Science.gov

Sample records for gene transfer stability

  1. Histidine-rich stabilized polyplexes for cMet-directed tumor-targeted gene transfer

    NASA Astrophysics Data System (ADS)

    Kos, Petra; Lächelt, Ulrich; Herrmann, Annika; Mickler, Frauke Martina; Döblinger, Markus; He, Dongsheng; Krhač Levačić, Ana; Morys, Stephan; Bräuchle, Christoph; Wagner, Ernst

    2015-03-01

    Overexpression of the hepatocyte growth factor receptor/c-Met proto oncogene on the surface of a variety of tumor cells gives an opportunity to specifically target cancerous tissues. Herein, we report the first use of c-Met as receptor for non-viral tumor-targeted gene delivery. Sequence-defined oligomers comprising the c-Met binding peptide ligand cMBP2 for targeting, a monodisperse polyethylene glycol (PEG) for polyplex surface shielding, and various cationic (oligoethanamino) amide cores containing terminal cysteines for redox-sensitive polyplex stabilization, were assembled by solid-phase supported syntheses. The resulting oligomers exhibited a greatly enhanced cellular uptake and gene transfer over non-targeted control sequences, confirming the efficacy and target-specificity of the formed polyplexes. Implementation of endosomal escape-promoting histidines in the cationic core was required for gene expression without additional endosomolytic agent. The histidine-enriched polyplexes demonstrated stability in serum as well as receptor-specific gene transfer in vivo upon intratumoral injection. The co-formulation with an analogous PEG-free cationic oligomer led to a further compaction of pDNA polyplexes with an obvious change of shape as demonstrated by transmission electron microscopy. Such compaction was critically required for efficient intravenous gene delivery which resulted in greatly enhanced, cMBP2 ligand-dependent gene expression in the distant tumor.Overexpression of the hepatocyte growth factor receptor/c-Met proto oncogene on the surface of a variety of tumor cells gives an opportunity to specifically target cancerous tissues. Herein, we report the first use of c-Met as receptor for non-viral tumor-targeted gene delivery. Sequence-defined oligomers comprising the c-Met binding peptide ligand cMBP2 for targeting, a monodisperse polyethylene glycol (PEG) for polyplex surface shielding, and various cationic (oligoethanamino) amide cores containing

  2. Emergence of collective territorial defense in bacterial communities: horizontal gene transfer can stabilize microbiomes.

    PubMed

    Juhász, János; Kertész-Farkas, Attila; Szabó, Dóra; Pongor, Sándor

    2014-01-01

    Multispecies bacterial communities such as the microbiota of the gastrointestinal tract can be remarkably stable and resilient even though they consist of cells and species that compete for resources and also produce a large number of antimicrobial agents. Computational modeling suggests that horizontal transfer of resistance genes may greatly contribute to the formation of stable and diverse communities capable of protecting themselves with a battery of antimicrobial agents while preserving a varied metabolic repertoire of the constituent species. In other words horizontal transfer of resistance genes makes a community compatible in terms of exoproducts and capable to maintain a varied and mature metagenome. The same property may allow microbiota to protect a host organism, or if used as a microbial therapy, to purge pathogens and restore a protective environment. PMID:24755769

  3. Adenoviral gene transfer into the normal and injured spinal cord: enhanced transgene stability by combined administration of temperature-sensitive virus and transient immune blockade.

    PubMed

    Romero, M I; Smith, G M

    1998-12-01

    This study characterized gene transfer into both normal and injured adult rat dorsal spinal cord using first (E1-/E3-) or second (E1-/E2A125/E3-, temperature-sensitive; ts) generation of replication-defective adenoviral (Ad) vectors. A novel immunosuppressive regimen aimed at blocking CD4/CD45 lymphocytic receptors was tested for improving transgene persistence. In addition, the effect of gene transfer on nociception was also evaluated. Seven days after treatment, numerous LacZ-positive cells were observed after transfection with either viral vector. By 21 days after transfection, beta-galactosidase staining was reduced and suggestive of ongoing cytopathology in both Ad-treated groups, despite the fact that the immunogenicity of LacZ/Adts appeared less when compared with that elicited by the LacZ/Ad vector. In contrast, immunosuppressed animals showed a significant (P < or = 0.05) increase in the number of LacZ-positive cells not displaying cytopathology. In these animals, a concomitant reduction in numbers of macrophages/microglia and CD4 and CD8 lymphocytes was observed. Only animals that received LacZ/Adts and immunosuppression showed transgene expression after 60 days. Similar results were observed in animals in which the L4-L5 dorsal roots were lesioned before transfection. Gene transfer into the dorsal spinal cord did not affect nociception, independent of the adenovirus vector. These results indicate that immune blockade of the CD4/CD45 lymphocytic receptors enhanced transgene stability in adult animals with normal or injured spinal cords and that persistent transgene expression in the spinal cord does not interfere with normal neural function. PMID:10023440

  4. Lateral gene transfer in eukaryotes.

    PubMed

    Andersson, J O

    2005-06-01

    Lateral gene transfer -- the transfer of genetic material between species -- has been acknowledged as a major mechanism in prokaryotic genome evolution for some time. Recently accumulating data indicate that the process also occurs in the evolution of eukaryotic genomes. However, there are large rate variations between groups of eukaryotes; animals and fungi seem to be largely unaffected, with a few exceptions, while lateral gene transfer frequently occurs in protists with phagotrophic lifestyles, possibly with rates comparable to prokaryotic organisms. Gene transfers often facilitate the acquisition of functions encoded in prokaryotic genomes by eukaryotic organisms, which may enable them to colonize new environments. Transfers between eukaryotes also occur, mainly into larger phagotrophic eukaryotes that ingest eukaryotic cells, but also between plant lineages. These findings have implications for eukaryotic genomic research in general, and studies of the origin and phylogeny of eukaryotes in particular. PMID:15761667

  5. Gene Transfer into Cardiac Myocytes

    PubMed Central

    Lang, Sarah E.; Westfall, Margaret V.

    2016-01-01

    Traditional methods for DNA transfection are often inefficient and toxic for terminally differentiated cells, such as cardiac myocytes. Vector-based gene transfer is an efficient approach for introducing exogenous cDNA into these types of primary cell cultures. In this chapter, separate protocols for adult rat cardiac myocyte isolation and gene transfer with recombinant adenovirus are provided and are routinely utilized for studying the effects of sarcomeric proteins on myofilament function. PMID:25836585

  6. Gene transfer for erythropoiesis enhancement.

    PubMed

    Naffakh, N; Danos, O

    1996-08-01

    The spectrum of anemias treated with recombinant human erythropoietin is rapidly broadening. Lifelong treatment with very high doses is now under evaluation for beta-thalassemia and sickle cell anemia. These indications make it worthwhile to search for methods that will allow a permanent systemic delivery of the hormone. Here, we review experimental gene-transfer-based procedures for erythropoietin delivery in vivo. In mice, both ex vivo and direct in vivo approaches for gene transfer have resulted in the long-term production of therapeutic levels of the hormone. Gene transfer of erythropoietin could become a viable alternative to the injection of the purified recombinant protein once reliable procedures for controlling transgene expression are available. PMID:8796920

  7. Gene transfer: transduction.

    PubMed

    Frangipani, Emanuela

    2014-01-01

    Bacteriophages able to propagate on Pseudomonas strains are very common and can be easily isolated from natural environments or lysogenic strains. The development of transducing systems has allowed bacterial geneticists to perform chromosome analyses and mutation mapping. Moreover, these systems have also been proved to be a successful tool for molecular microbiologists to introduce a foreign gene or a mutation into the chromosome of a bacterial cell. This chapter provides a description of the phage methodology illustrated by Adams in 1959 and applicable to strain PAO1 derivatives. PMID:24818891

  8. Gene transfer in intact animals

    NASA Astrophysics Data System (ADS)

    Cline, M. J.; Stang, H.; Mercola, K.; Morse, L.; Ruprecht, R.; Browne, J.; Salser, W.

    1980-04-01

    Resistance to methotrexate was induced in bone marrow cells of mice by transformation in vitro with DNA from a drug-resistant cell line. Transformed cells were injected in vivo and haematopoietic cells expressing resistance were selected by drug treatment of recipients. Transformed cells had elevated levels of dihydrofolate reductase and demonstrated a proliferative advantage over untransformed cells, indicating successful gene transfer.

  9. Horizontal gene transfer in plants.

    PubMed

    Gao, Caihua; Ren, Xiaodong; Mason, Annaliese S; Liu, Honglei; Xiao, Meili; Li, Jiana; Fu, Donghui

    2014-03-01

    Horizontal gene transfer (HGT) describes the transmission of genetic material across species boundaries. HGT often occurs in microbic and eukaryotic genomes. However, the pathways by which HGTs occur in multicellular eukaryotes, especially in plants, are not well understood. We systematically summarized more than ten possible pathways for HGT. The intimate contact which frequently occurs in parasitism, symbiosis, pathogen, epiphyte, entophyte, and grafting interactions could promote HGTs between two species. Besides these direct transfer methods, genes can be exchanged with a vector as a bridge: possible vectors include pollen, fungi, bacteria, viruses, viroids, plasmids, transposons, and insects. HGT, especially when involving horizontal transfer of transposable elements, is recognized as a significant force propelling genomic variation and biological innovation, playing an important functional and evolutionary role in both eukaryotic and prokaryotic genomes. We proposed possible mechanisms by which HGTs can occur, which is useful in understanding the genetic information exchange among distant species or distant cellular components. PMID:24132513

  10. Viral Vectors for in Vivo Gene Transfer

    NASA Astrophysics Data System (ADS)

    Thévenot, E.; Dufour, N.; Déglon, N.

    The transfer of DNA into the nucleus of a eukaryotic cell (gene transfer) is a central theme of modern biology. The transfer is said to be somatic when it refers to non-germline organs of a developed individual, and germline when it concerns gametes or the fertilised egg of an animal, with the aim of transmitting the relevant genetic modification to its descendents [1]. The efficient introduction of genetic material into a somatic or germline cell and the control of its expression over time have led to major advances in understanding how genes work in vivo, i.e., in living organisms (functional genomics), but also to the development of innovative therapeutic methods (gene therapy). The efficiency of gene transfer is conditioned by the vehicle used, called the vector. Desirable features for a vector are as follows: Easy to produce high titer stocks of the vector in a reproducible way. Absence of toxicity related to transduction (transfer of genetic material into the target cell, and its expression there) and no immune reaction of the organism against the vector and/or therapeutic protein. Stability in the expression of the relevant gene over time, and the possibility of regulation, e.g., to control expression of the therapeutic protein on the physiological level, or to end expression at the end of treatment. Transduction of quiescent cells should be as efficient as transduction of dividing cells. Vectors currently used fall into two categories: non-viral and viral vectors. In non-viral vectors, the DNA is complexed with polymers, lipids, or cationic detergents (described in Chap. 3). These vectors have a low risk of toxicity and immune reaction. However, they are less efficient in vivo than viral vectors when it comes to the number of cells transduced and long-term transgene expression. (Naked DNA transfer or electroporation is rather inefficient in the organism. This type of gene transfer will not be discussed here, and the interested reader is referred to the

  11. Problems associated with gene transfer and opportunities for microgravity environments

    NASA Astrophysics Data System (ADS)

    Tennessen, Daniel J.

    1997-01-01

    The method of crop improvement by gene transfer is becoming increasingly routine with transgenic foods and ornamental crops now being marketed to consumers. However, biological processes of plants, and the physical barriers of current protocols continue to limit the application of gene transfer in many commercial crops. The goal of this paper is to outline the current limitations of gene transfer and to hypothesize possible opportunities for use of microgravity to overcome such limitations. The limitations detailed in this paper include host-range specificity of Agrobacterium mediated transformation, probability of gene insertion, position effects of the inserted genes, gene copy number, stability of foreign gene expression in host plants, and regeneration of recalcitrant plant species. Microgravity offers an opportunity for gene transfer where cell growth kinetics, DNA synthesis, and genetic recombination rates can be altered. Such biological conditions may enhance the ability for recombination of reporter genes and other genes of interest to agriculture. Proposed studies would be useful for understanding instability of foreign gene expression and may lead to stable transformed plants. Other aspects of gene transfer in microgravity are discussed.

  12. The stability and degradation of dietary DNA in the gastrointestinal tract of mammals: implications for horizontal gene transfer and the biosafety of GMOs.

    PubMed

    Rizzi, Aurora; Raddadi, Noura; Sorlini, Claudia; Nordgrd, Lise; Nielsen, Kaare Magne; Daffonchio, Daniele

    2012-01-01

    The fate of dietary DNA in the gastrointestinal tract (GIT) of animals has gained renewed interest after the commercial introduction of genetically modified organisms (GMO). Among the concerns regarding GM food, are the possible consequences of horizontal gene transfer (HGT) of recombinant dietary DNA to bacteria or animal cells. The exposure of the GIT to dietary DNA is related to the extent of food processing, food composition, and to the level of intake. Animal feeding studies have demonstrated that a minor amount of fragmented dietary DNA may resist the digestive process. Mammals have been shown to take up dietary DNA from the GIT, but stable integration and expression of internalized DNA has not been demonstrated. Despite the ability of several bacterial species to acquire external DNA by natural transformation, in vivo transfer of dietary DNA to bacteria in the intestine has not been detected in the few experimental studies conducted so far. However, major methodological limitations and knowledge gaps of the mechanistic aspects of HGT calls for methodological improvements and further studies to understand the fate of various types of dietary DNA in the GIT. PMID:22059960

  13. Lateral Gene Transfer from the Dead

    PubMed Central

    Szöllősi, Gergely J.; Tannier, Eric; Lartillot, Nicolas; Daubin, Vincent

    2013-01-01

    In phylogenetic studies, the evolution of molecular sequences is assumed to have taken place along the phylogeny traced by the ancestors of extant species. In the presence of lateral gene transfer, however, this may not be the case, because the species lineage from which a gene was transferred may have gone extinct or not have been sampled. Because it is not feasible to specify or reconstruct the complete phylogeny of all species, we must describe the evolution of genes outside the represented phylogeny by modeling the speciation dynamics that gave rise to the complete phylogeny. We demonstrate that if the number of sampled species is small compared with the total number of existing species, the overwhelming majority of gene transfers involve speciation to and evolution along extinct or unsampled lineages. We show that the evolution of genes along extinct or unsampled lineages can to good approximation be treated as those of independently evolving lineages described by a few global parameters. Using this result, we derive an algorithm to calculate the probability of a gene tree and recover the maximum-likelihood reconciliation given the phylogeny of the sampled species. Examining 473 near-universal gene families from 36 cyanobacteria, we find that nearly a third of transfer events (28%) appear to have topological signatures of evolution along extinct species, but only approximately 6% of transfers trace their ancestry to before the common ancestor of the sampled cyanobacteria. [Gene tree reconciliation; lateral gene transfer; macroevolution; phylogeny.] PMID:23355531

  14. Horizontal gene transfer between bacteria and animals.

    PubMed

    Dunning Hotopp, Julie C

    2011-04-01

    Horizontal gene transfer is increasingly described between bacteria and animals. Such transfers that are vertically inherited have the potential to influence the evolution of animals. One classic example is the transfer of DNA from mitochondria and chloroplasts to the nucleus after the acquisition of these organelles by eukaryotes. Even today, many of the described instances of bacteria-to-animal transfer occur as part of intimate relationships such as those of endosymbionts and their invertebrate hosts, particularly insects and nematodes, while numerous transfers are also found in asexual animals. Both of these observations are consistent with modern evolutionary theory, in particular the serial endosymbiotic theory and Muller's ratchet. Although it is tempting to suggest that these particular lifestyles promote horizontal gene transfer, it is difficult to ascertain given the nonrandom sampling of animal genome sequencing projects and the lack of a systematic analysis of animal genomes for such transfers. PMID:21334091

  15. High expression hampers horizontal gene transfer.

    PubMed

    Park, Chungoo; Zhang, Jianzhi

    2012-01-01

    Horizontal gene transfer (HGT), the movement of genetic material from one species to another, is a common phenomenon in prokaryotic evolution. Although the rate of HGT is known to vary among genes, our understanding of the cause of this variation, currently summarized by two rules, is far from complete. The first rule states that informational genes, which are involved in DNA replication, transcription, and translation, have lower transferabilities than operational genes. The second rule asserts that protein interactivity negatively impacts gene transferability. Here, we hypothesize that high expression hampers HGT, because the fitness cost of an HGT to the recipient, arising from the 1) energy expenditure in transcription and translation, 2) cytotoxic protein misfolding, 3) reduction in cellular translational efficiency, 4) detrimental protein misinteraction, and 5) disturbance of the optimal protein concentration or cell physiology, increases with the expression level of the transferred gene. To test this hypothesis, we examined laboratory and natural HGTs to Escherichia coli. We observed lower transferabilities of more highly expressed genes, even after controlling the confounding factors from the two established rules and the genic GC content. Furthermore, expression level predicts gene transferability better than all other factors examined. We also confirmed the significant negative impact of gene expression on the rate of HGTs to 127 of 133 genomes of eubacteria and archaebacteria. Together, these findings establish the gene expression level as a major determinant of horizontal gene transferability. They also suggest that most successful HGTs are initially slightly deleterious, fixed because of their negligibly low costs rather than high benefits to the recipient. PMID:22436996

  16. Horizontal gene transfer, genome innovation and evolution.

    PubMed

    Gogarten, J Peter; Townsend, Jeffrey P

    2005-09-01

    To what extent is the tree of life the best representation of the evolutionary history of microorganisms? Recent work has shown that, among sets of prokaryotic genomes in which most homologous genes show extremely low sequence divergence, gene content can vary enormously, implying that those genes that are variably present or absent are frequently horizontally transferred. Traditionally, successful horizontal gene transfer was assumed to provide a selective advantage to either the host or the gene itself, but could horizontally transferred genes be neutral or nearly neutral? We suggest that for many prokaryotes, the boundaries between species are fuzzy, and therefore the principles of population genetics must be broadened so that they can be applied to higher taxonomic categories. PMID:16138096

  17. Gene Transfers Between Distantly Related Organisms

    NASA Technical Reports Server (NTRS)

    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. Horizontal gene transfer of stress resistance genes through plasmid transport.

    PubMed

    Shoeb, Erum; Badar, Uzma; Akhter, Jameela; Shams, Hina; Sultana, Maria; Ansari, Maqsood A

    2012-03-01

    The horizontal gene transfer of plasmid-determined stress tolerance was achieved under lab conditions. Bacterial isolates, Enterobacter cloacae (DGE50) and Escherichia coli (DGE57) were used throughout the study. Samples were collected from contaminated marine water and soil to isolate bacterial strains having tolerance against heavy metals and antimicrobial agents. We have demonstrated plasmid transfer, from Amp(+)Cu(+)Zn(-) strain (DGE50) to Amp(-)Cu(-)Zn(+) strain (DGE57), producing Amp(+)Cu(+)Zn(+) transconjugants (DGE(TC50→57)) and Amp(+)Cu(-)Zn(+) transformants (DGE(TF50→57)). DGE57 did not carry any plasmid, therefore, it can be speculated that zinc tolerance gene in DGE57 is located on chromosome. DGE50 was found to carry three plasmids, out of which two were transferred through conjugation into DGE57, and only one was transferred through transformation. Plasmid transferred through transformation was one out of the two transferred through conjugation. Through the results of transformation it was revealed that the genes of copper and ampicillin tolerance in DGE50 were located on separate plasmids, since only ampicillin tolerance genes were transferred through transformation as a result of one plasmid transfer. By showing transfer of plasmids under lab conditions and monitoring retention of respective phenotype via conjugation and transformation, it is very well demonstrated how multiple stress tolerant strains are generated in nature. PMID:22805823

  19. In vitro gene transfer by electrosonoporation.

    PubMed

    Escoffre, J M; Kaddur, K; Rols, M P; Bouakaz, A

    2010-10-01

    Among the nonviral methods for gene delivery in vitro, electroporation is simple, inexpensive and safe. To upregulate the expression level of transfected gene, we investigated the applicability of electrosonoporation. This approach consists of a combination of electric pulses and ultrasound assisted with gas microbubbles. Cells were first electroporated with plasmid DNA encoding-enhanced green fluorescent protein and then sonoporated in presence of contrast microbubbles. Twenty-four hours later, cells that received electrosonoporation demonstrated a four-fold increase in transfection level and a six-fold increase in transfection efficiency compared with cells having undergone electroporation alone. Although electroporation induced the formation of DNA aggregates into the cell membrane, sonoporation induced its direct propulsion into the cytoplasm. Sonoporation can improve the transfer of electro-induced DNA aggregates by allowing its free and rapid entrance into the cells. These results demonstrated that in vitro gene transfer by electrosonoporation could provide a new potent method for gene transfer. PMID:20850028

  20. Gene transfer mediated by alpha2-macroglobulin.

    PubMed Central

    Schneider, H; Huse, K; Birkenmeier, G; Otto, A; Scholz, G H

    1996-01-01

    alpha2-Macroglobulin covalently linked to poly(L)-lysine can be used as a vehicle for receptor-mediated gene transfer. This modified alpha2-macroglobulin maintains its ability to bind to the alpha2-macroglobulin receptor, and was shown to introduce a luciferase reporter gene plasmid into HepG2 human hepatoma cells in vitro. The alpha2-macroglobulin receptor is a very large and multifunctional cell surface receptor, whose rapid and efficient internalization rate makes it attractive for gene therapy, e.g. for hepatic gene targeting via injection into the portal vein. PMID:8871570

  1. Stabilizing gene regulatory networks through feedforward loops

    NASA Astrophysics Data System (ADS)

    Kadelka, C.; Murrugarra, D.; Laubenbacher, R.

    2013-06-01

    The global dynamics of gene regulatory networks are known to show robustness to perturbations in the form of intrinsic and extrinsic noise, as well as mutations of individual genes. One molecular mechanism underlying this robustness has been identified as the action of so-called microRNAs that operate via feedforward loops. We present results of a computational study, using the modeling framework of stochastic Boolean networks, which explores the role that such network motifs play in stabilizing global dynamics. The paper introduces a new measure for the stability of stochastic networks. The results show that certain types of feedforward loops do indeed buffer the network against stochastic effects.

  2. Unsupervised learning in detection of gene transfer.

    PubMed

    Hamel, L; Nahar, N; Poptsova, M S; Zhaxybayeva, O; Gogarten, J P

    2008-01-01

    The tree representation as a model for organismal evolution has been in use since before Darwin. However, with the recent unprecedented access to biomolecular data, it has been discovered that, especially in the microbial world, individual genes making up the genome of an organism give rise to different and sometimes conflicting evolutionary tree topologies. This discovery calls into question the notion of a single evolutionary tree for an organism and gives rise to the notion of an evolutionary consensus tree based on the evolutionary patterns of the majority of genes in a genome embedded in a network of gene histories. Here, we discuss an approach to the analysis of genomic data of multiple genomes using bipartition spectral analysis and unsupervised learning. An interesting observation is that genes within genomes that have evolutionary tree topologies, which are in substantial conflict with the evolutionary consensus tree of an organism, point to possible horizontal gene transfer events which often delineate significant evolutionary events. PMID:18509479

  3. [Synthesis of new gene-loaded microbubbles serve as gene delivery vehicle applied in reporter gene transfer into cardiac myocytes].

    PubMed

    Wang, Guozhong; Hu, Shenjiang; Zheng, Zhelan; Sun, Jian; Zheng, Xia; Zhu, Zhaohui; Li, Jiang; Yao, Yumei

    2006-08-01

    To improve the stability and gene-carried capability of gene-attached microbubbles, the method for manufacture of albumin microbubbles was modified and new gene-loaded microbubbles were synthesized by incorporated gene-PEI complex into the shell of microbubbles. Agarose gel electrophoresis and bacteria transformation showed that PEI had the ability to provide the protection of plasmid DNA from ultrasonic degradation. The new gene-loaded microbubbles exhibited excellent acoustical and hemorheological properties. Moreover, they could carry more plasmid DNA than gene-attached microbubbles. beta-galactosidase plasmid transfection into cardiac myocytes was performed by using ultrasound targeted destruction of new gene-loaded microbubbles or gene-attached microbubbles. Gene expression in cardiac myocytes was detected by beta-galactosidase in situ staining and quantitive assay. It was shown that beta-galactosidase activity in cardiac myocytes was enhanced 107-fold by ultrasonic destruction of gene-loaded microbubbles compared with naked plasmid transfection and new gene-loaded microbubbles resulted in 6.85-fold increase in beta-galactosidase activity compared with optimal transfection mediated by gene-attached microbubbles. These results suggested that ultrasonic destruction of the gene-loaded microbubbles can enhance the cardiac myocytes exogenous gene transfer efficiency significantly and new gene-loaded microbubbles is an efficient and safe gene delivery vehicle. PMID:17002125

  4. Lateral gene transfer in the subsurface

    SciTech Connect

    Barkay, Tamar; Sobecky, Patricia

    2007-08-27

    Lateral gene transfer (LGT) is an important adaptive mechanism among prokaryotic organisms. This mechanism is particularly important for the response of microorganisms to changing environmental conditions because it facilitates the transfer of a large number of genes and their rapid expression. Together the transferred genes promote rapid genetic and metabolic changes that may enhance survival to newly established and sometimes hostile environmental conditions. The goal of our project was to examine if and how LGT enhances microbial adaptation to toxic heavy metals in subsurface environments that had been contaminated by mixed wastes due to activities associated with the production of nuclear energy and weapons. This task has been accomplished by dividing the project to several sub-tasks. Thus, we: (1) Determined the level of resistance of subsurface bacterial isolates to several toxic metals, all identified as pollutants of concern in subsurface environments; (2) Designed, tested, and applied, a molecular approach that determined whether metal resistance genes had evolved by LGT among subsurface bacteria; and (3) Developed a DNA hybridization array for the identification of broad host range plasmids and of metal resistance plasmids. The results are briefly summarized below with references to published papers and manuscripts in preparation where details about our research can be found. Additional information may be found in copies of our published manuscripts and conference proceedings, and our yearly reports that were submitted through the RIMS system.

