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排序方式: 共有107条查询结果,搜索用时 31 毫秒
1.
O. P. Yadav V. K. Manga G. K. Gupta 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,87(5):558-560
Large-scale cultivation of pearl millet [Pennisetum glaucum (L.) R. Br. F1 hybrids in India has led to increased incidence of downy-mildew (Sclerospora graminicola). There is concern that the A1 male-sterile cytoplasm used in all the hybrids released so far is responsible for this increase. The influence of A1 malesterile cytoplasm on downy-mildew incidence in pearl millet was studied by comparing the disease reaction of 40 pairs of F1 hybrids, each pair carrying respectively a1 male-sterile and normal B cytoplasm. Mean downy-mildew incidence was similar in the hybrids carrying either A1 male-sterile or B cytoplasm. The general combining ability of lines with and without A1 cytoplasm was found to be similar for downy-mildew incidence. These results indicated that in pearl millet A1 cytoplasm is not associated with increased downymildew incidence. The possible danger of using only one source of cytoplasm has been briefly discussed. 相似文献
2.
Guillermo Jiménez Mercedes Urdiain Ana Cifuentes Aránzazu López-López Anicet R. Blanch Javier Tamames Peter Kämpfer Anne-Brit Kolstø Daniel Ramón Juan F. Martínez Francisco M. Codoñer Ramon Rosselló-Móra 《Systematic and applied microbiology》2013
Strain BCT-7112T was isolated in 1966 in Japan from a survey designed to obtain naturally occurring microorganisms as pure cultures in the laboratory for use as probiotics in animal nutrition. This strain, which was primarily identified as Bacillus cereus var toyoi, has been in use for more than 30 years as the active ingredient of the preparation TOYOCERIN®, an additive for use in animal nutrition (e.g. swine, poultry, cattle, rabbits and aquaculture). Despite the fact that the strain was initially classified as B. cereus, it showed significant genomic differences from the type strains of the B. cereus group that were large enough (ANI values below 92%) to allow it to be considered as a different species within the group. The polyphasic taxonomic study presented here provides sufficient discriminative parameters to classify BCT-7112T as a new species for which the name Bacillus toyonensis sp. nov. is proposed, with BCT-7112T (=CECT 876T; =NCIMB 14858T) being designated as the type strain. In addition, a pairwise comparison between the available genomes of the whole B. cereus group by means of average nucleotide identity (ANI) calculations indicated that besides the eight classified species (including B. toyonensis), additional genomospecies could be detected, and most of them also had ANI values below 94%. ANI values were on the borderline of a species definition only in the cases of representatives of B. cereus versus B. thuringiensis, and B. mycoides and B. weihenstephanensis. 相似文献
3.
García-Aljaro C Muniesa M Jofre J Blanch AR 《Applied and environmental microbiology》2004,70(6):3535-3540
Shiga toxin-producing Escherichia coli strains are human pathogens linked to hemorrhagic colitis and hemolytic uremic syndrome. The major virulence factors of these strains are Shiga toxins Stx1 and Stx2. The majority of the genes coding for these toxins are borne by bacteriophages. Free Stx2-encoding bacteriophages have been found in aquatic environments, but there is limited information about the lysogenic strains and bacteria present in the environment that are susceptible to phage infection. The aim of this work was to study the prevalence and the distribution of the stx(2) gene in coliform bacteria in sewage samples of different origins. The presence of the stx(2) gene was monitored every 2 weeks over a 1-year period in a municipal sewage treatment plant. A mean value of 10(2) genes/ml was observed without significant variation during the study period. This concentration was of the same order of magnitude in raw municipal sewage of various origins and in animal wastewater from several slaughterhouses. A total of 138 strains carrying the stx(2) gene were isolated by colony hybridization. This procedure detected approximately 1 gene-carrying colony per 1,000 fecal coliform colonies in municipal sewage and around 1 gene-carrying colony per 100 fecal coliform colonies in animal wastewaters. Most of the isolates belonged to E. coli serotypes other than E. coli O157, suggesting a low prevalence of strains of this serotype carrying the stx(2) gene in the wastewater studied. 相似文献
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D. V. N. Chakravarthi Y. V. Rao M. V. S. Rao V. Manga 《Plant Cell, Tissue and Organ Culture》2010,102(1):87-97
Genetic analysis of four in vitro characters (callus initiation, callus productivity, embryogenic callus percentage, and mean
number of regenerated shoots per callus) was conducted using a 6 × 6 diallel cross among four cultivars of eggplant (Solanum melongena) and two related species (S. indicum, S. surattense) showing different in vitro responses. Among the 30 hybrid families, the in vitro performance exceeded the midparent in 19,
29, 18, and 22 cases, respectively, for callus initiation, callus productivity, embryogenic callus induction, and number of
regenerated shoots. Both additive and dominant effects were significant and additive gene action was predominant for three
of four in vitro characters with the exception of callus productivity. Different degrees of dominance were observed in the
expression of the four characters. The broad and narrow sense heritabilities were 0.97 and 0.82 for callus initiation frequency,
0.99 and 0.42 for total amount of callus, 0.99 and 0.92 for E-callus productivity, and 0.99 and 0.73 for mean number of shoots,
respectively, suggesting that these traits can be easily transferred into economically important cultivars with low tissue
culture response or recalcitrance. 相似文献
7.
