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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‣ Ecological connection between fish preference in the diet of Siberian cranes and their incubation period in tundra zone

Maria Vladimirtseva; Inga Bysykatova; Sergey Sleptsov
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
We researched the ecology of the third rarest crane species, Siberian crane, which breeds in northern-eastern Siberian tundra. Nesting in places near great lakes, this crane appears to be an indicator of the global warming processes that affect lake growth as a result of the permafrost situation close to the surface in tundra. Research has shown that these birds are presumably fish-eating during their incubation period, coinciding with the flooding season when fish come to areas around great lakes. Such a diet may be explained by the necessity of high-energy food during the incubating period as well as the particularity of this species for leaving plant resources around the nest point for the period of the first days after chick hatching. This situation emphasizes tight connections in the vulnerable northern ecosystems. If the water level in tundra lakes starts to be higher due to global warming, all these links may be destroyed.

‣ Reduced glutathione and cysteine hydrochloride on crossbred bull semen

P Perumal
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Over the last few years, good quality freezable semen was not utilized effectively due to less knowledge about the freezability of semen. One reason is the lack of sufficient antioxidants in the seminal plasma and semen extender. The antioxidant content is reduced during the cryopreservation process and causes premature cryo-capacitation and modification of sperm membrane structure upon thawing. So the study of pre-freezing and post thaw seminal parameters like viability, motility, acrosomal integrity, lipid peroxide assay, vanguard distance traveled by sperm, mitochondrial membrane potential, velocity and motility parameters (CASA) and field fertility trial helped to assess the effectiveness of the additives. The conception rate was better in reduced glutathione than the cysteine hydrochloride treated group. The glutathione has improved the poor freezing and maintained the good freezable semen. Thus the field fertility rate was enhanced and in turn helped to prevent waste of good quality germplasm and repeat breeder syndrome in cows.

‣ Identification of transcription regulation associated proteins in plants and stramenopiles

Diego Mauricio Riaño Pachón; Silvia Restrepo; Bernd Mueller-Roeber; Francisco Buitrago Florez
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Conferência ou Objeto de Conferência
Português
The generation of biodiversity is tied to the evolution and re-wiring of gene regulatory networks (GRNs). One component of these GRN are transcription factors and other transcriptional regulators. We have devised a pipeline for the identification of TFs and TRs, exploiting the domain architecture of these proteins. Currently we have a set of rules, representing 138 proteins families, that we have applied to the identification of ~20 different plant species and several species of Stramenopiles, where important plant pathogens are found. Results for plant species are available at http://plntfdb.uniandes.edu.co/; we are now developing a newer interface for Stramenopiles.

‣ Seminal Plasma Proteins

P Perumal
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Conferência ou Objeto de Conferência
Português
The ejaculated semen consists of two major components viz. sperm cells (spermatozoa) and the fluid part obtained after centrifugation called seminal plasma. The spermatozoa originate from the semniferous tubule and are suspended in the seminal plasma. The seminal plasma is composed of secretions contributed by the testis, epididymis, seminal vesicles, ampullae, prostate and bulbourethral glands. About 60-80 % of the ejaculated semen of the bull originates from these sources. Seminal plasma is a highly complex biological fluid containing proteins, amino acids, enzymes, fructose and other carbohydrates, lipids, major minerals and trace elements. Seminal plasma proteins partly originates from the blood plasma by exudation through the lumen of the male genital tract and partly are synthesized and secreted by various reproductive organs and are known as seminal plasma specific proteins. Several seminal plasma proteins of blood origin viz. prealbumin, albumin, globulin, transferring, α-antitrypsin, β-lipoprotein, β-glycoprotein, orsomucoid, kininogen, Peptide hormones, IgG, IgA and IgM have been identified and characterized. These proteins are involved in regulation of osmotic pressure and pH of seminal plasma, transport of ions...

‣ Identification of transcription factor genes and their correlation with the high diversity of Stramenopiles

Francisco Buitrago; Silvia Restrepo; Diego Riaño-Pachón
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
In this study we identify, and classify into families, transcription factors (TFs) and other transcriptional regulators (TRs) in genome sequences available from the Stramenopile group. For this we exploit the presence of protein domains and their combinations to build rules in the form of boolean rules, that are specific for each family of TFs and TRs. We found a correlation between the family size and some traits that has been described to be involved in the complexity of organisms. Furthermore, we found specific gains, losses and families that shows higher abundance in different lineages, which may be involved in the regulation of specific traits for some Stramenopile species.