  5. Clinical Applications Involving CNS Gene Transfer

    PubMed Central

    Kantor, Boris; McCown, Thomas; Leone, Paola; Gray, Steven J.

    2015-01-01

    Diseases of the central nervous system (CNS) have traditionally been the most difficult to treat by traditional pharmacological methods, due mostly to the blood–brain barrier and the difficulties associated with repeated drug administration targeting the CNS. Viral vector gene transfer represents a way to permanently provide a therapeutic protein within the nervous system after a single administration, whether this be a gene replacement strategy for an inherited disorder or a disease-modifying protein for a disease such as Parkinson's. Gene therapy approaches for CNS disorders has evolved considerably over the last two decades. Although a breakthrough treatment has remained elusive, current strategies are now considerably safer and potentially much more effective. This chapter will explore the past, current, and future status of CNS gene therapy, focusing on clinical trials utilizing adeno-associated virus and lentiviral vectors. PMID:25311921

  6. Perinatal Gene Transfer to the Liver

    PubMed Central

    McKay, Tristan R; Rahim, Ahad A; Buckley, Suzanne M.K; Ward, Natalie J; Chan, Jerry K.Y; Howe, Steven J; Waddington, Simon N

    2011-01-01

    The liver acts as a host to many functions hence raising the possibility that any one may be compromised by a single gene defect. Inherited or de novo mutations in these genes may result in relatively mild diseases or be so devastating that death within the first weeks or months of life is inevitable. Some diseases can be managed using conventional medicines whereas others are, as yet, untreatable. In this review we consider the application of early intervention gene therapy in neonatal and fetal preclinical studies. We appraise the tools of this technology, including lentivirus, adenovirus and adeno-associated virus (AAV)-based vectors. We highlight the application of these for a range of diseases including hemophilia, urea cycle disorders such as ornithine transcarbamylase deficiency, organic acidemias, lysosomal storage diseases including mucopolysaccharidoses, glycogen storage diseases and bile metabolism. We conclude by assessing the advantages and disadvantages associated with fetal and neonatal liver gene transfer. PMID:21774770

  7. Engineering stability in gene networks by autoregulation

    NASA Astrophysics Data System (ADS)

    Becskei, Attila; Serrano, Luis

    2000-06-01

    The genetic and biochemical networks which underlie such things as homeostasis in metabolism and the developmental programs of living cells, must withstand considerable variations and random perturbations of biochemical parameters. These occur as transient changes in, for example, transcription, translation, and RNA and protein degradation. The intensity and duration of these perturbations differ between cells in a population. The unique state of cells, and thus the diversity in a population, is owing to the different environmental stimuli the individual cells experience and the inherent stochastic nature of biochemical processes (for example, refs 5 and 6). It has been proposed, but not demonstrated, that autoregulatory, negative feedback loops in gene circuits provide stability, thereby limiting the range over which the concentrations of network components fluctuate. Here we have designed and constructed simple gene circuits consisting of a regulator and transcriptional repressor modules in Escherichia coli and we show the gain of stability produced by negative feedback.

  8. Engineering stability in gene networks by autoregulation.

    PubMed

    Becskei, A; Serrano, L

    2000-06-01

    The genetic and biochemical networks which underlie such things as homeostasis in metabolism and the developmental programs of living cells, must withstand considerable variations and random perturbations of biochemical parameters. These occur as transient changes in, for example, transcription, translation, and RNA and protein degradation. The intensity and duration of these perturbations differ between cells in a population. The unique state of cells, and thus the diversity in a population, is owing to the different environmental stimuli the individual cells experience and the inherent stochastic nature of biochemical processes (for example, refs 5 and 6). It has been proposed, but not demonstrated, that autoregulatory, negative feedback loops in gene circuits provide stability, thereby limiting the range over which the concentrations of network components fluctuate. Here we have designed and constructed simple gene circuits consisting of a regulator and transcriptional repressor modules in Escherichia coli and we show the gain of stability produced by negative feedback. PMID:10850721

  9. Characterization of an Ancient Lepidopteran Lateral Gene Transfer

    PubMed Central

    Wheeler, David; Redding, Amanda J.; Werren, John H.

    2013-01-01

    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. PMID:23533610

  10. Foamy virus vectors for gene transfer

    PubMed Central

    Trobridge, Grant D.

    2009-01-01

    Foamy virus (FV) vectors are efficient gene delivery vehicles that have shown great promise for gene therapy in preclinical animal models. FVs or spumaretroviruses are not endemic in humans, but are prevalent in nonhuman primates and in other mammals. They have evolved means for efficient horizontal transmission in their host species without pathology. FV vectors have several unique properties that make them well-suited for therapeutic gene transfer including a desirable safety profile, a broad tropism, a large transgene capacity, and the ability to persist in quiescent cells. They mediate efficient and stable gene transfer to hematopoietic stem cells (HSCs) in mouse models, and in the canine large animal model. Analysis of FV vector integration sites in vitro and in hematopoietic repopulating cells shows they have a unique integration profile, and suggests they may be safer than gammaretroviruses or lentiviral vectors. Here properties of FVs relevant to the safety and efficacy of FV vectors are discussed. The development of FV vector systems is described, and studies evaluating their potential in vitro, and in small and large animal models is reviewed. PMID:19743892

  11. Horizontal Gene Transfer, Dispersal and Haloarchaeal Speciation

    PubMed Central

    Papke, R. Thane; Corral, Paulina; Ram-Mohan, Nikhil; de la Haba, Rafael R.; Sánchez-Porro, Cristina; Makkay, Andrea; Ventosa, Antonio

    2015-01-01

    The Halobacteria are a well-studied archaeal class and numerous investigations are showing how their diversity is distributed amongst genomes and geographic locations. Evidence indicates that recombination between species continuously facilitates the arrival of new genes, and within species, it is frequent enough to spread acquired genes amongst all individuals in the population. To create permanent independent diversity and generate new species, barriers to recombination are probably required. The data support an interpretation that rates of evolution (e.g., horizontal gene transfer and mutation) are faster at creating geographically localized variation than dispersal and invasion are at homogenizing genetic differences between locations. Therefore, we suggest that recurrent episodes of dispersal followed by variable periods of endemism break the homogenizing forces of intrapopulation recombination and that this process might be the principal stimulus leading to divergence and speciation in Halobacteria. PMID:25997110

  12. Development of a transfer function method for dynamic stability measurement

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1977-01-01

    Flutter testing method based on transfer function measurements is developed. The error statistics of several dynamic stability measurement methods are reviewed. It is shown that the transfer function measurement controls the error level by averaging the data and correlating the input and output. The method also gives a direct estimate of the error in the response measurement. An algorithm is developed for obtaining the natural frequency and damping ratio of low damped modes of the system, using integrals of the transfer function in the vicinity of a resonant peak. Guidelines are given for selecting the parameters in the transfer function measurement. Finally, the dynamic stability measurement technique is applied to data from a wind tunnel test of a proprotor and wing model.

  13. Simple rapid method for gene transfer

    SciTech Connect

    Cockburn, A.F.; Meier, H.

    1990-01-30

    The object of the present invention is to provide methods for gene transfer that reduce or eliminate cellular pretreatment steps, e.g., the removal of cell wall by chemical or enzymatic methods, is rapid and can be practiced without the need of additional expensive equipment. Cells, embryos or tissues selected for genetic manipulation are suspended in an Eppendorf tube in an aliquot of the desired genetic material to be transferred to which the resulting mixture is added and is agitated by vortexing from about 30 to about 90 seconds. The cells, embryos or tissue are sedimented and the DNA supernatant removed. After sedimentation, the injected material is resuspended in or on a growth medium to assay for expression.

  14. Gene Transfer between Salmonella enterica Serovar Typhimurium inside Epithelial Cells

    PubMed Central

    Ferguson, Gayle C.; Heinemann, Jack A.; Kennedy, Martin A.

    2002-01-01

    Virulence and antibiotic resistance genes transfer between bacteria by bacterial conjugation. Conjugation also mediates gene transfer from bacteria to eukaryotic organisms, including yeast and human cells. Predicting when and where genes transfer by conjugation could enhance our understanding of the risks involved in the release of genetically modified organisms, including those being developed for use as vaccines. We report here that Salmonella enterica serovar Typhimurium conjugated inside cultured human cells. The DNA transfer from donor to recipient bacteria was proportional to the probability that the two types of bacteria occupied the same cell, which was dependent on viable and invasive bacteria and on plasmid tra genes. Based on the high frequencies of gene transfer between bacteria inside human cells, we suggest that such gene transfers occur in situ. The implications of gene transfer between bacteria inside human cells, particularly in the context of antibiotic resistance, are discussed. PMID:11914355

  15. Reducible cationic lipids for gene transfer.

    PubMed Central

    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

  16. Horizontal gene transfer from Agrobacterium to plants

    PubMed Central

    Matveeva, Tatiana V.; Lutova, Ludmila A.

    2014-01-01

    Most genetic engineering of plants uses Agrobacterium mediated transformation to introduce novel gene content. In nature, insertion of T-DNA in the plant genome and its subsequent transfer via sexual reproduction has been shown in several species in the genera Nicotiana and Linaria. In these natural examples of horizontal gene transfer from Agrobacterium to plants, the T-DNA donor is assumed to be a mikimopine strain of A. rhizogenes. A sequence homologous to the T-DNA of the Ri plasmid of Agrobacterium rhizogenes was found in the genome of untransformed Nicotiana glauca about 30 years ago, and was named “cellular T-DNA” (cT-DNA). It represents an imperfect inverted repeat and contains homologs of several T-DNA oncogenes (NgrolB, NgrolC, NgORF13, NgORF14) and an opine synthesis gene (Ngmis). A similar cT-DNA has also been found in other species of the genus Nicotiana. These presumably ancient homologs of T-DNA genes are still expressed, indicating that they may play a role in the evolution of these plants. Recently T-DNA has been detected and characterized in Linaria vulgaris and L. dalmatica. In Linaria vulgaris the cT-DNA is present in two copies and organized as a tandem imperfect direct repeat, containing LvORF2, LvORF3, LvORF8, LvrolA, LvrolB, LvrolC, LvORF13, LvORF14, and the Lvmis genes. All L. vulgaris and L. dalmatica plants screened contained the same T-DNA oncogenes and the mis gene. Evidence suggests that there were several independent T-DNA integration events into the genomes of these plant genera. We speculate that ancient plants transformed by A. rhizogenes might have acquired a selective advantage in competition with the parental species. Thus, the events of T-DNA insertion in the plant genome might have affected their evolution, resulting in the creation of new plant species. In this review we focus on the structure and functions of cT-DNA in Linaria and Nicotiana and discuss their possible evolutionary role. PMID:25157257

  17. Gene therapy: Biological pacemaker created by gene transfer

    NASA Astrophysics Data System (ADS)

    Miake, Junichiro; Marbán, Eduardo; Nuss, H. Bradley

    2002-09-01

    The pacemaker cells of the heart initiate the heartbeat, sustain the circulation, and dictate the rate and rhythm of cardiac contraction. Circulatory collapse ensues when these specialized cells are damaged by disease, a situation that currently necessitates the implantation of an electronic pacemaker. Here we report the use of viral gene transfer to convert quiescent heart-muscle cells into pacemaker cells, and the successful generation of spontaneous, rhythmic electrical activity in the ventricle in vivo. Our results indicate that genetically engineered pacemakers could be developed as a possible alternative to implantable electronic devices.

  18. Gene duplication and transfer events in plant mitochondria genome

    SciTech Connect

    Xiong Aisheng Peng Rihe; Zhuang Jing; Gao Feng; Zhu Bo; Fu Xiaoyan; Xue Yong; Jin Xiaofen; Tian Yongsheng; Zhao Wei; Yao Quanhong

    2008-11-07

    Gene or genome duplication events increase the amount of genetic material available to increase the genomic, and thereby phenotypic, complexity of organisms during evolution. Gene duplication and transfer events have been important to molecular evolution in all three domains of life, and may be the first step in the emergence of new gene functions. Gene transfer events have been proposed as another accelerator of evolution. The duplicated gene or genome, mainly nuclear, has been the subject of several recent reviews. In addition to the nuclear genome, organisms have organelle genomes, including mitochondrial genome. In this review, we briefly summarize gene duplication and transfer events in the plant mitochondrial genome.

  19. Optical gene transfer by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Konig, Karsten; Riemann, Iris; Tirlapur, Uday K.

    2003-07-01

    Targeted transfection of cells is an important technique for gene therapy and related biomedical applications. We delineate how high-intensity (1012 W/cm2) near-infrared (NIR) 80 MHz nanojoule femtosecond laser pulses can create highly localised membrane perforations within a minute focal volume, enabling non-invasive direct transfection of mammalian cells with DNA. We suspended Chinese hamster ovarian (CHO), rat kangaroo kidney epithelial (PtK2) and rat fibroblast cells in 0.5 ml culture medium in a sterile miniaturized cell chamber (JenLab GmbH, Jena, Germany) containing 0.2 μg plasmid DNA vector pEGFP-N1 (4.7 kb), which codes for green fluorescent protein (GFP). The NIR laser beam was introduced into a femtosecond laser scanning microscope (JenLab GmbH, Jena, Germany; focussed on the edge of the cell membrane of a target cell for 16 ms. The integration and expression efficiency of EGFP were assessed in situ by two-photon fluorescence-lifetime imaging using time-correlated single photon counting. The unique capability to transfer foreign DNA safely and efficiently into specific cell types (including stem cells), circumventing mechanical, electrical or chemical means, will have many applications, such as targeted gene therapy and DNA vaccination.

  20. Lentiviral vector gene transfer to porcine airways.

    PubMed

    Sinn, Patrick L; Cooney, Ashley L; Oakland, Mayumi; Dylla, Douglas E; Wallen, Tanner J; Pezzulo, Alejandro A; Chang, Eugene H; McCray, Paul B

    2012-01-01

    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).Molecular Therapy - Nucleic Acids (2012) 1, e56; doi:10.1038/mtna.2012.47; published online 27 November 2012. PMID:23187455

  1. Plant transformation via pollen tube-mediated gene transfer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic transformation using foreign genes and the subsequent development of transgenic plants has been employed to develop enhanced elite germplasm. Although some skepticism exits regarding pollen tube-mediated gene transfer (PTT), reports demonstrating improved transformation efficiency with PTT ...

  2. Gene Transfer & Hybridization Studies in Hyperthermophilic Species

    SciTech Connect

    Nelson, Karen E.

    2005-10-14

    A. ABSTRACT The importance of lateral gene transfer (LGT) in the evolution of microbial species has become increasingly evident with each completed microbial genome sequence. Most significantly, the genome of Thermotoga maritima MSB8, a hyperthermophilic bacterium isolated by Karl Stetter and workers from Vulcano Italy in 1986, and sequenced at The Institute for Genomic Research (TIGR) in Rockville Maryland in 1999, revealed extensive LGT between % . this bacterium and members of the archaeal domain (in particular Archaeoglobus fulgidus, and Pyracoccus frcriosus species). Based on whole genome comparisons, it was estimated that 24% of the genetic information in this organism was acquired by genetic exchange with archaeal species, Independent analyses including periodicity analysis of the T. maritimu genomic DNA sequence, phylogenetic reconstruction based on genes that appear archaeal-like, and codon and amino acid usage, have provided additional evidence for LGT between T. maritima and the archaea. More recently, DiRuggiero and workers have identified a very recent LGT event between two genera of hyperthermophilic archaea, where a nearly identical DNA fragment of 16 kb in length flanked by insertion sequence (IS) elements, exists. Undoubtedly, additional examples of LGT will be identified as more microbial genomes are completed. For the present moment however, the genome sequence of T. maritima and other hyperthermophiles including P. furiosus, Pyrococcus horikoshii, Pyrococcus abyssi, A. fulgidus, and Aquifex aeolicus, have significantly increased out awareness of evolution being a web of life rather than a tree of life, as suggested by single gene phylogenies. In this proposal, we will aim to determine the extent of LGT across the hyperthemophiles, employing iY maritima as the model organism. A variety of biochemical techniques and phylogenetic reconstructions will allow for a detailed and thorough characterization of the extent of LGT in this species. The

  3. Skyrmion stability in nanocontact spin-transfer oscillators

    SciTech Connect

    Chui, C. P.; Zhou, Yan

    2015-09-15

    We investigate the conditions for nanocontact spin-transfer oscillators (NC-STOs) that allow for stabilization of a skyrmion. Emphasis is made on the breathing mode, which can be regarded as a source of microwave generation. Micromagnetic simulations of NC-STOs with varying parameters have been performed, with the resulting magnetization plotted in the form of phase diagrams. It is found that control of spin wave mode in conventional STOs can be applied to skyrmion-based STOs.

  4. Direct gene transfer into human cultured cells facilitated by laser micropuncture of the cell membrane

    SciTech Connect

    Tao, W.; Wilkinson, J.; Stanbridge, E.J.; Berns, M.W.

    1987-06-01

    The selective alteration of the cellular genome by laser microbeam irradiation has been extensively applied in cell biology. We report here the use of the third harmonic (355 nm) of an yttrium-aluminum garnet laser to facilitate the direct transfer of the neo gene into cultured human HT1080-6TG cells. The resultant transformants were selected in media containing an aminoglycoside antibiotic, G418. Integration of the neo gene into individual chromosomes and expression of the gene were demonstrated by Southern blot analyses, microcell-mediated chromosome transfer, and chromosome analyses. The stability of the integrated neo gene in the transformants was shown by a comparative growth assay in selective and nonselective media. Transformation and incorporation of the neo gene into the host genome occurred at a frequency of 8x10-4-3x10-3. This method appears to be 100-fold more efficient than the standard calcium phosphate-mediated method of DNA transfer.

  5. Direct Gene Transfer into Human Cultured Cells Facilitated by Laser Micropuncture of the Cell Membrane

    NASA Astrophysics Data System (ADS)

    Tao, Wen; Wilkinson, Joyce; Stanbridge, Eric J.; Berns, Michael W.

    1987-06-01

    The selective alteration of the cellular genome by laser microbeam irradiation has been extensively applied in cell biology. We report here the use of the third harmonic (355 nm) of an yttrium-aluminum garnet laser to facilitate the direct transfer of the neo gene into cultured human HT1080-6TG cells. The resultant transformants were selected in medium containing an aminoglycoside antibiotic, G418. Integration of the neo gene into individual human chromosomes and expression of the gene were demonstrated by Southern blot analyses, microcell-mediated chromosome transfer, and chromosome analyses. The stability of the integrated neo gene in the transformants was shown by a comparative growth assay in selective and nonselective media. Transformation and incorporation of the neo gene into the host genome occurred at a frequency of 8 × 10-4-3 × 10-3. This method appears to be 100-fold more efficient than the standard calcium phosphate-mediated method of DNA transfer.

  6. Methods for Gene Transfer to the Central Nervous System

    PubMed Central

    Kantor, Boris; Bailey, Rachel M.; Wimberly, Keon; Kalburgi, Sahana N.; Gray, Steven J.

    2015-01-01

    Gene transfer is an increasingly utilized approach for research and clinical applications involving the central nervous system (CNS). Vectors for gene transfer can be as simple as an unmodified plasmid, but more commonly involve complex modifications to viruses to make them suitable gene delivery vehicles. This chapter will explain how tools for CNS gene transfer have been derived from naturally occurring viruses. The current capabilities of plasmid, retroviral, adeno-associated virus, adenovirus, and herpes simplex virus vectors for CNS gene delivery will be described. These include both focal and global CNS gene transfer strategies, with short- or long-term gene expression. As is described in this chapter, an important aspect of any vector is the cis-acting regulatory elements incorporated into the vector genome that control when, where, and how the transgene is expressed. PMID:25311922

  7. Gene transfer system for Rhodopseudomonas viridis.

    PubMed Central

    Lang, F S; Oesterhelt, D

    1989-01-01

    A gene transfer system for Rhodopseudomonas viridis was established which uses conjugation with Escherichia coli S17-I as the donor and mobilizable plasmids as vectors. Initially, plasmids of the incompatibility group P1 (pRK290 and pRK404) were used. The more effective shuttle vectors between E. coli and R. viridis, pKV1 and pKVS1, were derived from plasmid pBR322 and showed the highest conjugation frequency (10(-2] thus far demonstrated in purple bacteria. It was also demonstrated that Rhizobium meliloti can be used as a donor for conjugation with R. viridis. From a genomic cosmid library of R. viridis constructed in the vector pHC79, clones that coded for subunits H (puh operon), L, M and cytochrome c (puf operon) of the photosynthetic reaction center were isolated and characterized. For linkage of the two operons on the genome, cosmids that overlapped with the operon-carrying clones were identified. The relative positions of the two operons could not be determined, but the operons must be more than 100 kilobase pairs apart. Thus, the genomic organization of the reaction center in R. viridis is different from that of Rhodobacter capsulatus, for which a distance of about 39 kilobase pairs was determined. From a spontaneous mutant of R. viridis that is resistant to the herbicide terbutryn, the puf operon was cloned in pKVS1 and transferred by conjugation into R. viridis wild-type cells. The resulting exconjugants were resistant to the herbicide, which demonstrated that the puf operon on pKVS1 constructions was functionally expressed in R. viridis. Images PMID:2666398

  8. Kinetics of conjugative gene transfer on surfaces in granular porous media

    NASA Astrophysics Data System (ADS)

    Massoudieh, A.; Crain, C.; Lambertini, E.; Nelson, K. E.; Barkouki, T.; L'Amoreaux, P.; Loge, F. J.; Ginn, T. R.

    2010-03-01

    The transfer of genetic material among bacteria in the environment can occur both in the planktonic and attached state. Given the propensity of organisms to exist in sessile microbial communities in oligotrophic subsurface conditions, and that such conditions typify the subsurface, this study focuses on exploratory modeling of horizontal gene transfer among surface-associated Escherichiacoli in the subsurface. The mathematics so far used to describe the kinetics of conjugation in biofilms are developed largely from experimental observations of planktonic gene transfer, and are absent of lags or plasmid stability that appear experimentally. We develop a model and experimental system to quantify bacterial filtration and gene transfer in the attached state, on granular porous media. We include attachment kinetics described in Nelson et al. (2007) using the filtration theory approach of Nelson and Ginn (2001, 2005) with motility of E. coli described according to Biondi et al. (1998).

  9. Kinetics of conjugative gene transfer on surfaces in granular porous media

    NASA Astrophysics Data System (ADS)

    Ginn, T.; Massoudieh, A.; Nelson, K.; Mathew, A.; Lambertini, E.

    2005-12-01

    The transfer of genetic material among bacteria in the environment can occur both in the planktonic and attached state. Given the propensity of organisms to exist in sessile microbial communities in oligotrophic conditions, and that such conditions typify the subsurface, this study focuses on exploratory modeling of horizontal gene transfer among surface-associated E. coli in the subsurface. The mathematics so far used to describe the kinetics of conjugation in biofilms are developed largely from experimental observations of planktonic gene transfer, and are absent of lags or plasmid stability that appear experimentally. We develop a model for bacterial filtration and gene transfer in the attached state, for the early stages of biofilm formation using a recently revised filtration theory approach (Nelson and Ginn, 2005) with motility of E. coli described as a continuous time random walk according to data from microflow chamber experiments (Biondi et al., 2002).

  10. Laser frequency stabilization and shifting by using modulation transfer spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, Bing; Wang, Zhao-Ying; Wu, Bin; Xu, Ao-Peng; Wang, Qi-Yu; Xu, Yun-Fei; Lin, Qiang

    2014-10-01

    The stabilizing and shifting of laser frequency are very important for the interaction between the laser and atoms. The modulation transfer spectroscopy for the 87Rb atom with D2 line transition F = 2 → F' = 3 is used for stabilizing and shifting the frequency of the external cavity grating feedback diode laser. The resonant phase modulator with electro—optical effect is used to generate frequency sideband to lock the laser frequency. In the locking scheme, circularly polarized pump- and probe-beams are used. By optimizing the temperature of the vapor, the pump- and probe-beam intensity, the laser linewidth of 280 kHz is obtained. Furthermore, the magnetic field generated by a solenoid is added into the system. Therefore the system can achieve the frequency locking at any point in a range of hundreds of megahertz frequency shifting with very low power loss.

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

    PubMed Central

    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

  12. Cotransfer of linked eukaryotic genes and efficient transfer of hypoxanthine phosphoribosyltransferase by DNA-mediated gene transfer.

