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61.
A new hybrid approach to predict subcellular localization of proteins by incorporating gene ontology 总被引:3,自引:0,他引:3
Based on the recent development in the gene ontology and functional domain databases, a new hybridization approach is developed for predicting protein subcellular location by combining the gene product, functional domain, and quasi-sequence-order effects. As a showcase, the same prokaryotic and eukaryotic datasets, which were studied by many previous investigators, are used for demonstration. The overall success rate by the jackknife test for the prokaryotic set is 94.7% and that for the eukaryotic set 92.9%. These are so far the highest success rates achieved for the two datasets by following a rigorous cross-validation test procedure, suggesting that such a hybrid approach may become a very useful high-throughput tool in the area of bioinformatics, proteomics, as well as molecular cell biology. The very high success rates also reflect the fact that the subcellular localization of a protein is closely correlated with: (1). the biological objective to which the gene or gene product contributes, (2). the biochemical activity of a gene product, and (3). the place in the cell where a gene product is active. 相似文献
62.
Bolcato-Bellemin AL Lefebvre O Arnold C Sorokin L Miner JH Kedinger M Simon-Assmann P 《Developmental biology》2003,260(2):376-390
Laminins (comprised of alpha, beta, and gamma chains) are heterotrimeric glycoproteins integral to all basement membranes. The function of the laminin alpha5 chain in the developing intestine was defined by analysing laminin alpha5(-/-) mutants and by grafting experiments. We show that laminin alpha5 plays a major role in smooth muscle organisation and differentiation, as excessive folding of intestinal loops and delay in the expression of specific markers are observed in laminin alpha5(-/-) mice. In the subepithelial basement membrane, loss of alpha5 expression was paralleled by ectopic or accelerated deposition of laminin alpha2 and alpha4 chains; this may explain why no obvious defects were observed in the villous form and enterocytic differentiation. This compensation process is attributable to mesenchyme-derived molecules as assessed by chick/mouse alpha5(-/-) grafted associations. Lack of the laminin alpha5 chain was accompanied by a decrease in epithelial alpha3beta1 integrin receptor expression adjacent to the epithelial basement membrane and of Lutheran blood group glycoprotein in the smooth muscle cells, indicating that these receptors are likely mediating interactions with laminin alpha5-containing molecules. Taken together, the data indicate that the laminin alpha5 chain is essential for normal development of the intestinal smooth muscle and point to possible mesenchyme-derived compensation to promote normal intestinal morphogenesis when laminin alpha5 is absent. 相似文献
63.
Variation in host-specific infectivity was studied in monogenean polystome parasites (Protopolystoma spp.) of the interfertile, parapatric anurans Xenopus laevis laevis and Xenopus muelleri. Laboratory-raised host F1 hybrids were resistant to parasites respectively specific to each parent taxon in nature. This resistance occurred against parasite isolates from both inside and outside a host hybrid/sympatric zone (and no isolate was compatible with the foreign host species under experimental conditions). Geographical Protopolystoma xenopodis isolates showed variable infectivity to a single full-sib group of their usual host, X. l. laevis, and strains with high or low infectivity to these sibs co-occurred in spatially distant local areas (separated by 1,700 km). The host compatibility of P. xenopodis was also subject to host genotypexparasite genotype interactions. Refractoriness to some parasites or pathogens, as a consequence of hybridisation, may have conferred a selective advantage on the allopolyploid pathway by which most Xenopus spp. are believed to have evolved. 相似文献
64.
Diosque P Barnabé C Padilla AM Marco JD Cardozo RM Cimino RO Nasser JR Tibayrenc M Basombrío MA 《International journal for parasitology》2003,33(10):997-1003
A set of 65 Trypanosoma cruzi stocks from dogs, opossums, insect vectors and humans was isolated in a geographically restricted endemic area for Chagas' disease in Argentina and was analysed by multilocus enzyme electrophoresis for 15 loci. The results show that at least five multilocus genotypes (clonets) circulate in the study area, one belonging to T. cruzi IIe, one to T. cruzi IId and three clonets belonging to T. cruzi I; and they confirm the presence of these lineages in the country. The three clonets attributed to T. cruzi I were identical to each other for all loci except for Sod-2, where three different patterns were identified. These patterns suggest the presence of two homozygous genotypes and one heterozygous genotype. Our results also suggest association of clonet IIe with dogs, clonet IId with humans and the three T. cruzi I clonets with Didelphis albiventris. On the other hand, there was no significant association between Triatoma infestans and any particular clonet circulating in the area. These findings are consistent with the hypothesis of natural selection, from mixed populations of T. cruzi in vectors, toward more restricted populations in mammals. The epidemiological implications of the possible selection of different clonets by different mammal hosts and the significance of two homozygous genotypes and one heterozygous genotype for the Sod-2 locus are discussed. 相似文献
65.
