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排序方式: 共有70条查询结果,搜索用时 62 毫秒
1.
Biology Bulletin - Abstract—The results of the study of 23 natural cenopopulations of Cephalaria uralensis (Murr.) Schrad. ex Roem. et Schult., a rare subendemic species of the Eastern... 相似文献
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Data on the structural organization and evolutionary role of specific bacterial DNA regions known as genomic islands are reviewed. Emphasis is placed on the most extensively studied genomic islands, pathogenicity islands (PAIs), which are present in the chromosome of Gram-negative and Gram-positive pathogenic bacteria and absent from related nonpathogenic strains. PAIs are long DNA regions that harbor virulence genes and often differ in GC content from the remainder of the bacterial genome. Many PAI occur in the tRNA gene loci, which provide a convenient target for foreign gene insertion. Some PAI are highly homologous to each other and contain sequences similar to ISs, phage att sites, and plasmid ori sites, along with functional or defective integrase and transposase genes, suggesting horizontal transfer of PAI among bacteria. 相似文献
4.
G. A. Velikanov A. A. Ponomareva L. P. Belova T. M. Ilyina 《Cell and Tissue Biology》2011,5(3):305-310
The work presents the results of the electron-microscopy visualization of stromule-like protrusions of plastid membrane envelope
in root cells. Cases of the appearance of a long, narrow protrusion of the outer membrane, in which the shorter protrusion
of the plastid envelope inner membrane was located, are discussed. The possible role of cytoskeleton and plastoskeleton in
formation of outer and inner protrusions, respectively, is considered. It is concluded that items of the structure and functions
of stromules in plant cells are to be considered to be the same as the structure and functions of the intracavity space of
endoplasmic reticulum. 相似文献
5.
Replication slippage may cause parallel evolution in the secondary structures of mitochondrial transfer RNAs 总被引:9,自引:4,他引:5
Presence of the dihydrouridine (D) stem in the mitochondrial cysteine tRNA
is unusually variable among lepidosaurian reptiles. Phylogenetic and
comparative analyses of cysteine tRNA gene sequences identify eight
parallel losses of the D-stem, resulting in D-arm replacement loops.
Sampling within the monophyletic Acrodonta provides no evidence for
reversal. Slipped-strand mispairing of noncontiguous repeated sequences
during replication or direct replication slippage can explain repeats
observed within cysteine tRNAs that contain a D-arm replacement loop. These
two mechanisms involving replication slippage can account for the loss of
the cysteine tRNA D-stem in several lepidosaurian lineages, and may
represent general mechanisms by which the secondary structures of
mitochondrial tRNAs are altered.
相似文献
6.
N.?S.?Katina E.?I.?Grigorashvili M.?Yu.?Suvorina N.?B.?Ilyina N.?A.?Ryabova O.?M.?Selivanova A.?K.?SurinEmail author 《Molecular Biology》2018,52(1):42-51
As has been recently shown, the toxicity of protein aggregates is determined by their structure. Therefore, special attention has been focused on the search for factors that specify the structural features of formed amyloid fibrils. The effect of amino acid substitutions in apomyoglobin on the structural characteristics of its amyloid aggregates has been analyzed. The morphology and secondary structure of amyloids of the wild-type protein and its mutant variants Val10Ala, Val10Phe, and Trp14Phe have been compared, and the regions involved in intermolecular interactions in fibrils have been determined using limited proteolysis and mass spectrometry. No considerable differences have been found in the morphology (shape, length, or diameter) or the content (percentage) of the cross-β structure of apomyoglobin amyloids and its mutant variants. Amyloid cores of wild-type apomyoglobin and variants with Val10Phe and Trp14Phe substitutions have been formed by different regions of the polypeptide chain. The case study of apomyoglobin demonstrates that the location of amyloidogenic regions in the polypeptide chain of wild-type protein and its mutant forms can differ. Thus, possible structural changes in amyloids resulting from amino acid substitutions should be taken into account when studying phenotype aggregation. 相似文献
7.
B. Ts. Shagdarova A. V. Ilyina S. A. Lopatin M. I. Kartashov L. R. Arslanova V. G. Dzhavakhiya V. P. Varlamov 《Applied Biochemistry and Microbiology》2018,54(1):71-75
Chitosan hydrolyzate containing low-molecular-weight chitosan (≤24 kDa) and its oligomers (≤1.2 kDa) has been obtained via chemical depolimerization of high-molecular-weight chitosan by nitric acid. The fractions of the obtained chitosan hydrolyzate have been characterized by high performance gel permeation chromatography and proton magnetic resonance. The test performed on detached leaves of wheat has shown that the hydrolyzate completely inhibits the development of Stagonospora nodorum, a casual agent of the septoria leaf blotch, at a concentration of 200 μg/mL. A similar test with detached tobacco leaves has shown that the hydrolyzate at a concentration of 100 μg/mL also inhibits the development of Alternaria longipes, which causes brown spot of tobacco, by 75%. 相似文献
8.
