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51.
Jan P. Meier-Kolthoff Markus Göker Cathrin Spröer Hans-Peter Klenk 《Archives of microbiology》2013,195(6):413-418
DNA–DNA hybridizations (DDH) play a key role in microbial species discrimination in cases when 16S rRNA gene sequence similarities are 97 % or higher. Using real-world 16S rRNA gene sequences and DDH data, we here re-investigate whether or not, and in which situations, this threshold value might be too conservative. Statistical estimates of these thresholds are calculated in general as well as more specifically for a number of phyla that are frequently subjected to DDH. Among several methods to infer 16S gene sequence similarities investigated, most of those routinely applied by taxonomists appear well suited for the task. The effects of using distinct DDH methods also seem to be insignificant. Depending on the investigated taxonomic group, a threshold between 98.2 and 99.0 % appears reasonable. In that way, up to half of the currently conducted DDH experiments could safely be omitted without a significant risk for wrongly differentiated species. 相似文献
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Establishment of in vitro culture, plant regeneration, and genetic transformation of Camelina sativa
A. I. Yemets Yu. N. Boychuk E. N. Shysha D. B. Rakhmetov Ya. B. Blume 《Cytology and Genetics》2013,47(3):138-144
The results of establishing an in vitro culture, plantlet regeneration, and rooting of Camelina sativa cultivar Peremozhets and cultivar Mirazh are presented. The effective concentrations of sterilizing agents and the duration of plant material treatment were estimated. The phytohormone ratio, the sucrose concentration in the nutrient medium that induced the effective formation of C. sativa shoots, and the NAA concentration for plantlet rooting have been established. A method of Agrobacterium-mediated transformation of Camelina by using binary vector pGH217 carrying the reporter β-glucoronidase (gus) gene driven under the 35S CaMV promoter and nos-terminator, as well as the selective marker hpt gene conferring hygromycin-resistance in transgenic plant, was elaborated. 相似文献
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Ke Xing Guang-Kai Bian Sheng Qin Hans-Peter Klenk Bo Yuan Yue-Ji Zhang Wen-Jun Li Ji-Hong Jiang 《Antonie van Leeuwenhoek》2013,104(6):1245-1245
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Click reactions between alkynes and azides using the privileged scaffold of triterpenes have been of interest for biological chemistry. Many publications deal with the synthesis of novel bioactive molecules; these conjugates have also been used for bioanalytical and diagnostic purposes. As a result, conjugates of better physicochemical properties were obtained; even compounds of improved solubility in water and physiological fluids were made through the introduction of a triazol residue. “Hybrid-structures“, i.e. molecules consisting of two independently bioactive subunits linked by a triazole residue were higher bioactive than their parent compounds but not as active as expected, and with a few exceptions the ultimate breakthrough has not yet been achieved. Only in the synthesis of compounds with anti-leishmanial activity some new and promising lead structures were found. As a consequence, triazole modified triterpenes seem to hold their greatest future prospect rather as diagnostic reagents and molecular probes than as drugs. 相似文献
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Olesya V. Kolmakova Michail I. Gladyshev Jérémy André Fonvielle Lars Ganzert Thomas Hornick Hans-Peter Grossart 《Environmental microbiology》2019,21(1):34-49
Non-predatory mortality of zooplankton provides an abundant, yet, little studied source of high quality labile organic matter (LOM) in aquatic ecosystems. Using laboratory microcosms, we followed the decomposition of organic carbon of fresh 13C-labelled Daphnia carcasses by natural bacterioplankton. The experimental setup comprised blank microcosms, that is, artificial lake water without any organic matter additions (B), and microcosms either amended with natural humic matter (H), fresh Daphnia carcasses (D) or both, that is, humic matter and Daphnia carcasses (HD). Most of the carcass carbon was consumed and respired by the bacterial community within 15 days of incubation. A shift in the bacterial community composition shaped by labile carcass carbon and by humic matter was observed. Nevertheless, we did not observe a quantitative change in humic matter degradation by heterotrophic bacteria in the presence of LOM derived from carcasses. However, carcasses were the main factor driving the bacterial community composition suggesting that the presence of large quantities of dead zooplankton might affect the carbon cycling in aquatic ecosystems. Our results imply that organic matter derived from zooplankton carcasses is efficiently remineralized by a highly specific bacterial community, but does not interfere with the bacterial turnover of more refractory humic matter. 相似文献