WorldWideScience

Sample records for conjugal gene transfer

  1. Conjugal gene transfer between bacteria in soil and rhizosphere

    NARCIS (Netherlands)

    Smit, E.

    1994-01-01

    The extent of possible conjugal transfer of recombinant DNA present in genetically engineered microorganisms (GEMs) was studied. Occurrence of transfer of recombinant DNA is only one of the concerns regarding the use of GEMs (Chapter 2). Other potential hazards preventing the application of

  2. Identification of the rctA Gene, Which Is Required for Repression of Conjugative Transfer of Rhizobial Symbiotic Megaplasmids†

    Science.gov (United States)

    Pérez-Mendoza, Daniel; Sepúlveda, Edgardo; Pando, Victoria; Muñoz, Socorro; Nogales, Joaquina; Olivares, José; Soto, Maria J.; Herrera-Cervera, José A.; Romero, David; Brom, Susana; Sanjuán, Juan

    2005-01-01

    An analysis of the conjugative transfer of pRetCFN42d, the symbiotic plasmid (pSym) of Rhizobium etli, has revealed a novel gene, rctA, as an essential element of a regulatory system for silencing the conjugative transfer of R. etli pSym by repressing the transcription of conjugal transfer genes in standard laboratory media. The rctA gene product lacks sequence conservation with other proteins of known function but may belong to the winged-helix DNA-binding subfamily of transcriptional regulators. Similar to that of many transcriptional repressors, rctA transcription seems to be positively autoregulated. rctA expression is greatly reduced upon overexpression of another gene, rctB, previously identified as a putative activator of R. etli pSym conjugal transfer. Thus, rctB seems to counteract the repressive action of rctA. rctA homologs are present in at least three other bacterial genomes within the order Rhizobiales, where they are invariably located adjacent to and divergently transcribed from putative virB-like operons. We show that similar to that of R. etli pSym, conjugative transfer of the 1.35-Mb symbiotic megaplasmid A of Sinorhizobium meliloti is also subjected to the inhibitory action of rctA. Our data provide strong evidence that the R. etli and S. meliloti pSym plasmids are indeed self-conjugative plasmids and that this property would only be expressed under optimal, as yet unknown conditions that entail inactivation of the rctA function. The rctA gene seems to represent novel but probably widespread regulatory systems controlling the transfer of conjugative elements within the order Rhizobiales. PMID:16237017

  3. Plasmid transfer by conjugation in Xylella fastidiosa.

    Science.gov (United States)

    Recombination and horizontal gene transfer have been implicated in the adaption of Xylella fastidiosa (Xf) to infect a wide variety of different plant species. There is evidence that certain strains of Xf carry native plasmids equipped with transfer and mobilization genes, suggesting conjugation as ...

  4. Plasmid transfer by conjugation as a possible route of horizontal gene transfer and recombination in Xylella fastidiosa

    Science.gov (United States)

    Horizontal gene transfer is an important component of evolution and adaptation of bacterial species. Xylella fastidiosa has the ability to incorporate exogenous DNA into its genome by homologous recombination at relatively high rates. This genetic recombination is believed to play a role in adaptati...

  5. Intergenic and intragenic conjugal transfer of multiple antibiotic ...

    African Journals Online (AJOL)

    Conjugation process was conducted to determine the means of transferring ... In this study, it was surprisingly observed that tetracycline resistant gene was ... among pathogenic bacteria, particularly since antibiotics are indiscriminately used in ...

  6. Theory of periodic conjugate heat transfer

    CERN Document Server

    Zudin, Yuri B

    2016-01-01

    This book presents the theory of periodic conjugate heat transfer in detail. It offers a simplified description of the interaction between a solid body and a fluid as a boundary value problem of the heat conduction equation for the solid body.

  7. Conjugate problems in convective heat transfer

    CERN Document Server

    Dorfman, Abram S

    2009-01-01

    The conjugate heat transfer (CHT) problem takes into account the thermal interaction between a body and fluid flowing over or through it, a key consideration in both mechanical and aerospace engineering. Presenting more than 100 solutions of non-isothermal and CHT problems, this title considers the approximate solutions of CHT problems.

  8. Conjugate Problems in Convective Heat Transfer: Review

    Directory of Open Access Journals (Sweden)

    Abram Dorfman

    2009-01-01

    Full Text Available A review of conjugate convective heat transfer problems solved during the early and current time of development of this modern approach is presented. The discussion is based on analytical solutions of selected typical relatively simple conjugate problems including steady-state and transient processes, thermal material treatment, and heat and mass transfer in drying. This brief survey is accompanied by the list of almost two hundred publications considering application of different more and less complex analytical and numerical conjugate models for simulating technology processes and industrial devices from aerospace systems to food production. The references are combined in the groups of works studying similar problems so that each of the groups corresponds to one of selected analytical solutions considered in detail. Such structure of review gives the reader the understanding of early and current situation in conjugate convective heat transfer modeling and makes possible to use the information presented as an introduction to this area on the one hand, and to find more complicated publications of interest on the other hand.

  9. Conjugative Plasmid Transfer in Xylella fastidiosa Is Dependent on tra and trb Operon Functions

    OpenAIRE

    Burbank, Lindsey P.; Van Horn, Christopher R.

    2017-01-01

    The insect-transmitted plant pathogen Xylella fastidiosa is capable of efficient horizontal gene transfer (HGT) and recombination. Natural transformation occurs at high rates in X. fastidiosa, but there also is evidence that certain strains of X. fastidiosa carry native plasmids equipped with transfer and mobilization genes, suggesting conjugation as an additional mechanism of HGT in some instances. Two operons, tra and trb, putatively encoding a conjugative type IV secretion system, are foun...

  10. Conjugate Heat Transfer Study in Hypersonic Flows

    Science.gov (United States)

    Sahoo, Niranjan; Kulkarni, Vinayak; Peetala, Ravi Kumar

    2018-04-01

    Coupled and decoupled conjugate heat transfer (CHT) studies are carried out to imitate experimental studies for heat transfer measurement in hypersonic flow regime. The finite volume based solvers are used for analyzing the heat interaction between fluid and solid domains. Temperature and surface heat flux signals are predicted by both coupled and decoupled CHT analysis techniques for hypersonic Mach numbers. These two methodologies are also used to study the effect of different wall materials on surface parameters. Effectiveness of these CHT solvers has been verified for the inverse problem of wall heat flux recovery using various techniques reported in the literature. Both coupled and decoupled CHT techniques are seen to be equally useful for prediction of local temperature and heat flux signals prior to the experiments in hypersonic flows.

  11. Double diffusive conjugate heat transfer: Part I

    Science.gov (United States)

    Azeem, Soudagar, Manzoor Elahi M.

    2018-05-01

    The present work is undertaken to investigate the effect of solid wall being placed at left of square cavity filled with porous medium. The presence of a solid wall in the porous medium turns the situation into a conjugate heat transfer problem. The boundary conditions are such that the left vertical surface is maintained at highest temperature and concentration whereas right vertical surface at lowest temperature and concentration in the medium. The top and bottom surfaces are adiabatic. The additional conduction equation along with the regular momentum and energy equations of porous medium are solved in an iterative manner with the help of finite element method. It is seen that the heat and mass transfer rate is lesser due to smaller thermal and concentration gradients.

  12. Theory of Periodic Conjugate Heat Transfer

    CERN Document Server

    Zudin, Yuri B

    2012-01-01

    This book presents the theory of periodic conjugate heat transfer in a detailed way. The effects of thermophysical properties and geometry of a solid body on the commonly used and experimentally determined heat transfer coefficient are analytically presented from a general point of view. The main objective of the book is a simplified description of the interaction between a solid body and a fluid as a boundary value problem of the heat conduction equation for the solid body. At the body surface, the true heat transfer coefficient is composed of two parts: the true mean value resulting from the solution of the steady state heat transfer problem and a periodically variable part, the periodic time and length to describe the oscillatory hydrodynamic effects. The second edition is extended by (i) the analysis of stability boundaries in helium flow at supercritical conditions in a heated channel with respect to the interaction between a solid body and a fluid; (ii) a periodic model and a method of heat transfer sim...

  13. Effects of phosphorylatable short peptide-conjugated chitosan-mediated IL-1Ra and igf-1 gene transfer on articular cartilage defects in rabbits.

    Directory of Open Access Journals (Sweden)

    Ronglan Zhao

    Full Text Available Previously, we reported an improvement in the transfection efficiency of the plasmid DNA-chitosan (pDNA/CS complex by the utilization of phosphorylatable short peptide-conjugated chitosan (pSP-CS. In this study, we investigated the effects of pSP-CS-mediated gene transfection of interleukin-1 receptor antagonist protein (IL-1Ra combined with insulin-like growth factor-1 (IGF-1 in rabbit chondrocytes and in a rabbit model of cartilage defects. pBudCE4.1-IL-1Ra+igf-1, pBudCE4.1-IL-1Ra and pBudCE4.1-igf-1 were constructed and combined with pSP-CS to form pDNA/pSP-CS complexes. These complexes were transfected into rabbit primary chondrocytes or injected into the joint cavity. Seven weeks after treatment, all rabbits were sacrificed and analyzed. High levels of IL-1Ra and igf-1 expression were detected both in the cell culture supernatant and in the synovial fluid. In vitro, the transgenic complexes caused significant proliferation of chondrocytes, promotion of glycosaminoglycan (GAG and collagen II synthesis, and inhibition of chondrocyte apoptosis and nitric oxide (NO synthesis. In vivo, the exogenous genes resulted in increased collagen II synthesis and reduced NO and GAG concentrations in the synovial fluid; histological studies revealed that pDNA/pSP-CS treatment resulted in varying degrees of hyaline-like cartilage repair and Mankin score decrease. The co-expression of both genes produced greater effects than each single gene alone both in vitro and in vivo. The results suggest that pSP-CS is a good candidate for use in gene therapy for the treatment of cartilage defects and that igf-1 and IL-1Ra co-expression produces promising biologic effects on cartilage defects.

  14. Conjugative Plasmid Transfer in Xylella fastidiosa Is Dependent on tra and trb Operon Functions.

    Science.gov (United States)

    Burbank, Lindsey P; Van Horn, Christopher R

    2017-11-01

    The insect-transmitted plant pathogen Xylella fastidiosa is capable of efficient horizontal gene transfer (HGT) and recombination. Natural transformation occurs at high rates in X. fastidiosa , but there also is evidence that certain strains of X. fastidiosa carry native plasmids equipped with transfer and mobilization genes, suggesting conjugation as an additional mechanism of HGT in some instances. Two operons, tra and trb , putatively encoding a conjugative type IV secretion system, are found in some but not all X. fastidiosa isolates, often on native plasmids. X. fastidiosa strains that carry the conjugative transfer genes can belong to different subspecies and frequently differ in host ranges. Using X. fastidiosa strain M23 ( X. fastidiosa subsp. fastidiosa ) or Dixon ( X. fastidiosa subsp. multiplex ) as the donor strain and Temecula ( X. fastidiosa subsp. fastidiosa ) as the recipient strain, plasmid transfer was characterized using the mobilizable broad-host-range vector pBBR5pemIK. Transfer of plasmid pBBR5pemIK was observed under in vitro conditions with both donor strains and was dependent on both tra and trb operon functions. A conjugative mechanism likely contributes to gene transfer between diverse strains of X. fastidiosa , possibly facilitating adaptation to new environments or different hosts. IMPORTANCE Xylella fastidiosa is an important plant pathogen worldwide, infecting a wide range of different plant species. The emergence of new diseases caused by X. fastidiosa , or host switching of existing strains, is thought to be primarily due to the high frequency of HGT and recombination in this pathogen. Transfer of plasmids by a conjugative mechanism enables movement of larger amounts of genetic material at one time, compared with other routes of gene transfer such as natural transformation. Establishing the prevalence and functionality of this mechanism in X. fastidiosa contributes to a better understanding of HGT, adaptation, and disease emergence

  15. High-yield nontoxic gene transfer through conjugation of the CM₁₈-Tat₁₁ chimeric peptide with nanosecond electric pulses.

    Science.gov (United States)

    Salomone, Fabrizio; Breton, Marie; Leray, Isabelle; Cardarelli, Francesco; Boccardi, Claudia; Bonhenry, Daniel; Tarek, Mounir; Mir, Lluis M; Beltram, Fabio

    2014-07-07

    We report a novel nontoxic, high-yield, gene delivery system based on the synergistic use of nanosecond electric pulses (NPs) and nanomolar doses of the recently introduced CM18-Tat11 chimeric peptide (sequence of KWKLFKKIGAVLKVLTTGYGRKKRRQRRR, residues 1-7 of cecropin-A, 2-12 of melittin, and 47-57 of HIV-1 Tat protein). This combined use makes it possible to drastically reduce the required CM18-Tat11 concentration and confines stable nanopore formation to vesicle membranes followed by DNA release, while no detectable perturbation of the plasma membrane is observed. Two different experimental assays are exploited to quantitatively evaluate the details of NPs and CM18-Tat11 cooperation: (i) cytofluorimetric analysis of the integrity of synthetic 1,2-dioleoyl-sn-glycero-3-phosphocholine giant unilamellar vesicles exposed to CM18-Tat11 and NPs and (ii) the in vitro transfection efficiency of a green fluorescent protein-encoding plasmid conjugated to CM18-Tat11 in the presence of NPs. Data support a model in which NPs induce membrane perturbation in the form of transient pores on all cellular membranes, while the peptide stabilizes membrane defects selectively within endosomes. Interestingly, atomistic molecular dynamics simulations show that the latter activity can be specifically attributed to the CM18 module, while Tat11 remains essential for cargo binding and vector subcellular localization. We argue that this result represents a paradigmatic example that can open the way to other targeted delivery protocols.

  16. Conjugal transfer of aac(6')Ie-aph(2″)Ia gene from native species and mechanism of regulation and cross resistance in Enterococcus faecalis MCC3063 by real time-PCR.

    Science.gov (United States)

    Jaimee, G; Halami, P M

    2017-09-01

    High level aminoglycoside resistance (HLAR) in the lactic acid bacteria (LAB) derived from food animals is detrimental. The aim of this study was to investigate the localization and conjugal transfer of aminoglycoside resistance genes, aac(6')Ie-aph(2″)Ia and aph(3')IIIa in different Enterococcus species. The cross resistance patterns in Enterococcus faecalis MCC3063 to clinically important aminoglycosides by real time PCR were also studied. Southern hybridization experiments revealed the presence of aac(6')Ie-aph(2 ″ )Ia and aph(3')IIIa genes conferring HLAR in high molecular weight plasmids except in Lactobacillus plantarum. The plasmid encoded bifunctional aac(6')Ie-aph(2″)Ia gene was transferable from Enterococcus avium (n = 2), E. cecorum (n = 1), E. faecalis (n = 1) and Pediococcus lolii (n = 1) species into the recipient strain; E. faecalis JH2-2 by filter mating experiments thus indicating the possible risks of gene transfer into pathogenic strains. Molecular analysis of cross resistance patterns in native isolate of E. faecalis MCC3063 carrying aac(6')Ie-aph(2″)Ia and aph(3')IIIa gene was displayed by quantification of the mRNA levels in this study. For this, the culture was induced with increasing concentrations of gentamicin, kanamycin and streptomycin (2048, 4096, 8192, 16384 μg/mL) individually. The increasing concentrations of gentamicin and kanamycin induced the expression of the aac(6')Ie-aph(2″)Ia and aph(3')IIIa resistance genes, respectively. Interestingly, it was observed that induction with streptomycin triggered a significant fold increase in the expression of the aph(3')IIIa gene which otherwise was not known to modify the aminoglycoside. This is noteworthy as streptomycin was found to confer cross resistance to structurally unrelated kanamycin. Also, expression of the aph(3')IIIa gene when induced with streptomycin, revealed that bacteria harbouring this gene will be able to overcome streptomycin bactericidal action at

  17. Blending genomes: distributive conjugal transfer in mycobacteria, a sexier form of HGT.

    Science.gov (United States)

    Gray, Todd A; Derbyshire, Keith M

    2018-04-18

    This review discusses a novel form of horizontal gene transfer (HGT) found in mycobacteria called Distributive Conjugal Transfer (DCT). While satisfying the criteria for conjugation, DCT occurs by a mechanism so distinct from oriT-mediated conjugation that it could be considered a fourth category of HGT. DCT involves the transfer of chromosomal DNA between mycobacteria and, most significantly, generates transconjugants with mosaic genomes of the parental strains. Multiple segments of donor chromosomal DNA can be co-transferred regardless of their location or the genetic selection and, as a result, the transconjugant genome contains many donor-derived segments; hence the name DCT. This distinguishing feature of DCT separates it from the other known mechanisms of HGT, which generally result in the introduction of a single, defined segment of DNA into the recipient chromosome (Fig. ). Moreover, these mosaic progeny are generated from a single conjugal event, which provides enormous capacity for rapid adaptation and evolution, again distinguishing it from the three classical modes of HGT. Unsurprisingly, the unusual mosaic products of DCT are generated by a conjugal mechanism that is also unusual. Here, we will describe the unique features of DCT and contrast those to other mechanisms of HGT, both from a mechanistic and an evolutionary perspective. Our focus will be on transfer of chromosomal DNA, as opposed to plasmid mobilization, because DCT mediates transfer of chromosomal DNA and is a chromosomally encoded process. © 2018 John Wiley & Sons Ltd.

  18. Conjugate Image Theory Applied on Capacitive Wireless Power Transfer

    OpenAIRE

    Ben Minnaert; Nobby Stevens

    2017-01-01

    Wireless power transfer using a magnetic field through inductive coupling is steadily entering the market in a broad range of applications. However, for certain applications, capacitive wireless power transfer using electric coupling might be preferable. In order to obtain a maximum power transfer efficiency, an optimal compensation network must be designed at the input and output ports of the capacitive wireless link. In this work, the conjugate image theory is applied to determine this opti...

  19. Conjugate heat and mass transfer in heat mass exchanger ducts

    CERN Document Server

    Zhang, Li-Zhi

    2013-01-01

    Conjugate Heat and Mass Transfer in Heat Mass Exchanger Ducts bridges the gap between fundamentals and recent discoveries, making it a valuable tool for anyone looking to expand their knowledge of heat exchangers. The first book on the market to cover conjugate heat and mass transfer in heat exchangers, author Li-Zhi Zhang goes beyond the basics to cover recent advancements in equipment for energy use and environmental control (such as heat and moisture recovery ventilators, hollow fiber membrane modules for humidification/dehumidification, membrane modules for air purification, desi

  20. Numerical Modeling of Conjugate Heat Transfer in Fluid Network

    Science.gov (United States)

    Majumdar, Alok

    2004-01-01

    Fluid network modeling with conjugate heat transfer has many applications in Aerospace engineering. In modeling unsteady flow with heat transfer, it is important to know the variation of wall temperature in time and space to calculate heat transfer between solid to fluid. Since wall temperature is a function of flow, a coupled analysis of temperature of solid and fluid is necessary. In cryogenic applications, modeling of conjugate heat transfer is of great importance to correctly predict boil-off rate in propellant tanks and chill down of transfer lines. In TFAWS 2003, the present author delivered a paper to describe a general-purpose computer program, GFSSP (Generalized Fluid System Simulation Program). GFSSP calculates flow distribution in complex flow circuit for compressible/incompressible, with or without heat transfer or phase change in all real fluids or mixtures. The flow circuit constitutes of fluid nodes and branches. The mass, energy and specie conservation equations are solved at the nodes where as momentum conservation equations are solved at the branches. The proposed paper describes the extension of GFSSP to model conjugate heat transfer. The network also includes solid nodes and conductors in addition to fluid nodes and branches. The energy conservation equations for solid nodes solves to determine the temperatures of the solid nodes simultaneously with all conservation equations governing fluid flow. The numerical scheme accounts for conduction, convection and radiation heat transfer. The paper will also describe the applications of the code to predict chill down of cryogenic transfer line and boil-off rate of cryogenic propellant storage tank.

  1. Conjugate Compressible Fluid Flow and Heat Transfer in Ducts

    Science.gov (United States)

    Cross, M. F.

    2011-01-01

    A computational approach to modeling transient, compressible fluid flow with heat transfer in long, narrow ducts is presented. The primary application of the model is for analyzing fluid flow and heat transfer in solid propellant rocket motor nozzle joints during motor start-up, but the approach is relevant to a wide range of analyses involving rapid pressurization and filling of ducts. Fluid flow is modeled through solution of the spatially one-dimensional, transient Euler equations. Source terms are included in the governing equations to account for the effects of wall friction and heat transfer. The equation solver is fully-implicit, thus providing greater flexibility than an explicit solver. This approach allows for resolution of pressure wave effects on the flow as well as for fast calculation of the steady-state solution when a quasi-steady approach is sufficient. Solution of the one-dimensional Euler equations with source terms significantly reduces computational run times compared to general purpose computational fluid dynamics packages solving the Navier-Stokes equations with resolved boundary layers. In addition, conjugate heat transfer is more readily implemented using the approach described in this paper than with most general purpose computational fluid dynamics packages. The compressible flow code has been integrated with a transient heat transfer solver to analyze heat transfer between the fluid and surrounding structure. Conjugate fluid flow and heat transfer solutions are presented. The author is unaware of any previous work available in the open literature which uses the same approach described in this paper.

  2. Quorum-Dependent Mannopine-Inducible Conjugative Transfer of an Agrobacterium Opine-Catabolic Plasmid

    Science.gov (United States)

    Wetzel, Margaret E.; Kim, Kun-Soo; Miller, Marilyn; Olsen, Gary J.

    2014-01-01

    The Ti plasmid in Agrobacterium tumefaciens strain 15955 carries two alleles of traR that regulate conjugative transfer. The first is a functional allele, called traR, that is transcriptionally induced by the opine octopine. The second, trlR, is a nonfunctional, dominant-negative mutant located in an operon that is inducible by the opine mannopine (MOP). Based on these findings, we predicted that there exist wild-type agrobacterial strains harboring plasmids in which MOP induces a functional traR and, hence, conjugation. We analyzed 11 MOP-utilizing field isolates and found five where MOP induced transfer of the MOP-catabolic element and increased production of the acyl-homoserine lactone (acyl-HSL) quormone. The transmissible elements in these five strains represent a set of highly related plasmids. Sequence analysis of one such plasmid, pAoF64/95, revealed that the 176-kb element is not a Ti plasmid but carries genes for catabolism of MOP, mannopinic acid (MOA), agropinic acid (AGA), and the agrocinopines. The plasmid additionally carries all of the genes required for conjugative transfer, including the regulatory genes traR, traI, and traM. The traR gene, however, is not located in the MOP catabolism region. The gene, instead, is monocistronic and located within the tra-trb-rep gene cluster. A traR mutant failed to transfer the plasmid and produced little to no quormone even when grown with MOP, indicating that TraRpAoF64/95 is the activator of the tra regulon. A traM mutant was constitutive for transfer and acyl-HSL production, indicating that the anti-activator function of TraM is conserved. PMID:24363349

  3. Material Selection for Microchannel Heatsink: Conjugate Heat Transfer Simulation

    Science.gov (United States)

    Uday Kumar, A.; Javed, Arshad; Dubey, Satish K.

    2018-04-01

    Heat dissipation during the operation of electronic devices causes rise in temperature, which demands an effective thermal management for their performance, life and reliability. Single phase liquid cooling in microchannels is an effective and proven technology for electronics cooling. However, due to the ongoing trends of miniaturization and developments in the microelectronics technology, the future needs of heat flux dissipation rate are expected to rise to 1 kW/cm2. Air cooled systems are unable to meet this demand. Hence, liquid cooled heatsinks are preferred. This paper presents conjugate heat transfer simulation of single phase flow in microchannels with application to electronic cooling. The numerical model is simulated for different materials: copper, aluminium and silicon as solid and water as liquid coolant. The performances of microchannel heatsink are analysed for mass flow rate range of 20-40 ml/min. The investigation has been carried out on same size of electronic chip and heat flux in order to have comparative study of different materials. This paper is divided into two sections: fabrication techniques and numerical simulation for different materials. In the first part, a brief discussion of fabrication techniques of microchannel heatsink have been presented. The second section presents conjugate heat transfer simulation and parametric investigation for different material microchannel heatsink. The presented study and findings are useful for selection of materials for microchannel heatsink.

  4. Conjugate Image Theory Applied on Capacitive Wireless Power Transfer

    Directory of Open Access Journals (Sweden)

    Ben Minnaert

    2017-01-01

    Full Text Available Wireless power transfer using a magnetic field through inductive coupling is steadily entering the market in a broad range of applications. However, for certain applications, capacitive wireless power transfer using electric coupling might be preferable. In order to obtain a maximum power transfer efficiency, an optimal compensation network must be designed at the input and output ports of the capacitive wireless link. In this work, the conjugate image theory is applied to determine this optimal network as a function of the characteristics of the capacitive wireless link, as well for the series as for the parallel topology. The results are compared with the inductive power transfer system. Introduction of a new concept, the coupling function, enables the description of the compensation network of both an inductive and a capacitive system in two elegant equations, valid for the series and the parallel topology. This approach allows better understanding of the fundamentals of the wireless power transfer link, necessary for the design of an efficient system.

  5. Interplay of a non-conjugative integrative element and a conjugative plasmid in the spread of antibiotic resistance via suicidal plasmid transfer from an aquaculture Vibrio isolate.

    Science.gov (United States)

    Nonaka, Lisa; Yamamoto, Tatsuya; Maruyama, Fumito; Hirose, Yuu; Onishi, Yuki; Kobayashi, Takeshi; Suzuki, Satoru; Nomura, Nobuhiko; Masuda, Michiaki; Yano, Hirokazu

    2018-01-01

    The capture of antimicrobial resistance genes (ARGs) by mobile genetic elements (MGEs) plays a critical role in resistance acquisition for human-associated bacteria. Although aquaculture environments are recognized as important reservoirs of ARGs, intra- and intercellular mobility of MGEs discovered in marine organisms is poorly characterized. Here, we show a new pattern of interspecies ARGs transfer involving a 'non-conjugative' integrative element. To identify active MGEs in a Vibrio ponticus isolate, we conducted whole-genome sequencing of a transconjugant obtained by mating between Escherichia coli and Vibrio ponticus. This revealed integration of a plasmid (designated pSEA1) into the chromosome, consisting of a self-transmissible plasmid backbone of the MOBH group, ARGs, and a 13.8-kb integrative element Tn6283. Molecular genetics analysis suggested a two-step gene transfer model. First, Tn6283 integrates into the recipient chromosome during suicidal plasmid transfer, followed by homologous recombination between the Tn6283 copy in the chromosome and that in the newly transferred pSEA1. Tn6283 is unusual among integrative elements in that it apparently does not encode transfer function and its excision barely generates unoccupied donor sites. Thus, its movement is analogous to the transposition of insertion sequences rather than to that of canonical integrative and conjugative elements. Overall, this study reveals the presence of a previously unrecognized type of MGE in a marine organism, highlighting diversity in the mode of interspecies gene transfer.

  6. Comparisons of Salmonella conjugation and virulence gene hyperexpression mediated by rumen protozoa from domestic and exotic ruminants.

    Science.gov (United States)

    Brewer, Matt T; Xiong, Nalee; Dier, Jeffery D; Anderson, Kristi L; Rasmussen, Mark A; Franklin, Sharon K; Carlson, Steve A

    2011-08-05

    Recent studies have identified a phenomenon in which ciliated protozoa engulf Salmonella and the intra-protozoal environment hyperactivates virulence gene expression and provides a venue for conjugal transfer of antibiotic resistance plasmids. The former observation is relegated to Salmonella bearing the SGI1 multiresistance integron while the latter phenomenon appears to be a more generalized event for recipient Salmonella. Our previous studies have assessed virulence gene hyperexpression only with protozoa from the bovine rumen while conjugal transfer has been demonstrated in rumen protozoa from cattle and goats. The present study examined virulence gene hyperexpression for Salmonella exposed to rumen protozoa obtained from cattle, sheep, goats, or two African ruminants (giraffe and bongo). Conjugal transfer was also assessed in these protozoa using Salmonella as the recipient. Virulence gene hyperexpression was only observed following exposure to the rumen protozoa from cattle and sheep while elevated virulence was also observed in these animals. Conjugal transfer events were, however, observed in all protozoa evaluated. It therefore appears that the protozoa-based hypervirulence is not universal to all ruminants while conjugal transfer is more ubiquitous. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. A study on the role that quorum sensing play in antibiotic-resistant plasmid conjugative transfer in Escherichia coli.

    Science.gov (United States)

    Zhang, Yueheng; Ma, Qingping; Su, Bingmei; Chen, Rui; Lin, Juan; Lin, Zhifen; Wang, Dali; Yu, Yang

    2018-03-01

    Horizontal genes transfer (HGT) plays an important role in the dissemination of antibiotic resistance genes (ARGs) in the environment. However, the mechanisms of HGT of ARGs under the influence of antibiotics in sub-MIC remain rarely explored. Moreover, given its collective nature, HGT was considered to be relative to quorum sensing (QS) system. To investigate whether QS has any impact on horizontal gene transfer of ARGs, experiments were conducted to determine the conjugative efficiency of plasmid RP4 on Escherichia coli (E.coli) under the influences of tetracyclines (TCs), quorum sensing autoinducers (AIs) and quorum sensing inhibitors (QSIs). The results indicated that the sub-MIC TCs could facilitate the conjugative transfer of RP4, a process which could be enhanced by AIs but inhibited by QSIs. This study demonstrated the roles that QS played in the dissemination of ARGs, and provided theoretical insights into the mechanism of HGT of ARGs in the environment.

  8. Horizontal Gene Transfers in Mycoplasmas (Mollicutes).

    Science.gov (United States)

    Citti, C; Dordet-Frisoni, E; Nouvel, L X; Kuo, C H; Baranowski, E

    2018-04-12

    The class Mollicutes (trivial name "mycoplasma") is composed of wall-less bacteria with reduced genomes whose evolution was long thought to be only driven by gene losses. Recent evidences of massive horizontal gene transfer (HGT) within and across species provided a new frame to understand the successful adaptation of these minimal bacteria to a broad range of hosts. Mobile genetic elements are being identified in a growing number of mycoplasma species, but integrative and conjugative elements (ICEs) are emerging as pivotal in HGT. While sharing common traits with other bacterial ICEs, such as their chromosomal integration and the use of a type IV secretion system to mediate horizontal dissemination, mycoplasma ICEs (MICEs) revealed unique features: their chromosomal integration is totally random and driven by a DDE recombinase related to the Mutator-like superfamily. Mycoplasma conjugation is not restricted to ICE transmission, but also involves the transfer of large chromosomal fragments that generates progenies with mosaic genomes, nearly every position of chromosome being mobile. Mycoplasmas have thus developed efficient ways to gain access to a considerable reservoir of genetic resources distributed among a vast number of species expanding the concept of minimal cell to the broader context of flowing information.

  9. Radiopharmaceuticals to monitor gene transfer

    International Nuclear Information System (INIS)

    Wiebe, L. I.; Morin, K. W.; Knaus, E. E.

    1997-01-01

    Advances in genetic engineering and molecular biology have opened the door to disease treatment by transferring genes to cells that are responsible for the pathological condition being addressed. These genes can serve to supplement or introduce the function of indigenous genes that are either inadequately expressed or that are congenitally absent in the patient. They can introduce new functions such as drug sensitization to provide a unique therapeutic target. Gene transfer is readily monitored in vitro using a range of histochemical and biochemical tests that are ''built in'' to the therapeutic gene cassette. In vivo, in situ monitoring of the gene transfer and gene expression processes can be achieved with these tests only if biopsy is possible. Scintigraphic imaging can offer unique information on both the extent and location of gene expression, provided that an appropriate reporter gene is included in the therapeutic cassette. This overview includes a brief orientation to gene transfer therapy and is followed by a review of current approaches to gene therapy imaging. The concluding section deals with imaging based on radiolabelled nucleoside substrates for herpes simplex type-1 thymidine kinase, with emphasis on IVFRU, a stable potent and selective HSV-1 TK substrate developed in their laboratories

  10. Dynamic impedance compensation for wireless power transfer using conjugate power

    Science.gov (United States)

    Liu, Suqi; Tan, Jianping; Wen, Xue

    2018-02-01

    Wireless power transfer (WPT) via coupled magnetic resonances has been in development for over a decade. However, the frequency splitting phenomenon occurs in the over-coupled region. Thus, the output power of the two-coil system achieves the maximum output power at the two splitting angular frequencies, and not at the natural resonant angular frequency. According to the maximum power transfer theorem, the impedance compensation method was adopted in many WPT projects. However, it remains a challenge to achieve the maximum output power and transmission efficiency in a fixed-frequency mode. In this study, dynamic impedance compensation for WPT was presented by utilizing the compensator within a virtual three-coil WPT system. First, the circuit model was established and transfer characteristics of a system were studied by utilizing circuit theories. Second, the power superposition of the WPT system was carefully researched. When a pair of compensating coils was inserted into the transmitter loop, the conjugate power of the compensator loop was created via magnetic coupling of the two compensating coils that insert into the transmitter loop. The mechanism for dynamic impedance compensation for wireless power transfer was then provided by investigating a virtual three-coil WPT system. Finally, the experimental circuit of a virtual three-coil WPT system was designed, and experimental results are consistent with the theoretical analysis, which achieves the maximum output power and transmission efficiency.

  11. Dynamic impedance compensation for wireless power transfer using conjugate power

    Directory of Open Access Journals (Sweden)

    Suqi Liu

    2018-02-01

    Full Text Available Wireless power transfer (WPT via coupled magnetic resonances has been in development for over a decade. However, the frequency splitting phenomenon occurs in the over-coupled region. Thus, the output power of the two-coil system achieves the maximum output power at the two splitting angular frequencies, and not at the natural resonant angular frequency. According to the maximum power transfer theorem, the impedance compensation method was adopted in many WPT projects. However, it remains a challenge to achieve the maximum output power and transmission efficiency in a fixed-frequency mode. In this study, dynamic impedance compensation for WPT was presented by utilizing the compensator within a virtual three-coil WPT system. First, the circuit model was established and transfer characteristics of a system were studied by utilizing circuit theories. Second, the power superposition of the WPT system was carefully researched. When a pair of compensating coils was inserted into the transmitter loop, the conjugate power of the compensator loop was created via magnetic coupling of the two compensating coils that insert into the transmitter loop. The mechanism for dynamic impedance compensation for wireless power transfer was then provided by investigating a virtual three-coil WPT system. Finally, the experimental circuit of a virtual three-coil WPT system was designed, and experimental results are consistent with the theoretical analysis, which achieves the maximum output power and transmission efficiency.

  12. Effects of Metals on Antibiotic Resistance and Conjugal Plasmid Transfer in Soil Bacterial Communities

    DEFF Research Database (Denmark)

    Song, Jianxiao

    Antibiotic resistance currently represents one of the biggest challenges for human health and in recent years the environmental dimension of antibiotic resistance has been increasingly recognized. The soil environment serves as an important reservoir of antibiotic resistance determinants. In addi...... adaptation to metal stress did not significantly increase the permissiveness of the soil bacterial community towards conjugal plasmid transfer........ In addition to direct selection of antibiotic resistance by antibiotics, metals may co-select for antibiotic resistance via different mechanisms causing environmental selection of antibiotic resistance in metal contaminated soils. Horizontal gene transfer of mobile genetic elements (MGEs) like plasmids...... is generally considered one of the most important co-selection mechanisms as multiple resistance genes can be located on the same MGE. This PhD thesis focused on the impact of metals (Cu and Zn) on the development of antibiotic resistance in bacterial communities in soils exposed to different degrees...

  13. TOL plasmid transfer during bacterial conjugation in vitro and rhizoremediation of oil compounds in vivo

    International Nuclear Information System (INIS)

    Jussila, Minna M.; Zhao, Ji; Suominen, Leena; Lindstroem, Kristina

    2007-01-01

    Molecular profiling methods for horizontal transfer of aromatics-degrading plasmids were developed and applied during rhizoremediation in vivo and conjugations in vitro. pWW0 was conjugated from Pseudomonas to Rhizobium. The xylE gene was detected both in Rhizobium galegae bv. officinalis and bv. orientalis, but it was neither stably maintained in orientalis nor functional in officinalis. TOL plasmids were a major group of catabolic plasmids among the bacterial strains isolated from the oil-contaminated rhizosphere of Galega orientalis. A new finding was that some Pseudomonas migulae and Pseudomonas oryzihabitans strains harbored a TOL plasmid with both pWW0- and pDK1-type xylE gene. P. oryzihabitans 29 had received the archetypal TOL plasmid pWW0 from Pseudomonas putida PaW85. As an application for environmental biotechnology, the biodegradation potential of oil-polluted soil and the success of bioremediation could be estimated by monitoring changes not only in the type and amount but also in transfer of degradation plasmids. - Horizontal transfer of degradation plasmids in the oil-contaminated rhizosphere reveals the dynamic nature of the intrinsic biodegradation potential

  14. Polyhedral meshing in numerical analysis of conjugate heat transfer

    Science.gov (United States)

    Sosnowski, Marcin; Krzywanski, Jaroslaw; Grabowska, Karolina; Gnatowska, Renata

    2018-06-01

    Computational methods have been widely applied in conjugate heat transfer analysis. The very first and crucial step in such research is the meshing process which consists in dividing the analysed geometry into numerous small control volumes (cells). In Computational Fluid Dynamics (CFD) applications it is desirable to use the hexahedral cells as the resulting mesh is characterized by low numerical diffusion. Unfortunately generating such mesh can be a very time-consuming task and in case of complicated geometry - it may not be possible to generate cells of good quality. Therefore tetrahedral cells have been implemented into commercial pre-processors. Their advantage is the ease of its generation even in case of very complex geometry. On the other hand tetrahedrons cannot be stretched excessively without decreasing the mesh quality factor, so significantly larger number of cells has to be used in comparison to hexahedral mesh in order to achieve a reasonable accuracy. Moreover the numerical diffusion of tetrahedral elements is significantly higher. Therefore the polyhedral cells are proposed within the paper in order to combine the advantages of hexahedrons (low numerical diffusion resulting in accurate solution) and tetrahedrons (rapid semi-automatic generation) as well as to overcome the disadvantages of both the above mentioned mesh types. The major benefit of polyhedral mesh is that each individual cell has many neighbours, so gradients can be well approximated. Polyhedrons are also less sensitive to stretching than tetrahedrons which results in better mesh quality leading to improved numerical stability of the model. In addition, numerical diffusion is reduced due to mass exchange over numerous faces. This leads to a more accurate solution achieved with a lower cell count. Therefore detailed comparison of numerical modelling results concerning conjugate heat transfer using tetrahedral and polyhedral meshes is presented in the paper.

  15. Conjugate heat transfer simulations of advanced research reactor fuel

    Energy Technology Data Exchange (ETDEWEB)

    Piro, M.H.A., E-mail: pirom@aecl.ca; Leitch, B.W.

    2014-07-01

    Highlights: • Temperature predictions are enhanced by coupling heat transfer in solid and fluid zones. • Seven different cases are considered to observe trends in predicted temperature and pressure. • The seven cases consider high/medium/low power, flow, burnup, fuel material and geometry. • Simulations provide temperature predictions for performance/safety. Boiling is unlikely. • Simulations demonstrate that a candidate geometry can enhance performance/safety. - Abstract: The current work presents numerical simulations of coupled fluid flow and heat transfer of advanced U–Mo/Al and U–Mo/Mg research reactor fuels in support of performance and safety analyses. The objective of this study is to enhance predictions of the flow regime and fuel temperatures through high fidelity simulations that better capture various heat transfer pathways and with a more realistic geometric representation of the fuel assembly in comparison to previous efforts. Specifically, thermal conduction, convection and radiation mechanisms are conjugated between the solid and fluid regions. Also, a complete fuel element assembly is represented in three dimensional space, permitting fluid flow and heat transfer to be simulated across the entire domain. Seven case studies are examined that vary the coolant inlet conditions, specific power, and burnup to investigate the predicted changes in the pressure drop in the coolant and the fuel, clad and coolant temperatures. In addition, an alternate fuel geometry is considered with helical fins (replacing straight fins in the existing design) to investigate the relative changes in predicted fluid and solid temperatures. Numerical simulations predict that the clad temperature is sensitive to changes in the thermal boundary layer in the coolant, particularly in simultaneously developing flow regions, while the temperature in the fuel is anticipated to be unaffected. Finally, heat transfer between fluid and solid regions is enhanced with

  16. Conjugal plasmid transfer (pAM beta 1) in Lactobacillus plantarum.

    OpenAIRE

    Shrago, A W; Chassy, B M; Dobrogosz, W J

    1986-01-01

    The streptococcal plasmid pAM beta 1 (erythromycin resistance) was transferred via conjugation from Streptococcus faecalis to Lactobacillus plantarum and was transferred among L. plantarum strains. Streptococcus sanguis Challis was transformed with pAM beta 1 isolated from these transconjugants, and transformants harboring intact pAM beta 1 could conjugate the plasmid back to L. plantarum.

  17. Effect of TiO2 on conjugative transfer of RP4 plasmid

    International Nuclear Information System (INIS)

    Qian Di; Zhang Buchang; Yang Dong; Chen Zhaoli; Jin Min; Qiu Zhigang; Li Junwen

    2013-01-01

    Objective: To explore the effect and law of nano-titanium dioxide on the conjugative transfer of RP4 plasmid. Methods: Mating was conducted between Escherichia coli HB101 (RP4) and E. coli K12Rif in saline without stirring under certain conditions and the donor per recipient ratio was 1:1 constantly. The selective LB agar medium plates containing appropriate antibiotics were used to count the number of transconjugants and the conjugative transfer frequency. Results: Nano-titanium dioxide could promote the conjugative transfer of RP4. The nano-titanium dioxide concentration, bacterial concentration, mating temperature and mating time could affect the conjugative transfer of RP4. Conclusion: Nano-titanium dioxide can promote plasmid conjugal transfer in the liquid phase under certain conditions, which may pose a potential hazard to environmental and human health. (authors)

  18. An immersed-boundary method for conjugate heat transfer analysis

    Energy Technology Data Exchange (ETDEWEB)

    Song, Jeong Chul; Lee, Joon Sik [Seoul National University, Seoul (Korea, Republic of); Ahn, Joon [Kookmin University, Seoul (Korea, Republic of)

    2017-05-15

    An immersed-boundary method is proposed for the analysis of conjugate problems of convective heat transfer in conducting solids. In- side the solid body, momentum forcing is applied to set the velocity to zero. A thermal conductivity ratio and a heat capacity ratio, between the solid body and the fluid, are introduced so that the energy equation is reduced to the heat diffusion equation. At the solid fluid interface, an effective conductivity is introduced to satisfy the heat flux continuity. The effective thermal conductivity is obtained by considering the heat balance at the interface or by using a harmonic mean formulation. The method is first validated against the analytic solution to the heat transfer problem in a fully developed laminar channel flow with conducting solid walls. Then it is applied to a laminar channel flow with a heated, block-shaped obstacle to show its validity for geometry with sharp edges. Finally the validation for a curvilinear solid body is accomplished with a laminar flow through arrayed cylinders.

  19. Simplified 3d CFD flow simulation of a turbojet disc cavity with conjugate heat transfer

    CSIR Research Space (South Africa)

    Snedden, Glen C

    2003-09-01

    Full Text Available A comprehensive computational fluid dynamics (CFD) model of an actual disc cavity, complete with rotation and conjugate heat transfer, is presented. The model uses a commercially available code with geometrical accuracy including a labyrinth seal...

  20. Horizontal gene transfer between bacteria.

    Science.gov (United States)

    Heuer, Holger; Smalla, Kornelia

    2007-01-01

    Horizontal gene transfer (HGT) refers to the acquisition of foreign genes by organisms. The occurrence of HGT among bacteria in the environment is assumed to have implications in the risk assessment of genetically modified bacteria which are released into the environment. First, introduced genetic sequences from a genetically modified bacterium could be transferred to indigenous micro-organisms and alter their genome and subsequently their ecological niche. Second, the genetically modified bacterium released into the environment might capture mobile genetic elements (MGE) from indigenous micro-organisms which could extend its ecological potential. Thus, for a risk assessment it is important to understand the extent of HGT and genome plasticity of bacteria in the environment. This review summarizes the present state of knowledge on HGT between bacteria as a crucial mechanism contributing to bacterial adaptability and diversity. In view of the use of GM crops and microbes in agricultural settings, in this mini-review we focus particularly on the presence and role of MGE in soil and plant-associated bacteria and the factors affecting gene transfer.

  1. Horizontal gene transfer in chromalveolates

    Directory of Open Access Journals (Sweden)

    Bhattacharya Debashish

    2007-09-01

    Full Text Available Abstract Background Horizontal gene transfer (HGT, the non-genealogical transfer of genetic material between different organisms, is considered a potentially important mechanism of genome evolution in eukaryotes. Using phylogenomic analyses of expressed sequence tag (EST data generated from a clonal cell line of a free living dinoflagellate alga Karenia brevis, we investigated the impact of HGT on genome evolution in unicellular chromalveolate protists. Results We identified 16 proteins that have originated in chromalveolates through ancient HGTs before the divergence of the genera Karenia and Karlodinium and one protein that was derived through a more recent HGT. Detailed analysis of the phylogeny and distribution of identified proteins demonstrates that eight have resulted from independent HGTs in several eukaryotic lineages. Conclusion Recurring intra- and interdomain gene exchange provides an important source of genetic novelty not only in parasitic taxa as previously demonstrated but as we show here, also in free-living protists. Investigating the tempo and mode of evolution of horizontally transferred genes in protists will therefore advance our understanding of mechanisms of adaptation in eukaryotes.

  2. Human Intestinal Cells Modulate Conjugational Transfer of Multidrug Resistance Plasmids between Clinical Escherichia coli Isolates

    DEFF Research Database (Denmark)

    Machado, Ana Manuel; Sommer, Morten

    2014-01-01

    Bacterial conjugation in the human gut microbiota is believed to play a major role in the dissemination of antibiotic resistance genes and virulence plasmids. However, the modulation of bacterial conjugation by the human host remains poorly understood and there is a need for controlled systems...... to study this process. We established an in vitro co-culture system to study the interaction between human intestinal cells and bacteria. We show that the conjugation efficiency of a plasmid encoding an extended spectrum beta-lactamase is reduced when clinical isolates of Escherichia coli are co...... of the intestinal cells exposed to bacteria leading to a two-fold reduction in conjugation efficiency. These results show that human gut epithelial cells can modulate bacterial conjugation and may have relevance to gene exchange in the gut....

  3. Fundamental study on gene transfer utilizing magnetic force and jet injector

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, T.; Nakagami, H.; Akiyama, Y.; Nishjima, S. [Osaka University, Osaka (Japan)

    2017-03-15

    Recently, DNA vaccination is attracting attentions as a new therapeutic method for lifestyle diseases and autoimmune diseases. However, its clinical applications are limited because a safe and efficient gene transfer method has not been established yet. In this study, a new method of gene transfer was proposed which utilizes the jet injection and the magnetic transfection. The jet injection is a method to inject medical liquid by momentary high pressure without needle. The injected liquid diffuses in the bio tissue and the endocytosis is considered to be improved by the diffusion. The magnetic transfection is a method to deliver the conjugates of plasmid DNA and magnetic particles to the desired site by external magnetic field. It is expected that jet injection of the conjugates causes slight membrane disruptions and the traction of the conjugates by magnetic field induces the efficient gene transfer. In conclusion, the possibility of improvement of the gene expression by the combination of jet injection and magnetic transfection was confirmed.

  4. Fundamental study on gene transfer utilizing magnetic force and jet injector

    International Nuclear Information System (INIS)

    Hasegawa, T.; Nakagami, H.; Akiyama, Y.; Nishjima, S.

    2017-01-01

    Recently, DNA vaccination is attracting attentions as a new therapeutic method for lifestyle diseases and autoimmune diseases. However, its clinical applications are limited because a safe and efficient gene transfer method has not been established yet. In this study, a new method of gene transfer was proposed which utilizes the jet injection and the magnetic transfection. The jet injection is a method to inject medical liquid by momentary high pressure without needle. The injected liquid diffuses in the bio tissue and the endocytosis is considered to be improved by the diffusion. The magnetic transfection is a method to deliver the conjugates of plasmid DNA and magnetic particles to the desired site by external magnetic field. It is expected that jet injection of the conjugates causes slight membrane disruptions and the traction of the conjugates by magnetic field induces the efficient gene transfer. In conclusion, the possibility of improvement of the gene expression by the combination of jet injection and magnetic transfection was confirmed

  5. Gene transfer to the cerebellum.

    Science.gov (United States)

    Louboutin, Jean-Pierre; Reyes, Beverly A S; Van Bockstaele, Elisabeth J; Strayer, David S

    2010-12-01

    There are several diseases for which gene transfer therapy to the cerebellum might be practicable. In these studies, we used recombinant Tag-deleted SV40-derived vectors (rSV40s) to study gene delivery targeting the cerebellum. These vectors transduce neurons and microglia very effectively in vitro and in vivo, and so we tested them to evaluate gene transfer to the cerebellum in vivo. Using a rSV40 vector carrying human immunodeficiency virus (HIV)-Nef with a C-terminal FLAG epitope, we characterized the distribution, duration, and cell types transduced. Rats received test and control vectors by stereotaxic injection into the cerebellum. Transgene expression was assessed 1, 2, and 4 weeks later by immunostaining of serial brain sections. FLAG epitope-expressing cells were seen, at all times after vector administration, principally detected in the Purkinje cells of the cerebellum, identified as immunopositive for calbindin. Occasional microglial cells were tranduced; transgene expression was not detected in astrocytes or oligodendrocytes. No inflammatory or other reaction was detected at any time. Thus, SV40-derived vectors can deliver effective, safe, and durable transgene expression to the cerebellum.

  6. Heat loss prediction of a confined premixed jet flame using a conjugate heat transfer approach

    NARCIS (Netherlands)

    Gövert, S.; Mira, D.; Zavala-Ake, M.; Kok, J.B.W.; Vázquez, M.; Houzeaux, G.

    2017-01-01

    The presented work addresses the investigation of the heat loss of a confined turbulent jet flame in a lab-scale combustor using a conjugate-heat transfer approach and large-eddy simulation. The analysis includes the assessment of the principal mechanisms of heat transfer in this combustion chamber:

  7. Preclinical evaluation of a Haemophilus influenzae type b conjugate vaccine process intended for technology transfer.

    Science.gov (United States)

    Hamidi, Ahd; Verdijk, Pauline; Kreeftenberg, Hans

    2014-01-01

    Introduction of Haemophilus influenzae type b (Hib) vaccine in low- and middle-income countries has been limited by cost and availability of Hib conjugate vaccines for a long time. It was previously recognized by the Institute for Translational Vaccinology (Intravacc, originating from the former Vaccinology Unit of the National Institute of Public Health [RIVM] and the Netherlands Vaccine Institute [NVI]) that local production of a Hib conjugate vaccine would increase the affordability and sustainability of the vaccine and thereby help to speed up Hib introduction in these countries. A new affordable and a non-infringing production process for a Hib conjugate vaccine was developed, including relevant quality control tests, and the technology was transferred to a number of vaccine manufacturers in India, Indonesia, and China. As part of the Hib technology transfer project managed by Intravacc, a preclinical toxicity study was conducted in the Netherlands to test the safety and immunogenicity of this new Hib conjugate vaccine. The data generated by this study were used by the technology transfer partners to accelerate the clinical development of the new Hib conjugate vaccine. A repeated dose toxicity and local tolerance study in rats was performed to assess the reactogenicity and immunogenicity of a new Hib conjugate vaccine compared to a licensed vaccine. The results showed that the vaccine was well tolerated and immunogenic in rats, no major differences in both safety and immunogenicity in rats were found between the vaccine produced according to the production process developed by Intravacc and the licensed one. Rats may be useful to verify the immunogenicity of Hib conjugate vaccines and for preclinical evaluation. In general, nonclinical evaluation of the new Hib conjugate vaccine, including this proof of concept (safety and immunogenicity study in rats), made it possible for technology transfer partners, having implemented the original process with no changes

  8. Transcriptional regulation of pWW0 transfer genes in Pseudomonas putida KT2440

    DEFF Research Database (Denmark)

    Lambertsen, L.M.; Molin, Søren; Kroer, N.

    2004-01-01

    The conjugative IncP-9 plasmid pWW0 (TOL) carries transfer genes, many of whose functions can be predicted from sequence similarities to the well-studied IncW and IncP-1 plasmids, and that are clustered with the replication and maintenance genes of the plasmid core. In this study we show that the...

  9. Transferring alien genes to wheat

    International Nuclear Information System (INIS)

    Knott, D.R.

    1987-01-01

    In broad terms an alien gene can be considered to be any gene transferred to wheat from a related species. As described above by Maan (section 7D) the genus Triticum contains a broad range of species, some of which cross readily with the cultivated tetraploid (T. Turgidum L.) or hexaploid (T. aestivum L.) wheats, and others only with great difficulty. In addition, wheat will also cross with species in a number of other genera including Agropyron, Elymus, Elytrigia (=Agropyron), Haynaldia, Hordeum, and Secale (Riley and Kimber, 1966; Knobloch, 1968; Feldman and Sears, 1981). In discussing the Triticum and Aegilops spp., the classification by Kimber and Sears, section SA-I, above, will be followed. For the Agropyron and related species the classification described by Dewey (1983) will be used. To avoid confusion, in referring to the literature the designations used by the authors will be given, followed by the new designation. The wild relatives of wheat are adapted to a broad range of environments and carry a large reservoir of useful genes (Zohary et al., 1969; Kerber and Dyck, 1973; Brezhnev, 1977; Feldman and Sears, 1981; Limin and Fowler, 1981; Sharma et aI., 1981; McGuire and Dvorak, 1981). Initially they were considered to be primarily sources of disease resistance, but more recently they have been recognized as potential sources of genes for high protein, cold tolerance, salt tolerance, drought tolerance, lodging resistance, early maturity, and even yield. Extensive screening of the wild relatives of wheat needs to be done before their useful genes can be fully utilized

  10. Transferring alien genes to wheat

    Energy Technology Data Exchange (ETDEWEB)

    Knott, D. R.

    1987-07-01

    In broad terms an alien gene can be considered to be any gene transferred to wheat from a related species. As described above by Maan (section 7D) the genus Triticum contains a broad range of species, some of which cross readily with the cultivated tetraploid (T. Turgidum L.) or hexaploid (T. aestivum L.) wheats, and others only with great difficulty. In addition, wheat will also cross with species in a number of other genera including Agropyron, Elymus, Elytrigia (=Agropyron), Haynaldia, Hordeum, and Secale (Riley and Kimber, 1966; Knobloch, 1968; Feldman and Sears, 1981). In discussing the Triticum and Aegilops spp., the classification by Kimber and Sears, section SA-I, above, will be followed. For the Agropyron and related species the classification described by Dewey (1983) will be used. To avoid confusion, in referring to the literature the designations used by the authors will be given, followed by the new designation. The wild relatives of wheat are adapted to a broad range of environments and carry a large reservoir of useful genes (Zohary et al., 1969; Kerber and Dyck, 1973; Brezhnev, 1977; Feldman and Sears, 1981; Limin and Fowler, 1981; Sharma et aI., 1981; McGuire and Dvorak, 1981). Initially they were considered to be primarily sources of disease resistance, but more recently they have been recognized as potential sources of genes for high protein, cold tolerance, salt tolerance, drought tolerance, lodging resistance, early maturity, and even yield. Extensive screening of the wild relatives of wheat needs to be done before their useful genes can be fully utilized.

  11. Solving implicit multi-mesh flow and conjugate heat transfer problems with RELAP-7

    International Nuclear Information System (INIS)

    Zou, L.; Peterson, J.; Zhao, H.; Zhang, H.; Andrs, D.; Martineau, R.

    2013-01-01

    The fully implicit simulation capability of RELAP-7 to solve multi-mesh flow and conjugate heat transfer problems for reactor system safety analysis is presented. Compared to general single-mesh simulations, the reactor system safety analysis-type of code has unique challenges due to its highly simplified, interconnected, one-dimensional, and zero-dimensional flow network describing multiple physics with significantly different time and length scales. To use the Jacobian-free Newton Krylov-type of solver, preconditioning is generally required for the Krylov method. The uniqueness of the reactor safety analysis-type of code in treating the interconnected flow network and conjugate heat transfer also introduces challenges in providing preconditioning matrix. Typical flow and conjugate heat transfer problems involved in reactor safety analysis using RELAP-7, as well as the special treatment on the preconditioning matrix are presented in detail. (authors)

  12. Conjugated heat transfer in laminar flow between parallel-plates channel

    International Nuclear Information System (INIS)

    Guedes, R.O.C.; Cotta, R.M.; Brum, N.C.L.

    1989-01-01

    An analysis is made of conjugated convective-conductive heat transfer in laminar flow of a newtonian fluid between parallel-plates channel, taking into account the longitudinal conduction along the duct walls only, by neglecting the transversal temperature gradients in the solid. This extended Graetz-type problem is then analytically handled through the generalized integral transform technique, providing accurate numerical results for quantities of practical interest sucyh as bulk and wall temperatures, and Nusselt numbers. The effects of a conjugation parameter and Biot number on heat transfer behavior are then investigated. (author)

  13. PRECONDITIONED BI-CONJUGATE GRADIENT METHOD FOR RADIATIVE TRANSFER IN SPHERICAL MEDIA

    International Nuclear Information System (INIS)

    Anusha, L. S.; Nagendra, K. N.; Paletou, F.; Leger, L.

    2009-01-01

    A robust numerical method called the Preconditioned Bi-Conjugate Gradient (Pre-BiCG) method is proposed for the solution of the radiative transfer equation in spherical geometry. A variant of this method called Stabilized Preconditioned Bi-Conjugate Gradient (Pre-BiCG-STAB) is also presented. These are iterative methods based on the construction of a set of bi-orthogonal vectors. The application of the Pre-BiCG method in some benchmark tests shows that the method is quite versatile, and can handle difficult problems that may arise in astrophysical radiative transfer theory.

  14. Crystal growth of new charge-transfer salts based on π-conjugated donor molecules

    Energy Technology Data Exchange (ETDEWEB)

    Morherr, Antonia, E-mail: morherr@stud.uni-frankfurt.de [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Witt, Sebastian [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Chernenkaya, Alisa [Graduate School Materials Science in Mainz, 55128 Mainz (Germany); Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Bäcker, Jan-Peter [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Schönhense, Gerd [Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Bolte, Michael [Institut für anorganische Chemie, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Krellner, Cornelius [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany)

    2016-09-01

    New charge transfer crystals of π-conjugated, aromatic molecules (phenanthrene and picene) as donors were obtained by physical vapor transport. The melting behavior, optimization of crystal growth and the crystal structure are reported for charge transfer salts with (fluorinated) tetracyanoquinodimethane (TCNQ-F{sub x}, x=0, 2, 4), which was used as acceptor material. The crystal structures were determined by single-crystal X-ray diffraction. Growth conditions for different vapor pressures in closed ampules were applied and the effect of these starting conditions for crystal size and quality is reported. The process of charge transfer was investigated by geometrical analysis of the crystal structure and by infrared spectroscopy on single crystals. With these three different acceptor strengths and the two sets of donor materials, it is possible to investigate the distribution of the charge transfer systematically. This helps to understand the charge transfer process in this class of materials with π-conjugated donor molecules.

  15. Conjugate heat transfer of laminar film condensation along a horizontal plate

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Euk Soo [Pusan National Univesity, Busan (Korea, Republic of)

    2006-03-15

    This paper proposes appropriate conjugate parameters and dimensionless temperatures to analysis the conjugate problem of heat conduction in solid wall coupled with laminar film condensation flow adjacent to horizontal flat plate. An efficient methods for some fluids are proposed for its solution. The momentum and energy balance equations are reduced to a nonlinear system of ordinary differential equations with four parameters: the Prandtl number, Pr, Modified Jacob number, Ja{sup *}/Pr, defined by an overall temperature difference, a property ratio {radical}{rho}{sub {iota}}{mu}{sub {iota}} {radical}{rho}{sub {upsilon}}{mu}{sub {upsilon}} and the conjugate parameter {zeta}. The obtained similarity solution reveals the effect of the conjugate parameter, and the results are compared with the simplified solution. The variations of the heat transfer rates as well as the interface temperature and frictions along the plate are shown explicitly.

  16. Conjugate heat transfer effects on wall bubble nucleation in subcooled flashing flows

    International Nuclear Information System (INIS)

    Peterson, P.F.; Hijikata, K.

    1990-01-01

    A variety of models have been proposed to explain observations that large liquid superheat is required to initiate nucleation in flashing flows of subcooled liquids in nozzles, cracks and pipes. In such flows an abrupt change in the fluid temperature occurs downstream of the nucleating cavities. This paper examines the subcooling of the nucleating cavities due to conjugate heat transfer to the cold downstream fluid. This examination suggests a mechanism limiting the maximum active cavity size. Simple analysis shows that, of the total superheat required to initiate flashing, a substantial portion results from conjugate wall subcooling, which decreases the cavity vapor pressure. The specific case of flashing critical nozzle flow is examined in detail. Here boundary-layer laminarization due to the strong favorable pressure gradient aids the analysis of conjugate heat transfer

  17. Enterococcus faecalis Sex Pheromone cCF10 Enhances Conjugative Plasmid Transfer In Vivo.

    Science.gov (United States)

    Hirt, Helmut; Greenwood-Quaintance, Kerryl E; Karau, Melissa J; Till, Lisa M; Kashyap, Purna C; Patel, Robin; Dunny, Gary M

    2018-02-13

    Cell-cell communication mediated by peptide pheromones (cCF10 [CF]) is essential for high-frequency plasmid transfer in vitro in Enterococcus faecalis To examine the role of pheromone signaling in vivo , we established either a CF-producing (CF+) recipient or a recipient producing a biologically inactive variant of CF (CF- recipient) in a germfree mouse model 3 days before donor inoculation and determined transfer frequencies of the pheromone-inducible plasmid pCF10. Plasmid transfer was detected in the upper and middle sections of the intestinal tract 5 h after donor inoculation and was highly efficient in the absence of antibiotic selection. The transconjugant/donor ratio reached a maximum level approaching 1 on day 4 in the upper intestinal tract. Plasmid transfer was significantly lower with the CF- recipient. While rescue of the CF- mating defect by coculture with CF+ recipients is easily accomplished in vitro , no extracellular complementation occurred in vivo This suggests that most pheromone signaling in the gut occurs between recipient and donor cells in very close proximity. Plasmid-bearing cells (donors plus transconjugants) steadily increased in the population from 0.1% after donor inoculation to about 10% at the conclusion of the experiments. This suggests a selective advantage of pCF10 carriage distinct from antibiotic resistance or bacteriocin production. Our results demonstrate that pheromone signaling is required for efficient pCF10 transfer in vivo In the absence of CF+ recipients, a low level of transfer to CF- recipients occurred in the gut. This may result from low-level host-mediated induction of the donors in the gastrointestinal (GI) tract, similar to that previously observed in serum. IMPORTANCE Horizontal gene transfer is a major factor in the biology of Enterococcus faecalis , an important nosocomial pathogen. Previous studies showing efficient conjugative plasmid transfer in the gastrointestinal (GI) tracts of experimental animals did

  18. Conjugate heat transfer for turbulent flow in a thick walled plain pipe

    Directory of Open Access Journals (Sweden)

    Canli Eyub

    2018-01-01

    Full Text Available Laminar and turbulent flow have their own characteristics in respect of heat transfer in pipes. While conjugate heat transfer is a major concern for a thick walled pipe with laminar flow inside it, there are limited studies about a turbulent flow in a thick walled plain pipe considering the conjugate heat transfer. In order to conduct such a work by means of in-house developed code, it was desired to make a preliminary investigation with commercially available CFD codes. ANSYS CFD was selected as the tool since it has a positive reputation in the literature for reliability. Defined heat transfer problem was solved with SIMPLE and Coupled Schemes for pressure velocity coupling and results are presented accordingly.

  19. Dynamic impedance compensation for wireless power transfer using conjugate power

    OpenAIRE

    Suqi Liu; Jianping Tan; Xue Wen

    2018-01-01

    Wireless power transfer (WPT) via coupled magnetic resonances has been in development for over a decade. However, the frequency splitting phenomenon occurs in the over-coupled region. Thus, the output power of the two-coil system achieves the maximum output power at the two splitting angular frequencies, and not at the natural resonant angular frequency. According to the maximum power transfer theorem, the impedance compensation method was adopted in many WPT projects. However, it remains a c...

  20. Effect of Conjugation Length on Photoinduced Charge-Transfer in π-Conjugated Oligomer-Acceptor Dyads

    KAUST Repository

    Jiang, Junlin

    2017-05-25

    A series of -conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (G0CS ~ -1.1 and G0CR ~ -2.0 eV), and the driving forces do not vary much across the series because the oxidation and reduction potentials and singlet energies of the OPEs do not vary much with their length. Bimolecular photoinduced charge transfer between model OPEs that do not contain the NDI acceptors with methyl viologen was studied, and the results reveal that the absorption of the cation radical state (OPE+•) remains approximately constant ( ~ 575 nm) regardless of oligomer length. This finding suggests that the cation radical (polaron) of the OPE is relatively localized, effectively occupying a confined segment of n 4 repeat units in the longer oligomers. Photoinduced intramolecular electron transfer dynamics in the PEn-NDI series was investigated by UV-visible femtosecond transient absorption spectroscopy with visible and mid-infrared probes. Charge separation occurs on the 1 – 10 ps timescale, with the rates decreasing slightly with increased oligomer length (βCS ~ 0.15 Å-1). The rate for charge-recombination decreases in the sequence PE4-NDI > PE6-NDI ~ PE8-NDI. The discontinuous distance dependence in the rate for charge recombination may be related to the spatial localization of the positive polaron state in the longer oligomers.

  1. Effect of Conjugation Length on Photoinduced Charge-Transfer in π-Conjugated Oligomer-Acceptor Dyads

    KAUST Repository

    Jiang, Junlin; Alsam, Amani Abdu; Wang, Shanshan; Aly, Shawkat Mohammede; Pan, Zhenxing; Mohammed, Omar F.; Schanze, Kirk S.

    2017-01-01

    A series of -conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (G0CS ~ -1.1 and G0CR ~ -2.0 eV), and the driving forces do not vary much across the series because the oxidation and reduction potentials and singlet energies of the OPEs do not vary much with their length. Bimolecular photoinduced charge transfer between model OPEs that do not contain the NDI acceptors with methyl viologen was studied, and the results reveal that the absorption of the cation radical state (OPE+•) remains approximately constant ( ~ 575 nm) regardless of oligomer length. This finding suggests that the cation radical (polaron) of the OPE is relatively localized, effectively occupying a confined segment of n 4 repeat units in the longer oligomers. Photoinduced intramolecular electron transfer dynamics in the PEn-NDI series was investigated by UV-visible femtosecond transient absorption spectroscopy with visible and mid-infrared probes. Charge separation occurs on the 1 – 10 ps timescale, with the rates decreasing slightly with increased oligomer length (βCS ~ 0.15 Å-1). The rate for charge-recombination decreases in the sequence PE4-NDI > PE6-NDI ~ PE8-NDI. The discontinuous distance dependence in the rate for charge recombination may be related to the spatial localization of the positive polaron state in the longer oligomers.

  2. Intergenic and intragenic conjugal transfer of multiple antibiotic ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-01-19

    Jan 19, 2009 ... antibiotic resistance determinants among bacteria in the aquatic ... loci of antibiotic resistant gene among bacteria in the surface water of Bangladesh. ..... bial communities is in assessing the risk of genetically engineered ...

  3. Translating Gene Transfer: A Stalled Effort

    OpenAIRE

    Greenberg, Alexandra J.; McCormick, Jennifer; Tapia, Carmen J.; Windebank, Anthony J.

    2011-01-01

    The journey of gene transfer from laboratory to clinic has been slow and fraught with many challenges and barriers. Despite the development of the initial technology in the early 1970s, a standard clinical treatment involving “gene therapy” remains to be seen. Furthermore, much was written about the technology in the early 1990s, but since then, not much has been written about the journey of gene transfer. The translational path of gene transfer thus far, both pitfalls and successes, can serv...

  4. The master regulator of IncA/C plasmids is recognized by the Salmonella Genomic island SGI1 as a signal for excision and conjugal transfer.

    Science.gov (United States)

    Kiss, János; Papp, Péter Pál; Szabó, Mónika; Farkas, Tibor; Murányi, Gábor; Szakállas, Erik; Olasz, Ferenc

    2015-10-15

    The genomic island SGI1 and its variants, the important vehicles of multi-resistance in Salmonella strains, are integrative elements mobilized exclusively by the conjugative IncA/C plasmids. Integration and excision of the island are carried out by the SGI1-encoded site-specific recombinase Int and the recombination directionality factor Xis. Chromosomal integration ensures the stable maintenance and vertical transmission of SGI1, while excision is the initial step of horizontal transfer, followed by conjugation and integration into the recipient. We report here that SGI1 not only exploits the conjugal apparatus of the IncA/C plasmids but also utilizes the regulatory mechanisms of the conjugation system for the exact timing and activation of excision to ensure efficient horizontal transfer. This study demonstrates that the FlhDC-family activator AcaCD, which regulates the conjugation machinery of the IncA/C plasmids, serves as a signal of helper entry through binding to SGI1 xis promoter and activating SGI1 excision. Promoters of int and xis genes have been identified and the binding site of the activator has been located by footprinting and deletion analyses. We prove that expression of xis is activator-dependent while int is constitutively expressed, and this regulatory mechanism is presumably responsible for the efficient transfer and stable maintenance of SGI1. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  5. Photoluminescence quenching through resonant energy transfer in blends of conjugated polymer with low-molecular acceptor

    International Nuclear Information System (INIS)

    Zapunidi, S. A.; Paraschuk, D. Yu.

    2008-01-01

    A model is proposed for photoluminescence quenching due to resonant energy transfer in a blend of a conjugated polymer and a low-molecular energy acceptor. An analytical dependence of the normalized photoluminescence intensity on the acceptor concentration is derived for the case of a homogeneous blend. This dependence can be described by two fitting parameters related to the Foerster radii for energy transfer between conjugated segments of the polymer and between the conjugated polymer segment and the energy acceptor. Asymptotic approximations are obtained for the model dependence that make it possible to estimate the contribution from the spatial migration of excitons to the photoluminescence quenching. The proposed model is used to analyze experimental data on the photoluminescence quenching in a blend of the soluble derivative of poly(p-phenylene vinylene) and trinitrofluorenone [13]. The Foerster radius for resonant energy transfer between the characteristic conjugated segment of poly(p-phenylene vinylene) and the energy acceptor is determined to be r F = 2.6 ± 0.3 nm

  6. Photoinduced partial charge transfer between conjugated polymer and fullerene in solutions

    International Nuclear Information System (INIS)

    Lin Hongzhen; Weng Yufeng; Huang Hongmin; He Qingguo; Zheng Min; Bai Fenglian

    2004-01-01

    Photoinduced charge transfer between a conjugated polymer and C 60 and the related processes were investigated in dilute solutions. The substantial fluorescence quenching is correlated with the efficient exciton diffusion within the polymer chains, according to which a sphere-of-action mechanism is proposed. An emissive exciplex was found formed between the conjugated polymer and fullerene in a nonpolar solvent, indicating the occurrence of a photoinduced partial charge transfer process. The low-energy sites in the polymer are believed to play a crucial role in the partial charge transfer. The asymmetry of the exciplex provides a method for evaluating the tendency of photoinduced charge separation between the donor and the acceptor. This method allows screening candidates for photovoltaic applications

  7. Charge transfer in conjugated oligomers encapsulated into carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Almadori, Y.; Alvarez, L.; Michel, T.; Le Parc, R.; Bantignies, J.L.; Hermet, P.; Sauvajol, J.L. [Laboratoire Charles Coulomb UMR 5521, Universite Montpellier 2, 34095 Montpellier (France); Laboratoire Charles Coulomb UMR 5521, CNRS, 34095 Montpellier (France); Arenal, R. [Laboratoire d' Etude des Microstructures, CNRS-ONERA, 92322 Chatillon (France); Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, U. Zaragoza, 50018 Zaragoza (Spain); Babaa, R. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France); Chemical Engineering Department, University of Technology PETRONAS, UTP, Ipoh-Perak (Malaysia); Jouselme, B.; Palacin, S. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France)

    2011-11-15

    This study deals with a hybrid system consisting in quaterthiophene derivative encapsulated inside single-walled and multi-walled carbon nanotubes. Investigations of the encapsulation step are performed by transmission electron microscopy. Raman spectroscopy data point out different behaviors depending on the laser excitation energy with respect to the optical absorption of quaterthiophene. At low excitation energy (far from the oligomer resonance window) there is no significant modification of the Raman spectra before and after encapsulation. By contrast, at high excitation energy (close to the oligomer resonance window), Raman spectra exhibit a G-band shift together with an important RBM intensity loss, suggesting a significant charge transfer between the inserted molecule and the host nanotubes. Those results suggest a photo induced process leading to a significant charge transfer. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Genome-Wide Identification, Phylogenetic and Expression Analyses of the Ubiquitin-Conjugating Enzyme Gene Family in Maize

    Science.gov (United States)

    Jue, Dengwei; Sang, Xuelian; Lu, Shengqiao; Dong, Chen; Zhao, Qiufang; Chen, Hongliang; Jia, Liqiang

    2015-01-01

    Background Ubiquitination is a post-translation modification where ubiquitin is attached to a substrate. Ubiquitin-conjugating enzymes (E2s) play a major role in the ubiquitin transfer pathway, as well as a variety of functions in plant biological processes. To date, no genome-wide characterization of this gene family has been conducted in maize (Zea mays). Methodology/Principal Findings In the present study, a total of 75 putative ZmUBC genes have been identified and located in the maize genome. Phylogenetic analysis revealed that ZmUBC proteins could be divided into 15 subfamilies, which include 13 ubiquitin-conjugating enzymes (ZmE2s) and two independent ubiquitin-conjugating enzyme variant (UEV) groups. The predicted ZmUBC genes were distributed across 10 chromosomes at different densities. In addition, analysis of exon-intron junctions and sequence motifs in each candidate gene has revealed high levels of conservation within and between phylogenetic groups. Tissue expression analysis indicated that most ZmUBC genes were expressed in at least one of the tissues, indicating that these are involved in various physiological and developmental processes in maize. Moreover, expression profile analyses of ZmUBC genes under different stress treatments (4°C, 20% PEG6000, and 200 mM NaCl) and various expression patterns indicated that these may play crucial roles in the response of plants to stress. Conclusions Genome-wide identification, chromosome organization, gene structure, evolutionary and expression analyses of ZmUBC genes have facilitated in the characterization of this gene family, as well as determined its potential involvement in growth, development, and stress responses. This study provides valuable information for better understanding the classification and putative functions of the UBC-encoding genes of maize. PMID:26606743

  9. CRISPR-cas-mediated phage resistance enhances horizontal gene transfer by transduction

    NARCIS (Netherlands)

    Watson, Bridget N.J.; Staals, Raymond H.J.; Fineran, Peter C.