‣ Effect of 2-H and 18-O water isotopes in kinesin-1 gliding assay

Andy Maloney; Lawrence J. Herskowitz; Steven J. Koch
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
We show here the effects of heavy-hydrogen water (^2^H~2~O) and heavy-oxygen water (H~2~^18^O) on the gliding speed of microtubules on kinesin-1 coated surfaces. Increased fractions of isotopic waters used in the motility solution decreased the gliding speed of microtubules by a maximum of 21% for heavy-hydrogen and 5% for heavy-oxygen water. We discuss possible interpretations of these results and the importance for future studies of water effects on kinesin and microtubules. We also discuss the implication for biomolecular devices incorporating molecular motors.

‣ Recombination modulates how selection affects linked sites in Drosophila

Suzanne E. McGaugh; Caiti S. Smukowski; Brenda Manzano-Winkler; Tiffany L. Himmel; Mohamed A. F. Noor
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
One of the most influential observations in molecular evolution has been a strong association between regional recombination rate and amount of nucleotide polymorphism in those genomic regions, interpreted as evidence for ubiquitous natural selection. The alternative explanation, that recombination is mutagenic, has been rejected by the absence of a similar association between regional recombination rate and nucleotide divergence between species. However, many recent studies show that recombination rates are often very different even in closely related species, questioning whether an association between recombination rate and divergence between species has been tested satisfactorily. To circumvent this problem, we directly surveyed recombination across approximately 43% of the D. pseudoobscura physical genome in two separate recombination maps, and 31.3% of the D. miranda physical genome, and we identified both global and local differences in recombination rate between these two closely related species. Using only regions with conserved recombination rates between and within species and accounting for multiple covariates, our data support the conclusion that recombination is positively related to diversity because recombination modulates hitchhiking in the genome. Finally...

‣ Effect Of Pre-freeze Addition Of Cysteine Hydrochloride And Reduced Glutathione On Post-thaw Sperm Parameters And Field Fertility In Jersey Crossbred Bull Semen

P Perumal; S Selvaraju; A.K. Barik; D. N. Mohanty; Srinibas Das; P.C. Mishra
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Conferência ou Objeto de Conferência
Português
The present study was aimed to assess the effect of pre-freeze addition of cysteine hydrochloride and glutathione (GSH) on post-thaw sperm functional parameters and field fertility. The experimental bulls aged 4 to 6 years were used for the present study. A total of 36 ejaculates, 6 ejaculates from each bull (n=6) were collected and divided in to three groups, group I (control), group II (5mM cysteine hydrochloride) and group III (5mM GSH). The extended semen samples were added with @5mM additives, filled in mini straw using automatic filling and sealing machine (IMV, France) and cryopreserved in liquid nitrogen. Post-freeze seminal traits were also recorded after thawing at 37oC for 30 seconds. Post thaw livability was significantly (p< 0.01) higher in GSH group as compared to cysteine and control groups. The loss of acrosomal integrity was significantly (p< 0.01) lower in GSH group than cysteine and control groups. Analysis of variance for post thaw motility parameters (Forward progressive and Total motility) has revealed that significant difference (p< 0.05) between the good and poor freezer in the group II and there was no difference in the group I and III under study at 0 and 1 hr incubation period and at 2 hrs the group III and at 4 hrs group I has revealed significance difference (p< 0.05).The curvilinear velocity (VCL) and amplitude of lateral head displacement (ALH) values were significantly (P<0.05) higher in GSH than the cysteine and control groups. The Mitochondrial membrane potential (per cent) had no significance difference between the treatment groups. The present study indicates that the addition of cysteine and GSH suggestive of reducing lipid peroxide levels. The conception rate (%) in glutathione (68) added semen was significantly (p>0.05) higher than cysteine (58) and control (49) groups. The post-thaw sperm progressive forward motility (r=0.4) had moderate but...

‣ Integration of the scientific literature into the Semantic Web: Facts from biomedical data resources

Dietrich Rebholz; Samuel Croset; Christoph Grabmueller
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Conferência ou Objeto de Conferência
Português
Scientific literature is the primary resource for relevant and innovative information. The integration of the literature with other data resources in the biomedical research community generates overhead that can be avoided through the used of Semantic Web Technology generating openly accessible data. Projects such as SESL and CALBC have producted significant amount of data that that are ready for exploitation. The tutorial will teach different approaches on how to integrate the scientific literature with the content from biomedical databases, and will discuss the inferences that can be achieved. Furthermore, the tutorial will point to the resources that are ready for use and enable integration of the literature at your discretion. A good understanding of Semantic Web technology, ontologies, OWL and the existing biomedical data resources is advantageous to easily follow the tutorial.

