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排序方式: 共有157条查询结果,搜索用时 484 毫秒
91.
Atanasova I Kabadjova P Bogatzevska N Moncheva P 《Zeitschrift für Naturforschung. C, Journal of biosciences》2005,60(11-12):893-898
Nine strains of Erwinia amylovora were isolated from new host plants in Bulgaria--chokeberry and strawberry. The strains were characterized morphologically and biochemically using the API 20E and BIOLOG system. It was established that they showed three different API 20E metabolic profiles, not found by previous studies of E. amylovora. All strains were identified as E. amylovora due to their metabolic fingerprint patterns obtained by the BIOLOG system. The identification was confirmed by PCR amplification of a specific region of plasmid pEA29 and genome ams-region. This study is the first characterization and identification of E. amylovora strains isolated from chokeberry and strawberry by the API 20E and BIOLOG system and by polymerase chain reaction. 相似文献
92.
Nikolić Radomirka Mitić Nevena Nešković Mirjana 《Plant Cell, Tissue and Organ Culture》1997,48(1):67-69
Two newly selected Lotus corniculatus cultivars (Bokor and Zora), introduced recently as pasture legumes, were studied with respect to their in vitro regeneration capacity and field performance of R1 regenerates. Multiple buds were induced in callus tissues derived from apical buds, petioles, leaf and cotyledon explants. The rooted regenerates, acclimated in a greenhouse, were fertile. Seeds from the R1 generation were sown in the field and the plants found to be superior to controls in stem height and green mass production. 相似文献
93.
Morana Dulic Nevena Cvetesic Igor Zivkovic Andrés Palencia Stephen Cusack Branimir Bertosa Ita Gruic-Sovulj 《Journal of molecular biology》2018,430(1):1-16
The intrinsic editing capacities of aminoacyl-tRNA synthetases ensure a high-fidelity translation of the amino acids that possess effective non-cognate aminoacylation surrogates. The dominant error-correction pathway comprises deacylation of misaminoacylated tRNA within the aminoacyl-tRNA synthetase editing site. To assess the origin of specificity of Escherichia coli leucyl-tRNA synthetase (LeuRS) against the cognate aminoacylation product in editing, we followed binding and catalysis independently using cognate leucyl- and non-cognate norvalyl-tRNALeu and their non-hydrolyzable analogues. We found that the amino acid part (leucine versus norvaline) of (mis)aminoacyl-tRNAs can contribute approximately 10-fold to ground-state discrimination at the editing site. In sharp contrast, the rate of deacylation of leucyl- and norvalyl-tRNALeu differed by about 104-fold. We further established the critical role for the A76 3′-OH group of the tRNALeu in post-transfer editing, which supports the substrate-assisted deacylation mechanism. Interestingly, the abrogation of the LeuRS specificity determinant threonine 252 did not improve the affinity of the editing site for the cognate leucine as expected, but instead substantially enhanced the rate of leucyl-tRNALeu hydrolysis. In line with that, molecular dynamics simulations revealed that the wild-type enzyme, but not the T252A mutant, enforced leucine to adopt the side-chain conformation that promotes the steric exclusion of a putative catalytic water. Our data demonstrated that the LeuRS editing site exhibits amino acid specificity of kinetic origin, arguing against the anticipated prominent role of steric exclusion in the rejection of leucine. This feature distinguishes editing from the synthetic site, which relies on ground-state discrimination in amino acid selection. 相似文献
94.
Ljiljana Radojevic Nevena Marinkovic Sladjana Jervremovic 《In vitro cellular & developmental biology. Plant》2000,36(6):464-469
Summary Flowers of Aesculus hippocastanum L. are bisexual and zygomorphic, and are positioned on a 20–30 cm long inflorescence. Those located in the basal part of
the panicle are female and fertile (segment A), flowers in the middle are bisexual (segment B), and those on top of the panicle
are male (segment C). Androgenesis was achieved in anther culture which originated from three types of flowers cultured on
modified Murashige and Skoog medium containing 2,4-dichlorophenoxyacetic acid (4.5 μM) and kinetin (4.6 μM). Differences in viability of uninuclear microspores were found between female (90.0%) and other flowers (bisexual 61.1%;
male 72.7%.). Both the percentage of embryogenic anthers and the number of androgenic embryos formed per inflorescence differed
according to the segment of origin. The highest embryogenic response was obtained in segment A (47.3%) and the lowest in segment
C (24.1%). A significant difference was found between the number of androgenic embryos formed per inflorescence in segments
A (921.0) and C (286.7). The highest germination percentage (21.3%) and plantelet formation (41.0%) were obtained on woody
plant WPM liquid medium supplemented with 1% activated charcoal. Acclimation and regeneration were best from plantelets originating
from female flowers (62.5%). Plantlets originating from bisexual and male flowers have much poorer survival (29.3 and 22.2%,
respectively). 相似文献
95.
