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Sample records for aneuploid drosophila s2

  1. Chloride channels in the plasma membrane of a foetal Drosophila cell line, S2

    DEFF Research Database (Denmark)

    Asmild, Margit; Willumsen, Niels J.

    2000-01-01

    S2 cells, Cl- Channels, Expression system, Drosophila, Inward rectifier, Outward rectifier, Patch clamp......S2 cells, Cl- Channels, Expression system, Drosophila, Inward rectifier, Outward rectifier, Patch clamp...

  2. RNAi in Drosophila S2 cells as a tool for studying cell cycle progression.

    Science.gov (United States)

    Bettencourt-Dias, Mónica; Goshima, Gohta

    2009-01-01

    Genetic studies on model organisms, particularly yeasts and Drosophila melanogaster, have proven powerful in identifying the cell cycle machinery and its regulatory mechanisms. In more recent years RNAi has been used in a variety of genome-wide screens and single molecule studies to elucidate the mechanisms of cell cycle progression. In Drosophila cultured cells, RNAi is extremely simple, and a strong effect can be observed by adding the dsRNA to the cultured cells, with few complications of off-target effects. Functions in cell cycle progression can be followed by a variety of assays. One of the advantages of these cells is that they allow high-resolution spatiotemporal observations to be made by microscopy, with no particular complexity in terms of media and temperature. Here we discuss protocols for RNAi in Drosophila S2 culture cells, followed by the study of mitotic progression, through immunocytochemistry, live imaging, and flow cytometry analysis.

  3. Assembly of homotrimeric type XXI minicollagen by coexpression of prolyl 4-hydroxylase in stably transfected Drosophila melanogaster S2 cells.

    Science.gov (United States)

    Li, Hsiu-Chuan; Huang, Chuan-Chuan; Chen, Sung-Fang; Chou, Min-Yuan

    2005-10-21

    We established stably transfected insect cell lines containing cDNAs encoding the alpha and beta subunits of human prolyl 4-hydroxylase in both Trichoplusia ni and Drosophila melanogaster S2 cells. The expression level and enzymatic activity of recombinant prolyl 4-hydroxylase produced in the Drosophila expression system were significantly higher than those produced in the T. ni system. We further characterized the involvement of prolyl 4-hydroxylase in the assembly of the three alpha chains to form trimeric type XXI minicollagen, which comprises the intact C-terminal non-collagenous (NC1) and collagenous domain (COL1), in the Drosophila system. When minicollagen XXI was stably expressed in Drosophila S2 cells alone, negligible amounts of interchain disulfide-bonded trimers were detected in the culture media. However, minicollagen XXI was secreted as disulfide-bonded homotrimers by coexpression with prolyl 4-hydroxylase in the stably transfected Drosophila S2 cells. Minicollagen XXI coexpressed with prolyl 4-hydroxylase contained sufficient amounts of hydroxyproline to form thermal stable pepsin-resistant triple helices consisting of both interchain and non-interchain disulfide-bonded trimers. These results demonstrate that a sufficient amount of active prolyl 4-hydroxylase is required for the assembly of type XXI collagen triple helices in Drosophila cells and the trimeric assembly is governed by the C-terminal collagenous domain.

  4. Expression and purification of sea raven type II antifreeze protein from Drosophila melanogaster S2 cells.

    Science.gov (United States)

    Scotter, Andrew J; Kuntz, Douglas A; Saul, Michelle; Graham, Laurie A; Davies, Peter L; Rose, David R

    2006-06-01

    We present a system for the expression and purification of recombinant sea raven type II antifreeze protein, a cysteine-rich, C-type lectin-like globular protein that has proved to be a difficult target for recombinant expression and purification. The cDNAs encoding the pro- and mature forms of the sea raven protein were cloned into a modified pMT Drosophila expression vector. These constructs produced N-terminally His(6)-tagged pro- and mature forms of the type II antifreeze protein under the control of a metallothionein promoter when transfected into Drosophila melanogaster S2 cells. Upon induction of stable cell lines the two proteins were expressed at high levels and secreted into the medium. The proteins were then purified from the cell medium in a simple and rapid protocol using immobilized metal affinity chromatography and specific protease cleavage by tobacco etch virus protease. The proteins demonstrated antifreeze activity indistinguishable from that of wild-type sea raven antifreeze protein purified from serum as illustrated by ice affinity purification, ice crystal morphology, and their ability to inhibit ice crystal growth. This expression and purification system gave yields of 95 mg/L of fully active mature sea raven type II AFP and 9.6 mg/L of the proprotein. This surpasses all previous attempts to express this protein in Escherichia coli, baculovirus-infected fall armyworm cells and Pichia pastoris and will provide sufficient protein for structural analysis.

  5. Protease domain of human ADAM33 produced by Drosophila S2 cells.

    Science.gov (United States)

    Prosise, Winifred W; Yarosh-Tomaine, Taisa; Lozewski, Zia; Ingram, Richard N; Zou, Jun; Liu, Jian-Jun; Zhu, Feng; Taremi, S Shane; Le, Hung V; Wang, Wenyan

    2004-12-01

    Human ADAM33 is a multiple-domain, type-I transmembrane zinc metalloprotease recently implicated in asthma susceptibility [Nature 418 (2002) 426]. To provide an active protease for functional studies, expression of a recombinant ADAM33 zymogen (pro-catalytic domains, pro-CAT) was attempted in several insect cells. The pro-CAT was cloned into baculovirus under the regulation of the polyhedron promoter and using either the honeybee mellitin or ADAM33 signal sequence. Sf9 or Hi5 cells infected with these recombinant viruses expressed the majority of the protein unprocessed and as inclusion bodies ( approximately 10 mg/L). On the other hand, similar constructs could be expressed, processed, and secreted by Drosophila S2 cells using a variety of constitutive (actin, pAc5.1) or inducible (metallothionein, PMT) promoters and leader sequences (e.g., native and BiP). Higher expression level of 10-fold was observed for the inducible system resulting in an average yield of 20 mg/L after purification. The majority of the catalytic domain purified from the Drosophila conditioned media remained associated with the pro-domain after several chromatography steps. An induction cocktail containing cadmium chloride and zinc chloride was subsequently developed for the PMT system as an alternative to using cupric sulfate or cadmium chloride as single inducers. The novel induction cocktail resulted in an increased ratio of secreted catalytic to pro-domain, and yielded milligram amounts of highly purified protease. The availability of this modified expression system facilitated purification of the wild type and several glycosylation mutants, one of which (N231Q) crystallized recently for X-ray structure determination [J. Mol. Biol. 335 (2003) 129].

  6. Mechanical coupling of microtubule-dependent motor teams during peroxisome transport in Drosophila S2 cells.

    Science.gov (United States)

    De Rossi, María Cecilia; Wetzler, Diana E; Benseñor, Lorena; De Rossi, María Emilia; Sued, Mariela; Rodríguez, Daniela; Gelfand, Vladimir; Bruno, Luciana; Levi, Valeria

    2017-12-01

    Intracellular transport requires molecular motors that step along cytoskeletal filaments actively dragging cargoes through the crowded cytoplasm. Here, we explore the interplay of the opposed polarity motors kinesin-1 and cytoplasmic dynein during peroxisome transport along microtubules in Drosophila S2 cells. We used single particle tracking with nanometer accuracy and millisecond time resolution to extract quantitative information on the bidirectional motion of organelles. The transport performance was studied in cells expressing a slow chimeric plus-end directed motor or the kinesin heavy chain. We also analyzed the influence of peroxisomes membrane fluidity in methyl-β-ciclodextrin treated cells. The experimental data was also confronted with numerical simulations of two well-established tug of war scenarios. The velocity distributions of retrograde and anterograde peroxisomes showed a multimodal pattern suggesting that multiple motor teams drive transport in either direction. The chimeric motors interfered with the performance of anterograde transport and also reduced the speed of the slowest retrograde team. In addition, increasing the fluidity of peroxisomes membrane decreased the speed of the slowest anterograde and retrograde teams. Our results support the existence of a crosstalk between opposed-polarity motor teams. Moreover, the slowest teams seem to mechanically communicate with each other through the membrane to trigger transport. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Legionella pneumophila infection of Drosophila S2 cells induces only minor changes in mitochondrial dynamics.

    Directory of Open Access Journals (Sweden)

    Elizabeth Wen Sun

    Full Text Available During infection of cells by Legionella pneumophila, the bacterium secretes a large number of effector proteins into the host cell cytoplasm, allowing it to alter many cellular processes and make the vacuole and the host cell into more hospitable environments for bacterial replication. One major change induced by infection is the recruitment of ER-derived vesicles to the surface of the vacuole, where they fuse with the vacuole membrane and prevent it from becoming an acidified, degradative compartment. However, the recruitment of mitochondria to the region of the vacuole has also been suggested by ultrastructural studies. In order to test this idea in a controlled and quantitative experimental system, and to lay the groundwork for a genome-wide screen for factors involved in mitochondrial recruitment, we examined the behavior of mitochondria during the early stages of Legionella pneumophila infection of Drosophila S2 cells. We found that the density of mitochondria near vacuoles formed by infection with wild type Legionella was not different from that found in dotA(- mutant-infected cells during the first 4 hours after infection. We then examined 4 parameters of mitochondrial motility in infected cells: velocity of movement, duty cycle of movement, directional persistence and net direction. In the 4 hours following infection, most of these measures were indistinguishable between wild type and dotA(-.infection. However, wild type Legionella did induce a modest shift in the velocity distribution toward faster movement compared dotA(- infection, and a small downward shift in the duty cycle distribution. In addition, wild type infection produced mitochondrial movement that was biased in the direction of the bacterial vacuole relative to dotA-, although not enough to cause a significant accumulation within 10 um of the vacuole. We conclude that in this host cell, mitochondria are not strongly recruited to the vacuole, nor is their motility

  8. Transport of polyamines in Drosophila S2 cells: kinetics, pharmacology and dependence on the plasma membrane proton gradient.

    Science.gov (United States)

    Romero-Calderón, Rafael; Krantz, David E

    2006-01-15

    Polyamine transport activities have been described in diverse multicellular systems, but their bioenergetic mechanisms and molecular identity remain unclear. In the present paper, we describe a high-affinity spermine/spermidine transport activity expressed in Drosophila S2 cells. Ion-replacement experiments indicate that polyamine uptake across the cell membrane is Na+-, K+-, Cl-- and Ca2+-independent, but pH-sensitive. Additional experiments using ionophores suggest that polyamine uptake may be H+-coupled. Pharmacological experiments show that polyamine uptake in S2 cells is selectively blocked by MGBG {methylglyoxal bis(guanylhydrazone) or 1,1'-[(methylethanediylidine)-dinitrilo]diguanidine} and paraquat (N,N-dimethyl-4,4'-bipyridylium), two known inhibitors of polyamine uptake in mammalian cells. In addition, inhibitors known to block the Slc22 (solute carrier 22) family of organic anion/cation transporters inhibit spermine uptake in S2 cells. These data and the genetic tools available in Drosophila will facilitate the molecular identification and further characterization of this activity.

  9. Aneuploid polyclonality in image analysis.

    Science.gov (United States)

    Alderisio, M; Ribotta, G; Giarnieri, E; Midulla, C; Ferranti, S; Narilli, P; Nofroni, I; Vecchione, A

    1996-05-01

    Solid tumors such as colorectal adenocarcinomas consist of biologically diverse cell subpopulations. Nuclear DNA content of tumor cells in colorectal carcinomas may be studied with different techniques of intranuclear DNA quantification. In the current study, the DNA ploidy of samples obtained from 68 patients with colorectal carcinoma (age ranging from 46 to 86 years, mean age 66 years), treated with radical surgery, between the years 1992 and 1995 was analyzed. DNA ploidy was assessed using a CAS 200 image analyzer and was evaluated on neoplastic tissue and undamaged healthy mucosa obtained from the edges of the surgical resection. Approximately 150-300 cells were analyzed for each sample. The aim of this study was to evaluate the prognostic significance of the polyclonal cases correlated with lymph node infiltration and disease free-survival. The pathological stage according to the TNM classification was compared to ploidy: an increase in multiple stemlines was observed in stage III cases, i.e., a progression towards aneuploidy and multiple stemlines was significantly associated with lymphatic metastasis (p<0.0003). Concerning distant metastasis, we found a correlation between stage IV and polyclonality. A significant correlation was observed between disease-free survival and aneuploid and polyclonal cases (p<0.0053). In polyclonal cases a nine fold greater relapse risk compared to the non-polyclonal cases was observed (p<0.0004). In two cases, the adeno-carcinoma of the sigma was polyclonal and its hepatic metastasis contained the predominant aneuploid clone with the same cytometric characteristics (DNA index) of the original lesion.

  10. A Genome-wide RNAi Screen for Microtubule Bundle Formation and Lysosome Motility Regulation in Drosophila S2 Cells

    Directory of Open Access Journals (Sweden)

    Amber L. Jolly

    2016-01-01

    Full Text Available Long-distance intracellular transport of organelles, mRNA, and proteins (“cargo” occurs along the microtubule cytoskeleton by the action of kinesin and dynein motor proteins, but the vast network of factors involved in regulating intracellular cargo transport are still unknown. We capitalize on the Drosophila melanogaster S2 model cell system to monitor lysosome transport along microtubule bundles, which require enzymatically active kinesin-1 motor protein for their formation. We use an automated tracking program and a naive Bayesian classifier for the multivariate motility data to analyze 15,683 gene phenotypes and find 98 proteins involved in regulating lysosome motility along microtubules and 48 involved in the formation of microtubule filled processes in S2 cells. We identify innate immunity genes, ion channels, and signaling proteins having a role in lysosome motility regulation and find an unexpected relationship between the dynein motor, Rab7a, and lysosome motility regulation.

  11. Expression and purification of biologically active recombinant human paraoxonase 1 from a Drosophila S2 stable cell line.

    Science.gov (United States)

    Yun, Hyeongseok; Yu, Jiyeon; Kim, Sumi; Lee, Nari; Lee, Jinhee; Lee, Sungrae; Kim, Nam Doo; Yu, Chiho; Rho, Jaerang

    2017-03-01

    Many pesticides and chemical warfare nerve agents are highly toxic organophosphorus compounds (OPs), which inhibit acetylcholinesterase activity. Human paraoxonase 1 (PON1) has demonstrated significant potential for use as a catalytic bioscavenger capable of hydrolyzing a broad range of OPs. However, there are several limitations to the use of human PON1 as a catalytic bioscavenger, including the relatively difficult purification of PON1 from human plasma and its dependence on the presence of hydrophobic binding partners to maintain stability. Therefore, research efforts to efficiently produce recombinant human PON1 are necessary. In this study, we developed a Drosophila S2 stable cell line expressing recombinant human PON1. The recombinant human PON1 was fused with the human immunoglobulin Fc domain (PON1-hFc) to improve protein stability and purification efficiency. We purified the recombinant human PON1-hFc from the S2 stable cell line and characterized its enzymatic properties for OP hydrolysis. We purified the recombinant human PON1-hFc from the S2 stable cell line and characterized its enzymatic properties for OP hydrolysis compared with those of the recombinant human PON1 derived from E. coli. We observed that the recombinant human PON1-hFc is functionally more stable for OP hydrolyzing activities compared to the recombinant human PON1. The catalytic efficiency of the recombinant PON1-hFc towards diisopropyl fluorophosphate (DFP, 0.26 × 10 6  M -1  min -1 ) and paraoxon hydrolysis (0.015 × 10 6  M -1  min -1 ) was 1.63- and 1.24-fold higher, respectively, than the recombinant human PON1. Thus, we report that the recombinant PON1-hFc exerts hydrolytic activity against paraoxon and DFP. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. 1.8 Å structure of murine GITR ligand dimer expressed in Drosophila melanogaster S2 cells

    International Nuclear Information System (INIS)

    Chattopadhyay, Kausik; Ramagopal, Udupi A.; Nathenson, Stanley G.; Almo, Steven C.

    2009-01-01

    1.8 Å X-ray crystal structure of mouse GITRL expressed in D. melanogaster S2 cells shows an identical ‘strand-exchanged’ dimeric assembly similar to that observed previously for the E. coli-expressed protein. Glucocorticoid-induced TNF receptor ligand (GITRL), a prominent member of the TNF superfamily, activates its receptor on both effector and regulatory T cells to generate critical costimulatory signals that have been implicated in a wide range of T-cell immune functions. The crystal structures of murine and human orthologs of GITRL recombinantly expressed in Escherichia coli have previously been determined. In contrast to all classical TNF structures, including the human GITRL structure, murine GITRL demonstrated a unique ‘strand-exchanged’ dimeric organization. Such a novel assembly behavior indicated a dramatic impact on receptor activation as well as on the signaling mechanism associated with the murine GITRL costimulatory system. In this present work, the 1.8 Å resolution crystal structure of murine GITRL expressed in Drosophila melanogaster S2 cells is reported. The eukaryotic protein-expression system allows transport of the recombinant protein into the extracellular culture medium, thus maximizing the possibility of obtaining correctly folded material devoid of any folding/assembly artifacts that are often suspected with E. coli-expressed proteins. The S2 cell-expressed murine GITRL adopts an identical ‘strand-exchanged’ dimeric structure to that observed for the E. coli-expressed protein, thus conclusively demonstrating the novel quaternary structure assembly behavior of murine GITRL

  13. 1.8 Å structure of murine GITR ligand dimer expressed in Drosophila melanogaster S2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, Kausik [Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461 (United States); Ramagopal, Udupi A. [Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461 (United States); Nathenson, Stanley G., E-mail: nathenso@aecom.yu.edu [Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461 (United States); Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461 (United States); Almo, Steven C., E-mail: nathenso@aecom.yu.edu [Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461 (United States); Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461 (United States); Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461 (United States)

    2009-05-01

    1.8 Å X-ray crystal structure of mouse GITRL expressed in D. melanogaster S2 cells shows an identical ‘strand-exchanged’ dimeric assembly similar to that observed previously for the E. coli-expressed protein. Glucocorticoid-induced TNF receptor ligand (GITRL), a prominent member of the TNF superfamily, activates its receptor on both effector and regulatory T cells to generate critical costimulatory signals that have been implicated in a wide range of T-cell immune functions. The crystal structures of murine and human orthologs of GITRL recombinantly expressed in Escherichia coli have previously been determined. In contrast to all classical TNF structures, including the human GITRL structure, murine GITRL demonstrated a unique ‘strand-exchanged’ dimeric organization. Such a novel assembly behavior indicated a dramatic impact on receptor activation as well as on the signaling mechanism associated with the murine GITRL costimulatory system. In this present work, the 1.8 Å resolution crystal structure of murine GITRL expressed in Drosophila melanogaster S2 cells is reported. The eukaryotic protein-expression system allows transport of the recombinant protein into the extracellular culture medium, thus maximizing the possibility of obtaining correctly folded material devoid of any folding/assembly artifacts that are often suspected with E. coli-expressed proteins. The S2 cell-expressed murine GITRL adopts an identical ‘strand-exchanged’ dimeric structure to that observed for the E. coli-expressed protein, thus conclusively demonstrating the novel quaternary structure assembly behavior of murine GITRL.

  14. Genomic RNAi screening in Drosophila S2 cells: What have we learned about host-pathogen interactions?

    OpenAIRE

    Cherry, Sara

    2008-01-01

    The détente between pathogen and host has been of keen interest to researchers in spite of being exceedingly difficult to probe. Recently, new RNA interference (RNAi) technologies, in particular in Drosophila tissue culture cells, have made it possible to interrogate the genetics of host organisms rapidly, with nearly complete genomic coverage and high fidelity. Therefore, it is not surprising that the applications of RNAi to the study of host-pathogen interactions were amongst the first to b...

  15. A new tagging system for production of recombinant proteins in Drosophila S2 cells using the third domain of the urokinase receptor

    DEFF Research Database (Denmark)

    Gårdsvoll, Henrik; Hansen, Line V; Jørgensen, Thomas J D

    2007-01-01

    The use of protein fusion tag technology greatly facilitates detection, expression and purification of recombinant proteins, and the demands for new and more effective systems are therefore expanding. We have used a soluble truncated form of the third domain of the urokinase receptor...... as a convenient C-terminal fusion partner for various recombinant extracellular human proteins used in basic cancer research. The stability of this cystein-rich domain, which structure adopts a three-finger fold, provides an important asset for its applicability as a fusion tag for expression of recombinant...... proteins. Up to 20mg of intact fusion protein were expressed by stably transfected Drosophila S2 cells per liter of culture using this strategy. Purification of these secreted fusion proteins from the conditioned serum free medium of S2 cells was accompanied by an efficient one-step immunoaffinity...

  16. Drosophila S2 cells are non-permissive for vaccinia virus DNA replication following entry via low pH-dependent endocytosis and early transcription.

    Directory of Open Access Journals (Sweden)

    Zain Bengali

    Full Text Available Vaccinia virus (VACV, a member of the chordopox subfamily of the Poxviridae, abortively infects insect cells. We have investigated VACV infection of Drosophila S2 cells, which are useful for protein expression and genome-wide RNAi screening. Biochemical and electron microscopic analyses indicated that VACV entry into Drosophila S2 cells depended on the VACV multiprotein entry-fusion complex but appeared to occur exclusively by a low pH-dependent endocytic mechanism, in contrast to both neutral and low pH entry pathways used in mammalian cells. Deep RNA sequencing revealed that the entire VACV early transcriptome, comprising 118 open reading frames, was robustly expressed but neither intermediate nor late mRNAs were made. Nor was viral late protein synthesis or inhibition of host protein synthesis detected by pulse-labeling with radioactive amino acids. Some reduction in viral early proteins was noted by Western blotting. Nevertheless, synthesis of the multitude of early proteins needed for intermediate gene expression was demonstrated by transfection of a plasmid containing a reporter gene regulated by an intermediate promoter. In addition, expression of a reporter gene with a late promoter was achieved by cotransfection of intermediate genes encoding the late transcription factors. The requirement for transfection of DNA templates for intermediate and late gene expression indicated a defect in viral genome replication in VACV-infected S2 cells, which was confirmed by direct analysis. Furthermore, VACV-infected S2 cells did not support the replication of a transfected plasmid, which occurs in mammalian cells and is dependent on all known viral replication proteins, indicating a primary restriction of DNA synthesis.

  17. Purification and characterization of recombinant full-length and protease domain of murine MMP-9 expressed in Drosophila S2 cells

    DEFF Research Database (Denmark)

    Rasch, Morten G; Lund, Ida K; Illemann, Martin

    2010-01-01

    Matrix metalloproteinase-9 (MMP-9) is a 92-kDa soluble pro-enzyme implicated in pathological events including cancer invasion. It is therefore an attractive target for therapeutic intervention studies in mouse models. Development of inhibitors requires sufficient amounts of correctly folded murine...... MMP-9. Constructs encoding zymogens of full-length murine MMP-9 and a version lacking the O-glycosylated linker region and hemopexin domains were therefore generated and expressed in stably transfected Drosophila S2 insect cells. After 7 days of induction the expression levels of the full....... No immunoreactivity was observed when the antibody was probed against skin wound material from MMP-9 deficient mice. In conclusion, we have generated and purified two proteolytically active recombinant murine MMP-9 protein constructs, which are critical reagents for future cancer drug discovery studies....

  18. Purification and characterization of recombinant full-length and protease domain of murine MMP-9 expressed in Drosophila S2 cells

    DEFF Research Database (Denmark)

    Rasch, Morten G; Lund, Ida K; Illemann, Martin

    2010-01-01

    MMP-9. Constructs encoding zymogens of full-length murine MMP-9 and a version lacking the O-glycosylated linker region and hemopexin domains were therefore generated and expressed in stably transfected Drosophila S2 insect cells. After 7 days of induction the expression levels of the full......-length and truncated versions were 5 mg/l and 2 mg/l, respectively. The products were >95% pure after gelatin Sepharose chromatography and possessed proteolytic activity when analyzed by gelatin zymography. Using the purified full-length murine MMP-9 we raised polyclonal antibodies by immunizations of rabbits......Matrix metalloproteinase-9 (MMP-9) is a 92-kDa soluble pro-enzyme implicated in pathological events including cancer invasion. It is therefore an attractive target for therapeutic intervention studies in mouse models. Development of inhibitors requires sufficient amounts of correctly folded murine...

  19. Dielectric Spectroscopy and Optical Density Measurement for the Online Monitoring and Control of Recombinant Protein Production in Stably Transformed Drosophila melanogaster S2 Cells

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    Jan Zitzmann

    2018-03-01

    Full Text Available The production of recombinant proteins in bioreactors requires real-time process monitoring and control to increase process efficiency and to meet the requirements for a comprehensive audit trail. The combination of optical near-infrared turbidity sensors and dielectric spectroscopy provides diverse system information because different measurement principles are exploited. We used this combination of techniques to monitor and control the growth and protein production of stably transformed Drosophila melanogaster S2 cells expressing antimicrobial proteins. The in situ monitoring system was suitable in batch, fed-batch and perfusion modes, and was particularly useful for the online determination of cell concentration, specific growth rate (µ and cell viability. These data were used to pinpoint the optimal timing of the key transitional events (induction and harvest during batch and fed-batch cultivation, achieving a total protein yield of ~25 mg at the 1-L scale. During cultivation in perfusion mode, the OD880 signal was used to control the bleed line in order to maintain a constant cell concentration of 5 × 107 cells/mL, thus establishing a turbidostat/permittistat culture. With this setup, a five-fold increase in productivity was achieved and 130 mg of protein was recovered after 2 days of induced perfusion. Our results demonstrate that both sensors are suitable for advanced monitoring and integration into online control strategies.

  20. Human embryonic stem cells as models for aneuploid chromosomal syndromes.

    Science.gov (United States)

    Biancotti, Juan-Carlos; Narwani, Kavita; Buehler, Nicole; Mandefro, Berhan; Golan-Lev, Tamar; Yanuka, Ofra; Clark, Amander; Hill, David; Benvenisty, Nissim; Lavon, Neta

    2010-09-01

    Syndromes caused by chromosomal aneuploidies are widely recognized genetic disorders in humans and often lead to spontaneous miscarriage. Preimplantation genetic screening is used to detect chromosomal aneuploidies in early embryos. Our aim was to derive aneuploid human embryonic stem cell (hESC) lines that may serve as models for human syndromes caused by aneuploidies. We have established 25 hESC lines from blastocysts diagnosed as aneuploid on day 3 of their in vitro development. The hESC lines exhibited morphology and expressed markers typical of hESCs. They demonstrated long-term proliferation capacity and pluripotent differentiation. Karyotype analysis revealed that two-third of the cell lines carry a normal euploid karyotype, while one-third remained aneuploid throughout the derivation, resulting in eight hESC lines carrying either trisomy 13 (Patau syndrome), 16, 17, 21 (Down syndrome), X (Triple X syndrome), or monosomy X (Turner syndrome). On the basis of the level of single nucleotide polymorphism heterozygosity in the aneuploid chromosomes, we determined whether the aneuploidy originated from meiotic or mitotic chromosomal nondisjunction. Gene expression profiles of the trisomic cell lines suggested that all three chromosomes are actively transcribed. Our analysis allowed us to determine which tissues are most affected by the presence of a third copy of either chromosome 13, 16, 17 or 21 and highlighted the effects of trisomies on embryonic development. The results presented here suggest that aneuploid embryos can serve as an alternative source for either normal euploid or aneuploid hESC lines, which represent an invaluable tool to study developmental aspects of chromosomal abnormalities in humans.

  1. Karyotypic Determinants of Chromosome Instability in Aneuploid Budding Yeast

    Science.gov (United States)

    Bradford, William D.; Li, Rong

    2012-01-01

    Recent studies in cancer cells and budding yeast demonstrated that aneuploidy, the state of having abnormal chromosome numbers, correlates with elevated chromosome instability (CIN), i.e. the propensity of gaining and losing chromosomes at a high frequency. Here we have investigated ploidy- and chromosome-specific determinants underlying aneuploidy-induced CIN by observing karyotype dynamics in fully isogenic aneuploid yeast strains with ploidies between 1N and 2N obtained through a random meiotic process. The aneuploid strains exhibited various levels of whole-chromosome instability (i.e. chromosome gains and losses). CIN correlates with cellular ploidy in an unexpected way: cells with a chromosomal content close to the haploid state are significantly more stable than cells displaying an apparent ploidy between 1.5 and 2N. We propose that the capacity for accurate chromosome segregation by the mitotic system does not scale continuously with an increasing number of chromosomes, but may occur via discrete steps each time a full set of chromosomes is added to the genome. On top of such general ploidy-related effect, CIN is also associated with the presence of specific aneuploid chromosomes as well as dosage imbalance between specific chromosome pairs. Our findings potentially help reconcile the divide between gene-centric versus genome-centric theories in cancer evolution. PMID:22615582

  2. Spatial quantitation of FISH signals in diploid versus aneuploid nuclei.

    Science.gov (United States)

    Shete, Amol; Rao, Pulivarthi; Pati, Debananda; Merchant, Fatima

    2014-04-01

    Fluorescence in situ hybridization (FISH) is the most widely used molecular technique to visualize chromosomal abnormalities. Here, we describe a novel 3D modeling approach to allow precise shape estimation and localization of FISH signals in the nucleus of human embryonic stem cells (hES) undergoing progressive but defined aneuploidy. The hES cell line WA09 acquires an extra copy of chromosome 12 in culture with increasing passages. Both diploid and aneuploid nuclei were analyzed to quantitate the differences in the localization of centromeric FISH signals for chromosome 12 as it transitions from euploidy to aneuploidy. We employed superquadric modeling primitives coupled with principal component analysis to determine the 3D position of FISH signals within the nucleus. A novel aspect of our modeling approach is that it allows comparison of FISH signals across multiple cells by normalizing the position of the centromeric signals relative to a reference landmark in oriented nuclei. Using this model we present evidence of changes in the relative positioning of centromeres in trisomy-12 cells when compared with diploid cells from the same population. Our analysis also suggests a significant change in the spatial distribution of at least one of the FISH signals in the aneuploid chromosome complements implicating that an overall change in centromere position may occur in trisomy-12 due to the addition of an extra chromosome. These studies underscore the unique utility of our modeling algorithms in quantifying FISH signals in three dimensions. © 2013 International Society for Advancement of Cytometry.

  3. Is the aneuploid chromosome in an apomictic Boechera holboellii a genuine B chromosome?

    NARCIS (Netherlands)

    Sharbel, T.F.; Voigt, M.L.; Mitchell-Olds, T.; Kantama, L.; Jong, de J.H.S.G.M.

    2004-01-01

    The Boechera holboellii complex comprises B. holboellii and B. drummondii, both of which can reproduce through sex or apomixis. Sexuality is associated with diploidy, whereas apomictic individuals can either be diploid, aneuploid or triploid. Aneuploid individuals are found in geographically and

  4. Mouse model of chromosome mosaicism reveals lineage-specific depletion of aneuploid cells and normal developmental potential.

    Science.gov (United States)

    Bolton, Helen; Graham, Sarah J L; Van der Aa, Niels; Kumar, Parveen; Theunis, Koen; Fernandez Gallardo, Elia; Voet, Thierry; Zernicka-Goetz, Magdalena

    2016-03-29

    Most human pre-implantation embryos are mosaics of euploid and aneuploid cells. To determine the fate of aneuploid cells and the developmental potential of mosaic embryos, here we generate a mouse model of chromosome mosaicism. By treating embryos with a spindle assembly checkpoint inhibitor during the four- to eight-cell division, we efficiently generate aneuploid cells, resulting in embryo death during peri-implantation development. Live-embryo imaging and single-cell tracking in chimeric embryos, containing aneuploid and euploid cells, reveal that the fate of aneuploid cells depends on lineage: aneuploid cells in the fetal lineage are eliminated by apoptosis, whereas those in the placental lineage show severe proliferative defects. Overall, the proportion of aneuploid cells is progressively depleted from the blastocyst stage onwards. Finally, we show that mosaic embryos have full developmental potential, provided they contain sufficient euploid cells, a finding of significance for the assessment of embryo vitality in the clinic.

  5. Mouse model of chromosome mosaicism reveals lineage-specific depletion of aneuploid cells and normal developmental potential

    Science.gov (United States)

    Bolton, Helen; Graham, Sarah J. L.; Van der Aa, Niels; Kumar, Parveen; Theunis, Koen; Fernandez Gallardo, Elia; Voet, Thierry; Zernicka-Goetz, Magdalena

    2016-01-01

    Most human pre-implantation embryos are mosaics of euploid and aneuploid cells. To determine the fate of aneuploid cells and the developmental potential of mosaic embryos, here we generate a mouse model of chromosome mosaicism. By treating embryos with a spindle assembly checkpoint inhibitor during the four- to eight-cell division, we efficiently generate aneuploid cells, resulting in embryo death during peri-implantation development. Live-embryo imaging and single-cell tracking in chimeric embryos, containing aneuploid and euploid cells, reveal that the fate of aneuploid cells depends on lineage: aneuploid cells in the fetal lineage are eliminated by apoptosis, whereas those in the placental lineage show severe proliferative defects. Overall, the proportion of aneuploid cells is progressively depleted from the blastocyst stage onwards. Finally, we show that mosaic embryos have full developmental potential, provided they contain sufficient euploid cells, a finding of significance for the assessment of embryo vitality in the clinic. PMID:27021558

  6. Causes and consequences of protein folding stress in aneuploid cells.

    Science.gov (United States)

    Donnelly, Neysan; Storchová, Zuzana

    2015-01-01

    Imbalanced chromosomal content, or aneuploidy, strongly affects the physiology of eukaryotic cells. The consequences of these effects are frequently detrimental, in particular in Metazoans. In humans, aneuploidy has been causatively linked to pathological conditions such as spontaneous abortions, trisomy syndromes and cancer. However, only in recent years have we witnessed an unraveling of the complex phenotypes that are caused by aneuploidy. Importantly, it has become apparent that aneuploidy evokes global and uniform changes that cannot be explained by the altered expression of the specific genes located on aneuploid chromosomes. Recent discoveries show that aneuploidy negatively affects protein folding; in particular, the functions of the molecular chaperone Heat Shock Protein 90 (HSP90) and the upstream regulator of heat shock-induced transcription, Heat Shock Factor 1 (HSF1), are impaired. Here we discuss the possible causes and consequences of this impairment and propose that the protein folding stress instigated by aneuploidy may be a common feature of conditions as variable as cancer and trisomy syndromes.

  7. A large-scale expression strategy for multimeric extracellular protein complexes using Drosophila S2 cells and its application to the recombinant expression of heterodimeric ligand-binding domains of taste receptor.

    Science.gov (United States)

    Yamashita, Atsuko; Nango, Eriko; Ashikawa, Yuji

    2017-11-01

    Many of the extracellular proteins or extracellular domains of plasma membrane proteins exist or function as homo- or heteromeric multimer protein complexes. Successful recombinant production of such proteins is often achieved by co-expression of the components using eukaryotic cells via the secretory pathway. Here we report a strategy addressing large-scale expression of hetero-multimeric extracellular domains of plasma membrane proteins and its application to the extracellular domains of a taste receptor. The target receptor consists of a heterodimer of T1r2 and T1r3 proteins, and their extracellular ligand binding domains (LBDs) are responsible for the perception of major taste substances. However, despite the functional importance, recombinant production of the heterodimeric proteins has so far been unsuccessful. We achieved the successful preparation of the heterodimeric LBD by use of Drosophila S2 cells, which have a high secretory capacity, and by the establishment of a stable high-expression clone producing both subunits at a comparable level. The method overcame the problems encountered in the conventional transient expression of the receptor protein in insect cells using baculovirus or vector lipofection, which failed in the proper heterodimer production because of the biased expression of T1r3LBD over T1r2LBD. The large-scale expression methodology reported here may serve as one of the considerable strategies for the preparation of multimeric extracellular protein complexes. © 2017 The Protein Society.

  8. Mandatory chromosomal segment balance in aneuploid tumor cells

    Directory of Open Access Journals (Sweden)

    Li Lung Maria

    2007-01-01

    contrast to the well tolerated gain in 3q26-q27 is consistent with the fact that the former is often deleted in human tumors, whereas the latter is frequently amplified. The findings emphasize the importance of even minor changes in copy number in seemingly unbalanced aneuploid tumors.

  9. FREQUENCY OF ANEUPLOID SPERMATOZOA STUDIED BY MULTICOLOR FISH IN SERIAL SEMEN SAMPLES

    Science.gov (United States)

    Frequency of aneuploid spermatozoa studied by multicolor FISH in serial semen samplesM. Vozdova1, S. D. Perreault2, O. Rezacova1, D. Zudova1 , Z. Zudova3, S. G. Selevan4, J. Rubes1,51Veterinary Research Institute, Brno, Czech Republic; 2U.S. Environmental Protection A...

  10. Doble aneuploidía en un niño Colombiano

    OpenAIRE

    Pachajoa Londoño, Harry Mauricio; Perilla Duque, Diana; Isaza de Lourido, Carolina

    2011-01-01

    La ocurrencia de una doble aneuploidía en una misma persona es un evento relativamente raro. Se presenta el caso de un niño de siete meses de edad, de padres no consanguíneos con características clínicas de síndrome de Down y cariotipo 48XXY.

  11. Induction of genomic instability and activation of autophagy in artificial human aneuploid cells

    Energy Technology Data Exchange (ETDEWEB)

    Ariyoshi, Kentaro [Hirosaki University, Institute of Radiation Emergency Medicine, 66-1 Hon-cho, Hirosaki 036-8564 (Japan); Miura, Tomisato; Kasai, Kosuke; Fujishima, Yohei [Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki 036-8564 (Japan); Oshimura, Mitsuo [Chromosome Engineering Research Center (CERC), Tottori University, Nishicho 86, Yonago, Tottori 683-8503 (Japan); Yoshida, Mitsuaki A., E-mail: ariyoshi@hirosaki-u.ac.jp [Hirosaki University, Institute of Radiation Emergency Medicine, 66-1 Hon-cho, Hirosaki 036-8564 (Japan)

    2016-08-15

    Highlights: • Clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. • Increased autophagy was observed in the artificially aneuploid clones. • Inhibition of autophagy resulted in increased genomic instability and DNA damage. • Intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones. - Abstract: Chromosome missegregation can lead to a change in chromosome number known as aneuploidy. Although aneuploidy is a known hallmark of cancer cells, the various mechanisms by which altered gene and/or DNA copy number facilitate tumorigenesis remain unclear. To understand the effect of aneuploidy occurring in non-tumorigenic human breast epithelial cells, we generated clones harboring artificial aneuploidy using microcell-mediated chromosome transfer. Our results demonstrate that clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. Also, the increased autophagy was observed in the artificially aneuploidy clones, and inhibition of autophagy resulted in increased genomic instability and DNA damage. In addition, the intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones, and inhibition of autophagy further increased the production of reactive oxygen species. Together, these results suggest that even a single extraneous chromosome can induce genomic instability, and that autophagy triggered by aneuploidy-induced stress is a mechanism to protect cells bearing abnormal chromosome number.

  12. Induction of genomic instability and activation of autophagy in artificial human aneuploid cells

    International Nuclear Information System (INIS)

    Ariyoshi, Kentaro; Miura, Tomisato; Kasai, Kosuke; Fujishima, Yohei; Oshimura, Mitsuo; Yoshida, Mitsuaki A.

    2016-01-01

    Highlights: • Clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. • Increased autophagy was observed in the artificially aneuploid clones. • Inhibition of autophagy resulted in increased genomic instability and DNA damage. • Intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones. - Abstract: Chromosome missegregation can lead to a change in chromosome number known as aneuploidy. Although aneuploidy is a known hallmark of cancer cells, the various mechanisms by which altered gene and/or DNA copy number facilitate tumorigenesis remain unclear. To understand the effect of aneuploidy occurring in non-tumorigenic human breast epithelial cells, we generated clones harboring artificial aneuploidy using microcell-mediated chromosome transfer. Our results demonstrate that clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. Also, the increased autophagy was observed in the artificially aneuploidy clones, and inhibition of autophagy resulted in increased genomic instability and DNA damage. In addition, the intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones, and inhibition of autophagy further increased the production of reactive oxygen species. Together, these results suggest that even a single extraneous chromosome can induce genomic instability, and that autophagy triggered by aneuploidy-induced stress is a mechanism to protect cells bearing abnormal chromosome number.

  13. Footprintless disruption of prosurvival genes in aneuploid cancer cells using CRISPR/Cas9 technology.

    Science.gov (United States)

    Krachulec, Justyna M; Sedlmeier, Georg; Thiele, Wilko; Sleeman, Jonathan P

    2016-06-01

    CRISPR/Cas9 has emerged as a powerful methodology for the targeted editing of genomic DNA sequences. Nevertheless, the intrinsic inefficiency of transfection methods required to use this technique with cultured cells requires the selection and isolation of successfully modified cells, which invariably subjects the cells to stress. Here we report a workflow that allows the isolation of genomically modified cells, even where loss of functional alleles constitutes a selective disadvantage owing to impaired ability to survive stress. Using targeted disruption of the Id1 and Id3 genes in murine B16-F10 and Ret melanoma cell lines as an example, we show that the method allows for the footprintless isolation of CRISPR/Cas9-modified aneuploid cancer cells. We also provide evidence that serial CRISPR/Cas9 modifications can occur, for example when initial homologous recombination events introduce cryptic PAM sequences, and demonstrate that multiple alleles can be successfully targeted in aneuploid cancer cells. By sequencing individual alleles we also found evidence for CRISPR/Cas9-induced transposable element insertion, albeit at a low frequency. This workflow should have broad application in the functional analysis of prosurvival gene function in cultured cells.

  14. Modeling abnormal early development with induced pluripotent stem cells from aneuploid syndromes.

    Science.gov (United States)

    Li, Wen; Wang, Xianming; Fan, Wenxia; Zhao, Ping; Chan, Yau-Chi; Chen, Shen; Zhang, Shiqiang; Guo, Xiangpeng; Zhang, Ya; Li, Yanhua; Cai, Jinglei; Qin, Dajiang; Li, Xingyan; Yang, Jiayin; Peng, Tianran; Zychlinski, Daniela; Hoffmann, Dirk; Zhang, Ruosi; Deng, Kang; Ng, Kwong-Man; Menten, Bjorn; Zhong, Mei; Wu, Jiayan; Li, Zhiyuan; Chen, Yonglong; Schambach, Axel; Tse, Hung-Fat; Pei, Duanqing; Esteban, Miguel A

    2012-01-01

    Many human diseases share a developmental origin that manifests during childhood or maturity. Aneuploid syndromes are caused by supernumerary or reduced number of chromosomes and represent an extreme example of developmental disease, as they have devastating consequences before and after birth. Investigating how alterations in gene dosage drive these conditions is relevant because it might help treat some clinical aspects. It may also provide explanations as to how quantitative differences in gene expression determine phenotypic diversity and disease susceptibility among natural populations. Here, we aimed to produce induced pluripotent stem cell (iPSC) lines that can be used to improve our understanding of aneuploid syndromes. We have generated iPSCs from monosomy X [Turner syndrome (TS)], trisomy 8 (Warkany syndrome 2), trisomy 13 (Patau syndrome) and partial trisomy 11;22 (Emanuel syndrome), using either skin fibroblasts from affected individuals or amniocytes from antenatal diagnostic tests. These cell lines stably maintain the karyotype of the donors and behave like embryonic stem cells in all tested assays. TS iPSCs were used for further studies including global gene expression analysis and tissue-specific directed differentiation. Multiple clones displayed lower levels of the pseudoautosomal genes ASMTL and PPP2R3B than the controls. Moreover, they could be transformed into neural-like, hepatocyte-like and heart-like cells, but displayed insufficient up-regulation of the pseudoautosomal placental gene CSF2RA during embryoid body formation. These data support that abnormal organogenesis and early lethality in TS are not caused by a tissue-specific differentiation blockade, but rather involves other abnormalities including impaired placentation.

  15. The fate of chrysotile-induced multipolar mitosis and aneuploid population in cultured lung cancer cells.

    Directory of Open Access Journals (Sweden)

    Beatriz de Araujo Cortez

    Full Text Available Chrysotile is one of the six types of asbestos, and it is the only one that can still be commercialized in many countries. Exposure to other types of asbestos has been associated with serious diseases, such as lung carcinomas and pleural mesotheliomas. The association of chrysotile exposure with disease is controversial. However, in vitro studies show the mutagenic potential of chrysotile, which can induce DNA and cell damage. The present work aimed to analyze alterations in lung small cell carcinoma cultures after 48 h of chrysotile exposure, followed by 2, 4 and 8 days of recovery in fiber-free culture medium. Some alterations, such as aneuploid cell formation, increased number of cells in G2/M phase and cells in multipolar mitosis were observed even after 8 days of recovery. The presence of chrysotile fibers in the cell cultures was detected and cell morphology was observed by laser scanning confocal microscopy. After 4 and 8 days of recovery, only a few chrysotile fragments were present in some cells, and the cellular morphology was similar to that of control cells. Cells transfected with the GFP-tagged α-tubulin plasmid were treated with chrysotile for 24 or 48 h and cells in multipolar mitosis were observed by time-lapse microscopy. Fates of these cells were established: retention in metaphase, cell death, progression through M phase generating more than two daughter cells or cell fusion during telophase or cytokinesis. Some of them were related to the formation of aneuploid cells and cells with abnormal number of centrosomes.

  16. Gene expression analysis of induced pluripotent stem cells from aneuploid chromosomal syndromes

    Science.gov (United States)

    2013-01-01

    Background Human aneuploidy is the leading cause of early pregnancy loss, mental retardation, and multiple congenital anomalies. Due to the high mortality associated with aneuploidy, the pathophysiological mechanisms of aneuploidy syndrome remain largely unknown. Previous studies focused mostly on whether dosage compensation occurs, and the next generation transcriptomics sequencing technology RNA-seq is expected to eventually uncover the mechanisms of gene expression regulation and the related pathological phenotypes in human aneuploidy. Results Using next generation transcriptomics sequencing technology RNA-seq, we profiled the transcriptomes of four human aneuploid induced pluripotent stem cell (iPSC) lines generated from monosomy × (Turner syndrome), trisomy 8 (Warkany syndrome 2), trisomy 13 (Patau syndrome), and partial trisomy 11:22 (Emanuel syndrome) as well as two umbilical cord matrix iPSC lines as euploid controls to examine how phenotypic abnormalities develop with aberrant karyotype. A total of 466 M (50-bp) reads were obtained from the six iPSC lines, and over 13,000 mRNAs were identified by gene annotation. Global analysis of gene expression profiles and functional analysis of differentially expressed (DE) genes were implemented. Over 5000 DE genes are determined between aneuploidy and euploid iPSCs respectively while 9 KEGG pathways are overlapped enriched in four aneuploidy samples. Conclusions Our results demonstrate that the extra or missing chromosome has extensive effects on the whole transcriptome. Functional analysis of differentially expressed genes reveals that the genes most affected in aneuploid individuals are related to central nervous system development and tumorigenesis. PMID:24564826

  17. Diagnóstico genético preimplantacional: análisis de aneuploidías únicas

    Directory of Open Access Journals (Sweden)

    Paul W. López

    2013-01-01

    Full Text Available Introducción: De las causas más conocidas en cuanto a la falta del éxito en el embarazo con tratamientos de reproducción asistida son aquellas relacionadas a las aneuploidías cromosómicas presentes en los embriones. El diagnóstico genético preimplantacional (PGD es una técnica empleada en reproducción asistida para detectar estas anomalías, seleccionando aquellos que sean cromosómicamente normales, para luego transferirlos al útero de la paciente. Los embriones con aneuploidías únicas podrían tener la capacidad de sobrevivir y lograr la implantación, y por lo tanto, sin diagnóstico previo, estas podrían pasar desapercibidas. Objetivos: Determinar la incidencia de aneuploidías únicas en embriones de buena calidad embrionaria en el día 3 de desarrollo hasta blastocisto. Diseño: Estadístico y experimental. Instituciones: Reprogenetics Latinoamérica y Centro de Reproducción asistida, de la Clínica Concebir. Material Biológico: Muestras de biopsia embrionaria. Metodología: Análisis comparativo de resultados a partir de la evaluación de cada muestra obtenida por biopsia en el día tercero y día quinto de desarrollo embrionario, realizando el PGD por hibridación in situ (FISH y genómica comparada (aCGH, respectivamente. Resultados: El 62,9% de embriones que presentaron monosomías únicas al tercer día de desarrollo embrionario resultaron ser de 8 células. Pero cuando se evaluó por aCGH en día cinco, 42,3% resultó anormal, y de estos 37,5% perteneció al estadio de 8 células. El índice de monosomías únicas en blastocisto resultó ser 57,9% de un total de 84,2% de aneuploidías únicas. Conclusiones: Los embriones de 8 células en el tercer día de desarrollo embrionario son los más probables de llegar al estadio de blastocisto, así como presentar aneuploidías únicas.

  18. A strategy for constructing aneuploid yeast strains by transient nondisjunction of a target chromosome

    Directory of Open Access Journals (Sweden)

    Peck Anders T

    2009-07-01

    Full Text Available Abstract Background Most methods for constructing aneuploid yeast strains that have gained a specific chromosome rely on spontaneous failures of cell division fidelity. In Saccharomyces cerevisiae, extra chromosomes can be obtained when errors in meiosis or mitosis lead to nondisjunction, or when nuclear breakdown occurs in heterokaryons. We describe a strategy for constructing N+1 disomes that does not require such spontaneous failures. The method combines two well-characterized genetic tools: a conditional centromere that transiently blocks disjunction of one specific chromosome, and a duplication marker assay that identifies disomes among daughter cells. To test the strategy, we targeted chromosomes III, IV, and VI for duplication. Results The centromere of each chromosome was replaced by a centromere that can be blocked by growth in galactose, and ura3::HIS3, a duplication marker. Transient exposure to galactose induced the appearance of colonies carrying duplicated markers for chromosomes III or IV, but not VI. Microarray-based comparative genomic hybridization (CGH confirmed that disomic strains carrying extra chromosome III or IV were generated. Chromosome VI contains several genes that are known to be deleterious when overexpressed, including the beta-tubulin gene TUB2. To test whether a tubulin stoichiometry imbalance is necessary for the apparent lethality caused by an extra chromosome VI, we supplied the parent strain with extra copies of the alpha-tubulin gene TUB1, then induced nondisjunction. Galactose-dependent chromosome VI disomes were produced, as revealed by CGH. Some chromosome VI disomes also carried extra, unselected copies of additional chromosomes. Conclusion This method causes efficient nondisjunction of a targeted chromosome and allows resulting disomic cells to be identified and maintained. We used the method to test the role of tubulin imbalance in the apparent lethality of disomic chromosome VI. Our results indicate

  19. Estudio de anomalías meióticas y aneuploidías en pacientes con azoospermia secretora

    OpenAIRE

    Peinado Cervera, Vanessa

    2016-01-01

    La contribución de anomalías meióticas a la infertilidad masculina humana ha sido reconocida desde hace tiempo. Los errores meióticos ligados a los procesos de sinapsis, recombinación y reparación del ADN, interfieren en el proceso normal de la meiosis pudiendo dar lugar a una segregación anómala de los cromosomas homólogos (meiosis I) ó las cromátidas hermanas (meiosis II) y generar espermatozoides portadores de alteraciones cromosómicas numéricas (aneuploides o diploides). El objetivo p...

  20. Giemsa C-banding in two polyploid, South American Hordeum species, H. tetraploidum and H. lechleri, and their aneuploid hybrids with H. vulgare

    DEFF Research Database (Denmark)

    Linde-Laursen, Ib; Bothmer, R. von

    1986-01-01

    American taxa of the same sections suggest a rather close relationship and support that the biological basis for their classification with different sections is questionable. C-banding patterns identified the chromosomes of parental genomes in interspecific hybrids between the two species and H. vulgare....... The hybrids were stably aneuploid. Both had lost and acquired H. vulgare chromosomes. Thus, somatic elimination of chromosomes was combined with multiplication of chromosomes. The observations of stably aneuploid hybrids have implications for the exploitation of alien germplasm. The activity of non-H. vulgare...

  1. DUAL PARAMETER FLOW-CYTOMETRY FOR DEOXYRIBONUCLEIC-ACID AND INTERMEDIATE FILAMENT PROTEINS OF RESIDUAL MATURE TERATOMA - ALL TUMOR-CELLS ARE ANEUPLOID

    NARCIS (Netherlands)

    LOOIJENGA, LHJ; OOSTERHUIS, JW; RAMAEKERS, FCS; DEJONG, B; BECK, JLM; SLEIJFER, DT; KOOPS, HS; Dam, A.

    Most testicular germ cell tumors of adults are presumably derived from polyploid carcinoma in situ. Thus, one would expect that even highly differentiated teratoma components are aneuploid and that it is unlikely to find diploid tumor cell (sub)populations. We studied 10 residual mature teratomas

  2. Glia in Drosophila behavior.

    Science.gov (United States)

    Zwarts, L; Van Eijs, F; Callaerts, P

    2015-09-01

    Glial cells constitute about 10 % of the Drosophila nervous system. The development of genetic and molecular tools has helped greatly in defining different types of glia. Furthermore, considerable progress has been made in unraveling the mechanisms that control the development and differentiation of Drosophila glia. By contrast, the role of glia in adult Drosophila behavior is not well understood. We here summarize recent work describing the role of glia in normal behavior and in Drosophila models for neurological and behavioral disorders.

  3. Metabolomic Studies in Drosophila.

    Science.gov (United States)

    Cox, James E; Thummel, Carl S; Tennessen, Jason M

    2017-07-01

    Metabolomic analysis provides a powerful new tool for studies of Drosophila physiology. This approach allows investigators to detect thousands of chemical compounds in a single sample, representing the combined contributions of gene expression, enzyme activity, and environmental context. Metabolomics has been used for a wide range of studies in Drosophila , often providing new insights into gene function and metabolic state that could not be obtained using any other approach. In this review, we survey the uses of metabolomic analysis since its entry into the field. We also cover the major methods used for metabolomic studies in Drosophila and highlight new directions for future research. Copyright © 2017 by the Genetics Society of America.

  4. Hearing regulates Drosophila aggression.

    Science.gov (United States)

    Versteven, Marijke; Vanden Broeck, Lies; Geurten, Bart; Zwarts, Liesbeth; Decraecker, Lisse; Beelen, Melissa; Göpfert, Martin C; Heinrich, Ralf; Callaerts, Patrick

    2017-02-21

    Aggression is a universal social behavior important for the acquisition of food, mates, territory, and social status. Aggression in Drosophila is context-dependent and can thus be expected to involve inputs from multiple sensory modalities. Here, we use mechanical disruption and genetic approaches in Drosophila melanogaster to identify hearing as an important sensory modality in the context of intermale aggressive behavior. We demonstrate that neuronal silencing and targeted knockdown of hearing genes in the fly's auditory organ elicit abnormal aggression. Further, we show that exposure to courtship or aggression song has opposite effects on aggression. Our data define the importance of hearing in the control of Drosophila intermale aggression and open perspectives to decipher how hearing and other sensory modalities are integrated at the neural circuit level.

  5. Controlling S2 terminal using FS software

    Science.gov (United States)

    Xue, Zhuhe

    New S2FS software for controlling S2 terminal of Sheshan station has been developed. It works under Field System software. All S2 operation commands are incorporated in a station program. The interface of SWT computer and S2 terminal is RS232 interface. S2FS software is designed by using Shell and C language. It has been used in VSOP experiments.

  6. Cancer in Drosophila

    DEFF Research Database (Denmark)

    Herranz, Héctor; Eichenlaub, Teresa; Cohen, Stephen M

    2016-01-01

    Cancer genomics has greatly increased our understanding of the complexity of the genetic and epigenetic changes found in human tumors. Understanding the functional relationships among these elements calls for the use of flexible genetic models. We discuss the use of Drosophila models to study...

  7. BMAA neurotoxicity in Drosophila.

    Science.gov (United States)

    Zhou, Xianchong; Escala, Wilfredo; Papapetropoulos, Spyridon; Bradley, Walter G; Zhai, R Grace

    2009-01-01

    We report the establishment of an in vivo model using the fruit fly Drosophila melanogaster to investigate the toxic effects of L-BMAA. We found that dietary intake of BMAA reduced the lifespan as well as the neurological functions of flies. Furthermore, we have developed an HPLC method to reliably detect both free and protein-bound BMAA in fly tissue extracts.

  8. Modeling Human Cancers in Drosophila.

    Science.gov (United States)

    Sonoshita, M; Cagan, R L

    2017-01-01

    Cancer is a complex disease that affects multiple organs. Whole-body animal models provide important insights into oncology that can lead to clinical impact. Here, we review novel concepts that Drosophila studies have established for cancer biology, drug discovery, and patient therapy. Genetic studies using Drosophila have explored the roles of oncogenes and tumor-suppressor genes that when dysregulated promote cancer formation, making Drosophila a useful model to study multiple aspects of transformation. Not limited to mechanism analyses, Drosophila has recently been showing its value in facilitating drug development. Flies offer rapid, efficient platforms by which novel classes of drugs can be identified as candidate anticancer leads. Further, we discuss the use of Drosophila as a platform to develop therapies for individual patients by modeling the tumor's genetic complexity. Drosophila provides both a classical and a novel tool to identify new therapeutics, complementing other more traditional cancer tools. © 2017 Elsevier Inc. All rights reserved.

  9. DNA aneuploidy in colorectal adenomas: Role in the adenoma-carcinoma sequence Aneuploidía del ADN en adenomas colónicos: Papel en la secuencia adenoma-carcinoma

    Directory of Open Access Journals (Sweden)

    M. Alcántara Torres

    2005-01-01

    Full Text Available Introduction: aneuploidy has been observed in 6-27% of lesions known to be precursors of colorectal cancer, such as adenomas or ulcerative colitis. It has been suggested that aneuploidy may predispose to malignancy in these cases. However, its role in the adenoma-carcinoma sequence has not been definitely established. The objective of this study was to assess the incidence of aneuploidy in colon adenomas, as well as to study its possible role in the adenoma-carcinoma sequence. Material and methods: the study was performed on a series of 57 large bowel adenomas measuring 10 mm or more, collected from 54 consecutive patients. All specimens were obtained either by endoscopic or by surgical resection. There were 49 adenomas with low-grade dysplasia, two with high-grade dysplasia, two intramucous carcinomas, and four microinvasive carcinomas. A flow cytometric DNA analysis was performed in fresh specimens following Vindelov´s method. Results: aneuploid DNA was detected in five out of 49 low-grade dysplasia adenomas (10%, in all four high-grade dysplasia adenomas or intramucous carcinomas (100%, and in three out of four microinvasive carcinomas (75%. The association between aneuploidy and high-grade dysplasia adenomas, intramucous, or microinvasive carcinoma was statistically significant (p Introducción: en patología benigna de intestino grueso precursora del cáncer colorrectal, como adenomas o colitis ulcerosa, se ha observado aneuploidía en el 6-27% de los casos y se ha sugerido que su presencia predispone al desarrollo de malignidad. Sin embargo, su papel en la secuencia adenoma-carcinoma no se ha demostrado de forma concluyente. El objetivo de nuestro trabajo fue valorar la incidencia de aneuploidía en adenomas colónicos, con y sin signos de malignidad, y estudiar su posible papel en la secuencia adenoma-carcinoma. Material y métodos: el estudio se realizó en una serie de 57 adenomas de intestino grueso, de 10 o más mil

  10. CLImAT: accurate detection of copy number alteration and loss of heterozygosity in impure and aneuploid tumor samples using whole-genome sequencing data.

    Science.gov (United States)

    Yu, Zhenhua; Liu, Yuanning; Shen, Yi; Wang, Minghui; Li, Ao

    2014-09-15

    Whole-genome sequencing of tumor samples has been demonstrated as an efficient approach for comprehensive analysis of genomic aberrations in cancer genome. Critical issues such as tumor impurity and aneuploidy, GC-content and mappability bias have been reported to complicate identification of copy number alteration and loss of heterozygosity in complex tumor samples. Therefore, efficient computational methods are required to address these issues. We introduce CLImAT (CNA and LOH Assessment in Impure and Aneuploid Tumors), a bioinformatics tool for identification of genomic aberrations from tumor samples using whole-genome sequencing data. Without requiring a matched normal sample, CLImAT takes integrated analysis of read depth and allelic frequency and provides extensive data processing procedures including GC-content and mappability correction of read depth and quantile normalization of B-allele frequency. CLImAT accurately identifies copy number alteration and loss of heterozygosity even for highly impure tumor samples with aneuploidy. We evaluate CLImAT on both simulated and real DNA sequencing data to demonstrate its ability to infer tumor impurity and ploidy and identify genomic aberrations in complex tumor samples. The CLImAT software package can be freely downloaded at http://bioinformatics.ustc.edu.cn/CLImAT/. © The Author 2014. Published by Oxford University Press.

  11. First Detection of Interstellar S2H

    Science.gov (United States)

    Fuente, Asunción; Goicoechea, Javier R.; Pety, Jérôme; Le Gal, Romane; Martín-Doménech, Rafael; Gratier, Pierre; Guzmán, Viviana; Roueff, Evelyne; Loison, Jean Christophe; Muñoz Caro, Guillermo M.; Wakelam, Valentine; Gerin, Maryvonne; Riviere-Marichalar, Pablo; Vidal, Thomas

    2017-12-01

    We present the first detection of gas-phase S2H in the Horsehead, a moderately UV-irradiated nebula. This confirms the presence of doubly sulfuretted species in the interstellar medium and opens a new challenge for sulfur chemistry. The observed S2H abundance is ∼5 × 10‑11, only a factor of 4–6 lower than that of the widespread H2S molecule. H2S and S2H are efficiently formed on the UV-irradiated icy grain mantles. We performed ice irradiation experiments to determine the H2S and S2H photodesorption yields. The obtained values are ∼1.2 × 10‑3 and <1 × 10‑5 molecules per incident photon for H2S and S2H, respectively. Our upper limit to the S2H photodesorption yield suggests that photodesorption is not a competitive mechanism to release the S2H molecules to the gas phase. Other desorption mechanisms such as chemical desorption, cosmic-ray desorption, and grain shattering can increase the gaseous S2H abundance to some extent. Alternatively, S2H can be formed via gas-phase reactions involving gaseous H2S and the abundant ions S+ and SH+. The detection of S2H in this nebula therefore could be the result of the coexistence of an active grain-surface chemistry and gaseous photochemistry.

  12. Transgenesis in Drosophila melanogaster.

    Science.gov (United States)

    Ringrose, Leonie

    2009-01-01

    Transgenesis in Drosophila melanogaster relies upon direct microinjection of embryos and subsequent crossing of surviving adults. The necessity of crossing single flies to screen for transgenic events limits the range of useful transgenesis techniques to those that have a very high frequency of integration, so that about 1 in 10 to 1 in 100 surviving adult flies carry a transgene. Until recently, only random P-element transgenesis fulfilled these criteria. However, recent advances have brought homologous recombination and site-directed integration up to and beyond this level of efficiency. For all transgenesis techniques in Drosophila melanogaster, microinjection of embryos is the central procedure. This chapter gives a detailed protocol for microinjection, and aims to enable the reader to use it for both site-directed integration and for P-element transgenesis.

