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排序方式: 共有1371条查询结果,搜索用时 15 毫秒
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Summary Amino acid starvation of Escherichia coli relA mutants may be used as a method for efficient plasmid DNA amplification. Here we demonstrate DNA degradation which occurs at elevated temperatures (42–43°C) after plasmid amplification in amino acid-starved bacteria. These results may explain the previously described low efficiency of plasmid DNA amplification at elevated temperatures. 相似文献
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Jacek Hennig Jocelyn Malamy Grzegorz Grynkiewicz Janusz Indulski Daniel F. Klessig 《The Plant journal : for cell and molecular biology》1993,4(4):593-600
Salicylic acid (SA) has been proposed to play a role in the induction of pathogenesis-related (PR) proteins and systemic acquired resistance (SAR) in tobacco. Since SA is rapidly converted to salicylic acid β-glucoside (SAG) in tobacco, we have attempted to assess the role of SAG in pathogenesis by application of chemically synthesized SAG to tobacco leaves. SAG was as active as SA in induction of PR-1 gene expression. This induction was preceded by a transient release of SA, which occurred in the extracellular spaces. The existence of a mechanism that releases SA from SAG suggests a possible role for SAG in SAR. 相似文献
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Markéta Ondračková Maria Yu Tkachenko Veronika Bartáková Anna Bryjová Michal Janáč Grzegorz Zięba Kacper Pyrzanowski Yuriy Kvach 《Journal of fish biology》2023,102(2):426-442
In Poland, distribution of non-native pumpkinseed Lepomis gibbosus (Centrarchidae) is strictly limited to the Oder river basin, where it was introduced in the early 20th century. Recently, several populations have been found in waterbodies adjacent to the Oder, particularly in its lower reaches. In this study, we compare the genetic relatedness of populations in the Oder basin with other European populations using nuclear (microsatellite) and mitochondrial (partial cytochrome c oxidase subunit I; cox1) markers. Microsatellite analysis indicated that four populations in the lower Oder form a separate cluster, while one in the middle Oder clustered with Danubian populations, from where probably having been introduced. Microsatellite data suggested that the lower Oder populations differ from other non-native European populations, making it impossible to estimate the source of introduction. Nevertheless, analysis of cox1 indicated that Oder pumpkinseeds belong to the same haplotype as the vast majority of European populations. Parasitological examination confirmed the presence of two North American species, the monogenean Onchocleidus dispar and trematode Posthodiplostomum centrarchi, in the lower Oder, both previously unknown in the region. Fifteen other parasite species were acquired, including glochidia of invasive Sinanodonta woodiana. In the middle Oder, parasite infection was more limited. Fish from the Gryfino Canal, considered one of the most invasive populations in Europe, showed the highest parasite abundance and diversity, and the highest somatic condition and growth rate due to warm water released from the Dolna Odra power plant. Our results highlight significant differences in somatic condition and parasite infection in long-established non-native pumpkinseed populations in the same river system, reflecting mainly environmental conditions. 相似文献
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Grzegorz Garbacz Bartosz Kołodziej Mirko Koziolek Werner Weitschies Sandra Klein 《AAPS PharmSciTech》2013,14(2):517-522
The bicarbonate buffer is considered as the most biorelevant buffer system for the simulation of intestinal conditions. However, its use in dissolution testing of solid oral dosage forms is very limited. The reason for this is the thermodynamic instability of the solution containing hydrogen carbonate ions and carbonic acid. The spontaneous loss of carbon dioxide (CO2) from the solution results in an uncontrolled increase of the pH. In order to maintain the pH on the desired level, either a CO2 loss must be completely avoided or the escaped CO2 has to be replaced by quantitative substitution, i.e. feeding the solution with the respective amount of gas, which re-acidifies the buffer after dissociation. The present work aimed at the development of a device enabling an automatic pH monitoring and regulation of hydrogen carbonate buffers during dissolution tests. 相似文献
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Population trends in black woodpecker in relation to changes and characteristics of European forests
Grzegorz Mikusiski 《Ecography》1995,18(4):363-369
During the last century the black woodpecker Drycopus maritus has expanded m range in central and western Europe Habitat changes were the most common explanations of these expansions I compared changes m forest characteristics in countries where different black woodpecker population trends were observed Results showed that countries with positive population trends had significantly higher increase in coniferous forest volume These countries had also significantly higher proportion of young forest stands The importance of coniferous forests, as well as importance of forest structure for the black woodpecker, are discussed 相似文献