    2018-01-01

    A powerful contributor to prokaryotic evolution is horizontal gene transfer (HGT) through transformation, conjugation, and transduction, which can be advantageous, neutral, or detrimental to fitness. Bacteria and archaea control HGT and phage infection through CRISPR-Cas (clustered regularly

  10. Gene transfer therapy in vascular diseases.

    Science.gov (United States)

    McKay, M J; Gaballa, M A

    2001-01-01

    Somatic gene therapy of vascular diseases is a promising new field in modern medicine. Recent advancements in gene transfer technology have greatly evolved our understanding of the pathophysiologic role of candidate disease genes. With this knowledge, the expression of selective gene products provides the means to test the therapeutic use of gene therapy in a multitude of medical conditions. In addition, with the completion of genome sequencing programs, gene transfer can be used also to study the biologic function of novel genes in vivo. Novel genes are delivered to targeted tissue via several different vehicles. These vectors include adenoviruses, retroviruses, plasmids, plasmid/liposomes, and oligonucleotides. However, each one of these vectors has inherent limitations. Further investigations into developing delivery systems that not only allow for efficient, targeted gene transfer, but also are stable and nonimmunogenic, will optimize the clinical application of gene therapy in vascular diseases. This review further discusses the available mode of gene delivery and examines six major areas in vascular gene therapy, namely prevention of restenosis, thrombosis, hypertension, atherosclerosis, peripheral vascular disease in congestive heart failure, and ischemia. Although we highlight some of the recent advances in the use of gene therapy in treating vascular disease discovered primarily during the past two years, many excellent studies published during that period are not included in this review due to space limitations. The following is a selective review of practical uses of gene transfer therapy in vascular diseases. This review primarily covers work performed in the last 2 years. For earlier work, the reader may refer to several excellent review articles. For instance, Belalcazer et al. (6) reviewed general aspects of somatic gene therapy and the different vehicles used for the delivery of therapeutic genes. Gene therapy in restenosis and stimulation of

  11. Treatment with Cefotaxime Affects Expression of Conjugation Associated Proteins and Conjugation Transfer Frequency of an IncI1 Plasmid in Escherichia coli

    DEFF Research Database (Denmark)

    Møller, Thea S B; Liu, Gang; Boysen, Anders

    2017-01-01

    research suggests that the effect of antibiotic treatment on plasmid conjugation frequencies, and hence the spread of resistance plasmids, may have been overestimated. We addressed the question by quantifying transfer proteins and conjugation frequencies of a blaCTX-M-1 encoding IncI1 resistance plasmid....... The frequency of plasmid conjugation, measured in an antibiotic free environment, increased significantly when the donor was pre-grown in broth containing CTX compared to growth without this drug, regardless of whether blaCTX-M-1 was located on the plasmid or in trans on the chromosome. The results shows...

  12. Translating gene transfer: a stalled effort.

    Science.gov (United States)

    Greenberg, Alexandra J; McCormick, Jennifer; Tapia, Carmen J; Windebank, Anthony J

    2011-08-01

    The journey of gene transfer from laboratory to clinic has been slow and fraught with many challenges and barriers. Despite the development of the initial technology in the early 1970s, a standard clinical treatment involving "gene therapy" remains to be seen. Furthermore, much was written about the technology in the early 1990s, but since then, not much has been written about the journey of gene transfer. The translational path of gene transfer thus far, both pitfalls and successes, can serve as a study not only in navigating ethical and safety concerns, but also in the importance of scientist-public interactions. Here, we examine the translational progress of gene transfer and what can be gleaned from its history. © 2011 Wiley Periodicals, Inc.

  13. Pentanidium-catalyzed enantioselective phase-transfer conjugate addition reactions

    KAUST Repository

    Ma, Ting

    2011-03-09

    A new chiral entity, pentanidium, has been shown to be an excellent chiral phase-transfer catalyst. The enantioselective Michael addition reactions of tert-butyl glycinate-benzophenone Schiff base with various α,β- unsaturated acceptors provide adducts with high enantioselectivities. A successful gram-scale experiment at a low catalyst loading of 0.05 mol % indicates the potential for practical applications of this methodology. Phosphoglycine ester analogues can also be utilized as the Michael donor, affording enantioenriched α-aminophosphonic acid derivatives and phosphonic analogues of (S)-proline. © 2011 American Chemical Society.

  14. A computationally efficient method for full-core conjugate heat transfer modeling of sodium fast reactors

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Rui, E-mail: rhu@anl.gov; Yu, Yiqi

    2016-11-15

    Highlights: • Developed a computationally efficient method for full-core conjugate heat transfer modeling of sodium fast reactors. • Applied fully-coupled JFNK solution scheme to avoid the operator-splitting errors. • The accuracy and efficiency of the method is confirmed with a 7-assembly test problem. • The effects of different spatial discretization schemes are investigated and compared to the RANS-based CFD simulations. - Abstract: For efficient and accurate temperature predictions of sodium fast reactor structures, a 3-D full-core conjugate heat transfer modeling capability is developed for an advanced system analysis tool, SAM. The hexagon lattice core is modeled with 1-D parallel channels representing the subassembly flow, and 2-D duct walls and inter-assembly gaps. The six sides of the hexagon duct wall and near-wall coolant region are modeled separately to account for different temperatures and heat transfer between coolant flow and each side of the duct wall. The Jacobian Free Newton Krylov (JFNK) solution method is applied to solve the fluid and solid field simultaneously in a fully coupled fashion. The 3-D full-core conjugate heat transfer modeling capability in SAM has been demonstrated by a verification test problem with 7 fuel assemblies in a hexagon lattice layout. Additionally, the SAM simulation results are compared with RANS-based CFD simulations. Very good agreements have been achieved between the results of the two approaches.

  15. Guanidinylated polyethyleneimine-polyoxypropylene-polyoxyethylene conjugates as gene transfection agents.

    Science.gov (United States)

    Bromberg, Lev; Raduyk, Svetlana; Hatton, T Alan; Concheiro, Angel; Rodriguez-Valencia, Cosme; Silva, Maite; Alvarez-Lorenzo, Carmen

    2009-05-20

    Conjugates of linear and branched polyethyleneimine (PEI) and monoamine polyether Jeffamine M-2070 (PO/EO mol ratio 10/31, 2000 Da) were synthesized through polyether activation by cyanuric chloride followed by attachment to PEI and guanidinylation by 1H-pyrazole-carboxamidine hydrochloride. The resulting guanidinylated PEI-polyether conjugates (termed gPEI-Jeffamine) efficiently complexed plasmid DNA, and their polyplexes possessed enhanced colloidal stability in the presence of serum proteins. In vitro studies with mammalian CHO-1, 3T3, and Cos-7 cell lines demonstrated improved transfection efficiency of the pCMVbeta-gal plasmid/gPEI-Jeffamine polyplexes. The guanidinylation of the amino groups of PEI and the conjugation of PEI with the Jeffamine polyether enhanced the conjugates' interaction with genetic material and reduced the cytotoxicity of the polyplexes in experiments with the L929 cell line.

  16. Requirement for Vibrio cholerae integration host factor in conjugative DNA transfer.

    Science.gov (United States)

    McLeod, Sarah M; Burrus, Vincent; Waldor, Matthew K

    2006-08-01

    The requirement for host factors in the transmission of integrative and conjugative elements (ICEs) has not been extensively explored. Here we tested whether integration host factor (IHF) or Fis, two host-encoded nucleoid proteins, are required for transfer of SXT, a Vibrio cholerae-derived ICE that can be transmitted to many gram-negative species. Fis did not influence the transfer of SXT to or from V. cholerae. In contrast, IHF proved to be required for V. cholerae to act as an SXT donor. In the absence of IHF, V. cholerae displayed a modest defect for serving as an SXT recipient. Surprisingly, SXT integration into or excision from the V. cholerae chromosome, which requires an SXT-encoded integrase related to lambda integrase, did not require IHF. Therefore, the defect in SXT transmission in the V. cholerae IHF mutant is probably not related to IHF's ability to promote DNA recombination. The V. cholerae IHF mutant was also highly impaired as a donor of RP4, a broad-host-range conjugative plasmid. Thus, the V. cholerae IHF mutant appears to have a general defect in conjugation. Escherichia coli IHF mutants were not impaired as donors or recipients of SXT or RP4, indicating that IHF is a V. cholerae-specific conjugation factor.

  17. Gene Transfers Between Distantly Related Organisms

    Science.gov (United States)

    Doolittle, Russell F.

    2003-01-01

    With the completion of numerous microbial genome sequences, reports of individual gene transfers between distantly related prokaryotes have become commonplace. On the other hand, transfers between prokaryotes and eukaryotes still excite the imagination. Many of these claims may be premature, but some are certainly valid. In this chapter, the kinds of supporting data needed to propose transfers between distantly related organisms and cite some interesting examples are considered.

  18. Risks from GMOs due to horizontal gene transfer.

    Science.gov (United States)

    Keese, Paul

    2008-01-01

    Horizontal gene transfer (HGT) is the stable transfer of genetic material from one organism to another without reproduction or human intervention. Transfer occurs by the passage of donor genetic material across cellular boundaries, followed by heritable incorporation to the genome of the recipient organism. In addition to conjugation, transformation and transduction, other diverse mechanisms of DNA and RNA uptake occur in nature. The genome of almost every organism reveals the footprint of many ancient HGT events. Most commonly, HGT involves the transmission of genes on viruses or mobile genetic elements. HGT first became an issue of public concern in the 1970s through the natural spread of antibiotic resistance genes amongst pathogenic bacteria, and more recently with commercial production of genetically modified (GM) crops. However, the frequency of HGT from plants to other eukaryotes or prokaryotes is extremely low. The frequency of HGT to viruses is potentially greater, but is restricted by stringent selection pressures. In most cases the occurrence of HGT from GM crops to other organisms is expected to be lower than background rates. Therefore, HGT from GM plants poses negligible risks to human health or the environment.

  19. Requirement for Vibrio cholerae Integration Host Factor in Conjugative DNA Transfer

    OpenAIRE

    McLeod, Sarah M.; Burrus, Vincent; Waldor, Matthew K.

    2006-01-01

    The requirement for host factors in the transmission of integrative and conjugative elements (ICEs) has not been extensively explored. Here we tested whether integration host factor (IHF) or Fis, two host-encoded nucleoid proteins, are required for transfer of SXT, a Vibrio cholerae-derived ICE that can be transmitted to many gram-negative species. Fis did not influence the transfer of SXT to or from V. cholerae. In contrast, IHF proved to be required for V. cholerae to act as an SXT donor. I...

  20. Antimicrobial Peptide-PNA Conjugates Selectively Targeting Bacterial Genes

    Science.gov (United States)

    2013-07-22

    antibacterial therapy. Initial publications suggest that conjugates of cell penetrating peptides and PNA’s can overcome the barrier in transporting ...Zhou, Y., Hou, Z., Meng, J., and Luo, X. Targeting RNA polymerase primary σ70 as a therapeutic strategy against methicillin - resistant ... Staphylococcus aureus by antisense peptide nucleic acid. PLoS One. 2012; 7(1):e29886. 2. Good, L., Sandberg, R., Larsson, O., Nielsen, P.E., and Wahlestedt, C

  1. Fluorescence resonance energy transfer between conjugated molecules infiltrated in three-dimensional opal photonic crystals

    International Nuclear Information System (INIS)

    Zou, Lu; Sui, Ning; Wang, Ying-Hui; Qian, Cheng; Ma, Yu-Guang; Zhang, Han-Zhuang

    2015-01-01

    Fluorescence resonance energy transfer (FRET) from Coumarin 6 (C-6) to Sulforhodamine B (S-B) infiltrated into opal PMMA (poly-methyl-methacrylate) photonic crystals (PCs) has been studied in detail. The intrinsic mesh micro-porous structure of opal PCs could increase the luminescent efficiency through inhibiting the intermolecular interaction. Meanwhile, its structure of periodically varying refractive indices could also modify the FRET through affecting the luminescence characteristics of energy donor or energy acceptor. The results demonstrate that the FRET efficiency between conjugated dyes was easily modified by opal PCs. - Highlights: • We investigate the fluorescence resonance energy transfer between two kinds of dyes. • These two kinds of dyes are infiltrated in PMMA opal photonic crystals. • The structure of opal PCs could improve the luminescent characteristics. • The structure of opal PCs could improve the energy transfer characteristics

  2. Mobilisation and remobilisation of a large archetypal pathogenicity island of uropathogenic Escherichia coli in vitro support the role of conjugation for horizontal transfer of genomic islands

    Directory of Open Access Journals (Sweden)

    Hochhut Bianca

    2011-09-01

    Full Text Available Abstract Background A substantial amount of data has been accumulated supporting the important role of genomic islands (GEIs - including pathogenicity islands (PAIs - in bacterial genome plasticity and the evolution of bacterial pathogens. Their instability and the high level sequence similarity of different (partial islands suggest an exchange of PAIs between strains of the same or even different bacterial species by horizontal gene transfer (HGT. Transfer events of archetypal large genomic islands of enterobacteria which often lack genes required for mobilisation or transfer have been rarely investigated so far. Results To study mobilisation of such large genomic regions in prototypic uropathogenic E. coli (UPEC strain 536, PAI II536 was supplemented with the mobRP4 region, an origin of replication (oriVR6K, an origin of transfer (oriTRP4 and a chloramphenicol resistance selection marker. In the presence of helper plasmid RP4, conjugative transfer of the 107-kb PAI II536 construct occured from strain 536 into an E. coli K-12 recipient. In transconjugants, PAI II536 existed either as a cytoplasmic circular intermediate (CI or integrated site-specifically into the recipient's chromosome at the leuX tRNA gene. This locus is the chromosomal integration site of PAI II536 in UPEC strain 536. From the E. coli K-12 recipient, the chromosomal PAI II536 construct as well as the CIs could be successfully remobilised and inserted into leuX in a PAI II536 deletion mutant of E. coli 536. Conclusions Our results corroborate that mobilisation and conjugal transfer may contribute to evolution of bacterial pathogens through horizontal transfer of large chromosomal regions such as PAIs. Stabilisation of these mobile genetic elements in the bacterial chromosome result from selective loss of mobilisation and transfer functions of genomic islands.

  3. Evidence for the role of horizontal transfer in generating pVT1, a large mosaic conjugative plasmid from the clam pathogen, Vibrio tapetis.

    Directory of Open Access Journals (Sweden)

    Gaël Erauso

    Full Text Available The marine bacterium Vibrio tapetis is the causative agent of the brown ring disease, which affects the clam Ruditapes philippinarum and causes heavy economic losses in North of Europe and in Eastern Asia. Further characterization of V. tapetis isolates showed that all the investigated strains harbored at least one large plasmid. We determined the sequence of the 82,266 bp plasmid pVT1 from the CECT4600(T reference strain and analyzed its genetic content. pVT1 is a mosaic plasmid closely related to several conjugative plasmids isolated from Vibrio vulnificus strains and was shown to be itself conjugative in Vibrios. In addition, it contains DNA regions that have similarity with several other plasmids from marine bacteria (Vibrio sp., Shewanella sp., Listonella anguillarum and Photobacterium profundum. pVT1 contains a number of mobile elements, including twelve Insertion Sequences or inactivated IS genes and an RS1 phage element related to the CTXphi phage of V. cholerae. The genetic organization of pVT1 underscores an important role of horizontal gene transfer through conjugative plasmid shuffling and transposition events in the acquisition of new genetic resources and in generating the pVT1 modular organization. In addition, pVT1 presents a copy number of 9, relatively high for a conjugative plasmid, and appears to belong to a new type of replicon, which may be specific to Vibrionaceae and Shewanelleacae.

  4. Conjugated heat transfer and temperature distributions in a gas turbine combustion liner under base-load operation

    International Nuclear Information System (INIS)

    Kim, Kyung Min; Yun, Nam Geon; Jeon, Yun Heung; Lee, Dong Hyun; Cho, Yung Hee

    2010-01-01

    Prediction of temperature distributions on hot components is important in development of a gas turbine combustion liner. The present study investigated conjugated heat transfer to obtain temperature distributions in a combustion liner with six combustion nozzles. 3D numerical simulations using FVM commercial codes, Fluent and CFX were performed to calculate combustion and heat transfer distributions. The temperature distributions in the combustor liner were calculated by conjugation of conduction and convection (heat transfer coefficients) obtained by combustion and cooling flow analysis. The wall temperature was the highest on the attachment points of the combustion gas from combustion nozzles, but the temperature gradient was high at the after shell section with low wall temperature

  5. Conjugate heat transfer analysis for in-vessel retention with external reactor vessel cooling

    International Nuclear Information System (INIS)

    Park, Jong-Woon; Bae, Jae-ho; Song, Hyuk-Jin

    2016-01-01

    Highlights: • A conjugate heat transfer analysis method is applied for in-vessel corium retention. • 3D heat diffusion has a formidable effect in alleviating focusing heat load from metallic layer. • The focusing heat load is decreased by about 2.5 times on the external surface. - Abstract: A conjugate heat transfer analysis method for the thermal integrity of a reactor vessel under external reactor vessel cooling conditions is developed to resolve light metal layer focusing effect issue for in-vessel retention. The method calculates steady-state three-dimensional temperature distribution of a reactor vessel using coupled conjugate heat transfer between in-vessel three-layered stratified corium (metallic pool, oxide pool and heavy metal and polar-angle dependent boiling heat transfer at the outer surface of a reactor vessel). The three-layer corium heat transfer model is utilizing lumped-parameter thermal-resistance circuit method. For the ex-vessel boiling boundary conditions, nucleate, transition and film boiling are considered. The thermal integrity of a reactor vessel is addressed in terms of heat flux at the outer-most nodes of the vessel and remaining thickness profile. The vessel three-dimensional heat conduction is validated against a commercial code. It is found that even though the internal heat flux from the metal layer goes far beyond critical heat flux (CHF) the heat flux from the outermost nodes of the vessel may be maintained below CHF due to massive vessel heat diffusion. The heat diffusion throughout the vessel is more pronounced for relatively low heat generation rate in an oxide pool. Parametric calculations are performed considering thermal conditions such as peak heat flux from a light metal layer, heat generation in an oxide pool and external boiling conditions. The major finding is that the most crucial factor for success of in-vessel retention is not the mass of the molten light metal above the oxide pool but the heat generation rate

  6. Conjugal transfer of plasmid pAM beta 1 in Lactobacillus reuteri and between lactobacilli and Enterococcus faecalis.

    OpenAIRE

    Tannock, G W

    1987-01-01

    The broad-host-range plasmid pAM beta 1 (erythromycin resistance) was transferred conjugally from Streptococcus lactis to Lactobacillus reuteri, L. murinus, and L. fermentum. Transfer of pAM beta 1 between two L. reuteri strains occurred, and lactobacillus transconjugants could act as donors of pAM beta 1 in crosses with Enterococcus faecalis JH2-2.

  7. Horizontal gene transfer in silkworm, Bombyx mori

    Science.gov (United States)

    2011-01-01

    Background The domesticated silkworm, Bombyx mori, is the model insect for the order Lepidoptera, has economically important values, and has gained some representative behavioral characteristics compared to its wild ancestor. The genome of B. mori has been fully sequenced while function analysis of BmChi-h and BmSuc1 genes revealed that horizontal gene transfer (HGT) maybe bestow a clear selective advantage to B. mori. However, the role of HGT in the evolutionary history of B. mori is largely unexplored. In this study, we compare the whole genome of B. mori with those of 382 prokaryotic and eukaryotic species to investigate the potential HGTs. Results Ten candidate HGT events were defined in B. mori by comprehensive sequence analysis using Maximum Likelihood and Bayesian method combining with EST checking. Phylogenetic analysis of the candidate HGT genes suggested that one HGT was plant-to- B. mori transfer while nine were bacteria-to- B. mori transfer. Furthermore, functional analysis based on expression, coexpression and related literature searching revealed that several HGT candidate genes have added important characters, such as resistance to pathogen, to B. mori. Conclusions Results from this study clearly demonstrated that HGTs play an important role in the evolution of B. mori although the number of HGT events in B. mori is in general smaller than those of microbes and other insects. In particular, interdomain HGTs in B. mori may give rise to functional, persistent, and possibly evolutionarily significant new genes. PMID:21595916

  8. Effect of genomic location on horizontal transfer of a recombinant gene cassette between Pseudomonas strains in the rhizosphere and spermosphere of barley seedlings

    DEFF Research Database (Denmark)

    Sengelov, G.; Kristensen, K. J.; Sørensen, Anders Morten Hay

    2001-01-01

    , horizontal transfer of a recombinant gene cassette inserted into the chromosome of a Pseudomonas strutzeri strain, into a mobilizable plasmid (pAGM42), and into a conjugative plasmid (pKJK5) isolated from barley rhizosphere was investigated. Horizontal transfer efficiencies of the gene cassette inserted...... efficiencies were up to 4.36 x 10(-3) transconjugants/(donors x recipients)(1/2). Transfer of chromosomal encoded genes could not be detected in the microcosms by conjugation or transformation. However, transformation did occur by using the same bacterial strains under laboratory conditions. The rhizosphere...

  9. Stochastic modelling of conjugate heat transfer in near-wall turbulence

    International Nuclear Information System (INIS)

    Pozorski, Jacek; Minier, Jean-Pierre

    2006-01-01

    The paper addresses the conjugate heat transfer in turbulent flows with temperature assumed to be a passive scalar. The Lagrangian approach is applied and the heat transfer is modelled with the use of stochastic particles. The intensity of thermal fluctuations in near-wall turbulence is determined from the scalar probability density function (PDF) with externally provided dynamical statistics. A stochastic model for the temperature field in the wall material is proposed and boundary conditions for stochastic particles at the solid-fluid interface are formulated. The heated channel flow with finite-thickness walls is considered as a validation case. Computation results for the mean temperature profiles and the variance of thermal fluctuations are presented and compared with available DNS data

  10. Stochastic modelling of conjugate heat transfer in near-wall turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Pozorski, Jacek [Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80952 Gdansk (Poland)]. E-mail: jp@imp.gda.pl; Minier, Jean-Pierre [Research and Development Division, Electricite de France, 6 quai Watier, 78400 Chatou (France)

    2006-10-15

    The paper addresses the conjugate heat transfer in turbulent flows with temperature assumed to be a passive scalar. The Lagrangian approach is applied and the heat transfer is modelled with the use of stochastic particles. The intensity of thermal fluctuations in near-wall turbulence is determined from the scalar probability density function (PDF) with externally provided dynamical statistics. A stochastic model for the temperature field in the wall material is proposed and boundary conditions for stochastic particles at the solid-fluid interface are formulated. The heated channel flow with finite-thickness walls is considered as a validation case. Computation results for the mean temperature profiles and the variance of thermal fluctuations are presented and compared with available DNS data.

  11. Theory of interfacial charge-transfer complex photophysics in π-conjugated polymer-fullerene blends

    Science.gov (United States)

    Aryanpour, K.; Psiachos, D.; Mazumdar, S.

    2010-03-01

    We present a theory of the electronic structure and photophysics of 1:1 blends of derivatives of polyparaphenylenevinylene and fullerenes [1]. Within the same Coulomb-correlated Hamiltonian applied previously to interacting chains of single-component π-conjugated polymers [2], we find an exciplex state that occurs below the polymer's optical exciton. Weak absorption from the ground state occurs to the exciplex. We explain transient photoinduced absorptions in the blend [3], observed for both above-gap and below-gap photoexcitations, within our theory. Photoinduced absorptions for above-gap photoexcitation are from the optical exciton as well as the exciplex, while for below-gap photoexcitation induced absorptions are from the exciplex alone. In neither case are free polarons generated in the time scale of the experiment. Importantly, the photophysics of films of single-component π-conjugated polymers and blends can both be understood by extending Mulliken's theory of ground state charge-transfer to the case of excited state charge-transfer. [1] K. Aryanpour, D. Psiachos, and S. Mazumdar, arXiv:0908.0366 [2] D. Psiachos and S. Mazumdar, Phys. Rev. B. 79 155106 (2009) [3] T. Drori et al., Phys. Rev. Lett. 101, 037402 (2008)

  12. DNS of turbulent channel flow with conjugate heat transfer at Prandtl number 0.01

    Energy Technology Data Exchange (ETDEWEB)

    Tiselj, Iztok, E-mail: iztok.tiselj@ijs.si [' Jozef Stefan' Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Cizelj, Leon, E-mail: leon.cizelj@ijs.si [' Jozef Stefan' Institute, Jamova 39, SI-1000 Ljubljana (Slovenia)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer DNS database for turbulent channel flow at Prandtl number 0.01 and various Re{sub {tau}}. Black-Right-Pointing-Pointer Two ideal boundary condition analyzed: non-fluctuating and fluctuating temperature. Black-Right-Pointing-Pointer DNS database with conjugate heat transfer for liquid sodium-steel contact. Black-Right-Pointing-Pointer Penetration of the turbulent temperature fluctuations into the solid wall analyzed. - Abstract: Direct Numerical Simulation (DNS) of the fully developed velocity and temperature fields in a turbulent channel flow coupled with the unsteady conduction in the heated walls was carried out. Simulations were performed with passive scalar approximation at Prandtl number 0.01, which roughly corresponds to the Prandtl number of liquid sodium. DNSs were performed at friction Reynolds numbers 180, 395 and 590. The obtained statistical quantities like mean temperatures, profiles of the root-mean-square (RMS) temperature fluctuations for various thermal properties of wall and fluid, and various wall thicknesses were obtained from a pseudo-spectral channel-flow code. Even for the highest implemented Reynolds number the temperature profile in the fluid does not exhibit log-law region and the near-wall RMS temperature fluctuations show Reynolds number dependence. Conjugate heat transfer simulations of liquid sodium-steel system point to a relatively intensive penetration of turbulent temperature fluctuations into the heated wall. Database containing the results is available in a digital form.

  13. DNS of turbulent channel flow with conjugate heat transfer at Prandtl number 0.01

    International Nuclear Information System (INIS)

    Tiselj, Iztok; Cizelj, Leon

    2012-01-01

    Highlights: ► DNS database for turbulent channel flow at Prandtl number 0.01 and various Re τ . ► Two ideal boundary condition analyzed: non-fluctuating and fluctuating temperature. ► DNS database with conjugate heat transfer for liquid sodium–steel contact. ► Penetration of the turbulent temperature fluctuations into the solid wall analyzed. - Abstract: Direct Numerical Simulation (DNS) of the fully developed velocity and temperature fields in a turbulent channel flow coupled with the unsteady conduction in the heated walls was carried out. Simulations were performed with passive scalar approximation at Prandtl number 0.01, which roughly corresponds to the Prandtl number of liquid sodium. DNSs were performed at friction Reynolds numbers 180, 395 and 590. The obtained statistical quantities like mean temperatures, profiles of the root-mean-square (RMS) temperature fluctuations for various thermal properties of wall and fluid, and various wall thicknesses were obtained from a pseudo-spectral channel-flow code. Even for the highest implemented Reynolds number the temperature profile in the fluid does not exhibit log-law region and the near-wall RMS temperature fluctuations show Reynolds number dependence. Conjugate heat transfer simulations of liquid sodium–steel system point to a relatively intensive penetration of turbulent temperature fluctuations into the heated wall. Database containing the results is available in a digital form.

  14. Conjugate Heat Transfer of Mixed Convection for Viscoelastic Fluid Past a Stretching Sheet

    Directory of Open Access Journals (Sweden)

    Kai-Long Hsiao

    2007-01-01

    Full Text Available A conjugate heat transfer problem of a second-grade viscoelastic fluid past a stretching sheet has been studied. Governing equations include heat conduction equation of a stretching sheet, continuity equation, momentum equation, and energy equation of a second-grade fluid, analyzed by a combination of a series expansion method, the similarity transformation, and a second-order accurate finite-difference method. These solutions are used to iterate with the heat conduction equation of the stretching sheet to obtain distributions of the local convective heat transfer coefficient and the stretching sheet temperature. Ranges of dimensionless parameters, the Prandtl number Pr, the elastic number E and the conduction-convection coefficient Ncc are from 0.001 to 10, 0.0001 to 0.01, and 0.5 to 2.0, respectively. A parameter G, which is used to represent the dominance of the buoyant effect, is present in governing equations. Results indicated that elastic effect in the flow could increase the local heat transfer coefficient and enhance the heat transfer of a stretching sheet. In addition, same as the results from Newtonian fluid flow and conduction analysis of a stretching sheet, a better heat transfer is obtained with a larger Ncc, G, and E.

  15. Synthetic Nucleic Acid Analogues in Gene Therapy: An Update for Peptide–Oligonucleotide Conjugates

    DEFF Research Database (Denmark)

    Taskova, Maria; Mantsiou, Anna; Astakhova, Kira

    2017-01-01

    The main objective of this work is to provide an update on synthetic nucleic acid analogues and nanoassemblies as tools in gene therapy. In particular, the synthesis and properties of peptide–oligonucleotide conjugates (POCs), which have high potential in research and as therapeutics, are described...

  16. Widespread of horizontal gene transfer in the human genome

    OpenAIRE

    Huang, Wenze; Tsai, Lillian; Li, Yulong; Hua, Nan; Sun, Chen; Wei, Chaochun

    2017-01-01

    Background A fundamental concept in biology is that heritable material is passed from parents to offspring, a process called vertical gene transfer. An alternative mechanism of gene acquisition is through horizontal gene transfer (HGT), which involves movement of genetic materials between different species. Horizontal gene transfer has been found prevalent in prokaryotes but very rare in eukaryote. In this paper, we investigate horizontal gene transfer in the human genome. Results From the pa...

  17. Conjugative plasmids: Vessels of the communal gene pool

    DEFF Research Database (Denmark)

    Norman, Anders; Hansen, Lars H.; Sørensen, Søren Johannes

    2009-01-01

    to the hosts and, potentially, other resident prokaryotes within specific environmental niches. Insight into the evolution of plasmid modules therefore contributes to our knowledge of gene dissemination and evolution within prokaryotic communities. This communal pool provides the prokaryotes with an important...... mechanistic framework for obtaining adaptability and functional diversity that alleviates the need for large genomes of specialized ‘private genes'....

  18. Plant nodulation inducers enhance horizontal gene transfer of Azorhizobium caulinodans symbiosis island.

    Science.gov (United States)

    Ling, Jun; Wang, Hui; Wu, Ping; Li, Tao; Tang, Yu; Naseer, Nawar; Zheng, Huiming; Masson-Boivin, Catherine; Zhong, Zengtao; Zhu, Jun

    2016-11-29

    Horizontal gene transfer (HGT) of genomic islands is a driving force of bacterial evolution. Many pathogens and symbionts use this mechanism to spread mobile genetic elements that carry genes important for interaction with their eukaryotic hosts. However, the role of the host in this process remains unclear. Here, we show that plant compounds inducing the nodulation process in the rhizobium-legume mutualistic symbiosis also enhance the transfer of symbiosis islands. We demonstrate that the symbiosis island of the Sesbania rostrata symbiont, Azorhizobium caulinodans, is an 87.6-kb integrative and conjugative element (ICE Ac ) that is able to excise, form a circular DNA, and conjugatively transfer to a specific site of gly-tRNA gene of other rhizobial genera, expanding their host range. The HGT frequency was significantly increased in the rhizosphere. An ICE Ac -located LysR-family transcriptional regulatory protein AhaR triggered the HGT process in response to plant flavonoids that induce the expression of nodulation genes through another LysR-type protein, NodD. Our study suggests that rhizobia may sense rhizosphere environments and transfer their symbiosis gene contents to other genera of rhizobia, thereby broadening rhizobial host-range specificity.

  19. The use of alien gene transfers

    International Nuclear Information System (INIS)

    Bhatia, C.R.

    1976-01-01

    The present status of the gene transfers from alien species belonging to the sub-tribe Triticanae into wheat is reviewed, and the advantages and disadvantages of the different methods available for such transfers are examined. In general, the alien genes provide a high degree of resistance against a notably wide range of physiological races of wheat rusts, powdery mildew and other diseases. The alien resistance, like other sources of resistance, is known to break down for certain new races. This may happen more often when alien genes of resistance are widely incorporated in commercial cultivars and grown over large areas. So far, few of the available induced translocation stocks have contributed to the development of agronomically superior commercial cultivars, mainly due to the associated undesirable effects of the translocations on agronomic characters of the recipient variety. The deleterious effects appear in some genetic backgrounds and not in others. Extensive hybridization of translocation stocks with different genotypes has been emphasized by most investigators. Such programmes have led to the release of three commercial cultivars - 2 in Australia and 1 in the USA. On the other hand, spontaneous wheat-rye translocations carrying gene(s) for disease resistance have been unconsciously incorporated into several wheat cultivars, some of them are widely cultivated and were top in ranking based on grain yield. (author)

  20. Numerical study of the conjugate heat transfer in a horizontal pipe heated by Joulean effect

    Directory of Open Access Journals (Sweden)

    Touahri Sofiane

    2012-01-01

    Full Text Available The three dimensional mixed convection heat transfer in a electrically heated horizontal pipe conjugated to a thermal conduction through the entire solid thickness is investigated by taking into account the thermal dependence of the physical properties of the fluid and the outer heat losses. The model equations of continuity, momentum and energy are numerically solved by the finite volume method. The pipe thickness, the Prandtl and the Reynolds numbers are fixed while the Grashof number is varied from 104to107. The results obtained show that the dynamic and thermal fields for mixed convection are qualitatively and quantitatively different from those of forced convection, and the local Nusselt number at the interface solid-fluid is not uniform: it has considerable axial and azimuthally variations. The effect of physical variables of the fluid depending on temperature is significant, which justifies its inclusion. The heat transfer is quantified by the local and average Nusselt numbers. We found that the average Nusselt number of solid-fluid interface of the duct increases with the increase of Grashof number. We have equally found out that the heat transfer is improved thanks to the consideration of the thermo dependence of the physical properties. We have tried modelling the average Nusselt number as a function of Richardson number. With the parameters used, the heat transfer is quantified by the correlation: NuA=12.0753 Ri0.156

  1. Rifkin strikes against gene transfer experiments.

    Science.gov (United States)

    Beardsley, T

    Jeremy Rifkin's lobbying organization, the Foundation on Economic Trends, has brought suit in U.S. District Court, together with the Humane Society of the U.S., to halt gene transfer experiments being carried out in livestock by the Department of Agriculture. The plaintiffs allege that the experiments--which entail injecting fusion genes that include the DNA structural sequence of the human growth hormone into the fertilized eggs of sheep and pigs--are morally objectionable, a potential threat to the biological stability of animal species, and likely to have undesirable economic and environmental consequences.

  2. Conjugative transfer of clostridial shuttle vectors from Escherichia coli to Clostridium difficile through circumvention of the restriction barrier.

    Science.gov (United States)

    Purdy, Des; O'Keeffe, Triona A T; Elmore, Michael; Herbert, Mike; McLeod, Anne; Bokori-Brown, Monika; Ostrowski, Anna; Minton, Nigel P

    2002-10-01

    Progress towards understanding the molecular basis of virulence in Clostridium difficile has been hindered by the lack of effective gene transfer systems. We have now, for the first time, developed procedures that may be used to introduce autonomously replicating vectors into this organism through their conjugative, oriT-based mobilization from Escherichia coli donors. Successful transfer was achieved through the use of a plasmid replicon isolated from an indigenous C. difficile plasmid, pCD6, and through the characterization and subsequent circumvention of host restriction/modification (RM) systems. The characterized replicon is the first C. difficile plasmid replicon to be sequenced and encodes a large replication protein (RepA) and a repetitive region composed of a 35 bp iteron sequence repeated seven times. Strain CD6 has two RM systems, CdiCD6I/M.CdiCD6I and CdiCD6II/M. CdiCD6II, with equivalent specificities to Sau96I/M. Sau96I (5'-GGNMCC-3') and MboI/M. MboI (5'-GMATC-3') respectively. A second strain (CD3) possesses a type IIs restriction enzyme, Cdi I, which cleaves the sequence 5'-CATCG-3' between the fourth and fifth nucleotide to give a blunt-ended fragment. This is the first time that an enzyme with this specificity has been reported. The sequential addition of this site to vectors showed that each site caused between a five- and 16-fold reduction in transfer efficiency. The transfer efficiencies achieved with both strains equated to between 1.0 x 10-6 and 5.5 x 10-5 transconjugants per donor.

  3. Peptide-conjugated micelles as a targeting nanocarrier for gene delivery

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wen Jen, E-mail: wjlin@ntu.edu.tw; Chien, Wei Hsuan [National Taiwan University, School of Pharmacy, Graduate Institute of Pharmaceutical Sciences (China)

    2015-09-15

    The aim of this study was to develop peptide-conjugated micelles possessing epidermal growth factor receptor (EGFR) targeting ability for gene delivery. A sequence-modified dodecylpeptide, GE11(2R), with enhancing EGF receptor binding affinity, was applied in this study as a targeting ligand. The active targeting micelles were composed of poly(d,l-lactide-co-glycolide)-poly(ethylene glycol) (PLGA-PEG) copolymer conjugated with GE11(2R)-peptide. The particle sizes of peptide-free and peptide-conjugated micelles were 277.0 ± 5.1 and 308.7 ± 14.5 nm, respectively. The peptide-conjugated micelles demonstrated the cellular uptake significantly higher than peptide-free micelles in EGFR high-expressed MDA-MB-231 and MDA-MB-468 cells due to GE11(2R)-peptide specificity. Furthermore, the peptide-conjugated micelles were able to encapsulate plasmid DNA and expressed cellular transfection higher than peptide-free micelles in EGFR high-expressed cells. The EGFR-targeting delivery micelles enhanced DNA internalized into cells and achieved higher cellular transfection in EGFR high-expressed cells.

  4. A conjugate gradient method for solving the non-LTE line radiation transfer problem

    Science.gov (United States)

    Paletou, F.; Anterrieu, E.

    2009-12-01

    This study concerns the fast and accurate solution of the line radiation transfer problem, under non-LTE conditions. We propose and evaluate an alternative iterative scheme to the classical ALI-Jacobi method, and to the more recently proposed Gauss-Seidel and successive over-relaxation (GS/SOR) schemes. Our study is indeed based on applying a preconditioned bi-conjugate gradient method (BiCG-P). Standard tests, in 1D plane parallel geometry and in the frame of the two-level atom model with monochromatic scattering are discussed. Rates of convergence between the previously mentioned iterative schemes are compared, as are their respective timing properties. The smoothing capability of the BiCG-P method is also demonstrated.

  5. Conjugate Heat Transfer Characteristics of Laminar Flows Through a Backward Facing Step Duct

    Directory of Open Access Journals (Sweden)

    Bayram CELİK

    2017-10-01

    Full Text Available Present study investigates the effects of solid to fluid conductivity ratio, Prandtl and Reynolds numbers, and solid wall thickness on conjugate heat transfer for a backward facing step duct with a conductive solid bottom wall. Although Kanna and Das performed a case study in 2006 for the same problem, the benchmark studies conducted later including the present one revealed that their results are arguable. Ramsak states in a study “Professor Kanna has confirmed in personal communication that their results are probably wrong”. The temperature and Nusselt number variations along the solid-fluid interface presented here are in excellent agreement with those obtained by Ramsak. The analyses presented here reveal that even though the decrease in Pr and the increase in solid to fluid conductivity ratio have similar global influence with the thinning wall on the interface temperature, the influence of the former parameters are limited in recirculation zone.

  6. Numerical simulation of conjugate heat transfer in electronic cooling and analysis based on field synergy principle

    International Nuclear Information System (INIS)

    Cheng, Y.P.; Lee, T.S.; Low, H.T.

    2008-01-01

    In this paper, the conjugate heat transfer in electronic cooling is numerically simulated with the newly proposed algorithm CLEARER on collocated grid. Because the solid heat source and substrate are isolated from the boundary, special attention is given to deal with the velocity and temperature in the solid region in the full field computation. The influence of openings on the substrate, heat source height and their distribution along the substrate on the maximum temperature and overall Nusselt number is investigated. The numerical results show that the openings on the substrate can enhance the heat transfer as well as increasing the heat source height, meanwhile, by arranging the heat sources coarsely in the front part and densely in the rear part of the substrate, the thermal performance can also be increased. Then the results are analyzed from the viewpoint of field synergy principle, and it is shown that the heat transfer improvement can all be attributed to the better synergy between the velocity field and temperature field, which may offer some guidance in the design of electronic devices

  7. On uncertainty and local sensitivity analysis for transient conjugate heat transfer problems

    International Nuclear Information System (INIS)

    Rauch, Christian

    2012-01-01

    The need for simulating real-world behavior of automobiles has led to more and more sophisticated models being added of various physical phenomena for being coupled together. This increases the number of parameters to be set and, consequently, the required knowledge of their relative importance for the solution and the theory behind them. Sensitivity and uncertainty analysis provides the knowledge of parameter importance. In this paper a thermal radiation solver is considered that performs conduction calculations and receives heat transfer coefficient and fluid temperate at a thermal node. The equations of local, discrete, and transient sensitivities for the conjugate heat transfer model solved by the finite difference method are being derived for some parameters. In the past, formulations for the finite element method have been published. This paper builds on the steady-state formulation published previously by the author. A numerical analysis on the stability of the solution matrix is being conducted. From those normalized sensitivity coefficients are calculated dimensionless uncertainty factors. On a simplified example the relative importance of the heat transfer modes at various locations is then investigated by those uncertainty factors and their changes over time

  8. Photoinduced charge and energy transfer in dye-doped conjugated polymers

    International Nuclear Information System (INIS)

    Veldman, Dirk; Bastiaansen, Jolanda J.A.M.; Langeveld-Voss, Bea M.W.; Sweelssen, Joergen; Koetse, Marc M.; Meskers, Stefan C.J.; Janssen, Rene A.J.

    2006-01-01

    Conjugated polymer-molecular dye blends of MDMO-PPV (poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene]) and PF1CVTP (poly[9,9-dioctylfluorene-2,7-diyl-alt-2,5-bis(2-thienyl-1-cyanovinyl) -1-(3',7= '-dimethyloctyloxy)-4-methoxybenzene-5'',5''-diyl]) with three dipyrrometheneboron difluoride (bodipy) dyes were studied by (time-resolved) fluorescence and photoinduced absorption spectroscopy to determine quantitatively the relation between the electronic HOMO and LUMO levels and the occurrence of energy or charge transfer after optical excitation. We find that for MDMO-PPV photoinduced charge transfer to the dyes occurs, while photoexcitation of PF1CVTP exclusively results in energy transfer. The differences can be rationalized by assuming that the energy of the charge separated state is 0.33-0.45 eV higher than the energy determined from oxidation and reduction potentials of donor and acceptor, respectively. This provides an important design rule to identify appropriate materials for polymer solar cells that can have a high open-circuit voltage

  9. Conjugate heat transfer LES of thermal mixing in a T-junction

    Energy Technology Data Exchange (ETDEWEB)

    Timperi, Antti, E-mail: antti.timperi@vtt.fi

    2014-07-01

    Highlights: • Turbulent mixing of hot and cold water in a T-junction is studied with LES including conjugate heat transfer. • The numerical simulations are in good agreement with experimental data in the bulk of the flow. • Comparison of different inlet and wall boundary conditions shows significant differences only near walls. • Effects of mesh and flow velocity on the velocity and temperature fluctuations are also considered. - Abstract: Turbulent mixing of hot and cold fluids may lead to high-cycle thermal fatigue in piping of nuclear power plants. In this work, the mixing in a T-junction experiment is studied by large-eddy simulation (LES). Conjugate heat transfer (CHT) between fluid and pipe wall is studied by replacing the plexiglass pipe of the experiment with a steel one. Different inlet and wall boundary conditions are first considered. Steady and turbulent inlets are compared, as well as adiabatic and CHT wall conditions. The turbulent inlets are created by using the vortex method which is validated for fully developed flow. The inlets are shown to have only small effect in bulk of the flow, but non-negligible effect near walls. The adiabatic and CHT cases show practically no difference in the logarithmic layer and upward, whereas near walls the difference becomes significant due to thermal inertia of the pipe wall. In bulk of the flow, the mean and fluctuating quantities show good agreement with the experiment. CHT simulations by using different meshes and flow velocities are then considered. A coarse mesh is found to yield qualitative agreement but significant errors in e.g. Reynolds stresses near walls. Temperature fluctuation intensity at the pipe inner surface is fairly similar for both meshes. Normalized profiles and spectra for different velocities are qualitatively similar, but some differences exist e.g. in distributions of wall temperature fluctuation intensity.

  10. Conjugative plasmid transfer in Xylella fastidiosa is dependent on tra and trb operon functions

    Science.gov (United States)

    The insect-transmitted plant pathogen Xylella fastidiosa is capable of efficient horizontal gene transfer and recombination, leading to diversity between strains and the categorization of X. fastidiosa into multiple subspecies. Although natural transformation is shown to occur at high rates in X. fa...

  11. Effect of bacterial distribution and activity on conjugal transfer on the phylloplane of the bush bean (Phaseolus vulgaris)

    DEFF Research Database (Denmark)

    Normander, Bo; Christensen, Bjarke Bak; Molin, Søren

    1998-01-01

    Conjugal plasmid transfer was examined on the phylloplane of bean (Phaseolus vulgaris) and related to the spatial distribution pattern and metabolic activity of the bacteria. The donor (Pseudomonas putida KT2442) harbored a derivative of the TOL plasmid, which conferred kanamycin resistance and had...

  12. Impact of nuclear lattice relaxation on the excitation energy transfer along a chain of pi-conjugated molecules

    NARCIS (Netherlands)

    Schmid, S.A.; Abbel, R.J.; Schenning, A.P.H.J.; Meijer, E.W.; Herz, L.M.

    2010-01-01

    We have investigated the extent to which delocalization of the ground-state and excited-state wave functions of a p-conjugated molecule affects the excitation energy transfer (EET) between such molecules. Using femtosecond photoluminescence spectroscopy, we experimentally monitored the EET along

  13. ICESag37, a Novel Integrative and Conjugative Element Carrying Antimicrobial Resistance Genes and Potential Virulence Factors in Streptococcus agalactiae.

    Science.gov (United States)

    Zhou, Kaixin; Xie, Lianyan; Han, Lizhong; Guo, Xiaokui; Wang, Yong; Sun, Jingyong

    2017-01-01

    ICE Sag37 , a novel integrative and conjugative element carrying multidrug resistance and potential virulence factors, was characterized in a clinical isolate of Streptococcus agalactiae . Two clinical strains of S. agalactiae , Sag37 and Sag158, were isolated from blood samples of new-borns with bacteremia. Sag37 was highly resistant to erythromycin and tetracycline, and susceptible to levofloxacin and penicillin, while Sag158 was resistant to tetracycline and levofloxacin, and susceptible to erythromycin. Transfer experiments were performed and selection was carried out with suitable antibiotic concentrations. Through mating experiments, the erythromycin resistance gene was found to be transferable from Sag37 to Sag158. Sma I-PFGE revealed a new Sma I fragment, confirming the transfer of the fragment containing the erythromycin resistance gene. Whole genome sequencing and sequence analysis revealed a mobile element, ICE Sag37 , which was characterized using several molecular methods and in silico analyses. ICE Sag37 was excised to generate a covalent circular intermediate, which was transferable to S. agalactiae . Inverse PCR was performed to detect the circular form. A serine family integrase mediated its chromosomal integration into rumA , which is a known hotspot for the integration of streptococcal ICEs. The integration site was confirmed using PCR. ICE Sag37 carried genes for resistance to multiple antibiotics, including erythromycin [ erm(B) ], tetracycline [ tet(O) ], and aminoglycosides [ aadE, aphA , and ant(6) ]. Potential virulence factors, including a two-component signal transduction system ( nisK/nisR ), were also observed in ICE Sag37 . S1-PFGE analysis ruled out the existence of plasmids. ICE Sag37 is the first ICE Sa2603 family-like element identified in S. agalactiae carrying both resistance and potential virulence determinants. It might act as a vehicle for the dissemination of multidrug resistance and pathogenicity among S. agalactiae .

  14. Solution of the conjugated heat transfer problem for the fuel elements assemblies

    International Nuclear Information System (INIS)

    Golba, V.S.; Ivanenko, I.J.; Zinina, G.A.

    1997-01-01

    The paper presents the assemblies conjugated heat conductivity problem calculation and experimental method. The method is based on the temperature superposition modified concept and subchannel method and allows to predict the fuel elements surface temperatures with availability of fuel elements inside structure of any complication caused by technological and working defects and with availability of depositions with low heat conductivity on the fuel elements surfaces. According to the method developed the partial solutions of the heat conductivity equation at the heat removal boundaries (solid-liquid) are found separately for the fuel elements and for the liquid. The heat conductivity equation partial solutions for the fuel elements are predicted by calculations. The coolant heat conductivity equation partial solution ('influence functions') data massif is obtained in present work experimentally in the fuel assembly model consists of 7 tube bundle of fuel elements imitators placed in right grating with relative grating step equal to 1.1 and cooled by eutectic alloy Pb-Bi. It is shown that 'subchannel prediction method' decreases the crosswise heat transfer in comparison with crosswise heat transfer, when the fuel element inside structure is taken into account. Also in the paper it is shown that it is possible to realize the assembly temperature prediction method suggested without carrying out the experiments in the assembly's model in order to get the external problem influence functions'. (author)

  15. Three dimensional conjugated heat transfer analysis in sodium fast reactor wire-wrapped fuel assembly

    International Nuclear Information System (INIS)

    Peniguel, C.; Rupp, I.; Juhel, JP.; Rolfo, S.; Guillaud, M.; Gervais, N.

    2009-01-01

    Fast reactors with liquid metal coolant have recently received a renewed interest owing to a more efficient usage of the primary uranium resources, and they are one of the proposal for the next Generation IV. In order to evaluate nuclear power plant design and safety, 3D analysis of the flow and heat transfer in a wire spacer fuel assembly are ongoing at EDF. The introduction of the wire wrapped spacers, helically wound along the pin axis, enhances the mixing of the coolant between sub-channels and prevents contact between the fuel pins. The mesh generation step constitutes a challenging task if a reasonable amount of cells in conjunction with a suitable spatial discretization is wanted. Several approaches have been investigated and will be presented. Quite complex global flow patterns are found using either k-ε or preferably Reynolds Stress turbulent models. Preliminary conjugated heat transfer calculations using a coupling between the finite element thermal code SYRTHES and the finite volume CFD code Code Saturne are also shown. (author)

  16. Reducible cationic lipids for gene transfer.

    Science.gov (United States)

    Wetzer, B; Byk, G; Frederic, M; Airiau, M; Blanche, F; Pitard, B; Scherman, D

    2001-01-01

    One of the main challenges of gene therapy remains the increase of gene delivery into eukaryotic cells. We tested whether intracellular DNA release, an essential step for gene transfer, could be facilitated by using reducible cationic DNA-delivery vectors. For this purpose, plasmid DNA was complexed with cationic lipids bearing a disulphide bond. This reduction-sensitive linker is expected to be reduced and cleaved in the reducing milieu of the cytoplasm, thus potentially improving DNA release and consequently transfection. The DNA--disulphide-lipid complexation was monitored by ethidium bromide exclusion, and the size of complexes was determined by dynamic light scattering. It was found that the reduction kinetics of disulphide groups in DNA--lipid complexes depended on the position of the disulphide linker within the lipid molecule. Furthermore, the internal structure of DNA--lipid particles was examined by small-angle X-ray scattering before and after lipid reduction. DNA release from lipid complexes was observed after the reduction of disulphide bonds of several lipids. Cell-transfection experiments suggested that complexes formed with selected reducible lipids resulted in up to 1000-fold higher reporter-gene activity, when compared with their analogues without disulphide bonds. In conclusion, reduction-sensitive groups introduced into cationic lipid backbones potentially allow enhanced DNA release from DNA--lipid complexes after intracellular reduction and represent a tool for improved vectorization. PMID:11389682

  17. Photoinduced electron transfer for an eosin-tyrosine conjugate. Activity of the tyrosinate anion in long-range electron transfer in a protein-like polymer matrix

    Energy Technology Data Exchange (ETDEWEB)

    Jones, G. II; Feng, Z.; Oh, C. [Boston Univ., MA (United States)

    1995-03-23

    The Xanthene dye eosin Y has been modified via a thiohydantoin link to the amine terminus of the amino acid L-tyrosine. Photochemical electron transfer involving the singlet state of the dye and the attached phenol-containing residue led to a reduction in eosin fluorescence quantum yield and lifetime for aqueous solutions at elevated pH. The conjugate provided an electron transfer product of relatively long lifetime (1 {mu}s range) observed by flash photolysis of solutions at pH 12.0, conditions under which the tyrosine moiety is ionized. The effects of binding of the conjugate in the polymer poly(vinylpyrrolidone) (PVP) on the rates of electron transfer of species of different charge type were examined. 30 refs., 5 figs., 1 tab.

  18. Analytical solutions of steady-state conjugate heat transfer in ducts with turbulent flow

    International Nuclear Information System (INIS)

    Cerqueira, Djane R.; Jian Su

    2007-01-01

    In this work, we present an approximate analytical solution of the steady-state conjugate heat transfer of turbulent forced convection in a circular pipe with wall axial heat conduction and external convective boundary conditions. Improved lumped differential approach based on two points Hermite approximation for integrals was applied to reduce the heat conduction equation in the solid into a second-order ordinary differential equation for the radially averaged solid temperature. The energy equation in the fluid was solved by applying the generalized integral transform technique (GITT). The Sturm-Lioville eigenproblem for fluid energy equation in the cylindrical coordinate system was solved by the sign-count method. The truncated system of N ordinary differential equations for transformed potentials of the fluid temperature and the second-order ordinary differential equation for radially averaged solid temperature formed a homogeneous system of N+2 ordinary differential equations, which was solved analytically. The effects of the fluid-solid thermal conductivity ratio on the Nusselt number, the average fluid and solid temperatures, and the fluid-solid interface temperature were investigated. (author)

  19. Numerical analysis for the conjugate heat transfer of skin under various temperature conditions of contrast therapy

    Energy Technology Data Exchange (ETDEWEB)

    Park, Da Ae; Oh, Han Nah; Choi, Hyoung Gwon [Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of); Jeon, Byoung Jin; Kim, Eun Jeoung; Lee, Seung Deok [Yonsei University, Seoul (Korea, Republic of)

    2015-11-15

    In this paper, the contrast therapy of skin was numerically investigated by solving the conjugate heat transfer problem. A finite volume method based on the SIMPLE algorithm was adopted to solve the axisymmetric incompressible Navier-Stokes equations, coupled with an energy equation. These equations are strongly coupled with the Pennes bio-heat equation in order to consider the effect of blood perfusion rate. We investigated the thermal response of skin at some selected depths for various input temperature profiles of a stimulator for contrast therapy. From the numerical simulations, the regions with cold/hot threshold temperatures were found for five input temperature profiles. It was shown that the temperature varies mildly for different input profiles as the depth increases, owing to the Pennes effect. The input temperatures for effective hot/cold stimulation of dermis layer were found to be 47 degrees C and 7 degrees C, respectively. The present numerical results will be used for finding an optimal temperature profile of a stimulator for contrast therapy.

  20. Transfer of copper from a chelated 67Cu-antibody conjugate to ceruloplasmin in lymphoma patients

    International Nuclear Information System (INIS)

    Mirick, Gary R.; O'Donnell, Robert T.; DeNardo, Sally J.; Shen Sui; Meares, Claude F.; DeNardo, Gerald L.

    1999-01-01

    The Lym-1 monoclonal antibody was conjugated with the bifunctional chelating agent 6-[p-(bromoacetamido)benzyl]-1,4,8,11-tetraazacyclotetradecane-N,N',N'',N' -tetraacetic acid (BAT), using 2IT as a linker, and radiolabeled with 67 Cu to make the radiopharmaceutical, 67 Cu-2IT-BAT-Lym-1. Ten patients received a total of 18 doses of 67 Cu-2IT-BAT-Lym-1 as targeted, systemic radiotherapy. The beta phase of blood clearance, when corrected for 67 Cu decay, was positive or flat, a phenomenon not observed in similar patients treated with 131 I-Lym-1. The flat beta phase of blood clearance suggested recycling of 67 Cu from 67 Cu-2IT-BAT-Lym-1 to another plasma protein. Therefore, the amount of 67 Cu transferred from the radiopharmaceutical to CP, Alb, and TF was measured using affinity-purified polyclonal antibodies. The fraction of plasma 67 Cu precipitated by anti-human CP increased daily; most blood radioactivity was 67 Cu-CP after a median of 4 days (range 2-7 days). The transfer of 67 Cu to CP was observed in all patients and was consistent from dose to dose within the same patient. An average of 2.8±1.5% (range 0.8-7.8%) of the 67 Cu dose (%ID) was transferred to CP. The release rate of 67 Cu-CP from the liver into the blood was 0.9±0.4 %ID/day for the first 3 days. The 67 Cu-CP effective clearance half-life was 3.7 ± 0.7 days. Subtraction of the 67 Cu-CP activity from the total blood radioactivity yielded a biphasic blood clearance similar to that obtained for patients given 131 I-Lym-1. Cu-67-CP increased the AUC for whole blood by 24 ± 10%. The %ID of 67 Cu recycled correlated with GGT, ALT, and alkaline phosphatase levels; r=0.958 (p 67 Cu-2IT-BAT-Lym-1 and recycles a small fraction of the 67 Cu, transferring it to CP

  1. The Application of Discontinuous Galerkin Methods in Conjugate Heat Transfer Simulations of Gas Turbines

    Directory of Open Access Journals (Sweden)

    Zeng-Rong Hao

    2014-11-01

    Full Text Available The performance of modern heavy-duty gas turbines is greatly determined by the accurate numerical predictions of thermal loading on the hot-end components. The purpose of this paper is: (1 to present an approach applying a novel numerical technique—the discontinuous Galerkin (DG method—to conjugate heat transfer (CHT simulations, develop the engineering-oriented numerical platform, and validate the feasibility of the methodology and tool preliminarily; and (2 to utilize the constructed platform to investigate the aerothermodynamic features of a typical transonic turbine vane with convection cooling. Fluid dynamic and solid heat conductive equations are discretized into explicit DG formulations. A centroid-expanded Taylor basis is adopted for various types of elements. The Bassi-Rebay method is used in the computation of gradients. A coupled strategy based on a data exchange process via numerical flux on interface quadrature points is simply devised. Additionally, various turbulence Reynolds-Averaged-Navier-Stokes (RANS models and the local-variable-based transition model γ-Reθ are assimilated into the integral framework, combining sophisticated modelling with the innovative algorithm. Numerical tests exhibit good consistency between computational and analytical or experimental results, demonstrating that the presented approach and tool can handle well general CHT simulations. Application and analysis in the turbine vane, focusing on features around where there in cluster exist shock, separation and transition, illustrate the effects of Bradshaw’s shear stress limitation and separation-induced-transition modelling. The general overestimation of heat transfer intensity behind shock is conjectured to be associated with compressibility effects on transition modeling. This work presents an unconventional formulation in CHT problems and achieves its engineering applications in gas turbines.

  2. Patterns of prokaryotic lateral gene transfers affecting parasitic microbial eukaryotes

    DEFF Research Database (Denmark)

    Alsmark, Cecilia; Foster, Peter G; Sicheritz-Pontén, Thomas

    2013-01-01

    BACKGROUND: The influence of lateral gene transfer on gene origins and biology in eukaryotes is poorly understood compared with those of prokaryotes. A number of independent investigations focusing on specific genes, individual genomes, or specific functional categories from various eukaryotes have...... approach to systematically investigate lateral gene transfer affecting the proteomes of thirteen, mainly parasitic, microbial eukaryotes, representing four of the six eukaryotic super-groups. All of the genomes investigated have been significantly affected by prokaryote-to-eukaryote lateral gene transfers...... indicated that lateral gene transfer does indeed affect eukaryotic genomes. However, the lack of common methodology and criteria in these studies makes it difficult to assess the general importance and influence of lateral gene transfer on eukaryotic genome evolution. RESULTS: We used a phylogenomic...

  3. Lentiviral Vector Gene Transfer to Porcine Airways

    Directory of Open Access Journals (Sweden)

    Patrick L Sinn

    2012-01-01

    Full Text Available In this study, we investigated lentiviral vector development and transduction efficiencies in well-differentiated primary cultures of pig airway epithelia (PAE and wild-type pigs in vivo. We noted gene transfer efficiencies similar to that observed for human airway epithelia (HAE. Interestingly, feline immunodeficiency virus (FIV-based vectors transduced immortalized pig cells as well as pig primary cells more efficiently than HIV-1–based vectors. PAE express TRIM5α, a well-characterized species-specific lentiviral restriction factor. We contrasted the restrictive properties of porcine TRIM5α against FIV- and HIV-based vectors using gain and loss of function approaches. We observed no effect on HIV-1 or FIV conferred transgene expression in response to porcine TRIM5α overexpression or knockdown. To evaluate the ability of GP64-FIV to transduce porcine airways in vivo, we delivered vector expressing mCherry to the tracheal lobe of the lung and the ethmoid sinus of 4-week-old pigs. One week later, epithelial cells expressing mCherry were readily detected. Our findings indicate that pseudotyped FIV vectors confer similar tropisms in porcine epithelia as observed in human HAE and provide further support for the selection of GP64 as an appropriate envelope pseudotype for future preclinical gene therapy studies in the porcine model of cystic fibrosis (CF.

  4. Radiopharmaceuticals to monitor the expression of transferred genes in gene transfer therapy

    International Nuclear Information System (INIS)

    Wiebe, L. I.

    1997-01-01

    The development and application of radiopharmaceuticals has, in many instances, been based on the pharmacological properties of therapeutic agents. The molecular biology-biotechnology revolution has had an important impact on treatment of diseases, in part through the reduced toxicity of 'biologicals', in part because of their specificity for interaction at unique molecular sites and in part because of their selective delivery to the target site. Immunotherapeutic approaches include the use of monoclonal antibodies (MABs), MAB-fragments and chemotactic peptides. Such agents currently form the basis of both diagnostic and immunotherapeutic radiopharmaceuticals. More recently, gene transfer techniques have been advanced to the point that a new molecular approach, gene therapy, has become a reality. Gene therapy offers an opportunity to attack disease at its most fundamental level. The therapeutic mechanism is based on the expression of a specific gene or genes, the product of which will invoke immunological, receptor-based or enzyme-based therapeutic modalities. Several approaches to gene therapy of cancer have been envisioned, the most clinically-advanced concepts involving the introduction of genes that will encode for molecular targets nor normally found in healthy mammalian cells. A number of gene therapy clinical trials are based on the introduction of the Herpes simplex virus type-1 (HSV-1) gene that encodes for viral thymidine kinase (tk+). Once HSV-1 tk+ is expressed in the target (cancer) cell, therapy can be effected by the administration of a highly molecularly-targeted and systemically non-toxic antiviral drug such as ganciclovir. The development of radiodiagnostic imaging in gene therapy will be reviewed, using HSV-1 tk+ and radioiodinated IVFRU as a basis for development of the theme. Molecular targets that could be exploited in gene therapy, other than tk+, will be identified

  5. Radiopharmaceuticals to monitor the expression of transferred genes in gene transfer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Wiebe, L I [University of Alberta, Edmonton (Canada). Noujaim Institute for Pharmaceutical Oncology Research

    1997-10-01

    The development and application of radiopharmaceuticals has, in many instances, been based on the pharmacological properties of therapeutic agents. The molecular biology-biotechnology revolution has had an important impact on treatment of diseases, in part through the reduced toxicity of `biologicals`, in part because of their specificity for interaction at unique molecular sites and in part because of their selective delivery to the target site. Immunotherapeutic approaches include the use of monoclonal antibodies (MABs), MAB-fragments and chemotactic peptides. Such agents currently form the basis of both diagnostic and immunotherapeutic radiopharmaceuticals. More recently, gene transfer techniques have been advanced to the point that a new molecular approach, gene therapy, has become a reality. Gene therapy offers an opportunity to attack disease at its most fundamental level. The therapeutic mechanism is based on the expression of a specific gene or genes, the product of which will invoke immunological, receptor-based or enzyme-based therapeutic modalities. Several approaches to gene therapy of cancer have been envisioned, the most clinically-advanced concepts involving the introduction of genes that will encode for molecular targets nor normally found in healthy mammalian cells. A number of gene therapy clinical trials are based on the introduction of the Herpes simplex virus type-1 (HSV-1) gene that encodes for viral thymidine kinase (tk+). Once HSV-1 tk+ is expressed in the target (cancer) cell, therapy can be effected by the administration of a highly molecularly-targeted and systemically non-toxic antiviral drug such as ganciclovir. The development of radiodiagnostic imaging in gene therapy will be reviewed, using HSV-1 tk+ and radioiodinated IVFRU as a basis for development of the theme. Molecular targets that could be exploited in gene therapy, other than tk+, will be identified

  6. Numerical analysis of unsteady conjugate heat transfer for initial evolution of thermal stratification in a curved pipe

    International Nuclear Information System (INIS)

    Jo, Jong Chull; Kim, Wee Kyung; Kim, Yun Il; Cho, Sang Jin; Choi, Seok Ki

    2000-01-01

    A detailed numerical analysis of initial evolution of thermal stratification in a curved pipe with a finite wall thickness is performed. A primary emphasis of the present study is placed on the investigation of the effect of existence of pipe wall thickness on the evolution of thermal stratification. A simple and convenient numerical method of treating the unsteady conjugate heat transfer in Cartesian as well as non-orthogonal coordinate systems is presented. The proposed unsteady conjugate heat transfer analysis method is implemented in a finite volume thermal-hydraulic computer code based on a cell-centered, non-staggered grid arrangement, the SIMPLEC algorithm and a higher-order bounded convection scheme. Calculations are performed for initial evolution of thermal stratification with high Richardson number in a curved pipe. The predicted results show that the thermally stratified flow and transient conjugate heat transfer in a curved pipe with a specified wall thickness can be satisfactorily analyzed by using the numerical method presented in this paper. As the result, the present analysis method is considered to be effective for the determination of transient temperature distributions in the wall of curved piping system subjected to internally thermal stratification. In addition, the method can be extended to be applicable for the simulation of turbulent flow of thermally stratified fluid

  7. Widespread of horizontal gene transfer in the human genome.

    Science.gov (United States)

    Huang, Wenze; Tsai, Lillian; Li, Yulong; Hua, Nan; Sun, Chen; Wei, Chaochun

    2017-04-04

    A fundamental concept in biology is that heritable material is passed from parents to offspring, a process called vertical gene transfer. An alternative mechanism of gene acquisition is through horizontal gene transfer (HGT), which involves movement of genetic materials between different species. Horizontal gene transfer has been found prevalent in prokaryotes but very rare in eukaryote. In this paper, we investigate horizontal gene transfer in the human genome. From the pair-wise alignments between human genome and 53 vertebrate genomes, 1,467 human genome regions (2.6 M bases) from all chromosomes were found to be more conserved with non-mammals than with most mammals. These human genome regions involve 642 known genes, which are enriched with ion binding. Compared to known horizontal gene transfer regions in the human genome, there were few overlapping regions, which indicated horizontal gene transfer is more common than we expected in the human genome. Horizontal gene transfer impacts hundreds of human genes and this study provided insight into potential mechanisms of HGT in the human genome.

  8. Gene transfer technology and genetic radioisotope targeting therapy

    International Nuclear Information System (INIS)

    Wang Jiaqiong; Wang Zizheng

    2004-01-01

    With deeper cognition about mechanisms of disease at the cellular and molecular level, gene therapy has become one of the most important research fields in medical molecular biology at present. Gene transfer technology plays an important role during the course of gene therapy, and further improvement should be made about vectors carrying target gene sequences. Also, gene survey is needed during gene therapy, and gene imaging is the most effective method. The combination of gene therapy and targeted radiotherapy, that is, 'Genetic Radioisotope Targeting Therapy', will be a novel approach to tumor gene therapy

  9. The BlcC (AttM) lactonase of Agrobacterium tumefaciens does not quench the quorum-sensing system that regulates Ti plasmid conjugative transfer.

    Science.gov (United States)

    Khan, Sharik R; Farrand, Stephen K

    2009-02-01

    The conjugative transfer of Agrobacterium plasmids is controlled by a quorum-sensing system consisting of TraR and its acyl-homoserine lactone (HSL) ligand. The acyl-HSL is essential for the TraR-mediated activation of the Ti plasmid Tra genes. Strains A6 and C58 of Agrobacterium tumefaciens produce a lactonase, BlcC (AttM), that can degrade the quormone, leading some to conclude that the enzyme quenches the quorum-sensing system. We tested this hypothesis by examining the effects of the mutation, induction, or mutational derepression of blcC on the accumulation of acyl-HSL and on the conjugative competence of strain C58. The induction of blc resulted in an 8- to 10-fold decrease in levels of extracellular acyl-HSL but in only a twofold decrease in intracellular quormone levels, a measure of the amount of active intracellular TraR. The induction or mutational derepression of blc as well as a null mutation in blcC had no significant effect on the induction of or continued transfer of pTiC58 from donors in any stage of growth, including stationary phase. In matings performed in developing tumors, wild-type C58 transferred the Ti plasmid to recipients, yielding transconjugants by 14 to 21 days following infection. blcC-null donors yielded transconjugants 1 week earlier, but by the following week, transconjugants were recovered at numbers indistinguishable from those of the wild type. Donors mutationally derepressed for blcC yielded transconjugants in planta at numbers 10-fold lower than those for the wild type at weeks 2 and 3, but by week 4, the two donors showed no difference in recoverable transconjugants. We conclude that BlcC has no biologically significant effect on Ti plasmid transfer or its regulatory system.

  10. Conjugated heat transfer of natural convection in pool with internal heat sources and convection in the tube

    International Nuclear Information System (INIS)

    Li Longjian; Liu Hongtao; Cui Wenzhi

    2007-01-01

    The conjugated heat transfer of natural convection in pool with internal heat source and the forced convection in the tube was analyzed, and the corresponding three-dimensional physical and mathematical model was proposed. A control volume based finite element method was employed to solve numerically the problem. The computations were performed for different internal heat source intensity of the pool and the different flow velocity in the tube. The computed heat transfer coefficients on the inner and outer wall showed well consistency of those calculated with the empirical correlations. Compared with the measured total heat transfer coefficients between the fluids in and out of the tube, the computed ones showed also the well consistency, which implied that the numerical model proposed in this paper was reliable. The research results revealed that the total heat transfer coefficients between the fluids were strongly affected by the internal heat source intensity of the pool liquid and the flow velocity in the tube. (authors)

  11. Pollen irradiation and possible gene transfer in Nicotiana species

    DEFF Research Database (Denmark)

    Engvild, Kjeld Christensen

    1985-01-01

    , and Petunia parodii with irradiated pollen from N. alata and Petunia hybrida showed no evidence of gene transfer, nor did experiments with irradiated mentor pollen. This indicates that gene transfer with irradiated pollen between non-crossing species or between species giving sterile hybrids is probably...

  12. Social behaviour and decision making in bacterial conjugation

    Directory of Open Access Journals (Sweden)

    Günther eKoraimann

    2014-04-01

    Full Text Available Bacteria frequently acquire novel genes by HGT (horizontal gene transfer. HGT through the process of bacterial conjugation is highly efficient and depends on the presence of conjugative plasmids (CPs or integrated conjugative elements (ICEs that provide the necessary genes for DNA transmission. This review focuses on recent advancements in our understanding of ssDNA transfer systems and regulatory networks ensuring timely and spatially controlled DNA transfer (tra gene expression. As will become obvious by comparing different systems, by default, tra genes are shut off in cells in which conjugative elements are present. Only when conditions are optimal, donor cells – through epigenetic alleviation of negatively acting roadblocks and direct stimulation of DNA transfer genes – become transfer competent. These transfer competent cells have developmentally transformed into specialized cells capable of secreting ssDNA via a T4S (type IV secretion complex directly into recipient cells. Intriguingly, even under optimal conditions, only a fraction of the population undergoes this transition, a finding that indicates specialization and cooperative, social behavior. Thereby, at the population level, the metabolic burden and other negative consequences of tra gene expression are greatly reduced without compromising the ability to horizontally transfer genes to novel bacterial hosts. This undoubtedly intelligent strategy may explain why conjugative elements – CPs and ICEs – have been successfully kept in and evolved with bacteria to constitute a major driving force of bacterial evolution.

