1,138 research outputs found

    Reduced glutamine synthetase activity alters the fecundity of female Bactrocera dorsalis (Hendel)

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    Glutamine synthetase (GS) is a key enzyme in glutamine synthesis and is associated with multiple physiological processes in insects, such as embryonic development, heat shock response, and fecundity regulation. However, little is known about the influence of GS on female fecundity in the oriental fruit fly, Bactrocera dorsalis. Based on the cloning of BdGSs, mitochondrial BdGSm and cytoplasmic BdGSc, we determined their expressions in the tissues of adult B. dorsalis. BdGSm was highly expressed in the fat body, while BdGSc was highly expressed in the head and midgut. Gene silencing by RNA interference against two BdGSs isoforms suppressed target gene expression at the transcriptional level, leading to a reduced ovarian size and lower egg production. The specific inhibitor L-methionine S-sulfoximine suppressed enzyme activity, but only the gene expression of BdGSm was suppressed. A similar phenotype of delayed ovarian development occurred in the inhibitor bioassay. Significantly lower expression of vitellogenin and vitellogenin receptor was observed when GS enzyme activity was suppressed. These data illustrate the effects of two GS genes on adult fecundity by regulating vitellogenin synthesis in different ways

    FiGS: a filter-based gene selection workbench for microarray data

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    <p>Abstract</p> <p>Background</p> <p>The selection of genes that discriminate disease classes from microarray data is widely used for the identification of diagnostic biomarkers. Although various gene selection methods are currently available and some of them have shown excellent performance, no single method can retain the best performance for all types of microarray datasets. It is desirable to use a comparative approach to find the best gene selection result after rigorous test of different methodological strategies for a given microarray dataset.</p> <p>Results</p> <p>FiGS is a web-based workbench that automatically compares various gene selection procedures and provides the optimal gene selection result for an input microarray dataset. FiGS builds up diverse gene selection procedures by aligning different feature selection techniques and classifiers. In addition to the highly reputed techniques, FiGS diversifies the gene selection procedures by incorporating gene clustering options in the feature selection step and different data pre-processing options in classifier training step. All candidate gene selection procedures are evaluated by the .632+ bootstrap errors and listed with their classification accuracies and selected gene sets. FiGS runs on parallelized computing nodes that capacitate heavy computations. FiGS is freely accessible at <url>http://gexp.kaist.ac.kr/figs</url>.</p> <p>Conclusion</p> <p>FiGS is an web-based application that automates an extensive search for the optimized gene selection analysis for a microarray dataset in a parallel computing environment. FiGS will provide both an efficient and comprehensive means of acquiring optimal gene sets that discriminate disease states from microarray datasets.</p

    Cis-regulatory control of the nodal gene, initiator of the sea urchin oral ectoderm gene network

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    Expression of the nodal gene initiates the gene regulatory network which establishes the transcriptional specification of the oral ectoderm in the sea urchin embryo. This gene encodes a TGFβ ligand, and in Strongylocentrotus purpuratus its transcription is activated in the presumptive oral ectoderm at about the 30-cell stage. Thereafter Nodal signaling occurs among all cells of the oral ectoderm territory, and nodal expression is required for expression of oral ectoderm regulatory genes. The cis-regulatory system of the nodal gene transduces anisotropically distributed cytoplasmic cues that distinguish the future oral and aboral domains of the early embryo. Here we establish the genomic basis for the initiation and maintenance of nodal gene expression in the oral ectoderm. Functional cis-regulatory control modules of the nodal gene were identified by interspecific sequence conservation. A 5′ cis-regulatory module functions both to initiate expression of the nodal gene and to maintain its expression by means of feedback input from the Nodal signal transduction system. These functions are mediated respectively by target sites for bZIP transcription factors, and by SMAD target sites. At least one SMAD site is also needed for the initiation of expression. An intron module also contains SMAD sites which respond to Nodal feedback, and in addition acts to repress vegetal expression. These observations explain the main features of nodal expression in the oral ectoderm: since the activity of bZIP factors is redox sensitive, and the initial polarization of oral vs. aboral fate is manifested in a redox differential, the bZIP sites account for the activation of nodal on the oral side; and since the immediate early signal transduction response factors for Nodal are SMAD factors, the SMAD sites account for the feedback maintenance of nodal gene expression

    Bis{2-eth­oxy-6-[2-(isopropyl­ammonio)ethyl­imino­meth­yl]phenolato}dithio­cyanato­nickel(II)

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    In the mononuclear title complex, [Ni(NCS)2(C14H22N2O2)2], the Ni atom lies on an inversion centre. It is chelated by the phenolate O and imine N atoms from two zwitterionic Schiff base ligands, and is also coordinated by the N atoms from two thio­cyanate ligands, giving a slightly distorted octa­hedral geometry. Intra­molecular N—H⋯O and N—H⋯N hydrogen bonds are observed

    Ukupna kinetika redukcije niskokvalitetnog piroluzita smjesom hemiceluloze i lignina kao redukcijskog sredstva

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    Manganese is widely used in many fields. Many efforts have been made to recover manganese from low-grade pyrolusite due to the depletion of high-grade manganese ore. Thus, it is of practical significance to develop a clean, energy-saving and environmentally friendly technical route to reduce the low-grade pyrolusite. The reported results show that biomass wastes from crops, crop waste, wood and wood waste are environmentally friendly, energy-saving, and low-cost reducing agents for roasting reduction of low-grade pyrolusite. Kinetics of the reduction reactions is necessary for an efficient design of biomass reduction of pyrolusite. Therefore, it is important to look for a general kinetics equation to describe the reduction of pyrolusite by different kinds of biomass, because there is a wide variety of biomass wastes, meaning that it is impossible to investigate the kinetics for each biomass waste. In this paper, thermal gravimetric analysis and differential thermal analysis were applied to study the overall reduction kinetics of pyrolusite using a mixture of hemicellulose and lignin, two major components of biomass. Overall reduction process is the overlap of the respective reduction processes. A new empirical equation based on the Johnson–Mehl–Avrami equation can be used to describe the respective reduction kinetics using hemicellulose and lignin as reductants, and the corresponding apparent activation energy is 30.14 kJ mol−1 and 38.91 kJ mol−1, respectively. The overall kinetic model for the reduction of pyrolusite by the mixture of hemicellulose and lignin can be simulated by the summation of the respective kinetics by considering their mass-loss fractions, while a unit step function was used to avoid the invalid conversion data. The obtained results in this work are necessary to understand the biomass reduction of pyrolusite and provide valuable assistance in the development of a general kinetics equation.Ukupna kinetika redukcije piroluzita istraživana je termogravimetrijom i diferencijalnom termogravimetrijom. Kao redukcijsko sredstvo upotrijebljeni su hemiceluloza i lignin, glavni sastojci poljoprivrednog biljnog biootpada, drva i drvnog otpada. Ukupnu redukciju čine isprepleteni pojedinačni redukcijski procesi. Kinetika redukcije piroluzita smjesom hemiceluloze i lignina može se opisati novom empirijskom jednadžbom temeljenoj na jednadžbi Johnson–Mehl–Avrami, a odgovarajuća prividna energija aktivacije iznosi 30.14 kJ mol−1, odnosno 38.91 kJ mol−1. Sveobuhvatna kinetika može se modelirati kao zbroj pojedinačnih udjela uzimajući u obzir masene udjele sastojaka smjese te uz primjenu jedinične odskočne funkcije kako bi se izbjegli nevaljani podaci
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