  13. Drosophila by the dozen

    Energy Technology Data Exchange (ETDEWEB)

    Celniker, Susan E.; Hoskins, Roger A.

    2007-07-13

    This year's conference on Drosophila research illustratedwell the current focus of Drosophila genomics on the comprehensiveidentification of functional elements in the genome sequence, includingmRNA transcripts arising from multiple alternative start sites and splicesites, a multiplicity of noncoding transcripts and small RNAs,identification of binding sites for transcription factors, sequenceconservation in related species and sequence variation within species.Resources and technologies for genetics and functional genomics aresteadily being improved, including the building of collections oftransposon insertion mutants and hairpin constructs for RNA interference(RNAi). The conference also highlighted progress in the use of genomicinformation by many laboratories to study diverse aspects of biology andmodels of human disease. Here we will review a few highlights of especialinterest to readers of Genome Biology.

  14. The Drosophila melanogaster host model

    Science.gov (United States)

    Igboin, Christina O.; Griffen, Ann L.; Leys, Eugene J.

    2012-01-01

    The deleterious and sometimes fatal outcomes of bacterial infectious diseases are the net result of the interactions between the pathogen and the host, and the genetically tractable fruit fly, Drosophila melanogaster, has emerged as a valuable tool for modeling the pathogen–host interactions of a wide variety of bacteria. These studies have revealed that there is a remarkable conservation of bacterial pathogenesis and host defence mechanisms between higher host organisms and Drosophila. This review presents an in-depth discussion of the Drosophila immune response, the Drosophila killing model, and the use of the model to examine bacterial–host interactions. The recent introduction of the Drosophila model into the oral microbiology field is discussed, specifically the use of the model to examine Porphyromonas gingivalis–host interactions, and finally the potential uses of this powerful model system to further elucidate oral bacterial-host interactions are addressed. PMID:22368770

  15. Myoblast fusion in Drosophila

    International Nuclear Information System (INIS)

    Haralalka, Shruti; Abmayr, Susan M.

    2010-01-01

    The body wall musculature of a Drosophila larva is composed of an intricate pattern of 30 segmentally repeated muscle fibers in each abdominal hemisegment. Each muscle fiber has unique spatial and behavioral characteristics that include its location, orientation, epidermal attachment, size and pattern of innervation. Many, if not all, of these properties are dictated by founder cells, which determine the muscle pattern and seed the fusion process. Myofibers are then derived from fusion between a specific founder cell and several fusion competent myoblasts (FCMs) fusing with as few as 3-5 FCMs in the small muscles on the most ventral side of the embryo and as many as 30 FCMs in the larger muscles on the dorsal side of the embryo. The focus of the present review is the formation of the larval muscles in the developing embryo, summarizing the major issues and players in this process. We have attempted to emphasize experimentally-validated details of the mechanism of myoblast fusion and distinguish these from the theoretically possible details that have not yet been confirmed experimentally. We also direct the interested reader to other recent reviews that discuss myoblast fusion in Drosophila, each with their own perspective on the process . With apologies, we use gene nomenclature as specified by Flybase (http://flybase.org) but provide Table 1 with alternative names and references.

  16. SUMOylation in Drosophila Development

    Directory of Open Access Journals (Sweden)

    Albert J. Courey

    2012-07-01

    Full Text Available Small ubiquitin-related modifier (SUMO, an ~90 amino acid ubiquitin-like protein, is highly conserved throughout the eukaryotic domain. Like ubiquitin, SUMO is covalently attached to lysine side chains in a large number of target proteins. In contrast to ubiquitin, SUMO does not have a direct role in targeting proteins for proteasomal degradation. However, like ubiquitin, SUMO does modulate protein function in a variety of other ways. This includes effects on protein conformation, subcellular localization, and protein–protein interactions. Significant insight into the in vivo role of SUMOylation has been provided by studies in Drosophila that combine genetic manipulation, proteomic, and biochemical analysis. Such studies have revealed that the SUMO conjugation pathway regulates a wide variety of critical cellular and developmental processes, including chromatin/chromosome function, eggshell patterning, embryonic pattern formation, metamorphosis, larval and pupal development, neurogenesis, development of the innate immune system, and apoptosis. This review discusses our current understanding of the diverse roles for SUMO in Drosophila development.

  17. Drosophila Myc is required for normal DREF gene expression

    International Nuclear Information System (INIS)

    Dang Thi Phuong Thao; Seto, Hirokazu; Yamaguchi, Masamitsu

    2008-01-01

    The Drosophila DNA replication-related element-binding factor (dDREF) is required for the expression of many proliferation-related genes carrying the DRE sequence, 5'-TATCGATA. Finding a canonical E-box, 5'-CACGTG, in the dDREF gene promoter prompted us to explore the possibility that the dDREF gene is a target of Drosophila Myc (dMyc). Luciferase transient expression assays combined with RNA interference in Drosophila S2 cells revealed that knockdown of dmyc reduced dDREF gene promoter activity by 35% to 82%, an effect at least partly mediated by the E-box in the promoter. dm 4 /Y hemizygous mutant larvae demonstrated no maternal dMyc and severe impairment of dDREF mRNA transcription. dMyc loss of function in dm 2 /dm 2 homozygous mutant follicle cell clones also resulted in loss of anti-dDREF immunostaining in nuclei. In contrast, co-expression of dMyc-dMax up-regulated dDREF promoter activity in S2 cells. Furthermore, dMyc over-expressing clones exhibited a high level of dDREF gene expression in wing and eye discs. These results taken together indicate that dMyc is indeed required for dDREF gene expression

  18. Behavior of wild-type and transfected S2 cells cultured in two different media.

    Science.gov (United States)

    Batista, Fabiana R X; Greco, Kátia N; Astray, Renato M; Jorge, Soraia A C; Augusto, Elisabeth F P; Pereira, Carlos A; Mendonça, Ronaldo Z; Moraes, Angela M

    2011-01-01

    An animal protein-free medium composed of IPL-41 containing 6 g L(-1) yeastolate ultrafiltrate, 10 g L(-1) glucose, 2 g L(-1) lactose, 5 g L(-1) glutamine, 1% lipid emulsion, and 0.1% Pluronic F-68 was used for producing recombinant proteins in batch mode employing two cell lines, S2AcRVGP2k expressing the G glycoprotein from rabies virus (RVGP) and S2AcHBsAgHy-9C expressing the surface antigen of hepatitis B virus (HBsAg), both obtained from Drosophila melanogaster S2 cells. Growth of wild-type S2 cells was also evaluated in the same medium. Cell behavior in the tested medium was compared to that verified in Sf900 II®. The results show that in shake flasks, S2AcRVGP2k and S2AcHBsAgHy-9C cells reached around 2 × 10(7) cells mL(-1) in both media. In supplemented IPL-41 and Sf900 II® media, S2AcRVGP2k cells produced 367 ng RVGP mL(-1) and 638 ng RVGP mL(-1), respectively, while S2AcHBsAgHy-9C cells correspondently produced 573 ng HBsAg mL(-1) and 322 ng HBsAg mL(-1) in the mentioned media. In stirred tanks, S2AcRVGP2k cells reached 3 × 10(7) cells mL(-1) and produced up to 758 ng RVGP mL(-1). In general, glucose was consumed by cells, while lactate and ammonia were produced.

  19. Influencia de la estimulación ovárica durante un tratamiento de fecundación in vitro en la incidencia de aneuploidías embrionarias

    OpenAIRE

    Labarta Demur, María Elena

    2014-01-01

    La baja fecundidad humana podría deberse a la alta incidencia de anomalías cromosómicas embrionarias que justifica que hasta un 70% de las concepciones espontáneas no lleguen a término. La elevada tasa de aneuploidías observada en tratamientos de Fecundación in vitro (FIV) podría ser inherente a la especie humana o estar relacionada con los procedimientos derivados de la técnica, como las condiciones de cultivo in vitro o la estimulación ovárica (EO). Se ha especulado que esta última pudiera ...

  20. Internal epithelia in Drosophila display rudimentary competence to form cytoplasmic networks of transgenic human vimentin.

    Science.gov (United States)

    Gullmets, Josef; Torvaldson, Elin; Lindqvist, Julia; Imanishi, Susumu Y; Taimen, Pekka; Meinander, Annika; Eriksson, John E

    2017-12-01

    Cytoplasmic intermediate filaments (cIFs) are found in all eumetazoans, except arthropods. To investigate the compatibility of cIFs in arthropods, we expressed human vimentin (hVim), a cIF with filament-forming capacity in vertebrate cells and tissues, transgenically in Drosophila Transgenic hVim could be recovered from whole-fly lysates by using a standard procedure for intermediate filament (IF) extraction. When this procedure was used to test for the possible presence of IF-like proteins in flies, only lamins and tropomyosin were observed in IF-enriched extracts, thereby providing biochemical reinforcement to the paradigm that arthropods lack cIFs. In Drosophila , transgenic hVim was unable to form filament networks in S2 cells and mesenchymal tissues; however, cage-like vimentin structures could be observed around the nuclei in internal epithelia, which suggests that Drosophila retains selective competence for filament formation. Taken together, our results imply that although the filament network formation competence is partially lost in Drosophila , a rudimentary filament network formation ability remains in epithelial cells. As a result of the observed selective competence for cIF assembly in Drosophila , we hypothesize that internal epithelial cIFs were the last cIFs to disappear from arthropods.-Gullmets, J., Torvaldson, E., Lindqvist, J., Imanishi, S. Y., Taimen, P., Meinander, A., Eriksson, J. E. Internal epithelia in Drosophila display rudimentary competence to form cytoplasmic networks of transgenic human vimentin. © FASEB.

  1. Spektroskopie a spektroelektrochemie MoS2

    OpenAIRE

    Jurková, Kateřina

    2014-01-01

    This work deals with studies MoS2 layers prepared by mechanical exfoliation was detected by optical microscopy and the number of layers was determined from AFM measurement. The layers were characterized by Raman spectroscopy in various wavelengths. A spectroelectrochemical cell for the sandwich sample consisting of a MoS2 layer and two layers of graphene with various isotope composition and Raman spectra measurements were performed at voltages from 0.0 V to 0.9 V. A larger shift of the G band...

  2. Cytokines in Drosophila immunity.

    Science.gov (United States)

    Vanha-Aho, Leena-Maija; Valanne, Susanna; Rämet, Mika

    2016-02-01

    Cytokines are a large and diverse group of small proteins that can affect many biological processes, but most commonly cytokines are known as mediators of the immune response. In the event of an infection, cytokines are produced in response to an immune stimulus, and they function as key regulators of the immune response. Cytokines come in many shapes and sizes, and although they vary greatly in structure, their functions have been well conserved in evolution. The immune signaling pathways that respond to cytokines are remarkably conserved from fly to man. Therefore, Drosophila melanogaster, provides an excellent platform for studying the biology and function of cytokines. In this review, we will describe the cytokines and cytokine-like molecules found in the fly and discuss their roles in host immunity. Copyright © 2015 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.

  3. Humidity Sensing in Drosophila.

    Science.gov (United States)

    Enjin, Anders; Zaharieva, Emanuela E; Frank, Dominic D; Mansourian, Suzan; Suh, Greg S B; Gallio, Marco; Stensmyr, Marcus C

    2016-05-23

    Environmental humidity influences the fitness and geographic distribution of all animals [1]. Insects in particular use humidity cues to navigate the environment, and previous work suggests the existence of specific sensory mechanisms to detect favorable humidity ranges [2-5]. Yet, the molecular and cellular basis of humidity sensing (hygrosensation) remains poorly understood. Here we describe genes and neurons necessary for hygrosensation in the vinegar fly Drosophila melanogaster. We find that members of the Drosophila genus display species-specific humidity preferences related to conditions in their native habitats. Using a simple behavioral assay, we find that the ionotropic receptors IR40a, IR93a, and IR25a are all required for humidity preference in D. melanogaster. Yet, whereas IR40a is selectively required for hygrosensory responses, IR93a and IR25a mediate both humidity and temperature preference. Consistent with this, the expression of IR93a and IR25a includes thermosensory neurons of the arista. In contrast, IR40a is excluded from the arista but is expressed (and required) in specialized neurons innervating pore-less sensilla of the sacculus, a unique invagination of the third antennal segment. Indeed, calcium imaging showed that IR40a neurons directly respond to changes in humidity, and IR40a knockdown or IR93a mutation reduced their responses to stimuli. Taken together, our results suggest that the preference for a specific humidity range depends on specialized sacculus neurons, and that the processing of environmental humidity can happen largely in parallel to that of temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Use of Drosophila to study DNA repair

    International Nuclear Information System (INIS)

    Boyd, J.B.; Harris, P.V.; Sakaguchi, K.

    1988-01-01

    This paper discusses Drosophila, the premier metazoan organism for analyzing many fundamental features of eukaryotic gene regulation. The authors present adaptations of several approaches for studying DNA repair to an analysis of repair-defective mutants in Drosophila. A current understanding of Drosophila DNA repair is described

  5. An Investigation on the He−(1s2s2 2S Resonance in Debye Plasmas

    Directory of Open Access Journals (Sweden)

    Arijit Ghoshal

    2017-01-01

    Full Text Available The effect of Debye plasma on the 1 s 2 s 2 2 S resonance states in the scattering of electron from helium atom has been investigated within the framework of the stabilization method. The interactions among the charged particles in Debye plasma have been modelled by Debye–Huckel potential. The 1 s 2 s excited state of the helium atom has been treated as consisting of a H e + ionic core plus an electron moving around. The interaction between the core and the electron has then been modelled by a model potential. It has been found that the background plasma environment significantly affects the resonance states. To the best of our knowledge, such an investigation of 1 s 2 s 2 2 S resonance states of the electron–helium system embedded in Debye plasma environment is the first reported in the literature.

  6. Transcriptomic Response of Drosophila Melanogaster Pupae Developed in Hypergravity

    Science.gov (United States)

    Hosamani, Ravikumar; Hateley, Shannon; Bhardwaj, Shilpa R.; Pachter, Lior; Bhattacharya, Sharmila

    2016-01-01

    The metamorphosis of Drosophila is evolutionarily adapted to Earth's gravity, and is a tightly regulated process. Deviation from 1g to microgravity or hypergravity can influence metamorphosis, and alter associated gene expression. Understanding the relationship between an altered gravity environment and developmental processes is important for NASA's space travel goals. In the present study, 20 female and 20 male synchronized (Canton S, 2 to 3day old) flies were allowed to lay eggs while being maintained in a hypergravity environment (3g). Centrifugation was briefly stopped to discard the parent flies after 24hrs of egg laying, and then immediately continued until the eggs developed into P6-staged pupae (25 - 43 hours after pupation initiation). Post hypergravity exposure, P6-staged pupae were collected, total RNA was extracted using Qiagen RNeasy mini kits. We used RNA-Seq and qRT-PCR techniques to profile global transcriptomic changes in early pupae exposed to chronic hypergravity. During the pupal stage, Drosophila relies upon gravitational cues for proper development. Assessing gene expression changes in the pupa under altered gravity conditions helps highlight gravity dependent genetic pathways. A robust transcriptional response was observed in hypergravity-exposed pupae compared to controls, with 1,513 genes showing a significant (q Drosophila pupae in response to hypergravity.

  7. Modelling Cooperative Tumorigenesis in Drosophila

    Science.gov (United States)

    2018-01-01

    The development of human metastatic cancer is a multistep process, involving the acquisition of several genetic mutations, tumour heterogeneity, and interactions with the surrounding microenvironment. Due to the complexity of cancer development in mammals, simpler model organisms, such as the vinegar fly, Drosophila melanogaster, are being utilized to provide novel insights into the molecular mechanisms involved. In this review, we highlight recent advances in modelling tumorigenesis using the Drosophila model, focusing on the cooperation of oncogenes or tumour suppressors, and the interaction of mutant cells with the surrounding tissue in epithelial tumour initiation and progression. PMID:29693007

  8. AdS2 holographic dictionary

    International Nuclear Information System (INIS)

    Cvetič, Mirjam; Papadimitriou, Ioannis

    2016-01-01

    We construct the holographic dictionary for both running and constant dilaton solutions of the two dimensional Einstein-Maxwell-Dilaton theory that is obtained by a circle reduction from Einstein-Hilbert gravity with negative cosmological constant in three dimensions. This specific model ensures that the dual theory has a well defined ultraviolet completion in terms of a two dimensional conformal field theory, but our results apply qualitatively to a wider class of two dimensional dilaton gravity theories. For each type of solutions we perform holographic renormalization, compute the exact renormalized one-point functions in the presence of arbitrary sources, and derive the asymptotic symmetries and the corresponding conserved charges. In both cases we find that the scalar operator dual to the dilaton plays a crucial role in the description of the dynamics. Its source gives rise to a matter conformal anomaly for the running dilaton solutions, while its expectation value is the only non trivial observable for constant dilaton solutions. The role of this operator has been largely overlooked in the literature. We further show that the only non trivial conserved charges for running dilaton solutions are the mass and the electric charge, while for constant dilaton solutions only the electric charge is non zero. However, by uplifting the solutions to three dimensions we show that constant dilaton solutions can support non trivial extended symmetry algebras, including the one found by Compère, Song and Strominger http://dx.doi.org/10.1007/JHEP05(2013)152, in agreement with the results of Castro and Song http://arxiv.org/abs/1411.1948. Finally, we demonstrate that any solution of this specific dilaton gravity model can be uplifted to a family of asymptotically AdS 2 ×S 2 or conformally AdS 2 ×S 2 solutions of the STU model in four dimensions, including non extremal black holes. The four dimensional solutions obtained by uplifting the running dilaton solutions coincide

  9. -MoS2 Lateral Heterojunctions

    KAUST Repository

    Li, Ming-yang

    2018-02-28

    2D layered heterostructures have attracted intensive interests due to their unique optical, transport, and interfacial properties. The laterally stitched heterojunction based on dissimilar 2D transition metal dichalcogenides forms an intrinsic p–n junction without the necessity of applying an external voltage. However, no scalable processes are reported to construct the devices with such lateral heterostructures. Here, a scalable strategy, two-step and location-selective chemical vapor deposition, is reported to synthesize self-aligned WSe2–MoS2 monolayer lateral heterojunction arrays and demonstrates their light-emitting devices. The proposed fabrication process enables the growth of high-quality interfaces and the first successful observation of electroluminescence at the WSe2–MoS2 lateral heterojunction. The electroluminescence study has confirmed the type-I alignment at the interface rather than commonly believed type-II alignment. This self-aligned growth process paves the way for constructing various 2D lateral heterostructures in a scalable manner, practically important for integrated 2D circuit applications.

  10. Doble aneuploidía en un niño Colombiano: síndrome de Down–Klinefelter, con fenotipo de síndrome de Down = Double aneuploidy in a Colombian child: Down-Klinefelter syndrome with Down syndrome phenotype

    OpenAIRE

    Pachajoa Londoño, Harry; Perilla Duque, Diana; Isaza de Lourido, Carolina

    2011-01-01

    La ocurrencia de una doble aneuploidía en una misma persona es un evento relativamente raro. Se presenta el caso de un niño de siete meses de edad, de padres no consanguíneos con características clínicas de síndrome de Down y cariotipo 48XXY.

  11. Doble aneuploidía en un niño Colombiano: síndrome de Down–Klinefelter, con fenotipo de síndrome de Down = Double aneuploidy in a Colombian child: Down-Klinefelter syndrome with Down syndrome phenotype

    Directory of Open Access Journals (Sweden)

    Pachajoa Londoño, Harry

    2011-03-01

    Full Text Available La ocurrencia de una doble aneuploidía en una misma persona es un evento relativamente raro. Se presenta el caso de un niño de siete meses de edad, de padres no consanguíneos con características clínicas de síndrome de Down y cariotipo 48XXY.

  12. Luminescence of ions with s2 configuration

    International Nuclear Information System (INIS)

    Steen, A. van der.

    1980-01-01

    Some Bi 3+ -activated oxidic compounds show a red luminescence (e.g. BaSO 4 -Bi 3+ and Ca 2 P 2 O 7 -Bi 3+ ); others show an ultraviolet emission (e.g. LaGaO 3 -Bi 3+ and Ln 2 SO 6 -Bi 3+ (Ln=Y, La, Lu)). This thesis investigates which factors are responsible for these large differences in the position of the emission bands, which factors determine the occurrence of vibrational structure in the luminescence spectra of an s 2 ion and what the influence of the non-radiative processes in the 3 P multiplet is on the luminescence characteristics of the luminescent materials. (Auth.)

  13. Semi-automated quantitative Drosophila wings measurements.

    Science.gov (United States)

    Loh, Sheng Yang Michael; Ogawa, Yoshitaka; Kawana, Sara; Tamura, Koichiro; Lee, Hwee Kuan

    2017-06-28

    Drosophila melanogaster is an important organism used in many fields of biological research such as genetics and developmental biology. Drosophila wings have been widely used to study the genetics of development, morphometrics and evolution. Therefore there is much interest in quantifying wing structures of Drosophila. Advancement in technology has increased the ease in which images of Drosophila can be acquired. However such studies have been limited by the slow and tedious process of acquiring phenotypic data. We have developed a system that automatically detects and measures key points and vein segments on a Drosophila wing. Key points are detected by performing image transformations and template matching on Drosophila wing images while vein segments are detected using an Active Contour algorithm. The accuracy of our key point detection was compared against key point annotations of users. We also performed key point detection using different training data sets of Drosophila wing images. We compared our software with an existing automated image analysis system for Drosophila wings and showed that our system performs better than the state of the art. Vein segments were manually measured and compared against the measurements obtained from our system. Our system was able to detect specific key points and vein segments from Drosophila wing images with high accuracy.

  14. Kinetic response of a Drosophila melanogaster cell line to different medium formulations and culture conditions

    OpenAIRE

    Bovo, R.; Galesi, A. L. L; Jorge, S. A. C.; Piccoli, R. A. M.; Moraes, A. M.; Pereira, C. A.; Augusto, E. F. P.

    2008-01-01

    In the past few years, Drosophila melanogaster cells have been employed for recombinant protein production purposes, and a comprehensive knowledge of their metabolism is essential for process optimization. In this work, the kinetic response of a Schneider S2 cell line, grown in shake flasks, in two different culture media, the serum-free SF900-II® and the serum-supplemented TC-100, was evaluated. Cell growth, amino acids and glucose uptake, and lactate synthesis were measured allowing the cal...

  15. A Drosophila wing spot test

    International Nuclear Information System (INIS)

    Ayaki, Toshikazu; Yoshikawa, Isao; Niikawa, Norio; Hoshi, Masaharu.

    1986-01-01

    A Drosophila wing spot test system was used to investigate the effects of low doses of X-rays, gamma rays, and both 2.3 and 14.1 MeV neutrons on somatic chromosome mutation (SCM) induction. The incidence of SCM was significantly increased with any type of radiation, with evident linear dose-response relationship within the range of 3 to 20 cGy. It was estimated that relative biological effectiveness value for SCM induction of 2.3 MeV neutrons to X-rays and gamma rays is much higher than that of 14.1 MeV neutrons to those photons (2.4 vs 8.0). The Drosophila wing spot test system seems to become a promising in vivo experimental method for higher animals in terms of the lack of necessity for a marvelously large number of materials required in conventional test system. (Namekawa, K.)

  16. Limited taste discrimination in Drosophila.

    Science.gov (United States)

    Masek, Pavel; Scott, Kristin

    2010-08-17

    In the gustatory systems of mammals and flies, different populations of sensory cells recognize different taste modalities, such that there are cells that respond selectively to sugars and others to bitter compounds. This organization readily allows animals to distinguish compounds of different modalities but may limit the ability to distinguish compounds within one taste modality. Here, we developed a behavioral paradigm in Drosophila melanogaster to evaluate directly the tastes that a fly distinguishes. These studies reveal that flies do not discriminate among different sugars, or among different bitter compounds, based on chemical identity. Instead, flies show a limited ability to distinguish compounds within a modality based on intensity or palatability. Taste associative learning, similar to olfactory learning, requires the mushroom bodies, suggesting fundamental similarities in brain mechanisms underlying behavioral plasticity. Overall, these studies provide insight into the discriminative capacity of the Drosophila gustatory system and the modulation of taste behavior.

  17. Studies on Drosophila radiosensitive strains

    International Nuclear Information System (INIS)

    Varentsova, E.P.; Zakharov, I.A.

    1976-01-01

    45 of radiosensitive strains of Drosophila melanogaster were isolated by Curly/Lobe technique after EMS treatment of Livadia population males. The lethality of non-Curly late larvae after gamma-irradiation (4000r) characterized radiosensitivity strains. Most of them exhibited higher frequency of the spontaneous dominant lethals (up to 69%). The males of 6 strains were semi-sterile. 5 of these strains exhibited higher frequency of X-chromosome non-disjunction

  18. Drosophila: Retrotransposons Making up Telomeres.

    Science.gov (United States)

    Casacuberta, Elena

    2017-07-19

    Drosophila and extant species are the best-studied telomerase exception. In this organism, telomere elongation is coupled with targeted retrotransposition of Healing Transposon (HeT-A) and Telomere Associated Retrotransposon (TART) with sporadic additions of Telomere Associated and HeT-A Related (TAHRE), all three specialized non-Long Terminal Repeat (non-LTR) retrotransposons. These three very special retroelements transpose in head to tail arrays, always in the same orientation at the end of the chromosomes but never in interior locations. Apparently, retrotransposon and telomerase telomeres might seem very different, but a detailed view of their mechanisms reveals similarities explaining how the loss of telomerase in a Drosophila ancestor could successfully have been replaced by the telomere retrotransposons. In this review, we will discover that although HeT-A, TART, and TAHRE are still the only examples to date where their targeted transposition is perfectly tamed into the telomere biology of Drosophila, there are other examples of retrotransposons that manage to successfully integrate inside and at the end of telomeres. Because the aim of this special issue is viral integration at telomeres, understanding the base of the telomerase exceptions will help to obtain clues on similar strategies that mobile elements and viruses could have acquired in order to ensure their survival in the host genome.

  19. Insulin receptor in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Petruzzelli, L.; Herrera, R.; Rosen, O.

    1986-01-01

    A specific, high affinity insulin receptor is present in both adult Drosophila and in Drosophila embryos. Wheat germ lectin-enriched extracts of detergent-solubilized membranes from embryos and adults bind insulin with a K/sub d/ of 15 nM. Binding is specific for insulin; micromolar concentrations of proinsulin, IGFI, and IGFII are required to displace bound 125 I-insulin. Insulin-dependent protein tyrosine kinase activity appears during embryogenesis. It is evident between 6 and 12 hours of development, peaks between 12 and 18 hours and falls in the adult. During 0-6 hours of embryogenesis, and in the adult, a specific protein band (Mr = 135,000) is crosslinked to 125 I-insulin. During 6-12 and 12-18 hours of embryogenesis stages in which insulin-dependent protein tyrosine kinase is high, an additional band (Mr = 100,000) becomes crosslinked to 125 I-insulin. Isolation and DNA sequence analysis of genomic clones encoding the Drosophila insulin receptor will be presented as will the characterization of insulin receptor mRNA's during development

  20. 'Peer pressure' in larval Drosophila?

    Science.gov (United States)

    Niewalda, Thomas; Jeske, Ines; Michels, Birgit; Gerber, Bertram

    2014-06-06

    Understanding social behaviour requires a study case that is simple enough to be tractable, yet complex enough to remain interesting. Do larval Drosophila meet these requirements? In a broad sense, this question can refer to effects of the mere presence of other larvae on the behaviour of a target individual. Here we focused in a more strict sense on 'peer pressure', that is on the question of whether the behaviour of a target individual larva is affected by what a surrounding group of larvae is doing. We found that innate olfactory preference of a target individual was neither affected (i) by the level of innate olfactory preference in the surrounding group nor (ii) by the expression of learned olfactory preference in the group. Likewise, learned olfactory preference of a target individual was neither affected (iii) by the level of innate olfactory preference of the surrounding group nor (iv) by the learned olfactory preference the group was expressing. We conclude that larval Drosophila thus do not take note of specifically what surrounding larvae are doing. This implies that in a strict sense, and to the extent tested, there is no social interaction between larvae. These results validate widely used en mass approaches to the behaviour of larval Drosophila. © 2014. Published by The Company of Biologists Ltd.

  1. Quantification of Drosophila Grooming Behavior.

    Science.gov (United States)

    Barradale, Francesca; Sinha, Kairav; Lebestky, Tim

    2017-07-19

    Drosophila grooming behavior is a complex multi-step locomotor program that requires coordinated movement of both forelegs and hindlegs. Here we present a grooming assay protocol and novel chamber design that is cost-efficient and scalable for either small or large-scale studies of Drosophila grooming. Flies are dusted all over their body with Brilliant Yellow dye and given time to remove the dye from their bodies within the chamber. Flies are then deposited in a set volume of ethanol to solubilize the dye. The relative spectral absorbance of dye-ethanol samples for groomed versus ungroomed animals are measured and recorded. The protocol yields quantitative data of dye accumulation for individual flies, which can be easily averaged and compared across samples. This allows experimental designs to easily evaluate grooming ability for mutant animal studies or circuit manipulations. This efficient procedure is both versatile and scalable. We show work-flow of the protocol and comparative data between WT animals and mutant animals for the Drosophila type I Dopamine Receptor (DopR).

  2. Radioresistance and radiosensitivity in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Reguly, M.L.

    1983-01-01

    Studying the mechanisms controlling radioresistant in Drosophila the sensibility of four strains of Drosophila melanogaster to sex-linked recessive lethal mutations induced by 5kR Cobalt-60 gamma radiation and 0,006 M EMS or 0,25% of caffeine was determined. (M.A.C.) [pt

  3. Size control in development: lessons from Drosophila

    Indian Academy of Sciences (India)

    which mediates dosage compensation in Drosophila; Mol. Cell 4 117–122. Kelley R L, Meller V H, Gordadze P R, Roman G, Davis R L and Kuroda M I 1999 Epigenetic spreading of the Drosophila dosage compensation complex from rox RNA genes into flanking chromatin; Cell 98. 513–522. Lucchesi J C 1998 Dosage ...

  4. AdS2 models in an embedding superspace

    International Nuclear Information System (INIS)

    McKeon, D.G.C.; Sherry, T.N.

    2003-01-01

    An embedding superspace, whose bosonic part is the flat (2+1)-dimensional embedding space for AdS 2 , is introduced. Superfields and several supersymmetric models are examined in the embedded AdS 2 superspace

  5. Excitation energies and oscillator strengths for the 1s2 2s2 3d 2D e ...

    Indian Academy of Sciences (India)

    involving electronic transitions induced by energetic radiation [15]. Tiwary [16] calculated the excitation energies and oscillator strengths, of both the length ( fL) and velocity ( fV) forms, for the inner-shell excitation 1s2 2s2 2p6 3s2 3p6. 3d 2De → 1s2 2s2 2p6 3s2 3p5 3d2 2Po, 2Do, 2Fo transitions using the configuration in-.

  6. Electron microscopy studies on MoS2 nanocrystals

    DEFF Research Database (Denmark)

    Hansen, Lars Pilsgaard

    Industrial-style MoS2-based hydrotreating catalysts are studied using electron microscopy. The MoS2 nanostructures are imaged with single-atom sensitivity to reveal the catalytically important edge structures. Furthermore, the in-situ formation of MoS2 crystals is imaged for the first time....

  7. Adaptive genic evolution in the Drosophila genomes

    DEFF Research Database (Denmark)

    Shapiro, Joshua A; Huang, Wei; Zhang, Chenhui

    2007-01-01

    and stable population. In this study, we sequenced 419 genes from 24 lines of Drosophila melanogaster and its close relatives. Together with data from Drosophila simulans, these data reveal the following. (i) Approximately 10% of the loci in regions of normal recombination are much less polymorphic at silent...... sites than expected, hinting at the action of selective sweeps. (ii) The level of polymorphism is negatively correlated with the rate of nonsynonymous divergence across loci. Thus, even under strict neutrality, the ratio of amino acid to silent nucleotide changes (A:S) between Drosophila species...

  8. Detection of cell death in Drosophila.

    Science.gov (United States)

    McCall, Kimberly; Peterson, Jeanne S; Pritchett, Tracy L

    2009-01-01

    Drosophila is a powerful model system for the identification of cell death genes and understanding the role of cell death in development. In this chapter, we describe three methods typically used for the detection of cell death in Drosophila. The TUNEL and acridine orange methods are used to detect dead or dying cells in a variety of tissues. We focus on methods for the embryo and the ovary, but these techniques can be used on other tissues as well. The third method is the detection of genetic interactions by expressing cell death genes in the Drosophila eye.

  9. Three-dimensional hierarchical MoS2/CoS2 heterostructure arrays for highly efficient electrocatalytic hydrogen evolution

    Directory of Open Access Journals (Sweden)

    Canbin Ouyang

    2017-04-01

    Full Text Available Developing non-expensive, highly active and highly stable electrocatalysts for hydrogen evolution has aroused extensive attention, owing to the necessity of novel clean and sustainable energy carriers. In this paper, we report a synthesis of free-standing three-dimensional hierarchical MoS2/CoS2 heterostructure arrays through a convenient process. The investigation of electrocatalytic HER performance suggests that the MoS2/CoS2 hybrid catalyst exhibits significant enhancement in HER (onsetpotential and potential at a current density of 100 mA cm−2 are 20 mV and 125 mV, respectively and superior durability (no shift of current density is observed after a continuous scanning of 3000 times compared with individual CoS2 and MoS2. The superior HER performance was attributed to the formation of the interface between CoS2 and MoS2 through the electrochemical characterization, Raman, XPS analysis, and the control experiment. The lower onsetpotential, higher current density, excellent durability, and the free-standing structure of the three-dimensional hierarchical MoS2/CoS2 heterostructure array make it a promising cathode catalyst suitable for widespread application. Keywords: MoS2/CoS2, Heterostructure array, Free-standing, Hydrogen evolution reaction

  10. Studies on Drosophila radiosensitivity strains

    International Nuclear Information System (INIS)

    Varentsova, E.R.; Sharygin, V.I.; Khromykh, Yu.U.

    1985-01-01

    Fertility of radiosensitive mutant drosophila female strain rad (2) 201 61 after irradiation and frequency of dominant lethal mutations (DLM), induced by γ-radiation for 0-5 h and 5-7 days, are investigated. It is shown, that oocytes of the mutant strain are more radiosensitive as compared with cells of mongrel flies as to criterion of DLM appearance over the period of maturing. Early oocytes of stages 2-7 are the most sensitive, i.e. at the stages, corresponding to the manifestation of previously established recombination-defective properties of mutations rad (2) 201 61 . It is also sown, that doses of γ-rays, exceeding 10 Gy produce a strong sterilizing effect on mutant females due to destruction and resorption of egg chambers, irradiated at the stages of previtellogenetic growth of oocytes. In females, carrying mutation of radiosensitivity there is no direct correlation betwen sensitivity of oocytes proper to DLM induction and sensitivity of egg folleicles to resorbing effect of γ-rays. The ways of possible involvement of mutant locus studied into genetic processes in various specialized cells of drosophila

  11. Differentiation of Drosophila glial cells.

    Science.gov (United States)

    Sasse, Sofia; Neuert, Helen; Klämbt, Christian

    2015-01-01

    Glial cells are important constituents of the nervous system and a hallmark of these cells are their pronounced migratory abilities. In Drosophila, glial lineages have been well described and some of the molecular mechanisms necessary to guide migrating glial cells to their final target sites have been identified. With the onset of migration, glial cells are already specified into one of five main glial cell types. The perineurial and subperineurial glial cells are eventually located at the outer surface of the Drosophila nervous system and constitute the blood-brain barrier. The cortex glial cells ensheath all neuroblasts and their progeny and reside within the central nervous system. Astrocyte-like cells invade the neuropil to control synaptic function and ensheathing glial cells encase the entire neuropil. Within the peripheral nervous system, wrapping glial cells ensheath individual axons or axon fascicles. Here, we summarize the current knowledge on how differentiation of glial cells into the specific subtypes is orchestrated. Furthermore, we discuss sequencing data that will facilitate further analyses of glial differentiation in the fly nervous system. © 2015 Wiley Periodicals, Inc.

  12. Life span extension and neuronal cell protection by Drosophila nicotinamidase.

    Science.gov (United States)

    Balan, Vitaly; Miller, Gregory S; Kaplun, Ludmila; Balan, Karina; Chong, Zhao-Zhong; Li, Faqi; Kaplun, Alexander; VanBerkum, Mark F A; Arking, Robert; Freeman, D Carl; Maiese, Kenneth; Tzivion, Guri

    2008-10-10

    The life span of model organisms can be modulated by environmental conditions that influence cellular metabolism, oxidation, or DNA integrity. The yeast nicotinamidase gene pnc1 was identified as a key transcriptional target and mediator of calorie restriction and stress-induced life span extension. PNC1 is thought to exert its effect on yeast life span by modulating cellular nicotinamide and NAD levels, resulting in increased activity of Sir2 family class III histone deacetylases. In Caenorhabditis elegans, knockdown of a pnc1 homolog was shown recently to shorten the worm life span, whereas its overexpression increased survival under conditions of oxidative stress. The function and regulation of nicotinamidases in higher organisms has not been determined. Here, we report the identification and biochemical characterization of the Drosophila nicotinamidase, D-NAAM, and demonstrate that its overexpression significantly increases median and maximal fly life span. The life span extension was reversed in Sir2 mutant flies, suggesting Sir2 dependence. Testing for physiological effectors of D-NAAM in Drosophila S2 cells, we identified oxidative stress as a primary regulator, both at the transcription level and protein activity. In contrast to the yeast model, stress factors such as high osmolarity and heat shock, calorie restriction, or inhibitors of TOR and phosphatidylinositol 3-kinase pathways do not appear to regulate D-NAAM in S2 cells. Interestingly, the expression of D-NAAM in human neuronal cells conferred protection from oxidative stress-induced cell death in a sirtuin-dependent manner. Together, our findings establish a life span extending the ability of nicotinamidase in flies and offer a role for nicotinamide-modulating genes in oxidative stress regulated pathways influencing longevity and neuronal cell survival.

  13. Functional Analysis of Drosophila NF1

    National Research Council Canada - National Science Library

    Bernards, Andre

    2005-01-01

    ...) for Ras, yet homozygous loss of a highly conserved Drosophila NF1 ortholog results in several phenotypes that are insensitive to manipulating Ras signal transduction, but rescued by increasing...

  14. Drosophila melanogaster gene expression changes after spaceflight.

    Data.gov (United States)

    National Aeronautics and Space Administration — Gene expression levels were determined in 3rd instar and adult Drosophila melanogaster reared during spaceflight to elucidate the genetic and molecular mechanisms...

  15. Modeling tumor invasion and metastasis in Drosophila

    Directory of Open Access Journals (Sweden)

    Wayne O. Miles

    2011-11-01

    Full Text Available Conservation of major signaling pathways between humans and flies has made Drosophila a useful model organism for cancer research. Our understanding of the mechanisms regulating cell growth, differentiation and development has been considerably advanced by studies in Drosophila. Several recent high profile studies have examined the processes constraining the metastatic growth of tumor cells in fruit fly models. Cell invasion can be studied in the context of an in vivo setting in flies, enabling the genetic requirements of the microenvironment of tumor cells undergoing metastasis to be analyzed. This Perspective discusses the strengths and limitations of Drosophila models of cancer invasion and the unique tools that have enabled these studies. It also highlights several recent reports that together make a strong case for Drosophila as a system with the potential for both testing novel concepts in tumor progression and cell invasion, and for uncovering players in metastasis.

  16. BM2(reinverted) of Drosophila melanogaster is

    Indian Academy of Sciences (India)

    -chromosome (Lucchesi et al. 2005). Dosage compensation and the phenomenon of. Keywords. dosage compensation; histone acetylation; chromatin remodelling; H4K16; MOF; Drosophila. Journal of Genetics, Vol. 87, No. 3, December 2008.

  17. The Drosophila bipectinata species complex: phylogenetic ...

    Indian Academy of Sciences (India)

    PARUL BANERJEE

    c Indian Academy of Sciences. RESEARCH ARTICLE. The Drosophila bipectinata species complex: phylogenetic relationship among different members based on chromosomal variations. PARUL BANERJEE and BASHISTH N. SINGH. ∗. Genetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi ...

  18. Ecdysteroid receptors in Drosophila melanogaster adult females

    Science.gov (United States)

    Ecdysteroid receptors were identified and partially characterized from total cell extracts of whole animals and dissected tissues from Drosophila melanogaster adult females. Binding studies indicated the presence of two ecdysteroid binding components having high affinity and specificity consistent w...

  19. On the Morphology of the Drosophila Heart

    Directory of Open Access Journals (Sweden)

    Barbara Rotstein

    2016-04-01

    Full Text Available The circulatory system of Drosophila melanogaster represents an easily amenable genetic model whose analysis at different levels, i.e., from single molecules up to functional anatomy, has provided new insights into general aspects of cardiogenesis, heart physiology and cardiac aging, to name a few examples. In recent years, the Drosophila heart has also attracted the attention of researchers in the field of biomedicine. This development is mainly due to the fact that several genes causing human heart disease are also present in Drosophila, where they play the same or similar roles in heart development, maintenance or physiology as their respective counterparts in humans. This review will attempt to briefly introduce the anatomy of the Drosophila circulatory system and then focus on the different cell types and non-cellular tissue that constitute the heart.

  20. Gold nanoparticles on MoS2 layered crystal flakes

    International Nuclear Information System (INIS)

    Cao, Wei; Pankratov, Vladimir; Huttula, Marko; Shi, Xinying; Saukko, Sami; Huang, Zhongjia; Zhang, Meng

    2015-01-01

    Inorganic layered crystal MoS 2 is considered as one of the most promising and efficient semiconductor materials for future transistors, photoelectronics, and electrocatalysis. To boost MoS 2 -based material applications, one direction is to grow physically and chemically reactive nanoparticles onto MoS 2 . Here we report on a simple route to synthesis crystalized MoS 2 –Au complexes. The gold nanoparticles were grown on MoS 2 flakes through a wet method in the oxygen free environment at room temperature. Nanoparticles with diameters varying from 9 nm to 429 nm were controlled by the molar ratios of MoS 2 and HAuCl 4 precursors. MoS 2 host flakes keep intrinsic honeycomb layered structures and the Au nanoparticles cubic-center crystal microstructures. From product chemical states analysis, the synthesis was found driven by redox reactions between the sulphide and the chloroauric acid. Photoluminescence measurement showed that introducing Au nanoparticles onto MoS 2 stacks substantially prompted excitonic transitions of stacks, as an analogy for doping Si wafers with dopants. Such composites may have potential applications in wide ranges similar as the doped Si. - Highlights: • The Au nanoparticles were decorated on MoS 2 in oxygen free ambiences via a wet method. • The Au nanoparticles are size-controllable and crystalized. • Chemical reaction scheme was clarified. • The MoS 2 –Au complexes have strong photoluminescent properties

  1. Die induzierbare antivirale Immunantwort von Drosophila melanogaster

    OpenAIRE

    Kemp, Cordula

    2010-01-01

    In der vorliegenden Arbeit wurde Drosophila melanogaster als Modell ge- nutzt, um die angeborene Immunantwort gegen virale Infektionen zu studie- ren. Wir untersuchten mit Hilfe von genomweiten microarrays das Transkriptom von Fliegen, welche entweder mit dem Drosophila C Virus (DCV), dem Flock- house Virus (FHV) oder dem Sindbis Virus (SINV) infiziert waren. Infektion mit diesen drei positiv orientierten Einzelstrang RNS Viren führte zu einer starken transkriptionellen Antwort, welche deutlic...

  2. Mapping of gene mutations in drosophila melanogaster

    OpenAIRE

    Halvorsen, Charlotte Marie

    2004-01-01

    In this experiment, mutant genes of a given unknown mutant strain of Drosophila melanogaster were mapped to specific chromosomes. Drosophila melanogaster, commonly known as the fruit fly, was the appropriate choice for the organism to use in this specific experiment because of its relatively rapid life cycle of 10-14 days and because of the small amount of space and food neccessary for maintaining thousands of flies. The D. Melanogaster unknown strain specifically used in this experiment wa...

  3. A Drosophila Model for Screening Antiobesity Agents

    Directory of Open Access Journals (Sweden)

    Tran Thanh Men

    2016-01-01

    Full Text Available Although triacylglycerol, the major component for lipid storage, is essential for normal physiology, its excessive accumulation causes obesity in adipose tissue and is associated with organ dysfunction in nonadipose tissue. Here, we focused on the Drosophila model to develop therapeutics for preventing obesity. The brummer (bmm gene in Drosophila melanogaster is known to be homologous with human adipocyte triglyceride lipase, which is related to the regulation of lipid storage. We established a Drosophila model for monitoring bmm expression by introducing the green fluorescent protein (GFP gene as a downstream reporter of the bmm promoter. The third-instar larvae of Drosophila showed the GFP signal in all tissues observed and specifically in the salivary gland nucleus. To confirm the relationship between bmm expression and obesity, the effect of oral administration of glucose diets on bmm promoter activity was analyzed. The Drosophila flies given high-glucose diets showed higher lipid contents, indicating the obesity phenotype; this was suggested by a weaker intensity of the GFP signal as well as reduced bmm mRNA expression. These results demonstrated that the transgenic Drosophila model established in this study is useful for screening antiobesity agents. We also report the effects of oral administration of histone deacetylase inhibitors and some vegetables on the bmm promoter activity.

  4. Characterization of Autophagic Responses in Drosophila melanogaster.

    Science.gov (United States)

    Xu, T; Kumar, S; Denton, D

    2017-01-01

    Drosophila is an excellent model system for studying autophagy during animal development due to the availability of genetic reagents and opportunity for in vivo cell biological analysis. The regulation and mechanism of autophagy are highly evolutionarily conserved and the role of autophagy has been characterized during various stages of Drosophila development as well as following starvation. Studies in Drosophila have revealed novel insights into the role of distinct components of the autophagy machinery. This chapter describes protocols for examining autophagy during Drosophila development. A crucial step in the induction of autophagy is the incorporation of Atg8a into the autophagosome. This can be measured as autophagic puncta using live fluorescent imaging, immunostaining, or immunoblot analysis of LC3/Atg8a processing. The level of autophagy can also be examined using other specific components of the autophagy pathway as markers detected by immunofluorescent imaging. Based on the distinct morphology of autophagy, it can also be examined by transmission electron microscopy. In addition, one of the advantages of using Drosophila as a model is the ability to undertake genetic analysis of individual components of the autophagy machinery. Current approaches that can be used to monitor autophagy, including the overall flux and individual steps in Drosophila melanogaster, will be discussed. © 2017 Elsevier Inc. All rights reserved.

  5. New record for the invasive Spotted Wing Drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae) in Anillaco, Argentina

    Science.gov (United States)

    The invasive Spotted Wing Drosophila (SWD), Drosophila suzukii Matsumura, is reported for the first time in La Rioja, Argentina. This represents a major range expansion for this species. The natural enemies of SWD, Leptopilina clavipes and Ganaspis hookeri were also collected with the SWD at the s...

  6. Effect of non-nutritive sugars to decrease the survivorship of spotted wing drosophila, Drosophila suzukii

    Science.gov (United States)

    In this study, we investigated the effects of non-nutritive sugars and sugar alcohols on the survivorship of spotted wing drosophila, Drosophila suzukii, and found erythritol and erythrose as potentially toxic to the fly. In a dose-dependent study, erythritol and erythrose significantly reduced fly ...

  7. Identification of four Drosophila allatostatins as the cognate ligands for the Drosophila orphan receptor DAR-2

    DEFF Research Database (Denmark)

    Lenz, C; Williamson, M; Hansen, G N

    2001-01-01

    to be the receptor for an intrinsic Drosophila A-type (cockroach-type) allatostatin. Here, we have permanently expressed DAR-2 in CHO cells and found that it is the cognate receptor for four Drosophila A-type allatostatins, the drostatins-A1 to -A4. Of all the drostatins, drostatin-A4 (Thr...

  8. Folded MoS2 layers with reduced interlayer coupling

    OpenAIRE

    Castellanos-Gomez, Andres; van der Zant, Herre S. J.; Steele, Gary A.

    2013-01-01

    We study molybdenum disulfide (MoS2) structures generated by folding single- and bilayer MoS2 flakes. We find that this modified layer stacking leads to a decrease in the interlayer coupling and an enhancement of the photoluminescence emission yield. We additionally find that folded single-layer MoS2 structures show a contribution to photoluminescence spectra of both neutral and charged excitons, which is a characteristic feature of single-layer MoS2 that has not been observed in multilayer M...

  9. Identification of four Drosophila allatostatins as the cognate ligands for the Drosophila orphan receptor DAR-2

    DEFF Research Database (Denmark)

    Lenz, C; Williamson, M; Hansen, G N

    2001-01-01

    The allatostatins are generally inhibitory insect neuropeptides. The Drosophila orphan receptor DAR-2 is a G-protein-coupled receptor, having 47% amino acid residue identity with another Drosophila receptor, DAR-1 (which is also called dros. GPCR, or DGR) that was previously shown...... to be the receptor for an intrinsic Drosophila A-type (cockroach-type) allatostatin. Here, we have permanently expressed DAR-2 in CHO cells and found that it is the cognate receptor for four Drosophila A-type allatostatins, the drostatins-A1 to -A4. Of all the drostatins, drostatin-A4 (Thr...... weakly in the brain. The Drosophila larval gut also contains about 20-30 endocrine cells, expressing the gene for the drostatins-A1 to -A4. We suggest, therefore, that DAR-2 mediates an allatostatin (drostatin)-induced inhibition of gut motility. This is the first report on the permanent and functional...

  10. Molecular neurobiology of Drosophila taste.

    Science.gov (United States)

    Freeman, Erica Gene; Dahanukar, Anupama

    2015-10-01

    Drosophila is a powerful model in which to study the molecular and cellular basis of taste coding. Flies sense tastants via populations of taste neurons that are activated by compounds of distinct categories. The past few years have borne witness to studies that define the properties of taste neurons, identifying functionally distinct classes of sweet and bitter taste neurons that express unique subsets of gustatory receptor (Gr) genes, as well as water, salt, and pheromone sensing neurons that express members of the pickpocket (ppk) or ionotropic receptor (Ir) families. There has also been significant progress in terms of understanding how tastant information is processed and conveyed to higher brain centers, and modulated by prior dietary experience or starvation. Copyright © 2015. Published by Elsevier Ltd.

  11. Gustatory Processing in Drosophila melanogaster.

    Science.gov (United States)

    Scott, Kristin

    2018-01-07

    The ability to identify nutrient-rich food and avoid toxic substances is essential for an animal's survival. Although olfaction and vision contribute to food detection, the gustatory system acts as a final checkpoint control for food acceptance or rejection. The vinegar fly Drosophila melanogaster tastes many of the same stimuli as mammals and provides an excellent model system for comparative studies of taste detection. The relative simplicity of the fly brain and behaviors, along with the molecular genetic and functional approaches available in this system, allow the examination of gustatory neural circuits from sensory input to motor output. This review discusses the molecules and cells that detect taste compounds in the periphery and the circuits that process taste information in the brain. These studies are providing insight into how the detection of taste compounds regulates feeding decisions.

  12. Applications of subseasonal-to-seasonal (S2S) predictions

    Science.gov (United States)

    White, Christopher; Lamb, Rob; Carlsen, Henrik; Robertson, Andrew; Klein, Richard; Lazo, Jeffrey; Kumar, Arun; Vitart, Frederic; Coughlan de Perez, Erin; Ray, Andrea; Murray, Virginia; Graham, Richard; Buontempo, Carlo

    2017-04-01

    While long-range seasonal outlooks have been operational for many years, until recently the extended-range timescale - referred to as 'subseasonal-to-seasonal' (S2S) and which sits between the medium- to long-range forecasting timescales - has received relatively little attention. The S2S timescale has long been seen as a 'predictability desert', yet a new generation of S2S predictions are starting to bridge the gap between weather forecasts and longer-range prediction. Decisions in a range of sectors are made in this extended-range lead time, therefore there is a strong demand for this new generation of predictions. At least ten international weather centres now have some capability for issuing experimental or operational S2S predictions, including the European Centre for Medium-Range Weather Forecasting (ECMWF) and the National Oceanic and Atmospheric Administration (NOAA) that now have operational S2S outputs. International efforts are now underway to identify key sources of predictability, improve forecast skill and operationalise aspects of S2S forecasts, however challenges remain in advancing this new frontier. If S2S predictions are to be utilised effectively, it is important that along with science advances, we learn how to develop, communicate and apply these forecasts appropriately. In this study, we present the potential of the emerging operational S2S forecasts to the wider weather and climate applications community by undertaking the first comprehensive review of sectoral applications of S2S predictions, including public health, disaster preparedness, water management, energy and agriculture. We explore the value of applications-relevant S2S predictions, and highlight the opportunities and challenges facing their uptake. We show how social sciences can be integrated with S2S development - from communication to decision-making and valuation of forecasts - to enhance the benefits of 'climate services' approaches for extended-range forecasting. We

  13. The Global Mode-1 S2 Internal Tide

    Science.gov (United States)

    Zhao, Zhongxiang

    2017-11-01

    The global mode-1 S2 internal tide is observed using sea surface height (SSH) measurements from four satellite altimeters: TOPEX/Poseidon, Jason-1, Jason-2, and Geosat Follow-On. Plane wave analysis is employed to extract three mode-1 S2 internal tidal waves in any given 250 km by 250 km window, which are temporally coherent over a 20 year period from 1992 to 2012. Depth-integrated energy and flux of the S2 internal tide are calculated from the SSH amplitude and a conversion function built from climatological hydrographic profiles in the World Ocean Atlas 2013. The results show that the S2 and M2 internal tides have similar spatial patterns. Both S2 and M2 internal tides originate at major topographic features and propagate over long distances. The S2 internal tidal beams are generally shorter, likely because the relatively weaker S2 internal tide is easily overwhelmed by nontidal noise. The northbound S2 and M2 internal tides from the Hawaiian Ridge are observed to travel over 3500 km across the Northeast Pacific. The globally integrated energy of the mode-1 S2 internal tide is 7.8 PJ (1 PJ = 1015 J), about 20% that of M2 (36.4 PJ). The histogram of S2 to M2 SSH ratios peaks at 0.4, consistent with the square root of their energy ratio. In terms of SSH, S2 is greater than M2 in ≈10% of the global ocean and ≥50% of M2 in about half of the global ocean.

  14. Single Nucleotide Polymorphism Markers for Genetic Mapping in Drosophila melanogaster

    OpenAIRE

    Hoskins, Roger A.; Phan, Alexander C.; Naeemuddin, Mohammed; Mapa, Felipa A.; Ruddy, David A.; Ryan, Jessica J.; Young, Lynn M.; Wells, Trent; Kopczynski, Casey; Ellis, Michael C.

    2001-01-01

    For nearly a century, genetic analysis in Drosophila melanogaster has been a powerful tool for analyzing gene function, yet Drosophila lacks the molecular genetic mapping tools that recently have revolutionized human, mouse, and plant genetics. Here, we describe the systematic characterization of a dense set of molecular markers in Drosophila by using a sequence tagged site-based physical map of the genome. We identify 474 biallelic markers in standard laboratory strains of Drosophila that sp...

  15. Band edge states, intrinsic defects, and dopants in monolayer HfS2 and SnS2

    Science.gov (United States)

    Lu, Haichang; Guo, Yuzheng; Robertson, John

    2018-02-01

    Although monolayer HfS2 and SnS2 do not have a direct bandgap like MoS2, they have much higher carrier mobilities. Their band offsets are favorable for use with WSe2 in tunnel field effect transistors. Here, we study the effective masses, intrinsic defects, and substitutional dopants of these dichalcogenides. We find that HfS2 has surprisingly small effective masses for a compound that might appear partly ionic. The S vacancy in HfS2 is found to be a shallow donor while that in SnS2 is a deep donor. Substitutional dopants at the S site are found to be shallow. This contrasts with MoS2 where donors and acceptors are not always shallow or with black phosphorus where dopants can reconstruct into deep non-doping configurations. It is pointed out that HfS2 is more favorable than MoS2 for semiconductor processing because it has the more convenient CVD precursors developed for growing HfO2.

  16. Magnetoresistance in Co/2D MoS2/Co and Ni/2D MoS2/Ni junctions.

    Science.gov (United States)

    Zhang, Han; Ye, Meng; Wang, Yangyang; Quhe, Ruge; Pan, Yuanyuan; Guo, Ying; Song, Zhigang; Yang, Jinbo; Guo, Wanlin; Lu, Jing

    2016-06-28

    Semiconducting single-layer (SL) and few-layer MoS2 have a flat surface, free of dangling bonds. Using density functional theory coupled with non-equilibrium Green's function method, we investigate the spin-polarized transport properties of Co/2D MoS2/Co and Ni/2D MoS2/Ni junctions with MoS2 layer numbers of N = 1, 3, and 5. Well-defined interfaces are formed between MoS2 and metal electrodes. The junctions with a SL MoS2 spacer are almost metallic owing to the strong coupling between MoS2 and the ferromagnets, while those are tunneling with a few layer MoS2 spacer. Both large magnetoresistance and tunneling magnetoresistance are found when fcc or hcp Co is used as an electrode. Therefore, flat single- and few-layer MoS2 can serve as an effective nonmagnetic spacer in a magnetoresistance or tunneling magnetoresistance device with a well-defined interface.

  17. Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

    OpenAIRE

    Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

    2015-01-01

    A new BiS2-based superconductor Bi2(O,F)S2 was discovered. This is a layered compound consisting of alternate stacking structure of rock-salt-type BiS2 superconducting layer and fluorite-type Bi(O,F) blocking layer. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2, which is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis length increased and decreased, respe...

  18. Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

    Science.gov (United States)

    Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

    2015-02-01

    A new BiS2-based superconductor, Bi2(O,F)S2, was discovered. It is a layered compound consisting of alternately stacked structure of rock-salt-type BiS2 superconducting layers and fluorite-type Bi(O,F) blocking layers. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2. This is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis lengths increased and decreased, respectively, and Tc increased to 5.1 K.

  19. Intercalation of Si between MoS2 layers

    NARCIS (Netherlands)

    van Bremen, Rik; Yao, Qirong; Banerjee, Soumya; Cakir, Deniz; Oncel, Nuri; Zandvliet, Harold J.W.

    2017-01-01

    We report a combined experimental and theoretical study of the growth of sub-monolayer amounts of silicon (Si) on molybdenum disulfide (MoS2). At room temperature and low deposition rates we have found compelling evidence that the deposited Si atoms intercalate between the MoS2 layers. Our evidence

  20. Effect of Hawthorn on Drosophila Melanogaster Antioxidant-Related ...

    African Journals Online (AJOL)

    Purpose: To study the effects of various doses of hawthorn extract on Drosophila lifespan, antioxidant enzyme activity and expression of antioxidant-related regulation genes. Methods: Experiments with Drosophila as an animal model were conducted. The effects of hawthorn on Drosophila melanogaster antioxidant related ...

  1. MoS2-supported gold nanoparticle for CO hydrogenation

    Science.gov (United States)

    Rawal, Takat B.; Le, Duy; Rahman, Talat S.

    2017-10-01

    Employing dispersion-corrected density functional theory, we examine the geometry, electronic structure, and reactivity of 13-atom Au nanoparticle supported on defect-laden single-layer MoS2. The planar structure of Au13 favored in isolated phase, transforms into the three-dimensional structure when supported on MoS2. We find that charge is transferred from MoS2 to Au13, and that the electron density is also distributed away from the Au13/MoS2 interfacial region—making Au sites away from the interface catalytically active. Owing to effect of the support, the Au d states become narrower, and the frontier states appear close to the Fermi level. Consequently, in contrast to the reactivity of Au13/TiO2 toward methanol decomposition, Au13/MoS2 offers excellent activity toward methanol synthesis, as demonstrated here, via CO hydrogenation.

  2. Design lateral heterostructure of monolayer ZrS2 and HfS2 from first principles calculations

    Science.gov (United States)

    Yuan, Junhui; Yu, Niannian; Wang, Jiafu; Xue, Kan-Hao; Miao, Xiangshui

    2018-04-01

    The successful fabrication of two-dimensional lateral heterostructures (LHS's) has opened up unprecedented opportunities in material science and device physics. It is therefore highly desirable to search for more suitable materials to create such heterostructures for next-generation devices. Here, we investigate a novel lateral heterostructure composed of monolayer ZrS2 and HfS2 based on density functional theory. The phonon dispersion and ab initio molecular dynamics analysis indicate its good kinetic and thermodynamic stability. Remarkably, we find that these lateral heterostructures exhibit an indirect to direct bandgap transition, in contrast to the intrinsic indirect bandgap nature of ZrS2 and HfS2. The type-II alignment and chemical bonding across the interline have also been revealed. The tensile strain is proved to be an efficient way to modulate the band structure. Finally, we further discuss other three stable lateral heterostructures: (ZrSe2)2(HfSe2)2 LHS, (ZrS2)2(ZrSe2)2 LHS and (HfS2)2(HfSe2)2 LHS. Generally, the lateral heterostructures of monolayer ZrS2 and HfS2 are of excellent electrical properties, and may find potential applications for future electronic devices.

  3. Emergence of topological and topological crystalline phases in TlBiS2 and TlSbS2

    KAUST Repository

    Zhang, Qingyun

    2015-02-11

    Using first-principles calculations, we investigate the band structure evolution and topological phase transitions in TlBiS2 and TlSbS2 under hydrostatic pressure as well as uniaxial and biaxial strain. The phase transitions are identified by parity analysis and by calculating the surface states. Zero, one, and four Dirac cones are found for the (111) surfaces of both TlBiS2 and TlSbS2 when the pressure grows, which confirms trivial-nontrivial-trivial phase transitions. The Dirac cones at the (M) over bar points are anisotropic with large out-of-plane component. TlBiS2 shows normal, topological, and topological crystalline insulator phases under hydrostatic pressure, thus being the first compound to exhibit a phase transition from a topological to a topological crystalline insulator.