    PubMed Central

    Peterson, J L; McBride, O W

    1980-01-01

    The efficiency of DNA-mediated transfer of the gene (hprt) for hypoxanthine phosphoribosyltransferase (HPRT; IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) is dependent upon the recipient cell used. hprt has been transferred into mouse TG8 or Chinese hamster CHTG49 cells at a high frequency, similar to the frequency of the gene (tk) for thymidine kinase (TK; ATP:thymidine 5'-phosphotransferase, EC 2.7.1.21) transfer into mouse LMTK- cells (i.e., 10(-6)). In contrast, the frequency of transfer of hprt into mouse A9 cells was about two orders of magnitude less. The identification of efficient recipient cells for hprt transfer permits the use of DNA-mediated transfer as a bioassay for the gene. Cotransfer of the linked tk gene and the gene (galk) for galactokinase (ATP: D-galactose 1-phosphotransferase, EC 2.7.1.6) to LMTK- cells has been detected once among 87 tk transferrents. This suggests that the distance between the tk and galk genes in the Chinese hamster genome may be smaller than was previously thought. Significant differences between chromosome-mediated and DNA-mediated gene transfer were observed with respect to both the size of the transferred functional genetic fragment and the recipient cell specificity. Images PMID:6929511

  13. Gene Transfer Strategies to Promote Chondrogenesis and Cartilage Regeneration.

    PubMed

    Im, Gun-Il

    2016-04-01

    Gene transfer has been used experimentally to promote chondrogenesis and cartilage regeneration. While it is controversial to apply gene therapy for nonlethal conditions such as cartilage defect, there is a possibility that the transfer of therapeutic transgenes may dramatically increase the effectiveness of cell therapy and reduce the quantity of cells that are needed to regenerate cartilage. Single or combination of growth factors and transcription factors has been transferred to mesenchymal stem cells or articular chondrocytes using both nonviral and viral approaches. The current challenge for the clinical applications of genetically modified cells is ensuring the safety of gene therapy while guaranteeing effectiveness. Viral gene delivery methods have been mainstays currently with enhanced safety features being recently refined. On the other hand, efficiency has been greatly improved in nonviral delivery. This review summarizes the history and recent update on the gene transfer to enhance chondrogenesis from stem cells or articular chondrocytes. PMID:26414246

  14. Direct transfer of IL-12 gene into growing Renca tumors.

    PubMed

    Budryk, M; Wilczyńska, U; Szary, J; Szala, S

    2000-01-01

    We investigated the feasibility of transferring naked plasmid DNA containing a therapeutic gene (IL-12) into mice harboring growing Renca tumors. We found that naked DNA transferred into growing Renca and B16(F10) tumors gives higher expression level of reporter gene than complexes of DNA with DDAB/DOPE or DC-Chol/DOPE. Transfer of naked DNA carrying the IL-12 gene into growing Renca tumors causes a distinct therapeutic effect that depends on the time span between inoculation of mice with cancer cells and the beginning of the therapy. Therapy started on day 3 resulted in total cure (100%) of mice. PMID:11051203

  15. LATERAL GENE TRANSFER AND THE HISTORY OF BACTERIAL GENOMES

    SciTech Connect

    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.

  16. Intracellular gene transfer: Reduced hydrophobicity facilitates gene transfer for subunit 2 of cytochrome c oxidase

    PubMed Central

    Daley, Daniel O.; Clifton, Rachel; Whelan, James

    2002-01-01

    Subunit 2 of cytochrome c oxidase (Cox2) in legumes offers a rare opportunity to investigate factors necessary for successful gene transfer of a hydrophobic protein that is usually mitochondrial-encoded. We found that changes in local hydrophobicity were necessary to allow import of this nuclear-encoded protein into mitochondria. All legume species containing both a mitochondrial and nuclear encoded Cox2 displayed a similar pattern, with a large decrease in hydrophobicity evident in the first transmembrane region of the nuclear encoded protein compared with the organelle-encoded protein. Mitochondrial-encoded Cox2 could not be imported into mitochondria under the direction of the mitochondrial targeting sequence that readily supports the import of nuclear encoded Cox2. Removal of the first transmembrane region promotes import ability of the mitochondrial-encoded Cox2. Changing just two amino acids in the first transmembrane region of mitochondrial-encoded Cox2 to the corresponding amino acids in the nuclear encoded Cox2 also promotes import ability, whereas changing the same two amino acids in the nuclear encoded Cox2 to what they are in the mitochondrial-encoded copy prevents import. Therefore, changes in amino acids in the mature protein were necessary and sufficient for gene transfer to allow import under the direction of an appropriate signal to achieve the functional topology of Cox2. PMID:12142462

  17. Fibrin-mediated lentivirus gene transfer: implications for lentivirus microarrays

    PubMed Central

    Raut, Shruti; Lei, Pedro; Padmashali, Roshan; Andreadis, Stelios T.

    2010-01-01

    We employed fibrin hydrogel as bioactive matrix for lentivirus mediated gene transfer. Fibrin-mediated gene transfer was highly efficient and exhibited strong dependence on fibrinogen concentration. Efficient gene transfer was achieved with fibrinogen concentration between 3.75 – 7.5 mg/mL. Lower fibrinogen concentrations resulted in diffusion of virus out of the gel while higher concentrations led to ineffective fibrin degradation by target cells. Addition of fibrinolytic inhibitors decreased gene transfer in a dose-dependent manner suggesting that fibrin degradation by target cells may be necessary for successful gene delivery. Under these conditions transduction may be limited only to cells interacting with the matrix thereby providing a method for spatially localized gene delivery. Indeed, when lentivirus-containing fibrin microgels were spotted in an array format gene transfer was confined to virus-containing fibrin spots with minimal cross-contamination between neighboring sites. Collectively, our data suggest that fibrin may provide an effective matrix for spatially-localized gene delivery with potential applications in high-throughput lentiviral microarrays and in regenerative medicine. PMID:20153386

  18. Global Analysis of Horizontal Gene Transfer in Fusarium verticillioides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The co-occurrence of microbes within plants and other specialized niches may facilitate horizontal gene transfer (HGT) affecting host-pathogen interactions. We recently identified fungal-to-fungal HGTs involving metabolic gene clusters. For a global analysis of HGTs in the maize pathogen Fusarium ve...

  19. TWIN BINARIES: STUDIES OF STABILITY, MASS TRANSFER, AND COALESCENCE

    SciTech Connect

    Lombardi, J. C.; Holtzman, W.; Gearity, K.; Dooley, K. L.; Kalogera, V.; Rasio, F. A.

    2011-08-20

    Motivated by suggestions that binaries with almost equal-mass components ('twins') play an important role in the formation of double neutron stars and may be rather abundant among binaries, we study the stability of synchronized close and contact binaries with identical components in circular orbits. In particular, we investigate the dependency of the innermost stable circular orbit on the core mass, and we study the coalescence of the binary that occurs at smaller separations. For twin binaries composed of convective main-sequence stars, subgiants, or giants with low-mass cores (M{sub c} {approx}< 0.15M, where M is the mass of a component), a secular instability is reached during the contact phase, accompanied by a dynamical mass transfer instability at the same or at a slightly smaller orbital separation. Binaries that come inside this instability limit transfer mass gradually from one component to the other and then coalesce quickly as mass is lost through the outer Lagrangian points. For twin giant binaries with moderate to massive cores (M{sub c} {approx}> 0.15M), we find that stable contact configurations exist at all separations down to the Roche limit, when mass shedding through the outer Lagrangian points triggers a coalescence of the envelopes and leaves the cores orbiting in a central tight binary. In addition to the formation of binary neutron stars, we also discuss the implications of our results for the production of planetary nebulae with double degenerate central binaries.

  20. Evolution of and horizontal gene transfer in the Endornavirus genus.

    PubMed

    Song, Dami; Cho, Won Kyong; Park, Sang-Ho; Jo, Yeonhwa; Kim, Kook-Hyung

    2013-01-01

    The transfer of genetic information between unrelated species is referred to as horizontal gene transfer. Previous studies have demonstrated that both retroviral and non-retroviral sequences have been integrated into eukaryotic genomes. Recently, we identified many non-retroviral sequences in plant genomes. In this study, we investigated the evolutionary origin and gene transfer of domains present in endornaviruses which are double-stranded RNA viruses. Using the available sequences for endornaviruses, we found that Bell pepper endornavirus-like sequences homologous to the glycosyltransferase 28 domain are present in plants, fungi, and bacteria. The phylogenetic analysis revealed the glycosyltransferase 28 domain of Bell pepper endornavirus may have originated from bacteria. In addition, two domains of Oryza sativa endornavirus, a glycosyltransferase sugar-binding domain and a capsular polysaccharide synthesis protein, also exhibited high similarity to those of bacteria. We found evidence that at least four independent horizontal gene transfer events for the glycosyltransferase 28 domain have occurred among plants, fungi, and bacteria. The glycosyltransferase sugar-binding domains of two proteobacteria may have been horizontally transferred to the genome of Thalassiosira pseudonana. Our study is the first to show that three glycome-related viral genes in the genus Endornavirus have been acquired from marine bacteria by horizontal gene transfer. PMID:23667703

  1. Evolution of and Horizontal Gene Transfer in the Endornavirus Genus

    PubMed Central

    Park, Sang-Ho; Jo, Yeonhwa; Kim, Kook-Hyung

    2013-01-01

    The transfer of genetic information between unrelated species is referred to as horizontal gene transfer. Previous studies have demonstrated that both retroviral and non-retroviral sequences have been integrated into eukaryotic genomes. Recently, we identified many non-retroviral sequences in plant genomes. In this study, we investigated the evolutionary origin and gene transfer of domains present in endornaviruses which are double-stranded RNA viruses. Using the available sequences for endornaviruses, we found that Bell pepper endornavirus-like sequences homologous to the glycosyltransferase 28 domain are present in plants, fungi, and bacteria. The phylogenetic analysis revealed the glycosyltransferase 28 domain of Bell pepper endornavirus may have originated from bacteria. In addition, two domains of Oryza sativa endornavirus, a glycosyltransferase sugar-binding domain and a capsular polysaccharide synthesis protein, also exhibited high similarity to those of bacteria. We found evidence that at least four independent horizontal gene transfer events for the glycosyltransferase 28 domain have occurred among plants, fungi, and bacteria. The glycosyltransferase sugar-binding domains of two proteobacteria may have been horizontally transferred to the genome of Thalassiosira pseudonana. Our study is the first to show that three glycome-related viral genes in the genus Endornavirus have been acquired from marine bacteria by horizontal gene transfer. PMID:23667703

  2. Horizontal functional gene transfer from bacteria to fishes

    PubMed Central

    Sun, Bao-Fa; Li, Tong; Xiao, Jin-Hua; Jia, Ling-Yi; Liu, Li; Zhang, Peng; Murphy, Robert W.; He, Shun-Min; Huang, Da-Wei

    2015-01-01

    Invertebrates can acquire functional genes via horizontal gene transfer (HGT) from bacteria but fishes are not known to do so. We provide the first reliable evidence of one HGT event from marine bacteria to fishes. The HGT appears to have occurred after emergence of the teleosts. The transferred gene is expressed and regulated developmentally. Its successful integration and expression may change the genetic and metabolic repertoire of fishes. In addition, this gene contains conserved domains and similar tertiary structures in fishes and their putative donor bacteria. Thus, it may function similarly in both groups. Evolutionary analyses indicate that it evolved under purifying selection, further indicating its conserved function. We document the first likely case of HGT of functional gene from prokaryote to fishes. This discovery certifies that HGT can influence vertebrate evolution. PMID:26691285

  3. Advancements in gene transfer-based therapy for hemophilia A

    PubMed Central

    Doering, Christopher B; Spencer, H Trent

    2010-01-01

    Gene therapy has promised clinical benefit to those suffering with hemophilia A, but this benefit has not yet been realized. However, during the past two decades, basic and applied gene therapy research has progressed and the goal of gene therapy for hemophilia A is once again in our sights. The hemophilia A patient population suffers from a disease that requires invasive, lifelong management, is exorbitantly expensive to treat, has geographically limited treatment access and can become untreatable due to immune reactions to the treatment product. Subsequent to the cloning of the factor VIII gene and cDNA in the early 1980s, academic and commercial research laboratories began to pursue gene transfer-based therapies to supplement or supplant the available protein replacement therapy. However, to date, clinical trials for gene therapy of hemophilia A have been unsuccessful. Three trials have been conducted with each having tested a different gene-transfer strategy and each demonstrating that there is a considerable barrier to achieving sustained expression of therapeutic amounts of factor VIII. Recent progress has been made in gene-transfer technology and, relevant to hemophilia A, towards increasing the biosynthetic efficiency of factor VIII. These advances are now being combined to develop novel strategies to treat and possibly cure hemophilia A. PMID:20577574

  4. Horizontal gene transfer in the human gastrointestinal tract: potential spread of antibiotic resistance genes

    PubMed Central

    Huddleston, Jennifer R

    2014-01-01

    Bacterial infections are becoming increasingly difficult to treat due to widespread antibiotic resistance among pathogens. This review aims to give an overview of the major horizontal transfer mechanisms and their evolution and then demonstrate the human lower gastrointestinal tract as an environment in which horizontal gene transfer of resistance determinants occurs. Finally, implications for antibiotic usage and the development of resistant infections and persistence of antibiotic resistance genes in populations as a result of horizontal gene transfer in the large intestine will be discussed. PMID:25018641

  5. Experiments on gene transferring to primary hematopoietic cells by liposome.

    PubMed

    Hu, L; Zhang, B

    2000-01-01

    Liposomes have showed many advantages in mediating exogenous gene into many cell types in vitro and in vivo. But few data are available concerning gene transfer into hematopoietic cells. In this report, we described two-marker genes (Neo R and Lac Z) co-transferred into hematopoietic cells of human and mouse by using liposome in vitro. The efficiency of gene transfer was tested by X-gal staining and observation of colony formation. The X-gal blue staining rate of transduced cells was about (13.33 +/- 2.68)% in human and about (16.28 +/- 2.95)% in mouse without G418 selection. After G418 selection, the blue cell rate was (46.06 +/- 3.47)% in human and (43.45 +/- 4.1)% in mouse, which were markedly higher than those before selection, suggesting that high-efficiency gene transfer and expression could be attained in primary hematopoietic cells using this easy and harmless transduction protocol. At the same time, this protocol provided experimental data for clinicians to investigate the biology of marrow reconstitution and trace the origin of relapse after autologous bone marrow transplantation for the patients with leukemia. PMID:12840913

  6. Estimating the Frequency of Horizontal Gene Transfer Using Phylogenetic Models of Gene Gain and Loss.

    PubMed

    Zamani-Dahaj, Seyed Alireza; Okasha, Mohamed; Kosakowski, Jakub; Higgs, Paul G

    2016-07-01

    We analyze patterns of gene presence and absence in a maximum likelihood framework with rate parameters for gene gain and loss. Standard methods allow independent gains and losses in different parts of a tree. While losses of the same gene are likely to be frequent, multiple gains need to be considered carefully. A gene gain could occur by horizontal transfer or by origin of a gene within the lineage being studied. If a gene is gained more than once, then at least one of these gains must be a horizontal transfer. A key parameter is the ratio of gain to loss rates, a/v We consider the limiting case known as the infinitely many genes model, where a/v tends to zero and a gene cannot be gained more than once. The infinitely many genes model is used as a null model in comparison to models that allow multiple gains. Using genome data from cyanobacteria and archaea, it is found that the likelihood is significantly improved by allowing for multiple gains, but the average a/v is very small. The fraction of genes whose presence/absence pattern is best explained by multiple gains is only 15% in the cyanobacteria and 20% and 39% in two data sets of archaea. The distribution of rates of gene loss is very broad, which explains why many genes follow a treelike pattern of vertical inheritance, despite the presence of a significant minority of genes that undergo horizontal transfer. PMID:27189546

  7. Horizontal gene transfer in eukaryotes: The weak-link model

    PubMed Central

    Huang, Jinling

    2013-01-01

    The significance of horizontal gene transfer (HGT) in eukaryotic evolution remains controversial. Although many eukaryotic genes are of bacterial origin, they are often interpreted as being derived from mitochondria or plastids. Because of their fixed gene pool and gene loss, however, mitochondria and plastids alone cannot adequately explain the presence of all, or even the majority, of bacterial genes in eukaryotes. Available data indicate that no insurmountable barrier to HGT exists, even in complex multicellular eukaryotes. In addition, the discovery of both recent and ancient HGT events in all major eukaryotic groups suggests that HGT has been a regular occurrence throughout the history of eukaryotic evolution. A model of HGT is proposed that suggests both unicellular and early developmental stages as likely entry points for foreign genes into multicellular eukaryotes. PMID:24037739

  8. Stability and Heat Transfer Characteristics of Condensing Films

    NASA Astrophysics Data System (ADS)

    Hermanson, J. C.; Pedersen, P. C.; Allen, J. S.; Shear, M. A.; Chen, Z. Q.; Alexandrou, A. N.

    2002-11-01

    The overall objective of this research is to investigate the fundamental physics of film condensation in reduced gravity. The condensation of vapor on a cool surface is important in many engineering problems,including spacecraft thermal control and also the behavior of condensate films that may form on the interior surfaces of spacecraft. To examine the effects of body force on condensing films, two different geometries have been tested in the laboratory: (1) a stabilizing gravitational body force (+1g, or condensing surface facing 'upwards') and (2) de-stabilizing gravitational body force (-1g, or 'downwards'). For each geometry, different fluid configurations are employed to help isolate the fluid mechanical and thermal mechanisms operative in condensing films. The fluid configurations are (a) a condensing film, and (b) a non-condensing film with film growth by mass addition by through the plate surface. Condensation experiments are conducted in a test cell containing a cooled copper or brass plate with an exposed diameter of 12.7 cm. The metal surface is polished to allow for double-pass shadowgraph imaging, and the test surface is instrumented with imbedded heat transfer gauges and thermocouples. Representative shadowgraph images of a condensing, unstable (-1g) n-pentane film are shown. The interfacial disturbances associated with the de-stabilizing body force leading to droplet formation and break-off can be clearly seen. The heat transfer coefficient associated with the condensing film is shown. The heat transfer coefficient is seen to initially decrease, consistent with the increased thermal resistance due to layer growth. For sufficiently long time, a steady value of heat transfer is observed, accompanied by continuous droplet formation and break-off. The non-condensing cell consists of a stack of thin stainless steel disks 10 cm in diameter mounted in a brass enclosure. The disks are perforated with a regular pattern of 361 holes each 0.25 mm in diameter

  9. Stability and Heat Transfer Characteristics of Condensing Films

    NASA Technical Reports Server (NTRS)

    Hermanson, J. C.; Pedersen, P. C.; Allen, J. S.; Shear, M. A.; Chen, Z. Q.; Alexandrou, A. N.

    2002-01-01

    The overall objective of this research is to investigate the fundamental physics of film condensation in reduced gravity. The condensation of vapor on a cool surface is important in many engineering problems,including spacecraft thermal control and also the behavior of condensate films that may form on the interior surfaces of spacecraft. To examine the effects of body force on condensing films, two different geometries have been tested in the laboratory: (1) a stabilizing gravitational body force (+1g, or condensing surface facing 'upwards') and (2) de-stabilizing gravitational body force (-1g, or 'downwards'). For each geometry, different fluid configurations are employed to help isolate the fluid mechanical and thermal mechanisms operative in condensing films. The fluid configurations are (a) a condensing film, and (b) a non-condensing film with film growth by mass addition by through the plate surface. Condensation experiments are conducted in a test cell containing a cooled copper or brass plate with an exposed diameter of 12.7 cm. The metal surface is polished to allow for double-pass shadowgraph imaging, and the test surface is instrumented with imbedded heat transfer gauges and thermocouples. Representative shadowgraph images of a condensing, unstable (-1g) n-pentane film are shown. The interfacial disturbances associated with the de-stabilizing body force leading to droplet formation and break-off can be clearly seen. The heat transfer coefficient associated with the condensing film is shown. The heat transfer coefficient is seen to initially decrease, consistent with the increased thermal resistance due to layer growth. For sufficiently long time, a steady value of heat transfer is observed, accompanied by continuous droplet formation and break-off. The non-condensing cell consists of a stack of thin stainless steel disks 10 cm in diameter mounted in a brass enclosure. The disks are perforated with a regular pattern of 361 holes each 0.25 mm in diameter

  10. Viral mediated gene transfer to sprouting blood vessels during angiogenesis.

    PubMed

    Alian, Akram; Eldor, Amiram; Falk, Haya; Panet, Amos

    2002-08-01

    Several experimental systems have been applied to investigate the development of new blood vessels. Angiogenesis can be followed ex-vivo by culturing explants of rat aorta 'rings' in biomatrix gels. This angiogenesis system was modified for the study of viral vector mediated gene transfer, using adenovirus, vaccinia- and retroviral vectors. Two modifications were introduced to the model in order to facilitate efficient viral mediated gene transfer, (i) placing the aorta ring on top of a thin layer of collagen such that the angiogenic tissue will be accessible to the viral vector; and (ii) infection of the aorta rings prior to embedding them into the collagen matrix. While adenovirus and vaccinia vectors infected efficiently the aorta rings they induced cell death. Subsequent gene transfer experiments were, therefore, carried with retroviral vectors containing vascular endothelial growth factor (VEGF) and the beta-interferon (IFN) genes. Overexpression of VEGF enhanced significantly microvessel sprouting, while overexpression of IFN-beta induced an antiviral effect. The experimental system described in this study can facilitate the application of other viral vectors to the study of genes that may regulate the complex angiogenic process and thereby open new avenues for vascular gene therapy. PMID:12176137

  11. Gene Transfer in Mycobacterium tuberculosis: Shuttle Phasmids to Enlightenment

    PubMed Central

    JACOBS, WILLIAM R.

    2016-01-01

    Infectious diseases have plagued humankind throughout history and have posed serious public health problems. Yet vaccines have eradicated smallpox and antibiotics have drastically decreased the mortality rate of many infectious agents. These remarkable successes in the control of infections came from knowing the causative agents of the diseases, followed by serendipitous discoveries of attenuated viruses and antibiotics. The discovery of DNA as genetic material and the understanding of how this information translates into specific phenotypes have changed the paradigm for developing new vaccines, drugs, and diagnostic tests. Knowledge of the mechanisms of immunity and mechanisms of action of drugs has led to new vaccines and new antimicrobial agents. The key to the acquisition of the knowledge of these mechanisms has been identifying the elemental causes (i.e., genes and their products) that mediate immunity and drug resistance. The identification of these genes is made possible by being able to transfer the genes or mutated forms of the genes into causative agents or surrogate hosts. Such an approach was limited in Mycobacterium tuberculosis by the difficulty of transferring genes or alleles into M. tuberculosis or a suitable surrogate mycobacterial host. The construction of shuttle phasmids—chimeric molecules that replicate in Escherichia coli as plasmids and in mycobacteria as mycobacteriophages—was instrumental in developing gene transfer systems for M. tuberculosis. This review will discuss M. tuberculosis genetic systems and their impact on tuberculosis research. “I had to know my enemy in order to prevail against him.”Nelson Mandela PMID:26105819

  12. Detecting Horizontal Gene Transfer between Closely Related Taxa.

    PubMed

    Adato, Orit; Ninyo, Noga; Gophna, Uri; Snir, Sagi

    2015-10-01

    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. PMID:26439115

  13. Detecting Horizontal Gene Transfer between Closely Related Taxa

    PubMed Central

    Adato, Orit; Ninyo, Noga; Gophna, Uri; Snir, Sagi

    2015-01-01

    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. PMID:26439115

  14. Specific Gene Repression by CRISPRi System Transferred through Bacterial Conjugation

    PubMed Central

    2014-01-01

    In microbial communities, bacterial populations are commonly controlled using indiscriminate, broad range antibiotics. There are few ways to target specific strains effectively without disrupting the entire microbiome and local environment. Here, we use conjugation, a natural DNA horizontal transfer process among bacterial species, to deliver an engineered CRISPR interference (CRISPRi) system for targeting specific genes in recipient Escherichia coli cells. We show that delivery of the CRISPRi system is successful and can specifically repress a reporter gene in recipient cells, thereby establishing a new tool for gene regulation across bacterial cells and potentially for bacterial population control. PMID:25409531

  15. Antibiotics and gene transfer in swine gut bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mammalian gastrointestinal (GI) tract hosts a diverse collection bacteria, most of which are beneficial for host health. This bacterial community also supports a community of viruses that infect bacteria (called bacteriophages or phages). Phages transfer genes between bacteria, and phage-media...

  16. Transferred interbacterial antagonism genes augment eukaryotic innate immune function

    PubMed Central

    Chou, Seemay; Daugherty, Matthew D.; Peterson, S. Brook; Biboy, Jacob; Yang, Youyun; Jutras, Brandon L.; Fritz-Laylin, Lillian K.; Ferrin, Michael A.; Harding, Brittany N.; Jacobs-Wagner, Christine; Yang, X. Frank; Vollmer, Waldemar; Malik, Harmit S.

    2015-01-01

    Horizontal gene transfer (HGT) allows organisms to rapidly acquire adaptive traits1. Though documented instances of HGT from bacteria to eukaryotes remain rare, bacteria represent a rich source of new functions potentially available for co-option2. One benefit that genes of bacterial origin could provide to eukaryotes is the capacity to produce anti-bacterials, which have evolved in prokaryotes as the result of eons of interbacterial competition. The type VI secretion amidase effector (Tae) proteins are potent bacteriocidal enzymes that degrade the cell wall when delivered into competing bacterial cells by the type VI secretion system (T6SS)3. Here we show that tae genes have been transferred to eukaryotes on at least six occasions, and that the resulting domesticated amidase effector (dae) genes have been preserved for hundreds of millions of years via purifying selection. We show that the dae genes acquired eukaryotic secretion signals, are expressed within recipient organisms, and encode active antibacterial toxins that possess substrate specificity matching extant Tae proteins of the same lineage. Finally, we show that a dae gene in the deer tick Ixodes scapularis limits proliferation of Borrelia burgdorferi, the etiologic agent of Lyme disease. Our work demonstrates that a family of horizontally acquired toxins honed to mediate interbacterial antagonism confers previously undescribed antibacterial capacity to eukaryotes. We speculate that the selective pressure imposed by competition between bacteria has produced a reservoir of genes encoding diverse antimicrobial functions that are tailored for facile co-option by eukaryotic innate immune systems. PMID:25470067

  17. Detection of horizontal gene transfers from phylogenetic comparisons.

    PubMed

    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

  18. Rescuing the Failing Heart by Targeted Gene Transfer

    PubMed Central

    Kawase, Yoshiaki; Ladage, Dennis; Hajjar, Roger J.

    2011-01-01

    Congestive heart failure is a major cause of morbidity and mortality in the US. While progress in conventional treatments is making steady and incremental gains to reduce heart failure mortality, there is a critical need to explore new therapeutic approaches. Gene therapy was initially applied in the clinical setting for inherited monogenic disorders. It is now apparent that gene therapy has broader potential that also includes acquired polygenic diseases, such as congestive heart failure. Recent advances in understanding of the molecular basis of myocardial dysfunction, together with the evolution of increasingly efficient gene transfer technology, has placed heart failure within reach of gene-based therapy. Furthermore, the recent successful and safe completion of a phase 2 trial targeting the sarcoplasmic reticulum calcium ATPase pump (SERCA2a) along with the start of more recent phase 1 trials usher a new era for gene therapy for the treatment of heart failure. PMID:21371634

  19. Direct gene transfer into human cultured cells facilitated by laser micropuncture of the cell membrane

    SciTech Connect

    Tao, W.; Wilkinson, J.; Stanbridge, E.J.; Berns, M.W.

