Últimos itens adicionados do Acervo: Proceedings Nature

Nature é uma das mais prestigiosas e antigas revistas científicas do mundo: sua primeira edição é de 4 de novembro de 1869. Entre as inúmeras descobertas científicas publicadas na Nature estão a dos raios X, da estrutura em dupla hélice do ADN e o buraco na camada de ozônio.

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‣ Structure Prediction and Functional Characterization of ERG Proteins Involved in Ergosterol Biosynthetic Pathway of Candida albicans

Sudeep Roy; Suaib Luqman; Ashok Sharma
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
The ERG proteins and enzymes of the ergosterol biosynthetic pathway has been the subject of intensive investigation as a target for several classes of antifungal agents used to treat C. albicans infection. Over the past few decades, a number of drugs and inhibitors with wide spectrum of activity, low toxicity and defined targets have been introduced. Several lines of evidence suggest that allylamines targets squalene epoxidase (ERG1), morpholines affects sterol C8-C7 isomerase (ERG2) and sterol reductase (ERG24), azoles inhibits a cytochrome P450 (ERG11) responsible for the 14 α-demethylation of lanosterol and C-5 sterol desaturase (ERG3) and polyenes binds to ergosterol that leads to the damage of cell plasma membrane, ensuing in leakage of intracellular ions. However, little information about the experimental structure (X-ray and NMR) of proteins from ergosterol biosynthetic pathway is available in RCSB Protein Databank (PDB). Since ERG proteins play a key role in metabolic pathway of ergosterol, their 3D structures are essential to determine most of their functions. Homology modeling approach was employed for comparative modeling. Modeller 9v7 and I-Tasser programs were utilized to serve our purpose. The modeled proteins were further validated by Procheck...

‣ Geographical and chronological origin and evolution of Hepatitis C Virus.

amjesh revikumar; Achuthsankar S. Nair; Sugunan V.S.
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Hepatitis C Virus (HCV) infection is a major health problem that leads to cirrhosis and hepatocellular carcinoma. World over, more than 270-300 million people are estimated to be infected with the virus. HCV is a positive sense single stranded RNA virus and replicates within the cytoplasm of the hepatocyte using its own RNA dependent RNA polymerase (RdRp). RdRp does not have proof reading capacity, and hence generates mutants of the virus, resulting in a chronic infection, which ultimately ends in hepatocellular carcinoma. Such mutations have given rise to several genotypes, subtypes, strains and variants with significant difference in disease outcomes. The mutation rate varies among genotypes, subtypes, strains or even in different sites of the genome. Yet, the extent of heterogeneity is usually moderate, so that estimates of the time of divergence can be computed. The evolution of variants seems to be influenced by the genetic make-up and the immune response of the host and has geographical significance. Here we used phylogenetic analysis and Computational molecular dating techniques to conclude that the ancestral genotype is 7a and that it originated in Canada 363 years ago. Molecular dating was based on the fact that the rate of mutation across all evolutionary lineages is constant over time. Surprisingly...

‣ A snake of a different color: physiological color change in Arizona black rattlesnakes

Melissa Amarello; Jeffrey J. Smith
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
Coloration may serve a variety of behavioral (e.g., crypsis, communication) and physiological (e.g., thermoregulation, protection) functions for terrestrial ectotherms. However, optimal coloration for a given function may vary over environments (spatial or temporal) or conflict with other functions. Physiological color change (rapid change due to movement of pigment granules within chromatophores) may be an adaptation to resolve conflicting selective pressures on coloration. The proximate factors related to physiological color change are well known in many animals, but few studies have investigated the ecological or evolutionary implications of this behavior. Here, we present alternative hypotheses for physiological color change and discuss biotic and abiotic factors that may have led to the maintenance and/or loss of this behavior among populations of Arizona black rattlesnakes (_Crotalus cerberus_). We discuss what is known about this behavior and propose to investigate the function and evolution of coloration and color change in _C. cerberus_.