  13. Design of PEI-conjugated bio-reducible polymer for efficient gene delivery.

    Science.gov (United States)

    Nam, Joung-Pyo; Kim, Soyoung; Kim, Sung Wan

    2018-07-10

    The poly(cystaminebis(acrylamide)-diaminohexane) (poly(CBA-DAH)) was designed previously as a bio-reducible efficient gene delivery carrier. However, the high weight ratio required to form the polyplexes between poly(CBA-DAH) with pDNA is still a problem that needs to be addressed. To solve this problem and increase the transfection efficiency, poly(ethylenimine) (PEI, 1.8 kDa) was conjugated to poly(CBA-DAH) via disulfide bond. The PEI conjugated poly(CBA-DAH) (PCDP) can bind with pDNA at a very low weight ratio of 0.5 and above, like PEI 25 kDa, and form the polyplexes with nano-size (102-128 nm) and positive surface charge (27-34 mV). PCDP and PCDP polyplexes had negligible cytotoxicity and indicated similar or better cellular uptake than the comparison groups such as PEI 25 kDa and Lipofectamine® polyplexes. To confirm the transfection efficiency, the plasmid DNA (pDNA) encoded with the luciferase reporter gene (gWiz-Luc) and green fluorescent protein reporter gene (GFP) were used and treated with PCDP into the A549, Huh-7, and Mia PaCa-2 cells. PCDP/pDNA polyplexes showed highest transfection efficiency in all tested cell lines. In the luciferase assay, PCDP polyplexes showed 10.2 times higher gene transfection efficiency than Lipofectamine® polyplexes in mimic in vivo conditions (30% FBS, A549 cells). The VEGF siRNA expressing plasmid (pshVEGF), which is constructed as a therapeutic gene by our previous work, was delivered by PCDP into the cancer cells. The VEGF gene expression of PCDP/pshVEGF polyplexes was dramatically lower than control and the VEGF gene silencing efficiencies of PCDP/pshVEGF (w/w; 10/1) polyplexes were 54% (A549 cells), 77% (Huh-7 cells), and 66% (Mia PaCa-2 cells). In addition, PCDP/pshVEGF had reduced cell viability rates of about 31% (A549 cells), 39% (Huh-7 cells), and 42% (Mia PaCa-2 cells) and showed better results than all comparison groups. In the transfection efficiency and VEGF silencing assay, PCDP polyplexes showed

  14. The chromosomal organization of horizontal gene transfer in bacteria.

    Science.gov (United States)

    Oliveira, Pedro H; Touchon, Marie; Cury, Jean; Rocha, Eduardo P C

    2017-10-10

    Bacterial adaptation is accelerated by the acquisition of novel traits through horizontal gene transfer, but the integration of these genes affects genome organization. We found that transferred genes are concentrated in only ~1% of the chromosomal regions (hotspots) in 80 bacterial species. This concentration increases with genome size and with the rate of transfer. Hotspots diversify by rapid gene turnover; their chromosomal distribution depends on local contexts (neighboring core genes), and content in mobile genetic elements. Hotspots concentrate most changes in gene repertoires, reduce the trade-off between genome diversification and organization, and should be treasure troves of strain-specific adaptive genes. Most mobile genetic elements and antibiotic resistance genes are in hotspots, but many hotspots lack recognizable mobile genetic elements and exhibit frequent homologous recombination at flanking core genes. Overrepresentation of hotspots with fewer mobile genetic elements in naturally transformable bacteria suggests that homologous recombination and horizontal gene transfer are tightly linked in genome evolution.Horizontal gene transfer (HGT) is an important mechanism for genome evolution and adaptation in bacteria. Here, Oliveira and colleagues find HGT hotspots comprising  ~ 1% of the chromosomal regions in 80 bacterial species.

  15. Improvement Method of Gene Transfer in Kappaphycus Alvarezii

    OpenAIRE

    Triana, St. Hidayah; Alimuddin,; Widyastuti, Utut; Suharsono,; Suryati, Emma; Parenrengi, Andi

    2016-01-01

    Method of foreign gene transfer in red seaweed Kappaphycus alvarezii has been reported, however, li-mited number of transgenic F0 (broodstock) was obtained. This study was conducted to improve the method of gene transfer mediated by Agrobacterium tumefaciens in order to obtain high percentage of K. alvarezii transgenic. Superoxide dismutase gene from Melastoma malabatrichum (MmCu/Zn-SOD) was used as model towards increasing adaptability of K. alvarezii to environmental stress. The treat-ment...

  16. Type 3 Fimbriae Encoded on Plasmids Are Expressed from a Unique Promoter without Affecting Host Motility, Facilitating an Exceptional Phenotype That Enhances Conjugal Plasmid Transfer

    DEFF Research Database (Denmark)

    Madsen, Jonas Stenlokke; Riber, Leise; Kot, Witold

    2016-01-01

    Horizontal gene transfer (HGT), the transmission of genetic material to a recipient that is not the progeny of the donor, is fundamental in bacterial evolution. HGT is often mediated by mobile genetic elements such as conjugative plasmids, which may be in conflict with the chromosomal elements...... of the genome because they are independent replicons that may petition their own evolutionary strategy. Here we study differences between type 3 fimbriae encoded on wild type plasmids and in chromosomes. Using known and newly characterized plasmids we show that the expression of type 3 fimbriae encoded...... on plasmids is systematically different, as MrkH, a c-di-GMP dependent transcriptional activator is not needed for strong expression of the fimbriae. MrkH is required for expression of type 3 fimbriae of the Klebsiella pneumoniae chromosome, wherefrom the fimbriae operon (mrkABCDF) of plasmids is believed...

  17. Pleiotropic functions of magnetic nanoparticles for ex vivo gene transfer.

    Science.gov (United States)

    Kami, Daisuke; Kitani, Tomoya; Kishida, Tsunao; Mazda, Osam; Toyoda, Masashi; Tomitaka, Asahi; Ota, Satoshi; Ishii, Ryuga; Takemura, Yasushi; Watanabe, Masatoshi; Umezawa, Akihiro; Gojo, Satoshi

    2014-08-01

    Gene transfer technique has various applications, ranging from cellular biology to medical treatments for diseases. Although nonviral vectors, such as episomal vectors, have been developed, it is necessary to improve their gene transfer efficacy. Therefore, we attempted to develop a highly efficient gene delivery system combining an episomal vector with magnetic nanoparticles (MNPs). In comparison with the conventional method using transfection reagents, polyethylenimine-coated MNPs introduced episomal vectors more efficiently under a magnetic field and could express the gene in mammalian cells with higher efficiency and for longer periods. This novel in vitro separation method of gene-introduced cells utilizing the magnetic property of MNPs significantly facilitated the separation of cells of interest. Transplanted cells in vivo were detected using magnetic resonance. These results suggest that MNPs play multifunctional roles in ex vivo gene transfer, such as improvement of gene transfer efficacy, separation of cells, and detection of transplanted cells. This study convincingly demonstrates enhanced efficiency of gene transfer via magnetic nanoparticles. The method also enables magnetic sorting of cells positive for the transferred gene, and in vivo monitoring of the process with MRI. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Transfer of engineered genes from crop to wild plants

    DEFF Research Database (Denmark)

    Bagger Jørgensen, Rikke; Hauser, T.P.; Mikkelsen, T.R.

    1996-01-01

    The escape of engineered genes - genes inserted using recombinant DNA techniques - from cultivated plants to wild or weedy relatives has raised concern about possible risks to the environment or to health. The media have added considerably to public concern by suggesting that such gene escape...... is a new and rather unexpected phenomenon. However, transfer of engineered genes between plants is not at-all surprising, because it is mediated by exactly the same mechanisms as those responsible for transferring endogenous plant genes: it takes place by sexual crosses, with pollen as the carrier...

  19. A recently transferred cluster of bacterial genes in Trichomonas vaginalis - lateral gene transfer and the fate of acquired genes

    Science.gov (United States)

    2014-01-01

    Background Lateral Gene Transfer (LGT) has recently gained recognition as an important contributor to some eukaryote proteomes, but the mechanisms of acquisition and fixation in eukaryotic genomes are still uncertain. A previously defined norm for LGTs in microbial eukaryotes states that the majority are genes involved in metabolism, the LGTs are typically localized one by one, surrounded by vertically inherited genes on the chromosome, and phylogenetics shows that a broad collection of bacterial lineages have contributed to the transferome. Results A unique 34 kbp long fragment with 27 clustered genes (TvLF) of prokaryote origin was identified in the sequenced genome of the protozoan parasite Trichomonas vaginalis. Using a PCR based approach we confirmed the presence of the orthologous fragment in four additional T. vaginalis strains. Detailed sequence analyses unambiguously suggest that TvLF is the result of one single, recent LGT event. The proposed donor is a close relative to the firmicute bacterium Peptoniphilus harei. High nucleotide sequence similarity between T. vaginalis strains, as well as to P. harei, and the absence of homologs in other Trichomonas species, suggests that the transfer event took place after the radiation of the genus Trichomonas. Some genes have undergone pseudogenization and degradation, indicating that they may not be retained in the future. Functional annotations reveal that genes involved in informational processes are particularly prone to degradation. Conclusions We conclude that, although the majority of eukaryote LGTs are single gene occurrences, they may be acquired in clusters of several genes that are subsequently cleansed of evolutionarily less advantageous genes. PMID:24898731

  20. Hepatoma targeting peptide conjugated bio-reducible polymer complexed with oncolytic adenovirus for cancer gene therapy.

    Science.gov (United States)

    Choi, Joung-Woo; Kim, Hyun Ah; Nam, Kihoon; Na, Youjin; Yun, Chae-Ok; Kim, SungWan

    2015-12-28

    Despite adenovirus (Ad) vector's numerous advantages for cancer gene therapy, such as high ability of endosomal escape, efficient nuclear entry mechanism, and high transduction, and therapeutic efficacy, tumor specific targeting and antiviral immune response still remain as a critical challenge in clinical setting. To overcome these obstacles and achieve cancer-specific targeting, we constructed tumor targeting bioreducible polymer, an arginine grafted bio-reducible polymer (ABP)-PEG-HCBP1, by conjugating PEGylated ABP with HCBP1 peptides which has high affinity and selectivity towards hepatoma. The ABP-PEG-HCBP1-conjugated replication incompetent GFP-expressing ad, (Ad/GFP)-ABP-PEG-HCBP1, showed a hepatoma cancer specific uptake and transduction compared to either naked Ad/GFP or Ad/GFP-ABP. Competition assays demonstrated that Ad/GFP-ABP-PEG-HCBP1-mediated transduction was specifically inhibited by HCBP1 peptide rather than coxsackie and adenovirus receptor specific antibody. In addition, ABP-PEG-HCBP1 can protect biological activity of Ad against serum, and considerably reduced both innate and adaptive immune response against Ad. shMet-expressing oncolytic Ad (oAd; RdB/shMet) complexed with ABP-PEG-HCBP1 delivered oAd efficiently into hepatoma cancer cells. The oAd/ABP-PEG-HCBP1 demonstrated enhanced cancer cell killing efficacy in comparison to oAd/ABP complex. Furthermore, Huh7 and HT1080 cancer cells treated with oAd/shMet-ABP-PEG-HCBP1 complex had significantly decreased Met and VEGF expression in hepatoma cancer, but not in non-hepatoma cancer. In sum, these results suggest that HCBP1-conjugated bioreducible polymer could be used to deliver oncolytic Ad safely and efficiently to treat hepatoma. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Smooth and robust solutions for Dirichlet boundary control of fluid-solid conjugate heat transfer problems

    KAUST Repository

    Yan, Yan

    2015-01-01

    We study a new optimization scheme that generates smooth and robust solutions for Dirichlet velocity boundary control (DVBC) of conjugate heat transfer (CHT) processes. The solutions to the DVBC of the incompressible Navier-Stokes equations are typically nonsmooth, due to the regularity degradation of the boundary stress in the adjoint Navier-Stokes equations. This nonsmoothness is inherited by the solutions to the DVBC of CHT processes, since the CHT process couples the Navier-Stokes equations of fluid motion with the convection-diffusion equations of fluid-solid thermal interaction. Our objective in the CHT boundary control problem is to select optimally the fluid inflow profile that minimizes an objective function that involves the sum of the mismatch between the temperature distribution in the fluid system and a prescribed temperature profile and the cost of the control.Our strategy to resolve the nonsmoothness of the boundary control solution is based on two features, namely, the objective function with a regularization term on the gradient of the control profile on both the continuous and the discrete levels, and the optimization scheme with either explicit or implicit smoothing effects, such as the smoothed Steepest Descent and the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) methods. Our strategy to achieve the robustness of the solution process is based on combining the smoothed optimization scheme with the numerical continuation technique on the regularization parameters in the objective function. In the section of numerical studies, we present two suites of experiments. In the first one, we demonstrate the feasibility and effectiveness of our numerical schemes in recovering the boundary control profile of the standard case of a Poiseuille flow. In the second one, we illustrate the robustness of our optimization schemes via solving more challenging DVBC problems for both the channel flow and the flow past a square cylinder, which use initial

  2. CRISPR-Cas and Restriction-Modification Act Additively against Conjugative Antibiotic Resistance Plasmid Transfer in Enterococcus faecalis.

    Science.gov (United States)

    Price, Valerie J; Huo, Wenwen; Sharifi, Ardalan; Palmer, Kelli L

    2016-01-01

    Enterococcus faecalis is an opportunistic pathogen and a leading cause of nosocomial infections. Conjugative pheromone-responsive plasmids are narrow-host-range mobile genetic elements (MGEs) that are rapid disseminators of antibiotic resistance in the faecalis species. Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas and restriction-modification confer acquired and innate immunity, respectively, against MGE acquisition in bacteria. Most multidrug-resistant E. faecalis isolates lack CRISPR-Cas and possess an orphan locus lacking cas genes, CRISPR2, that is of unknown function. Little is known about restriction-modification defense in E. faecalis. Here, we explore the hypothesis that multidrug-resistant E. faecalis strains are immunocompromised. We assessed MGE acquisition by E. faecalis T11, a strain closely related to the multidrug-resistant hospital isolate V583 but which lacks the ~620 kb of horizontally acquired genome content that characterizes V583. T11 possesses the E. faecalis CRISPR3-cas locus and a predicted restriction-modification system, neither of which occurs in V583. We demonstrate that CRISPR-Cas and restriction-modification together confer a 4-log reduction in acquisition of the pheromone-responsive plasmid pAM714 in biofilm matings. Additionally, we show that the orphan CRISPR2 locus is functional for genome defense against another pheromone-responsive plasmid, pCF10, only in the presence of cas9 derived from the E. faecalis CRISPR1-cas locus, which most multidrug-resistant E. faecalis isolates lack. Overall, our work demonstrated that the loss of only two loci led to a dramatic reduction in genome defense against a clinically relevant MGE, highlighting the critical importance of the E. faecalis accessory genome in modulating horizontal gene transfer. Our results rationalize the development of antimicrobial strategies that capitalize upon the immunocompromised status of multidrug-resistant E. faecalis. IMPORTANCE

  3. LATERAL GENE TRANSFER AND THE HISTORY OF BACTERIAL GENOMES

    Energy Technology Data Exchange (ETDEWEB)

    Howard Ochman

    2006-02-22

    The aims of this research were to elucidate the role and extent of lateral transfer in the differentiation of bacterial strains and species, and to assess the impact of gene transfer on the evolution of bacterial genomes. The ultimate goal of the project is to examine the dynamics of a core set of protein-coding genes (i.e., those that are distributed universally among Bacteria) by developing conserved primers that would allow their amplification and sequencing in any bacterial taxa. In addition, we adopted a bioinformatic approach to elucidate the extent of lateral gene transfer in sequenced genome.

  4. Validation of ANSYS CFX for gas and liquid metal flows with conjugate heat transfer within the European project THINS

    Energy Technology Data Exchange (ETDEWEB)

    Papukchiev, A., E-mail: angel.papukchiev@grs.de; Buchholz, S.

    2017-02-15

    Highlights: • ANSYS CFX is validated for gas and liquid metal flows. • L-STAR and TALL-3D experiments are simulated. • Complex flow and heat transfer phenomena are modelled. • Conjugate heat transfer has to be considered in CFD analyses. - Abstract: Within the FP7 European project THINS (Thermal Hydraulics of Innovative Nuclear Systems), numerical tools for the simulation of the thermal-hydraulics of next generation rector systems were developed, applied and validated for innovative coolants. The Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH participated in THINS with activities related to the development and validation of computational fluid dynamics (CFD) and coupled System Thermal Hydraulics (STH) – CFD codes. High quality measurements from the L-STAR and TALL-3D experiments were used to assess the numerical results. Two-equation eddy viscosity and scale resolving turbulence models were used in the validation process of ANSYS CFX for gas and liquid metal flows with conjugate heat transfer. This paper provides a brief overview on the main results achieved at GRS within the project.

  5. Trends and barriers to lateral gene transfer in prokaryotes.

    Science.gov (United States)

    Popa, Ovidiu; Dagan, Tal

    2011-10-01

    Gene acquisition by lateral gene transfer (LGT) is an important mechanism for natural variation among prokaryotes. Laboratory experiments show that protein-coding genes can be laterally transferred extremely fast among microbial cells, inherited to most of their descendants, and adapt to a new regulatory regime within a short time. Recent advance in the phylogenetic analysis of microbial genomes using networks approach reveals a substantial impact of LGT during microbial genome evolution. Phylogenomic networks of LGT among prokaryotes reconstructed from completely sequenced genomes uncover barriers to LGT in multiple levels. Here we discuss the kinds of barriers to gene acquisition in nature including physical barriers for gene transfer between cells, genomic barriers for the integration of acquired DNA, and functional barriers for the acquisition of new genes. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Interface model conditions for a non-equilibrium heat transfer model for conjugate fluid/porous/solid domains

    International Nuclear Information System (INIS)

    Betchen, L.J.; Straatman, A.G.

    2005-01-01

    A mathematical and numerical model for the treatment of conjugate fluid flow and heat transfer problems in domains containing pure fluid, porous, and pure solid regions has been developed. The model is general and physically reasoned, and allows for local thermal non-equilibrium in the porous region. The model is developed for implementation on a simple collocated finite volume grid. Of particular novelty are the conditions implemented at the interfaces between porous regions, and those containing a pure solid or pure fluid. The model is validated by simulation of a three-dimensional porous plug problem for which experimental results are available. (author)

  7. Conjugate gradient determination of optimal plane changes for a class of three-impulse transfers between noncoplanar circular orbits

    Science.gov (United States)

    Burrows, R. R.

    1972-01-01

    A particular type of three-impulse transfer between two circular orbits is analyzed. The possibility of three plane changes is recognized, and the problem is to optimally distribute these plane changes to minimize the sum of the individual impulses. Numerical difficulties and their solution are discussed. Numerical results obtained from a conjugate gradient technique are presented for both the case where the individual plane changes are unconstrained and for the case where they are constrained. Possibly not unexpectedly, multiple minima are found. The techniques presented could be extended to the finite burn case, but primarily the contents are addressed to preliminary mission design and vehicle sizing.

  8. Synthesis and characterization of PEG-conjugated quaternized chitosan and its application as a gene vector.

    Science.gov (United States)

    Zhang, Xi; Yao, Juan; Zhang, Lihong; Fang, Jianguo; Bian, Fengling

    2014-03-15

    Poly(ethylene glycol)-conjugated N-(2-hydroxy) propyl-3-trimethyl ammonium chitosan chloride (PHTAC) derivatives were prepared by incorporating PEG molecules onto quaternized chitosan backbone. The copolymers were characterized by FTIR, (1)H NMR and XRD. Agarose gel retardation assay indicated that PHTAC had good plasmid DNA (pDNA) binding capability and the particle sizes of PHTAC/pDNA complexes determined by DLS were about 200 nm. Cytotoxicity assays in HeLa and 293T cells showed that PHTAC had low cytotoxicity. In vitro luciferase assay showed that PHTAC with PEGylation degree of 9% (PHTAC-1) had good transfection efficiency about 5.3-fold higher than quaternized chitosan, which was comparable with PEI (25 kDa). These results suggest that PHTAC-1 is a promising candidate as an efficient nonviral gene vector. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Evolution of glutamate dehydrogenase genes: evidence for lateral gene transfer within and between prokaryotes and eukaryotes

    Directory of Open Access Journals (Sweden)

    Roger Andrew J

    2003-06-01

    Full Text Available Abstract Background Lateral gene transfer can introduce genes with novel functions into genomes or replace genes with functionally similar orthologs or paralogs. Here we present a study of the occurrence of the latter gene replacement phenomenon in the four gene families encoding different classes of glutamate dehydrogenase (GDH, to evaluate and compare the patterns and rates of lateral gene transfer (LGT in prokaryotes and eukaryotes. Results We extend the taxon sampling of gdh genes with nine new eukaryotic sequences and examine the phylogenetic distribution pattern of the various GDH classes in combination with maximum likelihood phylogenetic analyses. The distribution pattern analyses indicate that LGT has played a significant role in the evolution of the four gdh gene families. Indeed, a number of gene transfer events are identified by phylogenetic analyses, including numerous prokaryotic intra-domain transfers, some prokaryotic inter-domain transfers and several inter-domain transfers between prokaryotes and microbial eukaryotes (protists. Conclusion LGT has apparently affected eukaryotes and prokaryotes to a similar extent within the gdh gene families. In the absence of indications that the evolution of the gdh gene families is radically different from other families, these results suggest that gene transfer might be an important evolutionary mechanism in microbial eukaryote genome evolution.

  10. Integrated conjugate heat transfer analysis method for in-vessel retention with external reactor vessel cooling - 15477

    International Nuclear Information System (INIS)

    Park, J.W.; Bae, J.H.; Seol, W.C.

    2015-01-01

    An integrated conjugate heat transfer analysis method for the thermal integrity of a reactor vessel under external reactor vessel cooling conditions is developed to resolve light metal layer focusing effect issue. The method calculates steady-state 3-dimensional temperature distribution of a reactor vessel using coupled conjugate heat transfer between in-vessel 3-layered stratified corium (metallic pool, oxide pool and heavy metal) and polar-angle dependent boiling heat transfer at the outer surface of a reactor vessel. The 3-layer corium heat transfer model is utilizing lumped-parameter thermal-resistance circuit method and ex-vessel boiling regimes are parametrically considered. The thermal integrity of a reactor vessel is addressed in terms of un-molten thickness profile. The vessel 3-dimensional heat conduction is validated against a commercial code. It is found that even though the internal heat flux from the metal layer goes far beyond critical heat flux (CHF) the heat flux from the outermost nodes of the vessel may be maintained below CHF due to massive vessel heat diffusion. The heat diffusion throughout the vessel is more pronounced for relatively low heat generation rate in an oxide pool. Parametric calculations are performed considering thermal conditions such as peak heat flux from a light metal layer, heat generation in an oxide pool and external boiling conditions. The major finding is that the most crucial factor for success of in-vessel retention is not the mass of the molten light metal above the oxide pool but the heat generation rate inside the oxide pool and the 3-dimensional vessel heat transfer provides a much larger minimum vessel wall thickness. (authors)

  11. A standardized conjugation protocol to asses antibiotic resistance transfer between lactococcal species

    DEFF Research Database (Denmark)

    Lampkowska, Joanna; Feld, Louise; Monaghan, Aine

    2008-01-01

    Optimal conditions and a standardized method for conjugation between two model lactococcal strains, Lactococcus lactis SH4174 (pAM beta 1-containing, erythromycin resistant donor) and L. lactis Bu2-60 (plasmid-free, erythromycin sensitive recipient), were developed and tested in a inter-laborator...

  12. A standardized conjugation protocol to assess antibiotic resistance transfer between lactococcal species

    NARCIS (Netherlands)

    Lampkowska, J.; Feld, L.; Monaghan, A.; Toomey, N.; Schjørring, S.; Jacobsen, B.; Voet, van der H.; Andersen, S.R.; Bolton, D.; Aarts, H.J.M.; Krogfelt, K.A.; Wilcks, A.; Bardowski, J.K.

    2008-01-01

    Optimal conditions and a standardized method for conjugation between two model lactococcal strains, Lactococcus lactis SH4174 (pAMbeta1-containing, erythromycin resistant donor) and L. lactis Bu2-60 (plasmid-free, erythromycin sensitive recipient), were developed and tested in a inter-laboratory

  13. High-level fluoroquinolone resistant Salmonella enterica serovar Kentucky ST198 epidemic clone with IncA/C conjugative plasmid carrying bla(CTX-M-25) gene.

    Science.gov (United States)

    Wasyl, Dariusz; Kern-Zdanowicz, Izabela; Domańska-Blicharz, Katarzyna; Zając, Magdalena; Hoszowski, Andrzej

    2015-01-30

    Multidrug resistant Salmonella Kentucky strains have been isolated from turkeys in Poland since 2009. Multiple mutations within chromosomal genes gyrA and parC were responsible for high-level ciprofloxacin resistance. One of the isolates was extended spectrum β-lactamase- (ESBL) positive: the strain 1643/2010 carried a conjugative 167,779 bps plasmid of IncA/C family. The sequence analysis revealed that it carried a blaCTX-M-25 gene and an integron with another β-lactamase encoding gene-blaOXA-21. This is the first known report of a CTX-M-25 encoding gene both in Poland and in Salmonella Kentucky world-wide, as well as in the IncA/C plasmid. Analysis of the integron showed a novel arrangement of gene cassettes-aacA4, aacC-A1 and blaOXA-21 where the latter might result from an intergeneric gene transfer. The study confirmed Salmonella Kentucky population isolated in Poland belongs to global epidemics of high level fluoroquinolone resistant clone ST198 that can carry rare β-lactamase genes. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. A new mosaic integrative and conjugative element from Streptococcus agalactiae carrying resistance genes for chloramphenicol (catQ) and macrolides [mef(I) and erm(TR)].

    Science.gov (United States)

    Morici, Eleonora; Simoni, Serena; Brenciani, Andrea; Giovanetti, Eleonora; Varaldo, Pietro E; Mingoia, Marina

    2017-01-01

    To investigate the genetic basis of catQ-mediated chloramphenicol resistance in Streptococcus agalactiae. Two clinical strains of catQ-positive chloramphenicol-resistant S. agalactiae (Sag236 and Sag403) were recently isolated, typed (MLST, PFGE pulsotypes, capsular types) and their antibiotic resistances investigated by phenotypic and genotypic approaches. Several molecular methods (PCR mapping, restriction assays, Southern blotting, sequencing and sequence analysis, conjugal transfer assays) were used to determine the genetic context of catQ and characterize a genetic element detected in the isolates. Sag236 and Sag403 shared the same ST (ST19), but exhibited a different capsular type (III and V, respectively) and pulsotype. Both harboured the macrolide resistance genes mef(I) and erm(TR) and the tetracycline resistance gene tet(M). Accordingly, they were resistant to chloramphenicol, erythromycin and tetracycline. catQ and mef(I) were associated in an IQ module that was indistinguishable in Sag236 and Sag403. In mating assays, chloramphenicol and erythromycin resistance proved transferable, at low frequency, only from Sag236. Transconjugants carried not only catQ and mef(I), but also erm(TR), suggesting a linkage of the three resistance genes in a mobile element, which, though seemingly non-mobile, was also detected in Sag403. The new element (designated ICESag236, ∼110 kb) results from recombination of two integrative and conjugative elements (ICEs) originally described in different streptococcal species: S. agalactiae ICESagTR7, carrying erm(TR); and Streptococcus pneumoniae ICESpn529IQ, carrying the prototype IQ module. These findings strengthen the notion that widespread streptococcal ICEs may form mosaics that enhance their diversity and spread, broaden their host range and carry new cargo genes. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions

  15. Stem cell collection and gene transfer in Fanconi anemia.

    Science.gov (United States)

    Kelly, Patrick F; Radtke, Susan; von Kalle, Christof; Balcik, Brenden; Bohn, Kimberley; Mueller, Robin; Schuesler, Todd; Haren, Moira; Reeves, Lilith; Cancelas, Jose A; Leemhuis, Thomas; Harris, Richard; Auerbach, Arleen D; Smith, Franklin O; Davies, Stella M; Williams, David A

    2007-01-01

    Fanconi anemia (FA) is a rare genetic syndrome characterized by progressive bone marrow failure (BMF), congenital anomalies, and a predisposition to malignancy. Successful gene transfer into hematopoietic stem cells (HSCs) could reverse BMF in this disease. We developed clinical trials to determine whether a sufficient number of CD34(+) stem cells could be collected for gene modification and to evaluate the safety and efficacy of HSC-corrective gene transfer in FA genotype A (FANCA) patients. Here, we report that FA patients have significant depletion of their BM CD34(+) cell compartment even before severe pancytopenia is present. However, oncoretroviral-mediated ex vivo gene transfer was efficient in clinical scale in FA-A cells, leading to reversal of the cellular phenotype in a significant percentage of CD34(+) cells. Re-infusion of gene-corrected products in two patients was safe and well tolerated and accompanied by transient improvements in hemoglobin and platelet counts. Gene correction was transient, likely owing to the low dose of gene-corrected cells infused. Our early experience shows that stem cell collection is well tolerated in FA patients and suggests that collection be considered as early as possible in patients who are potential candidates for future gene transfer trials.

  16. Horizontal gene transfer and bacterial diversity

    Indian Academy of Sciences (India)

    Unknown

    This review discusses how the recent influx of complete chromosomal sequences of various ... enteric bacteria, a great deal of phenotypic diversity among species is ..... E V 1998 Evidence for massive gene exchange between archaeal and ...

  17. AtMRP1 gene of Arabidopsis encodes a glutathione S-conjugate pump: isolation and functional definition of a plant ATP-binding cassette transporter gene.

    Science.gov (United States)

    Lu, Y P; Li, Z S; Rea, P A

    1997-07-22

    Because plants produce cytotoxic compounds to which they, themselves, are susceptible and are exposed to exogenous toxins (microbial products, allelochemicals, and agrochemicals), cell survival is contingent on mechanisms for detoxifying these agents. One detoxification mechanism is the glutathione S-transferase-catalyzed glutathionation of the toxin, or an activated derivative, and transport of the conjugate out of the cytosol. We show here that a transporter responsible for the removal of glutathione S-conjugates from the cytosol, a specific Mg2+-ATPase, is encoded by the AtMRP1 gene of Arabidopsis thaliana. The sequence of AtMRP1 and the transport capabilities of membranes prepared from yeast cells transformed with plasmid-borne AtMRP1 demonstrate that this gene encodes an ATP-binding cassette transporter competent in the transport of glutathione S-conjugates of xenobiotics and endogenous substances, including herbicides and anthocyanins.

  18. Insights on the Horizontal Gene Transfer of Carbapenemase Determinants in the Opportunistic Pathogen Acinetobacter baumannii

    Science.gov (United States)

    Da Silva, Gabriela Jorge; Domingues, Sara

    2016-01-01

    Horizontal gene transfer (HGT) is a driving force to the evolution of bacteria. The fast emergence of antimicrobial resistance reflects the ability of genetic adaptation of pathogens. Acinetobacter baumannii has emerged in the last few decades as an important opportunistic nosocomial pathogen, in part due to its high capacity of acquiring resistance to diverse antibiotic families, including to the so-called last line drugs such as carbapenems. The rampant selective pressure and genetic exchange of resistance genes hinder the effective treatment of resistant infections. A. baumannii uses all the resistance mechanisms to survive against carbapenems but production of carbapenemases are the major mechanism, which may act in synergy with others. A. baumannii appears to use all the mechanisms of gene dissemination. Beyond conjugation, the mostly reported recent studies point to natural transformation, transduction and outer membrane vesicles-mediated transfer as mechanisms that may play a role in carbapenemase determinants spread. Understanding the genetic mobilization of carbapenemase genes is paramount in preventing their dissemination. Here we review the carbapenemases found in A. baumannii and present an overview of the current knowledge of contributions of the various HGT mechanisms to the molecular epidemiology of carbapenem resistance in this relevant opportunistic pathogen. PMID:27681923

  19. Horizontal gene transfer in an acid mine drainage microbial community.

    Science.gov (United States)

    Guo, Jiangtao; Wang, Qi; Wang, Xiaoqi; Wang, Fumeng; Yao, Jinxian; Zhu, Huaiqiu

    2015-07-04

    Horizontal gene transfer (HGT) has been widely identified in complete prokaryotic genomes. However, the roles of HGT among members of a microbial community and in evolution remain largely unknown. With the emergence of metagenomics, it is nontrivial to investigate such horizontal flow of genetic materials among members in a microbial community from the natural environment. Because of the lack of suitable methods for metagenomics gene transfer detection, microorganisms from a low-complexity community acid mine drainage (AMD) with near-complete genomes were used to detect possible gene transfer events and suggest the biological significance. Using the annotation of coding regions by the current tools, a phylogenetic approach, and an approximately unbiased test, we found that HGTs in AMD organisms are not rare, and we predicted 119 putative transferred genes. Among them, 14 HGT events were determined to be transfer events among the AMD members. Further analysis of the 14 transferred genes revealed that the HGT events affected the functional evolution of archaea or bacteria in AMD, and it probably shaped the community structure, such as the dominance of G-plasma in archaea in AMD through HGT. Our study provides a novel insight into HGT events among microorganisms in natural communities. The interconnectedness between HGT and community evolution is essential to understand microbial community formation and development.

  20. Design of radiopharmaceuticals for monitoring gene transfer therapy

    International Nuclear Information System (INIS)

    Lambrecht, R.M.; Staehler, P.; Kley, J.; Spiegel, M.; Gross, C.; Graepler, F.T.C.; Gregor, M.; Lauer, U.; Oberdorfer, F.

    1998-01-01

    The development of radiopharmaceuticals for monitoring gene transfer therapy with emission tomography is expected to lead to improved management of cancer by the year 2010. There are now only a few examples and approaches to the design of radiopharmaceuticals for gene transfer therapy. This paper introduces a novel concept for the monitoring of gene therapy. We present the optimisation of the labelling of recombinant human β-NGF ligands for in vitro studies prior to using 123 I for SPET and 124 I for PET studies. (author)

  1. Horizontal gene transfer between Wolbachia and the mosquito Aedes aegypti

    Directory of Open Access Journals (Sweden)

    Walker Thomas

    2009-01-01

    Full Text Available Abstract Background The evolutionary importance of horizontal gene transfer (HGT from Wolbachia endosymbiotic bacteria to their eukaryotic hosts is a topic of considerable interest and debate. Recent transfers of genome fragments from Wolbachia into insect chromosomes have been reported, but it has been argued that these fragments may be on an evolutionary trajectory to degradation and loss. Results We have discovered a case of HGT, involving two adjacent genes, between the genomes of Wolbachia and the currently Wolbachia-uninfected mosquito Aedes aegypti, an important human disease vector. The lower level of sequence identity between Wolbachia and insect, the transcription of all the genes involved, and the fact that we have identified homologs of the two genes in another Aedes species (Ae. mascarensis, suggest that these genes are being expressed after an extended evolutionary period since horizontal transfer, and therefore that the transfer has functional significance. The association of these genes with Wolbachia prophage regions also provides a mechanism for the transfer. Conclusion The data support the argument that HGT between Wolbachia endosymbiotic bacteria and their hosts has produced evolutionary innovation.

  2. Identification of horizontally transferred genes in the genus Colletotrichum reveals a steady tempo of bacterial to fungal gene transfer.

    Science.gov (United States)

    Jaramillo, Vinicio D Armijos; Sukno, Serenella A; Thon, Michael R

    2015-01-02

    Horizontal gene transfer (HGT) is the stable transmission of genetic material between organisms by means other than vertical inheritance. HGT has an important role in the evolution of prokaryotes but is relatively rare in eukaryotes. HGT has been shown to contribute to virulence in eukaryotic pathogens. We studied the importance of HGT in plant pathogenic fungi by identifying horizontally transferred genes in the genomes of three members of the genus Colletotrichum. We identified eleven HGT events from bacteria into members of the genus Colletotrichum or their ancestors. The HGT events include genes involved in amino acid, lipid and sugar metabolism as well as lytic enzymes. Additionally, the putative minimal dates of transference were calculated using a time calibrated phylogenetic tree. This analysis reveals a constant flux of genes from bacteria to fungi throughout the evolution of subphylum Pezizomycotina. Genes that are typically transferred by HGT are those that are constantly subject to gene duplication and gene loss. The functions of some of these genes suggest roles in niche adaptation and virulence. We found no evidence of a burst of HGT events coinciding with major geological events. In contrast, HGT appears to be a constant, albeit rare phenomenon in the Pezizomycotina, occurring at a steady rate during their evolution.

  3. SiRNAs conjugated with aromatic compounds induce RISC-mediated antisense strand selection and strong gene-silencing activity

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, Takanori, E-mail: kubo-t@yasuda-u.ac.jp [Faculty of Pharmacy, Yasuda Women' s University, 6-13-1 Yasuhigashi, Asaminami-ku, Hiroshima 731-0153 (Japan); Yanagihara, Kazuyoshi [Faculty of Pharmacy, Yasuda Women' s University, 6-13-1 Yasuhigashi, Asaminami-ku, Hiroshima 731-0153 (Japan); Division of Genetics, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Takei, Yoshifumi [Department of Biochemistry, Nagoya University Graduate School of Medicine, 65 Tsurumi-cho, Showa-ku, Nagoya 466-8550 (Japan); Mihara, Keichiro [Department of Hematology and Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Sato, Yuichiro; Seyama, Toshio [Faculty of Pharmacy, Yasuda Women' s University, 6-13-1 Yasuhigashi, Asaminami-ku, Hiroshima 731-0153 (Japan)

    2012-10-05

    Highlights: Black-Right-Pointing-Pointer SiRNAs conjugated with aromatic compounds (Ar-siRNAs) at 5 Prime -sense strand were synthesized. Black-Right-Pointing-Pointer Ar-siRNAs increased resistance against nuclease degradation. Black-Right-Pointing-Pointer Ar-siRNAs were thermodynamically stable compared with the unmodified siRNA. Black-Right-Pointing-Pointer High levels of cellular uptake and cytoplasmic localization were found. Black-Right-Pointing-Pointer Strong gene-silencing efficacy was exhibited in the Ar-siRNAs. -- Abstract: Short interference RNA (siRNA) is a powerful tool for suppressing gene expression in mammalian cells. In this study, we focused on the development of siRNAs conjugated with aromatic compounds in order to improve the potency of RNAi and thus to overcome several problems with siRNAs, such as cellular delivery and nuclease stability. The siRNAs conjugated with phenyl, hydroxyphenyl, naphthyl, and pyrenyl derivatives showed strong resistance to nuclease degradation, and were thermodynamically stable compared with unmodified siRNA. A high level of membrane permeability in HeLa cells was also observed. Moreover, these siRNAs exhibited enhanced RNAi efficacy, which exceeded that of locked nucleic acid (LNA)-modified siRNAs, against exogenous Renilla luciferase in HeLa cells. In particular, abundant cytoplasmic localization and strong gene-silencing efficacy were found in the siRNAs conjugated with phenyl and hydroxyphenyl derivatives. The novel siRNAs conjugated with aromatic compounds are promising candidates for a new generation of modified siRNAs that can solve many of the problems associated with RNAi technology.

  4. [Gene doping: gene transfer and possible molecular detection].

    Science.gov (United States)

    Argüelles, Carlos Francisco; Hernández-Zamora, Edgar

    2007-01-01

    The use of illegal substances in sports to enhance athletic performance during competition has caused international sports organizations such as the COI and WADA to take anti doping measures. A new doping method know as gene doping is defined as "the non-therapeutic use of genes, genetic elements and/or cells that have the capacity to enhance athletic performance". However, gene doping in sports is not easily identified and can cause serious consequences. Molecular biology techniques are needed in order to distinguish the difference between a "normal" and an "altered" genome. Further, we need to develop new analytic methods and biological molecular techniques in anti-doping laboratories, and design programs that avoid the non therapeutic use of genes.

  5. Shock wave induced sonoporation and gene transfer

    Science.gov (United States)

    Miller, Douglas L.

    2003-10-01

    During shockwave (SW) treatment, cavitation activity can be applied for cell killing. A bonus is that some surviving cells appear to be briefly permeabilized, or sonoporated, allowing them to take up large molecules including DNA. In vitro research has indicated that as the number of SW increased, survival declined exponentially but the number of sonoporated cells increased to better than 50% of survivors for 1000 SW. In vivo tests have demonstrated SW-induced tumor ablation could indeed be accompanied by the transfection of marker plasmids into mouse B16 melanoma tumors in vivo. With intratumor injection of plasmid DNA and air bubbles, significant results were obtained for only 400 SW. In a trial of cancer therapy, the effects of 500 SW combined with interleukin-12 immuno-gene therapy was observed on the progression of two mouse tumors, B16 melanoma and RENCA renal carcinoma. The combination of SW and IL-12 plasmid injection provided a statistically significant inhibition of tumor growth relative to SW alone for both tumor models, demonstrating feasibility for this treatment method. In the future, the development of intravenous gene delivery and improved transfection, together with image-guided ultrasound treatment, should lead to the clinical application of ultrasound enhanced gene therapy. [Work supported by NIH Grant No. EB002782.

  6. Gene transfer strategies for improving radiolabeled peptide imaging and therapy

    International Nuclear Information System (INIS)

    Rogers, B.E.; Buchsbaum, D.J.; Zinn, K.R.

    2000-01-01

    Utilization of molecular biology techniques offers attractive options in nuclear medicine for improving cancer imaging and therapy with radiolabeled peptides. Two of these options include utilization of phage-panning to identify novel tumor specific peptides or single chain antibodies and gene transfer techniques to increase the antibodies and gene transfer techniques to increase the number of antigen/receptor sites expressed on malignant cells. The group has focused on the latter approach for improving radiolabeled peptide imaging and therapy. The most widely used gene transfer vectors in clinical gene therapy trials include retrovirus, cationic lipids and adenovirus. It has been utilized adenovirus vectors for gene transfer because of their ability to accomplish efficient in vivo gene transfer. Adenovirus vectors encoding the genes for a variety of antigens/receptors (carcinoembryonic antigen, gastrin-releasing peptide receptor, somatostatin receptor subtype 2 (SSTr2) have all shown that their expression is increased on cancer cells both in vitro and in vivo following adenovirus infection. Of particular interest has been the adenovirus encoding for SSTr2 (AdCMVSSTr2). Various radioisotopes have been attached to somatostatin analogues for imaging and therapy of SSTr2-positive tumors both clinically and in animal models. The use of these analogues in combination with AdCMVSSTr2 is a promising approach for improving the detection sensitivity and therapeutic efficacy of these radiolabeled peptides against solid tumors. In addition, it has been proposed the use of SSTr2 as a marker for imaging the expression of another cancer therapeutic transgene (e.g. cytosine deaminase, thymidine kinase) encoded within the same vector. This would allow for non-invasive monitoring of gene delivery to tumor sites

  7. Twenty Years of European Union Support to Gene Therapy and Gene Transfer.

    Science.gov (United States)

    Gancberg, David

    2017-11-01

    For 20 years and throughout its research programmes, the European Union has supported the entire innovation chain for gene transfer and gene therapy. The fruits of this investment are ripening as gene therapy products are reaching the European market and as clinical trials are demonstrating the safety of this approach to treat previously untreatable diseases.

  8. DNA-mediated gene transfer into ataxia-telangiectasia cells

    International Nuclear Information System (INIS)

    Crescenzi, M.; Pulciani, S.; Carbonari, M.; Tedesco, L.; Russo, G.; Gaetano, C.; Fiorilli, M.

    1986-01-01

    The complete description of the genetic lesion(s) underlying the AT mutation might, therefore, highlight not only a DNA-repair pathwa, but also an important aspect of the physiology of lymphocytes. DNA-mediated gene transfer into eukaryotic cells has proved a powerful tool for the molecular cloning of certain mammalian genes. The possibility to clone a given gene using this technology depends, basically, on the availability of a selectable marker associated with the expression of the transfected gene in the recipient cell. Recently, a human DNA repair gene has been cloned in CHO mutant cells by taking advantage of the increased resistance to ultraviolet radiation of the transformants. As a preliminary step toward the molecular cloning of the AT gene(s), the authors have attempted to confer radioresistance to AT cells by transfection with normal human DNA

  9. Occurrence and Distribution of Antibiotic-resistant Bacteria and Transfer of Resistance Genes in Lake Taihu

    Science.gov (United States)

    Yin, Qian; Yue, Dongmei; Peng, Yuke; Liu, Ying; Xiao, Lin

    2013-01-01

    The overuse of antibiotics has accelerated antibiotic resistance in the natural environment, especially fresh water, generating a potential risk for public health around the world. In this study, antibiotic resistance in Lake Taihu was investigated and this was the first thorough data obtained through culture-dependent methods. High percentages of resistance to streptomycin and ampicillin among bacterial isolates were detected, followed by tetracycline and chloramphenicol. Especially high levels of ampicillin resistance in the western and northern regions were illustrated. Bacterial identification of the isolates selected for further study indicated the prevalence of some opportunistic pathogens and 62.0% of the 78 isolates exhibited multiple antibiotic resistance. The presence of ESBLs genes was in the following sequence: blaTEM > blaSHV > blaCTMX and 38.5% of the isolates had a class I integrase gene. Of all tested strains, 80.8% were able to transfer antibiotic resistance through conjugation. We also concluded that some new families of human-associated ESBLs and AmpC genes can be found in natural environmental isolates. The prevalence of antibiotic resistance and the dissemination of transferable antibiotic resistance in bacterial isolates (especially in opportunistic pathogens) was alarming and clearly indicated the urgency of realizing the health risks of antibiotic resistance to human and animal populations who are dependent on Lake Taihu for water consumption. PMID:24240317

  10. Numerical analysis of the transient conjugated heat transfer in a circular duct with a power-law fluid

    Energy Technology Data Exchange (ETDEWEB)

    Luna, N. [Secretaria de Energia, Direccion de Operacion Petrolera, Mexico DF (Mexico); Mendez, F. [UNAM, Facultad de Ingenieria, Mexico DF (Mexico); Bautista, O. [ITESM, Division de Ingenieria y Arquitectura, Mexico DF (Mexico)

    2005-05-01

    We treat numerically in this paper, the transient analysis of a conjugated heat transfer process in the thermal entrance region of a circular tube with a fully developed laminar power-law fluid flow. We apply the quasi-steady approximation for the power-law fluid, identifying the suitable time scales of the process. Thus, the energy equation in the fluids is solved analytically using the well-known integral boundary layer technique. This solution is coupled to the transient energy equation for the solid where the transverse and longitudinal heat conduction effects are taken into account. The numerical results for the temporal evolution of the average temperature of the tube wall, {theta}{sub av,} is plotted for different nondimensional parameters such as conduction parameter, {alpha}, the aspect ratios of the tube, {epsilon} and {epsilon}{sub 0} and the index of power-law fluid, n. (orig.)

  11. NUMERICAL MODELING OF CONJUGATE HEAT TRANSFER IN AN INSULATED GLASS UNIT (IGU WITH ACCOUNT FOR ITS DEFORMATION

    Directory of Open Access Journals (Sweden)

    Golubev Stanislav Sergeevich

    2012-12-01

    The effects of different climatic impacts lead to the deformation of glasses within an IGU (and its vertical cavity, respectively. Deformation of glasses and vertical cavities reduces the thermal resistance of an IGU. A numerical simulation of conjugate heat transfer within an IGU was implemented as part of the research into this phenomenon. Calculations were performed in ANSYS FLUENT CFD package. Basic equations describing the conservation of mass, conservation of momentum (in the Boussinesq approximation, conservation of energy were solved. Also, the radiation of the cavity wall was taken into account. Vertical walls were considered as non-isothermal, while horizontal walls were adiabatic. Calculations were made for several patterns of glass deformations. Calculation results demonstrate that the heat flow over vertical walls intensifies as the distance between centres of IGU glasses is reduced. The temperature in the central area of the hot glass drops.

  12. Excitation energy transfer in ruthenium (II)-porphyrin conjugates led to enhanced emission quantum yield and 1O2 generation

    International Nuclear Information System (INIS)

    Pan, Jie; Jiang, Lijun; Chan, Chi-Fai; Tsoi, Tik-Hung; Shiu, Kwok-Keung; Kwong, Daniel W.J.; Wong, Wing-Tak; Wong, Wai-Kwok; Wong, Ka-Leung

    2017-01-01

    Porphyrins are good photodynamic therapy (PDT) agents due to its flexibility for modifications to achieve tumor localization and photo-cytotoxicity against cancer. Yet they are not perfect. In a Ru(polypyridyl)-porphyrin system, the Ru(polypyridyl) moiety improves the water solubility and cell permeability. Consider the similar excited state energies between Ru(polypyridyl) and porphyrin moieties; a small perturbation (e.g. Zn(II) metalation) would lead to a marked change in the energy migration process. In this work, we have synthesized a series of porphyrins conjugated with Ru(polypyridyl) complexes using different linkers and investigated their photophysical properties, which included singlet oxygen quantum yield and their in vitro biological properties, resulting from linker variation and porphyrin modification by Zn(II) metalation. - Graphical abstract: Four amphiphilic ruthenium(II)-porphyrin complexes were prepared that display energy transfer conversion with zinc coordination, lysosome specific target, low dark toxicity and efficient photodynamic therapy.

  13. Tetrapeptide-coumarin conjugate 3D networks based on hydrogen-bonded charge transfer complexes: gel formation and dye release.

    Science.gov (United States)

    Guo, Zongxia; Gong, Ruiying; Jiang, Yi; Wan, Xiaobo

    2015-08-14

    Oligopeptide-based derivatives are important synthons for bio-based functional materials. In this article, a Gly-(L-Val)-Gly-(L-Val)-coumarin (GVGV-Cou) conjugate was synthesized, which forms 3D networks in ethanol. The gel nanostructures were characterized by UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD), SEM and TEM. It is suggested that the formation of charge transfer (CT) complexes between the coumarin moieties is the main driving force for the gel formation. The capability of the gel to encapsulate and release dyes was explored. Both Congo Red (CR) and Methylene Blue (MB) can be trapped in the CT gel matrix and released over time. The present gel might be used as a functional soft material for guest encapsulation and release.

  14. Solution to Two-Dimensional Steady Inverse Heat Transfer Problems with Interior Heat Source Based on the Conjugate Gradient Method

    Directory of Open Access Journals (Sweden)

    Shoubin Wang

    2017-01-01

    Full Text Available The compound variable inverse problem which comprises boundary temperature distribution and surface convective heat conduction coefficient of two-dimensional steady heat transfer system with inner heat source is studied in this paper applying the conjugate gradient method. The introduction of complex variable to solve the gradient matrix of the objective function obtains more precise inversion results. This paper applies boundary element method to solve the temperature calculation of discrete points in forward problems. The factors of measuring error and the number of measuring points zero error which impact the measurement result are discussed and compared with L-MM method in inverse problems. Instance calculation and analysis prove that the method applied in this paper still has good effectiveness and accuracy even if measurement error exists and the boundary measurement points’ number is reduced. The comparison indicates that the influence of error on the inversion solution can be minimized effectively using this method.

  15. Expression of a transferred nuclear gene in a mitochondrial genome

    Directory of Open Access Journals (Sweden)

    Yichun Qiu

    2014-08-01

    Full Text Available Transfer of mitochondrial genes to the nucleus, and subsequent gain of regulatory elements for expression, is an ongoing evolutionary process in plants. Many examples have been characterized, which in some cases have revealed sources of mitochondrial targeting sequences and cis-regulatory elements. In contrast, there have been no reports of a nuclear gene that has undergone intracellular transfer to the mitochondrial genome and become expressed. Here we show that the orf164 gene in the mitochondrial genome of several Brassicaceae species, including Arabidopsis, is derived from the nuclear ARF17 gene that codes for an auxin responsive protein and is present across flowering plants. Orf164 corresponds to a portion of ARF17, and the nucleotide and amino acid sequences are 79% and 81% identical, respectively. Orf164 is transcribed in several organ types of Arabidopsis thaliana, as detected by RT-PCR. In addition, orf164 is transcribed in five other Brassicaceae within the tribes Camelineae, Erysimeae and Cardamineae, but the gene is not present in Brassica or Raphanus. This study shows that nuclear genes can be transferred to the mitochondrial genome and become expressed, providing a new perspective on the movement of genes between the genomes of subcellular compartments.

  16. Ultrafast Photoinduced Electron Transfer in a π-Conjugated Oligomer/Porphyrin Complex

    KAUST Repository

    Aly, Shawkat Mohammede; Goswami, Subhadip; Alsulami, Qana; Schanze, Kirk S.; Mohammed, Omar F.

    2014-01-01

    Controlling charge transfer (CT), charge separation (CS), and charge recombination (CR) at the donor-acceptor interface is extremely important to optimize the conversion efficiency in solar cell devices. In general, ultrafast CT and slow CR

  17. Coupled sensitizer-catalyst dyads: electron-transfer reactions in a perylene-polyoxometalate conjugate.

    Science.gov (United States)

    Odobel, Fabrice; Séverac, Marjorie; Pellegrin, Yann; Blart, Errol; Fosse, Céline; Cannizzo, Caroline; Mayer, Cédric R; Elliott, Kristopher J; Harriman, Anthony

    2009-01-01

    Ultrafast discharge of a single-electron capacitor: A variety of intramolecular electron-transfer reactions are apparent for polyoxometalates functionalized with covalently attached perylene monoimide chromophores, but these are restricted to single-electron events. (et=electron transfer, cr=charge recombination, csr=charge-shift reaction, PER=perylene, POM=polyoxometalate).A new strategy is introduced that permits covalent attachment of an organic chromophore to a polyoxometalate (POM) cluster. Two examples are reported that differ according to the nature of the anchoring group and the flexibility of the linker. Both POMs are functionalized with perylene monoimide units, which function as photon collectors and form a relatively long-lived charge-transfer state under illumination. They are reduced to a stable pi-radical anion by electrolysis or to a protonated dianion under photolysis in the presence of aqueous triethanolamine. The presence of the POM opens up an intramolecular electron-transfer route by which the charge-transfer state reduces the POM. The rate of this process depends on the molecular conformation and appears to involve through-space interactions. Prior reduction of the POM leads to efficient fluorescence quenching, again due to intramolecular electron transfer. In most cases, it is difficult to resolve the electron-transfer products because of relatively fast reverse charge shift that occurs within a closed conformer. Although the POM can store multiple electrons, it has not proved possible to use these systems as molecular-scale capacitors because of efficient electron transfer from the one-electron-reduced POM to the excited singlet state of the perylene monoimide.

  18. Trans-kingdom horizontal DNA transfer from bacteria to yeast is highly plastic due to natural polymorphisms in auxiliary nonessential recipient genes.

    Directory of Open Access Journals (Sweden)

    Kazuki Moriguchi

    Full Text Available With the rapid accumulation of genomic information from various eukaryotes in the last decade, genes proposed to have been derived from recent horizontal gene transfer (HGT events have been reported even in non-phagotrophic unicellular and multicellular organisms, but the molecular pathways underlying HGT remain to be explained. The development of in vitro HGT detection systems, which permit the molecular and genetic analyses of donor and recipient organisms and quantify HGT, are helpful in order to gain insight into mechanisms that may contribute to contemporary HGT events or may have contributed to past HGT events. We applied a horizontal DNA transfer system model based on conjugal gene transfer called trans-kingdom conjugation (TKC from the prokaryote Escherichia coli to the eukaryote Saccharomyces cerevisiae, and assessed whether and to what extent genetic variations in the eukaryotic recipient affect its receptivity to TKC. Strains from a collection of 4,823 knock-out mutants of S. cerevisiae MAT-α haploids were tested for their individual TKC receptivity. Two types of mutants, an ssd1 mutant and respiratory mutants, which are also found in experimental strains and in nature widely, were identified as highly receptive mutants. The TKC efficiency for spontaneously accrued petite (rho (-/0 mutants of the functional allele (SSD1-V strain showed increased receptivity. The TKC efficiency of the ssd1Δ mutant was 36% for bacterial conjugation, while that of the petite/ssd1Δ double mutants was even higher (220% in average compared to bacterial conjugation. This increased TKC receptivity was also observed when other conjugal transfer systems were applied and the donor bacterium was changed to Agrobacterium tumefaciens. These results support the idea that the genomes of certain eukaryotes have been exposed to exogenous DNA more frequently and continuously than previously thought.

  19. Conjugate heat transfer in a porous cavity filled with nano-fluids and heated by a triangular thick wall

    International Nuclear Information System (INIS)

    Chamkha, Ali J.; Ismael, Muneer A.

    2013-01-01

    The conjugate natural convection-conduction heat transfer in a square domain composed of nano-fluids filled porous cavity heated by a triangular solid wall is studied under steady-state conditions. The vertical and horizontal walls of the triangular solid wall are kept isothermal and at the same hot temperature Th. The other boundaries surrounding the porous cavity are kept adiabatic except the right vertical wall where it is kept isothermally at the lower temperature T c . Equations governing the heat transfer in the triangular wall and heat and nano-fluid flow, based on the Darcy model, in the nano-fluid-saturated porous medium together with the derived relation of the interface temperature are solved numerically using the over-successive relaxation finite-difference method. A temperature independent nano-fluids properties model is adopted. Three nano-particle types dispersed in one base fluid (water) are investigated. The investigated parameters are the nano-particles volume fraction φ (0-0.2), Rayleigh number Ra (10-1000), solid wall to base-fluid saturated porous medium thermal conductivity ratio K ro (0.44, 1, 23.8), and the triangular wall thickness D (0.1-1). The results are presented in the conventional form; contours of streamlines and isotherms and the local and average Nusselt numbers. At a very low Rayleigh number Ra = 10, a significant enhancement in heat transfer within the porous cavity with φ is observed. Otherwise, the heat transfer may be enhanced or deteriorated with φ depending on the wall thickness D and the Rayleigh number Ra. At high Rayleigh numbers and low conductivity ratios, critical values of D, regardless of 4, are observed and accounted. (authors)

  20. Detecting Horizontal Gene Transfer between Closely Related Taxa.

    Directory of Open Access Journals (Sweden)

    Orit Adato

    2015-10-01

    Full Text Available Horizontal gene transfer (HGT, the transfer of genetic material between organisms, is crucial for genetic innovation and the evolution of genome architecture. Existing HGT detection algorithms rely on a strong phylogenetic signal distinguishing the transferred sequence from ancestral (vertically derived genes in its recipient genome. Detecting HGT between closely related species or strains is challenging, as the phylogenetic signal is usually weak and the nucleotide composition is normally nearly identical. Nevertheless, there is a great importance in detecting HGT between congeneric species or strains, especially in clinical microbiology, where understanding the emergence of new virulent and drug-resistant strains is crucial, and often time-sensitive. We developed a novel, self-contained technique named Near HGT, based on the synteny index, to measure the divergence of a gene from its native genomic environment and used it to identify candidate HGT events between closely related strains. The method confirms candidate transferred genes based on the constant relative mutability (CRM. Using CRM, the algorithm assigns a confidence score based on "unusual" sequence divergence. A gene exhibiting exceptional deviations according to both synteny and mutability criteria, is considered a validated HGT product. We first employed the technique to a set of three E. coli strains and detected several highly probable horizontally acquired genes. We then compared the method to existing HGT detection tools using a larger strain data set. When combined with additional approaches our new algorithm provides richer picture and brings us closer to the goal of detecting all newly acquired genes in a particular strain.

  1. UCP2 muscle gene transfer modifies mitochondrial membrane potential.

    Science.gov (United States)

    Marti, A; Larrarte, E; Novo, F J; Garcia, M; Martinez, J A

    2001-01-01

    The aim of this work was to evaluate the effect of uncoupling protein 2 (UCP2) muscle gene transfer on mitochondrial activity. Five week-old male Wistar rats received an intramuscular injection of plasmid pXU1 containing UCP2 cDNA in the right tibialis anterior muscles. Left tibialis anterior muscles were injected with vehicle as control. Ten days after DNA injection, tibialis anterior muscles were dissected and muscle mitochondria isolated and analyzed. There were two mitochondrial populations in the muscle after UCP2 gene transfer, one of low fluorescence and complexity and the other, showing high fluorescence and complexity. UCP2 gene transfer resulted in a 3.6 fold increase in muscle UCP2 protein levels compared to control muscles assessed by Western blotting. Furthermore, a significant reduction in mitochondria membrane potential assessed by spectrofluorometry and flow cytometry was observed. The mitochondria membrane potential reduction might account for a decrease in fluorescence of the low fluorescence mitochondrial subpopulation. It has been demonstrated that UCP2 muscle gene transfer in vivo is associated with a lower mitochondria membrane potential. Our results suggest the potential involvement of UCP2 in uncoupling respiration. International Journal of Obesity (2001) 25, 68-74

  2. Enterococcus faecalis Sex Pheromone cCF10 Enhances Conjugative Plasmid Transfer In Vivo

    Directory of Open Access Journals (Sweden)

    Helmut Hirt

    2018-02-01

    Full Text Available Cell-cell communication mediated by peptide pheromones (cCF10 [CF] is essential for high-frequency plasmid transfer in vitro in Enterococcus faecalis. To examine the role of pheromone signaling in vivo, we established either a CF-producing (CF+ recipient or a recipient producing a biologically inactive variant of CF (CF− recipient in a germfree mouse model 3 days before donor inoculation and determined transfer frequencies of the pheromone-inducible plasmid pCF10. Plasmid transfer was detected in the upper and middle sections of the intestinal tract 5 h after donor inoculation and was highly efficient in the absence of antibiotic selection. The transconjugant/donor ratio reached a maximum level approaching 1 on day 4 in the upper intestinal tract. Plasmid transfer was significantly lower with the CF− recipient. While rescue of the CF− mating defect by coculture with CF+ recipients is easily accomplished in vitro, no extracellular complementation occurred in vivo. This suggests that most pheromone signaling in the gut occurs between recipient and donor cells in very close proximity. Plasmid-bearing cells (donors plus transconjugants steadily increased in the population from 0.1% after donor inoculation to about 10% at the conclusion of the experiments. This suggests a selective advantage of pCF10 carriage distinct from antibiotic resistance or bacteriocin production. Our results demonstrate that pheromone signaling is required for efficient pCF10 transfer in vivo. In the absence of CF+ recipients, a low level of transfer to CF− recipients occurred in the gut. This may result from low-level host-mediated induction of the donors in the gastrointestinal (GI tract, similar to that previously observed in serum.

  3. Effective in vitro gene delivery to murine cancerous brain cells using carbon nanotube-polyethylenimine conjugates

    Directory of Open Access Journals (Sweden)

    Azadeh Hashem Nia

    2015-04-01

    Conclusion: Conjugation of PEI with carbon nanotube les to new vectors with lowered cytotoxicity and higher transfection efficiency. The highest transfection efficiency was obtained with the lowest molecular weight PEI.

  4. An approximate block Newton method for coupled iterations of nonlinear solvers: Theory and conjugate heat transfer applications

    Science.gov (United States)

    Yeckel, Andrew; Lun, Lisa; Derby, Jeffrey J.

    2009-12-01

    A new, approximate block Newton (ABN) method is derived and tested for the coupled solution of nonlinear models, each of which is treated as a modular, black box. Such an approach is motivated by a desire to maintain software flexibility without sacrificing solution efficiency or robustness. Though block Newton methods of similar type have been proposed and studied, we present a unique derivation and use it to sort out some of the more confusing points in the literature. In particular, we show that our ABN method behaves like a Newton iteration preconditioned by an inexact Newton solver derived from subproblem Jacobians. The method is demonstrated on several conjugate heat transfer problems modeled after melt crystal growth processes. These problems are represented by partitioned spatial regions, each modeled by independent heat transfer codes and linked by temperature and flux matching conditions at the boundaries common to the partitions. Whereas a typical block Gauss-Seidel iteration fails about half the time for the model problem, quadratic convergence is achieved by the ABN method under all conditions studied here. Additional performance advantages over existing methods are demonstrated and discussed.

  5. Color optimization of conjugated-polymer/InGaN hybrid white light emitting diodes by incomplete energy transfer

    International Nuclear Information System (INIS)

    Chang, Chi-Jung; Lai, Chun-Feng; Madhusudhana Reddy, P.; Chen, Yung-Lin; Chiou, Wei-Yung; Chang, Shinn-Jen

    2015-01-01

    By using the wavelength conversion method, white light emitting diodes (WLEDs) were produced by applying mixtures of polysiloxane and fluorescent polymers on InGaN based light emitting diodes. UV curable organic–inorganic hybrid materials with high refractive index (1.561), compromised optical, thermal and mechanical properties was used as encapsulants. Red light emitting fluorescent FABD polymer (with 9,9-dioctylfluorene (F), anthracene (A) and 2,1,3-benzothiadiazole (B), and 4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (D) repeating units) and green light emitting fluorescent FAB polymer were used as wavelength converters. The encapsulant/fluorescent polymer mixture and InGaN produce the white light by incomplete energy transfer mechanism. WLEDs with high color rendering index (CRI, about 93), and tunable correlated color temperature (CCT) properties can be produced by controlling the composition and chemical structures of encapsulating polymer and fluorescent polymer in hybrid materials, offering cool-white and neutral-white LEDs. - Highlights: • Highly efficient white light-emitting diodes (WLEDs) were produced. • Conjugated-polymer/InGaN hybrid WLEDs by incomplete energy transfer mechanism. • WLEDs with high color-rendering index and tunable correlated color temperature. • Polysiloxane encapsulant with superior optical, mechanical and thermal properties

  6. Frequent conjugative transfer accelerates adaptation of a broad-host-range plasmid to an unfavorable Pseudomonas putida host.

    Science.gov (United States)

    Heuer, Holger; Fox, Randal E; Top, Eva M

    2007-03-01

    IncP-1 plasmids are known to be promiscuous, but it is not understood if they are equally well adapted to various species within their host range. Moreover, little is known about their fate in bacterial communities. We determined if the IncP-1beta plasmid pB10 was unstable in some Proteobacteria, and whether plasmid stability was enhanced after long-term carriage in a single host and when regularly switched between isogenic hosts. Plasmid pB10 was found to be very unstable in Pseudomonas putida H2, and conferred a high cost (c. 20% decrease in fitness relative to the plasmid-free host). H2(pB10) was then evolved under conditions that selected for plasmid maintenance, with or without regular plasmid transfer (host-switching). When tested in the ancestral host, the evolved plasmids were more stable and their cost was significantly reduced (9% and 16% for plasmids from host-switched and nonswitched lineages, respectively). Our findings suggest that IncP-1 plasmids can rapidly adapt to an unfavorable host by improving their overall stability, and that regular conjugative transfer accelerates this process.

  7. Detection of Horizontal Gene Transfers from Phylogenetic Comparisons

    Science.gov (United States)

    Pylro, Victor Satler; Vespoli, Luciano de Souza; Duarte, Gabriela Frois; Yotoko, Karla Suemy Clemente

    2012-01-01

    Bacterial phylogenies have become one of the most important challenges for microbial ecology. This field started in the mid-1970s with the aim of using the sequence of the small subunit ribosomal RNA (16S) tool to infer bacterial phylogenies. Phylogenetic hypotheses based on other sequences usually give conflicting topologies that reveal different evolutionary histories, which in some cases may be the result of horizontal gene transfer events. Currently, one of the major goals of molecular biology is to understand the role that horizontal gene transfer plays in species adaptation and evolution. In this work, we compared the phylogenetic tree based on 16S with the tree based on dszC, a gene involved in the cleavage of carbon-sulfur bonds. Bacteria of several genera perform this survival task when living in environments lacking free mineral sulfur. The biochemical pathway of the desulphurization process was extensively studied due to its economic importance, since this step is expensive and indispensable in fuel production. Our results clearly show that horizontal gene transfer events could be detected using common phylogenetic methods with gene sequences obtained from public sequence databases. PMID:22675653

  8. Myeloprotection by Cytidine Deaminase Gene Transfer in Antileukemic Therapy

    Directory of Open Access Journals (Sweden)

    Nico Lachmann

    2013-03-01

    Full Text Available Gene transfer of drug resistance (CTX-R genes can be used to protect the hematopoietic system from the toxicity of anticancer chemotherapy and this concept recently has been proven by overexpression of a mutant O6-methylguaninemethyltransferase in the hematopoietic system of glioblastoma patients treated with temozolomide. Given its protection capacity against such relevant drugs as cytosine arabinoside (ara-C, gemcitabine, decitabine, or azacytidine and the highly hematopoiesis-specific toxicity profile of several of these agents, cytidine deaminase (CDD represents another interesting candidate CTX-R gene and our group recently has established the myeloprotective capacity of CDD gene transfer in a number of murine transplant studies. Clinically, CDD overexpression appears particularly suited to optimize treatment strategies for acute leukemias and myelodysplasias given the efficacy of ara-C (and to a lesser degree decitabine and azacytidine in these disease entities. This article will review the current state of the art with regard to CDD gene transfer and point out potential scenarios for a clinical application of this strategy. In addition, risks and potential side effects associated with this approach as well as strategies to overcome these problems will be highlighted.

  9. Photoinduced electron-transfer from pi-conjugated polymers onto buckminsterfullerene, fulleroids, and methanofullerenes

    NARCIS (Netherlands)

    Janssen, R. A. J.; Hummelen, J. C.; Lee, Kwanghee; Pakbaz, K.; Sariciftci, N. S.; Heeger, A. J.; Wudl, F

    1995-01-01

    We present near-steady-state photoinduced absorption (PIA), photoluminescence, and light-induced electron spin resonance (LESR) studies on photoinduced electron transfer reactions from poly(bis-2,5-epi-cholestanoxy-1,4-phenylene vinylene) (BeCHA-PPV) as a donor to Buckminsterfullerene (C60) and a

  10. Fully-developed conjugate heat transfer in porous media with uniform heating

    NARCIS (Netherlands)

    Lopez Penha, D.J.; Stolz, S.; Kuerten, Johannes G.M.; Nordlund, M.; Kuczaj, Arkadiusz K.; Geurts, Bernardus J.

    2012-01-01

    We propose a computational method for approximating the heat transfer coefficient of fully-developed flow in porous media. For a representative elementary volume of the porous medium we develop a transport model subject to periodic boundary conditions that describes incompressible fluid flow through

  11. Charge-transfer mobility and electrical conductivity of PANI as conjugated organic semiconductors.

    Science.gov (United States)

    Zhang, Yahong; Duan, Yuping; Song, Lulu; Zheng, Daoyuan; Zhang, Mingxing; Zhao, Guangjiu

    2017-09-21

    The intramolecular charge transfer properties of a phenyl-end-capped aniline tetramer (ANIH) and a chloro-substituted derivative (ANICl) as organic semiconductors were theoretically studied through the first-principles calculation based on the Marcus-Hush theory. The reorganization energies, intermolecular electronic couplings, angular resolution anisotropic mobilities, and density of states of the two crystals were evaluated. The calculated results demonstrate that both ANIH and ANICl crystals show the higher electron transfer mobilities than the hole-transfer mobilities, which means that the two crystals should prefer to function as n-type organic semiconductors. Furthermore, the angle dependence mobilities of the two crystals show remarkable anisotropic character. The maximum mobility μ max of ANIH and ANICl crystals is 1.3893 and 0.0272 cm 2 V -1 s -1 , which appear at the orientation angles near 176°/356° and 119°/299° of a conducting channel on the a-b reference plane. It is synthetically evaluated that the ANIH crystal possesses relatively lower reorganization energy, higher electronic coupling, and electron transfer mobility, which means that the ANIH crystal may be the more ideal candidate as a high performance n-type organic semiconductor material. The systematic theoretical studies on organic crystals should be conducive to evaluating the charge-transport properties and designing higher performance organic semiconductor materials.

  12. Evaluation of conjugate, radial heat transfer in an internally insulated composite pipe

    NARCIS (Netherlands)

    Reurings, C.; Koussios, S.; Bergsma, O.K.; Vergote, K.

    2015-01-01

    In order to compete with steel, a fibre-reinforced composite exhaust wall with a general-purpose resin system requires an effective but lightweight insulation layer. However a lack of experimental methods for heat transfer from turbulent gas flow to pipe walls lined with a porous insulation layer

  13. Gene cloning and overexpression of two conjugated polyketone reductases, novel aldo-keto reductase family enzymes, of Candida parapsilosis.

    Science.gov (United States)

    Kataoka, M; Delacruz-Hidalgo, A-R G; Akond, M A; Sakuradani, E; Kita, K; Shimizu, S

    2004-04-01

    The genes encoding two conjugated polyketone reductases (CPR-C1, CPR-C2) of Candida parapsilosis IFO 0708 were cloned and sequenced. The genes encoded a total of 304 and 307 amino acid residues for CPR-C1 and CPR-C2, respectively. The deduced amino acid sequences of the two enzymes showed high similarity to each other and to several proteins of the aldo-keto reductase (AKR) superfamily. However, several amino acid residues in putative active sites of AKRs were not conserved in CPR-C1 and CPR-C2. The two CPR genes were overexpressed in Escherichia coli. The E. coli transformant bearing the CPR-C2 gene almost stoichiometrically reduced 30 mg ketopantoyl lactone/ml to D-pantoyl lactone.

  14. On the application of Chimera/unstructured hybrid grids for conjugate heat transfer

    Science.gov (United States)

    Kao, Kai-Hsiung; Liou, Meng-Sing

    1995-01-01

    A hybrid grid system that combines the Chimera overset grid scheme and an unstructured grid method is developed to study fluid flow and heat transfer problems. With the proposed method, the solid structural region, in which only the heat conduction is considered, can be easily represented using an unstructured grid method. As for the fluid flow region external to the solid material, the Chimera overset grid scheme has been shown to be very flexible and efficient in resolving complex configurations. The numerical analyses require the flow field solution and material thermal response to be obtained simultaneously. A continuous transfer of temperature and heat flux is specified at the interface, which connects the solid structure and the fluid flow as an integral system. Numerical results are compared with analytical and experimental data for a flat plate and a C3X cooled turbine cascade. A simplified drum-disk system is also simulated to show the effectiveness of this hybrid grid system.

  15. Two-Dimensional Variable Property Conjugate Heat Transfer Simulation of Nanofluids in Microchannels

    International Nuclear Information System (INIS)

    Ramiar, A.; Ranjbar, A.A.