  4. Gut-associated microbes of Drosophila melanogaster

    Science.gov (United States)

    Broderick, Nichole; Lemaitre, Bruno

    2012-01-01

    There is growing interest in using Drosophila melanogaster to elucidate mechanisms that underlie the complex relationships between a host and its microbiota. In addition to the many genetic resources and tools Drosophila provides, its associated microbiota is relatively simple (1–30 taxa), in contrast to the complex diversity associated with vertebrates (> 500 taxa). These attributes highlight the potential of this system to dissect the complex cellular and molecular interactions that occur between a host and its microbiota. In this review, we summarize what is known regarding the composition of gut-associated microbes of Drosophila and their impact on host physiology. We also discuss these interactions in the context of their natural history and ecology and describe some recent insights into mechanisms by which Drosophila and its gut microbiota interact. “Workers with Drosophila have been considered fortunate in that they deal with the first multicellular invertebrate to be cultured monoxenically (Delcourt and Guyenot, 1910); the first to be handled axenically on a semisynthetic diet (Guyenot, 1917); and the first to be grown on a defined diet (Schultz et al., 1946). This list of advantages is somewhat embarrassing, since it implies an interest in nutrition that, in reality, was only secondary. The very first studies were concerned with the reduction of variability in genetic experiments (Delcourt and Guyenot, 1910) and standardization of the nutritional environment.” -James Sang, 1959 Ann NY Acad 1 PMID:22572876

  5. Soft chemistry routes to GeS2 nanoparticles

    Science.gov (United States)

    Courthéoux, Laurence; Mathiaud, Romain; Ribes, Michel; Pradel, Annie

    2018-04-01

    Spherical GeS2 particles are prepared by a low temperature liquid route with TEOG as germanium precursor and either H2S or thioacetamide (TAA) as sulfur precursors. The size and agglomeration of the particles change depending upon the temperature and nature of the solvent. Most synthesis lead to preparing amorphous GeS2. When the reaction kinetic is slowed down by using TAA at 25 °C, the obtained GeS2 product presents a larger order in the range of few Å as proven by Raman spectroscopy, even though it is still an amorphous compound as suggested by X-Ray diffraction and TEM experiments.

  6. Ripples and Layers in Ultrathin MoS2 Membranes

    OpenAIRE

    Brivio Jacopo Alexander Duncan T. L. Kis Andras

    2011-01-01

    Single layer MoS2 is a newly emerging two dimensional semiconductor with a potentially wide range of applications in the fields of nanoelectronics and energy harvesting. The fact that it can be exfoliated down to single layer thickness makes MoS2 interesting both for practical applications and for fundamental research where the structure and crystalline order of ultrathin MoS2 will have a strong influence on electronic mechanical and other properties. Here we report on the transmission elec...

  7. ReS2-based interlayer tunnel field effect transistor

    Science.gov (United States)

    Mohammed, Omar B.; Movva, Hema C. P.; Prasad, Nitin; Valsaraj, Amithraj; Kang, Sangwoo; Corbet, Chris M.; Taniguchi, Takashi; Watanabe, Kenji; Register, Leonard F.; Tutuc, Emanuel; Banerjee, Sanjay K.

    2017-12-01

    In this study, we report the fabrication and characterization of a vertical resonant interlayer tunneling field-effect transistor created using exfoliated, few-layer rhenium disulfide (ReS2) flakes as the electrodes and hexagonal boron nitride as the tunnel barrier. Due to the Γ-point conduction band minimum, the ReS2 based system offers the possibility of resonant interlayer tunneling and associated low-voltage negative differential resistance (NDR) without rotational alignment of the electrode crystal orientations. Substantial NDR is observed, which appears consistent with in-plane crystal momentum conserving tunneling, although considerably broadened by scattering consistent within low mobility ReS2 flakes.

  8. Charge density study of two FeS2 polymorphs

    DEFF Research Database (Denmark)

    Schmøkel, Mette Stokkebro; Jørgensen, Mads Ry Vogel; Bjerg, Lasse

    experimental electron density studies of an inorganic solid containing a transition metal was presented by Stevens et al. [2] who investigated the effect of crystal-field splitting of the partially filled iron d-orbitals in the pyrite structure of FeS2. Other studies of various FeS2 structures, including...... pyrite, has been performed by Gibbs et al. [3], however, these are all based on theoretical calculations rather than experiment. In the current study we revisit FeS2 through an experimental charge density study of the two low-spin iron FeS2 structures, pyrite and marcasite. High-quality, low...... been determined by multipole least squares modelling and analyzed by means of the Quantum Theory of Atoms in Molecules. The resulting topology has been compared to the results obtained by Gibbs et al. and to current periodic ab-initio DFT calculations and in general a good agreement between experiment...

  9. Rhenium-doped MoS2 films

    Science.gov (United States)

    Hallam, Toby; Monaghan, Scott; Gity, Farzan; Ansari, Lida; Schmidt, Michael; Downing, Clive; Cullen, Conor P.; Nicolosi, Valeria; Hurley, Paul K.; Duesberg, Georg S.

    2017-11-01

    Tailoring the electrical properties of transition metal dichalcogenides by doping is one of the biggest challenges for the application of 2D materials in future electronic devices. Here, we report on a straightforward approach to the n-type doping of molybdenum disulfide (MoS2) films with rhenium (Re). High-Resolution Scanning Transmission Electron Microscopy and Energy-Dispersive X-ray spectroscopy are used to identify Re in interstitial and lattice sites of the MoS2 structure. Hall-effect measurements confirm the electron donating influence of Re in MoS2, while the nominally undoped films exhibit a net p-type doping. Density functional theory (DFT) modelling indicates that Re on Mo sites is the origin of the n-type doping, whereas S-vacancies have a p-type nature, providing an explanation for the p-type behaviour of nominally undoped MoS2 films.

  10. Harmonic distributions, Diff(S2) and Virasoro algebra

    International Nuclear Information System (INIS)

    Saidi, E.H.; Zakkari, M.

    1990-09-01

    Harmonic distributions on the two sphere are developed and their relation with the complex plane ones is established. the basic harmonic distributions are shown to obey the Cauchy integration rules. Local Cartan tensors on S 2 are introduced. They are analytic functions satisfying a harmonic analyticity condition. Their Laurent expansion is examined and the connection with the complex plane analysis is given. Diff(S 2 ) and its one parameter gauge subgroups are discussed in the harmonic coordinate system. The derivation of the Virasoro algebra from the one parameter subgroups of Diff(S 2 ) is worked out in two special cases (α -- .β ++ = 0). A realization based on Cartan tensors is also given. Finally, we show that there is a 1 : 1 correspondence between the (2,0) supersymmetry on S 2 and the hypermultiplet duality of Galperin et al. (author). 19 refs

  11. Monolayer MoS2 heterojunction solar cells

    KAUST Repository

    Tsai, Menglin

    2014-08-26

    We realized photovoltaic operation in large-scale MoS2 monolayers by the formation of a type-II heterojunction with p-Si. The MoS 2 monolayer introduces a built-in electric field near the interface between MoS2 and p-Si to help photogenerated carrier separation. Such a heterojunction photovoltaic device achieves a power conversion efficiency of 5.23%, which is the highest efficiency among all monolayer transition-metal dichalcogenide-based solar cells. The demonstrated results of monolayer MoS 2/Si-based solar cells hold the promise for integration of 2D materials with commercially available Si-based electronics in highly efficient devices. © 2014 American Chemical Society.

  12. Receptor Tyrosine Kinases in Drosophila Development

    Science.gov (United States)

    Sopko, Richelle; Perrimon, Norbert

    2013-01-01

    Tyrosine phosphorylation plays a significant role in a wide range of cellular processes. The Drosophila genome encodes more than 20 receptor tyrosine kinases and extensive studies in the past 20 years have illustrated their diverse roles and complex signaling mechanisms. Although some receptor tyrosine kinases have highly specific functions, others strikingly are used in rather ubiquitous manners. Receptor tyrosine kinases regulate a broad expanse of processes, ranging from cell survival and proliferation to differentiation and patterning. Remarkably, different receptor tyrosine kinases share many of the same effectors and their hierarchical organization is retained in disparate biological contexts. In this comprehensive review, we summarize what is known regarding each receptor tyrosine kinase during Drosophila development. Astonishingly, very little is known for approximately half of all Drosophila receptor tyrosine kinases. PMID:23732470

  13. Viruses and Antiviral Immunity in Drosophila

    Science.gov (United States)

    Xu, Jie; Cherry, Sara

    2013-01-01

    Viral pathogens present many challenges to organisms, driving the evolution of a myriad of antiviral strategies to combat infections. A wide variety of viruses infect invertebrates, including both natural pathogens that are insect-restricted, and viruses that are transmitted to vertebrates. Studies using the powerful tools available in the model organism Drosophila have expanded our understanding of antiviral defenses against diverse viruses. In this review, we will cover three major areas. First, we will describe the tools used to study viruses in Drosophila. Second, we will survey the major viruses that have been studied in Drosophila. And lastly, we will discuss the well-characterized mechanisms that are active against these diverse pathogens, focusing on non-RNAi mediated antiviral mechanisms. Antiviral RNAi is discussed in another paper in this issue. PMID:23680639

  14. Apoptosis in Drosophila: which role for mitochondria?

    Science.gov (United States)

    Clavier, Amandine; Rincheval-Arnold, Aurore; Colin, Jessie; Mignotte, Bernard; Guénal, Isabelle

    2016-03-01

    It is now well established that the mitochondrion is a central regulator of mammalian cell apoptosis. However, the importance of this organelle in non-mammalian apoptosis has long been regarded as minor, mainly because of the absence of a crucial role for cytochrome c in caspase activation. Recent results indicate that the control of caspase activation and cell death in Drosophila occurs at the mitochondrial level. Numerous proteins, including RHG proteins and proteins of the Bcl-2 family that are key regulators of Drosophila apoptosis, constitutively or transiently localize in mitochondria. These proteins participate in the cell death process at different levels such as degradation of Diap1, a Drosophila IAP, production of mitochondrial reactive oxygen species or stimulation of the mitochondrial fission machinery. Here, we review these mitochondrial events that might have their counterpart in human.

  15. Facile synthesis of MoS2 and MoxW1-xS2 triangular monolayers

    Directory of Open Access Journals (Sweden)

    Zhong Lin

    2014-09-01

    Full Text Available Single- and few-layered transition metal dichalcogenides, such as MoS2 and WS2, are emerging two-dimensional materials exhibiting numerous and unusual physico-chemical properties that could be advantageous in the fabrication of unprecedented optoelectronic devices. Here we report a novel and alternative route to synthesize triangular monocrystals of MoS2 and MoxW1-xS2 by annealing MoS2 and MoS2/WO3 precursors, respectively, in the presence of sulfur vapor. In particular, the MoxW1-xS2 triangular monolayers show gradual concentration profiles of W and Mo whereby Mo concentrates in the islands’ center and W is more abundant on the outskirts of the triangular monocrystals. These observations were confirmed by atomic force microscopy, and high-resolution transmission electron microscopy, as well as Raman and photoluminescence spectroscopy. The presence of tunable PL signals depending on the MoxW1-xS2 stoichiometries in 2D monocrystals opens up a wide range of applications in electronics and optoelectronics.

  16. Functionalization of Single Layer MoS$_2$ Honeycomb Structures

    OpenAIRE

    Ataca, C.; Ciraci, S.

    2010-01-01

    Based on the first-principles plane wave calculations, we studied the functionalization of the two-dimensional single layer MoS$_2$ structure via adatom adsorption and vacancy defect creation. Minimum energy adsorption sites are determined for sixteen different adatoms, each gives rise to diverse properties. Bare, single layer MoS$_2$, which is normally a nonmagnetic, direct band gap semiconductor, attains a net magnetic moment upon adsorption of specific transition metal atoms, as well as si...

  17. The SCF ubiquitin ligase Slimb controls Nerfin-1 turnover in Drosophila.

    Science.gov (United States)

    Lin, Xiaohui; Wang, Feng; Li, Yuanpei; Zhai, Chaojun; Wang, Guiping; Zhang, Xiaoting; Gao, Yang; Yi, Tao; Sun, Dan; Wu, Shian

    2018-01-01

    The C2H2 type zinc-finger transcription factor Nerfin-1 expresses dominantly in Drosophila nervous system and plays an important role in early axon guidance decisions and preventing neurons dedifferentiation. Recently, increasing reports indicated that INSM1 (homologue to nerfin-1 in mammals) is a useful marker for prognosis of neuroendocrine tumors. The dynamic expression of Nerfin-1 is regulated post-transcriptionally by multiple microRNAs; however, its post-translational regulation is still unclear. Here we showed that the protein turnover of Nerfin-1 is regulated by Slimb, the substrate adaptor of SCF Slimb ubiquitin ligase complex. Mechanistically, Slimb associates with Nerfin-1 and promotes it ubiquitination and degradation in Drosophila S2R + cells. Furthermore, we determined that the C-terminal half of Nerfin-1 (Nerfin-1 CT ) is required for its binding to Slimb. Genetic epistasis assays showed that Slimb misexpression antagonizes, while knock-down enhances the activity of Nerfin-1 CT in Drosophila eyes. Our data revealed a new link to understand the underlying mechanism for Nerfin-1 turnover in post-translational level, and provided useful insights in animal development and disease treatment by manipulating the activity of Slimb and Nerfin-1. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Heterologous expression of mammalian Plk1 in Drosophila reveals divergence from Polo during late mitosis

    International Nuclear Information System (INIS)

    Pearson, John; Godinho, Susana A.; Tavares, Alvaro; Glover, David M.

    2006-01-01

    Drosophila Polo kinase is the founder member of a conserved kinase family required for multiple stages of mitosis. We assessed the ability of mouse Polo-like kinase 1 (Plk1) to perform the multiple mitotic functions of Polo kinase, by expressing a Plk1-GFP fusion in Drosophila. Consistent with the previously reported localization of Polo kinase, Plk1-GFP was strongly localized to centrosomes and recruited to the centromeric regions of condensing chromosomes during early mitosis. However, in contrast to a functional Polo-GFP fusion, Plk1-GFP failed to localize to the central spindle midzone in both syncytial embryo mitosis and the conventional mitoses of cellularized embryos and S2 cells. Moreover, unlike endogenous Polo kinase and Polo-GFP, Plk1-GFP failed to associate with the contractile ring. Expression of Plk1-GFP enhanced the lethality of hypomorphic polo mutants and disrupted the organization of the actinomyosin cytoskeleton in a dominant-negative manner. Taken together, our results suggest that endogenous Polo kinase has specific roles in regulating actinomyosin rearrangements during Drosophila mitoses that its mammalian counterpart, Plk1, cannot fulfill. Consistent with this hypothesis, we observed defects in the cortical recruitment of myosin and myosin regulatory light chain in Polo deficient cells

  19. Bicaudal is a conserved substrate for Drosophila and mammalian caspases and is essential for cell survival.

    LENUS (Irish Health Repository)

    Creagh, Emma M

    2009-01-01

    Members of the caspase family of cysteine proteases coordinate cell death through restricted proteolysis of diverse protein substrates and play a conserved role in apoptosis from nematodes to man. However, while numerous substrates for the mammalian cell death-associated caspases have now been described, few caspase substrates have been identified in other organisms. Here, we have utilized a proteomics-based approach to identify proteins that are cleaved by caspases during apoptosis in Drosophila D-Mel2 cells, a subline of the Schneider S2 cell line. This approach identified multiple novel substrates for the fly caspases and revealed that bicaudal\\/betaNAC is a conserved substrate for Drosophila and mammalian caspases. RNAi-mediated silencing of bicaudal expression in Drosophila D-Mel2 cells resulted in a block to proliferation, followed by spontaneous apoptosis. Similarly, silencing of expression of the mammalian bicaudal homologue, betaNAC, in HeLa, HEK293T, MCF-7 and MRC5 cells also resulted in spontaneous apoptosis. These data suggest that bicaudal\\/betaNAC is essential for cell survival and is a conserved target of caspases from flies to man.

  20. REDfly: a Regulatory Element Database for Drosophila.

    Science.gov (United States)

    Gallo, Steven M; Li, Long; Hu, Zihua; Halfon, Marc S

    2006-02-01

    Bioinformatics studies of transcriptional regulation in the metazoa are significantly hindered by the absence of readily available data on large numbers of transcriptional cis-regulatory modules (CRMs). Even the richly annotated Drosophila melanogaster genome lacks extensive CRM information. We therefore present here a database of Drosophila CRMs curated from the literature complete with both DNA sequence and a searchable description of the gene expression pattern regulated by each CRM. This resource should greatly facilitate the development of computational approaches to CRM discovery as well as bioinformatics analyses of regulatory sequence properties and evolution.

  1. Identification of the Drosophila skpA gene as a novel target of the transcription factor DREF

    International Nuclear Information System (INIS)

    Dang Thi Phuong Thao; Ida, Hiroyuki; Yoshida, Hideki; Yamaguchi, Masamitsu

    2006-01-01

    SKPa is component of a Drosophila SCF complex that functions in combination with the ubiquitin-conjugating enzyme UbcD1. skpA null mutation results in centrosome overduplication, unusual chromatin condensation, defective endoreduplication and cell-cycle progression. While the molecular mechanisms that regulate expression of the skpA gene are poorly understood, the DNA replication-related element (DRE) and the DRE-binding factor (DREF) play important roles in regulating proliferation-related genes in Drosophila and DRE (5'-TATCGATA) and DRE-like (5'-CATCGATT) sequences were here found to be involved in skpA promoter activity. Thus both luciferase transient expression assays in cultured Drosophila S2 cells using skpA promoter-luciferase fusion plasmids and anti-lacZ immunostaining of various tissues from transgenic third instar larvae carrying the skpA promoter-lacZ fusion genes provided supportive evidence. Furthermore, anti-SKPa immunostaining of eye imaginal discs from flies overexpressing DREF showed ectopic expression of protein in the region posterior to the morphogenetic furrow where DREF is overexpressed. Knockdown of DREF in some tissues where SKPa distribution is well known almost completely abrogated the skpA gene expression. These findings, taken together, indicate that the Drosophila skpA gene is a novel target of the transcription factor DREF

  2. The interface of the ferromagnetic metal CoS2 and the nonmagnetic semiconductor FeS2

    KAUST Repository

    Nazir, S.

    2010-11-05

    The electronic and magnetic properties of the cubic pyriteCoS2/FeS2interface are studied using the all-electron full-potential linearized augmented plane wave method. We find that this contact between a ferromagneticmetal and a nonmagnetic semiconductor shows a metallic character. The CoS2 stays close to half-metallicity at the interface, while the FeS2 becomes metallic. The magnetic moment of the Co atoms at the interface slightly decreases as compared to the bulk value and a small moment is induced on the Fe atoms. Furthermore, at the interfaceferromagnetic ordering is found to be energetically favorable as compared to antiferromagnetic ordering.

  3. Drosophila X-Linked Genes Have Lower Translation Rates than Autosomal Genes.

    Science.gov (United States)

    Zhang, Zhenguo; Presgraves, Daven C

    2016-02-01

    In Drosophila, X-linked and autosomal genes achieve comparable expression at the mRNA level. Whether comparable X-autosome gene expression is realized at the translational and, ultimately, the protein levels is, however, unknown. Previous studies suggest the possibility of higher translation rates for X-linked genes owing to stronger usage of preferred codons. In this study, we use public ribosome profiling data from Drosophila melanogaster to infer translation rates on the X chromosome versus the autosomes. We find that X-linked genes have consistently lower ribosome densities than autosomal genes in S2 cells, early embryos, eggs, and mature oocytes. Surprisingly, the lower ribosome densities of X-linked genes are not consistent with faster translation elongation but instead imply slower translation initiation. In particular, X-linked genes have sequence features known to slow translation initiation such as stronger mRNA structure near start codons and longer 5'-UTRs. Comparison to outgroup species suggests that stronger mRNA structure is an evolved feature of Drosophila X chromosomes. Finally, we find that the magnitude of the X-autosome difference in ribosome densities is smaller for genes encoding members of protein complexes, suggesting that stoichiometry constrains the evolution of translation rates. In sum, our analyses suggest that Drosophila X-linked genes have evolved lower translation rates than autosomal genes despite stronger usage of preferred codons. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Genetic changeover in Drosophila populations

    International Nuclear Information System (INIS)

    Wallace, B.

    1986-01-01

    Three populations of Drosophila melanogaster that were daughter populations of two others with histories of high, continuous radiation exposure [population 5 (irradiated, small population size) gave rise to populations 17 (small) and 18 (large); population 6 (irradiated, large population size) gave rise to population 19 (large)] were maintained for 1 year with no radiation exposure. The frequency with which random combinations of second chromosomes taken from population 19 proved to be lethal changed abruptly after about 8 months, thus revealing the origin of a selectively favored element in that population. (This element may or may not have been the cause of the lethality.) A comparison of the loss of lethals in populations 17 and 18 with a loss that occurred concurrently in the still-irradiated population 5 suggests that a second, selectively favored element had arisen in that population just before populations 17 and 18 were split off. This element was on a nonlethal chromosome. The result in population 5 was the elimination of many lethals from that population, followed by a subsequent increase as mutations occurred in the favored nonlethal chromosome. Populations 17 and 18, with no radiation exposure, underwent a loss of lethals with no subsequent increase. The events described here, as well as others to be described elsewhere, suggest that populations may be subject to episodic periods of rapid gene frequency changes that occur under intense selection pressure. In the instances in which the changeover was revealed by the elimination of preexisting lethals, earlier lethal frequencies were reduced by approximately one-half; the selectively favored elements appear, then, to be favored in the heterozygous--not homozygous--condition

  5. Olefin metathesis reaction on a MoS2 catalyst

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    Olefin metathesis reaction was found to take place on rather pure MoS 2 evacuated at 450 0 C for several hours. Systematic studies of the isotopic scrambling in ethylene, propylene, 1-butene, and 2-butene on MoS 2 using microwave spectroscopy are reported. These studies were made using 12 C- and 13 C-labelled compounds and D-labelled compounds. Results indicated that the MoS 2 catalyst evacuated at 450 0 C has two kinds of active sites, one is effective for the isomerization and the hydrogen isotopic mixing of olefins, and the other is effective for the hydrogenation reaction. This may be explained by assuming different degrees of coordinative unsaturation for the active sites

  6. Thermal conductivity of bulk and monolayer MoS2

    KAUST Repository

    Gandi, Appala

    2016-02-26

    © Copyright EPLA, 2016. We show that the lattice contribution to the thermal conductivity of MoS2 strongly dominates the carrier contribution in a broad temperature range from 300 to 800 K. Since theoretical insight into the lattice contribution is largely missing, though it would be essential for materials design, we solve the Boltzmann transport equation for the phonons self-consistently in order to evaluate the phonon lifetimes. In addition, the length scale for transition between diffusive and ballistic transport is determined. The low out-of-plane thermal conductivity of bulk MoS2 (2.3 Wm-1K-1 at 300 K) is useful for thermoelectric applications. On the other hand, the thermal conductivity of monolayer MoS2 (131 Wm-1K-1 at 300 K) is comparable to that of Si.

  7. Excitation intensity dependence of photoluminescence from monolayers of MoS2 and WS2/MoS2 heterostructures

    International Nuclear Information System (INIS)

    Kaplan, D; Swaminathan, V; Gong, Y; Ajayan, P M; Mills, K; Shirodkar, S; Kaxiras, E

    2016-01-01

    A detailed study of the excitation dependence of the photoluminescence (PL) from monolayers of MoS 2 and WS 2 /MoS 2 heterostructures grown by chemical vapor deposition on Si substrates has revealed that the luminescence from band edge excitons from MoS 2 monolayers shows a linear dependence on excitation intensity for both above band gap and resonant excitation conditions. In particular, a band separated by ∼55 meV from the A exciton, referred to as the C band, shows the same linear dependence on excitation intensity as the band edge excitons. A band similar to the C band has been previously ascribed to a trion, a charged, three-particle exciton. However, in our study the C band does not show the 3/2 power dependence on excitation intensity as would be expected for a three-particle exciton. Further, the PL from the MoS 2 monolayer in a bilayer WS 2 /MoS 2 heterostructure, under resonant excitation conditions where only the MoS 2 absorbs the laser energy, also revealed a linear dependence on excitation intensity for the C band, confirming that its origin is not due to a trion but instead a bound exciton, presumably of an unintentional impurity or a native point defect such as a sulfur vacancy. The PL from the WS 2 /MoS 2 heterostructure, under resonant excitation conditions also showed additional features which are suggested to arise from the interface states at the heteroboundary. Further studies are required to clearly identify the origin of these features. (paper)

  8. Chromosomal localization of autosomal mutations in Drosophila ...

    Indian Academy of Sciences (India)

    Unknown

    1Drosophila Stock Centre, Department of Studies in Zoology, University of Mysore,. Manasagangotri, Mysore 570 006, ... of genetic markers. In the present study, we have exploited the differences in karyotypic composition between these two subspecies, and their cross-fertility, in order to localize some autosomal genes.

  9. Lamin C and chromatin organization in Drosophila

    Indian Academy of Sciences (India)

    wm4h; Su(var)205/lamCEX187 had nearly normal red eye colour with little evidence of variegation, in contrast to the variegated eyes of the PEV strains crossed to w1118 strains. (figure 5,A&B). Precise excisions of ..... 2003 A P- element insertion screen identified mutations in. 455 novel essential genes in Drosophila.

  10. Second-Order Conditioning in "Drosophila"

    Science.gov (United States)

    Tabone, Christopher J.; de Belle, J. Steven

    2011-01-01

    Associative conditioning in "Drosophila melanogaster" has been well documented for several decades. However, most studies report only simple associations of conditioned stimuli (CS, e.g., odor) with unconditioned stimuli (US, e.g., electric shock) to measure learning or establish memory. Here we describe a straightforward second-order conditioning…

  11. Behavioural reproductive isolation and speciation in Drosophila

    Indian Academy of Sciences (India)

    In the genus Drosophila, the phenomenon of behavioural reproductive isolation, which is an important type of premating (prezygotic) reproductive isolating mechanisms, has been extensively studied and interesting data have been documented. In many cases incomplete sexual isolation has been observed and the pattern ...

  12. The Drosophila melanogaster circadian pacemaker circuit

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... As an experimental model system, the fruit fly Drosophila melanogaster has been seminal in shaping our understanding of the circadian clockwork. The wealth of genetic tools at our disposal over the past four decades has enabled discovery of the genetic and molecular bases of circadian rhythmicity.

  13. Functional Neuroanatomy of "Drosophila" Olfactory Memory Formation

    Science.gov (United States)

    Guven-Ozkan, Tugba; Davis, Ronald L.

    2014-01-01

    New approaches, techniques and tools invented over the last decade and a half have revolutionized the functional dissection of neural circuitry underlying "Drosophila" learning. The new methodologies have been used aggressively by researchers attempting to answer three critical questions about olfactory memories formed with appetitive…

  14. Biological effects of radon in Drosophila

    International Nuclear Information System (INIS)

    Pimentel P, A.E.; Tavera D, L.; Cruces M, M.P.; Arceo M, C.; Rosa D, M.E. de la

    1992-04-01

    The main objective of this investigation, is to study the biological effects of the Radon-222 at low dose in 'Drosophila melanogaster'. It is necessary to mention that these effects will analyze from the genetic point of view for: 1) To evaluate in which form the Radon-222 to low dose it influences in some genetic components of the adaptation in Drosophila, such as: fecundity, viability egg-adult and sex proportion. 2) To evaluate which is the genetic effect that induces the Radon to low dose by means of the SMART technique in Drosophila melanogaster, and this way to try of to identify which is the possible mechanism that causes the genetic damage to somatic level. The carried out investigation was divided in three stages: 1. Tests to the vacuum resistance. 2. Test of somatic mutation, and 3. Determination of the presence of radon daughters on the adult of Drosophila. It is necessary to point out that all the experiments were made by triplicate and in each one of them was placed detectors in preset places. Those obtained results are presented inside the 4 charts included in the present work. (Author)

  15. Egg-laying rhythm in Drosophila melanogaster

    Indian Academy of Sciences (India)

    Extensive research has been carried out to understand how circadian clocks regulate various physiological processes in organisms. The discovery of clock genes and the molecular clockwork has helped researchers to understand the possible role of these genes in regulating various metabolic processes. In Drosophila ...

  16. Radiation effects on the drosophila melanogaster genoma

    International Nuclear Information System (INIS)

    Arceo-Maldonado, C.

    1989-01-01

    When DNA of living beings has been damaged, the cells show different responses depending on their physiological state. Repair mechanisms can be classified into two groups: constitutive which are always present in the cells and inductible, which must be stimulated to show themselves. It is suggested that a repair mechanism exists in the drosophila ovules which act upon the damage present in mature spermatozoids. Our aim is to verify whether or not a radiation dosis applied to the female drosophila will modify the frequency of individuals which have lost the paternal sex chromosomes. YW/YW virgin females and XEZ males and fbb-/bS Y y + y were mated for two days in order to collect radiation treated spermatozoids. The results were consistent as to the parameters being evaluated and lead one to suppose that the radiation applied to the female drosophila produced some changes in the ovule metabolism which reduced the frequency of individuals with lost chromosomes. It is believed that ionizing radiation interferes with the repair mechanisms that are existent and constitutive, retarding and hindering the restoration of chromosome fragments and this brings about death of the zygote or death of the eggs which lessens the frequencies of individuals carriers of chromosomic aberrations. Ionizing radiations applied to the female drosophila modifies the frequency of loss of patternal chromosomes and comes about when the radiation dose to the female is 700 rad. (Author)

  17. Analysis of Phagocytosis in the Drosophila Ovary.

    Science.gov (United States)

    Meehan, Tracy L; Serizier, Sandy B; Kleinsorge, Sarah E; McCall, Kimberly

    2016-01-01

    Programmed cell death (PCD) is essential for health and development. Generally, the last step of PCD is clearance, or engulfment, by phagocytes. Engulfment can be broken down into five basic steps: attraction of the phagocyte, recognition of the dying cell, internalization, phagosome maturation, and acidification of the engulfed material. The Drosophila melanogaster ovary serves as an excellent model to study diverse types of PCD and engulfment by epithelial cells. Here, we describe several methods to detect and analyze multiple steps of engulfment in the Drosophila ovary: recognition, vesicle uptake, phagosome maturation, and acidification. Annexin V detects phosphatidylserine, which is flipped to the outer leaflet of the plasma membrane of apoptotic cells, serving as an "eat me" signal. Several germline markers including tral-GFP, Orb, and cleaved Dcp-1 can all be used to label the germline and visualize its uptake into engulfing follicle cells. Drosophila strains expressing GFP and mCherry protein fusions can enable a detailed analysis of phagosome maturation. LysoTracker labels highly acidified compartments, marking phagolysosomes. Together these labels can be used to mark the progression of engulfment in Drosophila follicle cells.

  18. The Drosophila melanogaster circadian pacemaker circuit

    Indian Academy of Sciences (India)

    2008-12-07

    Dec 7, 2008 ... large variety of tissues in the fly such as the eye, brain, pro- boscis, antennae, wings, abdomen, Malpighian tubules and testes (Plautz et al. 1997; Giebultowicz 2001). Although cell-autonomous circadian function is attributed to several tissues in Drosophila, circadian pacemaker neurons located in the brain ...

  19. Lamin C and chromatin organization in Drosophila

    Indian Academy of Sciences (India)

    Drosophila lamin C (LamC) is a developmentally regulated component of the nuclear lamina. The lamC gene is situated in the fifth intron of the essential gene tout velu (ttv). We carried out genetic analysis of lamC during development. Phenotypic analyses of RNAi-mediated downregulation of lamC expression as well as ...

  20. The Drosophila bipectinata species complex: phylogenetic ...

    Indian Academy of Sciences (India)

    Navya

    Acad. Sci India 82, 99-115. Tomimura Y., Matsuda, M. and Tobari, Y. N. 2005 Chromosomal phylogeny and geographical divergence in the Drosophila bipectinata complex. Genome 48, 487–502. White M. J. D. 1958 Restriction and recombination in grasshopper populations and species. Cold Spr. Harb. Symp. Quant. Biol.

  1. Sex determining signal in Drosophila melanogaster

    Indian Academy of Sciences (India)

    Administrator

    Drosophila; sex determination; X/A ratio; Sex-lethal. Sexual dimorphism is the most striking naturally occurring phenotypic variation that is a direct outcome of a simple. Mendelian segregation. Molecular genetic dissection of mechanisms underlying sexual development in organisms ranging from flies to humans has been a ...

  2. Radioresistance and radiosensitivity in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Reguly, M.L.; Marques, E.K.

    1987-01-01

    The mechanisms of radioresistance in Drosophila are studied. The mutagenic effects of 5KR of 60 Cobalt gamma radiation and of 0,006M dose of ethyl methanesulfonate (EMS) on four D. Melanogaster strains (RC 1 , CO 3 , BUE and LEN) are investigated. (M.A.C.) [pt

  3. Drosophila Melanogaster as an Experimental Organism.

    Science.gov (United States)

    Rubin, Gerald M.

    1988-01-01

    Discusses the role of the fruit fly in genetics research requiring a multidisciplinary approach. Describes embryological and genetic methods used in the experimental analysis of this organism. Outlines the use of Drosophila in the study of the development and function of the nervous system. (RT)

  4. Drosophila melanogaster deoxyribonucleoside kinase activates gemcitabine

    DEFF Research Database (Denmark)

    Knecht, Wolfgang; Mikkelsen, N.E.; Clausen, A.R.

    2009-01-01

    Drosophila melanogaster multisubstrate deoxyribonucleoside kinase (Dm-dNK) can additionally sensitize human cancer cell lines towards the anti-cancer drug gemcitabine. We show that this property is based on the Dm-dNK ability to efficiently phosphorylate gemcitabine. The 2.2 angstrom resolution...

  5. Intersex (ix) mutations of Drosophila melanogaster cause ...

    Indian Academy of Sciences (India)

    In Drosophila, a hierarchy of regulatory genes control somatic sexual differences (Baker 1989; Burtis and ... also function independently of dsx to regulate other aspects of sexual differentiation in tissue-specific manner. .... bination, for facilitating the analysis of single and double mutant genotypes. Double homozygote males ...

  6. Mapping selection within Drosophila melanogaster embryo's anatomy

    DEFF Research Database (Denmark)

    Salvador-Martínez, Irepan; Coronado-Zamora, Marta; Castellano, David

    2018-01-01

    We present a survey of selection across Drosophila melanogaster embryonic anatomy. Our approach integrates genomic variation, spatial gene expression patterns and development, with the aim of mapping adaptation over the entire embryo's anatomy. Our adaptation map is based on analyzing spatial gen...

  7. Developing a Drosophila Model of Schwannomatosis

    Science.gov (United States)

    2013-02-01

    General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA; 2Computer Science and Artificial Intelligence Laboratory...1384–1387. 61. Petersen UM, Kadalayil L, Rehorn KP, Hoshizaki DK, Reuter R, et al. (1999) Serpent regulates Drosophila immunity genes in the larval

  8. Intersex (ix) mutations of Drosophila melanogaster cause ...

    Indian Academy of Sciences (India)

    In Drosophila melanogaster, the intersex (ix) is a terminally positioned gene in somatic sex determination hierarchy and function with the female specific product of double sex (DSXF) to implement female sexual differentiation. The null phenotype of ix is to transform diplo-X individuals into intersexes while leaving haplo-X ...

  9. The Drosophila bipectinata species complex: phylogenetic ...

    Indian Academy of Sciences (India)

    [Banerjee P. and Singh B. N. 2017 The Drosophila bipectinata species complex: phylogenetic relationship among different members based on chromosomal variations. J. Genet. 96, 97–107]. Introduction ..... loops touch the chromocenter and in our microphotograph. (depicting both the arms) too, the involvement of chromo-.

  10. Atomic and electronic structure of MoS2 nanoparticles

    DEFF Research Database (Denmark)

    Bollinger, Mikkel; Jacobsen, Karsten Wedel; Nørskov, Jens Kehlet

    2003-01-01

    Using density-functional theory (DFT) we present a detailed theoretical study of MoS2 nanoparticles. We focus on the edge structures, and a number of different edge terminations are investigated. Several, but not all, of these configurations have one-dimensional metallic states localized at the e......Using density-functional theory (DFT) we present a detailed theoretical study of MoS2 nanoparticles. We focus on the edge structures, and a number of different edge terminations are investigated. Several, but not all, of these configurations have one-dimensional metallic states localized...

  11. Self-assembled lamellar MoS2, SnS2 and SiO2 semiconducting polymer nanocomposites.

    Science.gov (United States)

    Kirmayer, Saar; Aharon, Eyal; Dovgolevsky, Ekaterina; Kalina, Michael; Frey, Gitti L

    2007-06-15

    Lamellar nanocomposites based on semiconducting polymers incorporated into layered inorganic matrices are prepared by the co-assembly of organic and inorganic precursors. Semiconducting polymer-incorporated silica is prepared by introducing the semiconducting polymers into a tetrahydrofuran (THF)/water homogeneous sol solution containing silica precursor species and a surface-active agent. Semiconducting polymer-incorporated MoS(2) and SnS(2) are prepared by Li intercalation into the inorganic compound, exfoliation and restack in the presence of the semiconducting polymer. All lamellar nanocomposite films are organized in domains aligned parallel to the substrate surface plane. The incorporated polymers maintain their semiconducting properties, as evident from their optical absorption and photoluminescence spectra. The optoelectronic properties of the nanocomposites depend on the properties of both the inorganic host and the incorporated guest polymer as demonstrated by integrating the nanocomposite films into light-emitting diodes. Devices based on polymer-incorporated silica and polymer-incorporated MoS(2) show no diode behaviour and no light emission due to the insulating and metallic properties of the silica and MoS(2) hosts. In contrast, diode performance and electroluminescence are obtained from devices based on semiconducting polymer-incorporated semiconducting SnS(2), demonstrating that judicious selection of the composite components in combination with the optimization of material synthesis conditions allows new hierarchical structures to be tailored for electronic and optoelectronic applications.

  12. Drosophila increase exploration after visually detecting predators.

    Directory of Open Access Journals (Sweden)

    Miguel de la Flor

    Full Text Available Novel stimuli elicit behaviors that are collectively known as specific exploration. These behaviors allow the animal to become more familiar with the novel objects within its environment. Specific exploration is frequently suppressed by defensive reactions to predator cues. Herein, we examine if this suppression occurs in Drosophila melanogaster by measuring the response of these flies to wild harvested predators. The flies used in our experiments have been cultured and had not lived under predator threat for multiple decades. In a circular arena with centrally-caged predators, wild type Drosophila actively avoided the pantropical jumping spider, Plexippus paykulli, and the Texas unicorn mantis, Phyllovates chlorophaena, indicating an innate defensive reaction to these predators. Interestingly, wild type Drosophila males also avoided a centrally-caged mock spider, and the avoidance of the mock spider became exaggerated when it was made to move within the cage. Visually impaired Drosophila failed to detect and avoid the Plexippus paykulli and the moving mock spider, while the broadly anosmic orco2 mutants were fully capable of detecting and avoiding Plexippus paykulli, indicating that these flies principally relied upon vison to perceive the predator stimuli. During early exploration of the arena, exploratory activity increased in the presence of Plexippus paykulli and the moving mock spider. The elevated activity induced by Plexippus paykulli disappeared after the fly had finished exploring, suggesting the flies were capable of habituating the predator cues. Taken together, these results indicate that despite being isolated from predators for decades Drosophila will visually detect these predators, retain innate defensive behaviors, respond by increasing exploratory activity in the arena rather than suppressing activity, and may habituate to normal predator cues.

  13. Optogenetic pacing in Drosophila melanogaster (Conference Presentation)

    Science.gov (United States)

    Alex, Aneesh; Li, Airong; Men, Jing; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

    2016-03-01

    A non-invasive, contact-less cardiac pacing technology can be a powerful tool in basic cardiac research and in clinics. Currently, electrical pacing is the gold standard for cardiac pacing. Although highly effective in controlling the cardiac function, the invasive nature, non-specificity to cardiac tissues and possible tissue damage limits its capabilities. Optical pacing of heart is a promising alternative, which is non-invasive and more specific, has high spatial and temporal precision, and avoids shortcomings in electrical stimulation. Optical coherence tomography has been proved to be an effective technique in non-invasive imaging in vivo with ultrahigh resolution and imaging speed. In the last several years, non-invasive specific optical pacing in animal hearts has been reported in quail, zebrafish, and rabbit models. However, Drosophila Melanogaster, which is a significant model with orthologs of 75% of human disease genes, has rarely been studied concerning their optical pacing in heart. Here, we combined optogenetic control of Drosophila heartbeat with optical coherence microscopy (OCM) technique for the first time. The light-gated cation channel, channelrhodopsin-2 (ChR2) was specifically expressed by transgene as a pacemaker in drosophila heart. By stimulating the pacemaker with 472 nm pulsed laser light at different frequencies, we achieved non-invasive and more specific optical control of the Drosophila heart rhythm, which demonstrates the wide potential of optical pacing for studying cardiac dynamics and development. Imaging capability of our customized OCM system was also involved to observe the pacing effect visually. No tissue damage was found after long exposure to laser pulses, which proved the safety of optogenetic control of Drosophila heart.

  14. Stimulation of the Drosophila immune system alters genome-wide nucleosome occupancy

    Directory of Open Access Journals (Sweden)

    Yingxue Ren

    2015-03-01

    Full Text Available In eukaryotes, nucleosomes participate in all DNA-templated events by regulating access to the underlying DNA sequence. However, nucleosome dynamics during a genome response have not been well characterized [1,2]. We stimulated Drosophila S2 cells with heat-killed Gram-negative bacteria Salmonella typhimurium, and mapped genome-wide nucleosome occupancy at high temporal resolution by MNase-seq using Illumina HiSeq 2500. We show widespread nucleosome occupancy change in S2 cells during the immune response, with the significant nucleosomal loss occurring at 4 h after stimulation. Data have been deposited to the Gene Expression Omnibus (GEO database repository with the dataset identifier GSE64507.

  15. Ambipolar MoS2 Thin Flake Transistors

    NARCIS (Netherlands)

    Zhang, Yijin; Ye, Jianting; Matsuhashi, Yusuke; Iwasa, Yoshihiro

    Field effect transistors (FETs) made of thin flake single crystals isolated from layered materials have attracted growing interest since the success of graphene. Here, we report the fabrication of an electric double layer transistor (EDLT, a FET gated by ionic liquids) using a thin flake of MoS2, a

  16. Anionic construction of the SLq,s(2) algebra

    International Nuclear Information System (INIS)

    Matheus-Valle, J.L.; Monteiro, M.R.

    1993-01-01

    Considering anionic oscillators in a two-dimensional lattice, the quantum semi-group sl (q,s ) (2) is realized by means of a generalized Schwinger construction. It is found that the parameter q of the algebra is connected to the statistical parameter, whereas the s parameter is related to a s-deformed oscillator introduced at each point of the lattice. (author)

  17. High pressure synthesis of BiS2

    DEFF Research Database (Denmark)

    Søndergaard-Pedersen, Simone; Nielsen, Morten Bormann; Bremholm, Martin

    crystal structures and electrical properties.1,2 Up until now, the most sulfur rich phase in the Bi-S phase diagram was Bi2S3.3 For BiS2 the Bi atoms have anisotropic charge distribution and more complex structures are expected when comparing the layered structures of transition metal dichalcogenides....... The possibilities of using high pressure synthesis to discover new phases in the Bi-S binary system were investigated as early as the 1960’s.4 The research led to discovery of a compound with BiS2 stoichiometry, but no structure solution of BiS2 was reported. A reason behind making this new phase is to study...... the physical properties since the related compound Bi2S3 is known to be a thermoelectric material.5 In this research the BiS2 compound was synthesized by a high pressure and high temperature method using a multi-anvil large volume press and the structure was solved by single crystal diffraction. The structure...

  18. Single-layer MoS2 transistors.

    Science.gov (United States)

    Radisavljevic, B; Radenovic, A; Brivio, J; Giacometti, V; Kis, A

    2011-03-01

    Two-dimensional materials are attractive for use in next-generation nanoelectronic devices because, compared to one-dimensional materials, it is relatively easy to fabricate complex structures from them. The most widely studied two-dimensional material is graphene, both because of its rich physics and its high mobility. However, pristine graphene does not have a bandgap, a property that is essential for many applications, including transistors. Engineering a graphene bandgap increases fabrication complexity and either reduces mobilities to the level of strained silicon films or requires high voltages. Although single layers of MoS(2) have a large intrinsic bandgap of 1.8 eV (ref. 16), previously reported mobilities in the 0.5-3 cm(2) V(-1) s(-1) range are too low for practical devices. Here, we use a halfnium oxide gate dielectric to demonstrate a room-temperature single-layer MoS(2) mobility of at least 200 cm(2) V(-1) s(-1), similar to that of graphene nanoribbons, and demonstrate transistors with room-temperature current on/off ratios of 1 × 10(8) and ultralow standby power dissipation. Because monolayer MoS(2) has a direct bandgap, it can be used to construct interband tunnel FETs, which offer lower power consumption than classical transistors. Monolayer MoS(2) could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.

  19. Thermal conductivity of MoS2 polycrystalline nanomembranes

    Science.gov (United States)

    Sledzinska, M.; Graczykowski, B.; Placidi, M.; Saleta Reig, D.; El Sachat, A.; Reparaz, J. S.; Alzina, F.; Mortazavi, B.; Quey, R.; Colombo, L.; Roche, S.; Sotomayor Torres, C. M.

    2016-09-01

    Heat conduction in 2D materials can be effectively engineered by means of controlling nanoscale grain structure. A favorable thermal performance makes these structures excellent candidates for integrated heat management units. Here we show combined experimental and theoretical studies for MoS2 nanosheets in a nanoscale grain-size limit. We report thermal conductivity measurements on 5 nm thick polycrystalline MoS2 by means of 2-laser Raman thermometry. The free-standing, drum-like MoS2 nanomembranes were fabricated using a novel polymer- and residue-free, wet transfer, in which we took advantage of the difference in the surface energies between MoS2 and the growth substrate to transfer the CVD-grown nanosheets. The measurements revealed a strong reduction in the in-plane thermal conductivity down to about 0.73 ± 0.25 {{{W}}{{m}}}-1 {{{K}}}-1. The results are discussed theoretically using finite elements method simulations for a polycrystalline film, and a scaling trend of the thermally conductivity with grain size is proposed.

  20. Organization and evolution of Drosophila terminin: similarities and differences between Drosophila and human telomeres

    Directory of Open Access Journals (Sweden)

    Grazia Daniela Raffa

    2013-05-01

    Full Text Available Drosophila lacks telomerase and fly telomeres are elongated by occasional transposition of three specialized retroelements. Drosophila telomeres do not terminate with GC-rich repeats and are assembled independently of the sequence of chromosome ends. Recent work has shown that Drosophila telomeres are capped by the terminin complex, which includes the fast-evolving proteins HOAP, HipHop, Moi and Ver. These proteins are not conserves outside Drosophilidae and localize and function exclusively at telomeres, protecting them from fusion events. Other proteins required to prevent end-to-end fusion in flies include HP1, Eff/UbcD1, ATM, the components of the Mre11-Rad50-Nbs (MRN complex, and the Woc transcription factor. These proteins do not share the terminin properties; they are evolutionarily conserved non-fast-evolving proteins that do not accumulate only telomeres and do not serve telomere-specific functions. We propose that following telomerase loss, Drosophila rapidly evolved terminin to bind chromosome ends in a sequence-independent manner. This hypothesis suggests that terminin is the functional analog of the shelterin complex that protects human telomeres. The non-terminin proteins are instead likely to correspond to ancestral telomere-associated proteins that did not evolve as rapidly as terminin because of the functional constraints imposed by their involvement in diverse cellular processes. Thus, it appears that the main difference between Drosophila and human telomeres is in the protective complexes that specifically associate with the DNA termini. We believe that Drosophila telomeres offer excellent opportunities for investigations on human telomere biology. The identification of additional Drosophila genes encoding non-terminin proteins involved in telomere protection might lead to the discovery of novel components of human telomeres.

  1. Plasma-assisted synthesis of MoS2

    Science.gov (United States)

    Campbell, Philip M.; Perini, Christopher J.; Chiu, Johannes; Gupta, Atul; Ray, Hunter S.; Chen, Hang; Wenzel, Kevin; Snyder, Eric; Wagner, Brent K.; Ready, Jud; Vogel, Eric M.

    2018-03-01

    There has been significant interest in transition metal dichalcogenides (TMDs), including MoS2, in recent years due to their potential application in novel electronic and optical devices. While synthesis methods have been developed for large-area films of MoS2, many of these techniques require synthesis temperatures of 800 °C or higher. As a result of the thermal budget, direct synthesis requiring high temperatures is incompatible with many integrated circuit processes as well as flexible substrates. This work explores several methods of plasma-assisted synthesis of MoS2 as a way to lower the synthesis temperature. The first approach used is conversion of a naturally oxidized molybdenum thin film to MoS2 using H2S plasma. Conversion is demonstrated at temperatures as low as 400 °C, and the conversion is enabled by hydrogen radicals which reduce the oxidized molybdenum films. The second method is a vapor phase reaction incorporating thermally evaporated MoO3 exposed to a direct H2S plasma, similar to chemical vapor deposition (CVD) synthesis of MoS2. Synthesis at 400 °C results in formation of super-stoichiometric MoS2 in a beam-interrupted growth process. A final growth method relies on a cyclical process in which a small amount of Mo is sputtered onto the substrate and is subsequently sulfurized in a H2S plasma. Similar results could be realized using an atomic layer deposition (ALD) process to deposit the Mo film. Compared to high temperature synthesis methods, the lower temperature samples are lower quality, potentially due to poor crystallinity or higher defect density in the films. Temperature-dependent conductivity measurements are consistent with hopping conduction in the plasma-assisted synthetic MoS2, suggesting a high degree of disorder in the low-temperature films. Optimization of the plasma-assisted synthesis process for slower growth rate and better stoichiometry is expected to lead to high quality films at low growth temperature.

  2. Virtual half-metallicity at the CoS2/FeS2 interface induced by strain

    KAUST Repository

    Nazir, Safdar

    2013-01-01

    Spin polarized ab initio calculations based on density functional theory are performed to investigate the electronic and magnetic properties of the interface between the ferromagnetic metal CoS2 and the nonmagnetic semiconductor FeS2. Relaxation of the interface structure is taken into account by atomic force minimization. We find that both Co and Fe are close to half-metallicity at the interface. Tensile strain is shown to strongly enhance the spin polarization so that a virtually half-metallic interface can be achieved, for comparably moderate strain. © 2012 The Royal Society of Chemistry.

  3. FlyTED: the Drosophila Testis Gene Expression Database

    OpenAIRE

    Zhao, Jun; Klyne, Graham; Benson, Elizabeth; Gudmannsdottir, Elin; White-Cooper, Helen; Shotton, David

    2009-01-01

    FlyTED, the Drosophila Testis Gene Expression Database, is a biological research database for gene expression images from the testis of the fruit fly Drosophila melanogaster. It currently contains 2762 mRNA in situ hybridization images and ancillary metadata revealing the patterns of gene expression of 817 Drosophila genes in testes of wild type flies and of seven meiotic arrest mutant strains in which spermatogenesis is defective. This database has been built by adapting a widely used digita...

  4. Early Olfactory Processing in Drosophila: Mechanisms and Principles

    OpenAIRE

    Wilson, Rachel I.

    2013-01-01

    In the olfactory system of Drosophila melanogaster, it is relatively straightforward to make in vivo measurements of activity in neurons corresponding to targeted processing. This, together with the numerical simplicity of the Drosophila olfactory system, has produced rapid gains in our understanding of Drosophila olfaction. This review summarizes the neurophysiology of the first two layers of this system: the peripheral olfactory receptor neurons and their postsynaptic targets in the antenna...

  5. Molecular cloning, functional expression, and gene silencing of two Drosophila receptors for the Drosophila neuropeptide pyrokinin-2

    DEFF Research Database (Denmark)

    Rosenkilde, Carina; Cazzamali, Giuseppe; Williamson, Michael

    2003-01-01

    The database of the Drosophila Genome Project contains the sequences of two genes, CG8784 and CG8795, predicted to code for two structurally related G protein-coupled receptors. We have cloned these genes and expressed their coding parts in Chinese hamster ovary cells. We found that both receptors...... can be activated by low concentrations of the Drosophila neuropeptide pyrokinin-2 (CG8784, EC(50) for pyrokinin-2, 1x10(-9)M; CG8795, EC(50) for pyrokinin-2, 5 x 10(-10)M). The precise role of Drosophila pyrokinin-2 (SVPFKPRLamide) in Drosophila is unknown, but in other insects, pyrokinins have...... embryos and first instar larvae. In addition to the two Drosophila receptors, we also identified two probable pyrokinin receptors in the genomic database from the malaria mosquito Anopheles gambiae. The two Drosophila pyrokinin receptors are, to our knowledge, the first invertebrate pyrokinin receptors...

  6. Origin and Evolution of Y chromosomes: Drosophila tales

    Science.gov (United States)

    Carvalho, A. Bernardo; Koerich, Leonardo B.; Clark, Andrew G.

    2010-01-01

    Classically Y chromosomes are thought to originate from X chromosomes through a process of degeneration and gene loss. Now, the availability of 12 Drosophila genomes provides the opportunity to study the origin and evolution of Y chromosomes in an informative phylogenetic context. Surprisingly, the majority of Drosophila Y-linked genes are recent acquisitions from autosomes, and Y chromosome gene gains are more frequent than gene losses. Moreover, the D. pseudoobscura Y chromosome lacks homology with the Y of most Drosophila species. Thus the Drosophila Y has a different evolutionary history from canonical Y chromosomes (such as the mammalian Y), and it also might have a different origin. PMID:19443075

  7. Revealing electronic nature of broad bound exciton bands in two-dimensional semiconducting W S2 and Mo S2

    Science.gov (United States)

    Shang, Jingzhi; Cong, Chunxiao; Shen, Xiaonan; Yang, Weihuang; Zou, Chenji; Peimyoo, Namphung; Cao, Bingchen; Eginligil, Mustafa; Lin, Wei; Huang, Wei; Yu, Ting

    2017-12-01

    Owing to unique electronic, excitonic, and valleytronic properties, atomically thin transition metal dichalcogenides are becoming a promising two-dimensional (2D) semiconductor system for diverse electronic and optoelectronic applications. In an ideal 2D semiconductor, efficient carrier transport is very difficult because of lacking free charge carriers. Doping is necessary for electrically driven device applications based on such 2D semiconductors, which requires investigation of electronic structure changes induced by dopants. Therefore probing correlations between localized electronic states and doping is important. Here, we address the electronic nature of broad bound exciton bands and their origins in exfoliated monolayer (1L) W S2 and Mo S2 through monitoring low-temperature photoluminescence and manipulating electrostatic doping. The dominant bound excitons in 1L W S2 vary from donor to acceptor bound excitons with the switching from n - to p -type doping. In 1L Mo S2 , two localized emission bands appear which are assigned to neutral and ionized donor bound excitons, respectively. The deep donor and acceptor states play critical roles in the observed bound exciton bands, indicating the presence of strongly localized excitons in such 2D semiconductors.

  8. MoS 2 MoS2: choice substrate for accessing and tuning the electronic properties of graphene.

    Science.gov (United States)

    Lu, Chih-Pin; Li, Guohong; Watanabe, K; Taniguchi, T; Andrei, Eva Y

    2014-10-10

    One of the enduring challenges in graphene research and applications is the extreme sensitivity of its charge carriers to external perturbations, especially those introduced by the substrate. The best available substrates to date, graphite and hexagonal boron nitride (h-BN), still pose limitations: graphite being metallic does not allow gating, while both h-BN and graphite, having lattice structures closely matched to that of graphene, may cause significant band structure reconstruction. Here we show that the atomically smooth surface of exfoliated MoS(2) provides access to the intrinsic electronic structure of graphene without these drawbacks. Using scanning tunneling microscopy and Landau-level (LL) spectroscopy in a device configuration that allows tuning of the carrier concentration, we find that graphene on MoS(2) is ultraflat, producing long mean free paths, while avoiding band structure reconstruction. Importantly, the screening of the MoS(2) substrate can be tuned by changing the position of the Fermi energy with relatively low gate voltages. We show that shifting the Fermi energy from the gap to the edge of the conduction band gives rise to enhanced screening and to a substantial increase in the mean free path and quasiparticle lifetime. MoS(2) substrates thus provide unique opportunities to access the intrinsic electronic properties of graphene and to study in situ the effects of screening on electron-electron interactions and transport.

  9. Integrability of the superstring in AdS3 × S 2 × S 2 × T 3

    Science.gov (United States)

    Wulff, Linus

    2017-06-01

    Type II supergravity admits an AdS_3× S^2× S^2× T3 solution with fluxes depending on several free parameters. We determine the constraints on these parameters imposed by the requirement of (classical) integrability of the superstring sigma model. To do this we analyze the low-energy effective action for the spinning GKP string. The absence of particle production in the tree-level S-matrix of bosonic excitations is shown to imply the vanishing of two of the four parameters in the NSNS three-form flux. This reduces the supergravity background to either the one-parameter AdS_3× S^2× S^2× T3 background preserving eight supersymmetries, or a non-supersymmetric branch, which differs only by flipping a sign in the RR flux. We show that both these branches can be obtained from AdS_3× S^3× S^3× S1 by T-dualities on the (Hopf) circle fibers of the three-spheres and therefore the integrability of the string in these backgrounds follows.

  10. Mutants dissecting development and behaviour in drosophila

    International Nuclear Information System (INIS)

    Joshi, Adita; Chandrashekaran, Shanti; Sharma, R.P.

    2005-01-01

    We have traced in this paper the progress in Drosophila genetics research from the 1960s, at the IARI, spearheaded by the visionary insight of M. S. Swaminathan. The work started with the study of indirect effect of radiation and the synergistic interaction of physical and chemical mutagens on chromosomal and genetic changes. This paved the way for the study of single gene mutants in dissecting developmental and behavioural processes. New genes discovered by us have been shown to encode conserved cell signalling molecules controlling developmental and behavioural pathways. With the complete sequencing of the Drosophila genome, in the year 2000, mounting evidence for the homology between Drosophila and human genes controlling genetic disorders became available. This has led to the fly becoming an indispensable tool for studying human diseases as well as a model to test for drugs and pharmaceuticals against human diseases and complex behavioural processes. For example wingless in Drosophila belongs to the conserved Wnt gene family and aberrant WNT signalling is linked to a range of human diseases, most notably cancer. Inhibition as well as activation of WNT signalling form the basis of an effective therapy for some cancers as well as several other clinical conditions. Recent experiments have shown that WNTs might also normally participate in self-renewal, proliferation or differentiation of stem cells and altering WNT signalling might be beneficial to the use of stem cells for therapeutic means. Likewise, the stambhA mutant of Drosophila which was discovered for its temperature-dependent paralytic behaviour is the fly homologue of Phospholipase Cβ. Phospholipase C mediated G protein signalling plays a central role in vital processes controlling epilepsy, vision, taste, and olfaction in animals. Proteins of the G-signalling pathway are of intense research interest since many human diseases involve defects in G-protein signalling pathways. In fact, approximately 50

  11. Parametric amplification in MoS2drum resonator.

    Science.gov (United States)

    Prasad, Parmeshwar; Arora, Nishta; Naik, A K

    2017-11-30

    Parametric amplification is widely used in diverse areas from optics to electronic circuits to enhance low level signals by varying relevant system parameters. Parametric amplification has also been performed in several micro-nano resonators including nano-electromechanical system (NEMS) resonators based on a two-dimensional (2D) material. Here, we report the enhancement of mechanical response in a MoS 2 drum resonator using degenerate parametric amplification. We use parametric pumping to modulate the spring constant of the MoS 2 resonator and achieve a 10 dB amplitude gain. We also demonstrate quality factor enhancement in the resonator with parametric amplification. We investigate the effect of cubic nonlinearity on parametric amplification and show that it limits the gain of the mechanical resonator. Amplifying ultra-small displacements at room temperature and understanding the limitations of the amplification in these devices is key for using these devices for practical applications.

  12. Massless AdS 2 scattering and Bethe ansatz

    Science.gov (United States)

    Fontanella, A.; Torrielli, A.

    2017-09-01

    We first analyse the integrable scattering theory describing the massless excitations of AdS 2 × S 2 × T 6 superstrings in the relativistic limit. The matrix part of the S-matrix is obtained in the BMN limit from the conjectured exact expression, and compared to known S-matrices with N=1 supersymmetry in 1 + 1 dimensions. A dressing factor, yet unknown for the complete theory, is here constructed based on relativistic crossing symmetry. We derive a Bethe-ansatz condition by employing a transfer-matrix technique based on the so-called free-fermion condition. This is known to overcome the problem of lack of a reference state. We then generalise the method to the massless non-relativistic case, and compare the resulting Bethe-ansatz condition with a simple massless limit of the one conjectured by Sorokin, Tseytlin, Wulff and Zarembo.

  13. New four-quark ΔS = 2 local operator

    International Nuclear Information System (INIS)

    Donoghue, J.F.; Golowich, E.; Valencia, G.

    1986-01-01

    We describe a new four-quark ΔS = 2 local operator, which we dub the ''dipenguin'' operator. Its form is derived and its K-bar 0 -to-K 0 matrix element is estimated. Also, we comment upon bag-model evaluations of K-bar 0 -to-K 0 matrix elements of (V-A) x (V-A) operators

  14. Monolayer MoS2 self-switching diodes

    International Nuclear Information System (INIS)

    Al-Dirini, Feras; Hossain, Md Sharafat; Hossain, Faruque M.; Skafidas, Efstratios; Mohammed, Mahmood A.; Nirmalathas, Ampalavanapillai

    2016-01-01

    This paper presents a new molybdenum disulphide (MoS 2 ) nanodevice that acts as a two-terminal field-effect rectifier. The device is an atomically-thin two-dimensional self-switching diode (SSD) that can be realized within a single MoS 2 monolayer with very minimal process steps. Quantum simulation results are presented confirming the device's operation as a diode and showing strong non-linear I-V characteristics. Interestingly, the device shows p-type behavior, in which conduction is dominated by holes as majority charge carriers and the flow of reverse current is enhanced, while the flow of forward current is suppressed, in contrast to monolayer graphene SSDs, which behave as n-type devices. The presence of a large bandgap in monolayer MoS 2 results in strong control over the channel, showing complete channel pinch-off in forward conduction, which was confirmed with transmission pathways plots. The device exhibited large leakage tunnelling current through the insulating trenches, which may have been due to the lack of passivation; nevertheless, reverse current remained to be 6 times higher than forward current, showing strong rectification. The effect of p-type substitutional channel doping of sulphur with phosphorus was investigated and showed that it greatly enhances the performance of the device, increasing the reverse-to-forward current rectification ratio more than an order of magnitude, up to a value of 70

  15. Highly sensitive MoS2 photodetectors with graphene contacts

    Science.gov (United States)

    Han, Peize; St. Marie, Luke; Wang, Qing X.; Quirk, Nicholas; El Fatimy, Abdel; Ishigami, Masahiro; Barbara, Paola

    2018-05-01

    Two-dimensional materials such as graphene and transition metal dichalcogenides (TMDs) are ideal candidates to create ultra-thin electronics suitable for flexible substrates. Although optoelectronic devices based on TMDs have demonstrated remarkable performance, scalability is still a significant issue. Most devices are created using techniques that are not suitable for mass production, such as mechanical exfoliation of monolayer flakes and patterning by electron-beam lithography. Here we show that large-area MoS2 grown by chemical vapor deposition and patterned by photolithography yields highly sensitive photodetectors, with record shot-noise-limited detectivities of 8.7 × 1014 Jones in ambient condition and even higher when sealed with a protective layer. These detectivity values are higher than the highest values reported for photodetectors based on exfoliated MoS2. We study MoS2 devices with gold electrodes and graphene electrodes. The devices with graphene electrodes have a tunable band alignment and are especially attractive for scalable ultra-thin flexible optoelectronics.