‣ Time Trends for Agricultural Crop Production in Saskatchewan, Canada: 1905-2011

Sierra Rayne; Kaya Forest
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
Saskatchewan, Canada, with a total land area of 651,900 km^2^, is one of the world’s most productive agricultural cropping regions. Approximately 44% of Canada's total cultivated farmland is in the province. In 2008, the total export value of crops was CAD$8.34 billion. Over the past century, changing industry economics and advances in scientific, technical, and engineering knowledge and practices have affected the amount and type of crops produced. The current work examines time trends for agricultural crop production since Saskatchewan was created in 1905. While yields of all crops have generally increased over time, total production trends vary widely by crop, warranting more detailed investigations into the socio-economical and technological drivers behind such changes.

‣ Time Trends for Livestock Production in Saskatchewan, Canada: 1905-2011

Sierra Rayne; Kaya Forest
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
Saskatchewan, Canada, with a total land area of 651,900 km^2^, is one of the world’s most productive agricultural regions. A broad variety of livestock are raised in the province, including cattle, pigs, poultry, sheep/goats, llama, ostrich, elk, deer, and bison. In 2010, the total revenue from the Saskatchewan livestock sector was CAD$1.6 billion. Over the past century, changing industry economics and advances in scientific, technical, and engineering knowledge and practices have affected the amount and type of livestock produced. The current work examines time trends for livestock production since Saskatchewan was created in 1905. While production trends vary widely by livestock type, most sectors display clearly increasing amounts of industry consolidation over time, warranting more detailed investigations into the socio-economical and technological drivers behind such changes.

‣ Causal Stability Ranking

Daniel J. Stekhoven; Lars Hennig; Gardar Sveinbjörnsson; Izabel Moraes; Marloes H. Maathuis; Peter Bühlmann
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Genotypic causes of a phenotypic trait are typically determined via randomized controlled intervention experiments. Such experiments are often prohibitive with respect to durations and costs. We therefore consider inferring stable rankings of genes, according to their causal effects on a phenotype, from observational data only. Our method allows for efficient design and prioritization of future experiments, and due to its generality it is useable for a broad spectrum of applications.

‣ In silico comparative analysis of conserved genes expressed in solanaceous plants under abiotic stresses

sanchita gupta; sunita singh dhawan; ashok sharma
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
The gene expression data was studied in order to analyze genes involved in different abiotic stresses in solanaceous plants. Salt, temperature (heat & cold) and drought are the main abiotic stresses to the plants. Abiotic stress responses are important for sessile organisms like plants because they have to cope with environmental changes to survive. The idea was to analyze those differentially expressed genes, which show common expression in response to different abiotic stress conditions in each plant. Mitogen activated protein kinases (MAPK) are important mediators in signal transmission, connecting the perception of external stimuli to cellular responses. In plants, MAPKs plays a major role in the signaling of abiotic stresses. The expression data were retrieved from gene expression omnibus (GEO) database at NCBI. The set of genes were selected showing up or down regulation in at least two abiotic stresses. These genes were used for searching their involvement in different steps of MAP kinase pathway. Our findings suggest that a common set of genes are the key players in signaling pathway responsible for initiation of cascade of reaction in response to stress. The study will help to understand how the conserved genes are expressing differentially in response to various abiotic stresses. The common genes affecting the MAP kinase pathway might be highly conserved. These genes may be used to study the response of different abiotic stresses in other plant species.

