排序方式: 共有49条查询结果,搜索用时 0 毫秒
41.
Dive D. Robert S. Angrand E. Bel C. Bonnemain H. Brun L. Demarque Y. Le Du A. El Bouhouti R. Fourmaux M. N. Guery L. Hanssens O. Murat M. 《Hydrobiologia》1989,(1):181-188
A bioassay method using the ciliate protozoan Colpidium campylum is presented in a standardized form. The influence of the initial cell concentration on the potassium dichromate EC50 values was determined. Two intercalibration experiments between two laboratories were performed on ten toxicants in two different conditions. The potassium dichromate EC50 determinations performed by eight different people are also presented. All results are discussed in terms of feasibility and reproducibility of the method, fields of application, and limitations. 相似文献
42.
43.
NSD1 is essential for early post-implantation development and has a catalytically active SET domain 总被引:11,自引:0,他引:11 下载免费PDF全文
Rayasam GV Wendling O Angrand PO Mark M Niederreither K Song L Lerouge T Hager GL Chambon P Losson R 《The EMBO journal》2003,22(12):3153-3163
The nuclear receptor-binding SET domain-containing protein (NSD1) belongs to an emerging family of proteins, which have all been implicated in human malignancy. To gain insight into the biological functions of NSD1, we have generated NSD1-deficient mice by gene disruption. Homozygous mutant NSD1 embryos, which initiate mesoderm formation, display a high incidence of apoptosis and fail to complete gastrulation, indicating that NSD1 is a developmental regulatory protein that exerts function(s) essential for early post-implantation development. We have also examined the enzymatic potential of NSD1 and found that its SET domain possesses intrinsic histone methyltransferase activity with specificity for Lys36 of histone H3 (H3-K36) and Lys20 of histone H4 (H4-K20). 相似文献
44.
A simple assay to determine the functionality of Cre or FLP recombination targets in genomic manipulation constructs. 总被引:4,自引:5,他引:4 下载免费PDF全文
We report the construction of two Escherichia coli strains (294-Cre and 294-FLP) which express either Cre- or FLP-recombinase. Plasmids containing authentic recognition targets for either recombinase (loxPs or FRTs) are recombined when propagated in the appropriate strain. 294-Cre and 294-FLP thus provide a simple test for the recombination competence of constructs that are designed for use in Cre- or FLP-mediated genomic manipulations. 相似文献
45.
Biological control agents (BCAs) composed of attenuated cucumber mosaic (CMV) and its satellite RNA for controlling CMV diseases were found to induce plant resistance to a number of fungal diseases. Tests conducted in both the field and greenhouse showed evident protective effects against fungal infections by the BCAs. Artificial inoculation with a fungal spore suspension using BCA-treated plants, satellite transgenic plants and plants infected with CMV alone indicated that the resistance to fungi was induced by the virus infection, not by the presence of satellite RNA. 相似文献
46.
Bouwmeester T Bauch A Ruffner H Angrand PO Bergamini G Croughton K Cruciat C Eberhard D Gagneur J Ghidelli S Hopf C Huhse B Mangano R Michon AM Schirle M Schlegl J Schwab M Stein MA Bauer A Casari G Drewes G Gavin AC Jackson DB Joberty G Neubauer G Rick J Kuster B Superti-Furga G 《Nature cell biology》2004,6(2):97-105
47.
Does host‐plant diversity explain species richness in insects? A test using Coccidae (Hemiptera) 下载免费PDF全文
1. The megadiverse herbivores and their host plants are a major component of biodiversity, and their interactions have been hypothesised to drive the diversification of both. 2. If plant diversity influences the diversity of insects, there is an expectation that insect species richness will be strongly correlated with host‐plant species richness. This should be observable at two levels (i) more diverse host‐plant groups should harbour more species of insects, and (ii) the species richness of a group of insects should correlate with the richness of the host groups it uses. However, such a correlation is also consistent with a hypothesis of random host use, in which insects encounter and use hosts in proportion to the diversity of host plants. Neither of these expectations has been widely tested. 3. These expectations were tested using data from a species‐rich group of insects – the Coccidae (Hemiptera). 4. Significant positive correlations were found between the species richness of coccid clades (genera) and the species richness of the host‐plant family or families upon which the clades occur. On a global scale, more closely related plant families have more similar communities of coccid genera but the correlation is weak. 5. Random host use could not be rejected for many coccids but randomisation tests and similarity of coccid communities on closely related plant families show that there is non‐random host use in some taxa. Overall, our results support the idea that plant diversity is a driver of species richness of herbivorous insects, probably via escape‐and‐radiate or oscillation‐type processes. 相似文献
48.
A genetic algorithm for maximum-likelihood phylogeny inference using nucleotide sequence data 总被引:4,自引:2,他引:4
Phylogeny reconstruction is a difficult computational problem, because the
number of possible solutions increases with the number of included taxa.
For example, for only 14 taxa, there are more than seven trillion possible
unrooted phylogenetic trees. For this reason, phylogenetic inference
methods commonly use clustering algorithms (e.g., the neighbor-joining
method) or heuristic search strategies to minimize the amount of time spent
evaluating nonoptimal trees. Even heuristic searches can be painfully slow,
especially when computationally intensive optimality criteria such as
maximum likelihood are used. I describe here a different approach to
heuristic searching (using a genetic algorithm) that can tremendously
reduce the time required for maximum-likelihood phylogenetic inference,
especially for data sets involving large numbers of taxa. Genetic
algorithms are simulations of natural selection in which individuals are
encoded solutions to the problem of interest. Here, labeled phylogenetic
trees are the individuals, and differential reproduction is effected by
allowing the number of offspring produced by each individual to be
proportional to that individual's rank likelihood score. Natural selection
increases the average likelihood in the evolving population of phylogenetic
trees, and the genetic algorithm is allowed to proceed until the likelihood
of the best individual ceases to improve over time. An example is presented
involving rbcL sequence data for 55 taxa of green plants. The genetic
algorithm described here required only 6% of the computational effort
required by a conventional heuristic search using tree
bisection/reconnection (TBR) branch swapping to obtain the same
maximum-likelihood topology.
相似文献
49.
April DeLaurier Nicholas Burton Michael Bennett Richard Baldock Duncan Davidson Timothy J Mohun Malcolm PO Logan 《BMC developmental biology》2008,8(1):83