  16. S2p core level spectroscopy of short chain oligothiophenes.

    Science.gov (United States)

    Baseggio, O; Toffoli, D; Stener, M; Fronzoni, G; de Simone, M; Grazioli, C; Coreno, M; Guarnaccio, A; Santagata, A; D'Auria, M

    2017-12-28

    The Near-Edge X-ray-Absorption Fine-Structure (NEXAFS) and X-ray Photoemission Spectroscopy (XPS) of short-chain oligothiophenes (thiophene, 2,2'-bithiophene, and 2,2':5',2″-terthiophene) in the gas phase have been measured in the sulfur L 2,3 -edge region. The assignment of the spectral features is based on the relativistic two-component zeroth-order regular approximation time dependent density functional theory approach. The calculations allow us to estimate both the contribution of the spin-orbit splitting and of the molecular-field splitting to the sulfur binding energies and give results in good agreement with the experimental measurements. The deconvolution of the calculated S2p NEXAFS spectra into the two manifolds of excited states converging to the L III and L II edges facilitates the attribution of the spectral structures. The main S2p NEXAFS features are preserved along the series both as concerns the energy positions and the nature of the transitions. This behaviour suggests that the electronic and geometrical environment of the sulfur atom in the three oligomers is relatively unaffected by the increasing chain length. This trend is also observed in the XPS spectra. The relatively simple structure of S2p NEXAFS spectra along the series reflects the localized nature of the virtual states involved in the core excitation process.

  17. S2p core level spectroscopy of short chain oligothiophenes

    Science.gov (United States)

    Baseggio, O.; Toffoli, D.; Stener, M.; Fronzoni, G.; de Simone, M.; Grazioli, C.; Coreno, M.; Guarnaccio, A.; Santagata, A.; D'Auria, M.

    2017-12-01

    The Near-Edge X-ray-Absorption Fine-Structure (NEXAFS) and X-ray Photoemission Spectroscopy (XPS) of short-chain oligothiophenes (thiophene, 2,2'-bithiophene, and 2,2':5',2″-terthiophene) in the gas phase have been measured in the sulfur L2,3-edge region. The assignment of the spectral features is based on the relativistic two-component zeroth-order regular approximation time dependent density functional theory approach. The calculations allow us to estimate both the contribution of the spin-orbit splitting and of the molecular-field splitting to the sulfur binding energies and give results in good agreement with the experimental measurements. The deconvolution of the calculated S2p NEXAFS spectra into the two manifolds of excited states converging to the LIII and LII edges facilitates the attribution of the spectral structures. The main S2p NEXAFS features are preserved along the series both as concerns the energy positions and the nature of the transitions. This behaviour suggests that the electronic and geometrical environment of the sulfur atom in the three oligomers is relatively unaffected by the increasing chain length. This trend is also observed in the XPS spectra. The relatively simple structure of S2p NEXAFS spectra along the series reflects the localized nature of the virtual states involved in the core excitation process.

  18. Transcriptome analysis of Drosophila neural stem cells.

    Science.gov (United States)

    Gold, Katrina S; Brand, Andrea H

    2012-01-01

    In Drosophila, the central nervous system is populated by a set of asymmetrically dividing neural stem cells called neuroblasts. Neuroblasts are derived from epithelial or neuroepithelial precursors, and divide along their apico-basal axes to produce a large apical neuroblast and a smaller basal ganglion mother cell. The ganglion mother cell will divide once again to produce two post-mitotic neurons or glia. In this chapter we outline a method for labeling different types of neural precursors in the Drosophila central nervous system, followed by their extraction and processing for transcriptome analysis. This technique has allowed us to capture and compare the expression profiles of neuroblasts and neuroepithelial cells, resulting in the identification of key genes required for the regulation of self-renewal and differentiation.

  19. Drosophila VAMP7 regulates Wingless intracellular trafficking.

    Science.gov (United States)

    Gao, Han; He, Fang; Lin, Xinhua; Wu, Yihui

    2017-01-01

    Drosophila Wingless (Wg) is a morphogen that determines cell fate during development. Previous studies have shown that endocytic pathways regulate Wg trafficking and signaling. Here, we showed that loss of vamp7, a gene required for vesicle fusion, dramatically increased Wg levels and decreased Wg signaling. Interestingly, we found that levels of Dally-like (Dlp), a glypican that can interact with Wg to suppress Wg signaling at the dorsoventral boundary of the Drosophila wing, were also increased in vamp7 mutant cells. Moreover, Wg puncta in Rab4-dependent recycling endosomes were Dlp positive. We hypothesize that VAMP7 is required for Wg intracellular trafficking and the accumulation of Wg in Rab4-dependent recycling endosomes might affect Wg signaling.

  20. Maintenance of a Drosophila melanogaster Population Cage.

    Science.gov (United States)

    Caravaca, Juan Manuel; Lei, Elissa P

    2016-03-15

    Large quantities of DNA, RNA, proteins and other cellular components are often required for biochemistry and molecular biology experiments. The short life cycle of Drosophila enables collection of large quantities of material from embryos, larvae, pupae and adult flies, in a synchronized way, at a low economic cost. A major strategy for propagating large numbers of flies is the use of a fly population cage. This useful and common tool in the Drososphila community is an efficient way to regularly produce milligrams to tens of grams of embryos, depending on uniformity of developmental stage desired. While a population cage can be time consuming to set up, maintaining a cage over months takes much less time and enables rapid collection of biological material in a short period. This paper describes a detailed and flexible protocol for the maintenance of a Drosophila melanogaster population cage, starting with 1.5 g of harvested material from the previous cycle.

  1. Adaptive Evolution of Gene Expression in Drosophila

    Directory of Open Access Journals (Sweden)

    Armita Nourmohammad

    2017-08-01

    Full Text Available Gene expression levels are important quantitative traits that link genotypes to molecular functions and fitness. In Drosophila, population-genetic studies have revealed substantial adaptive evolution at the genomic level, but the evolutionary modes of gene expression remain controversial. Here, we present evidence that adaptation dominates the evolution of gene expression levels in flies. We show that 64% of the observed expression divergence across seven Drosophila species are adaptive changes driven by directional selection. Our results are derived from time-resolved data of gene expression divergence across a family of related species, using a probabilistic inference method for gene-specific selection. Adaptive gene expression is stronger in specific functional classes, including regulation, sensory perception, sexual behavior, and morphology. Moreover, we identify a large group of genes with sex-specific adaptation of expression, which predominantly occurs in males. Our analysis opens an avenue to map system-wide selection on molecular quantitative traits independently of their genetic basis.

  2. Neural control of aggression in Drosophila.

    Science.gov (United States)

    Hoopfer, Eric D

    2016-06-01

    Like most animal species, fruit flies fight to obtain and defend resources essential to survival and reproduction. Aggressive behavior in Drosophila is genetically specified and also strongly influenced by the fly's social context, past experiences and internal states, making it an excellent framework for investigating the neural mechanisms that regulate complex social behaviors. Here, I summarize our current knowledge of the neural control of aggression in Drosophila and discuss recent advances in understanding the sensory pathways that influence the decision to fight or court, the neuromodulatory control of aggression, the neural basis by which internal states can influence both fighting and courtship, and how social experience modifies aggressive behavior. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Counting Calories in Drosophila Diet Restriction

    Science.gov (United States)

    Min, Kyung-Jin; Flatt, Thomas; Kulaots, Indrek; Tatar, Marc

    2007-01-01

    The extension of life span by diet restriction in Drosophila has been argued to occur without limiting calories. Here we directly measure the calories assimilated by flies when maintained on full- and restricted-diets. We find that caloric intake is reduced on all diets that extend life span. Flies on low-yeast diet are long-lived and consume about half the calories of flies on high yeast diets, regardless of the energetic content of the diet itself. Since caloric intake correlates with yeast concentration and thus with the intake of every metabolite in this dietary component, it is premature to conclude for Drosophila that calories do not explain extension of life span. PMID:17125951

  4. The fabulous destiny of the Drosophila heart.

    Science.gov (United States)

    Medioni, Caroline; Sénatore, Sébastien; Salmand, Pierre-Adrien; Lalevée, Nathalie; Perrin, Laurent; Sémériva, Michel

    2009-10-01

    For the last 15 years the fly cardiovascular system has attracted developmental geneticists for its potential as a model system of organogenesis. Heart development in Drosophila indeed provides a remarkable system for elucidating the basic molecular and cellular mechanisms of morphogenesis and, more recently, for understanding the genetic control of cardiac physiology. The success of these studies can in part be attributed to multidisciplinary approaches, the multiplicity of existing genetic tools, and a detailed knowledge of the system. Striking similarities with vertebrate cardiogenesis have long been stressed, in particular concerning the conservation of key molecular regulators of cardiogenesis and the new data presented here confirm Drosophila cardiogenesis as a model not only for organogenesis but also for the study of molecular mechanisms of human cardiac disease.

  5. Remembering components of food in Drosophila

    Directory of Open Access Journals (Sweden)

    Gaurav eDas

    2016-02-01

    Full Text Available Remembering features of past feeding experience can refine foraging and food choice. Insects can learn to associate sensory cues with components of food, such as sugars, amino acids, water, salt, alcohol, toxins and pathogens. In the fruit fly Drosophila some food components activate unique subsets of dopaminergic neurons that innervate distinct functional zones on the mushroom bodies. This architecture suggests that the overall dopaminergic neuron population could provide a potential cellular substrate through which the fly might learn to value a variety of food components. In addition, such an arrangement predicts that individual component memories reside in unique locations. Dopaminergic neurons are also critical for food memory consolidation and deprivation-state dependent motivational control of the expression of food-relevant memories. Here we review our current knowledge of how nutrient-specific memories are formed, consolidated and specifically retrieved in insects, with a particular emphasis on Drosophila.

  6. Development of larval motor circuits in Drosophila.

    Science.gov (United States)

    Kohsaka, Hiroshi; Okusawa, Satoko; Itakura, Yuki; Fushiki, Akira; Nose, Akinao

    2012-04-01

    How are functional neural circuits formed during development? Despite recent advances in our understanding of the development of individual neurons, little is known about how complex circuits are assembled to generate specific behaviors. Here, we describe the ways in which Drosophila motor circuits serve as an excellent model system to tackle this problem. We first summarize what has been learned during the past decades on the connectivity and development of component neurons, in particular motor neurons and sensory feedback neurons. We then review recent progress in our understanding of the development of the circuits as well as studies that apply optogenetics and other innovative techniques to dissect the circuit diagram. New approaches using Drosophila as a model system are now making it possible to search for developmental rules that regulate the construction of neural circuits. © 2012 The Authors Development, Growth & Differentiation © 2012 Japanese Society of Developmental Biologists.

  7. The translation factors of Drosophila melanogaster.

    Science.gov (United States)

    Marygold, Steven J; Attrill, Helen; Lasko, Paul

    2017-01-02

    Synthesis of polypeptides from mRNA (translation) is a fundamental cellular process that is coordinated and catalyzed by a set of canonical 'translation factors'. Surprisingly, the translation factors of Drosophila melanogaster have not yet been systematically identified, leading to inconsistencies in their nomenclature and shortcomings in functional (Gene Ontology, GO) annotations. Here, we describe the complete set of translation factors in D. melanogaster, applying nomenclature already in widespread use in other species, and revising their functional annotation. The collection comprises 43 initiation factors, 12 elongation factors, 3 release factors and 6 recycling factors, totaling 64 of which 55 are cytoplasmic and 9 are mitochondrial. We also provide an overview of notable findings and particular insights derived from Drosophila about these factors. This catalog, together with the incorporation of the improved nomenclature and GO annotation into FlyBase, will greatly facilitate access to information about the functional roles of these important proteins.

  8. Exquisite light sensitivity of Drosophila melanogaster cryptochrome.

    Directory of Open Access Journals (Sweden)

    Pooja Vinayak

    Full Text Available Drosophila melanogaster shows exquisite light sensitivity for modulation of circadian functions in vivo, yet the activities of the Drosophila circadian photopigment cryptochrome (CRY have only been observed at high light levels. We studied intensity/duration parameters for light pulse induced circadian phase shifts under dim light conditions in vivo. Flies show far greater light sensitivity than previously appreciated, and show a surprising sensitivity increase with pulse duration, implying a process of photic integration active up to at least 6 hours. The CRY target timeless (TIM shows dim light dependent degradation in circadian pacemaker neurons that parallels phase shift amplitude, indicating that integration occurs at this step, with the strongest effect in a single identified pacemaker neuron. Our findings indicate that CRY compensates for limited light sensitivity in vivo by photon integration over extraordinarily long times, and point to select circadian pacemaker neurons as having important roles.

  9. Motor Control of Drosophila Courtship Song

    Directory of Open Access Journals (Sweden)

    Troy R. Shirangi

    2013-11-01

    Full Text Available Many animals utilize acoustic signals—or songs—to attract mates. During courtship, Drosophila melanogaster males vibrate a wing to produce trains of pulses and extended tone, called pulse and sine song, respectively. Courtship songs in the genus Drosophila are exceedingly diverse, and different song features appear to have evolved independently of each other. How the nervous system allows such diversity to evolve is not understood. Here, we identify a wing muscle in D. melanogaster (hg1 that is uniquely male-enlarged. The hg1 motoneuron and the sexually dimorphic development of the hg1 muscle are required specifically for the sine component of the male song. In contrast, the motoneuron innervating a sexually monomorphic wing muscle, ps1, is required specifically for a feature of pulse song. Thus, individual wing motor pathways can control separate aspects of courtship song and may provide a “modular” anatomical substrate for the evolution of diverse songs.

  10. Plasticity in the Drosophila larval visual System

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    Abud J Farca-Luna

    2013-07-01

    Full Text Available The remarkable ability of the nervous system to modify its structure and function is mostly experience and activity modulated. The molecular basis of neuronal plasticity has been studied in higher behavioral processes, such as learning and memory formation. However, neuronal plasticity is not restricted to higher brain functions, but may provide a basic feature of adaptation of all neural circuits. The fruit fly Drosophila melanogaster provides a powerful genetic model to gain insight into the molecular basis of nervous system development and function. The nervous system of the larvae is again a magnitude simpler than its adult counter part, allowing the genetic assessment of a number of individual genetically identifiable neurons. We review here recent progress on the genetic basis of neuronal plasticity in developing and functioning neural circuits focusing on the simple visual system of the Drosophila larva.

  11. Rapid matching in Drosophila place learning

    Science.gov (United States)

    Zars, Melissa; Zars, Troy

    2009-08-01

    The level of conditioned behavior in animals is proportional to the intensity, amount, frequency, or probability of reinforcement. Interestingly, this matching can be dynamic, with performance levels following, for example, a switch in the probability of reinforcement with a short delay. We previously found that conditioned performance levels in Drosophila match reinforcement intensity in a place conditioning paradigm. Whether Drosophila can match conditioned behavior to a change in reinforcement intensity was an open question. In this study, we found that both conditioned behavior and memory levels match reinforcement intensity after a switch, and this rapid matching occurs within 2 min. Thus, fruit flies can dynamically match conditioned behavior and memory levels to a change in reinforcement intensity.

  12. Genetics and neurobiology of aggression in Drosophila

    OpenAIRE

    Zwarts, Liesbeth; Versteven, Marijke; Callaerts, Patrick

    2012-01-01

    Aggressive behavior is widely present throughout the animal kingdom and is crucial to ensure survival and reproduction. Aggressive actions serve to acquire territory, food, or mates and in defense against predators or rivals; while in some species these behaviors are involved in establishing a social hierarchy. Aggression is a complex behavior, influenced by a broad range of genetic and environmental factors. Recent studies in Drosophila provide insight into the genetic basis and control of a...

  13. Structure and Development of Glia in Drosophila

    OpenAIRE

    Hartenstein, Volker

    2011-01-01

    Insect glia represents a conspicuous and diverse population of cells and plays a role in controlling neuronal progenitor proliferation, axonal growth, neuronal differentiation and maintenance, and neuronal function. Genetic studies in Drosophila have elucidated many aspects of glial structure, function and development. Just as in vertebrates, it appears as if different classes of glial cells are specialized for different functions. Based on topology and cell shape, glial cells of the central ...

  14. Ultrastructural Analysis of Myoblast Fusion in Drosophila

    OpenAIRE

    Zhang, Shiliang; Chen, Elizabeth H.

    2008-01-01

    Myoblast fusion in Drosophila has become a powerful genetic system with which to unravel the mechanisms underlying cell fusion. The identification of important components of myoblast fusion by genetic analysis has led to a molecular pathway toward our understanding of this cellular process. In addition to the application of immunohistochemistry and live imaging techniques to visualize myoblast fusion at the light microscopic level, ultrastructural analysis using electron microscopy remains an...

  15. Organization Of The Drosophila Larval Visual Circuit

    OpenAIRE

    Fritsch, Pauline; Gendre, Nanae; Maier, Larisa; Fetter, Rick; Schneider-Mizell, Casey; Truman, James; Zlatic, Marta; Cardona, Albert; Larderet, Ivan; Sprecher, Simon

    2017-01-01

    Visual systems transduce, process and transmit light-dependent environmental cues. Computation of visual features depends on the types of photoreceptor neurons (PR) present, the organization of the eye and the wiring of the underlying neural circuit. Here, we describe the circuit architecture of the visual system of Drosophila larvae by mapping the synaptic wiring diagram and neurotransmitters. By contacting different targets, the two larval PR-subtypes create parallel circuits potentially un...

  16. A Drosophila Model to Image Phagosome Maturation

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    Douglas A. Brooks

    2013-03-01

    Full Text Available Phagocytosis involves the internalization of extracellular material by invagination of the plasma membrane to form intracellular vesicles called phagosomes, which have functions that include pathogen degradation. The degradative properties of phagosomes are thought to be conferred by sequential fusion with endosomes and lysosomes; however, this maturation process has not been studied in vivo. We employed Drosophila hemocytes, which are similar to mammalian professional macrophages, to establish a model of phagosome maturation. Adult Drosophila females, carrying transgenic Rab7-GFP endosome and Lamp1-GFP lysosome markers, were injected with E. coli DH5α and the hemocytes were collected at 15, 30, 45 and 60 minutes after infection. In wild-type females, E. coli were detected within enlarged Rab7-GFP positive phagosomes at 15 to 45 minutes after infection; and were also observed in enlarged Lamp1-GFP positive phagolysosomes at 45 minutes. Two-photon imaging of hemocytes in vivo confirmed this vesicle morphology, including enlargement of Rab7-GFP and Lamp1-GFP structures that often appeared to protrude from hemocytes. The interaction of endosomes and lysosomes with E. coli phagosomes observed in Drosophila hemocytes was consistent with that previously described for phagosome maturation in human ex vivo macrophages. We also tested our model as a tool for genetic analysis using 14-3-3e mutants, and demonstrated altered phagosome maturation with delayed E. coli internalization, trafficking and/or degradation. These findings demonstrate that Drosophila hemocytes provide an appropriate, genetically amenable, model for analyzing phagosome maturation ex vivo and in vivo.

  17. Adaptive dynamics of cuticular hydrocarbons in Drosophila

    Czech Academy of Sciences Publication Activity Database

    Rajpurohit, S.; Hanus, Robert; Vrkoslav, Vladimír; Behrman, E. L.; Bergland, A. O.; Petrov, D.; Cvačka, Josef; Schmidt, P. S.

    2017-01-01

    Roč. 30, č. 1 (2017), s. 66-80 ISSN 1010-061X R&D Projects: GA ČR GAP206/12/1093 Institutional support: RVO:61388963 Keywords : cuticular hydrocarbons * Drosophila * experimental evolution * spatiotemporal variation * thermal plasticity Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biology (theoretical, mathematical, thermal, cryobiology, biological rhythm), Evolutionary biology Impact factor: 2.792, year: 2016 http://onlinelibrary.wiley.com/doi/10.1111/jeb.12988/full

  18. Neurophysiology of Drosophila Models of Parkinson's Disease

    OpenAIRE

    West, Ryan J. H.; Furmston, Rebecca; Williams, Charles A. C.; Elliott, Christopher J. H.

    2015-01-01

    We provide an insight into the role Drosophila has played in elucidating neurophysiological perturbations associated with Parkinson's disease- (PD-) related genes. Synaptic signalling deficits are observed in motor, central, and sensory systems. Given the neurological impact of disease causing mutations within these same genes in humans the phenotypes observed in fly are of significant interest. As such we observe four unique opportunities provided by fly nervous system models of Parkinson's ...

  19. Three-dimensional imaging of Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Leeanne McGurk

    2007-09-01

    Full Text Available The major hindrance to imaging the intact adult Drosophila is that the dark exoskeleton makes it impossible to image through the cuticle. We have overcome this obstacle and describe a method whereby the internal organs of adult Drosophila can be imaged in 3D by bleaching and clearing the adult and then imaging using a technique called optical projection tomography (OPT. The data is displayed as 2D optical sections and also in 3D to provide detail on the shape and structure of the adult anatomy.We have used OPT to visualize in 2D and 3D the detailed internal anatomy of the intact adult Drosophila. In addition this clearing method used for OPT was tested for imaging with confocal microscopy. Using OPT we have visualized the size and shape of neurodegenerative vacuoles from within the head capsule of flies that suffer from age-related neurodegeneration due to a lack of ADAR mediated RNA-editing. In addition we have visualized tau-lacZ expression in 2D and 3D. This shows that the wholemount adult can be stained without any manipulation and that this stain penetrates well as we have mapped the localization pattern with respect to the internal anatomy.We show for the first time that the intact adult Drosophila can be imaged in 3D using OPT, also we show that this method of clearing is also suitable for confocal microscopy to image the brain from within the intact head. The major advantage of this is that organs can be represented in 3D in their natural surroundings. Furthermore optical sections are generated in each of the three planes and are not prone to the technical limitations that are associated with manual sectioning. OPT can be used to dissect mutant phenotypes and to globally map gene expression in both 2D and 3D.

  20. Studies on maternal repair in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Mendelson, D.

    1976-01-01

    The work reported in this thesis is mainly concerned with studies on the nature of the repair mechanism(s) operating in Drosophila oocytes, and which act on chromosome damage induced by X-irradiation of post-meiotic male germ-cells. Caffeine treatment of the females has been used as an analytical tool to gain an insight into the nature of this repair mechanism and its genetic basis

  1. ‘Peer pressure’ in larval Drosophila?

    Directory of Open Access Journals (Sweden)

    Thomas Niewalda

    2014-06-01

    Full Text Available Understanding social behaviour requires a study case that is simple enough to be tractable, yet complex enough to remain interesting. Do larval Drosophila meet these requirements? In a broad sense, this question can refer to effects of the mere presence of other larvae on the behaviour of a target individual. Here we focused in a more strict sense on ‘peer pressure’, that is on the question of whether the behaviour of a target individual larva is affected by what a surrounding group of larvae is doing. We found that innate olfactory preference of a target individual was neither affected (i by the level of innate olfactory preference in the surrounding group nor (ii by the expression of learned olfactory preference in the group. Likewise, learned olfactory preference of a target individual was neither affected (iii by the level of innate olfactory preference of the surrounding group nor (iv by the learned olfactory preference the group was expressing. We conclude that larval Drosophila thus do not take note of specifically what surrounding larvae are doing. This implies that in a strict sense, and to the extent tested, there is no social interaction between larvae. These results validate widely used en mass approaches to the behaviour of larval Drosophila.

  2. An automated paradigm for Drosophila visual psychophysics.

    Science.gov (United States)

    Evans, Oliver; Paulk, Angelique C; van Swinderen, Bruno

    2011-01-01

    Mutations that cause learning and memory defects in Drosophila melanogaster have been found to also compromise visual responsiveness and attention. A better understanding of attention-like defects in such Drosophila mutants therefore requires a more detailed characterization of visual responsiveness across a range of visual parameters. We designed an automated behavioral paradigm for efficiently dissecting visual responsiveness in Drosophila. Populations of flies walk through multiplexed serial choice mazes while being exposed to moving visuals displayed on computer monitors, and infra-red fly counters at the end of each maze automatically score the responsiveness of a strain. To test our new design, we performed a detailed comparison between wild-type flies and a learning and memory mutant, dunce(1). We first confirmed that the learning mutant dunce(1) displays increased responsiveness to a black/green moving grating compared to wild type in this new design. We then extended this result to explore responses to a wide range of psychophysical parameters for moving gratings (e.g., luminosity, contrast, spatial frequency, velocity) as well as to a different stimulus, moving dots. Finally, we combined these visuals (gratings versus dots) in competition to investigate how dunce(1) and wild-type flies respond to more complex and conflicting motion effects. We found that dunce(1) responds more strongly than wild type to high contrast and highly structured motion. This effect was found for simple gratings, dots, and combinations of both stimuli presented in competition.

  3. An automated paradigm for Drosophila visual psychophysics.

    Directory of Open Access Journals (Sweden)

    Oliver Evans

    Full Text Available BACKGROUND: Mutations that cause learning and memory defects in Drosophila melanogaster have been found to also compromise visual responsiveness and attention. A better understanding of attention-like defects in such Drosophila mutants therefore requires a more detailed characterization of visual responsiveness across a range of visual parameters. METHODOLOGY/PRINCIPAL FINDINGS: We designed an automated behavioral paradigm for efficiently dissecting visual responsiveness in Drosophila. Populations of flies walk through multiplexed serial choice mazes while being exposed to moving visuals displayed on computer monitors, and infra-red fly counters at the end of each maze automatically score the responsiveness of a strain. To test our new design, we performed a detailed comparison between wild-type flies and a learning and memory mutant, dunce(1. We first confirmed that the learning mutant dunce(1 displays increased responsiveness to a black/green moving grating compared to wild type in this new design. We then extended this result to explore responses to a wide range of psychophysical parameters for moving gratings (e.g., luminosity, contrast, spatial frequency, velocity as well as to a different stimulus, moving dots. Finally, we combined these visuals (gratings versus dots in competition to investigate how dunce(1 and wild-type flies respond to more complex and conflicting motion effects. CONCLUSIONS/SIGNIFICANCE: We found that dunce(1 responds more strongly than wild type to high contrast and highly structured motion. This effect was found for simple gratings, dots, and combinations of both stimuli presented in competition.

  4. Neurophysiology of Drosophila models of Parkinson's disease.

    Science.gov (United States)

    West, Ryan J H; Furmston, Rebecca; Williams, Charles A C; Elliott, Christopher J H

    2015-01-01

    We provide an insight into the role Drosophila has played in elucidating neurophysiological perturbations associated with Parkinson's disease- (PD-) related genes. Synaptic signalling deficits are observed in motor, central, and sensory systems. Given the neurological impact of disease causing mutations within these same genes in humans the phenotypes observed in fly are of significant interest. As such we observe four unique opportunities provided by fly nervous system models of Parkinson's disease. Firstly, Drosophila models are instrumental in exploring the mechanisms of neurodegeneration, with several PD-related mutations eliciting related phenotypes including sensitivity to energy supply and vesicular deformities. These are leading to the identification of plausible cellular mechanisms, which may be specific to (dopaminergic) neurons and synapses rather than general cellular phenotypes. Secondly, models show noncell autonomous signalling within the nervous system, offering the opportunity to develop our understanding of the way pathogenic signalling propagates, resembling Braak's scheme of spreading pathology in PD. Thirdly, the models link physiological deficits to changes in synaptic structure. While the structure-function relationship is complex, the genetic tractability of Drosophila offers the chance to separate fundamental changes from downstream consequences. Finally, the strong neuronal phenotypes permit relevant first in vivo drug testing.

  5. Transcriptional regulation of xenobiotic detoxification in Drosophila

    Science.gov (United States)

    Misra, Jyoti R.; Horner, Michael A.; Lam, Geanette; Thummel, Carl S.

    2011-01-01

    Living organisms, from bacteria to humans, display a coordinated transcriptional response to xenobiotic exposure, inducing enzymes and transporters that facilitate detoxification. Several transcription factors have been identified in vertebrates that contribute to this regulatory response. In contrast, little is known about this pathway in insects. Here we show that the Drosophila Nrf2 (NF-E2-related factor 2) ortholog CncC (cap ‘n’ collar isoform-C) is a central regulator of xenobiotic detoxification responses. A binding site for CncC and its heterodimer partner Maf (muscle aponeurosis fibromatosis) is sufficient and necessary for robust transcriptional responses to three xenobiotic compounds: phenobarbital (PB), chlorpromazine, and caffeine. Genetic manipulations that alter the levels of CncC or its negative regulator, Keap1 (Kelch-like ECH-associated protein 1), lead to predictable changes in xenobiotic-inducible gene expression. Transcriptional profiling studies reveal that more than half of the genes regulated by PB are also controlled by CncC. Consistent with these effects on detoxification gene expression, activation of the CncC/Keap1 pathway in Drosophila is sufficient to confer resistance to the lethal effects of the pesticide malathion. These studies establish a molecular mechanism for the regulation of xenobiotic detoxification in Drosophila and have implications for controlling insect populations and the spread of insect-borne human diseases. PMID:21896655

  6. The Ran pathway in Drosophila melanogaster mitosis

    Directory of Open Access Journals (Sweden)

    James G Wakefield

    2015-11-01

    Full Text Available Over the last two decades, the small GTPase Ran has emerged as a central regulator of both mitosis and meiosis, particularly in the generation, maintenance and regulation of the microtubule (MT-based bipolar spindle. Ran-regulated pathways in mitosis bear many similarities to the well-characterized functions of Ran in nuclear transport and, as with transport, the majority of these mitotic effects are mediated through affecting the physical interaction between karyopherins and Spindle Assembly Factors (SAFs - a loose term describing proteins or protein complexes involved in spindle assembly through promoting nucleation, stabilization, and/or depolymerization of MTs, through anchoring MTs to specific structures such as centrosomes, chromatin or kinetochores, or through sliding MTs along each other to generate the force required to achieve bipolarity. As such, the Ran-mediated pathway represents a crucial functional module within the wider spindle assembly landscape. Research into mitosis using the model organism Drosophila melanogaster has contributed substantially to our understanding of centrosome and spindle function. However, in comparison to mammalian systems, very little is known about the contribution of Ran-mediated pathways in Drosophila mitosis. This article sets out to summarize our understanding of the roles of the Ran pathway components in Drosophila mitosis, focusing on the syncytial blastoderm embryo, arguing that, far from being superfluous, it can provide important insights into the conserved functions on Ran during spindle formation.

  7. Pervasive natural selection in the Drosophila genome?

    Directory of Open Access Journals (Sweden)

    Guy Sella

    2009-06-01

    Full Text Available Over the past four decades, the predominant view of molecular evolution saw little connection between natural selection and genome evolution, assuming that the functionally constrained fraction of the genome is relatively small and that adaptation is sufficiently infrequent to play little role in shaping patterns of variation within and even between species. Recent evidence from Drosophila, reviewed here, suggests that this view may be invalid. Analyses of genetic variation within and between species reveal that much of the Drosophila genome is under purifying selection, and thus of functional importance, and that a large fraction of coding and noncoding differences between species are adaptive. The findings further indicate that, in Drosophila, adaptations may be both common and strong enough that the fate of neutral mutations depends on their chance linkage to adaptive mutations as much as on the vagaries of genetic drift. The emerging evidence has implications for a wide variety of fields, from conservation genetics to bioinformatics, and presents challenges to modelers and experimentalists alike.

  8. Tet protein function during Drosophila development.

    Directory of Open Access Journals (Sweden)

    Fei Wang

    Full Text Available The TET (Ten-eleven translocation 1, 2 and 3 proteins have been shown to function as DNA hydroxymethylases in vertebrates and their requirements have been documented extensively. Recently, the Tet proteins have been shown to also hydroxylate 5-methylcytosine in RNA. 5-hydroxymethylcytosine (5hmrC is enriched in messenger RNA but the function of this modification has yet to be elucidated. Because Cytosine methylation in DNA is barely detectable in Drosophila, it serves as an ideal model to study the biological function of 5hmrC. Here, we characterized the temporal and spatial expression and requirement of Tet throughout Drosophila development. We show that Tet is essential for viability as Tet complete loss-of-function animals die at the late pupal stage. Tet is highly expressed in neuronal tissues and at more moderate levels in somatic muscle precursors in embryos and larvae. Depletion of Tet in muscle precursors at early embryonic stages leads to defects in larval locomotion and late pupal lethality. Although Tet knock-down in neuronal tissue does not cause lethality, it is essential for neuronal function during development through its affects upon locomotion in larvae and the circadian rhythm of adult flies. Further, we report the function of Tet in ovarian morphogenesis. Together, our findings provide basic insights into the biological function of Tet in Drosophila, and may illuminate observed neuronal and muscle phenotypes observed in vertebrates.

  9. Synthesization and characterization of FeS2 by mechanical alloying for Na/FeS2 cell.

    Science.gov (United States)

    Liu, Xiaojing; Kang, Sang-Dae; Kim, Jong-Seon; Ahn, In-Shup; Ahn, Hyo-Jun

    2012-02-01

    In this study, the FeS2 fine compound powders were synthesized by mechanical alloying (MA) for 15 hrs and stearic acid was added as PCA (Process Control Agent) to prevent the excessive cold welding and agglomeration. For the purpose of ulteriorly reducing the particle size to improve the contact areas between the active materials and conducting agents, the wet ball milling process was applied by employing normal hexane (C6H14) as the milling solvent. The mean particle size of FeS2 powders about 1.14 microm were obtained after 24 hrs wet ball milling. The powders were characterized by FE-SEM, XRD, TEM and EDS. To compare the influence of particle size on the properties of charge/discharge, the same electrolyte was employed for both tests by dissolving 1M NaCF3SO3 (sodium trifluoromethanesulfonate) in a liquid of TEGDME (tetraethylene glycol dimethylether). The first discharge capacity of Na/FeS2 cell made by dry ball milled powders was 440 mAh/g with a plateau potential at approximately 1.25 V versus Na/Na+ and 260 mAh/g at the 25th cycle at room temperature. Meanwhile, the initial discharge capacity of Na/FeS2 cell made by wet ball milled powders was 614 mAh/g with the same discharge plateau potential and retained 385 mAh/g at the 25th cycle. And the discharge capacity for wet milled system decreased continuously by repeated charge/discharge cycling in the first 20 cycles and has little change after 60 cycles, which means the good cycling properties, remaining half of its initial discharge capacity of 320 mAh/g even after 100 cycles.

  10. Synthesis And Electrochemical Characteristics Of Mechanically Alloyed Anode Materials SnS2 For Li/SnS2 Cells

    Directory of Open Access Journals (Sweden)

    Hong J.H.

    2015-06-01

    Full Text Available With the increasing demand for efficient and economic energy storage, tin disulfide (SnS2, as one of the most attractive anode candidates for the next generation high-energy rechargeable Li-ion battery, have been paid more and more attention because of its high theoretical energy density and cost effectiveness. In this study, a new, simple and effective process, mechanical alloying (MA, has been developed for preparing fine anode material tin disulfides, in which ammonium chloride (AC, referred to as process control agents (PCAs, were used to prevent excessive cold-welding and accelerate the synthesis rates to some extent. Meanwhile, in order to decrease the mean size of SnS2 powder particles and improve the contact areas between the active materials, wet milling process was also conducted with normal hexane (NH as a solvent PCA. The prepared powders were both characterized by X-ray diffraction, Field emission-scanning electron microscopeand particle size analyzer. Finally, electrochemical measurements for Li/SnS2 cells were takenat room temperature, using a two-electrode cell assembled in an argon-filled glove box and the electrolyte of 1M LiPF6 in a mixture of ethylene carbonate(EC/dimethylcarbonate (DMC/ethylene methyl carbonate (EMC (volume ratio of 1:1:1.

  11. Synthesis and Characterization of the Quaternary Thio-aluminogermanates A(AlS2)(GeS2) (A = Na, K)

    KAUST Repository

    Al-Bloushi, Mohammed

    2015-05-27

    The quaternary thioaluminogermanates Na(AlS2)(GeS2) (1) and K(AlS2)(GeS2) (2) crystallize in the tetragonal space group I4/mcm (no. 140) with unit cell parameters a = 7.4274(11) Å, c = 5.8560(12) Å for Na(AlS2)(GeS2) and a = 7.8826(2) Å, c = 5.8642(4) Å for K(AlS2)(GeS2). The crystal structure comprises of one-dimensional [(AlS2)(GeS2)]- anionic chains with Al and Ge sharing the tetrahedral site. The alkali metal cations fill the square antiprismatic voids between chains. Both 1 and 2 are semiconductors with bandgap of around 3.6 eV and 3.5 eV, respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Exfoliated MoS2 in Water without Additives.

    Directory of Open Access Journals (Sweden)

    Viviane Forsberg

    Full Text Available Many solution processing methods of exfoliation of layered materials have been studied during the last few years; most of them are based on organic solvents or rely on surfactants and other funtionalization agents. Pure water should be an ideal solvent, however, it is generally believed, based on solubility theories that stable dispersions of water could not be achieved and systematic studies are lacking. Here we describe the use of water as a solvent and the stabilization process involved therein. We introduce an exfoliation method of molybdenum disulfide (MoS2 in pure water at high concentration (i.e., 0.14 ± 0.01 g L-1. This was achieved by thinning the bulk MoS2 by mechanical exfoliation between sand papers and dispersing it by liquid exfoliation through probe sonication in water. We observed thin MoS2 nanosheets in water characterized by TEM, AFM and SEM images. The dimensions of the nanosheets were around 200 nm, the same range obtained in organic solvents. Electrophoretic mobility measurements indicated that electrical charges may be responsible for the stabilization of the dispersions. A probability decay equation was proposed to compare the stability of these dispersions with the ones reported in the literature. Water can be used as a solvent to disperse nanosheets and although the stability of the dispersions may not be as high as in organic solvents, the present method could be employed for a number of applications where the dispersions can be produced on site and organic solvents are not desirable.

  13. Exciton transport phenomena in monolayer MoS2

    Science.gov (United States)

    Onga, Masaru; Zhang, Yijin; Ideue, Toshiya; Iwasa, Yoshihiro

    Monolayer transition metal dichalcogenides exhibit unique optical phenomena owing to the two-dimensional structure and valley degree of freedom. Many researchers have revealed that excitonic states play an important role in optical response, and have observed the diffusion transport of excitons in this system at room temperature. Here we report exciton transport phenomena in monolayer MoS2 at low temperature through photoluminescence mapping. Our results can provide us a new platform for exciton-based optoelectronics with valley degrees of freedom.

  14. Genetic monitoring of irradiated Drosophila populations treated with antimutagen melanine

    International Nuclear Information System (INIS)

    Mosseh, I.B.; Savchenko, V.K.; Lyakh, I.P.

    1986-01-01

    It was shown that viability of irradiated Drosophila is, on an average, lower than in intact populations. The fertility first decreases then increases exceeding the control level. Melanine added to the diet increases fertility and viability of both exposed and intact Drosophila populations

  15. Drosophila suzukii population response to environment and management strategies

    Science.gov (United States)

    Spotted wing drosophila, Drosophila suzukii, quickly emerged as a devastating invasive pest of small and stone fruits in the Americas and Europe. To better understand the population dynamics of D. suzukii, we reviewed recent work on juvenile development, adult reproduction, and seasonal variation in...

  16. First foreign exploration for asian parasitoids of Drosophila suzukii

    Science.gov (United States)

    The invasive spotted wing drosophila, Drosophila suzukii Matsumura (Dipt.: Drosophilidae), is a native of East Asia and is now widely established in North America and Europe, where it is a serious pest of small and stone fruit crops. The lack of effective indigenous parasitoids of D. suzukii in the ...

  17. Drosophila Courtship Conditioning As a Measure of Learning and Memory

    NARCIS (Netherlands)

    Koemans, T.S.; Oppitz, C.; Donders, R.; Bokhoven, H. van; Schenck, A.; Keleman, K.; Kramer, J.M.

    2017-01-01

    Many insights into the molecular mechanisms underlying learning and memory have been elucidated through the use of simple behavioral assays in model organisms such as the fruit fly, Drosophila melanogaster. Drosophila is useful for understanding the basic neurobiology underlying cognitive deficits

  18. Medium-term changes in Drosophila subobscura chromosomal ...

    Indian Academy of Sciences (India)

    2015-06-02

    Jun 2, 2015 ... [Zivanovic G., Arenas C. and Mestres F. 2015 Medium-term changes in Drosophila subobscura chromosomal inversion polymorphism: a possible relation with global warming? J. Genet. 94, 343–346]. Introduction. Drosophila subobscura is a species with a rich chromosomal polymorphism for inversions.

  19. Ultradian rhythm unmasked in the Pdf clock mutant of Drosophila

    Indian Academy of Sciences (India)

    2014-07-20

    Jul 20, 2014 ... temperature compensated. Our results suggest that Drosophila has an endogenous ultradian oscillator that is masked by circadian rhythmic behaviours. [Seki Y and Tanimura T 2014 Ultradian rhythm unmasked in the Pdf clock mutant of Drosophila. J. Biosci. 39 585-594]. DOI 10.1007/s12038-014-9450-z.

  20. Ionizing radiation causes the stress response in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Gruntenko, N.E.; Zakharenko, L.P.; Raushenbakh, I.Yu.

    1998-01-01

    Potentiality of the stress-reaction arising in Drosophila melanogaster under gamma-irradiation of the source with 137 Cs (irradiation dose is 10 Gy , radiation dose rate amounts 180 c Gy/min) is studied. It is shown that radiation induces the stress-reaction in Drosophila resulting in alterations in energetic metabolism (biogenic amines metabolic system) and in reproductive function [ru

  1. Status of research on Drosophila ananassae at global level

    Indian Academy of Sciences (India)

    Abstract. Drosophila, a dipteran insect, has been found to be the best biological model for different kinds of studies. D melanogaster was first described by Meigen in 1830, is most extensively studied species of the genus Drosophila and a number of investigations employing this species have been documented in areas ...

  2. The developmental transcriptome of Drosophila melanogaster

    Energy Technology Data Exchange (ETDEWEB)

    University of Connecticut; Graveley, Brenton R.; Brooks, Angela N.; Carlson, Joseph W.; Duff, Michael O.; Landolin, Jane M.; Yang, Li; Artieri, Carlo G.; van Baren, Marijke J.; Boley, Nathan; Booth, Benjamin W.; Brown, James B.; Cherbas, Lucy; Davis, Carrie A.; Dobin, Alex; Li, Renhua; Lin, Wei; Malone, John H.; Mattiuzzo, Nicolas R.; Miller, David; Sturgill, David; Tuch, Brian B.; Zaleski, Chris; Zhang, Dayu; Blanchette, Marco; Dudoit, Sandrine; Eads, Brian; Green, Richard E.; Hammonds, Ann; Jiang, Lichun; Kapranov, Phil; Langton, Laura; Perrimon, Norbert; Sandler, Jeremy E.; Wan, Kenneth H.; Willingham, Aarron; Zhang, Yu; Zou, Yi; Andrews, Justen; Bicke, Peter J.; Brenner, Steven E.; Brent, Michael R.; Cherbas, Peter; Gingeras, Thomas R.; Hoskins, Roger A.; Kaufman, Thomas C.; Oliver, Brian; Celniker, Susan E.

    2010-12-02

    Drosophila melanogaster is one of the most well studied genetic model organisms; nonetheless, its genome still contains unannotated coding and non-coding genes, transcripts, exons and RNA editing sites. Full discovery and annotation are pre-requisites for understanding how the regulation of transcription, splicing and RNA editing directs the development of this complex organism. Here we used RNA-Seq, tiling microarrays and cDNA sequencing to explore the transcriptome in 30 distinct developmental stages. We identified 111,195 new elements, including thousands of genes, coding and non-coding transcripts, exons, splicing and editing events, and inferred protein isoforms that previously eluded discovery using established experimental, prediction and conservation-based approaches. These data substantially expand the number of known transcribed elements in the Drosophila genome and provide a high-resolution view of transcriptome dynamics throughout development. Drosophila melanogaster is an important non-mammalian model system that has had a critical role in basic biological discoveries, such as identifying chromosomes as the carriers of genetic information and uncovering the role of genes in development. Because it shares a substantial genic content with humans, Drosophila is increasingly used as a translational model for human development, homeostasis and disease. High-quality maps are needed for all functional genomic elements. Previous studies demonstrated that a rich collection of genes is deployed during the life cycle of the fly. Although expression profiling using microarrays has revealed the expression of, 13,000 annotated genes, it is difficult to map splice junctions and individual base modifications generated by RNA editing using such approaches. Single-base resolution is essential to define precisely the elements that comprise the Drosophila transcriptome. Estimates of the number of transcript isoforms are less accurate than estimates of the number of genes

  3. Rhodopsin 7–The unusual Rhodopsin in Drosophila

    Directory of Open Access Journals (Sweden)

    Pingkalai R. Senthilan

    2016-09-01

    Full Text Available Rhodopsins are the major photopigments in the fruit fly Drosophila melanogaster. Drosophila express six well-characterized Rhodopsins (Rh1–Rh6 with distinct absorption maxima and expression pattern. In 2000, when the Drosophila genome was published, a novel Rhodopsin gene was discovered: Rhodopsin 7 (Rh7. Rh7 is highly conserved among the Drosophila genus and is also found in other arthropods. Phylogenetic trees based on protein sequences suggest that the seven Drosophila Rhodopsins cluster in three different groups. While Rh1, Rh2 and Rh6 form a “vertebrate-melanopsin-type”–cluster, and Rh3, Rh4 and Rh5 form an “insect-type”-Rhodopsin cluster, Rh7 seem to form its own cluster. Although Rh7 has nearly all important features of a functional Rhodopsin, it differs from other Rhodopsins in its genomic and structural properties, suggesting it might have an overall different role than other known Rhodopsins.

  4. Intestinal stem cells in the adult Drosophila midgut

    International Nuclear Information System (INIS)

    Jiang, Huaqi; Edgar, Bruce A.

    2011-01-01

    Drosophila has long been an excellent model organism for studying stem cell biology. Notably, studies of Drosophila's germline stem cells have been instrumental in developing the stem cell niche concept. The recent discovery of somatic stem cells in adult Drosophila, particularly the intestinal stem cells (ISCs) of the midgut, has established Drosophila as an exciting model to study stem cell-mediated adult tissue homeostasis and regeneration. Here, we review the major signaling pathways that regulate the self-renewal, proliferation and differentiation of Drosophila ISCs, discussing how this regulation maintains midgut homeostasis and mediates regeneration of the intestinal epithelium after injury. -- Highlights: ► The homeostasis and regeneration of adult fly midguts are mediated by ISCs. ► Damaged enterocytes induce the proliferation of intestinal stem cells (ISC). ► EGFR and Jak/Stat signalings mediate compensatory ISC proliferation. ► Notch signaling regulates ISC self-renewal and differentiation.

  5. Drosophila melanogaster as a model organism to study nanotoxicity.

    Science.gov (United States)

    Ong, Cynthia; Yung, Lin-Yue Lanry; Cai, Yu; Bay, Boon-Huat; Baeg, Gyeong-Hun

    2015-05-01

    Drosophila melanogaster has been used as an in vivo model organism for the study of genetics and development since 100 years ago. Recently, the fruit fly Drosophila was also developed as an in vivo model organism for toxicology studies, in particular, the field of nanotoxicity. The incorporation of nanomaterials into consumer and biomedical products is a cause for concern as nanomaterials are often associated with toxicity in many in vitro studies. In vivo animal studies of the toxicity of nanomaterials with rodents and other mammals are, however, limited due to high operational cost and ethical objections. Hence, Drosophila, a genetically tractable organism with distinct developmental stages and short life cycle, serves as an ideal organism to study nanomaterial-mediated toxicity. This review discusses the basic biology of Drosophila, the toxicity of nanomaterials, as well as how the Drosophila model can be used to study the toxicity of various types of nanomaterials.

  6. Detecting novel low-abundant transcripts in Drosophila

    DEFF Research Database (Denmark)

    Lee, Sanggyu; Bao, Jingyue; Zhou, Guolin

    2005-01-01

    Increasing evidence suggests that low-abundant transcripts may play fundamental roles in biological processes. In an attempt to estimate the prevalence of low-abundant transcripts in eukaryotic genomes, we performed a transcriptome analysis in Drosophila using the SAGE technique. We collected 244......,313 SAGE tags from transcripts expressed in Drosophila embryonic, larval, pupae, adult, and testicular tissue. From these SAGE tags, we identified 40,823 unique SAGE tags. Our analysis showed that 55% of the 40,823 unique SAGE tags are novel without matches in currently known Drosophila transcripts...... in the Drosophila genome. Our study reveals the presence of a significant number of novel low-abundant transcripts in Drosophila, and highlights the need to isolate these novel low-abundant transcripts for further biological studies. Udgivelsesdato: 2005-Jun...

  7. Open Standards and Technologies in the S2S Framework

    Science.gov (United States)

    Maffei, A. R.; Rozell, E. A.; West, P.; Zednik, S.; Fox, P. A.

    2011-12-01

    The S2S Search Interface Framework provides tools and services to build customized user interfaces. It also serves as a focal point for repository managers to develop science data services and reusable components for search interfaces. The framework has been used to design a faceted browsing platform for web services, including OpenSearch and SAWSDL. This exemplar faceted browsing platform has been applied in our development of search interfaces for 1) an international open government dataset catalog and 2) a metadata catalog for biological and chemical oceanography. S2S was designed from the ground up using open standards and technologies. The framework was initially created to develop "data dashboard" interfaces on top of OpenSearch services, but has been generalized to support web services and standards with semantic annotation capabilities. We apply OWL, a W3C standard for ontologies on the Web, to create a vocabulary for the description of framework metadata. Our faceted browsing platform is heavily focused on the use of jQuery; we have created reusable user interface "widgets" that leverage OpenLayers and MapServer technology in geospatial selection and visualization, which can be used in this and future platforms. The use of open standards and technologies has enabled rapid iterations over software development lifecycles, and has kept the framework agile as new use cases and ideas have emerged.

  8. Production of large area layered MoS2 films

    International Nuclear Information System (INIS)

    Lemon, K.S.; Singh, A.; Taheri, E.; Jakovidis, G.

    2000-01-01

    Full text: The layered structure of transition metal di-chalcogenides makes this family of compounds of interest to industry because of their potential use as lubricants, photovoltaic materials or as catalysts. An important example of these compounds is Molybdenum Disulphide (MoS 2 ), which has been shown to have remarkable lubrication properties over a range of physical conditions, including pressures from high vacuum to atmospheric, and temperatures over the 100 - 700K range. This compound grows as hexagonal platelets which are arranged either perpendicular to the substrate, or parallel to it (i.e. forming layers). These two forms are known as type I and type II morphologies respectively. Type II MoS 2 is of interest to lubrication and photovoltaic applications because of its low friction and densities of minority carrier recombination centres. The production of large area films which are predominantly type II in nature, however, has not been easy, most attempts resulting in films which are a mixture of the two types. We report, for the first time, a technique that is capable of producing type II films in areas large enough to be useful. The method is based on vapour transport, and can produce smooth polycrystalline films of the order of 10 cm 2 . This presentation will describe the method in full detail. SEM results will be presented that show the layered growth of the hexagonal platelets. Results of X-ray diffraction analysis will confirm the single phase nature of the sample

  9. Few-Layered Mo(1-x)WxS2Hollow Nanospheres on Ni3S2Nanorod Heterostructure as Robust Electrocatalysts for Overall Water Splitting.

    Science.gov (United States)

    Zheng, Meiyong; Du, Jing; Hou, Baopu; Xu, Cai-Ling

    2017-08-09

    Owing to unique optical, electronic, and catalytic properties, MoS 2 have received increasing interest in electrochemical water splitting. Herein, few-layered Mo (1-x) W x S 2 hollow nanospheres-modified Ni 3 S 2 heterostructures are prepared through a facile hydrothermal method to further enhance the electrocatalytic performance of MoS 2 . The doping of W element optimizes the electronic structure of MoS 2 @Ni 3 S 2 thus improving the conductivity and charge-transfer ability of MoS 2 @Ni 3 S 2 . In addition, benefitting from the few-layered hollow structure of Mo (1-x) W x S 2 , the strong electronic interactions between Mo (1-x) W x S 2 and Ni 3 S 2 and the hierarchical structure of one-dimensional nanorods and three-dimensional Ni foam, massive active sites and fast ion and charge transportation are obtained. As a result, the optimized Mo (1-x) W x S 2 @Ni 3 S 2 heterostructure (Mo-W-S-2@Ni 3 S 2 ) achieves an extremely low overpotential of 98 mV for hydrogen evolution reaction and 285 mV for oxygen evolution reaction at 10 mA cm -2 in alkaline electrolyte. Particularly, using Mo-W-S-2@Ni 3 S 2 heterostructure as a bifunctional electrocatalyst, a cell voltage of 1.62 V is required to deliver a 10 mA cm -2 water splitting current density. In addition, the electrode can be maintained at 10 mA cm -2 for at least 50 h, indicating the excellent stability of Mo-W-S-2@Ni 3 S 2 heterostructure. Therefore, this development demonstrates an effective and feasible strategy to prepare highly efficient bifunctional electrocatalysts for overall water splitting.

  10. Rapid and highly accurate detection of Drosophila suzukii, spotted wing Drosophila (Diptera: Drosophilidae) by loop-mediated isothermal amplification assays

    Science.gov (United States)

    Drosophila suzukii, the spotted wing drosophila (SWD), is currently a major pest that causes severe economic losses to thin-skinned, small fruit growers in North America and Europe. The monitoring and early detection of SWD in the field is of the utmost importance for its proper management. Althou...

  11. Isolation of protease-free alcohol dehydrogenase (ADH) from Drosophila simulans and several homozygous and heterozygous Drosophila melanogaster variants

    NARCIS (Netherlands)

    Smilda, T; Lamme, DA; Collu, G; Jekel, PA; Reinders, P; Beintema, JJ

    The enzyme alcohol dehydrogenase (ADH) from several naturally occurring ADH variants of Drosophila melanogaster and Drosophila simulans Lc,as isolated. Affinity chromatography with the ligand Cibacron Blue and elution with NAD(+) showed similar behavior for D. melanogaster ADH-FF, ADH-71k, and D.

  12. Peptidergic control of a fruit crop pest: the spotted-wing drosophila, Drosophila suzukii

    Science.gov (United States)

    Neuropeptides play an important role in the regulation of feeding in insects and offer potential targets for the development of new chemicals to control insect pests. A pest that has attracted much recent attention is the highly invasive Drosophila suzukii, a polyphagous pest that can cause serious...

  13. Biological effects of radon in Drosophila; Efectos biologicos del radon en Drosophila

    Energy Technology Data Exchange (ETDEWEB)

    Pimentel P, A.E.; Tavera D, L.; Cruces M, M.P.; Arceo M, C.; Rosa D, M.E. de la

    1992-04-15

    The main objective of this investigation, is to study the biological effects of the Radon-222 at low dose in 'Drosophila melanogaster'. It is necessary to mention that these effects will analyze from the genetic point of view for: 1) To evaluate in which form the Radon-222 to low dose it influences in some genetic components of the adaptation in Drosophila, such as: fecundity, viability egg-adult and sex proportion. 2) To evaluate which is the genetic effect that induces the Radon to low dose by means of the SMART technique in Drosophila melanogaster, and this way to try of to identify which is the possible mechanism that causes the genetic damage to somatic level. The carried out investigation was divided in three stages: 1. Tests to the vacuum resistance. 2. Test of somatic mutation, and 3. Determination of the presence of radon daughters on the adult of Drosophila. It is necessary to point out that all the experiments were made by triplicate and in each one of them was placed detectors in preset places. Those obtained results are presented inside the 4 charts included in the present work. (Author)

  14. Strain engineering in monolayer WS2, MoS2, and the WS2/MoS2 heterostructure

    KAUST Repository

    He, Xin

    2016-10-27

    Mechanically exfoliated monolayers of WS2, MoS2 and their van der Waals heterostructure were fabricated on flexible substrate so that uniaxial tensile strain can be applied to the two-dimensional samples. The modification of the band structure under strain was investigated by micro-photoluminescence spectroscopy at room temperature as well as by first-principles calculations. Exciton and trion emissions were observed in both WS2 and the heterostructure at room temperature, and were redshifted by strain, indicating potential for applications in flexible electronics and optoelectronics.

  15. Definition of a RACK1 Interaction Network in Drosophila melanogaster Using SWATH-MS.

    Science.gov (United States)

    Kuhn, Lauriane; Majzoub, Karim; Einhorn, Evelyne; Chicher, Johana; Pompon, Julien; Imler, Jean-Luc; Hammann, Philippe; Meignin, Carine

    2017-07-05

    Receptor for Activated protein C kinase 1 (RACK1) is a scaffold protein that has been found in association with several signaling complexes, and with the 40S subunit of the ribosome. Using the model organism Drosophila melanogaster , we recently showed that RACK1 is required at the ribosome for internal ribosome entry site (IRES)-mediated translation of viruses. Here, we report a proteomic characterization of the interactome of RACK1 in Drosophila S2 cells. We carried out Label-Free quantitation using both Data-Dependent and Data-Independent Acquisition (DDA and DIA, respectively) and observed a significant advantage for the Sequential Window Acquisition of all THeoretical fragment-ion spectra (SWATH) method, both in terms of identification of interactants and quantification of low abundance proteins. These data represent the first SWATH spectral library available for Drosophila and will be a useful resource for the community. A total of 52 interacting proteins were identified, including several molecules involved in translation such as structural components of the ribosome, factors regulating translation initiation or elongation, and RNA binding proteins. Among these 52 proteins, 15 were identified as partners by the SWATH strategy only. Interestingly, these 15 proteins are significantly enriched for the functions translation and nucleic acid binding. This enrichment reflects the engagement of RACK1 at the ribosome and highlights the added value of SWATH analysis. A functional screen did not reveal any protein sharing the interesting properties of RACK1, which is required for IRES-dependent translation and not essential for cell viability. Intriguingly however, 10 of the RACK1 partners identified restrict replication of Cricket paralysis virus (CrPV), an IRES-containing virus. Copyright © 2017 Kuhn et al.

  16. Identification of a TPX2-like microtubule-associated protein in Drosophila.

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    Gohta Goshima

    Full Text Available Chromosome segregation during mitosis and meiosis relies on the spindle and the functions of numerous microtubule-associated proteins (MAPs. One of the best-studied spindle MAPs is the highly conserved TPX2, which has been reported to have characteristic intracellular dynamics and molecular activities, such as nuclear localisation in interphase, poleward movement in the metaphase spindle, microtubule nucleation, microtubule stabilisation, microtubule bundling, Aurora A kinase activation, kinesin-5 binding, and kinesin-12 recruitment. This protein has been shown to be essential for spindle formation in every cell type analysed so far. However, as yet, TPX2 homologues have not been found in the Drosophila genome. In this study, I found that the Drosophila protein Ssp1/Mei-38 has significant homology to TPX2. Sequence conservation was limited to the putative spindle microtubule-associated region of TPX2, and intriguingly, D-TPX2 (Ssp1/Mei-38 lacks Aurora A- and kinesin-5-binding domains, which are highly conserved in other animal and plant species, including many insects such as ants and bees. D-TPX2 uniformly localised to kinetochore microtubule-enriched regions of the metaphase spindle in the S2 cell line, and it had microtubule binding and bundling activities in vitro. In comparison with other systems, the contribution of D-TPX2 to cell division seems to be minor; live cell imaging of microtubules and chromosomes after RNAi knockdown identified significant delay in chromosome congression in only 18% of the cells. Thus, while this conserved spindle protein is present in Drosophila, other mechanisms may largely compensate for its spindle assembly and chromosome segregation functions.

  17. Identification of the Drosophila eIF4A gene as a target of the DREF transcription factor

    International Nuclear Information System (INIS)

    Ida, Hiroyuki; Yoshida, Hideki; Nakamura, Kumi; Yamaguchi, Masamitsu

    2007-01-01

    The DNA replication-related element-binding factor (DREF) regulates cell proliferation-related gene expression in Drosophila. We have carried out a genetic screening, taking advantage of the rough eye phenotype of transgenic flies that express full-length DREF in the eye imaginal discs and identified the eukaryotic initiation factor 4A (eIF4A) gene as a dominant suppressor of the DREF-induced rough eye phenotype. The eIF4A gene was here found to carry three DRE sequences, DRE1 (- 40 to - 47), DRE2 (- 48 to - 55), and DRE3 (- 267 to - 274) in its promoter region, these all being important for the eIF4A gene promoter activity in cultured Drosophila Kc cells and in living flies. Knockdown of DREF in Drosophila S2 cells decreased the eIF4A mRNA level and the eIF4A gene promoter activity. Furthermore, specific binding of DREF to genomic regions containing DRE sequences was demonstrated by chromatin immunoprecipitation assays using anti-DREF antibodies. Band mobility shift assays using Kc cell nuclear extracts revealed that DREF could bind to DRE1 and DRE3 sequences in the eIF4A gene promoter in vitro, but not to the DRE2 sequence. The results suggest that the eIF4A gene is under the control of the DREF pathway and DREF is therefore involved in the regulation of protein synthesis

  18. First record of spotted wing drosophila Drosophila suzukii (Diptera: Drosophilidae in Montenegro

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    Snježana Hrnčić

    2015-01-01

    Full Text Available The spotted wing drosophila Drosophila suzukii Matsumura (Diptera: Drosophilidae is an invasive pest originating from Southeast Asia. It was detected for the first time in Europe in 2008 (Spain and Italy and subsequently in other European countries. It is a highly polyphagous pest that infests healthy, ripening fruit and presents a serious threat to fruit production, particularly of soft skinned fruit. In the first half of October 2013, a new fruit fly species was unexpectedly detected in Tephri traps baited with the three-component female-biased attractant BioLure that is regularly used for monitoring the Mediterranean fruit fly Ceratitis capitata Wiedem. (Diptera: Tephritidae in Montenegro. Brief visual inspection identified the new species as the spotted wing drosophila D. suzukii. The pest was first recorded in several localities on the Montenegrin seacoast around Boka Kotor Bay. After the finding, all Drosophila specimens were collected from traps for further laboratory observation. A quick follow-up monitoring of other Tephri traps was carried out within the next few days on the rest of the seacoast (localities from Tivat to Ulcinj. Additionally, Tephri traps were set up around Lake Skadar and in the city of Podgorica, as well as on fresh fruit markets in Podgorica. The results of this preliminary study showed that D. suzukii was present in all surveyed locations and adults were captured until late December. Both sexes were found in traps with BioLure. Our data show that D. suzukii is present in southern parts of Montenegro and there is a serious threat of its further spreading, particularly towards northern parts of the country where the main raspberry and blueberry production is placed. The results also show that Tephri traps baited with BioLure can be used for detection and monitoring of spotted wing drosophila.

