排序方式: 共有71条查询结果,搜索用时 218 毫秒
41.
O. S. Oparina I. A. Kondratenkov M. L. Oparin A. B. Mamaev L. S. Trofimova 《Biology Bulletin》2016,43(10):1428-1433
The results of our study of the abundance dynamics of the great bustard population in the southern part of the Saratov Trans-Volga region for the period from 1998 to 2015 are presented on the basis of censuses carried out before the migration for wintering in the fall and on leks in the spring. The abundance dynamics was analyzed, and the factors causing it were identified. Data on the distribution of the great bustard population density over an account area of 12000 km2 are presented. 相似文献
42.
Class-1 polypeptide chain release factors (RF) induce peptidyl-tRNA hydrolysis in the ribosome if any of the three stop codons
encounters the ribosomal A site. We have shown earlier that all factors of this class possess a common functionally essential
motif GGQ. In this study we analyzed the primary structures of all known class-1 factors taken from the data banks together
with the experimental data available on their structural and functional organization. The following conclusions were drawn.
1. Amino acid sequences of eukaryotic and archaebacterial factors (eRF1 and aRF1, respectively) show high similarity. This
suggests the potential ability of eRF1 to function in archaebacterial and aRF1 in eukaryotic ribosomes, and points to their
origin from a common ancestor. 2. Primary structures of class-1 release factors from prokaryotes and enkaryotic mitochondria
show no statistically significant similarity with archaebacterial and cytoplasmic eukaryotic release factors, except for a
common motif GGQ. This confirms our earlier conclusion (Nature, 1994, vol. 372, pp. 701–703) and contradicts the hypothesis of Itoet al. (Proc. Natl. Acad. Sci. USA, 1996, vol. 93, pp. 5443–5448) about structural similarity of all class-1 release factors. 3. All the eRF1/aRF1 recognizing
three stop codons have a common motif NIKs that is absent from eubacterial RF1 and RF2, each of which is able to recognize
two stop codons of the three. We suppose that the function of the NIKs motif is to fix the proper orientation of eRF1/aRF1
at the ribosome. 4. The domain structure and functional properties of eRF1/aRF1 point to the similarity of these factors with
suppressor tRNAs as suggested long ago, and also semblance with aminoacyl-tRNA synthetases. 5. Considering that peptidyl-tRNA
is fixed at the ribosomal P site while the stop codon and termination factor are at the A site, it may be presumed that the
distance between the functionally essential motifs NIKs and GGQS in eRF1/aRF1 should approximately correspond to the distance
between the anticodon and the aminoacyl end of aminoacyl-tRNA located at the ribosomal A site. 相似文献
43.
Maria S. Zharkova Boris N. Sobolev Nina Yu. Oparina Alexander V. Veselovsky Alexander I. Archakov 《Journal of molecular recognition : JMR》2013,26(2):86-91
Cytochromes P450 comprise a large superfamily and several of their isoforms play a crucial role in metabolism of xenobiotics, including drugs. Although these enzymes demonstrate broad and cross‐substrate specificity, different cytochrome P450 subfamilies exhibit certain selectivity for some types of substrates. Analysis of amino acid residues of the active sites of six cytochrome subfamilies (CYP1А, CYP2А, CYP2С, CYP2D, CYP2E and CYP3А) enables to define subfamily‐specific patterns that consist of four residues. These residues are located on the periphery of the active sites of these cytochromes. We suggest that they can form a primary binding site at the entrance to the active site, defining cytochrome substrate recognition. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
44.
45.
The impact of plowing on the bird and mammal faunas of steppe landscapes is considered using the example of steppes in the Saratov Region. It is shown that the faunas of ground-nesting birds and small mammals in crop-rotation fields represent impoverished variants of the same faunas in natural steppe land-scapes with their characteristic diversity of habitats. As a rule, dominance in the fields belongs to bird and mammal species that, prior to extensive plowing of the steppes, inhabited intrazonal landscape elements. Only a few species characteristic of zonal steppe habitats have adapted to living in crop-rotation fields. 相似文献
46.
47.
48.
A. V. Kudriavtseva E. A. Anedchenko N. Yu. Oparina G. S. Krasnov K. N. Kashkin A. A. Dmitriev I. B. Zborovskaya T. T. Kondratjeva E. V. Vinogradova M. V. Zinovyeva E. P. Kopantsev V. N. Senchenko 《Molecular Biology》2009,43(6):972-981
Numerous human cancers are accompanied with the increase of ferritin content in blood serum. Ferritin is composed of light and heavy chains, encoded by FTL and FTH genes, respectively. The analysis of EST database showed that the expression of FTL and FTH genes in lung tumors is decreased compared to normal tissues, and is not altered in renal cancer cells. The alteration of mRNA corresponding to FTL and FTH genes was estimated by real-time PCR in primary lung and kidney tumors. A significant and frequent inhibition of FTL and FTH gene expression (on average by 11 and 9 times, in 83% (33/40) and 73% (11/15) of cases, respectively) was detected in primary squamous lung carcinoma. The expression of these genes was not altered so significantly (by 6 and 3 times, in 58% and 27% of samples) in clear cell renal cell carcinoma. Our work reports for the first time the down-regulation of FTL gene expression at the first stage of lung cancer (10/10), and proposes this gene as a potential oncomarker for early diagnosis. The FTL mRNA content may be quantified by non-competitive hybridization on expression DNA microarrays. The possible causes of a serum ferritin increase in lung squamous cell carcinoma and clear cell renal cell carcinoma are discussed. 相似文献
49.
K. D. Taganov A. E. Gushchin T. A. Akopian N. Yu. Oparina N. Yu. Abramycheva V. M. Govorun 《Molecular Biology》2000,34(2):256-262
A 5-kb region of theAcholeplasma laidlawii PG-8B genome was sequenced. The region contained the genes for RecF, DNA gyrase subunits A and B (GyrA and GyrB), and a fragment
of the ATP-binding subunit of the hypothetical ABC transporter. In phylogenetic analysis,A. laidlawii GyrA and GyrB formed statistically significant, stable clusters with the corresponding proteins ofClostridium acetobutylicum, Staphylococcus aureus, Bacillus subtilis, andStreptococcus pneumoniae. A laidlawii PG-8B clones resistant to fluoroquinolone (FQ) antibiotic ciprofloxacin (Cff) were obtained on a selective medium. The clones
carried mutations in the quinolone resistance-determining region (QRDR) ofgyrA, which resulted in substitutions Ser83→Ala, Ser83→Phe, or Asp91→Asn. No mutations were found ingyrB QRDR of the resistant clones. 相似文献
50.