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21.
Some concrete and reinforced concrete structures are found to suffer from rapid corrosion, which reduces their life. Reduction of concrete strength characteristics, decline in pH, and changes in the chemical composition of concrete were related to the development of an association of heterotrophic and auto‐trophic bacteria, which transformed carbon, sulfur, and nitrogen compounds. The mechanism of concrete biocorrosion at high pH values is based on the degradation of hydrosilicates with the subsequent dissolution of the resultant amorphous silica and on the production of calcite.  相似文献   
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Russian Journal of Genetics - Owing to the changes in the general ecological situation in Russia, livestock losses from ovine anaplasmosis have rapidly increased in recent years. The development of...  相似文献   
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A binary system of photoaffinity reagents was proposed earlier for highly efficient labeling of DNA polymerases by 5"-[32P]DNA primers. In the present study we demonstrate the feasibility of this approach to increase the efficiency of DNA polymerase labeling. A photoactive 2,3,5,6-tetrafluoro-4-azidobenzoyl (FAB) group was incorporated at the 3"-end of 5"-[32P]DNA primers synthesized by DNA polymerase or Tte in the presence of one of the dTTP analogs—FAB-4-dUTP, FAB-9-dUTP, or FAB-4-ddUTP. The reaction mixture was irradiated by light with wavelength of 334-365 nm (direct labeling) or 365-450 nm in the presence of photosensitizer, one of dTTP analogs containing a pyrene moiety, Pyr-6-dUTP or Pyr-8-dUTP. In the case of the binary system of photoaffinity reagents, a FAB group is activated by energy transfer from sensitizer localized in the dNTP-binding site of DNA polymerase in the triple complex, comprised by reagent, DNA polymerase, and Pyr-6(8)-dUTP. Direct activation of the FAB group under these conditions is negligible. The most efficient photolabeling of DNA polymerases was observed with a primer containing a FAB-4-dUMP group at the 3"-end, and Pyr-6-dUTP as a photosensitizer. Using 10-fold molar excess of photoreagent to DNA polymerase , the labeling efficiency was shown to achieve 60%, which is 2-fold higher than the efficiency of the direct DNA polymerase labeling under harsher conditions (334-365 nm).  相似文献   
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Maturation of bovine oocyte-cumulus complexes (OCC) in media derived following granulosa cell culturing with prolactin (PRL, 50 ng/ml) and somatotropin (ST, 10 ng/ml) was studied. A medium conditioned by granulosa cells in the presence of PRL or ST exerted a stimulating effect on the proliferative activity of cumulus cells. ST introduction into the granulosa cell culture also caused a decrease in the rate of cumulus cells with degenerated chromatin at a subsequent OCC culturing. At the same time, the expansion of cumulus did not depend on hormone availability in the culture medium for granulosa cells. When OCC matured in conditioned media, a short-term inhibition of oocyte meiosis reinitiation (after 6 h of culturing) was revealed in both the experimental groups, as compared to the control. Furthermore, the addition of ST and PRL to granulosa cell culture resulted in a subsequent decline in the rate of oocytes with signs of chromosome degeneration, observed as early as by 6 h of incubation and to be retained throughout the whole period of OCC culturing. In this case the earlier resumption of meiosis was associated with a higher rate of degeneration of the nuclear material in oocytes. The results of the present study suggest that granulosa cells may mediate, at least in part, PRL and ST impacts on in vitro maturation of bovine OCC, with no contact between OCC and granulosa cells being required for hormonal signaling.  相似文献   
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Two types of surface tactile epidermal formations are identified in the bill tip organ of 11 species of lamellirostral birds. Their density arrangement and ratio in the mandible and maxilla are greater in dabbling ducks (filter-feeder species) than in herbivorous and in actively pursuing species. The length and proportions of the connective tissue tubules enclosing the encapsulated mechanoreceptors in filter-feeder species differ significantly from the others. The vibroreceptor endings are significantly more numerous in filter-feeder species and the touch endings in nonfiltering ones. The latter are smaller in the filter-feeder species. Within the walls of the connective tissue tubules, tactile epitheliocytes are registered for the first time. The structure of keratinocytes separating epidermal papillae of the bill tip organ apparently ensures their mobility. The bill tip organ is probably involved in the communication process of waterfowl.  相似文献   
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Modern views on genetic, cytological and molecular bases of the structure and regulation of preparing and implementing mitotic chromosome segregation are discussed.  相似文献   
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Specific binding of bovine prolactin and somatotropin by granulosa cells from the antral follicles of various diameters was studied in cows at different reproductive states, prepubertal, pubertal, and early gestation. The ability of granulosa cells to bind prolactin did not depend on the reproductive state of an animal. At the same time, the dynamics of somatotropin specific binding by granulosa cells during maturation of the antral follicles differed at dissimilar reproductive states of the cows. When the diameter of follicles increased from 3-5 to 6-10 mm, specific binding of 125I-somatotropin decreased in pubertal animals, but remained unchanged in the prepubertal and pregnant animals. The results of Scatchard analysis of the binding data suggest that sexual maturation of cows did not affect the binding of prolactin and somatotropin by granulosa cells from follicles of 1-2 mm in diameter. The data obtained suggest that the decreased sensitivity of granulosa cells to somatotropin at the terminal stages of maturation of the antral follicles is essential for their development and acquisition of the ability for ovulation.  相似文献   
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