    2013-01-01

    Laminar two-dimensional forced convective heat transfer of CuO-water and Al 2 O 3 -water nanofluids in a horizontal microchannel has been studied numerically, considering axial conduction effects in both solid and liquid regions and variable thermal conductivity and dynamic viscosity. The results show that using nanoparticles with higher thermal conductivities will intensify enhancement of heat transfer characteristics and slightly increases shear stress on the wall. The obtained results show more steep changes in Nusselt number for lower diameters and also higher values of Nusselt number by decreasing the diameter of nanoparticles. Also, by utilizing conduction number as the criterion, it was concluded from the results that adding nanoparticles will intensify the axial conduction effect in the geometry considered.

  16. Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

    Directory of Open Access Journals (Sweden)

    Jiří Kulhánek

    2012-01-01

    Full Text Available Research activities in the field of imidazole-derived push–pull systems featuring intramolecular charge transfer (ICT are reviewed. Design, synthetic pathways, linear and nonlinear optical properties, electrochemistry, structure–property relationships, and the prospective application of such D-π-A organic materials are described. This review focuses on Y-shaped imidazoles, bi- and diimidazoles, benzimidazoles, bis(benzimidazoles, imidazole-4,5-dicarbonitriles, and imidazole-derived chromophores chemically bound to a polymer chain.

  17. Conjugate heat transfer analysis of an energy conversion device with an updated numerical model obtained through inverse identification

    International Nuclear Information System (INIS)

    Hey, Jonathan; Malloy, Adam C.; Martinez-Botas, Ricardo; Lamperth, Michael

    2015-01-01

    Highlights: • Conjugate heat transfer analysis of an electric machine. • Inverse identification method for estimating the model parameters. • Experimentally determined thermal properties and electromagnetic losses. • Coupling of inverse identification method with a numerical model. • Improved modeling accuracy through introduction of interface material. - Abstract: Energy conversion devices undergo thermal loading during their operation as a result of inefficiencies in the energy conversion process. This will eventually lead to degradation and possible failure of the device if the heat generated is not properly managed. The ability to accurately predict the thermal behavior of such a device during the initial developmental stage is an important requirement. However, accurate predictions of critical temperature is challenging due to the variation of heat transfer parameters from one device to another. The ability to determine the model parameters is key to accurately representing the heat transfer in such a device. This paper presents the use of an inverse identification technique to estimate the model parameters of an energy conversion device designed for vehicular applications. To simulate the imperfect contact and the presence of insulating materials in the permanent magnet electric machine, thin material are introduced at the component interface of the numerical model. The proposed inverse identification method is used to estimate the equivalent thermal conductance of the thin material. In addition, the electromagnetic losses generated in the permanent magnet is also derived indirectly from the temperature measurement using the same method. With the thermal properties and input parameters of the numerical model obtained from the inverse identification method, the critical temperature of the device can be predicted more accurately. The deviation between the maximum measured and predicted winding temperature is less than 2.4%

  18. Experimental study of conjugate heat transfer from liquid metal layer cooled by overlying freon

    International Nuclear Information System (INIS)

    Cho, J.S.; Suh, K.Y.; Chung, C.H.; Park, R.J.; Kim, S.B.

    2001-01-01

    Steady-state and transient experiments were performed for the heat transfer from the liquid metal pool with overlying Freon (R113) coolant in the process of boiling. The simulant molten pool material is tin (Sn) with the melting temperature of 232 Celsius degrees. The metal pool is heated from the bottom surface and the coolant is injected onto the molten metal pool. Tests were conducted under the condition of the bottom surface heating in the test section and the forced convection of the R113 coolant being injected onto the molten metal pool. The bottom heating condition was varied from 8 kW to 14 kW. The temperature distributions of the metal layer and coolant were obtained in the steady-state experiment. The boiling mechanism of the R113 coolant was changed from the nucleate boiling to film boiling in the transient experiment. The critical heat flux (CHF) phenomenon was observed during the transition from the nucleate boiling to the film boiling. Also, the Nusselt (Nu) number and the Rayleigh (Ra) number in the molten metal pool region were obtained as functions of time. Analysis was done for the relationship between the heat flux and the temperature difference between the metal layer surface and the boiling coolant. In this experiment, the heat transfer is achieved with accompanying solidification in the molten metal pool by the boiling R113 coolant there above. The present test results of the natural convection heat transfer on the molten metal pool are higher than those of the liquid metal natural convection heat transfer without coolant boiling. It can be interpreted that the heat transfer rate is enhanced by the overlying boiling coolant having the high heat removal rate. Analysis of the relationship between the heat flux and the difference between the metal layer surface temperature and the coolant bulk boiling temperature revealed that the CHF occurs when the temperature difference reaches a neighborhood of 50 Celsius degrees. Also, if the temperature

  19. Development of a reduction-sensitive diselenide-conjugated oligoethylenimine nanoparticulate system as a gene carrier

    Directory of Open Access Journals (Sweden)

    Cheng G

    2012-07-01

    Full Text Available Gang Cheng,1,2 Yiyan He,1 Li Xie,1 Yu Nie,1 Bin He,1 Zhirong Zhang,2 Zhongwei Gu11National Engineering Research Center for Biomaterials, 2Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, People's Republic of ChinaBackground: The reduction-sensitive cationic polymer is a promising nonviral carrier for gene delivery. Until now, disulfide bonds have been the only golden standard for its design. The aim of this research was to develop a novel reduction-responsive cationic polymer as a gene carrier.Methods: Polycationic carriers were synthesized by addition of branched oligoethylenimine 800 Da (OEI800 via an active ester containing diselenide bonds. Disulfide bonds cross-linked with OEI800-SSx and monoselenide bonds linked with OEI800-Sex were synthesized and compared. Their molecular weights and degradation properties were determined using gel permeation chromatography. Changes in particle size, morphology, and DNA binding were investigated by dynamic light scattering, transmission electron microscopy, and electrophoresis assay in a reduction environment. Cytotoxicity and transfection in vitro were evaluated in a murine melanoma cell line (B16F10 and a human cervical epithelial carcinoma cell line (HeLa, while intracellular degradation and dissociation with DNA were studied by confocal laser scanning microscopy with FITC-labeled OEI800 derivatives and Cy5-labeled DNA.Results: Diselenide-conjugated OEI800 (OEI800-Se Sex polymer carriers of high molecular weight were successfully synthesized. After compacting with DNA, the OEI800-SeSex polymers formed nanoparticles with an average size of 140 nm at an adequate C/P ratio. OEI800-Se Sex showed reduction-responsive degradation properties similar to those of the OEI800-SSx via gel permeation chromatography, dynamic light scattering, and transmission electron microscopy. OEI800-SeSex showed much lower cytotoxicity than PEI25k

  20. The extended regulatory networks of SXT/R391 integrative and conjugative elements and IncA/C conjugative plasmids.

    Science.gov (United States)

    Poulin-Laprade, Dominic; Carraro, Nicolas; Burrus, Vincent

    2015-01-01

    Nowadays, healthcare systems are challenged by a major worldwide drug resistance crisis caused by the massive and rapid dissemination of antibiotic resistance genes and associated emergence of multidrug resistant pathogenic bacteria, in both clinical and environmental settings. Conjugation is the main driving force of gene transfer among microorganisms. This mechanism of horizontal gene transfer mediates the translocation of large DNA fragments between two bacterial cells in direct contact. Integrative and conjugative elements (ICEs) of the SXT/R391 family (SRIs) and IncA/C conjugative plasmids (ACPs) are responsible for the dissemination of a broad spectrum of antibiotic resistance genes among diverse species of Enterobacteriaceae and Vibrionaceae. The biology, diversity, prevalence and distribution of these two families of conjugative elements have been the subject of extensive studies for the past 15 years. Recently, the transcriptional regulators that govern their dissemination through the expression of ICE- or plasmid-encoded transfer genes have been described. Unrelated repressors control the activation of conjugation by preventing the expression of two related master activator complexes in both types of elements, i.e., SetCD in SXT/R391 ICEs and AcaCD in IncA/C plasmids. Finally, in addition to activating ICE- or plasmid-borne genes, these master activators have been shown to specifically activate phylogenetically unrelated mobilizable genomic islands (MGIs) that also disseminate antibiotic resistance genes and other adaptive traits among a plethora of pathogens such as Vibrio cholerae and Salmonella enterica.

  1. The extended regulatory networks of SXT/R391 integrative and conjugative elements and IncA/C conjugative plasmids.

    Directory of Open Access Journals (Sweden)

    Dominic ePoulin-Laprade

    2015-08-01

    Full Text Available Nowadays, healthcare systems are challenged by a major worldwide drug resistance crisis caused by the massive and rapid dissemination of antibiotic resistance genes and associated emergence of multidrug resistant pathogenic bacteria, in both clinical and environmental settings. Conjugation is the main driving force of gene transfer among microorganisms. This mechanism of horizontal gene transfer mediates the translocation of large DNA fragments between two bacterial cells in direct contact. Integrative and conjugative elements (ICEs of the SXT/R391 family (SRIs and IncA/C conjugative plasmids (ACPs are responsible for the dissemination of a broad spectrum of antibiotic resistance genes among diverse species of Enterobacteriaceae and Vibrionaceae. The biology, diversity, prevalence and distribution of these two families of conjugative elements have been the subject of extensive studies for the past 15 years. Recently, the transcriptional regulators that govern their dissemination through the expression of ICE- or plasmid-encoded transfer genes have been described. Unrelated repressors control the activation of conjugation by preventing the expression of two related master activator complexes in both types of elements, i.e. SetCD in SXT/R391 ICEs and AcaCD in IncA/C plasmids. Finally, in addition to activating ICE- or plasmid-borne genes, these master activators have been shown to specifically activate phylogenetically unrelated mobilizable genomic islands (MGIs that also disseminate antibiotic resistance genes and other adaptive traits among a plethora of pathogens such as Vibrio cholerae and Salmonella enterica.

  2. Dissemination of antimicrobial resistance in microbial ecosystems through horizontal gene transfer

    Directory of Open Access Journals (Sweden)

    Christian Johannes Hendrik Von Wintersdorff

    2016-02-01

    Full Text Available The emergence and spread of antibiotic resistance among pathogenic bacteria has been a rising problem for public health in recent decades. It is becoming increasingly recognized that not only antibiotic resistance genes (ARGs encountered in clinical pathogens are of relevance, but rather, all pathogenic, commensal as well as environmental bacteria – and also mobile genetic elements and bacteriophages – form a reservoir of ARGs (the resistome from which pathogenic bacteria can acquire resistance via horizontal gene transfer (HGT. HGT has caused antibiotic resistance to spread from commensal and environmental species to pathogenic ones, as has been shown for some clinically important ARGs. Of the three canonical mechanisms of HGT, conjugation is thought to have the greatest influence on the dissemination of ARGs. While transformation and transduction are deemed less important, recent discoveries suggest their role may be larger than previously thought. Understanding the extent of the resistome and how its mobilization to pathogenic bacteria takes place is essential for efforts to control the dissemination of these genes. Here, we will discuss the concept of the resistome, provide examples of HGT of clinically relevant ARGs and present an overview of the current knowledge of the contributions the various HGT mechanisms make to the spread of antibiotic resistance.

  3. Characterization of an ancient lepidopteran lateral gene transfer.

    Directory of Open Access Journals (Sweden)

    David Wheeler

    Full Text Available Bacteria to eukaryote lateral gene transfers (LGT are an important potential source of material for the evolution of novel genetic traits. The explosion in the number of newly sequenced genomes provides opportunities to identify and characterize examples of these lateral gene transfer events, and to assess their role in the evolution of new genes. In this paper, we describe an ancient lepidopteran LGT of a glycosyl hydrolase family 31 gene (GH31 from an Enterococcus bacteria. PCR amplification between the LGT and a flanking insect gene confirmed that the GH31 was integrated into the Bombyx mori genome and was not a result of an assembly error. Database searches in combination with degenerate PCR on a panel of 7 lepidopteran families confirmed that the GH31 LGT event occurred deep within the Order approximately 65-145 million years ago. The most basal species in which the LGT was found is Plutella xylostella (superfamily: Yponomeutoidea. Array data from Bombyx mori shows that GH31 is expressed, and low dN/dS ratios indicates the LGT coding sequence is under strong stabilizing selection. These findings provide further support for the proposition that bacterial LGTs are relatively common in insects and likely to be an underappreciated source of adaptive genetic material.

  4. Polybrene increases the efficiency of gene transfer by lipofection.

    Science.gov (United States)

    Abe, A; Miyanohara, A; Friedmann, T

    1998-05-01

    Lipofection involves the introduction of foreign genetic information into mammalian cells through the use of lipophilic reagents that enhance cellular uptake of polynucleotides. Despite the use of currently optimized lipofection conditions, including the use of serum-depleted media, the efficiency of gene transfer is often low. We show here that, in a variety of cell lines, polybrene markedly enhances the efficiency of lipofection under standardized conditions and also compensates the serum-mediated inhibition of lipofection. Although the degree of the polybrene effect depends on the nature of the cell line, these results indicate that individually optimized concentrations of polybrene can be useful for increasing the efficiency of lipofectin-mediated gene transfer in vitro.

  5. The interconnection between biofilm formation and horizontal gene transfer

    DEFF Research Database (Denmark)

    Madsen, Jonas Stenløkke; Burmølle, Mette; Hansen, Lars H.

    2012-01-01

    Recent research has revealed that horizontal gene transfer and biofilm formation are connected processes. Although published research investigating this interconnectedness is still limited, we will review this subject in order to highlight the potential of these observations because....... Biofilms, furthermore, promote plasmid stability and may enhance the host range of mobile genetic elements that are transferred horizontally. Plasmids, on the other hand, are very well suited to promote the evolution of social traits such as biofilm formation. This, essentially, transpires because plasmids...... of their believed importance in the understanding of the adaptation and subsequent evolution of social traits in bacteria. Here, we discuss current evidence for such interconnectedness centred on plasmids. Horizontal transfer rates are typically higher in biofilm communities compared with those in planktonic states...

  6. Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

    Science.gov (United States)

    Ji, Yongbin; Ma, Chao; Ge, Bing; Zang, Shusheng

    2016-08-01

    A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.

  7. A sensitivity function-based conjugate gradient method for optical tomography with the frequency-domain equation of radiative transfer

    International Nuclear Information System (INIS)

    Kim, Hyun Keol; Charette, Andre

    2007-01-01

    The Sensitivity Function-based Conjugate Gradient Method (SFCGM) is described. This method is used to solve the inverse problems of function estimation, such as the local maps of absorption and scattering coefficients, as applied to optical tomography for biomedical imaging. A highly scattering, absorbing, non-reflecting, non-emitting medium is considered here and simultaneous reconstructions of absorption and scattering coefficients inside the test medium are achieved with the proposed optimization technique, by using the exit intensity measured at boundary surfaces. The forward problem is solved with a discrete-ordinates finite-difference method on the framework of the frequency-domain full equation of radiative transfer. The modulation frequency is set to 600 MHz and the frequency data, obtained with the source modulation, is used as the input data. The inversion results demonstrate that the SFCGM can retrieve simultaneously the spatial distributions of optical properties inside the medium within a reasonable accuracy, by significantly reducing a cross-talk between inter-parameters. It is also observed that the closer-to-detector objects are better retrieved

  8. Gene Transfer in Eukaryotic Cells Using Activated Dendrimers

    Science.gov (United States)

    Dennig, Jörg

    Gene transfer into eukaryotic cells plays an important role in cell biology. Over the last 30 years a number of transfection methods have been developed to mediate gene transfer into eukaryotic cells. Classical methods include co-precipitation of DNA with calcium phosphate, charge-dependent precipitation of DNA with DEAE-dextran, electroporation of nucleic acids, and formation of transfection complexes between DNA and cationic liposomes. Gene transfer technologies based on activated PAMAM-dendrimers provide another class of transfection reagents. PAMAM-dendrimers are highly branched, spherical molecules. Activation of newly synthesized dendrimers involves hydrolytic removal of some of the branches, and results in a molecule with a higher degree of flexibility. Activated dendrimers assemble DNA into compact structures via charge interactions. Activated dendrimer - DNA complexes bind to the cell membrane of eukaryotic cells, and are transported into the cell by non-specific endocytosis. A structural model of the activated dendrimer - DNA complex and a potential mechanism for its uptake into cells will be discussed.

  9. Differences in lateral gene transfer in hypersaline versus thermal environments.

    Science.gov (United States)

    Rhodes, Matthew E; Spear, John R; Oren, Aharon; House, Christopher H

    2011-07-08

    The role of lateral gene transfer (LGT) in the evolution of microorganisms is only beginning to be understood. While most LGT events occur between closely related individuals, inter-phylum and inter-domain LGT events are not uncommon. These distant transfer events offer potentially greater fitness advantages and it is for this reason that these "long distance" LGT events may have significantly impacted the evolution of microbes. One mechanism driving distant LGT events is microbial transformation. Theoretically, transformative events can occur between any two species provided that the DNA of one enters the habitat of the other. Two categories of microorganisms that are well-known for LGT are the thermophiles and halophiles. We identified potential inter-class LGT events into both a thermophilic class of Archaea (Thermoprotei) and a halophilic class of Archaea (Halobacteria). We then categorized these LGT genes as originating in thermophiles and halophiles respectively. While more than 68% of transfer events into Thermoprotei taxa originated in other thermophiles, less than 11% of transfer events into Halobacteria taxa originated in other halophiles. Our results suggest that there is a fundamental difference between LGT in thermophiles and halophiles. We theorize that the difference lies in the different natures of the environments. While DNA degrades rapidly in thermal environments due to temperature-driven denaturization, hypersaline environments are adept at preserving DNA. Furthermore, most hypersaline environments, as topographical minima, are natural collectors of cellular debris. Thus halophiles would in theory be exposed to a greater diversity and quantity of extracellular DNA than thermophiles.

  10. Conjugation and Evaluation of Triazole?Linked Single Guide RNA for CRISPR?Cas9 Gene Editing

    OpenAIRE

    He, Kaizhang; Chou, Eldon T.; Begay, Shawn; Anderson, Emily M.; van?Brabant?Smith, Anja

    2016-01-01

    Abstract The CRISPR?Cas9 gene editing system requires Cas9 endonuclease and guide RNAs (either the natural dual RNA consisting of crRNA and tracrRNA or a chimeric single guide RNA) that direct site?specific double?stranded DNA cleavage. This communication describes a click ligation approach that uses alkyne?azide cycloaddition to generate a triazole?linked single guide RNA (sgRNA). The conjugated sgRNA shows efficient and comparable genome editing activity to natural dual RNA and unmodified s...

  11. Phylogeographic support for horizontal gene transfer involving sympatric bruchid species

    Directory of Open Access Journals (Sweden)

    Grill Andrea

    2006-07-01

    Full Text Available Abstract Background We report on the probable horizontal transfer of a mitochondrial gene, cytb, between species of Neotropical bruchid beetles, in a zone where these species are sympatric. The bruchid beetles Acanthoscelides obtectus, A. obvelatus, A. argillaceus and Zabrotes subfasciatus develop on various bean species in Mexico. Whereas A. obtectus and A. obvelatus develop on Phaseolus vulgaris in the Mexican Altiplano, A. argillaceus feeds on P. lunatus in the Pacific coast. The generalist Z. subfasciatus feeds on both bean species, and is sympatric with A. obtectus and A. obvelatus in the Mexican Altiplano, and with A. argillaceus in the Pacific coast. In order to assess the phylogenetic position of these four species, we amplified and sequenced one nuclear (28S rRNA and two mitochondrial (cytb, COI genes. Results Whereas species were well segregated in topologies obtained for COI and 28S rRNA, an unexpected pattern was obtained in the cytb phylogenetic tree. In this tree, individuals from A. obtectus and A. obvelatus, as well as Z. subfasciatus individuals from the Mexican Altiplano, clustered together in a unique little variable monophyletic unit. In contrast, A. argillaceus and Z. subfasciatus individuals from the Pacific coast clustered in two separated clades, identically to the pattern obtained for COI and 28S rRNA. An additional analysis showed that Z. subfasciatus individuals from the Mexican Altiplano also possessed the cytb gene present in individuals of this species from the Pacific coast. Zabrotes subfasciatus individuals from the Mexican Altiplano thus demonstrated two cytb genes, an "original" one and an "infectious" one, showing 25% of nucleotide divergence. The "infectious" cytb gene seems to be under purifying selection and to be expressed in mitochondria. Conclusion The high degree of incongruence of the cytb tree with patterns for other genes is discussed in the light of three hypotheses: experimental contamination

  12. Phylogeographic support for horizontal gene transfer involving sympatric bruchid species.

    Science.gov (United States)

    Alvarez, Nadir; Benrey, Betty; Hossaert-McKey, Martine; Grill, Andrea; McKey, Doyle; Galtier, Nicolas

    2006-07-27

    We report on the probable horizontal transfer of a mitochondrial gene, cytb, between species of Neotropical bruchid beetles, in a zone where these species are sympatric. The bruchid beetles Acanthoscelides obtectus, A. obvelatus, A. argillaceus and Zabrotes subfasciatus develop on various bean species in Mexico. Whereas A. obtectus and A. obvelatus develop on Phaseolus vulgaris in the Mexican Altiplano, A. argillaceus feeds on P. lunatus in the Pacific coast. The generalist Z. subfasciatus feeds on both bean species, and is sympatric with A. obtectus and A. obvelatus in the Mexican Altiplano, and with A. argillaceus in the Pacific coast. In order to assess the phylogenetic position of these four species, we amplified and sequenced one nuclear (28S rRNA) and two mitochondrial (cytb, COI) genes. Whereas species were well segregated in topologies obtained for COI and 28S rRNA, an unexpected pattern was obtained in the cytb phylogenetic tree. In this tree, individuals from A. obtectus and A. obvelatus, as well as Z. subfasciatus individuals from the Mexican Altiplano, clustered together in a unique little variable monophyletic unit. In contrast, A. argillaceus and Z. subfasciatus individuals from the Pacific coast clustered in two separated clades, identically to the pattern obtained for COI and 28S rRNA. An additional analysis showed that Z. subfasciatus individuals from the Mexican Altiplano also possessed the cytb gene present in individuals of this species from the Pacific coast. Zabrotes subfasciatus individuals from the Mexican Altiplano thus demonstrated two cytb genes, an "original" one and an "infectious" one, showing 25% of nucleotide divergence. The "infectious" cytb gene seems to be under purifying selection and to be expressed in mitochondria. The high degree of incongruence of the cytb tree with patterns for other genes is discussed in the light of three hypotheses: experimental contamination, hybridization, and pseudogenisation. However, none of these

  13. Dietary conjugated linoleic acid modify gene expression in liver, muscles, and fat tissues of finishing pigs

    DEFF Research Database (Denmark)

    Tous, Nuria; Theil, Peter Kappel; Lauridsen, Charlotte

    2012-01-01

    The aim of this study was to investigate underlying mechanisms of dietary conjugated linoleic acid (CLA) on lipid metabolism in various tissues of pigs. Sixteen gilts (73 ± 3 kg) were fed a control (containing sunflower oil) or an experimental diet in which 4% of sunflower oil was replaced by CLA...

  14. Ultrafast Photoinduced Electron Transfer in a π-Conjugated Oligomer/Porphyrin Complex

    KAUST Repository

    Aly, Shawkat Mohammede

    2014-10-02

    Controlling charge transfer (CT), charge separation (CS), and charge recombination (CR) at the donor-acceptor interface is extremely important to optimize the conversion efficiency in solar cell devices. In general, ultrafast CT and slow CR are desirable for optimal device performance. In this Letter, the ultrafast excited-state CT between platinum oligomer (DPP-Pt(acac)) as a new electron donor and porphyrin as an electron acceptor is monitored for the first time using femtosecond (fs) transient absorption (TA) spectroscopy with broad-band capability and 120 fs temporal resolution. Turning the CT on/off has been shown to be possible either by switching from an organometallic oligomer to a metal-free oligomer or by controlling the charge density on the nitrogen atom of the porphyrin meso unit. Our time-resolved data show that the CT and CS between DPP-Pt(acac) and cationic porphyrin are ultrafast (approximately 1.5 ps), and the CR is slow (ns time scale), as inferred from the formation and the decay of the cationic and anionic species. We also found that the metallic center in the DPP-Pt(acac) oligomer and the positive charge on the porphyrin are the keys to switching on/off the ultrafast CT process.

  15. IMPROVEMENT METHOD OF GENE TRANSFER IN Kappaphycus alvarezii

    Directory of Open Access Journals (Sweden)

    St. Hidayah Triana

    2016-11-01

    Full Text Available Method of foreign gene transfer in red seaweed Kappaphycus alvarezii has been reported, however, li-mited number of transgenic F0 (broodstock was obtained. This study was conducted to improve the method of gene transfer mediated by Agrobacterium tumefaciens in order to obtain high percentage of K. alvarezii transgenic. Superoxide dismutase gene from Melastoma malabatrichum (MmCu/Zn-SOD was used as model towards increasing adaptability of K. alvarezii to environmental stress. The treat-ments were the culture media and recovery duration, and each treatment consisted of three replica-tions. The best method was co-cultivation using liquid media, then recovery was conducted in liquid media for 10 days. That treatment allowed higher transformation percentage (90%, regeneration effi-ciency (90%, putative bud efficiency (100%, number of buds and explants sprouted (100% and transgenic explants (100%. The transgenic explants showed an amplification PCR product of Mm-Cu/Zn-SOD gene fragment, whereas the non-transgenic explants showed no amplification product.  All results revealed that suitable method of transgenesis for K. alvarezii has been developed. Keywords:       Agrobacterium tumefaciens, culture media, Kappaphycus alvarezii, recovery duration, transformation

  16. Horizontal Gene Transfer Contributes to the Evolution of Arthropod Herbivory.

    Science.gov (United States)

    Wybouw, Nicky; Pauchet, Yannick; Heckel, David G; Van Leeuwen, Thomas

    2016-06-27

    Within animals, evolutionary transition toward herbivory is severely limited by the hostile characteristics of plants. Arthropods have nonetheless counteracted many nutritional and defensive barriers imposed by plants and are currently considered as the most successful animal herbivores in terrestrial ecosystems. We gather a body of evidence showing that genomes of various plant feeding insects and mites possess genes whose presence can only be explained by horizontal gene transfer (HGT). HGT is the asexual transmission of genetic information between reproductively isolated species. Although HGT is known to have great adaptive significance in prokaryotes, its impact on eukaryotic evolution remains obscure. Here, we show that laterally transferred genes into arthropods underpin many adaptations to phytophagy, including efficient assimilation and detoxification of plant produced metabolites. Horizontally acquired genes and the traits they encode often functionally diversify within arthropod recipients, enabling the colonization of more host plant species and organs. We demonstrate that HGT can drive metazoan evolution by uncovering its prominent role in the adaptations of arthropods to exploit plants. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  17. PCR-based detection of gene transfer vectors: application to gene doping surveillance.

    Science.gov (United States)

    Perez, Irene C; Le Guiner, Caroline; Ni, Weiyi; Lyles, Jennifer; Moullier, Philippe; Snyder, Richard O

    2013-12-01

    Athletes who illicitly use drugs to enhance their athletic performance are at risk of being banned from sports competitions. Consequently, some athletes may seek new doping methods that they expect to be capable of circumventing detection. With advances in gene transfer vector design and therapeutic gene transfer, and demonstrations of safety and therapeutic benefit in humans, there is an increased probability of the pursuit of gene doping by athletes. In anticipation of the potential for gene doping, assays have been established to directly detect complementary DNA of genes that are top candidates for use in doping, as well as vector control elements. The development of molecular assays that are capable of exposing gene doping in sports can serve as a deterrent and may also identify athletes who have illicitly used gene transfer for performance enhancement. PCR-based methods to detect foreign DNA with high reliability, sensitivity, and specificity include TaqMan real-time PCR, nested PCR, and internal threshold control PCR.

  18. Lateral Gene Transfer Dynamics in the Ancient Bacterial Genus Streptomyces.

    Science.gov (United States)

    McDonald, Bradon R; Currie, Cameron R

    2017-06-06

    Lateral gene transfer (LGT) profoundly shapes the evolution of bacterial lineages. LGT across disparate phylogenetic groups and genome content diversity between related organisms suggest a model of bacterial evolution that views LGT as rampant and promiscuous. It has even driven the argument that species concepts and tree-based phylogenetics cannot be applied to bacteria. Here, we show that acquisition and retention of genes through LGT are surprisingly rare in the ubiquitous and biomedically important bacterial genus Streptomyces Using a molecular clock, we estimate that the Streptomyces bacteria are ~380 million years old, indicating that this bacterial genus is as ancient as land vertebrates. Calibrating LGT rate to this geologic time span, we find that on average only 10 genes per million years were acquired and subsequently maintained. Over that same time span, Streptomyces accumulated thousands of point mutations. By explicitly incorporating evolutionary timescale into our analyses, we provide a dramatically different view on the dynamics of LGT and its impact on bacterial evolution. IMPORTANCE Tree-based phylogenetics and the use of species as units of diversity lie at the foundation of modern biology. In bacteria, these pillars of evolutionary theory have been called into question due to the observation of thousands of lateral gene transfer (LGT) events within and between lineages. Here, we show that acquisition and retention of genes through LGT are exceedingly rare in the bacterial genus Streptomyces , with merely one gene acquired in Streptomyces lineages every 100,000 years. These findings stand in contrast to the current assumption of rampant genetic exchange, which has become the dominant hypothesis used to explain bacterial diversity. Our results support a more nuanced understanding of genetic exchange, with LGT impacting evolution over short timescales but playing a significant role over long timescales. Deeper understanding of LGT provides new

  19. Deciphering conjugative plasmid permissiveness in wastewater microbiomes

    DEFF Research Database (Denmark)

    Jacquiod, Samuel Jehan Auguste; Brejnrod, Asker Daniel; Milani, Stefan Morberg

    2017-01-01

    Wastewater treatment plants (WWTPs) are designed to robustly treat polluted water. They are characterized by ceaseless flows of organic, chemical and microbial matter, followed by treatment steps before environmental release. WWTPs are hotspots of horizontal gene transfer between bacteria via...... still remains largely uncharted. Furthermore, current in vitro methods used to assess conjugation in complex microbiomes do not include in situ behaviours of recipient cells, resulting in partial understanding of transfers. We investigated the in vitro conjugation capacities of WWTP microbiomes from...... inlet sewage and outlet treated water using the broad-host range IncP-1 conjugative plasmid, pKJK5. A thorough molecular approach coupling metagenomes to 16S rRNA DNA/cDNA amplicon sequencing was established to characterize microbiomes using the ecological concept of functional response groups. A broad...

  20. Gene ontology based transfer learning for protein subcellular localization

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    Zhou Shuigeng

    2011-02-01

    Full Text Available Abstract Background Prediction of protein subcellular localization generally involves many complex factors, and using only one or two aspects of data information may not tell the true story. For this reason, some recent predictive models are deliberately designed to integrate multiple heterogeneous data sources for exploiting multi-aspect protein feature information. Gene ontology, hereinafter referred to as GO, uses a controlled vocabulary to depict biological molecules or gene products in terms of biological process, molecular function and cellular component. With the rapid expansion of annotated protein sequences, gene ontology has become a general protein feature that can be used to construct predictive models in computational biology. Existing models generally either concatenated the GO terms into a flat binary vector or applied majority-vote based ensemble learning for protein subcellular localization, both of which can not estimate the individual discriminative abilities of the three aspects of gene ontology. Results In this paper, we propose a Gene Ontology Based Transfer Learning Model (GO-TLM for large-scale protein subcellular localization. The model transfers the signature-based homologous GO terms to the target proteins, and further constructs a reliable learning system to reduce the adverse affect of the potential false GO terms that are resulted from evolutionary divergence. We derive three GO kernels from the three aspects of gene ontology to measure the GO similarity of two proteins, and derive two other spectrum kernels to measure the similarity of two protein sequences. We use simple non-parametric cross validation to explicitly weigh the discriminative abilities of the five kernels, such that the time & space computational complexities are greatly reduced when compared to the complicated semi-definite programming and semi-indefinite linear programming. The five kernels are then linearly merged into one single kernel for

  1. Nucleofection: A New Method for Cutaneous Gene Transfer?

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    Frank Jacobsen

    2006-01-01

    Full Text Available Background. Transfection efficacy after nonviral gene transfer in primary epithelial cells is limited. The aim of this study was to compare transfection efficacy of the recently available method of nucleofection with the established transfection reagent FuGENE6. Methods. Primary human keratinocytes (HKC, primary human fibroblasts (HFB, and a human keratinocyte cell line (HaCaT were transfected with reporter gene construct by FuGENE6 or Amaxa Nucleofector device. At corresponding time points, β-galactosidase expression, cell proliferation (MTT-Test, transduction efficiency (X-gal staining, cell morphology, and cytotoxicity (CASY were determined. Results. Transgene expression after nucleofection was significantly higher in HKC and HFB and detected earlier (3 h vs. 24 h than in FuGENE6. After lipofection 80%–90% of the cells remained proliferative without any influence on cell morphology. In contrast, nucleofection led to a decrease in keratinocyte cell size, with only 20%–42% proliferative cells. Conclusion. Related to the method-dependent increase of cytotoxicity, transgene expression after nucleofection was earlier and higher than after lipofection.

  2. Nucleofection: A New Method for Cutaneous Gene Transfer?

    Science.gov (United States)

    Jacobsen, Frank; Mertens-Rill, Janine; Beller, Juergen; Hirsch, Tobias; Daigeler, Adrien; Langer, Stefan; Lehnhardt, Marcus; Steinau, Hans-Ulrich; Steinstraesser, Lars

    2006-01-01

    Background. Transfection efficacy after nonviral gene transfer in primary epithelial cells is limited. The aim of this study was to compare transfection efficacy of the recently available method of nucleofection with the established transfection reagent FuGENE6. Methods. Primary human keratinocytes (HKC), primary human fibroblasts (HFB), and a human keratinocyte cell line (HaCaT) were transfected with reporter gene construct by FuGENE6 or Amaxa Nucleofector device. At corresponding time points, β-galactosidase expression, cell proliferation (MTT-Test), transduction efficiency (X-gal staining), cell morphology, and cytotoxicity (CASY) were determined. Results. Transgene expression after nucleofection was significantly higher in HKC and HFB and detected earlier (3 h vs. 24 h) than in FuGENE6. After lipofection 80%–90% of the cells remained proliferative without any influence on cell morphology. In contrast, nucleofection led to a decrease in keratinocyte cell size, with only 20%–42% proliferative cells. Conclusion. Related to the method-dependent increase of cytotoxicity, transgene expression after nucleofection was earlier and higher than after lipofection. PMID:17489014

  3. Photoinduced electron transfer between Fe(III) and adenosine triphosphate-BODIPY conjugates: Application to alkaline-phosphatase-linked immunoassay.

    Science.gov (United States)

    Lin, Jia-Hui; Yang, Ya-Chun; Shih, Ya-Chen; Hung, Szu-Ying; Lu, Chi-Yu; Tseng, Wei-Lung

    2016-03-15

    Fluorescent boron dipyrromethene (BODIPY) analogs are often used as sensors for detecting various species because of their relatively high extinction coefficients, outstanding fluorescence quantum yields, photostability, and pH-independent fluorescence. However, there is little-to-no information in the literature that describes the use of BODIPY analogs for detecting alkaline phosphatase (ALP) activity and inhibition. This study discovered that the fluorescence of BODIPY-conjugated adenosine triphosphate (BODIPY-ATP) was quenched by Fe(III) ions through photoinduced electron transfer. The ALP-catalyzed hydrolysis of BODIPY-ATP resulted in the formation of BODIPY-adenosine and phosphate ions. The fluorescence of the generated BODIPY-adenosine was insensitive to the change in the concentration of Fe(III) ions. Thus, the Fe(III)-induced fluorescence quenching of BODIPY-ATP can be paired with its ALP-mediated dephosphorylation to design a turn-on fluorescence probe for ALP sensing. A method detection limit at a signal-to-noise ratio of 3 for ALP was estimated to be 0.02 units/L (~6 pM; 1 ng/mL). This probe was used for the screening of ALP inhibitors, including Na3VO4, imidazole, and arginine. Because ALP is widely used in enzyme-linked immunosorbent assays, the probe was coupled to an ALP-linked immunosorbent assay for the sensitive and selective detection of immunoglobulin G (IgG). The lowest detectable concentration for IgG in this system was 5 ng/mL. Compared with the use of 3,6-fluorescein diphosphate as a signal reporter in an ALP-linked immunosorbent assay, the proposed system provided comparable sensitivity, large linear range, and high stability over temperature and pH changes. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Silencing of BCR/ABL Chimeric Gene in Human Chronic Myelogenous Leukemia Cell Line K562 by siRNA-Nuclear Export Signal Peptide Conjugates.

    Science.gov (United States)

    Shinkai, Yasuhiro; Kashihara, Shinichi; Minematsu, Go; Fujii, Hirofumi; Naemura, Madoka; Kotake, Yojiro; Morita, Yasutaka; Ohnuki, Koichiro; Fokina, Alesya A; Stetsenko, Dmitry A; Filichev, Vyacheslav V; Fujii, Masayuki

    2017-06-01

    Herein we described the synthesis of siRNA-NES (nuclear export signal) peptide conjugates by solid phase fragment coupling and the application of them to silencing of bcr/abl chimeric gene in human chronic myelogenous leukemia cell line K562. Two types of siRNA-NES conjugates were prepared, and both sense strands at 5' ends were covalently linked to a NES peptide derived from TFIIIA and HIV-1 REV, respectively. Significant enhancement of silencing efficiency was observed for both of them. siRNA-TFIIIA NES conjugate suppressed the expression of BCR/ABL gene to 8.3% at 200 nM and 11.6% at 50 nM, and siRNA-HIV-1REV NES conjugate suppressed to 4.0% at 200 nM and 6.3% at 50 nM, whereas native siRNA suppressed to 36.3% at 200 nM and 30.2% at 50 nM. We could also show complex of siRNA-NES conjugate and designed amphiphilic peptide peptideβ7 could be taken up into cells with no cytotoxicity and showed excellent silencing efficiency. We believe that the complex siRNA-NES conjugate and peptideβ7 is a promising candidate for in vivo use and therapeutic applications.

  5. Agrobacterium-mediated gene transfer in plants and biosafety considerations.

    Science.gov (United States)

    Mehrotra, Shweta; Goyal, Vinod

    2012-12-01

    Agrobacterium, the natures' genetic engineer, has been used as a vector to create transgenic plants. Agrobacterium-mediated gene transfer in plants is a highly efficient transformation process which is governed by various factors including genotype of the host plant, explant, vector, plasmid, bacterial strain, composition of culture medium, tissue damage, and temperature of co-cultivation. Agrobacterium has been successfully used to transform various economically and horticulturally important monocot and dicot species by standard tissue culture and in planta transformation techniques like floral or seedling infilteration, apical meristem transformation, and the pistil drip methods. Monocots have been comparatively difficult to transform by Agrobacterium. However, successful transformations have been reported in the last few years based on the adjustment of the parameters that govern the responses of monocots to Agrobacterium. A novel Agrobacterium transferred DNA-derived nanocomplex method has been developed which will be highly valuable for plant biology and biotechnology. Agrobacterium-mediated genetic transformation is known to be the preferred method of creating transgenic plants from a commercial and biosafety perspective. Agrobacterium-mediated gene transfer predominantly results in the integration of foreign genes at a single locus in the host plant, without associated vector backbone and is also known to produce marker free plants, which are the prerequisites for commercialization of transgenic crops. Research in Agrobacterium-mediated transformation can provide new and novel insights into the understanding of the regulatory process controlling molecular, cellular, biochemical, physiological, and developmental processes occurring during Agrobacterium-mediated transformation and also into a wide range of aspects on biological safety of transgenic crops to improve crop production to meet the demands of ever-growing world's population.

  6. Differences in lateral gene transfer in hypersaline versus thermal environments

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    House Christopher H

    2011-07-01

    Full Text Available Abstract Background The role of lateral gene transfer (LGT in the evolution of microorganisms is only beginning to be understood. While most LGT events occur between closely related individuals, inter-phylum and inter-domain LGT events are not uncommon. These distant transfer events offer potentially greater fitness advantages and it is for this reason that these "long distance" LGT events may have significantly impacted the evolution of microbes. One mechanism driving distant LGT events is microbial transformation. Theoretically, transformative events can occur between any two species provided that the DNA of one enters the habitat of the other. Two categories of microorganisms that are well-known for LGT are the thermophiles and halophiles. Results We identified potential inter-class LGT events into both a thermophilic class of Archaea (Thermoprotei and a halophilic class of Archaea (Halobacteria. We then categorized these LGT genes as originating in thermophiles and halophiles respectively. While more than 68% of transfer events into Thermoprotei taxa originated in other thermophiles, less than 11% of transfer events into Halobacteria taxa originated in other halophiles. Conclusions Our results suggest that there is a fundamental difference between LGT in thermophiles and halophiles. We theorize that the difference lies in the different natures of the environments. While DNA degrades rapidly in thermal environments due to temperature-driven denaturization, hypersaline environments are adept at preserving DNA. Furthermore, most hypersaline environments, as topographical minima, are natural collectors of cellular debris. Thus halophiles would in theory be exposed to a greater diversity and quantity of extracellular DNA than thermophiles.

  7. Gene expression profiles in rat mesenteric lymph nodes upon supplementation with Conjugated Linoleic Acid during gestation and suckling

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    Rivero Montserrat

    2011-04-01

    Full Text Available Abstract Background Diet plays a role on the development of the immune system, and polyunsaturated fatty acids can modulate the expression of a variety of genes. Human milk contains conjugated linoleic acid (CLA, a fatty acid that seems to contribute to immune development. Indeed, recent studies carried out in our group in suckling animals have shown that the immune function is enhanced after feeding them with an 80:20 isomer mix composed of c9,t11 and t10,c12 CLA. However, little work has been done on the effects of CLA on gene expression, and even less regarding immune system development in early life. Results The expression profile of mesenteric lymph nodes from animals supplemented with CLA during gestation and suckling through dam's milk (Group A or by oral gavage (Group B, supplemented just during suckling (Group C and control animals (Group D was determined with the aid of the specific GeneChip® Rat Genome 230 2.0 (Affymettrix. Bioinformatics analyses were performed using the GeneSpring GX software package v10.0.2 and lead to the identification of 89 genes differentially expressed in all three dietary approaches. Generation of a biological association network evidenced several genes, such as connective tissue growth factor (Ctgf, tissue inhibitor of metalloproteinase 1 (Timp1, galanin (Gal, synaptotagmin 1 (Syt1, growth factor receptor bound protein 2 (Grb2, actin gamma 2 (Actg2 and smooth muscle alpha actin (Acta2, as highly interconnected nodes of the resulting network. Gene underexpression was confirmed by Real-Time RT-PCR. Conclusions Ctgf, Timp1, Gal and Syt1, among others, are genes modulated by CLA supplementation that may have a role on mucosal immune responses in early life.

  8. Gene Transfer and Molecular Cloning of the Human NGF Receptor

    Science.gov (United States)

    Chao, Moses V.; Bothwell, Mark A.; Ross, Alonzo H.; Koprowski, Hilary; Lanahan, Anthony A.; Buck, C. Randall; Sehgal, Amita

    1986-04-01

    Nerve growth factor (NGF) and its receptor are important in the development of cells derived from the neural crest. Mouse L cell transformants have been generated that stably express the human NGF receptor gene transfer with total human DNA. Affinity cross-linking, metabolic labeling and immunoprecipitation, and equilibrium binding with 125I-labeled NGF revealed that this NGF receptor had the same size and binding characteristics as the receptor from human melanoma cells and rat PC12 cells. The sequences encoding the NGF receptor were molecularly cloned using the human Alu repetitive sequence as a probe. A cosmid clone that contained the human NGF receptor gene allowed efficient transfection and expression of the receptor.

  9. Lightning-triggered electroporation and electrofusion as possible contributors to natural horizontal gene transfer.

    Science.gov (United States)

    Kotnik, Tadej

    2013-09-01

    Phylogenetic studies show that horizontal gene transfer (HGT) is a significant contributor to genetic variability of prokaryotes, and was perhaps even more abundant during the early evolution. Hitherto, research of natural HGT has mainly focused on three mechanisms of DNA transfer: conjugation, natural competence, and viral transduction. This paper discusses the feasibility of a fourth such mechanism--cell electroporation and/or electrofusion triggered by atmospheric electrostatic discharges (lightnings). A description of electroporation as a phenomenon is followed by a review of experimental evidence that electroporation of prokaryotes in aqueous environments can result in release of non-denatured DNA, as well as uptake of DNA from the surroundings and transformation. Similarly, a description of electrofusion is followed by a review of experiments showing that prokaryotes devoid of cell wall can electrofuse into hybrids expressing the genes of their both precursors. Under sufficiently fine-tuned conditions, electroporation and electrofusion are efficient tools for artificial transformation and hybridization, respectively, but the quantitative analysis developed here shows that conditions for electroporation-based DNA release, DNA uptake and transformation, as well as for electrofusion are also present in many natural aqueous environments exposed to lightnings. Electroporation is thus a plausible contributor to natural HGT among prokaryotes, and could have been particularly important during the early evolution, when the other mechanisms might have been scarcer or nonexistent. In modern prokaryotes, natural absence of the cell wall is rare, but it is reasonable to assume that the wall has formed during a certain stage of evolution, and at least prior to this, electrofusion could also have contributed to natural HGT. The concluding section outlines several guidelines for assessment of the feasibility of lightning-triggered HGT. © 2013 Elsevier B.V. All rights

  10. Energy Transfer between Conjugated Colloidal Ga2O3 and CdSe/CdS Core/Shell Nanocrystals for White Light Emitting Applications

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    Paul C. Stanish

    2016-02-01

    Full Text Available Developing solid state materials capable of generating homogeneous white light in an energy efficient and resource-sustainable way is central to the design of new and improved devices for various lighting applications. Most currently-used phosphors depend on strategically important rare earth elements, and rely on a multicomponent approach, which produces sub-optimal quality white light. Here, we report the design and preparation of a colloidal white-light emitting nanocrystal conjugate. This conjugate is obtained by linking colloidal Ga2O3 and II–VI nanocrystals in the solution phase with a short bifunctional organic molecule (thioglycolic acid. The two types of nanocrystals are electronically coupled by Förster resonance energy transfer owing to the short separation between Ga2O3 (energy donor and core/shell CdSe/CdS (energy acceptor nanocrystals, and the spectral overlap between the photoluminescence of the donor and the absorption of the acceptor. Using steady state and time-resolved photoluminescence spectroscopies, we quantified the contribution of the energy transfer to the photoluminescence spectral power distribution and the corresponding chromaticity of this nanocrystal conjugate. Quantitative understanding of this new system allows for tuning of the emission color and the design of quasi-single white light emitting inorganic phosphors without the use of rare-earth elements.

  11. Energy Transfer between Conjugated Colloidal Ga2O3 and CdSe/CdS Core/Shell Nanocrystals for White Light Emitting Applications

    Science.gov (United States)

    Stanish, Paul C.; Radovanovic, Pavle V.

    2016-01-01

    Developing solid state materials capable of generating homogeneous white light in an energy efficient and resource-sustainable way is central to the design of new and improved devices for various lighting applications. Most currently-used phosphors depend on strategically important rare earth elements, and rely on a multicomponent approach, which produces sub-optimal quality white light. Here, we report the design and preparation of a colloidal white-light emitting nanocrystal conjugate. This conjugate is obtained by linking colloidal Ga2O3 and II–VI nanocrystals in the solution phase with a short bifunctional organic molecule (thioglycolic acid). The two types of nanocrystals are electronically coupled by Förster resonance energy transfer owing to the short separation between Ga2O3 (energy donor) and core/shell CdSe/CdS (energy acceptor) nanocrystals, and the spectral overlap between the photoluminescence of the donor and the absorption of the acceptor. Using steady state and time-resolved photoluminescence spectroscopies, we quantified the contribution of the energy transfer to the photoluminescence spectral power distribution and the corresponding chromaticity of this nanocrystal conjugate. Quantitative understanding of this new system allows for tuning of the emission color and the design of quasi-single white light emitting inorganic phosphors without the use of rare-earth elements. PMID:28344289

  12. Gene Transfer Enhancement by Alkylcarboxylation of Poly(propylenimine

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    Maryam Hashemi

    2013-01-01

    Full Text Available Abstract Among synthetic carriers, dendrimers with the more flexible structure have attracted a great deal of researchers’ attention in the field of gene delivery. Followed by the promising results upon hydrophobic modification on polymeric structures in our laboratory, alkylcarboxylated poly (propylenimine-based carriers were synthesized by nucleophilic substitution of amines with alkyl moieties and were further characterized for their physicochemical and biological characteristics for plasmid DNA delivery. Although not noticeably effective gene transfer activity for hexanoate- and hexadecanoate-modified series was observed, but alkylation by decanoic acid significantly improved the transfection efficiency of the final constructs up to 60 fold in comparison with unmodified poly(propylenimine (PPI. PPI modified by 10-bromodecanoic acid at 50% grafting, showed significantly higher gene expression at c/p ratio of 2 compared to Superfect as positive control.  Overall, modification of PPI with 50% primary amines grafting with 10-bromodecanoic acid could increase the transfection efficiency which is occurred at lower c/p ratio when compared to Superfect, i.e. less amount of modified vector is required to exhibit the same efficiency as Superfect. Therefore, the obtained constructs seem to be safer carriers for long-term gene therapy applications.

  13. Horizontal gene transfer and mobile genetic elements in marine systems.

    Science.gov (United States)

    Sobecky, Patricia A; Hazen, Tracy H

    2009-01-01

    The pool of mobile genetic elements (MGE) in microbial communities consists of viruses, plasmids, and associated elements (insertion sequences, transposons, and integrons) that are either self-transmissible or use mobile plasmids and viruses as vehicles for their dissemination. This mobilome facilitates the horizontal transfer of genes that promote the evolution and adaptation of microbial communities. Efforts to characterize MGEs from microbial populations resident in a variety of ecological habitats have revealed a surprisingly novel and seemingly untapped biodiversity. To better understand the impact of horizontal gene transfer (HGT), as well as the agents that promote HGT in marine ecosystems and to determine whether or not environmental parameters can effect the composition and structure of the mobilome in marine microbial communities, information on the distribution, diversity, and ecological traits of the marine mobilome is presented. In this chapter we discuss recent insights gained from different methodological approaches used to characterize the biodiversity and ecology of MGE in marine environments and their contributions to HGT. In addition, we present case studies that highlight specific HGT examples in coastal, open-ocean, and deep-sea marine ecosystems.

  14. Recombinant adenovirus-mediated gene transfer suppresses experimental arthritis

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    E. Quattrocchi

    2011-09-01

    Full Text Available Collagen Induced Arthritis (CIA is a widely studied animal model to develop and test novel therapeutic approaches for treating Rheumatoid Arthritis (RA in humans. Soluble Cytotoxic T-Lymphocyte Antigen 4 (CTLA4-Ig, which binds B7 molecule on antigen presenting cells and blocks CD28 mediated T-lymphocyte activation, has been shown to ameliorate experimental autoimmune diseases such as lupus, diabetes and CIA. Objective of our research was to investigate in vivo the effectiveness of blocking the B7/CD28 T-lymphocyte co-stimulatory pathway, utilizing a gene transfer technology, as a therapeutic strategy against CIA. Replication-deficient adenoviruses encoding a chimeric CTLA4-Ig fusion protein, or β-galactosidase as control, have been injected intravenously once at arthritis onset. Disease activity has been monitored by the assessment of clinical score, paw thickness and type II collagen (CII specific cellular and humoral immune responses for 21 days. The adenovirally delivered CTLA4-Ig fusion protein at a dose of 2×108 pfu suppressed established CIA, whereas the control β-galactosidase did not significantly affect the disease course. CII-specific lymphocyte proliferation, IFNg production and anti-CII antibodies were significantly reduced by CTLA4-Ig treatment. Our results demonstrate that blockade of the B7/CD28 co-stimulatory pathway by adenovirus-mediated CTLA4-Ig gene transfer is effective in treating established CIA suggesting its potential in treating RA.

  15. Ubiquitin-conjugating enzyme E2-like gene associated to pathogen response in Concholepas concholepas: SNP identification and transcription expression.

    Science.gov (United States)

    Núñez-Acuña, Gustavo; Aguilar-Espinoza, Andrea; Chávez-Mardones, Jacqueline; Gallardo-Escárate, Cristian

    2012-10-01

    Ubiquitin-conjugated E2 enzyme (UBE2) is one of the main components of the proteasome degradation cascade. Previous studies have shown an increase of expression levels in individuals challenged to some pathogen organism such as virus and bacteria. The study was to characterize the immune response of UBE2 gene in the gastropod Concholepas concholepas through expression analysis and single nucleotide polymorphisms (SNP) discovery. Hence, UBE2 was identified from a cDNA library by 454 pyrosequencing, while SNP identification and validation were performed using De novo assembly and high resolution melting analysis. Challenge trials with Vibrio anguillarum was carried out to evaluate the relative transcript abundance of UBE2 gene from two to thirty-three hours post-treatment. The results showed a partial UBE2 sequence of 889 base pair (bp) with a partial coding region of 291 bp. SNP variation (A/C) was observed at the 546th position. Individuals challenged by V. anguillarum showed an overexpression of the UBE2 gene, the expression being significantly higher in homozygous individuals (AA) than (CC) or heterozygous individuals (A/C). This study contributes useful information relating to the UBE2 gene and its association with innate immune response in marine invertebrates. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. GENE TRANSFER IN TOBACCO MITOCHONDRIA IN VITRO AND IN VIVO

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    Katyshev A.I.

    2012-08-01

    Full Text Available Earlier, we had showed that isolated mitochondria from different organisms can import DNA. Exploiting this mechanism, we assessed the possibility of genes transfer in tobacco mitochondria in vitro and in vivo. Whereas homologous recombination is a rare occasion in higher plant nuclei, recombination between the large direct repeats in plant mitochondrial genome generates its multipartite structure. Following transfection of isolated organelles with constructs composed of a partial gfp gene flanked by mitochondrial DNA fragments, we showed the homologous recombination of imported DNA with the resident DNA and the integration of the reporter gene. The recombination yielded an insertion of a continuous exogenous DNA fragment including the gfp sequence and at least the 0.5 kb of the flanking sequence on each side. Using of transfection constructs carrying multiple sequences homologous to mitochondrial DNA could be suitable for insertion of a target gene into any region of the mitochondrial genome, which turns this approach to be of a general and methodical importance. Usually mitochondrial reactive oxygen species (ROS level is under strict control of the antioxidant system including the Mn-containing superoxide dismutase (MnSOD. MnSOD is presented in multiple forms encoded by several genes in plants. Possibly, this enzyme, beside its catalytic function, fulfills as well some unknown biochemical functions. Thus, one of maize SOD enzymes (SOD3.4 could bind with mitochondrial DNA. Another SOD form (SOD3.1 is located in close proximity to mitochondrial respiratory complexes, where ROS are generated. To study possible physiological functions of this enzyme, we cloned the maize SOD3.1 gene. Compared to the SOD3.4, this enzyme didn't demonstrate DNA-binding activity. At the same time, SOD3.1 didn't show non-specific DNA-hydrolyzing activity as Cu/ZnSOD does. It means that this enzyme might have some DNA protective function. We made NtPcob-sod3.1-IGR

  17. AAV5-Factor VIII Gene Transfer in Severe Hemophilia A.

    Science.gov (United States)

    Rangarajan, Savita; Walsh, Liron; Lester, Will; Perry, David; Madan, Bella; Laffan, Michael; Yu, Hua; Vettermann, Christian; Pierce, Glenn F; Wong, Wing Y; Pasi, K John

    2017-12-28

    Patients with hemophilia A rely on exogenous factor VIII to prevent bleeding in joints, soft tissue, and the central nervous system. Although successful gene transfer has been reported in patients with hemophilia B, the large size of the factor VIII coding region has precluded improved outcomes with gene therapy in patients with hemophilia A. We infused a single intravenous dose of a codon-optimized adeno-associated virus serotype 5 (AAV5) vector encoding a B-domain-deleted human factor VIII (AAV5-hFVIII-SQ) in nine men with severe hemophilia A. Participants were enrolled sequentially into one of three dose cohorts (low dose [one participant], intermediate dose [one participant], and high dose [seven participants]) and were followed through 52 weeks. Factor VIII activity levels remained at 3 IU or less per deciliter in the recipients of the low or intermediate dose. In the high-dose cohort, the factor VIII activity level was more than 5 IU per deciliter between weeks 2 and 9 after gene transfer in all seven participants, and the level in six participants increased to a normal value (>50 IU per deciliter) that was maintained at 1 year after receipt of the dose. In the high-dose cohort, the median annualized bleeding rate among participants who had previously received prophylactic therapy decreased from 16 events before the study to 1 event after gene transfer, and factor VIII use for participant-reported bleeding ceased in all the participants in this cohort by week 22. The primary adverse event was an elevation in the serum alanine aminotransferase level to 1.5 times the upper limit of the normal range or less. Progression of preexisting chronic arthropathy in one participant was the only serious adverse event. No neutralizing antibodies to factor VIII were detected. The infusion of AAV5-hFVIII-SQ was associated with the sustained normalization of factor VIII activity level over a period of 1 year in six of seven participants who received a high dose, with

  18. Conjugation Inhibitors and Their Potential Use to Prevent Dissemination of Antibiotic Resistance Genes in Bacteria

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    Elena Cabezón

    2017-11-01

    Full Text Available Antibiotic resistance has become one of the most challenging problems in health care. Bacteria conjugation is one of the main mechanisms whereby bacteria become resistant to antibiotics. Therefore, the search for specific conjugation inhibitors (COINs is of interest in the fight against the spread of antibiotic resistances in a variety of laboratory and natural environments. Several compounds, discovered as COINs, are promising candidates in the fight against plasmid dissemination. In this review, we survey the effectiveness and toxicity of the most relevant compounds. Particular emphasis has been placed on unsaturated fatty acid derivatives, as they have been shown to be efficient in preventing plasmid invasiveness in bacterial populations. Biochemical and structural studies have provided insights concerning their potential molecular targets and inhibitory mechanisms. These findings open a new avenue in the search of new and more effective synthetic inhibitors. In this pursuit, the use of structure-based drug design methods will be of great importance for the screening of ligands and binding sites of putative targets.

  19. Modeling horizontal gene transfer (HGT in the gut of the Chagas disease vector Rhodnius prolixus

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    Durvasula Ravi V

    2011-05-01

    Full Text Available Abstract Background Paratransgenesis is an approach to reducing arthropod vector competence using genetically modified symbionts. When applied to control of Chagas disease, the symbiont bacterium Rhodococcus rhodnii, resident in the gut lumen of the triatomine vector Rhodnius prolixus (Hemiptera: Reduviidae, is transformed to export cecropin A, an insect immune peptide. Cecropin A is active against Trypanosoma cruzi, the causative agent of Chagas disease. While proof of concept has been achieved in laboratory studies, a rigorous and comprehensive risk assessment is required prior to consideration of field release. An important part of this assessment involves estimating probability of transgene horizontal transfer to environmental organisms (HGT. This article presents a two-part risk assessment methodology: a theoretical model predicting HGT in the gut of R. prolixus from the genetically transformed symbiont R. rhodnii to a closely related non-target bacterium, Gordona rubropertinctus, in the absence of selection pressure, and a series of laboratory trials designed to test the model. Results The model predicted an HGT frequency of less than 1.14 × 10-16 per 100,000 generations at the 99% certainty level. The model was iterated twenty times, with the mean of the ten highest outputs evaluated at the 99% certainty level. Laboratory trials indicated no horizontal gene transfer, supporting the conclusions of the model. Conclusions The model treats HGT as a composite event, the probability of which is determined by the joint probability of three independent events: gene transfer through the modalities of transformation, transduction, and conjugation. Genes are represented in matrices and Monte Carlo method and Markov chain analysis are used to simulate and evaluate environmental conditions. The model is intended as a risk assessment instrument and predicts HGT frequency of less than 1.14 × 10-16 per 100,000 generations. With laboratory studies that

  20. Adaptive Horizontal Gene Transfers between Multiple Cheese-Associated Fungi.

    Science.gov (United States)

    Ropars, Jeanne; Rodríguez de la Vega, Ricardo C; López-Villavicencio, Manuela; Gouzy, Jérôme; Sallet, Erika; Dumas, Émilie; Lacoste, Sandrine; Debuchy, Robert; Dupont, Joëlle; Branca, Antoine; Giraud, Tatiana

    2015-10-05

    Domestication is an excellent model for studies of adaptation because it involves recent and strong selection on a few, identified traits [1-5]. Few studies have focused on the domestication of fungi, with notable exceptions [6-11], despite their importance to bioindustry [12] and to a general understanding of adaptation in eukaryotes [5]. Penicillium fungi are ubiquitous molds among which two distantly related species have been independently selected for cheese making-P. roqueforti for blue cheeses like Roquefort and P. camemberti for soft cheeses like Camembert. The selected traits include morphology, aromatic profile, lipolytic and proteolytic activities, and ability to grow at low temperatures, in a matrix containing bacterial and fungal competitors [13-15]. By comparing the genomes of ten Penicillium species, we show that adaptation to cheese was associated with multiple recent horizontal transfers of large genomic regions carrying crucial metabolic genes. We identified seven horizontally transferred regions (HTRs) spanning more than 10 kb each, flanked by specific transposable elements, and displaying nearly 100% identity between distant Penicillium species. Two HTRs carried genes with functions involved in the utilization of cheese nutrients or competition and were found nearly identical in multiple strains and species of cheese-associated Penicillium fungi, indicating recent selective sweeps; they were experimentally associated with faster growth and greater competitiveness on cheese and contained genes highly expressed in the early stage of cheese maturation. These findings have industrial and food safety implications and improve our understanding of the processes of adaptation to rapid environmental changes. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. The role of the achiral template in enantioselective transformations. Radical conjugate additions to alpha-methacrylates followed by hydrogen atom transfer.

    Science.gov (United States)

    Sibi, Mukund P; Sausker, Justin B

    2002-02-13

    We have evaluated various achiral templates (1a-g, 10, and 16) in conjunction with chiral Lewis acids in the conjugate addition of nucleophilic radicals to alpha-methacrylates followed by enantioselective H-atom transfer. Of these, a novel naphthosultam template (10) gave high enantioselectivity in the H-atom-transfer reactions with ee's up to 90%. A chiral Lewis acid derived from MgBr(2) and bisoxazoline (2) gave the highest selectivity in the enantioselective hydrogen-atom-transfer reactions. Non-C(2) symmetric oxazolines (20-25) have also been examined as ligands, and of these, compound 25 gave optimal results (87% yield and 80% ee). Insights into rotamer control in alpha-substituted acrylates and the critical role of the tetrahedral sulfone moiety in realizing high selectivity are discussed.

  2. Lateral Gene Transfer Dynamics in the Ancient Bacterial Genus Streptomyces

    Directory of Open Access Journals (Sweden)

    Bradon R. McDonald

    2017-06-01

    Full Text Available Lateral gene transfer (LGT profoundly shapes the evolution of bacterial lineages. LGT across disparate phylogenetic groups and genome content diversity between related organisms suggest a model of bacterial evolution that views LGT as rampant and promiscuous. It has even driven the argument that species concepts and tree-based phylogenetics cannot be applied to bacteria. Here, we show that acquisition and retention of genes through LGT are surprisingly rare in the ubiquitous and biomedically important bacterial genus Streptomyces. Using a molecular clock, we estimate that the Streptomyces bacteria are ~380 million years old, indicating that this bacterial genus is as ancient as land vertebrates. Calibrating LGT rate to this geologic time span, we find that on average only 10 genes per million years were acquired and subsequently maintained. Over that same time span, Streptomyces accumulated thousands of point mutations. By explicitly incorporating evolutionary timescale into our analyses, we provide a dramatically different view on the dynamics of LGT and its impact on bacterial evolution.

  3. Adenovirus gene transfer to amelogenesis imperfecta ameloblast-like cells.

    Directory of Open Access Journals (Sweden)

    Anton V Borovjagin

    Full Text Available To explore gene therapy strategies for amelogenesis imperfecta (AI, a human ameloblast-like cell population was established from third molars of an AI-affected patient. These cells were characterized by expression of cytokeratin 14, major enamel proteins and alkaline phosphatase staining. Suboptimal transduction of the ameloblast-like cells by an adenovirus type 5 (Ad5 vector was consistent with lower levels of the coxsackie-and-adenovirus receptor (CAR on those cells relative to CAR-positive A549 cells. To overcome CAR -deficiency, we evaluated capsid-modified Ad5 vectors with various genetic capsid modifications including "pK7" and/or "RGD" motif-containing short peptides incorporated in the capsid protein fiber as well as fiber chimera with the Ad serotype 3 (Ad3 fiber "knob" domain. All fiber modifications provided an augmented transduction of AI-ameloblasts, revealed following vector dose normalization in A549 cells with a superior effect (up to 404-fold of pK7/RGD double modification. This robust infectivity enhancement occurred through vector binding to both α(vβ3/α(vβ5 integrins and heparan sulfate proteoglycans (HSPGs highly expressed by AI-ameloblasts as revealed by gene transfer blocking experiments. This work thus not only pioneers establishment of human AI ameloblast-like cell population as a model for in vitro studies but also reveals an optimal infectivity-enhancement strategy for a potential Ad5 vector-mediated gene therapy for AI.

  4. Numerical analysis of natural convection and radiation heat transfer from various shaped thin fin-arrays placed on a horizontal plate-a conjugate analysis

    International Nuclear Information System (INIS)

    Dogan, M.; Sivrioglu, Mecit; Yılmaz, Onder

    2014-01-01

    Highlights: • Optimum fin shape is determined for natural convection and radiation heat transfer. • Fin array with the optimum shape has a much greater average heat transfer coefficient. • The most important factors affecting the heat transfer coefficient are determined. - Abstract: Steady state natural convection and radiation heat transfer from various shaped thin fin-arrays on a horizontal base plate has been numerically investigated. A conjugate analysis has been carried out in which the conservation equations of mass, momentum and energy for the fluid in the two fin enclosure are solved together with the heat conduction equation in the fin and the base plate. Heat transfer by radiation is also considered in analysis. The heat transfer coefficient has been determined for each of the fin array considered in the present study at the same base and the same total area. The results of the analysis show that there are some important geometrical factors affecting the design of fin arrays. Taking into consideration these factors, an optimum fin shape that yields the highest average heat transfer coefficient has been determined

  5. The Ubiquitin-Conjugating Enzyme Gene Family in Longan (Dimocarpus longan Lour.: Genome-Wide Identification and Gene Expression during Flower Induction and Abiotic Stress Responses

    Directory of Open Access Journals (Sweden)

    Dengwei Jue

    2018-03-01

    Full Text Available Ubiquitin-conjugating enzymes (E2s or UBC enzymes play vital roles in plant development and combat various biotic and abiotic stresses. Longan (Dimocarpus longan Lour. is an important fruit tree in the subtropical region of Southeast Asia and Australia; however the characteristics of the UBC gene family in longan remain unknown. In this study, 40 D. longan UBC genes (DlUBCs, which were classified into 15 groups, were identified in the longan genome. An RNA-seq based analysis showed that DlUBCs showed distinct expression in nine longan tissues. Genome-wide RNA-seq and qRT-PCR based gene expression analysis revealed that 11 DlUBCs were up- or down-regualted in the cultivar “Sijimi” (SJ, suggesting that these genes may be important for flower induction. Finally, qRT-PCR analysis showed that the mRNA levels of 13 DlUBCs under SA (salicylic acid treatment, seven under methyl jasmonate (MeJA treatment, 27 under heat treatment, and 16 under cold treatment were up- or down-regulated, respectively. These results indicated that the DlUBCs may play important roles in responses to abiotic stresses. Taken together, our results provide a comprehensive insight into the organization, phylogeny, and expression patterns of the longan UBC genes, and therefore contribute to the greater understanding of their biological roles in longan.

  6. Identification of a Novel Conjugative Plasmid in Mycobacteria That Requires Both Type IV and Type VII Secretion

    KAUST Repository

    Ummels, R.

    2014-09-23

    Conjugative plasmids have been identified in a wide variety of different bacteria, ranging from proteobacteria to firmicutes, and conjugation is one of the most efficient routes for horizontal gene transfer. The most widespread mechanism of plasmid conjugation relies on different variants of the type IV secretion pathway. Here, we describe the identification of a novel type of conjugative plasmid that seems to be unique for mycobacteria. Interestingly, while this plasmid is efficiently exchanged between different species of slow-growing mycobacteria, including Mycobacterium tuberculosis, it could not be transferred to any of the fast-growing mycobacteria tested. Genetic analysis of the conjugative plasmid showed the presence of a locus containing homologues of three type IV secretion system components and a relaxase. In addition, a new type VII secretion locus was present. Using transposon insertion mutagenesis, we show that in fact both these secretion systems are essential for conjugation, indicating that this plasmid represents a new class of conjugative plasmids requiring two secretion machineries. This plasmid could form a useful new tool to exchange or introduce DNA in slow-growing mycobacteria. IMPORTANCE: Conjugative plasmids play an important role in horizontal gene transfer between different bacteria and, as such, in their adaptation and evolution. This effect is most obvious in the spread of antibiotic resistance genes. Thus far, conjugation of natural plasmids has been described only rarely for mycobacterial species. In fact, it is generally accepted that M. tuberculosis does not show any recent sign of horizontal gene transfer. In this study, we describe the identification of a new widespread conjugative plasmid that can also be efficiently transferred to M. tuberculosis. This plasmid therefore poses both a threat and an opportunity. The threat is that, through the acquisition of antibiotic resistance markers, this plasmid could start a rapid spread of

  7. Kidney-specific Sonoporation-mediated Gene Transfer.

    Science.gov (United States)

    Ishida, Ryo; Kami, Daisuke; Kusaba, Tetsuro; Kirita, Yuhei; Kishida, Tsunao; Mazda, Osam; Adachi, Takaomi; Gojo, Satoshi

    2016-02-01

    Sonoporation can deliver agents to target local organs by systemic administration, while decreasing the associated risk of adverse effects. Sonoporation has been used for a variety of materials and in a variety of organs. Herein, we demonstrated that local sonoporation to the kidney can offer highly efficient transfer of oligonucleotides, which were systemically administrated to the tubular epithelium with high specificity. Ultrasonic wave irradiation to the kidney collapsed the microbubbles and transiently affected the glomerular filtration barrier and increased glomerular permeability. Oligonucleotides were passed through the barrier all at once and were absorbed throughout the tubular epithelium. Tumor necrosis factor alpha (TNFα), which plays a central role in renal ischemia-reperfusion injury, was targeted using small interfering RNA (siRNA) with renal sonoporation in a murine model. The reduction of TNFα expression after single gene transfer significantly inhibited the expression of kidney injury markers, suggesting that systemic administration of siRNA under temporary and local sonoporation could be applicable in the clinical setting of ischemic acute kidney injury.

  8. Center for Fetal Monkey Gene Transfer for Heart, Lung, and Blood Diseases: An NHLBI Resource for the Gene Therapy Community

    Science.gov (United States)

    Skarlatos, Sonia I.

    2012-01-01

    Abstract The goals of the National Heart, Lung, and Blood Institute (NHLBI) Center for Fetal Monkey Gene Transfer for Heart, Lung, and Blood Diseases are to conduct gene transfer studies in monkeys to evaluate safety and efficiency; and to provide NHLBI-supported investigators with expertise, resources, and services to actively pursue gene transfer approaches in monkeys in their research programs. NHLBI-supported projects span investigators throughout the United States and have addressed novel approaches to gene delivery; “proof-of-principle”; assessed whether findings in small-animal models could be demonstrated in a primate species; or were conducted to enable new grant or IND submissions. The Center for Fetal Monkey Gene Transfer for Heart, Lung, and Blood Diseases successfully aids the gene therapy community in addressing regulatory barriers, and serves as an effective vehicle for advancing the field. PMID:22974119

  9. Photoinduced electron transfer in a Watson-Crick base-paired, 2-aminopurine:uracil-C60 hydrogen bonding conjugate.

    Science.gov (United States)

    D'Souza, Francis; Gadde, Suresh; Islam, D-M Shafiqul; Pang, Siew-Cheng; Schumacher, Amy Lea; Zandler, Melvin E; Horie, Rumiko; Araki, Yasuyaki; Ito, Osamu

    2007-02-07

    A fluorescent reporter molecule, 2-aminopurine was self-assembled via Watson-Crick base-pairing to a uracil appended fullerene to form a donor-acceptor conjugate; efficient photoinduced charge separation was confirmed by time-resolved emission and transient absorption spectral studies.