‣ JSBML: a flexible and entirely Java-based library for working with SBML

Nicolas Rodriguez; Marine Dumousseau; Andreas Dräger; Clemens Wrzodek; Alexander Dörr; Sarah M. Keating; Akiya Jouraku; Nicolas Le Novère; Andreas Zell; Michael Hucka
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
The XML-based Systems Biology Markup Language (SBML) is the de facto standard file format for the storage and exchange of biochemical network models, and is supported by more than 180 software packages to date. Much of this success is due to its clearly defined specifications and the availability of libSBML, a portable, robust, and easy-to-use library. LibSBML provides many methods for manipulating and validating SBML files through its Application Programming Interface (API). Originally written in C and C++, libSBML also provides automatically-generated language bindings for Java, MATLAB, Perl, and many more. However, the platform independence of Java is compromised in libSBML due to the fact that the language binding is a wrapper around the C/C++ core. The real-world experiences of many software developers has been that the deployment of portable libSBML-based Java applications is difficult. Further, the libSBML API and type hierarchy are not sufficiently intuitive from a Java programmer's perspective just because they were not designed directly for Java. For these reasons, several groups in the SBML community have mounted an open-source effort to develop a pure Java library for SBML. Here we present the JSBML project...

‣ Determinative atom model and the nature of chemical bond

Wanchung Hu
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Quantum mechanics including Schrodinger and Dirac’s equations are used to describe the atom model. However, the basic assumption assuming electron energy can be described by E=h’w is wrong. If E=h’w, then the total energy of the electron will be E=rmv^2 in contrary to E=rmc^2 from special relativity. Here, I propose a new atom model integrating frame-dragging force, centrifugal force, electrostatic force, and magnetic force. In this new model, the proton group and neutron group in atomic nucleus are rotating in different direction. Thus, they provide equal and opposite frame-dragging force for orbiting electrons. The electrons are orbiting in the equator plane of nucleus. There is no net force or net acceleration for electrons to allow electrons for stable orbiting. 1.Electrostatic force from protons balances centrifugal force. 2. Electrostatic force from paired electron itself balances magnetic force from spinning electrons. 3. No net frame-dragging force from proton group and neutron group. In addition, by using De Brodglie’s matter wave and standing wave concept, we can explain the atomic magic number 2,8,8,18,18,32,32. The electron is basically a particle, but it moves like a wave. By using this atom model...

‣ Balancing noise and plasticity in gene expression

Djordje Bajic; Juan F. Poyatos
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Coupling the control of expression stochasticity (noise) with the capacity to expression change (plasticity) can constrain gene function and limit adaptation. Which factors contribute then to modulate this coupling? Transcription re-initiation is generally associated with coupling and this is commonly related to strong chromatin regulation. We alternatively show how strong regulation can however lead to plasticity uncorrelated to noise. The character of the regulation is also relevant, with plastic but noiseless genes usually subjected to broad expression activation whereas plastic and noisy genes experience targeted repression. This differential action is similarly noticed in how histones influence these genes. In contrast, we find that translational mechanisms are the ones separating noise from plasticity in low-plastic genes, a pattern associated with the simplicity of their expression regulation. Neighboring genome architecture as modifier appears then only effective in highly plastic genes. This poses ultimately an interesting paradox between intergenic distances and modulation, with short intergenic distances both associated and not associated with noise at different plasticity levels. Balancing the coupling among different types of expression variability appears thus as a potential shaping force of genome architecture and regulation.

‣ Accurate Reconstruction of Molecular Phylogenies for Proteins Using Codon and Amino Acid Unified Sequence Alignments (CAUSA)

Xiaolong Wang; Yu Fu; Yue Zhao; Qi Wang; Chandra Sekhar Pedamallu; Shuang-yong Xu; Yingbo Niu; Jingjie Hu
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Based on molecular clock hypothesis, and neutral theory of molecular evolution, molecular phylogenies have been widely used for inferring evolutionary history of organisms and individual genes. Traditionally, alignments and phylogeny trees of proteins and their coding DNA sequences are constructed separately, thus often different conclusions were drawn. Here we present a new strategy for sequence alignment and phylogenetic tree reconstruction, codon and amino acid unified sequence alignment (CAUSA), which aligns DNA and protein sequences and draw phylogenetic trees in a unified manner. We demonstrated that CAUSA improves both the accuracy of multiple sequence alignments and phylogenetic trees by solving a variety of molecular evolutionary problems in virus, bacteria and mammals. Our results support the hypothesis that the molecular clock for proteins has two pointers existing separately in DNA and protein sequences. It is more accurate to read the molecular clock by combination (additive) of these two pointers, since the ticking rates of them are sometimes consistent, sometimes different. CAUSA software were released as Open Source under GNU/GPL license, and are downloadable free of charge from the website www.dnapluspro.com.

