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991.
992.
Protein threading by recursive dynamic programming. 总被引:4,自引:0,他引:4
We present the recursive dynamic programming (RDP) method for the threading approach to three-dimensional protein structure prediction. RDP is based on the divide-and-conquer paradigm and maps the protein sequence whose backbone structure is to be found (the protein target) onto the known backbone structure of a model protein (the protein template) in a stepwise fashion, a technique that is similar to computing local alignments but utilising different cost functions. We begin by mapping parts of the target onto the template that show statistically significant similarity with the template sequence. After mapping, the template structure is modified in order to account for the mapped target residues. Then significant similarities between the yet unmapped parts of the target and the modified template are searched, and the resulting segments of the target are mapped onto the template. This recursive process of identifying segments in the target to be mapped onto the template and modifying the template is continued until no significant similarities between the remaining parts of target and template are found. Those parts which are left unmapped by the procedure are interpreted as gaps.The RDP method is robust in the sense that different local alignment methods can be used, several alternatives of mapping parts of the target onto the template can be handled and compared in the process, and the cost functions can be dynamically adapted to biological needs.Our computer experiments show that the RDP procedure is efficient and effective. We can thread a typical protein sequence against a database of 887 template domains in about 12 hours even on a low-cost workstation (SUN Ultra 5). In statistical evaluations on databases of known protein structures, RDP significantly outperforms competing methods. RDP has been especially valuable in providing accurate alignments for modeling active sites of proteins.RDP is part of the ToPLign system (GMD Toolbox for protein alignment) and can be accessed via the WWW independently or in concert with other ToPLign tools at http://cartan.gmd.de/ToPLign.html. 相似文献
993.
The biology of insularity: an introduction 总被引:5,自引:0,他引:5
Donald R. Drake Christa P. H. Mulder David R. Towns & Charles H. Daugherty 《Journal of Biogeography》2002,29(5-6):563-569
994.
Contrary to theoretical predictions, female 2‐spot ladybirds (Adalia bipunctata) mate many more times than necessary to maintain high fertilisation success and may gain through the acquisition of material or genetic benefits. In order to investigate this mating system in detail, microsatellite markers have been isolated using a modified enrichment technique. Thirty‐nine loci were successfully amplified by polymerase chain reaction (PCR), of which only two were monomorphic. Detailed characterization of ten loci revealed very high levels of polymorphism. These markers are likely to be invaluable tools with which to study population genetics and patterns of paternity in this species. 相似文献
995.
V. Selvakumar P. R. Anbudurai T. Balakumar 《In vitro cellular & developmental biology. Plant》2001,37(2):280-284
Summary A protocol for rapid in vitro propagation using nodal explants obtained from 2-yr-old, field-grown medicinal plants of Plumbago zeylanica L. belonging to the family Plumbaginaceae is described. High frequency bud break and fast development of shoots were induced
on Murashige and Skoog's basal medium supplemented with 27.2 μM adenine sulfate +2.46 μM indole-3-butyric acid (IBA). Induction of rooting was achieved by transferring the shoots to the same basal medium containing
4.92 μM IBA. Using our protocol from one twig of P. zeylanica (eight responsive nodes per explant shoot) within a period of 5 mo., eight plantlets could be raised. After a hardening period
of 4 wk, there was a 90% transplantation success in the field compared to the 60–65% survival of plantlets recorded in the
experiments of previous workers. The plantlets derived through in vitro propagation mimic the growth and morphological characteristics of the donor plants. 相似文献
996.
997.
Regulated exocytosis is controlled by internal and external signals. The molecular machinery controlling the sorting from the newly synthesized vesicles from the Golgi apparatus to the plasma membrane play a key role in the regulation of both the number and spatial location of the vesicles. In this context the mammalian acrosome is a unique vesicle since it is the only secretory vesicle attached to the nucleus. In this work we have studied the membrane trafficking between the Golgi apparatus and the acrosome during mammalian spermiogenesis. During bovine spermiogenesis, Golgi antigens (mannosidase II) were detected in the acrosome until the late cap-phase spermatids, but are not found in testicular spermatozoa (maturation-phase spermatids). This suggests that Golgiacrosome flow may be relatively unselective, with Golgi residents retrieved before spermination is complete. Surprisingly, rab7, a protein involved in lysosome/endosome trafficking was also found associated with the acrosomal vesicle during mouse spermiogenesis. Our results suggest that the acrosome biogenesis is associated with membrane flow from both the Golgi apparatus and the endosome/lysosome system in mammalian spermatids. 相似文献
998.
The identification and characterization of differential gene expression from tissues subjected to stress has gained much attention in plant research. The recognition of elements involved in the response to a particular stress enhances the possibility of promoting crop improvement through direct genetic modification. However, the performance of some of the 'first generation' of transgenic plants with the incorporation of a single gene has not always been as expected. These results have stimulated the development of new transgenic constructions introducing more than one gene and capable of modifying complex pathways. Several techniques are available to conduct the analysis of gene regulation, with such information providing the basis for novel constructs specifically designed to modify metabolism. This review deals with techniques that allow the identification and characterization of differentially-expressed genes and the use of molecular pathway information to produce transgenic plants. 相似文献
999.
D. R. Knott 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,103(1):171-177
The action of the gene Sr6 for stem rust resistance in wheat is affected by temperature, light, and the particular susceptible parent with which a line
carrying Sr6 has been crossed. Two experiments were carried out to determine whether the effect of the susceptible parents was due to
modifier genes, the general genetic background, or interallelic interactions. The data indicated that the susceptible parents
carried different sr6 alleles that interacted with Sr6, possibly in a paramutation-like process. In the course of the study, a number of anomalous results were obtained that may
be due to the action of transposable elements.
Received: 18 February 2000 / Accepted: 31 October 2000 相似文献
1000.