共查询到20条相似文献,搜索用时 15 毫秒
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Malissen B 《Médecine sciences : M/S》2007,23(2):115-116
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Soto C 《Trends in biochemical sciences》2011,36(3):151-158
Forty-three years have passed since it was first proposed that a protein could be the sole component of the infectious agent responsible for the enigmatic prion diseases. Many discoveries have strongly supported the prion hypothesis, but only recently has this once heretical hypothesis been widely accepted by the scientific community. In the past 3 years, researchers have achieved the 'Holy Grail' demonstration that infectious material can be generated in vitro using completely defined components. These breakthroughs have proven that a misfolded protein is the active component of the infectious agent, and that propagation of the disease and its unique features depend on the self-replication of the infectious folding of the prion protein. In spite of these important discoveries, it remains unclear whether another molecule besides the misfolded prion protein might be an essential element of the infectious agent. Future research promises to reveal many more intriguing features about the rogue prions. 相似文献
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Garber K 《Nature biotechnology》2007,25(8):838-840
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Are islands the end of the colonization road? 总被引:1,自引:0,他引:1
Ecologists have, up to now, widely regarded colonization of islands from continents as a one-way journey, mainly because of widely accepted assertions that less diverse island communities are easier to invade. However, continents present large targets and island species should be capable of making the reverse journey, considering they are the direct descendants of successful colonists and provided that they have not lost their dispersal abilities. Recent mapping of geography onto molecular phylogenies has revealed several cases of 'reverse colonization' (from islands to continents). We suggest this phenomenon warrants closer attention in ecology and biogeography. Assessing its significance will contribute to understanding the role of dispersal and establishment in biogeographic distributions and the assembly of natural biotas. 相似文献
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Nalinie S. M. D Wickramasinghe James C. Lacey Jr. 《Molecular and cellular biochemistry》1994,139(2):117-121
Recent reports suggest that the ribosome retains considerable peptidyl transferase activity even when much of the protein of the ribosome is removed and further suggests that rRNA may be the peptidyl transferase. The work here suggests that the AMP residue at the 3 terminus of each tRNA has some catalytic activity both in the esterification reaction and in forming a pseudopeptide, AcGly, and further suggests that whatever peptidyl transferase is, it finds a cooperative substrate in the aminoacyl-AMP at the 3 terminus of tRNA. 相似文献
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Jonathan Kaplan 《Biology & philosophy》2008,23(5):625-638
The concepts of adaptive/fitness landscapes and adaptive peaks are a central part of much of contemporary evolutionary biology;
the concepts are introduced in introductory texts, developed in more detail in graduate-level treatments, and are used extensively
in papers published in the major journals in the field. The appeal of visualizing the process of evolution in terms of the
movement of populations on such landscapes is very strong; as one becomes familiar with the metaphor, one often develops the
feeling that it is possible to gain deep insights into evolution by thinking about the movement of populations on landscapes
consisting of adaptive valleys and peaks. But, since Wright first introduced the metaphor in 1932, the metaphor has been the
subject of persistent confusion, from equivocation over just what the features of the landscape are meant to represent to
how we ought to expect the landscapes to look. Recent advances—conceptual, empirical, and computational—have pointed towards
the inadequacy and indeed incoherence of the landscapes as usually pictured. I argue that attempts to reform the metaphor
are misguided; it is time to give up the pictorial metaphor of the landscape entirely and rely instead on the results of formal
modeling, however difficult such results are to understand in ‘intuitive’ terms.
相似文献
Jonathan KaplanEmail: |
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Recent work has demonstrated substantial wiring and functional stereotypy in the fly olfactory system. In this issue of Neuron, Murthy et al. demonstrate that in the mushroom body, a site of olfactory associative learning, this initial peripheral stereotypy gives way to functionally nonstereotyped circuits. 相似文献
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Oliver Massenet Pascal Martinez Patrick Seyer Jean-François Briat 《Plant molecular biology》1987,10(1):53-63
The 2201-bp spacer between the chloroplast ribosomal 16S and 23S genes ofSpinacia oleracea was sequenced. It contains the genes of the tRNAIle (GAU) and tRNAAla (UGC) which are both interrupted by introns of respectively 728 and 816 bp. These introns belong to the class II according to the classfication of Michel and Dujon [17]. Comparison of the rDNA spacer sequence of maize, tobacco and spinach indicates that no conserved polypeptide is encoded within the introns of the two tRNA genes and that the two main insertions/deletions between the three plants are located within two loops of the class II introns secondary structure, which is therefore conserved. Based on the sequence complementarity observed between the upstream and downstream parts, of the 16S and 23S rRNA genes, RNase III-like secondary structures involved in the processing of the rRNA precursor are proposed. 相似文献
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J A Witkowski 《Trends in genetics : TIG》1988,4(2):27-30
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Debates on patenting DNA must evolve to reflect the global decline in filings and regional disparities in patenting activity. 相似文献