The hydrothermal reaction of NiCl2·6H2O, MoO3, 3,4′-bipyridine (3,4′-bpy) and H2O in the mole ratio 1.0:1.0:2.1:1500 yields [Ni(3,4′-bpy)2MoO4]·3H2O (1·3H2O) in 80% yield. The structure of 1·3H2O consists of a three-dimensional coordination polymer {Ni(3,4′-bpy)2}n2n+ with entrained {MoO4}2− tetrahedra and with water molecules of crystallization occupying channels within the bimetallic oxide-ligand framework. Crystal data: C20H16N4O4NiMo·3H2O (1·3H2O), tetragonal P41212, a=13.1866(5) Å, c=29.458(2) Å, V=5122.3(4) Å3, Z=8, Dcalc=1.532 g cm−3. 相似文献
66.
Christopher?T.?WalshEmail author Sarah?E.?O'Connor Tanya?L.?Schneider 《Journal of industrial microbiology & biotechnology》2003,30(8):448-455
The epothilones are a family of macrolactone natural products from the myxobacterial species Sorangium cellulosum. Similar to taxol, they are of current clinical interest as anticancer agents. Sequence analysis of the epothilone gene cluster
allowed the identification of polyketide synthase and nonribosomal peptide synthetase modules involved in catalyzing epothilone
biosynthesis. Given this information, it has been possible to test the predicted functions of several modules to date. EpoA
ACP, EpoB, and EpoC have been overproduced in Escherichia coli, allowing in vitro reconstitution of the EpoA/B/C interface and production of the expected epothilone precursor. Further
experiments probed the tolerance of EpoB and EpoC for unnatural substrates. These studies of the first three modules of the
epothilone biosynthetic cluster suggest that combinatorial biosynthesis may lead to the production of a variety of epothilone
analogs that incorporate diversity into the heterocycle starter unit. Additional efforts with the remaining modules, coupled
with increased understanding of the macrocyclizing thioesterase domain, may lead to the production of epothilone variants
with improved clinical properties. 相似文献
67.
Solaiman DK 《Journal of industrial microbiology & biotechnology》2003,30(5):322-326
Pseudomonas resinovorans harbors two isogenic poly(hydroxyalkanoates) (PHAs) synthase genes (phaC1
Pre
, phaC2
Pre
) responsible for the production of intracellular medium-chain-length (mcl-)PHAs. Sequence analysis showed that the putative
gene-products of these genes contain a conserved α/β-hydrolase fold in the carboxy-terminal half of the proteins. Hybrid genes pha7 and pha8 were constructed by exchanging the α/β-hydrolase-fold coding portions of phaC1
Pre
and phaC2
Pre
at the 3′ terminal. When grown with decanoate as carbon source, the pha7- or pha8-transformed Escherichia coli LS1298 produced PHAs containing 73–75% β-hydroxydecanoate (β-HD) and 25–27% β-hydroxyoctanoate (β-HO). Deletion mutants,
Δpha7 and Δpha8, were isolated during the PCR-based construction of pha7 and pha8, respectively. Cells harboring these mutants produced PHAs containing 55–60 mol% β-HD and 40–45 mol% β-HO. These results
demonstrate the feasibility of generating active hybrid mcl-PHA synthase genes and their mutants with the potential of producing
polymers having a varied repeat-unit composition. 相似文献
68.
P. K. Subudhi S. Nandi C. Casal S. S. Virmani N. Huang 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(6-7):941-949
The cytoplasmic genetic male-sterile (CMS) lines developed at the International Rice Research Institute are valuable in producing
tropical rice hybrids. Efficient use of CMS lines in hybrid rice production will depend on their level of genetic diversity.
