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51.
Klenow-like DNA polymerase I fragment from Geobacillus anatolicus (GF) was cloned and purified. The accuracy of GF was measured in vitro at three different temperatures under single turnover conditions as well as using a forward mutation assay. In pre-steady-state kinetic measurements, when temperature was raised from 22 °C to 50 °C, the rate (kpol) for cognate dTTP and non-cognate dATP nucleotide incorporations increased six- and four-fold, respectively, whereas the Kd for both nucleotide incorporations changed only slightly. As a result, the error frequency was remained constant (∼4 × 10−4) over this temperature range. The accuracy of GF was also measured using a forward mutation assay during a single cycle of DNA synthesis of the lacZα complementation gene in M13mp2 DNA. In this assay, which scores various types of replication errors, mutant frequency of GF was 5 × 10−3 at 72 °C which is four-fold higher than that of 37 °C. 相似文献
52.
S Benson-Amram KE Holekamp 《Proceedings. Biological sciences / The Royal Society》2012,279(1744):4087-4095
Innovative animals are those able to solve novel problems or invent novel solutions to existing problems. Despite the important ecological and evolutionary consequences of innovation, we still know very little about the traits that vary among individuals within a species to make them more or less innovative. Here we examine innovative problem solving by spotted hyenas (Crocuta crocuta) in their natural habitat, and demonstrate for the first time in a non-human animal that those individuals exhibiting a greater diversity of initial exploratory behaviours are more successful problem solvers. Additionally, as in earlier work, we found that neophobia was a critical inhibitor of problem-solving success. Interestingly, although juveniles and adults were equally successful in solving the problem, juveniles were significantly more diverse in their initial exploratory behaviours, more persistent and less neophobic than were adults. We found no significant effects of social rank or sex on success, the diversity of initial exploratory behaviours, behavioural persistence or neophobia. Our results suggest that the diversity of initial exploratory behaviours, akin to some measures of human creativity, is an important, but largely overlooked, determinant of problem-solving success in non-human animals. 相似文献
53.
54.
Recent advances in technologies such as DNA microarrays have provided an abundance of gene expression data on the genomic scale. One of the most important projects in the post-genome-era is the systemic identification of gene expression networks. However, inferring internal gene expression structure from experimentally observed time-series data are an inverse problem. We have therefore developed a system for inferring network candidates based on experimental observations. Moreover, we have proposed an analytical method for extracting common core binomial genetic interactions from various network candidates. Common core binomial genetic interactions are reliable interactions with a higher possibility of existence, and are important for understanding the dynamic behavior of gene expression networks. Here, we discuss an efficient method for inferring genetic interactions that combines a Step-by-step strategy (Y. Maki, Y. Takahashi, Y. Arikawa, S. Watanabe, K. Aoshima, Y. Eguchi, T. Ueda, S. Aburatani, S. Kuhara, M. Okamoto, An integrated comprehensive workbench for inferring genetic networks: Voyagene, Journal of Bioinformatics and Computational Biology 2(3) (2004) 533.) with an analysis method for extracting common core binomial genetic interactions. 相似文献
55.
McBrayer JP 《Bioethics》2008,22(6):299-306
The non‐identity problem is the problem of grounding moral wrongdoing in cases in which an action affects who will exist in the future. Consider a woman who intentionally conceives while on medication that is harmful for a fetus. If the resulting child is disabled as a result of the medication, what makes the woman's action morally wrong? I argue that an explanation in terms of harmful rights violations fails, and I focus on Peter Markie's recent rights‐based defense. Markie's analysis rests on the notion of an indirect harm, and I show that the calculation of an indirect harm relies on an improper baseline for the determination of whether or not an action adversely affects a patient's interests. I also defend an impersonal duty‐based analysis of the wrongdoing in non‐identity cases against an objection by Markie. I close by arguing that the rights‐based analysis is insensitive to context and that context is morally relevant in the determination of the moral valence of actions in cases of non‐identity. This failure provides a pro tanto reason to favor an impersonal duty‐based analysis of the wrongdoing in non‐identity cases. 相似文献
56.