  19. Nematocytes: Discovery and characterization of a novel anculeate hemocyte in Drosophila falleni and Drosophila phalerata.

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    Julianna Bozler

    Full Text Available Immune challenges, such as parasitism, can be so pervasive and deleterious that they constitute an existential threat to a species' survival. In response to these ecological pressures, organisms have developed a wide array of novel behavioral, cellular, and molecular adaptations. Research into these immune defenses in model systems has resulted in a revolutionary understanding of evolution and functional biology. As the field has expanded beyond the limited number of model organisms our appreciation of evolutionary innovation and unique biology has widened as well. With this in mind, we have surveyed the hemolymph of several non-model species of Drosophila. Here we identify and describe a novel hemocyte, type-II nematocytes, found in larval stages of numerous Drosophila species. Examined in detail in Drosophila falleni and Drosophila phalerata, we find that these remarkable cells are distinct from previously described hemocytes due to their anucleate state (lacking a nucleus and unusual morphology. Type-II nematocytes are long, narrow cells with spindle-like projections extending from a cell body with high densities of mitochondria and microtubules, and exhibit the ability to synthesize proteins. These properties are unexpected for enucleated cells, and together with our additional characterization, we demonstrate that these type-II nematocytes represent a biological novelty. Surprisingly, despite the absence of a nucleus, we observe through live cell imaging that these cells remain motile with a highly dynamic cellular shape. Furthermore, these cells demonstrate the ability to form multicellular structures, which we suggest may be a component of the innate immune response to macro-parasites. In addition, live cell imaging points to a large nucleated hemocyte, type-I nematocyte, as the progenitor cell, leading to enucleation through a budding or asymmetrical division process rather than nuclear ejection: This study is the first to report such a

  20. Interlayer resistance of misoriented MoS2.

    Science.gov (United States)

    Zhou, Kuan; Wickramaratne, Darshana; Ge, Supeng; Su, Shanshan; De, Amrit; Lake, Roger K

    2017-04-19

    Interlayer misorientation in transition metal dichalcogenides alters their interlayer distance, total energy, electronic band structure, and vibrational modes, but its effect on the interlayer resistance is not known. This study analyzes the interlayer resistance of misoriented bilayer MoS 2 as a function of the misorientation angle, and it shows that interlayer misorientation exponentially increases the electron resistivity while leaving the hole resistivity almost unchanged. The physics, determined by the wave functions at the high symmetry points, are generic among the popular semiconducting transition metal dichalcogenides (TMDs). The asymmetrical effect of misorientation on the electron and hole transport may be exploited in the design and optimization of vertical transport devices such as a bipolar transistor. Density functional theory provides the interlayer coupling elements used for the resistivity calculations.

  1. An investigation of AdS2 backreaction and holography

    International Nuclear Information System (INIS)

    Engelsöy, Julius; Mertens, Thomas G.; Verlinde, Herman

    2016-01-01

    We investigate a dilaton gravity model in AdS 2 proposed by Almheiri and Polchinski http://dx.doi.org/10.1007/JHEP11(2015)014 and develop a 1d effective description in terms of a dynamical boundary time with a Schwarzian derivative action. We show that the effective model is equivalent to a 1d version of Liouville theory, and investigate its dynamics and symmetries via a standard canonical framework. We include the coupling to arbitrary conformal matter and analyze the effective action in the presence of possible sources. We compute commutators of local operators at large time separation, and match the result with the time shift due to a gravitational shockwave interaction. We study a black hole evaporation process and comment on the role of entropy in this model.

  2. OBTAINING AND PROPERTIES OF AgInS2 FILMS

    Directory of Open Access Journals (Sweden)

    M. A. Abdullaev

    2016-01-01

    Full Text Available Aim. The aim is to obtain AgInS2 films and study their electrical and optical properties.Methods. The samples of thin AgInS2 films for measurement were obtained by the method of magnetron sputtering with direct current. The structure, phase and elemental composition were studied using DRON-2 X-ray diffractometer (СuKа - radiation and the microscope LEO-1450 with EDS attachment for X-ray microanalysis. The optical transmittance and absorption were examined using MDR-2 monochromator in the wavelength range of 400-800 nm with the Keitley electrometer and FD-10G; we applied the spectral resolution of ± 1 meV. The electrical conductivity, Hall effect was measured by the four-point probe method with indium ohmic contacts. Measurements were carried out in the temperature range of 77-400 K.Findings. We obtained indium disulfide and silver films with the thickness of up to 1 μm on quartz substrates by magnetron sputtering. It is shown that increasing the substrate temperature to about 450 0С allows to obtain single phase film with a chalcopyrite structure with a band gap of 1.88 eV and high absorption coefficient (>104см-1.Conclusions. The possibility of obtaining films in a wide range of the electrical resistance and variation of the electrical parameters at constant stoichiometry is of interest for efficient technologies of phototransduction.

  3. The Fz-Dsh planar cell polarity pathway induces oriented cell division via Mud/NuMA in Drosophila and zebrafish.

    Science.gov (United States)

    Ségalen, Marion; Johnston, Christopher A; Martin, Charlotte A; Dumortier, Julien G; Prehoda, Kenneth E; David, Nicolas B; Doe, Chris Q; Bellaïche, Yohanns

    2010-11-16

    The Frizzled receptor and Dishevelled effector regulate mitotic spindle orientation in both vertebrates and invertebrates, but how Dishevelled orients the mitotic spindle is unknown. Using the Drosophila S2 cell "induced polarity" system, we find that Dishevelled cortical polarity is sufficient to orient the spindle and that Dishevelled's DEP domain mediates this function. This domain binds a C-terminal domain of Mud (the Drosophila NuMA ortholog), and Mud is required for Dishevelled-mediated spindle orientation. In Drosophila, Frizzled-Dishevelled planar cell polarity (PCP) orients the sensory organ precursor (pI) spindle along the anterior-posterior axis. We show that Dishevelled and Mud colocalize at the posterior cortex of pI, Mud localization at the posterior cortex requires Dsh, and Mud loss-of-function randomizes spindle orientation. During zebrafish gastrulation, the Wnt11-Frizzled-Dishevelled PCP pathway orients spindles along the animal-vegetal axis, and reducing NuMA levels disrupts spindle orientation. Overall, we describe a Frizzled-Dishevelled-NuMA pathway that orients division from Drosophila to vertebrates. Copyright © 2010 Elsevier Inc. All rights reserved.

  4. Whole genome phylogenies for multiple Drosophila species

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    Seetharam Arun

    2012-12-01

    Full Text Available Abstract Background Reconstructing the evolutionary history of organisms using traditional phylogenetic methods may suffer from inaccurate sequence alignment. An alternative approach, particularly effective when whole genome sequences are available, is to employ methods that don’t use explicit sequence alignments. We extend a novel phylogenetic method based on Singular Value Decomposition (SVD to reconstruct the phylogeny of 12 sequenced Drosophila species. SVD analysis provides accurate comparisons for a high fraction of sequences within whole genomes without the prior identification of orthologs or homologous sites. With this method all protein sequences are converted to peptide frequency vectors within a matrix that is decomposed to provide simplified vector representations for each protein of the genome in a reduced dimensional space. These vectors are summed together to provide a vector representation for each species, and the angle between these vectors provides distance measures that are used to construct species trees. Results An unfiltered whole genome analysis (193,622 predicted proteins strongly supports the currently accepted phylogeny for 12 Drosophila species at higher dimensions except for the generally accepted but difficult to discern sister relationship between D. erecta and D. yakuba. Also, in accordance with previous studies, many sequences appear to support alternative phylogenies. In this case, we observed grouping of D. erecta with D. sechellia when approximately 55% to 95% of the proteins were removed using a filter based on projection values or by reducing resolution by using fewer dimensions. Similar results were obtained when just the melanogaster subgroup was analyzed. Conclusions These results indicate that using our novel phylogenetic method, it is possible to consult and interpret all predicted protein sequences within multiple whole genomes to produce accurate phylogenetic estimations of relatedness between

  5. The intimate genetics of Drosophila fertilization

    Science.gov (United States)

    Loppin, Benjamin; Dubruille, Raphaëlle; Horard, Béatrice

    2015-01-01

    The union of haploid gametes at fertilization initiates the formation of the diploid zygote in sexually reproducing animals. This founding event of embryogenesis includes several fascinating cellular and nuclear processes, such as sperm–egg cellular interactions, sperm chromatin remodelling, centrosome formation or pronuclear migration. In comparison with other aspects of development, the exploration of animal fertilization at the functional level has remained so far relatively limited, even in classical model organisms. Here, we have reviewed our current knowledge of fertilization in Drosophila melanogaster, with a special emphasis on the genes involved in the complex transformation of the fertilizing sperm nucleus into a replicated set of paternal chromosomes. PMID:26246493

  6. Drosophila melanogaster deoxyribonucleoside kinase activates gemcitabine

    Energy Technology Data Exchange (ETDEWEB)

    Knecht, Wolfgang [BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby (Denmark); Mikkelsen, Nils Egil [Department of Molecular Biology, Swedish University of Agricultural Sciences, Biomedical Centre, SE-751 24 Uppsala (Sweden); Clausen, Anders Ranegaard [Cell and Organism Biology, Lund University, Soelvegatan 35, SE-22362 Lund (Sweden); Willer, Mette [ZGene A/S, Agern Alle 7, DK-2970 Horsholm (Denmark); Eklund, Hans [Department of Molecular Biology, Swedish University of Agricultural Sciences, Biomedical Centre, SE-751 24 Uppsala (Sweden); Gojkovic, Zoran [ZGene A/S, Agern Alle 7, DK-2970 Horsholm (Denmark); Piskur, Jure, E-mail: Jure.Piskur@cob.lu.se [BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby (Denmark); Cell and Organism Biology, Lund University, Soelvegatan 35, SE-22362 Lund (Sweden)

    2009-05-01

    Drosophila melanogaster multisubstrate deoxyribonucleoside kinase (Dm-dNK) can additionally sensitize human cancer cell lines towards the anti-cancer drug gemcitabine. We show that this property is based on the Dm-dNK ability to efficiently phosphorylate gemcitabine. The 2.2 A resolution structure of Dm-dNK in complex with gemcitabine shows that the residues Tyr70 and Arg105 play a crucial role in the firm positioning of gemcitabine by extra interactions made by the fluoride atoms. This explains why gemcitabine is a good substrate for Dm-dNK.

  7. Crystal structure of enolase from Drosophila melanogaster.

    Science.gov (United States)

    Sun, Congcong; Xu, Baokui; Liu, Xueyan; Zhang, Zhen; Su, Zhongliang

    2017-04-01

    Enolase is an important enzyme in glycolysis and various biological processes. Its dysfunction is closely associated with diseases. Here, the enolase from Drosophila melanogaster (DmENO) was purified and crystallized. A crystal of DmENO diffracted to 2.0 Å resolution and belonged to space group R32. The structure was solved by molecular replacement. Like most enolases, DmENO forms a homodimer with conserved residues in the dimer interface. DmENO possesses an open conformation in this structure and contains conserved elements for catalytic activity. This work provides a structural basis for further functional and evolutionary studies of enolase.

  8. Genome, evolution, Drosophila and beyond: the new dimensions.

    Science.gov (United States)

    Prigent, Stéphane R; Rajpurohit, Subhash

    2007-01-01

    A century ago a little fly with red eyes was first used for genetic studies. That insignificant fly, called at that time Drosophila ampelophila, revolutionized biology while becoming the model we know today under the name of Drosophila melanogaster. Since then its study has never ceased, but the field of interest has somewhat changed during the century. To caricature a little, today we essentially learn from Drosophila meetings that the fly has a brain! It is true that the fly is a tremendous model organism for neurobiology. But this fly is, in fact, an appropriate and recognized model for the whole of biology. Indeed, Drosophila meetings are exceptional opportunities to gather biologists of diverse backgrounds together. There we not only learn about the latest improvements in our field of interest, but surely appreciate learning another bit of biology. From this biological melting pot has emerged a culture very specific to the fly community. Thus besides neurobiology, cell biology and development, a diversity of other research fields exist; they all have their own place in the cultural and historical dimension of the "drosophila" model. Several communications from those diverse research fields were presented at the 8th Japanese Drosophila Research Conference (JDRC8) and are briefly covered here. We believe it more judicious to call the model "drosophila" without a capital initial, as the model has never really been limited to only the Drosophila genus. The vernacular name "drosophila" is currently used to designate any fly of the Drosophilidae family and we believe the term more appropriate than "small fruit fly" or "vinegar fly" to better include the species and ecological diversity of the model.

  9. MoS2 based dual input logic AND gate

    Science.gov (United States)

    Martinez, Luis M.; Pinto, Nicholas J.; Naylor, Carl H.; Johnson, A. T. Charlie

    2016-12-01

    Crystalline monolayers of CVD MoS2 are used as the active semiconducting channel in a split-gate field effect transistor. The device demonstrates logic AND functionality that is controlled by independently addressing each gate terminal with ±10V. When +10V was simultaneously applied to both gates, the device was conductive (ON), while any other combination of gate voltages rendered the device resistive (OFF). The ON/OFF ratio of the device was ˜ 35 and the charge mobility using silicon nitride as the gate dielectric was 1.2cm2/V-s and 0.1cm2/V-s in the ON and OFF states respectively. Clear discrimination between the two states was observed when a simple circuit containing a load resistor was used to test the device logic AND functionality at 10Hz. One advantage is that split gate technology can reduce the number of devices required in complex circuits, leading to compact electronics and large scale integration based on intrinsic 2-D semiconducting materials.

  10. MoS2 nanoribbons as promising thermoelectric materials

    Science.gov (United States)

    Fan, D. D.; Liu, H. J.; Cheng, L.; Jiang, P. H.; Shi, J.; Tang, X. F.

    2014-09-01

    The thermoelectric properties of MoS2 armchair nanoribbons with different width are studied by using first-principles calculations and Boltzmann transport theory, where the relaxation time is predicted from deformation potential theory. Due to the dangling bonds at the armchair edge, there is obvious structure reconstruction of the nanoribbons which plays an important role in governing the electronic and transport properties. The investigated armchair nanoribbons are found to be semiconducting with indirect gaps, which exhibit interesting width-dependent oscillation behavior. The smaller gap of nanoribbon with width N = 4 (Here, N represents the number of dimer lines or zigzag chains across the ribbon width) leads to a much larger electrical conductivity at 300 K, which outweighs the relatively larger electronic thermal conductivity when compared with those of N = 5, 6. As a result, the ZT values can be optimized to 3.4 (p-type) and 2.5 (n-type) at room temperature, which significantly exceed the performance of most laboratory results reported in the literature.

  11. Search for the H Dibaryon (S = -2) Using Diffraction Dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Ecklund, K.

    2005-04-05

    The observed hadrons are understood as bound states of three quarks (baryons) or of quarks and antiquarks (mesons). To date no six quark bound state other than the loosely bound deuteron has been observed. Quantum Chromodynamics permits other color-singlet bound states of quarks, and a number of phenomenological models extended from the baryon (q{sup 3}) and meson (q{bar q}) sectors predict bound six quark states (q{sup 6}). The most probable candidate is the H dibaryon, composed of two each of the lightest three quarks (udsuds), with quantum numbers J{sup P} = 0{sup +}, I = 0 and S = -2. Its mass would likely be between the deuteron mass and twice the {Lambda} (uds) mass. This dissertation describes a search for the H dibaryon conducted in a neutral beam at the Brookhaven National Laboratory's Alternating Gradient Synchrotron. In the experiment a 24.1 GeV/c proton beam struck a 1.35 interaction length platinum target producing a collimated neutral beam (62 {mu}sr at 65 mrad from the incident proton direction) which propagated through a 18 m vacuum decay tank before entering a double arm spectrometer. Approximately 20 m from the production target a 10 cm (0.15 interaction length) long active scintillator dissociator was placed in the beam.

  12. Sigma virus and mutation in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Paquin, S.L.A.

    1977-01-01

    - The objectives of these experiments have been (1) to verify and evidence more fully the action of sigma in causing recessive lethal mutation on the X chromosome of Drosophila, both in the male and the female germ line; (2) to extend the study of sigma-induced recessive lethal mutation to the Drosophila autosomes; (3) to explore the possibility that this mutagenesis is site-directed; (4) to study the effects of sigma virus in conjunction with radiation in increasing non-disjunction and dominant lethality. The virus increases the rate of radiation-induced nondisjunction by altering meiotic chromosomal behavior. Percentage of non-disjunction with 500 rads of x-rays in the virus-free flies was 0.176, while in sigma-containing lines it was 0.333. With high doses of either x or neutron radiation, the presence of the virus enhances the frequency of dominant lethality. The difference is especially significant with the fast neutrons. The results indicate that sigma, and presumably other viruses, are indeed environmental mutagens and are, therefore, factors in the rate of background or spontaneous mutation

  13. Modeling Fragile X Syndrome in Drosophila

    Science.gov (United States)

    Drozd, Małgorzata; Bardoni, Barbara; Capovilla, Maria

    2018-01-01

    Intellectual disability (ID) and autism are hallmarks of Fragile X Syndrome (FXS), a hereditary neurodevelopmental disorder. The gene responsible for FXS is Fragile X Mental Retardation gene 1 (FMR1) encoding the Fragile X Mental Retardation Protein (FMRP), an RNA-binding protein involved in RNA metabolism and modulating the expression level of many targets. Most cases of FXS are caused by silencing of FMR1 due to CGG expansions in the 5′-UTR of the gene. Humans also carry the FXR1 and FXR2 paralogs of FMR1 while flies have only one FMR1 gene, here called dFMR1, sharing the same level of sequence homology with all three human genes, but functionally most similar to FMR1. This enables a much easier approach for FMR1 genetic studies. Drosophila has been widely used to investigate FMR1 functions at genetic, cellular, and molecular levels since dFMR1 mutants have many phenotypes in common with the wide spectrum of FMR1 functions that underlay the disease. In this review, we present very recent Drosophila studies investigating FMRP functions at genetic, cellular, molecular, and electrophysiological levels in addition to research on pharmacological treatments in the fly model. These studies have the potential to aid the discovery of pharmacological therapies for FXS.

  14. Imaging fictive locomotor patterns in larval Drosophila

    Science.gov (United States)

    Bayley, Timothy G.; Taylor, Adam L.; Berni, Jimena; Bate, Michael; Hedwig, Berthold

    2015-01-01

    We have established a preparation in larval Drosophila to monitor fictive locomotion simultaneously across abdominal and thoracic segments of the isolated CNS with genetically encoded Ca2+ indicators. The Ca2+ signals closely followed spiking activity measured electrophysiologically in nerve roots. Three motor patterns are analyzed. Two comprise waves of Ca2+ signals that progress along the longitudinal body axis in a posterior-to-anterior or anterior-to-posterior direction. These waves had statistically indistinguishable intersegmental phase delays compared with segmental contractions during forward and backward crawling behavior, despite being ∼10 times slower. During these waves, motor neurons of the dorsal longitudinal and transverse muscles were active in the same order as the muscle groups are recruited during crawling behavior. A third fictive motor pattern exhibits a left-right asymmetry across segments and bears similarities with turning behavior in intact larvae, occurring equally frequently and involving asymmetry in the same segments. Ablation of the segments in which forward and backward waves of Ca2+ signals were normally initiated did not eliminate production of Ca2+ waves. When the brain and subesophageal ganglion (SOG) were removed, the remaining ganglia retained the ability to produce both forward and backward waves of motor activity, although the speed and frequency of waves changed. Bilateral asymmetry of activity was reduced when the brain was removed and abolished when the SOG was removed. This work paves the way to studying the neural and genetic underpinnings of segmentally coordinated motor pattern generation in Drosophila with imaging techniques. PMID:26311188

  15. Structure of PCNA from Drosophila melanogaster

    International Nuclear Information System (INIS)

    Wang, Ke; Shi, Zhubing; Zhang, Min; Cheng, Dianlin

    2013-01-01

    Proliferating cell nuclear antigen (PCNA) plays essential roles in DNA replication, DNA repair, cell-cycle regulation and chromatin metabolism. The PCNA from Drosophila melanogaster (DmPCNA) has been purified and crystallized. Proliferating cell nuclear antigen (PCNA) plays essential roles in DNA replication, DNA repair, cell-cycle regulation and chromatin metabolism. The PCNA from Drosophila melanogaster (DmPCNA) was purified and crystallized. The crystal of DmPCNA diffracted to 2.0 Å resolution and belonged to space group H3, with unit-cell parameters a = b = 151.16, c = 38.28 Å. The structure of DmPCNA was determined by molecular replacement. DmPCNA forms a symmetric homotrimer in a head-to-tail manner. An interdomain connector loop (IDCL) links the N- and C-terminal domains. Additionally, the N-terminal and C-terminal domains contact each other through hydrophobic associations. Compared with human PCNA, the IDCL of DmPCNA has conformational changes, which may explain their difference in function. This work provides a structural basis for further functional and evolutionary studies of PCNA

  16. Adaptive Evolution of Gene Expression in Drosophila.

    Science.gov (United States)

    Nourmohammad, Armita; Rambeau, Joachim; Held, Torsten; Kovacova, Viera; Berg, Johannes; Lässig, Michael

    2017-08-08

    Gene expression levels are important quantitative traits that link genotypes to molecular functions and fitness. In Drosophila, population-genetic studies have revealed substantial adaptive evolution at the genomic level, but the evolutionary modes of gene expression remain controversial. Here, we present evidence that adaptation dominates the evolution of gene expression levels in flies. We show that 64% of the observed expression divergence across seven Drosophila species are adaptive changes driven by directional selection. Our results are derived from time-resolved data of gene expression divergence across a family of related species, using a probabilistic inference method for gene-specific selection. Adaptive gene expression is stronger in specific functional classes, including regulation, sensory perception, sexual behavior, and morphology. Moreover, we identify a large group of genes with sex-specific adaptation of expression, which predominantly occurs in males. Our analysis opens an avenue to map system-wide selection on molecular quantitative traits independently of their genetic basis. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Quantification of food intake in Drosophila.

    Directory of Open Access Journals (Sweden)

    Richard Wong

    2009-06-01

    Full Text Available Measurement of food intake in the fruit fly Drosophila melanogaster is often necessary for studies of behaviour, nutrition and drug administration. There is no reliable and agreed method for measuring food intake of flies in undisturbed, steady state, and normal culture conditions. We report such a method, based on measurement of feeding frequency by proboscis-extension, validated by short-term measurements of food dye intake. We used the method to demonstrate that (a female flies feed more frequently than males, (b flies feed more often when housed in larger groups and (c fly feeding varies at different times of the day. We also show that alterations in food intake are not induced by dietary restriction or by a null mutation of the fly insulin receptor substrate chico. In contrast, mutation of takeout increases food intake by increasing feeding frequency while mutation of ovo(D increases food intake by increasing the volume of food consumed per proboscis-extension. This approach provides a practical and reliable method for quantification of food intake in Drosophila under normal, undisturbed culture conditions.

  18. The smell of love in Drosophila

    Directory of Open Access Journals (Sweden)

    Anna B. eZiegler

    2013-04-01

    Full Text Available Odors are key sensory signals for social communication and food search in animals including insects. Drosophila melanogaster, is a powerful neurogenetic model commonly used to reveal molecular and cellular mechanisms involved in odorant detection. Males use olfaction together with other sensory modalities to find their mates. Here, we review known olfactory signals, their related olfactory receptors, and the corresponding neuronal architecture impacting courtship. OR67d receptor detects 11-cis-Vaccenyl Acetate (cVA, a male specific pheromone transferred to the female during copulation. Transferred cVA is able to reduce female attractiveness for other males after mating, and is also suspected to decrease male-male courtship. cVA can also serve as an aggregation signal, maybe through another OR. OR47b was shown to be activated by fly odors, and to enhance courtship depending on taste pheromones. IR84a detects phenylacetic acid (PAA and phenylacetaldehyde. These two odors are not pheromones produced by flies, but are present in various fly food sources. PAA enhances male courtship, acting as a food aphrodisiac. Drosophila males have thus developed complementary olfactory strategies to help them to select their mates.

  19. Odd-Paired: The Drosophila Zic Gene.

    Science.gov (United States)

    Hursh, Deborah A; Stultz, Brian G

    2018-01-01

    Zinc finger in the cerebellum (Zic) proteins are a family of transcription factors with multiple roles during development, particularly in neural tissues. The founding member of the Zic family is the Drosophila odd-paired (opa) gene. The Opa protein has a DNA binding domain containing five Cys2His2-type zinc fingers and has been shown to act as a sequence-specific DNA binding protein. Opa has significant homology to mammalian Zic1, Zic2, and Zic3 within the zinc finger domain and in two other conserved regions outside that domain. opa was initially identified as a pair-rule gene, part of the hierarchy of genes that establish the segmental body plan of the early Drosophila embryo. However, its wide expression pattern during embryogenesis indicates it plays additional roles. Embryos deficient in opa die before hatching with aberrant segmentation but also with defects in larval midgut formation. Post-embryonically, opa plays important roles in adult head development and circadian rhythm. Based on extensive neural expression, opa is predicted to be involved in many aspects of neural development and behavior, like other proteins of the Zic family. Consensus DNA binding sites have been identified for Opa and have been shown to activate transcription in vivo. However, there is evidence Opa may serve as a transcriptional regulator in the absence of direct DNA binding, as has been seen for other Zic proteins.

  20. Genetic variation for cardiac dysfunction in Drosophila.

    Directory of Open Access Journals (Sweden)

    Karen A Ocorr

    Full Text Available BACKGROUND: Common diseases may be attributed to combinations of variant alleles, but there are few model systems where the interactions among such variants can be studied in controlled genetic crosses. While association studies are designed to detect common polymorphisms of moderate effect, new approaches are required to characterize the impact on disease of interactions among rare alleles. METHODOLOGY/PRINCIPAL FINDINGS: We show that wild populations of Drosophila melanogaster harbor rare polymorphisms of major effect (RAME that predispose flies to a specific disease phenotype, age-dependent cardiac dysfunction. A screen of fifty inbred wild-type lines revealed a continuous spectrum of pacing-induced heart failure that generally increases in frequency with age. High-speed video analysis of the inbred lines with high rates of inducible heart failure indicates specific defects in cardiac function, including arrhythmias and contractile disorders ('cardiomyopathies'. A combination of bulked segregant analysis and single feature polymorphism (SFP detection localizes one of the cardiac susceptibility loci to the 97C interval on the fly genome. CONCLUSIONS/SIGNIFICANCE: Wild-type Drosophila, like humans, are predisposed to cardiac dysfunction. Identification of factors associated with these naturally occurring cardiac traits promises to provide important insights into the epidemiology of cardiac disease.

  1. Life Span Extension and Neuronal Cell Protection by Drosophila Nicotinamidase*S⃞

    Science.gov (United States)

    Balan, Vitaly; Miller, Gregory S.; Kaplun, Ludmila; Balan, Karina; Chong, Zhao-Zhong; Li, Faqi; Kaplun, Alexander; VanBerkum, Mark F. A.; Arking, Robert; Freeman, D. Carl; Maiese, Kenneth; Tzivion, Guri

    2008-01-01

    The life span of model organisms can be modulated by environmental conditions that influence cellular metabolism, oxidation, or DNA integrity. The yeast nicotinamidase gene pnc1 was identified as a key transcriptional target and mediator of calorie restriction and stress-induced life span extension. PNC1 is thought to exert its effect on yeast life span by modulating cellular nicotinamide and NAD levels, resulting in increased activity of Sir2 family class III histone deacetylases. In Caenorhabditis elegans, knockdown of a pnc1 homolog was shown recently to shorten the worm life span, whereas its overexpression increased survival under conditions of oxidative stress. The function and regulation of nicotinamidases in higher organisms has not been determined. Here, we report the identification and biochemical characterization of the Drosophila nicotinamidase, D-NAAM, and demonstrate that its overexpression significantly increases median and maximal fly life span. The life span extension was reversed in Sir2 mutant flies, suggesting Sir2 dependence. Testing for physiological effectors of D-NAAM in Drosophila S2 cells, we identified oxidative stress as a primary regulator, both at the transcription level and protein activity. In contrast to the yeast model, stress factors such as high osmolarity and heat shock, calorie restriction, or inhibitors of TOR and phosphatidylinositol 3-kinase pathways do not appear to regulate D-NAAM in S2 cells. Interestingly, the expression of D-NAAM in human neuronal cells conferred protection from oxidative stress-induced cell death in a sirtuin-dependent manner. Together, our findings establish a life span extending the ability of nicotinamidase in flies and offer a role for nicotinamide-modulating genes in oxidative stress regulated pathways influencing longevity and neuronal cell survival. PMID:18678867

  2. Mapping Sites of O-Glycosylation and Fringe Elongation on Drosophila Notch*

    Science.gov (United States)

    Harvey, Beth M.; Rana, Nadia A.; Moss, Hillary; Leonardi, Jessica; Jafar-Nejad, Hamed; Haltiwanger, Robert S.

    2016-01-01

    Glycosylation of the Notch receptor is essential for its activity and serves as an important modulator of signaling. Three major forms of O-glycosylation are predicted to occur at consensus sites within the epidermal growth factor-like repeats in the extracellular domain of the receptor: O-fucosylation, O-glucosylation, and O-GlcNAcylation. We have performed comprehensive mass spectral analyses of these three types of O-glycosylation on Drosophila Notch produced in S2 cells and identified peptides containing all 22 predicted O-fucose sites, all 18 predicted O-glucose sites, and all 18 putative O-GlcNAc sites. Using semiquantitative mass spectral methods, we have evaluated the occupancy and relative amounts of glycans at each site. The majority of the O-fucose sites were modified to high stoichiometries. Upon expression of the β3-N-acetylglucosaminyltransferase Fringe with Notch, we observed varying degrees of elongation beyond O-fucose monosaccharide, indicating that Fringe preferentially modifies certain sites more than others. Rumi modified O-glucose sites to high stoichiometries, although elongation of the O-glucose was site-specific. Although the current putative consensus sequence for O-GlcNAcylation predicts 18 O-GlcNAc sites on Notch, we only observed apparent O-GlcNAc modification at five sites. In addition, we performed mass spectral analysis on endogenous Notch purified from Drosophila embryos and found that the glycosylation states were similar to those found on Notch from S2 cells. These data provide foundational information for future studies investigating the mechanisms of how O-glycosylation regulates Notch activity. PMID:27268051

  3. Ultrahigh-performance pseudocapacitor based on phase-controlled synthesis of MoS2 nanosheets decorated Ni3S2 hybrid structure through annealing treatment

    Science.gov (United States)

    Huang, Long; Hou, Huijie; Liu, Bingchuan; Zeinu, Kemal; Zhu, Xiaolei; Yuan, Xiqing; He, Xiulin; Wu, Longsheng; Hu, Jingping; Yang, Jiakuan

    2017-12-01

    In this work, a hierarchical Ni3S2@MoS2 hybrid structure was synthesized by an effective strategy with a combined hydrothermal route and subsequent annealing treatment. When tested as supercapacitor electrodes, the Ni3S2@MoS2 composites exhibited high specific capacitance of 1418.5 F g-1 at 0.5 A g-1, which also showed a good capacitance retention of 75.8% at 5 A g-1 after 1250 cycles. The Ni3S2@MoS2 composites demonstrated 1.9 fold higher specific capacitance compared to the amorphous shell counterpart (NixSy@MoS2). Furthermore, the assembled asymmetric supercapacitor (Ni3S2@MoS2//rGO) also demonstrated a capacitance of 61 F g-1 at 0.5 A g-1, with energy and power densities of 21.7 Wh kg-1 at 400 W kg-1 and 12 Wh kg-1 at 2400 W kg-1 under an operating window of 1.6 V. The asymmetric supercapacitor also showed a favorable cycle stability with 72% capacity retention over 4000 cycles at 10 A g-1. The improved electrochemical performance is attributed to the synergetic effect of the large accessible surface area and optimal contacts between the MoS2 and the electrolyte, as well as high capacitance of the metallic Ni3S2 core.

  4. Molecular Cloning and Genomic Organization of a Novel Receptor from Drosophila melanogaster Structurally Related to Mammalian Galanin Receptors

    DEFF Research Database (Denmark)

    Lenz, Camilla; Søndergaard, L.; Grimmelikhuijzen, Cornelis J.P.

    2000-01-01

    neurobiologi, molekylærbiologi, zoologi, neurohormonereceptor, allatostatin, galanin, insekt, Drosophila......neurobiologi, molekylærbiologi, zoologi, neurohormonereceptor, allatostatin, galanin, insekt, Drosophila...

  5. Characterization of the 1S-2S transition in antihydrogen.

    Science.gov (United States)

    Ahmadi, M; Alves, B X R; Baker, C J; Bertsche, W; Capra, A; Carruth, C; Cesar, C L; Charlton, M; Cohen, S; Collister, R; Eriksson, S; Evans, A; Evetts, N; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayden, M E; Isaac, C A; Johnson, M A; Jones, J M; Jones, S A; Jonsell, S; Khramov, A; Knapp, P; Kurchaninov, L; Madsen, N; Maxwell, D; McKenna, J T K; Menary, S; Momose, T; Munich, J J; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sacramento, R L; Sameed, M; Sarid, E; Silveira, D M; Stutter, G; So, C; Tharp, T D; Thompson, R I; van der Werf, D P; Wurtele, J S

    2018-04-04

    In 1928, Dirac published an equation 1 that combined quantum mechanics and special relativity. Negative-energy solutions to this equation, rather than being unphysical as initially thought, represented a class of hitherto unobserved and unimagined particles-antimatter. The existence of particles of antimatter was confirmed with the discovery of the positron 2 (or anti-electron) by Anderson in 1932, but it is still unknown why matter, rather than antimatter, survived after the Big Bang. As a result, experimental studies of antimatter 3-7 , including tests of fundamental symmetries such as charge-parity and charge-parity-time, and searches for evidence of primordial antimatter, such as antihelium nuclei, have high priority in contemporary physics research. The fundamental role of the hydrogen atom in the evolution of the Universe and in the historical development of our understanding of quantum physics makes its antimatter counterpart-the antihydrogen atom-of particular interest. Current standard-model physics requires that hydrogen and antihydrogen have the same energy levels and spectral lines. The laser-driven 1S-2S transition was recently observed 8 in antihydrogen. Here we characterize one of the hyperfine components of this transition using magnetically trapped atoms of antihydrogen and compare it to model calculations for hydrogen in our apparatus. We find that the shape of the spectral line agrees very well with that expected for hydrogen and that the resonance frequency agrees with that in hydrogen to about 5 kilohertz out of 2.5 × 10 15 hertz. This is consistent with charge-parity-time invariance at a relative precision of 2 × 10 -12 -two orders of magnitude more precise than the previous determination 8 -corresponding to an absolute energy sensitivity of 2 × 10 -20 GeV.

  6. Genome-wide comparative analysis of four Indian Drosophila species.

    Science.gov (United States)

    Mohanty, Sujata; Khanna, Radhika

    2017-12-01

    Comparative analysis of multiple genomes of closely or distantly related Drosophila species undoubtedly creates excitement among evolutionary biologists in exploring the genomic changes with an ecology and evolutionary perspective. We present herewith the de novo assembled whole genome sequences of four Drosophila species, D. bipectinata, D. takahashii, D. biarmipes and D. nasuta of Indian origin using Next Generation Sequencing technology on an Illumina platform along with their detailed assembly statistics. The comparative genomics analysis, e.g. gene predictions and annotations, functional and orthogroup analysis of coding sequences and genome wide SNP distribution were performed. The whole genome of Zaprionus indianus of Indian origin published earlier by us and the genome sequences of previously sequenced 12 Drosophila species available in the NCBI database were included in the analysis. The present work is a part of our ongoing genomics project of Indian Drosophila species.

  7. Neurogenetics of female reproductive behaviors in Drosophila melanogaster

    NARCIS (Netherlands)

    Laturney, Meghan; Billeter, Jean-Christophe; Friedmann, T; Dunlap, JC; Goodwin, SF

    2014-01-01

    We follow an adult Drosophila melanogaster female through the major reproductive decisions she makes during her lifetime, including habitat selection, precopulatory mate choice, postcopulatory physiological changes, polyandry, and egg-laying site selection. In the process, we review the molecular

  8. Neuromodulation and Strategic Action Choice in Drosophila Aggression.

    Science.gov (United States)

    Asahina, Kenta

    2017-07-25

    In this review, I discuss current knowledge and outstanding questions on the neuromodulators that influence aggressive behavior of the fruit fly Drosophila melanogaster. I first present evidence that Drosophila exchange information during an agonistic interaction and choose appropriate actions based on this information. I then discuss the influence of several biogenic amines and neuropeptides on aggressive behavior. One striking characteristic of neuromodulation is that it can configure a neural circuit dynamically, enabling one circuit to generate multiple outcomes. I suggest a consensus effect of each neuromodulatory molecule on Drosophila aggression, as well as effects of receptor proteins where relevant data are available. Lastly, I consider neuromodulation in the context of strategic action choices during agonistic interactions. Genetic components of neuromodulatory systems are highly conserved across animals, suggesting that molecular and cellular mechanisms controlling Drosophila aggression can shed light on neural principles governing action choice during social interactions.

  9. NF-1 Dependent Gene Regulation in Drosophila Melanogaster

    National Research Council Canada - National Science Library

    Zhong, Yi

    2004-01-01

    .... We have used an Affymetrix whole genome chip, containing all 13,500 genes of the fruit fly Drosophila, to identify 93 genes with altered expression patterns in flies that have no NF1 protein compared...

  10. Induction of morphological aberrations by enzyme inhibition in Drosophila melanogaster

    NARCIS (Netherlands)

    Bos, M.; Scharloo, W.; Bijlsma, R.; de Boer, I.M.; den Hollander, J.

    1969-01-01

    Zusatz zum Futter vonDrosophila melanogaster von 5-Fluoro-2-deoxyuridin oder Aminopterin induziert überzählige Skutellar- und Dorsozentralborsten sowie gekerbte Flügel. Diese Modifikationen wurden als Konsequenz von Enzymhemmung interpretiert.

  11. Drosophila tsRNAs preferentially suppress general translation machinery via antisense pairing and participate in cellular starvation response.

    Science.gov (United States)

    Luo, Shiqi; He, Feng; Luo, Junjie; Dou, Shengqian; Wang, Yirong; Guo, Annan; Lu, Jian

    2018-03-14

    Transfer RNA-derived small RNAs (tsRNAs) are an emerging class of small RNAs, yet their regulatory roles have not been well understood. Here we studied the molecular mechanisms and consequences of tsRNA-mediated regulation in Drosophila. By analyzing 495 public small RNA libraries, we demonstrate that most tsRNAs are conserved, prevalent and abundant in Drosophila. By carrying out mRNA sequencing and ribosome profiling of S2 cells transfected with single-stranded tsRNA mimics and mocks, we show that tsRNAs recognize target mRNAs through conserved complementary sequence matching and suppress target genes by translational inhibition. The target prediction suggests that tsRNAs preferentially suppress translation of the key components of the general translation machinery, which explains how tsRNAs inhibit the global mRNA translation. Serum starvation experiments confirm tsRNAs participate in cellular starvation responses by preferential targeting the ribosomal proteins and translational initiation or elongation factors. Knock-down of AGO2 in S2 cells under normal and starved conditions reveals a dependence of the tsRNA-mediated regulation on AGO2. We also validated the repressive effects of representative tsRNAs on cellular global translation and specific targets with luciferase reporter assays. Our study suggests the tsRNA-mediated regulation might be crucial for the energy homeostasis and the metabolic adaptation in the cellular systems.

  12. The lysosomal enzyme receptor protein (LERP is not essential, but is implicated in lysosomal function in Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Medina Hasanagic

    2015-10-01

    Full Text Available The lysosomal enzyme receptor protein (LERP of Drosophila melanogaster is the ortholog of the mammalian cation-independent mannose 6-phosphate (Man 6-P receptor, which mediates trafficking of newly synthesized lysosomal acid hydrolases to lysosomes. However, flies lack the enzymes necessary to make the Man 6-P mark, and the amino acids implicated in Man 6-P binding by the mammalian receptor are not conserved in LERP. Thus, the function of LERP in sorting of lysosomal enzymes to lysosomes in Drosophila is unclear. Here, we analyze the consequence of LERP depletion in S2 cells and intact flies. RNAi-mediated knockdown of LERP in S2 cells had little or no effect on the cellular content or secretion of several lysosomal hydrolases. We generated a novel Lerp null mutation, LerpF6, which abolishes LERP protein expression. Lerp mutants have normal viability and fertility and display no overt phenotypes other than reduced body weight. Lerp mutant flies exhibit a 30–40% decrease in the level of several lysosomal hydrolases, and are hypersensitive to dietary chloroquine and starvation, consistent with impaired lysosome function. Loss of LERP also enhances an eye phenotype associated with defective autophagy. Our findings implicate Lerp in lysosome function and autophagy.

  13. Drosophila C Virus Systemic Infection Leads to Intestinal Obstruction

    OpenAIRE

    Chtarbanova, Stanislava; Lamiable, Olivier; Lee, Kwang-Zin; Galiana, Delphine; Troxler, Laurent; Meignin, Carine; Hetru, Charles; Hoffmann, Jules A.; Daeffler, Laurent; Imler, Jean-Luc

    2014-01-01

    Drosophila C virus (DCV) is a positive-sense RNA virus belonging to the Dicistroviridae family. This natural pathogen of the model organism Drosophila melanogaster is commonly used to investigate antiviral host defense in flies, which involves both RNA interference and inducible responses. Although lethality is used routinely as a readout for the efficiency of the antiviral immune response in these studies, virus-induced pathologies in flies still are poorly understood. Here, we characterize ...

  14. The Persistence of Facultative Parthenogenesis in Drosophila albomicans

    OpenAIRE

    Chang, Chia-chen; Ting, Chau-Ti; Chang, Ching-Ho; Fang, Shu; Chang, Hwei-yu

    2014-01-01

    Parthenogenesis has evolved independently in more than 10 Drosophila species. Most cases are tychoparthenogenesis, which is occasional or accidental parthenogenesis in normally bisexual species with a low hatching rate of eggs produced by virgin females; this form is presumed to be an early stage of parthenogenesis. To address how parthenogenesis and sexual reproduction coexist in Drosophila populations, we investigated several reproductive traits, including the fertility, parthenogenetic cap...

  15. Dietary glucose regulates yeast consumption in adult Drosophila males

    OpenAIRE

    Lebreton, S?bastien; Witzgall, Peter; Olsson, Marie; Becher, Paul G.

    2014-01-01

    The adjustment of feeding behavior in response to hunger and satiety contributes to homeostatic regulation in animals. The fruit fly Drosophila melanogaster feeds on yeasts growing on overripe fruit, providing nutrients required for adult survival, reproduction and larval growth. Here, we present data on how the nutritional value of food affects subsequent yeast consumption in Drosophila adult males. After a period of starvation, flies showed intensive yeast consumption. In comparison, flies ...

  16. Molecular characterization of the Drosophila responses towards nematodes

    OpenAIRE

    Arefin, Md. Badrul

    2016-01-01

    A sophisticated evolutionary conserved innate immune system has evolved in insects to fight pathogens and to restrict damage in harmful (danger) situations including cancer. A significant amount of knowledge about different infection models in Drosophila has been generated in past decades, which revealed functional resemblances and implications for vertebrate systems. However, how Drosophila responds towards multicellular parasitic nematodes and in danger situations is still little understood...

  17. Genomic and karyotypic variation in Drosophila parasitoids (Hymenoptera, Cynipoidea, Figitidae

    Directory of Open Access Journals (Sweden)

    Vladimir Gokhman

    2011-08-01

    Full Text Available Drosophila melanogaster Meigen, 1830 has served as a model insect for over a century. Sequencing of the 11 additional Drosophila Fallen, 1823 species marks substantial progress in comparative genomics of this genus. By comparison, practically nothing is known about the genome size or genome sequences of parasitic wasps of Drosophila. Here, we present the first comparative analysis of genome size and karyotype structures of Drosophila parasitoids of the Leptopilina Förster, 1869 and Ganaspis Förster, 1869 species. The gametic genome size of Ganaspis xanthopoda (Ashmead, 1896 is larger than those of the three Leptopilina species studied. The genome sizes of all parasitic wasps studied here are also larger than those known for all Drosophila species. Surprisingly, genome sizes of these Drosophila parasitoids exceed the average value known for all previously studied Hymenoptera. The haploid chromosome number of both Leptopilina heterotoma (Thomson, 1862 and L. victoriae Nordlander, 1980 is ten. A chromosomal fusion appears to have produced a distinct karyotype for L. boulardi (Barbotin, Carton et Keiner-Pillault, 1979 (n = 9, whose genome size is smaller than that of wasps of the L. heterotoma clade. Like L. boulardi, the haploid chromosome number for G. xanthopoda is also nine. Our studies reveal a positive, but non linear, correlation between the genome size and total chromosome length in Drosophila parasitoids. These Drosophila parasitoids differ widely in their host range, and utilize different infection strategies to overcome host defense. Their comparative genomics, in relation to their exceptionally well-characterized hosts, will prove to be valuable for understanding the molecular basis of the host-parasite arms race and how such mechanisms shape the genetic structures of insect communities.

  18. Reassignment of Drosophila willistoni Genome Scaffolds to Chromosome II Arms

    OpenAIRE

    Garcia, Carolina; Delprat, Alejandra; Ruiz, Alfredo; Valente, Vera L. S.

    2015-01-01

    Drosophila willistoni is a geographically widespread Neotropical species. The genome of strain Gd-H4-1 from Guadeloupe Island (Caribbean) was sequenced in 2007 as part of the 12 Drosophila Genomes Project. The assembled scaffolds were joined based on conserved linkage and assigned to polytene chromosomes based on a handful of genetic and physical markers. This paucity of markers was particularly striking in the metacentric chromosome II, comprised two similarly sized arms, IIL and IIR, tradit...

  19. The influence of sterol metabolism upon radiation-induced aneuploidy of Drosophila melanogaster in the yeast-drosophila system

    International Nuclear Information System (INIS)

    Savitsij, V.V.; Luchnikova, E.M.; Inge-Vechtomov, S.I.

    1985-01-01

    The influence of sterol metabolism upon induced Drosophila melanogaster mutagenesis in an ecology-genetic yeast-drosophila system has been studied. The sterol deficit in fly organism has been created for account of using as food substrate for fremales of biomass of saccharomyces cerevisiae living cells of 9-2-PZ12 train with nyssup(r1) locus mutation which blocks the ergosterol synthesis. It has been found that the Drosophila females content on mutant yeast increases the frequency of losses and non discrepancy of X-chromosomes induced by X-radiation (1000 R). Addition into yeast biomass of 0.1 % cholesterol solution in 10 %-ethanol reduces the oocytes resistance to X-radiation up to control level. Possible hormonal and membrane mechanisms of increasing radiation-induced aneuploidy of Drosophila and the role of sterol metabolism in organism resistance to damaging factors are discussed

  20. Purification and characterization of recombinant full-length and protease domain of murine MMP-9 expressed in Drosophila S2 cells

    DEFF Research Database (Denmark)

    Rasch, Morten G; Lund, Ida K.; Illemann, Martin

    2010-01-01

    -length and truncated versions were 5 mg/l and 2 mg/l, respectively. The products were >95% pure after gelatin Sepharose chromatography and possessed proteolytic activity when analyzed by gelatin zymography. Using the purified full-length murine MMP-9 we raised polyclonal antibodies by immunizations of rabbits...

  1. Cytoplasmic Streaming in the Drosophila Oocyte.

    Science.gov (United States)

    Quinlan, Margot E

    2016-10-06

    Objects are commonly moved within the cell by either passive diffusion or active directed transport. A third possibility is advection, in which objects within the cytoplasm are moved with the flow of the cytoplasm. Bulk movement of the cytoplasm, or streaming, as required for advection, is more common in large cells than in small cells. For example, streaming is observed in elongated plant cells and the oocytes of several species. In the Drosophila oocyte, two stages of streaming are observed: relatively slow streaming during mid-oogenesis and streaming that is approximately ten times faster during late oogenesis. These flows are implicated in two processes: polarity establishment and mixing. In this review, I discuss the underlying mechanism of streaming, how slow and fast streaming are differentiated, and what we know about the physiological roles of the two types of streaming.

  2. [Ulysses retrotransposon aspartate proteinase (Drosophila virilis)].

    Science.gov (United States)

    Volkov, D A; Savvateeva, L V; Dergousova, N I; Rumsh, L D

    2002-01-01

    Retrotransposones are mobile genetic elements occurring in genomes of bacteria, plants or animals. Retrotransposones were found to contain nucleotide sequences encoding proteins which are homological to retroviral aspartic proteinases. Our research has been focused on Ulysses which is mobile genetic element found in Drosophila virilis. We suggested a primary structure of Ulysses proteinase using comparative analysis of amino acid sequences of retroviral proteinases and proteinases from retrotransposones. The appropriate cDNA fragment has been cloned and expressed in E. coli. The purification of recombinant protein (12 kD) has been carried out by affinity chromatography using pepstatine-agarose. The obtained protein has proteolytic activity at optimum pH 5.5 like the majority of aspartic proteinases.

  3. Organization of the Drosophila larval visual circuit

    Science.gov (United States)

    Gendre, Nanae; Neagu-Maier, G Larisa; Fetter, Richard D; Schneider-Mizell, Casey M; Truman, James W; Zlatic, Marta; Cardona, Albert

    2017-01-01

    Visual systems transduce, process and transmit light-dependent environmental cues. Computation of visual features depends on photoreceptor neuron types (PR) present, organization of the eye and wiring of the underlying neural circuit. Here, we describe the circuit architecture of the visual system of Drosophila larvae by mapping the synaptic wiring diagram and neurotransmitters. By contacting different targets, the two larval PR-subtypes create two converging pathways potentially underlying the computation of ambient light intensity and temporal light changes already within this first visual processing center. Locally processed visual information then signals via dedicated projection interneurons to higher brain areas including the lateral horn and mushroom body. The stratified structure of the larval optic neuropil (LON) suggests common organizational principles with the adult fly and vertebrate visual systems. The complete synaptic wiring diagram of the LON paves the way to understanding how circuits with reduced numerical complexity control wide ranges of behaviors.

  4. Phenotypic plasticity of the Drosophila transcriptome.

    Directory of Open Access Journals (Sweden)

    Shanshan Zhou

    Full Text Available Phenotypic plasticity is the ability of a single genotype to produce different phenotypes in response to changing environments. We assessed variation in genome-wide gene expression and four fitness-related phenotypes of an outbred Drosophila melanogaster population under 20 different physiological, social, nutritional, chemical, and physical environments; and we compared the phenotypically plastic transcripts to genetically variable transcripts in a single environment. The environmentally sensitive transcriptome consists of two transcript categories, which comprise ∼15% of expressed transcripts. Class I transcripts are genetically variable and associated with detoxification, metabolism, proteolysis, heat shock proteins, and transcriptional regulation. Class II transcripts have low genetic variance and show sexually dimorphic expression enriched for reproductive functions. Clustering analysis of Class I transcripts reveals a fragmented modular organization and distinct environmentally responsive transcriptional signatures for the four fitness-related traits. Our analysis suggests that a restricted environmentally responsive segment of the transcriptome preserves the balance between phenotypic plasticity and environmental canalization.

  5. Studying cytokinesis in Drosophila epithelial tissues.

    Science.gov (United States)

    Pinheiro, D; Bellaïche, Y

    2017-01-01

    Epithelial tissue cohesiveness is ensured through cell-cell junctions that maintain both adhesion and mechanical coupling between neighboring cells. During development, epithelial tissues undergo intensive cell proliferation. Cell division, and particularly cytokinesis, is coupled to the formation of new adhesive contacts, thereby preserving tissue integrity and propagating cell polarity. Remarkably, the geometry of the new interfaces is determined by the combined action of the dividing cell and its neighbors. To further understand the interplay between the dividing cell and its neighbors, as well as the role of cell division for tissue morphogenesis, it is important to analyze cytokinesis in vivo. Here we present methods to perform live imaging of cell division in Drosophila epithelial tissues and discuss some aspects of image processing and analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Longevity and the stress response in Drosophila

    DEFF Research Database (Denmark)

    Vermeulen, Corneel J.; Loeschcke, Volker

    2007-01-01

    to affect lifespan. The progress in modern genetic techniques has allowed researchers to test this idea. The general stress response involves the expression of stress proteins, such as chaperones and antioxidative proteins, downregulation of genes involved in energy metabolism and the release of protective......The concept that lifespan is a function of the capacity to withstand extrinsic stress is very old. In concordance with this, long-lived individuals often have increased resistance against a variety of stresses throughout life. Genes underlying the stress response may therefore have the ability...... briefly review the state of the art of research on ageing and longevity in the model organism Drosophila, with focus on the role of the general stress response. We will conclude by contemplating some of the implications of the findings in this research and will suggest several directions for future...

  7. Taste Preference Assay for Adult Drosophila.

    Science.gov (United States)

    Bantel, Andrew P; Tessier, Charles R

    2016-09-08

    Olfactory and gustatory perception of the environment is vital for animal survival. The most obvious application of these chemosenses is to be able to distinguish good food sources from potentially dangerous food sources. Gustation requires physical contact with a chemical compound which is able to signal through taste receptors that are expressed on the surface of neurons. In insects, these gustatory neurons can be located across the animal's body allowing taste to play an important role in many different behaviors. Insects typically prefer compounds containing sugars, while compounds that are considered bitter tasting are avoided. Given the basic biological importance of taste, there is intense interest in understanding the molecular mechanisms underlying this sensory modality. We describe an adult Drosophila taste assay which reflects the preference of the animals for a given tastant compound. This assay may be applied to animals of any genetic background to examine the taste preference for a desired soluble compound.

  8. MicroRNA function in Drosophila melanogaster.

    Science.gov (United States)

    Carthew, Richard W; Agbu, Pamela; Giri, Ritika

    2017-05-01

    Over the last decade, microRNAs have emerged as critical regulators in the expression and function of animal genomes. This review article discusses the relationship between microRNA-mediated regulation and the biology of the fruit fly Drosophila melanogaster. We focus on the roles that microRNAs play in tissue growth, germ cell development, hormone action, and the development and activity of the central nervous system. We also discuss the ways in which microRNAs affect robustness. Many gene regulatory networks are robust; they are relatively insensitive to the precise values of reaction constants and concentrations of molecules acting within the networks. MicroRNAs involved in robustness appear to be nonessential under uniform conditions used in conventional laboratory experiments. However, the robust functions of microRNAs can be revealed when environmental or genetic variation otherwise has an impact on developmental outcomes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Proteome reference map of Drosophila melanogaster head.

    Science.gov (United States)

    Lee, Tian-Ren; Huang, Shun-Hong; Lee, Chi-Ching; Lee, Hsiao-Yun; Chan, Hsin-Tzu; Lin, Kuo-Sen; Chan, Hong-Lin; Lyu, Ping-Chiang

    2012-06-01

    Drosophila melanogaster has been used as a genetic model organism to understand the fundamental molecular mechanisms in human biology including memory formation that has been reported involving protein synthesis and/or post-translational modification. In this study, we employed a proteomic platform based on fluorescent 2DE and MALDI-TOF MS to build a standard D. melanogaster head proteome map for proteome-proteome comparison. In order to facilitate the comparison, an interactive database has been constructed for systematically integrating and analyzing the proteomes from different conditions and further implicated to study human diseases related to D. melanogaster model. In summary, the fundamental head proteomic database and bioinformatic analysis will be useful for further elucidating the biological mechanisms such as memory formation and neurodegenerative diseases. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Origin of meiotic nondisjunction in Drosophila females

    International Nuclear Information System (INIS)

    Grell, R.F.

    1978-01-01

    Meiotic nondisjunction can be induced by external agents, such as heat, radiation, and chemicals, and by internal genotypic alterations, namely, point mutations and chromosomal rearrangements. In many cases nondisjunction arises from a reduction or elimination of crossing-over, leading to the production of homologous univalents which fail to co-orient on the metaphase plate and to disjoin properly. In some organisms, e.g., Drosophila and perhaps man, distributive pairing [i.e., a post-exchange, size-dependent pairing] ensures the regular segregation of such homologous univalents. When a nonhomologous univalent is present, which falls within a size range permitting nonhomologous recognition and pairing, distributive nondisjunction of the homologues may follow. Examples of nondisjunction induced by inversion heterozygosity, translocation heterozygosity, chromosome fragments, radiation, heat, and recombination-defective mutants are presented

  11. A microsatellite linkage map of Drosophila mojavensis

    Directory of Open Access Journals (Sweden)

    Schully Sheri

    2004-05-01

    Full Text Available Abstract Background Drosophila mojavensis has been a model system for genetic studies of ecological adaptation and speciation. However, despite its use for over half a century, no linkage map has been produced for this species or its close relatives. Results We have developed and mapped 90 microsatellites in D. mojavensis, and we present a detailed recombinational linkage map of 34 of these microsatellites. A slight excess of repetitive sequence was observed on the X-chromosome relative to the autosomes, and the linkage groups have a greater recombinational length than the homologous D. melanogaster chromosome arms. We also confirmed the conservation of Muller's elements in 23 sequences between D. melanogaster and D. mojavensis. Conclusions The microsatellite primer sequences and localizations are presented here and made available to the public. This map will facilitate future quantitative trait locus mapping studies of phenotypes involved in adaptation or reproductive isolation using this species.

  12. Genetic control of Drosophila nerve cord development

    Science.gov (United States)

    Skeath, James B.; Thor, Stefan

    2003-01-01

    The Drosophila ventral nerve cord has been a central model system for studying the molecular genetic mechanisms that control CNS development. Studies show that the generation of neural diversity is a multistep process initiated by the patterning and segmentation of the neuroectoderm. These events act together with the process of lateral inhibition to generate precursor cells (neuroblasts) with specific identities, distinguished by the expression of unique combinations of regulatory genes. The expression of these genes in a given neuroblast restricts the fate of its progeny, by activating specific combinations of downstream genes. These genes in turn specify the identity of any given postmitotic cell, which is evident by its cellular morphology and choice of neurotransmitter.

  13. Stable MoS2 Field-Effect Transistors Using TiO2 Interfacial Layer at Metal/MoS2 Contact

    KAUST Repository

    Park, Woojin

    2017-09-07

    Molybdenum disulphide (MoS2) is an emerging 2-dimensional (2D) semiconductor for electronic devices. However, unstable and low performance of MoS2 FETs is an important concern. In this study, inserting an atomic layer deposition (ALD) titanium dioxide (TiO2) interfacial layer between contact metal and MoS2 channel is suggested to achieve more stable performances. The reduced threshold voltage (VTH) shift and reduced series resistance (RSD) were simultaneously achieved.

  14. Transcription profiling of Drosophila exposed to a levitation magnet for different lengths of time

    Data.gov (United States)

    National Aeronautics and Space Administration — Drosophila samples were exposed to the levitation magnet inside a 25mm diameter tubes with 3 ml of yeast-based Drosophila food in the bottom and a chamber of only 5...

  15. Structure and Development of Glia in Drosophila

    Science.gov (United States)

    Hartenstein, Volker

    2014-01-01

    Insect glia represents a conspicuous and diverse population of cells and plays a role in controlling neuronal progenitor proliferation, axonal growth, neuronal differentiation and maintenance, and neuronal function. Genetic studies in Drosophila have elucidated many aspects of glial structure, function and development. Just as in vertebrates, it appears as if different classes of glial cells are specialized for different functions. Based on topology and cell shape, glial cells of the central nervous system fall into three classes (Fig. 1A–C): (i) surface glia that extend sheath-like processes to wrap around the entire brain; (ii) cortex glia (also called cell body-associated glia) that encapsulate neuronal somata and neuroblasts which form the outer layer (cortex) of the central nervous system; (iii) neuropile glia that are located at the interface between the cortex and the neuropile, the central domain of the nervous system formed by the highly branched neuronal processes and their synaptic contacts. Surface glia is further subdivided into an outer, perineurial layer, and an inner, subperineurial layer. Likewise, neuropile glia comprises a class of cells that remain at the surface of the neuropile (ensheathing glia), and a second class that forms profuse lamellar processes around nerve fibers within the neuropile (astrocyte-like or reticular glia). Glia also surrounds the peripheral nerves and sensory organs; here, one also recognizes perineurial and subperineurial glia, and a third type called “wrapping glia” that most likely corresponds to the ensheathing glia of the central nervous system. Much more experimental work is needed to determine how fundamental these differences between classes of glial cells are, or how and when during development they are specified. To aid in this work the following review will briefly summarize our knowledge of the classes of glial cells encountered in the Drosophila nervous system, and then survey their development from

  16. Unique properties of Drosophila spermatocyte primary cilia

    Directory of Open Access Journals (Sweden)

    Maria Giovanna Riparbelli

    2013-09-01

    The primary cilium is an essential organelle required for animal development and adult homeostasis that is found on most animal cells. The primary cilium contains a microtubule-based axoneme cytoskeleton that typically grows from the mother centriole in G0/G1 phase of the cell cycle as a membrane-bound compartment that protrudes from the cell surface. A unique system of bidirectional transport, intraflagellar transport (IFT, maintains the structure and function of cilia. While the axoneme is dynamic, growing and shrinking at its tip, at the same time it is very stable to the effects of microtubule-targeting drugs. The primary cilia found on Drosophila spermatocytes diverge from the general rules of primary cilium biology in several respects. Among these unique attributes, spermatocyte cilia assemble from all four centrioles in an IFT-independent manner in G2 phase, and persist continuously through two cell divisions. Here, we show that Drosophila spermatocyte primary cilia are extremely sensitive to microtubule-targeting drugs, unlike their mammalian counterparts. Spermatocyte cilia and their axonemes fail to assemble or be maintained upon nocodazole treatment, while centriole replication appears unperturbed. On the other hand, paclitaxel (Taxol, a microtubule-stabilizing drug, disrupted transition zone assembly and anchoring to the plasma membrane while causing spermatocyte primary cilia to grow extensively long during the assembly/elongation phase, but did not overtly affect the centrioles. However, once assembled to their mature length, spermatocyte cilia appeared unaffected by Taxol. The effects of these drugs on axoneme dynamics further demonstrate that spermatocyte primary cilia are endowed with unique assembly properties.

  17. Multiphonon absorption processes in layered structured TlGaS2, TlInS2 and TlGaSe2 single crystals

    Science.gov (United States)

    Isik, M.; Gasanly, N. M.; Korkmaz, F.

