共查询到20条相似文献,搜索用时 31 毫秒
1.
Background
The protein folding problem is a fundamental problems in computational molecular biology and biochemical physics. Various optimisation methods have been applied to formulations of the ab-initio folding problem that are based on reduced models of protein structure, including Monte Carlo methods, Evolutionary Algorithms, Tabu Search and hybrid approaches. In our work, we have introduced an ant colony optimisation (ACO) algorithm to address the non-deterministic polynomial-time hard (NP-hard) combinatorial problem of predicting a protein's conformation from its amino acid sequence under a widely studied, conceptually simple model – the 2-dimensional (2D) and 3-dimensional (3D) hydrophobic-polar (HP) model. 相似文献2.
T. Aravinda H. S. Bhojya Naik H. R. Prakash Naik 《International journal of peptide research and therapeutics》2009,15(4):273-279
Abstract
We present, simple approach for the accession of 1,2,3-triazole fused quinoline peptide analogues from 3-(azidomethyl)-2-chloroquinoline in a three-step mechanistic pathway. The UV–Visible absorbance plot shows dynamic interaction of parent triazole derivative with CT DNA as efficient DNA intercalator (K b = 4.6 × 10−4 M−1). Finally, the efficient DNA damage was observed on photo-irradiation at 360 nm in the presence of 2-(9H-Fluoren-9-ylmethoxycarbonylamino)-propionic acid 1-(2-chloro-quinolin-3-ylmethyl)-1H-[1,2,3]triazole-4-ylmethyl ester (6a). 相似文献3.
Background
Gradients of morphogens pattern cell fate – a phenomenon that is especially important during development. A simple model system for studying how morphogens pattern cell behavior would overcome difficulties inherent in the study of natural morphogens in vivo. A synthetic biology approach to building such a system is attractive. 相似文献4.
Background
A major cornerstone of evolutionary biology theory is the explanation of the emergence of cooperation in communities of selfish individuals. There is an unexplained tendency in the plant and animal world – with examples from alpine plants, worms, fish, mole-rats, monkeys and humans – for cooperation to flourish where the environment is more adverse (harsher) or more unpredictable. 相似文献5.
Gráinne H Long Brian HK Chan Judith E Allen Andrew F Read Andrea L Graham 《BMC evolutionary biology》2008,8(1):128
Background
Explaining parasite virulence (harm to the host) represents a major challenge for evolutionary and biomedical scientists alike. Most theoretical models of virulence evolution assume that virulence arises as a direct consequence of host exploitation, the process whereby parasites convert host resources into transmission opportunities. However, infection-induced disease can be immune-mediated (immunopathology). Little is known about how immunopathology affects parasite fitness, or how it will affect the evolution of parasite virulence. Here we studied the effects of immunopathology on infection-induced host mortality rate and lifetime transmission potential – key components of parasite fitness – using the rodent malaria model, Plasmodium chabaudi chabaudi. 相似文献6.
Niall De Lappe Jean O Connor Geraldine Doran Genevieve Devane Martin Cormican 《BMC microbiology》2009,9(1):155-6
Background
With the exception of M. tuberculosis, little has been published on the problems of cross-contamination in bacteriology laboratories. We performed a retrospective analysis of subtyping data from the National Salmonella Reference Laboratory (Ireland) from 2000–2007 to identify likely incidents of laboratory cross contamination. 相似文献7.
Nunzio D'Agostino Daniele Pizzichini Maria Luisa Chiusano Giovanni Giuliano 《BMC plant biology》2007,7(1):53
Background
Saffron (Crocus sativus L., Iridaceae) flowers have been used as a spice and medicinal plant ever since the Greek-Minoan civilization. The edible part – the stigmas – are commonly considered the most expensive spice in the world and are the site of a peculiar secondary metabolism, responsible for the characteristic color and flavor of saffron. 相似文献8.