    1987-06-01

    The selective alteration of the cellular genome by laser microbeam irradiation has been extensively applied in cell biology. The authors report here the use of the third harmonic (355 nm) of an yttrium-aluminum garnet laser to facilitate the direct transfer of the neo gene into cultured human HT1080-6TG cells. The resultant transformants were selected in medium containing an aminoglycoside antibiotic, G418. Integration of the neo gene into individual human chromosomes and expression of the gene were demonstrated by Southern blot analyses, microcell-mediated chromosome transfer, and chromosome analyses. The stability of the integrated neo gene in the transformants was shown by a comparative growth assay in selective and nonselective media. Transformation and incorporation of the neo gene into the host genome occurred at a frequency of 8 x 10 /sup -4/-3 x 10/sup -3/. This method appears to be 100-fold more efficient than the standard calcium phosphate-mediated method of DNA transfer.

  20. AAV-mediated gene transfer to the mouse CNS

    PubMed Central

    Stoica, Lorelei; Ahmed, Seemin S.

    2013-01-01

    Recombinant adeno associated virus (rAAV) vectors are great tools for gene transfer due to their ability to mediate long-term gene expression. Recombinant AAVs have been used at various ages of development with no apparent toxicity. There are multiple ways of delivering AAV vectors to the CNS, depending on the stage of development of the mouse. In neonates, intravascular injections into the facial vein are often used. In adults, direct injections into target regions of the brain are achieved with great spatiotemporal control through stereotaxic surgeries. Recently, discoveries of new AAV vectors with the ability to cross the blood brain barrier have made it possible to also target the adult CNS by intravascular injections. rAAVs have been successfully used as gene transfer vehicles in multiple animal models of CNS disorders, and several clinical trials are currently underway. PMID:23686825

  1. Endosymbiotic gene transfer from prokaryotic pangenomes: Inherited chimerism in eukaryotes

    PubMed Central

    Ku, Chuan; Nelson-Sathi, Shijulal; Roettger, Mayo; Garg, Sriram; Hazkani-Covo, Einat; Martin, William F.

    2015-01-01

    Endosymbiotic theory in eukaryotic-cell evolution rests upon a foundation of three cornerstone partners—the plastid (a cyanobacterium), the mitochondrion (a proteobacterium), and its host (an archaeon)—and carries a corollary that, over time, the majority of genes once present in the organelle genomes were relinquished to the chromosomes of the host (endosymbiotic gene transfer). However, notwithstanding eukaryote-specific gene inventions, single-gene phylogenies have never traced eukaryotic genes to three single prokaryotic sources, an issue that hinges crucially upon factors influencing phylogenetic inference. In the age of genomes, single-gene trees, once used to test the predictions of endosymbiotic theory, now spawn new theories that stand to eventually replace endosymbiotic theory with descriptive, gene tree-based variants featuring supernumerary symbionts: prokaryotic partners distinct from the cornerstone trio and whose existence is inferred solely from single-gene trees. We reason that the endosymbiotic ancestors of mitochondria and chloroplasts brought into the eukaryotic—and plant and algal—lineage a genome-sized sample of genes from the proteobacterial and cyanobacterial pangenomes of their respective day and that, even if molecular phylogeny were artifact-free, sampling prokaryotic pangenomes through endosymbiotic gene transfer would lead to inherited chimerism. Recombination in prokaryotes (transduction, conjugation, transformation) differs from recombination in eukaryotes (sex). Prokaryotic recombination leads to pangenomes, and eukaryotic recombination leads to vertical inheritance. Viewed from the perspective of endosymbiotic theory, the critical transition at the eukaryote origin that allowed escape from Muller’s ratchet—the origin of eukaryotic recombination, or sex—might have required surprisingly little evolutionary innovation. PMID:25733873

  2. Endosymbiotic gene transfer from prokaryotic pangenomes: Inherited chimerism in eukaryotes.

    PubMed

    Ku, Chuan; Nelson-Sathi, Shijulal; Roettger, Mayo; Garg, Sriram; Hazkani-Covo, Einat; Martin, William F

    2015-08-18

    Endosymbiotic theory in eukaryotic-cell evolution rests upon a foundation of three cornerstone partners--the plastid (a cyanobacterium), the mitochondrion (a proteobacterium), and its host (an archaeon)--and carries a corollary that, over time, the majority of genes once present in the organelle genomes were relinquished to the chromosomes of the host (endosymbiotic gene transfer). However, notwithstanding eukaryote-specific gene inventions, single-gene phylogenies have never traced eukaryotic genes to three single prokaryotic sources, an issue that hinges crucially upon factors influencing phylogenetic inference. In the age of genomes, single-gene trees, once used to test the predictions of endosymbiotic theory, now spawn new theories that stand to eventually replace endosymbiotic theory with descriptive, gene tree-based variants featuring supernumerary symbionts: prokaryotic partners distinct from the cornerstone trio and whose existence is inferred solely from single-gene trees. We reason that the endosymbiotic ancestors of mitochondria and chloroplasts brought into the eukaryotic--and plant and algal--lineage a genome-sized sample of genes from the proteobacterial and cyanobacterial pangenomes of their respective day and that, even if molecular phylogeny were artifact-free, sampling prokaryotic pangenomes through endosymbiotic gene transfer would lead to inherited chimerism. Recombination in prokaryotes (transduction, conjugation, transformation) differs from recombination in eukaryotes (sex). Prokaryotic recombination leads to pangenomes, and eukaryotic recombination leads to vertical inheritance. Viewed from the perspective of endosymbiotic theory, the critical transition at the eukaryote origin that allowed escape from Muller's ratchet--the origin of eukaryotic recombination, or sex--might have required surprisingly little evolutionary innovation. PMID:25733873

  3. Horizontal gene transfer confers adaptive advantages to phytopathogenic fungi: a case study of catalase-peroxidase in Fusarium verticillioides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Horizontal gene transfer (HGT), the exchange and stable integration of genetic material between different evolutionary lineages, is widely observed in fungi. We hypothesize that successful stabilization of HGT elements provides adaptive advantages (e.g., virulence). Catalase/peroxidases (KatGs) are ...

  4. Human gene transfer: Characterization of human tumor-infiltrating lymphocytes as vehicles for retroviral-mediated gene transfer in man

    SciTech Connect

    Kasid, A.; Morecki, S.; Aebersold, P.; Cornetta, K.; Culver, K.; Freeman, S.; Director, E.; Lotze, M.T.; Blaese, R.M.; Anderson, W.F.; Rosenberg, S.A. )

    1990-01-01

    Tumor-infiltrating lymphocytes (TILs) are cells generated from tumor suspensions cultured in interleukin 2 that can mediate cancer regression when adoptively transferred into mice or humans. Since TILs proliferate rapidly in vitro, recirculate, and preferentially localize at the tumor site in vivo, they provide an attractive model for delivery of exogenous genetic material into man. To determine whether efficient gene transfer into TILs is feasible. The authors transduced human TILs with the bacterial gene for neomycin-resistance (Neo{sup R}) using the retroviral vector N2. The transduced TIL populations were stable and polyclonal with respect to the intact Neo{sup R} gene integration and expressed high levels of neomycin phosphotransferase activity. The Neo{sup R} gene insertion did not alter the in vitro growth pattern and interleukin 2 dependence of the transduced TILs. Analyses of T-cell receptor gene rearrangement for {beta}- and {gamma}-chain genes revealed the oligoclonal nature of the TIL populations with no major change in the DNA rearrangement patterns or the levels of mRNA expression of the {beta} and {gamma} chains following transduction and selection of TILs in the neomycin analog G418. Human TILs expressed mRNA for tumor necrosis factors ({alpha} and {beta}) and interleukin 2 receptor P55. This pattern of cytokine-mRNA expression was not significantly altered following the transduction of TILs. The studies demonstrate the feasibility of TILs as suitable cellular vehicles for the introduction of therapeutic genes into patients receiving autologous TILs.

  5. Immunotherapy of Malignancy by in vivo Gene Transfer into Tumors

    NASA Astrophysics Data System (ADS)

    Plautz, Gregory E.; Yang, Zhi-Yong; Wu, Bei-Yue; Gao, Xiang; Huang, Leaf; Nabel, Gary J.

    1993-05-01

    The immune system confers protection against a variety of pathogens and contributes to the surveillance and destruction of neoplastic cells. Several cell types participate in the recognition and lysis of tumors, and appropriate immune stimulation provides therapeutic effects in malignancy. Foreign major histocompatibility complex (MHC) proteins also serve as a potent stimulus to the immune system. In this report, a foreign MHC gene was introduced directly into malignant tumors in vivo in an effort to stimulate tumor rejection. In contrast to previous attempts to induce tumor immunity by cell-mediated gene transfer, the recombinant gene was introduced directly into tumors in vivo. Expression of the murine class I H-2K^s gene within the CT26 mouse colon adenocarcinoma (H-2K^d) or the MCA 106 fibrosarcoma (H-2K^b) induced a cytotoxic T-cell response to H-2K^s and, more importantly, to other antigens present on unmodified tumor cells. This immune response attenuated tumor growth and caused complete tumor regression in many cases. Direct gene transfer in vivo can therefore induce cell-mediated immunity against specific gene products, which provides an immunotherapeutic effect for malignancy, and potentially can be applied to the treatment of cancer and infectious diseases in man.

  6. [Experimental study of vascular gene transfer using soluble stent].

    PubMed

    Huang, Z; Gou, J; Li, X

    1997-05-01

    We assessed the possibility of gene transfer into anastomotic arteries in vivo using soluble stent containing Adv5-CMV/LacZ. After being soaked in a high concentration solution of glucose containing Adv5-CMV (control group) or Adv5-CMV/LacZ (treatment group) for 30 minutes, we inserted soluble stents into the lumina of cut rat carotid arteries, and end-to-end anastomoses of cut rat carotid were performed with standard microvascular surgical technique. 16 rats were killed after two weeks, the segments of anastomotic carotid arteries were prepared for assessing beta-galactosidase activity and histochemical staining. In the control group, the anastomotic arteries did not have detectable level of beta-galactosidase expression. In the treatment group, the amount of beta-galactosidase expression was 9.80 x 10-3 u/g tissue. Microscopic examination of histochemically stained arteries demonstrated that gene transfered not only to endothelial cells but also to smooth muscle cells, and all anastomotic arteries were transfered in the treatment group, but none of arteries revealed blue in the control group. The results of this experimental study suggested that soluble stent be a new method of direct gene transfer into arteries in vivo. PMID:10374573

  7. Stability domains of actin genes and genomic evolution

    NASA Astrophysics Data System (ADS)

    Carlon, E.; Dkhissi, A.; Malki, M. Lejard; Blossey, R.

    2007-11-01

    In eukaryotic genes, the protein coding sequence is split into several fragments, the exons, separated by noncoding DNA stretches, the introns. Prokaryotes do not have introns in their genomes. We report calculations of the stability domains of actin genes for various organisms in the animal, plant, and fungi kingdoms. Actin genes have been chosen because they have been highly conserved during evolution. In these genes, all introns were removed so as to mimic ancient genes at the time of the early eukaryotic development, i.e., before intron insertion. Common stability boundaries are found in evolutionarily distant organisms, which implies that these boundaries date from the early origin of eukaryotes. In general, the boundaries correspond with intron positions in the actins of vertebrates and other animals, but not much for plants and fungi. The sharpest boundary is found in a locus where fungi, algae, and animals have introns in positions separated by one nucleotide only, which identifies a hot spot for insertion. These results suggest that some introns may have been incorporated into the genomes through a thermodynamically driven mechanism, in agreement with previous observations on human genes. They also suggest a different mechanism for intron insertion in plants and animals.

  8. Stability and functional effectiveness of phosphorothioate modified duplex DNA and synthetic 'mini-genes'.

    PubMed Central

    Ciafrè, S A; Rinaldi, M; Gasparini, P; Seripa, D; Bisceglia, L; Zelante, L; Farace, M G; Fazio, V M

    1995-01-01

    Several gene transfer techniques that employ 'naked DNA' molecules have recently been developed and numerous gene therapy protocols that make use of 'naked-DNA' have been proposed. We studied the possibility of enhancing the stability of 'naked DNA vectors' and thus also gene transfer and expression efficiencies, by constructing phosphorothioate (PS-) double strand DNA molecules and functional transcription units. We first synthesized short PS-double strand DNA molecules by the annealing of two complementary, 35 nt long, oligonucleotides. The accessibility of DNA modifying enzymes to this molecule was significantly decreased: T4-ligase and kinase activity were respectively reduced up to 1/2 and to 1/6, as compared to the normal phosphodiester molecule. Nucleolytic stability was increased either to purified enzymes (DNase I and Bal31) or to incubations in fresh serum, cell culture medium or in muscle protein extract. Phosphorothioate end-capped complete eukaryotic transcription units (obtained by Taq polymerase amplification with PS-primers) were not significantly protected from nucleolytic attack. On the contrary, synthetic transcription units, 'mini genes', obtained by Taq amplification with 1, 2 or 3 PS-dNTP substitutions, were resistant to DNase I and Bal31 nucleolytic activity. Transcription efficiency, driven by the T7 promoter, was 96.5, 95 and 33.5% (respectively with 1, 2 or 3 substitutions), as compared to the normal phosphodiester molecules. Images PMID:7479077

  9. Effect of radiative heat transfer on the convective stability of a fluid in a slot

    NASA Astrophysics Data System (ADS)

    Kural, O.

    1988-06-01

    A fluid, confined between two vertical flat plates, with a linear temperature gradient decreasing upwards, is investigated analytically for convective stability under the influence of radiative heat transfer. The effect of radiative transfer is accounted for by use of the Milne-Eddington differential approximation. It is shown that three dimensionless parameters influence the stability: the optical thickness, tau, a parameter A which compares radiative and conductive fluxes, and E, which combines the effects of boundary surface properties with the 'color' properties of the medium. It is shown that radiative heat transfer has a stabilizing effect on the system and that A and tau exert strong influences.

  10. Source–sink plasmid transfer dynamics maintain gene mobility in soil bacterial communities

    PubMed Central

    Wood, A. Jamie

    2016-01-01

    Horizontal gene transfer is a fundamental process in bacterial evolution that can accelerate adaptation via the sharing of genes between lineages. Conjugative plasmids are the principal genetic elements mediating the horizontal transfer of genes, both within and between bacterial species. In some species, plasmids are unstable and likely to be lost through purifying selection, but when alternative hosts are available, interspecific plasmid transfer could counteract this and maintain access to plasmid-borne genes. To investigate the evolutionary importance of alternative hosts to plasmid population dynamics in an ecologically relevant environment, we established simple soil microcosm communities comprising two species of common soil bacteria, Pseudomonas fluorescens and Pseudomonas putida, and a mercury resistance (HgR) plasmid, pQBR57, both with and without positive selection [i.e., addition of Hg(II)]. In single-species populations, plasmid stability varied between species: although pQBR57 survived both with and without positive selection in P. fluorescens, it was lost or replaced by nontransferable HgR captured to the chromosome in P. putida. A simple mathematical model suggests these differences were likely due to pQBR57’s lower intraspecific conjugation rate in P. putida. By contrast, in two-species communities, both models and experiments show that interspecific conjugation from P. fluorescens allowed pQBR57 to persist in P. putida via source–sink transfer dynamics. Moreover, the replacement of pQBR57 by nontransferable chromosomal HgR in P. putida was slowed in coculture. Interspecific transfer allows plasmid survival in host species unable to sustain the plasmid in monoculture, promoting community-wide access to the plasmid-borne accessory gene pool and thus potentiating future evolvability. PMID:27385827

  11. Source-sink plasmid transfer dynamics maintain gene mobility in soil bacterial communities.

    PubMed

    Hall, James P J; Wood, A Jamie; Harrison, Ellie; Brockhurst, Michael A

    2016-07-19

    Horizontal gene transfer is a fundamental process in bacterial evolution that can accelerate adaptation via the sharing of genes between lineages. Conjugative plasmids are the principal genetic elements mediating the horizontal transfer of genes, both within and between bacterial species. In some species, plasmids are unstable and likely to be lost through purifying selection, but when alternative hosts are available, interspecific plasmid transfer could counteract this and maintain access to plasmid-borne genes. To investigate the evolutionary importance of alternative hosts to plasmid population dynamics in an ecologically relevant environment, we established simple soil microcosm communities comprising two species of common soil bacteria, Pseudomonas fluorescens and Pseudomonas putida, and a mercury resistance (Hg(R)) plasmid, pQBR57, both with and without positive selection [i.e., addition of Hg(II)]. In single-species populations, plasmid stability varied between species: although pQBR57 survived both with and without positive selection in P. fluorescens, it was lost or replaced by nontransferable Hg(R) captured to the chromosome in P. putida A simple mathematical model suggests these differences were likely due to pQBR57's lower intraspecific conjugation rate in P. putida By contrast, in two-species communities, both models and experiments show that interspecific conjugation from P. fluorescens allowed pQBR57 to persist in P. putida via source-sink transfer dynamics. Moreover, the replacement of pQBR57 by nontransferable chromosomal Hg(R) in P. putida was slowed in coculture. Interspecific transfer allows plasmid survival in host species unable to sustain the plasmid in monoculture, promoting community-wide access to the plasmid-borne accessory gene pool and thus potentiating future evolvability. PMID:27385827

  12. Evaluation of Hose in Hose Transfer Line Service Life for Hanford's Interim Stabilization Program

    SciTech Connect

    TORRES, T.D.

    2000-08-24

    RPP-6153, Engineering Task Plan for Hose-in-Hose Transfer System for the Interim Stabilization Program, defines the programmatic goals, functional requirements, and technical criteria for the development and subsequent installation of transfer line equipment to support Hanford's Interim Stabilization Program. RPP-6028, Specification for Hose in Hose Transfer Lines for Hanford's Interim Stabilization Program, has been issued to define the specific requirements for the design, manufacture, and verification of transfer line assemblies for specific waste transfer applications. Included in RPP-6028 are tables defining the chemical constituents of concern to which transfer lines will be exposed. Current Interim Stabilization Program planning forecasts that the at-grade transfer lines will be required to convey pumpable waste for as much as three years after commissioning. Prudent engineering dictates that the equipment placed in service have a working life in excess of this forecasted time period, with some margin to allow for future adjustments to the planned schedule. This document evaluates the effective service life of the Hose-in-Hose Transfer Lines, based on information submitted by the manufacturer and published literature. The effective service life of transfer line assemblies is a function of several factors. Foremost among these are process fluid characteristics, ambient environmental conditions, and the manufacturer's stated shelf life. This evaluation examines the manufacturer's certification of shelf life, the manufacturer's certifications of chemical compatibility with waste, and published literature on the effects of exposure to ionizing radiation on the mechanical properties of elastomeric materials to evaluate transfer line service life.

  13. Nano-Sized Sunflower Polycations As Effective Gene Transfer Vehicles.

    PubMed

    Cheng, Yilong; Wei, Hua; Tan, James-Kevin Y; Peeler, David J; Maris, Don O; Sellers, Drew L; Horner, Philip J; Pun, Suzie H

    2016-05-01

    The architecture of polycations plays an important role in both gene transfection efficiency and cytotoxicity. In this work, a new polymer, sunflower poly(2-dimethyl amino)ethyl methacrylate) (pDMAEMA), is prepared by atom transfer radical polymerization and employed as nucleic acid carriers compared to linear pDMAEMA homopolymer and comb pDMAEMA. The sunflower pDMAEMAs show higher IC50 , greater buffering capacity, and stronger binding capacity toward plasmid DNA than their linear and comb counterparts. In vitro transfection studies demonstrate that sunflower pDMAEMAs exhibit high transfection efficiency as well as relatively low cytotoxicity in complete growth medium. In vivo gene delivery by intraventricular injection to the brain shows that sunflower polymer delivers plasmid DNA more effectively than comb polymer. This study provides a new insight into the relationship between polymeric architecture and gene delivery capability, and as well as a useful means to design potent vectors for successful gene delivery. PMID:27061622

  14. Electroporation-Mediated Gene Transfer Directly to the Swine Heart

    PubMed Central

    Hargrave, Barbara; Downey, Harre; Strange, Robert; Murray, Len; Cinnamond, Cade; Lundberg, Cathryn; Israel, Annelise; Chen, Yeong-Jer; Marshall, William; Heller, Richard

    2012-01-01

    In vivo gene transfer to the ischemic heart via electroporation holds promise as a potential therapeutic approach for the treatment of heart disease. In the current study, we investigated the use of in vivo electroporation for gene transfer using 3 different penetrating electrodes and one non-penetrating electrode. The hearts of adult male swine were exposed through a sternotomy. Eight electric pulses synchronized to the rising phase of the R wave of the ECG were administered at varying pulse widths and field strengths following an injection of either a plasmid encoding luciferase or one encoding green fluorescent protein. Four sites on the anterior wall of the left ventricle were treated. Animals were euthanized 48 hours after injection and electroporation and gene expression was determined. Results were compared to sites in the heart that received plasmid injection but no electric pulses or were not treated. Gene expression was higher in all electroporated sites when compared to injection only sites demonstrating the robustness of this approach. Our results provide evidence that in vivo electroporation can be a safe and effective non-viral method for delivering genes to the heart, in vivo. PMID:22456328

  15. Adenovirus serotype 5 hexon mediates liver gene transfer.

    PubMed

    Waddington, Simon N; McVey, John H; Bhella, David; Parker, Alan L; Barker, Kristeen; Atoda, Hideko; Pink, Rebecca; Buckley, Suzanne M K; Greig, Jenny A; Denby, Laura; Custers, Jerome; Morita, Takashi; Francischetti, Ivo M B; Monteiro, Robson Q; Barouch, Dan H; van Rooijen, Nico; Napoli, Claudio; Havenga, Menzo J E; Nicklin, Stuart A; Baker, Andrew H

    2008-02-01

    Adenoviruses are used extensively as gene transfer agents, both experimentally and clinically. However, targeting of liver cells by adenoviruses compromises their potential efficacy. In cell culture, the adenovirus serotype 5 fiber protein engages the coxsackievirus and adenovirus receptor (CAR) to bind cells. Paradoxically, following intravascular delivery, CAR is not used for liver transduction, implicating alternate pathways. Recently, we demonstrated that coagulation factor (F)X directly binds adenovirus leading to liver infection. Here, we show that FX binds to the Ad5 hexon, not fiber, via an interaction between the FX Gla domain and hypervariable regions of the hexon surface. Binding occurs in multiple human adenovirus serotypes. Liver infection by the FX-Ad5 complex is mediated through a heparin-binding exosite in the FX serine protease domain. This study reveals an unanticipated function for hexon in mediating liver gene transfer in vivo. PMID:18267072

  16. Gene transfer from a parasitic flowering plant to a fern

    PubMed Central

    Davis, Charles C; Anderson, William R; Wurdack, Kenneth J

    2005-01-01

    The rattlesnake fern (Botrychium virginianum (L.) Sw.) is obligately mycotrophic and widely distributed across the northern hemisphere. Three mitochondrial gene regions place this species with other ferns in Ophioglossaceae, while two regions place it as a member of the largely parasitic angiosperm order Santalales (sandalwoods and mistletoes). These discordant phylogenetic placements suggest that part of the genome in B. virginianum was acquired by horizontal gene transfer (HGT), perhaps from root-parasitic Loranthaceae. These transgenes are restricted to B. virginianum and occur across the range of the species. Molecular and life-history traits indicate that the transfer preceded the global expansion of B. virginianum, and that the latter may have happened very rapidly. This is the first report of HGT from an angiosperm to a fern, through either direct parasitism or the mediation of interconnecting fungal symbionts. PMID:16191635

  17. A Rice Stowaway MITE for Gene Transfer in Yeast

    PubMed Central

    Fattash, Isam; Bhardwaj, Priyanka; Hui, Caleb; Yang, Guojun

    2013-01-01

    Miniature inverted repeat transposable elements (MITEs) lack protein coding capacity and often share very limited sequence similarity with potential autonomous elements. Their capability of efficient transposition and dramatic amplification led to the proposition that MITEs are an untapped rich source of materials for transposable element (TE) based genetic tools. To test the concept of using MITE sequence in gene transfer, a rice Stowaway MITE previously shown to excise efficiently in yeast was engineered to carry cargo genes (neo and gfp) for delivery into the budding yeast genome. Efficient excision of the cargo gene cassettes was observed even though the excision frequency generally decreases with the increase of the cargo sizes. Excised elements insert into new genomic loci efficiently, with about 65% of the obtained insertion sites located in genes. Elements at the primary insertion sites can be remobilized, frequently resulting in copy number increase of the element. Surprisingly, the orientation of a cargo gene (neo) on a construct bearing dual reporter genes (gfp and neo) was found to have a dramatic effect on transposition frequency. These results demonstrated the concept that MITE sequences can be useful in engineering genetic tools to deliver cargo genes into eukaryotic genomes. PMID:23704977

  18. Detection of homologous horizontal gene transfer in SNP data

    Energy Science and Technology Software Center (ESTSC)

    2012-07-23

    We study the detection of mutations, sequencing errors, and homologous horizontal gene transfers (HGT) in a set of closely related microbial genomes. We base the model on single nucleotide polymorphisms (SNP's) and break the genomes into blocks to handle the rearrangement problem. Then we apply a synamic programming algorithm to model whether changes within each block are likely a result of mutations, sequencing errors, or HGT.

  19. Stability of coaxial jets confined in a tube with heat and mass transfer

    NASA Astrophysics Data System (ADS)

    Mohanta, Lokanath; Cheung, Fan-Bill; Bajorek, Stephen M.