  10. Effect of the environment on horizontal gene transfer between bacteria and archaea.

    Science.gov (United States)

    Fuchsman, Clara A; Collins, Roy Eric; Rocap, Gabrielle; Brazelton, William J

    2017-01-01

    Horizontal gene transfer, the transfer and incorporation of genetic material between different species of organisms, has an important but poorly quantified role in the adaptation of microbes to their environment. Previous work has shown that genome size and the number of horizontally transferred genes are strongly correlated. Here we consider how genome size confuses the quantification of horizontal gene transfer because the number of genes an organism accumulates over time depends on its evolutionary history and ecological context (e.g., the nutrient regime for which it is adapted). We investigated horizontal gene transfer between archaea and bacteria by first counting reciprocal BLAST hits among 448 bacterial and 57 archaeal genomes to find shared genes. Then we used the DarkHorse algorithm, a probability-based, lineage-weighted method (Podell & Gaasterland, 2007), to identify potential horizontally transferred genes among these shared genes. By removing the effect of genome size in the bacteria, we have identified bacteria with unusually large numbers of shared genes with archaea for their genome size. Interestingly, archaea and bacteria that live in anaerobic and/or high temperature conditions are more likely to share unusually large numbers of genes. However, high salt was not found to significantly affect the numbers of shared genes. Numbers of shared (genome size-corrected, reciprocal BLAST hits) and transferred genes (identified by DarkHorse) were strongly correlated. Thus archaea and bacteria that live in anaerobic and/or high temperature conditions are more likely to share horizontally transferred genes. These horizontally transferred genes are over-represented by genes involved in energy conversion as well as the transport and metabolism of inorganic ions and amino acids. Anaerobic and thermophilic bacteria share unusually large numbers of genes with archaea. This is mainly due to horizontal gene transfer of genes from the archaea to the bacteria. In

  11. Effect of the environment on horizontal gene transfer between bacteria and archaea

    Directory of Open Access Journals (Sweden)

    Clara A. Fuchsman

    2017-09-01

    Full Text Available Background Horizontal gene transfer, the transfer and incorporation of genetic material between different species of organisms, has an important but poorly quantified role in the adaptation of microbes to their environment. Previous work has shown that genome size and the number of horizontally transferred genes are strongly correlated. Here we consider how genome size confuses the quantification of horizontal gene transfer because the number of genes an organism accumulates over time depends on its evolutionary history and ecological context (e.g., the nutrient regime for which it is adapted. Results We investigated horizontal gene transfer between archaea and bacteria by first counting reciprocal BLAST hits among 448 bacterial and 57 archaeal genomes to find shared genes. Then we used the DarkHorse algorithm, a probability-based, lineage-weighted method (Podell & Gaasterland, 2007, to identify potential horizontally transferred genes among these shared genes. By removing the effect of genome size in the bacteria, we have identified bacteria with unusually large numbers of shared genes with archaea for their genome size. Interestingly, archaea and bacteria that live in anaerobic and/or high temperature conditions are more likely to share unusually large numbers of genes. However, high salt was not found to significantly affect the numbers of shared genes. Numbers of shared (genome size-corrected, reciprocal BLAST hits and transferred genes (identified by DarkHorse were strongly correlated. Thus archaea and bacteria that live in anaerobic and/or high temperature conditions are more likely to share horizontally transferred genes. These horizontally transferred genes are over-represented by genes involved in energy conversion as well as the transport and metabolism of inorganic ions and amino acids. Conclusions Anaerobic and thermophilic bacteria share unusually large numbers of genes with archaea. This is mainly due to horizontal gene transfer of

  12. Therapeutic misconception in early phase gene transfer trials.

    Science.gov (United States)

    Henderson, Gail E; Easter, Michele M; Zimmer, Catherine; King, Nancy M P; Davis, Arlene M; Rothschild, Barbra Bluestone; Churchill, Larry R; Wilfond, Benjamin S; Nelson, Daniel K

    2006-01-01

    Many subjects in early phase clinical trials expect to benefit in some way from the research intervention. It is understandable that people hope for improvement in their condition, no matter what the evidence. Yet unreasonable expectation of medical benefit may reflect problems with informed consent: Investigators may not disclose clearly that direct medical benefit from an early phase experimental intervention is unlikely or impossible, or subjects may not appreciate the differences between treatment and research. This paper presents findings from recent interviews with researchers and subjects and analysis of consent forms in early phase gene transfer research, a cutting-edge technology often called 'gene therapy'. We use three variables to construct a composite measure of therapeutic misconception TM, tapping misconceptions about the purposes of early phase research and the potential for direct medical benefit in these trials. Our multivariate model demonstrates the importance of both subject- and study-level factors as predictors of this TM index: education, disease type, and communication by study personnel about the likelihood of benefit. We hope that this work will deepen the discussion of how to define and measure TM, and refine the specification of factors that are related to subjects' TM.

  13. What tangled web: barriers to rampant horizontal gene transfer.

    Science.gov (United States)

    Kurland, Charles G

    2005-07-01

    Dawkins in his The Selfish Gene(1) quite aptly applies the term "selfish" to parasitic repetitive DNA sequences endemic to eukaryotic genomes, especially vertebrates. Doolittle and Sapienza(2) as well as Orgel and Crick(3) enlivened this notion of selfish DNA with the identification of such repetitive sequences as remnants of mobile elements such as transposons. In addition, Orgel and Crick(3) associated parasitic DNA with a potential to outgrow their host genomes by propagating both vertically via conventional genome replication as well as infectiously by horizontal gene transfer (HGT) to other genomes. Still later, Doolittle(4) speculated that unchecked HGT between unrelated genomes so complicates phylogeny that the conventional representation of a tree of life would have to be replaced by a thicket or a web of life.(4) In contrast, considerable data now show that reconstructions based on whole genome sequences are consistent with the conventional "tree of life".(5-10) Here, we identify natural barriers that protect modern genome populations from the inroads of rampant HGT. Copyright (c) 2005 Wiley Periodicals, Inc.

  14. Evaluation of biolistic gene transfer methods in vivo using non-invasive bioluminescent imaging techniques

    Directory of Open Access Journals (Sweden)

    Daniell Henry

    2011-06-01

    Full Text Available Abstract Background Gene therapy continues to hold great potential for treating many different types of disease and dysfunction. Safe and efficient techniques for gene transfer and expression in vivo are needed to enable gene therapeutic strategies to be effective in patients. Currently, the most commonly used methods employ replication-defective viral vectors for gene transfer, while physical gene transfer methods such as biolistic-mediated ("gene-gun" delivery to target tissues have not been as extensively explored. In the present study, we evaluated the efficacy of biolistic gene transfer techniques in vivo using non-invasive bioluminescent imaging (BLI methods. Results Plasmid DNA carrying the firefly luciferase (LUC reporter gene under the control of the human Cytomegalovirus (CMV promoter/enhancer was transfected into mouse skin and liver using biolistic methods. The plasmids were coupled to gold microspheres (1 μm diameter using different DNA Loading Ratios (DLRs, and "shot" into target tissues using a helium-driven gene gun. The optimal DLR was found to be in the range of 4-10. Bioluminescence was measured using an In Vivo Imaging System (IVIS-50 at various time-points following transfer. Biolistic gene transfer to mouse skin produced peak reporter gene expression one day after transfer. Expression remained detectable through four days, but declined to undetectable levels by six days following gene transfer. Maximum depth of tissue penetration following biolistic transfer to abdominal skin was 200-300 μm. Similarly, biolistic gene transfer to mouse liver in vivo also produced peak early expression followed by a decline over time. In contrast to skin, however, liver expression of the reporter gene was relatively stable 4-8 days post-biolistic gene transfer, and remained detectable for nearly two weeks. Conclusions The use of bioluminescence imaging techniques enabled efficient evaluation of reporter gene expression in vivo. Our results

  15. Time-accurate CFD conjugate analysis of transient measurements of the heat-transfer coefficient in a channel with pin fins

    Directory of Open Access Journals (Sweden)

    Tom I-P. Shih

    2013-03-01

    Full Text Available Heat-transfer coefficients (HTC on surfaces exposed to convection environments are often measured by transient techniques such as thermochromic liquid crystal (TLC or infrared thermography. In these techniques, the surface temperature is measured as a function of time, and that measurement is used with the exact solution for unsteady, zero-dimensional (0-D or one-dimensional (1-D heat conduction into a solid to calculate the local HTC. When using the 0-D or 1-D exact solutions, the transient techniques assume the HTC and the free-stream or bulk temperature characterizing the convection environment to be constants in addition to assuming the conduction into the solid to be 0-D or 1-D. In this study, computational fluid dynamics (CFD conjugate analyses were performed to examine the errors that might be invoked by these assumptions for a problem, where the free-stream/bulk temperature and the heat-transfer coefficient vary appreciably along the surface and where conduction into the solid may not be 0-D or 1-D. The problem selected to assess these errors is flow and heat transfer in a channel lined with a staggered array of pin fins. This conjugate study uses three-dimensional (3-D unsteady Reynolds-averaged Navier–Stokes (RANS closed by the shear-stress transport (SST turbulence model for the gas phase (wall functions not used and the Fourier law for the solid phase. The errors in the transient techniques are assessed by comparing the HTC predicted by the time-accurate conjugate CFD with those predicted by the 0-D and 1-D exact solutions, where the surface temperatures needed by the exact solutions are taken from the time-accurate conjugate CFD solution. Results obtained show that the use of the 1-D exact solution for the semi-infinite wall to give reasonably accurate “transient” HTC (less than 5% relative error. Transient techniques that use the 0-D exact solution for the pin fins were found to produce large errors (up to 160% relative error

  16. The fosfomycin resistance gene fosB3 is located on a transferable, extrachromosomal circular intermediate in clinical Enterococcus faecium isolates.

    Directory of Open Access Journals (Sweden)

    Xiaogang Xu

    Full Text Available Some VanM-type vancomycin-resistant Enterococcus faecium isolates from China are also resistant to fosfomycin. To investigate the mechanism of fosfomycin resistance in these clinical isolates, antimicrobial susceptibility testing, filter-mating, Illumina/Solexa sequencing, inverse PCR and fosfomycin resistance gene cloning were performed. Three E. faecium clinical isolates were highly resistant to fosfomycin and vancomycin with minimal inhibitory concentrations (MICs >1024 µg/ml and >256 µg/ml, respectively. The fosfomycin and vancomycin resistance of these strains could be co-transferred by conjugation. They carried a fosfomycin resistance gene fosB encoding a protein differing by one or two amino acids from FosB, which is encoded on staphylococcal plasmids. Accordingly, the gene was designated fosB3. The fosB3 gene was cloned into pMD19-T, and transformed into E. coli DH5α. The fosfomycin MIC for transformants with fosB3 was 750-fold higher than transformants without fosB3. The fosB3 gene could be transferred by an extrachromosomal circular intermediate. The results indicate that the fosB3 gene is transferable, can mediate high level fosfomycin resistance in both Gram-positive and Gram-negative bacteria, and can be located on a circular intermediate.

  17. A combined ANN-GA and experimental based technique for the estimation of the unknown heat flux for a conjugate heat transfer problem

    Science.gov (United States)

    M K, Harsha Kumar; P S, Vishweshwara; N, Gnanasekaran; C, Balaji

    2018-05-01

    The major objectives in the design of thermal systems are obtaining the information about thermophysical, transport and boundary properties. The main purpose of this paper is to estimate the unknown heat flux at the surface of a solid body. A constant area mild steel fin is considered and the base is subjected to constant heat flux. During heating, natural convection heat transfer occurs from the fin to ambient. The direct solution, which is the forward problem, is developed as a conjugate heat transfer problem from the fin and the steady state temperature distribution is recorded for any assumed heat flux. In order to model the natural convection heat transfer from the fin, an extended domain is created near the fin geometry and air is specified as a fluid medium and Navier Stokes equation is solved by incorporating the Boussinesq approximation. The computational time involved in executing the forward model is then reduced by developing a neural network (NN) between heat flux values and temperatures based on back propagation algorithm. The conjugate heat transfer NN model is now coupled with Genetic algorithm (GA) for the solution of the inverse problem. Initially, GA is applied to the pure surrogate data, the results are then used as input to the Levenberg- Marquardt method and such hybridization is proven to result in accurate estimation of the unknown heat flux. The hybrid method is then applied for the experimental temperature to estimate the unknown heat flux. A satisfactory agreement between the estimated and actual heat flux is achieved by incorporating the hybrid method.

  18. Transduction-like gene transfer in the methanogen Methanococcus voltae

    Science.gov (United States)

    Bertani, G.

    1999-01-01

    Strain PS of Methanococcus voltae (a methanogenic, anaerobic archaebacterium) was shown to generate spontaneously 4.4-kbp chromosomal DNA fragments that are fully protected from DNase and that, upon contact with a cell, transform it genetically. This activity, here called VTA (voltae transfer agent), affects all markers tested: three different auxotrophies (histidine, purine, and cobalamin) and resistance to BES (2-bromoethanesulfonate, an inhibitor of methanogenesis). VTA was most effectively prepared by culture filtration. This process disrupted a fraction of the M. voltae cells (which have only an S-layer covering their cytoplasmic membrane). VTA was rapidly inactivated upon storage. VTA particles were present in cultures at concentrations of approximately two per cell. Gene transfer activity varied from a minimum of 2 x 10(-5) (BES resistance) to a maximum of 10(-3) (histidine independence) per donor cell. Very little VTA was found free in culture supernatants. The phenomenon is functionally similar to generalized transduction, but there is no evidence, for the time being, of intrinsically viral (i.e., containing a complete viral genome) particles. Consideration of VTA DNA size makes the existence of such viral particles unlikely. If they exist, they must be relatively few in number;perhaps they differ from VTA particles in size and other properties and thus escaped detection. Digestion of VTA DNA with the AluI restriction enzyme suggests that it is a random sample of the bacterial DNA, except for a 0.9-kbp sequence which is amplified relative to the rest of the bacterial chromosome. A VTA-sized DNA fraction was demonstrated in a few other isolates of M. voltae.

  19. CRISPR-Cas and Restriction-Modification Act Additively against Conjugative Antibiotic Resistance Plasmid Transfer in Enterococcus faecalis

    OpenAIRE

    Price, Valerie J.; Huo, Wenwen; Sharifi, Ardalan; Palmer, Kelli L.

    2016-01-01

    ABSTRACT Enterococcus faecalis is an opportunistic pathogen and a leading cause of nosocomial infections. Conjugative pheromone-responsive plasmids are narrow-host-range mobile genetic elements (MGEs) that are rapid disseminators of antibiotic resistance in the faecalis species. Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas and restriction-modification confer acquired and innate immunity, respectively, against MGE acquisition in bacteria. Most multidrug-resistant E.?fa...

  20. Sub-inhibitory concentrations of heavy metals facilitate the horizontal transfer of plasmid-mediated antibiotic resistance genes in water environment.

    Science.gov (United States)

    Zhang, Ye; Gu, April Z; Cen, Tianyu; Li, Xiangyang; He, Miao; Li, Dan; Chen, Jianmin

    2018-06-01

    Although widespread antibiotic resistance has been mostly attributed to the selective pressure generated by overuse and misuse of antibiotics, recent growing evidence suggests that chemicals other than antibiotics, such as certain metals, can also select and stimulate antibiotic resistance via both co-resistance and cross-resistance mechanisms. For instance, tetL, merE, and oprD genes are resistant to both antibiotics and metals. However, the potential de novo resistance induced by heavy metals at environmentally-relevant low concentrations (much below theminimum inhibitory concentrations [MICs], also referred as sub-inhibitory) has hardly been explored. This study investigated and revealed that heavy metals, namely Cu(II), Ag(I), Cr(VI), and Zn(II), at environmentally-relevant and sub-inhibitory concentrations, promoted conjugative transfer of antibiotic resistance genes (ARGs) between E. coli strains. The mechanisms of this phenomenon were further explored, which involved intracellular reactive oxygen species (ROS) formation, SOS response, increased cell membrane permeability, and altered expression of conjugation-relevant genes. These findings suggest that sub-inhibitory levels of heavy metals that widely present in various environments contribute to the resistance phenomena via facilitating horizontal transfer of ARGs. This study provides evidence from multiple aspects implicating the ecological effect of low levels of heavy metals on antibiotic resistance dissemination and highlights the urgency of strengthening efficacious policy and technology to control metal pollutants in the environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. SXT/R391 Integrative and Conjugative Elements (ICEs) Encode a Novel 'Trap-Door' Strategy for Mobile Element Escape.

    Science.gov (United States)

    Ryan, Michael P; Armshaw, Patricia; Pembroke, J Tony

    2016-01-01

    Integrative conjugative elements (ICEs) are a class of bacterial mobile elements that have the ability to mediate their own integration, excision, and transfer from one host genome to another by a mechanism of site-specific recombination, self-circularisation, and conjugative transfer. Members of the SXT/R391 ICE family of enterobacterial mobile genetic elements display an unusual UV-inducible sensitization function which results in stress induced killing of bacterial cells harboring the ICE. This sensitization has been shown to be associated with a stress induced overexpression of a mobile element encoded conjugative transfer gene, orf43, a traV homolog. This results in cell lysis and release of a circular form of the ICE. Induction of this novel system may allow transfer of an ICE, enhancing its survival potential under conditions not conducive to conjugative transfer.

  2. Gene Therapy in Fanconi Anemia: A Matter of Time, Safety and Gene Transfer Tool Efficiency.

    Science.gov (United States)

    Verhoeyen, Els; Roman-Rodriguez, Francisco Jose; Cosset, Francois-Loic; Levy, Camille; Rio, Paula

    2017-01-01

    Fanconi anemia (FA) is a rare genetic syndrome characterized by progressive marrow failure. Gene therapy by infusion of FA-corrected autologous hematopoietic stem cells (HSCs) may offer a potential cure since it is a monogenetic disease with mutations in the FANC genes, coding for DNA repair enzymes [1]. However, the collection of hCD34+-cells in FA patients implies particular challenges because of the reduced numbers of progenitor cells present in their bone marrow (BM) [2] or mobilized peripheral blood [3-5]. In addition, the FA genetic defect fragilizes the HSCs [6]. These particular features might explain why the first clinical trials using murine leukemia virus derived retroviral vectors conducted for FA failed to show engraftment of corrected cells. The gene therapy field is now moving towards the use of lentiviral vectors (LVs) evidenced by recent succesful clinical trials for the treatment of patients suffering from adrenoleukodystrophy (ALD) [7], β-thalassemia [8], metachromatic leukodystrophy [9] and Wiskott-Aldrich syndrome [10]. LV trials for X-linked severe combined immunodificiency and Fanconi anemia (FA) defects were recently initiated [11, 12]. Fifteen years of preclinical studies using different FA mouse models and in vitro research allowed us to find the weak points in the in vitro culture and transduction conditions, which most probably led to the initial failure of FA HSC gene therapy. In this review, we will focus on the different obstacles, unique to FA gene therapy, and how they have been overcome through the development of optimized protocols for FA HSC culture and transduction and the engineering of new gene transfer tools for FA HSCs. These combined advances in the field hopefully will allow the correction of the FA hematological defect in the near future. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. Efficient gene transfer into nondividing cells by adeno-associated virus-based vectors.

    OpenAIRE

    Podsakoff, G; Wong, K K; Chatterjee, S

    1994-01-01

    Gene transfer vectors based on adeno-associated virus (AAV) are emerging as highly promising for use in human gene therapy by virtue of their characteristics of wide host range, high transduction efficiencies, and lack of cytopathogenicity. To better define the biology of AAV-mediated gene transfer, we tested the ability of an AAV vector to efficiently introduce transgenes into nonproliferating cell populations. Cells were induced into a nonproliferative state by treatment with the DNA synthe...

  4. Gene doping detection: evaluation of approach for direct detection of gene transfer using erythropoietin as a model system.

    Science.gov (United States)

    Baoutina, A; Coldham, T; Bains, G S; Emslie, K R

    2010-08-01

    As clinical gene therapy has progressed toward realizing its potential, concern over misuse of the technology to enhance performance in athletes is growing. Although 'gene doping' is banned by the World Anti-Doping Agency, its detection remains a major challenge. In this study, we developed a methodology for direct detection of the transferred genetic material and evaluated its feasibility for gene doping detection in blood samples from athletes. Using erythropoietin (EPO) as a model gene and a simple in vitro system, we developed real-time PCR assays that target sequences within the transgene complementary DNA corresponding to exon/exon junctions. As these junctions are absent in the endogenous gene due to their interruption by introns, the approach allows detection of trace amounts of a transgene in a large background of the endogenous gene. Two developed assays and one commercial gene expression assay for EPO were validated. On the basis of ability of these assays to selectively amplify transgenic DNA and analysis of literature on testing of gene transfer in preclinical and clinical gene therapy, it is concluded that the developed approach would potentially be suitable to detect gene doping through gene transfer by analysis of small volumes of blood using regular out-of-competition testing.

  5. Environmental factors influencing gene transfer agent (GTA mediated transduction in the subtropical ocean.

    Directory of Open Access Journals (Sweden)

    Lauren D McDaniel

    Full Text Available Microbial genomic sequence analyses have indicated widespread horizontal gene transfer (HGT. However, an adequate mechanism accounting for the ubiquity of HGT has been lacking. Recently, high frequencies of interspecific gene transfer have been documented, catalyzed by Gene Transfer Agents (GTAs of marine α-Proteobacteria. It has been proposed that the presence of bacterial genes in highly purified viral metagenomes may be due to GTAs. However, factors influencing GTA-mediated gene transfer in the environment have not yet been determined. Several genomically sequenced strains containing complete GTA sequences similar to Rhodobacter capsulatus (RcGTA, type strain were screened to ascertain if they produced putative GTAs, and at what abundance. Five of nine marine strains screened to date spontaneously produced virus-like particles (VLP's in stationary phase. Three of these strains have demonstrated gene transfer activity, two of which were documented by this lab. These two strains Roseovarius nubinhibens ISM and Nitratireductor 44B9s, were utilized to produce GTAs designated RnGTA and NrGTA and gene transfer activity was verified in culture. Cell-free preparations of purified RnGTA and NrGTA particles from marked donor strains were incubated with natural microbial assemblages to determine the level of GTA-mediated gene transfer. In conjunction, several ambient environmental parameters were measured including lysogeny indicated by prophage induction. GTA production in culture systems indicated that approximately half of the strains produced GTA-like particles and maximal GTA counts ranged from 10-30% of host abundance. Modeling of GTA-mediated gene transfer frequencies in natural samples, along with other measured environmental variables, indicated a strong relationship between GTA mediated gene transfer and the combined factors of salinity, multiplicity of infection (MOI and ambient bacterial abundance. These results indicate that GTA

  6. Gene transfer from wild Helianthus to sunflower: topicalities and limits

    Directory of Open Access Journals (Sweden)

    Breton Catherine

    2010-03-01

    Full Text Available Sunflower (2n=17 belongs to the Helianthus genus (Asteraceae. Wild Helianthus species display morphological variation for branching and stem number, for architecture and seed size, and for resistance to abiotic and biotic stresses due to which they thrive in different environments in North America. The genus is divided into botanical sections, two for annual as sunflower, and two for perennial species as Jerusalem artichoke that produces rhizomes (tubers. We explain the difficulties and successes obtained by crossing sunflower with these species to improve the agronomic traits of the sunflower crop. It is easier to cross the annual species than the perennials’ with sunflower. Several traits such as Cytoplasmic male sterility and restorer Rf-PET1 genes, Downy mildew resistance, Phomopsis resistance, Sclerotinia resistance, Rust resistance, and Orobanche resistance have already been introduced from annual species into sunflower crop, but the complex genomic organization of these species compared to sunflower limits their important potential. Perennial species are much more diverse, and their genomes display 2n, 4n, or 6n chromosomes for n 17. The realities of inter-specific hybridization are relatively disappointing due to the introgression lines that have low oil and low seed yield. We report here several attempts to introgress agronomic traits from these species to sunflower, and we present as a case study, an introgressed progenies from H. mollis, a diploid species with sessile small leaves. We constructed a preliminary genetic map with AFLP markers in 21 BC1 plants, and we then showed that some progenies display 6 to 44% of introgression from H. mollis. Although this study is promising due to the novel compact architecture of the progenies, we cannot estimate the transferability from H. mollis to other perennial Helianthus to improve sunflower.

  7. Patient Perspectives on Gene Transfer Therapy for Sickle Cell Disease.

    Science.gov (United States)

    Strong, Heather; Mitchell, Monica J; Goldstein-Leever, Alana; Shook, Lisa; Malik, Punam; Crosby, Lori E

    2017-08-01

    Sickle cell disease (SCD) is a chronic genetic disease with high morbidity and early mortality; it affects nearly 100,000 individuals in the USA. Bone marrow transplantation, the only curative treatment, is available to less than 20% of patients because of a number of access barriers. Gene transfer therapy (GTT) has been shown to be curative in animal models and is approved for use in humans for early-phase studies at a few centers. GTT would offer a more accessible treatment option available to all patients. It is important to understand patient perspectives on GTT to help ensure human clinical trial success. Two focus groups were conducted with younger (18-30 years) and older (31 years and older) adults with SCD to obtain data on patient knowledge and beliefs about GTT. Data from these two focus groups was used to develop a GTT educational brochure. A third focus group was conducted to obtain participant feedback on acceptability and feasibility of education and the brochure. Most adults, especially young adults, had little knowledge about GTT and expressed fear and uncertainty about the side effects of chemotherapy (e.g., hair loss, infertility), use of a human immunodeficiency virus (HIV)-derived viral vector, and potential for cancer risk. Participants wanted full transparency in educational materials, but advised researchers not to share the vector's relation to HIV because of cultural stigma and no HIV virus is used for the GTT vector. Older adults had more desire to participate in human clinical GTT trials than younger participants. When recruiting for trials, researchers should develop GTT educational materials that address participant lack of trust in the healthcare system, cultural beliefs, fears related to side effects, and include visual illustrations. Use of such materials will provide adults with SCD the information they need to fully evaluate GTT.

  8. A first glimpse into the pattern and scale of gene transfer in the Apicomplexa

    DEFF Research Database (Denmark)

    Huang, J.L.; Mullapudi, N.; Sicheritz-Pontén, Thomas

    2004-01-01

    with a phylogenomic approach to detect potential gene transfers in four apicomplexan genomes. We have detected genes of algal nuclear, chloroplast (cyanobacterial) and proteobacterial origin. Plant-like genes were detected in species not currently harbouring a plastid (e.g. Cryptosporidium parvum) and putatively...

  9. Enhancement of Gene Silencing Effect and Membrane Permeability by Peptide-Conjugated 27-Nucleotide Small Interfering RNA

    Directory of Open Access Journals (Sweden)

    Toshio Seyama

    2012-09-01

    Full Text Available Two different sizes of siRNAs, of which one type was 21-nucleotide (nt siRNA containing 2-nt dangling ends and the other type was 27-nt siRNA with blunt ends, were conjugated with a nuclear export signal peptide of HIV-1 Rev at the 5′-sense end. Processing by Dicer enzyme, cell membrane permeability, and RNAi efficiency of the peptide-conjugated siRNAs were examined. Dicer cleaved the peptide-conjugated 27-nt siRNA leading to the release of 21-nt siRNA, whereas the peptide-conjugated 21-nt siRNA was not cleaved. High membrane permeability and cytoplasmic localization was found in the conjugates. Moreover, the peptide-conjugated 27-nt siRNA showed increased potency of RNAi in comparison with the nonmodified 21-nt and 27-nt siRNAs, whereas the peptide-conjugated 21-nt siRNA showed decreased RNAi efficacy. This potent RNAi efficacy is probably owing to acceleration of RISC through recognition by Dicer, as well as to the improvement of cell membrane permeability and intracellular accumulation.

  10. Excitation energy transfer in ruthenium (II)-porphyrin conjugates led to enhanced emission quantum yield and {sup 1}O{sub 2} generation

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Jie; Jiang, Lijun; Chan, Chi-Fai [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong); Tsoi, Tik-Hung [Department of Applied Biology and Chemical Technology, Hung Hom, Hong Kong Special Administrative Region (Hong Kong); Shiu, Kwok-Keung; Kwong, Daniel W.J. [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong); Wong, Wing-Tak [Department of Applied Biology and Chemical Technology, Hung Hom, Hong Kong Special Administrative Region (Hong Kong); Wong, Wai-Kwok, E-mail: wkwong@hkbu.edu.hk [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong); Wong, Ka-Leung, E-mail: klwong@hkbu.edu.hk [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong)

    2017-04-15

    Porphyrins are good photodynamic therapy (PDT) agents due to its flexibility for modifications to achieve tumor localization and photo-cytotoxicity against cancer. Yet they are not perfect. In a Ru(polypyridyl)-porphyrin system, the Ru(polypyridyl) moiety improves the water solubility and cell permeability. Consider the similar excited state energies between Ru(polypyridyl) and porphyrin moieties; a small perturbation (e.g. Zn(II) metalation) would lead to a marked change in the energy migration process. In this work, we have synthesized a series of porphyrins conjugated with Ru(polypyridyl) complexes using different linkers and investigated their photophysical properties, which included singlet oxygen quantum yield and their in vitro biological properties, resulting from linker variation and porphyrin modification by Zn(II) metalation. - Graphical abstract: Four amphiphilic ruthenium(II)-porphyrin complexes were prepared that display energy transfer conversion with zinc coordination, lysosome specific target, low dark toxicity and efficient photodynamic therapy.

  11. Exact Algorithms for Duplication-Transfer-Loss Reconciliation with Non-Binary Gene Trees.

    Science.gov (United States)

    Kordi, Misagh; Bansal, Mukul S

    2017-06-01

    Duplication-Transfer-Loss (DTL) reconciliation is a powerful method for studying gene family evolution in the presence of horizontal gene transfer. DTL reconciliation seeks to reconcile gene trees with species trees by postulating speciation, duplication, transfer, and loss events. Efficient algorithms exist for finding optimal DTL reconciliations when the gene tree is binary. In practice, however, gene trees are often non-binary due to uncertainty in the gene tree topologies, and DTL reconciliation with non-binary gene trees is known to be NP-hard. In this paper, we present the first exact algorithms for DTL reconciliation with non-binary gene trees. Specifically, we (i) show that the DTL reconciliation problem for non-binary gene trees is fixed-parameter tractable in the maximum degree of the gene tree, (ii) present an exponential-time, but in-practice efficient, algorithm to track and enumerate all optimal binary resolutions of a non-binary input gene tree, and (iii) apply our algorithms to a large empirical data set of over 4700 gene trees from 100 species to study the impact of gene tree uncertainty on DTL-reconciliation and to demonstrate the applicability and utility of our algorithms. The new techniques and algorithms introduced in this paper will help biologists avoid incorrect evolutionary inferences caused by gene tree uncertainty.

  12. The Roles of Mitochondrion in Intergenomic Gene Transfer in Plants: A Source and a Pool

    Directory of Open Access Journals (Sweden)

    Nan Zhao

    2018-02-01

    Full Text Available Intergenomic gene transfer (IGT is continuous in the evolutionary history of plants. In this field, most studies concentrate on a few related species. Here, we look at IGT from a broader evolutionary perspective, using 24 plants. We discover many IGT events by assessing the data from nuclear, mitochondrial and chloroplast genomes. Thus, we summarize the two roles of the mitochondrion: a source and a pool. That is, the mitochondrion gives massive sequences and integrates nuclear transposons and chloroplast tRNA genes. Though the directions are opposite, lots of likenesses emerge. First, mitochondrial gene transfer is pervasive in all 24 plants. Second, gene transfer is a single event of certain shared ancestors during evolutionary divergence. Third, sequence features of homologies vary for different purposes in the donor and recipient genomes. Finally, small repeats (or micro-homologies contribute to gene transfer by mediating recombination in the recipient genome.

  13. Horizontal gene transfer and the evolution of transcriptionalregulation in Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Price, Morgan N.; Dehal, Paramvir S.; Arkin, Adam P.

    2007-12-20

    Background: Most bacterial genes were acquired by horizontalgene transfer from other bacteria instead of being inherited bycontinuous vertical descent from an ancient ancestor}. To understand howthe regulation of these {acquired} genes evolved, we examined theevolutionary histories of transcription factors and of regulatoryinteractions from the model bacterium Escherichia coli K12. Results:Although most transcription factors have paralogs, these usually arose byhorizontal gene transfer rather than by duplication within the E. colilineage, as previously believed. In general, most neighbor regulators --regulators that are adjacent to genes that they regulate -- were acquiredby horizontal gene transfer, while most global regulators evolvedvertically within the gamma-Proteobacteria. Neighbor regulators wereoften acquired together with the adjacent operon that they regulate, sothe proximity might be maintained by repeated transfers (like "selfishoperons"). Many of the as-yet-uncharacterized (putative) regulators havealso been acquired together with adjacent genes, so we predict that theseare neighbor regulators as well. When we analyzed the histories ofregulatory interactions, we found that the evolution of regulation byduplication was rare, and surprisingly, many of the regulatoryinteractions that are shared between paralogs result from convergentevolution. Another surprise was that horizontally transferred genes aremore likely than other genes to be regulated by multiple regulators, andmost of this complex regulation probably evolved after the transfer.Conclusions: Our results highlight the rapid evolution of niche-specificgene regulation in bacteria.

  14. Leu452His mutation in lipoprotein lipase gene transfer associated with hypertriglyceridemia in mice in vivo.

    Directory of Open Access Journals (Sweden)

    Kaiyue Sun

    Full Text Available Mutated mouse lipoprotein lipase (LPL containing a leucine (L to histidine (H substitution at position 452 was transferred into mouse liver by hydrodynamics-based gene delivery (HD. Mutated-LPL (MLPL gene transfer significantly increased the concentrations of plasma MLPL and triglyceride (TG but significantly decreased the activity of plasma LPL. Moreover, the gene transfer caused adiposis hepatica and significantly increased TG content in mouse liver. To understand the effects of MLPL gene transfer on energy metabolism, we investigated the expression of key functional genes related to energy metabolism in the liver, epididymal fat, and leg muscles. The mRNA contents of hormone-sensitive lipase (HSL, adipose triglyceride lipase (ATGL, fatty acid-binding protein (FABP, and uncoupling protein (UCP were found to be significantly reduced. Furthermore, we investigated the mechanism by which MLPL gene transfer affected fat deposition in the liver, fat tissue, and muscle. The gene expression and protein levels of forkhead Box O3 (FOXO3, AMP-activated protein kinase (AMPK, and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α were found to be remarkably decreased in the liver, fat and muscle. These results suggest that the Leu452His mutation caused LPL dysfunction and gene transfer of MLPL in vivo produced resistance to the AMPK/PGC-1α signaling pathway in mice.

  15. Identification of a Novel Conjugative Plasmid in Mycobacteria That Requires Both Type IV and Type VII Secretion

    KAUST Repository

    Ummels, R.; Abdallah, A. M.; Kuiper, V.; Aajoud, A.; Sparrius, M.; Naeem, R.; Spaink, H. P.; van Soolingen, D.; Pain, Arnab; Bitter, W.

    2014-01-01

    Conjugative plasmids play an important role in horizontal gene transfer between different bacteria and, as such, in their adaptation and evolution. This effect is most obvious in the spread of antibiotic resistance genes. Thus far, conjugation of natural plasmids has been described only rarely for mycobacterial species. In fact, it is generally accepted that M. tuberculosis does not show any recent sign of horizontal gene transfer. In this study, we describe the identification of a new widespread conjugative plasmid that can also be efficiently transferred to M. tuberculosis. This plasmid therefore poses both a threat and an opportunity. The threat is that, through the acquisition of antibiotic resistance markers, this plasmid could start a rapid spread of antibiotic resistance genes between pathogenic mycobacteria. The opportunity is that we could use this plasmid to generate new tools for the efficient introduction of foreign DNA in slow-growing mycobacteria.

  16. Horizontal gene transfer of an entire metabolic pathway between a eukaryotic alga and its DNA virus

    Science.gov (United States)

    Monier, Adam; Pagarete, António; de Vargas, Colomban; Allen, Michael J.; Read, Betsy; Claverie, Jean-Michel; Ogata, Hiroyuki

    2009-01-01

    Interactions between viruses and phytoplankton, the main primary producers in the oceans, affect global biogeochemical cycles and climate. Recent studies are increasingly revealing possible cases of gene transfers between cyanobacteria and phages, which might have played significant roles in the evolution of cyanobacteria/phage systems. However, little has been documented about the occurrence of horizontal gene transfer in eukaryotic phytoplankton/virus systems. Here we report phylogenetic evidence for the transfer of seven genes involved in the sphingolipid biosynthesis pathway between the cosmopolitan eukaryotic microalga Emiliania huxleyi and its large DNA virus EhV. PCR assays indicate that these genes are prevalent in E. huxleyi and EhV strains isolated from different geographic locations. Patterns of protein and gene sequence conservation support that these genes are functional in both E. huxleyi and EhV. This is the first clear case of horizontal gene transfer of multiple functionally linked enzymes in a eukaryotic phytoplankton–virus system. We examine arguments for the possible direction of the gene transfer. The virus-to-host direction suggests the existence of ancient viruses that controlled the complex metabolic pathway in order to infect primitive eukaryotic cells. In contrast, the host-to-virus direction suggests that the serial acquisition of genes involved in the same metabolic pathway might have been a strategy for the ancestor of EhVs to stay ahead of their closest relatives in the great evolutionary race for survival. PMID:19451591

  17. A new computational method for the detection of horizontal gene transfer events.

    Science.gov (United States)

    Tsirigos, Aristotelis; Rigoutsos, Isidore

    2005-01-01

    In recent years, the increase in the amounts of available genomic data has made it easier to appreciate the extent by which organisms increase their genetic diversity through horizontally transferred genetic material. Such transfers have the potential to give rise to extremely dynamic genomes where a significant proportion of their coding DNA has been contributed by external sources. Because of the impact of these horizontal transfers on the ecological and pathogenic character of the recipient organisms, methods are continuously sought that are able to computationally determine which of the genes of a given genome are products of transfer events. In this paper, we introduce and discuss a novel computational method for identifying horizontal transfers that relies on a gene's nucleotide composition and obviates the need for knowledge of codon boundaries. In addition to being applicable to individual genes, the method can be easily extended to the case of clusters of horizontally transferred genes. With the help of an extensive and carefully designed set of experiments on 123 archaeal and bacterial genomes, we demonstrate that the new method exhibits significant improvement in sensitivity when compared to previously published approaches. In fact, it achieves an average relative improvement across genomes of between 11 and 41% compared to the Codon Adaptation Index method in distinguishing native from foreign genes. Our method's horizontal gene transfer predictions for 123 microbial genomes are available online at http://cbcsrv.watson.ibm.com/HGT/.

  18. Hyperbranched–dendrimer architectural copolymer gene delivery using hyperbranched PEI conjugated to poly(propyleneimine) dendrimers: synthesis, characterization, and evaluation of transfection efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Alavi, Seyyed Jamal [Ferdowsi University of Mashhad, Department of Chemistry, Faculty of Science (Iran, Islamic Republic of); Gholami, Leila [Mashhad University of Medical Sciences, Department of Modern Sciences and Technologies, School of Medicine (Iran, Islamic Republic of); Askarian, Saeedeh [Mashhad University of Medical Sciences, Department of Medical Biotechnology, School of Medicine (Iran, Islamic Republic of); Darroudi, Majid [Mashhad University of Medical Sciences, Nuclear Medicine Research Center (Iran, Islamic Republic of); Massoudi, Abdolhossein [University of Payam noor, Department of Chemistry (Iran, Islamic Republic of); Rezaee, Mehdi; Kazemi Oskuee, Reza, E-mail: Oskueekr@mums.ac.ir [Mashhad University of Medical Sciences, Department of Medical Biotechnology, School of Medicine (Iran, Islamic Republic of)

    2017-02-15

    The applications of dendrimer-based vectors seem to be promising in non-viral gene delivery because of their potential for addressing the problems with viral vectors. In this study, generation 3 poly(propyleneimine) (G3-PPI) dendrimers with 1, 4-diaminobutane as a core initiator was synthesized using a divergent growth approach. To increase the hydrophobicity and reduce toxicity, 10% of primary amines of G3-PPI dendrimers were replaced with bromoalkylcarboxylates with different chain lengths (6-bromohexanoic and 10-bromodecanoic). Then, to retain the overall buffering capacity and enhance transfection, the alkylcarboxylate–PPIs were conjugated to 10 kDa branched polyethylenimine (PEI). The results showed that the modified PPI was able to form complexes with the diameter of less than 60 nm with net-positive surface charge around 20 mV. No significant toxicity was observed in modified PPIs; however, the hexanoate conjugated PPI–PEI (PPI-HEX-10% PEI) and the decanoate conjugated PPI–PEI (PPI-DEC-10%-PEI) showed the best transfection efficiency in murine neuroblastoma (Neuro-2a) cell line, even PPI-HEX-10%-PEI showed transfection efficiency equal to standard PEI 25 kDa with reduced toxicity. This study suggested a new series of hyperbranched (PEI)–dendrimer (PPI) architectural copolymers as non-viral gene delivery vectors with high transfection efficiency and low toxicity.

  19. Hyperbranched-dendrimer architectural copolymer gene delivery using hyperbranched PEI conjugated to poly(propyleneimine) dendrimers: synthesis, characterization, and evaluation of transfection efficiency

    Science.gov (United States)

    Alavi, Seyyed Jamal; Gholami, Leila; Askarian, Saeedeh; Darroudi, Majid; Massoudi, Abdolhossein; Rezaee, Mehdi; Kazemi Oskuee, Reza

    2017-02-01

    The applications of dendrimer-based vectors seem to be promising in non-viral gene delivery because of their potential for addressing the problems with viral vectors. In this study, generation 3 poly(propyleneimine) (G3-PPI) dendrimers with 1, 4-diaminobutane as a core initiator was synthesized using a divergent growth approach. To increase the hydrophobicity and reduce toxicity, 10% of primary amines of G3-PPI dendrimers were replaced with bromoalkylcarboxylates with different chain lengths (6-bromohexanoic and 10-bromodecanoic). Then, to retain the overall buffering capacity and enhance transfection, the alkylcarboxylate-PPIs were conjugated to 10 kDa branched polyethylenimine (PEI). The results showed that the modified PPI was able to form complexes with the diameter of less than 60 nm with net-positive surface charge around 20 mV. No significant toxicity was observed in modified PPIs; however, the hexanoate conjugated PPI-PEI (PPI-HEX-10% PEI) and the decanoate conjugated PPI-PEI (PPI-DEC-10%-PEI) showed the best transfection efficiency in murine neuroblastoma (Neuro-2a) cell line, even PPI-HEX-10%-PEI showed transfection efficiency equal to standard PEI 25 kDa with reduced toxicity. This study suggested a new series of hyperbranched (PEI)-dendrimer (PPI) architectural copolymers as non-viral gene delivery vectors with high transfection efficiency and low toxicity.

  20. On the Complexity of Duplication-Transfer-Loss Reconciliation with Non-Binary Gene Trees.

    Science.gov (United States)

    Kordi, Misagh; Bansal, Mukul S

    2017-01-01

    Duplication-Transfer-Loss (DTL) reconciliation has emerged as a powerful technique for studying gene family evolution in the presence of horizontal gene transfer. DTL reconciliation takes as input a gene family phylogeny and the corresponding species phylogeny, and reconciles the two by postulating speciation, gene duplication, horizontal gene transfer, and gene loss events. Efficient algorithms exist for finding optimal DTL reconciliations when the gene tree is binary. However, gene trees are frequently non-binary. With such non-binary gene trees, the reconciliation problem seeks to find a binary resolution of the gene tree that minimizes the reconciliation cost. Given the prevalence of non-binary gene trees, many efficient algorithms have been developed for this problem in the context of the simpler Duplication-Loss (DL) reconciliation model. Yet, no efficient algorithms exist for DTL reconciliation with non-binary gene trees and the complexity of the problem remains unknown. In this work, we resolve this open question by showing that the problem is, in fact, NP-hard. Our reduction applies to both the dated and undated formulations of DTL reconciliation. By resolving this long-standing open problem, this work will spur the development of both exact and heuristic algorithms for this important problem.

  1. Alterations in radioresistance of eucaryotic cells after the transfer of genomic wildtype DNA and metallothionein genes

    International Nuclear Information System (INIS)

    Lohrer, H.

    1987-01-01

    The presented paper describes experiments concerning the alteration of radiosensitivity of eucaryotic cells after gene transfer. Ionizing radiation (γ- or X-ray) induces DNA single- or double strand breaks, which are religated by an unknown repair system. Repair deficient cells are highly sensitive to ionizing radiation. In the experiments described, cells from a patient with the heritable disease Ataxia telangiectasia were used as well as two X-ray sensitive CHO mutant cell lines. After gene transfer of an intact human DNA repair gene or a metallothionein gene the cells should regain radioresistance. (orig.) [de

  2. Herpes simplex virus type 1 (HSV-1)-derived recombinant vectors for gene transfer and gene therapy.

    Science.gov (United States)

    Marconi, Peggy; Fraefel, Cornel; Epstein, Alberto L

    2015-01-01

    Herpes simplex virus type 1 (HSV-1 ) is a human pathogen whose lifestyle is based on a long-term dual interaction with the infected host, being able to establish both lytic and latent infections. The virus genome is a 153-kilobase pair (kbp) double-stranded DNA molecule encoding more than 80 genes. The interest of HSV-1 as gene transfer vector stems from its ability to infect many different cell types, both quiescent and proliferating cells, the very high packaging capacity of the virus capsid, the outstanding neurotropic adaptations that this virus has evolved, and the fact that it never integrates into the cellular chromosomes, thus avoiding the risk of insertional mutagenesis. Two types of vectors can be derived from HSV-1, recombinant vectors and amplicon vectors, and different methodologies have been developed to prepare large stocks of each type of vector. This chapter summarizes the approach most commonly used to prepare recombinant HSV-1 vectors through homologous recombination, either in eukaryotic cells or in bacteria.

  3. Mortalin antibody-conjugated quantum dot transfer from human mesenchymal stromal cells to breast cancer cells requires cell–cell interaction

    Energy Technology Data Exchange (ETDEWEB)

    Pietilä, Mika [National Institute of Advanced industrial Sciences and Technology, Tsukuba, Ibaraki 305 8562 (Japan); Lehenkari, Petri [Institute of Biomedicine, Department of Anatomy and Cell Biology, University of Oulu, Aapistie 7, P.O. Box 5000, FIN-90014 (Finland); Institute of Clinical Medicine, Division of Surgery, University of Oulu and Clinical Research Centre, Department of Surgery and Intensive Care, Oulu University Hospital, Aapistie 5a, P.O. Box 5000, FIN-90014 (Finland); Kuvaja, Paula [Institute of Biomedicine, Department of Anatomy and Cell Biology, University of Oulu, Aapistie 7, P.O. Box 5000, FIN-90014 (Finland); Department of Pathology, Oulu University Hospital, P.O. Box 50, FIN-90029 OYS, Oulu (Finland); Kaakinen, Mika [Biocenter Oulu, University of Oulu, P.O. Box 5000, FI-90014 (Finland); Kaul, Sunil C.; Wadhwa, Renu [National Institute of Advanced industrial Sciences and Technology, Tsukuba, Ibaraki 305 8562 (Japan); Uemura, Toshimasa, E-mail: t.uemura@aist.go.jp [National Institute of Advanced industrial Sciences and Technology, Tsukuba, Ibaraki 305 8562 (Japan)

    2013-11-01

    The role of tumor stroma in regulation of breast cancer growth has been widely studied. However, the details on the type of heterocellular cross-talk between stromal and breast cancer cells (BCCs) are still poorly known. In the present study, in order to investigate the intercellular communication between human mesenchymal stromal cells (hMSCs) and breast cancer cells (BCCs, MDA-MB-231), we recruited cell-internalizing quantum dots (i-QD) generated by conjugation of cell-internalizing anti-mortalin antibody and quantum dots (QD). Co-culture of illuminated and color-coded hMSCs (QD655) and BCCs (QD585) revealed the intercellular transfer of QD655 signal from hMSCs to BCCs. The amount of QD double positive BCCs increased gradually within 48 h of co-culture. We found prominent intercellular transfer of QD655 in hanging drop co-culture system and it was non-existent when hMSCs and BBCs cells were co-cultured in trans-well system lacking imminent cell–cell contact. Fluorescent and electron microscope analyses also supported that the direct cell-to-cell interactions may be required for the intercellular transfer of QD655 from hMSCs to BCCs. To the best of our knowledge, the study provides a first demonstration of transcellular crosstalk between stromal cells and BCCs that involve direct contact and may also include a transfer of mortalin, an anti-apoptotic and growth-promoting factor enriched in cancer cells.

  4. Incorporation of a horizontally transferred gene into an operon during cnidarian evolution.

    Directory of Open Access Journals (Sweden)

    Catherine E Dana

    Full Text Available Genome sequencing has revealed examples of horizontally transferred genes, but we still know little about how such genes are incorporated into their host genomes. We have previously reported the identification of a gene (flp that appears to have entered the Hydra genome through horizontal transfer. Here we provide additional evidence in support of our original hypothesis that the transfer was from a unicellular organism, and we show that the transfer occurred in an ancestor of two medusozoan cnidarian species. In addition we show that the gene is part of a bicistronic operon in the Hydra genome. These findings identify a new animal phylum in which trans-spliced leader addition has led to the formation of operons, and define the requirements for evolution of an operon in Hydra. The identification of operons in Hydra also provides a tool that can be exploited in the construction of transgenic Hydra strains.

  5. Modifier Genes for Mouse Phosphatidylinositol Transfer Protein alpha (vibrator) That Bypass Juvenile Lethality

    NARCIS (Netherlands)

    Concepcion, Dorothy; Johannes, Frank; Lo, Yuan Hung; Yao, Jay; Fong, Jerry; Hamilton, Bruce A.

    Phosphatidylinositol transfer proteins (PITPs) mediate lipid signaling and membrane trafficking in eukaryotic cells. Loss-of-function mutations of the gene encoding PITP alpha in mice result in a range of dosage-sensitive phenotypes, including neurological dysfunction, neurodegeneration, and

  6. Effective generation of transgenic pigs and mice by linker based sperm-mediated gene transfer.

    OpenAIRE

    Chang, Keejong; Qian, Jin; Jiang, MeiSheng; Liu, Yi-Hsin; Wu, Ming-Che; Chen, Chi-Dar; Lai, Chao-Kuen; Lo, Hsin-Lung; Hsiao, Chin-Ton; Brown, Lucy; Bolen, James; Huang, Hsiao-I; Ho, Pei-Yu; Shih, Ping Yao; Yao, Chen-Wen

    2002-01-01

    Abstract Background Transgenic animals have become valuable tools for both research and applied purposes. The current method of gene transfer, microinjection, which is widely used in transgenic mouse production, has only had limited success in producing transgenic animals of larger or higher species. Here, we report a linker based sperm-mediated gene transfer method (LB-SMGT) that greatly improves the production efficiency of large transgenic animals. Results The linker protein, a monoclonal ...

  7. Optimization of cationic lipid mediated gene transfer: structure-function, physico-chemical, and cellular studies.

    Science.gov (United States)

    Carrière, Marie; Tranchant, Isabelle; Niore, Pierre-Antoine; Byk, Gerardo; Mignet, Nathalie; Escriou, Virginie; Scherman, Daniel; Herscovici, Jean

    2002-01-01

    The rationale design aimed at the enhancement of cationic lipid mediated gene transfer is discussed. These improvements are based on the straight evaluation of the structure-activity relationship and on the introduction of new structures. Much attention have been given to the supramolecular structures of the lipid/DNA complexes, to the effect of serum on gene transfer and to the intracellular trafficking of the lipoplexes. Finally new avenue using reducible cationic lipids has been discussed.

  8. Evolutionary change and phylogenetic relationships in light of horizontal gene transfer.

    Science.gov (United States)

    Boto, Luis

    2015-06-01

    Horizontal gene transfer has, over the past 25 years, become a part of evolutionary thinking. In the present paper I discuss horizontal gene transfer (HGT) in relation to contingency, natural selection, evolutionary change speed and the Tree-of-Life endeavour, with the aim of contributing to the understanding of the role of HGT in evolutionary processes. In addition, the challenges that HGT imposes on the current view of evolution are emphasized.

  9. Mobility of the native Bacillus subtilis conjugative plasmid pLS20 is regulated by intercellular signaling.

    Science.gov (United States)

    Singh, Praveen K; Ramachandran, Gayetri; Ramos-Ruiz, Ricardo; Peiró-Pastor, Ramón; Abia, David; Wu, Ling J; Meijer, Wilfried J J

    2013-10-01

    Horizontal gene transfer mediated by plasmid conjugation plays a significant role in the evolution of bacterial species, as well as in the dissemination of antibiotic resistance and pathogenicity determinants. Characterization of their regulation is important for gaining insights into these features. Relatively little is known about how conjugation of Gram-positive plasmids is regulated. We have characterized conjugation of the native Bacillus subtilis plasmid pLS20. Contrary to the enterococcal plasmids, conjugation of pLS20 is not activated by recipient-produced pheromones but by pLS20-encoded proteins that regulate expression of the conjugation genes. We show that conjugation is kept in the default "OFF" state and identified the master repressor responsible for this. Activation of the conjugation genes requires relief of repression, which is mediated by an anti-repressor that belongs to the Rap family of proteins. Using both RNA sequencing methodology and genetic approaches, we have determined the regulatory effects of the repressor and anti-repressor on expression of the pLS20 genes. We also show that the activity of the anti-repressor is in turn regulated by an intercellular signaling peptide. Ultimately, this peptide dictates the timing of conjugation. The implications of this regulatory mechanism and comparison with other mobile systems are discussed.

  10. Lateral gene transfer between prokaryotes and multicellular eukaryotes: ongoing and significant?

    NARCIS (Netherlands)

    Ros, V.I.D.; Hurst, G.D.D.

    2009-01-01

    The expansion of genome sequencing projects has produced accumulating evidence for lateral transfer of genes between prokaryotic and eukaryotic genomes. However, it remains controversial whether these genes are of functional importance in their recipient host. Nikoh and Nakabachi, in a recent paper

  11. Gene loss and horizontal gene transfer contributed to the genome evolution of the extreme acidophile Ferrovum

    Directory of Open Access Journals (Sweden)

    Sophie Roxana Ullrich

    2016-05-01

    Full Text Available Acid mine drainage (AMD, associated with active and abandoned mining sites, is a habitat for acidophilic microorganisms that gain energy from the oxidation of reduced sulfur compounds and ferrous iron and that thrive at pH below 4. Members of the recently proposed genus Ferrovum are the first acidophilic iron oxidizers to be described within the Betaproteobacteria. Although they have been detected as typical community members in AMD habitats worldwide, knowledge of their phylogenetic and metabolic diversity is scarce. Genomics approaches appear to be most promising in addressing this lacuna since isolation and cultivation of Ferrovum has proven to be extremely difficult and has so far only been successful for the designated type strain Ferrovum myxofaciens P3G. In this study, the genomes of two novel strains of Ferrovum (PN-J185 and Z-31 derived from water samples of a mine water treatment plant were sequenced. These genomes were compared with those of Ferrovum sp. JA12 that also originated from the mine water treatment plant, and of the type strain (P3G. Phylogenomic scrutiny suggests that the four strains represent three Ferrovum species that cluster in two groups (1 and 2. Comprehensive analysis of their predicted metabolic pathways revealed that these groups harbor characteristic metabolic profiles, notably with respect to motility, chemotaxis, nitrogen metabolism, biofilm formation and their potential strategies to cope with the acidic environment. For example, while the F. myxofaciens strains (group 1 appear to be motile and diazotrophic, the non-motile group 2 strains have the predicted potential to use a greater variety of fixed nitrogen sources. Furthermore, analysis of their genome synteny provides first insights into their genome evolution, suggesting that horizontal gene transfer and genome reduction in the group 2 strains by loss of genes encoding complete metabolic pathways or physiological features contributed to the observed

  12. The standard lateral gene transfer model is statistically consistent for pectinate four-taxon trees

    DEFF Research Database (Denmark)

    Sand, Andreas; Steel, Mike

    2013-01-01

    Evolutionary events such as incomplete lineage sorting and lateral gene transfers constitute major problems for inferring species trees from gene trees, as they can sometimes lead to gene trees which conflict with the underlying species tree. One particularly simple and efficient way to infer...... species trees from gene trees under such conditions is to combine three-taxon analyses for several genes using a majority vote approach. For incomplete lineage sorting this method is known to be statistically consistent; however, for lateral gene transfers it was recently shown that a zone...... of inconsistency exists for a specific four-taxon tree topology, and it was posed as an open question whether inconsistencies could exist for other four-taxon tree topologies? In this letter we analyze all remaining four-taxon topologies and show that no other inconsistencies exist....

  13. Sustainability of keratinocyte gene transfer and cell survival in vivo.

    Science.gov (United States)

    Choate, K A; Khavari, P A

    1997-05-20

    The epidermis is an attractive site for therapeutic gene delivery because it is accessible and capable of delivering polypeptides to the systemic circulation. A number of difficulties, however, have emerged in attempts at cutaneous gene delivery, and central among these is an inability to sustain therapeutic gene production. We have examined two major potential contributing factors, viral vector stamina and involvement of long-lived epidermal progenitor cells. Human keratinocytes were either untreated or transduced with a retroviral vector for beta-galactosidase (beta-Gal) at > 99% efficiency and then grafted onto immunodeficient mice to regenerate human epidermis. Human epidermis was monitored in vivo after grafting for clinical and histologic appearance as well as for gene expression. Although integrated vector sequences persisted unchanged in engineered epidermis at 10 weeks post-grafting, retroviral long terminal repeat (LTR)-driven beta-Gal expression ceased in vivo after approximately 4 weeks. Endogenous cellular promoters, however, maintained consistently normal gene expression levels without evidence of time-dependent decline, as determined by immunostaining with species-specific antibodies for human involucrin, filaggrin, keratinocyte transglutaminase, keratin 10, type VII collagen, and Laminin 5 proteins out to week 14 post-grafting. Transduced human keratinocytes generated multilayer epidermis sustained through multiple epidermal turnover cycles; this epidermis demonstrated retention of a spatially appropriate pattern of basal and suprabasal epidermal marker gene expression. These results confirm previous findings suggesting that viral promoter-driven gene expression is not durable and demonstrate that keratinocytes passaged in vitro can regenerate and sustain normal epidermis for prolonged periods.

  14. Cellular automata-based artificial life system of horizontal gene transfer

    Directory of Open Access Journals (Sweden)

    Ji-xin Liu

    2016-02-01

    Full Text Available Mutation and natural selection is the core of Darwin's idea about evolution. Many algorithms and models are based on this idea. However, in the evolution of prokaryotes, more and more researches have indicated that horizontal gene transfer (HGT would be much more important and universal than the authors had imagined. Owing to this mechanism, the prokaryotes not only become adaptable in nearly any environment on Earth, but also form a global genetic bank and a super communication network with all the genes of the prokaryotic world. Under this background, they present a novel cellular automata model general gene transfer to simulate and study the vertical gene transfer and HGT in the prokaryotes. At the same time, they use Schrodinger's life theory to formulate some evaluation indices and to discuss the intelligence and cognition of prokaryotes which is derived from HGT.

  15. The Agricultural Antibiotic Carbadox Induces Phage-mediated Gene Transfer in Salmonella

    Directory of Open Access Journals (Sweden)

    Bradley L. Bearson

    2014-02-01

    Full Text Available Antibiotics are used for disease therapeutic or preventative effects in humans and animals, as well as for enhanced feed conversion efficiency in livestock. Antibiotics can also cause undesirable effects in microbial populations, including selection for antibiotic resistance, enhanced pathogen invasion, and stimulation of horizontal gene transfer. Carbadox is a veterinary antibiotic used in the U.S. during the starter phase of swine production for improved feed efficiency and control of swine dysentery and bacterial swine enteritis. Carbadox has been shown in vitro to induce phage-encoded Shiga toxin in Shiga toxin-producing Escherichia coli and a phage-like element transferring antibiotic resistance genes in Brachyspira hyodysenteriae, but the effect of carbadox on prophages in other bacteria is unknown. This study examined carbadox exposure on prophage induction and genetic transfer in Salmonella enterica serovar Typhimurium, a human foodborne pathogen that frequently colonizes swine without causing disease. S. Typhimurium LT2 exposed to carbadox induced prophage production, resulting in bacterial cell lysis and release of virions that were visible by electron microscopy. Carbadox induction of phage-mediated gene transfer was confirmed by monitoring the transduction of a sodCIII::neo cassette in the Fels-1 prophage from LT2 to a recipient Salmonella strain. Furthermore, carbadox frequently induced generalized transducing phages in multidrug-resistant phage type DT104 and DT120 isolates, resulting in the transfer of chromosomal and plasmid DNA that included antibiotic resistance genes. Our research indicates that exposure of Salmonella to carbadox induces prophages that can transfer virulence and antibiotic resistance genes to susceptible bacterial hosts. Carbadox-induced, phage-mediated gene transfer could serve as a contributing factor in bacterial evolution during animal production, with prophages being a reservoir for bacterial fitness

  16. Two Horizontally Transferred Xenobiotic Resistance Gene Clusters Associated with Detoxification of Benzoxazolinones by Fusarium Species

    Science.gov (United States)

    Glenn, Anthony E.; Davis, C. Britton; Gao, Minglu; Gold, Scott E.; Mitchell, Trevor R.; Proctor, Robert H.; Stewart, Jane E.; Snook, Maurice E.

    2016-01-01

    Microbes encounter a broad spectrum of antimicrobial compounds in their environments and often possess metabolic strategies to detoxify such xenobiotics. We have previously shown that Fusarium verticillioides, a fungal pathogen of maize known for its production of fumonisin mycotoxins, possesses two unlinked loci, FDB1 and FDB2, necessary for detoxification of antimicrobial compounds produced by maize, including the γ-lactam 2-benzoxazolinone (BOA). In support of these earlier studies, microarray analysis of F. verticillioides exposed to BOA identified the induction of multiple genes at FDB1 and FDB2, indicating the loci consist of gene clusters. One of the FDB1 cluster genes encoded a protein having domain homology to the metallo-β-lactamase (MBL) superfamily. Deletion of this gene (MBL1) rendered F. verticillioides incapable of metabolizing BOA and thus unable to grow on BOA-amended media. Deletion of other FDB1 cluster genes, in particular AMD1 and DLH1, did not affect BOA degradation. Phylogenetic analyses and topology testing of the FDB1 and FDB2 cluster genes suggested two horizontal transfer events among fungi, one being transfer of FDB1 from Fusarium to Colletotrichum, and the second being transfer of the FDB2 cluster from Fusarium to Aspergillus. Together, the results suggest that plant-derived xenobiotics have exerted evolutionary pressure on these fungi, leading to horizontal transfer of genes that enhance fitness or virulence. PMID:26808652

  17. Modeling 3D conjugate heat and mass transfer for turbulent air drying of Chilean papaya in a direct contact dryer

    Science.gov (United States)

    Lemus-Mondaca, Roberto A.; Vega-Gálvez, Antonio; Zambra, Carlos E.; Moraga, Nelson O.

    2017-01-01

    A 3D model considering heat and mass transfer for food dehydration inside a direct contact dryer is studied. The k- ɛ model is used to describe turbulent air flow. The samples thermophysical properties as density, specific heat, and thermal conductivity are assumed to vary non-linearly with temperature. FVM, SIMPLE algorithm based on a FORTRAN code are used. Results unsteady velocity, temperature, moisture, kinetic energy and dissipation rate for the air flow are presented, whilst temperature and moisture values for the food also are presented. The validation procedure includes a comparison with experimental and numerical temperature and moisture content results obtained from experimental data, reaching a deviation 7-10 %. In addition, this turbulent k- ɛ model provided a better understanding of the transport phenomenon inside the dryer and sample.

  18. An adaptive simplex cut-cell method for high-order discontinuous Galerkin discretizations of elliptic interface problems and conjugate heat transfer problems

    Science.gov (United States)

    Sun, Huafei; Darmofal, David L.

    2014-12-01

    In this paper we propose a new high-order solution framework for interface problems on non-interface-conforming meshes. The framework consists of a discontinuous Galerkin (DG) discretization, a simplex cut-cell technique, and an output-based adaptive scheme. We first present a DG discretization with a dual-consistent output evaluation for elliptic interface problems on interface-conforming meshes, and then extend the method to handle multi-physics interface problems, in particular conjugate heat transfer (CHT) problems. The method is then applied to non-interface-conforming meshes using a cut-cell technique, where the interface definition is completely separate from the mesh generation process. No assumption is made on the interface shape (other than Lipschitz continuity). We then equip our strategy with an output-based adaptive scheme for an accurate output prediction. Through numerical examples, we demonstrate high-order convergence for elliptic interface problems and CHT problems with both smooth and non-smooth interface shapes.

  19. Follistatin allows efficient retroviral-mediated gene transfer into rat liver

    International Nuclear Information System (INIS)

    Borgnon, Josephine; Djamouri, Fatima; Lorand, Isabelle; Rico, Virginie Di; Loux, Nathalie; Pages, Jean-Christophe; Franco, Dominique; Capron, Frederique; Weber, Anne

    2005-01-01

    Retroviral vectors are widely used tools for gene therapy. However, in vivo gene transfer is only effective in dividing cells, which, in liver, requires a regenerative stimulus. Follistatin is effective in promoting liver regeneration after 90% and 70% hepatectomy in rats. We studied its efficacy on liver regeneration and retroviral-mediated gene delivery in 50% hepatectomized rats. When human recombinant follistatin was infused into the portal vein immediately after 50% hepatectomy, hepatocyte proliferation was significantly higher than in control 50% hepatectomized rats. A single injection of virus particles administered 23 h after follistatin infusion resulted in more than 20% gene transduction efficiency in hepatocytes compared to 3% in control rats. It is concluded that a single injection of follistatin induces onset of proliferation in 50% hepatectomized rats and allows efficient retroviral-mediated gene transfer to the liver

  20. Ex-Vivo Gene Therapy Using Lentiviral Mediated Gene Transfer Into Umbilical Cord Blood Derived Stem Cells

    Directory of Open Access Journals (Sweden)

    Hanieh Jalali

    2016-02-01

    Full Text Available Background Introduction of therapeutic genes into the injured site of nervous system can be achieved using transplantation of cellular vehicles containing desired gene. To transfer exogenous genes into the cellular vehicles, lentiviral vectors are one of interested vectors because of advantages such high transduction efficiency of dividing and non-dividing cells. Unrestricted somatic stem cells are subclasses of umbilical cord blood derived stem cells which are appreciate candidates to use as cellular vehicles for ex vivo gene therapy of nervous system. Objectives In current study we investigated the effect of lentiviral vector transduction on the neuronal related features of unrestricted somatic stem cells to indicate the probable and unwanted changes related to transduction procedure. Materials and Methods In this experimental study, lentiviral vector containing green fluorescent protein (GFP were transduced into unrestricted somatic stem cells and its effect was investigated with using MTT assay, qPCR and immunohistochemistry techniques. For statistical comparison of real time PCR results, REST software (2009, Qiagen was used. Results Obtained results showed lentiviral vector transduction did not have cytotoxic effects on unrestricted somatic stem cells and did not change neuronal differentiation capacity of them as well the expression of some neuronal related genes and preserved them in multilineage situation. Conclusions In conclusion, we suggested that lentiviral vectors could be proper vectors to transfer therapeutic gene into unrestricted somatic stem cells to provide a cellular vehicle for ex vivo gene therapy of nervous system disorders.

  1. Innate Functions of Immunoglobulin M Lessen Liver Gene Transfer with Helper-Dependent Adenovirus

    Science.gov (United States)

    Unzu, Carmen; Morales-Kastresana, Aizea; Sampedro, Ana; Serrano-Mendioroz, Irantzu; Azpilikueta, Arantza; Ochoa, María Carmen; Dubrot, Juan; Martínez-Ansó, Eduardo

    2014-01-01

    The immune system poses obstacles to viral vectors, even in the first administration to preimmunized hosts. We have observed that the livers of B cell-deficient mice were more effectively transduced by a helper-dependent adenovirus serotype-5 (HDA) vector than those of WT mice. This effect was T-cell independent as shown in athymic mice. Passive transfer of the serum from adenovirus-naïve WT to Rag1KO mice resulted in a reduction in gene transfer that was traced to IgM purified from serum of adenovirus-naïve mice. To ascribe the gene transfer inhibition activity to either adenoviral antigen-specific or antigen-unspecific functions of IgM, we used a monoclonal IgM antibody of unrelated specificity. Both the polyclonal and the irrelevant monoclonal IgM inhibited gene transfer by the HDA vector to either cultured hepatocellular carcinoma cells or to the liver of mice in vivo. Adsorption of polyclonal or monoclonal IgMs to viral capsids was revealed by ELISAs on adenovirus-coated plates. These observations indicate the existence of an inborn IgM mechanism deployed against a prevalent virus to reduce early post-infection viremia. In conclusion, innate IgM binding to adenovirus serotype-5 capsids restrains gene-transfer and offers a mechanism to be targeted for optimization of vector dosage in gene therapy with HDA vectors. PMID:24465560

  2. Innate functions of immunoglobulin M lessen liver gene transfer with helper-dependent adenovirus.

    Directory of Open Access Journals (Sweden)

    Carmen Unzu

    Full Text Available The immune system poses obstacles to viral vectors, even in the first administration to preimmunized hosts. We have observed that the livers of B cell-deficient mice were more effectively transduced by a helper-dependent adenovirus serotype-5 (HDA vector than those of WT mice. This effect was T-cell independent as shown in athymic mice. Passive transfer of the serum from adenovirus-naïve WT to Rag1KO mice resulted in a reduction in gene transfer that was traced to IgM purified from serum of adenovirus-naïve mice. To ascribe the gene transfer inhibition activity to either adenoviral antigen-specific or antigen-unspecific functions of IgM, we used a monoclonal IgM antibody of unrelated specificity. Both the polyclonal and the irrelevant monoclonal IgM inhibited gene transfer by the HDA vector to either cultured hepatocellular carcinoma cells or to the liver of mice in vivo. Adsorption of polyclonal or monoclonal IgMs to viral capsids was revealed by ELISAs on adenovirus-coated plates. These observations indicate the existence of an inborn IgM mechanism deployed against a prevalent virus to reduce early post-infection viremia. In conclusion, innate IgM binding to adenovirus serotype-5 capsids restrains gene-transfer and offers a mechanism to be targeted for optimization of vector dosage in gene therapy with HDA vectors.

  3. A reconstruction problem for a class of phylogenetic networks with lateral gene transfers.

    Science.gov (United States)

    Cardona, Gabriel; Pons, Joan Carles; Rosselló, Francesc

    2015-01-01

    Lateral, or Horizontal, Gene Transfers are a type of asymmetric evolutionary events where genetic material is transferred from one species to another. In this paper we consider LGT networks, a general model of phylogenetic networks with lateral gene transfers which consist, roughly, of a principal rooted tree with its leaves labelled on a set of taxa, and a set of extra secondary arcs between nodes in this tree representing lateral gene transfers. An LGT network gives rise in a natural way to a principal phylogenetic subtree and a set of secondary phylogenetic subtrees, which, roughly, represent, respectively, the main line of evolution of most genes and the secondary lines of evolution through lateral gene transfers. We introduce a set of simple conditions on an LGT network that guarantee that its principal and secondary phylogenetic subtrees are pairwise different and that these subtrees determine, up to isomorphism, the LGT network. We then give an algorithm that, given a set of pairwise different phylogenetic trees [Formula: see text] on the same set of taxa, outputs, when it exists, the LGT network that satisfies these conditions and such that its principal phylogenetic tree is [Formula: see text] and its secondary phylogenetic trees are [Formula: see text].

  4. Exploration of new perspectives and limitations in Agrobacterium mediated gene transfer technology. Progress report, [June 1, 1992-- May 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Marton, L.

    1994-12-31

    This report describes progress aimed at constructing gene-transfer technology for Nicotiana plumbaginifolia. Most actual effort as described herein has so far been directed at exploring new perspectives and limitations in Agrobacterium mediated gene transfer. Accomplishments are described using a core homologous gene targeting vector.

  5. Ancient horizontal gene transfer from bacteria enhances biosynthetic capabilities of fungi.

    Directory of Open Access Journals (Sweden)

    Imke Schmitt

    Full Text Available Polyketides are natural products with a wide range of biological functions and pharmaceutical applications. Discovery and utilization of polyketides can be facilitated by understanding the evolutionary processes that gave rise to the biosynthetic machinery and the natural product potential of extant organisms. Gene duplication and subfunctionalization, as well as horizontal gene transfer are proposed mechanisms in the evolution of biosynthetic gene clusters. To explain the amount of homology in some polyketide synthases in unrelated organisms such as bacteria and fungi, interkingdom horizontal gene transfer has been evoked as the most likely evolutionary scenario. However, the origin of the genes and the direction of the transfer remained elusive.We used comparative phylogenetics to infer the ancestor of a group of polyketide synthase genes involved in antibiotic and mycotoxin production. We aligned keto synthase domain sequences of all available fungal 6-methylsalicylic acid (6-MSA-type PKSs and their closest bacterial relatives. To assess the role of symbiotic fungi in the evolution of this gene we generated 24 6-MSA synthase sequence tags from lichen-forming fungi. Our results support an ancient horizontal gene transfer event from an actinobacterial source into ascomycete fungi, followed by gene duplication.Given that actinobacteria are unrivaled producers of biologically active compounds, such as antibiotics, it appears particularly promising to study biosynthetic genes of actinobacterial origin in fungi. The large number of 6-MSA-type PKS sequences found in lichen-forming fungi leads us hypothesize that the evolution of typical lichen compounds, such as orsellinic acid derivatives, was facilitated by the gain of this bacterial polyketide synthase.

  6. What tangled web: barriers to rampant horizontal gene transfer

    OpenAIRE

    Kurland, Charles

    2005-01-01

    Dawkins in his The Selfish Gene(1) quite aptly applies the term "selfish" to parasitic repetitive DNA sequences endemic to eukaryotic genomes, especially vertebrates. Doolittle and Sapienza (2) as well as Orgel and Crick (3) enlivened this notion of selfish DNA with the identification of such repetitive sequences as remnants of mobile elements such as transposons. In addition, Orgel and Crick (3) associated parasitic DNA with a potential to outgrow their host genomes by propagating ...

  7. Gene transfer into subcultured endometrial cells using lipofection.

    Science.gov (United States)

    Lascombe, I; Mougin, P; Vuillermoz, C; Adessi, G L; Jouvenot, M

    1996-01-01

    Lipofection using the Lipofectin reagent was optimized to transiently transfect subcultured guinea pig endometrial stromal cells with a beta-galactosidase gene driven by a simian virus 40 promoter. Efficient transfection was obtained in the following conditions: a value of six for the ratio of lipofectin to DNA, a low cellular density (10(5) cells per 35-mm well) at the time of subculture (48 h before lipofection) and a lipofection duration of 12 hours. Lipofection was compared to calcium phosphate precipitation previously optimized in the same culture model. At a low cellular density, the lipofection method was found to be more efficient than the calcium phosphate precipitation. This result gives a great relevance to lipofection since the cultured cells available in an experiment are often limited. Then, using cells at low density and a plasmid containing the chloramphenicol acetyltransferase (cat) gene linked to an estrogen response element, it was shown that the lipofection procedure is a suitable tool for the evaluation of gene regulation by estrogen.