‣ NPY Levels In Type 1 Diabetic Men of Different Duration.

Riccardo Volpi; Anna Araldi; Simona Cataldo; Maria Grazia Magotti; Luigi Capretti; Vittorio Coiro; Claudio Giumelli; Teore Ferri; Roberta Minelli; Lavinia Volpi; Paolo Chiodera
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Background: The aim of the present study was to evaluate whether the different duration of type 1 diabetes mellitus influences basal NPY secretion. Design: The NPY concentrations were measured in sixty-eight men with insulin-dependent diabetes mellitus (IDDM) (duration: group 1 (n.21) <5 years (range 2-4 years); group 2 (n.24) >5 years and <10 years (range: 6-9 years); group 3 (n.29) >10 years (range: 11-14 years)) and in age matched normal control subjects (n. 30). Results: The NPY levels were significantly lower in group 3 than in group 2 and 1 and in the control group, in group 2 than in group 1 and in the control group and in group 1 than control group. Conclusion: These results support the view that the duration of diabetes may have a modulatory role in the decreased basal NPY secretion observed in diabetics.

‣ Limitation of F1 hybrids uniformity law

Evgenii Levites
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Using isozymes as markers, data indicative of polymorphisms in the progeny produced from crossing two beet plants, homozygous on contrastive alleles of enzyme loci, were obtained.

‣ Optogenetics in primates: monkey see monkey look

Mehrdad Jazayeri; Zachary Lindbloom-Brown; Gregory Horwitz
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Optogenetics has emerged as a powerful tool for studying the neural basis of simple behaviors in rodents and small animals. In the primate model, however, optogenetics has had limited utility because optical methods have not been able to drive behavior. Here, we report that monkeys reliably shift their gaze toward the receptive field of optically driven channelrhodopsin-2-expressing V1 neurons. This result establishes optogenetics as a viable means for the causal analysis of behavior in the primate model.

‣ Isoglitter

Michael J. Bucknum; Eduardo A. Castro; Bin Wen
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Described herein is a novel crystalline pattern in space group Ammm, that is a model of a C allotrope. This so-called isoglitter structure-type is a model of a graphite-diamond hybrid. A DFT geometry optimization and band structure calculation indicates that the lattice is metallic in a C realization.

‣ Determination of linkage disequilibrium region suggests association of the ancient haplotype, hX with neural function

Makoto Shimada; Tsutomu Kanasashi
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Modern human populations are known to contain "ancient haplotypes" that originated from archaic humans by hybridization. Some of them had been reported before the development of human genomic diversity databases, such as HapMap. Consequently, some of them have no information about linkage disequilibrium (LD) regions. Because genetic information within LD is tightly linked, to know LD region containing ancient haplotypes will be useful to estimate basic parameters of admixture events, and to infer biological functions that linked with the ancient haplotypes. One of these ancient haplotypes, haplotype X (_hX_) was found in a 10.1 kb-region located on Xp11.22, which diverged at 1.4 M years ago, with low diversity within the cluster in gene genealogy and worldwide distribution in low frequency. We determined the LD region around the ancient haplotypes using LD information obtained in the HapMap project. The LD determination presents that the LD region surrounding the _hX_ is stable and contains genic regions that may associate with neural and brain functions.

‣ Post-meiotic apozygotic combinatory process in sugar beet (Beta vulgaris L.)

