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Rapid adaptation to global change can counter vulnerability of species to population declines and extinction. Theoretically, under such circumstances both genetic variation and phenotypic plasticity can maintain population fitness, but empirical support for this is currently limited. Here, we aim to characterize the role of environmental and genetic diversity, and their prior evolutionary history (via haplogroup profiles) in shaping patterns of life history traits during biological invasion. Data were derived from both genetic and life history traits including a morphological analysis of 29 native and invasive populations of topmouth gudgeon Pseudorasbora parva coupled with climatic variables from each location. General additive models were constructed to explain distribution of somatic growth rate (SGR) data across native and invasive ranges, with model selection performed using Akaike's information criteria. Genetic and environmental drivers that structured the life history of populations in their native range were less influential in their invasive populations. For some vertebrates at least, fitness‐related trait shifts do not seem to be dependent on the level of genetic diversity or haplogroup makeup of the initial introduced propagule, nor of the availability of local environmental conditions being similar to those experienced in their native range. As long as local conditions are not beyond the species physiological threshold, its local establishment and invasive potential are likely to be determined by local drivers, such as density‐dependent effects linked to resource availability or to local biotic resistance.  相似文献   
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On April 18, 2007 an international meeting on Pathophysiology of Ageing, Longevity and Age-Related Diseases was held in Palermo, Italy. Several interesting topics on Cancer, Immunosenescence, Age-related inflammatory diseases and longevity were discussed. In this report we summarize the most important issues. However, ageing must be considered an unavoidable end point of the life history of each individual, nevertheless the increasing knowledge on ageing mechanisms, allows envisaging many different strategies to cope with, and delay it. So, a better understanding of pathophysiology of ageing and age-related disease is essential for giving everybody a reasonable chance for living a long and enjoyable final part of the life.  相似文献   
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Sclerocarya birrea subsp. caffra (marula), a keystone large tree species in southern Africa and heavily utilized by people and herbivores, is declining at an unprecedented rate in the Kruger National Park (KNP), South Africa. Due to increasing concerns over large tree declines in the KNP, mirroring those in eastern Africa over the last 50 years, and local extinctions of marula populations in the north‐western KNP, adult trees in the southern KNP were monitored between 2001 and 2010. Annual mortality rates across all adult size classes ranged between 3.2 and 4.6%. Loss of adult marula trees in some areas over the last decade exceeded 25%. Rainfall had a strong influence on mortality rates temporally and spatially, but the distance to the nearest perennial river had little influence. Overall, marula populations continue to decline and further local extinctions are possible. Given the clearly unacceptable trends of decline, the next step is to utilize this information (i) to develop predictive models for the future dynamics of marula populations incorporating all drivers; (ii) to advocate active management of refugia within the park where marula populations are protected from elephant impacts; and in combination with (iii) continued monitoring.  相似文献   
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The purpose of the study was to determine the specificity of the development and training of coordination skills (CSs) in 11- to 19-year-old soccer players (n = 600). Tests for soccer players’ CSs and technical skills and one- and two-year training experiments on targeted development of CSs were used. It was found that the period from 11 to 13 years of age was the most favorable for the development of CSs in soccer players, and the period from 14 to 16 years of age was the next most favorable. The use of special coordination training aimed at development of individual CSs led to a greater improvement, with the CS and technical skill parameters of athletes from the experimental groups being significantly higher (by 2.5–38.3 and 3.6–12.2%, respectively) than those of athletes from the control groups developing CSs by the traditional method using dexterity exercises.  相似文献   
5.
Color Figures in BJ: RGB versus CMYK   总被引:2,自引:0,他引:2       下载免费PDF全文
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The active sites of caspases are composed of four mobile loops. A loop (L2) from one half of the dimer interacts with a loop (L2′) from the other half of the dimer to bind substrate. In an inactive form, the two L2′ loops form a cross‐dimer hydrogen‐bond network over the dimer interface. Although the L2′ loop has been implicated as playing a central role in the formation of the active‐site loop bundle, its precise role in catalysis has not been shown. A detailed understanding of the active and inactive conformations is essential to control the caspase function. We have interrogated the contributions of the residues in the L2′ loop to catalytic function and enzyme stability. In wild‐type and all mutants, active‐site binding results in substantial stabilization of the complex. One mutation, P214A, is significantly destabilized in the ligand‐free conformation, but is as stable as wild type when bound to substrate, indicating that caspase‐7 rests in different conformations in the absence and presence of substrate. Residues K212 and I213 in the L2′ loop are shown to be essential for substrate‐binding and thus proper catalytic function of the caspase. In the crystal structure of I213A, the void created by side‐chain deletion is compensated for by rearrangement of tyrosine 211 to fill the void, suggesting that the requirements of substrate‐binding are sufficiently strong to induce the active conformation. Thus, although the L2′ loop makes no direct contacts with substrate, it is essential for buttressing the substrate‐binding groove and is central to native catalytic efficiency.  相似文献   
8.
We tested the hypothesis that women have blunted sympathetic neural responses to orthostatic stress compared with men, which may be elicited under hypovolemic conditions. Muscle sympathetic nerve activity (MSNA) and hemodynamics were measured in eight healthy young women and seven men in supine position and during 6 min of 60 degrees head-up tilt (HUT) under normovolemic and hypovolemic conditions (randomly), with approximately 4-wk interval. Acute hypovolemia was produced by diuretic (furosemide) administration approximately 2 h before testing. Orthostatic tolerance was determined by progressive lower body negative pressure to presyncope. We found that furosemide produced an approximately 13% reduction in plasma volume, causing a similar increase in supine MSNA in men and women (mean +/- SD of 5 +/- 7 vs. 6 +/- 5 bursts/min; P = 0.895). MSNA increased during HUT and was greater in the hypovolemic than in the normovolemic condition (32 +/- 6 bursts/min in normovolemia vs. 44 +/- 15 bursts/min in hypovolemia in men, P = 0.055; 35 +/- 9 vs. 45 +/- 8 bursts/min in women, P < 0.001); these responses were not different between the genders (gender effect: P = 0.832 and 0.814 in normovolemia and hypovolemia, respectively). Total peripheral resistance increased proportionately with increases in MSNA during HUT; these responses were similar between the genders. However, systolic blood pressure was lower, whereas diastolic blood pressure was similar in women compared with men during HUT, which was associated with a smaller stroke volume or stroke index. Orthostatic tolerance was lower in women, especially under hypovolemic conditions. These results indicate that men and women have comparable sympathetic neural responses during orthostatic stress under normovolemic and hypovolemic conditions. The lower orthostatic tolerance in women is predominantly because of a smaller stroke volume, presumably due to less cardiac filling during orthostasis, especially under hypovolemic conditions, which may overwhelm the vasomotor reserve available for vasoconstriction or precipitate neurally mediated sympathetic withdrawal and syncope.  相似文献   
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Analogues of the dsRNA poly(I).poly(C), namely double-stranded like complexes of poly(I) or poly(C), respectively, with corresponding vinyl nucleobases copolymerized with various vinyl compounds are highly effective interferon inducers in human lymphocyte cultures. Like poly(I).poly(C) they stimulate the liberation of an inhibitor(s) of interferon activity and, moreover, display mitogenic effect. With respect to the extent of these effects the various inducers differ considerably.  相似文献   
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