    2013-07-01

    The infrared transmittance and Raman scattering spectra in TlGaS2, TlInS2 and TlGaSe2 layered single crystals grown by Bridgman method were studied in the frequency ranges of 400-1500 and 10-400 cm-1, respectively. Three, three and five bands observed at room temperature in IR transmittance spectra of TlGaS2, TlInS2 and TlGaSe2, respectively, were interpreted in terms of multiphonon absorption processes.

  18. Multiphonon absorption processes in layered structured TlGaS2, TlInS2 and TlGaSe2 single crystals

    International Nuclear Information System (INIS)

    Isik, M.; Gasanly, N.M.; Korkmaz, F.

    2013-01-01

    The infrared transmittance and Raman scattering spectra in TlGaS 2 , TlInS 2 and TlGaSe 2 layered single crystals grown by Bridgman method were studied in the frequency ranges of 400–1500 and 10–400 cm −1 , respectively. Three, three and five bands observed at room temperature in IR transmittance spectra of TlGaS 2 , TlInS 2 and TlGaSe 2 , respectively, were interpreted in terms of multiphonon absorption processes

  19. Preparation of Monolayer MoS2 Quantum Dots using Temporally Shaped Femtosecond Laser Ablation of Bulk MoS2 Targets in Water

    OpenAIRE

    Li, Bo; Jiang, Lan; Li, Xin; Ran, Peng; Zuo, Pei; Wang, Andong; Qu, Liangti; Zhao, Yang; Cheng, Zhihua; Lu, Yongfeng

    2017-01-01

    Zero-dimensional MoS2 quantum dots (QDs) possess distinct physical and chemical properties, which have garnered them considerable attention and facilitates their use in a broad range of applications. In this study, we prepared monolayer MoS2 QDs using temporally shaped femtosecond laser ablation of bulk MoS2 targets in water. The morphology, crystal structures, chemical, and optical properties of the MoS2 QDs were characterized by transmission electron microscopy, X-ray diffraction, Raman spe...

  20. E’’ Raman Mode in Thermal Strain-Fractured CVD-MoS2

    Directory of Open Access Journals (Sweden)

    Di Wu

    2016-11-01

    Full Text Available Molybdenum disulfide (MoS2 has recently attracted considerable interests due to its unique properties and potential applications. Chemical vapor deposition (CVD method is used widely to grow large-area and high-quality MoS2 single crystals. Here, we report our investigation on thermal strain-fractured (SF single crystalline MoS2, oxidation-fractured MoS2, and normal MoS2 by atomic force microscopy (AFM, Raman and photoluminescence (PL measurements. Several new Raman modes are observed for SF-MoS2. The band gap of SF-MoS2 is enlarged by 150 meV and the PL intensity is reduced substantially. These results imply that a structural transformation occurs in SF-MoS2. Our findings here are useful for the design of MoS2-based nanocatalysts with relative high catalytic activity.

  1. Enzymatic biomineralization of biocompatible CuInS2, (CuInZn)S2and CuInS2/ZnS core/shell nanocrystals for bioimaging.

    Science.gov (United States)

    Spangler, Leah C; Chu, Roxanne; Lu, Li; Kiely, Christopher J; Berger, Bryan W; McIntosh, Steven

    2017-07-13

    This work demonstrates a bioenabled fully aqueous phase and room temperature route to the synthesis of CuInS 2 /ZnS core/shell quantum confined nanocrystals conjugated to IgG antibodies and used for fluorescent tagging of THP-1 leukemia cells. This elegant, straightforward and green approach avoids the use of solvents, high temperatures and the necessity to phase transfer the nanocrystals prior to application. Non-toxic CuInS 2 , (CuInZn)S 2 , and CuInS 2 /ZnS core/shell quantum confined nanocrystals are synthesized via a biomineralization process based on a single recombinant cystathionine γ-lyase (CSE) enzyme. First, soluble In-S complexes are formed from indium acetate and H 2 S generated by CSE, which are then stabilized by l-cysteine in solution. The subsequent addition of copper, or both copper and zinc, precursors then results in the immediate formation of CuInS 2 or (CuInZn)S 2 quantum dots. Shell growth is realized through subsequent introduction of Zn acetate to the preformed core nanocrystals. The size and optical properties of the nanocrystals are tuned by adjusting the indium precursor concentration and initial incubation period. CuInS 2 /ZnS core/shell particles are conjugated to IgG antibodies using EDC/NHS cross-linkers and then applied in the bioimaging of THP-1 cells. Cytotoxicity tests confirm that CuInS 2 /ZnS core/shell quantum dots do not cause cell death during bioimaging. Thus, this biomineralization enabled approach provides a facile, low temperature route for the fully aqueous synthesis of non-toxic CuInS 2 /ZnS quantum dots, which are ideal for use in bioimaging applications.

  2. Dual role of monolayer MoS2 in enhanced photocatalytic performance of hybrid MoS2/SnO2 nanocomposite

    Science.gov (United States)

    Ding, Shuang-Shuang; Huang, Wei-Qing; Yang, Yin-Cai; Zhou, Bing-Xin; Hu, Wang-Yu; Long, Meng-Qiu; Peng, P.; Huang, Gui-Fang

    2016-05-01

    The enhanced photocatalytic performance of various MoS2-based nanomaterials has recently been observed, but the role of monolayer MoS2 is still not well elucidated at the electronic level. Herein, focusing on a model system, hybrid MoS2/SnO2 nanocomposite, we first present a theoretical elucidation of the dual role of monolayer MoS2 as a sensitizer and a co-catalyst by performing density functional theory calculations. It is demonstrated that a type-II, staggered, band alignment of ˜0.49 eV exists between monolayer MoS2 and SnO2 with the latter possessing the higher electron affinity, or work function, leading to the robust separation of photoexcited charge carriers between the two constituents. Under irradiation, the electrons are excited from Mo 4d orbitals to SnO2, thus enhancing the reduction activity of latter, indicating that the monolayer MoS2 is an effective sensitizer. Moreover, the Mo atoms, which are catalytically inert in isolated monolayer MoS2, turn into catalytic active sites, making the monolayer MoS2 to be a highly active co-catalyst in the composite. The dual role of monolayer MoS2 is expected to arise in other MoS2-semiconductor nanocomposites. The calculated absorption spectra can be rationalized by available experimental results. These findings provide theoretical evidence supporting the experimental reports and pave the way for developing highly efficient MoS2-based photocatalysts.

  3. NOVEL ASPECTS OF SPOTTED WING DROSOPHILA BIOLOGY AND IMPROVED METHODS OF REARING

    Science.gov (United States)

    Drosophila suzukii (Mats.) or the spotted wing Drosophila (SWD), is a global pest of soft fruits that can now be reared on a standard Drosophila diet containing the fly's own natural food: soft-skinned berries. The techniques tested here can thwart bacterial and fungal disease that can destroy more ...

  4. Maximum likelihood estimation of ancestral codon usage bias parameters in Drosophila

    DEFF Research Database (Denmark)

    Nielsen, Rasmus; Bauer DuMont, Vanessa L; Hubisz, Melissa J

    2007-01-01

    : the selection coefficient for optimal codon usage (S), allowing joint maximum likelihood estimation of S and the dN/dS ratio. We apply the method to previously published data from Drosophila melanogaster, Drosophila simulans, and Drosophila yakuba and show, in accordance with previous results, that the D...

  5. Drosophila-based in vivo assay for the validation of inhibitors of the ...

    Indian Academy of Sciences (India)

    Photoshop 7.0. 3. Results. In order to identify the suitability of the Drosophila model system for screening TKIs, sequence similarity of the. TK domain of EGFR between humans and Drosophila melanogaster was compared. In silico docking results of the. TKIs to the modelled Drosophila TK domain of EGFR were.

  6. Study of radioadaptive response in Drosophila melanogaster at different oogenesis stages

    International Nuclear Information System (INIS)

    Glushkova, I.V.; Aksyutik, T.V.

    2005-01-01

    We study radioadaptive response in the Canton-S strain of Drosophila melanogaster at different oogenesis stages using the test of dominant lethal mutations (DLM). AR was not revealed at the stages of 14-7 and 7--1 oocytes in the studied Drosophila stock. It is likely to be associated with a genetic constitution of the Drosophila strain under study. (authors)

  7. 40 CFR 798.5955 - Heritable translocation test in drosophila melanogaster.

    Science.gov (United States)

    2010-07-01

    ... drosophila melanogaster. 798.5955 Section 798.5955 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....5955 Heritable translocation test in drosophila melanogaster. (a) Purpose. The heritable translocation test in Drosophila measures the induction of chromosomal translocations in germ cells of insects...

  8. The dopaminergic system in the aging brain of Drosophila

    Directory of Open Access Journals (Sweden)

    Katherine E White

    2010-12-01

    Full Text Available Drosophila models of Parkinson’s disease are characterised by two principal phenotypes: the specific loss of dopaminergic neurons in the aging brain and defects in motor behavior. However, an age-related analysis of these baseline parameters in wildtype Drosophila is lacking. Here we analysed the dopaminergic system and motor behavior in aging Drosophila. Dopaminergic neurons in the adult brain can be grouped into bilateral symmetric clusters, each comprising a stereotypical number of cells. Analysis of TH>mCD8::GFP and cell type-specific MARCM clones revealed that dopaminergic neurons show cluster-specific, stereotypical projection patterns with terminal arborization in target regions that represent distinct functional areas of the adult brain. Target areas include the mushroom bodies, involved in memory formation and motivation, and the central complex, involved in the control of motor behavior, indicating that similar to the mammalian brain, dopaminergic neurons in the fly brain are involved in the regulation of specific behaviors. Behavioral analysis revealed that Drosophila show an age-related decline in startle-induced locomotion and negative geotaxis. Motion tracking however, revealed that walking activity and exploration behavior, but not centrophobism increase at late stages of life. Analysis of TH>Dcr2, mCD8::GFP revealed a specific effect of Dcr2 expression on walking activity but not on exploratory or centrophobic behavior, indicating that the siRNA pathway may modulate distinct dopaminergic behaviors in Drosophila. Moreover, dopaminergic neurons were maintained between early- and late life, as quantified by TH>mCD8::GFP and anti-TH labelling, indicating that adult onset, age-related degeneration of dopaminergic neurons does not occur in the aging brain of Drosophila. Taken together, our data establish baseline parameters in Drosophila for the study of Parkinson’s disease as well as other disorders affecting dopaminergic neurons

  9. The dopaminergic system in the aging brain of Drosophila.

    Science.gov (United States)

    White, Katherine E; Humphrey, Dickon M; Hirth, Frank

    2010-01-01

    Drosophila models of Parkinson's disease are characterized by two principal phenotypes: the specific loss of dopaminergic (DA) neurons in the aging brain and defects in motor behavior. However, an age-related analysis of these baseline parameters in wildtype Drosophila is lacking. Here we analyzed the DA system and motor behavior in aging Drosophila. DA neurons in the adult brain can be grouped into bilateral symmetric clusters, each comprising a stereotypical number of cells. Analysis of TH > mCD8::GFP and cell type-specific MARCM clones revealed that DA neurons show cluster-specific, stereotypical projection patterns with terminal arborization in target regions that represent distinct functional areas of the adult brain. Target areas include the mushroom bodies, involved in memory formation and motivation, and the central complex, involved in the control of motor behavior, indicating that similar to the mammalian brain, DA neurons in the fly brain are involved in the regulation of specific behaviors. Behavioral analysis revealed that Drosophila show an age-related decline in startle-induced locomotion and negative geotaxis. Motion tracking however, revealed that walking activity, and exploration behavior, but not centrophobism increase at late stages of life. Analysis of TH > Dcr2, mCD8::GFP revealed a specific effect of Dcr2 expression on walking activity but not on exploratory or centrophobic behavior, indicating that the siRNA pathway may modulate distinct DA behaviors in Drosophila. Moreover, DA neurons were maintained between early- and late life, as quantified by TH > mCD8::GFP and anti-TH labeling, indicating that adult onset, age-related degeneration of DA neurons does not occur in the aging brain of Drosophila. Taken together, our data establish baseline parameters in Drosophila for the study of Parkinson's disease as well as other disorders affecting DA neurons and movement control.

  10. Low sub-threshold swing realization with contacts of graphene/h-BN/MoS2 heterostructures in MoS2 transistors

    Science.gov (United States)

    Li, Chao; Yan, Xiao; Bao, Wenzhong; Ding, Shijin; Zhang, David Wei; Zhou, Peng

    2017-11-01

    MoS2 and other atomically thin-layered semiconductors have attracted intensive interest for their unique characteristics and have become promising candidates for short-channel transistor devices. In this work, we demonstrate an MoS2 transistor with a graphene/hBN/MoS2 heterostructure contact so as to achieve a low sub-threshold swing (SS) and expand the scope of the drain current with a low SS. By inserting an h-BN tunneling layer between graphene and MoS2, the carrier transport with a tunneling effect across h-BN makes the transistor exhibit a less than 80 mV/dec sub-threshold swing over 4 orders of magnitude of the drain current at room temperature. Meanwhile, the MoS2 transistor achieves a maximum on/off ratio of ˜107, and the heterostructure contact shows fairly good ohmic characteristics. Furthermore, the thickness of the h-BN tunneling layer in the heterostructure is optimized, which is essential for the tunneling current and the performance of an MoS2 transistor. This study of an MoS2 transistor based on a graphene/h-BN/MoS2 heterostructure contact may pave the way for the development of thin-layered semiconductors in low-power electronic applications.

  11. Improved wavelengths for the 1s2s3S1-1s2p3P0,2 transitions in helium-like Si12+

    International Nuclear Information System (INIS)

    Armour, I.A.; Myers, E.G.; Silver, J.D.; Traebert, E.; Oxford Univ.

    1979-01-01

    The wavelengths of the 1s2s 3 S 1 -1s2p 3 P 0 , 2 transitions in He-like Si 12+ have been remaesured to be 87.86 +- 0.01 nm and 81.48 +- 0.01 nm. The use of Rydberg lines for the calibration of fast beam spectra is discussed. (orig.)

  12. Adsorption of DNA/RNA nucleobases onto single-layer MoS2 and Li-Doped MoS2: A dispersion-corrected DFT study

    Science.gov (United States)

    Sadeghi, Meisam; Jahanshahi, Mohsen; Ghorbanzadeh, Morteza; Najafpour, Ghasem

    2018-03-01

    The kind of sensing platform in nano biosensor plays an important role in nucleic acid sequence detection. It has been demonstrated that graphene does not have an intrinsic band gap; therefore, transition metal dichalcogenides (TMDs) are desirable materials for electronic base detection. In the present work, a comparative study of the adsorption of the DNA/RNA nucleobases [Adenine (A), Cytosine (C) Guanine (G), Thymine (T) and Uracil (U)] onto the single-layer molybdenum disulfide (MoS2) and Li-doped MoS2 (Li-MoS2) as a sensing surfaces was investigated by using Dispersion-corrected Density Functional Theory (D-DFT) calculations and different measure of equilibrium distances, charge transfers and binding energies for the various nucleobases were calculated. The results revealed that the interactions between the nucleobases and the MoS2 can be strongly enhanced by introducing metal atom, due to significant charge transfer from the Li atom to the MoS2 when Lithium is placed on top of the MoS2. Furthermore, the binding energies of the five nucleobases were in the range of -0.734 to -0.816 eV for MoS2 and -1.47 to -1.80 eV for the Li-MoS2. Also, nucleobases were adsorbed onto MoS2 sheets via the van der Waals (vdW) force. This high affinity and the renewable properties of the biosensing platform demonstrated that Li-MoS2 nanosheet is biocompatible and suitable for nucleic acid analysis.

  13. Evaluation of Off-season Potential Breeding Sources for Spotted Wing Drosophila (Drosophila suzukii Matsumura) in Michigan.

    Science.gov (United States)

    Bal, Harit K; Adams, Christopher; Grieshop, Matthew

    2017-12-05

    It has been suggested that fruit wastes including dropped and unharvested fruits, and fruit byproducts (i.e., pomace) found in fruit plantings and cideries or wine-making facilities could serve as potential off-season breeding sites for spotted wing Drosophila (Drosophila suzukii Matsumura (Diptera: Drosophilidae)). This idea, however, has yet to be widely tested. The goal of our study was to determine the potential of dropped fruit and fruit wastes as Fall spotted wing Drosophila breeding resources in Michigan, USA. Fruit waste samples were collected from 15 farms across the lower peninsula of Michigan and were evaluated for spotted wing Drosophila and other drosophilid emergence and used in host suitability bioassays. All of the dropped apples, pears, grapes, and raspberries and 40% of apple and 100% of grape fruit pomace evaluated were found to contain spotted wing Drosophila with the highest numbers collected from dropped grapes and pears. Greater spotted wing Drosophila recovery was found in fruit wastes at sites attached with cideries and wine-making facilities and with multiple cultivated fruit crops than sites with no cideries and only one crop. Females oviposited in raspberry, pear, apple, grape, apple pomace and grape pomace samples with the highest rates of reproduction in raspberries. Our results demonstrate that fruit wastes including dropped berry, pomme and stone fruits, as well as fruit compost may be important late season reproductive resources for spotted wing Drosophila. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Deep-level transient spectroscopy of TiO2/CuInS2 heterojunctions

    NARCIS (Netherlands)

    Nanu, M.; Boulch, F.; Schoonman, J.; Goossens, A.

    2005-01-01

    Deep-level transient spectroscopy (DLTS) has been used to measure the concentration and energy position of deep electronic states in CuInS2. Flat TiO2?CuInS2 heterojunctions as well as TiO2-CuInS2 nanocomposites have been investigated. Subband-gap electronic states in CuInS2 films are mostly due to

  15. MoS2 Nanoparticles Grown on Graphene: An Advanced Catalyst for Hydrogen Evolution Reaction

    OpenAIRE

    Li, Yanguang; Wang, Hailiang; Xie, Liming; Liang, Yongye; Hong, Guosong; Dai, Hongjie

    2011-01-01

    Advanced materials for electrocatalytic and photoelectrochemical water splitting are central to the area of renewable energy. Here, we developed a solvothermal synthesis of MoS2 nanoparticles selectively on reduced graphene oxide (RGO) sheets suspended in solution. The resulting MoS2/RGO hybrid material possessed nanoscopic few-layer MoS2 structures with abundant exposed edges stacked onto graphene, in strong contrast to large aggregated MoS2 particles grown freely in solution without GO. The...

  16. Bioimage Informatics in the context of Drosophila research.

    Science.gov (United States)

    Jug, Florian; Pietzsch, Tobias; Preibisch, Stephan; Tomancak, Pavel

    2014-06-15

    Modern biological research relies heavily on microscopic imaging. The advanced genetic toolkit of Drosophila makes it possible to label molecular and cellular components with unprecedented level of specificity necessitating the application of the most sophisticated imaging technologies. Imaging in Drosophila spans all scales from single molecules to the entire populations of adult organisms, from electron microscopy to live imaging of developmental processes. As the imaging approaches become more complex and ambitious, there is an increasing need for quantitative, computer-mediated image processing and analysis to make sense of the imagery. Bioimage Informatics is an emerging research field that covers all aspects of biological image analysis from data handling, through processing, to quantitative measurements, analysis and data presentation. Some of the most advanced, large scale projects, combining cutting edge imaging with complex bioimage informatics pipelines, are realized in the Drosophila research community. In this review, we discuss the current research in biological image analysis specifically relevant to the type of systems level image datasets that are uniquely available for the Drosophila model system. We focus on how state-of-the-art computer vision algorithms are impacting the ability of Drosophila researchers to analyze biological systems in space and time. We pay particular attention to how these algorithmic advances from computer science are made usable to practicing biologists through open source platforms and how biologists can themselves participate in their further development. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  17. big bang gene modulates gut immune tolerance in Drosophila.

    Science.gov (United States)

    Bonnay, François; Cohen-Berros, Eva; Hoffmann, Martine; Kim, Sabrina Y; Boulianne, Gabrielle L; Hoffmann, Jules A; Matt, Nicolas; Reichhart, Jean-Marc

    2013-02-19

    Chronic inflammation of the intestine is detrimental to mammals. Similarly, constant activation of the immune response in the gut by the endogenous flora is suspected to be harmful to Drosophila. Therefore, the innate immune response in the gut of Drosophila melanogaster is tightly balanced to simultaneously prevent infections by pathogenic microorganisms and tolerate the endogenous flora. Here we describe the role of the big bang (bbg) gene, encoding multiple membrane-associated PDZ (PSD-95, Discs-large, ZO-1) domain-containing protein isoforms, in the modulation of the gut immune response. We show that in the adult Drosophila midgut, BBG is present at the level of the septate junctions, on the apical side of the enterocytes. In the absence of BBG, these junctions become loose, enabling the intestinal flora to trigger a constitutive activation of the anterior midgut immune response. This chronic epithelial inflammation leads to a reduced lifespan of bbg mutant flies. Clearing the commensal flora by antibiotics prevents the abnormal activation of the gut immune response and restores a normal lifespan. We now provide genetic evidence that Drosophila septate junctions are part of the gut immune barrier, a function that is evolutionarily conserved in mammals. Collectively, our data suggest that septate junctions are required to maintain the subtle balance between immune tolerance and immune response in the Drosophila gut, which represents a powerful model to study inflammatory bowel diseases.

  18. Transmembrane channel-like (tmc) gene regulates Drosophila larval locomotion.

    Science.gov (United States)

    Guo, Yanmeng; Wang, Yuping; Zhang, Wei; Meltzer, Shan; Zanini, Damiano; Yu, Yue; Li, Jiefu; Cheng, Tong; Guo, Zhenhao; Wang, Qingxiu; Jacobs, Julie S; Sharma, Yashoda; Eberl, Daniel F; Göpfert, Martin C; Jan, Lily Yeh; Jan, Yuh Nung; Wang, Zuoren

    2016-06-28

    Drosophila larval locomotion, which entails rhythmic body contractions, is controlled by sensory feedback from proprioceptors. The molecular mechanisms mediating this feedback are little understood. By using genetic knock-in and immunostaining, we found that the Drosophila melanogaster transmembrane channel-like (tmc) gene is expressed in the larval class I and class II dendritic arborization (da) neurons and bipolar dendrite (bd) neurons, both of which are known to provide sensory feedback for larval locomotion. Larvae with knockdown or loss of tmc function displayed reduced crawling speeds, increased head cast frequencies, and enhanced backward locomotion. Expressing Drosophila TMC or mammalian TMC1 and/or TMC2 in the tmc-positive neurons rescued these mutant phenotypes. Bending of the larval body activated the tmc-positive neurons, and in tmc mutants this bending response was impaired. This implicates TMC's roles in Drosophila proprioception and the sensory control of larval locomotion. It also provides evidence for a functional conservation between Drosophila and mammalian TMCs.

  19. Identification of the Drosophila Mes4 gene as a novel target of the transcription factor DREF

    Energy Technology Data Exchange (ETDEWEB)

    Suyari, Osamu; Ida, Hiroyuki [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Yoshioka, Yasuhide; Kato, Yasuko; Hashimoto, Reina [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Venture Laboratory, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Yamaguchi, Masamitsu, E-mail: myamaguc@kit.ac.jp [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan)

    2009-05-01

    The Mes4 gene has been identified as one of the maternal Dorsal target genes in Drosophila. In the present study, we found a DNA replication-related element (DRE, 5'-TATCGATA) in the Mes4 promoter recognized by the DRE-binding factor (DREF). Luciferase transient expression assays in S2 cells using Mes4 promoter-luciferase fusion plasmids revealed that the DRE sequence is essential for Mes4 promoter activity. Requirement of DRE for Mes4 promoter activity was further confirmed by anti-{beta}-galactosidase antibody-staining of various tissues from transgenic flies carrying Mes4 promoter-lacZ fusion genes. Furthermore, wild type Mes4 promoter activity was decreased by 40% in DREF-depleted S2 cells. These results indicate that DREF positively regulates Mes4 gene expression. Band mobility shift analyses using Kc cell nuclear extracts further indicated that the DRE sequence in the Mes4 promoter is especially important for binding to DREF. Moreover, specific binding of DREF to the involved genomic region could be demonstrated by chromatin immunoprecipitation assays using anti-DREF antibodies. These results, taken together, indicate that the DRE/DREF system activates transcription of the Mes4 gene. In addition, knockdown of the Mes4 gene in wing imaginal discs using the GAL4-UAS system caused an atrophied wing phenotype, suggesting that Mes4 is required for wing morphogenesis.

  20. Rendering high charge density of states in ionic liquid-gated MoS 2 transistors

    NARCIS (Netherlands)

    Lee, Y.; Lee, J.; Kim, S.; Park, H.S.

    2014-01-01

    We investigated high charge density of states (DOS) in the bandgap of MoS2 nanosheets with variable temperature measurements on ionic liquid-gated MoS2 transistors. The thermally activated charge transport indicates that the electrical current in the two-dimensional MoS 2 nanosheets under high

  1. Acetylations of Ftz-F1 and histone H4K5 are required for the fine-tuning of ecdysone biosynthesis during Drosophila metamorphosis.

    Science.gov (United States)

    Borsos, Barbara N; Pankotai, Tibor; Kovács, Dávid; Popescu, Christina; Páhi, Zoltán; Boros, Imre M

    2015-08-01

    The molting during Drosophila development is tightly regulated by the ecdysone hormone. Several steps of the ecdysone biosynthesis have been already identified but the regulation of the entire process has not been clarified yet. We have previously reported that dATAC histone acetyltransferase complex is necessary for the steroid hormone biosynthesis process. To reveal possible mechanisms controlled by dATAC we made assumptions that either dATAC may influence directly the transcription of Halloween genes involved in steroid hormone biosynthesis or it may exert an indirect effect on it by acetylating the Ftz-F1 transcription factor which regulates the transcription of steroid converting genes. Here we show that the lack of dATAC complex results in increased mRNA level and decreased protein level of Ftz-F1. In this context, decreased mRNA and increased protein levels of Ftz-F1 were detected upon treatment of Drosophila S2 cells with histone deacetylase inhibitor trichostatin A. We showed that Ftz-F1, the transcriptional activator of Halloween genes, is acetylated in S2 cells. In addition, we found that ecdysone biosynthetic Halloween genes are transcribed in S2 cells and their expression can be influenced by deacetylase inhibitors. Furthermore, we could detect H4K5 acetylation at the regulatory regions of disembodied and shade Halloween genes, while H3K9 acetylation is absent on these genes. Based on our findings we conclude that the dATAC HAT complex might play a dual regulatory role in Drosophila steroid hormone biosynthesis through the acetylation of Ftz-F1 protein and the regulation of the H4K5 acetylation at the promoters of Halloween genes. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Molecular cloning and genomic organization of a second probable allatostatin receptor from Drosophila melanogaster

    DEFF Research Database (Denmark)

    Lenz, C; Williamson, M; Grimmelikhuijzen, C J

    2000-01-01

    We (C. Lenz et al. (2000) Biochem. Biophys. Res. Commun. 269, 91-96) and others (N. Birgül et al. (1999) EMBO J. 18, 5892-5900) have recently cloned a Drosophila receptor that was structurally related to the mammalian galanin receptors, but turned out to be a receptor for a Drosophila peptide...... with a Drosophila genomic database clone that contained a DNA sequence coding for a protein having, again, structural similarities with the rat galanin receptors. Using PCR with primers coding for the presumed exons of this second Drosophila receptor gene, 5'- and 3'-RACE, and Drosophila cDNA as template, we...

  3. Biological radiation effects of Radon in Drosophila

    International Nuclear Information System (INIS)

    Pimentel P, A.E.

    1995-01-01

    In order to contribute to the knowledge on the effects of radon and its decay products, the aim of this investigation is to study the biological effects of radon using Drosophila melanogaster throught the somatic mutation and recombination test (SMART) and the analysis of some adaptative factors exposing larvaes to controlled radon atmosphers, considering that this insect could be used as biological monitor. Using the somatic mutation test a mutagenic effect was observed proportional to radon concentration, into an interval of 1 ± 0.3 to 111 ± 7.4 KBq/m 3 equivalent to doses under 0.0106 Gy. The correlation analysis gives a linear (r=0.80) relationship with a positive slope of 0.2217. The same happens when gamma rays are used in the interval of 1 to 20 Gy, given a linear dose-dependent effect (r=0.878) is obtained; nevetheless the slop is smaller (m=0.003) than for radon. Analysing the results of adaptative factors of the nine exposed generations, it was found that probably radon exposition induced dominant lethals during gametogenesis or/and a selection of the more component gamets of the treated individuals in larval state. It was reflected in the significant decrease on fecundity of the generation exposed. Nevertheless the laying eggs had an increase in egg-to-adult viability and the develop velocity was higher than in control for 3 KBq/m 3 , this suggest that radon concentrations used were able to induce repair mechanisms. These data agree with the Hormesis hypothesis that says: low doses have positive effects on health. It was not possible to obtain a dose-effect relationship except with the develop velocity where it was found a dose-effect inverse proportion. In conclusion, Drosophila melanogaster could be a good system to obtain in vivo damaged induction concentration dependent of radon and its decay products, as well as to study the effects in an exposed population by the analysis of adaptative factors. (Author)

  4. Analysis of Thisbe and Pyramus functional domains reveals evidence for cleavage of Drosophila FGFs

    Directory of Open Access Journals (Sweden)

    Stathopoulos Angelike

    2010-08-01

    Full Text Available Abstract Background As important regulators of developmental and adult processes in metazoans, Fibroblast Growth Factor (FGF proteins are potent signaling molecules whose activities must be tightly regulated. FGFs are known to play diverse roles in many processes, including mesoderm induction, branching morphogenesis, organ formation, wound healing and malignant transformation; yet much more remains to be learned about the mechanisms of regulation used to control FGF activity. Results In this work, we conducted an analysis of the functional domains of two Drosophila proteins, Thisbe (Ths and Pyramus (Pyr, which share homology with the FGF8 subfamily of ligands in vertebrates. Ths and Pyr proteins are secreted from Drosophila Schneider cells (S2 as smaller N-terminal fragments presumably as a result of intracellular proteolytic cleavage. Cleaved forms of Ths and Pyr can be detected in embryonic extracts as well. The FGF-domain is contained within the secreted ligand portion, and this domain alone is capable of functioning in the embryo when ectopically expressed. Through targeted ectopic expression experiments in which we assay the ability of full-length, truncated, and chimeric proteins to support cell differentiation, we find evidence that (1 the C-terminal domain of Pyr is retained inside the cell and does not seem to be required for receptor activation and (2 the C-terminal domain of Ths is secreted and, while also not required for receptor activation, this domain does plays a role in limiting the activity of Ths when present. Conclusions We propose that differential protein processing may account for the previously observed inequalities in signaling capabilities between Ths and Pyr. While the regulatory mechanisms are likely complex, studies such as ours conducted in a tractable model system may be able to provide insights into how ligand processing regulates growth factor activity.

  5. Quantifying host potentials: indexing postharvest fresh fruits for spotted wing Drosophila, Drosophila suzukii.

    Directory of Open Access Journals (Sweden)

    David E Bellamy

    Full Text Available Novel methodology is presented for indexing the relative potential of hosts to function as resources. A Host Potential Index (HPI was developed as a practical framework to express relative host potential based on combining results from one or more independent studies, such as those examining host selection, utilization, and physiological development of the organism resourcing the host. Several aspects of the HPI are addressed including: 1 model derivation; 2 influence of experimental design on establishing host rankings for a study type (no choice, two-choice, and multiple-choice; and, 3 variable selection and weighting associated with combining multiple studies. To demonstrate application of the HPI, results from the interactions of spotted wing drosophila (SWD, Drosophila suzukii Matsumura (Diptera: Drosophilidae, with seven "reported" hosts (blackberries, blueberries, sweet cherries, table grapes, peaches, raspberries, and strawberries in a postharvest scenario were analyzed. Four aspects of SWD-host interaction were examined: attraction to host volatiles; population-level oviposition performance; individual-level oviposition performance; and key developmental factors. Application of HPI methodology indicated that raspberries ( (meanHPIvaried  = 301.9±8.39; rank 1 of 7 have the greatest potential to serve as a postharvest host for SWD relative to the other fruit hosts, with grapes ( (meanHPIvaried  = 232.4±3.21; rank 7 of 7 having the least potential.

  6. Identification and characterization of novel natural pathogen of Drosophila melanogaster isolated from wild captured Drosophila spp.

    Science.gov (United States)

    Singh, Karan; Zulkifli, Mohammad; Prasad, N G

    2016-12-01

    Drosophila melanogaster is an emerging model system for the study of evolutionary ecology of immunity. However, a large number of studies have used non natural pathogens as very few natural pathogens have been isolated and identified. Our aim was to isolate and characterize natural pathogen/s of D. melanogaster. A bacterial pathogen was isolated from wild caught Drosophila spp., identified as a new strain of Staphylococcus succinus subsp. succinus and named PK-1. This strain induced substantial mortality (36-62%) in adults of several laboratory populations of D. melanogaster. PK-1 grew rapidly within the body of the flies post infection and both males and females had roughly same number of colony forming units. Mortality was affected by mode of infection and dosage of the pathogen. However mating status of the host had no effect on mortality post infection. Given that there are very few known natural bacterial pathogens of D. melanogaster and that PK-1 can establish a sustained infection across various outbred and inbred populations of D. melanogaster this new isolate is a potential resource for future studies on immunity. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  7. Comparative population genomics of latitudinal variation in Drosophila simulans and Drosophila melanogaster.

    Science.gov (United States)

    Machado, Heather E; Bergland, Alan O; O'Brien, Katherine R; Behrman, Emily L; Schmidt, Paul S; Petrov, Dmitri A

    2016-02-01

    Examples of clinal variation in phenotypes and genotypes across latitudinal transects have served as important models for understanding how spatially varying selection and demographic forces shape variation within species. Here, we examine the selective and demographic contributions to latitudinal variation through the largest comparative genomic study to date of Drosophila simulans and Drosophila melanogaster, with genomic sequence data from 382 individual fruit flies, collected across a spatial transect of 19 degrees latitude and at multiple time points over 2 years. Consistent with phenotypic studies, we find less clinal variation in D. simulans than D. melanogaster, particularly for the autosomes. Moreover, we find that clinally varying loci in D. simulans are less stable over multiple years than comparable clines in D. melanogaster. D. simulans shows a significantly weaker pattern of isolation by distance than D. melanogaster and we find evidence for a stronger contribution of migration to D. simulans population genetic structure. While population bottlenecks and migration can plausibly explain the differences in stability of clinal variation between the two species, we also observe a significant enrichment of shared clinal genes, suggesting that the selective forces associated with climate are acting on the same genes and phenotypes in D. simulans and D. melanogaster. © 2015 John Wiley & Sons Ltd.

  8. Relative roles of the cellular and humoral responses in the Drosophila host defense against three gram-positive bacterial infections.

    Directory of Open Access Journals (Sweden)

    Nadine T Nehme

    2011-03-01

    Full Text Available Two NF-kappaB signaling pathways, Toll and immune deficiency (imd, are required for survival to bacterial infections in Drosophila. In response to septic injury, these pathways mediate rapid transcriptional activation of distinct sets of effector molecules, including antimicrobial peptides, which are important components of a humoral defense response. However, it is less clear to what extent macrophage-like hemocytes contribute to host defense.In order to dissect the relative importance of humoral and cellular defenses after septic injury with three different gram-positive bacteria (Micrococcus luteus, Enterococcus faecalis, Staphylococcus aureus, we used latex bead pre-injection to ablate macrophage function in flies wildtype or mutant for various Toll and imd pathway components. We found that in all three infection models a compromised phagocytic system impaired fly survival--independently of concomitant Toll or imd pathway activation. Our data failed to confirm a role of the PGRP-SA and GNBP1 Pattern Recognition Receptors for phagocytosis of S. aureus. The Drosophila scavenger receptor Eater mediates the phagocytosis by hemocytes or S2 cells of E. faecalis and S. aureus, but not of M. luteus. In the case of M. luteus and E. faecalis, but not S. aureus, decreased survival due to defective phagocytosis could be compensated for by genetically enhancing the humoral immune response.Our results underscore the fundamental importance of both cellular and humoral mechanisms in Drosophila immunity and shed light on the balance between these two arms of host defense depending on the invading pathogen.

  9. Autophagy in Drosophila: From Historical Studies to Current Knowledge

    Science.gov (United States)

    Mulakkal, Nitha C.; Nagy, Peter; Takats, Szabolcs; Tusco, Radu; Juhász, Gábor; Nezis, Ioannis P.

    2014-01-01

    The discovery of evolutionarily conserved Atg genes required for autophagy in yeast truly revolutionized this research field and made it possible to carry out functional studies on model organisms. Insects including Drosophila are classical and still popular models to study autophagy, starting from the 1960s. This review aims to summarize past achievements and our current knowledge about the role and regulation of autophagy in Drosophila, with an outlook to yeast and mammals. The basic mechanisms of autophagy in fruit fly cells appear to be quite similar to other eukaryotes, and the role that this lysosomal self-degradation process plays in Drosophila models of various diseases already made it possible to recognize certain aspects of human pathologies. Future studies in this complete animal hold great promise for the better understanding of such processes and may also help finding new research avenues for the treatment of disorders with misregulated autophagy. PMID:24949430

  10. Localized expression pattern of miR-184 in Drosophila.

    Science.gov (United States)

    Li, Ping; Peng, Jianjian; Hu, Jiangbo; Xu, Zhongxin; Xie, Wei; Yuan, Liudi

    2011-01-01

    MicroRNAs (miRNAs) are a kind of endogenous non-coding small RNAs whose specific functions in animals are generally important. Although functions of some miRNAs have been identified, the role of miR-184 remains unknown. Here, we determined the temporal and spatial expression pattern of miR-184 during the different development stages and tissues in Drosophila. Strikingly, miR-184 is expressed ubiquitously in Drosophila embryos, larvae and adults, its expression pattern shows a dynamic changes during the development of embryo, especially in the central nervous system. This expression profile suggests that miR-184 may act important function in Drosophila development.

  11. Analysis of Cell Cycle Switches in Drosophila Oogenesis.

    Science.gov (United States)

    Jia, Dongyu; Huang, Yi-Chun; Deng, Wu-Min

    2015-01-01

    The study of Drosophila oogenesis provides invaluable information about signaling pathway regulation and cell cycle programming. During Drosophila oogenesis, a string of egg chambers in each ovariole progressively develops toward maturity. Egg chamber development consists of 14 stages. From stage 1 to stage 6 (mitotic cycle), main-body follicle cells undergo mitotic divisions. From stage 7 to stage 10a (endocycle), follicle cells cease mitosis but continue three rounds of endoreduplication. From stage 10b to stage 13 (gene amplification), instead of whole genome duplication, follicle cells selectively amplify specific genomic regions, mostly for chorion production. So far, Drosophila oogenesis is one of the most well studied model systems used to understand cell cycle switches, which furthers our knowledge about cell cycle control machinery and sheds new light on potential cancer treatments. Here, we give a brief summary of cell cycle switches, the associated signaling pathways and factors, and the detailed experimental procedures used to study the cell cycle switches.

  12. Evolution of genes and genomes on the Drosophila phylogeny.

    Science.gov (United States)

    Clark, Andrew G; Eisen, Michael B; Smith, Douglas R; Bergman, Casey M; Oliver, Brian; Markow, Therese A; Kaufman, Thomas C; Kellis, Manolis; Gelbart, William; Iyer, Venky N; Pollard, Daniel A; Sackton, Timothy B; Larracuente, Amanda M; Singh, Nadia D; Abad, Jose P; Abt, Dawn N; Adryan, Boris; Aguade, Montserrat; Akashi, Hiroshi; Anderson, Wyatt W; Aquadro, Charles F; Ardell, David H; Arguello, Roman; Artieri, Carlo G; Barbash, Daniel A; Barker, Daniel; Barsanti, Paolo; Batterham, Phil; Batzoglou, Serafim; Begun, Dave; Bhutkar, Arjun; Blanco, Enrico; Bosak, Stephanie A; Bradley, Robert K; Brand, Adrianne D; Brent, Michael R; Brooks, Angela N; Brown, Randall H; Butlin, Roger K; Caggese, Corrado; Calvi, Brian R; Bernardo de Carvalho, A; Caspi, Anat; Castrezana, Sergio; Celniker, Susan E; Chang, Jean L; Chapple, Charles; Chatterji, Sourav; Chinwalla, Asif; Civetta, Alberto; Clifton, Sandra W; Comeron, Josep M; Costello, James C; Coyne, Jerry A; Daub, Jennifer; David, Robert G; Delcher, Arthur L; Delehaunty, Kim; Do, Chuong B; Ebling, Heather; Edwards, Kevin; Eickbush, Thomas; Evans, Jay D; Filipski, Alan; Findeiss, Sven; Freyhult, Eva; Fulton, Lucinda; Fulton, Robert; Garcia, Ana C L; Gardiner, Anastasia; Garfield, David A; Garvin, Barry E; Gibson, Greg; Gilbert, Don; Gnerre, Sante; Godfrey, Jennifer; Good, Robert; Gotea, Valer; Gravely, Brenton; Greenberg, Anthony J; Griffiths-Jones, Sam; Gross, Samuel; Guigo, Roderic; Gustafson, Erik A; Haerty, Wilfried; Hahn, Matthew W; Halligan, Daniel L; Halpern, Aaron L; Halter, Gillian M; Han, Mira V; Heger, Andreas; Hillier, LaDeana; Hinrichs, Angie S; Holmes, Ian; Hoskins, Roger A; Hubisz, Melissa J; Hultmark, Dan; Huntley, Melanie A; Jaffe, David B; Jagadeeshan, Santosh; Jeck, William R; Johnson, Justin; Jones, Corbin D; Jordan, William C; Karpen, Gary H; Kataoka, Eiko; Keightley, Peter D; Kheradpour, Pouya; Kirkness, Ewen F; Koerich, Leonardo B; Kristiansen, Karsten; Kudrna, Dave; Kulathinal, Rob J; Kumar, Sudhir; Kwok, Roberta; Lander, Eric; Langley, Charles H; Lapoint, Richard; Lazzaro, Brian P; Lee, So-Jeong; Levesque, Lisa; Li, Ruiqiang; Lin, Chiao-Feng; Lin, Michael F; Lindblad-Toh, Kerstin; Llopart, Ana; Long, Manyuan; Low, Lloyd; Lozovsky, Elena; Lu, Jian; Luo, Meizhong; Machado, Carlos A; Makalowski, Wojciech; Marzo, Mar; Matsuda, Muneo; Matzkin, Luciano; McAllister, Bryant; McBride, Carolyn S; McKernan, Brendan; McKernan, Kevin; Mendez-Lago, Maria; Minx, Patrick; Mollenhauer, Michael U; Montooth, Kristi; Mount, Stephen M; Mu, Xu; Myers, Eugene; Negre, Barbara; Newfeld, Stuart; Nielsen, Rasmus; Noor, Mohamed A F; O'Grady, Patrick; Pachter, Lior; Papaceit, Montserrat; Parisi, Matthew J; Parisi, Michael; Parts, Leopold; Pedersen, Jakob S; Pesole, Graziano; Phillippy, Adam M; Ponting, Chris P; Pop, Mihai; Porcelli, Damiano; Powell, Jeffrey R; Prohaska, Sonja; Pruitt, Kim; Puig, Marta; Quesneville, Hadi; Ram, Kristipati Ravi; Rand, David; Rasmussen, Matthew D; Reed, Laura K; Reenan, Robert; Reily, Amy; Remington, Karin A; Rieger, Tania T; Ritchie, Michael G; Robin, Charles; Rogers, Yu-Hui; Rohde, Claudia; Rozas, Julio; Rubenfield, Marc J; Ruiz, Alfredo; Russo, Susan; Salzberg, Steven L; Sanchez-Gracia, Alejandro; Saranga, David J; Sato, Hajime; Schaeffer, Stephen W; Schatz, Michael C; Schlenke, Todd; Schwartz, Russell; Segarra, Carmen; Singh, Rama S; Sirot, Laura; Sirota, Marina; Sisneros, Nicholas B; Smith, Chris D; Smith, Temple F; Spieth, John; Stage, Deborah E; Stark, Alexander; Stephan, Wolfgang; Strausberg, Robert L; Strempel, Sebastian; Sturgill, David; Sutton, Granger; Sutton, Granger G; Tao, Wei; Teichmann, Sarah; Tobari, Yoshiko N; Tomimura, Yoshihiko; Tsolas, Jason M; Valente, Vera L S; Venter, Eli; Venter, J Craig; Vicario, Saverio; Vieira, Filipe G; Vilella, Albert J; Villasante, Alfredo; Walenz, Brian; Wang, Jun; Wasserman, Marvin; Watts, Thomas; Wilson, Derek; Wilson, Richard K; Wing, Rod A; Wolfner, Mariana F; Wong, Alex; Wong, Gane Ka-Shu; Wu, Chung-I; Wu, Gabriel; Yamamoto, Daisuke; Yang, Hsiao-Pei; Yang, Shiaw-Pyng; Yorke, James A; Yoshida, Kiyohito; Zdobnov, Evgeny; Zhang, Peili; Zhang, Yu; Zimin, Aleksey V; Baldwin, Jennifer; Abdouelleil, Amr; Abdulkadir, Jamal; Abebe, Adal; Abera, Brikti; Abreu, Justin; Acer, St Christophe; Aftuck, Lynne; Alexander, Allen; An, Peter; Anderson, Erica; Anderson, Scott; Arachi, Harindra; Azer, Marc; Bachantsang, Pasang; Barry, Andrew; Bayul, Tashi; Berlin, Aaron; Bessette, Daniel; Bloom, Toby; Blye, Jason; Boguslavskiy, Leonid; Bonnet, Claude; Boukhgalter, Boris; Bourzgui, Imane; Brown, Adam; Cahill, Patrick; Channer, Sheridon; Cheshatsang, Yama; Chuda, Lisa; Citroen, Mieke; Collymore, Alville; Cooke, Patrick; Costello, Maura; D'Aco, Katie; Daza, Riza; De Haan, Georgius; DeGray, Stuart; DeMaso, Christina; Dhargay, Norbu; Dooley, Kimberly; Dooley, Erin; Doricent, Missole; Dorje, Passang; Dorjee, Kunsang; Dupes, Alan; Elong, Richard; Falk, Jill; Farina, Abderrahim; Faro, Susan; Ferguson, Diallo; Fisher, Sheila; Foley, Chelsea D; Franke, Alicia; Friedrich, Dennis; Gadbois, Loryn; Gearin, Gary; Gearin, Christina R; Giannoukos, Georgia; Goode, Tina; Graham, Joseph; Grandbois, Edward; Grewal, Sharleen; Gyaltsen, Kunsang; Hafez, Nabil; Hagos, Birhane; Hall, Jennifer; Henson, Charlotte; Hollinger, Andrew; Honan, Tracey; Huard, Monika D; Hughes, Leanne; Hurhula, Brian; Husby, M Erii; Kamat, Asha; Kanga, Ben; Kashin, Seva; Khazanovich, Dmitry; Kisner, Peter; Lance, Krista; Lara, Marcia; Lee, William; Lennon, Niall; Letendre, Frances; LeVine, Rosie; Lipovsky, Alex; Liu, Xiaohong; Liu, Jinlei; Liu, Shangtao; Lokyitsang, Tashi; Lokyitsang, Yeshi; Lubonja, Rakela; Lui, Annie; MacDonald, Pen; Magnisalis, Vasilia; Maru, Kebede; Matthews, Charles; McCusker, William; McDonough, Susan; Mehta, Teena; Meldrim, James; Meneus, Louis; Mihai, Oana; Mihalev, Atanas; Mihova, Tanya; Mittelman, Rachel; Mlenga, Valentine; Montmayeur, Anna; Mulrain, Leonidas; Navidi, Adam; Naylor, Jerome; Negash, Tamrat; Nguyen, Thu; Nguyen, Nga; Nicol, Robert; Norbu, Choe; Norbu, Nyima; Novod, Nathaniel; O'Neill, Barry; Osman, Sahal; Markiewicz, Eva; Oyono, Otero L; Patti, Christopher; Phunkhang, Pema; Pierre, Fritz; Priest, Margaret; Raghuraman, Sujaa; Rege, Filip; Reyes, Rebecca; Rise, Cecil; Rogov, Peter; Ross, Keenan; Ryan, Elizabeth; Settipalli, Sampath; Shea, Terry; Sherpa, Ngawang; Shi, Lu; Shih, Diana; Sparrow, Todd; Spaulding, Jessica; Stalker, John; Stange-Thomann, Nicole; Stavropoulos, Sharon; Stone, Catherine; Strader, Christopher; Tesfaye, Senait; Thomson, Talene; Thoulutsang, Yama; Thoulutsang, Dawa; Topham, Kerri; Topping, Ira; Tsamla, Tsamla; Vassiliev, Helen; Vo, Andy; Wangchuk, Tsering; Wangdi, Tsering; Weiand, Michael; Wilkinson, Jane; Wilson, Adam; Yadav, Shailendra; Young, Geneva; Yu, Qing; Zembek, Lisa; Zhong, Danni; Zimmer, Andrew; Zwirko, Zac; Jaffe, David B; Alvarez, Pablo; Brockman, Will; Butler, Jonathan; Chin, CheeWhye; Gnerre, Sante; Grabherr, Manfred; Kleber, Michael; Mauceli, Evan; MacCallum, Iain

    2007-11-08

    Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.

  13. Evolution of Drosophila ribosomal protein gene core promoters.

    Science.gov (United States)

    Ma, Xiaotu; Zhang, Kangyu; Li, Xiaoman

    2009-03-01

    The coordinated expression of ribosomal protein genes (RPGs) has been well documented in many species. Previous analyses of RPG promoters focus only on Fungi and mammals. Recognizing this gap and using a comparative genomics approach, we utilize a motif-finding algorithm that incorporates cross-species conservation to identify several significant motifs in Drosophila RPG promoters. As a result, significant differences of the enriched motifs in RPG promoter are found among Drosophila, Fungi, and mammals, demonstrating the evolutionary dynamics of the ribosomal gene regulatory network. We also report a motif present in similar numbers of RPGs among Drosophila species which does not appear to be conserved at the individual RPG gene level. A module-wise stabilizing selection theory is proposed to explain this observation. Overall, our results provide significant insight into the fast-evolving nature of transcriptional regulation in the RPG module.

  14. Drosophila as a genetic model for studying pathogenic human viruses.

    Science.gov (United States)

    Hughes, Tamara T; Allen, Amanda L; Bardin, Joseph E; Christian, Megan N; Daimon, Kansei; Dozier, Kelsey D; Hansen, Caom L; Holcomb, Lisa M; Ahlander, Joseph

    2012-02-05

    Viruses are infectious particles whose viability is dependent on the cells of living organisms, such as bacteria, plants, and animals. It is of great interest to discover how viruses function inside host cells in order to develop therapies to treat virally infected organisms. The fruit fly Drosophila melanogaster is an excellent model system for studying the molecular mechanisms of replication, amplification, and cellular consequences of human viruses. In this review, we describe the advantages of using Drosophila as a model system to study human viruses, and highlight how Drosophila has been used to provide unique insight into the gene function of several pathogenic viruses. We also propose possible directions for future research in this area. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Patterns of mutation and selection at synonymous sites in Drosophila

    DEFF Research Database (Denmark)

    Singh, Nadia D; Bauer DuMont, Vanessa L; Hubisz, Melissa J

    2007-01-01

    That natural selection affects molecular evolution at synonymous sites in protein-coding sequences is well established and is thought to predominantly reflect selection for translational efficiency/accuracy mediated through codon bias. However, a recently developed maximum likelihood framework......, when applied to 18 coding sequences in 3 species of Drosophila, confirmed an earlier report that the Notch gene in Drosophila melanogaster was evolving under selection in favor of those codons defined as unpreferred in this species. This finding opened the possibility that synonymous sites may...... be subject to a variety of selective pressures beyond weak selection for increased frequencies of the codons currently defined as "preferred" in D. melanogaster. To further explore patterns of synonymous site evolution in Drosophila in a lineage-specific manner, we expanded the application of the maximum...

  16. RNA editing in Drosophila melanogaster: new targets and functionalconsequences

    Energy Technology Data Exchange (ETDEWEB)

    Stapleton, Mark; Carlson, Joseph W.; Celniker, Susan E.

    2006-09-05

    Adenosine deaminases that act on RNA (ADARs) catalyze the site-specific conversion of adenosine to inosine in primary mRNA transcripts. These re-coding events affect coding potential, splice-sites, and stability of mature mRNAs. ADAR is an essential gene and studies in mouse, C. elegans, and Drosophila suggest its primary function is to modify adult behavior by altering signaling components in the nervous system. By comparing the sequence of isogenic cDNAs to genomic DNA, we have identified and experimentally verified 27 new targets of Drosophila ADAR. Our analyses lead us to identify new classes of genes whose transcripts are targets of ADAR including components of the actin cytoskeleton, and genes involved in ion homeostasis and signal transduction. Our results indicate that editing in Drosophila increases the diversity of the proteome, and does so in a manner that has direct functional consequences on protein function.

  17. The Drosophila TIPE family member Sigmar interacts with the Ste20-like kinase Misshapen and modulates JNK signaling, cytoskeletal remodeling and autophagy

    Science.gov (United States)

    Chittaranjan, Suganthi; Xu, Jing; Kuzyk, Michael; Dullat, Harpreet K.; Wilton, James; DeVorkin, Lindsay; Lebovitz, Chandra; Morin, Gregg B.; Marra, Marco A.; Gorski, Sharon M.

    2015-01-01

    TNFAIP8 and other mammalian TIPE family proteins have attracted increased interest due to their associations with disease-related processes including oncogenic transformation, metastasis, and inflammation. The molecular and cellular functions of TIPE family proteins are still not well understood. Here we report the molecular and genetic characterization of the Drosophila TNFAIP8 homolog, CG4091/sigmar. Previous gene expression studies revealed dynamic expression of sigmar in larval salivary glands prior to histolysis. Here we demonstrate that in sigmar loss-of-function mutants, the salivary glands are morphologically abnormal with defects in the tubulin network and decreased autophagic flux. Sigmar localizes subcellularly to microtubule-containing projections in Drosophila S2 cells, and co-immunoprecipitates with the Ste20-like kinase Misshapen, a regulator of the JNK pathway. Further, the Drosophila TNF ligand Eiger can induce sigmar expression, and sigmar loss-of-function leads to altered localization of pDJNK in salivary glands. Together, these findings link Sigmar to the JNK pathway, cytoskeletal remodeling and autophagy activity during salivary gland development, and provide new insights into TIPE family member function. PMID:25836674

  18. Defects and Disorder in the Drosophila Eye

    Science.gov (United States)

    Kim, Sangwoo; Carthew, Richard; Hilgenfeldt, Sascha

    Cell division and differentiation tightly control the regular pattern in the normal eye of the Drosophila fruit fly while certain genetic mutations introduce disorder in the form of topological defects. Analyzing data from pupal retinas, we develop a model based on Voronoi construction that explains the defect statistics as a consequence of area variation of individual facets (ommatidia). The analysis reveals a previously unknown systematic long-range area variation that spans the entire eye, with distinct effects on topological disorder compared to local fluctuations. The internal structure of the ommatidia and the stiffness of their interior cells also plays a crucial role in the defect generation. Accurate predictions of the correlation between the area variation and the defect density in both normal and mutant animals are obtained without free parameters. This approach can potentially be applied to cellular systems in many other contexts to identify size-topology correlations near the onset of symmetry breaking. This work has been supported by the NIH (GM098077) and the NSF (Grant No. 1504301).

  19. Healthy aging – insights from Drosophila

    Directory of Open Access Journals (Sweden)

    Konstantin G Iliadi

    2012-04-01

    Full Text Available Human life expectancy has nearly doubled in the past century due, in part, to social and economic development, and a wide range of new medical technologies and treatments. As the number of elderly increase it becomes of vital importance to understand what factors contribute to healthy aging. Human longevity is a complex process that is affected by both environmental and genetic factors and interactions between them. Unfortunately, it is currently difficult to identify the role of genetic components in human longevity. In contrast, model organisms such as C. elegans, Drosophila and rodents have facilitated the search for specific genes that affect lifespan. Experimental evidence obtained from studies in model organisms suggests that mutations in a single gene may increase longevity and delay the onset of age-related symptoms including motor impairments, sexual and reproductive and immune dysfunction, cardiovascular disease and cognitive decline. Furthermore, the high degree of conservation between diverse species in the genes and pathways that regulate longevity suggests that work in model organisms can both expand our theoretical knowledge of aging and perhaps provide new therapeutic targets for the treatment of age-related disorders.

  20. Active forgetting of olfactory memories in Drosophila.

    Science.gov (United States)

    Berry, Jacob A; Davis, Ronald L

    2014-01-01

    Failure to remember, or forgetting, is a phenomenon familiar to everyone and despite more than a century of scientific inquiry, why we forget what we once knew remains unclear. If the brain marshals significant resources to form and store memories, why is it that these memories become lost? In the last century, psychological studies have divided forgetting into decay theory, in which memory simply dissipates with time, and interference theory, in which additional learning or mental activity hinders memory by reducing its stability or retrieval (for review, Dewar et al., 2007; Wixted, 2004). Importantly, these psychological models of forgetting posit that forgetting is a passive property of the brain and thus a failure of the brain to retain memories. However, recent neuroscience research on olfactory memory in Drosophila has offered evidence for an alternative conclusion that forgetting is an "active" process, with specific, biologically regulated mechanisms that remove existing memories (Berry et al., 2012; Shuai et al., 2010). Similar to the bidirectional regulation of cell number by mitosis and apoptosis, protein concentration by translation and lysosomal or proteomal degradation, and protein phosphate modification by kinases and phosphatases, biologically regulated memory formation and removal would be yet another example in biological systems where distinct and separate pathways regulate the creation and destruction of biological substrates. © 2014 Elsevier B.V. All rights reserved.

  1. Functional neuroanatomy of Drosophila olfactory memory formation.

    Science.gov (United States)

    Guven-Ozkan, Tugba; Davis, Ronald L

    2014-10-01

    New approaches, techniques and tools invented over the last decade and a half have revolutionized the functional dissection of neural circuitry underlying Drosophila learning. The new methodologies have been used aggressively by researchers attempting to answer three critical questions about olfactory memories formed with appetitive and aversive reinforcers: (1) Which neurons within the olfactory nervous system mediate the acquisition of memory? (2) What is the complete neural circuitry extending from the site(s) of acquisition to the site(s) controlling memory expression? (3) How is information processed across this circuit to consolidate early-forming, disruptable memories to stable, late memories? Much progress has been made and a few strong conclusions have emerged: (1) Acquisition occurs at multiple sites within the olfactory nervous system but is mediated predominantly by the γ mushroom body neurons. (2) The expression of long-term memory is completely dependent on the synaptic output of α/β mushroom body neurons. (3) Consolidation occurs, in part, through circuit interactions between mushroom body and dorsal paired medial neurons. Despite this progress, a complete and unified model that details the pathway from acquisition to memory expression remains elusive. © 2014 Guven-Ozkan and Davis; Published by Cold Spring Harbor Laboratory Press.

  2. Host plant adaptation in Drosophila mettleri populations.

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    Sergio Castrezana

    Full Text Available The process of local adaptation creates diversity among allopatric populations, and may eventually lead to speciation. Plant-feeding insect populations that specialize on different host species provide an excellent opportunity to evaluate the causes of ecological specialization and the subsequent consequences for diversity. In this study, we used geographically separated Drosophila mettleri populations that specialize on different host cacti to examine oviposition preference for and larval performance on an array of natural and non-natural hosts (eight total. We found evidence of local adaptation in performance on saguaro cactus (Carnegiea gigantea for populations that are typically associated with this host, and to chemically divergent prickly pear species (Opuntia spp. in a genetically isolated population on Santa Catalina Island. Moreover, each population exhibited reduced performance on the alternative host. This finding is consistent with trade-offs associated with adaptation to these chemically divergent hosts, although we also discuss alternative explanations for this pattern. For oviposition preference, Santa Catalina Island flies were more likely to oviposit on some prickly pear species, but all populations readily laid eggs on saguaro. Experiments with non-natural hosts suggest that factors such as ecological opportunity may play a more important role than host plant chemistry in explaining the lack of natural associations with some hosts.

  3. Exploring strategies for protein trapping in Drosophila

    Energy Technology Data Exchange (ETDEWEB)

    Quinones-Coello, Ana T.; Petrella, Lisa N.; Ayers, Kathleen; Melillo, Anthony; Mazzalupo, Stacy; Hudson, Andrew M.; Wang, Shu; Castiblanco, Claudia; Buszczak, Michael; Hoskins, Roger A.; Cooley, Lynn

    2006-12-18

    The use of fluorescent protein tags has had a huge impact oncell biological studies in virtually every experimental system.Incorporation of coding sequence for fluorescent proteins such as greenfluorescent protein (GFP) into genes at their endogenous chromosomalposition is especially useful for generating GFP-fusion proteins thatprovide accurate cellular and subcellular expression data. We testedmodifications of a transposon-based protein trap screening procedure inDrosophila to optimize the rate of recovering useful protein traps andtheir analysis. Transposons carrying the GFP-coding sequence flanked bysplice acceptor and donor sequences were mobilized, and new insertionsthat resulted in production of GFP were captured using an automatedembryo sorter. Individual stocks were established, GFP expression wasanalyzed during oogenesis, and insertion sites were determined bysequencing genomic DNA flanking the insertions. The resulting collectionincludes lines with protein traps in which GFP was spliced into mRNAs andembedded within endogenous proteins or enhancer traps in which GFPexpression depended on splicing into transposon-derived RNA. We report atotal of 335 genes associated with protein or enhancer traps and aweb-accessible database for viewing molecular information and expressiondata for these genes.

  4. The sexually antagonistic genes of Drosophila melanogaster.

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    Paolo Innocenti

    2010-03-01

    Full Text Available When selective pressures differ between males and females, the genes experiencing these conflicting evolutionary forces are said to be sexually antagonistic. Although the phenotypic effect of these genes has been documented in both wild and laboratory populations, their identity, number, and location remains unknown. Here, by combining data on sex-specific fitness and genome-wide transcript abundance in a quantitative genetic framework, we identified a group of candidate genes experiencing sexually antagonistic selection in the adult, which correspond to 8% of Drosophila melanogaster genes. As predicted, the X chromosome is enriched for these genes, but surprisingly they represent only a small proportion of the total number of sex-biased transcripts, indicating that the latter is a poor predictor of sexual antagonism. Furthermore, the majority of genes whose expression profiles showed a significant relationship with either male or female adult fitness are also sexually antagonistic. These results provide a first insight into the genetic basis of intralocus sexual conflict and indicate that genetic variation for fitness is dominated and maintained by sexual antagonism, potentially neutralizing any indirect genetic benefits of sexual selection.

