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排序方式: 共有258条查询结果,搜索用时 31 毫秒
1.
Tetiana Gren Bohdan Ostash Yaroslav Hrubskyy Stepan Tistechok Victor Fedorenko 《Folia microbiologica》2014,59(2):147-153
Bacteria-assisted bioremediation is widely recognized as a low-cost method to minimize the consequences of soil pollution with toxic metals originating from industrial sites. Strains used in bioremediation have to deal with high metal load via biosorption, reduction, bioprecipitation, metal sequestration, and/or chelation. Actinobacteria, and streptomycetes in particular, are considered a perspective group for bioremediation as natural soil inhabitants with extensive secondary metabolism. Nevertheless, there is no reference information on survival of the model streptomycetes in the presence of the most abundant metal pollutants. Also, there are no reports describing the selection approaches towards improvement of bioremediation properties. In this work, the resistance of Streptomyces coelicolor M145 and Streptomyces sioyaensis Lv81 to certain transition metals and their growth under different pH values are described for the first time. Spontaneous chromate-resistant S. sioyaensis Lv81-138 strain was selected in the course of this work. Strain Lv81-138 is the most efficient actinobacterial Cr(VI) reducer reported so far, capable of converting 12 mmol/L of Cr(VI) into Cr(III) in a medium supplemented with 50 mmol/L K2CrO4. 相似文献
2.
Tarun Ghose Soldano Ferrone A. Huntley Blair Yaroslav Kralovec Massimo Temponi Mandip Singh Moll Mammen 《Cancer immunology, immunotherapy : CII》1991,34(2):90-96
Summary Intravenous injections into nude mice of 5 mg/kg methotrexate (MTX) linked to the antibody to human high molecular weight-melanoma associated antigen (HMW-MAA), monoclonal antibody (mAb) 225.28, an IgG2a, on days 1, 4, 7, 10 and 14, starting 24 h after subcutaneous inoculation of 2 × 106 cultured human M21 melanoma cells inhibited mean tumor volume by 90% on day 14 and by 65% on day 50 after the beginning of the treatment. Injections of equimolar amounts of free MTX and MTX linked to normal mouse IgG or to an isotypematched myeloma protein did not inhibit tumor growth significantly. MTX linked to mAb 225.28 did not inhibit the xenograft of a subline of human melanoma cell line M21 without detectable expression of HMW-MAA. In a clonogenic assay, the MTX-225.28 conjugate was three times more potent in inhibiting the growth of M21 melanoma cells than free MTX, but did not inhibit the growth of kidney carcinoma cells Caki-1, which do not express high-M
r MAA. In contrast, MTX linked to the mAb DAL K29, reacting with kidney carcinoma cells Caki-1, inhibited their growth but did not affect that of melanoma cells. M21 melanoma cells isolated from the residual tumor of a mouse treated with the MTX-225.28 conjugate did not differ in their reactivity with mAb 225.28 and in their sensitivity to MTX when compared with M21 cells from an untreated mouse. 相似文献
3.
Understanding community saturation is fundamental to ecological theory. While investigations of the diversity of evolutionary stable states (ESSs) are widespread, the diversity of communities that have yet to reach an evolutionary endpoint is poorly understood. We use Lotka–Volterra dynamics and trait-based competition to compare the diversity of randomly assembled communities to the diversity of the ESS. We show that, with a large enough founding diversity (whether assembled at once or through sequential invasions), the number of long-time surviving species exceeds that of the ESS. However, the excessive founding diversity required to assemble a saturated community increases rapidly with the dimension of phenotype space. Additionally, traits present in communities resulting from random assembly are more clustered in phenotype space compared to random, although still markedly less ordered than the ESS. By combining theories of random assembly and ESSs we bring a new viewpoint to both the saturation and random assembly literature. 相似文献
4.
The quest for evolutionary mechanisms providing separation between the coding (exons) and noncoding (introns) parts of genomic DNA remains an important focus of genetics. This work combines an analysis of the most recent achievements of genomics and fundamental concepts of random processes to provide a novel point of view on genome evolution. Exon sizes in sequenced genomes show a lognormal distribution typical of a random Kolmogoroff fractioning process. This implies that the process of intron incretion may be independent of exon size, and therefore could be dependent on intron-exon boundaries. All genomes examined have two distinctive classes of exons, each with different evolutionary histories. In the framework proposed in this article, these two classes of exons can be derived from a hypothetical ancestral genome by (spontaneous) symmetry breaking. We note that one of these exon classes comprises mostly alternatively spliced exons. 相似文献
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Bilge Argunhan Sarah Farmer Wing-Kit Leung Yaroslav Terentyev Neil Humphryes Tomomi Tsubouchi Hiroshi Toyoizumi Hideo Tsubouchi 《PloS one》2013,8(6)
Meiotic recombination plays an essential role in the proper segregation of chromosomes at meiosis I in many sexually reproducing organisms. Meiotic recombination is initiated by the scheduled formation of genome-wide DNA double-strand breaks (DSBs). The timing of DSB formation is strictly controlled because unscheduled DSB formation is detrimental to genome integrity. Here, we investigated the role of DNA damage checkpoint mechanisms in the control of meiotic DSB formation using budding yeast. By using recombination defective mutants in which meiotic DSBs are not repaired, the effect of DNA damage checkpoint mutations on DSB formation was evaluated. The Tel1 (ATM) pathway mainly responds to unresected DSB ends, thus the sae2 mutant background in which DSB ends remain intact was employed. On the other hand, the Mec1 (ATR) pathway is primarily used when DSB ends are resected, thus the rad51 dmc1 double mutant background was employed in which highly resected DSBs accumulate. In order to separate the effect caused by unscheduled cell cycle progression, which is often associated with DNA damage checkpoint defects, we also employed the ndt80 mutation which permanently arrests the meiotic cell cycle at prophase I. In the absence of Tel1, DSB formation was reduced in larger chromosomes (IV, VII, II and XI) whereas no significant reduction was found in smaller chromosomes (III and VI). On the other hand, the absence of Rad17 (a critical component of the ATR pathway) lead to an increase in DSB formation (chromosomes VII and II were tested). We propose that, within prophase I, the Tel1 pathway facilitates DSB formation, especially in bigger chromosomes, while the Mec1 pathway negatively regulates DSB formation. We also identified prophase I exit, which is under the control of the DNA damage checkpoint machinery, to be a critical event associated with down-regulating meiotic DSB formation. 相似文献
8.
Evgenia V. Dolgova Yaroslav R. Efremov Konstantin E. Orishchenko Oleg M. Andrushkevich Ekaterina A. Alyamkina Anastasia S. Proskurina Sergey I. Bayborodin Valeriy P. Nikolin Nelly A. Popova Elena R. Chernykh Alexandr A. Ostanin Oleg S. Taranov Vladimir V. Omigov Alexandra M. Minkevich Vladimir A. Rogachev Sergey S. Bogachev Mikhail A. Shurdov 《Gene》2013
We previously reported that fragments of exogenous double-stranded DNA can be internalized by mouse bone marrow cells without any transfection. Our present analysis shows that only 2% of bone marrow cells take up the fragments of extracellular exogenous DNA. Of these, ~ 45% of the cells correspond to CD34 + hematopoietic stem cells. Taking into account that CD34 + stem cells constituted 2.5% of the total cell population in the bone marrow samples analyzed, these data indicate that as much as 40% of CD34 + cells readily internalize fragments of extracellular exogenous DNA. This suggests that internalization of fragmented dsDNA is a general feature of poorly differentiated cells, in particular CD34 + bone marrow cells. 相似文献
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