Christopher L Douglas Vladyslav Vyazovskiy Teresa Southard Shing-Yan Chiu Albee Messing Giulio Tononi Chiara Cirelli 《BMC biology》2007,5(1):42
Background
Shaker codes for a Drosophila voltage-dependent potassium channel. Flies carrying Shaker null or hypomorphic mutations sleep 3–4 h/day instead of 8–14 h/day as their wild-type siblings do. Shaker-like channels are conserved across species but it is unknown whether they affect sleep in mammals. To address this issue, we studied sleep in Kcna2 knockout (KO) mice. Kcna2 codes for Kv1.2, the alpha subunit of a Shaker-like voltage-dependent potassium channel with high expression in the mammalian thalamocortical system. 相似文献9.
Background
Identifying large gene regulatory networks is an important task, while the acquisition of data through perturbation experiments (e.g., gene switches, RNAi, heterozygotes) is expensive. It is thus desirable to use an identification method that effectively incorporates available prior knowledge – such as sparse connectivity – and that allows to design experiments such that maximal information is gained from each one. 相似文献10.
Juan A Sánchez Catalina Aguilar Daniel Dorado Nelson Manrique 《BMC evolutionary biology》2007,7(1):122
Background
Colonial invertebrates such as corals exhibit nested levels of modularity, imposing a challenge to the depiction of their morphological evolution. Comparisons among diverse Caribbean gorgonian corals suggest decoupling of evolution at the polyp vs. branch/internode levels. Thus, evolutionary change in polyp form or size (the colonial module sensu stricto) does not imply a change in colony form (constructed of modular branches and other emergent features). This study examined the patterns of morphological integration at the intraspecific level. Pseudopterogorgia bipinnata (Verrill) (Octocorallia: Gorgoniidae) is a Caribbean shallow water gorgonian that can colonize most reef habitats (shallow/exposed vs. deep/protected; 1–45 m) and shows great morphological variation. 相似文献11.
The purpose of this research was to study whether the bioavailability of ursodeoxycholic acid could be improved by administering
ursodeoxycholic acid–phospholipid complex (UDCA–PLC) orally to rats. A central composite design approach was used for process
optimization in order to obtain the acceptable UDCA–PLC. The physicochemical properties of the complex obtained by optimal
parameters were investigated by means of scanning electron microscopy and X-ray diffraction. The pharmacokinetic parameters
and bioavailability studies were conducted in rats of UDCA after oral administration of UDCA–PLC and UDCA tablet. Multiple
linear regression analysis for process optimization revealed that the acceptable UDCA–PLC was obtained wherein the optimal
values of X
1, X
2 and X
3 were 3, 60°C and 3 h, respectively. The XRD studies of UDCA–PLC obtained by the optimal parameters demonstrated that UDCA
and phospholipids in the UDCA–PLC were combined by non-covalent bonds, not form new compounds. But pharmacokinetic parameters
of the complex in rats were T
max 1.6 h, C
max 0.1346 μg/ml, 11.437 μg·h/ml, respectively. The relative bioavailability of UDCA of UDCA–PLC was increased by 241%,compared with the reference
ursodeoxycholic acid tablet. 相似文献
12.
David M Kristensen R Matthew Ward Andreas Martin Lisewski Serkan Erdin Brian Y Chen Viacheslav Y Fofanov Marek Kimmel Lydia E Kavraki Olivier Lichtarge 《BMC bioinformatics》2008,9(1):17
Background
Structural genomics projects such as the Protein Structure Initiative (PSI) yield many new structures, but often these have no known molecular functions. One approach to recover this information is to use 3D templates – structure-function motifs that consist of a few functionally critical amino acids and may suggest functional similarity when geometrically matched to other structures. Since experimentally determined functional sites are not common enough to define 3D templates on a large scale, this work tests a computational strategy to select relevant residues for 3D templates. 相似文献13.
Background
Model violations constitute the major limitation in inferring accurate phylogenies. Characterizing properties of the data that are not being correctly handled by current models is therefore of prime importance. One of the properties of protein evolution is the variation of the relative rate of substitutions across sites and over time, the latter is the phenomenon called heterotachy. Its effect on phylogenetic inference has recently obtained considerable attention, which led to the development of new models of sequence evolution. However, thus far focus has been on the quantitative heterogeneity of the evolutionary process, thereby overlooking more qualitative variations. 相似文献14.