‣ The computational magic of the ventral stream

Tomaso Poggio
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
I argue that the sample complexity of (biological, feedforward) object recognition is mostly due to geometric image transformations and conjecture that a main goal of the ventral stream – V1, V2, V4 and IT – is to learn-and-discount image transformations. In the first part of the paper I describe a class of simple and biologically plausible memory-based modules that learn transformations from unsupervised visual experience. The main theorems show that these modules provide (for every object) a signature which is invariant to local affine transformations and approximately invariant for other transformations. I also prove that, in a broad class of hierarchical architectures, signatures remain invariant from layer to layer. The identification of these memory-based modules with complex (and simple) cells in visual areas leads to a theory of invariant recognition for the ventral stream. In the second part, I outline a theory about hierarchical architectures that can learn invariance to transformations. I show that the memory complexity of learning affine transformations is drastically reduced in a hierarchical architecture that factorizes transformations in terms of the subgroup of translations and the subgroups of rotations and scalings. I then show how translations are automatically selected as the only learnable transformations during development by enforcing small apertures – eg small receptive fields – in the first layer. In a third part I show that the transformations represented in each area can be optimized in terms of storage and robustness...

‣ Biodegradable Luminescent Silicon Quantum Dots for Two Photon Imaging Applications

Chen-An Tien; Folarin Erogbogbo; Ching-Wen Chang; Priscilla Adjei-Baffour; Wing-Chueng Law; Mark T. Swihart
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Cadmium- and lead-based quantum dots are normally coated for biological applications, because their degradation may result in the release of toxic heavy metal ions. Here, we synthesize silicon quantum dots that are expected to biodegrade to non-toxic products. A chitosan coating is used to render the silicon quantum dots stable in storage conditions and biodegradable at physiological conditions. The applications of these particles are demonstrated in cellular imaging with single and two-photon excitation. These results open the door for a new generation of silicon quantum dots that may have a wide variety of applications derived from the flexibility of chitosan.

‣ Management and provision of computational models

Camille Laibe
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Conferência ou Objeto de Conferência
Português
Quantitative models of biological systems provide an understanding of chemical and biological phenomena based on their underlying mechanisms. Moreover, they can be used for example, to predict the behaviour of a system under given conditions or direct future experiments. This has made quantitative models the perfect tools to answer a variety of questions in the biological sciences and has lead to a steady growth of the number of published models. To maximise the benefits of this growing body of models, the field needs centralised model repositories that will encourage, facilitate and promote model dissemination and reuse. BioModels Database(http://www.ebi.ac.uk/biomodels/) has been developed to exactly fulfil those needs. In order to ensure the correctness of the models distributed, their structure and behaviour are thoroughly checked. To ease their understanding, the model elements are annotated with terms from controlled vocabularies as well as linked to relevant data resources. Finally, to allow their reuse, the models are provided encoded in community supported and standardised formats. However, the modelling field is constantly evolving and data providers, like BioModels Database, are faced with new challenges. For example...

‣ Inferring decoding strategy from choice probabilities in the presence of noise correlations

Ralf M. Haefner; Sebastian Gerwinn; Jakob H. Macke; Matthias Bethge
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
The activity of cortical neurons in sensory areas covaries with perceptual decisions, a relationship often quantified by choice probabilities. While choice probabilities have been measured extensively, their interpretation has remained fraught with difficulty. Here, we derive the mathematical relationship between choice probabilities, read-out weights and noise correlations within the standard neural decision making model. Our solution allows us to prove and generalize earlier observations based on numerical simulations, and to derive novel predictions. Importantly, we show how the read-out weight profile, or decoding strategy, can be inferred from experimentally measurable quantities. Furthermore, we present a test to decide whether the decoding weights of individual neurons are optimal, even without knowing the underlying noise correlations. We confirm the practical feasibility of our approach using simulated data from a realistic population model. Our work thus provides the theoretical foundation for a growing body of experimental results on choice probabilities and correlations.

‣ A novel predicted calcium-regulated kinase family implicated in neurological disorders

Małgorzata Dudkiewicz; Anna Lenart; Krzysztof Pawłowski
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Protein kinases are essential effectors of cellular signaling. Surprisingly, using bioinformatics tools, we predicted protein kinase structure and function for proteins of unknown function (FAM69 family) coded by five related human genes and their Metazoan homologues. Analysis of three-dimensional structure models and conservation of the classic catalytic motifs of protein kinases in four of human FAM69 proteins suggests they might have retained catalytic phosphotransferase activity. The FAM69 genes, FAM69A, FAM69B, FAM69C, C3ORF58 and CXORF36, are by large uncharacterized molecularly, yet linked to several neurological disorders in genetics studies. An EF-hand Ca2+-binding domain in FAM69A and FAM69B proteins, inserted within the structure of the kinase domain, suggests they function as Ca2+-dependent kinases.