  8. Highly efficient retrograde gene transfer into motor neurons by a lentiviral vector pseudotyped with fusion glycoprotein.

    Directory of Open Access Journals (Sweden)

    Miyabi Hirano

    Full Text Available The development of gene therapy techniques to introduce transgenes that promote neuronal survival and protection provides effective therapeutic approaches for neurological and neurodegenerative diseases. Intramuscular injection of adenoviral and adeno-associated viral vectors, as well as lentiviral vectors pseudotyped with rabies virus glycoprotein (RV-G, permits gene delivery into motor neurons in animal models for motor neuron diseases. Recently, we developed a vector with highly efficient retrograde gene transfer (HiRet by pseudotyping a human immunodeficiency virus type 1 (HIV-1-based vector with fusion glycoprotein B type (FuG-B or a variant of FuG-B (FuG-B2, in which the cytoplasmic domain of RV-G was replaced by the corresponding part of vesicular stomatitis virus glycoprotein (VSV-G. We have also developed another vector showing neuron-specific retrograde gene transfer (NeuRet with fusion glycoprotein C type, in which the short C-terminal segment of the extracellular domain and transmembrane/cytoplasmic domains of RV-G was substituted with the corresponding regions of VSV-G. These two vectors afford the high efficiency of retrograde gene transfer into different neuronal populations in the brain. Here we investigated the efficiency of the HiRet (with FuG-B2 and NeuRet vectors for retrograde gene transfer into motor neurons in the spinal cord and hindbrain in mice after intramuscular injection and compared it with the efficiency of the RV-G pseudotype of the HIV-1-based vector. The main highlight of our results is that the HiRet vector shows the most efficient retrograde gene transfer into both spinal cord and hindbrain motor neurons, offering its promising use as a gene therapeutic approach for the treatment of motor neuron diseases.

  9. Indication of Horizontal DNA Gene Transfer by Extracellular Vesicles.

    Directory of Open Access Journals (Sweden)

    Stefanie Fischer

    Full Text Available The biological relevance of extracellular vesicles (EV in intercellular communication has been well established. Thus far, proteins and RNA were described as main cargo. Here, we show that EV released from human bone marrow derived mesenchymal stromal cells (BM-hMSC also carry high-molecular DNA in addition. Extensive EV characterization revealed this DNA mainly associated with the outer EV membrane and to a smaller degree also inside the EV. Our EV purification protocol secured that DNA is not derived from apoptotic or necrotic cells. To analyze the relevance of EV-associated DNA we lentivirally transduced Arabidopsis thaliana-DNA (A.t.-DNA as indicator into BM-hMSC and generated EV. Using quantitative polymerase chain reaction (qPCR techniques we detected high copy numbers of A.t.-DNA in EV. In recipient hMSC incubated with tagged EV for two weeks we identified A.t.-DNA transferred to recipient cells. Investigation of recipient cell DNA using quantitative PCR and verification of PCR-products by sequencing suggested stable integration of A.t.-DNA. In conclusion, for the first time our proof-of-principle experiments point to horizontal DNA transfer into recipient cells via EV. Based on our results we assume that eukaryotic cells are able to exchange genetic information in form of DNA extending the known cargo of EV by genomic DNA. This mechanism might be of relevance in cancer but also during cell evolution and development.

  10. Efficient gene transfer into silkworm larval tissues by a combination of sonoporation and lipofection.

    Science.gov (United States)

    Lee, Jae Man; Takahashi, Masateru; Mon, Hiroaki; Koga, Katsumi; Kawaguchi, Yutaka; Kusakabe, Takahiro

    2005-11-01

    Sonoporation (ultrasound treatment) provides a new and attractive nonviral way of in vivo gene transfer. To access the applicability of this method to the silkworm, Bombyx mori, we have compared the efficiencies of gene transfer by means of lipofection (using an appropriate agent, PDD111), sonoporation (ditto, FluoroGene), and lipofection followed by sonoporation. By these methods, a luciferase expression plasmid was found to be markedly transferred into the haemocoel of newly ecdysed fifth instar silkworm larvae, and also into other tissues although with lower rates compared with the haemocoel. In terms of luciferase activity, the efficiencies of transgene by lipofection plus sonoporation were approximately 6 (hemocytes), 20 (silk glands), 8 (mid-gut), 38 (fat body), 10 (Malpighian tubules), 33 (ovaries), and 16 (testes) times as high as those by lipofection or sonoporation alone. These results demonstrated that the present method is useful to introduce the exogenous DNA into insect organs in vivo.

  11. Use of γ-irradiated pollen for the gene transfer in Petunia

    International Nuclear Information System (INIS)

    Andrejchenko, S.V.; Grodzinskij, D.M.

    1986-01-01

    Possibility of using gamma-irradiated pollen for the gene transfer in Petunia is shown. Occurrence of gametic transformation provided not only the gene integration and expression but also their transfer to the daughter generations. The described methodical approach to construction of the plant eucariotic cell genome is based not only on its simplicity but also on the fact that gamma-radiation doses of 1000 Gy and higher have no desorganizing effect on the chromatine structure in such a degree that its transcription activity is completely lost. Besides, selective inactivation of the locus radiation in the pollen genome is much assisted by their different radioresistance. Though the gene transfer by gametic transformation is mostly irregular but its probability may be increased by the correct selection of the pollen irradiation dose in a range in which the growth of pollen tube before ovary is conserved and reparation of one-strand and two-strand DNA breaks preventing chromatine fragmentation is suppressed

  12. Ectopic expression of ubiquitin-conjugating enzyme gene from wild rice, OgUBC1, confers resistance against UV-B radiation and Botrytis infection in Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Jeon, En Hee; Pak, Jung Hun; Kim, Mi Jin; Kim, Hye Jeong; Shin, Sang Hyun; Lee, Jai Heon; Kim, Doh Hoon; Oh, Ju Sung; Oh, Boung-Jun; Jung, Ho Won; Chung, Young Soo

    2012-01-01

    Highlights: ► We isolated a novel E2 ubiquitin-conjugating enzyme from leaves of wild rice plants. ► The OgUBC1 was highly expressed in leaves treated with SA and UV-B radiation. ► The recombinant OgUBC1 has an enzymatic activity of E2 in vitro. ► The OgUBC1 could protect disruption of plant cells by UV-B radiation. ► OgUBC1 confers disease resistance and UV-B tolerance in transgenic Arabidopsis plants. -- Abstract: A previously unidentified gene encoding ubiquitin-conjugating enzyme was isolated from leaves of wild rice plant treated with wounding and microbe-associated molecular patterns. The OgUBC1 gene was composed of 148 amino acids and contained a typical active site and 21 ubiquitin thioester intermediate interaction residues and 4 E3 interaction residues. Both exogenous application of salicylic acid and UV-B irradiation triggered expression of OgUBC1 in leaves of wild rice. Recombinant OgUBC1 proteins bound to ubiquitins in vitro, proposing that the protein might act as E2 enzyme in planta. Heterologous expression of the OgUBC1 in Arabidopsis thaliana protected plants from cellular damage caused by an excess of UV-B radiation. A stable expression of chalcone synthase gene was detected in leaves of OgUBC1-expressing Arabidopsis, resulting in producing higher amounts of anthocyanin than those in wild-type Col-0 plants. Additionally, both pathogenesis-related gene1 and 5 were transcribed in the transgenic Arabidopsis in the absence of pathogen infection. The OgUBC1-expressing plants were resistant to the infection of Botrytis cinerea. Taken together, we suggested that the OgUBC1 is involved in ubiquitination process important for cellular response against biotic and abiotic stresses in plants.

  13. Ectopic expression of ubiquitin-conjugating enzyme gene from wild rice, OgUBC1, confers resistance against UV-B radiation and Botrytis infection in Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, En Hee; Pak, Jung Hun; Kim, Mi Jin; Kim, Hye Jeong [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Shin, Sang Hyun [National Crop Experiment Station, Rural Development Administration, Suwon 441-100 (Korea, Republic of); Lee, Jai Heon; Kim, Doh Hoon; Oh, Ju Sung [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Oh, Boung-Jun [BioControl Center, Jeonnam 516-942 (Korea, Republic of); Jung, Ho Won, E-mail: hwjung@dau.ac.kr [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Chung, Young Soo, E-mail: chungys@dau.ac.kr [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of)

    2012-10-19

    Highlights: Black-Right-Pointing-Pointer We isolated a novel E2 ubiquitin-conjugating enzyme from leaves of wild rice plants. Black-Right-Pointing-Pointer The OgUBC1 was highly expressed in leaves treated with SA and UV-B radiation. Black-Right-Pointing-Pointer The recombinant OgUBC1 has an enzymatic activity of E2 in vitro. Black-Right-Pointing-Pointer The OgUBC1 could protect disruption of plant cells by UV-B radiation. Black-Right-Pointing-Pointer OgUBC1 confers disease resistance and UV-B tolerance in transgenic Arabidopsis plants. -- Abstract: A previously unidentified gene encoding ubiquitin-conjugating enzyme was isolated from leaves of wild rice plant treated with wounding and microbe-associated molecular patterns. The OgUBC1 gene was composed of 148 amino acids and contained a typical active site and 21 ubiquitin thioester intermediate interaction residues and 4 E3 interaction residues. Both exogenous application of salicylic acid and UV-B irradiation triggered expression of OgUBC1 in leaves of wild rice. Recombinant OgUBC1 proteins bound to ubiquitins in vitro, proposing that the protein might act as E2 enzyme in planta. Heterologous expression of the OgUBC1 in Arabidopsis thaliana protected plants from cellular damage caused by an excess of UV-B radiation. A stable expression of chalcone synthase gene was detected in leaves of OgUBC1-expressing Arabidopsis, resulting in producing higher amounts of anthocyanin than those in wild-type Col-0 plants. Additionally, both pathogenesis-related gene1 and 5 were transcribed in the transgenic Arabidopsis in the absence of pathogen infection. The OgUBC1-expressing plants were resistant to the infection of Botrytis cinerea. Taken together, we suggested that the OgUBC1 is involved in ubiquitination process important for cellular response against biotic and abiotic stresses in plants.

  14. Bacteriophytochromes control conjugation in Agrobacterium fabrum.

    Science.gov (United States)

    Bai, Yingnan; Rottwinkel, Gregor; Feng, Juan; Liu, Yiyao; Lamparter, Tilman

    2016-08-01

    Bacterial conjugation, the transfer of single stranded plasmid DNA from donor to recipient cell, is mediated through the type IV secretion system. We performed conjugation assays using a transmissible artificial plasmid as reporter. With this assay, conjugation in Agrobacterium fabrum was modulated by the phytochromes Agp1 and Agp2, photoreceptors that are most sensitive in the red region of visible light. In conjugation studies with wild-type donor cells carrying a pBIN-GUSINT plasmid as reporter that lacked the Ti (tumor inducing) plasmid, no conjugation was observed. When either agp1(-) or agp2(-) knockout donor strains were used, plasmid DNA was delivered to the recipient, indicating that both phytochromes suppress conjugation in the wild type donor. In the recipient strains, the loss of Agp1 or Agp2 led to diminished conjugation. When wild type cells with Ti plasmid and pBIN-GUS reporter plasmid were used as donor, a high rate of conjugation was observed. The DNA transfer was down regulated by red or far-red light by a factor of 3.5. With agp1(-) or agp2(-) knockout donor cells, conjugation in the dark was about 10 times lower than with the wild type donor, and with the double knockout donor no conjugation was observed. These results imply that the phytochrome system has evolved to inhibit conjugation in the light. The decrease of conjugation under different temperature correlated with the decrease of phytochrome autophosphorylation. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Imaging living central neurones using viral gene transfer.

    Science.gov (United States)

    Teschemacher, A G; Paton, J F R; Kasparov, S

    2005-01-02

    Studies of central neurones and other cellular components of the brain, such as glial and vascular cells, can be greatly advanced by the use of the modern optical techniques such as confocal live cell imaging. Fluorescent proteins have allowed imaging of particular cell types or intracellular elements to be visualised and distinguished from irrelevant background structures. To introduce the genetic information encoding for fluorescent proteins into relevant cellular targets, molecular tools are required. Viral vectors are one of the best ways of gene delivery into differentiated postnatal brain neurones and glia. Current progress in this field allows targeting of various cell types and therefore makes it possible to express a variety of fluorescent constructs in selected subpopulations of neurones, for example. In this review, we will discuss and compare the properties of the most popular viral gene delivery systems and the advantages of different brain cell preparations to illustrate how they can be used for high-resolution live cell confocal imaging in order to study new aspects of central nervous system (CNS) structure and function.

  16. Trans-10, cis-12-conjugated linoleic acid alters hepatic gene expression in a polygenic obese line of mice displaying hepatic lipidosis.

    Science.gov (United States)

    Ashwell, Melissa S; Ceddia, Ryan P; House, Ralph L; Cassady, Joseph P; Eisen, Eugene J; Eling, Thomas E; Collins, Jennifer B; Grissom, Sherry F; Odle, Jack

    2010-09-01

    The trans-10, cis-12 isomer of conjugated linoleic acid (CLA) causes a rapid reduction of body and adipose mass in mice. In addition to changes in adipose tissue, numerous studies have reported alterations in hepatic lipid metabolism. Livers of CLA-fed mice gain mass, partly due to lipid accumulation; however, the precise molecular mechanisms are unknown. To elucidate these mechanisms, we examined fatty acid composition and gene expression profiles of livers from a polygenic obese line of mice fed 1% trans-10, cis-12-CLA for 14 days. Analysis of gene expression data led to the identification of 1393 genes differentially expressed in the liver of CLA-fed male mice at a nominal P value of .01, and 775 were considered significant using a false discovery rate (FDR) threshold of .05. While surprisingly few genes in lipid metabolism were impacted, pathway analysis found that protein kinase A (PKA) and cyclic adenosine monophosphate (cAMP) pathways signaling pathways were affected by CLA treatment and 98 of the 775 genes were found to be regulated by hepatocyte nuclear factor 4alpha, a transcription factor important in controlling liver metabolic status. Copyright 2010 Elsevier Inc. All rights reserved.

  17. A conserved helicase processivity factor is needed for conjugation and replication of an integrative and conjugative element.

    Directory of Open Access Journals (Sweden)

    Jacob Thomas

    Full Text Available Integrative and conjugative elements (ICEs are agents of horizontal gene transfer and have major roles in evolution and acquisition of new traits, including antibiotic resistances. ICEs are found integrated in a host chromosome and can excise and transfer to recipient bacteria via conjugation. Conjugation involves nicking of the ICE origin of transfer (oriT by the ICE-encoded relaxase and transfer of the nicked single strand of ICE DNA. For ICEBs1 of Bacillus subtilis, nicking of oriT by the ICEBs1 relaxase NicK also initiates rolling circle replication. This autonomous replication of ICEBs1 is critical for stability of the excised element in growing cells. We found a conserved and previously uncharacterized ICE gene that is required for conjugation and replication of ICEBs1. Our results indicate that this gene, helP (formerly ydcP, encodes a helicase processivity factor that enables the host-encoded helicase PcrA to unwind the double-stranded ICEBs1 DNA. HelP was required for both conjugation and replication of ICEBs1, and HelP and NicK were the only ICEBs1 proteins needed for replication from ICEBs1 oriT. Using chromatin immunoprecipitation, we measured association of HelP, NicK, PcrA, and the host-encoded single-strand DNA binding protein Ssb with ICEBs1. We found that NicK was required for association of HelP and PcrA with ICEBs1 DNA. HelP was required for association of PcrA and Ssb with ICEBs1 regions distal, but not proximal, to oriT, indicating that PcrA needs HelP to progress beyond nicked oriT and unwind ICEBs1. In vitro, HelP directly stimulated the helicase activity of the PcrA homologue UvrD. Our findings demonstrate that HelP is a helicase processivity factor needed for efficient unwinding of ICEBs1 for conjugation and replication. Homologues of HelP and PcrA-type helicases are encoded on many known and putative ICEs. We propose that these factors are essential for ICE conjugation, replication, and genetic stability.

  18. Bacteriophage Mediates Efficient Gene Transfer in Combination with Conventional Transfection Reagents.

    Science.gov (United States)

    Donnelly, Amanda; Yata, Teerapong; Bentayebi, Kaoutar; Suwan, Keittisak; Hajitou, Amin

    2015-12-08

    The development of commercially available transfection reagents for gene transfer applications has revolutionized the field of molecular biology and scientific research. However, the challenge remains in ensuring that they are efficient, safe, reproducible and cost effective. Bacteriophage (phage)-based viral vectors have the potential to be utilized for general gene transfer applications within research and industry. Yet, they require adaptations in order to enable them to efficiently enter cells and overcome mammalian cellular barriers, as they infect bacteria only; furthermore, limited progress has been made at increasing their efficiency. The production of a novel hybrid nanocomplex system consisting of two different nanomaterial systems, phage vectors and conventional transfection reagents, could overcome these limitations. Here we demonstrate that the combination of cationic lipids, cationic polymers or calcium phosphate with M13 bacteriophage-derived vectors, engineered to carry a mammalian transgene cassette, resulted in increased cellular attachment, entry and improved transgene expression in human cells. Moreover, addition of a targeting ligand into the nanocomplex system, through genetic engineering of the phage capsid further increased gene expression and was effective in a stable cell line generation application. Overall, this new hybrid nanocomplex system (i) provides enhanced phage-mediated gene transfer; (ii) is applicable for laboratory transfection processes and (iii) shows promise within industry for large-scale gene transfer applications.

  19. In vivo tyrosinase mini-gene transfer enhances killing effect of BNCT on amelanotic melanoma

    International Nuclear Information System (INIS)

    Kondoh, H.; Mishima, Y.; Hiratsuka, J.; Iwakura, M.

    2000-01-01

    Using accentuated melanogenesis principally occurring within melanoma cells, we have successfully treated human malignant melanoma (Mm) with 10 B-BPA BNCT. Despite this success, there are still remaining issues for poorly melanogenic Mm and further non-pigment cell tumors. We found the selective accumulation of 10 B-BPA to Mm is primarily due to the complex formation of BPA and melanin-monomers activity synthesized within Mm cells. Then, we succeeded in transferring the tyrosinase gene into amelanotic to substantially produce melanin monomers. These cells has demonstrated increased boron accumulation and enhanced killing effect of BNCT. Further, transfection of TRP-2 (DOPAchrome tautomerase) gene into poorly eumelanotic and slightly phenomelanotic Mm cells in culture cell systems also led to increased BPA accumulation. Thereafter, we studied in vivo gene transfer. We transferred the tyrosinase mini-gene by intra-tumor injection into poorly melanotic Mm proliferating subcutaneously in hamster skin, and performed BNCT. Compared to control tumors, gene-transferred tumors showed increased BPA accumulation leading to enhanced killing effect. (author)

  20. In vivo tyrosinase mini-gene transfer enhances killing effect of BNCT on amelanotic melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Kondoh, H.; Mishima, Y. [Mishima Institute for Dermatological Research, Kobe, Hyogo (Japan); Hiratsuka, J. [Kawasaki Medical School, Dept. of Radiation Oncology, Kurashiki, Okayama (Japan); Iwakura, M. [Kobe Univ. (Japan). School of Medicine

    2000-10-01

    Using accentuated melanogenesis principally occurring within melanoma cells, we have successfully treated human malignant melanoma (Mm) with {sup 10}B-BPA BNCT. Despite this success, there are still remaining issues for poorly melanogenic Mm and further non-pigment cell tumors. We found the selective accumulation of {sup 10}B-BPA to Mm is primarily due to the complex formation of BPA and melanin-monomers activity synthesized within Mm cells. Then, we succeeded in transferring the tyrosinase gene into amelanotic to substantially produce melanin monomers. These cells has demonstrated increased boron accumulation and enhanced killing effect of BNCT. Further, transfection of TRP-2 (DOPAchrome tautomerase) gene into poorly eumelanotic and slightly phenomelanotic Mm cells in culture cell systems also led to increased BPA accumulation. Thereafter, we studied in vivo gene transfer. We transferred the tyrosinase mini-gene by intra-tumor injection into poorly melanotic Mm proliferating subcutaneously in hamster skin, and performed BNCT. Compared to control tumors, gene-transferred tumors showed increased BPA accumulation leading to enhanced killing effect. (author)

  1. Analysis of bone marrow stromal cell transferred bacterial {beta}-galactosidase gene by PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Kumakawa, Toshiro [Tokyo Metropolitan Geriatric Hospital, Tokyo (Japan). Dept. of Blood Transfusion and Hematology; Hibino, Hitoshi; Tani, Kenzaburo; Asano, Shigetaka; Futatugawa, Shouji; Sera, Kouichiro

    1997-12-31

    PIXE, Particle Induced X-ray Emission, is a powerful, multi-elemental analysis method which has many distinguishing features and has been used in varies research fields. Recently the method of applying baby cyclotrons for nuclear medicine to PIXE has been developed. This enables us to study biomedical phenomena from the physical point of view. Mouse bone marrow stromal cells were transferred bacterial {beta}-galactosidase gene (LacZ gene) by murine retroviral vectors. Analysis of the bone marrow stromal cells with the LacZ gene by PIXE revealed remarkable changes of intracellular trace elements compared with the normal control cells. These results indicate that gene transfer by retroviral vectors may bring about a dynamic change of intracellular circumstances of the target cell. (author)

  2. Collective evolution of cyanobacteria and cyanophages mediated by horizontal gene transfer

    Science.gov (United States)

    Shih, Hong-Yan; Rogers, Tim; Goldenfeld, Nigel

    We describe a model for how antagonistic predator-prey coevolution can lead to mutualistic adaptation to an environment, as a result of horizontal gene transfer. Our model is a simple description of ecosystems such as marine cyanobacteria and their predator cyanophages, which carry photosynthesis genes. These genes evolve more rapidly in the virosphere than the bacterial pan-genome, and thus the bacterial population could potentially benefit from phage predation. By modeling both the barrier to predation and horizontal gene transfer, we study this balance between individual sacrifice and collective benefits. The outcome is an emergent mutualistic coevolution of improved photosynthesis capability, benefiting both bacteria and phage. This form of multi-level selection can contribute to niche stratification in the cyanobacteria-phage ecosystem. This work is supported in part by a cooperative agreement with NASA, Grant NNA13AA91A/A0018.

  3. Graphene materials as 2D non-viral gene transfer vector platforms.

    Science.gov (United States)

    Vincent, M; de Lázaro, I; Kostarelos, K

    2017-03-01

    Advances in genomics and gene therapy could offer solutions to many diseases that remain incurable today, however, one of the critical reasons halting clinical progress is due to the difficulty in designing efficient and safe delivery vectors for the appropriate genetic cargo. Safety and large-scale production concerns counter-balance the high gene transfer efficiency achieved with viral vectors, while non-viral strategies have yet to become sufficiently efficient. The extraordinary physicochemical, optical and photothermal properties of graphene-based materials (GBMs) could offer two-dimensional components for the design of nucleic acid carrier systems. We discuss here such properties and their implications for the optimization of gene delivery. While the design of such vectors is still in its infancy, we provide here an exhaustive and up-to-date analysis of the studies that have explored GBMs as gene transfer vectors, focusing on the functionalization strategies followed to improve vector performance and on the biological effects attained.

  4. Subthalamic hGAD65 Gene Therapy and Striatum TH Gene Transfer in a Parkinson’s Disease Rat Model

    Science.gov (United States)

    Zheng, Deyu; Jiang, Xiaohua; Zhao, Junpeng; Duan, Deyi; Zhao, Huanying; Xu, Qunyuan

    2013-01-01

    The aim of the present study is to detect a combination method to utilize gene therapy for the treatment of Parkinson’s disease (PD). Here, a PD rat model is used for the in vivo gene therapy of a recombinant adeno-associated virus (AAV2) containing a human glutamic acid decarboxylase 65 (rAAV2-hGAD65) gene delivered to the subthalamic nucleus (STN). This is combined with the ex vivo gene delivery of tyrosine hydroxylase (TH) by fibroblasts injected into the striatum. After the treatment, the rotation behavior was improved with the greatest efficacy in the combination group. The results of immunohistochemistry showed that hGAD65 gene delivery by AAV2 successfully led to phenotypic changes of neurons in STN. And the levels of glutamic acid and GABA in the internal segment of the globus pallidus (GPi) and substantia nigra pars reticulata (SNr) were obviously lower than the control groups. However, hGAD65 gene transfer did not effectively protect surviving dopaminergic neurons in the SNc and VTA. This study suggests that subthalamic hGAD65 gene therapy and combined with TH gene therapy can alleviate symptoms of the PD model rats, independent of the protection the DA neurons from death. PMID:23738148

  5. Synthesis and Characterization of Cationic Glycidyl-Based Poly(aminoester-Folic Acid Targeting Conjugates and Study on Gene Delivery

    Directory of Open Access Journals (Sweden)

    Yu Che Hsiao

    2012-07-01

    Full Text Available A new poly(aminoester (EPAE-FA containing folic acid and amino groups in the backbone and side chain was synthesized. EPAE-FA self-assembled readily with the plasmid DNA (pCMV-βgal in HEPES buffer and was characterized by dynamic light scattering, zeta potential, fluorescence images, and XTT cell viability assays. To evaluate the transfection effect of graft ratio of FA on the EPAE system, EPAE-FA polymers with two different graft ratios (EPAE-FA12k and EPAE-FA14k were also prepared. This study found that all EPAE-FA polymers were able to bind plasmid DNA and yielded positively charged complexes with nano-sized particles ( < 200 nm. To assess the transfection efficiency mediated by EPAE and EPAE-FA polymers, we performed in vitro transfection activity assays using FR-negative (COS-7 and FR-positive (HeLa cells. The EPAE-FA12k/DNA and EPAE-FA14k/DNA complexes were able to transfect HeLa cell in vitro with higher transfection efficiency than PEI25k/DNA at the similar weight ratio. These results demonstrated that the introduction of FA into EPAE system had a significant effect on transferring ability for FR-positive cells (HeLa. Examination of the cytotoxicity of PEI25k and EPAE-FA system revealed that EPAE-FA system had lower cytotoxicity. In this paper, EPAE-FA seemed to be a novel cationic poly(aminoester for gene delivery and an interesting candidate for further study.

  6. Horizontal transfer of a eukaryotic plastid-targeted protein gene to cyanobacteria

    Directory of Open Access Journals (Sweden)

    Keeling Patrick J

    2007-06-01

    Full Text Available Abstract Background Horizontal or lateral transfer of genetic material between distantly related prokaryotes has been shown to play a major role in the evolution of bacterial and archaeal genomes, but exchange of genes between prokaryotes and eukaryotes is not as well understood. In particular, gene flow from eukaryotes to prokaryotes is rarely documented with strong support, which is unusual since prokaryotic genomes appear to readily accept foreign genes. Results Here, we show that abundant marine cyanobacteria in the related genera Synechococcus and Prochlorococcus acquired a key Calvin cycle/glycolytic enzyme from a eukaryote. Two non-homologous forms of fructose bisphosphate aldolase (FBA are characteristic of eukaryotes and prokaryotes respectively. However, a eukaryotic gene has been inserted immediately upstream of the ancestral prokaryotic gene in several strains (ecotypes of Synechococcus and Prochlorococcus. In one lineage this new gene has replaced the ancestral gene altogether. The eukaryotic gene is most closely related to the plastid-targeted FBA from red algae. This eukaryotic-type FBA once replaced the plastid/cyanobacterial type in photosynthetic eukaryotes, hinting at a possible functional advantage in Calvin cycle reactions. The strains that now possess this eukaryotic FBA are scattered across the tree of Synechococcus and Prochlorococcus, perhaps because the gene has been transferred multiple times among cyanobacteria, or more likely because it has been selectively retained only in certain lineages. Conclusion A gene for plastid-targeted FBA has been transferred from red algae to cyanobacteria, where it has inserted itself beside its non-homologous, functional analogue. Its current distribution in Prochlorococcus and Synechococcus is punctate, suggesting a complex history since its introduction to this group.

  7. Extensive horizontal transfer of core genome genes between two Lactobacillus species found in the gastrointestinal tract

    Directory of Open Access Journals (Sweden)

    Maguin Emmanuelle

    2007-08-01

    Full Text Available Abstract Background While genes that are conserved between related bacterial species are usually thought to have evolved along with the species, phylogenetic trees reconstructed for individual genes may contradict this picture and indicate horizontal gene transfer. Individual trees are often not resolved with high confidence, however, and in that case alternative trees are generally not considered as contradicting the species tree, although not confirming it either. Here we conduct an in-depth analysis of 401 protein phylogenetic trees inferred with varying levels of confidence for three lactobacilli from the acidophilus complex. At present the relationship between these bacteria, isolated from environments as diverse as the gastrointestinal tract (Lactobacillus acidophilus and Lactobacillus johnsonii and yogurt (Lactobacillus delbrueckii ssp. bulgaricus, is ambiguous due to contradictory phenotypical and 16S rRNA based classifications. Results Among the 401 phylogenetic trees, those that could be reconstructed with high confidence support the 16S-rRNA tree or one alternative topology in an astonishing 3:2 ratio, while the third possible topology is practically absent. Lowering the confidence threshold for trees to be taken into consideration does not significantly affect this ratio, and therefore suggests that gene transfer may have affected as much as 40% of the core genome genes. Gene function bias suggests that the 16S rRNA phylogeny of the acidophilus complex, which indicates that L. acidophilus and L. delbrueckii ssp. bulgaricus are the closest related of these three species, is correct. A novel approach of comparison of interspecies protein divergence data employed in this study allowed to determine that gene transfer most likely took place between the lineages of the two species found in the gastrointestinal tract. Conclusion This case-study reports an unprecedented level of phylogenetic incongruence, presumably resulting from extensive

  8. Detection of horizontal transfer of individual genes by anomalous oligomer frequencies

    Directory of Open Access Journals (Sweden)

    Elhai Jeff

    2012-06-01

    Full Text Available Abstract Background Understanding the history of life requires that we understand the transfer of genetic material across phylogenetic boundaries. Detecting genes that were acquired by means other than vertical descent is a basic step in that process. Detection by discordant phylogenies is computationally expensive and not always definitive. Many have used easily computed compositional features as an alternative procedure. However, different compositional methods produce different predictions, and the effectiveness of any method is not well established. Results The ability of octamer frequency comparisons to detect genes artificially seeded in cyanobacterial genomes was markedly increased by using as a training set those genes that are highly conserved over all bacteria. Using a subset of octamer frequencies in such tests also increased effectiveness, but this depended on the specific target genome and the source of the contaminating genes. The presence of high frequency octamers and the GC content of the contaminating genes were important considerations. A method comprising best practices from these tests was devised, the Core Gene Similarity (CGS method, and it performed better than simple octamer frequency analysis, codon bias, or GC contrasts in detecting seeded genes or naturally occurring transposons. From a comparison of predictions with phylogenetic trees, it appears that the effectiveness of the method is confined to horizontal transfer events that have occurred recently in evolutionary time. Conclusions The CGS method may be an improvement over existing surrogate methods to detect genes of foreign origin.

  9. Horizontal transfer of a nitrate assimilation gene cluster and ecological transitions in fungi: a phylogenetic study.

    Directory of Open Access Journals (Sweden)

    Jason C Slot

    Full Text Available High affinity nitrate assimilation genes in fungi occur in a cluster (fHANT-AC that can be coordinately regulated. The clustered genes include nrt2, which codes for a high affinity nitrate transporter; euknr, which codes for nitrate reductase; and NAD(PH-nir, which codes for nitrite reductase. Homologs of genes in the fHANT-AC occur in other eukaryotes and prokaryotes, but they have only been found clustered in the oomycete Phytophthora (heterokonts. We performed independent and concatenated phylogenetic analyses of homologs of all three genes in the fHANT-AC. Phylogenetic analyses limited to fungal sequences suggest that the fHANT-AC has been transferred horizontally from a basidiomycete (mushrooms and smuts to an ancestor of the ascomycetous mold Trichoderma reesei. Phylogenetic analyses of sequences from diverse eukaryotes and eubacteria, and cluster structure, are consistent with a hypothesis that the fHANT-AC was assembled in a lineage leading to the oomycetes and was subsequently transferred to the Dikarya (Ascomycota+Basidiomycota, which is a derived fungal clade that includes the vast majority of terrestrial fungi. We propose that the acquisition of high affinity nitrate assimilation contributed to the success of Dikarya on land by allowing exploitation of nitrate in aerobic soils, and the subsequent transfer of a complete assimilation cluster improved the fitness of T. reesei in a new niche. Horizontal transmission of this cluster of functionally integrated genes supports the "selfish operon" hypothesis for maintenance of gene clusters.

  10. Phylogenomic analysis demonstrates a pattern of rare and ancient horizontal gene transfer between plants and fungi.

    Science.gov (United States)

    Richards, Thomas A; Soanes, Darren M; Foster, Peter G; Leonard, Guy; Thornton, Christopher R; Talbot, Nicholas J

    2009-07-01

    Horizontal gene transfer (HGT) describes the transmission of genetic material across species boundaries and is an important evolutionary phenomenon in the ancestry of many microbes. The role of HGT in plant evolutionary history is, however, largely unexplored. Here, we compare the genomes of six plant species with those of 159 prokaryotic and eukaryotic species and identify 1689 genes that show the highest similarity to corresponding genes from fungi. We constructed a phylogeny for all 1689 genes identified and all homolog groups available from the rice (Oryza sativa) genome (3177 gene families) and used these to define 14 candidate plant-fungi HGT events. Comprehensive phylogenetic analyses of these 14 data sets, using methods that account for site rate heterogeneity, demonstrated support for nine HGT events, demonstrating an infrequent pattern of HGT between plants and fungi. Five HGTs were fungi-to-plant transfers and four were plant-to-fungi HGTs. None of the fungal-to-plant HGTs involved angiosperm recipients. These results alter the current view of organismal barriers to HGT, suggesting that phagotrophy, the consumption of a whole cell by another, is not necessarily a prerequisite for HGT between eukaryotes. Putative functional annotation of the HGT candidate genes suggests that two fungi-to-plant transfers have added phenotypes important for life in a soil environment. Our study suggests that genetic exchange between plants and fungi is exceedingly rare, particularly among the angiosperms, but has occurred during their evolutionary history and added important metabolic traits to plant lineages.

  11. Operon Formation is Driven by Co-Regulation and Not by Horizontal Gene Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Price, Morgan N.; Huang, Katherine H.; Arkin, Adam P.; Alm, Eric J.

    2005-04-12

    Although operons are often subject to horizontal gene transfer (HGT), non-HGT genes are particularly likely to be in operons. To resolve this apparent discrepancy and to determine whether HGT is involved in operon formation, we examined the evolutionary history of the genes and operons in Escherichia coli K12. We show that genes that have homologs in distantly related bacteria but not in close relatives of E. coli (indicating HGTi) form new operons at about the same rates as native genes. Furthermore, genes in new operons are no more likely than other genes to have phylogenetic trees that are inconsistent with the species tree. In contrast, essential genes and ubiquitous genes without paralogs (genes believed to undergo HGT rarely) often form new operons. We conclude that HGT is not associated with operon formation, but instead promotes the prevalence of pre-existing operons. To explain operon formation, we propose that new operons reduce the amount of regulatory information required to specify optimal expression patterns. Consistent with this hypothesis, operons have greater amounts of conserved regulatory sequences than do individually transcribed genes.

  12. THE RISK OF TRANSFER OF GENES IN THE INSURANCE PROTECTION OF AGRICULTURAL PRODUCERS

    Directory of Open Access Journals (Sweden)

    Henrikh Hudz

    2017-09-01

    Full Text Available The paper deals with the risk of transfer of genes, its impact, and possible consequences for agricultural producers; the possibility of creating an insurance service, to address this risk. The purpose of the paper is to disclose the results of a study of the risk of transfer of genes in agriculture when organizing insurance coverage. The tasks of this paper are: to clarify the essence of genetic engineering as an object of providing insurance services; to define the concept of risk of transfer of genes, its specific features, impact, and possible consequences for agricultural producers; carry out a description of the possibility of creating an insurance service about the risk of transfer of genes. The object of the study is the risk of transfer of genes in insurance protection. The subject of the study is theoretical and methodological approaches to optimizing the risk of transfer of genes in insurance protection. Methodology. This work requires attracting a large number of scientists from different fields. Legal Aspects covered in the EU Regulation Terms №1829/2003 and 1830/2003 of the European Parliament and Council. A considerable attention to the legislative regulation of genetic engineering and risks in the use of genetic modification is given to the Cartagena Protocol on Biosafety. It should be noted that at present, economic literature and especially publications related to agricultural insurance protection do not pay attention to the risks associated with the transfer of transgenic organisms and the possibility of taking this risk to insurance. The work uses the experience of the US Department of Agriculture and the European Center for Insurance Legislation. The results of the study showed that the introduction of the insurance mechanism has the main difference in the fact that this operation takes into account as a person who suffered a loss, could get more profit than the fact of causing damage to another farmer. In this regard, the

  13. Horizontal gene transfer and nucleotide compositional anomaly in large DNA viruses

    Directory of Open Access Journals (Sweden)

    Ogata Hiroyuki

    2007-12-01

    Full Text Available Abstract Background DNA viruses have a wide range of genome sizes (5 kb up to 1.2 Mb, compared to 0.16 Mb to 1.5 Mb for obligate parasitic bacteria that do not correlate with their virulence or the taxonomic distribution of their hosts. The reasons for such large variation are unclear. According to the traditional view of viruses as gifted "gene pickpockets", large viral genome sizes could originate from numerous gene acquisitions from their hosts. We investigated this hypothesis by studying 67 large DNA viruses with genome sizes larger than 150 kb, including the recently characterized giant mimivirus. Given that horizontally transferred DNA often have anomalous nucleotide compositions differing from the rest of the genome, we conducted a detailed analysis of the inter- and intra-genome compositional properties of these viruses. We then interpreted their compositional heterogeneity in terms of possible causes, including strand asymmetry, gene function/expression, and horizontal transfer. Results We first show that the global nucleotide composition and nucleotide word usage of viral genomes are species-specific and distinct from those of their hosts. Next, we identified compositionally anomalous (cA genes in viral genomes, using a method based on Bayesian inference. The proportion of cA genes is highly variable across viruses and does not exhibit a significant correlation with genome size. The vast majority of the cA genes were of unknown function, lacking homologs in the databases. For genes with known homologs, we found a substantial enrichment of cA genes in specific functional classes for some of the viruses. No significant association was found between cA genes and compositional strand asymmetry. A possible exogenous origin for a small fraction of the cA genes could be confirmed by phylogenetic reconstruction. Conclusion At odds with the traditional dogma, our results argue against frequent genetic transfers to large DNA viruses from their

  14. Horizontal gene transfer of a plastid gene in the non-photosynthetic flowering plants Orobanche and Phelipanche (Orobanchaceae).

    Science.gov (United States)

    Park, Jeong-Mi; Manen, Jean-François; Schneeweiss, Gerald M

    2007-06-01

    Plastid sequences are among the most widely used in phylogenetic and phylogeographic studies in flowering plants, where they are usually assumed to evolve like non-recombining, uniparentally transmitted, single-copy genes. Among others, this assumption can be violated by intracellular gene transfer (IGT) within cells or by the exchange of genes across mating barriers (horizontal gene transfer, HGT). We report on HGT of a plastid region including rps2, trnL-F, and rbcL in a group of non-photosynthetic flowering plants. Species of the parasitic broomrape genus Phelipanche harbor two copies of rps2, a plastid ribosomal gene, one corresponding to the phylogenetic position of the respective species, the other being horizontally acquired from the related broomrape genus Orobanche. While the vertically transmitted copies probably reside within the plastid genome, the localization of the horizontally acquired copies is not known. With both donor and recipient being parasitic plants, a possible pathway for the exchange of genetic material is via a commonly attacked host.

  15. Fluorescent strategy based on cationic conjugated polymer fluorescence resonance energy transfer for the quantification of 5-(hydroxymethyl)cytosine in genomic DNA.

    Science.gov (United States)

    Hong, Tingting; Wang, Tianlu; Guo, Pu; Xing, Xiwen; Ding, Fei; Chen, Yuqi; Wu, Jinjun; Ma, Jingwei; Wu, Fan; Zhou, Xiang

    2013-11-19

    DNA methylation is dynamically reprogrammed during early embryonic development in mammals. It can be explained partially by the discovery of 5-(hydroxymethyl)cytosine (5-hmC), 5-formylcytosine (5-fC), and 5-carboxylcytosine (5-caC), which are identified as key players involved in both active and passive demethylation pathways. As one of the ten-eleven translocation oxidation products, 5-hmC was found relatively abundant in neuron cells and embryonic stem cells. Herein we report a new method for 5-hmC quantification in genomic DNA based on CCP-FRET (cationic conjugated polymers act as the energy donor and induce fluorescence resonance energy transfer) assay combined with KRuO4 oxidation. 5-hmC in genomic DNA can be selectively transformed into 5-fC by the oxidation of KRuO4 and then labeled with hydroxylamine-BODIPY (BODIPY = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) fluorophore through the reaction between 5-fC and hydroxylamine-BODIPY. After the fluorescently labeled DNA was captured by CCP through electrostatic interactions, a significant FRET between CCP and hydroxylamine-BODIPY fluorophore was observed. This CCP-FRET-based assay benefits from light-harvesting, large Stokes shift, and optical signal amplification properties of the CCP. Furthermore, this CCP-FRET-based assay was quite successfully demonstrated for the 5-hmC quantification in three types of cells (mESc, HeLa, HEK 293T), providing a much more convenient choice for 5-hmC quantification in genomic DNA.

  16. Adeno-associated virus-mediated gene transfer.

    Science.gov (United States)

    Srivastava, Arun

    2008-09-01

    Although the remarkable versatility and efficacy of recombinant adeno-associated virus 2 (AAV2) vectors in transducing a wide variety of cells and tissues in vitro, and in numerous pre-clinical animal models of human diseases in vivo, have been well established, the published literature is replete with controversies with regard to the efficacy of AAV2 vectors in hematopoietic stem cell (HSC) transduction. A number of factors have contributed to these controversies, the molecular bases of which have begun to come to light in recent years. With the availability of several novel serotypes (AAV1 through AAV12), rational design of AAV capsid mutants, and strategies (self-complementary vector genomes, hematopoietic cell-specific promoters), it is indeed becoming feasible to achieve efficient transduction of HSC by AAV vectors. Using a murine serial bone marrow transplantation model in vivo, we have recently documented stable integration of the proviral AAV genome into mouse chromosomes, which does not lead to any overt hematological abnormalities. Thus, a better understanding of the AAV-HSC interactions, and the availability of a vast repertoire of novel serotype and capsid mutant vectors, are likely to have significant implications in the use of AAV vectors in high-efficiency transduction of HSCs as well as in gene therapy applications involving the hematopoietic system. (c) 2008 Wiley-Liss, Inc.

  17. Identification of a Divided Genome for VSH-1, the Prophage-Like Gene Transfer Agent of Brachyspira hyodysenteriae

    Science.gov (United States)

    The Brachyspira hyodysenteriae B204 genome sequence revealed three VSH-1 tail genes hvp31, hvp60, and hvp37, in a 3.6 kb cluster. The location and transcription direction of these genes relative to the previously described VSH-1 16.3 kb gene operon indicate that the gene transfer agent VSH-1 has a ...

  18. Ethical perception of cross-species gene transfer in plant | Amin ...

    African Journals Online (AJOL)

    Plants can be genetically modified through a variety of methods in the hope that it will be improved in some way to increase the yield and quality of a crop, or to add nutritional value or shelf life. The development of genetically modified (GM) rice to enrich its nutritional value, such as Vitamin C might involve gene transfer ...

  19. Role of Horizontal Gene Transfer in the Evolution of Plant Parasitism Among Nematodes

    NARCIS (Netherlands)

    Mitreva, M.; Smant, G.; Helder, J.

    2009-01-01

    Horizontal gene transfer (HGT) implies the non-sexual exchange of genetic material between species ¿ in some cases even across kingdoms. Although common among Bacteria and Archaea, HGTs from pro- to eukaryotes and between eukaryotes were thought to be extremely rare. Recent studies on intracellular

  20. An efficient marker-free vector for clean gene transfer into plants ...

    African Journals Online (AJOL)

    A marker-free vector, pBINMF, for clean gene transfer was constructed based on the binary vector pBINPLUS. Vector pBINMF, carrying only a multiple cloning site (MCS) between the left and the right T-DNA border, was suitable to directly generate marker-free transgenic plants (MFTPs) without any vector sequences ...

  1. Transfer of Chinese hamster DNA repair gene(s) into repair-deficient human cells (Xeroderma pigmentosum)

    International Nuclear Information System (INIS)

    Karentz, D.; Cleaver, J.E.

    1985-01-01

    Transfer of repair genes by DNA transfection into repair-deficient Xeroderma pigmentosum (XP) cells has thus far been unsuccessful, presenting an obstacle to cloning XP genes. The authors chose an indirect route to transfer repair genes in chromosome fragments. DNA repair-competent (UV resistant) hybrid cell lines were established by PEG-mediated fusions of DNA repair-deficient (UV sensitive) human fibroblasts (XP12RO) with wild type Chinese hamster (CHO) cells (AA8). CHO cells were exposed to 5 Krad X-rays prior to fusions, predisposing hybrid cells to lose CHO chromosome fragments preferentially. Repair-competent hybrids were selected by periodic exposures to UV light. Secondary and tertiary hybrid cell lines were developed by fusion of X-irradiated hybrids to XP12RO. The hybrid cell lines exhibit resistance to UV that is comparable to that of CHO cells and they are proficient at repair replication after UV exposure. Whole cell DNA-DNA hybridizations indicate that the hybrids have greater homology to CHO DNA than is evident between XP12RO and CHO. These observations indicate that CHO DNA sequences which can function in repair of UV-damaged DNA in human cells have been transferred into the genome of the repair-deficient XP12RO cells

  2. Evidence for the intense exchange of MazG in marine cyanophages by horizontal gene transfer.

    Directory of Open Access Journals (Sweden)

    Michael J Bryan

    Full Text Available BACKGROUND: S-PM2 is a phage capable of infecting strains of unicellular cyanobacteria belonging to the genus Synechococcus. S-PM2, like other myoviruses infecting marine cyanobacteria, encodes a number of bacterial-like genes. Amongst these genes is one encoding a MazG homologue that is hypothesized to be involved in the adaption of the infected host for production of progeny phage. METHODOLOGY/PRINCIPAL FINDINGS: This study focuses on establishing the occurrence of mazG homologues in other cyanophages isolated from different oceanic locations. Degenerate PCR primers were designed using the mazG gene of S-PM2. The mazG gene was found to be widely distributed and highly conserved among Synechococcus myoviruses and podoviruses from diverse oceanic provinces. CONCLUSIONS/SIGNIFICANCE: This study provides evidence of a globally connected cyanophage gene pool, the cyanophage mazG gene having a small effective population size indicative of rapid lateral gene transfer despite being present in a substantial fraction of cyanophage. The Prochlorococcus and Synechococcus phage mazG genes do not cluster with the host mazG gene, suggesting that their primary hosts are not the source of the mazG gene.

  3. Phylogenetic evidence for lateral gene transfer in the intestine of marine iguanas.

    Directory of Open Access Journals (Sweden)

    David M Nelson

    Full Text Available BACKGROUND: Lateral gene transfer (LGT appears to promote genotypic and phenotypic variation in microbial communities in a range of environments, including the mammalian intestine. However, the extent and mechanisms of LGT in intestinal microbial communities of non-mammalian hosts remains poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: We sequenced two fosmid inserts obtained from a genomic DNA library derived from an agar-degrading enrichment culture of marine iguana fecal material. The inserts harbored 16S rRNA genes that place the organism from which they originated within Clostridium cluster IV, a well documented group that habitats the mammalian intestinal tract. However, sequence analysis indicates that 52% of the protein-coding genes on the fosmids have top BLASTX hits to bacterial species that are not members of Clostridium cluster IV, and phylogenetic analysis suggests that at least 10 of 44 coding genes on the fosmids may have been transferred from Clostridium cluster XIVa to cluster IV. The fosmids encoded four transposase-encoding genes and an integrase-encoding gene, suggesting their involvement in LGT. In addition, several coding genes likely involved in sugar transport were probably acquired through LGT. CONCLUSION: Our phylogenetic evidence suggests that LGT may be common among phylogenetically distinct members of the phylum Firmicutes inhabiting the intestinal tract of marine iguanas.

  4. Phylogenetic evidence for lateral gene transfer in the intestine of marine iguanas.

    Science.gov (United States)

    Nelson, David M; Cann, Isaac K O; Altermann, Eric; Mackie, Roderick I

    2010-05-24

    Lateral gene transfer (LGT) appears to promote genotypic and phenotypic variation in microbial communities in a range of environments, including the mammalian intestine. However, the extent and mechanisms of LGT in intestinal microbial communities of non-mammalian hosts remains poorly understood. We sequenced two fosmid inserts obtained from a genomic DNA library derived from an agar-degrading enrichment culture of marine iguana fecal material. The inserts harbored 16S rRNA genes that place the organism from which they originated within Clostridium cluster IV, a well documented group that habitats the mammalian intestinal tract. However, sequence analysis indicates that 52% of the protein-coding genes on the fosmids have top BLASTX hits to bacterial species that are not members of Clostridium cluster IV, and phylogenetic analysis suggests that at least 10 of 44 coding genes on the fosmids may have been transferred from Clostridium cluster XIVa to cluster IV. The fosmids encoded four transposase-encoding genes and an integrase-encoding gene, suggesting their involvement in LGT. In addition, several coding genes likely involved in sugar transport were probably acquired through LGT. Our phylogenetic evidence suggests that LGT may be common among phylogenetically distinct members of the phylum Firmicutes inhabiting the intestinal tract of marine iguanas.

  5. Phylogenetic Evidence for Lateral Gene Transfer in the Intestine of Marine Iguanas

    Science.gov (United States)

    Nelson, David M.; Cann, Isaac K. O.; Altermann, Eric; Mackie, Roderick I.

    2010-01-01

    Background Lateral gene transfer (LGT) appears to promote genotypic and phenotypic variation in microbial communities in a range of environments, including the mammalian intestine. However, the extent and mechanisms of LGT in intestinal microbial communities of non-mammalian hosts remains poorly understood. Methodology/Principal Findings We sequenced two fosmid inserts obtained from a genomic DNA library derived from an agar-degrading enrichment culture of marine iguana fecal material. The inserts harbored 16S rRNA genes that place the organism from which they originated within Clostridium cluster IV, a well documented group that habitats the mammalian intestinal tract. However, sequence analysis indicates that 52% of the protein-coding genes on the fosmids have top BLASTX hits to bacterial species that are not members of Clostridium cluster IV, and phylogenetic analysis suggests that at least 10 of 44 coding genes on the fosmids may have been transferred from Clostridium cluster XIVa to cluster IV. The fosmids encoded four transposase-encoding genes and an integrase-encoding gene, suggesting their involvement in LGT. In addition, several coding genes likely involved in sugar transport were probably acquired through LGT. Conclusion Our phylogenetic evidence suggests that LGT may be common among phylogenetically distinct members of the phylum Firmicutes inhabiting the intestinal tract of marine iguanas. PMID:20520734

  6. Evolutionary maintenance of selfish homing endonuclease genes in the absence of horizontal transfer.

    Science.gov (United States)

    Yahara, Koji; Fukuyo, Masaki; Sasaki, Akira; Kobayashi, Ichizo

    2009-11-03

    Homing endonuclease genes are "selfish" mobile genetic elements whose endonuclease promotes the spread of its own gene by creating a break at a specific target site and using the host machinery to repair the break by copying and inserting the gene at this site. Horizontal transfer across the boundary of a species or population within which mating takes place has been thought to be necessary for their evolutionary persistence. This is based on the assumption that they will become fixed in a host population, where opportunities of homing will disappear, and become susceptible to degeneration. To test this hypothesis, we modeled behavior of a homing endonuclease gene that moves during meiosis through double-strand break repair. We mathematically explored conditions for persistence of the homing endonuclease gene and elucidated their parameter dependence as phase diagrams. We found that, if the cost of the pseudogene is lower than that of the homing endonuclease gene, the 2 forms can persist in a population through autonomous periodic oscillation. If the cost of the pseudogene is higher, 2 types of dynamics appear that enable evolutionary persistence: bistability dependent on initial frequency or fixation irrespective of initial frequency. The prediction of long persistence in the absence of horizontal transfer was confirmed by stochastic simulations in finite populations. The average time to extinction of the endonuclease gene was found to be thousands of meiotic generations or more based on realistic parameter values. These results provide a solid theoretical basis for an understanding of these and other extremely selfish elements.

  7. Low cytotoxicity effect of dendrosome as an efficient carrier for rotavirus VP2 gene transferring into a human lung cell line : dendrosome, as a novel intranasally gene porter.

    Science.gov (United States)

    Pourasgari, Farzaneh; Ahmadian, Shahin; Salmanian, Ali Hatef; Sarbolouki, Mohammad Nabi; Massumi, Mohammad

    2009-01-01

    The efficiency of dendrosome (a gene porter) was assessed in transferring recombinant human rotavirus VP2 cDNA into A549, a human lung cell line. After gene transferring, transmission electron microscopy showed core-like particles (CLPs) formation in the transfected cells both with dendrosome and lipofectamine porters. In addition, western blotting analysis showed that the expression of VP2 gene was almost equal in the dendrosome and lipofectamine-transfected cells. Also, the cytotoxicity studies revealed that dendrosome had a lower cytotoxicity than lipofectamine. Therefore, our study may introduce dendrosome as a possible carrier for gene transferring into the human lung cell line, especially, for intranasally administration of DNA vaccines.

  8. Dynamic evolution of Geranium mitochondrial genomes through multiple horizontal and intracellular gene transfers.

    Science.gov (United States)

    Park, Seongjun; Grewe, Felix; Zhu, Andan; Ruhlman, Tracey A; Sabir, Jamal; Mower, Jeffrey P; Jansen, Robert K

    2015-10-01

    The exchange of genetic material between cellular organelles through intracellular gene transfer (IGT) or between species by horizontal gene transfer (HGT) has played an important role in plant mitochondrial genome evolution. The mitochondrial genomes of Geraniaceae display a number of unusual phenomena including highly accelerated rates of synonymous substitutions, extensive gene loss and reduction in RNA editing. Mitochondrial DNA sequences assembled for 17 species of Geranium revealed substantial reduction in gene and intron content relative to the ancestor of the Geranium lineage. Comparative analyses of nuclear transcriptome data suggest that a number of these sequences have been functionally relocated to the nucleus via IGT. Evidence for rampant HGT was detected in several Geranium species containing foreign organellar DNA from diverse eudicots, including many transfers from parasitic plants. One lineage has experienced multiple, independent HGT episodes, many of which occurred within the past 5.5 Myr. Both duplicative and recapture HGT were documented in Geranium lineages. The mitochondrial genome of Geranium brycei contains at least four independent HGT tracts that are absent in its nearest relative. Furthermore, G. brycei mitochondria carry two copies of the cox1 gene that differ in intron content, providing insight into contrasting hypotheses on cox1 intron evolution. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  9. Efficient gene transfer into lymphoma cells using adenoviral vectors combined with lipofection.

    Science.gov (United States)

    Buttgereit, P; Weineck, S; Röpke, G; Märten, A; Brand, K; Heinicke, T; Caselmann, W H; Huhn, D; Schmidt-Wolf, I G

    2000-08-01

    Tumor cells, such as lymphoma cells, are possible targets for gene therapy. In general, gene therapeutic approaches require efficient gene transfer to host cells and sufficient transgene expression. However, lymphoma cells previously have been demonstrated to be resistant to most of the currently available gene transfer methods. The aim of this study was to analyze various methods for transfection of lymphoma cells and to improve the efficiency of gene delivery. In accordance with previously published reports, lymphoma cells were demonstrated to be resistant to lipofection and electroporation. In contrast, we present an improved adenoviral protocol leading to highly efficient gene transfer to lymphoma cell lines derived from B cells as well as primary lymphoma cells being achieved with an adenoviral vector system encoding the beta-galactosidase protein. At a multiplicity of infection of 200, up to 100% of Daudi cells and Raji cells and 70% of OCI-Ly8-LAM53 cells could be transfected. Even at high adenoviral concentrations, no marked toxicity was observed, and the growth characteristics of the lymphoma cell lines were not impaired. The transfection rates in primary cells derived from six patients with non-Hodgkin's lymphoma were 30-65%, respectively. Transfection efficiency could be further increased by addition of cationic liposomes to adenoviral gene transfer. Furthermore, we examined the expression of the Coxsackie-adenoviral receptor (CAR) and the integrin receptors on the lymphoma cell surface. Flow cytometric analysis showed that 88% of Daudi cells, 69% of Raji cells, and 6% of OCI-Ly8-LAM53 cells expressed CAR on the cell surface. According to our data, adenoviral infection of lymphoma cells seems to be mediated by CAR. In contrast, integrin receptors are unlikely to play a major role, because lymphoma cells were negative for alphavbeta3-integrins and negative for alphavbeta5-integrins. In conclusion, this study demonstrates that B-lymphoma cell lines and

  10. In vitro study for laser gene transfer in BHK-21 fibroblast cell line

    Science.gov (United States)

    Abdel Aziz, M.; Salem, D. S.; Salama, M. S.; Badr, Y.

    2009-02-01

    Modifications to our previously introduced system for laser microbeam cell surgery were carried out in the present work to match animal cells. These modifications included: 1- Using other laser system that used before, Excimer laser with 193 and 308 nm wavelengths. The used laser here, is He-Cd with low power and 441.5 nm wavelength in the visible region. 2- Instead of using pulsed laser, we used here CW He-Cd chopped by electrical chopper, which is synchronized with the mechanical motion of the mobile stage with step 40 microns, according to cell dimensions to avoid puncturing the same cell twice. The advantages of the modified here laser setup for gene transfer is: it is less damaging to the sensitive animal cell which has thin cell membrane. The present work aimed to: 1- Design a modified laser microbeam cell surgery, applicable to animal cells, such as fibroblast cells 2- To examine the efficiency of such system. 3- To assure gene transfer and its expression in the used cells. 4- To evaluate the ultra damages produced from using the laser beam as a modality for gene transfer. On the other wards, to introduce: safe, efficient and less damaging modality for gene transfer in animal cells. To achieve these goals, we applied the introduced here home-made laser setup with its synchronized parameters to introduce pBK-CMV phagemid, containing LacZ and neomycin resistance (neor )genes into BHK-21 fibroblast cell line. The results of the present work showed that: 1- Our modified laser microbeam cell surgery setup proved to be useful and efficient tool for gene transfer into fibroblast cells. 2- The presence and expression of LacZ gene was achieved using histochemical LacZ assay. 3- Selection of G418 antibiotic sensitivity assay confirmed the presence and expression towards stability of neor gene with time. 4- Presence of LacZ and neor genes in the genomic DNA of transfected fibroblast cells was indicated using PCR analysis. 5- Transmission electron microscopy indicated

  11. Homologous recombination mediates functional recovery of dysferlin deficiency following AAV5 gene transfer.

    Directory of Open Access Journals (Sweden)

    William E Grose

    Full Text Available The dysferlinopathies comprise a group of untreatable muscle disorders including limb girdle muscular dystrophy type 2B, Miyoshi myopathy, distal anterior compartment syndrome, and rigid spine syndrome. As with other forms of muscular dystrophy, adeno-associated virus (AAV gene transfer is a particularly auspicious treatment strategy, however the size of the DYSF cDNA (6.5 kb negates packaging into traditional AAV serotypes known to express well in muscle (i.e. rAAV1, 2, 6, 8, 9. Potential advantages of a full cDNA versus a mini-gene include: maintaining structural-functional protein domains, evading protein misfolding, and avoiding novel epitopes that could be immunogenic. AAV5 has demonstrated unique plasticity with regards to packaging capacity and recombination of virions containing homologous regions of cDNA inserts has been implicated in the generation of full-length transcripts. Herein we show for the first time in vivo that homologous recombination following AAV5.DYSF gene transfer leads to the production of full length transcript and protein. Moreover, gene transfer of full-length dysferlin protein in dysferlin deficient mice resulted in expression levels sufficient to correct functional deficits in the diaphragm and importantly in skeletal muscle membrane repair. Intravascular regional gene transfer through the femoral artery produced high levels of transduction and enabled targeting of specific muscle groups affected by the dysferlinopathies setting the stage for potential translation to clinical trials. We provide proof of principle that AAV5 mediated delivery of dysferlin is a highly promising strategy for treatment of dysferlinopathies and has far-reaching implications for the therapeutic delivery of other large genes.

  12. Mining the bitter melon (momordica charantia l.) seed transcriptome by 454 analysis of non-normalized and normalized cDNA populations for conjugated fatty acid metabolism-related genes

    Science.gov (United States)

    Seeds of Momordica charantia (bitter melon) produce high levels of eleostearic acid, an unusual conjugated fatty acid with industrial value. Deep sequencing of non-normalized and normalized cDNAs from developing bitter melon seeds was conducted to uncover key genes required for biotechnological tran...

  13. Efficient procedure for transferring specific human genes into Chinese hamster cell mutants: interspecific transfer of the human genes encoding leucyl- and asparaginyl-tRNA synthetases

    International Nuclear Information System (INIS)

    Cirullo, R.E.; Dana, S.; Wasmuth, J.J.

    1983-01-01

    A simple and efficient procedure for transferring specific human genes into mutant Chinese hamster ovary cell recipients has been developed that does not rely on using calcium phosphate-precipitated high-molecular-weight DNA. Interspecific cell hybrids between human leukocytes and temperature-sensitive Chinese hamster cell mutants with either a thermolabile leucyl-tRNA synthetase or a thermolabile asparaginyl-tRNA synthetase were used as the starting material in these experiments. These hybrids contain only one or a few human chromosomes and require expression of the appropriate human aminoacyl-tRNA synthetase gene to grow at 39 degrees C. Hybrids were exposed to very high doses of gamma-irradiation to extensively fragment the chromosomes and re-fused immediately to the original temperature-sensitive Chinese hamster mutant, and secondary hybrids were isolated at 39 degrees C. Secondary hybrids, which had retained small fragments of the human genome containing the selected gene, were subjected to another round of irradiation, refusion, and selection at 39 degrees C to reduce the amount of human DNA even further. Using this procedure, Chinese hamster cell lines have been constructed that express the human genes encoding either asparaginyl- or leucyl-tRNA synthetase, yet less than 0.1% of their DNA is derived from the human genome, as quantitated by a sensitive dot-blot nucleic acid hybridization procedure

  14. Interferon-β gene transfer induces a strong cytotoxic bystander effect on melanoma cells.

    Science.gov (United States)

    Rossi, Úrsula A; Gil-Cardeza, María L; Villaverde, Marcela S; Finocchiaro, Liliana M E; Glikin, Gerardo C

    2015-05-01

    A local gene therapy scheme for the delivery of type I interferons could be an alternative for the treatment of melanoma. We evaluated the cytotoxic effects of interferon-β (IFNβ) gene lipofection on tumor cell lines derived from three human cutaneous and four canine mucosal melanomas. The cytotoxicity of human IFNβ gene lipofection resulted higher or equivalent to that of the corresponding addition of the recombinant protein (rhIFNβ) to human cells. IFNβ gene lipofection was not cytotoxic for only one canine melanoma cell line. When cultured as monolayers, three human and three canine IFNβ-lipofected melanoma cell lines displayed a remarkable bystander effect. As spheroids, the same six cell lines were sensitive to IFNβ gene transfer, two displaying a significant multicell resistance phenotype. The effects of conditioned IFNβ-lipofected canine melanoma cell culture media suggested the release of at least one soluble thermolabile cytotoxic factor that could not be detected in human melanoma cells. By using a secretion signal-free truncated human IFNβ, we showed that its intracellular expression was enough to induce cytotoxicity in two human melanoma cell lines. The lower cytoplasmatic levels of reactive oxygen species detected after intracellular IFNβ expression could be related to the resistance displayed by one human melanoma cell line. As IFNβ gene transfer was effective against most of the assayed melanomas in a way not limited by relatively low lipofection efficiencies, the clinical potential of this approach is strongly supported. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  15. Targeted disruption of Ataxia-telangiectasia mutated gene in miniature pigs by somatic cell nuclear transfer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young June; Ahn, Kwang Sung; Kim, Minjeong; Kim, Min Ju; Park, Sang-Min; Ryu, Junghyun; Ahn, Jin Seop; Heo, Soon Young; Kang, Jee Hyun; Choi, You Jung [Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan (Korea, Republic of); Choi, Seong-Jun [Institute of Tissue Regeneration Engineering, Dankook University, Cheonan (Korea, Republic of); Shim, Hosup, E-mail: shim@dku.edu [Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan (Korea, Republic of); Institute of Tissue Regeneration Engineering, Dankook University, Cheonan (Korea, Republic of); Department of Physiology, Dankook University School of Medicine, Cheonan (Korea, Republic of)

    2014-10-03

    Highlights: • ATM gene-targeted pigs were produced by somatic cell nuclear transfer. • A novel large animal model for ataxia telangiectasia was developed. • The new model may provide an alternative to the mouse model. - Abstract: Ataxia telangiectasia (A-T) is a recessive autosomal disorder associated with pleiotropic phenotypes, including progressive cerebellar degeneration, gonad atrophy, and growth retardation. Even though A-T is known to be caused by the mutations in the Ataxia telangiectasia mutated (ATM) gene, the correlation between abnormal cellular physiology caused by ATM mutations and the multiple symptoms of A-T disease has not been clearly determined. None of the existing ATM mouse models properly reflects the extent to which neurological degeneration occurs in human. In an attempt to provide a large animal model for A-T, we produced gene-targeted pigs with mutations in the ATM gene by somatic cell nuclear transfer. The disrupted allele in the ATM gene of cloned piglets was confirmed via PCR and Southern blot analysis. The ATM gene-targeted pigs generated in the present study may provide an alternative to the current mouse model for the study of mechanisms underlying A-T disorder and for the development of new therapies.

  16. An adenovirus vector incorporating carbohydrate binding domains utilizes glycans for gene transfer.

    Directory of Open Access Journals (Sweden)

    Julius W Kim

    Full Text Available Vectors based on human adenovirus serotype 5 (HAdV-5 continue to show promise as delivery vehicles for cancer gene therapy. Nevertheless, it has become clear that therapeutic benefit is directly linked to tumor-specific vector localization, highlighting the need for tumor-targeted gene delivery. Aberrant glycosylation of cell surface glycoproteins and glycolipids is a central feature of malignant transformation, and tumor-associated glycoforms are recognized as cancer biomarkers. On this basis, we hypothesized that cancer-specific cell-surface glycans could be the basis of a novel paradigm in HAdV-5-based vector targeting.As a first step toward this goal, we constructed a novel HAdV-5 vector encoding a unique chimeric fiber protein that contains the tandem carbohydrate binding domains of the fiber protein of the NADC-1 strain of porcine adenovirus type 4 (PAdV-4. This glycan-targeted vector displays augmented CAR-independent gene transfer in cells with low CAR expression. Further, we show that gene transfer is markedly decreased in cells with genetic glycosylation defects and by inhibitors of glycosylation in normal cells.These data provide the initial proof-of-concept for HAdV-5 vector-mediated gene delivery based on the presence of cell-surface carbohydrates. Further development of this new targeting paradigm could provide targeted gene delivery based on vector recognition of disease-specific glycan biomarkers.

  17. Targeted disruption of Ataxia-telangiectasia mutated gene in miniature pigs by somatic cell nuclear transfer

    International Nuclear Information System (INIS)

    Kim, Young June; Ahn, Kwang Sung; Kim, Minjeong; Kim, Min Ju; Park, Sang-Min; Ryu, Junghyun; Ahn, Jin Seop; Heo, Soon Young; Kang, Jee Hyun; Choi, You Jung; Choi, Seong-Jun; Shim, Hosup

    2014-01-01

    Highlights: • ATM gene-targeted pigs were produced by somatic cell nuclear transfer. • A novel large animal model for ataxia telangiectasia was developed. • The new model may provide an alternative to the mouse model. - Abstract: Ataxia telangiectasia (A-T) is a recessive autosomal disorder associated with pleiotropic phenotypes, including progressive cerebellar degeneration, gonad atrophy, and growth retardation. Even though A-T is known to be caused by the mutations in the Ataxia telangiectasia mutated (ATM) gene, the correlation between abnormal cellular physiology caused by ATM mutations and the multiple symptoms of A-T disease has not been clearly determined. None of the existing ATM mouse models properly reflects the extent to which neurological degeneration occurs in human. In an attempt to provide a large animal model for A-T, we produced gene-targeted pigs with mutations in the ATM gene by somatic cell nuclear transfer. The disrupted allele in the ATM gene of cloned piglets was confirmed via PCR and Southern blot analysis. The ATM gene-targeted pigs generated in the present study may provide an alternative to the current mouse model for the study of mechanisms underlying A-T disorder and for the development of new therapies

  18. Ionizing and ultraviolet radiation enhances the efficiency of DNA mediated gene transfer in vitro

    International Nuclear Information System (INIS)

    Perez, C.F.

    1984-08-01

    The enhancement effects of ionizing and non-ionizing radiation on the efficiency of DNA mediated gene transfer were studied. Confluent Rat-2 cells were transfected with purified SV40 viral DNA, irradiated with either X-rays or ultraviolet, trypsinized, plated, and assayed for the formation of foci on Rat-2 monolayers. Both ionizing and ultraviolet radiation enhanced the frequency of A-gene transformants/survivor compared to unirradiated transfected cells. These enhancements were non-linear and dose dependent. A recombinant plasmid, pOT-TK5, was constructed that contained the SV40 virus A-gene and the Herpes Simplex virus (HSV) thymidine kinase (TK) gene. Confluent Rat-2 cells transfected with pOT-TK5 DNA and then immediately irradiated with either X-rays or 330 MeV/amu argon particles at the Berkeley Bevalac showed a higher frequency of HAT + colonies/survivor than unirradiated transfected cells. Rat-2 cells transfected with the plasmid, pTK2, containing only the HSV TK-gene were enhanced for TK-transformation by both X-rays and ultraviolet radiation. The results demonstrate that radiation enhancement of the efficiency of DNA mediated gene transfer is not explained by increased nuclear uptake of the transfected DNA. Radiation increases the competence of the transfected cell population for genetic transformation. Three models for this increased competence are presented. The targeted integration model, the inducible recombination model, the partition model, and the utilization of DNA mediated gene transfer for DNA repair studies are discussed. 465 references

  19. Ionizing and ultraviolet radiation enhances the efficiency of DNA mediated gene transfer in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Perez, C.F.

    1984-08-01

    The enhancement effects of ionizing and non-ionizing radiation on the efficiency of DNA mediated gene transfer were studied. Confluent Rat-2 cells were transfected with purified SV40 viral DNA, irradiated with either X-rays or ultraviolet, trypsinized, plated, and assayed for the formation of foci on Rat-2 monolayers. Both ionizing and ultraviolet radiation enhanced the frequency of A-gene transformants/survivor compared to unirradiated transfected cells. These enhancements were non-linear and dose dependent. A recombinant plasmid, pOT-TK5, was constructed that contained the SV40 virus A-gene and the Herpes Simplex virus (HSV) thymidine kinase (TK) gene. Confluent Rat-2 cells transfected with pOT-TK5 DNA and then immediately irradiated with either X-rays or 330 MeV/amu argon particles at the Berkeley Bevalac showed a higher frequency of HAT/sup +/ colonies/survivor than unirradiated transfected cells. Rat-2 cells transfected with the plasmid, pTK2, containing only the HSV TK-gene were enhanced for TK-transformation by both X-rays and ultraviolet radiation. The results demonstrate that radiation enhancement of the efficiency of DNA mediated gene transfer is not explained by increased nuclear uptake of the transfected DNA. Radiation increases the competence of the transfected cell population for genetic transformation. Three models for this increased competence are presented. The targeted integration model, the inducible recombination model, the partition model, and the utilization of DNA mediated gene transfer for DNA repair studies are discussed. 465 references.

  20. Technology transfer

    International Nuclear Information System (INIS)

    1998-01-01

    On the base of technological opportunities and of the environmental target of the various sectors of energy system this paper intend to conjugate the opportunity/objective with economic and social development through technology transfer and information dissemination [it

  1. Phylogenetic inference in Rafflesiales: the influence of rate heterogeneity and horizontal gene transfer

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    Vidal-Russell Romina

    2004-10-01

    Full Text Available Abstract Background The phylogenetic relationships among the holoparasites of Rafflesiales have remained enigmatic for over a century. Recent molecular phylogenetic studies using the mitochondrial matR gene placed Rafflesia, Rhizanthes and Sapria (Rafflesiaceae s. str. in the angiosperm order Malpighiales and Mitrastema (Mitrastemonaceae in Ericales. These phylogenetic studies did not, however, sample two additional groups traditionally classified within Rafflesiales (Apodantheaceae and Cytinaceae. Here we provide molecular phylogenetic evidence using DNA sequence data from mitochondrial and nuclear genes for representatives of all genera in Rafflesiales. Results Our analyses indicate that the phylogenetic affinities of the large-flowered clade and Mitrastema, ascertained using mitochondrial matR, are congruent with results from nuclear SSU rDNA when these data are analyzed using maximum likelihood and Bayesian methods. The relationship of Cytinaceae to Malvales was recovered in all analyses. Relationships between Apodanthaceae and photosynthetic angiosperms varied depending upon the data partition: Malvales (3-gene, Cucurbitales (matR or Fabales (atp1. The latter incongruencies suggest that horizontal gene transfer (HGT may be affecting the mitochondrial gene topologies. The lack of association between Mitrastema and Ericales using atp1 is suggestive of HGT, but greater sampling within eudicots is needed to test this hypothesis further. Conclusions Rafflesiales are not monophyletic but composed of three or four independent lineages (families: Rafflesiaceae, Mitrastemonaceae, Apodanthaceae and Cytinaceae. Long-branch attraction appears to be misleading parsimony analyses of nuclear small-subunit rDNA data, but model-based methods (maximum likelihood and Bayesian analyses recover a topology that is congruent with the mitochondrial matR gene tree, thus providing compelling evidence for organismal relationships. Horizontal gene transfer appears to

  2. Adaptations to High Salt in a Halophilic Protist: Differential Expression and Gene Acquisitions through Duplications and Gene Transfers

    Science.gov (United States)

    Harding, Tommy; Roger, Andrew J.; Simpson, Alastair G. B.