Violeta Georgieva Sotirova Nevena Stojanova Bogatsevska 《Acta Physiologiae Plantarum》2000,22(3):256-259
Thirty six tomato wild species accessions of the subgenera Eulycopersicon and Eriopersicon of the genus Lycopersicon were inoculated with race T1 and T3 of Xanthomonas vesicatoria by vaccum infiltration method. Degree of diseases was evaluated by scale of 0 to 4. It was established that some accessions
showed low degree of disease to race T1 and others to race T3. LA 2623 indicated very low degree of disease to race T1 and
was immune in inoculation with T3. LA 386 and LA 1297 manifested hypersensitive reaction to both races and PI 127826 to race
T3 only. The accessions possessing low degree of disease or hypersensitive reaction to race T1 and race T3 are new promising
sources of resistance to Xanthomonas vesicatoria. 相似文献
96.
97.
98.
Nevena Grdovi? Melita Vidakovi? Mirjana Mihailovi? Svetlana Dini? Aleksandra Uskokovi? Jelena Arambaši? Goran Poznanovi? 《Cryobiology》2010,60(3):271-280
Although cryosurgery is attaining increasing clinical acceptance, our understanding of the mechanisms of cryogenic cell destruction remains incomplete. While it is generally accepted that cryoinjured cells die by necrosis, the involvement of apoptosis was recently shown. Our studies of liver cell death by cryogenic temperature revealed the activation of endonuclease p23 and its de novo association with the nuclear matrix. This finding is strongly suggestive of a programmed-type of cell death process. The presumed order underlying cryonecrotic cell death is addressed here by examining the mechanism of p23 activation. To that end, nuclear proteins that were prepared from fresh liver, which is devoid of p23 activity, were incubated with protein fractions isolated from liver exposed to freezing/thawing that possessed a presumed p23 activation factor. We observed that the activation of p23 was the result of a proteolytic event in which cathepsin D played a major role. Different patterns of proteolytic cleavage of nuclear proteins after in vitro incubation of nuclei and in samples isolated from frozen/thawed liver were observed. Although both processes induced p23 activation, the incubation experiments generated proteolytic hallmarks of apoptosis, while freezing/thawing of whole liver resulted in typical necrotic PARP-1 cleavage products and intact lamin B. As an explanation we offer a hypothesis that after freezing, cells possess the potential to die through necrotic as well as apoptotic mechanisms, based on our finding that the cytosol of cells exposed to cryogenic temperatures contains both necrotic and apoptotic executors of cell death. 相似文献
99.
The Informational Spectrum Method (ISM) is the tool for the in silico analysis of proteins which interprets protein sequence linear information using signal analyses methods. In this paper the ISM was employed to characterize the products of genetic variants of tumor suppressor gene p53 and its natural binding regulator protein Mdm2. Based on this we propose the criterion for identification of missense mutations that have impact on the p53-Mdm2 feedback loop. The efficiency of the proposed criterion was confirmed by the ISM analyses of p53 mutants reported in: (i) healthy individuals, (ii) germline mutations database and (iii) somatic mutations database. 相似文献
100.
Lee KL Behnke ML Foley MA Chen L Wang W Vargas R Nunez J Tam S Mollova N Xu X Shen MW Ramarao MK Goodwin DG Nickerson-Nutter CL Abraham WM Williams C Clark JD McKew JC 《Bioorganic & medicinal chemistry》2008,16(3):1345-1358
The synthesis and structure-activity relationship of a series of benzenesulfonamide indole inhibitors of cPLA(2)alpha are described. Substitution of the benzenesulfonamide led to analogues with 50-fold improvement in potency versus the unsubstituted benzenesulfonamide lead compound. Rat pharmacokinetics in a minimal formulation was used to prioritize compounds, leading to the discovery of a potent inhibitor of cPLA(2)alpha with oral efficacy in models of rat carrageenan paw edema and Ascaris suum airway challenge in naturally sensitized sheep. 相似文献