    2016-02-01

    A linear temporal stability of coaxial confined jets in a vertical tube involving heat and mass transfer at the interface is presented in this paper. A potential flow analysis that includes the effect of viscosity at the interface is performed in analyzing the stability of the system. Film boiling in a vertical tube gives rise to the flow configuration explored in this work. The effects of various non-dimensional parameters on the growth rate and the neutral curve are discussed. The heat transfer at the interface has been characterized by introducing a heat flux ratio between the conduction heat flux and the evaporation heat flux. Viscous forces and the heat and mass transfer at the interface are found to stabilize the flow both in the capillary instability region and Kelvin-Helmholtz instability region. Increasing heat and mass transfer at the interface stabilizes the flow to small as well as very large wave numbers.

  20. Probing the Mass-Transfer Stability Limit in Close Binaries

    NASA Astrophysics Data System (ADS)

    D'Souza, M. C. R.; Motl, P. M.; Tohline, J. E.; Frank, J.

    2004-12-01

    We present results from numerical simulations that follow the nonlinear development of mass-transfer instabilities in close binary star systems. A self-consistent-field (SCF) technique is used to construct initial equilibrium models, which are synchronously rotating, semi-detached, polytropic stars on circular orbits. These models are evolved with an Eulerian, finite-difference hydrodynamics code in a fully self-consistent manner. Results are presented for binary systems having a wide range of initial conditions; emphasis is placed on systems in which the mass-transfer stream directly impacts the surface of the accreting star. Some systems are dynamically unstable and result in a merger; others approach a long-term, stable phase of mass transfer. The time-evolutionary behavior of the binary separation, mass transfer rate, spin angular momentum of the accretor, and gravitational wave strain are presented.

  1. Horizontal Gene Transfer Regulation in Bacteria as a “Spandrel” of DNA Repair Mechanisms

    PubMed Central

    Fall, Saliou; Mercier, Anne; Bertolla, Franck; Calteau, Alexandra; Gueguen, Laurent; Perrière, Guy; Vogel, Timothy M.; Simonet, Pascal

    2007-01-01

    Horizontal gene transfer (HGT) is recognized as the major force for bacterial genome evolution. Yet, numerous questions remain about the transferred genes, their function, quantity and frequency. The extent to which genetic transformation by exogenous DNA has occurred over evolutionary time was initially addressed by an in silico approach using the complete genome sequence of the Ralstonia solanacearum GMI1000 strain. Methods based on phylogenetic reconstruction of prokaryote homologous genes families detected 151 genes (13.3%) of foreign origin in the R. solanacearum genome and tentatively identified their bacterial origin. These putative transfers were analyzed in comparison to experimental transformation tests involving 18 different genomic DNA positions in the genome as sites for homologous or homeologous recombination. Significant transformation frequency differences were observed among these positions tested regardless of the overall genomic divergence of the R. solanacearum strains tested as recipients. The genomic positions containing the putative exogenous DNA were not systematically transformed at the highest frequencies. The two genomic “hot spots”, which contain recA and mutS genes, exhibited transformation frequencies from 2 to more than 4 orders of magnitude higher than positions associated with other genes depending on the recipient strain. These results support the notion that the bacterial cell is equipped with active mechanisms to modulate acquisition of new DNA in different genomic positions. Bio-informatics study correlated recombination “hot-spots” to the presence of Chi-like signature sequences with which recombination might be preferentially initiated. The fundamental role of HGT is certainly not limited to the critical impact that the very rare foreign genes acquired mainly by chance can have on the bacterial adaptation potential. The frequency to which HGT with homologous and homeologous DNA happens in the environment might have led

  2. Selective Gene Transfer to the Retina Using Intravitreal Ultrasound Irradiation

    PubMed Central

    Sonoda, Shozo; Tachibana, Katsuro; Yamashita, Toshifumi; Shirasawa, Makoto; Terasaki, Hiroto; Uchino, Eisuke; Suzuki, Ryo; Maruyama, Kazuo; Sakamoto, Taiji

    2012-01-01

    This paper aims to evaluate the efficacy of intravitreal ultrasound (US) irradiation for green fluorescent protein (GFP) plasmid transfer into the rabbit retina using a miniature US transducer. Intravitreal US irradiation was performed by a slight modification of the transconjunctival sutureless vitrectomy system utilizing a small probe. After vitrectomy, the US probe was inserted through a scleral incision. A mixture of GFP plasmid (50 μL) and bubble liposomes (BLs; 50 μL) was injected into the vitreous cavity, and US was generated to the retina using a SonoPore 4000. The control group was not exposed to US. After 72 h, the gene-transfer efficiency was quantified by counting the number of GFP-positive cells. The retinas that received plasmid, BL, and US showed a significant increase in the number (average ± SEM) of GFP-positive cells (32 ± 4.9; n = 7; P < 0.01 ). No GFP-positive cells were observed in the control eyes (n = 7). Intravitreal retinal US irradiation can transfer the GFP plasmid into the retina without causing any apparent damage. This procedure could be used to transfer genes and drugs directly to the retina and therefore has potential therapeutic value. PMID:22518277

  3. Dynamic monitoring of horizontal gene transfer in soil

    NASA Astrophysics Data System (ADS)

    Cheng, H. Y.; Masiello, C. A.; Silberg, J. J.; Bennett, G. N.

    2015-12-01

    Soil microbial gene expression underlies microbial behaviors (phenotypes) central to many aspects of C, N, and H2O cycling. However, continuous monitoring of microbial gene expression in soils is challenging because genetically-encoded reporter proteins widely used in the lab are difficult to deploy in soil matrices: for example, green fluorescent protein cannot be easily visualized in soils, even in the lab. To address this problem we have developed a reporter protein that releases small volatile gases. Here, we applied this gas reporter in a proof-of-concept soil experiment, monitoring horizontal gene transfer, a microbial activity that alters microbial genotypes and phenotypes. Horizontal gene transfer is central to bacterial evolution and adaptation and is relevant to problems such as the spread of antibiotic resistance, increasing metal tolerance in superfund sites, and bioremediation capability of bacterial consortia. This process is likely to be impacted by a number of matrix properties not well-represented in the petri dish, such as microscale variations in water, nutrients, and O2, making petri-dish experiments a poor proxy for environmental processes. We built a conjugation system using synthetic biology to demonstrate the use of gas-reporting biosensors in safe, lab-based biogeochemistry experiments, and here we report the use of these sensors to monitor horizontal gene transfer in soils. Our system is based on the F-plasmid conjugation in Escherichia coli. We have found that the gas signal reports on the number of cells that acquire F-plasmids (transconjugants) in a loamy Alfisol collected from Kellogg Biological Station. We will report how a gas signal generated by transconjugants varies with the number of F-plasmid donor and acceptor cells seeded in a soil, soil moisture, and soil O2 levels.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27307274

  5. Evidence of horizontal gene transfer between obligate leaf nodule symbionts.

    PubMed

    Pinto-Carbó, Marta; Sieber, Simon; Dessein, Steven; Wicker, Thomas; Verstraete, Brecht; Gademann, Karl; Eberl, Leo; Carlier, Aurelien

    2016-09-01

    Bacteria of the genus Burkholderia establish an obligate symbiosis with plant species of the Rubiaceae and Primulaceae families. The bacteria, housed within the leaves, are transmitted hereditarily and have not yet been cultured. We have sequenced and compared the genomes of eight bacterial leaf nodule symbionts of the Rubiaceae plant family. All of the genomes exhibit features consistent with genome erosion. Genes potentially involved in the biosynthesis of kirkamide, an insecticidal C7N aminocyclitol, are conserved in most Rubiaceae symbionts. However, some have partially lost the kirkamide pathway due to genome erosion and are unable to synthesize the compound. Kirkamide synthesis is therefore not responsible for the obligate nature of the symbiosis. More importantly, we find evidence of intra-clade horizontal gene transfer (HGT) events affecting genes of the secondary metabolism. This indicates that substantial gene flow can occur at the early stages following host restriction in leaf nodule symbioses. We propose that host-switching events and plasmid conjugative transfers could have promoted these HGTs. This genomic analysis of leaf nodule symbionts gives, for the first time, new insights in the genome evolution of obligate symbionts in their early stages of the association with plants. PMID:26978165

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

    PubMed

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

    2016-01-01

    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. PMID:27307274

  7. PEGylated Cationic Serum Albumin for Boosting Retroviral Gene Transfer.

    PubMed

    Palesch, David; Boldt, Felix; Müller, Janis A; Eisele, Klaus; Stürzel, Christina M; Wu, Yuzhou; Münch, Jan; Weil, Tanja

    2016-08-17

    Retroviral vectors are common tools for introducing genes into the genome of a cell. However, low transduction rates are a major limitation in retroviral gene transfer, especially in clinical applications. We generated cationic human serum albumin (cHSA) protected by a shell of poly(ethylene glycol) (PEG); this significantly enhanced retroviral gene transduction with potentially attractive pharmacokinetics and low immunogenicity. By screening a panel of chemically optimized HSA compounds, we identified a very potent enhancer that boosted the transduction rates of viral vectors. Confocal microscopy revealed a drastically increased number of viral particles attached to the surfaces of target cells. In accordance with the positive net charge of cationic and PEGylated HSA, this suggests a mechanism of action in which the repulsion of the negatively charged cellular and viral vector membranes is neutralized, thereby promoting attachment and ultimately transduction. Importantly, the transduction-enhancing PEGylated HSA derivative evaded recognition by HSA-specific antibodies and macrophage activation. Our findings hold great promise for facilitating improved retroviral gene transfer. PMID:27239020

  8. HGTree: database of horizontally transferred genes determined by tree reconciliation

    PubMed Central

    Jeong, Hyeonsoo; Sung, Samsun; Kwon, Taehyung; Seo, Minseok; Caetano-Anollés, Kelsey; Choi, Sang Ho; Cho, Seoae; Nasir, Arshan; Kim, Heebal

    2016-01-01

    The HGTree database provides putative genome-wide horizontal gene transfer (HGT) information for 2472 completely sequenced prokaryotic genomes. This task is accomplished by reconstructing approximate maximum likelihood phylogenetic trees for each orthologous gene and corresponding 16S rRNA reference species sets and then reconciling the two trees under parsimony framework. The tree reconciliation method is generally considered to be a reliable way to detect HGT events but its practical use has remained limited because the method is computationally intensive and conceptually challenging. In this regard, HGTree (http://hgtree.snu.ac.kr) represents a useful addition to the biological community and enables quick and easy retrieval of information for HGT-acquired genes to better understand microbial taxonomy and evolution. The database is freely available and can be easily scaled and updated to keep pace with the rapid rise in genomic information. PMID:26578597

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

    PubMed

    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. PMID:23912835

  10. Indications for Acquisition of Reductive Dehalogenase Genes through Horizontal Gene Transfer by Dehalococcoides ethenogenes Strain 195

    PubMed Central

    Regeard, Christophe; Maillard, Julien; Dufraigne, Christine; Deschavanne, Patrick; Holliger, Christof

    2005-01-01

    The genome of Dehalococcoides ethenogenes strain 195, an anaerobic dehalorespiring bacterium, contains 18 copies of putative reductive dehalogenase genes, including the well-characterized tceA gene, whose gene product functions as the key enzyme in the environmentally important dehalorespiration process. The genome of D. ethenogenes was analyzed using a bioinformatic tool based on the frequency of oligonucleotides. The results in the form of a genomic signature revealed several local disruptions of the host signature along the genome sequence. These fractures represent DNA segments of potentially foreign origin, so-called atypical regions, which may have been acquired by an ancestor through horizontal gene transfer. Most interestingly, 15 of the 18 reductive dehalogenase genes, including the tceA gene, were found to be located in these regions, strongly indicating the foreign nature of the dehalorespiration activity. The GC content and the presence of recombinase genes within some of these regions corroborate this hypothesis. A hierarchical classification of the atypical regions containing the reductive dehalogenase genes indicated that these regions were probably acquired by several gene transfer events. PMID:15932990

  11. Bacterial gene transfer by natural genetic transformation in the environment.

    PubMed Central

    Lorenz, M G; Wackernagel, W

    1994-01-01

    Natural genetic transformation is the active uptake of free DNA by bacterial cells and the heritable incorporation of its genetic information. Since the famous discovery of transformation in Streptococcus pneumoniae by Griffith in 1928 and the demonstration of DNA as the transforming principle by Avery and coworkers in 1944, cellular processes involved in transformation have been studied extensively by in vitro experimentation with a few transformable species. Only more recently has it been considered that transformation may be a powerful mechanism of horizontal gene transfer in natural bacterial populations. In this review the current understanding of the biology of transformation is summarized to provide the platform on which aspects of bacterial transformation in water, soil, and sediments and the habitat of pathogens are discussed. Direct and indirect evidence for gene transfer routes by transformation within species and between different species will be presented, along with data suggesting that plasmids as well as chromosomal DNA are subject to genetic exchange via transformation. Experiments exploring the prerequisites for transformation in the environment, including the production and persistence of free DNA and factors important for the uptake of DNA by cells, will be compiled, as well as possible natural barriers to transformation. The efficiency of gene transfer by transformation in bacterial habitats is possibly genetically adjusted to submaximal levels. The fact that natural transformation has been detected among bacteria from all trophic and taxonomic groups including archaebacteria suggests that transformability evolved early in phylogeny. Probable functions of DNA uptake other than gene acquisition will be discussed. The body of information presently available suggests that transformation has a great impact on bacterial population dynamics as well as on bacterial evolution and speciation. PMID:7968924

  12. Scapholunate stabilization with dynamic extensor carpi radialis longus tendon transfer.

    PubMed

    Peterson, Steven L; Freeland, Alan E

    2010-12-01

    Dynamic extensor carpi radialis longus tendon transfer to the distal pole of the scaphoid acts synchronously and synergistically with wrist motion to restore the slider crank mechanism of the scaphoid after scapholunate interosseous ligament (SLIL) injury. The procedure is designed to simulate a hypothetical dorsal radioscaphoid ligament that more closely approximates the normal viscoelastic forces acting on the scaphoid throughout all phases of wrist motion than does the static checkrein effect and motion limitations of capsulodesis or tenodesis. Extensor carpi radialis longus transfer may be independently sufficient to support normal or near-normal scapholunate and midcarpal kinematics and prevent further injury propagation in patients with partial SLIL tears and dynamic scapholunate instability. Extensor carpi radialis longus transfer alone may improve carpal congruity in patients with static scapholunate instability, but SLIL and dorsal lunate ligament repair or reconstruction is essential for favorable durable outcomes. Extensor carpi radialis longus transfer offers a simple and reasonable alternative to capsulodesis or tenodesis to support these ligament repairs or reconstructions, does not require intercarpal fixation, and allows rehabilitation to proceed expeditiously at approximately 1 month after surgery. PMID:21134618

  13. In vivo Cytokine Gene Transfer by Gene Gun Reduces Tumor Growth in Mice

    NASA Astrophysics Data System (ADS)

    Sun, Wenn H.; Burkholder, Joseph K.; Sun, Jian; Culp, Jerilyn; Turner, Joel; Lu, Xing G.; Pugh, Thomas D.; Ershler, William B.; Yang, Ning-Sun

    1995-03-01

    Implantation of tumor cells modified by in vitro cytokine gene transfer has been shown by many investigators to result in potent in vivo antitumor activities in mice. Here we describe an approach to tumor immunotherapy utilizing direct transfection of cytokine genes into tumorbearing animals by particle-mediated gene transfer. In vivo transfection of the human interleukin 6 gene into the tumor site reduced methylcholanthrene-induced fibrosarcoma growth, and a combination of murine tumor necrosis factor α and interferon γ genes inhibited growth of a renal carcinoma tumor model (Renca). In addition, treatment with murine interleukin 2 and interferon γ genes prolonged the survival of Renca tumor-bearing mice and resulted in tumor eradication in 25% of the test animals. Transgene expression was demonstrated in treated tissues by ELISA and immunohistochemical analysis. Significant serum levels of interleukin 6 and interferon γ were detected, demonstrating effective secretion of transgenic proteins from treated skin into the bloodstream. This in vivo cytokine gene therapy approach provides a system for evaluating the antitumor properties of various cytokines in different tumor models and has potential utility for human cancer gene therapy.

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

    PubMed

    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

    2015-10-01

    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. PMID:26412136

  15. Interaction between Conjugative and Retrotransposable Elements in Horizontal Gene Transfer

    PubMed Central

    Novikova, Olga; Smith, Dorie; Hahn, Ingrid; Beauregard, Arthur; Belfort, Marlene

    2014-01-01

    Mobile genetic elements either encode their own mobilization machineries or hijack them from other mobile elements. Multiple classes of mobile elements often coexist within genomes and it is unclear whether they have the capacity to functionally interact and even collaborate. We investigate the possibility that molecular machineries of disparate mobile elements may functionally interact, using the example of a retrotransposon, in the form of a mobile group II intron, found on a conjugative plasmid pRS01 in Lactococcus lactis. This intron resides within the pRS01 ltrB gene encoding relaxase, the enzyme required for nicking the transfer origin (oriT) for conjugal transmission of the plasmid into a recipient cell. Here, we show that relaxase stimulates both the frequency and diversity of retrotransposition events using a retromobility indicator gene (RIG), and by developing a high-throughput genomic retrotransposition detection system called RIG-Seq. We demonstrate that LtrB relaxase not only nicks ssDNA of its cognate oriT in a sequence- and strand-specific manner, but also possesses weak off-target activity. Together, the data support a model in which the two different mobile elements, one using an RNA-based mechanism, the other using DNA-based transfer, do functionally interact. Intron splicing facilitates relaxase expression required for conjugation, whereas relaxase introduces spurious nicks in recipient DNA that stimulate both the frequency of intron mobility and the density of events. We hypothesize that this functional interaction between the mobile elements would promote horizontal conjugal gene transfer while stimulating intron dissemination in the donor and recipient cells. PMID:25474706

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Site-Specific Gene Expression in Vivo by Direct Gene Transfer into the Arterial Wall

    NASA Astrophysics Data System (ADS)

    Nabel, Elizabeth G.; Plautz, Gregory; Nabel, Gary J.

    1990-09-01

    A recombinant β-galactosidase gene has been expressed in a specific arterial segment in vivo by direct infection with a murine amphotropic retroviral vector or by DNA transfection with the use of liposomes. Several cell types in the vessel wall were transduced, including endothelial and vascular smooth muscle cells. After retroviral infection, a recombinant reporter gene was expressed for at least 5 months, and no helper virus was detected. Recombinant gene expression achieved by direct retroviral infection or liposome-mediated DNA transfection was limited to the site of infection and was absent from liver, lung, kidney, and spleen. These results demonstrate that site-specific gene expression can be achieved by direct gene transfer in vivo and could be applied to the treatment of such human diseases as atherosclerosis or cancer.

  18. Laterally Transferred Gene Recruited as a Venom in Parasitoid Wasps.

    PubMed

    Martinson, Ellen O; Martinson, Vincent G; Edwards, Rachel; Mrinalini; Werren, John H

    2016-04-01

    Parasitoid wasps use venom to manipulate the immunity and metabolism of their host insects in a variety of ways to provide resources for their offspring. Yet, how genes are recruited and evolve to perform venom functions remain open questions. A recently recognized source of eukaryotic genome innovation is lateral gene transfer (LGT). Glycoside hydrolase family 19 (GH19) chitinases are widespread in bacteria, microsporidia, and plants where they are used in nutrient acquisition or defense, but have previously not been known in metazoans. In this study, a GH19 chitinase LGT is described from the unicellular microsporidia/Rozella clade into parasitoid wasps of the superfamily Chalcidoidea, where it has become recruited as a venom protein. The GH19 chitinase is present in 15 species of chalcidoid wasps representing four families, and phylogenetic analysis indicates that it was laterally transferred near or before the origin of Chalcidoidea (∼95 Ma). The GH19 chitinase gene is highly expressed in the venom gland of at least seven species, indicating a role in the complex host manipulations performed by parasitoid wasp venom. RNAi knockdown in the model parasitoid Nasonia vitripennis reveals that-following envenomation-the GH19 chitinase induces fly hosts to upregulate genes involved in an immune response to fungi. A second, independent LGT of GH19 chitinase from microsporidia into mosquitoes was also found, also supported by phylogenetic reconstructions. Besides these two LGT events, GH19 chitinase is not found in any other sequenced animal genome, or in any fungi outside the microsporidia/Rozella clade. PMID:26715630

  19. CXCR4 gene transfer prevents pressure overload induced heart failure

    PubMed Central

    LaRocca, Thomas J.; Jeong, Dongtak; Kohlbrenner, Erik; Lee, Ahyoung; Chen, JiQiu; Hajjar, Roger J.; Tarzami, Sima T.

    2012-01-01

    Stem cell and gene therapies are being pursued as strategies for repairing damaged cardiac tissue following myocardial infarction in an attempt to prevent heart failure. The chemokine receptor-4 (CXCR4) and its ligand, CXCL12, play a critical role in stem cell recruitment post-acute myocardial infarction. Whereas progenitor cell migration via the CXCL12/CXCR4 axis is well characterized, little is known about the molecular mechanisms of CXCR4 mediated modulation of cardiac hypertrophy and failure. We used gene therapy to test the effects of CXCR4 gene delivery on adverse ventricular remodeling due to pressure overload. We assessed the effect of cardiac overexpression of CXCR4 during trans-aortic constriction (TAC) using a cardiotropic adeno-associated viral vector (AAV9) carrying the CXCR4 gene. Cardiac overexpression of CXCR4 in mice with pressure overload prevented ventricular remodeling, preserved capillary density and maintained function as determined by echocardiography and in vivo hemodynamics. In isolated adult rat cardiac myocytes, CXCL12 treatment prevented isoproterenol induced hypertrophy and interrupted the calcineurin/NFAT pathway. Finally, a complex involving the L-type calcium channel, β2-adenoreceptor, and CXCR4 (Cav1.2/β2AR/CXCR4) was identified in healthy cardiac myocytes and was shown to dissociate as a consequence of heart failure. CXCR4 administered to the heart via gene transfer prevents pressure overload induced heart failure. The identification of CXCR4 participation in a Cav1.2-β2AR regulatory complex provides further insight into the mechanism by which CXCR4 modulates calcium homeostasis and chronic pressure overload responses in the cardiac myocyte. Together these results suggest AAV9.CXCR4 gene therapy is a potential therapeutic approach for congestive heart failure. PMID:22668785

  20. Thiolate versus Selenolate: Structure, Stability, and Charge Transfer Properties.

    PubMed

    Ossowski, Jakub; Wächter, Tobias; Silies, Laura; Kind, Martin; Noworolska, Agnieszka; Blobner, Florian; Gnatek, Dominika; Rysz, Jakub; Bolte, Michael; Feulner, Peter; Terfort, Andreas; Cyganik, Piotr; Zharnikov, Michael

    2015-04-28

    Selenolate is considered as an alternative to thiolate to serve as a headgroup mediating the formation of self-assembled monolayers (SAMs) on coinage metal substrates. There are, however, ongoing vivid discussions regarding the advantages and disadvantages of these anchor groups, regarding, in particular, the energetics of the headgroup-substrate interface and their efficiency in terms of charge transport/transfer. Here we introduce a well-defined model system of 6-cyanonaphthalene-2-thiolate and -selenolate SAMs on Au(111) to resolve these controversies. The exact structural arrangements in both types of SAMs are somewhat different, suggesting a better SAM-building ability in the case of selenolates. At the same time, both types of SAMs have similar packing densities and molecular orientations. This permitted reliable competitive exchange and ion-beam-induced desorption experiments which provided unequivocal evidence for a stronger bonding of selenolates to the substrate as compared to the thiolates. Regardless of this difference, the dynamic charge transfer properties of the thiolate- and selenolate-based adsorbates were found to be nearly identical, as determined by the core-hole-clock approach, which is explained by a redistribution of electron density along the molecular framework, compensating the difference in the substrate-headgroup bond strength. PMID:25857927

  1. Resistance Gene Transfer during Treatments for Experimental Avian Colibacillosis

    PubMed Central

    Dheilly, Alexandra; Le Devendec, Laëtitia; Mourand, Gwenaëlle; Bouder, Axelle; Jouy, Eric

    2012-01-01

    An experiment was conducted in animal facilities to compare the impacts of four avian colibacillosis treatments—oxytetracycline (OTC), trimethoprim-sulfadimethoxine (SXT), amoxicillin (AMX), or enrofloxacin (ENR)—on the susceptibility of Escherichia coli in broiler intestinal tracts. Birds were first orally inoculated with rifampin-resistant E. coli strains bearing plasmid genes conferring resistance to fluoroquinolones (qnr), cephalosporins (blaCTX-M or blaFOX), trimethoprim-sulfonamides, aminoglycosides, or tetracyclines. Feces samples were collected before, during, and after antimicrobial treatments. The susceptibilities of E. coli strains were studied, and resistance gene transfer was analyzed. An increase in the tetracycline-resistant E. coli population was observed only in OTC-treated birds, whereas multiresistant E. coli was detected in the dominant E. coli populations of SXT-, AMX-, or ENR-treated birds. Most multiresistant E. coli strains were susceptible to rifampin and exhibited various pulsed-field gel electrophoresis profiles, suggesting the transfer of one of the multiresistance plasmids from the inoculated strains to other E. coli strains in the intestinal tract. In conclusion, this study clearly illustrates how, in E. coli, “old” antimicrobials may coselect antimicrobial resistance to recent and critical molecules. PMID:21986830

  2. Lateral gene transfers have polished animal genomes: lessons from nematodes

    PubMed Central

    Danchin, Etienne G. J.; Rosso, Marie-Noëlle

    2012-01-01

    It is now accepted that lateral gene transfers (LGT), have significantly contributed to the composition of bacterial genomes. The amplitude of the phenomenon is considered so high in prokaryotes that it challenges the traditional view of a binary hierarchical tree of life to correctly represent the evolutionary history of species. Given the plethora of transfers between prokaryotes, it is currently impossible to infer the last common ancestral gene set for any extant species. For this ensemble of reasons, it has been proposed that the Darwinian binary tree of life may be inappropriate to correctly reflect the actual relations between species, at least in prokaryotes. In contrast, the contribution of LGT to the composition of animal genomes is less documented. In the light of recent analyses that reported series of LGT events in nematodes, we discuss the importance of this phenomenon in the evolutionary history and in the current composition of an animal genome. Far from being neutral, it appears that besides having contributed to nematode genome contents, LGT have favored the emergence of important traits such as plant-parasitism. PMID:22919619

  3. Synthetic Fatty Acids Prevent Plasmid-Mediated Horizontal Gene Transfer

    PubMed Central

    Getino, María; Sanabria-Ríos, David J.; Fernández-López, Raúl; Campos-Gómez, Javier; Sánchez-López, José M.; Fernández, Antonio; Carballeira, Néstor M.