  5. Structure of full-length Drosophila cryptochrome

    Energy Technology Data Exchange (ETDEWEB)

    Zoltowski, Brian D.; Vaidya, Anand T.; Top, Deniz; Widom, Joanne; Young, Michael W.; Crane, Brian R. (Cornell); (Rockefeller)

    2011-12-15

    The cryptochrome/photolyase (CRY/PL) family of photoreceptors mediates adaptive responses to ultraviolet and blue light exposure in all kingdoms of life. Whereas PLs function predominantly in DNA repair of cyclobutane pyrimidine dimers (CPDs) and 6-4 photolesions caused by ultraviolet radiation, CRYs transduce signals important for growth, development, magnetosensitivity and circadian clocks. Despite these diverse functions, PLs/CRYs preserve a common structural fold, a dependence on flavin adenine dinucleotide (FAD) and an internal photoactivation mechanism. However, members of the CRY/PL family differ in the substrates recognized (protein or DNA), photochemical reactions catalysed and involvement of an antenna cofactor. It is largely unknown how the animal CRYs that regulate circadian rhythms act on their substrates. CRYs contain a variable carboxy-terminal tail that appends the conserved PL homology domain (PHD) and is important for function. Here, we report a 2.3-{angstrom} resolution crystal structure of Drosophila CRY with an intact C terminus. The C-terminal helix docks in the analogous groove that binds DNA substrates in PLs. Conserved Trp536 juts into the CRY catalytic centre to mimic PL recognition of DNA photolesions. The FAD anionic semiquinone found in the crystals assumes a conformation to facilitate restructuring of the tail helix. These results help reconcile the diverse functions of the CRY/PL family by demonstrating how conserved protein architecture and photochemistry can be elaborated into a range of light-driven functions.

  6. How Food Controls Aggression in Drosophila

    Science.gov (United States)

    Lim, Rod S.; Eyjólfsdóttir, Eyrún; Shin, Euncheol; Perona, Pietro; Anderson, David J.

    2014-01-01

    How animals use sensory information to weigh the risks vs. benefits of behavioral decisions remains poorly understood. Inter-male aggression is triggered when animals perceive both the presence of an appetitive resource, such as food or females, and of competing conspecific males. How such signals are detected and integrated to control the decision to fight is not clear. For instance, it is unclear whether food increases aggression directly, or as a secondary consequence of increased social interactions caused by attraction to food. Here we use the vinegar fly, Drosophila melanogaster, to investigate the manner by which food influences aggression. We show that food promotes aggression in flies, and that it does so independently of any effect on frequency of contact between males, increase in locomotor activity or general enhancement of social interactions. Importantly, the level of aggression depends on the absolute amount of food, rather than on its surface area or concentration. When food resources exceed a certain level, aggression is diminished, suggestive of reduced competition. Finally, we show that detection of sugar via Gr5a+ gustatory receptor neurons (GRNs) is necessary for food-promoted aggression. These data demonstrate that food exerts a specific effect to promote aggression in male flies, and that this effect is mediated, at least in part, by sweet-sensing GRNs. PMID:25162609

  7. Ferritin Assembly in Enterocytes of Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Abraham Rosas-Arellano

    2016-02-01

    Full Text Available Ferritins are protein nanocages that accumulate inside their cavity thousands of oxidized iron atoms bound to oxygen and phosphates. Both characteristic types of eukaryotic ferritin subunits are present in secreted ferritins from insects, but here dimers between Ferritin 1 Heavy Chain Homolog (Fer1HCH and Ferritin 2 Light Chain Homolog (Fer2LCH are further stabilized by disulfide-bridge in the 24-subunit complex. We addressed ferritin assembly and iron loading in vivo using novel transgenic strains of Drosophila melanogaster. We concentrated on the intestine, where the ferritin induction process can be controlled experimentally by dietary iron manipulation. We showed that the expression pattern of Fer2LCH-Gal4 lines recapitulated iron-dependent endogenous expression of the ferritin subunits and used these lines to drive expression from UAS-mCherry-Fer2LCH transgenes. We found that the Gal4-mediated induction of mCherry-Fer2LCH subunits was too slow to effectively introduce them into newly formed ferritin complexes. Endogenous Fer2LCH and Fer1HCH assembled and stored excess dietary iron, instead. In contrast, when flies were genetically manipulated to co-express Fer2LCH and mCherry-Fer2LCH simultaneously, both subunits were incorporated with Fer1HCH in iron-loaded ferritin complexes. Our study provides fresh evidence that, in insects, ferritin assembly and iron loading in vivo are tightly regulated.

  8. A Model of Drosophila Larva Chemotaxis.

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    Alex Davies

    2015-11-01

    Full Text Available Detailed observations of larval Drosophila chemotaxis have characterised the relationship between the odour gradient and the runs, head casts and turns made by the animal. We use a computational model to test whether hypothesised sensorimotor control mechanisms are sufficient to account for larval behaviour. The model combines three mechanisms based on simple transformations of the recent history of odour intensity at the head location. The first is an increased probability of terminating runs in response to gradually decreasing concentration, the second an increased probability of terminating head casts in response to rapidly increasing concentration, and the third a biasing of run directions up concentration gradients through modulation of small head casts. We show that this model can be tuned to produce behavioural statistics comparable to those reported for the larva, and that this tuning results in similar chemotaxis performance to the larva. We demonstrate that each mechanism can enable odour approach but the combination of mechanisms is most effective, and investigate how these low-level control mechanisms relate to behavioural measures such as the preference indices used to investigate larval learning behaviour in group assays.

  9. Flavonoids and oxidative stress in Drosophila melanogaster.

    Science.gov (United States)

    Sotibrán, América Nitxin Castañeda; Ordaz-Téllez, María Guadalupe; Rodríguez-Arnaiz, Rosario

    2011-11-27

    Flavonoids are a family of antioxidants that are widely represented in fruits, vegetables, dry legumes, and chocolate, as well as in popular beverages, such as red wine, coffee, and tea. The flavonoids chlorogenic acid, kaempferol, quercetin and quercetin 3β-d-glycoside were investigated for genotoxicity using the wing somatic mutation and recombination test (SMART). This test makes use of two recessive wing cell markers: multiple wing hairs (mwh) and flare (flr(3)), which are mutations located on the left arm of chromosome 3 of Drosophila melanogaster and are indicative of both mitotic recombination and various types of mutational events. In order to test the antioxidant capacities of the flavonoids, experiments were conducted with various combinations of oxidants and polyphenols. Oxidative stress was induced using hydrogen peroxide, the Fenton reaction and paraquat. Third-instar transheterozygous larvae were chronically treated for all experiments. The data obtained in this study showed that, at the concentrations tested, the flavonoids did not induce somatic mutations or recombination in D. melanogaster with the exception of quercetin, which proved to be genotoxic at only one concentration. The oxidants hydrogen peroxide and the Fenton reaction did not induce mutations in the wing somatic assay of D. melanogaster, while paraquat and combinations of flavonoids produced significant numbers of small single spots. Quercetin 3β-d-glycoside mixed with paraquat was shown to be desmutagenic. Combinations of the oxidants with the other flavonoids did not show any antioxidant activity. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Place learning overrides innate behaviors in Drosophila.

    Science.gov (United States)

    Baggett, Vincent; Mishra, Aditi; Kehrer, Abigail L; Robinson, Abbey O; Shaw, Paul; Zars, Troy

    2018-03-01

    Animals in a natural environment confront many sensory cues. Some of these cues bias behavioral decisions independent of experience, and action selection can reveal a stimulus-response (S-R) connection. However, in a changing environment it would be a benefit for an animal to update behavioral action selection based on experience, and learning might modify even strong S-R relationships. How animals use learning to modify S-R relationships is a largely open question. Three sensory stimuli, air, light, and gravity sources were presented to individual Drosophila melanogaster in both naïve and place conditioning situations. Flies were tested for a potential modification of the S-R relationships of anemotaxis, phototaxis, and negative gravitaxis by a contingency that associated place with high temperature. With two stimuli, significant S-R relationships were abandoned when the cue was in conflict with the place learning contingency. The role of the dunce ( dnc ) cAMP-phosphodiesterase and the rutabaga ( rut ) adenylyl cyclase were examined in all conditions. Both dnc 1 and rut 2080 mutant flies failed to display significant S-R relationships with two attractive cues, and have characteristically lower conditioning scores under most conditions. Thus, learning can have profound effects on separate native S-R relationships in multiple contexts, and mutation of the dnc and rut genes reveal complex effects on behavior. © 2018 Baggett et al.; Published by Cold Spring Harbor Laboratory Press.

  11. Meiotic transmission of Drosophila pseudoobscura chromosomal arrangements.

    Directory of Open Access Journals (Sweden)

    Richard P Meisel

    Full Text Available Drosophila pseudoobscura harbors a rich gene arrangement polymorphism on the third chromosome generated by a series of overlapping paracentric inversions. The arrangements suppress recombination in heterokaryotypic individuals, which allows for the selective maintenance of coadapted gene complexes. Previous mapping experiments used to determine the degree to which recombination is suppressed in gene arrangement heterozygotes produced non-recombinant progeny in non-Mendelian ratios. The deviations from Mendelian expectations could be the result of viability differences between wild and mutant chromosomes, meiotic drive because of achiasmate pairing of homologues in heterokaryotypic females during meiosis, or a combination of both mechanisms. The possibility that the frequencies of the chromosomal arrangements in natural populations are affected by mechanisms other than adaptive selection led us to consider these hypotheses. We performed reciprocal crosses involving both heterozygous males and females to determine if the frequency of the non-recombinant progeny deviates significantly from Mendelian expectations and if the frequencies deviate between reciprocal crosses. We failed to observe non-Mendelian ratios in multiple crosses, and the frequency of the non-recombinant classes differed in only one of five pairs of reciprocal crosses despite sufficient power to detect these differences in all crosses. Our results indicate that deviations from Mendelian expectations in recombination experiments involving the D. pseudoobscura inversion system are most likely due to fitness differences of gene arrangement karyotypes in different environments.

  12. Tools for neuroanatomy and neurogenetics in Drosophila

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, Barret D.; Jenett, Arnim; Hammonds, Ann S.; Ngo, Teri-T B.; Misra, Sima; Murphy, Christine; Scully, Audra; Carlson, Joseph W.; Wan, Kenneth H.; Laverty, Todd R.; Mungall, Chris; Svirskas, Rob; Kadonaga, James T.; Doe, Chris Q.; Eisen, Michael B.; Celniker, Susan E.; Rubin, Gerald M.

    2008-08-11

    We demonstrate the feasibility of generating thousands of transgenic Drosophila melanogaster lines in which the expression of an exogenous gene is reproducibly directed to distinct small subsets of cells in the adult brain. We expect the expression patterns produced by the collection of 5,000 lines that we are currently generating to encompass all neurons in the brain in a variety of intersecting patterns. Overlapping 3-kb DNA fragments from the flanking noncoding and intronic regions of genes thought to have patterned expression in the adult brain were inserted into a defined genomic location by site-specific recombination. These fragments were then assayed for their ability to function as transcriptional enhancers in conjunction with a synthetic core promoter designed to work with a wide variety of enhancer types. An analysis of 44 fragments from four genes found that >80% drive expression patterns in the brain; the observed patterns were, on average, comprised of <100 cells. Our results suggest that the D. melanogaster genome contains >50,000 enhancers and that multiple enhancers drive distinct subsets of expression of a gene in each tissue and developmental stage. We expect that these lines will be valuable tools for neuroanatomy as well as for the elucidation of neuronal circuits and information flow in the fly brain.

  13. In-vivo Centrifugation of Drosophila Embryos

    Science.gov (United States)

    Tran, Susan L.; Welte, Michael A.

    2010-01-01

    A major strategy for purifying and isolating different types of intracellular organelles is to separate them from each other based on differences in buoyant density. However, when cells are disrupted prior to centrifugation, proteins and organelles in this non-native environment often inappropriately stick to each other. Here we describe a method to separate organelles by density in intact, living Drosophila embryos. Early embryos before cellularization are harvested from population cages, and their outer egg shells are removed by treatment with 50% bleach. Embryos are then transferred to a small agar plate and inserted, posterior end first, into small vertical holes in the agar. The plates containing embedded embryos are centrifuged for 30 min at 3000g. The agar supports the embryos and keeps them in a defined orientation. Afterwards, the embryos are dug out of the agar with a blunt needle. Centrifugation separates major organelles into distinct layers, a stratification easily visible by bright-field microscopy. A number of fluorescent markers are available to confirm successful stratification in living embryos. Proteins associated with certain organelles will be enriched in a particular layer, demonstrating colocalization. Individual layers can be recovered for biochemical analysis or transplantation into donor eggs. This technique is applicable for organelle separation in other large cells, including the eggs and oocytes of diverse species. PMID:20613707

  14. Insulin signaling mediates sexual attractiveness in Drosophila.

    Directory of Open Access Journals (Sweden)

    Tsung-Han Kuo

    Full Text Available Sexually attractive characteristics are often thought to reflect an individual's condition or reproductive potential, but the underlying molecular mechanisms through which they do so are generally unknown. Insulin/insulin-like growth factor signaling (IIS is known to modulate aging, reproduction, and stress resistance in several species and to contribute to variability of these traits in natural populations. Here we show that IIS determines sexual attractiveness in Drosophila through transcriptional regulation of genes involved in the production of cuticular hydrocarbons (CHC, many of which function as pheromones. Using traditional gas chromatography/mass spectrometry (GC/MS together with newly introduced laser desorption/ionization orthogonal time-of-flight mass spectrometry (LDI-MS we establish that CHC profiles are significantly affected by genetic manipulations that target IIS. Manipulations that reduce IIS also reduce attractiveness, while females with increased IIS are significantly more attractive than wild-type animals. IIS effects on attractiveness are mediated by changes in CHC profiles. Insulin signaling influences CHC through pathways that are likely independent of dFOXO and that may involve the nutrient-sensing Target of Rapamycin (TOR pathway. These results suggest that the activity of conserved molecular regulators of longevity and reproductive output may manifest in different species as external characteristics that are perceived as honest indicators of fitness potential.

  15. Effects of Spaceflight on Drosophila Neural Development

    Science.gov (United States)

    Keshishian, Haig S.

    1997-01-01

    The major goal from the animal side, however, has been achieved, namely to develop Drosophila lines where we can assay individual neuromuscular endings directly without dissection. This was achieved by means of using the GAL4-UAS system, where we have succeeded in establishing stocks of flies where the key neuromuscular connections can be assayed directly in undissected larvae by means of the expression of endogenously fluorescent reporters in the specific motor endings. The green fluorescent protein (GFP) as a reporter allows scoring of neural anatomy en-masse in whole mount using fluorescent microscopy without the need for either dissection or specific labeling. Two stocks have been developed. The first, which we developed first, uses the S65T mutant form, which has a dramatically brighter expression than the native protein. This animal will use GAL4 drivers with expression under the control of the elav gene, and which will ensure expression in all neurons of the embryo and larva. The second transgenic animal we have developed is of a novel kind, and makes use of dicistronic design, so that two copies of the protein will be expressed per insert. We have also developed a tricistronic form, but this has not yet been transformed into flies, and we do not imagine that this third line will be ready in time for the flight.

  16. Quantifying Abdominal Pigmentation in Drosophila melanogaster.

    Science.gov (United States)

    Saleh Ziabari, Omid; Shingleton, Alexander W

    2017-06-01

    Pigmentation is a morphologically simple but highly variable trait that often has adaptive significance. It has served extensively as a model for understanding the development and evolution of morphological phenotypes. Abdominal pigmentation in Drosophila melanogaster has been particularly useful, allowing researchers to identify the loci that underlie inter- and intraspecific variations in morphology. Hitherto, however, D. melanogaster abdominal pigmentation has been largely assayed qualitatively, through scoring, rather than quantitatively, which limits the forms of statistical analysis that can be applied to pigmentation data. This work describes a new methodology that allows for the quantification of various aspects of the abdominal pigmentation pattern of adult D. melanogaster. The protocol includes specimen mounting, image capture, data extraction, and analysis. All the software used for image capture and analysis feature macros written for open-source image analysis. The advantage of this approach is the ability to precisely measure pigmentation traits using a methodology that is highly reproducible across different imaging systems. While the technique has been used to measure variation in the tergal pigmentation patterns of adult D. melanogaster, the methodology is flexible and broadly applicable to pigmentation patterns in myriad different organisms.

  17. Tailored MoS2 nanorods: a simple microwave assisted synthesis

    Science.gov (United States)

    Reshmi, S.; Akshaya, M. V.; Satpati, Biswarup; Roy, Anupam; Basu, Palash Kumar; Bhattacharjee, K.

    2017-11-01

    We report here the synthesis of MoS2 nanostructures by a simple liquid phase exfoliation of MoS2 powder in organic solvents followed by microwave treatment. The probe sonication and the microwave treatment play an important role in rolling and curling of the MoS2 nanosheets to give rise to MoS2 spheres and rod/tube like-structures with diameter approximately 150-200 nm. The MoS2 nanorods formed in this fashion are hollow inside with a wall thickness of 15-20 nm and the length of the nanorods is found in the order of several micrometers. Synthesis of such tailored MoS2 nanorods by liquid phase exfoliation is not yet reported. Our observations suggest the 2H phase of bulk MoS2 remains preserved in the nanostructures with high crystalline quality.

  18. Drosophila as a genetically tractable model for social insect behaviour

    Directory of Open Access Journals (Sweden)

    Alison L Camiletti

    2016-04-01

    Full Text Available The relatively simple communication, breeding and egg-making systems that govern reproduction in female Drosophila retain homology to eusocial species in which these same systems are modified to the social condition. Despite having no parental care, division of labour or subfertile caste, Drosophila may nonetheless offer a living test of certain sociobiological hypotheses framed around gene function. In this review, we make this case, and do so around the recent discovery that the non-social fly, Drosophila melanogaster, can respond to the ovary-suppressing queen pheromone of the honey bee Apis meliffera. Here, we first explain the sociobiological imperative to reconcile kin theory with molecular biology, and qualify a potential role for Drosophila. Then, we offer three applications for the fly-pheromone assay. First, the availability and accessibility of massive mutant libraries makes immediately feasible any number of open or targeted gene screens against the ovary-inhibiting response. The sheer tractability of Drosophila may therefore help to accelerate the search for genes in pheromone-responsive pathways that regulate female reproduction, including potentially any that are preserved with modification to regulate worker sterility in response to queen pheromones in eusocial taxa. Secondly, Drosophila’s powerful Gal4/UAS expression system can complement the pheromone assay by driving target gene expression into living tissue, which could be well applied to the functional testing of genes presumed to drive ovary activation or de-activation in the honey bee or other eusocial taxa. Finally, coupling Gal4 with UAS-RNAi lines can facilitate loss-of-function experiments against perception and response to the ovary inhibiting pheromone, and do so for large numbers of candidates in systematic fashion. Drosophila's utility as an adjunct to the field of insect sociobiology is not ideal, but retains surprising potential.

  19. Unconventional Superconductivity in the BiS_{2}-Based Layered Superconductor NdO_{0.71}F_{0.29}BiS_{2}.

    Science.gov (United States)

    Ota, Yuichi; Okazaki, Kozo; Yamamoto, Haruyoshi Q; Yamamoto, Takashi; Watanabe, Shuntaro; Chen, Chuangtian; Nagao, Masanori; Watauchi, Satoshi; Tanaka, Isao; Takano, Yoshihiko; Shin, Shik

    2017-04-21

    We investigate the superconducting-gap anisotropy in one of the recently discovered BiS_{2}-based superconductors, NdO_{0.71}F_{0.29}BiS_{2} (T_{c}∼5  K), using laser-based angle-resolved photoemission spectroscopy. Whereas the previously discovered high-T_{c} superconductors such as copper oxides and iron-based superconductors, which are believed to have unconventional superconducting mechanisms, have 3d electrons in their conduction bands, the conduction band of BiS_{2}-based superconductors mainly consists of Bi 6p electrons, and, hence, the conventional superconducting mechanism might be expected. Contrary to this expectation, we observe a strongly anisotropic superconducting gap. This result strongly suggests that the pairing mechanism for NdO_{0.71}F_{0.29}BiS_{2} is an unconventional one and we attribute the observed anisotropy to competitive or cooperative multiple paring interactions.

  20. Intraspecific hybridization, developmental stability and fitness in Drosophila mercatorum

    DEFF Research Database (Denmark)

    Andersen, DH; Pertoldi, C; Scali, V

    2002-01-01

    (hybrid vigour) may be a result of hybridization, probably due to increased heterozygosity. Developmental stability is assumed to be correlated with fitness and is commonly measured as fluctuating asymmetry or phenotypic variance. Drosophila mercatorum is capable of reproducing sexually, but also....... Intraspecific hybridization between a parthenogenetic and a sexually reproducing strain of Drosophila mercatorum resulted in significant changes in fecundity as well as fluctuating asymmetry and phenotypic variance for the number of sternopleural bristles and in the length of two wing traits over three...

  1. Getting started : an overview on raising and handling Drosophila.

    Science.gov (United States)

    Stocker, Hugo; Gallant, Peter

    2008-01-01

    Drosophila melanogaster has long been a prime model organism for developmental biologists. During their work, they have established a large collection of techniques and reagents. This in turn has made fruit flies an attractive system for many other biomedical researchers who have otherwise no background in fly biology. This review intends to help Drosophila neophytes in setting up a fly lab. It briefly introduces the biological properties of fruit flies, describes the minimal equipment required for working with flies, and offers some basic advice for maintaining fly lines and setting up and analyzing experiments.

  2. Using the Drosophila Nephrocyte to Model Podocyte Function and Disease

    Directory of Open Access Journals (Sweden)

    Martin Helmstädter

    2017-12-01

    Full Text Available Glomerular disorders are a major cause of end-stage renal disease and effective therapies are often lacking. Nephrocytes are considered to be part of the Drosophila excretory system and form slit diaphragms across cellular membrane invaginations. Nehphrocytes have been shown to share functional, morphological, and molecular features with podocytes, which form the glomerular filter in vertebrates. Here, we report the progress and the evolving tool-set of this model system. Combining a functional, accessible slit diaphragm with the power of the genetic tool-kit in Drosophila, the nephrocyte has the potential to greatly advance our understanding of the glomerular filtration barrier in health and disease.

  3. Mutagenic effects of irradiated glucose in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Varma, M.B.; Rao, K.P.; Nandan, S.D.; Rao, M.S.

    1982-01-01

    The mutagenic effects of irradiated glucose were studied using the sex-linked recessive lethal test in Drosophila melanogaster. Oregon K males of D. melanogaster reared on a medium containing 20 or 40% glucose irradiated with a dose of 0.02, 0.10, 0.20, 2 or 5 Mrad #betta#-rays were scored for the induction of sex-linked recessive lethals. The results showed no significant increase in the frequency of X-lethals in Drosophila at any of the dose levels. (author)

  4. Polytene chromosome map and inversion polymorphism in Drosophila mediopunctata

    Directory of Open Access Journals (Sweden)

    Galina Ananina

    2002-07-01

    Full Text Available Drosophila mediopunctata belongs to the tripunctata group, and is one of the commonest Drosophila species collected in some places in Brazil, especially in the winter. A standard map of the polytene chromosomes is presented. The breakpoints of the naturally occurring chromosomal rearrangements are marked on the map. The distribution of breaking points through the chromosomes of D. mediopunctata is apparently non-random. Chromosomes X, II and IV show inversion polymorphisms. Chromosome II is the most polymorphic, with 17 inversions, 8 inversions in the distal region and 9 in the proximal region. Chromosome X has four different gene arrangements, while chromosome IV has only two.

  5. Genetic analysis of a Drosophila microtubule-associated protein

    OpenAIRE

    1992-01-01

    The 205-kD microtubule-associated protein (205K MAP) is one of the principal MAPs in Drosophila. 205K MAP is similar to the HeLa 210K/MAP4 family of MAPs since it shares the following biochemical properties: it is present in several isoforms, has a molecular mass of approximately 200 kD, and is thermostable. Furthermore, immuno-crossreactivity has been observed between mouse MAP4, HeLa 210K, and Drosophila 205K MAP. Currently, there is little information concerning the biological function of ...

  6. Egg size, embryonic development time and ovoviviparity in Drosophila species.

    Science.gov (United States)

    Markow, T A; Beall, S; Matzkin, L M

    2009-02-01

    Lengths, widths and volumes of eggs from 11 species of Drosophila whose genomes have been fully sequenced exhibit significant variation that is not explained by their phylogenetic relationships. Furthermore, egg size differences are unrelated to embryonic development time in these species. In addition, two of the species, Drosophila sechellia and, to a lesser degree, D. yakuba, both ecological specialists, exhibit ovoviviparity, suggesting that female control over oviposition in these species differs from what is observed in D. melanogaster. The interspecific differences in these reproductive characters, coupled with the availability of whole genome sequences for each, provide an unprecedented opportunity to examine their evolution.

  7. Neutron diffraction study on formation and structure of Dsub(x)TaS2 and Hsub(x)NbS2

    International Nuclear Information System (INIS)

    Riekel, C.; Reznik, H.G.; Schoellhorn, R.; Wright, C.J.

    1978-09-01

    Cathodic reduction of 2H-TaS 2 in D 2 SO 4 was investigated by transient neutron powder diffractometry. Deuterium was found to enter the lattice in a regular way. The structural model proposed implies a strong Ta-D bond. Single crystal neutron diffraction data on Hsub(0.76)NbS 2 confirm the position of hydrogen in a three center metal bond inside the dichalcogenide layers. Structural data are in accordance with inelastic neutron scattering data. (author)

  8. Magnetism by interfacial hybridization and p-type doping of MoS(2) in Fe(4)N/MoS(2) superlattices: a first-principles study.

    Science.gov (United States)

    Feng, Nan; Mi, Wenbo; Cheng, Yingchun; Guo, Zaibing; Schwingenschlögl, Udo; Bai, Haili

    2014-03-26

    Magnetic and electronic properties of Fe4N(111)/MoS2(√3 × √3) superlattices are investigated by first-principles calculations, considering two models: (I) Fe(I)Fe(II)-S and (II) N-S interfaces, each with six stacking configurations. In model I, strong interfacial hybridization between Fe(I)/Fe(II) and S results in magnetism of monolayer MoS2, with a magnetic moment of 0.33 μB for Mo located on top of Fe(I). For model II, no magnetism is induced due to weak N-S interfacial bonding, and the semiconducting nature of monolayer MoS2 is preserved. Charge transfer between MoS2 and N results in p-type MoS2 with Schottky barrier heights of 0.5-0.6 eV. Our results demonstrate that the interfacial geometry and hybridization can be used to tune the magnetism and doping in Fe4N(111)/MoS2(√3 × √3) superlattices.

  9. Magnetism by interfacial hybridization and p-type doping of MoS2 in Fe4N/MoS2 superlattices: A first-principles study

    KAUST Repository

    Feng, Nan

    2014-03-26

    Magnetic and electronic properties of Fe4N(111)/MoS 2(√3 × √3) superlattices are investigated by first-principles calculations, considering two models: (I) FeIFe II-S and (II) N-S interfaces, each with six stacking configurations. In model I, strong interfacial hybridization between FeI/Fe II and S results in magnetism of monolayer MoS2, with a magnetic moment of 0.33 μB for Mo located on top of Fe I. For model II, no magnetism is induced due to weak N-S interfacial bonding, and the semiconducting nature of monolayer MoS2 is preserved. Charge transfer between MoS2 and N results in p-type MoS2 with Schottky barrier heights of 0.5-0.6 eV. Our results demonstrate that the interfacial geometry and hybridization can be used to tune the magnetism and doping in Fe4N(111)/MoS2(√3 × √3) superlattices. © 2014 American Chemical Society.

  10. Confocal absorption spectral imaging of MoS2: optical transitions depending on the atomic thickness of intrinsic and chemically doped MoS2.

    Science.gov (United States)

    Dhakal, Krishna P; Duong, Dinh Loc; Lee, Jubok; Nam, Honggi; Kim, Minsu; Kan, Min; Lee, Young Hee; Kim, Jeongyong

    2014-11-07

    We performed a nanoscale confocal absorption spectral imaging to obtain the full absorption spectra (over the range 1.5-3.2 eV) within regions having different numbers of layers and studied the variation of optical transition depending on the atomic thickness of the MoS2 film. Three distinct absorption bands corresponding to A and B excitons and a high-energy background (BG) peak at 2.84 eV displayed a gradual redshift as the MoS2 film thickness increased from the monolayer, to the bilayer, to the bulk MoS2 and this shift was attributed to the reduction of the gap energy in the Brillouin zone at the K-point as the atomic thickness increased. We also performed n-type chemical doping of MoS2 films using reduced benzyl viologen (BV) and the confocal absorption spectra modified by the doping showed a strong dependence on the atomic thickness: A and B exciton peaks were greatly quenched in the monolayer MoS2 while much less effect was shown in larger thickness and the BG peak either showed very small quenching for 1 L MoS2 or remained constant for larger thicknesses. Our results indicate that confocal absorption spectral imaging can provide comprehensive information on optical transitions of microscopic size intrinsic and doped two-dimensional layered materials.

  11. Transcriptional activity and nuclear localization of Cabut, the Drosophila ortholog of vertebrate TGF-β-inducible early-response gene (TIEG proteins.

    Directory of Open Access Journals (Sweden)

    Yaiza Belacortu

    Full Text Available BACKGROUND: Cabut (Cbt is a C(2H(2-class zinc finger transcription factor involved in embryonic dorsal closure, epithelial regeneration and other developmental processes in Drosophila melanogaster. Cbt orthologs have been identified in other Drosophila species and insects as well as in vertebrates. Indeed, Cbt is the Drosophila ortholog of the group of vertebrate proteins encoded by the TGF-ß-inducible early-response genes (TIEGs, which belong to Sp1-like/Krüppel-like family of transcription factors. Several functional domains involved in transcriptional control and subcellular localization have been identified in the vertebrate TIEGs. However, little is known of whether these domains and functions are also conserved in the Cbt protein. METHODOLOGY/PRINCIPAL FINDINGS: To determine the transcriptional regulatory activity of the Drosophila Cbt protein, we performed Gal4-based luciferase assays in S2 cells and showed that Cbt is a transcriptional repressor and able to regulate its own expression. Truncated forms of Cbt were then generated to identify its functional domains. This analysis revealed a sequence similar to the mSin3A-interacting repressor domain found in vertebrate TIEGs, although located in a different part of the Cbt protein. Using β-Galactosidase and eGFP fusion proteins, we also showed that Cbt contains the bipartite nuclear localization signal (NLS previously identified in TIEG proteins, although it is non-functional in insect cells. Instead, a monopartite NLS, located at the amino terminus of the protein and conserved across insects, is functional in Drosophila S2 and Spodoptera exigua Sec301 cells. Last but not least, genetic interaction and immunohistochemical assays suggested that Cbt nuclear import is mediated by Importin-α2. CONCLUSIONS/SIGNIFICANCE: Our results constitute the first characterization of the molecular mechanisms of Cbt-mediated transcriptional control as well as of Cbt nuclear import, and demonstrate the

  12. Phosphorylation at serines 216 and 221 is important for Drosophila HeT-A Gag protein stability.

    Directory of Open Access Journals (Sweden)

    Sukhdev S Brar

    Full Text Available Telomeres from Drosophila appear to be very different from those of other organisms - in size and the mechanism of their maintenance. In the absence of the enzyme telomerase, Drosophila telomeres are maintained by retrotransposition of three elements, HeT-A, TART, and TAHRE, but details of their transposition mechanisms are not known. Here we characterized some biochemical characteristics of the HeT-A Gag protein encoded by the HeT-A element to understand this mechanism. The HeT-A Gag protein when overexpressed in S2 cells was localized to the nucleus but was resistant to high salt, detergents and nuclease extraction treatments. Analysis of the HeT-A Gag protein by tandem mass spectrophotometry revealed that serines 216 and 221 are phosphorylated. Substituting these serines with alanine or aspartic acid by site-directed mutagenesis did not result in any changes in HeT-A Gag translocation across the nucleus, suggesting that phosphorylation of these sites is not associated with HeT-A Gag translocation, but time course experiments showed that these phosphorylation sites are important for Gag-protein stability.

  13. MoS2 nanoparticles grown on graphene: an advanced catalyst for the hydrogen evolution reaction.

    Science.gov (United States)

    Li, Yanguang; Wang, Hailiang; Xie, Liming; Liang, Yongye; Hong, Guosong; Dai, Hongjie

    2011-05-18

    Advanced materials for electrocatalytic and photoelectrochemical water splitting are central to the area of renewable energy. In this work, we developed a selective solvothermal synthesis of MoS(2) nanoparticles on reduced graphene oxide (RGO) sheets suspended in solution. The resulting MoS(2)/RGO hybrid material possessed nanoscopic few-layer MoS(2) structures with an abundance of exposed edges stacked onto graphene, in strong contrast to large aggregated MoS(2) particles grown freely in solution without GO. The MoS(2)/RGO hybrid exhibited superior electrocatalytic activity in the hydrogen evolution reaction (HER) relative to other MoS(2) catalysts. A Tafel slope of ∼41 mV/decade was measured for MoS(2) catalysts in the HER for the first time; this exceeds by far the activity of previous MoS(2) catalysts and results from the abundance of catalytic edge sites on the MoS(2) nanoparticles and the excellent electrical coupling to the underlying graphene network. The ∼41 mV/decade Tafel slope suggested the Volmer-Heyrovsky mechanism for the MoS(2)-catalyzed HER, with electrochemical desorption of hydrogen as the rate-limiting step. © 2011 American Chemical Society

  14. Prognostic significance of cytosolic pS2 content in ovarian tumors

    International Nuclear Information System (INIS)

    Raigoso, P.; Allende, T.; Zeidan, N.; Llana, B.; Bernardo, L.; Roiz, C.; Tejuca, S.; Vazquez, J.; Lamelas, M.L.

    2002-01-01

    Aim: pS2 is an estrogen regulated peptide which has been associated with a good prognosis an with a more favorable response to treatment in breast cancer patients. In ovarian tumors, the expression of pS2 was demonstrated at both mRNA and protein levels. In addition, it has been showed significant association of pS2 with mucinous differentiation or well differentiation grade of the tumors. However, it is little know about the prognostic significance of the pS2 content in ovarian carcinomas. The aims of the present work were to analyze the cytosolic pS2 content in benign and malignant ovarian tumors, its relationship with clinico-pathologic parameters, steroid receptor status, and prognostic significance. Material and Methods: We analysed the cytosolic concentrations of pS2 in 91 specimen ovarian tissues by an immunoradiometric assay (ELSA-pS2, CIS, France). The tissues were 8 normal ovaries, 43 benign tumors and 40 malignant ovarian tumors. The same ovarian tissues processed to pS2 were analyzed to Estrogen (ER) and Progesterone (PgR) Receptor status. These steroid receptors were quantified biochemically following commercial ELISA method (ABBOTT Diagnostics, Germany). The relationship between cytosolic content and clinico-pathologic factors was examined by the Mann-Whitney or Kruskall-Wallis test. Correlation between steroid receptors and pS2 content was calculated with the Spearman test. Survival curves were calculated using the Kaplan-Meier method and compared by the log-rank test. Differences were considered significant at 5% probability level. Results: pS2 could be detected in 30 cases (32.9%) with values ranged from 0.04 to 89 ng/mg prt. Only one normal ovary showed detectable levels of pS2 and there were not differences in cytosolic content between benign and malignant ovarian tumors. The pS2 levels were only associated to mucinous differentiation in both benign and malignant ovarian tumors (p=0.029 and p=0.015, respectively). Significantly higher

  15. Spin transport properties of partially edge-hydrogenated MoS2 nanoribbon heterostructure

    International Nuclear Information System (INIS)

    Peng, Li; Yao, Kailun; Zhu, Sicong; Ni, Yun; Zu, Fengxia; Wang, Shuling; Guo, Bin; Tian, Yong

    2014-01-01

    We report ab initio calculations of electronic transport properties of heterostructure based on MoS 2 nanoribbons. The heterostructure consists of edge hydrogen-passivated and non-passivated zigzag MoS 2 nanoribbons (ZMoS 2 NR-H/ZMoS 2 NR). Our calculations show that the heterostructure has half-metallic behavior which is independent of the nanoribbon width. The opening of spin channels of the heterostructure depends on the matching of particular electronic orbitals in the Mo-dominated edges of ZMoS 2 NR-H and ZMoS 2 NR. Perfect spin filter effect appears at small bias voltages, and large negative differential resistance and rectifying effects are also observed in the heterostructure.

  16. Enhanced monolayer MoS2/InP heterostructure solar cells by graphene quantum dots

    Science.gov (United States)

    Wang, Peng; Lin, Shisheng; Ding, Guqiao; Li, Xiaoqiang; Wu, Zhiqian; Zhang, Shengjiao; Xu, Zhijuan; Xu, Sen; Lu, Yanghua; Xu, Wenli; Zheng, Zheyang

    2016-04-01

    We demonstrate significantly improved photovoltaic response of monolayer molybdenum disulfide (MoS2)/indium phosphide (InP) van der Waals heterostructure induced by graphene quantum dots (GQDs). Raman and photoluminescence measurements indicate that effective charge transfer takes place between GQDs and MoS2, which results in n-type doping of MoS2. The doping effect increases the barrier height at the MoS2/InP heterojunction, thus the averaged power conversion efficiency of MoS2/InP solar cells is improved from 2.1% to 4.1%. The light induced doping by GQD provides a feasible way for developing more efficient MoS2 based heterostructure solar cells.

  17. Modeling peripheral olfactory coding in Drosophila larvae.

    Directory of Open Access Journals (Sweden)

    Derek J Hoare

    Full Text Available The Drosophila larva possesses just 21 unique and identifiable pairs of olfactory sensory neurons (OSNs, enabling investigation of the contribution of individual OSN classes to the peripheral olfactory code. We combined electrophysiological and computational modeling to explore the nature of the peripheral olfactory code in situ. We recorded firing responses of 19/21 OSNs to a panel of 19 odors. This was achieved by creating larvae expressing just one functioning class of odorant receptor, and hence OSN. Odor response profiles of each OSN class were highly specific and unique. However many OSN-odor pairs yielded variable responses, some of which were statistically indistinguishable from background activity. We used these electrophysiological data, incorporating both responses and spontaneous firing activity, to develop a bayesian decoding model of olfactory processing. The model was able to accurately predict odor identity from raw OSN responses; prediction accuracy ranged from 12%-77% (mean for all odors 45.2% but was always significantly above chance (5.6%. However, there was no correlation between prediction accuracy for a given odor and the strength of responses of wild-type larvae to the same odor in a behavioral assay. We also used the model to predict the ability of the code to discriminate between pairs of odors. Some of these predictions were supported in a behavioral discrimination (masking assay but others were not. We conclude that our model of the peripheral code represents basic features of odor detection and discrimination, yielding insights into the information available to higher processing structures in the brain.

  18. moleculares de insectos (Drosophila y de primates

    Directory of Open Access Journals (Sweden)

    Enio Hernández Aguirre

    2006-01-01

    Full Text Available La mayoría de las especies poseen un macho heterogamético XY y una hembra homogamética XX. En el macho XY sólo se conservan unas regiones donde se intercambian información entre el X y el Y (Xpter y Ypter durante la meiosis, que se le llama región seudoautosómica (RSA. Se ha planteado la hipótesis que el cromosoma Y se deriva del cromosoma X, y que antiguamente eran homólogos en toda su extensión. Un posible mecanismo biológico implicado en este proceso evolutivo son fragmentos de ADN que pueden moverse a través del genoma. En general se llaman elementos genéticos móviles. Con base en los elementos génicos móviles y en los genes de la cutícula larval (Lcp se han realizado estudios en los cromosomas sexuales de Drosophila melanogaster, D. Permisilis, D. Seudooscura y D. Miranda. Los análisis moleculares realizados en D. Miranda son una clara evidencia científica de cómo un evento de translocacion cromosómica asociados a procesos biológicos naturales y normales del ADN, como lo es la transposición, pudieron generar un cromosoma “Y” a través de la evolución, que en su forma prístina fue homólogo del cromosoma X.

  19. TaS2 nanosheet-based room-temperature dosage meter for nitric oxide

    Directory of Open Access Journals (Sweden)

    Qiyuan He

    2014-09-01

    Full Text Available A miniature dosage meter for toxic gas is developed based on TaS2 nanosheets, which is capable of indicating the toxic dosage of trace level NO at room temperature. The TaS2 film-based chemiresistor shows an irreversible current response against the exposure of NO. The unique non-recovery characteristic makes the TaS2 film-based device an ideal indicator of total dosage of chronicle exposure.

  20. Synthesis of MoS 2 Inorganic Fullerene-like Nanoparticles by a ...

    African Journals Online (AJOL)

    The peaks at 155 cm–1, 349.8 cm–1 and 281.7 cm–1 in the Raman spectrum of bulk and layered MoS2 are absent, which is attributed to MoS2 layer folding or curling along Ã-M in Brillouin zone to formfullerene-like polyhedra and nanotubes. In addition, a gradual formation mechanism of IF-MoS2 nanoparticles was ...

  1. Study on the performance of MoS2 modified PTFE composites by molding process

    Science.gov (United States)

    Ma, Weiqiang; Hou, Genliang; Bi, Song; Li, Ping; Li, Penghui

    2017-10-01

    MoS2 filled PTFE composites were prepared by cold pressing and sintering molding. The compressive and creep properties of composite materials were analyzed by controlling the size of molded composites during molding. The results show that the composites have the best compressive and creep resistance when the molding pressure is 55 MPa in the MoS2 composites with 15% mass fraction, which is a practical reference for the preparation of MoS2-modified PTFE composites.

  2. Synthesis and characterization of vertically standing MoS2 nanosheets

    OpenAIRE

    Li, Han; Wu, Huaqiang; Yuan, Shuoguo; Qian, He

    2016-01-01

    Molybdenum disulfide (MoS2) has been attracting much attentions due to its excellent electrical and optical properties. We report here the synthesis of large-scale and uniform MoS2 nanosheets with vertically standing morphology using chemical vapor deposition method. TEM observations clearly reveal the growth mechanism of these vertical structures. It is suggested that the vertical structures are caused by the compression and extrusion between MoS2 islands. More importantly, the vertical morp...

  3. Micro-organism for the production of stereo-specific s, s-2,3-butanediol

    DEFF Research Database (Denmark)

    2016-01-01

    The invention relates to a genetically modified lactic acid bacterium capable of producing (S,S)-2,3-butanediol stereo specifically from glucose under aerobic conditions. Additionally the invention relates to a method for producing (S,S)-2,3-butanediol and L-acetoin using the genetically modified......; and additionally a number of genes are deleted in order to maximise the production of (S,S)-2,3-butanediol as compared to other products of oxidative fermentation....

  4. Cloning, purification, and functional characterization of Carocin S2, a ribonuclease bacteriocin produced by Pectobacterium carotovorum.

    Science.gov (United States)

    Chan, Yung-Chieh; Wu, Jian-Li; Wu, Huang-Pin; Tzeng, Kuo-Ching; Chuang, Duen-Yau

    2011-05-12

    Most isolates of Pectobacterium carotovorum subsp. carotovorum (Pcc) produce bacteriocins. In this study, we have determined that Pcc strain F-rif-18 has a chromosomal gene encoding the low-molecular-weight bacteriocin, Carocin S2, and that this bacteriocin inhibits the growth of a closely related strain. Carocin S2 is inducible by ultraviolet radiation but not by mutagenic agents such as mitomycin C. A carocin S2-defective mutant, TF1-2, was obtained by Tn5 insertional mutagenesis using F-rif-18. A 5706-bp DNA fragment was detected by Southern blotting, selected from a genomic DNA library, and cloned to the vector, pMS2KI. Two adjacent complete open reading frames within pMS2KI were sequenced, characterized, and identified as caroS2K and caroS2I, which respectively encode the killing protein and immunity protein. Notably, carocin S2 could be expressed not only in the mutant TF1-2 but also in Escherichia coli DH5α after entry of the plasmid pMS2KI. Furthermore, the C-terminal domain of CaroS2K was homologous to the nuclease domains of colicin D and klebicin D. Moreover, SDS-PAGE analysis showed that the relative mass of CaroS2K was 85 kDa and that of CaroS2I was 10 kDa. This study shown that another nuclease type of bacteriocin was found in Pectobacterium carotovorum. This new type of bacteriocin, Carocin S2, has the ribonuclease activity of CaroS2K and the immunity protein activity of CaroS2I.

  5. Cloning, purification, and functional characterization of Carocin S2, a ribonuclease bacteriocin produced by Pectobacterium carotovorum

    Directory of Open Access Journals (Sweden)

    Tzeng Kuo-Ching

    2011-05-01

    Full Text Available Abstract Background Most isolates of Pectobacterium carotovorum subsp. carotovorum (Pcc produce bacteriocins. In this study, we have determined that Pcc strain F-rif-18 has a chromosomal gene encoding the low-molecular-weight bacteriocin, Carocin S2, and that this bacteriocin inhibits the growth of a closely related strain. Carocin S2 is inducible by ultraviolet radiation but not by mutagenic agents such as mitomycin C. Results A carocin S2-defective mutant, TF1-2, was obtained by Tn5 insertional mutagenesis using F-rif-18. A 5706-bp DNA fragment was detected by Southern blotting, selected from a genomic DNA library, and cloned to the vector, pMS2KI. Two adjacent complete open reading frames within pMS2KI were sequenced, characterized, and identified as caroS2K and caroS2I, which respectively encode the killing protein and immunity protein. Notably, carocin S2 could be expressed not only in the mutant TF1-2 but also in Escherichia coli DH5α after entry of the plasmid pMS2KI. Furthermore, the C-terminal domain of CaroS2K was homologous to the nuclease domains of colicin D and klebicin D. Moreover, SDS-PAGE analysis showed that the relative mass of CaroS2K was 85 kDa and that of CaroS2I was 10 kDa. Conclusion This study shown that another nuclease type of bacteriocin was found in Pectobacterium carotovorum. This new type of bacteriocin, Carocin S2, has the ribonuclease activity of CaroS2K and the immunity protein activity of CaroS2I.

  6. Multiwavelength excitation Raman scattering analysis of bulk and two-dimensional MoS2: vibrational properties of atomically thin MoS2 layers

    International Nuclear Information System (INIS)

    Placidi, Marcel; Dimitrievska, Mirjana; Izquierdo-Roca, Victor; Fontané, Xavier; Espindola-Rodriguez, Moises; López-Marino, Simon; Neuschitzer, Markus; Pérez-Rodríguez, Alejandro; Castellanos-Gomez, Andres; Pérez-Tomás, Amador; Mestres, Narcis; Bermudez, Veronica; Yaremko, Anatoliy

    2015-01-01

    In order to deepen the knowledge of the vibrational properties of two-dimensional (2D) MoS 2 atomic layers, a complete and systematic Raman scattering analysis has been performed using both bulk single-crystal MoS 2 samples and atomically thin MoS 2 layers. Raman spectra have been measured under non-resonant and resonant conditions using seven different excitation wavelengths from near-infrared (NIR) to ultraviolet (UV). These measurements have allowed us to observe and identify 41 peaks, among which 22 have not been previously experimentally observed for this compound, and characterize the existence of different resonant excitation conditions for the different excitation wavelengths. This has also included the first analysis of resonant Raman spectra that are achieved using UV excitation conditions. In addition, the analysis of atomically thin MoS 2 layers has corroborated the higher potential of UV resonant Raman scattering measurements for the non-destructive assessment of 2D MoS 2 samples. Analysis of the relative integral intensity of the additional first- and second-order peaks measured under UV resonant excitation conditions is proposed for the non-destructive characterization of the thickness of the layers, complementing previous studies based on the changes of the peak frequencies. (paper)

  7. The mode of evolution of aggregation pheromones in Drosophila species

    NARCIS (Netherlands)

    Symonds, MRE; Wertheim, B

    Aggregation pheromones are used by fruit flies of the genus Drosophila to assemble on breeding substrates, where they feed, mate and oviposit communally. These pheromones consist of species-specific blends of chemicals. Here, using a phylogenetic framework, we examine how differences among species

  8. Comprehensive functional analysis of Rab GTPases in Drosophila nephrocytes.

    Science.gov (United States)

    Fu, Yulong; Zhu, Jun-Yi; Zhang, Fujian; Richman, Adam; Zhao, Zhanzheng; Han, Zhe

    2017-06-01

    The Drosophila nephrocyte is a critical component of the fly renal system and bears structural and functional homology to podocytes and proximal tubule cells of the mammalian kidney. Investigations of nephrocyte cell biological processes are fundamental to understanding the insect renal system. Nephrocytes are highly active in endocytosis and vesicle trafficking. Rab GTPases regulate endocytosis and trafficking but specific functions of nephrocyte Rabs remain undefined. We analyzed Rab GTPase expression and function in Drosophila nephrocytes and found that 11 out of 27 Drosophila Rabs were required for normal activity. Rabs 1, 5, 7, 11 and 35 were most important. Gene silencing of the nephrocyte-specific Rab5 eliminated all intracellular vesicles and the specialized plasma membrane structures essential for nephrocyte function. Rab7 silencing dramatically increased clear vacuoles and reduced lysosomes. Rab11 silencing increased lysosomes and reduced clear vacuoles. Our results suggest that Rab5 mediates endocytosis that is essential for the maintenance of functionally critical nephrocyte plasma membrane structures and that Rabs 7 and 11 mediate alternative downstream vesicle trafficking pathways leading to protein degradation and membrane recycling, respectively. Elucidating molecular pathways underlying nephrocyte function has the potential to yield important insights into human kidney cell physiology and mechanisms of cell injury that lead to disease. The Drosophila nephrocyte is emerging as a useful in vivo model system for molecular target identification and initial testing of therapeutic approaches in humans.

  9. Resources for Functional Genomics Studies in Drosophila melanogaster

    Science.gov (United States)

    Mohr, Stephanie E.; Hu, Yanhui; Kim, Kevin; Housden, Benjamin E.; Perrimon, Norbert

    2014-01-01

    Drosophila melanogaster has become a system of choice for functional genomic studies. Many resources, including online databases and software tools, are now available to support design or identification of relevant fly stocks and reagents or analysis and mining of existing functional genomic, transcriptomic, proteomic, etc. datasets. These include large community collections of fly stocks and plasmid clones, “meta” information sites like FlyBase and FlyMine, and an increasing number of more specialized reagents, databases, and online tools. Here, we introduce key resources useful to plan large-scale functional genomics studies in Drosophila and to analyze, integrate, and mine the results of those studies in ways that facilitate identification of highest-confidence results and generation of new hypotheses. We also discuss ways in which existing resources can be used and might be improved and suggest a few areas of future development that would further support large- and small-scale studies in Drosophila and facilitate use of Drosophila information by the research community more generally. PMID:24653003

  10. Multidimensional analysis of Drosophila wing variation in Evolution ...

    Indian Academy of Sciences (India)

    In this study, using Drosophila melanogaster isofemale lines derived from wild flies collected on both slopes of the canyon, we investigated the effect of developmental temperature upon the different components of phenotypic variation of a complex trait: the wing. Combining geometric and traditional morphometrics, we find ...

  11. A map of taste neuron projections in the Drosophila CNS

    Indian Academy of Sciences (India)

    We provide a map of the projections of taste neurons in the CNS of Drosophila. Using a collection of 67 GAL4 drivers representing the entire repertoire of Gr taste receptors, we systematically map the projections of neurons expressing these drivers in the thoracico-abdominal ganglion and the suboesophageal ganglion ...

  12. Investigating Biological Controls to Suppress Spotted Wing Drosophila Populations

    Science.gov (United States)

    The spotted wing drosophila has become a major cherry pest in California. To develop sustainable management options for this highly mobile pest, we worked with cooperators at Oregon State University and the USDA to discover and import natural enemies of the fly from its native range in South Korea ...

  13. Dynamical Analysis of bantam-Regulated Drosophila Circadian Rhythm Model

    Science.gov (United States)

    Li, Ying; Liu, Zengrong

    MicroRNAs (miRNAs) interact with 3‧untranslated region (UTR) elements of target genes to regulate mRNA stability or translation, and play a crucial role in regulating many different biological processes. bantam, a conserved miRNA, is involved in several functions, such as regulating Drosophila growth and circadian rhythm. Recently, it has been discovered that bantam plays a crucial role in the core circadian pacemaker. In this paper, based on experimental observations, a detailed dynamical model of bantam-regulated circadian clock system is developed to show the post-transcriptional behaviors in the modulation of Drosophila circadian rhythm, in which the regulation of bantam is incorporated into a classical model. The dynamical behaviors of the model are consistent with the experimental observations, which shows that bantam is an important regulator of Drosophila circadian rhythm. The sensitivity analysis of parameters demonstrates that with the regulation of bantam the system is more sensitive to perturbations, indicating that bantam regulation makes it easier for the organism to modulate its period against the environmental perturbations. The effectiveness in rescuing locomotor activity rhythms of mutated flies shows that bantam is necessary for strong and sustained rhythms. In addition, the biological mechanisms of bantam regulation are analyzed, which may help us more clearly understand Drosophila circadian rhythm regulated by other miRNAs.

  14. Species and genetic diversity in the genus Drosophila inhabiting the ...

    Indian Academy of Sciences (India)

    Genus Drosophila belongs to the family Drosophilidae (class Insecta, order Diptera), characterized by rich species diversity at global level and also in India, which is a megadiverse country. At global level, more than 1500 species have been described and several thousands estimated. Hawaiian Islands are particularly rich ...

  15. Is premating isolation in Drosophila overestimated due to ...

    Indian Academy of Sciences (India)

    ... give rise to statistically significant results in multiple-choice mating tests, leading to positive isolation values and the artifactual inference of sexual isolation between populations. This fact agrees with a nonrandom excess of significant positive tests found in a review of the literature of Drosophila intraspecific mating choice.

  16. Evolution of genes and genomes on the Drosophila phylogeny

    DEFF Research Database (Denmark)

    Clark, Andrew G; Eisen, Michael B; Smith, Douglas R

    2007-01-01

    Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the ...

  17. Fluctuation-Driven Neural Dynamics Reproduce Drosophila Locomotor Patterns.

    Directory of Open Access Journals (Sweden)

    Andrea Maesani

    2015-11-01

    Full Text Available The neural mechanisms determining the timing of even simple actions, such as when to walk or rest, are largely mysterious. One intriguing, but untested, hypothesis posits a role for ongoing activity fluctuations in neurons of central action selection circuits that drive animal behavior from moment to moment. To examine how fluctuating activity can contribute to action timing, we paired high-resolution measurements of freely walking Drosophila melanogaster with data-driven neural network modeling and dynamical systems analysis. We generated fluctuation-driven network models whose outputs-locomotor bouts-matched those measured from sensory-deprived Drosophila. From these models, we identified those that could also reproduce a second, unrelated dataset: the complex time-course of odor-evoked walking for genetically diverse Drosophila strains. Dynamical models that best reproduced both Drosophila basal and odor-evoked locomotor patterns exhibited specific characteristics. First, ongoing fluctuations were required. In a stochastic resonance-like manner, these fluctuations allowed neural activity to escape stable equilibria and to exceed a threshold for locomotion. Second, odor-induced shifts of equilibria in these models caused a depression in locomotor frequency following olfactory stimulation. Our models predict that activity fluctuations in action selection circuits cause behavioral output to more closely match sensory drive and may therefore enhance navigation in complex sensory environments. Together these data reveal how simple neural dynamics, when coupled with activity fluctuations, can give rise to complex patterns of animal behavior.

  18. Coexistence of three different Drosophila species by rescheduling ...

    Indian Academy of Sciences (India)

    We present evidence for coexistence of three different Drosophila species by rescheduling their life history traits in a natural population using the same resource, at the ... Genetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi 221 005, India; Department of Zoology, Institute of Basic Sciences, ...

  19. Drosophila phosphopantothenoylcysteine synthetase is required for tissue morphogenesis during oogenesis

    NARCIS (Netherlands)

    Bosveld, Floris; Rana, Anil; Lemstra - Wierenga, Willemina; Kampinga, Harm; Sibon, Ody

    2008-01-01

    Background: Coenzyme A (CoA) is an essential metabolite, synthesized from vitamin B5 by the subsequent action of five enzymes: PANK, PPCS, PPCDC, PPAT and DPCK. Mutations in Drosophila dPPCS disrupt female fecundity and in this study we analyzed the female sterile phenotype of dPPCS mutants in

  20. Odour avoidance learning in the larva of Drosophila melanogaster

    Indian Academy of Sciences (India)

    2008-12-11

    Dec 11, 2008 ... Drosophila larvae can be trained to avoid odours associated with electric shock. We describe here, an improved method of aversive conditioning and a procedure for decomposing learning retention curve that enables us to do a quantitative analysis of memory phases, short term (STM), middle term (MTM) ...

  1. Muscarinic ACh Receptors Contribute to Aversive Olfactory Learning in Drosophila.

    Science.gov (United States)

    Silva, Bryon; Molina-Fernández, Claudia; Ugalde, María Beatriz; Tognarelli, Eduardo I; Angel, Cristian; Campusano, Jorge M

    2015-01-01

    The most studied form of associative learning in Drosophila consists in pairing an odorant, the conditioned stimulus (CS), with an unconditioned stimulus (US). The timely arrival of the CS and US information to a specific Drosophila brain association region, the mushroom bodies (MB), can induce new olfactory memories. Thus, the MB is considered a coincidence detector. It has been shown that olfactory information is conveyed to the MB through cholinergic inputs that activate acetylcholine (ACh) receptors, while the US is encoded by biogenic amine (BA) systems. In recent years, we have advanced our understanding on the specific neural BA pathways and receptors involved in olfactory learning and memory. However, little information exists on the contribution of cholinergic receptors to this process. Here we evaluate for the first time the proposition that, as in mammals, muscarinic ACh receptors (mAChRs) contribute to memory formation in Drosophila. Our results show that pharmacological and genetic blockade of mAChRs in MB disrupts olfactory aversive memory in larvae. This effect is not explained by an alteration in the ability of animals to respond to odorants or to execute motor programs. These results show that mAChRs in MB contribute to generating olfactory memories in Drosophila.

  2. Limitations of the RAPD technique in phylogeny reconstruction in Drosophila

    NARCIS (Netherlands)

    van de Zande, Louis; Bijlsma, R.

    In this study the limitations of the RAPD technique for phylogenetic analysis of very closely related and less related species of Drosophila are examined. In addition, assumptions of positional homology of amplified fragments in different species are examined by cross-hybridization of RAPD

  3. Active sampling and decision making in Drosophila chemotaxis

    NARCIS (Netherlands)

    Gomez-Marin, Alex; Stephens, Greg J; Louis, Matthieu

    2011-01-01

    The ability to respond to chemical stimuli is fundamental to the survival of motile organisms, but the strategies underlying odour tracking remain poorly understood. Here we show that chemotaxis in Drosophila melanogaster larvae is an active sampling process analogous to sniffing in vertebrates.

  4. Gene structure of Drosophila diaphorase-1: diversity of transcripts in ...

    Indian Academy of Sciences (India)

    Moreover, we obtained only the third transcript (CG4199-RC) in the sample of testis from adult flies and the fourth transcript (CG4199-RD) in an embryo sample. None of the other five transcripts were found in the samples of different organs and in the samples obtained at different stages of Drosophila development.

  5. The Drosophila bipectinata species complex: degree of sterility and ...

    Indian Academy of Sciences (India)

    Genetica 140, 75–81. Banerjee P. and Singh B. N. 2015 Interspecific hybridization does not affect the level of fluctuating asymmetry (FA) in the. Drosophila bipectinata species complex. Genetica 143, 459–471. Barbash B. A., Awadalla P. and Parone A. M. 2004 Functional divergence caused by ancient positive selection of ...

  6. Odour avoidance learning in the larva of Drosophila melanogaster

    Indian Academy of Sciences (India)

    Prakash

    with electric shock in normal and mutant larvae and Tully et al. reported the passage of olfactory ... Drosophila larvae can be trained to avoid odours associated with electric shock. We describe here, an improved method of ..... Pairing odour with shock drives the larvae to the opposite zone. Preference learning index PLI.

  7. Gene structure of Drosophila diaphorase-1: diversity of transcripts in ...

    Indian Academy of Sciences (India)

    Drosophila culture. Adult D. melanogaster were maintained on a standard corn- meal/agar medium at 25. ◦. C. Embryos (2 h), larvae (third in- star), pupae (light and dark) were selected from mass cul- tures. The different organs (ovaries, testes and heads) were collected from adult flies. RT-PCR. The cDNA samples from ...

  8. Drosophila simulans Lethal hybrid rescue mutation (Lhr) rescues ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Genetics; Volume 86; Issue 3. Drosophila simulans Lethal hybrid rescue mutation (Lhr) rescues inviable hybrids by restoring X chromosomal dosage compensation and causes fluctuating asymmetry of development. R. N. Chatterjee P. Chatterjee A. Pal M. Pal-Bhadra. Research Article Volume 86 ...

  9. Immunohistological techniques for studying the Drosophila male germline stem cell.

    Science.gov (United States)

    Singh, Shree Ram; Hou, Steven X

    2008-01-01

    Stem cells are undifferentiated cells that have a remarkable ability to self-renew and produce differentiated cells that support normal development and tissue homeostasis. This unique capacity makes stem cells a powerful tool for future regenerative medicine and gene therapy. Accumulative evidence suggests that stem cell self-renewal or differentiation is controlled by both intrinsic and extrinsic factors, and that deregulation of stem cell behavior results in cancer formation, tissue degeneration, and premature aging. The Drosophila testis provides an excellent in vivo model for studying and understanding the fundamental cellular and molecular mechanisms controlling stem cell behavior and the relationship between niches and stem cells. At the tip of the Drosophila testes, germline stem cells (GSCs) and somatic stem cells (SSCs) contact each other and share common niches (known as a hub) to maintain spermatogenesis. Signaling pathways, such as the Janus kinase (JAK)/signal transducer and activator of transcription (STAT), bone morphogenetic protein (BMP), ras-associated protein-guanine nucleotide exchange factor for small GTPase (Rap-GEF), and epidermal growth factor receptor (EGFR)/mitogen-activated protein kinase (MAPK), are known to regulate self-renewal or differentiation of Drosophila male germline stem cells. We describe the detailed in vivo immunohistological protocols that mark GSCs, SSCs, and their progeny in Drosophila testes.

  10. Drosophila simulans Lethal hybrid rescue mutation (Lhr) rescues ...

    Indian Academy of Sciences (India)

    yellow (y), and (c) wild type strain of D. simulans (Califor- nia 0251.163 strain) were used for present investigation. Flies were raised on standard Drosophila food medium containing corn-meal – molasses – yeast – agar-agar. Propi- onic acid was added as a mold inhibitor. Adults and all de- velopmental stages were reared ...