A bio-trickling filter (BTF) packed with polyhedral spheres was used to remove nitrogen oxides (NOx) from the flue gas of
a coal-fired power plant. The BTF system consistently removed 64–95% of the NOx after start-up and acclimation under dynamic
conditions (e.g., 120–240 m3/h flue gas flow rate and inlet 300–900 mg NOx/m3). Scanning electron microscopy of the biofilms that were formed showed a shift in the predominating bacteria. Analyses by
PCR-denaturing gradient gel electrophoresis showed that the naturally-selected mixed cultures in the biofilm under a flue
gas environment were mainly Klebsiella sp. and Pseudomonas sp. 相似文献
15.
Svetlana?E?Moskalenko Svetlana?V?Chabelskaya Sergei?G?Inge-Vechtomov Michel?Philippe Galina?A?Zhouravleva
Background
Termination of protein synthesis in eukaryotes involves at least two polypeptide release factors (eRFs) – eRF1 and eRF3. The highly conserved translation termination factor eRF1 in Saccharomyces cerevisiae is encoded by the essential gene SUP45. 相似文献16.
Background
Safflower (Carthamus tinctorius L.) is a diploid oilseed crop whose origin is largely unknown. Safflower is widely believed to have been domesticated over 4,000 years ago somewhere in the Fertile Crescent. Previous hypotheses regarding the origin of safflower have focused primarily on two other species from sect. Carthamus – C. oxyacanthus and C. palaestinus – as the most likely progenitors, although some attention has been paid to a third species (C. persicus) as a possible candidate. Here, we describe the results of a phylogenetic analysis of the entire section using data from seven nuclear genes. 相似文献17.
Background
Fungi from environmental samples are typically identified to species level through DNA sequencing of the nuclear ribosomal internal transcribed spacer (ITS) region for use in BLAST-based similarity searches in the International Nucleotide Sequence Databases. These searches are time-consuming and regularly require a significant amount of manual intervention and complementary analyses. We here present software – in the form of an identification pipeline for large sets of fungal ITS sequences – developed to automate the BLAST process and several additional analysis steps. The performance of the pipeline was evaluated on a dataset of 350 ITS sequences from fungi growing as epiphytes on building material. 相似文献18.
Antoine Branca Fabrice Vavre Jean-Fran?ois Silvain Stéphane Dupas 《BMC evolutionary biology》2009,9(1):185
Background
Bacteria of the genus Wolbachia are reproductive parasites widespread among arthropods. The most common effect arising from the presence of Wolbachia in a population is Cytoplasmic Incompatibility (CI), whereby postmating reproductive isolation occurs in crosses between an infected male and an uninfected female, or when a male is infected with a different strain of Wolbachia to that of the female (bidirectional CI). Previous theoretical models have demonstrated that bidirectional CI can contribute to the genetic divergence of populations in haploid and diploid organisms. However, haplodiploid organisms were not considered in these models even though they include Nasonia parasitoid wasps – the best example of the implication of Wolbachia in ongoing speciation. Moreover, previous work did not investigate inbreeding mating systems, which are frequently observed in arthropod species. 相似文献19.
Three novel strains capable of heterotrophic nitrification–aerobic denitrification were isolated from the landfill leachate
treatment system. Based on their phenotypic and phylogenetic characteristics, the isolates were identified as Agrobacterium sp. LAD9, Achromobacter sp. GAD3 and Comamonas sp. GAD4, respectively. Batch tests were carried out to evaluate the growth and the ammonia removal patterns. The maximum
growth rates as determined from the growth curve were 0.286, 0.228, and 0.433 h−1 for LAD9, GAD3 and GAD4, respectively. The maximum aerobic nitrification–denitrification rate was achieved by the strain
GAD4 of 0.381 mmol/l h, followed by LAD9 of 0.374 mmol/l h and GAD3 of 0.346 mmol/l h. Moreover, hydroxylamine oxidase and
periplasmic nitrate reductase were successfully expressed in all the isolates. The relationship between the enzyme activities
and the aerobic nitrification–denitrification rates revealed that hydroxylamine oxidation may be the rate-limiting step in
the heterotrophic nitrification–aerobic denitrification process. The study results are of great significance to the wastewater
treatment systems where simultaneous removal of carbon and nitrogen is desired. 相似文献