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Bruce N. Waller 《Biology & philosophy》1996,11(2):245-254
Peter Woolcock, in Ruse's Darwinian Meta-Ethics: A Critique, argues that the subjectivist (nonobjectivist) Darwinian metaethics proposed by Michael Ruse (in Taking Darwin Seriously) cannot work, because the illusion of objectivity that Ruse claims is essential to morality breaks down when it is recognized as illusion, and there then remain no good reasons for acknowledging or following moral obligations. Woolcock, however, is mistaken in supposing that moral behaviour requires rational motivation. Ruse's Darwinian metaethical analysis shows why such objective support for morality is neither plausible nor necessary; and when that is recognized, it can also be seen that Ruse's proposed illusion of moral objectivity is superfluous. 相似文献
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Annexin IV (endonexin) has been purified from chicken liver and crystallized by the vapour diffusion method. Crystals which diffract to at least 2.2 A have been obtained. They belong to space group R3 and have unit cell dimensions of a = b = 99.4 A, c = 96.2 A, alpha = 90 degrees, beta = 90 degrees, gamma = 120 degrees. There is one molecule of 32,500 Da per asymmetric unit. 相似文献
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In a retrospective study 80 patients with Hodgkin's disease of stage III B (n = 32) and IV (n = 48) were investigated, who had been treated with a modified MOPP regimen. 28 patients (35%) were previously untreated. A completed remission was reached in 51 patients, a partial remission in 16, and 13 patients failed to respond. 16 patients had died in the observation period. Complete remissions were twice as frequent with 90% in stage III as compared with 45% in stage IV. The group of patients surviving 4 years was 92% in stage III and 62% in stage IV. 相似文献
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Enhanced level and metabolic regulation of methionyl-transfer ribonucleic acid synthetase in different strains of Escherichia coli K-12. 总被引:11,自引:10,他引:1 下载免费PDF全文
The methionyl-transfer ribonucleic acid (tRNA) synthetase of Escherichia coli K-12 eductants carrying P2-mediated deletions in the region of the structural gene of this enzyme was investigated. No structural alteration of this enzyme was observed in three eductants examined. These were isolated from strain AB311, which had a threefold higher level of methionyl-tRNA synthetase than most haploid strains examined. In two of the three eductants studied, the level of this enzyme was twofold higher than in their parental strain regardless of growth conditions used. In contrast, isoleucyl-, leucyl-, and valyl-tRNA synthetases had similar levels in all strains examined. Like valyl-tRNA synthetase, but to a lesser extent, methionyl-tRNA synthetase was subject to metabolic regulation. Coupling between the level of methionyl-tRNA synthetase and growth rate was observed even in strains that had an enhanced level of methionyl-tRNA synthetase. These results suggest that the formation of methionyl-tRNA synthetase remains subject to metabolic regulation even when the repression-like mechanism that controls the synthesis of this enzyme is altered. In addition, we report that in the merodiploid strain EM20031, which was haploid for the valyl-tRNA synthetase structural gene and diploid for the structural genes of methionyl-tRNA synthetase and D-serine deaminase, the levels of these latter two enzymes varied to a minor yet significant extent with the phosphate concentration of the culture medium; under the same conditions, the level of valyl-tRNA synthetase remained unchanged. Moreover, no variation of the levels of these three enzymes in response to phosphate was observed in the haploid strain HfrH. These results indicate that in the merodiploid strain EM20031, which carries the episome F32, the number of episomes per chromosome varies to some extent according to the phosphate concentration of the culture medium. 相似文献
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Freddie W. Leith Jennifer L. Grigg Barbara J. Barham Peter J. Barham Katrin Ludynia Cuan McGeorge Andile Mdluli Nola J. Parsons Lauren J. Waller Richard B. Sherley 《Ecology and evolution》2022,12(9)
In long‐lived species, reproductive skipping is a common strategy whereby sexually mature animals skip a breeding season, potentially reducing population growth. This may be an adaptive decision to protect survival, or a non‐adaptive decision driven by individual‐specific constraints. Understanding the presence and drivers of reproductive skipping behavior can be important for effective population management, yet in many species such as the endangered African penguin (Spheniscus demersus), these factors remain unknown. This study uses multistate mark‐recapture methods to estimate African penguin survival and breeding probabilities at two colonies between 2013 and 2020. Overall, survival (mean ± SE) was higher at Stony Point (0.82 ± 0.01) than at Robben Island (0.77 ± 0.02). Inter‐colony differences were linked to food availability; under decreasing sardine (Sardinops sagax) abundance, survival decreased at Robben Island and increased at Stony Point. Additionally, reproductive skipping was evident across both colonies; at Robben Island the probability of a breeder becoming a nonbreeder was ~0.22, versus ~0.1 at Stony Point. Penguins skipping reproduction had a lower probability of future breeding than breeding individuals; this lack of adaptive benefit suggests reproductive skipping is driven by individual‐specific constraints. Lower survival and breeding propensity at Robben Island places this colony in greater need of conservation action. However, further research on the drivers of inter‐colony differences is needed. 相似文献
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