排序方式: 共有47条查询结果,搜索用时 296 毫秒
31.
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32.
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
33.
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
34.
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35.
Heather R. Spence Ali M. Aslam Myron A. Hofer Susan A. Brunelli Harry N. Shair 《Ecology and evolution》2016,6(7):1922-1929
Selective breeding and natural selection that select for one trait often bring along other correlated traits via coselection. Selective breeding for an infantile trait, high or low call rates of isolation‐induced ultrasonic vocalization of rat pups, also alters functions of some brain systems and emotional behaviors throughout life. We examined the effect of breeding for call rate on acoustic parameters that are of communicative significance. Selecting for higher call rate produced calls of significantly increased amplitude and bandwidth relative to a randomly bred line. Selecting for lower rate produced calls of decreased duration. These nonmorphological, functional trait changes demonstrate enhanced communicatory potential and energy expenditure for the High line and the opposite for the Low line. This demonstration of coselection in a communicatory system suggests an underlying heritable suite of linked acoustic vocalization characteristics that in noisy environments could enhance dam–pup communication and lead to selection of emotionality traits with beneficial responses to stress. 相似文献
36.
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)
37.
Burgett AW Poulsen TB Wangkanont K Anderson DR Kikuchi C Shimada K Okubo S Fortner KC Mimaki Y Kuroda M Murphy JP Schwalb DJ Petrella EC Cornella-Taracido I Schirle M Tallarico JA Shair MD 《Nature chemical biology》2011,7(9):639-647
Cephalostatin 1, OSW-1, ritterazine B and schweinfurthin A are natural products that potently, and in some cases selectively, inhibit the growth of cultured human cancer cell lines. The cellular targets of these small molecules have yet to be identified. We have discovered that these molecules target oxysterol binding protein (OSBP) and its closest paralog, OSBP-related protein 4L (ORP4L)--proteins not known to be involved in cancer cell survival. OSBP and the ORPs constitute an evolutionarily conserved protein superfamily, members of which have been implicated in signal transduction, lipid transport and lipid metabolism. The functions of OSBP and the ORPs, however, remain largely enigmatic. Based on our findings, we have named the aforementioned natural products ORPphilins. Here we used ORPphilins to reveal new cellular activities of OSBP. The ORPphilins are powerful probes of OSBP and ORP4L that will be useful in uncovering their cellular functions and their roles in human diseases. 相似文献
38.
Occurrence of Vibrio cholerae in Municipal and Natural Waters and Incidence of Cholera in Azerbaijan
Gurbanov S Akhmadov R Shamkhalova G Akhmadova S Haley BJ Colwell RR Huq A 《EcoHealth》2011,8(4):468-477
Cholera, a waterborne disease caused by Vibrio cholerae, is an autochthonous member of the aquatic environment and predominantly reported from developing countries. Technical reports and proceedings were reviewed to determine the relationship between occurrence of V. cholerae in natural waters, including sources of municipal water, and cases of cholera in Azerbaijan. Water samples collected from different environmental sources from 1970 to 1998 were tested for V. cholerae and 0.73% (864/117,893) were positive. The results showed that in April of each year, when the air temperature rose by approximately 5°C, V. cholerae could be isolated. With each increase in air temperature, 6-8 weeks after, impact on cases of cholera was recorded. The incidence of cholera peaked when the air temperature reached >25°C during the month of September. It is concluded that a distinct seasonality in cholera incidence exists in Azerbaijan, with increased occurrence during warmer months. 相似文献
39.
Latent membrane protein 1 (LMP1) is the major oncoprotein of Epstein-Barr virus (EBV). In transgenic mice, LMP1 promotes increased lymphoma development by 12 mo of age. This study reveals that lymphoma develops in B-1a lymphocytes, a population that is associated with transformation in older mice. The lymphoma cells have deregulated cell cycle markers, and inhibitors of Akt, NFkappaB, and Stat3 block the enhanced viability of LMP1 transgenic lymphocytes and lymphoma cells in vitro. Lymphoma cells are independent of IL4/Stat6 signaling for survival and proliferation, but have constitutively activated Stat3 signaling. These same targets are also deregulated in wild-type B-1a lymphomas that arise spontaneously through age predisposition. These results suggest that Akt, NFkappaB, and Stat3 pathways may serve as effective targets in the treatment of EBV-associated B cell lymphomas. 相似文献
40.
Soumaya Kilani Ines Bouhlel Ribai Ben Ammar Mohamed Ben Shair Ines Skandrani Jihed Boubaker Amor Mahmoud Marie-Geneviève Dijoux-Franca Kamel Ghedira Leila Chekir-Ghedira 《Annals of microbiology》2007,57(4):657-664
The mutagenic potential of aqueous, Total Oligomers Flavonoids (TOF), ethyl acetate, and methanol extracts as well as essential oil (EO) obtained from tubers ofCyperus rotundus L. was assessed by “Ames assay”, usingSalmonella tester strains TA98 and TA100, and “SOS chromotest” usingEscherichia coli PQ37 strain with and without an exogenous metabolic activation system (S9). None of the different extracts showed a mutagenic effect. Likewise, the antimutagenicity of the same extracts was tested using the “Ames test” and the “SOS chromotest”. Our results showed thatC. rotundus extracts have antimutagenic effects withSalmonella typhimurium TA98 and TA100 strains towards the mutagen Aflatoxin B1 (AFB1), as well as withE. coli PQ37 strain against AFB1 and nifuroxazide mutagens. A free radical scavenging test was used in order to explore the antioxidant capacity of the extracts obtained from the tubers ofC. rotundus. TOF, ethyl acetate and methanol extracts showed an important free radical scavenging activity towards the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. These extracts showed IC50 values of respectively 5, 20 and 65 μg/ml. The beneficial effects of TOF, ethyl acetate, methanol and essential oil extracts ofC. rotundus have been assessed by antioxidant and antimutagenic activities. 相似文献