    2015-01-01

    ABSTRACT Bacterial conjugation constitutes a major horizontal gene transfer mechanism for the dissemination of antibiotic resistance genes among human pathogens. Antibiotic resistance spread could be halted or diminished by molecules that interfere with the conjugation process. In this work, synthetic 2-alkynoic fatty acids were identified as a novel class of conjugation inhibitors. Their chemical properties were investigated by using the prototype 2-hexadecynoic acid and its derivatives. Essential features of effective inhibitors were the carboxylic group, an optimal long aliphatic chain of 16 carbon atoms, and one unsaturation. Chemical modification of these groups led to inactive or less-active derivatives. Conjugation inhibitors were found to act on the donor cell, affecting a wide number of pathogenic bacterial hosts, including Escherichia, Salmonella, Pseudomonas, and Acinetobacter spp. Conjugation inhibitors were active in inhibiting transfer of IncF, IncW, and IncH plasmids, moderately active against IncI, IncL/M, and IncX plasmids, and inactive against IncP and IncN plasmids. Importantly, the use of 2-hexadecynoic acid avoided the spread of a derepressed IncF plasmid into a recipient population, demonstrating the feasibility of abolishing the dissemination of antimicrobial resistances by blocking bacterial conjugation. PMID:26330514

  4. Stability analysis of electrical powered wheelchair-mounted robotic-assisted transfer device.

    PubMed

    Wang, Hongwu; Tsai, Chung-Ying; Jeannis, Hervens; Chung, Cheng-Shiu; Kelleher, Annmarie; Grindle, Garrett G; Cooper, Rory A

    2014-01-01

    The ability of people with disabilities to live in their homes and communities with maximal independence often hinges, at least in part, on their ability to transfer or be transferred by an assistant. Because of limited resources and the expense of personal care, robotic transfer assistance devices will likely be in great demand. An easy-to-use system for assisting with transfers, attachable to electrical powered wheelchairs (EPWs) and readily transportable, could have a significant positive effect on the quality of life of people with disabilities. We investigated the stability of our newly developed Strong Arm, which is attached and integrated with an EPW to assist with transfers. The stability of the system was analyzed and verified by experiments applying different loads and using different system configurations. The model predicted the distributions of the system's center of mass very well compared with the experimental results. When real transfers were conducted with 50 and 75 kg loads and an 83.25 kg dummy, the current Strong Arm could transfer all weights safely without tip-over. Our modeling accurately predicts the stability of the system and is suitable for developing better control algorithms to enhance the safety of the device. PMID:25356515

  5. Stability Analysis of Absorption Chiller-Heaters by Applying Transfer Function

    NASA Astrophysics Data System (ADS)

    Fujii, Tatsuo; Miyake, Satoshi; Oka, Masahiro; Mori, Kiyoyuki

    A transfer function approach is found to be a practical method for ensuring stable operation of absorption chiller-heaters. The transfer function model is based on a solution-circuit of the machine, which dominates the stability of the operation. This model includes a solution pump, a generator with an overflow weir, and a float valve. We found that the solution-circuit system is designed with the cascade control, which makes the system stable. In this construction, the float valve actuates a primary control loop, and the overflow weir actuates a secondary loop. The effects of the characteristic of the solution pump and the overflow weir are estimated by the degree of the stabilities, which are the gain margin and the phase margin. We found that the characteristic of the solution pump strongly effects the stability by enhancing the effect of the cascade control and improving the stability. So it is essential for a better stability analysis model. According to these results, the established model is useful for quantitatively predicting the stabilities of a chiller-heater in operation, and simultaneously reducing its size and improving the stability of operation. We conclude that the methodology based on transfer function can provide compact and reliable absorption chiller-heaters.

  6. Amoebozoa possess lineage-specific globin gene repertoires gained by individual horizontal gene transfers.

    PubMed

    Dröge, Jasmin; Buczek, Dorota; Suzuki, Yutaka; Makałowski, Wojciech

    2014-01-01

    The Amoebozoa represent a clade of unicellular amoeboid organisms that display a wide variety of lifestyles, including free-living and parasitic species. For example, the social amoeba Dictyostelium discoideum has the ability to aggregate into a multicellular fruiting body upon starvation, while the pathogenic amoeba Entamoeba histolytica is a parasite of humans. Globins are small heme proteins that are present in almost all extant organisms. Although several genomes of amoebozoan species have been sequenced, little is known about the phyletic distribution of globin genes within this phylum. Only two flavohemoglobins (FHbs) of D. discoideum have been reported and characterized previously while the genomes of Entamoeba species are apparently devoid of globin genes. We investigated eleven amoebozoan species for the presence of globin genes by genomic and phylogenetic in silico analyses. Additional FHb genes were identified in the genomes of four social amoebas and the true slime mold Physarum polycephalum. Moreover, a single-domain globin (SDFgb) of Hartmannella vermiformis, as well as two truncated hemoglobins (trHbs) of Acanthamoeba castellanii were identified. Phylogenetic evidence suggests that these globin genes were independently acquired via horizontal gene transfer from some ancestral bacteria. Furthermore, the phylogenetic tree of amoebozoan FHbs indicates that they do not share a common ancestry and that a transfer of FHbs from bacteria to amoeba occurred multiple times. PMID:25013378

  7. Genome-wide experimental determination of barriers to horizontal gene transfer.

    PubMed

    Sorek, Rotem; Zhu, Yiwen; Creevey, Christopher J; Francino, M Pilar; Bork, Peer; Rubin, Edward M

    2007-11-30

    Horizontal gene transfer, in which genetic material is transferred from the genome of one organism to that of another, has been investigated in microbial species mainly through computational sequence analyses. To address the lack of experimental data, we studied the attempted movement of 246,045 genes from 79 prokaryotic genomes into Escherichia coli and identified genes that consistently fail to transfer. We studied the mechanisms underlying transfer inhibition by placing coding regions from different species under the control of inducible promoters. Our data suggest that toxicity to the host inhibited transfer regardless of the species of origin and that increased gene dosage and associated increased expression may be a predominant cause for transfer failure. Although these experimental studies examined transfer solely into E. coli, a computational analysis of gene-transfer rates across available bacterial and archaeal genomes supports that the barriers observed in our study are general across the tree of life. PMID:17947550

  8. Genome-wide experimental determination of barriers to horizontal gene transfer

    SciTech Connect

    Rubin, Edward; Sorek, Rotem; Zhu, Yiwen; Creevey, Christopher J.; Francino, M. Pilar; Bork, Peer; Rubin, Edward M.

    2007-09-24

    Horizontal gene transfer, in which genetic material is transferred from the genome of one organism to another, has been investigated in microbial species mainly through computational sequence analyses. To address the lack of experimental data, we studied the attempted movement of 246,045 genes from 79 prokaryotic genomes into E. coli and identified genes that consistently fail to transfer. We studied the mechanisms underlying transfer inhibition by placing coding regions from different species under the control of inducible promoters. Their toxicity to the host inhibited transfer regardless of the species of origin and our data suggest that increased gene dosage and associated increased expression is a predominant cause for transfer failure. While these experimental studies examined transfer solely into E. coli, a computational analysis of gene transfer rates across available bacterial and archaeal genomes indicates that the barriers observed in our study are general across the tree of life.

  9. Repeated, recent and diverse transfers of a mitochondrial gene to the nucleus in flowering plants.

    PubMed

    Adams, K L; Daley, D O; Qiu, Y L; Whelan, J; Palmer, J D

    2000-11-16

    A central component of the endosymbiotic theory for the bacterial origin of the mitochondrion is that many of its genes were transferred to the nucleus. Most of this transfer occurred early in mitochondrial evolution; functional transfer of mitochondrial genes has ceased in animals. Although mitochondrial gene transfer continues to occur in plants, no comprehensive study of the frequency and timing of transfers during plant evolution has been conducted. Here we report frequent loss (26 times) and transfer to the nucleus of the mitochondrial gene rps10 among 277 diverse angiosperms. Characterization of nuclear rps10 genes from 16 out of 26 loss lineages implies that many independent, RNA-mediated rps10 transfers occurred during recent angiosperm evolution; each of the genes may represent a separate functional gene transfer. Thus, rps10 has been transferred to the nucleus at a surprisingly high rate during angiosperm evolution. The structures of several nuclear rps10 genes reveal diverse mechanisms by which transferred genes become activated, including parasitism of pre-existing nuclear genes for mitochondrial or cytoplasmic proteins, and activation without gain of a mitochondrial targeting sequence. PMID:11099041

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

    PubMed Central

    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

    2015-01-01

    Summary 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. PMID:26412136

  11. High-bandwidth transfer of phase stability through a fiber frequency comb.

    PubMed

    Scharnhorst, Nils; Wübbena, Jannes B; Hannig, Stephan; Jakobsen, Kornelius; Kramer, Johannes; Leroux, Ian D; Schmidt, Piet O

    2015-07-27

    We demonstrate phase locking of a 729 nm diode laser to a 1542 nm master laser via an erbium-doped-fiber frequency comb, using a transfer-oscillator feedforward scheme which suppresses the effect of comb noise in an unprecedented 1.8 MHz bandwidth. We illustrate its performance by carrying out coherent manipulations of a trapped calcium ion with 99 % fidelity even at few-μs timescales. We thus demonstrate that transfer-oscillator locking can provide sufficient phase stability for high-fidelity quantum logic manipulation even without pre-stabilization of the slave diode laser. PMID:26367634

  12. Extensive Intra-Kingdom Horizontal Gene Transfer Converging on a Fungal Fructose Transporter Gene

    PubMed Central

    Coelho, Marco A.; Gonçalves, Carla; Sampaio, José Paulo; Gonçalves, Paula

    2013-01-01

    Comparative genomics revealed in the last decade a scenario of rampant horizontal gene transfer (HGT) among prokaryotes, but for fungi a clearly dominant pattern of vertical inheritance still stands, punctuated however by an increasing number of exceptions. In the present work, we studied the phylogenetic distribution and pattern of inheritance of a fungal gene encoding a fructose transporter (FSY1) with unique substrate selectivity. 109 FSY1 homologues were identified in two sub-phyla of the Ascomycota, in a survey that included 241 available fungal genomes. At least 10 independent inter-species instances of horizontal gene transfer (HGT) involving FSY1 were identified, supported by strong phylogenetic evidence and synteny analyses. The acquisition of FSY1 through HGT was sometimes suggestive of xenolog gene displacement, but several cases of pseudoparalogy were also uncovered. Moreover, evidence was found for successive HGT events, possibly including those responsible for transmission of the gene among yeast lineages. These occurrences do not seem to be driven by functional diversification of the Fsy1 proteins because Fsy1 homologues from widely distant lineages, including at least one acquired by HGT, appear to have similar biochemical properties. In summary, retracing the evolutionary path of the FSY1 gene brought to light an unparalleled number of independent HGT events involving a single fungal gene. We propose that the turbulent evolutionary history of the gene may be linked to the unique biochemical properties of the encoded transporter, whose predictable effect on fitness may be highly variable. In general, our results support the most recent views suggesting that inter-species HGT may have contributed much more substantially to shape fungal genomes than heretofore assumed. PMID:23818872

  13. Gene stability in mammalian cells and protein consistency.

    PubMed

    Berthold, W

    1994-01-01

    The safety of a patient who is the recipient of protein drugs has to be assured. A "wrong" protein is thought to represent a great risk. The philosophy of testing strategies related to gene stability with product safety will be discussed in the light of experimental data available today. Although all mammalian cell lines used in the production of biologicals including recombinant DNA-derived lines have been produced from individual clones (functional monoclonality) they have been found to be heterogenous with regard to the genomic content (number of chromosomes, characteristics of identifiable chromosomes and position and number of integrated recombinant sequences). The verification of the presence of correct gene in a production cell line constitutes a well accepted and useful test, especially if derived by "population sequencing". A batch not related repeated confirmation of this fact cannot lead to any additional assurance for the correctness of all proteins constituting a given product beyond the level provided by cheminal testing. In contrast to this obvious and unavoidable heterogeneity in cellular genomes, the coding regions of genes have not been shown to change. Evidence is available to demonstrate the consistency of protein products originating from recombinant (and hybridoma) cell lines, e.g. more than 500,000 patients have received and tolerated rtPA well. PMID:7883100

  14. Applying horizontal gene transfer phenomena to enhance non-viral gene therapy

    PubMed Central

    Elmer, Jacob J.; Christensen, Matthew D.; Rege, Kaushal

    2014-01-01

    Horizontal gene transfer (HGT) is widespread amongst prokaryotes, but eukaryotes tend to be far less promiscuous with their genetic information. However, several examples of HGT from pathogens into eukaryotic cells have been discovered and mimicked to improve non-viral gene delivery techniques. For example, several viral proteins and DNA sequences have been used to significantly increase cytoplasmic and nuclear gene delivery. Plant genetic engineering is routinely performed with the pathogenic bacterium Agrobacterium tumefaciens and similar pathogens (e.g. Bartonella henselae) may also be able to transform human cells. Intracellular parasites like Trypanosoma cruzi may also provide new insights into overcoming cellular barriers to gene delivery. Finally, intercellular nucleic acid transfer between host cells will also be briefly discussed. This article will review the unique characteristics of several different viruses and microbes and discuss how their traits have been successfully applied to improve non-viral gene delivery techniques. Consequently, pathogenic traits that originally caused diseases may eventually be used to treat many genetic diseases. PMID:23994344

  15. Comparison between Agrobacterium-mediated and direct gene transfer using the gene gun.

    PubMed

    Gao, Caixia; Nielsen, Klaus K

    2013-01-01

    Agrobacterium-mediated transformation and direct gene transfer using the gene gun (microparticle -bombardment) are the two most widely used methods for plant genetic modification. The Agrobacterium method has been successfully practiced in dicots for many years, but only recently have efficient protocols been developed for grasses. Microparticle bombardment has evolved as a method delivering exogenous nucleic acids into plant genome and is a commonly employed technique in plant science. Here these two systems are compared for transformation efficiency, transgene integration, and transgene expression when used to transform tall fescue (Festuca arundinacea Schreb.). The tall fescue transformation protocols lead to the production of large numbers of fertile, independent transgenic lines. PMID:23104329

  16. Phase transfer of oleic acid stabilized rod-shaped anatase TiO2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Wilkerson, Rachel J.; Elder, Theresa; Sowinksi, Olivia; Fostvedt, Jade I.; Hoefelmeyer, James D.

    2016-06-01

    Three methods were evaluated for phase transfer of oleic acid stabilized TiO2 nanorods from non-polar phase to an aqueous phase. Three alkyltrimethylammonium bromide (C6, C8, C12) surfactants were tested and compared with an amphiphilic polymer as interdigitation agents. Ligand substitutions with catechol derivatives with polar functional groups para to the -enediol were evaluated as well. The molecular surfactants were ineffective compared to the amphiphilic polymer in the interdigitation phase transfer approach. Ligand substitution with catechols proceeded efficiently with phase transfer. The ligand substitution reactions were accompanied by gas evolution, which was found to result from decarboxylation of oleic acid in alkaline aqueous conditions.

  17. Multiple Inter-Kingdom Horizontal Gene Transfers in the Evolution of the Phosphoenolpyruvate Carboxylase Gene Family

    PubMed Central

    Wang, Wen; Su, Bing

    2012-01-01

    Pepcase is a gene encoding phosphoenolpyruvate carboxylase that exists in bacteria, archaea and plants,playing an important role in plant metabolism and development. Most plants have two or more pepcase genes belonging to two gene sub-families, while only one gene exists in other organisms. Previous research categorized one plant pepcase gene as plant-type pepcase (PTPC) while the other as bacteria-type pepcase (BTPC) because of its similarity with the pepcase gene found in bacteria. Phylogenetic reconstruction showed that PTPC is the ancestral lineage of plant pepcase, and that all bacteria, protistpepcase and BTPC in plants are derived from a lineage of pepcase closely related with PTPC in algae. However, their phylogeny contradicts the species tree and traditional chronology of organism evolution. Because the diversification of bacteria occurred much earlier than the origin of plants, presumably all bacterialpepcase derived from the ancestral PTPC of algal plants after divergingfrom the ancestor of vascular plant PTPC. To solve this contradiction, we reconstructed the phylogeny of pepcase gene family. Our result showed that both PTPC and BTPC are derived from an ancestral lineage of gamma-proteobacteriapepcases, possibly via an ancient inter-kingdom horizontal gene transfer (HGT) from bacteria to the eukaryotic common ancestor of plants, protists and cellular slime mold. Our phylogenetic analysis also found 48other pepcase genes originated from inter-kingdom HGTs. These results imply that inter-kingdom HGTs played important roles in the evolution of the pepcase gene family and furthermore that HGTsare a more frequent evolutionary event than previouslythought. PMID:23251445

  18. Multiple inter-kingdom horizontal gene transfers in the evolution of the phosphoenolpyruvate carboxylase gene family.

    PubMed

    Peng, Yingmei; Cai, Jing; Wang, Wen; Su, Bing

    2012-01-01

    Pepcase is a gene encoding phosphoenolpyruvate carboxylase that exists in bacteria, archaea and plants,playing an important role in plant metabolism and development. Most plants have two or more pepcase genes belonging to two gene sub-families, while only one gene exists in other organisms. Previous research categorized one plant pepcase gene as plant-type pepcase (PTPC) while the other as bacteria-type pepcase (BTPC) because of its similarity with the pepcase gene found in bacteria. Phylogenetic reconstruction showed that PTPC is the ancestral lineage of plant pepcase, and that all bacteria, protistpepcase and BTPC in plants are derived from a lineage of pepcase closely related with PTPC in algae. However, their phylogeny contradicts the species tree and traditional chronology of organism evolution. Because the diversification of bacteria occurred much earlier than the origin of plants, presumably all bacterialpepcase derived from the ancestral PTPC of algal plants after divergingfrom the ancestor of vascular plant PTPC. To solve this contradiction, we reconstructed the phylogeny of pepcase gene family. Our result showed that both PTPC and BTPC are derived from an ancestral lineage of gamma-proteobacteriapepcases, possibly via an ancient inter-kingdom horizontal gene transfer (HGT) from bacteria to the eukaryotic common ancestor of plants, protists and cellular slime mold. Our phylogenetic analysis also found 48other pepcase genes originated from inter-kingdom HGTs. These results imply that inter-kingdom HGTs played important roles in the evolution of the pepcase gene family and furthermore that HGTsare a more frequent evolutionary event than previouslythought. PMID:23251445

  19. Improved gene transfer with histidine-functionalized mesoporous silica nanoparticles.

    PubMed

    Brevet, David; Hocine, Ouahiba; Delalande, Anthony; Raehm, Laurence; Charnay, Clarence; Midoux, Patrick; Durand, Jean-Olivier; Pichon, Chantal

    2014-08-25

    Mesoporous silica nanoparticles (MSN) were functionalized with aminopropyltriethoxysilane (MSN-NH2) then L-histidine (MSN-His) for pDNA delivery in cells and in vivo. The complexation of pDNA with MSN-NH2 and MSN-His was first studied with gel shift assay. pDNA complexed with MSN-His was better protected from DNase degradation than with MSN-NH2. An improvement of the transfection efficiency in cells was observed with MSN-His/pDNA compared to MSN-NH2/pDNA, which could be explained by a better internalization of MSN-His. The improvement of the transfection efficiency with MSN-His was also observed for gene transfer in Achilles tendons in vivo. PMID:24853464

  20. Statistical Mechanics of Horizontal Gene Transfer in Evolutionary Ecology

    NASA Astrophysics Data System (ADS)

    Chia, Nicholas; Goldenfeld, Nigel

    2011-04-01

    The biological world, especially its majority microbial component, is strongly interacting and may be dominated by collective effects. In this review, we provide a brief introduction for statistical physicists of the way in which living cells communicate genetically through transferred genes, as well as the ways in which they can reorganize their genomes in response to environmental pressure. We discuss how genome evolution can be thought of as related to the physical phenomenon of annealing, and describe the sense in which genomes can be said to exhibit an analogue of information entropy. As a direct application of these ideas, we analyze the variation with ocean depth of transposons in marine microbial genomes, predicting trends that are consistent with recent observations using metagenomic surveys.

  1. Stability-driven nonnegative matrix factorization to interpret spatial gene expression and build local gene networks.

    PubMed

    Wu, Siqi; Joseph, Antony; Hammonds, Ann S; Celniker, Susan E; Yu, Bin; Frise, Erwin

    2016-04-19

    Spatial gene expression patterns enable the detection of local covariability and are extremely useful for identifying local gene interactions during normal development. The abundance of spatial expression data in recent years has led to the modeling and analysis of regulatory networks. The inherent complexity of such data makes it a challenge to extract biological information. We developed staNMF, a method that combines a scalable implementation of nonnegative matrix factorization (NMF) with a new stability-driven model selection criterion. When applied to a set ofDrosophilaearly embryonic spatial gene expression images, one of the largest datasets of its kind, staNMF identified 21 principal patterns (PP). Providing a compact yet biologically interpretable representation ofDrosophilaexpression patterns, PP are comparable to a fate map generated experimentally by laser ablation and show exceptional promise as a data-driven alternative to manual annotations. Our analysis mapped genes to cell-fate programs and assigned putative biological roles to uncharacterized genes. Finally, we used the PP to generate local transcription factor regulatory networks. Spatially local correlation networks were constructed for six PP that span along the embryonic anterior-posterior axis. Using a two-tail 5% cutoff on correlation, we reproduced 10 of the 11 links in the well-studied gap gene network. The performance of PP with theDrosophiladata suggests that staNMF provides informative decompositions and constitutes a useful computational lens through which to extract biological insight from complex and often noisy gene expression data. PMID:27071099

  2. Detecting rare gene transfer events in bacterial populations.

    PubMed

    Nielsen, Kaare M; Bøhn, Thomas; Townsend, Jeffrey P

    2014-01-01

    Horizontal gene transfer (HGT) enables bacteria to access, share, and recombine genetic variation, resulting in genetic diversity that cannot be obtained through mutational processes alone. In most cases, the observation of evolutionary successful HGT events relies on the outcome of initially rare events that lead to novel functions in the new host, and that exhibit a positive effect on host fitness. Conversely, the large majority of HGT events occurring in bacterial populations will go undetected due to lack of replication success of transformants. Moreover, other HGT events that would be highly beneficial to new hosts can fail to ensue due to lack of physical proximity to the donor organism, lack of a suitable gene transfer mechanism, genetic compatibility, and stochasticity in tempo-spatial occurrence. Experimental attempts to detect HGT events in bacterial populations have typically focused on the transformed cells or their immediate offspring. However, rare HGT events occurring in large and structured populations are unlikely to reach relative population sizes that will allow their immediate identification; the exception being the unusually strong positive selection conferred by antibiotics. Most HGT events are not expected to alter the likelihood of host survival to such an extreme extent, and will confer only minor changes in host fitness. Due to the large population sizes of bacteria and the time scales involved, the process and outcome of HGT are often not amenable to experimental investigation. Population genetic modeling of the growth dynamics of bacteria with differing HGT rates and resulting fitness changes is therefore necessary to guide sampling design and predict realistic time frames for detection of HGT, as it occurs in laboratory or natural settings. Here we review the key population genetic parameters, consider their complexity and highlight knowledge gaps for further research. PMID:24432015

  3. Detecting rare gene transfer events in bacterial populations

    PubMed Central

    Nielsen, Kaare M.; Bøhn, Thomas; Townsend, Jeffrey P.

    2014-01-01

    Horizontal gene transfer (HGT) enables bacteria to access, share, and recombine genetic variation, resulting in genetic diversity that cannot be obtained through mutational processes alone. In most cases, the observation of evolutionary successful HGT events relies on the outcome of initially rare events that lead to novel functions in the new host, and that exhibit a positive effect on host fitness. Conversely, the large majority of HGT events occurring in bacterial populations will go undetected due to lack of replication success of transformants. Moreover, other HGT events that would be highly beneficial to new hosts can fail to ensue due to lack of physical proximity to the donor organism, lack of a suitable gene transfer mechanism, genetic compatibility, and stochasticity in tempo-spatial occurrence. Experimental attempts to detect HGT events in bacterial populations have typically focused on the transformed cells or their immediate offspring. However, rare HGT events occurring in large and structured populations are unlikely to reach relative population sizes that will allow their immediate identification; the exception being the unusually strong positive selection conferred by antibiotics. Most HGT events are not expected to alter the likelihood of host survival to such an extreme extent, and will confer only minor changes in host fitness. Due to the large population sizes of bacteria and the time scales involved, the process and outcome of HGT are often not amenable to experimental investigation. Population genetic modeling of the growth dynamics of bacteria with differing HGT rates and resulting fitness changes is therefore necessary to guide sampling design and predict realistic time frames for detection of HGT, as it occurs in laboratory or natural settings. Here we review the key population genetic parameters, consider their complexity and highlight knowledge gaps for further research. PMID:24432015

  4. Widespread impact of horizontal gene transfer on plant colonization of land

    PubMed Central

    Yue, Jipei; Hu, Xiangyang; Sun, Hang; Yang, Yongping; Huang, Jinling

    2012-01-01

    In complex multicellular eukaryotes such as animals and plants, horizontal gene transfer is commonly considered rare with very limited evolutionary significance. Here we show that horizontal gene transfer is a dynamic process occurring frequently in the early evolution of land plants. Our genome analyses of the moss Physcomitrella patens identified 57 families of nuclear genes that were acquired from prokaryotes, fungi or viruses. Many of these gene families were transferred to the ancestors of green or land plants. Available experimental evidence shows that these anciently acquired genes are involved in some essential or plant-specific activities such as xylem formation, plant defence, nitrogen recycling as well as the biosynthesis of starch, polyamines, hormones and glutathione. These findings suggest that horizontal gene transfer had a critical role in the transition of plants from aquatic to terrestrial environments. On the basis of these findings, we propose a model of horizontal gene transfer mechanism in nonvascular and seedless vascular plants. PMID:23093189

  5. Numerical Simulations of the Onset and Stability of Dynamical Mass Transfer in Binaries

    NASA Astrophysics Data System (ADS)

    D'Souza, Mario C. R.; Motl, Patrick M.; Tohline, Joel E.; Frank, Juhan

    2006-05-01

    Hydrodynamical simulations of semidetached, polytropic binary stars are presented in an effort to study the onset and stability of dynamical mass transfer events. Initial, synchronously rotating equilibrium models are constructed using a self-consistent field technique and then evolved with an Eulerian hydrodynamics code in a fully self-consistent manner. We describe code improvements introduced over the past few years that permit us to follow dynamical mass transfer events through more than 30 orbits. Mass transfer evolutions are presented for two different initial configurations: a dynamically unstable binary with initial mass ratio (donor/accretor) q0=1.3 that leads to a complete merger in ~10 orbits, and a double-degenerate binary with initial mass ratio q0=0.5 that, after some initial unstable growth of mass transfer, tends to separate as the mass transfer rate levels off.