    2017-01-01

    The capacity of halophiles to thrive in extreme hypersaline habitats derives partly from the tight regulation of ion homeostasis, the salt-dependent adjustment of plasma membrane fluidity, and the increased capability to manage oxidative stress. Halophilic bacteria, and archaea have been intensively studied, and substantial research has been conducted on halophilic fungi, and the green alga Dunaliella. By contrast, there have been very few investigations of halophiles that are phagotrophic protists, i.e., protozoa. To gather fundamental knowledge about salt adaptation in these organisms, we studied the transcriptome-level response of Halocafeteria seosinensis (Stramenopiles) grown under contrasting salinities. We provided further evolutionary context to our analysis by identifying genes that underwent recent duplications. Genes that were highly responsive to salinity variations were involved in stress response (e.g., chaperones), ion homeostasis (e.g., Na+/H+ transporter), metabolism and transport of lipids (e.g., sterol biosynthetic genes), carbohydrate metabolism (e.g., glycosidases), and signal transduction pathways (e.g., transcription factors). A significantly high proportion (43%) of duplicated genes were also differentially expressed, accentuating the importance of gene expansion in adaptation by H. seosinensis to high salt environments. Furthermore, we found two genes that were lateral acquisitions from bacteria, and were also highly up-regulated and highly expressed at high salt, suggesting that this evolutionary mechanism could also have facilitated adaptation to high salt. We propose that a transition toward high-salt adaptation in the ancestors of H. seosinensis required the acquisition of new genes via duplication, and some lateral gene transfers (LGTs), as well as the alteration of transcriptional programs, leading to increased stress resistance, proper establishment of ion gradients, and modification of cell structure properties like membrane

  3. Sequence diversities of serine-aspartate repeat genes among Staphylococcus aureus isolates from different hosts presumably by horizontal gene transfer.

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    Huping Xue

    Full Text Available BACKGROUND: Horizontal gene transfer (HGT is recognized as one of the major forces for bacterial genome evolution. Many clinically important bacteria may acquire virulence factors and antibiotic resistance through HGT. The comparative genomic analysis has become an important tool for identifying HGT in emerging pathogens. In this study, the Serine-Aspartate Repeat (Sdr family has been compared among different sources of Staphylococcus aureus (S. aureus to discover sequence diversities within their genomes. METHODOLOGY/PRINCIPAL FINDINGS: Four sdr genes were analyzed for 21 different S. aureus strains and 218 mastitis-associated S. aureus isolates from Canada. Comparative genomic analyses revealed that S. aureus strains from bovine mastitis (RF122 and mastitis isolates in this study, ovine mastitis (ED133, pig (ST398, chicken (ED98, and human methicillin-resistant S. aureus (MRSA (TCH130, MRSA252, Mu3, Mu50, N315, 04-02981, JH1 and JH9 were highly associated with one another, presumably due to HGT. In addition, several types of insertion and deletion were found in sdr genes of many isolates. A new insertion sequence was found in mastitis isolates, which was presumably responsible for the HGT of sdrC gene among different strains. Moreover, the sdr genes could be used to type S. aureus. Regional difference of sdr genes distribution was also indicated among the tested S. aureus isolates. Finally, certain associations were found between sdr genes and subclinical or clinical mastitis isolates. CONCLUSIONS: Certain sdr gene sequences were shared in S. aureus strains and isolates from different species presumably due to HGT. Our results also suggest that the distributional assay of virulence factors should detect the full sequences or full functional regions of these factors. The traditional assay using short conserved regions may not be accurate or credible. These findings have important implications with regard to animal husbandry practices that may

  4. Adaptations to High Salt in a Halophilic Protist: Differential Expression and Gene Acquisitions through Duplications and Gene Transfers

    Directory of Open Access Journals (Sweden)

    Tommy Harding

    2017-05-01

    Full Text Available The capacity of halophiles to thrive in extreme hypersaline habitats derives partly from the tight regulation of ion homeostasis, the salt-dependent adjustment of plasma membrane fluidity, and the increased capability to manage oxidative stress. Halophilic bacteria, and archaea have been intensively studied, and substantial research has been conducted on halophilic fungi, and the green alga Dunaliella. By contrast, there have been very few investigations of halophiles that are phagotrophic protists, i.e., protozoa. To gather fundamental knowledge about salt adaptation in these organisms, we studied the transcriptome-level response of Halocafeteria seosinensis (Stramenopiles grown under contrasting salinities. We provided further evolutionary context to our analysis by identifying genes that underwent recent duplications. Genes that were highly responsive to salinity variations were involved in stress response (e.g., chaperones, ion homeostasis (e.g., Na+/H+ transporter, metabolism and transport of lipids (e.g., sterol biosynthetic genes, carbohydrate metabolism (e.g., glycosidases, and signal transduction pathways (e.g., transcription factors. A significantly high proportion (43% of duplicated genes were also differentially expressed, accentuating the importance of gene expansion in adaptation by H. seosinensis to high salt environments. Furthermore, we found two genes that were lateral acquisitions from bacteria, and were also highly up-regulated and highly expressed at high salt, suggesting that this evolutionary mechanism could also have facilitated adaptation to high salt. We propose that a transition toward high-salt adaptation in the ancestors of H. seosinensis required the acquisition of new genes via duplication, and some lateral gene transfers (LGTs, as well as the alteration of transcriptional programs, leading to increased stress resistance, proper establishment of ion gradients, and modification of cell structure properties like

  5. Gene transfer to primary corneal epithelial cells with an integrating lentiviral vector

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    Lauro Augusto de Oliveira

    2010-10-01

    Full Text Available PURPOSE: To evaluate the transfer of heterologous genes carrying a Green Fluorescent Protein (GFP reporter cassette to primary corneal epithelial cells ex vivo. METHODS: Freshly enucleated rabbit corneoscleral tissue was used to obtain corneal epithelial cell suspension via enzymatic digestion. Cells were plated at a density of 5×10³ cells/cm² and allowed to grow for 5 days (to 70-80% confluency prior to transduction. Gene transfer was monitored using fluorescence microscopy and fluorescence activated cell sorter (FACS. We evaluated the transduction efficiency (TE over time and the dose-response effect of different lentiviral particles. One set of cells were dual sorted by fluorescence activated cell sorter for green fluorescent protein expression as well as Hoechst dye exclusion to evaluate the transduction of potentially corneal epithelial stem cells (side-population phenotypic cells. RESULTS: Green fluorescent protein expressing lentiviral vectors were able to effectively transduce rabbit primary epithelial cells cultured ex vivo. Live cell imaging post-transduction demonstrated GFP-positive cells with normal epithelial cell morphology and growth. The transduction efficiency over time was higher at the 5th post-transduction day (14.1% and tended to stabilize after the 8th day. The number of transduced cells was dose-dependent, and at the highest lentivirus concentrations approached 7%. When double sorted by fluorescence activated cell sorter to isolate both green fluorescent protein positive and side population cells, transduced side population cells were identified. CONCLUSIONS: Lentiviral vectors can effectively transfer heterologous genes to primary corneal epithelial cells expanded ex vivo. Genes were stably expressed over time, transferred in a dose-dependence fashion, and could be transferred to mature corneal cells as well as presumable putative stem cells.

  6. Updated clusters of orthologous genes for Archaea: a complex ancestor of the Archaea and the byways of horizontal gene transfer

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    Wolf Yuri I

    2012-12-01

    Full Text Available Abstract Background Collections of Clusters of Orthologous Genes (COGs provide indispensable tools for comparative genomic analysis, evolutionary reconstruction and functional annotation of new genomes. Initially, COGs were made for all complete genomes of cellular life forms that were available at the time. However, with the accumulation of thousands of complete genomes, construction of a comprehensive COG set has become extremely computationally demanding and prone to error propagation, necessitating the switch to taxon-specific COG collections. Previously, we reported the collection of COGs for 41 genomes of Archaea (arCOGs. Here we present a major update of the arCOGs and describe evolutionary reconstructions to reveal general trends in the evolution of Archaea. Results The updated version of the arCOG database incorporates 91% of the pangenome of 120 archaea (251,032 protein-coding genes altogether into 10,335 arCOGs. Using this new set of arCOGs, we performed maximum likelihood reconstruction of the genome content of archaeal ancestral forms and gene gain and loss events in archaeal evolution. This reconstruction shows that the last Common Ancestor of the extant Archaea was an organism of greater complexity than most of the extant archaea, probably with over 2,500 protein-coding genes. The subsequent evolution of almost all archaeal lineages was apparently dominated by gene loss resulting in genome streamlining. Overall, in the evolution of Archaea as well as a representative set of bacteria that was similarly analyzed for comparison, gene losses are estimated to outnumber gene gains at least 4 to 1. Analysis of specific patterns of gene gain in Archaea shows that, although some groups, in particular Halobacteria, acquire substantially more genes than others, on the whole, gene exchange between major groups of Archaea appears to be largely random, with no major ‘highways’ of horizontal gene transfer. Conclusions The updated collection

  7. Efficient gene transfer into nondividing cells by adeno-associated virus-based vectors.

    Science.gov (United States)

    Podsakoff, G; Wong, K K; Chatterjee, S

    1994-09-01

    Gene transfer vectors based on adeno-associated virus (AAV) are emerging as highly promising for use in human gene therapy by virtue of their characteristics of wide host range, high transduction efficiencies, and lack of cytopathogenicity. To better define the biology of AAV-mediated gene transfer, we tested the ability of an AAV vector to efficiently introduce transgenes into nonproliferating cell populations. Cells were induced into a nonproliferative state by treatment with the DNA synthesis inhibitors fluorodeoxyuridine and aphidicolin or by contact inhibition induced by confluence and serum starvation. Cells in logarithmic growth or DNA synthesis arrest were transduced with vCWR:beta gal, an AAV-based vector encoding beta-galactosidase under Rous sarcoma virus long terminal repeat promoter control. Under each condition tested, vCWR:beta Gal expression in nondividing cells was at least equivalent to that in actively proliferating cells, suggesting that mechanisms for virus attachment, nuclear transport, virion uncoating, and perhaps some limited second-strand synthesis of AAV vectors were present in nondividing cells. Southern hybridization analysis of vector sequences from cells transduced while in DNA synthetic arrest and expanded after release of the block confirmed ultimate integration of the vector genome into cellular chromosomal DNA. These findings may provide the basis for the use of AAV-based vectors for gene transfer into quiescent cell populations such as totipotent hematopoietic stem cells.

  8. Evidence of recent interkingdom horizontal gene transfer between bacteria and Candida parapsilosis

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    Butler Geraldine

    2008-06-01

    Full Text Available Abstract Background To date very few incidences of interdomain gene transfer into fungi have been identified. Here, we used the emerging genome sequences of Candida albicans WO-1, Candida tropicalis, Candida parapsilosis, Clavispora lusitaniae, Pichia guilliermondii, and Lodderomyces elongisporus to identify recent interdomain HGT events. We refer to these as CTG species because they translate the CTG codon as serine rather than leucine, and share a recent common ancestor. Results Phylogenetic and syntenic information infer that two C. parapsilosis genes originate from bacterial sources. One encodes a putative proline racemase (PR. Phylogenetic analysis also infers that there were independent transfers of bacterial PR enzymes into members of the Pezizomycotina, and protists. The second HGT gene in C. parapsilosis belongs to the phenazine F (PhzF superfamily. Most CTG species also contain a fungal PhzF homolog. Our phylogeny suggests that the CTG homolog originated from an ancient HGT event, from a member of the proteobacteria. An analysis of synteny suggests that C. parapsilosis has lost the endogenous fungal form of PhzF, and subsequently reacquired it from a proteobacterial source. There is evidence that Schizosaccharomyces pombe and Basidiomycotina also obtained a PhzF homolog through HGT. Conclusion Our search revealed two instances of well-supported HGT from bacteria into the CTG clade, both specific to C. parapsilosis. Therefore, while recent interkingdom gene transfer has taken place in the CTG lineage, its occurrence is rare. However, our analysis will not detect ancient gene transfers, and we may have underestimated the global extent of HGT into CTG species.

  9. RNA interference screen to identify pathways that enhance or reduce nonviral gene transfer during lipofection.

    Science.gov (United States)

    Barker, Gregory A; Diamond, Scott L

    2008-09-01

    Some barriers to DNA lipofection are well characterized; however, there is as yet no method of finding unknown pathways that impact the process. A druggable genome small-interfering RNA (siRNA) screen against 5,520 genes was tested for its effect on lipofection of human aortic endothelial cells (HAECs). We found 130 gene targets which, when silenced by pooled siRNAs (three siRNAs per gene), resulted in enhanced luminescence after lipofection (86 gene targets showed reduced expression). In confirmation tests with single siRNAs, 18 of the 130 hits showed enhanced lipofection with two or more individual siRNAs in the absence of cytotoxicity. Of these confirmed gene targets, we identified five leading candidates, two of which are isoforms of the regulatory subunit of protein phosphatase 2A (PP2A). The best candidate siRNA targeted the PPP2R2C gene and produced a 65% increase in luminescence from lipofection, with a quantitative PCR-validated knockdown of approximately 76%. Flow cytometric analysis confirmed that the silencing of the PPP2R2C gene resulted in an improvement of 10% in transfection efficiency, thereby demonstrating an increase in the number of transfected cells. These results show that an RNA interference (RNAi) high-throughput screen (HTS) can be applied to nonviral gene transfer. We have also demonstrated that siRNAs can be co-delivered with lipofected DNA to increase the transfection efficiency in vitro.

  10. A Preliminary List of Horizontally Transferred Genes in Prokaryotes Determined by Tree Reconstruction and Reconciliation

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    Hyeonsoo Jeong

    2017-08-01

    Full Text Available Genome-wide global detection of genes involved in horizontal gene transfer (HGT remains an active area of research in medical microbiology and evolutionary genomics. Utilizing the explicit evolutionary method of comparing topologies of a total of 154,805 orthologous gene trees against corresponding 16S rRNA “reference” trees, we previously detected a total of 660,894 candidate HGT events in 2,472 completely-sequenced prokaryotic genomes. Here, we report an HGT-index for each individual gene-reference tree pair reconciliation, representing the total number of detected HGT events on the gene tree divided by the total number of genomes (taxa member of that tree. HGT-index is thus a simple measure indicating the sensitivity of prokaryotic genes to participate (or not participate in HGT. Our preliminary list provides HGT-indices for a total of 69,365 genes (detected in >10 and <50% available prokaryotic genomes that are involved in a wide range of biological processes such as metabolism, information, and bacterial response to environment. Identification of horizontally-derived genes is important to combat antibiotic resistance and is a step forward toward reconstructions of improved phylogenies describing the history of life. Our effort is thus expected to benefit ongoing research in the fields of clinical microbiology and evolutionary biology.

  11. The Bacillus subtilis Conjugative Plasmid pLS20 Encodes Two Ribbon-Helix-Helix Type Auxiliary Relaxosome Proteins That Are Essential for Conjugation.

    Science.gov (United States)

    Miguel-Arribas, Andrés; Hao, Jian-An; Luque-Ortega, Juan R; Ramachandran, Gayetri; Val-Calvo, Jorge; Gago-Córdoba, César; González-Álvarez, Daniel; Abia, David; Alfonso, Carlos; Wu, Ling J; Meijer, Wilfried J J

    2017-01-01

    Bacterial conjugation is the process by which a conjugative element (CE) is transferred horizontally from a donor to a recipient cell via a connecting pore. One of the first steps in the conjugation process is the formation of a nucleoprotein complex at the origin of transfer ( oriT ), where one of the components of the nucleoprotein complex, the relaxase, introduces a site- and strand specific nick to initiate the transfer of a single DNA strand into the recipient cell. In most cases, the nucleoprotein complex involves, besides the relaxase, one or more additional proteins, named auxiliary proteins, which are encoded by the CE and/or the host. The conjugative plasmid pLS20 replicates in the Gram-positive Firmicute bacterium Bacillus subtilis . We have recently identified the relaxase gene and the oriT of pLS20, which are separated by a region of almost 1 kb. Here we show that this region contains two auxiliary genes that we name aux1 LS20 and aux2 LS20 , and which we show are essential for conjugation. Both Aux1 LS20 and Aux2 LS20 are predicted to contain a Ribbon-Helix-Helix DNA binding motif near their N-terminus. Analyses of the purified proteins show that Aux1 LS20 and Aux2 LS20 form tetramers and hexamers in solution, respectively, and that they both bind preferentially to oriT LS20 , although with different characteristics and specificities. In silico analyses revealed that genes encoding homologs of Aux1 LS20 and/or Aux2 LS20 are located upstream of almost 400 relaxase genes of the Rel LS20 family (MOB L ) of relaxases. Thus, Aux1 LS20 and Aux2 LS20 of pLS20 constitute the founding member of the first two families of auxiliary proteins described for CEs of Gram-positive origin.

  12. The Bacillus subtilis Conjugative Plasmid pLS20 Encodes Two Ribbon-Helix-Helix Type Auxiliary Relaxosome Proteins That Are Essential for Conjugation

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    Andrés Miguel-Arribas

    2017-11-01

    Full Text Available Bacterial conjugation is the process by which a conjugative element (CE is transferred horizontally from a donor to a recipient cell via a connecting pore. One of the first steps in the conjugation process is the formation of a nucleoprotein complex at the origin of transfer (oriT, where one of the components of the nucleoprotein complex, the relaxase, introduces a site- and strand specific nick to initiate the transfer of a single DNA strand into the recipient cell. In most cases, the nucleoprotein complex involves, besides the relaxase, one or more additional proteins, named auxiliary proteins, which are encoded by the CE and/or the host. The conjugative plasmid pLS20 replicates in the Gram-positive Firmicute bacterium Bacillus subtilis. We have recently identified the relaxase gene and the oriT of pLS20, which are separated by a region of almost 1 kb. Here we show that this region contains two auxiliary genes that we name aux1LS20 and aux2LS20, and which we show are essential for conjugation. Both Aux1LS20 and Aux2LS20 are predicted to contain a Ribbon-Helix-Helix DNA binding motif near their N-terminus. Analyses of the purified proteins show that Aux1LS20 and Aux2LS20 form tetramers and hexamers in solution, respectively, and that they both bind preferentially to oriTLS20, although with different characteristics and specificities. In silico analyses revealed that genes encoding homologs of Aux1LS20 and/or Aux2LS20 are located upstream of almost 400 relaxase genes of the RelLS20 family (MOBL of relaxases. Thus, Aux1LS20 and Aux2LS20 of pLS20 constitute the founding member of the first two families of auxiliary proteins described for CEs of Gram-positive origin.

  13. Androgen Receptor Antagonism By Divalent Ethisterone Conjugates In Castrate-Resistant Prostate Cancer Cells

    Science.gov (United States)

    Levine, Paul M.; Lee, Eugine; Greenfield, Alex; Bonneau, Richard; Logan, Susan K.; Garabedian, Michael J.; Kirshenbaum, Kent

    2013-01-01

    Sustained treatment of prostate cancer with Androgen Receptor (AR) antagonists can evoke drug resistance, leading to castrate-resistant disease. Elevated activity of the AR is often associated with this highly aggressive disease state. Therefore, new therapeutic regimens that target and modulate AR activity could prove beneficial. We previously introduced a versatile chemical platform to generate competitive and non-competitive multivalent peptoid oligomer conjugates that modulate AR activity. In particular, we identified a linear and a cyclic divalent ethisterone conjugate that exhibit potent anti-proliferative properties in LNCaP-abl cells, a model of castrate-resistant prostate cancer. Here, we characterize the mechanism of action of these compounds utilizing confocal microscopy, time-resolved fluorescence resonance energy transfer, chromatin immunoprecipitation, flow cytometry, and microarray analysis. The linear conjugate competitively blocks AR action by inhibiting DNA binding. In addition, the linear conjugate does not promote AR nuclear localization or co-activator binding. In contrast, the cyclic conjugate promotes AR nuclear localization and induces cell-cycle arrest, despite its inability to compete against endogenous ligand for binding to AR in vitro. Genome-wide expression analysis reveals that gene transcripts are differentially affected by treatment with the linear or cyclic conjugate. Although the divalent ethisterone conjugates share extensive chemical similarities, we illustrate that they can antagonize the AR via distinct mechanisms of action, establishing new therapeutic strategies for potential applications in AR pharmacology. PMID:22871957

  14. Eliminating HIV-1 Packaging Sequences from Lentiviral Vector Proviruses Enhances Safety and Expedites Gene Transfer for Gene Therapy.

    Science.gov (United States)

    Vink, Conrad A; Counsell, John R; Perocheau, Dany P; Karda, Rajvinder; Buckley, Suzanne M K; Brugman, Martijn H; Galla, Melanie; Schambach, Axel; McKay, Tristan R; Waddington, Simon N; Howe, Steven J

    2017-08-02

    Lentiviral vector genomic RNA requires sequences that partially overlap wild-type HIV-1 gag and env genes for packaging into vector particles. These HIV-1 packaging sequences constitute 19.6% of the wild-type HIV-1 genome and contain functional cis elements that potentially compromise clinical safety. Here, we describe the development of a novel lentiviral vector (LTR1) with a unique genomic structure designed to prevent transfer of HIV-1 packaging sequences to patient cells, thus reducing the total HIV-1 content to just 4.8% of the wild-type genome. This has been achieved by reconfiguring the vector to mediate reverse-transcription with a single strand transfer, instead of the usual two, and in which HIV-1 packaging sequences are not copied. We show that LTR1 vectors offer improved safety in their resistance to remobilization in HIV-1 particles and reduced frequency of splicing into human genes. Following intravenous luciferase vector administration to neonatal mice, LTR1 sustained a higher level of liver transgene expression than an equivalent dose of a standard lentivirus. LTR1 vectors produce reverse-transcription products earlier and start to express transgenes significantly quicker than standard lentiviruses after transduction. Finally, we show that LTR1 is an effective lentiviral gene therapy vector as demonstrated by correction of a mouse hemophilia B model. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  15. Gene therapy: a lipofection approach for gene transfer into primary endothelial cells.

    Science.gov (United States)

    Young, A T L; Lakey, J R T; Murray, A G; Moore, R B

    2002-01-01

    Despite the great potential of gene therapy to become a new treatment modality in future medicine, there are still many limitations to overcome before this gene approach can pass to the stage of human trial. The foremost obstacle is the development of a safe, efficient, and efficacious vector system for in vivo gene application. This study evaluated the efficacy of lipofection as a gene delivery vehicle into primary endothelial cells. Transfection efficiency of several lipid-based reagents (Effectene, Fugene 6, DOTAP) was examined at experimental temperatures of 37 degrees C, 24 degrees C, and 6 degrees C. Human umbilical vein endothelial cells (HUVECs) were transfected with the enhanced green fluorescent protein (EGFP) using precise amounts of DNA (Effectene, 0.2 microg; Fugene 6, 0.5 microg; DOTAP, 2.5 microg) and lipids (Effectene, 10 microl; Fugene 6, 6 microl; DOTAP, 15 microl) optimized in our laboratory. Duration of incubation in the DNA/lipid transfection mixture varied for each lipid transfectant as follows: 5 h for both Fugene 6 and DOTAP and 3 h for Effectene. Efficiency of transfection was quantified by microscopic evaluation of EFGP expression in a minimum of 100 cells per group. Transfection efficiencies achieved with these lipofection agents were 34 +/- 1.3% (mean +/- SEM), 33 +/- 1.4%, and 18 +/- 1.5% for Effectene, Fugene 6, and DOTAP, respectively, at 37 degrees C. Transfection results were lower at 24 degrees C with mean efficiencies of 26 +/- 2.4% for Effectene, 14 +/- 2.9% for Fugene 6, and 15 +/- 3.2% for DOTAP. Furthermore, mean efficiencies at 6 degrees C were 6 +/- 0.5%, 8 +/- 1.5%, and 6 +/- 0.0% for Effectene, Fugene 6, and DOTAP, respectively. Efficiency of transfection appeared to be temperature dependent (ANOVA; p lipofection a potential gene delivery strategy for in vivo gene therapy.

  16. Phylogeographic reconstruction of a bacterial species with high levels of lateral gene transfer

    Science.gov (United States)

    Pearson, T.; Giffard, P.; Beckstrom-Sternberg, S.; Auerbach, R.; Hornstra, H.; Tuanyok, A.; Price, E.P.; Glass, M.B.; Leadem, B.; Beckstrom-Sternberg, J. S.; Allan, G.J.; Foster, J.T.; Wagner, D.M.; Okinaka, R.T.; Sim, S.H.; Pearson, O.; Wu, Z.; Chang, J.; Kaul, R.; Hoffmaster, A.R.; Brettin, T.S.; Robison, R.A.; Mayo, M.; Gee, J.E.; Tan, P.; Currie, B.J.; Keim, P.

    2009-01-01

    Background: Phylogeographic reconstruction of some bacterial populations is hindered by low diversity coupled with high levels of lateral gene transfer. A comparison of recombination levels and diversity at seven housekeeping genes for eleven bacterial species, most of which are commonly cited as having high levels of lateral gene transfer shows that the relative contributions of homologous recombination versus mutation for Burkholderia pseudomallei is over two times higher than for Streptococcus pneumoniae and is thus the highest value yet reported in bacteria. Despite the potential for homologous recombination to increase diversity, B. pseudomallei exhibits a relative lack of diversity at these loci. In these situations, whole genome genotyping of orthologous shared single nucleotide polymorphism loci, discovered using next generation sequencing technologies, can provide very large data sets capable of estimating core phylogenetic relationships. We compared and searched 43 whole genome sequences of B. pseudomallei and its closest relatives for single nucleotide polymorphisms in orthologous shared regions to use in phylogenetic reconstruction. Results: Bayesian phylogenetic analyses of >14,000 single nucleotide polymorphisms yielded completely resolved trees for these 43 strains with high levels of statistical support. These results enable a better understanding of a separate analysis of population differentiation among >1,700 B. pseudomallei isolates as defined by sequence data from seven housekeeping genes. We analyzed this larger data set for population structure and allele sharing that can be attributed to lateral gene transfer. Our results suggest that despite an almost panmictic population, we can detect two distinct populations of B. pseudomallei that conform to biogeographic patterns found in many plant and animal species. That is, separation along Wallace's Line, a biogeographic boundary between Southeast Asia and Australia. Conclusion: We describe an

  17. Phylogeographic reconstruction of a bacterial species with high levels of lateral gene transfer

    Directory of Open Access Journals (Sweden)

    Kaul Rajinder

    2009-11-01

    Full Text Available Abstract Background Phylogeographic reconstruction of some bacterial populations is hindered by low diversity coupled with high levels of lateral gene transfer. A comparison of recombination levels and diversity at seven housekeeping genes for eleven bacterial species, most of which are commonly cited as having high levels of lateral gene transfer shows that the relative contributions of homologous recombination versus mutation for Burkholderia pseudomallei is over two times higher than for Streptococcus pneumoniae and is thus the highest value yet reported in bacteria. Despite the potential for homologous recombination to increase diversity, B. pseudomallei exhibits a relative lack of diversity at these loci. In these situations, whole genome genotyping of orthologous shared single nucleotide polymorphism loci, discovered using next generation sequencing technologies, can provide very large data sets capable of estimating core phylogenetic relationships. We compared and searched 43 whole genome sequences of B. pseudomallei and its closest relatives for single nucleotide polymorphisms in orthologous shared regions to use in phylogenetic reconstruction. Results Bayesian phylogenetic analyses of >14,000 single nucleotide polymorphisms yielded completely resolved trees for these 43 strains with high levels of statistical support. These results enable a better understanding of a separate analysis of population differentiation among >1,700 B. pseudomallei isolates as defined by sequence data from seven housekeeping genes. We analyzed this larger data set for population structure and allele sharing that can be attributed to lateral gene transfer. Our results suggest that despite an almost panmictic population, we can detect two distinct populations of B. pseudomallei that conform to biogeographic patterns found in many plant and animal species. That is, separation along Wallace's Line, a biogeographic boundary between Southeast Asia and Australia

  18. Improved in vivo gene transfer into tumor tissue by stabilization of pseudodendritic oligoethylenimine-based polyplexes.

    Science.gov (United States)

    Russ, Verena; Fröhlich, Thomas; Li, Yunqiu; Halama, Anna; Ogris, Manfred; Wagner, Ernst

    2010-02-01

    HD O is a low molecular weight pseudodendrimer containing oligoethylenimine and degradable hexanediol diacrylate diesters. DNA polyplexes display encouraging gene transfer efficiency in vitro and in vivo but also a limited stability under physiological conditions. This limitation must be overcome for further development into more sophisticated formulations. HD O polyplexes were laterally stabilized by crosslinking surface amines via bifunctional crosslinkers, bioreducible dithiobis(succimidyl propionate) (DSP) or the nonreducible analog disuccinimidyl suberate (DSS). Optionally, in a subsequent step, the targeting ligand transferrin (Tf) was attached to DSP-linked HD O polyplexes via Schiff base formation between HD O amino groups and Tf aldehyde groups, which were introduced into Tf by periodate oxidation of the glycosylation sites. Crosslinked DNA polyplexes showed an increased stability against exchange reaction by salt or heparin. Disulfide bond containing DSP-linked polyplexes were susceptible to reducing conditions. These polyplexes displayed the highest gene expression levels in vitro and in vivo (upon intratumoral application in mice), and these were significantly elevated and prolonged over standard or DSS-stabilized HD O formulations. DSP-stabilized HD O polyplexes with or without Tf coating were well-tolerated after intravenous application. High gene expression levels were found in tumor tissue, with negligible gene expression in any other organ. Lateral stabilization of HD O polyplexes with DSP crosslinker enhanced gene transfer efficacy and was essential for the incorporation of a ligand (Tf) into a stable particle formulation.

  19. Correction of Fanconi Anemia Group C Hematopoietic Stem Cells Following Intrafemoral Gene Transfer

    Directory of Open Access Journals (Sweden)

    Ouassila Habi

    2010-01-01

    Full Text Available The main cause of morbidity and mortality in Fanconi anemia patients is the development of bone marrow (BM failure; thus correction of hematopoietic stem cells (HSCs through gene transfer approaches would benefit FA patients. However, gene therapy trials for FA patients using ex vivo transduction protocols have failed to provide long-term correction. In addition, ex vivo cultures have been found to be hazardous for FA cells. To circumvent negative effects of ex vivo culture in FA stem cells, we tested the corrective ability of direct injection of recombinant lentiviral particles encoding FancC-EGFP into femurs of FancC−/− mice. Using this approach, we show that FancC−/− HSCs were efficiently corrected. Intrafemoral gene transfer of the FancC gene prevented the mitomycin C-induced BM failure. Moreover, we show that intrafemoral gene delivery into aplastic marrow restored the bone marrow cellularity and corrected the remaining HSCs. These results provide evidence that targeting FA-deficient HSCs directly in their environment enables efficient and long-term correction of BM defects in FA.

  20. Retroviral-mediated gene transfer and expression of human phenylalanine hydroxylase in primary mouse hepatocytes

    Energy Technology Data Exchange (ETDEWEB)

    Peng, H.; Armentano, D.; Mackenzie-Graham, L.; Shen, R.F.; Darlington, G.; Ledley, F.D.; Woo, S.L.C. (Baylor College of Medicine, Houston, TX (USA))

    1988-11-01

    Genetic therapy for phenylketonuria (severe phenylalanine hydroxylase deficiency) may require introduction of a normal phenylalanine hydroxylase gene into hepatic cells of patients. The authors report development of a recombinant retrovirus based on the N2 vector for gene transfer and expression of human phenylalanine hydroxylase cDNA in primary mouse hepatocytes. This construct contains an internal promoter of the human {alpha}{sub 1}-antitrypsin gene driving transcription of the phenylalanine hydroxylase cDNA. Primary mouse hepatocytes were isolated from newborn mice, infected with the recombinant virus, and selected for expression of the neomycin-resistance gene. Hepatocytes transformed with the recombinant virus contained high levels of human phenylalanine hydroxylase mRNA transcripts originating from the retroviral and internal promoters. These results demonstrate that the transcriptional regulatory elements of the {alpha}{sub 1} antitrypsin gene retain their tissue-specific function in the recombinant provirus and establish a method for efficient transfer and high-level expression of human phenylalanine hydroxylase in primary hepatocytes.

  1. Retroviral-mediated gene transfer and expression of human phenylalanine hydroxylase in primary mouse hepatocytes

    International Nuclear Information System (INIS)

    Peng, H.; Armentano, D.; Mackenzie-Graham, L.; Shen, R.F.; Darlington, G.; Ledley, F.D.; Woo, S.L.C.

    1988-01-01

    Genetic therapy for phenylketonuria (severe phenylalanine hydroxylase deficiency) may require introduction of a normal phenylalanine hydroxylase gene into hepatic cells of patients. The authors report development of a recombinant retrovirus based on the N2 vector for gene transfer and expression of human phenylalanine hydroxylase cDNA in primary mouse hepatocytes. This construct contains an internal promoter of the human α 1 -antitrypsin gene driving transcription of the phenylalanine hydroxylase cDNA. Primary mouse hepatocytes were isolated from newborn mice, infected with the recombinant virus, and selected for expression of the neomycin-resistance gene. Hepatocytes transformed with the recombinant virus contained high levels of human phenylalanine hydroxylase mRNA transcripts originating from the retroviral and internal promoters. These results demonstrate that the transcriptional regulatory elements of the α 1 antitrypsin gene retain their tissue-specific function in the recombinant provirus and establish a method for efficient transfer and high-level expression of human phenylalanine hydroxylase in primary hepatocytes

  2. Gene therapy for barrett's esophagus: adenoviral gene transfer in different intestinal models

    NARCIS (Netherlands)

    Marsman, Willem A.; Buskens, Christianne J.; Wesseling, John G.; van Lanschot, J. Jan B.; Bosma, Piter J.

    2005-01-01

    Adenoviral gene therapy could potentially be used for treatment of patients with a Barrett's esophagus. In order to study the feasibility of this approach it is important to study adenoviral intestinal transduction both in vitro and in vivo. In the present study, we used differentiating Caco-2

  3. Enhanced Gene Transfer with Fusogenic Liposomes Containing Vesicular Stomatitis Virus G Glycoprotein

    Science.gov (United States)

    Abe, Akihiro; Miyanohara, Atsushi; Friedmann, Theodore

    1998-01-01

    Exposure of Lipofectin-DNA complexes to the partially purified G glycoprotein of the vesicular stomatitis virus envelope (VSV-G) results in loss of serum-mediated inhibition and in enhanced efficiency of gene transfer. Sucrose density gradient sedimentation analysis indicated that the VSV-G associates physically with the DNA-lipid complex to produce a VSV-G liposome. The ability to incorporate surrogate viral or cellular envelope components such as VSV-G into liposomes may allow more-efficient and possibly targeted gene delivery by lipofection, both in vitro and in vivo. PMID:9621082

  4. Status of therapeutic gene transfer to treat canine dilated cardiomyopathy in dogs.

    Science.gov (United States)

    Sleeper, Meg M; Bish, Lawrence T; Sweeney, H Lee

    2010-07-01

    Therapeutic gene transfer holds promise as a way to treat dilated cardiomyopathy from any underlying cause because the approach attempts to address metabolic disturbances that occur at the molecular level of the failing heart. Calcium-handling abnormalities and increased rates of apoptosis are abnormalities that occur in many types of heart disease, and gene therapies that target these metabolic defects have proven to be beneficial in numerous rodent models of heart disease. The authors are currently evaluating this approach to treat canine idiopathic dilated cardiomyopathy.

  5. The Extent and Regulation of Lateral Gene Transfer in Natural Microbial Ecosystems

    DEFF Research Database (Denmark)

    Aminov, Rustam I.

    2012-01-01

    of bacteria through lateral gene exchange is the history of antibiotic use by humans. Within a very brief period of the 'antibiotic era' many bacterial pathogens were able to acquire the mechanisms allowing them to withstand the selective pressure of antibiotics. And, finally, field and microcosm studies......The importance of horizontal gene transfer (HGT) in bacterial evolution is evident from the retrospective analyses of bacterial genomes, which suggest that a substantial part of bacterial genomes is of foreign origin. Another line of evidence that supports the possibility of rapid adaptation...

  6. Light-controlled inhibition of malignant glioma by opsin gene transfer

    Science.gov (United States)

    Yang, F; Tu, J; Pan, J-Q; Luo, H-L; Liu, Y-H; Wan, J; Zhang, J; Wei, P-F; Jiang, T; Chen, Y-H; Wang, L-P

    2013-01-01

    Glioblastomas are aggressive cancers with low survival rates and poor prognosis because of their highly proliferative and invasive capacity. In the current study, we describe a new optogenetic strategy that selectively inhibits glioma cells through light-controlled membrane depolarization and cell death. Transfer of the engineered opsin ChETA (engineered Channelrhodopsin-2 variant) gene into primary human glioma cells or cell lines, but not normal astrocytes, unexpectedly decreased cell proliferation and increased mitochondria-dependent apoptosis, upon light stimulation. These optogenetic effects were mediated by membrane depolarization-induced reductions in cyclin expression and mitochondrial transmembrane potential. Importantly, the ChETA gene transfer and light illumination in mice significantly inhibited subcutaneous and intracranial glioma growth and increased the survival of the animals bearing the glioma. These results uncover an unexpected effect of opsin ion channels on glioma cells and offer the opportunity for the first time to treat glioma using a light-controllable optogenetic approach. PMID:24176851

  7. Use of electroporation for high-molecular-weight DNA-mediated gene transfer.

    Science.gov (United States)

    Jastreboff, M M; Ito, E; Bertino, J R; Narayanan, R

    1987-08-01

    Electroporation was used to introduce high-molecular-weight DNA into murine hematopoietic cells and NIH3T3 cells. CCRF-CEM cells were stably transfected with SV2NEO plasmid and the genomic DNA from G-418-resistant clones (greater than 65 kb) was introduced into mouse bone marrow and NIH3T3 cells by electroporation. NEO sequences and expression were detected in the hematopoietic tissues of lethally irradiated mice, with 24% of individual spleen colonies expressing NEO. The frequency of genomic DNA transfer into NIH3T3 cells was 0.25 X 10(-3). Electroporation thus offers a powerful mode of gene transfer not only of cloned genes but also of high-molecular-weight DNA into cells.

  8. Glutaric acidemia type II: gene structure and mutations of the electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO) gene.

    Science.gov (United States)

    Goodman, Stephen I; Binard, Robert J; Woontner, Michael R; Frerman, Frank E

    2002-01-01

    Glutaric acidemia type II is a human inborn error of metabolism which can be due to defects in either subunit of electron transfer flavoprotein (ETF) or in ETF:ubiquinone oxidoreductase (ETF:QO), but few disease-causing mutations have been described. The ETF:QO gene is located on 4q33, and contains 13 exons. Primers to amplify these exons are presented, together with mutations identified by molecular analysis of 20 ETF:QO-deficient patients. Twenty-one different disease-causing mutations were identified on 36 of the 40 chromosomes.

  9. Improving the Safety of Cell Therapy Products by Suicide Gene Transfer

    Directory of Open Access Journals (Sweden)

    Antonio eDi Stasi

    2014-11-01

    Full Text Available Adoptive T-cell therapy can involve donor lymphocyte infusion (DLI after allogeneic hematopoietic stem cell transplantation, the administration of tumor infiltrating lymphocyte (TILs expanded ex-vivo, or more recently the use of T cell receptor (TCR or chimeric antigen receptor (CAR redirected T cells. However cellular therapies can pose significant risks, including graft-versus-host-disease and other on and off-target effects, and therefore strategies need to be implemented to permanently reverse any sign of toxicity. A suicide gene is a genetically encoded molecule that allows selective destruction of adoptively transferred cells. Suicide gene addition to cellular therapeutic products can lead to selective ablation of gene-modified cells, preventing collateral damage to contiguous cells and/or tissues. The ‘ideal’ suicide gene would ensure the safety of gene modified cellular applications by granting irreversible elimination of ‘all’ and ‘only’ the cells responsible for the unwanted toxicity. This review presents the suicide gene safety systems reported to date, with a focus on the state-of-the-art and potential applications regarding two of the most extensively validated suicide genes, including the clinical setting: herpes-simplex-thymidine-kinase (HSV-TK and inducible-caspase-9 (iCasp9.

  10. Plant–Agrobacterium interaction mediated by ethylene and super-Agrobacterium conferring efficient gene transfer

    OpenAIRE

    Nonaka, Satoko; Ezura, Hiroshi

    2014-01-01

    Agrobacterium tumefaciens has a unique ability to transfer genes into plant genomes. This ability has been utilized for plant genetic engineering. However, the efficiency is not sufficient for all plant species. Several studies have shown that ethylene decreased the Agrobacterium-mediated transformation frequency. Thus, A. tumefaciens with an ability to suppress ethylene evolution would increase the efficiency of Agrobacterium-mediated transformation. Some studies showed that plant growth-pro...

  11. Transcriptional reprogramming of gene expression in bovine somatic cell chromatin transfer embryos

    Directory of Open Access Journals (Sweden)

    Page Grier P

    2009-04-01

    Full Text Available Abstract Background Successful reprogramming of a somatic genome to produce a healthy clone by somatic cells nuclear transfer (SCNT is a rare event and the mechanisms involved in this process are poorly defined. When serial or successive rounds of cloning are performed, blastocyst and full term development rates decline even further with the increasing rounds of cloning. Identifying the "cumulative errors" could reveal the epigenetic reprogramming blocks in animal cloning. Results Bovine clones from up to four generations of successive cloning were produced by chromatin transfer (CT. Using Affymetrix bovine microarrays we determined that the transcriptomes of blastocysts derived from the first and the fourth rounds of cloning (CT1 and CT4 respectively have undergone an extensive reprogramming and were more similar to blastocysts derived from in vitro fertilization (IVF than to the donor cells used for the first and the fourth rounds of chromatin transfer (DC1 and DC4 respectively. However a set of transcripts in the cloned embryos showed a misregulated pattern when compared to IVF embryos. Among the genes consistently upregulated in both CT groups compared to the IVF embryos were genes involved in regulation of cytoskeleton and cell shape. Among the genes consistently upregulated in IVF embryos compared to both CT groups were genes involved in chromatin remodelling and stress coping. Conclusion The present study provides a data set that could contribute in our understanding of epigenetic errors in somatic cell chromatin transfer. Identifying "cumulative errors" after serial cloning could reveal some of the epigenetic reprogramming blocks shedding light on the reprogramming process, important for both basic and applied research.

  12. Hypothalamic Gene Transfer of BDNF Inhibits Breast Cancer Progression and Metastasis in Middle Age Obese Mice

    OpenAIRE

    Liu, Xianglan; McMurphy, Travis; Xiao, Run; Slater, Andrew; Huang, Wei; Cao, Lei

    2014-01-01

    Activation of the hypothalamus-adipocyte axis is associated with an antiobesity and anticancer phenotype in animal models of melanoma and colon cancer. Brain-derived neurotrophic factor (BDNF) is a key mediator in the hypothalamus leading to preferential sympathoneural activation of adipose tissue and the ensuing resistance to obesity and cancer. Here, we generated middle age obese mice by high fat diet feeding for a year and investigated the effects of hypothalamic gene transfer of BDNF on a...

  13. Intrahepatic injection of adenovirus reduces inflammation and increases gene transfer and therapeutic effect in mice

    OpenAIRE

    Crettaz, J. (Julien); Berraondo, P. (Pedro); Mauleon, I. (Itsaso); Ochoa, L. (Laura); Shankar, V. (Vijay); Barajas, M. (Miguel); Rooijen, N. (Nico) van; Kochanek, S. (Stefan); Qian, C. (Cheng); Prieto, J. (Jesús); Hernandez-Alcoceba, R. (Rubén); Gonzalez-Aseguinolaza, G. (Gloria)

    2006-01-01

    Recombinant adenoviruses (Ad) are among the most extensively used vectors for liver gene transfer. One of the major limitations for the clinical application of these vectors is the inflammatory immune response associated with systemic administration of high dose of virus. We evaluated the effect of Ad administration route on the inflammatory immune response and liver transgene expression. We compared direct intrahepatic injection (IH) with the systemic administration via tail vein (IV). IH in...

  14. Cumulus-specific genes are transcriptionally silent following somatic cell nuclear transfer in a mouse model*

    OpenAIRE

    Tong, Guo-qing; Heng, Boon-chin; Ng, Soon-chye

    2007-01-01

    This study investigated whether four cumulus-specific genes: follicular stimulating hormone receptor (FSHr), hyaluronan synthase 2 (Has2), prostaglandin synthase 2 (Ptgs2) and steroidogenic acute regulator protein (Star), were correctly reprogrammed to be transcriptionally silent following somatic cell nuclear transfer (SCNT) in a murine model. Cumulus cells of C57×CBA F1 female mouse were injected into enucleated oocytes, followed by activation in 10 µmol/L strontium chloride for 5 h and sub...

  15. Transfer of alien genes by means of induced translocation in oats and other crop species

    International Nuclear Information System (INIS)

    Thomas, H.; Taing Aung

    1977-01-01

    Some of the best sources of resistance to mildew, which is the most important disease of the oat crop in the United Kingdom, occur in related weed species. The mildew resistance found in a genotype of the tetraploid species Avena barbata has been transferred into the germ plasm of the cultivated hexaploid species A. sativa by means of an induced translocation. The procedures adopted to isolate the desirable translocation and to determine its breeding behaviour are described. A number of alien genes have been transferred into wheat by means of induced translocations and genetic induction, but their successful introduction into commercial varieties has been limited. In this paper, the use and limitations of alien transfers as breeding material are discussed. (author)

  16. Et tu, Brute? Not Even Intracellular Mutualistic Symbionts Escape Horizontal Gene Transfer

    Directory of Open Access Journals (Sweden)

    Sergio López-Madrigal

    2017-09-01

    Full Text Available Many insect species maintain mutualistic relationships with endosymbiotic bacteria. In contrast to their free-living relatives, horizontal gene transfer (HGT has traditionally been considered rare in long-term endosymbionts. Nevertheless, meta-omics exploration of certain symbiotic models has unveiled an increasing number of bacteria-bacteria and bacteria-host genetic transfers. The abundance and function of transferred loci suggest that HGT might play a major role in the evolution of the corresponding consortia, enhancing their adaptive value or buffering detrimental effects derived from the reductive evolution of endosymbionts’ genomes. Here, we comprehensively review the HGT cases recorded to date in insect-bacteria mutualistic consortia, and discuss their impact on the evolutionary success of these associations.

  17. Effects of different replicons in conjugative plasmids on transformation efficiency, plasmid stability, gene expression and n-butanol biosynthesis in Clostridium tyrobutyricum

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Mingrui; Du, Yinming; Jiang, Wenyan; Chang, Wei-Lun; Yang, Shang-Tian [Ohio State Univ., Columbus, OH (United States). William G. Lowrie Dept. of Chemical and Biomolecular Engineering; Tang, I-Ching [Bioprocessing Innovative Company, Dublin, OH (United States)

    2012-01-15

    Clostridium tyrobutyricum ATCC 25755 can produce butyric acid, acetic acid, and hydrogen as the main products from various carbon sources. In this study, C. tyrobutyricum was used as a host to produce n-butanol by expressing adhE2 gene under the control of a native thiolase promoter using four different conjugative plasmids (pMTL82151, 83151, 84151, and 85151) each with a different replicon (pBP1 from C. botulinum NCTC2916, pCB102 from C. butyricum, pCD6 from Clostridium difficile, and pIM13 from Bacillus subtilis). The effects of different replicons on transformation efficiency, plasmid stability, adhE2 expression and aldehyde/alcohol dehydrogenase activities, and butanol production by different mutants of C. tyrobutyricum were investigated. Among the four plasmids and replicons studied, pMTL82151 with pBP1 gave the highest transformation efficiency, plasmid stability, gene expression, and butanol biosynthesis. Butanol production from various substrates, including glucose, xylose, mannose, and mannitol were then investigated with the best mutant strain harboring adhE2 in pMTL82151. A high butanol titer of 20.5 g/L with 0.33 g/g yield and 0.32 g/L h productivity was obtained with mannitol as the substrate in batch fermentation with pH controlled at {proportional_to}6.0. (orig.)

  18. Long-term transfer and expression of the human beta-globin gene in a mouse transplant model.

    Science.gov (United States)

    Raftopoulos, H; Ward, M; Leboulch, P; Bank, A

    1997-11-01

    Somatic gene therapy of hemoglobinopathies depends initially on the demonstration of safe, efficient gene transfer and long-term, high-level expression of the transferred human beta-globin gene in animal models. We have used a beta-globin gene/beta-locus control region retroviral vector containing several modifications to optimize gene transfer and expression in a mouse transplant model. In this report we show that transplantation of beta-globin-transduced hematopoietic cells into lethally irradiated mice leads to the continued presence of the gene up to 8 months posttransplantation. The transferred human beta-globin gene is detected in 3 of 5 mice surviving long term (>4 months) transplanted with bone marrow cells transduced with high-titer virus. Southern blotting confirms the presence of the unrearranged 5.1-kb human beta-globin gene-containing provirus in 2 of these mice. In addition, long-term expression of the transferred gene is seen in 2 mice at levels of 5% and 20% that of endogenous murine beta-globin at 6 and 8 months posttransplantation. We further document stem cell transduction by the successful transfer and high-level expression of the human beta-globin gene from mice transduced 9 months earlier into irradiated secondary recipient mice. These results demonstrate high-level, long-term somatic human beta-globin gene transfer into the hematopoietic stem cells of an animal for the first time, and suggest the potential feasibility of a retroviral gene therapy approach to sickle cell disease and the beta thalassemias.

  19. Adventitial gene transfer of catalase attenuates angiotensin II-induced vascular remodeling.

    Science.gov (United States)

    Liu, Cun-Fei; Zhang, Jia; Shen, Kai; Gao, Ping-Jin; Wang, Hai-Ya; Jin, Xin; Meng, Chao; Fang, Ning-Yuan

    2015-04-01

    Vascular adventitia and adventitia‑derived reactive oxygen species (ROS) contribute to vascular remodeling following vascular injury. A previous ex vivo study in adventitial fibroblasts showed that catalase, one of most important anti‑oxide enzymes, was downregulated by angiotensin II (AngII). The aim of the present study was to investigate whether adventitial gene transfer of catalase affects AngII‑induced vascular remodeling in vivo. Adenoviruses co‑expressing catalase and enhanced green fluorescent protein (eGFP) or expressing eGFP only were applied to the adventitial surface of common carotid arteries of Sprague‑Dawley rats. Alzet minipumps administering AngII (0.75 mg/kg/day) were then implanted subcutaneously for 14 days. Systolic blood pressure and biological parameters of vascular remodeling were measured in each group. Adventitial fibroblasts were cultured and p38 mitogen‑activated protein kinase (MAPK) phosphorylation was measured using western blot analysis. The results showed that adventitial gene transfer of catalase had no effect on AngII‑induced systolic blood pressure elevation. However, catalase adenovirus transfection significantly inhibited AngII‑induced media hypertrophy compared with that of the control virus (Padventitial α‑smooth muscle actin expression. Furthermore, catalase transfection significantly inhibited the AngII‑induced increase in p38MAPK phosphorylation. In conclusion, the results of the present study demonstrated that adventitial gene transfer of catalase significantly attenuated AngII‑induced vascular remodeling in rats via inhibition of adventitial p38MAPK phosphorylation.

  20. Transferability of microsatellite markers located in candidate genes for wood properties between Eucalyptus species

    Directory of Open Access Journals (Sweden)

    Cintia V. Acuña

    2014-12-01

    Full Text Available Aim of study:  To analyze the feasibility of extrapolating conclusions on wood quality genetic control between different Eucalyptus species, particularly from species with better genomic information, to those less characterized. For this purpose, the first step is to analyze the conservation and cross-transferability of microsatellites markers (SSRs located in candidate genes.Area of study: Eucalyptus species implanted in Argentina coming from different Australian origins.Materials and methods: Twelve validated and polymorphic SSRs in candidate genes (SSR-CGs for wood quality in E. globulus were selected for cross species amplification in six species: E. grandis, E. saligna, E. dunnii, E. viminalis, E. camaldulensis and E. tereticornis.Main results: High cross-species transferability (92% to 100% was found for the 12 polymorphic SSRs detected in E. globulus. These markers revealed allelic diversity in nine important candidate genes: cinnamoyl CoA reductase (CCR, cellulose synthase 3 (CesA3, the transcription factor LIM1, homocysteine S-methyltransferase (HMT, shikimate kinase (SK, xyloglucan endotransglycosylase 2 (XTH2, glutathione S-transferase (GST, glutamate decarboxylase (GAD and peroxidase (PER.Research highlights: The markers described are potentially suitable for comparative QTL mapping, molecular marker assisted breeding (MAB and for population genetic studies across different species within the subgenus Symphyomyrtus.Keywords: validation; cross-transferability; SSR; functional markers; eucalypts; Symphyomyrtus.

  1. THE RISK OF GENE TRANSFERRING IN THE INSURANCE PROTECTION OF AGRICULTERE

    Directory of Open Access Journals (Sweden)

    M. Malik

    2016-03-01

    Full Text Available The paper justified essence of genetic engineering as the object of insurance services. Defines the concept of risk gene transferring. The character features of this specific risk. The influence and consequences for agricultural producers. The description of the possible creation of the concept of insurance services that cover risk of gene transferring. The study reveals of the use of GMOs in agriculture, due to issues of economic security of a particular region or country as a whole. To determined the impact of risks and control for developing and developed countries that are important aspects of farming. Changes in weather, climate, productivity, price values, public policy, the situation on global markets can cause large fluctuations in agricultural production, and consequently affecting the income of agricultural producers. Risk management includes a range of strategies that reduce the social and financial implications of possible changes affecting the production and income of farmers. There is a need for an in-depth study of the theoretical and practical aspects of the impact of the risk of gene transferring in the context of insurance protection.

  2. Low-frequency ultrasound increases non-viral gene transfer to the mouse lung.

    Science.gov (United States)

    Xenariou, Stefania; Liang, Hai-Dong; Griesenbach, Uta; Zhu, Jie; Farley, Raymond; Somerton, Lucinda; Singh, Charanjit; Jeffery, Peter K; Scheule, Ronald K; Cheng, Seng H; Geddes, Duncan M; Blomley, Martin; Alton, Eric W F W

    2010-01-01

    The aim of the study was to assess if low-frequency ultrasound (US), in the range of 30-35 kHz, increases non-viral gene transfer to the mouse lung. US is greatly attenuated in the lung due to large energy losses at the air/tissue interfaces. The advantages of low-frequency US, compared with high-frequency US are: (i) increased cavitation (responsible for the formation of transient pores in the cell membrane) and (ii) reduced energy losses during lung penetration. Cationic lipid GL67/plasmid DNA (pDNA), polyethylenimine (PEI)/pDNA and naked pDNA were delivered via intranasal instillation and the animals were then exposed to US (sonoporation) at 0.07 or 0.1 MPa for 10 min. Under these conditions, US did not enhance GL67 or PEI-mediated transfection. It did, however, increase naked pDNA gene transfer by approximately 4 folds. Importantly, this was achieved in the absence of microbubbles, which are crucial for the commonly used high-frequency (1 MHz) sonoporation but may not be able to withstand nebulization in a clinically relevant setup. Lung hemorrhage was also assessed and shown to increase with US pressure in a dose-dependent manner. We have thus, established that low-frequency US can enhance lung gene transfer with naked pDNA and this enhancement is more effective than the previously reported 1 MHz US.

  3. Beyond Agrobacterium-Mediated Transformation: Horizontal Gene Transfer from Bacteria to Eukaryotes.

    Science.gov (United States)

    Lacroix, Benoît; Citovsky, Vitaly

    2018-03-03

    Besides the massive gene transfer from organelles to the nuclear genomes, which occurred during the early evolution of eukaryote lineages, the importance of horizontal gene transfer (HGT) in eukaryotes remains controversial. Yet, increasing amounts of genomic data reveal many cases of bacterium-to-eukaryote HGT that likely represent a significant force in adaptive evolution of eukaryotic species. However, DNA transfer involved in genetic transformation of plants by Agrobacterium species has traditionally been considered as the unique example of natural DNA transfer and integration into eukaryotic genomes. Recent discoveries indicate that the repertoire of donor bacterial species and of recipient eukaryotic hosts potentially are much wider than previously thought, including donor bacterial species, such as plant symbiotic nitrogen-fixing bacteria (e.g., Rhizobium etli) and animal bacterial pathogens (e.g., Bartonella henselae, Helicobacter pylori), and recipient species from virtually all eukaryotic clades. Here, we review the molecular pathways and potential mechanisms of these trans-kingdom HGT events and discuss their utilization in biotechnology and research.

  4. Oral Gene Application Using Chitosan-DNA Nanoparticles Induces Transferable Tolerance

    Science.gov (United States)

    Ensminger, Stephan M.; Spriewald, Bernd M.

    2012-01-01

    Oral tolerance is a promising approach to induce unresponsiveness to various antigens. The development of tolerogenic vaccines could be exploited in modulating the immune response in autoimmune disease and allograft rejection. In this study, we investigated a nonviral gene transfer strategy for inducing oral tolerance via antigen-encoding chitosan-DNA nanoparticles (NP). Oral application of ovalbumin (OVA)-encoding chitosan-DNA NP (OVA-NP) suppressed the OVA-specific delayed-type hypersensitivity (DTH) response and anti-OVA antibody formation, as well as spleen cell proliferation following OVA stimulation. Cytokine expression patterns following OVA stimulation in vitro showed a shift from a Th1 toward a Th2/Th3 response. The OVA-NP-induced tolerance was transferable from donor to naïve recipient mice via adoptive spleen cell transfer and was mediated by CD4+CD25+ T cells. These findings indicate that nonviral oral gene transfer can induce regulatory T cells for antigen-specific immune modulation. PMID:22933401

  5. Preliminary studies on gene therapy with TGF β1 antisense gene/liposome complexes and adenovirus transfer vector in RPF rats

    International Nuclear Information System (INIS)

    Liu Chunjie; Wang Dewen; Zhang Zhaoshan; Gao Yabing; Xiong Chengqi; Long Jianyin; Wang Huixin; Peng Ruiyun; Cui Xuemei

    2001-01-01

    Objective: To observed the efficiency of gene therapy with TGF β1 antisense gene/liposome complexes and adenovirus transfer vector in RPF rats. Methods: TGFβ1 sense and antisense gene expression vectors and adenovirus transfer vector were introduced into rat bronchus by way of intratracheal instillation. Results: At day 1.5 after TGFβ1 sense and antisense gene transfer, PCR amplification using neo gene-specific primer from lung tissue DNA was all positive. After day 5.5, 67% (2/3) of lung tissue DNA was positive. RNA dot blot hybridization indicated that TGFβ1 mRNA content of lung tissue transfected with pMAMneo-antiTGFβ1 gene decreased. Detection of lung hydroxyproline (Hyp) content after day 35 of gene transfer showed that even in lung of rats received pMAMneo-AntiTGFβ1 lipid complexes it raised remarkably (P 9 pfu/ml were instilled into bronchus at 0.5 ml per rat. After day 2 day 6, the lung tissues of all six rats (three per each group )expressed the transfected luciferase gene by luminometer. Conclusion: Cationic lipid-mediated TGFβ1 antisense gene therapy was a simple and easy method. It can slow down the course of pathogenesis of lung fibrosis. Replication-deficient recombinant adenovirus-mediated gene therapy of lung diseases is a good and efficient method

  6. Investigating rate-limiting barriers to nanoscale nonviral gene transfer with nanobiophotonics

    Science.gov (United States)

    Chen, Hunter H.

    Nucleic acids are a novel class of therapeutics poised to address many unmet clinical needs. Safe and efficient delivery remains a significant challenge that has delayed the realization of the full therapeutic potential of nucleic acids. Nanoscale nonviral vectors offer an attractive alternative to viral vectors as natural and synthetic polymers or polypeptides may be rationally designed to meet the unique demands of individual applications. A mechanistic understanding of cellular barriers is necessary to develop guidelines for designing custom gene carriers which are expected to greatly impact this delivery challenge. The work herein focused on the relationships among nanocomplex stability, intracellular trafficking and unpacking kinetics, and DNA degradation. Ultrasensitive nanosensors based on QD-FRET were developed to characterize the biophysical properties of nanocomplexes and study these rate-limiting steps. Quantitative image analysis enabled the distributions of the subpopulation of condensed or released DNA to be determined within the major cellular compartments encountered during gene transfer. The steady state stability and unpacking kinetics within these compartments were found to impact transgene expression, elucidating multiple design strategies to achieve efficient gene transfer. To address enzymatic barriers, a novel two-step QD-FRET nanosensor was developed to analyze unpacking and DNA degradation simultaneously, which has not been accomplished previously. Bioresponsive strategies such as disulfide crosslinking and thermosensitivity were evaluated by QD-FRET and quantitative compartmental analysis as case studies to determine appropriate design specifications for thiolated polymers and thermoresponsive polypeptides. Relevant nanobiophotonic tools were developed as a platform to study major rate-limiting barriers to nanomedicine and demonstrated the feasibility of using mechanistic information gained from these tools to guide the rational design of

  7. Intravascular local gene transfer mediated by protein-coated metallic stent.

    Science.gov (United States)

    Yuan, J; Gao, R; Shi, R; Song, L; Tang, J; Li, Y; Tang, C; Meng, L; Yuan, W; Chen, Z

    2001-10-01

    To assess the feasibility, efficiency and selectivity of adenovirus-mediated gene transfer to local arterial wall by protein-coated metallic stent. A replication-defective recombinant adenovirus carrying the Lac Z reporter gene for nuclear-specific beta-galactosidase (Ad-beta gal) was used in this study. The coating for metallic stent was made by immersing it in a gelatin solution containing crosslinker. The coated stents were mounted on a 4.0 or 3.0 mm percutaneous transluminal coronary angioplasty (PTCA) balloon and submersed into a high-titer Ad-beta gal viral stock (2 x 10(10) pfu/ml) for 3 min, and then implanted into the carotid arteries in 4 mini-swines and into the left anterior descending branch of the coronary artery in 2 mini-swines via 8F large lumen guiding catheters. The animals were sacrificed 7 (n = 4), 14 (n = 1) and 21 (n = 1) days after implantation, respectively. The beta-galactosidase expression was assessed by X-gal staining. The results showed that the expression of transgene was detected in all animal. In 1 of carotid artery with an intact intima, the beta-gal expression was limited to endothelial cells. In vessels with denuded endothelium, gene expression was found in the sub-intima, media and adventitia. The transfection efficiency of medial smooth muscle cells was 38.6%. In 2 animals sacrificed 7 days after transfection, a microscopic examination of X-gal-stained samples did not show evidence of transfection in remote organs and arterial segments adjacent to the treated arterial site. Adenovirus-mediated arterial gene transfer to endothelial, smooth muscle cells and adventitia by protein-coated metallic stent is feasible. The transfection efficiency is higher. The coated stent may act as a good carrier of adenovirus-mediated gene transfer and have a potential to prevent restenosis following PTCA.

  8. Horizontal gene transfers with or without cell fusions in all categories of the living matter.

    Science.gov (United States)

    Sinkovics, Joseph G

    2011-01-01

    This article reviews the history of widespread exchanges of genetic segments initiated over 3 billion years ago, to be part of their life style, by sphero-protoplastic cells, the ancestors of archaea, prokaryota, and eukaryota. These primordial cells shared a hostile anaerobic and overheated environment and competed for survival. "Coexist with, or subdue and conquer, expropriate its most useful possessions, or symbiose with it, your competitor" remain cellular life's basic rules. This author emphasizes the role of viruses, both in mediating cell fusions, such as the formation of the first eukaryotic cell(s) from a united crenarchaeon and prokaryota, and the transfer of host cell genes integrated into viral (phages) genomes. After rising above the Darwinian threshold, rigid rules of speciation and vertical inheritance in the three domains of life were established, but horizontal gene transfers with or without cell fusions were never abolished. The author proves with extensive, yet highly selective documentation, that not only unicellular microorganisms, but the most complex multicellular entities of the highest ranks resort to, and practice, cell fusions, and donate and accept horizontally (laterally) transferred genes. Cell fusions and horizontally exchanged genetic materials remain the fundamental attributes and inherent characteristics of the living matter, whether occurring accidentally or sought after intentionally. These events occur to cells stagnating for some 3 milliard years at a lower yet amazingly sophisticated level of evolution, and to cells achieving the highest degree of differentiation, and thus functioning in dependence on the support of a most advanced multicellular host, like those of the human brain. No living cell is completely exempt from gene drains or gene insertions.

  9. Inhibition of bacterial conjugation by phage M13 and its protein g3p: quantitative analysis and model.

    Directory of Open Access Journals (Sweden)

    Abraham Lin

    Full Text Available Conjugation is the main mode of horizontal gene transfer that spreads antibiotic resistance among bacteria. Strategies for inhibiting conjugation may be useful for preserving the effectiveness of antibiotics and preventing the emergence of bacterial strains with multiple resistances. Filamentous bacteriophages were first observed to inhibit conjugation several decades ago. Here we investigate the mechanism of inhibition and find that the primary effect on conjugation is occlusion of the conjugative pilus by phage particles. This interaction is mediated primarily by phage coat protein g3p, and exogenous addition of the soluble fragment of g3p inhibited conjugation at low nanomolar concentrations. Our data are quantitatively consistent with a simple model in which association between the pili and phage particles or g3p prevents transmission of an F plasmid encoding tetracycline resistance. We also observe a decrease in the donor ability of infected cells, which is quantitatively consistent with a reduction in pili elaboration. Since many antibiotic-resistance factors confer susceptibility to phage infection through expression of conjugative pili (the receptor for filamentous phage, these results suggest that phage may be a source of soluble proteins that slow the spread of antibiotic resistance genes.

  10. Type 3 fimbriae, encoded by the conjugative plasmid pOLA52, enhance biofilm formation and transfer frequencies in Enterobacteriaceae strains

    DEFF Research Database (Denmark)

    Burmølle, Mette; Bahl, Martin Iain; Jensen, Lars Bogø

    2008-01-01

    pathogenic, members of the family Enterobacteriaceae, including Klebsiella pneumoniae, Salmonella Typhimurium, Kluyvera sp. and Enterobacter aerogenes, pOLA52 facilitated increased biofilm formation. pOLA52 is believed to represent the first example of a conjugative plasmid encoding type 3 fimbriae...

  11. CysQ of , a Protozoa, May Have Been Acquired from Bacteria by Horizontal Gene Transfer

    Directory of Open Access Journals (Sweden)

    Ji Young Lee

    2012-03-01

    Full Text Available Horizontal gene transfer (HGT is the movement of genetic material between kingdoms and is considered to play a positive role in adaptation. Cryptosporidium parvum is a parasitic protozoan that causes an infectious disease. Its genome sequencing reported 14 bacteria-like proteins in the nuclear genome. Among them, cgd2_1810, which has been annotated as CysQ, a sulfite synthesis pathway protein, is listed as one of the candidates of genes horizontally transferred from bacterial origin. In this report, we examined this issue using phylogenetic analysis. Our BLAST search showed that C. parvum CysQ protein had the highest similarity with that of proteobacteria. Analysis with NCBI's Conserved Domain Tree showed phylogenetic incongruence, in that C. parvum CysQ protein was located within a branch of proteobacteria in the cd01638 domain, a bacterial member of the inositol monophosphatase family. According to Kyoto Encyclopedia of Genes and Genomes (KEGG pathway, the sulfate assimilation pathway, where CysQ plays an important role, is well conserved in most eukaryotes as well as prokaryotes. However, the Apicomplexa, including C. parvum, largely lack orthologous genes of the pathway, suggesting its loss in those protozoan lineages. Therefore, we conclude that C. parvum regained cysQ from proteobacteria by HGT, although its functional role is elusive.

  12. Ocular gene transfer in the spotlight: implications of newspaper content for clinical communications.

    Science.gov (United States)

    Benjaminy, Shelly; Bubela, Tania

    2014-07-16

    Ocular gene transfer clinical trials are raising hopes for blindness treatments and attracting media attention. News media provide an accessible health information source for patients and the public, but are often criticized for overemphasizing benefits and underplaying risks of novel biomedical interventions. Overly optimistic portrayals of unproven interventions may influence public and patient expectations; the latter may cause patients to downplay risks and over-emphasize benefits, with implications for informed consent for clinical trials. We analyze the news media communications landscape about ocular gene transfer and make recommendations for improving communications between clinicians and potential trial participants in light of media coverage. We analyzed leading newspaper articles about ocular gene transfer (1990-2012) from United States (n = 55), Canada (n = 26), and United Kingdom (n = 77) from Factiva and Canadian Newsstand databases using pre-defined coding categories. We evaluated the content of newspaper articles about ocular gene transfer for hereditary retinopathies, exploring representations of framing techniques, research design, risks/benefits, and translational timelines. The dominant frame in 61% of stories was a celebration of progress, followed by human-interest in 30% of stories. Missing from the positive frames were explanations of research design; articles conflated clinical research with treatment. Conflicts-of-interest and funding sources were similarly omitted. Attention was directed to the benefits of gene transfer, while risks were only reported in 43% of articles. A range of visual outcomes was described from slowing vision loss to cure, but the latter was the most frequently represented even though it is clinically infeasible. Despite the prominence of visual benefit portrayals, 87% of the articles failed to provide timelines for the commencement of clinical trials or for clinical implementation. Our analysis confirms

  13. Horizontal Transfer of Tetracycline Resistance Genes in the Subsurface of a Poultry Farm

    Science.gov (United States)

    You, Y.; Ward, M.; Hilpert, M.

    2008-12-01

    Concentrated animal feeding operations (CAFOs) are considered to be important man-made reservoirs of antibiotic resistant bacteria and antibiotic resistance genes. At a poultry farm, we, together with Mr.~James Doolittle from USDA, measured the apparent subsurface electrical conductivity (ECa) using a EM38 meter. The resulting ECaR) associated with the poultry farm due to the fact that tetracycline (Tc) is one of the most frequently used antibiotics in food animal production and therefore is probably used at this farm. Soil and aquifer samples were taken from the farm. TcR bacteria were detected, with higher concentrations in the top layer of soil than in the aquifer. TcR bacteria were then enriched from a soil sample, and two classes of TcR genes were detected: tet(M) genes encoding ribosomal protection proteins and tet(L) genes encoding tet efflux pumps. Sequences of the PCR products were compared to known tet(M) and tet(L) genes in GenBank using BLASTN. Phylogenetic trees were also built based on the sequence information. The tet(M) genes found in our soil sample were highly similar to those located on transposons. In a soil microcosm experiment, we used the aforementioned soil sample as incubation medium as well as genetic donor (TcR soil bacteria), and a green fluorescent strain of E. coli as a model genetic recipient to study horizontal transfer of TcR genes from soil bacteria to naïve bacteria. Concentrations of inoculated E. coli were continuously monitored for 15 days, TcR E. coli isolated, and colony PCR performed. The tet(M) genes were found to be transferred to naïve E. coli. The highest horizontal transfer ratio, 0.62 transconjugant per recipient, was observed when Tc was supplemented to a soil microcosm at a concentration of 140 μg/kg soil. Modeling is also ongoing to obtain a better understanding of this complex phenomenon.

  14. The advantages and disadvantages of horizontal gene transfer and the emergence of the first species

    Directory of Open Access Journals (Sweden)

    Higgs Paul G

    2011-01-01

    Full Text Available Abstract Background Horizontal Gene Transfer (HGT is beneficial to a cell if the acquired gene confers a useful function, but is detrimental if the gene has no function, if it is incompatible with existing genes, or if it is a selfishly replicating mobile element. If the balance of these effects is beneficial on average, we would expect cells to evolve high rates of acceptance of horizontally transferred genes, whereas if it is detrimental, cells should reduce the rate of HGT as far as possible. It has been proposed that the rate of HGT was very high in the early stages of prokaryotic evolution, and hence there were no separate lineages of organisms. Only when the HGT rate began to fall, would lineages begin to emerge with their own distinct sets of genes. Evolution would then become more tree-like. This phenomenon has been called the Darwinian Threshold. Results We study a model for genome evolution that incorporates both beneficial and detrimental effects of HGT. We show that if rate of gene loss during genome replication is high, as was probably the case in the earliest genomes before the time of the last universal common ancestor, then a high rate of HGT is favourable. HGT leads to the rapid spread of new genes and allows the build-up of larger, fitter genomes than could be achieved by purely vertical inheritance. In contrast, if the gene loss rate is lower, as in modern prokaryotes, then HGT is, on average, unfavourable. Conclusions Modern cells should therefore evolve to reduce HGT if they can, although the prevalence of independently replicating mobile elements and viruses may mean that cells cannot avoid HGT in practice. In the model, natural selection leads to gradual improvement of the replication accuracy and gradual decrease in the optimal rate of HGT. By clustering genomes based on gene content, we show that there are no separate lineages of organisms when the rate of HGT is high; however, as the rate of HGT decreases, a tree

  15. Tolerance induction to cytoplasmic beta-galactosidase by hepatic AAV gene transfer: implications for antigen presentation and immunotoxicity.

