, SM overrides soil temperature as the main driving parameter at landscape scale. It was concluded from the current study that degradation of permafrost and corresponding changes in soil hydrology combined with a shift from mature stages of pedogenesis to initial stages, have severe impact on soil C and plant available N. This may alter biodiversity patterns as well as the development and functioning of the ecosystems on the Tibetan Plateau. 相似文献
25.
Background
Breeding programs are usually reluctant to evaluate and use germplasm accessions other than the elite materials belonging to their advanced populations. The concept of core collections has been proposed to facilitate the access of potential users to samples of small sizes, representative of the genetic variability contained within the gene pool of a specific crop. The eventual large size of a core collection perpetuates the problem it was originally proposed to solve. The present study suggests that, in addition to the classic core collection concept, thematic core collections should be also developed for a specific crop, composed of a limited number of accessions, with a manageable size. 相似文献26.
MOTIVATION: Recently, we described a Maximum Weighted Matching (MWM) method
for RNA structure prediction. The MWM method is capable of detecting
pseudoknots and other tertiary base-pairing interactions in a
computationally efficient manner (Cary and Stormo, Proceedings of the Third
International Conference on Intelligent Systems for Molecular Biology, pp.
75-80, 1995). Here we report on the results of our efforts to improve the
MWM method's predictive accuracy, and show how the method can be extended
to detect base interactions formerly inaccessible to automated RNA modeling
techniques. RESULTS: Improved performance in MWM structure prediction was
achieved in two ways. First, new ways of calculating base pair likelihoods
have been developed. These allow experimental data and combined statistical
and thermodynamic information to be used by the program. Second, accuracy
was improved by developing techniques for filtering out spurious base pairs
predicted by the MWM program. We also demonstrate here a means by which the
MWM folding method may be used to detect the presence of base triples in
RNAs. AVAILABILITY: http://www.cshl.org/mzhanglab/tabaska/j axpage. html
CONTACT: tabaska@cshl.org
相似文献
27.
Contrasting levels of DNA polymorphism at the autosomal and X-linked visual color pigment loci in humans and squirrel monkeys 总被引:1,自引:0,他引:1
The X-linked color pigment (opsin) locus is known to be highly polymorphic
in the squirrel monkey and other New World monkeys. To see whether this is
also the case for the autosomal (blue) opsin locus, we obtained 32 squirrel
monkey and 30 human blue opsin gene sequences. No amino acid polymorphism
was found in either the squirrel monkey sample or the human sample,
contrary to the situation at the X-linked opsin locus. This sharp contrast
in the level of polymorphism might be due to differences in gene expression
between the autosomal and the X-linked loci. At the X-linked locus,
heterozygote advantage can occur because, owing to X-inactivation, the two
alleles in a heterozygote are expressed in different cone cells, producing
two types of cone cell, whereas at the autosomal locus, heterozygote
advantage cannot occur because the two alleles in a heterozygote are
expressed in the same cone cells, producing only one type of cone cell
(i.e., phenotypically a homozygote). From the sequence data, the levels of
nucleotide diversity (pi, i.e., the number of nucleotide differences per
site) are estimated: for the human sample, pi = 0.00% per nondegenerate
site, 0.00% per twofold degenerate site, and 0.04% per fourfold degenerate
site in the coding regions and 0.01% per site in intron 4; for the squirrel
monkey sample, pi = 0.00% per nondegenerate site, 0.00% per twofold
degenerate site, and 0.15% per fourfold degenerate site in the coding
regions and 0.17% per site in intron 4. The blue opsin genes from the
common and pygmy chimpanzees, the gorilla, the capuchin, and the howler
monkey were also sequenced. Features critical to the function of the opsin
are well conserved in all known mammalian sequences. However, the
interhelical loops are, on average, actually more conservative than the
transmembrane helical regions. In addition, these sequence data and those
from some other genes indicate that the common and pygmy chimpanzees are
not closely related, their divergence data being from one third to one half
the date of the human-chimpanzee divergence.
相似文献
28.
Stephen L. Gabow 《Primates; journal of primatology》1973,14(2-3):215-223
A rank reversal between two groups of free-ranging rhesus monkeys (Macaca mulatta) was observed.The group which became dominant through the reversal had been transplanted from another free-ranging colony eight months before. The actions of peripheral adult males of this group were important in effecting the reversal. Support of the peripheral males by the rest of the group was crucial in effecting the reversal.The development of the reversal indicates that social tradition and individual relationships between monkeys are important in maintaining and establishing intergroup rank. 相似文献
29.
Background
Bacillus organisms are common laboratory contaminants. The majority of Bacillus bacteraemias are transient and not clinically significant. Clinically significant infection due to Bacillus species is rare and mostly due to Bacillus cereus infections in immuno-compromised hosts.Case presentation
We report a case of central venous catheter infection with Bacillus pumilus in an immunocompetent child with tufting enteropathy on long-term parenteral nutrition (PN). There were three episodes of central venous catheter infection with Bacillus pumilus in three months. Despite adequate and appropriate use of intravenous antibiotics, the infection failed to clear resulting in the need for removal of the catheter for complete cure.Conclusion
Bacillus species can cause clinically significant central venous catheter infection, even in an immunocompetent host. Despite adequate antibiotic treatment, the central venous catheter may need removal for complete cure. 相似文献30.
Maria D. Van Kerkhove Tommi Asikainen Niels G. Becker Steven Bjorge Jean-Claude Desenclos Thais dos Santos Christophe Fraser Gabriel M. Leung Marc Lipsitch Ira M. Longini Jr Emma S. McBryde Cathy E. Roth David K. Shay Derek J. Smith Jacco Wallinga Peter J. White Neil M. Ferguson Steven Riley for the WHO Informal Network for Mathematical Modelling for Pandemic Influenza HN 《PLoS medicine》2010,7(6)