‣ Structural Analysis of Outer Membrane Beta-stranded Porins using Temperature Factor

Abhishek Kumar
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Computational and statistical analysis has formed a large component of the biophysical efforts put forth to understand protein structure and function, due to the diversity and complexity of their structure. Outer membrane proteins form a diverse and complex set of proteins. Of these, porins which allow passage of molecules across the membrane interface have been analyzed here from a biophysical and structural perspective. The objective of this study is to analyze the structural organization of porins using atomic temperature factor as a parameter. Generally atomic temperature factors of molecules from crystal structures indicate the degree of mobility or disorder seen in the crystal structure. As good crystal structures have fewer possibilities of errors so there is less chance that errors are playing roles in temperature factors. Structures of six porins (four 16 stranded beta barrel porins and two 8 stranded beta barrel porins) were taken from the PDB for the analysis based on resolution and R-factor. Programs and scripts were written for extracting the temperature factors for the beta strands, loops and turns so that the analysis could be done for different atom-types and residue-types. The residue distribution and mobility distribution was found to be characteristic of each of the porins. The mobility and residue distribution amongst the secondary structural elements were found to follow the level of homology at the sequence and structural level. The loops that had defined functional roles in structural terms were found to have lower temperature factors than the other loops. The turn regions that are thought to face the periplasmic region in the cell...

‣ Can bacteria adapt to starvation-free environment?

Kei Kitahara
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Bacteria will experience starvation-free environment if infinite nutrition is supplied continuously for a long period. In this study, an evolutionary experiment was performed for 118 days where bacteria adapted to starvation-free environment and reduced their doubling time. It is anticipated that this finding will help to select bacterial strains that can grow more rapidly in rich media.

‣ A new outlook towards kidney injuries

Mahesh Satwekar; Abhijeet Satwekar
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Acute and chronic progression of injury to the kidney leads to the failure of the renal system and has become an increasingly important cause of morbidity and mortality. Present diagnosis detects the condition only after irreversible loss of 70 percent of kidney function. Current research is focused only on the clinical manifestations after the kidney injuries and not towards the exact cause of the condition. Here we propose a new outlook- that there is an involvement of a pathogen in the pathogenesis of kidney injuries. Basis for our proposal is given by the similarity of the pathogenesis events occurring between a classical example of hepatitis and kidney injuries. Furthermore, literature regarding the role of early kidney injury biomarkers in innate immunity indicates the involvement of the pathogen. Research in this theme possesses a strong possibility in the development of therapeutic, preventive and management strategies for the acute and chronic kidney injuries.

‣ AGMAAS: a GIS integrated tool for modelling wind-borne spreading of FMD virus

Judit Sábitz; Zoltán Barcza Solymosi; Norbert Solymosi
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
The aim of our work was to develop a tool integrated into Quantum GIS (QGIS) that can help the user estimate and visualize the possible infective areas around an outbreak based on HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model.

‣ Aetiology and treatment of epidermal depigmentory disorder in humans

S. S. Sawhney
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
The epidermal depigmentary trigger in humans at post-natal level may occur with the toxification of skin organ with the endogenously produced melanocytotoxic hydrogen peroxide and subsequent formation of hydrogen peroxide- melanolipoprotein conjugate involving the hydrogen bonding of complementary hydroxyl and carbonyl molecular surfaces of these biosignitures respectively. The condition is multifactorial but reversible. The structural and functional degeneration of melanocytes under the acquired condition never occur. The molecular conjugation theory on the aetiology and line of treatment of the epidermal depigmentary disorder (recoined as hepato-epidermal syndrome HES) has been proposed. The inherent sulfoxides of Allium cepa have been found as the renaturant of HES condition with the capacity to dislodge the denaturant hydrogen peroxide forming stronger hydrogen bonding with hydrogen peroxide than that of carbonyl molecular surface of melanolipoprotein, the epidermal colour determinant. The orally and topically defined plant based combined therapy advances the recovery time of HES condition.

‣ Codonopsis pilosula twines either to the left or to the right

Gonghua Lin; Fang Zhao; Eviatar Nevo; Tongzuo Zhang; Jianping Su
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
We report the twining handedness of Codonopsis pilosula, which has either a left- or right-handed helix among different plants, among different tillers within a single plant, and among different branches within a single tiller. The handedness was randomly distributed among different plants, among the tillers within the same plants, but not among the branches within the same tillers. Moreover, the handedness of the stems can be strongly influenced by external forces, i.e. the compulsory left and right forming inclined to produce more left- and right-handed twining stems, respectively, and the reversing could make a left-handed stem to be right-handed and vice versa. We also discuss the probable mechanisms these curious cases happen.