Evgenii Levites; Svetlana Kirikovich
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
The effect of colchicine on phenotypic classes ratio of the enzyme locus controlling alcohol dehydrogenase (ADH1) in sugar beet agamospermous progenies was analyzed. The obtained data are indicative of the thing that colchicine causes polytenization of homological chromosome regions carrying marker locus Adh1 alleles. Theoretical calculation of the formation of egg cell frequencies and those of further development of cells entering embryogenesis without fertilization, also the diminution calculation of excessive chromosome regions carrying marker locus alleles have been made. The coincidence of theoretical and experimental ratios of phenotypic classes indicates the existence of a post-meiotic apozygotic combinatory process in plants.

‣ Integrative concept of homeostasis: translating physiology into medicine

Ivan Spasojevic
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
To truly understand living systems they must be viewed as a whole. In order to achieve this and to come to some law to which living systems obey, data obtained on cells, tissues and organs should be integrated. Because there are no such laws yet, there is usually a long path for physiological findings obtained by reductionist approaches to be translated into medical practice. The concept and accompanying equations of homeostasis presented here are aimed to develop biological laws and to bridge this gap between physiology and medicine. The concept of homeostasis takes into account energy input and output, enlisting all relevant contributors. In homeostasis, input should equal the output. What I suggest here is that if the system is out of homeostasis, the homeostasis may be regained by changing any of the input or output components in an adequate manner, not only the one that has changed first. The proposed equation should enable for new lab findings regarding any pathophysiological conditions to find a more direct use in medicine. It should also ease ‘decision making’ in medicine and make therapy development and treatment outcome more straightforward and predictable. Finally, to recognize the basic laws of living systems enables for evolutionary adaptations and processes to be understood better.

‣ Ajuvant effect of a Synthetic Aluminium - Magnesium Silicate on chloroquine phosphate, against Plasmodium berghei.

madike ezeibe; obianuju obianuju Okoroafor; nnenna elendu-eleke; Augustine Ngene
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Abstract effect of a synthetic Aluminium - Magnesium Silicate (AMS) on antiplasmodial activity of chloroquine was tested. Plasmodium berghei-infected mice were treated with 7 mg/kg, 5 mg/kg and 3 mg/kg chloroquine, respectively. The two subgroups in each experiment were treated with chloroquine alone and with chloroquine in AMS respectively. Parasitaemia (%) of the group treated with 7 mg/kg was higher than that of the control. At 5 mg/kg, chloroquine treatment significantly reduced parasitaemia from 3.60 to 2.46 (P =0.01). Incorporating chloroquine in AMS significantly improved its ability to reduce P. berghei parasitaemia at 5 mgkg and at 3 mg/kg, from 2.46 0.21 to 1.57 0.25 (P = 0.01) and from 3.82 0.06 to 2.12 0.08 (P =0.01 ). It also increased mortality of mice treated at 7 mg/kg from 20 to 80 %.

‣ Calorific values and ash contents of different organs of Masson pine (Pinus massoniana) in southern China

Wei Sheng Zeng; Shou Zheng Tang; Qian Hui Xiao
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Calorific values of plants are important indices for evaluating and reflecting material cycle and energy conversion in forest ecosystems. Based on the data of Masson Pine (Pinus massoniana) in southern China, the calorific values (CVs) and ash contents (ACs) of different plant organs were analyzed systematically using hypothesis test and regression analysis in this paper. The results show: (i) the CVs and ACs of different plant organs are almost significantly different, and the order by AFCV (ash-free calorific value) from the largest to the smallest is foliage (23.55 kJ/g), branches (22.25 kJ/g), stem bark (21.71 kJ/g), root (21.52 kJ/g) and stem wood (21.35 kJ/g); and the order by AC is foliage (2.35%), stem bark (1.44%), root (1.42%), branches (1.08%) and stem wood (0.33%); (ii) the CVs and ACs of stem woods on top, middle and lower sections are significantly different, and the CVs are increasing from top to lower sections of trunk while the ACs are decreasing; (iii) the mean GCV (gross calorific value) and AFCV of aboveground part are larger than those of belowground part (roots), and the differences are also statistically significant; (iv) the CVs and ACs of different organs are related, to some extent, to diameter, height and origin of the tree...