Kühn I Iversen A Finn M Greko C Burman LG Blanch AR Vilanova X Manero A Taylor H Caplin J Domínguez L Herrero IA Moreno MA Möllby R 《Applied and environmental microbiology》2005,71(9):5383-5390
Vancomycin-resistant enterococci (VRE) in Europe are thought to have emerged partly due to the use of the glycopeptide avoparcin in animal husbandry. We compared the occurrence of VRE in geographical regions of Europe in which until 1997 large amounts of avoparcin were used (Spain, United Kingdom, and Denmark) with the occurrence of VRE in Sweden, where avoparcin was banned in 1986. We also studied the relatedness between VRE strains from different regions and habitats. In total, 2,580 samples were collected from humans, animals, and the environment (soil, sewage, recipient water). VRE resistant to 20 microg/ml vancomycin were identified in 8.2% of the samples and were found most frequently in raw and treated urban sewage samples (means, 71% and 36% of the samples, respectively), pig manure (17%), and hospital sewage (16%). The proportions of VRE-positive sewage samples were similar in Sweden, Spain, and the United Kingdom, whereas pig feces and manure were more often positive in Spain than in Sweden (30% versus 1%). Most VRE were Enterococcus faecium carrying vanA, and computerized biochemical phenotyping of the isolates of different ecological origins showed a high degree of polyclonality. In conclusion, it seems that animal-associated VRE probably reflect the former use of avoparcin in animal production, whereas VRE in human-associated samples may be a result of antibiotic use in hospitals. Since there seems to be a reservoir of the resistance genes in all countries studied, precautions must be taken to limit the use of antibiotics and antibiotic-like feed additives. 相似文献
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Multiple receptors conformation docking (MRCD) and clustering of dock poses allows seamless incorporation of receptor binding
conformation of the molecules on wide range of ligands with varied structural scaffold. The accuracy of the approach was tested
on a set of 120 cyclic urea molecules having HIV-1 protease inhibitory activity using 12 high resolution X-ray crystal structures
and one NMR resolved conformation of HIV-1 protease extracted from protein data bank. A cross validation was performed on
25 non-cyclic urea HIV-1 protease inhibitor having varied structures. The comparative molecular field analysis (CoMFA) and
comparative molecular similarity indices analysis (CoMSIA) models were generated using 60 molecules in the training set by
applying leave one out cross validation method, rloo2 values of 0.598 and 0.674 for CoMFA and CoMSIA respectively and non-cross validated regression coefficient r2 values of 0.983 and 0.985 were obtained for CoMFA and CoMSIA respectively. The predictive ability of these models was determined
using a test set of 60 cyclic urea molecules that gave predictive correlation (rpred2) of 0.684 and 0.64 respectively for CoMFA and CoMSIA indicating good internal predictive ability. Based on this information
25 non-cyclic urea molecules were taken as a test set to check the external predictive ability of these models. This gave
remarkable out come with rpred2 of 0.61 and 0.53 for CoMFA and CoMSIA respectively. The results invariably show that this method is useful for performing
3D QSAR analysis on molecules having different structural motifs. 相似文献
10.
Luca Ceccato Simona Masiero Dola Sinha Roy Stefano Bencivenga Irma Roig-Villanova Franck Anicet Ditengou Klaus Palme Rüdiger Simon Lucia Colombo 《PloS one》2013,8(6)
Land plants are characterised by haplo-diploid life cycles, and developing ovules are the organs in which the haploid and diploid generations coexist. Recently it has been shown that hormones such as auxin and cytokinins play important roles in ovule development and patterning. The establishment and regulation of auxin levels in cells is predominantly determined by the activity of the auxin efflux carrier proteins PIN-FORMED (PIN). To study the roles of PIN1 and PIN3 during ovule development we have used mutant alleles of both genes and also perturbed PIN1 and PIN3 expression using micro-RNAs controlled by the ovule specific DEFH9 (DEFIFICENS Homologue 9) promoter. PIN1 down-regulation and pin1-5 mutation severely affect female gametophyte development since embryo sacs arrest at the mono- and/or bi-nuclear stages (FG1 and FG3 stage). PIN3 function is not required for ovule development in wild-type or PIN1-silenced plants. We show that sporophytically expressed PIN1 is required for megagametogenesis, suggesting that sporophytic auxin flux might control the early stages of female gametophyte development, although auxin response is not visible in developing embryo sacs. 相似文献