  11. Coexistence of three different Drosophila species by rescheduling ...

    Indian Academy of Sciences (India)

    Unknown

    We present evidence for coexistence of three different Drosophila species by rescheduling their life history traits in a natural population using the same resource, at the same time and same place. D. ananassae has faster larval develop- ment time (DT) and faster DT(egg-fly) than other two species thus utilizing the ...

  12. Monitoring Drosophila suzukii Matsumura in Oregon, USA sweet cherry orchards.

    Science.gov (United States)

    Drosophila suzukii rapidly became a significant cherry pest in the western United States after it was observed damaging cherries in 2009 in California. It has caused significant damage to ripening cherries in all major USA cherry production districts leading to increased management costs and reduced...

  13. Ultradian rhythm unmasked in the Pdf clock mutant of Drosophila

    Indian Academy of Sciences (India)

    2014-07-20

    Jul 20, 2014 ... A diverse range of organisms shows physiological and behavioural rhythms with various periods. Extensive studies have been performed to elucidate the molecular mechanisms of circadian rhythms with an approximately 24 h period in both Drosophila and mammals, while less attention has been paid to ...

  14. Thermal phenotypic plasticity of body size in Drosophila ...

    Indian Academy of Sciences (India)

    Thermal phenotypic plasticity of body size in Drosophila melanogaster: sexual dimorphism and genetic correlations. Jean R. David Amir Yassin ... Thirty isofemale lines collected in three different years from the same wild French population were grown at seven different temperatures (12–31°C). Two linear measures, wing ...

  15. Ultradian rhythm unmasked in the Pdf clock mutant of Drosophila

    Indian Academy of Sciences (India)

    A diverse range of organisms shows physiological and behavioural rhythms with various periods. Extensive studies have been performed to elucidate the molecular mechanisms of circadian rhythms with an approximately 24 h period in both Drosophila and mammals, while less attention has been paid to ultradian rhythms ...

  16. is pupation height affected by circadian organization in Drosophila ...

    Indian Academy of Sciences (India)

    Unknown

    and reproduction related events that constitute the life- history of an .... of light are not perceived by the Drosophila circadian system. (Chandrashekaran et al. 1973) ..... J. Insect. Physiol. 13, 1547–1568. Rizki M. T. M. and Davis C. G. Jr. 1953 Light as an ecological determinant of interspecific competition between D. willistoni.

  17. DIRECT SELECTION ON LIFE-SPAN IN DROSOPHILA-MELANOGASTER

    NARCIS (Netherlands)

    ZWAAN, B; BIJLSMA, R; HOEKSTRA, RE

    An important issue in the study of the evolution of aging in Drosophila melanogaster is whether decreased early fecundity is inextricably coupled with increased life span in selection experiments on age at reproduction. Here, this problem has been tackled using an experimental design in which

  18. Genotype–environment interaction for total fitness in Drosophila

    Indian Academy of Sciences (India)

    2008-12-23

    Dec 23, 2008 ... A fundamental assumption of models for the maintenance of genetic variation by environmental heterogeneity is that selection favours different genotypes in different environments. Here, I use a method for measuring total fitness of chromosomal heterozygotes in Drosophila melanogaster to assess ...

  19. Metabolic Activity of Radish Sprouts Derived Isothiocyanates in Drosophila melanogaster

    Science.gov (United States)

    Baenas, Nieves; Piegholdt, Stefanie; Schloesser, Anke; Moreno, Diego A.; García-Viguera, Cristina; Rimbach, Gerald; Wagner, Anika E.

    2016-01-01

    We used Drosophila melanogaster as a model system to study the absorption, metabolism and potential health benefits of plant bioactives derived from radish sprouts (Raphanus sativus cv. Rambo), a Brassicaceae species rich in glucosinolates and other phytochemicals. Flies were subjected to a diet supplemented with lyophilized radish sprouts (10.6 g/L) for 10 days, containing high amounts of glucoraphenin and glucoraphasatin, which can be hydrolyzed by myrosinase to the isothiocyanates sulforaphene and raphasatin, respectively. We demonstrate that Drosophila melanogaster takes up and metabolizes isothiocyanates from radish sprouts through the detection of the metabolite sulforaphane-cysteine in fly homogenates. Moreover, we report a decrease in the glucose content of flies, an upregulation of spargel expression, the Drosophila homolog of the mammalian PPARγ-coactivator 1 α, as well as the inhibition of α-amylase and α-glucosidase in vitro. Overall, we show that the consumption of radish sprouts affects energy metabolism in Drosophila melanogaster which is reflected by lower glucose levels and an increased expression of spargel, a central player in mitochondrial biogenesis. These processes are often affected in chronic diseases associated with aging, including type II diabetes mellitus. PMID:26901196

  20. Genetic Analysis of Micro-environmental Plasticity in Drosophila melanogaster

    DEFF Research Database (Denmark)

    Morgante, Fabio; Sorensen, Daniel A; Sørensen, Peter

    be genetically variable. This study utilized the Drosophila Genetic Reference Panel (DGRP) to accurately estimate the genetic variance of micro-environmental plasticity for chill coma recovery time and startle response. Estimates of broad sense heritabilities for both traits are substantial (from 0.51 to 0...

  1. Modern aspects of Drosophila melanogaster radiobiology. Apoptosis and aging

    International Nuclear Information System (INIS)

    Zajnulin, V.G.; Moskalev, A.A.; Shaposhnikov, M.V.; Taskaev, A.I.

    1999-01-01

    An attempt is made to explain the radioinduced change in life span of multicell organisms by deregulation of apoptosis processes. Radiation capacity to induce the apoptosis is shown in Drosophila as well. Assumption is made that radiation changes the rate of natural organism aging deregulating the control of apoptosis mechanisms [ru

  2. Nearly Neutral Evolution Across the Drosophila melanogaster Genome

    DEFF Research Database (Denmark)

    Esteve, David Castellano; James, Jennifer; Eyre-Walker, Adam

    2017-01-01

    Under the nearly neutral theory of molecular evolution the proportion of effectively neutral mutations is expected to depend upon the effective population size (Ne). Here we investigate whether this is the case across the genome of Drosophila melanogaster using polymorphism data from 128 North...

  3. P element excision in drosophila melanogaster and related drosophilids

    Science.gov (United States)

    The frequency of P element excision and the structure of the resulting excision products were determined in three drosophilid species, Drosophila melanogaster, D. virilis, and Chymomyza procnemis. A transient P element mobility assay was conducted in the cells of developing insect embryos, but unlik...

  4. mutations of Drosophila melanogaster cause nonrandom cell death ...

    Indian Academy of Sciences (India)

    In Drosophila melanogaster, the intersex (ix) is a terminally positioned gene in somatic sex determination hierarchy and function with the female specific product of double sex (DSXF) to implement female sexual differentiation. The null phenotype of ix is to transform diplo-X individuals into intersexes while leaving haplo-X ...

  5. Handling Alters Aggression and "Loser" Effect Formation in "Drosophila Melanogaster"

    Science.gov (United States)

    Trannoy, Severine; Chowdhury, Budhaditya; Kravitz, Edward A.

    2015-01-01

    In "Drosophila," prior fighting experience influences the outcome of later contests: losing a fight increases the probability of losing second contests, thereby revealing "loser" effects that involve learning and memory. In these experiments, to generate and quantify the behavioral changes observed as consequences of losing…

  6. The metabolic profile of long-lived Drosophila melanogaster

    DEFF Research Database (Denmark)

    Sarup, Pernille Merete; Pedersen, Simon Metz Mariendal; Nielsen, Niels Chr

    2012-01-01

    We investigated the age-related changes in the metabolic profile of male Drosophila melanogaster and compared the metabolic profile of flies selected for increased longevity to that of control flies of equal age. We found clear differences in metabolite composition between selection regimes...

  7. Inbreeding affects locomotor activity in Drosophila melanogaster at different ages

    DEFF Research Database (Denmark)

    Manenti, Tommaso; Pertoldi, Cino; Nasiri Moghadam, Neda

    2015-01-01

    The ability to move is essential for many behavioural traits closely related to fitness. Here we studied the effect of inbreeding on locomotor activity (LA) of Drosophila melanogaster at different ages under both dark and light regimes. We expected to find a decreased LA in inbred lines compared...

  8. Characterization of reproductive dormancy in male Drosophila melanogaster

    Czech Academy of Sciences Publication Activity Database

    Kubrak, O. I.; Kučerová, Lucie; Theopold, U.; Nylin, S.; Nässel, D. R.

    2016-01-01

    Roč. 7, NOV 24 (2016), č. článku 572. ISSN 1664-042X Institutional support: RVO:60077344 Keywords : Drosophila melanogaster * diapause * reproduction Subject RIV: ED - Physiology Impact factor: 4.134, year: 2016 http://journal.frontiersin.org/article/10.3389/fphys.2016.00572/full

  9. Late replication domains are evolutionary conserved in the Drosophila genome.

    Science.gov (United States)

    Andreyenkova, Natalya G; Kolesnikova, Tatyana D; Makunin, Igor V; Pokholkova, Galina V; Boldyreva, Lidiya V; Zykova, Tatyana Yu; Zhimulev, Igor F; Belyaeva, Elena S

    2013-01-01

    Drosophila chromosomes are organized into distinct domains differing in their predominant chromatin composition, replication timing and evolutionary conservation. We show on a genome-wide level that genes whose order has remained unaltered across 9 Drosophila species display late replication timing and frequently map to the regions of repressive chromatin. This observation is consistent with the existence of extensive domains of repressive chromatin that replicate extremely late and have conserved gene order in the Drosophila genome. We suggest that such repressive chromatin domains correspond to a handful of regions that complete replication at the very end of S phase. We further demonstrate that the order of genes in these regions is rarely altered in evolution. Substantial proportion of such regions significantly coincide with large synteny blocks. This indicates that there are evolutionary mechanisms maintaining the integrity of these late-replicating chromatin domains. The synteny blocks corresponding to the extremely late-replicating regions in the D. melanogaster genome consistently display two-fold lower gene density across different Drosophila species.

  10. Dosage compensation and demasculinization of X chromosomes in Drosophila.

    Science.gov (United States)

    Bachtrog, Doris; Toda, Nicholas R T; Lockton, Steven

    2010-08-24

    The X chromosome of Drosophila shows a deficiency of genes with male-biased expression, whereas mammalian X chromosomes are enriched for spermatogenesis genes expressed premeiosis and multicopy testis genes. Meiotic X-inactivation and sexual antagonism can only partly account for these patterns. Here, we show that dosage compensation (DC) in Drosophila may contribute substantially to the depletion of male genes on the X. To equalize expression between X-linked and autosomal genes in the two sexes, male Drosophila hypertranscribe their single X, whereas female mammals silence one of their two X chromosomes. We combine fine-scale mapping data of dosage compensated regions with genome-wide expression profiles and show that most male-biased genes on the D. melanogaster X are located outside dosage compensated regions. Additionally, X-linked genes that have newly acquired male-biased expression in D. melanogaster are less likely to be dosage compensated, and parental X-linked genes that gave rise to an autosomal male-biased retrocopy are more likely located within compensated regions. This suggests that DC contributes to the observed demasculinization of X chromosomes in Drosophila, both by limiting the emergence of male-biased expression patterns of existing X genes, and by contributing to gene trafficking of male genes off the X. Copyright 2010 Elsevier Ltd. All rights reserved.

  11. Gene structure of Drosophila diaphorase-1: diversity of transcripts in ...

    Indian Academy of Sciences (India)

    [Ivanova P. M., Dunkov B. H. and Ralchev K. H. 2008 Gene structure of Drosophila diaphorase-1: diversity of transcripts in adult males and females, in different ... ditions, close to 60 kD, indicating a monomeric structure. (Ralchev et al. .... Diversity in the exon–intron organization of diaphorase-1 gene. The six transcripts with ...

  12. Species and genetic diversity in the genus Drosophila inhabiting the ...

    Indian Academy of Sciences (India)

    These species are D. ananassae, D. melanogaster,. D. bipectinata, D. nasuta and a few others. The work done was with particular reference to inversion and allozyme poly- morphisms and .... species diversity, the scenario of Drosophila research is not ..... vary in their susceptibility to starvation owing to the differ- ence in ...

  13. Status of research on Drosophila ananassae at global level

    Indian Academy of Sciences (India)

    Extensive research work on D. ananassae has been done by numerous researchers per- taining to ... Also, the polytene chromosomes of. Keywords. genetic peculiarities; status of research; global level; Drosophila ananassae. Journal of Genetics, Vol. 94, No. ..... starvation because of difference in their propensity to store.

  14. Ultradian rhythm unmasked in the Pdf clock mutant of Drosophila

    Indian Academy of Sciences (India)

    ... kept under constant dark conditions. In particular, the Pigment-dispersing factor mutant (Pdf01) demonstrated a precise and robust ultradian rhythmicity, which was not temperature compensated. Our results suggest that Drosophila has an endogenous ultradian oscillator that is masked by circadian rhythmic behaviours.

  15. The route of infection determines Wolbachia antibacterial protection in Drosophila

    Science.gov (United States)

    Gupta, Vanika; Vasanthakrishnan, Radhakrishnan B.; Siva-Jothy, Jonathon; Monteith, Katy M.; Brown, Sam P.

    2017-01-01

    Bacterial symbionts are widespread among metazoans and provide a range of beneficial functions. Wolbachia-mediated protection against viral infection has been extensively demonstrated in Drosophila. In mosquitoes that are artificially transinfected with Drosophila melanogaster Wolbachia (wMel), protection from both viral and bacterial infections has been demonstrated. However, no evidence for Wolbachia-mediated antibacterial protection has been demonstrated in Drosophila to date. Here, we show that the route of infection is key for Wolbachia-mediated antibacterial protection. Drosophila melanogaster carrying Wolbachia showed reduced mortality during enteric—but not systemic—infection with the opportunist pathogen Pseudomonas aeruginosa. Wolbachia-mediated protection was more pronounced in male flies and is associated with increased early expression of the antimicrobial peptide Attacin A, and also increased expression of a reactive oxygen species detoxification gene (Gst D8). These results highlight that the route of infection is important for symbiont-mediated protection from infection, that Wolbachia can protect hosts by eliciting a combination of resistance and disease tolerance mechanisms, and that these effects are sexually dimorphic. We discuss the importance of using ecologically relevant routes of infection to gain a better understanding of symbiont-mediated protection. PMID:28592678

  16. Thermal phenotypic plasticity of body size in Drosophila ...

    Indian Academy of Sciences (India)

    ... body size in Drosophila melanogaster: sexual dimorphism and genetic correlations. Jean R. David, Amir Yassin, Jean-Claude Moreteau, Helene Legout and Brigitte Moreteau. J. Genet. 90, 295–302. Table 1. Correlations between wing and thorax length at the within (n = 420) and between line level (n = 30). Temperature.

  17. Preparation of Isotactic Polypropylene/Exfoliated MoS2 Nanocomposites via In Situ Intercalative Polymerization

    Directory of Open Access Journals (Sweden)

    He-Xin Zhang

    2017-10-01

    Full Text Available In this research, a Ziegler–Natta catalyst intercalated MoS2 was synthesized through the intercalation of a Grignard reagent into MoS2 galleries, followed by the anchoring of TiCl4. During propylene polymerization, the intercalated MoS2 exfoliated in situ to form PP/exfoliated MoS2 (EMoS2 nanocomposites. The isotactic index values of the resultant PP/EMoS2 nanocomposites were as high as 99%, varying from 98.1% to 99.0%. It was found that the incorporation of the EMoS2 significantly improved the thermal stability and mechanical properties (tensile strength, modulus, and elongation at break of PP. After introduction of EMoS2, the maximum increases in Td5% and Tdmax were 36.9 and 9.7 °C, respectively, relative to neat PP. After blending with commercial PP, the resultant nanocomposites increase in tensile strength and modulus up to 11.4% and 61.2% after 0.52 wt % EMoS2 loading. Thus, this work provides a new way to produce high-performance PP.

  18. A tunnelling study on polymer/1T-LixTaS2 layered nanocomposites

    International Nuclear Information System (INIS)

    Enomoto, Hiroyuki; Takai, Hiroyuki; Ozaki, Hajime; Lerner, Michael M

    2004-01-01

    Electronic structures near the Fermi level of polymer/1T-Li x TaS 2 layered nanocomposites have been studied by tunnelling spectroscopy. Polymer/1T-Li x TaS 2 layered nanocomposites were synthesized by using the exfoliation-adsorption technique. Single crystals of 1T-TaS 2 were used as host materials. Poly(ethylene oxide) (PEO) and poly(ethylenimine) (PEI) with different molecular weights were adopted as guest intercalants. Powder x-ray diffraction patterns showed that all samples of the polymer/1T-Li x TaS 2 layered nanocomposites contain organic polymer between all individual 1T-TaS 2 sheets. Although 1T-TaS 2 single crystal is well known to show quite unique temperature dependences of the resistivity due to the charge density wave (CDW), the resistivities of all polymer/1T-Li x TaS 2 nanocomposites showed semiconductor-like temperature dependences. The tunnelling spectra of polymer/1T-Li x TaS 2 nanocomposites revealed that the CDW gap disappears in the density of states near the Fermi level of polymer/1T-Li x TaS 2 nanocomposites and their electronic structures show a metallic behaviour

  19. Structure Re-determination and Superconductivity Observation of Bulk 1T MoS2

    OpenAIRE

    Fang, Yuqiang; Pan, Jie; He, Jianqiao; Luo, Ruichun; Wang, Dong; Che, Xiangli; Bu, Kejun; Zhao, Wei; Liu, Pan; Mu, Gang; Zhang, Hui; Lin, Tianquan; Huang, Fuqiang

    2017-01-01

    2H MoS2 has been intensively studied because of layer-dependent electronic structures and novel physical properties. Though the metastable 1T MoS2 with the [MoS6] octahedron was observed from the microscopic area, the true crystal structure of 1T phase has not been determined strictly. Moreover, the true physical properties have not been demonstrated from experiments due to the challenge for the preparation of pure 1T MoS2 crystals. Here, we successfully synthesized the 1T MoS2 single crystal...

  20. Tandem Duplications and the Limits of Natural Selection in Drosophila yakuba and Drosophila simulans.

    Directory of Open Access Journals (Sweden)

    Rebekah L Rogers

    Full Text Available Tandem duplications are an essential source of genetic novelty, and their variation in natural populations is expected to influence adaptive walks. Here, we describe evolutionary impacts of recently-derived, segregating tandem duplications in Drosophila yakuba and Drosophila simulans. We observe an excess of duplicated genes involved in defense against pathogens, insecticide resistance, chorion development, cuticular peptides, and lipases or endopeptidases associated with the accessory glands across both species. The observed agreement is greater than expectations on chance alone, suggesting large amounts of convergence across functional categories. We document evidence of widespread selection on the D. simulans X, suggesting adaptation through duplication is common on the X. Despite the evidence for positive selection, duplicates display an excess of low frequency variants consistent with largely detrimental impacts, limiting the variation that can effectively facilitate adaptation. Standing variation for tandem duplications spans less than 25% of the genome in D. yakuba and D. simulans, indicating that evolution will be strictly limited by mutation, even in organisms with large population sizes. Effective whole gene duplication rates are low at 1.17 × 10-9 per gene per generation in D. yakuba and 6.03 × 10-10 per gene per generation in D. simulans, suggesting long wait times for new mutations on the order of thousands of years for the establishment of sweeps. Hence, in cases where adaptation depends on individual tandem duplications, evolution will be severely limited by mutation. We observe low levels of parallel recruitment of the same duplicated gene in different species, suggesting that the span of standing variation will define evolutionary outcomes in spite of convergence across gene ontologies consistent with rapidly evolving phenotypes.

  1. Mass spectral studies on quadruply bonded molybdenum complexes, Mo2(S2PF2)4 and Mo2(S2PMe2)4

    International Nuclear Information System (INIS)

    Quamrul Islam, M.

    1993-01-01

    The electron impact mass spectrum of Mo 2 (S 2 PF 2 ) 4 shows the molecular ion which releases a PF 2 group to produce the most abundant ion, Mo 2 S 8 P 3 F 6 + . This ion fragments by releasing a series of groups such as PF 2 , PFS and PF 2 S. For Mo 2 (S 2 PMe 2 ) 4 Desorption Chemical Ionization (DCI) technique is required to see the molecular ion. The parent ion fragments by the loss Me 2 S, PMe 2 S and PMe 3 groups. Loss of PMe 3 from molecular ion suggests rearrangement before fragmentation - a process not observed for Mo 2 (S 2 PF 2 ) 4 . The difference in mass spectral fragmentation patterns is in agreement with the different structures of the two compounds. (author). 14 refs., 1 tab

  2. Erythritol and Lufenuron detrimentally alter age structure of Wild Spotted Wing Drosophila (SWD) Drosophila suzukii (Diptera: Drosophilidae) populations in blueberry and blackberry

    Science.gov (United States)

    We report on the efficacy of 0.5 M (61,000 ppm) Erythritol (E) in Truvia Baking Blend®, 10 ppm Lufenuron (L), and their combination (LE) to reduce egg and larval densities of wild populations of spotted wing Drosophila, Drosophila suzukii (Matsumura) (SWD) infesting fields of rabbiteye blueberries (...

  3. Image tracking study on courtship behavior of Drosophila.

    Directory of Open Access Journals (Sweden)

    Hung-Yin Tsai

    Full Text Available BACKGROUND: In recent years, there have been extensive studies aimed at decoding the DNA. Identifying the genetic cause of specific changes in a simple organism like Drosophila may help scientists recognize how multiple gene interactions may make some people more susceptible to heart disease or cancer. Investigators have devised experiments to observe changes in the gene networks in mutant Drosophila that responds differently to light, or have lower or higher locomotor activity. However, these studies focused on the behavior of the individual fly or on pair-wise interactions in the study of aggression or courtship. The behavior of these activities has been captured on film and inspected by a well-trained researcher after repeatedly watching the recorded film. Some studies also focused on ways to reduce the inspection time and increase the accuracy of the behavior experiment. METHODOLOGY: In this study, the behavior of drosophila during courtship was analyzed automatically by machine vision. We investigated the position and behavior discrimination during courtship using the captured images. Identification of the characteristics of drosophila, including sex, size, heading direction, and wing angles, can be computed using image analysis techniques that employ the Gaussian mixture model. The behavior of multiple drosophilae can also be analyzed simultaneously using the motion-prediction model and the variation constraint of heading direction. CONCLUSIONS: The overlapped fruit flies can be identified based on the relationship between body centers. Moreover, the behaviors and profiles can be correctly recognized by image processing based on the constraints of the wing angle and the size of the body. Therefore, the behavior of the male fruit flies can be discriminated when two or three fruit flies form a close cluster. In this study, the courtship behavior, including wing songs and attempts, can currently be distinguished with accuracies of 95.8% and

  4. Positive and purifying selection on the Drosophila Y chromosome.

    Science.gov (United States)

    Singh, Nadia D; Koerich, Leonardo B; Carvalho, Antonio Bernardo; Clark, Andrew G

    2014-10-01

    Y chromosomes, with their reduced effective population size, lack of recombination, and male-limited transmission, present a unique collection of constraints for the operation of natural selection. Male-limited transmission may greatly increase the efficacy of selection for male-beneficial mutations, but the reduced effective size also inflates the role of random genetic drift. Together, these defining features of the Y chromosome are expected to influence rates and patterns of molecular evolution on the Y as compared with X-linked or autosomal loci. Here, we use sequence data from 11 genes in 9 Drosophila species to gain insight into the efficacy of natural selection on the Drosophila Y relative to the rest of the genome. Drosophila is an ideal system for assessing the consequences of Y-linkage for molecular evolution in part because the gene content of Drosophila Y chromosomes is highly dynamic, with orthologous genes being Y-linked in some species whereas autosomal in others. Our results confirm the expectation that the efficacy of natural selection at weakly selected sites is reduced on the Y chromosome. In contrast, purifying selection on the Y chromosome for strongly deleterious mutations does not appear to be compromised. Finally, we find evidence of recurrent positive selection for 4 of the 11 genes studied here. Our results thus highlight the variable nature of the mode and impact of natural selection on the Drosophila Y chromosome. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Cellular and developmental adaptations to hypoxia: a Drosophila perspective.

    Science.gov (United States)

    Romero, Nuria Magdalena; Dekanty, Andrés; Wappner, Pablo

    2007-01-01

    The fruit fly Drosophila melanogaster, a widely utilized genetic model, is highly resistant to oxygen starvation and is beginning to be used for studying physiological, developmental, and cellular adaptations to hypoxia. The Drosophila respiratory (tracheal) system has features in common with the mammalian circulatory system so that an angiogenesis-like response occurs upon exposure of Drosophila larvae to hypoxia. A hypoxia-responsive system homologous to mammalian hypoxia-inducible factor (HIF) has been described in the fruit fly, where Fatiga is a Drosophila oxygen-dependent HIF prolyl hydroxylase, and the basic helix-loop-helix Per/ARNT/Sim (bHLH-PAS) proteins Sima and Tango are, respectively, the Drosophila homologues of mammalian HIF-alpha (alpha) and HIF-beta (beta). Tango is constitutively expressed regardless of oxygen tension and, like in mammalian cells, Sima is controlled at the level of protein degradation and subcellular localization. Sima is critically required for development in hypoxia, but, unlike mammalian model systems, it is dispensable for development in normoxia. In contrast, fatiga mutant alleles are all lethal; however, strikingly, viability to adulthood is restored in fatiga sima double mutants, although these double mutants are not entirely normal, suggesting that Fatiga has Sima-independent functions in fly development. Studies in cell culture and in vivo have revealed that Sima is activated by the insulin receptor (InR) and target-of-rapamycin (TOR) pathways. Paradoxically, Sima is a negative regulator of growth. This suggests that Sima is engaged in a negative feedback loop that limits growth upon stimulation of InR/TOR pathways.

  6. Tuning Electronic Structure of Single Layer MoS2through Defect and Interface Engineering.

    Science.gov (United States)

    Chen, Yan; Huang, Shengxi; Ji, Xiang; Adepalli, Kiran; Yin, Kedi; Ling, Xi; Wang, Xinwei; Xue, Jianmin; Dresselhaus, Mildred; Kong, Jing; Yildiz, Bilge

    2018-03-27

    Transition-metal dichalcogenides (TMDs) have emerged in recent years as a special group of two-dimensional materials and have attracted tremendous attention. Among these TMD materials, molybdenum disulfide (MoS 2 ) has shown promising applications in electronics, photonics, energy, and electrochemistry. In particular, the defects in MoS 2 play an essential role in altering the electronic, magnetic, optical, and catalytic properties of MoS 2 , presenting a useful way to engineer the performance of MoS 2 . The mechanisms by which lattice defects affect the MoS 2 properties are unsettled. In this work, we reveal systematically how lattice defects and substrate interface affect MoS 2 electronic structure. We fabricated single-layer MoS 2 by chemical vapor deposition and then transferred onto Au, single-layer graphene, hexagonal boron nitride, and CeO 2 as substrates and created defects in MoS 2 by ion irradiation. We assessed how these defects and substrates affect the electronic structure of MoS 2 by performing X-ray photoelectron spectroscopy, Raman and photoluminescence spectroscopies, and scanning tunneling microscopy/spectroscopy measurements. Molecular dynamics and first-principles based simulations allowed us to conclude the predominant lattice defects upon ion irradiation and associate those with the experimentally obtained electronic structure. We found that the substrates can tune the electronic energy levels in MoS 2 due to charge transfer at the interface. Furthermore, the reduction state of CeO 2 as an oxide substrate affects the interface charge transfer with MoS 2 . The irradiated MoS 2 had a faster hydrogen evolution kinetics compared to the as-prepared MoS 2 , demonstrating the concept of defect controlled reactivity in this phase. Our findings provide effective probes for energy band and defects in MoS 2 and show the importance of defect engineering in tuning the functionalities of MoS 2 and other TMDs in electronics, optoelectronics, and

  7. MoS2-modified ZnO quantum dots nanocomposite: Synthesis and ultrafast humidity response

    International Nuclear Information System (INIS)

    Ze, Lu; Yueqiu, Gong; Xujun, Li; Yong, Zhang

    2017-01-01

    Highlights: • MoS 2 @ZnO QDs composite structure was synthesized by two-steps methods. • Ultrafast humidity sensing response is achieved by MoS 2 @ZnO QDs humidity sensor. • Sensor performs excellent cycle stability from 11% to 95% RH. • Humidity sensor could detect wide humidity range (11–95%). - Abstract: In this work, ZnO quantum dots (QDs), layered MoS 2 and MoS 2 -modified ZnO QDs (MoS 2 @ZnO QDs) nanocomposite were synthesized and then applied as humidity sensor. The crystal structure, morphology and element distribution of ZnO QDs, MoS 2 and MoS 2 @ZnO QDs were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectrometry, respectively. The humidity sensing characteristics of the MoS 2 and MoS 2 @ZnO QDs against various relative humidity were measured at room temperature. The results show that the MoS 2 @ZnO QDs sensor exhibits high sensitivity with an impedance variation of three or four orders of magnitude to relative humidity range of 11–95% and it exhibits a short response-recovery time (1 s for adsorption and 20 s for desorption) and excellent repeatability. The mechanisms of the excellent performance for humidity sensing of MoS 2 @ZnO QDs sensor were discussed based on its impedance properties. Our work could offer guidelines to design higher performance especially ultrafast humidity response sensor utilizing the nanocomposite structure with two dimensional material and QDs.

  8. Effect of sterol metabolism in the yeast-Drosophila system on the frequency of radiation-induced aneuploidy in the Drosophila melanogaster oocytes

    International Nuclear Information System (INIS)

    Savitskii, V.V.; Luchnikova, E.M.; Inge-Vechtomov, S.G.

    1986-01-01

    The effect of sterol metabolism on induced mutagenesis of Drosophila melanogaster was studied in the ecogenetic system of yeast-Drosophila. Sterol deficiency was created in Drosophila by using the biomass of live cells of Saccharomyces cerevisiae strain 9-2-P712 till mutation in locus nys/sup r1/ blocking the synthesis of ergosterol as the food. It was found that rearing of Drosophila females on the mutant yeast increases the frequency of loss and nondisjunction of X chromosomes induced in mature oocytes by X rays (1000 R). Addition of 0.1% of cholesterol solution in 10% ethanol to the yeast biomass restores the resistance of oocyte to X irradiation to the control level. The possible hormonal effect on membrane leading to increased radiation-induced aneuploidy in Drosophila and the role of sterol metabolism in determining the resistance to various damaging factors are discussed

  9. Mechanical properties of freely suspended semiconducting graphene-like layers based on MoS2

    NARCIS (Netherlands)

    Castellanos-Gomez, A.; Poot, M.; Steele, G.A.; Van der Zant, H.S.J.; Agrait, N.; Rubio-Bollinger, G.

    2012-01-01

    We fabricate freely suspended nanosheets of molybdenum disulphide (MoS2) which are characterized by quantitative optical microscopy and high-resolution friction force microscopy. We study the elastic deformation of freely suspended nanosheets of MoS2 using an atomic force microscope. The Young’s

  10. S2Biom database with logistical components of the biomass value chain

    NARCIS (Netherlands)

    Annevelink, E.; Groot, de H.L.E.; Shah, N.; Giarola, S.; Pantaleo, M.; Anttila, P.; Vis, Martijn; Raa, te Rik; Berg, van den Douwe; Gabrielle, B.

    2015-01-01

    The S2Biom project (www.s2biom.eu) - Delivery of sustainable supply of non-food biomass to support
    a resource-efficient Bioeconomy in Europe - supports sustainable delivery chains of non-food biomass feedstock.
    This poses a logistical challenge because the quality and handling

  11. Few-layer MoS2 as nitrogen protective barrier

    Science.gov (United States)

    Akbali, B.; Yanilmaz, A.; Tomak, A.; Tongay, S.; Çelebi, C.; Sahin, H.

    2017-10-01

    We report experimental and theoretical investigations of the observed barrier behavior of few-layer MoS2 against nitrogenation. Owing to its low-strength shearing, low friction coefficient, and high lubricity, MoS2 exhibits the demeanor of a natural N-resistant coating material. Raman spectroscopy is done to determine the coating capability of MoS2 on graphene. Surface morphology of our MoS2/graphene heterostructure is characterized by using optical microscopy, scanning electron microscopy, and atomic force microscopy. In addition, density functional theory-based calculations are performed to understand the energy barrier performance of MoS2 against nitrogenation. The penetration of nitrogen atoms through a defect-free MoS2 layer is prevented by a very high vertical diffusion barrier, indicating that MoS2 can serve as a protective layer for the nitrogenation of graphene. Our experimental and theoretical results show that MoS2 material can be used both as an efficient nanocoating material and as a nanoscale mask for selective nitrogenation of graphene layer.

  12. Spin crossover in Fe(II) complexes with N4S2 coordination

    DEFF Research Database (Denmark)

    Arroyave, Alejandra; Lennartson, Anders; Dragulescu-Andrasi, Alina

    2016-01-01

    A systematic study of a series of Fe(II) complexes with the tetradentate N2S2-binding ligand and NCX− coligands (X = S, Se, BH3) conclusively demonstrates the occurrence of temperature-driven spin crossover (SCO), which is rarely observed for the Fe(II) ion in the N4S2 coordination environment...

  13. Identification of Active Edge Sites for Electrochemical H2 Evolution from MoS2 Nanocatalysts

    DEFF Research Database (Denmark)

    Jaramillo, Thomas; Jørgensen, Kristina Pilt; Bonde, Jacob

    2007-01-01

    The identification of the active sites in heterogeneous catalysis requires a combination of surface sensitive methods and reactivity studies. We determined the active site for hydrogen evolution, a reaction catalyzed by precious metals, on nanoparticulate molybdenum disulfide (MoS2) by atomically....... Electrocatalytic activity measurements for hydrogen evolution correlate linearly with the number of edge sites on the MoS2 catalyst....

  14. PTP-S2, a nuclear tyrosine phosphatase, is phosphorylated and ...

    Indian Academy of Sciences (India)

    PTP-S2 is a tyrosine specific protein phosphatase that binds to DNA and is localized to the nucleus in association with chromatin. It plays a role in the regulation of cell proliferation. Here we show that the subcellular distribution of this protein changes during cell division. While PTP-S2 was localized exclusively to the ...

  15. A Route to Permanent Valley Polarization in Monolayer MoS2

    KAUST Repository

    Singh, Nirpendra

    2016-10-24

    Realization of permanent valley polarization in Cr-doped monolayer MoS2 is found to be unfeasible because of extended moment formation. Introduction of an additional hole is suggested as a viable solution. V-doped monolayer MoS2 is demonstrated to sustain permanent valley polarization and therefore can serve as a prototype material for valleytronics.

  16. Frictional and morphological properties of Au-MoS2 films sputtered from a compact target

    Science.gov (United States)

    Spalvins, T.

    1984-01-01

    AuMoS2 films 0.02 to 1.2 microns thick were sputtered from target compacted from 5 wt % Au + 95 wt % MoS2, to investigate the frictional and morphological film growth characteristics. The gold dispersion effects in MoS2 films are of interest to increase the densitification and strengthening of the film structure. Three microstructural growth stages were identified on the nano-micro-macrostructural level. During sliding both sputtered Au-MoS2 and MoS2 films have a tendency to break within the columner region. The remaining or effective film, about 0.2 microns thick, performs the lubrication. The Au-MoS2 films displayed a lower friction coefficient with a high degree of frictional stability and less wear debris generation as compared to pure MoS2 films. The more favorable frictional characteristics of the Au-MoS2 films are attributed to the effective film thickness and the high density packed columner zone which has a reduced effect on the fragmentation of the tapered crystallites during fracture.

  17. Synthesis Methods of Two-Dimensional MoS2: A Brief Review

    Directory of Open Access Journals (Sweden)

    Jie Sun

    2017-07-01

    Full Text Available Molybdenum disulfide (MoS2 is one of the most important two-dimensional materials after graphene. Monolayer MoS2 has a direct bandgap (1.9 eV and is potentially suitable for post-silicon electronics. Among all atomically thin semiconductors, MoS2’s synthesis techniques are more developed. Here, we review the recent developments in the synthesis of hexagonal MoS2, where they are categorized into top-down and bottom-up approaches. Micromechanical exfoliation is convenient for beginners and basic research. Liquid phase exfoliation and solutions for chemical processes are cheap and suitable for large-scale production; yielding materials mostly in powders with different shapes, sizes and layer numbers. MoS2 films on a substrate targeting high-end nanoelectronic applications can be produced by chemical vapor deposition, compatible with the semiconductor industry. Usually, metal catalysts are unnecessary. Unlike graphene, the transfer of atomic layers is omitted. We especially emphasize the recent advances in metalorganic chemical vapor deposition and atomic layer deposition, where gaseous precursors are used. These processes grow MoS2 with the smallest building-blocks, naturally promising higher quality and controllability. Most likely, this will be an important direction in the field. Nevertheless, today none of those methods reproducibly produces MoS2 with competitive quality. There is a long way to go for MoS2 in real-life electronic device applications.

  18. Research progress in photolectric materials of CuFeS2

    Science.gov (United States)

    Jing, Mingxing; Li, Jing; Liu, Kegao

    2018-03-01

    CuFeS2 as a photoelectric material, there are many advantages, such as high optical absorption coefficient, direct gap semiconductor, thermal stability, no photo-recession effect and so on. Because of its low price, abundant reserves and non-toxic, CuFeS2 has attracted extensive attention of scientists.Preparation method of thin film solar cells are included that Electrodeposition, sputtering, thermal evaporation, thermal spraying method, co-reduction method.In this paper, the development of CuFeS2 thin films prepared by co-reduction method and co-reduction method is introduced.In this paper, the structure and development of solar cells, advantages of CuFeS2 as solar cell material, the structure and photoelectric properties and magnetic properties of CuFeS2, preparation process analysis of CuFeS2 thin film, research and development of CuFeS2 in solar cells is included herein. Finally, the development trend of CuFeS2 optoelectronic materials is analyzed and further research directions are proposed.

  19. Structural and optical properties of Zn doped CuInS2 thin films

    Indian Academy of Sciences (India)

    The effects of Zn (0–5%)molecular weight compared with CuInS2 Source and different substrate temperatures on films properties were investigated using X-ray diffraction (XRD) and optical transmission spectra. Optical characteristics of the CuInS2 films have been analysed using spectrophotometer in the wavelength range ...

  20. Magnetic and electrical properties in BaNiS2-type solid solutions

    International Nuclear Information System (INIS)

    Irizawa, Akinori; Yoshimura, Kazuyoshi; Kosuge, Koji

    2000-01-01

    The magnetic and electrical properties are reported in the new solid solutions BaCo 1-x Cu x S 2 and BaNi 1-x Fe x S 2 . Both compounds show spin-glass-like behavior, although the type of spin frustrations is different with each other. BaCo 1-x Cu x S 2 shows a competition type spin-glass behavior with reentrant phenomenon from antiferromagnetic to spin-glass at low temperatures. BaNi 1-x Fe x S 2 shows a dilute type spin-glass behavior together with super-paramagnetic properties. The temperature variation of 57 Fe Moessbauer spectra in BaNi 0.8 Fe 0.2 S 2 is explicable in a framework of cluster-glass. (author)

  1. Heterostructured layered hybrid ZnO/MoS2 nanosheets with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Benavente, Eglantina; Durán, Flor; Sotomayor-Torres, C.; González, Guillermo

    2018-02-01

    A series of novel heterostructured hybrid layered ZnO and MoS2 nanosheets composites were successfully prepared with different MoS2 contents. Among all the prepared materials, ZnO/MoS2 (1:0.05) composite showed enhanced photocatalytic activity for methylene blue degradation under direct solar light compared with pristine ZnO. The MoS2 component played a key role for the visible light activity of the composite system at longer wavelengths. The kinetic equations of photocatalytic reaction and possible photocatalytic degradation mechanism were investigated. The results indicated that it belongs to the zero order kinetic and the photogenerated electrons are transferred from hybrid layered ZnO to the MoS2 nanosheets, facilitating an interfacial electron transfer suppressing the recombination of charge carriers during the photocatalytic degradation.

  2. Defects Engineered Monolayer MoS2 for Improved Hydrogen Evolution Reaction.

    Science.gov (United States)

    Ye, Gonglan; Gong, Yongji; Lin, Junhao; Li, Bo; He, Yongmin; Pantelides, Sokrates T; Zhou, Wu; Vajtai, Robert; Ajayan, Pulickel M

    2016-02-10

    MoS2 is a promising and low-cost material for electrochemical hydrogen production due to its high activity and stability during the reaction. However, the efficiency of hydrogen production is limited by the amount of active sites, for example, edges, in MoS2. Here, we demonstrate that oxygen plasma exposure and hydrogen treatment on pristine monolayer MoS2 could introduce more active sites via the formation of defects within the monolayer, leading to a high density of exposed edges and a significant improvement of the hydrogen evolution activity. These as-fabricated defects are characterized at the scale from macroscopic continuum to discrete atoms. Our work represents a facile method to increase the hydrogen production in electrochemical reaction of MoS2 via defect engineering, and helps to understand the catalytic properties of MoS2.

  3. Improved photoelectrical properties of MoS(2) films after laser micromachining.

    Science.gov (United States)

    Lu, Junpeng; Lu, Jia Hui; Liu, Hongwei; Liu, Bo; Chan, Kim Xinhui; Lin, Jiadan; Chen, Wei; Loh, Kian Ping; Sow, Chorng Haur

    2014-06-24

    Direct patterning of ultrathin MoS2 films with well-defined structures and controllable thickness is appealing since the properties of MoS2 sheets are sensitive to the number of layer and surface properties. In this work, we employed a facile, effective, and well-controlled technique to achieve micropatterning of MoS2 films with a focused laser beam. We demonstrated that a direct focused laser beam irradiation was able to achieve localized modification and thinning of as-synthesized MoS2 films. With a scanning laser beam, microdomains with well-defined structures and controllable thickness were created on the same film. We found that laser modification altered the photoelectrical property of the MoS2 films, and subsequently, photodetectors with improved performance have been fabricated and demonstrated using laser modified films.

  4. Hysteresis in single-layer MoS2 field effect transistors.

    Science.gov (United States)

    Late, Dattatray J; Liu, Bin; Matte, H S S Ramakrishna; Dravid, Vinayak P; Rao, C N R

    2012-06-26

    Field effect transistors using ultrathin molybdenum disulfide (MoS(2)) have recently been experimentally demonstrated, which show promising potential for advanced electronics. However, large variations like hysteresis, presumably due to extrinsic/environmental effects, are often observed in MoS(2) devices measured under ambient environment. Here, we report the origin of their hysteretic and transient behaviors and suggest that hysteresis of MoS(2) field effect transistors is largely due to absorption of moisture on the surface and intensified by high photosensitivity of MoS(2). Uniform encapsulation of MoS(2) transistor structures with silicon nitride grown by plasma-enhanced chemical vapor deposition is effective in minimizing the hysteresis, while the device mobility is improved by over 1 order of magnitude.

  5. Enhancement of photocatalytic property on ZnS/MoS2 composite under visible light irradiation

    Directory of Open Access Journals (Sweden)

    Cheng Jiushan

    2017-01-01

    Full Text Available In this paper, the composite ZnS/MoS2 was obtained via two steps including solvothermal methods. The as-synthesized sample was characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM and UV-Vis. diffuse reflectance spectra (DRS. The photocatalytic activity of the product was evaluated through photocatalytic degradation of Rhodamine B (Rh B under UV-Vis. light irradiation; the electrical conductivity of ZnS/MoS2 composites was significantly improved compared to ZnS, MoS2, respectively. The results showed that the ZnS/MoS2 composite photocatalyst possesses better photocatalytic activity in degrading Rh B than the single ZnS or the single MoS2. The better photocatalytic properties may be due to the synergetic effect of two semiconductors, because of which electrons and holes were separated effectively. And its specific microstructure played an active role in evaluating photocatalytic performance.

  6. Asymmetrical reinforcement and Wolbachia infection in Drosophila.

    Directory of Open Access Journals (Sweden)

    John Jaenike

    2006-10-01

    Full Text Available Reinforcement refers to the evolution of increased mating discrimination against heterospecific individuals in zones of geographic overlap and can be considered a final stage in the speciation process. One the factors that may affect reinforcement is the degree to which hybrid matings result in the permanent loss of genes from a species' gene pool. Matings between females of Drosophila subquinaria and males of D. recens result in high levels of offspring mortality, due to interspecific cytoplasmic incompatibility caused by Wolbachia infection of D. recens. Such hybrid inviability is not manifested in matings between D. recens females and D. subquinaria males. Here we ask whether the asymmetrical hybrid inviability is associated with a corresponding asymmetry in the level of reinforcement. The geographic ranges of D. recens and D. subquinaria were found to overlap across a broad belt of boreal forest in central Canada. Females of D. subquinaria from the zone of sympatry exhibit much stronger levels of discrimination against males of D. recens than do females from allopatric populations. In contrast, such reproductive character displacement is not evident in D. recens, consistent with the expected effects of unidirectional cytoplasmic incompatibility. Furthermore, there is substantial behavioral isolation within D. subquinaria, because females from populations sympatric with D. recens discriminate against allopatric conspecific males, whereas females from populations allopatric with D. recens show no discrimination against any conspecific males. Patterns of general genetic differentiation among populations are not consistent with patterns of behavioral discrimination, which suggests that the behavioral isolation within D. subquinaria results from selection against mating with Wolbachia-infected D. recens. Interspecific cytoplasmic incompatibility may contribute not only to post-mating isolation, an effect already widely recognized, but also to

  7. System identification of Drosophila olfactory sensory neurons.

    Science.gov (United States)

    Kim, Anmo J; Lazar, Aurel A; Slutskiy, Yevgeniy B

    2011-02-01

    The lack of a deeper understanding of how olfactory sensory neurons (OSNs) encode odors has hindered the progress in understanding the olfactory signal processing in higher brain centers. Here we employ methods of system identification to investigate the encoding of time-varying odor stimuli and their representation for further processing in the spike domain by Drosophila OSNs. In order to apply system identification techniques, we built a novel low-turbulence odor delivery system that allowed us to deliver airborne stimuli in a precise and reproducible fashion. The system provides a 1% tolerance in stimulus reproducibility and an exact control of odor concentration and concentration gradient on a millisecond time scale. Using this novel setup, we recorded and analyzed the in-vivo response of OSNs to a wide range of time-varying odor waveforms. We report for the first time that across trials the response of OR59b OSNs is very precise and reproducible. Further, we empirically show that the response of an OSN depends not only on the concentration, but also on the rate of change of the odor concentration. Moreover, we demonstrate that a two-dimensional (2D) Encoding Manifold in a concentration-concentration gradient space provides a quantitative description of the neuron's response. We then use the white noise system identification methodology to construct one-dimensional (1D) and two-dimensional (2D) Linear-Nonlinear-Poisson (LNP) cascade models of the sensory neuron for a fixed mean odor concentration and fixed contrast. We show that in terms of predicting the intensity rate of the spike train, the 2D LNP model performs on par with the 1D LNP model, with a root mean-square error (RMSE) increase of about 5 to 10%. Surprisingly, we find that for a fixed contrast of the white noise odor waveforms, the nonlinear block of each of the two models changes with the mean input concentration. The shape of the nonlinearities of both the 1D and the 2D LNP model appears to be

  8. Impact of Layer Alignment on the Behavior of MoS2-ZrS2 Tunnel Field-Effect Transistors: An Ab Initio Study

    Science.gov (United States)

    Lu, Anh Khoa Augustin; Houssa, Michel; Luisier, Mathieu; Pourtois, Geoffrey

    2017-09-01

    Tunnel field-effect transistors based on van der Waals heterostructures are emerging device concepts for low-power applications, auguring sub -60 mV /dec subthreshold swing values. In these devices, the channel is built from a stack of several different two-dimensional materials whose nature allows tailoring the band alignments and enables a good electrostatic control of the device. In this work, we propose a theoretical study of the variability of the performances of a MoS2-ZrS2 tunnel field-effect transistor induced by fluctuations of the relative position or the orientation of the layers. Our results indicate that although a steep subthreshold slope (20 mV /dec ) is achievable, fluctuations in the relative orientation of the ZrS2 layer with respect to the MoS2 one lead to a significant variability in the tunneling current by about one decade. This arises from changes in the orbital overlap between the layers and from the modulation of the transport direction.

  9. Growth, structure and stability of sputter-deposited MoS2 thin films

    Directory of Open Access Journals (Sweden)

    Reinhard Kaindl

    2017-05-01

    Full Text Available Molybdenum disulphide (MoS2 thin films have received increasing interest as device-active layers in low-dimensional electronics and also as novel catalysts in electrochemical processes such as the hydrogen evolution reaction (HER in electrochemical water splitting. For both types of applications, industrially scalable fabrication methods with good control over the MoS2 film properties are crucial. Here, we investigate scalable physical vapour deposition (PVD of MoS2 films by magnetron sputtering. MoS2 films with thicknesses from ≈10 to ≈1000 nm were deposited on SiO2/Si and reticulated vitreous carbon (RVC substrates. Samples deposited at room temperature (RT and at 400 °C were compared. The deposited MoS2 was characterized by macro- and microscopic X-ray, electron beam and light scattering, scanning and spectroscopic methods as well as electrical device characterization. We find that room-temperature-deposited MoS2 films are amorphous, of smooth surface morphology and easily degraded upon moderate laser-induced annealing in ambient conditions. In contrast, films deposited at 400 °C are nano-crystalline, show a nano-grained surface morphology and are comparatively stable against laser-induced degradation. Interestingly, results from electrical transport measurements indicate an unexpected metallic-like conduction character of the studied PVD MoS2 films, independent of deposition temperature. Possible reasons for these unusual electrical properties of our PVD MoS2 thin films are discussed. A potential application for such conductive nanostructured MoS2 films could be as catalytically active electrodes in (photo-electrocatalysis and initial electrochemical measurements suggest directions for future work on our PVD MoS2 films.

  10. Coding and spacer sequences in the 5.8S-2S region of Sciara coprophila ribosomal DNA.

    OpenAIRE

    Jordan, B R; Latil-Damotte, M; Jourdan, R

    1980-01-01

    The sequence of 436 nucleotides around the region coding for 5.8S RNA in the Sciara coprophila rDNA transcription unit (1) has been determined. Regions coding for 5.8S and 2S RNAs have been identified; they are 80 - 90% homologous to the corresponding Drosophila sequences and are separated by a 22 nucleotide long spacer. This sequence as well as the two before the 5.8 and after the 2S coding region are very different from the corresponding Drosophila sequences. The main features reported in t...

  11. A genomic investigation of ecological differentiation between free-living and Drosophila-associated bacteria.

    Science.gov (United States)

    Winans, Nathan J; Walter, Alec; Chouaia, Bessem; Chaston, John M; Douglas, Angela E; Newell, Peter D

    2017-09-01

    Various bacterial taxa have been identified both in association with animals and in the external environment, but the extent to which related bacteria from the two habitat types are ecologically and evolutionarily distinct is largely unknown. This study investigated the scale and pattern of genetic differentiation between bacteria of the family Acetobacteraceae isolated from the guts of Drosophila fruit flies, plant material and industrial fermentations. Genome-scale analysis of the phylogenetic relationships and predicted functions was conducted on 44 Acetobacteraceae isolates, including newly sequenced genomes from 18 isolates from wild and laboratory Drosophila. Isolates from the external environment and Drosophila could not be assigned to distinct phylogenetic groups, nor are their genomes enriched for any different sets of genes or category of predicted gene functions. In contrast, analysis of bacteria from laboratory Drosophila showed they were genetically distinct in their universal capacity to degrade uric acid (a major nitrogenous waste product of Drosophila) and absence of flagellar motility, while these traits vary among wild Drosophila isolates. Analysis of the competitive fitness of Acetobacter discordant for these traits revealed a significant fitness deficit for bacteria that cannot degrade uric acid in culture with Drosophila. We propose that, for wild populations, frequent cycling of Acetobacter between Drosophila and the external environment prevents genetic differentiation by maintaining selection for traits adaptive in both the gut and external habitats. However, laboratory isolates bear the signs of adaptation to persistent association with the Drosophila host under tightly defined environmental conditions. © 2017 John Wiley & Sons Ltd.

  12. Environmental and facility conditions promote singular gravity responses of transcriptome during Drosophila metamorphosis

    Data.gov (United States)

    National Aeronautics and Space Administration — Genome-wide transcriptional profiling showed that reducing gravity levels in the International Space Station (ISS) causes important alterations in Drosophila gene...

  13. Histamine Recycling Is Mediated by CarT, a Carcinine Transporter in Drosophila Photoreceptors

    Science.gov (United States)

    Xu, Ying; An, Futing; Borycz, Jolanta A.; Borycz, Janusz; Meinertzhagen, Ian A.; Wang, Tao

    2015-01-01

    Histamine is an important chemical messenger that regulates multiple physiological processes in both vertebrate and invertebrate animals. Even so, how glial cells and neurons recycle histamine remains to be elucidated. Drosophila photoreceptor neurons use histamine as a neurotransmitter, and the released histamine is recycled through neighboring glia, where it is conjugated to β-alanine to form carcinine. However, how carcinine is then returned to the photoreceptor remains unclear. In an mRNA-seq screen for photoreceptor cell-enriched transporters, we identified CG9317, an SLC22 transporter family protein, and named it CarT (Carcinine Transporter). S2 cells that express CarT are able to take up carcinine in vitro. In the compound eye, CarT is exclusively localized to photoreceptor terminals. Null mutations of cart alter the content of histamine and its metabolites. Moreover, null cart mutants are defective in photoreceptor synaptic transmission and lack phototaxis. These findings reveal that CarT is required for histamine recycling at histaminergic photoreceptors and provide evidence for a CarT-dependent neurotransmitter trafficking pathway between glial cells and photoreceptor terminals. PMID:26713872

  14. Doping effect on monolayer MoS2 for visible light dye degradation - A DFT study

    Science.gov (United States)

    Cheriyan, Silpa; Balamurgan, D.; Sriram, S.

    2018-04-01

    The electronic and optical properties of, Nitrogen (N), Cobalt (Co), and Co-N co-doped monolayers of MoS2 has been studied by using density functional theory (DFT) for visible light photocatalytic activity. From the calculations, it has been observed that the band gap of monolayer MoS2 has been reduced while doping. However, the band gaps of pristine and N doped MoS2 monolayers only falls in the visible region while for Co and Co-N co-doped systems, the band gap shifted to IR region. The optical calculation also confirms the results. The formation energy values of the doped system reaveal that MoS2 monolayer drops its stability while doping. To evaluate the photocatalytic response, band edge potentials of pristine and N-MoS2 are calculated, and the observed results show that compared to N-doped MoS2 monolayer, pure MoS2 is highly suitable for visible light photocatalytic dye degradation.

  15. Experimental and Theoretical Investigations on Intermediate Band in Doped Nano-SnS2

    Science.gov (United States)

    Heiba, Zein K.; Mohamed, Mohamed Bakr; Abdel Kader, M. H.

    2018-03-01

    Nano-SnS2 and Sn0.75 X 0.25S2 (X = Cr, Fe, Y) have been prepared by thermolysis method. Phase analysis of x-ray diffraction data confirmed the single-phase nature of all prepared samples, with some residual carbon contributing to the background. Rietveld refinement revealed high anisotropy in crystallite size, signifying a cylindrical structure for the particle shape, as confirmed by transmission electron microscopy. The refined occupancies obtained for the doped cations were found to be smaller than the nominal target doping ratio (25%). Fourier-transform infrared spectra showed presence of Sn-S bond in all samples. The energy was found to be 3.42 eV, 3.33 eV, 2.1 eV and 3.14 eV, and 3.62 eV for undoped SnS2 and when doped with Cr, Fe, and Y, respectively. Density functional theory calculations illustrated that Fe-doped SnS2 has two bandgaps [normal and intermediate (IB) bands]. Meanwhile, Sn0.75Fe0.25S2 sample showed anti-Stokes and an extra photoluminescence peak related to the newly created intermediate band (IB) inside the energy gap. On the other hand, pure SnS2 and Sn0.75 X 0.25S2 (X = Cr, Y) samples emitted four photoluminescence subspectra in ultraviolet, violet, and blue regions.

  16. Descripción de tres especies nuevas del género Drosophila (Diptera, Drosophilidae en el Ecuador

    Directory of Open Access Journals (Sweden)

    María Luna Figuero

    2013-09-01

    Full Text Available Se encontraron tres especies nuevas de Drosophila entre los individuos colectados en diferentes localidades del Ecuador. Una de las especies nuevas pertenecen al grupo Drosophila willistoni y otra al grupo Drosophila asiri, la tercera especie se encuentra sin agrupar. En todos los muestreos realizados se usaron trampas fabricadas con botellas de plástico agujereadas con cebo de banano y levadura. Las tres especies son: D. (Sophophora neocapnoptera sp. nov., esta especie es similar a D. capnoptera Patterson & Mainland, 1944, sin embargo presentan algunas diferencias en el ala que permiten distinguirlas. Drosophila (Drosophila neoasiri sp. nov., una especie similar a D. asiri Vela & Rafael, 2005, la diferencia más relevante entre las dos especies se observa a nivel del edeago y Drosophila (Drosophila papallacta sp. nov. que por el momento no se encuentra relacionada a ningún grupo de especies del género Drosophila.

  17. Bonding between graphene and MoS2 monolayers without and with Li intercalation

    International Nuclear Information System (INIS)

    Ahmed, Towfiq; Modine, N. A.; Zhu, Jian-Xin

    2015-01-01

    We performed density functional theory (DFT) calculations for a bi-layered heterostructure combining a graphene layer with a MoS 2 layer with and without intercalated Li atoms. Our calculations demonstrate the importance of the van der Waals (vdW) interaction, which is crucial for forming stable bonding between the layers. Our DFT calculation correctly reproduces the linear dispersion, or Dirac cone, feature at the Fermi energy for the isolated graphene monolayer and the band gap for the MoS 2 monolayer. For the combined graphene/MoS 2 bi-layer, we observe interesting electronic structure and density of states (DOS) characteristics near the Fermi energy, showing both the gap like features of the MoS 2 layer and in-gap states with linear dispersion contributed mostly by the graphene layer. Our calculated total DOS in this vdW heterostructure reveals that the graphene layer significantly contributes to pinning the Fermi energy at the center of the band gap of MoS 2 . We also find that intercalating Li ions in between the layers of the graphene/MoS 2 heterostructure enhances the binding energy through orbital hybridizations between cations (Li adatoms) and anions (graphene and MoS 2 monolayers). Moreover, we calculate the dielectric function of the Li intercalated graphene/MoS 2 heterostructure, the imaginary component of which can be directly compared with experimental measurements of optical conductivity in order to validate our theoretical prediction. We observe sharp features in the imaginary component of the dielectric function, which shows the presence of a Drude peak in the optical conductivity, and therefore metallicity in the lithiated graphene/MoS 2 heterostructure

  18. Functional regulation of Pb-Ti/MoS2 composite coatings for environmentally adaptive solid lubrication

    Science.gov (United States)

    Ren, Siming; Li, Hao; Cui, Mingjun; Wang, Liping; Pu, Jibin

    2017-04-01

    The lubrication of molybdenum disulfide coatings has commonly been limited by the application environments, for instance, the crystal MoS2 are easily affected by water to form MoO3 that causes a higher friction coefficient and short lifetime. Therefore, to improve the tribolgical performance of MoS2 in high humidity condition, the co-doped Pb-Ti/MoS2 composite coatings are deposited by unbalanced magnetron sputtering system. The design of the co-doping elements in MoS2-based coatings can not only maintain the characteristic of low humidity-sensitivity as the Ti/MoS2 coating but also improve the mechanical properties and tribological performance of coatings as a comparison with single-doped ones. Moreover, the ultra-low friction coefficient with a minimum value of 0.006 under the vacuum condition is achieved for Pb-Ti/MoS2 composite coating containing about 4.6 at.% Pb, depending on the densification structure of coating. Intriguingly, the wear behaviours of Pb-Ti/MoS2 composite coatings are in accordance with the variation in H/E (hardness to the elastic modulus) ratio that the coating with higher H/E exhibits lower wear rate. These results demonstrate that the lubricating properties of MoS2 coatings in both humid environment and vacuum condition can be achieved through the Pb and Ti co-doped, which is of great significant for developing MoS2 coatings as the environmentally adaptive lubricants.

  19. Kinetic response of a Drosophila melanogaster cell line to different medium formulations and culture conditions.

    Science.gov (United States)

    Bovo, R; Galesi, A L L; Jorge, S A C; Piccoli, R A M; Moraes, A M; Pereira, C A; Augusto, E F P

    2008-05-01

    In the past few years, Drosophila melanogaster cells have been employed for recombinant protein production purposes, and a comprehensive knowledge of their metabolism is essential for process optimization. In this work, the kinetic response of a Schneider S2 cell line, grown in shake flasks, in two different culture media, the serum-free SF900-II((R)) and the serum-supplemented TC-100, was evaluated. Cell growth, amino acids and glucose uptake, and lactate synthesis were measured allowing the calculation of kinetic parameters. The results show that S2 cells metabolism was able to adjust to different environmental situations, as determined by medium formulation, as well as by the particular situation resulting from the culture conditions. Cells attained a 163% higher final cell concentration (1.4 x 10(7) cells mL(-1)) in SF900 II((R)) medium, when compared to serum-supplemented TC-100 medium. Also, a maximum specific cell growth rate 52% higher in SF900 II((R) )medium, when compared to serum-supplemented TC-100 one, was observed. Glutamine was the growth limiting factor in SF900 II((R)) medium, while glucose, sometimes associated with glutamine, controlled growth in serum-supplemented TC-100 medium based formulation. The different pattern of lactate production is an example of the versatility of the metabolism of these cells. This by-product was produced only in glutamine limitation, but the amount synthesized depended not only on the excess glucose, but on other medium components. Therefore, in serum-supplemented TC-100 medium a much smaller lactate amount was generated. Besides, glucose was identified not only as a growth limiting factor, but also as a viability limiting factor, since its depletion accelerated cell death.

  20. Catalytic growth of vertically aligned SnS/SnS2 p-n heterojunctions

    Science.gov (United States)

    Degrauw, Aaron; Armstrong, Rebekka; Rahman, Ajara A.; Ogle, Jonathan; Whittaker-Brooks, Luisa

    2017-09-01

    Nanowire arrays of SnS/SnS2 p-n heterojunctions are grown on transparent indium tin oxide (ITO) coated-glass and Si/SiO2 substrates via chemical vapor transport (CVT). The nanowire arrays are comprised of individual SnS/SnS2 heterostructures that are highly oriented with their lengths and morphologies controlled by the CVT conditions (i.e. reaction temperature, flow rate, and reaction time). The growth and optoelectronic characterization of these well-defined SnS/SnS2 p-n heterostructures pave the way for the fabrication of highly efficient solar cell devices.