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1.
In this paper the recent population changes of the Wild Boar in different European countries is analysed through the study of hunting statistics. A simultaneous increase in numbers is observed throughout the whole area during the period 1965–1975. From 1975 onwards the population stabilizes itself apart from in peripheral areas like Finland. Potentially favourable factors which play a part in this process are discussed and certain reproductive and dispersive characteristics which favour its invasive behaviour are discussed.  相似文献   
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The genetic constructions based on integrative vector pGV3850 were used to introduce bacterial genes xyl and T-cyt into potato cells. The transformation was carried out using the leaf-disc method with modifications. A special system for obtaining regenerants from explants of potato in vitro plants or calli has been designed that permitted the selection of transgenic shoots. The presence of the genes in potato genome has been proved by testing the NPTII and glucoisomerase activities. The transgenic plants expressing T-cyt gene differed from the wild type in sharp decrease of the apical dominance.  相似文献   
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Male white rats divided in three groups on the basis of their behavior in the elevated plus-maze were subjected to 10-min cardiac arrest. Analysis of the results of their subsequent food and active avoidance conditioning revealed the effects of the following factors: (1) a factor of initial typological features of the higher nervous activity, (2) a factor of general brain mechanisms of postresuscitation, and (3) a factor of postresuscitation features in rats with different behaviors, which represented changes in different mechanisms of conditioned reflex performance in these animals.  相似文献   
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Recent studies have shown that restriction endonucleases (REs), which are broadly used in genetic engineering and molecular biology, vary not only in nucleotide sequence of the recognition site, but also in the mechanism of their interaction with DNA. This review focuses on type IIF and IIE REs, which require simultaneous interaction with two nucleotide sequences for efficient DNA cleavage. Crystal structures of these REs and their complexes with DNA, stepwise interactions with DNA, catalytic mechanisms of DNA hydrolysis, and DNA looping are considered. Type IIE REs have provided an example of a new type of DNA–protein recognition: two copies of one recognition sequence interact specifically with two different amino acid sequences and two different structural motifs of one polypeptide chain.  相似文献   
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Purified rat islets were dissociated into single-cell suspension with an EDTA-Trypsin treatment. During a stationary culture in vitro the islet cells reassociated forming aggregates (neoislets). Electron microscopy revealed that the aggregates consisted mostly of beta-cells and not numerous alpha-cells. They showed a good insulin-secreting capacity and were able to increase insulin release in response to glucose plus theophylline. The lack of passenger leukocytes makes the neoislets particularly suited for experimental and clinical transplantation.  相似文献   
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