Aside from morphological characterization, molecular analysis based on DNA markers can provide information on the genetic
diversity of the germplasm. The Amplified Fragment Length Polymorphism (AFLP) technique was used to fingerprint 71 CMS lines
and four rice cultivars, ‘IR64’, ‘Azucena’, ‘IR74’, and ‘FR13A’. Eleven primer pair combinations specific to the enzymes PstI and MseI were used to generate 530 AFLP markers, 176 of which were polymorphic. Each CMS line revealed a distinct fingerprint. The
AFLP marker-based dendrogram depicted genetic variation among the CMS lines. The CMS lines developed in japonica background
grouped with ‘Azucena’, a japonica cultivar. None of the CMS lines clustered with ‘FR13A’, a flood-tolerant traditional indica
variety. ‘IR64’ was found to be distinct from the other indica CMS lines and clustered with lines developed in its background.
The grouping of CMS lines into a few groups is useful for breeders in selecting genetically diverse CMS lines for hybrid rice
production and in avoiding test crossing every CMS line empirically. This study demonstrated that AFLP is a powerful and reliable
tool in determining the genetic relationships and in producing distinct fingerprints of rice cultivars.
Received: 20 December 1996 / Accepted: 9 October 1997 相似文献
69.
Alexander F. Arendsen Jonathan Hadden Graeme Card Alan S. McAlpine Susan Bailey Vjacheslav Zaitsev Elizabeth H. M. Duke P. F. Lindley Monika Kröckel Alfred X. Trautwein Martinus C. Feiters John M. Charnock C. David Garner Sophie J. Marritt Andrew J. Thomson Ingeborg M. Kooter Michael K. Johnson Willy A. M. van den Berg Walter M. A. M. van Dongen W. R. Hagen 《Journal of biological inorganic chemistry》1998,3(1):81-95
The three-dimensional structure of the native "putative prismane" protein from Desulfovibrio vulgaris (Hildenborough) has been solved by X-ray crystallography to a resolution of 1.72?Å. The molecule does not contain a [6Fe-6S] prismane cluster, but rather two 4Fe clusters some 12?Å apart and situated close to the interfaces formed by the three domains of the protein. Cluster 1 is a conventional [4Fe-4S] cubane bound, however, near the N-terminus by an unusual, sequential arrangement of four cysteine residues (Cys 3, 6, 15, 21). Cluster 2 is a novel 4Fe structure with two μ2-sulfido bridges, two μ2-oxo bridges, and a partially occupied, unidentified μ2 bridge X. The protein ligands of cluster 2 are widely scattered through the second half of the sequence and include three cysteine residues (Cys 312, 434, 459), one persulfido-cysteine (Cys 406), two glutamates (Glu 268, 494), and one histidine (His 244). With this unusual mixture of bridging and external type of ligands, cluster 2 is named the "hybrid" cluster, and its asymmetric, open structure suggests that it could be the site of a catalytic activity. X-ray absorption spectroscopy at the Fe K-edge is readily interpretable in terms of the crystallographic model when allowance is made for volume contraction at 10?K; no Fe··Fe distances beyond 3.1?Å could be identified. EPR, Mössbauer and MCD spectroscopy have been used to define the oxidation states and the magnetism of the clusters in relation to the crystallographic structure. Reduced cluster 1 is a [4Fe-4S]1+ cubane with S?=?3/2; it is the first biological example of a "spin-admixed" iron-sulfur cluster. The hybrid cluster 2 has four oxidation states from (formally) all FeIII to three FeII plus one FeIII. The four iron ions are exchange coupled resulting in the system spins S?=?0, 9/2, 0 (and 4), 1/2, respectively, for the four redox states. Resonance Raman spectroscopy suggests that the bridging ligand X which could not be identified unambiguously in the crystal structure is a solvent-exchangeable oxygen. 相似文献
70.
接穗郁李影响杏砧变异的实验 总被引:3,自引:2,他引:3
陕西省咸阳市渭城中学范盛尧老师通过芽接实验, 使接穗郁李影响杏砧。经过一定时间的生理变化, 先营养器官, 后生殖器官, 使杏砧蘖生植株呈现出郁李性状。作者的本意是希望通过本刊寻求对这些现象的科学解释。现发表此文, 以引起学者的关注。本刊愿作生物教师的朋友, 欢迎大家就生物遗传的教学及科研等问题踊跃供稿; 广大读者对本文如有不同见解, 欢迎参加讨论。 相似文献