  6. Multiple losses and transfers to the nucleus of two mitochondrial succinate dehydrogenase genes during angiosperm evolution.

    PubMed Central

    Adams, K L; Rosenblueth, M; Qiu, Y L; Palmer, J D

    2001-01-01

    Unlike in animals, the functional transfer of mitochondrial genes to the nucleus is an ongoing process in plants. All but one of the previously reported transfers in angiosperms involve ribosomal protein genes. Here we report frequent transfer of two respiratory genes, sdh3 and sdh4 (encoding subunits 3 and 4 of succinate dehydrogenase), and we also show that these genes are present and expressed in the mitochondria of diverse angiosperms. Southern hybridization surveys reveal that sdh3 and sdh4 have been lost from the mitochondrion about 40 and 19 times, respectively, among the 280 angiosperm genera examined. Transferred, functional copies of sdh3 and sdh4 were characterized from the nucleus in four and three angiosperm families, respectively. The mitochondrial targeting presequences of two sdh3 genes are derived from preexisting genes for anciently transferred mitochondrial proteins. On the basis of the unique presequences of the nuclear genes and the recent mitochondrial gene losses, we infer that each of the seven nuclear sdh3 and sdh4 genes was derived from a separate transfer to the nucleus. These results strengthen the hypothesis that angiosperms are experiencing a recent evolutionary surge of mitochondrial gene transfer to the nucleus and reveal that this surge includes certain respiratory genes in addition to ribosomal protein genes. PMID:11454775

  7. Kidney-specific Sonoporation-mediated Gene Transfer

    PubMed Central

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

    2016-01-01

    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. PMID:26419704

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

    PubMed Central

    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. Engineering Task Plan for Hose In Hose Transfer Lines for the Interim Stabilization Program

    SciTech Connect

    RUNG, M.P.

    2000-06-20

    This document is the Engineering Task Plan for the engineering, design services, planning, project integration and management support for the design, modification, installation and testing of an over ground transfer (OGT) system to support the interim stabilization of nine tanks in the 241-S/SX Tank Farms.

  10. Engineering Task Plan for Hose In Hose Transfer Lines for the Interim Stabilization Program

    SciTech Connect

    TORRES, T.D.

    2000-08-16

    The document is the Engineering Task Plan for the engineering, design services, planning, project integration and management support for the design, modification, installation and testing of an over ground transfer (OGT) system to support the interim stabilization of S/SX and U Tank Farms.

  11. The tryptophanase gene cluster of Haemophilus influenzae type b: evidence for horizontal gene transfer.

    PubMed

    Martin, K; Morlin, G; Smith, A; Nordyke, A; Eisenstark, A; Golomb, M

    1998-01-01

    Among strains of Haemophilus influenzae, the ability to catabolize tryptophan (as detected by indole production) varies and is correlated with pathogenicity. Tryptophan catabolism is widespread (70 to 75%) among harmless respiratory isolates but is nearly universal (94 to 100%) among strains causing serious disease, including meningitis. As a first step in investigating the relationship between tryptophan catabolism and virulence, we have identified genes in pathogenic H. influenzae which are homologous to the tryptophanase (tna) operon of Escherichia coli. The tna genes are located on a 3.1-kb fragment between nlpD and mutS in the H. influenzae type b (Eagan) genome, are flanked by 43-bp direct repeats of an uptake signal sequence downstream from nlpD, and appear to have been inserted as a mobile unit within this sequence. The organization of this insertion is reminiscent of pathogenicity islands. The tna cluster is found at the same map location in all indole-positive strains of H. influenzae surveyed and is absent from reference type d and e genomes. In contrast to H. influenzae, most other Haemophilus species lack tna genes. Phylogenetic comparisons suggest that the tna cluster was acquired by intergeneric lateral transfer, either by H. influenzae or a recent ancestor, and that E. coli may have acquired its tnaA gene from a related source. Genomes of virulent H. influenzae resemble those of pathogenic enterics in having an island of laterally transferred DNA next to mutS. PMID:9422600

  12. Gene-transfer study approval awaits more data

    SciTech Connect

    Marwick, C.

    1988-11-18

    Approval of the gene-transfer study in cancer patients has been delayed. The proposal was recommended for approval by a National Institutes of Health (NIH) advisory committee, but has been put on hold by James B. Wyngaarden, MD, NIH director, pending submission in writing of further information. Some of this information, now forthcoming, had been withheld because data on preliminary studies had been submitted to peer-reviewed journals. The study involves placing the gene for neomycin-resistance to tumor-infiltrating lymphocytes as a marker. When these cells are injected into the patient, the presence of the marker should enable their fate to be studied over a prolonged period and an improved antitumor regimen could result. The use of tumor-infiltrating lymphocytes as immunotherapy has been studied for two years at the NIH's National Cancer Institute. The patients' tumors are removed and the tumor-infiltrating lymphocytes are cultivated to obtain several billion cells. These cells are then injected back into the patient. Early clinical experience has shown a substantial decease in tumor size in some patients, but not in all, an no one knows why.

  13. Adenoviral-mediated gene transfer to rabbit synovium in vivo.

    PubMed Central

    Roessler, B J; Allen, E D; Wilson, J M; Hartman, J W; Davidson, B L

    1993-01-01

    Currently, treatment for rheumatoid arthritis and other inflammatory arthropathies is often ineffective in ameliorating the progression of the disease, particularly the invasive destruction of cartilage and bone by rheumatoid synovium. Multiple aspects of this inflammatory process are mediated by the synovial lining cells (synoviocytes). Genetic modification of these cells in vivo represents a potential method for the treatment of these conditions. In this report, we describe a novel technique for the genetic transduction of synovial lining cells in vivo using recombinant adenoviral vectors and intraarticular injection techniques. Purified high titer suspensions of a recombinant adenoviral vector containing the gene for Escherichia coli beta-galactosidase (AdCMVlacZ) were directly injected into the hind knees of New Zealand white rabbits. Synovial tissues were then examined for transgenic lacZ expression using a combination of in situ staining for beta-galactosidase activity, immunohistochemical staining, and transmission electron microscopy. High efficiency gene transfer and lacZ expression was observed in both type A and type B synoviocytes throughout the articular and periarticular synovium of the rabbit knee, with continued expression of transgenic lacZ detected for > or = 8 wk after infection. Images PMID:8349791

  14. Passive Immunization against HIV/AIDS by Antibody Gene Transfer

    PubMed Central

    Yang, Lili; Wang, Pin

    2014-01-01

    Despite tremendous efforts over the course of many years, the quest for an effective HIV vaccine by the classical method of active immunization remains largely elusive. However, two recent studies in mice and macaques have now demonstrated a new strategy designated as Vectored ImmunoProphylaxis (VIP), which involves passive immunization by viral vector-mediated delivery of genes encoding broadly neutralizing antibodies (bnAbs) for in vivo expression. Robust protection against virus infection was observed in preclinical settings when animals were given VIP to express monoclonal neutralizing antibodies. This unorthodox approach raises new promise for combating the ongoing global HIV pandemic. In this article, we survey the status of antibody gene transfer, review the revolutionary progress on isolation of extremely bnAbs, detail VIP experiments against HIV and its related virus conduced in humanized mice and macaque monkeys, and discuss the pros and cons of VIP and its opportunities and challenges towards clinical applications to control HIV/AIDS endemics. PMID:24473340

  15. Passive immunization against HIV/AIDS by antibody gene transfer.

    PubMed

    Yang, Lili; Wang, Pin

    2014-02-01

    Despite tremendous efforts over the course of many years, the quest for an effective HIV vaccine by the classical method of active immunization remains largely elusive. However, two recent studies in mice and macaques have now demonstrated a new strategy designated as Vectored ImmunoProphylaxis (VIP), which involves passive immunization by viral vector-mediated delivery of genes encoding broadly neutralizing antibodies (bnAbs) for in vivo expression. Robust protection against virus infection was observed in preclinical settings when animals were given VIP to express monoclonal neutralizing antibodies. This unorthodox approach raises new promise for combating the ongoing global HIV pandemic. In this article, we survey the status of antibody gene transfer, review the revolutionary progress on isolation of extremely bnAbs, detail VIP experiments against HIV and its related virus conduced in humanized mice and macaque monkeys, and discuss the pros and cons of VIP and its opportunities and challenges towards clinical applications to control HIV/AIDS endemics. PMID:24473340

  16. Horizontal transference of S-layer genes within Thermus thermophilus.

    PubMed Central

    Fernández-Herrero, L A; Olabarría, G; Castón, J R; Lasa, I; Berenguer, J

    1995-01-01

    The S-layers of Thermus thermophilus HB27 and T. thermophilus HB8 are composed of protein units of 95 kDa (P95) and 100 kDa (P100), respectively. We have selected S-layer deletion mutants from both strains by complete replacement of the slpA gene. Mutants of the two strains showed similar defects in growth and morphology and overproduced an external cell envelope inside of which cells remained after division. However, the nature of this external layer is strain specific, being easily stained and regular in the HB8 delta slpA derivative and amorphous and poorly stained in the HB27 delta slpA strain. The addition of chromosomic DNA from T. thermophilus HB8 to growing cultures of T. thermophilus HB27 delta slpA led to the selection of a new strain, HB27C8, which expressed a functional S-layer composed of the P100 protein. Conversely, the addition of chromosomic DNA from T. thermophilus HB27 to growing cultures of T. thermophilus HB8 delta slpA allowed the isolation of strain HB8C27, which expressed a functional S-layer composed of the P95 protein. The driving force which selected the transference of the S-layer genes in these experiments was the difference in growth rates, one of the main factors leading to selection in natural environments. PMID:7559330

  17. Genome-scale phylogenetic analysis finds extensive gene transfer among fungi

    PubMed Central

    Szöllősi, Gergely J.; Davín, Adrián Arellano; Tannier, Eric; Daubin, Vincent; Boussau, Bastien

    2015-01-01

    Although the role of lateral gene transfer is well recognized in the evolution of bacteria, it is generally assumed that it has had less influence among eukaryotes. To explore this hypothesis, we compare the dynamics of genome evolution in two groups of organisms: cyanobacteria and fungi. Ancestral genomes are inferred in both clades using two types of methods: first, Count, a gene tree unaware method that models gene duplications, gains and losses to explain the observed numbers of genes present in a genome; second, ALE, a more recent gene tree-aware method that reconciles gene trees with a species tree using a model of gene duplication, loss and transfer. We compare their merits and their ability to quantify the role of transfers, and assess the impact of taxonomic sampling on their inferences. We present what we believe is compelling evidence that gene transfer plays a significant role in the evolution of fungi. PMID:26323765

  18. Frequent, independent transfers of a catabolic gene from bacteria to contrasted filamentous eukaryotes

    PubMed Central

    Bruto, Maxime; Prigent-Combaret, Claire; Luis, Patricia; Moënne-Loccoz, Yvan; Muller, Daniel

    2014-01-01

    Even genetically distant prokaryotes can exchange genes between them, and these horizontal gene transfer events play a central role in adaptation and evolution. While this was long thought to be restricted to prokaryotes, certain eukaryotes have acquired genes of bacterial origin. However, gene acquisitions in eukaryotes are thought to be much less important in magnitude than in prokaryotes. Here, we describe the complex evolutionary history of a bacterial catabolic gene that has been transferred repeatedly from different bacterial phyla to stramenopiles and fungi. Indeed, phylogenomic analysis pointed to multiple acquisitions of the gene in these filamentous eukaryotes—as many as 15 different events for 65 microeukaryotes. Furthermore, once transferred, this gene acquired introns and was found expressed in mRNA databases for most recipients. Our results show that effective inter-domain transfers and subsequent adaptation of a prokaryotic gene in eukaryotic cells can happen at an unprecedented magnitude. PMID:24990676

  19. Horizontal gene transfer and gene dosage drives adaptation to wood colonization in a tree pathogen

    PubMed Central

    Dhillon, Braham; Feau, Nicolas; Aerts, Andrea L.; Beauseigle, Stéphanie; Bernier, Louis; Copeland, Alex; Foster, Adam; Gill, Navdeep; Henrissat, Bernard; Herath, Padmini; LaButti, Kurt M.; Levasseur, Anthony; Lindquist, Erika A.; Majoor, Eline; Ohm, Robin A.; Pangilinan, Jasmyn L.; Pribowo, Amadeus; Saddler, John N.; Sakalidis, Monique L.; de Vries, Ronald P.; Grigoriev, Igor V.; Goodwin, Stephen B.; Tanguay, Philippe; Hamelin, Richard C.

    2015-01-01

    Some of the most damaging tree pathogens can attack woody stems, causing lesions (cankers) that may be lethal. To identify the genomic determinants of wood colonization leading to canker formation, we sequenced the genomes of the poplar canker pathogen, Mycosphaerella populorum, and the closely related poplar leaf pathogen, M. populicola. A secondary metabolite cluster unique to M. populorum is fully activated following induction by poplar wood and leaves. In addition, genes encoding hemicellulose-degrading enzymes, peptidases, and metabolite transporters were more abundant and were up-regulated in M. populorum growing on poplar wood-chip medium compared with M. populicola. The secondary gene cluster and several of the carbohydrate degradation genes have the signature of horizontal transfer from ascomycete fungi associated with wood decay and from prokaryotes. Acquisition and maintenance of the gene battery necessary for growth in woody tissues and gene dosage resulting in gene expression reconfiguration appear to be responsible for the adaptation of M. populorum to infect, colonize, and cause mortality on poplar woody stems. PMID:25733908

  20. Towards liver-directed gene therapy: retrovirus-mediated gene transfer into human hepatocytes.

    PubMed

    Grossman, M; Raper, S E; Wilson, J M

    1991-11-01

    Liver-directed gene therapy is being considered in the treatment of inherited metabolic diseases. One approach we are considering is the transplantation of autologous hepatocytes that have been genetically modified with recombinant retroviruses ex vivo. We describe, in this report, techniques for isolating human hepatocytes and efficiently transducing recombinant genes into primary cultures. Hepatocytes were isolated from tissue of four different donors, plated in primary culture, and exposed to recombinant retroviruses expressing either the LacZ reporter gene or the cDNA for rabbit LDL receptor. The efficiency of gene transfer under optimal conditions, as determined by Southern blot analysis, varied from a maximum of one proviral copy per cell to a minimum of 0.1 proviral copy per cell. Cytochemical assays were used to detect expression of the recombinant derived proteins, E. coli beta-galactosidase and rabbit LDL receptor. Hepatocytes transduced with the LDL receptor gene expressed levels of receptor protein that exceeded the normal endogenous levels. The ability to isolate and genetically modify human hepatocytes, as described in this report, is an important step towards the development of liver-directed gene therapies in humans. PMID:1767337

  1. Horizontal gene transfer and gene dosage drives adaptation to wood colonization in a tree pathogen.

    PubMed

    Dhillon, Braham; Feau, Nicolas; Aerts, Andrea L; Beauseigle, Stéphanie; Bernier, Louis; Copeland, Alex; Foster, Adam; Gill, Navdeep; Henrissat, Bernard; Herath, Padmini; LaButti, Kurt M; Levasseur, Anthony; Lindquist, Erika A; Majoor, Eline; Ohm, Robin A; Pangilinan, Jasmyn L; Pribowo, Amadeus; Saddler, John N; Sakalidis, Monique L; de Vries, Ronald P; Grigoriev, Igor V; Goodwin, Stephen B; Tanguay, Philippe; Hamelin, Richard C

    2015-03-17

    Some of the most damaging tree pathogens can attack woody stems, causing lesions (cankers) that may be lethal. To identify the genomic determinants of wood colonization leading to canker formation, we sequenced the genomes of the poplar canker pathogen, Mycosphaerella populorum, and the closely related poplar leaf pathogen, M. populicola. A secondary metabolite cluster unique to M. populorum is fully activated following induction by poplar wood and leaves. In addition, genes encoding hemicellulose-degrading enzymes, peptidases, and metabolite transporters were more abundant and were up-regulated in M. populorum growing on poplar wood-chip medium compared with M. populicola. The secondary gene cluster and several of the carbohydrate degradation genes have the signature of horizontal transfer from ascomycete fungi associated with wood decay and from prokaryotes. Acquisition and maintenance of the gene battery necessary for growth in woody tissues and gene dosage resulting in gene expression reconfiguration appear to be responsible for the adaptation of M. populorum to infect, colonize, and cause mortality on poplar woody stems. PMID:25733908

  2. The Fusarium graminearum Genome Reveals More Secondary Metabolite Gene Clusters and Hints of Horizontal Gene Transfer

    PubMed Central

    Wong, Philip; Münsterkötter, Martin; Mewes, Hans-Werner; Schmeitzl, Clemens; Varga, Elisabeth; Berthiller, Franz; Adam, Gerhard; Güldener, Ulrich

    2014-01-01

    Fungal secondary metabolite biosynthesis genes are of major interest due to the pharmacological properties of their products (like mycotoxins and antibiotics). The genome of the plant pathogenic fungus Fusarium graminearum codes for a large number of candidate enzymes involved in secondary metabolite biosynthesis. However, the chemical nature of most enzymatic products of proteins encoded by putative secondary metabolism biosynthetic genes is largely unknown. Based on our analysis we present 67 gene clusters with significant enrichment of predicted secondary metabolism related enzymatic functions. 20 gene clusters with unknown metabolites exhibit strong gene expression correlation in planta and presumably play a role in virulence. Furthermore, the identification of conserved and over-represented putative transcription factor binding sites serves as additional evidence for cluster co-regulation. Orthologous cluster search provided insight into the evolution of secondary metabolism clusters. Some clusters are characteristic for the Fusarium phylum while others show evidence of horizontal gene transfer as orthologs can be found in representatives of the Botrytis or Cochliobolus lineage. The presented candidate clusters provide valuable targets for experimental examination. PMID:25333987

  3. Improved efficiency of the walnut somatic embryo gene transfer system.

    PubMed

    McGranahan, G H; Leslie, C A; Uratsu, S L; Dandekar, A M

    1990-01-01

    AnAgrobacterium-mediated gene transfer system which relies on repetitive embryogenesis to regenerate transgenic walnut plants has been made more efficient by using a more virulent strain ofAgrobacterium and vectors containing genes for both kanamycin resistance and beta-glucuronidase (GUS) activity to facilitate early screening and selection. Two plasmids (pCGN7001 and pCGN7314) introduced individually into the disarmedAgrobacterium host strain EHA101 were used as inoculum. Embryos maintained on medium containing 100 mg/l kanamycin after co-cultivation produced more transformed secondary embryos than embryos maintained on kanamycin-free medium. Of the 186 GUS-positive secondary embryo lines identified, 70% were regenerated from 3 out of 16 primary embryos inoculated with EHA101/pCGN7314 and grown on kanamycin- containing medium, 28% from 4 out of 17 primary embryos inoculated with EHA101/ pCGN7001 and grown on kanamycin medium, and 2% from one out of 13 primary embryos inoculated with EHA101/pCGN7001 but not exposed to kanamycin. Because kanamycin inhibits but does not completely block new embryo formation in controls, identification of transformants formerly required repetitive selection on kanamycin for several months. Introduction of the GUS marker gene allowed positive identification of transformant secondary embryos as early as 5-6 weeks after inoculation. DNA analysis of a representative subset of lines (n=13) derived from secondary embryos confirmed transformation and provided evidence for multiple insertion events in single inoculated primary embryos. PMID:24226275

  4. Total Transfer Capability Assessment Incorporating Corrective Controls for Transient Stability using TSCOPF

    NASA Astrophysics Data System (ADS)

    Hakim, Lukmanul; Kubokawa, Junji; Yorino, Naoto; Zoka, Yoshifumi; Sasaki, Yutaka

    Advancements have been made towards inclusion of both static and dynamic security into transfer capability calculation. However, to the authors' knowledge, work on considering corrective controls into the calculation has not been reported yet. Therefore, we propose a Total Transfer Capability (TTC) assessment considering transient stability corrective controls. The method is based on the Newton interior point method for nonlinear programming and transfer capability is approached as a maximization of power transfer with both static and transient stability constraints are incorporated into our Transient Stability Constrained Optimal Power Flow (TSCOPF) formulation. An interconnected power system is simulated to be subjected to a severe unbalanced 3-phase 4-line to ground fault and following the fault, generator and load are shed in a pre-defined sequence to mimic actual corrective controls. In a deregulated electricity market, both generator companies and large load customers are encouraged to actively participate in maintaining power system stability as corrective controls upon agreement of compensation for being shed following a disturbance. Implementation of this proposal on the actual power system operation should be carried out through combining it with the existing transient stabilization controller system. Utilization of these corrective controls results in increasing TTC as suggested in our numerical simulation. As Lagrange multipliers can also describe sensitivity of both inequality and equality constraints to the objective function, then selection of which generator or load to be shed can be carried out on the basis of values of Lagrange multipliers of its respective generator's rotor angle stability and active power balance equation. Hence, the proposal in this paper can be utilized by system operator to assess the maximum TTC for specific loads and network conditions.

  5. Multimodality Imaging of Gene Transfer with a Receptor-Based Reporter Gene

    PubMed Central

    Chen, Ron; Parry, Jesse J.; Akers, Walter J.; Berezin, Mikhail Y.; El Naqa, Issam M.; Achilefu, Samuel; Edwards, W. Barry; Rogers, Buck E.

    2010-01-01

    Gene therapy trials have traditionally used tumor and tissue biopsies for assessing the efficacy of gene transfer. Non-invasive imaging techniques offer a distinct advantage over tissue biopsies in that the magnitude and duration of gene transfer can be monitored repeatedly. Human somatostatin receptor subtype 2 (SSTR2) has been used for the nuclear imaging of gene transfer. To extend this concept, we have developed a somatostatin receptor–enhanced green fluorescent protein fusion construct (SSTR2-EGFP) for nuclear and fluorescent multimodality imaging. Methods An adenovirus containing SSTR2-EGFP (AdSSTR2-EGFP) was constructed and evaluated in vitro and in vivo. SCC-9 human squamous cell carcinoma cells were infected with AdEGFP, AdSSTR2, or AdSSTR2-EGFP for in vitro evaluation by saturation binding, internalization, and fluorescence spectroscopy assays. In vivo biodistribution and nano-SPECT imaging studies were conducted with mice bearing SCC-9 tumor xenografts directly injected with AdSSTR2-EGFP or AdSSTR2 to determine the tumor localization of 111In-diethylenetriaminepentaacetic acid (DTPA)-Tyr3-octreotate. Fluorescence imaging was conducted in vivo with mice receiving intratumoral injections of AdSSTR2, AdSSTR2-EGFP, or AdEGFP as well as ex vivo with tissues extracted from mice. Results The similarity between AdSSTR2-EGFP and wild-type AdSSTR2 was demonstrated in vitro by the saturation binding and internalization assays, and the fluorescence emission spectra of cells infected with AdSSTR2-EGFP was almost identical to the spectra of cells infected with wild-type AdEGFP. Biodistribution studies demonstrated that the tumor uptake of 111In-DTPA-Tyr3-octreotate was not significantly different (P > 0.05) when tumors (n = 5) were injected with AdSSTR2 or AdSSTR2-EGFP but was significantly greater than the uptake in control tumors. Fluorescence was observed in tumors injected with AdSSTR2-EGFP and AdEGFP in vivo and ex vivo but not in tumors injected with AdSSTR2

  6. Persistent Gene Expression in Mouse Nasal Epithelia following Feline Immunodeficiency Virus-Based Vector Gene Transfer

    PubMed Central

    Sinn, Patrick L.; Burnight, Erin R.; Hickey, Melissa A.; Blissard, Gary W.; McCray, Paul B.