    Directory of Open Access Journals (Sweden)

    Ashley T Martino

    2009-08-01

    Full Text Available Hepatic gene transfer, in particular using adeno-associated viral (AAV vectors, has been shown to induce immune tolerance to several protein antigens. This approach has been exploited in animal models of inherited protein deficiency for systemic delivery of therapeutic proteins. Adequate levels of transgene expression in hepatocytes induce a suppressive T cell response, thereby promoting immune tolerance. This study addresses the question of whether AAV gene transfer can induce tolerance to a cytoplasmic protein.AAV-2 vector-mediated hepatic gene transfer for expression of cytoplasmic beta-galactosidase (beta-gal was performed in immune competent mice, followed by a secondary beta-gal gene transfer with E1/E3-deleted adenoviral Ad-LacZ vector to provoke a severe immunotoxic response. Transgene expression from the AAV-2 vector in approximately 2% of hepatocytes almost completely protected from inflammatory T cell responses against beta-gal, eliminated antibody formation, and significantly reduced adenovirus-induced hepatotoxicity. Consequently, approximately 10% of hepatocytes continued to express beta-gal 45 days after secondary Ad-LacZ gene transfer, a time point when control mice had lost all Ad-LacZ derived expression. Suppression of inflammatory T cell infiltration in the liver and liver damage was linked to specific transgene expression and was not seen for secondary gene transfer with Ad-GFP. A combination of adoptive transfer studies and flow cytometric analyses demonstrated induction of Treg that actively suppressed CD8(+ T cell responses to beta-gal and that was amplified in liver and spleen upon secondary Ad-LacZ gene transfer.These data demonstrate that tolerance induction by hepatic AAV gene transfer does not require systemic delivery of the transgene product and that expression of a cytoplasmic neo-antigen in few hepatocytes can induce Treg and provide long-term suppression of inflammatory responses and immunotoxicity.

  16. In Silico Prediction of Horizontal Gene Transfer Events in Lactobacillus bulgaricus and Streptococcus thermophilus Reveals Protocooperation in Yogurt Manufacturing▿ †

    Science.gov (United States)

    Liu, Mengjin; Siezen, Roland J.; Nauta, Arjen

    2009-01-01

    Lactobacillus bulgaricus and Streptococcus thermophilus, used in yogurt starter cultures, are well known for their stability and protocooperation during their coexistence in milk. In this study, we show that a close interaction between the two species also takes place at the genetic level. We performed an in silico analysis, combining gene composition and gene transfer mechanism-associated features, and predicted horizontally transferred genes in both L. bulgaricus and S. thermophilus. Putative horizontal gene transfer (HGT) events that have occurred between the two bacterial species include the transfer of exopolysaccharide (EPS) biosynthesis genes, transferred from S. thermophilus to L. bulgaricus, and the gene cluster cbs-cblB(cglB)-cysE for the metabolism of sulfur-containing amino acids, transferred from L. bulgaricus or Lactobacillus helveticus to S. thermophilus. The HGT event for the cbs-cblB(cglB)-cysE gene cluster was analyzed in detail, with respect to both evolutionary and functional aspects. It can be concluded that during the coexistence of both yogurt starter species in a milk environment, agonistic coevolution at the genetic level has probably been involved in the optimization of their combined growth and interactions. PMID:19395564

  17. In silico prediction of horizontal gene transfer events in Lactobacillus bulgaricus and Streptococcus thermophilus reveals protocooperation in yogurt manufacturing.

    Science.gov (United States)

    Liu, Mengjin; Siezen, Roland J; Nauta, Arjen

    2009-06-01

    Lactobacillus bulgaricus and Streptococcus thermophilus, used in yogurt starter cultures, are well known for their stability and protocooperation during their coexistence in milk. In this study, we show that a close interaction between the two species also takes place at the genetic level. We performed an in silico analysis, combining gene composition and gene transfer mechanism-associated features, and predicted horizontally transferred genes in both L. bulgaricus and S. thermophilus. Putative horizontal gene transfer (HGT) events that have occurred between the two bacterial species include the transfer of exopolysaccharide (EPS) biosynthesis genes, transferred from S. thermophilus to L. bulgaricus, and the gene cluster cbs-cblB(cglB)-cysE for the metabolism of sulfur-containing amino acids, transferred from L. bulgaricus or Lactobacillus helveticus to S. thermophilus. The HGT event for the cbs-cblB(cglB)-cysE gene cluster was analyzed in detail, with respect to both evolutionary and functional aspects. It can be concluded that during the coexistence of both yogurt starter species in a milk environment, agonistic coevolution at the genetic level has probably been involved in the optimization of their combined growth and interactions.

  18. Gene transfer preferentially selects MHC class I positive tumour cells and enhances tumour immunogenicity.

    Science.gov (United States)

    Hacker, Ulrich T; Schildhauer, Ines; Barroso, Margarita Céspedes; Kofler, David M; Gerner, Franz M; Mysliwietz, Josef; Buening, Hildegard; Hallek, Michael; King, Susan B S

    2006-05-01

    The modulated expression of MHC class I on tumour tissue is well documented. Although the effect of MHC class I expression on the tumorigenicity and immunogenicity of MHC class I negative tumour cell lines has been rigorously studied, less is known about the validity of gene transfer and selection in cell lines with a mixed MHC class I phenotype. To address this issue we identified a C26 cell subline that consists of distinct populations of MHC class I (H-2D/K) positive and negative cells. Transient transfection experiments using liposome-based transfer showed a lower transgene expression in MHC class I negative cells. In addition, MHC class I negative cells were more sensitive to antibiotic selection. This led to the generation of fully MHC class I positive cell lines. In contrast to C26 cells, all transfectants were rejected in vivo and induced protection against the parental tumour cells in rechallenge experiments. Tumour cell specificity of the immune response was demonstrated in in vitro cytokine secretion and cytotoxicity assays. Transfectants expressing CD40 ligand and hygromycin phosphotransferase were not more immunogenic than cells expressing hygromycin resistance alone. We suggest that the MHC class I positive phenotype of the C26 transfectants had a bearing on their immunogenicity, because selected MHC class I positive cells were more immunogenic than parental C26 cells and could induce specific anti-tumour immune responses. These data demonstrate that the generation of tumour cell transfectants can lead to the selection of subpopulations that show an altered phenotype compared to the parental cell line and display altered immunogenicity independent of selection marker genes or other immune modulatory genes. Our results show the importance of monitoring gene transfer in the whole tumour cell population, especially for the evaluation of in vivo therapies targeted to heterogeneous tumour cell populations.

  19. Factor IX expression in skeletal muscle of a severe hemophilia B patient 10 years after AAV-mediated gene transfer.

    Science.gov (United States)

    Buchlis, George; Podsakoff, Gregory M; Radu, Antonetta; Hawk, Sarah M; Flake, Alan W; Mingozzi, Federico; High, Katherine A

    2012-03-29

    In previous work we transferred a human factor IX-encoding adeno-associated viral vector (AAV) into skeletal muscle of men with severe hemophilia B. Biopsy of injected muscle up to 1 year after vector injection showed evidence of gene transfer by Southern blot and of protein expression by IHC and immunofluorescent staining. Although the procedure appeared safe, circulating F.IX levels remained subtherapeutic (< 1%). Recently, we obtained muscle tissue from a subject injected 10 years earlier who died of causes unrelated to gene transfer. Using Western blot, IHC, and immunofluorescent staining, we show persistent factor IX expression in injected muscle tissue. F.IX transcripts were detected in injected skeletal muscle using RT-PCR, and isolated whole genomic DNA tested positive for the presence of the transferred AAV vector sequence. This is the longest reported transgene expression to date from a parenterally administered AAV vector, with broad implications for the future of muscle-directed gene transfer.

  20. Survival of Antibiotic Resistant Bacteria and Horizontal Gene Transfer Control Antibiotic Resistance Gene Content in Anaerobic Digesters.

    Science.gov (United States)

    Miller, Jennifer H; Novak, John T; Knocke, William R; Pruden, Amy

    2016-01-01

    Understanding fate of antibiotic resistant bacteria (ARB) vs. their antibiotic resistance genes (ARGs) during wastewater sludge treatment is critical in order to reduce the spread of antibiotic resistance through process optimization. Here, we spiked high concentrations of tetracycline-resistant bacteria, isolated from mesophilic (Iso M1-1-a Pseudomonas sp.) and thermophilic (Iso T10-a Bacillus sp.) anaerobic digested sludge, into batch digesters and monitored their fate by plate counts and quantitative polymerase chain reaction (QPCR) of their corresponding tetracycline ARGs. In batch studies, spiked ARB plate counts returned to baseline (thermophilic) or 1-log above baseline (mesophilic) while levels of the ARG present in the spiked isolate [tet(G)] remained high in mesophilic batch reactors. To compare results under semi-continuous flow conditions with natural influent variation, tet(O), tet(W), and sul1 ARGs, along with the intI1 integrase gene, were monitored over a 9-month period in the raw feed sludge and effluent sludge of lab-scale thermophilic and mesophilic anaerobic digesters. sul1 and intI1 in mesophilic and thermophilic digesters correlated positively (Spearman rho = 0.457-0.829, P < 0.05) with the raw feed sludge. There was no correlation in tet(O) or tet(W) ratios in raw sludge and mesophilic digested sludge or thermophilic digested sludge (Spearman rho = 0.130-0.486, P = 0.075-0.612). However, in the thermophilic digester, the tet(O) and tet(W) ratios remained consistently low over the entire monitoring period. We conclude that the influent sludge microbial composition can influence the ARG content of a digester, apparently as a result of differential survival or death of ARBs or horizontal gene transfer of genes between raw sludge ARBs and the digester microbial community. Notably, mesophilic digestion was more susceptible to ARG intrusion than thermophilic digestion, which may be attributed to a higher rate of ARB survival and/or horizontal gene

  1. Involvement of β-carbonic anhydrase (β-CA) genes in bacterial genomic islands and horizontal transfer to protists.

    Science.gov (United States)

    Zolfaghari Emameh, Reza; Barker, Harlan R; Hytönen, Vesa P; Parkkila, Seppo

    2018-05-25

    Genomic islands (GIs) are a type of mobile genetic element (MGE) that are present in bacterial chromosomes. They consist of a cluster of genes which produce proteins that contribute to a variety of functions, including, but not limited to, regulation of cell metabolism, anti-microbial resistance, pathogenicity, virulence, and resistance to heavy metals. The genes carried in MGEs can be used as a trait reservoir in times of adversity. Transfer of genes using MGEs, occurring outside of reproduction, is called horizontal gene transfer (HGT). Previous literature has shown that numerous HGT events have occurred through endosymbiosis between prokaryotes and eukaryotes.Beta carbonic anhydrase (β-CA) enzymes play a critical role in the biochemical pathways of many prokaryotes and eukaryotes. We have previously suggested horizontal transfer of β-CA genes from plasmids of some prokaryotic endosymbionts to their protozoan hosts. In this study, we set out to identify β-CA genes that might have transferred between prokaryotic and protist species through HGT in GIs. Therefore, we investigated prokaryotic chromosomes containing β-CA-encoding GIs and utilized multiple bioinformatics tools to reveal the distinct movements of β-CA genes among a wide variety of organisms. Our results identify the presence of β-CA genes in GIs of several medically and industrially relevant bacterial species, and phylogenetic analyses reveal multiple cases of likely horizontal transfer of β-CA genes from GIs of ancestral prokaryotes to protists. IMPORTANCE The evolutionary process is mediated by mobile genetic elements (MGEs), such as genomic islands (GIs). A gene or set of genes in the GIs are exchanged between and within various species through horizontal gene transfer (HGT). Based on the crucial role that GIs can play in bacterial survival and proliferation, they were introduced as the environmental- and pathogen-associated factors. Carbonic anhydrases (CAs) are involved in many critical

  2. Effective generation of transgenic pigs and mice by linker based sperm-mediated gene transfer.

    Directory of Open Access Journals (Sweden)

    Shih Ping Yao

    2002-04-01

    Full Text Available Abstract Background Transgenic animals have become valuable tools for both research and applied purposes. The current method of gene transfer, microinjection, which is widely used in transgenic mouse production, has only had limited success in producing transgenic animals of larger or higher species. Here, we report a linker based sperm-mediated gene transfer method (LB-SMGT that greatly improves the production efficiency of large transgenic animals. Results The linker protein, a monoclonal antibody (mAb C, is reactive to a surface antigen on sperm of all tested species including pig, mouse, chicken, cow, goat, sheep, and human. mAb C is a basic protein that binds to DNA through ionic interaction allowing exogenous DNA to be linked specifically to sperm. After fertilization of the egg, the DNA is shown to be successfully integrated into the genome of viable pig and mouse offspring with germ-line transfer to the F1 generation at a highly efficient rate: 37.5% of pigs and 33% of mice. The integration is demonstrated again by FISH analysis and F2 transmission in pigs. Furthermore, expression of the transgene is demonstrated in 61% (35/57 of transgenic pigs (F0 generation. Conclusions Our data suggests that LB-SMGT could be used to generate transgenic animals efficiently in many different species.

  3. Transfer

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne; Aarkrog, Vibe

    Bogen er den første samlede indføring i transfer på dansk. Transfer kan anvendes som praksis-filosofikum. Den giver en systematisk indsigt til den studerende, der spørger: Hvordan kan teoretisk viden bruges til at reflektere over handlinger i situationer, der passer til min fremtidige arbejdsplads?...

  4. The qacC Gene Has Recently Spread between Rolling Circle Plasmids of Staphylococcus, Indicative of a Novel Gene Transfer Mechanism

    DEFF Research Database (Denmark)

    Wassenaar, Trudy M; Ussery, David W; Ingmer, Hanne

    2016-01-01

    and transferred to acceptor RC-plasmids without assistance of other genes, by means of its location in between the Double Strand replication Origin (DSO) and the Single-Strand replication Origin (SSO). The proposed mobilization model of this DSO-qacC-SSO element represents a novel mechanism of gene mobilization...

  5. Correction of the retinal dystrophy phenotype of the RCS rat by viral gene transfer of Mertk.

    Science.gov (United States)

    Vollrath, D; Feng, W; Duncan, J L; Yasumura, D; D'Cruz, P M; Chappelow, A; Matthes, M T; Kay, M A; LaVail, M M

    2001-10-23

    The Royal College of Surgeons (RCS) rat is a widely studied animal model of retinal degeneration in which the inability of the retinal pigment epithelium (RPE) to phagocytize shed photoreceptor outer segments leads to a progressive loss of rod and cone photoreceptors. We recently used positional cloning to demonstrate that the gene Mertk likely corresponds to the retinal dystrophy (rdy) locus of the RCS rat. In the present study, we sought to determine whether gene transfer of Mertk to a RCS rat retina would result in correction of the RPE phagocytosis defect and preservation of photoreceptors. We used subretinal injection of a recombinant replication-deficient adenovirus encoding rat Mertk to deliver the gene to the eyes of young RCS rats. Electrophysiological assessment of animals 30 days after injection revealed an increased sensitivity of treated eyes to low-intensity light. Histologic and ultrastructural assessment demonstrated substantial sparing of photoreceptors, preservation of outer segment structure, and correction of the RPE phagocytosis defect in areas surrounding the injection site. Our results provide definitive evidence that mutation of Mertk underlies the RCS retinal dystrophy phenotype, and that the phenotype can be corrected by treatment of juvenile animals. To our knowledge, this is the first demonstration of complementation of both a functional cellular defect (phagocytosis) and a photoreceptor degeneration by gene transfer to the RPE. These results, together with the recent discovery of MERTK mutations in individuals with retinitis pigmentosa, emphasize the importance of the RCS rat as a model for gene therapy of diseases that arise from RPE dysfunction.

  6. Investigation of transfection efficacy with transcatheter arterial transporting transferring to enhance p53 gene

    International Nuclear Information System (INIS)

    Lu Qin; Niu Huanzhang; Zhu Guangyu; An Yanli; Qiu Dinghong; Teng Gaojun

    2007-01-01

    Objective: To investigate the function of transferrin-DNA complex, transported by transferrin(Tf) and trans-arterial injection via interventional approach be the duel-target-orientated delivery and the transferring into malignant cells to get more effective therapy. Methods: p53-LipofectAMINE ligand with different concentrations of Tf (0, 10, 25, 50, 100 μg)transfected the 4 strains including LM6,Hep3B,YY and L02 in vitro to evaluate the gene transfection efficiency through western blot. Then, after setting up the VX2 hepatocarcinoma models, we delivered the Tf-p53-LipofectAMlNE complex into the hepatic arteries via interventional techniques to analyse the transfection efficiency in vivo. Results: Tf, within the range of l0 100 μg, could increase gene transfection efficiency mediated by liposome, and the efficiency increases with the raise of Tf concentration. Combination with interventional technique to inject Tf-DNA complex into tumor arteries, gene transfection efficiency was enhanced in rabbit models. Conclusion: Tf can enhance gene-liposome transfection efficiency, furthermore with combination of interventional catheter technique, there would be a potential duel-target-orientated gene therapy method. (authors)

  7. Gene Transfer into the Lung by Nanoparticle Dextran-Spermine/Plasmid DNA Complexes

    Directory of Open Access Journals (Sweden)

    Syahril Abdullah

    2010-01-01

    Full Text Available A novel cationic polymer, dextran-spermine (D-SPM, has been found to mediate gene expression in a wide variety of cell lines and in vivo through systemic delivery. Here, we extended the observations by determining the optimal conditions for gene expression of D-SPM/plasmid DNA (D-SPM/pDNA in cell lines and in the lungs of BALB/c mice via instillation delivery. In vitro studies showed that D-SPM could partially protect pDNA from degradation by nuclease and exhibited optimal gene transfer efficiency at D-SPM to pDNA weight-mixing ratio of 12. In the lungs of mice, the levels of gene expression generated by D-SPM/pDNA are highly dependent on the weight-mixing ratio of D-SPM to pDNA, amount of pDNA in the complex, and the assay time postdelivery. Readministration of the complex at day 1 following the first dosing showed no significant effect on the retention and duration of gene expression. The study also showed that there was a clear trend of increasing size of the complexes as the amount of pDNA was increased, where the sizes of the D-SPM/pDNA complexes were within the nanometer range.

  8. Investigation of transfection efficacy with transcatheter arterial transporting transferring to enhance p53 gene

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Lu; Huanzhang, Niu; Guangyu, Zhu; Yanli, An; Dinghong, Qiu; Gaojun, Teng [Radiologic Department, Zhongda Hospital, Southeast Univ., Nanjing (China)

    2007-02-15

    Objective: To investigate the function of transferrin-DNA complex, transported by transferrin(Tf) and trans-arterial injection via interventional approach be the duel-target-orientated delivery and the transferring into malignant cells to get more effective therapy. Methods: p53-LipofectAMINE ligand with different concentrations of Tf (0, 10, 25, 50, 100 {mu}g)transfected the 4 strains including LM6,Hep3B,YY and L02 in vitro to evaluate the gene transfection efficiency through western blot. Then, after setting up the VX2 hepatocarcinoma models, we delivered the Tf-p53-LipofectAMlNE complex into the hepatic arteries via interventional techniques to analyse the transfection efficiency in vivo. Results: Tf, within the range of l0 100 {mu}g, could increase gene transfection efficiency mediated by liposome, and the efficiency increases with the raise of Tf concentration. Combination with interventional technique to inject Tf-DNA complex into tumor arteries, gene transfection efficiency was enhanced in rabbit models. Conclusion: Tf can enhance gene-liposome transfection efficiency, furthermore with combination of interventional catheter technique, there would be a potential duel-target-orientated gene therapy method. (authors)

  9. Root parasitic plant Orobanche aegyptiaca and shoot parasitic plant Cuscuta australis obtained Brassicaceae-specific strictosidine synthase-like genes by horizontal gene transfer.

    Science.gov (United States)

    Zhang, Dale; Qi, Jinfeng; Yue, Jipei; Huang, Jinling; Sun, Ting; Li, Suoping; Wen, Jian-Fan; Hettenhausen, Christian; Wu, Jinsong; Wang, Lei; Zhuang, Huifu; Wu, Jianqiang; Sun, Guiling

    2014-01-13

    Besides gene duplication and de novo gene generation, horizontal gene transfer (HGT) is another important way of acquiring new genes. HGT may endow the recipients with novel phenotypic traits that are important for species evolution and adaption to new ecological niches. Parasitic systems expectedly allow the occurrence of HGT at relatively high frequencies due to their long-term physical contact. In plants, a number of HGT events have been reported between the organelles of parasites and the hosts, but HGT between host and parasite nuclear genomes has rarely been found. A thorough transcriptome screening revealed that a strictosidine synthase-like (SSL) gene in the root parasitic plant Orobanche aegyptiaca and the shoot parasitic plant Cuscuta australis showed much higher sequence similarities with those in Brassicaceae than with those in their close relatives, suggesting independent gene horizontal transfer events from Brassicaceae to these parasites. These findings were strongly supported by phylogenetic analysis and their identical unique amino acid residues and deletions. Intriguingly, the nucleus-located SSL genes in Brassicaceae belonged to a new member of SSL gene family, which were originated from gene duplication. The presence of introns indicated that the transfer occurred directly by DNA integration in both parasites. Furthermore, positive selection was detected in the foreign SSL gene in O. aegyptiaca but not in C. australis. The expression of the foreign SSL genes in these two parasitic plants was detected in multiple development stages and tissues, and the foreign SSL gene was induced after wounding treatment in C. australis stems. These data imply that the foreign genes may still retain certain functions in the recipient species. Our study strongly supports that parasitic plants can gain novel nuclear genes from distantly related host species by HGT and the foreign genes may execute certain functions in the new hosts.

  10. Transfer of genes for stem rust resistance from Agropyron elongatum and imperial rye to durum wheat

    International Nuclear Information System (INIS)

    Prabhakara Rao, M.V.

    1977-01-01

    The Agropyron elongatum gene for stem rust resistance on chromosome 6A of Knott's Thatcher translocation line was transferred to a susceptible local durum wheat variety, Jaya, through a series of back-crosses. Plants heterozygous for the Agropyron translocation always show at least one open bivalent. Homozygotes have not been obtained, probably because of the absence of male transmission in durum background. Monotelosomic addition of the short arm of Imperial rye chromosome 3R (formerly ''G'' of Sears), which carries a gene(s) for resistance to wheat stem rust, was obtained in the local durum variety. Rust-resistant plants from parents having the added rye telocentric were irradiated with gamma rays just before meiosis, and the pollen obtained from the irradiated spikes was used to pollinate euploid plants. In addition, seeds harvested from 2n+1 resistant plants were irradiated with thermal neutrons and the resistant M 1 plants were selfed to raise M 2 families. Two durum-rye translocation lines were obtained following irradiation. DRT-1 was transmitted normally through the female gametes but showed no male transmission. As a result of this, homozygotes have not been obtained. Gametic transmission rates of DRT-2 are being tested. Alien translocations, which show normal gametic and zygotic transmissions in the hexaploid wheat, may behave differently in a tetraploid background. The results indicate that alien genetic transfers may be more difficult to obtain in durum wheat, probably owing to the reduced buffering effect of the tetraploid genome. (author)

  11. Evolution of Phototrophy in the Chloroflexi Phylum Driven by Horizontal Gene Transfer

    Directory of Open Access Journals (Sweden)

    Lewis M. Ward

    2018-02-01

    Full Text Available The evolutionary mechanisms behind the extant distribution of photosynthesis is a point of substantial contention. Hypotheses range from the presence of phototrophy in the last universal common ancestor and massive gene loss in most lineages, to a later origin in Cyanobacteria followed by extensive horizontal gene transfer into the extant phototrophic clades, with intermediate scenarios that incorporate aspects of both end-members. Here, we report draft genomes of 11 Chloroflexi: the phototrophic Chloroflexia isolate Kouleothrix aurantiaca as well as 10 genome bins recovered from metagenomic sequencing of microbial mats found in Japanese hot springs. Two of these metagenome bins encode photrophic reaction centers and several of these bins form a metabolically diverse, monophyletic clade sister to the Anaerolineae class that we term Candidatus Thermofonsia. Comparisons of organismal (based on conserved ribosomal and phototrophy (reaction center and bacteriochlorophyll synthesis protein phylogenies throughout the Chloroflexi demonstrate that two new lineages acquired phototrophy independently via horizontal gene transfer (HGT from different ancestral donors within the classically phototrophic Chloroflexia class. These results illustrate a complex history of phototrophy within this group, with metabolic innovation tied to HGT. These observations do not support simple hypotheses for the evolution of photosynthesis that require massive character loss from many clades; rather, HGT appears to be the defining mechanic for the distribution of phototrophy in many of the extant clades in which it appears.

  12. Immunobiologic effects of cytokine gene transfer of the B16-BL6 melanoma.

    Science.gov (United States)

    Strome, S E; Krauss, J C; Cameron, M J; Forslund, K; Shu, S; Chang, A E

    1993-12-01

    The genetic modification of tumors offers an approach to modulate the host immune response to relatively weak native tumor antigens. We examined the immunobiologic effects of various cytokine genes transferred into the poorly immunogenic B16-BL6 murine melanoma. Retroviral expression vectors containing cDNAs for interleukin 2, interleukin 4, interferon gamma, or a neomycin-resistant control were electroporated into a B16-BL6 tumor clone. Selected transfected clones were examined for in vitro cytokine secretion and in vivo tumorigenicity. When cells from individual clones were injected intradermally into syngeneic mice, the interleukin 4-secreting clone grew significantly slower than did the neomycin-resistant transfected control, while the growth of the interleukin 2- and interferon gamma-expressing clones was not affected. Despite minimal cytokine secretion by interferon gamma-transfected cells, these cells expressed upregulated major histocompatibility class I antigen and were more susceptible to lysis by allosensitized cytotoxic T lymphocytes compared with parental or neomycin-resistant transfected tumor targets. We observed diverse immunobiologic effects associated with cytokine gene transfer into the B16-BL6 melanoma. Interleukin 4 transfection of tumor resulted in decreased in vivo tumorigenicity that may be related to a host immune response. Further studies to evaluate the host T-cell response to these gene-modified tumors are being investigated.

  13. Resolution and reconciliation of non-binary gene trees with transfers, duplications and losses.

    Science.gov (United States)

    Jacox, Edwin; Weller, Mathias; Tannier, Eric; Scornavacca, Celine

    2017-04-01

    Gene trees reconstructed from sequence alignments contain poorly supported branches when the phylogenetic signal in the sequences is insufficient to determine them all. When a species tree is available, the signal of gains and losses of genes can be used to correctly resolve the unsupported parts of the gene history. However finding a most parsimonious binary resolution of a non-binary tree obtained by contracting the unsupported branches is NP-hard if transfer events are considered as possible gene scale events, in addition to gene origination, duplication and loss. We propose an exact, parameterized algorithm to solve this problem in single-exponential time, where the parameter is the number of connected branches of the gene tree that show low support from the sequence alignment or, equivalently, the maximum number of children of any node of the gene tree once the low-support branches have been collapsed. This improves on the best known algorithm by an exponential factor. We propose a way to choose among optimal solutions based on the available information. We show the usability of this principle on several simulated and biological datasets. The results are comparable in quality to several other tested methods having similar goals, but our approach provides a lower running time and a guarantee that the produced solution is optimal. Our algorithm has been integrated into the ecceTERA phylogeny package, available at http://mbb.univ-montp2.fr/MBB/download_sources/16__ecceTERA and which can be run online at http://mbb.univ-montp2.fr/MBB/subsection/softExec.php?soft=eccetera . celine.scornavacca@umontpellier.fr. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

  14. Phylogenetic detection of horizontal gene transfer during the step-wise genesis of Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    Turenne Christine

    2009-08-01

    Full Text Available Abstract Background In the past decade, the availability of complete genome sequence data has greatly facilitated comparative genomic research aimed at addressing genetic variability within species. More recently, analysis across species has become feasible, especially in genera where genome sequencing projects of multiple species have been initiated. To understand the genesis of the pathogen Mycobacterium tuberculosis within a genus where the majority of species are harmless environmental organisms, we have used genome sequence data from 16 mycobacteria to look for evidence of horizontal gene transfer (HGT associated with the emergence of pathogenesis. First, using multi-locus sequence analysis (MLSA of 20 housekeeping genes across these species, we derived a phylogeny that serves as the basis for HGT assignments. Next, we performed alignment searches for the 3989 proteins of M. tuberculosis H37Rv against 15 other mycobacterial genomes, generating a matrix of 59835 comparisons, to look for genetic elements that were uniquely found in M. tuberculosis and closely-related pathogenic mycobacteria. To assign when foreign genes were likely acquired, we designed a bioinformatic program called mycoHIT (mycobacterial homologue investigation tool to analyze these data in conjunction with the MLSA-based phylogeny. Results The bioinformatic screen predicted that 137 genes had been acquired by HGT at different phylogenetic strata; these included genes coding for metabolic functions and modification of mycobacterial lipids. For the majority of these genes, corroborating evidence of HGT was obtained, such as presence of phage or plasmid, and an aberrant GC%. Conclusion M. tuberculosis emerged through vertical inheritance along with the step-wise addition of genes acquired via HGT events, a process that may more generally describe the evolution of other pathogens.

  15. Direct gene transfer in the Gottingen minipig CNS using stereotaxic lentiviral microinjections

    DEFF Research Database (Denmark)

    GLUD, AN; Hedegaard, Claus; Nielsen, Mette Slot

    2010-01-01

    We aim to induce direct viral mediated gene transfer in the substantia nigra (SN) of the Gottingen minipig using MRI guided stereotaxic injections of lentiviral vectors encoding enhanced green fluorescent protein (EGFP). Nine female Gottingen minipigs were injected unilaterally into the SN with 6...... per 2.5 microliters lentivirus capable of transducing cells and mediating expression of recombinant EGFP. The animals were euthanized after four (n=3) or twenty weeks (n=6). Fresh brain tissue from three animals was used for PCR. The remaining six brains were cryo- or paraffin...

  16. Gene transfer of heterologous G protein-coupled receptors to cardiomyocytes: differential effects on contractility.

    Science.gov (United States)

    Laugwitz, K L; Weig, H J; Moretti, A; Hoffmann, E; Ueblacker, P; Pragst, I; Rosport, K; Schömig, A; Ungerer, M

    2001-04-13

    In heart failure, reduced cardiac contractility is accompanied by blunted cAMP responses to beta-adrenergic stimulation. Parathyroid hormone (PTH)-related peptide and arginine vasopressin are released from the myocardium in response to increased wall stress but do not stimulate contractility or adenylyl cyclase at physiological concentrations. To bypass the defective beta-adrenergic signaling cascade, recombinant P1 PTH/PTH-related peptide receptors (rPTH1-Rs) and V(2) vasopressin receptors (rV(2)-Rs), which are normally not expressed in the myocardium and which are both strongly coupled to adenylyl cyclase, and recombinant beta(2)-adrenergic receptors (rbeta(2)-ARs) were overexpressed in cardiomyocytes by viral gene transfer. The capacity of endogenous hormones to increase contractility via the heterologous, recombinant receptors was compared. Whereas V(2)-Rs are uniquely coupled to Gs, PTH1-Rs and beta(2)-ARs are also coupled to other G proteins. Gene transfer of rPTH1-Rs or rbeta(2)-ARs to adult cardiomyocytes resulted in maximally increased basal contractility, which could not be further stimulated by adding receptor agonists. Agonists at rPTH1-Rs induced increased cAMP formation and phospholipase C activity. In contrast, healthy or failing rV(2)-R-expressing cardiomyocytes showed unaltered basal contractility. Their contractility and cAMP formation increased only at agonist exposure, which did not activate phospholipase C. In summary, we found that gene transfer of PTH1-Rs to cardiomyocytes results in constitutive activity of the transgene, as does that of beta(2)-ARS: In the absence of receptor agonists, rPTH1-Rs and rbeta(2)-ARs increase basal contractility, coupling to 2 G proteins simultaneously. In contrast, rV(2)-Rs are uniquely coupled to Gs and are not constitutively active, retaining their property to be activated exclusively on agonist stimulation. Therefore, gene transfer of V(2)-Rs might be more suited to test the effects of c

  17. High-efficiency gene transfer into skeletal muscle mediated by electric pulses

    DEFF Research Database (Denmark)

    Mir, L M; Bureau, M F; Gehl, J

    1999-01-01

    Gene delivery to skeletal muscle is a promising strategy for the treatment of muscle disorders and for the systemic secretion of therapeutic proteins. However, present DNA delivery technologies have to be improved with regard to both the level of expression and interindividual variability. We...... report very efficient plasmid DNA transfer in muscle fibers by using square-wave electric pulses of low field strength (less than 300 V/cm) and of long duration (more than 1 ms). Contrary to the electropermeabilization-induced uptake of small molecules into muscle fibers, plasmid DNA has to be present...... in the tissue during the electric pulses, suggesting a direct effect of the electric field on DNA during electrotransfer. This i.m. electrotransfer method increases reporter and therapeutic gene expression by several orders of magnitude in various muscles in mouse, rat, rabbit, and monkey. Moreover, i...

  18. Untangling hybrid phylogenetic signals: horizontal gene transfer and artifacts of phylogenetic reconstruction.

    Science.gov (United States)

    Beiko, Robert G; Ragan, Mark A

    2009-01-01

    Phylogenomic methods can be used to investigate the tangled evolutionary relationships among genomes. Building 'all the trees of all the genes' can potentially identify common pathways of horizontal gene transfer (HGT) among taxa at varying levels of phylogenetic depth. Phylogenetic affinities can be aggregated and merged with the information about genetic linkage and biochemical function to examine hypotheses of adaptive evolution via HGT. Additionally, the use of many genetic data sets increases the power of statistical tests for phylogenetic artifacts. However, large-scale phylogenetic analyses pose several challenges, including the necessary abandonment of manual validation techniques, the need to translate inferred phylogenetic discordance into inferred HGT events, and the challenges involved in aggregating results from search-based inference methods. In this chapter we describe a tree search procedure to recover the most parsimonious pathways of HGT, and examine some of the assumptions that are made by this method.

  19. Transfer and expression of the rabbit defensin NP-1 gene in lettuce (Lactuca sativa).

    Science.gov (United States)

    Song, D; Xiong, X; Tu, W F; Yao, W; Liang, H W; Chen, F J; He, Z Q

    2017-01-23

    Lettuce (Lactuca sativa L.) is an annual plant of the daisy family, Asteraceae, with high food and medicinal value. However, the crop is susceptible to several viruses that are transmitted by aphids and is highly vulnerable to post-harvest diseases, as well as insect and mammal pests and fungal and bacterial diseases. Here, the rabbit defensin gene NP-1 was transferred into lettuce by Agrobacterium-mediated transformation to obtain a broad-spectrum disease-resistant lettuce. Transgenic lettuce plants were selected and regenerated on selective media. The presence of the NP-1 gene in these plants was confirmed by western blot analyses. Resistance tests revealed native defensin NP-1 expression conferred partial resistance to Bacillus subtilis and Pseudomonas aeruginosa, which suggests new possibilities for lettuce disease resistance.

  20. Complete genome sequence of Brachyspira intermedia reveals unique genomic features in Brachyspira species and phage-mediated horizontal gene transfer

    Science.gov (United States)

    2011-01-01

    Background Brachyspira spp. colonize the intestines of some mammalian and avian species and show different degrees of enteropathogenicity. Brachyspira intermedia can cause production losses in chickens and strain PWS/AT now becomes the fourth genome to be completed in the genus Brachyspira. Results 15 classes of unique and shared genes were analyzed in B. intermedia, B. murdochii, B. hyodysenteriae and B. pilosicoli. The largest number of unique genes was found in B. intermedia and B. murdochii. This indicates the presence of larger pan-genomes. In general, hypothetical protein annotations are overrepresented among the unique genes. A 3.2 kb plasmid was found in B. intermedia strain PWS/AT. The plasmid was also present in the B. murdochii strain but not in nine other Brachyspira isolates. Within the Brachyspira genomes, genes had been translocated and also frequently switched between leading and lagging strands, a process that can be followed by different AT-skews in the third positions of synonymous codons. We also found evidence that bacteriophages were being remodeled and genes incorporated into them. Conclusions The accessory gene pool shapes species-specific traits. It is also influenced by reductive genome evolution and horizontal gene transfer. Gene-transfer events can cross both species and genus boundaries and bacteriophages appear to play an important role in this process. A mechanism for horizontal gene transfer appears to be gene translocations leading to remodeling of bacteriophages in combination with broad tropism. PMID:21816042

  1. Transient gene transfer to neurons and glia : analysis of adenoviral vector performance in the CNS and PNS

    NARCIS (Netherlands)

    Hermens, W.T.J.M.C.; Giger, Roman J; Holtmaat, Anthony J D G; Dijkhuizen, Paul A; Houweling, D A; Verhaagen, J

    In this paper a detailed protocol is presented for neuroscientists planning to start work on first generation recombinant adenoviral vectors as gene transfer agents for the nervous system. The performance of a prototype adenoviral vector encoding the bacterial lacZ gene as a reporter was studied,

  2. Adenoviral vector-mediated gene transfer and neurotransplantation : possibilities and limitations in grafting of the fetal rat suprachiasmatic nucleus

    NARCIS (Netherlands)

    van Esseveldt, K E; Liu, R.; Hermens, W.T.J.M.C.; Verhaagen, J; Boer, G J

    Several studies have reported on the use of primary neural cells transduced by adenoviral vectors as donor cells in neurotransplantation. In the present investigation, we examined whether adenoviral vector-mediated gene transfer could be used to introduce and express a foreign gene in solid neural

  3. Bortezomib Enhances the Antitumor Effects of Interferon-β Gene Transfer on Melanoma Cells.

    Science.gov (United States)

    Rossi, Ursula A; Finocchiaro, Liliana M E; Glikin, Gerardo C

    2017-01-01

    Malignant melanoma is a fast growing form of skin cancer with increasing global incidence. Clinically, canine malignant melanoma and human melanoma share comparable treatment-resistances, metastatic phenotypes and site selectivity. Both interferon-β (IFNβ) and bortezomib (BTZ) display inhibitory activities on melanoma cells. Here, we evaluated the cytotoxic effects of the combination of BTZ and IFNβ gene lipofection on cultured melanoma cell lines. Cell viability determined by the acid phosphatase method, cell migration mesasured by the wound healing assay, DNA fragmentation and cell cycle by flow cytometry after propidium iodide staining and reactive oxygen species (ROS) production by H2DCF-DA fluorescence. Four canine mucosal (Ak, Br, Bk and Ol) and two human dermal (A375 and SB2) melanoma cell lines were assayed. BTZ sub-pharmacological concentrations (5 nM) enhanced the cytotoxic effects of IFNβ transgene expression on melanoma cells monolayers and spheroids. The combination was also more effective than the single treatments when assayed for clonogenic survival and cell migration. The combined treatment produced a significant raise of apoptosis evidenced by DNA fragmentation as compared to either BTZ or IFNβ gene lipofection single treatments. Furthermore, BTZ significantly increased the intracellular ROS generation induced by IFNβ gene transfer in melanoma cells, an effect that was reversed by the addition of the ROS inhibitor N-acetyl-L-cystein. The present work encourages further studies about the potential of the combination of interferon gene transfer with proteasome inhibitors as a new combined therapy for malignant melanoma, both in veterinary and/or human clinical settings. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  4. Protein Homeostasis Imposes a Barrier on Functional Integration of Horizontally Transferred Genes in Bacteria.

    Science.gov (United States)

    Bershtein, Shimon; Serohijos, Adrian W R; Bhattacharyya, Sanchari; Manhart, Michael; Choi, Jeong-Mo; Mu, Wanmeng; Zhou, Jingwen; Shakhnovich, Eugene I

    2015-10-01

    Horizontal gene transfer (HGT) plays a central role in bacterial evolution, yet the molecular and cellular constraints on functional integration of the foreign genes are poorly understood. Here we performed inter-species replacement of the chromosomal folA gene, encoding an essential metabolic enzyme dihydrofolate reductase (DHFR), with orthologs from 35 other mesophilic bacteria. The orthologous inter-species replacements caused a marked drop (in the range 10-90%) in bacterial growth rate despite the fact that most orthologous DHFRs are as stable as E.coli DHFR at 37°C and are more catalytically active than E. coli DHFR. Although phylogenetic distance between E. coli and orthologous DHFRs as well as their individual molecular properties correlate poorly with growth rates, the product of the intracellular DHFR abundance and catalytic activity (kcat/KM), correlates strongly with growth rates, indicating that the drop in DHFR abundance constitutes the major fitness barrier to HGT. Serial propagation of the orthologous strains for ~600 generations dramatically improved growth rates by largely alleviating the fitness barriers. Whole genome sequencing and global proteome quantification revealed that the evolved strains with the largest fitness improvements have accumulated mutations that inactivated the ATP-dependent Lon protease, causing an increase in the intracellular DHFR abundance. In one case DHFR abundance increased further due to mutations accumulated in folA promoter, but only after the lon inactivating mutations were fixed in the population. Thus, by apparently distinguishing between self and non-self proteins, protein homeostasis imposes an immediate and global barrier to the functional integration of foreign genes by decreasing the intracellular abundance of their products. Once this barrier is alleviated, more fine-tuned evolution occurs to adjust the function/expression of the transferred proteins to the constraints imposed by the intracellular

  5. Protein Homeostasis Imposes a Barrier on Functional Integration of Horizontally Transferred Genes in Bacteria.

    Directory of Open Access Journals (Sweden)

    Shimon Bershtein

    2015-10-01

    Full Text Available Horizontal gene transfer (HGT plays a central role in bacterial evolution, yet the molecular and cellular constraints on functional integration of the foreign genes are poorly understood. Here we performed inter-species replacement of the chromosomal folA gene, encoding an essential metabolic enzyme dihydrofolate reductase (DHFR, with orthologs from 35 other mesophilic bacteria. The orthologous inter-species replacements caused a marked drop (in the range 10-90% in bacterial growth rate despite the fact that most orthologous DHFRs are as stable as E.coli DHFR at 37°C and are more catalytically active than E. coli DHFR. Although phylogenetic distance between E. coli and orthologous DHFRs as well as their individual molecular properties correlate poorly with growth rates, the product of the intracellular DHFR abundance and catalytic activity (kcat/KM, correlates strongly with growth rates, indicating that the drop in DHFR abundance constitutes the major fitness barrier to HGT. Serial propagation of the orthologous strains for ~600 generations dramatically improved growth rates by largely alleviating the fitness barriers. Whole genome sequencing and global proteome quantification revealed that the evolved strains with the largest fitness improvements have accumulated mutations that inactivated the ATP-dependent Lon protease, causing an increase in the intracellular DHFR abundance. In one case DHFR abundance increased further due to mutations accumulated in folA promoter, but only after the lon inactivating mutations were fixed in the population. Thus, by apparently distinguishing between self and non-self proteins, protein homeostasis imposes an immediate and global barrier to the functional integration of foreign genes by decreasing the intracellular abundance of their products. Once this barrier is alleviated, more fine-tuned evolution occurs to adjust the function/expression of the transferred proteins to the constraints imposed by the

  6. Design and bioinformatics analysis of novel biomimetic peptides as nanocarriers for gene transfer

    Directory of Open Access Journals (Sweden)

    Asia Majidi

    2015-01-01

    Full Text Available Objective(s: The introduction of nucleic acids into cells for therapeutic objectives is significantly hindered by the size and charge of these molecules and therefore requires efficient vectors that assist cellular uptake. For several years great efforts have been devoted to the study of development of recombinant vectors based on biological domains with potential applications in gene therapy. Such vectors have been synthesized in genetically engineered approach, resulting in biomacromolecules with new properties that are not present in nature. Materials and Methods: In this study, we have designed new peptides using homology modeling with the purpose of overcoming the cell barriers for successful gene delivery through Bioinformatics tools. Three different carriers were designed and one of those with better score through Bioinformatics tools was cloned, expressed and its affinity for pDNA was monitored. Results: The resultszz demonstrated that the vector can effectively condense pDNAinto nanoparticles with the average sizes about 100 nm. Conclusion: We hope these peptides can overcome the biological barriers associated with gene transfer, and mediate efficient gene delivery.

  7. Genetic Diversity of Bacterial Communities and Gene Transfer Agents in Northern South China Sea

    Science.gov (United States)

    Sun, Fu-Lin; Wang, You-Shao; Wu, Mei-Lin; Jiang, Zhao-Yu; Sun, Cui-Ci; Cheng, Hao

    2014-01-01

    Pyrosequencing of the 16S ribosomal RNA gene (rDNA) amplicons was performed to investigate the unique distribution of bacterial communities in northern South China Sea (nSCS) and evaluate community structure and spatial differences of bacterial diversity. Cyanobacteria, Proteobacteria, Actinobacteria, and Bacteroidetes constitute the majority of bacteria. The taxonomic description of bacterial communities revealed that more Chroococcales, SAR11 clade, Acidimicrobiales, Rhodobacterales, and Flavobacteriales are present in the nSCS waters than other bacterial groups. Rhodobacterales were less abundant in tropical water (nSCS) than in temperate and cold waters. Furthermore, the diversity of Rhodobacterales based on the gene transfer agent (GTA) major capsid gene (g5) was investigated. Four g5 gene clone libraries were constructed from samples representing different regions and yielded diverse sequences. Fourteen g5 clusters could be identified among 197 nSCS clones. These clusters were also related to known g5 sequences derived from genome-sequenced Rhodobacterales. The composition of g5 sequences in surface water varied with the g5 sequences in the sampling sites; this result indicated that the Rhodobacterales population could be highly diverse in nSCS. Phylogenetic tree analysis result indicated distinguishable diversity patterns among tropical (nSCS), temperate, and cold waters, thereby supporting the niche adaptation of specific Rhodobacterales members in unique environments. PMID:25364820

  8. Hypothalamic gene transfer of BDNF inhibits breast cancer progression and metastasis in middle age obese mice.

    Science.gov (United States)

    Liu, Xianglan; McMurphy, Travis; Xiao, Run; Slater, Andrew; Huang, Wei; Cao, Lei

    2014-07-01

    Activation of the hypothalamus-adipocyte axis is associated with an antiobesity and anticancer phenotype in animal models of melanoma and colon cancer. Brain-derived neurotrophic factor (BDNF) is a key mediator in the hypothalamus leading to preferential sympathoneural activation of adipose tissue and the ensuing resistance to obesity and cancer. Here, we generated middle age obese mice by high fat diet feeding for a year and investigated the effects of hypothalamic gene transfer of BDNF on a hormone receptor-positive mammary tumor model. The recombinant adeno-associated viral vector-mediated overexpression of BDNF led to marked weight loss and decrease of adiposity without change of food intake. BDNF gene therapy improved glucose tolerance, alleviated steatosis, reduced leptin level, inhibited mouse breast cancer EO771 growth, and prevented the metastasis. The reduced tumor growth in BDNF-treated mice was associated with reduced angiogenesis, decreased proliferation, increased apoptosis, and reduced adipocyte recruitment and lipid accumulation. Moreover, BDNF gene therapy reduced inflammation markers in the hypothalamus, the mammary gland, the subcutaneous fat, and the mammary tumor. Our results suggest that manipulating a single gene in the brain may influence multiple mechanisms implicated in obesity-cancer association and provide a target for the prevention and treatment of both obesity and cancer.

  9. [Cloning, mutagenesis and symbiotic phenotype of three lipid transfer protein encoding genes from Mesorhizobium huakuii 7653R].

    Science.gov (United States)

    Li, Yanan; Zeng, Xiaobo; Zhou, Xuejuan; Li, Youguo

    2016-12-04

    Lipid transfer protein superfamily is involved in lipid transport and metabolism. This study aimed to construct mutants of three lipid transfer protein encoding genes in Mesorhizobium huakuii 7653R, and to study the phenotypes and function of mutations during symbiosis with Astragalus sinicus. We used bioinformatics to predict structure characteristics and biological functions of lipid transfer proteins, and conducted semi-quantitative and fluorescent quantitative real-time PCR to analyze the expression levels of target genes in free-living and symbiotic conditions. Using pK19mob insertion mutagenesis to construct mutants, we carried out pot plant experiments to observe symbiotic phenotypes. MCHK-5577, MCHK-2172 and MCHK-2779 genes encoding proteins belonged to START/RHO alpha_C/PITP/Bet_v1/CoxG/CalC (SRPBCC) superfamily, involved in lipid transport or metabolism, and were identical to M. loti at 95% level. Gene relative transcription level of the three genes all increased compared to free-living condition. We obtained three mutants. Compared with wild-type 7653R, above-ground biomass of plants and nodulenitrogenase activity induced by the three mutants significantly decreased. Results indicated that lipid transfer protein encoding genes of Mesorhizobium huakuii 7653R may play important roles in symbiotic nitrogen fixation, and the mutations significantly affected the symbiotic phenotypes. The present work provided a basis to study further symbiotic function mechanism associated with lipid transfer proteins from rhizobia.

  10. Repression/depression of conjugative plasmids and their influence on the mutation-selection balance in static environments.

    Directory of Open Access Journals (Sweden)

    Yoav Atsmon-Raz

    Full Text Available We study the effect that conjugation-mediated Horizontal Gene Transfer (HGT has on the mutation-selection balance of a population in a static environment. We consider a model whereby a population of unicellular organisms, capable of conjugation, comes to mutation-selection balance in the presence of an antibiotic, which induces a first-order death rate constant [Formula: see text] for genomes that are not resistant. We explicitly take into consideration the repression/de-repression dynamics of the conjugative plasmid, and assume that a de-repressed plasmid remains temporarily de-repressed after copying itself into another cell. We assume that both repression and de-repression are characterized by first-order rate constants [Formula: see text]and [Formula: see text], respectively. We find that conjugation has a deleterious effect on the mean fitness of the population, suggesting that HGT does not provide a selective advantage in a static environment, but is rather only useful for adapting to new environments. This effect can be ameliorated by repression, suggesting that while HGT is not necessarily advantageous for a population in a static environment, its deleterious effect on the mean fitness can be negated via repression. Therefore, it is likely that HGT is much more advantageous in a dynamic landscape. Furthermore, in the limiting case of a vanishing spontaneous de-repression rate constant, we find that the fraction of conjugators in the population undergoes a phase transition as a function of population density. Below a critical population density, the fraction of conjugators is zero, while above this critical population density the fraction of conjugators rises continuously to one. Our model for conjugation-mediated HGT is related to models of infectious disease dynamics, where the conjugators play the role of the infected (I class, and the non-conjugators play the role of the susceptible (S class.

  11. The Transcriptomes of Xiphinema index and Longidorus elongatus Suggest Independent Acquisition of Some Plant Parasitism Genes by Horizontal Gene Transfer in Early-Branching Nematodes.

    Science.gov (United States)

    Danchin, Etienne G J; Perfus-Barbeoch, Laetitia; Rancurel, Corinne; Thorpe, Peter; Da Rocha, Martine; Bajew, Simon; Neilson, Roy; Guzeeva, Elena Sokolova; Da Silva, Corinne; Guy, Julie; Labadie, Karine; Esmenjaud, Daniel; Helder, Johannes; Jones, John T; den Akker, Sebastian Eves-van

    2017-10-23

    Nematodes have evolved the ability to parasitize plants on at least four independent occasions, with plant parasites present in Clades 1, 2, 10 and 12 of the phylum. In the case of Clades 10 and 12, horizontal gene transfer of plant cell wall degrading enzymes from bacteria and fungi has been implicated in the evolution of plant parasitism. We have used ribonucleic acid sequencing (RNAseq) to generate reference transcriptomes for two economically important nematode species, Xiphinema index and Longidorus elongatus , representative of two genera within the early-branching Clade 2 of the phylum Nematoda. We used a transcriptome-wide analysis to identify putative horizontal gene transfer events. This represents the first in-depth transcriptome analysis from any plant-parasitic nematode of this clade. For each species, we assembled ~30 million Illumina reads into a reference transcriptome. We identified 62 and 104 transcripts, from X. index and L. elongatus , respectively, that were putatively acquired via horizontal gene transfer. By cross-referencing horizontal gene transfer prediction with a phylum-wide analysis of Pfam domains, we identified Clade 2-specific events. Of these, a GH12 cellulase from X. index was analysed phylogenetically and biochemically, revealing a likely bacterial origin and canonical enzymatic function. Horizontal gene transfer was previously shown to be a phenomenon that has contributed to the evolution of plant parasitism among nematodes. Our findings underline the importance and the extensiveness of this phenomenon in the evolution of plant-parasitic life styles in this speciose and widespread animal phylum.

  12. DNA-mediated gene transfer into human diploid fibroblasts derived from normal and ataxia-telangiectasia donors: parameters for DNA transfer and properties of DNA transformants

    International Nuclear Information System (INIS)

    Debenham, P.G.; Webb, M.B.T.; Masson, W.K.; Cox, R.

    1984-01-01

    An investigation was made of the feasibility of DNA-mediated gene transfer into human diploid fibroblasts derived from patients with the radiation sensitive syndrome ataxia-telangiectasia (A-T) and from a normal donor. Although they are markedly different in their growth characteristics, both normal and A-T strains give similar frequencies for DNA transfer in a model system using the recombinant plasmid pSV2-gpt. pSV2-gpt DNA transformants arise with a frequency between 10 -5 and 10 -4 per viable cell. Analysis of such transformants, although possible, is severely handicapped by the limited clonal life span of diploid human cells. Despite these problems it may be concluded that diploid human fibroblasts are competent recipients for DNA-mediated gene transfer and the putative repair deficiency of A-T does not markedly effect the efficiency of this process. (author)

  13. Microbial co-habitation and lateral gene transfer: what transposases can tell us

    Energy Technology Data Exchange (ETDEWEB)

    Hooper, Sean D.; Mavromatis, Konstantinos; Kyrpides, Nikos C.

    2009-03-01

    Determining the habitat range for various microbes is not a simple, straightforward matter, as habitats interlace, microbes move between habitats, and microbial communities change over time. In this study, we explore an approach using the history of lateral gene transfer recorded in microbial genomes to begin to answer two key questions: where have you been and who have you been with? All currently sequenced microbial genomes were surveyed to identify pairs of taxa that share a transposase that is likely to have been acquired through lateral gene transfer. A microbial interaction network including almost 800 organisms was then derived from these connections. Although the majority of the connections are between closely related organisms with the same or overlapping habitat assignments, numerous examples were found of cross-habitat and cross-phylum connections. We present a large-scale study of the distributions of transposases across phylogeny and habitat, and find a significant correlation between habitat and transposase connections. We observed cases where phylogenetic boundaries are traversed, especially when organisms share habitats; this suggests that the potential exists for genetic material to move laterally between diverse groups via bridging connections. The results presented here also suggest that the complex dynamics of microbial ecology may be traceable in the microbial genomes.

  14. Comparison of lentiviral and sleeping beauty mediated αβ T cell receptor gene transfer.

    Directory of Open Access Journals (Sweden)

    Anne-Christine Field

    Full Text Available Transfer of tumour antigen-specific receptors to T cells requires efficient delivery and integration of transgenes, and currently most clinical studies are using gamma retroviral or lentiviral systems. Whilst important proof-of-principle data has been generated for both chimeric antigen receptors and αβ T cell receptors, the current platforms are costly, time-consuming and relatively inflexible. Alternative, more cost-effective, Sleeping Beauty transposon-based plasmid systems could offer a pathway to accelerated clinical testing of a more diverse repertoire of recombinant high affinity T cell receptors. Nucleofection of hyperactive SB100X transposase-mediated stable transposition of an optimised murine-human chimeric T cell receptor specific for Wilm's tumour antigen from a Sleeping Beauty transposon plasmid. Whilst transfer efficiency was lower than that mediated by lentiviral transduction, cells could be readily enriched and expanded, and mediated effective target cells lysis in vitro and in vivo. Integration sites of transposed TCR genes in primary T cells were almost randomly distributed, contrasting the predilection of lentiviral vectors for transcriptionally active sites. The results support exploitation of the Sleeping Beauty plasmid based system as a flexible and adaptable platform for accelerated, early-phase assessment of T cell receptor gene therapies.

  15. Cellular Immune Response Against Firefly Luciferase After Sleeping Beauty–Mediated Gene Transfer In Vivo

    Science.gov (United States)

    Podetz-Pedersen, Kelly M.; Vezys, Vaiva; Somia, Nikunj V.; Russell, Stephen J.

    2014-01-01

    Abstract The Sleeping Beauty (SB) transposon system has been shown to mediate new gene sequence integration resulting in long-term expression. Here the effectiveness of hyperactive SB100X transposase was tested, and we found that hydrodynamic co-delivery of a firefly luciferase transposon (pT2/CaL) along with SB100X transposase (pCMV-SB100X) resulted in remarkably sustained, high levels of luciferase expression. However, after 4 weeks there was a rapid, animal-by-animal loss of luciferase expression that was not observed in immunodeficient mice. We hypothesized that this sustained, high-level luciferase expression achieved using the SB100X transposase elicits an immune response in pT2/CaL co-administered mice, which was supported by the rapid loss of luciferase expression upon challenge of previously treated animals and in naive animals adoptively transferred with splenocytes from previously treated animals. Specificity of the immune response to luciferase was demonstrated by increased cytokine expression in splenocytes after exposure to luciferase peptide in parallel with MHC I–luciferase peptide tetramer binding. This anti-luciferase immune response observed following continuous, high-level luciferase expression in vivo clearly impacts its use as an in vivo reporter. As both an immunogen and an extremely sensitive reporter, luciferase is also a useful model system for the study of immune responses following in vivo gene transfer and expression. PMID:25093708

  16. Vesicular stomatitis virus enables gene transfer and transsynaptic tracing in a wide range of organisms.

    Science.gov (United States)

    Mundell, Nathan A; Beier, Kevin T; Pan, Y Albert; Lapan, Sylvain W; Göz Aytürk, Didem; Berezovskii, Vladimir K; Wark, Abigail R; Drokhlyansky, Eugene; Bielecki, Jan; Born, Richard T; Schier, Alexander F; Cepko, Constance L

    2015-08-01

    Current limitations in technology have prevented an extensive analysis of the connections among neurons, particularly within nonmammalian organisms. We developed a transsynaptic viral tracer originally for use in mice, and then tested its utility in a broader range of organisms. By engineering the vesicular stomatitis virus (VSV) to encode a fluorophore and either the rabies virus glycoprotein (RABV-G) or its own glycoprotein (VSV-G), we created viruses that can transsynaptically label neuronal circuits in either the retrograde or anterograde direction, respectively. The vectors were investigated for their utility as polysynaptic tracers of chicken and zebrafish visual pathways. They showed patterns of connectivity consistent with previously characterized visual system connections, and revealed several potentially novel connections. Further, these vectors were shown to infect neurons in several other vertebrates, including Old and New World monkeys, seahorses, axolotls, and Xenopus. They were also shown to infect two invertebrates, Drosophila melanogaster, and the box jellyfish, Tripedalia cystophora, a species previously intractable for gene transfer, although no clear evidence of transsynaptic spread was observed in these species. These vectors provide a starting point for transsynaptic tracing in most vertebrates, and are also excellent candidates for gene transfer in organisms that have been refractory to other methods. © 2015 Wiley Periodicals, Inc.

  17. Dual effects of adenovirus-mediated thrombopoietin gene transfer on hepatic oval cell proliferation and platelet counts

    International Nuclear Information System (INIS)

    Ichiba, Miho; Shimomura, Takashi; Murai, Rie; Hashiguchi, Koichi; Saeki, Toshiya; Yoshida, Yoko; Kanbe, Takamasa; Tanabe, Naotada; Tsuchiya, Hiroyuki; Miura, Norimasa; Tajima, Fumihito; Kurimasa, Akihiro; Hamada, Hirofumi; Shiota, Goshi

    2005-01-01

    Thrombopoietin (TPO) is the growth factor for megakaryocytes and platelets, however, it also acts as a potent regulator of stem cell proliferation. To examine the significance of TPO expression in proliferation of hepatic oval cells, the effect of adenovirus-mediated TPO gene transfer into livers of the Solt-Farber model, which mimics the condition where liver regeneration is impaired, was examined. Hepatic TPO mRNA peaked its expression at 2 days after gene transduction and then gradually decreased. The peripheral platelet number began to increase at 4 days (P < 0.05) and reached its plateau at 9 days (P < 0.01). Oval cells expressed c-Mpl, a receptor for TPO as well as immature hematopoietic and hepatocytic surface markers such as CD34 and AFP. The proliferating cell nuclear antigen-positive oval cells in rats into which adenovirus-TPO gene was transferred at 7 and 9 days were significantly greater than those in adenovirus-LacZ gene transferred (P < 0.05, each), and the total numbers of oval cells in the adenovirus-TPO gene transferred at 9 and 13 days were also significantly greater than those in adenovirus-LacZ gene transferred (P < 0.05, each). Expression of SCF protein was increased at 4, 7, and 9 days by TPO gene administration and that of c-Kit was increased at 4 and 7 days. These data suggest that adenovirus-mediated TPO gene transfer stimulated oval cell proliferation in liver as well as increasing peripheral platelet counts, emphasizing the significance of the TPO/c-Mpl system in proliferation of hepatic oval cells

  18. Heat-transfer-based detection of SNPs in the PAH gene of PKU patients

    Directory of Open Access Journals (Sweden)

    Vanden Bon N

    2014-03-01

    Full Text Available Natalie Vanden Bon,1 Bart van Grinsven,2 Mohammed Sharif Murib,2 Weng Siang Yeap,2 Ken Haenen,2,3 Ward De Ceuninck,2,3 Patrick Wagner,2,3 Marcel Ameloot,1 Veronique Vermeeren,1 Luc Michiels11Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium; 2Institute for Materials Research, Hasselt University, Diepenbeek, Belgium; 3IMOMEC, Diepenbeek, BelgiumAbstract: Conventional neonatal diagnosis of phenylketonuria is based on the presence of abnormal levels of phenylalanine in the blood. However, for carrier detection and prenatal diagnosis, direct detection of disease-correlated mutations is needed. To speed up and simplify mutation screening in genes, new technologies are developed. In this study, a heat-transfer method is evaluated as a mutation-detection technology in entire exons of the phenylalanine hydroxylase (PAH gene. This method is based on the change in heat-transfer resistance (Rth upon thermal denaturation of dsDNA (double-stranded DNA on nanocrystalline diamond. First, ssDNA (single-stranded DNA fragments that span the size range of the PAH exons were successfully immobilized on nanocrystalline diamond. Next, it was studied whether an Rth change could be observed during the thermal denaturation of these DNA fragments after hybridization to their complementary counterpart. A clear Rth shift during the denaturation of exon 5, exon 9, and exon 12 dsDNA was observed, corresponding to lengths of up to 123 bp. Finally, Rth was shown to detect prevalent single-nucleotide polymorphisms, c.473G>A (R158Q, c.932T>C (p.L311P, and c.1222C>T (R408W, correlated with phenylketonuria, displaying an effect related to the different melting temperatures of homoduplexes and heteroduplexes.Keywords: mutation detection, heat-transfer resistance, melting temperature, nanocrystalline diamond, persistence length

  19. Efficiency of RAFT-synthesized PDMAEMA in gene transfer to the retina.

    Science.gov (United States)

    Bitoque, Diogo B; Simão, Sónia; Oliveira, Ana V; Machado, Susana; Duran, Margarita R; Lopes, Eduardo; da Costa, Ana M Rosa; Silva, Gabriela A

    2017-01-01

    Gene therapy has long been heralded as the new hope to evolve from symptomatic care of genetic pathologies to a full cure. Recent successes in using gene therapy for treating several ocular and haematopoietic pathologies have shown the great potential of this approach that, in the early days, relied on the use of viral vectors, which were considered by many to be undesirable for human treatment. Therefore, there is considerable interest and effort in developing non-viral vectors, with efficiency close to that of viral vectors. The aim of this study was to develop suitable non-viral carriers for gene therapy to treat pathologies affecting the retina. In this study poly(2-(N,N-dimethylamino)ethyl methacrylate), PDMAEMA was synthesized by reversible addition-fragmentation chain transfer (RAFT) and the in vitro cytocompatibility and transfection efficiency of a range of polymer:DNA ratios evaluated using a retinal cell line; in vivo biocompatibility was evaluated by ocular injection in C57BL/6 mice. The results showed that through RAFT, it is possible to produce a defined-size polymer that is compatible with cell viability in vitro and capable of efficiently directing gene expression in a polymer-DNA ratio-dependent manner. When injected into the eyes of mice, these vectors induced a transient, mild inflammation, characteristic of the implantation of medical devices. These results form the basis of future studies where RAFT-synthesized PDMAEMA will be used to deliver gene expression systems to the retina of mouse models of retinal pathologies. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

  20. Factors enhancing Agrobacterium tumefaciens-mediated gene transfer in peanut (Arachis hypogaea L.)

    Science.gov (United States)

    Egnin, M.; Mora, A.; Prakash, C. S.; Mortley, D. G. (Principal Investigator)

    1998-01-01

    Parameters enhancing Agrobacterium-mediated transfer of foreign genes to peanut (Arachis hypogaea L.) cells were investigated. An intron-containing beta-glucuronidase uidA (gusA) gene under the transcriptional control of CaMV 35S promoter served as a reporter. Transformation frequency was evaluated by scoring the number of sectors expressing GUS activity on leaf and epicotyl explants. The 'Valencia Select' market type cv. New Mexico was more amenable to Agrobacterium transformation than the 'runner' market type cultivars tested (Florunner, Georgia Runner, Sunrunner, or South Runner). The disarmed Agrobacterium tumefaciens strain EHA101 was superior in facilitating the transfer of uidA gene to peanut cells compared to the disarmed strain C58. Rinsing of explants in half-strength Murashige-Skoog (MS) media prior to infection by Agrobacterium significantly increased the transformation efficiency. The use of cocultivation media containing high auxin [1.0 or 2.5 mg/l (4.53 micromolar or 11.31 micromolar) 2,4-D] and low cytokinin [0.25 or 0.5 mg/l (1.0 micromolar or 2.0 micromolar) BA] promoted higher transformation than either hormone-free or thidiazuron-containing medium. The polarity of the epicotyl during cocultivation was important; explants incubated in an inverted (vertically) manner followed by a vertically upright position resulted in improved transformation and shoot regeneration frequencies. Preculture of explants in MS basal medium or with 2.5 mg thidiazuron per l prior to infection drastically decreased the number of transformed zones. The optimized protocol was used to obtain transient transformation frequencies ranging from 12% to 36% for leaf explants, 15% to 42% for epicotyls. Initial evidence of transformation was obtained by polymerase chain reaction and subsequently confirmed by Southern analysis of regenerated plants.

  1. Retroviral-mediated transfer and expression of human β-globin genes in cultured murine and human erythroid cells

    International Nuclear Information System (INIS)

    Weber-Benarous, A.; Cone, R.D.; London, I.M.; Mulligan, R.C.

    1988-01-01

    The authors cloned human β-globin DNA sequences from a genomic library prepared from DNA isolated from the human leukemia cell line K562 and have used the retroviral vector pZip-NeoSV(X)1 to introduce a 3.0-kilobase segment encompassing the globin gene into mouse erythroleukemia cells. Whereas the endogenous K562 β-globin gene is repressed in K562 cells, when introduced into mouse erythroleukemia cells by retroviral-mediated gene transfer, the β-globin gene from K562 cells was transcribed and induced 5-20-fold after treatment of the cells with dimethyl sulfoxide. The transcripts were correctly initiated, and expression and regulation of the K562 gene were identical to the expression of a normal human β-globin gene transferred into mouse erythroleukemia cells in the same way. They have also introduced the normal human β-globin gene into K562 cells using the same retrovirus vector. SP6 analysis of the RNA isolated from the transduced cells showed that the normal β-globin gene was transcribed at a moderately high level, before or after treatment with hemin. Based on these data, they suggest that the lack of expression of the endogenous β-globin gene in K562 cells does not result from an alteration in the gene itself and may not result from a lack of factor(s) necessary for β-lobin gene transcription. Retroviral-mediated transfer of the human β-globin gene may, however, uniquely influence expression of the gene K562 cells

  2. Transfer of Antibiotic Resistance in Staphylococcus aureus

    DEFF Research Database (Denmark)

    Haaber, Jakob; Penadés, José R; Ingmer, Hanne

    2017-01-01

    Staphylococcus aureus is a serious human pathogen with remarkable adaptive powers. Antibiotic-resistant clones rapidly emerge mainly by acquisition of antibiotic-resistance genes from other S. aureus strains or even from other genera. Transfer is mediated by a diverse complement of mobile genetic...... of plasmids that can be transferred by conjugation and the efficiency with which transduction occurs. Here, we review the main routes of antibiotic resistance gene transfer in S. aureus in the context of its biology as a human commensal and a life-threatening pathogen. Staphylococcus aureus cells...... are effective in exchanging mobile genetic elements, including antibiotic-resistance genes.During colonization or infection of host organisms, the exchange appears to be particularly effective.Bacteriophage-mediated transfer involves both transduction and autotransduction, which may enable lysogenic S. aureus...

  3. TRANSFER

    African Journals Online (AJOL)

    This paper reports on further studies on long range energy transfer between curcumine as donor and another thiazine dye, thionine, which is closely related to methylene blue as energy harvester (Figure 1). Since thionine is known to have a higher quantum yield of singlet oxygen sensitization than methylene blue [8], it is ...

  4. Polygalacturonase from Sitophilus oryzae: Possible horizontal transfer of a pectinase gene from fungi to weevils

    Directory of Open Access Journals (Sweden)

    Zhicheng Shen

    2003-08-01

    Full Text Available Endo-polygalacturonase, one of the group of enzymes known collectively as pectinases, is widely distributed in bacteria, plants and fungi. The enzyme has also been found in several weevil species and a few other insects, such as aphids, but not in Drosophila melanogaster, Anopheles gambiae, or Caenorhabditis elegans or, as far as is known, in any more primitive animal species. What, then, is the genetic origin of the polygalacturonases in weevils? Since some weevil species harbor symbiotic microorganisms, it has been suggested, reasonably, that the symbionts' genomes of both aphids and weevils, rather than the insects' genomes, could encode polygalacturonase. We report here the cloning of a cDNA that encodes endo-polygalacturonase in the rice weevil, Sitophilus oryzae (L., and investigations based on the cloned cDNA. Our results, which include analysis of genes in antibiotic-treated rice weevils, indicate that the enzyme is, in fact, encoded by the insect genome. Given the apparent absence of the gene in much of the rest of the animal kingdom, it is therefore likely that the rice weevil polygalacturonase gene was incorporated into the weevil's genome by horizontal transfer, possibly from a fungus.

  5. Gene Transfer of Brain-derived Neurotrophic Factor (BDNF) Prevents Neurodegeneration Triggered by FXN Deficiency.

    Science.gov (United States)

    Katsu-Jiménez, Yurika; Loría, Frida; Corona, Juan Carlos; Díaz-Nido, Javier

    2016-05-01

    Friedreich's ataxia is a predominantly neurodegenerative disease caused by recessive mutations that produce a deficiency of frataxin (FXN). Here, we have used a herpesviral amplicon vector carrying a gene encoding for brain-derived neurotrophic factor (BDNF) to drive its overexpression in neuronal cells and test for its effect on FXN-deficient neurons both in culture and in the mouse cerebellum in vivo. Gene transfer of BDNF to primary cultures of mouse neurons prevents the apoptosis which is triggered by the knockdown of FXN gene expression. This neuroprotective effect of BDNF is also observed in vivo in a viral vector-based knockdown mouse cerebellar model. The injection of a lentiviral vector carrying a minigene encoding for a FXN-specific short hairpin ribonucleic acid (shRNA) into the mouse cerebellar cortex triggers a FXN deficit which is accompanied by significant apoptosis of granule neurons as well as loss of calbindin in Purkinje cells. These pathological changes are accompanied by a loss of motor coordination of mice as assayed by the rota-rod test. Coinjection of a herpesviral vector encoding for BDNF efficiently prevents both the development of cerebellar neuropathology and the ataxic phenotype. These data demonstrate the potential therapeutic usefulness of neurotrophins like BDNF to protect FXN-deficient neurons from degeneration.

  6. Horizontal gene transfer versus biostimulation: A strategy for bioremediation in Goa.

    Science.gov (United States)

    Pasumarthi, Rajesh; Mutnuri, Srikanth

    2016-12-15

    Bioaugmentation, Biostimulation and Horizontal gene transfer (HGT) of catabolic genes have been proven for their role in bioremediation of hydrocarbons. It also has been proved that selection of either biostimulation or bioremediation varies for every contaminated site. The reliability of HGT compared to biostimulation and bioremediation was not tested. The present study focuses on reliability of biostimulatiion, bioaugmentation and HGT during biodegradation of Diesel oil and Non aqueous phase liquids (NAPL). Pseudomonas aeruginosa (AEBBITS1) having alkB and NDO genes was used for bioaugmentation and the experiment was conducted using seawater as medium. Based on Gas chromatography results diesel was found to be degraded to 100% in both presence and absence of AEBBITS1. Denturing gradient gel electrophoresis result showed same pattern in presence and absence of AEBBITS1 indicating no HGT. NAPL degradation was found to be more by Biostimulated Bioaugmentation compared to biostimulation and bioaugmentation alone. This proves that biostimulated bioaugmentation is better strategy for oil contamination (tarabll) in Velsao beach, Goa. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Microfluidic Transduction Harnesses Mass Transport Principles to Enhance Gene Transfer Efficiency.

    Science.gov (United States)

    Tran, Reginald; Myers, David R; Denning, Gabriela; Shields, Jordan E; Lytle, Allison M; Alrowais, Hommood; Qiu, Yongzhi; Sakurai, Yumiko; Li, William C; Brand, Oliver; Le Doux, Joseph M; Spencer, H Trent; Doering, Christopher B; Lam, Wilbur A

    2017-10-04

    Ex vivo gene therapy using lentiviral vectors (LVs) is a proven approach to treat and potentially cure many hematologic disorders and malignancies but remains stymied by cumbersome, cost-prohibitive, and scale-limited production processes that cannot meet the demands of current clinical protocols for widespread clinical utilization. However, limitations in LV manufacture coupled with inefficient transduction protocols requiring significant excess amounts of vector currently limit widespread implementation. Herein, we describe a microfluidic, mass transport-based approach that overcomes the diffusion limitations of current transduction platforms to enhance LV gene