Davis J 《Bioethics》2008,22(5):258-268
For now, the best way to select a child's genes is to select a potential child who has those genes, using genetic testing and either selective abortion, sperm and egg donors, or selecting embryos for implantation. Some people even wish to select against genes that are only mildly undesirable, or to select for superior genes. I call this selection drift – the standard for acceptable children is creeping upwards. The President's Council on Bioethics and others have raised the parental love objection : Just as we should love existing children unconditionally, so we should unconditionally accept whatever child we get in the natural course of things. If we set conditions on which child we get, we are setting conditions on our love for whatever child we get. Although this objection was prompted by selection drift, it also seems to cover selecting against genes for severe impairments.
I argue that selection drift is not inconsistent with the ideal of unconditional parental love and, moreover, that the latter actually implies that we should practise selection drift – in other words, we should try to select potential children with the best genetic endowments. My endowment argument for the second claim works from an analogy between arranging an endowment prior to conception to fund a future child's education, and arranging a genetic endowment by selecting a potential child who already has it, where in both cases the child would not have existed without the endowment. I conclude with some programmatic remarks about the nonidentity problem. 相似文献
I argue that selection drift is not inconsistent with the ideal of unconditional parental love and, moreover, that the latter actually implies that we should practise selection drift – in other words, we should try to select potential children with the best genetic endowments. My endowment argument for the second claim works from an analogy between arranging an endowment prior to conception to fund a future child's education, and arranging a genetic endowment by selecting a potential child who already has it, where in both cases the child would not have existed without the endowment. I conclude with some programmatic remarks about the nonidentity problem. 相似文献
57.
Heow Pueh Lee 《仿生工程学报(英文版)》2008,5(2):111-119
A clonal selection based memetic algorithm is proposed for solving job shop scheduling problems in this paper. In the proposed algorithm, the clonal selection and the local search mechanism are designed to enhance exploration and exploitation. In the clonal selection mechanism, clonal selection, hypermutation and receptor edit theories are presented to construct an evolutionary searching mechanism which is used for exploration. In the local search mechanism, a simulated annealing local search algorithm based on Nowicki and Smutnicki's neighborhood is presented to exploit local optima. The proposed algorithm is examined using some well-known benchmark problems. Numerical results validate the effectiveness of the proposed algorithm. 相似文献
58.
A heterarchy is a dynamical hierarchical system inheriting logical inconsistencies between levels. Because of these inconsistencies, it is very difficult to formalize a heterarchy as a dynamical system. Here, the essence of a heterarchy is proposed as a pair of the property of self-reference and the property of a frame problem interacting with each other. The coupling of them embodies a one-ity inheriting logical inconsistency. The property of self-reference and a frame problem are defined in terms of logical operations, and are replaced by two kinds of dynamical system, temporal dynamics and state-scale dynamics derived from the same "liar statement". A modified tent map serving as the temporal dynamics is twisted and coupled with a tent map serving as the state-scale dynamics, and this results in a discontinuous self-similar map as a dynamical system. This reveals that the state-scale and temporal dynamics attribute to the system, and shows both robust and emergent behaviors. 相似文献
59.
根据外部形态、核型以技精子形态等特征,角蟾科分布于中国的角蟾属(Megophrys)较之拟髭蟾属(Leptobrachium)是更为原始的类群,角蟾科动物中拟角蟾属(Ophryophryne)与角蟾属亲缘关系较近,短腿蟾属(Brachytarsophrys)是较为原始的类群,且应为一无效属,无耳蟾属(Atympanophrys)应为一有效属。角蟾属可以分为两个种组,其是峨嵋角蟾种组比较进化,白颌大角蟾种组比较原始。 相似文献
60.
东北老工业基地煤炭矿区环境问题与生态对策 总被引:7,自引:1,他引:6
在对我国东北老工业基地煤炭矿区环境问题进行分析的基础上,提出了解决该地区煤炭矿区环境问题的生态对策,包括着重强调煤炭矿区的生态可持续发展对于采矿工业的复兴具有重要推进作用,而澳大利亚关于最佳实践的经验对于今后采煤矿区的发展具有重要借鉴意义。推行生态多元综合治理的土地复垦一修复模式是今后煤炭矿区环境保护的方向。 相似文献