Anvar B. Kerimov Tatyana A. Ilyina Elena V. Ivankina Andrey V. Bushuev Olga V. Sokolova Konstantin A. Rogovin 《Evolutionary ecology》2018,32(1):89-111
A specific interest in the persistence of color polymorphism in some populations of birds and other vertebrates is often linked to ideas about the signaling honesty of bright coloration. The evolution of conspicuous ornamentation could be associated with physiological costs including limitations of the immune system. The study of this process is crucial for an understanding of the maintenance of polymorphic coloration. Here we summarized the results of a study of a pied flycatcher population from the Moscow region (Russia) in 2010–2013. We experimentally induced antibody production by injecting sheep red blood cells (SRBC) and inflammatory swelling by injecting phytohaemagglutinin (PHA) after which we estimated the immune response in breeding males. We used leucocytes-to-erythrocytes and heterophils-to-lymphocytes (H/L) ratios as indicators of infectious, inflammatory processes and stress. The results showed that the feeding rates of males treated with SRBC decreased and negatively related to the intensity of their immune responses. Non-molting males of different color types did not significantly differ in antibody production. Among molting breeders, the immune response to SRBC was significantly higher in pale males than in bright ones with rich melanin-based coloration. In contrast to non-molting males, molting pale males had an increased antibody titer after immunization. The lower humoral immune response was associated with the higher H/L stress index before immunization. The change in H/L after immunization positively correlated with the intensity of the humoral immune response. As opposed to humoral immunity, we did not find any significant predictors, including coloration, molt, or their two-way interaction, to explain the variation in cutaneous inflammatory response to PHA. The results suggest that the apparent advantage of a cryptic male phenotype over a conspicuous phenotype occurring in one of two types of immune response has an impact on the maintenance of color polymorphism in the pied flycatcher. 相似文献
9.
Olga Zakharova Olga Luzina Alexandra Zakharenko Dmitry Sokolov Alexandr Filimonov Nadezhda Dyrkheeva Arina Chepanova Ekaterina Ilina Anna Ilyina Kristina Klabenkova Boris Chelobanov Dmitry Stetsenko Ayesha Zafar Chatchakorn Eurtivong Jóhannes Reynisson Konstantin Volcho Nariman Salakhutdinov Olga Lavrik 《Bioorganic & medicinal chemistry》2018,26(15):4470-4480
Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is a repair enzyme for stalled DNA-topoisomerase 1 (Top 1) cleavage complexes and other 3′-end DNA lesions. Tdp1 is a promising target for anticancer therapy, since it can repair DNA lesions caused by Top1 inhibitors leading to drug resistance. Hence, Tdp1 inhibition should result in synergistic effect with Top1 inhibitors. Twenty nine derivatives of (+)-usnic acid were tested for in vitro Tdp1 inhibitory activity using a fluorescent-based assay. Excellent activity was obtained, with derivative 6m demonstrating the lowest IC50 value of 25?nM. The established efficacy was verified using a gel-based assay, which gave close results to that of the fluorescent assay. In addition, molecular modeling in the Tdp1 substrate binding pocket suggested plausible binding modes for the active analogues. The synergistic effect of the Tdp1 inhibitors with topotecan, a Top1 poison in clinical use, was tested in two human cell lines, A-549 and HEK-293. Compounds 6k and 6x gave very promising results. In particular, 6x has a low cytotoxicity and an IC50 value of 63?nM, making it a valuable lead compound for the development of potent Tdp1 inhibitors for clinical use. 相似文献
10.
The complete cDNA sequence and protein reading frame of a developmentally
regulated hemocyanin subunit in the Dungeness crab (Cancer magister) is
presented. The protein sequence is aligned with 18 potentially homologous
hemocyanin-type proteins displaying apparent sequence similarities.
Functional domains are identified, and a comparison of predicted
hydrophilicities, surface probabilities, and regional backbone
flexibilities provides evidence for a remarkable degree of structural
conservation among the proteins surveyed. Parsimony analysis of the protein
sequence alignment identifies four monophyletic groups on the arthropodan
branch of the hemocyanin gene tree: crustacean hemocyanins, insect
hexamerins, chelicerate hemocyanins, and arthropodan prophenoloxidases.
They form a monophyletic group relative to molluscan hemocyanins and
nonarthropodan tyrosinases. Arthropodan prophenoloxidases, although
functionally similar to tyrosinases, appear to belong to the arthropodan
hexamer- type hemolymph proteins as opposed to molluscan hemocyanins and
tyrosinases.
相似文献