    2005-01-01

    Gene transfer development for treatment or prevention of cystic fibrosis lung disease has been limited by the inability of vectors to efficiently and persistently transduce airway epithelia. Influenza A is an enveloped virus with natural lung tropism; however, pseudotyping feline immunodeficiency virus (FIV)-based lentiviral vector with the hemagglutinin envelope protein proved unsuccessful. Conversely, pseudotyping FIV with the envelope protein from influenza D (Thogoto virus GP75) resulted in titers of 106 transducing units (TU)/ml and conferred apical entry into well-differentiated human airway epithelial cells. Baculovirus GP64 envelope glycoproteins share sequence identity with influenza D GP75 envelope glycoproteins. Pseudotyping FIV with GP64 from three species of baculovirus resulted in titers of 107 to 109 TU/ml. Of note, GP64 from Autographa californica multicapsid nucleopolyhedrovirus resulted in high-titer FIV preparations (∼109 TU/ml) and conferred apical entry into polarized primary cultures of human airway epithelia. Using a luciferase reporter gene and bioluminescence imaging, we observed persistent gene expression from in vivo gene transfer in the mouse nose with A. californica GP64-pseudotyped FIV (AcGP64-FIV). Longitudinal bioluminescence analysis documented persistent expression in nasal epithelia for ∼1 year without significant decline. According to histological analysis using a LacZ reporter gene, olfactory and respiratory epithelial cells were transduced. In addition, methylcellulose-formulated AcGP64-FIV transduced mouse nasal epithelia with much greater efficiency than similarly formulated vesicular stomatitis virus glycoprotein-pseudotyped FIV. These data suggest that AcGP64-FIV efficiently transduces and persistently expresses a transgene in nasal epithelia in the absence of agents that disrupt the cellular tight junction integrity. PMID:16188984

  7. Stabilization of gene expression and cell morphology after explant recycling during fin explant culture in goldfish.

    PubMed

    Chenais, Nathalie; Lareyre, Jean-Jacques; Le Bail, Pierre-Yves; Labbe, Catherine

    2015-07-01

    The development of fin primary cell cultures for in vitro cellular and physiological studies is hampered by slow cell outgrowth, low proliferation rate, poor viability, and sparse cell characterization. Here, we investigated whether the recycling of fresh explants after a first conventional culture could improve physiological stability and sustainability of the culture. The recycled explants were able to give a supplementary cell culture showing faster outgrowth, cleaner cell layers and higher net cell production. The cells exhibited a highly stabilized profile for marker gene expression including a low cytokeratin 49 (epithelial marker) and a high collagen 1a1 (mesenchymal marker) expression. Added to the cell spindle-shaped morphology, motility behavior, and actin organization, this suggests that the cells bore stable mesenchymal characteristics. This contrast with the time-evolving expression pattern observed in the control fresh explants during the first 2 weeks of culture: a sharp decrease in cytokeratin 49 expression was concomitant with a gradual increase in col1a1. We surmise that such loss of epithelial features for the benefit of mesenchymal ones was triggered by an epithelial to mesenchymal transition (EMT) process or by way of a progressive population replacement process. Overall, our findings provide a comprehensive characterization of this new primary culture model bearing mesenchymal features and whose stability over culture time makes those cells good candidates for cell reprogramming prior to nuclear transfer, in a context of fish genome preservation. PMID:25929521

  8. Horizontal gene transfer of a Chlamydial tRNA-guanine transglycosylase gene to eukaryotic microbes.

    PubMed

    Manna, Sam; Harman, Ashley

    2016-01-01

    tRNA-guanine transglycosylases are found in all domains of life and mediate the base exchange of guanine with queuine in the anticodon loop of tRNAs. They can also regulate virulence in bacteria such as Shigella flexneri, which has prompted the development of drugs that inhibit the function of these enzymes. Here we report a group of tRNA-guanine transglycosylases in eukaryotic microbes (algae and protozoa) which are more similar to their bacterial counterparts than previously characterized eukaryotic tRNA-guanine transglycosylases. We provide evidence demonstrating that the genes encoding these enzymes were acquired by these eukaryotic lineages via horizontal gene transfer from the Chlamydiae group of bacteria. Given that the S. flexneri tRNA-guanine transglycosylase can be targeted by drugs, we propose that the bacterial-like tRNA-guanine transglycosylases could potentially be targeted in a similar fashion in pathogenic amoebae that possess these enzymes such as Acanthamoeba castellanii. This work also presents ancient prokaryote-to-eukaryote horizontal gene transfer events as an untapped resource of potential drug target identification in pathogenic eukaryotes. PMID:26435002

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

    NASA Technical Reports Server (NTRS)

    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.

  10. Transduction-Like Gene Transfer in the Methanogen Methanococcus voltae

    PubMed Central

    Bertani, Giuseppe

    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 × 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. PMID:10321998

  11. Self-assembled ternary complexes stabilized with hyaluronic acid-green tea catechin conjugates for targeted gene delivery.

    PubMed

    Liang, Kun; Bae, Ki Hyun; Lee, Fan; Xu, Keming; Chung, Joo Eun; Gao, Shu Jun; Kurisawa, Motoichi

    2016-03-28

    Nanosized polyelectrolyte complexes are attractive delivery vehicles for the transfer of therapeutic genes to diseased cells. Here we report the application of self-assembled ternary complexes constructed with plasmid DNA, branched polyethylenimine and hyaluronic acid-green tea catechin conjugates for targeted gene delivery. These conjugates not only stabilize plasmid DNA/polyethylenimine complexes via the strong DNA-binding affinity of green tea catechin, but also facilitate their transport into CD44-overexpressing cells via receptor-mediated endocytosis. The hydrodynamic size, surface charge and physical stability of the complexes are characterized. We demonstrate that the stabilized ternary complexes display enhanced resistance to nuclease attack and polyanion-induced dissociation. Moreover, the ternary complexes can efficiently transfect the difficult-to-transfect HCT-116 colon cancer cell line even in serum-supplemented media due to their enhanced stability and CD44-targeting ability. Confocal microscopic analysis demonstrates that the stabilized ternary complexes are able to promote the nuclear transport of plasmid DNA more effectively than binary complexes and hyaluronic acid-coated ternary complexes. The present study suggests that the ternary complexes stabilized with hyaluronic acid-green tea catechin conjugates can be widely utilized for CD44-targeted delivery of nucleic acid-based therapeutics. PMID:26855049

  12. Calfection: a novel gene transfer method for suspension cells.

    PubMed

    Lindell, Jeanette; Girard, Philippe; Müller, Natalie; Jordan, Martin; Wurm, Florian

    2004-01-20

    We have developed a novel method called Calfection for gene delivery to and protein expression from suspension-cultivated mammalian cells. Plasmid DNA was simply diluted into a calcium chloride solution and then added to the cell culture for transfection. We evaluated and optimized this approach using suspension-adapted HEK293 cells grown in 12-well plates that were shaken on an orbital shaker. Highest expression levels were obtained when cells were transfected at a density of 5x10(5) cells/ml in the presence of 9 mM calcium and 5 microg/ml of plasmid DNA while maintaining a culture pH of 7.6 at the time of transfection. Suspension-adapted BHK 21 and CHO DG 44 cells could also be transfected using this method. Calfection differs from the widely known calcium phosphate coprecipitation technique. The physico-chemical composition of the DNA interacting complexes is not yet known. The transfection cocktail, DNA in a calcium chloride solution, remained highly efficient during long-term storage at temperatures ranging from room temperature to -80 degrees C. In contrast, calcium phosphate-DNA cocktails are only efficient for gene transfer when prepared fresh. Furthermore, passing the calcium-plasmid DNA mixture through a 0.2-microm filter did not compromise protein expression, whereas calcium phosphate-DNA coprecipitates were retained by the filter. High protein expression levels, a limited number of manipulations and the possibility to filter the cocktail make the Calfection approach suitable for both large-scale transfection in bioreactors and for high-throughput transfection experiments in microtiter plates. PMID:14746910

  13. Microbial Evolution Is in the Cards: Horizontal Gene Transfer in the Classroom

    ERIC Educational Resources Information Center

    Kagle, Jeanne; Hay, Anthony G.

    2007-01-01

    Horizontal gene transfer, the exchange of genetic material between bacteria, is a potentially important factor in the degradation of synthetic compounds introduced to the environment and in the acquisition of other characteristics including antibiotic resistance. This game-based activity illustrates the role of horizontal gene transfer in the…

  14. Characterizing short-term stability for Boolean networks over any distribution of transfer functions

    NASA Astrophysics Data System (ADS)

    Seshadhri, C.; Smith, Andrew M.; Vorobeychik, Yevgeniy; Mayo, Jackson R.; Armstrong, Robert C.

    2016-07-01

    We present a characterization of short-term stability of Kauffman's N K (random) Boolean networks under arbitrary distributions of transfer functions. Given such a Boolean network where each transfer function is drawn from the same distribution, we present a formula that determines whether short-term chaos (damage spreading) will happen. Our main technical tool which enables the formal proof of this formula is the Fourier analysis of Boolean functions, which describes such functions as multilinear polynomials over the inputs. Numerical simulations on mixtures of threshold functions and nested canalyzing functions demonstrate the formula's correctness.

  15. Characterizing short-term stability for Boolean networks over any distribution of transfer functions.

    PubMed

    Seshadhri, C; Smith, Andrew M; Vorobeychik, Yevgeniy; Mayo, Jackson R; Armstrong, Robert C

    2016-07-01

    We present a characterization of short-term stability of Kauffman's NK (random) Boolean networks under arbitrary distributions of transfer functions. Given such a Boolean network where each transfer function is drawn from the same distribution, we present a formula that determines whether short-term chaos (damage spreading) will happen. Our main technical tool which enables the formal proof of this formula is the Fourier analysis of Boolean functions, which describes such functions as multilinear polynomials over the inputs. Numerical simulations on mixtures of threshold functions and nested canalyzing functions demonstrate the formula's correctness. PMID:27575142

  16. Horizontal gene transfer in the acquisition of novel traits by metazoans

    PubMed Central

    Boto, Luis

    2014-01-01

    Horizontal gene transfer is accepted as an important evolutionary force modulating the evolution of prokaryote genomes. However, it is thought that horizontal gene transfer plays only a minor role in metazoan evolution. In this paper, I critically review the rising evidence on horizontally transferred genes and on the acquisition of novel traits in metazoans. In particular, I discuss suspected examples in sponges, cnidarians, rotifers, nematodes, molluscs and arthropods which suggest that horizontal gene transfer in metazoans is not simply a curiosity. In addition, I stress the scarcity of studies in vertebrates and other animal groups and the importance of forthcoming studies to understand the importance and extent of horizontal gene transfer in animals. PMID:24403327

  17. Gene transfer in the evolution of parasite nucleotide biosynthesis.

    PubMed

    Striepen, Boris; Pruijssers, Andrea J P; Huang, Jinling; Li, Catherine; Gubbels, Marc-Jan; Umejiego, Nwakaso N; Hedstrom, Lizbeth; Kissinger, Jessica C

    2004-03-01

    Nucleotide metabolic pathways provide numerous successful targets for antiparasitic chemotherapy, but the human pathogen Cryptosporidium parvum thus far has proved extraordinarily refractory to classical treatments. Given the importance of this protist as an opportunistic pathogen afflicting immunosuppressed individuals, effective treatments are urgently needed. The genome sequence of C. parvum is approaching completion, and we have used this resource to critically assess nucleotide biosynthesis as a target in C. parvum. Genomic analysis indicates that this parasite is entirely dependent on salvage from the host for its purines and pyrimidines. Metabolic pathway reconstruction and experimental validation in the laboratory further suggest that the loss of pyrimidine de novo synthesis is compensated for by possession of three salvage enzymes. Two of these, uridine kinase-uracil phosphoribosyltransferase and thymidine kinase, are unique to C. parvum within the phylum Apicomplexa. Phylogenetic analysis suggests horizontal gene transfer of thymidine kinase from a proteobacterium. We further show that the purine metabolism in C. parvum follows a highly streamlined pathway. Salvage of adenosine provides C. parvum's sole source of purines. This renders the parasite susceptible to inhibition of inosine monophosphate dehydrogenase, the rate-limiting enzyme in the multistep conversion of AMP to GMP. The inosine 5' monophosphate dehydrogenase inhibitors ribavirin and mycophenolic acid, which are already in clinical use, show pronounced anticryptosporidial activity. Taken together, these data help to explain why widely used drugs fail in the treatment of cryptosporidiosis and suggest more promising targets. PMID:14973196

  18. Neprilysin gene transfer: A promising therapeutic approach for Alzheimer's disease.

    PubMed

    Li, Yuanli; Wang, Junqing; Zhang, Shenghao; Liu, Zhaohui

    2015-09-01

    Alzheimer's disease (AD) is characterized by widespread neurodegeneration throughout the association cortex and limbic system, deposition of amyloid-β (Aβ) in the neuropil and around blood vessels, and formation of neurofibrillary tangles. Aβ accumulation is considered the major pathological change in AD progression. In recent years, several therapeutic strategies for treating AD have focused on reducing the Aβ burden in the brain. Among these approaches, the expression of Aβ-degrading enzymes in the brain has been effective but, so far, impractical for treating patients. Neprilysin (NEP), the most prominent of the Aβ-degrading enzymes in vivo, has been successfully delivered intracranially by viral vectors and is a promising therapeutic approach for reducing Aβ accumulation and treating AD. However, some challenges are associated with the use of viral and nonviral vectors, including secondary toxicity, activation of the immune response, and low efficiency. Therefore, safe and efficient NEP delivery systems that could avoid the viral problems with minor injury and high transfection efficiency are required to deliver AD medical applications. This Mini-Review summarizes NEP gene transfer technologies that use viral and nonviral vectors and discusses the rationale and benefits of these delivery systems for AD treatment trials, providing a reference for basic and clinical studies on AD. PMID:26096375

  19. Gene transfer in the evolution of parasite nucleotide biosynthesis

    PubMed Central

    Striepen, Boris; Pruijssers, Andrea J. P.; Huang, Jinling; Li, Catherine; Gubbels, Marc-Jan; Umejiego, Nwakaso N.; Hedstrom, Lizbeth; Kissinger, Jessica C.

    2004-01-01

    Nucleotide metabolic pathways provide numerous successful targets for antiparasitic chemotherapy, but the human pathogen Cryptosporidium parvum thus far has proved extraordinarily refractory to classical treatments. Given the importance of this protist as an opportunistic pathogen afflicting immunosuppressed individuals, effective treatments are urgently needed. The genome sequence of C. parvum is approaching completion, and we have used this resource to critically assess nucleotide biosynthesis as a target in C. parvum. Genomic analysis indicates that this parasite is entirely dependent on salvage from the host for its purines and pyrimidines. Metabolic pathway reconstruction and experimental validation in the laboratory further suggest that the loss of pyrimidine de novo synthesis is compensated for by possession of three salvage enzymes. Two of these, uridine kinase-uracil phosphoribosyltransferase and thymidine kinase, are unique to C. parvum within the phylum Apicomplexa. Phylogenetic analysis suggests horizontal gene transfer of thymidine kinase from a proteobacterium. We further show that the purine metabolism in C. parvum follows a highly streamlined pathway. Salvage of adenosine provides C. parvum's sole source of purines. This renders the parasite susceptible to inhibition of inosine monophosphate dehydrogenase, the rate-limiting enzyme in the multistep conversion of AMP to GMP. The inosine 5′ monophosphate dehydrogenase inhibitors ribavirin and mycophenolic acid, which are already in clinical use, show pronounced anticryptosporidial activity. Taken together, these data help to explain why widely used drugs fail in the treatment of cryptosporidiosis and suggest more promising targets. PMID:14973196

  20. Stagnation-point flow and heat transfer over an exponentially shrinking sheet: A stability analysis

    NASA Astrophysics Data System (ADS)

    Ismail, Nurul Syuhada; Arifin, Norihan Md.; Bachok, Norfifah; Mahiddin, Norhasimah

    2016-06-01

    Numerical solutions for the stagnation-point flow and heat transfer over an exponentially shrinking sheet have been investigated. The governing boundary layer equations are transformed into an ordinary differential equation using a non-similar transformation. By using the bvp4c solver in MATLAB, the results of the equations can be solved numerically. Numerical results indicate that in certain parameter, the non-unique solutions for the velocity and the temperature do exist. A linear stability analysis shows that only one solution is linearly stable otherwise is unstable. Then, the stability analysis is performed to identify which solution is stable between the two non-unique solutions.

  1. Identification of the class I genes of the mouse major histocompatibility complex by DNA-mediated gene transfer.

    PubMed

    Goodenow, R S; McMillan, M; Nicolson, M; Sher, B T; Eakle, K; Davidson, N; Hood, L

    1982-11-18

    DNA-mediated gene transfer was used to identify cloned class I genes from the major histocompatibility complex of the BALB/c mouse. Three genes encoding the transplantation antigens H-2 Kd, Dd and Ld were identified as well as genes encoding the Qa-2,3 and two TL differentiation antigens. As many as 10 putative novel class I genes were detected by the association of their gene products with beta 2-microglobulin. Alloantiserum prepared to one of the novel antigens was used to demonstrate the expression of the previously undetected antigen on spleen cells of various inbred, congeneic, and recombinant congeneic strains of mice. PMID:6815535

  2. Phase transfer of citrate stabilized gold nanoparticles using nonspecifically adsorbed polymers.

    PubMed

    Alkilany, Alaaldin M; Caravana, Aidan C; Hamaly, Majd A; Lerner, Kevin T; Thompson, Lucas B

    2016-01-01

    Many synthetic approaches for gold nanoparticles rely on an aqueous media, resulting in water-soluble nanoparticles, which limits the ability to incorporate gold nanoparticles into other organic solvents or hydrophobic polymeric composites. Surface functionalization and phase transfer approaches using alkylthiols or alkylamines, which strongly bind the gold surface, are common routes to overcome this limitation, however they are typically challenging methods. In this paper we report an approach to transport citrate capped gold nanoparticles into a variety of solvents, including ones that are hydrophobic and not miscible with water without the need for phase transfer agents. We suspend gold nanoparticles in a water-miscible polar organic solvent that also is a solvent for a hydrophobic polymer. After drying, polymer-stabilized gold nanoparticles were found to be dispersible in various hydrophobic solvents with maintained colloidal stability. This work investigates two hydrophobic polymers, namely (polymethylmethacrylate and polyvinylacetate), which share common chemical motifs but have significantly different physiochemical properties. Interestingly, a significant difference in their ability to stabilize the transferred gold nanoparticles is observed and discussed. PMID:26397907

  3. Non-Viral Gene Transfer as a Tool for Studying Transcription Regulation of Xenobiotic Metabolizing Enzymes

    PubMed Central

    Bonamassa, Barbara; Liu, Dexi

    2010-01-01

    Numerous xenobiotic metabolizing enzymes are regulated by nuclear receptors at transcriptional level. The challenge we currently face is to understand how a given nuclear receptor interacts with its xenobiotics, migrates into nucleus, binds to the xenobiotic response element of a target gene, and regulates transcription. Toward this end, new methods have been developed to introduce the nuclear receptor gene into appropriate cells and study its activity in activating reporter gene expression under the control of a promoter containing xenobiotic response elements. The goal of this review is to critically examine the gene transfer methods currently available. We concentrate on the gene transfer mechanism, advantages and limitations of each method when employed for nuclear receptor-mediated gene regulation studies. It is our hope that the information provided highlights the importance of gene transfer in studying the mechanisms by which our body eliminates the potentially harmful substances and maintains the homeostasis. PMID:20713102

  4. Dendronization-induced phase-transfer, stabilization and self-assembly of large colloidal Au nanoparticles.

    PubMed

    Malassis, Ludivine; Jishkariani, Davit; Murray, Christopher B; Donnio, Bertrand

    2016-07-21

    The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates. PMID:27348477

  5. Apramycin resistance as a selective marker for gene transfer in mycobacteria.

    PubMed Central

    Paget, E; Davies, J

    1996-01-01

    We have explored the potential of using the apramycin resistance gene as a marker in mycobacterial gene transfer studies. Shuttle plasmids available for both electroporation and conjugation studies have been constructed, and we have successfully validated the use of the apramycin resistance gene as a component of cloning vectors for Mycobacterium smegmatis, M. bovis BCG, and M. tuberculosis. PMID:8892841

  6. Dendronization-induced phase-transfer, stabilization and self-assembly of large colloidal Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Malassis, Ludivine; Jishkariani, Davit; Murray, Christopher B.; Donnio, Bertrand

    2016-07-01

    The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates.The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates. Electronic supplementary information (ESI) available: TEM microscope images. See DOI: 10.1039/c6nr03404g

  7. Migration and horizontal gene transfer divide microbial genomes into multiple niches.

    PubMed

    Niehus, Rene; Mitri, Sara; Fletcher, Alexander G; Foster, Kevin R

    2015-01-01

    Horizontal gene transfer is central to microbial evolution, because it enables genetic regions to spread horizontally through diverse communities. However, how gene transfer exerts such a strong effect is not understood. Here we develop an eco-evolutionary model and show how genetic transfer, even when rare, can transform the evolution and ecology of microbes. We recapitulate existing models, which suggest that asexual reproduction will overpower horizontal transfer and greatly limit its effects. We then show that allowing immigration completely changes these predictions. With migration, the rates and impacts of horizontal transfer are greatly increased, and transfer is most frequent for loci under positive natural selection. Our analysis explains how ecologically important loci can sweep through competing strains and species. In this way, microbial genomes can evolve to become ecologically diverse where different genomic regions encode for partially overlapping, but distinct, ecologies. Under these conditions ecological species do not exist, because genes, not species, inhabit niches. PMID:26592443

  8. Migration and horizontal gene transfer divide microbial genomes into multiple niches

    PubMed Central

    Niehus, Rene; Mitri, Sara; Fletcher, Alexander G.; Foster, Kevin R.

    2015-01-01

    Horizontal gene transfer is central to microbial evolution, because it enables genetic regions to spread horizontally through diverse communities. However, how gene transfer exerts such a strong effect is not understood. Here we develop an eco-evolutionary model and show how genetic transfer, even when rare, can transform the evolution and ecology of microbes. We recapitulate existing models, which suggest that asexual reproduction will overpower horizontal transfer and greatly limit its effects. We then show that allowing immigration completely changes these predictions. With migration, the rates and impacts of horizontal transfer are greatly increased, and transfer is most frequent for loci under positive natural selection. Our analysis explains how ecologically important loci can sweep through competing strains and species. In this way, microbial genomes can evolve to become ecologically diverse where different genomic regions encode for partially overlapping, but distinct, ecologies. Under these conditions ecological species do not exist, because genes, not species, inhabit niches. PMID:26592443

  9. Proteomic profiling of salivary gland after nonviral gene transfer mediated by conventional plasmids and minicircles

    PubMed Central

    Geguchadze, Ramaz; Wang, Zhimin; Zourelias, Lee; Perez-Riveros, Paola; Edwards, Paul C; Machen, Laurie; Passineau, Michael J

    2014-01-01

    In this study, we compared gene transfer efficiency and host response to ultrasound-assisted, nonviral gene transfer with a conventional plasmid and a minicircle vector in the submandibular salivary glands of mice. Initially, we looked at gene transfer efficiency with equimolar amounts of the plasmid and minicircle vectors, corroborating an earlier report showing that minicircle is more efficient in the context of a physical method of gene transfer. We then sought to characterize the physiological response of the salivary gland to exogenous gene transfer using global proteomic profiling. Somewhat surprisingly, we found that sonoporation alone, without a gene transfer vector present, had virtually no effect on the salivary gland proteome. However, when a plasmid vector was used, we observed profound perturbations of the salivary gland proteome that compared in magnitude to that seen in a previous report after high doses of adeno-associated virus. Finally, we found that gene transfer with a minicircle induces only minor proteomic alterations that were similar to sonoporation alone. Using mass spectrometry, we assigned protein IDs to 218 gel spots that differed between plasmid and minicircle. Bioinformatic analysis of these proteins demonstrated convergence on 68 known protein interaction pathways, most notably those associated with innate immunity, cellular stress, and morphogenesis. PMID:25414909

  10. Horizontal Gene Transfer of Pectinases from Bacteria Preceded the Diversification of Stick and Leaf Insects

    PubMed Central

    Shelomi, Matan; Danchin, Etienne G. J.; Heckel, David; Wipfler, Benjamin; Bradler, Sven; Zhou, Xin; Pauchet, Yannick

    2016-01-01

    Genes acquired by horizontal transfer are increasingly being found in animal genomes. Understanding their origin and evolution requires knowledge about the phylogenetic relationships from both source and recipient organisms. We used RNASeq data and respective assembled transcript libraries to trace the evolutionary history of polygalacturonase (pectinase) genes in stick insects (Phasmatodea). By mapping the distribution of pectinase genes on a Polyneoptera phylogeny, we identified the transfer of pectinase genes from known phasmatodean gut microbes into the genome of an early euphasmatodean ancestor that took place between 60 and 100 million years ago. This transfer preceded the rapid diversification of the suborder, enabling symbiont-free pectinase production that would increase the insects’ digestive efficiency and reduce dependence on microbes. Bacteria-to-insect gene transfer was thought to be uncommon, however the increasing availability of large-scale genomic data may change this prevailing notion. PMID:27210832

  11. Horizontal Gene Transfer of Pectinases from Bacteria Preceded the Diversification of Stick and Leaf Insects.

    PubMed

    Shelomi, Matan; Danchin, Etienne G J; Heckel, David; Wipfler, Benjamin; Bradler, Sven; Zhou, Xin; Pauchet, Yannick

    2016-01-01

    Genes acquired by horizontal transfer are increasingly being found in animal genomes. Understanding their origin and evolution requires knowledge about the phylogenetic relationships from both source and recipient organisms. We used RNASeq data and respective assembled transcript libraries to trace the evolutionary history of polygalacturonase (pectinase) genes in stick insects (Phasmatodea). By mapping the distribution of pectinase genes on a Polyneoptera phylogeny, we identified the transfer of pectinase genes from known phasmatodean gut microbes into the genome of an early euphasmatodean ancestor that took place between 60 and 100 million years ago. This transfer preceded the rapid diversification of the suborder, enabling symbiont-free pectinase production that would increase the insects' digestive efficiency and reduce dependence on microbes. Bacteria-to-insect gene transfer was thought to be uncommon, however the increasing availability of large-scale genomic data may change this prevailing notion. PMID:27210832

  12. Genes under weaker stabilizing selection increase network evolvability and rapid regulatory adaptation to an environmental shift.

    PubMed

    Laarits, T; Bordalo, P; Lemos, B

    2016-08-01

    Regulatory networks play a central role in the modulation of gene expression, the control of cellular differentiation, and the emergence of complex phenotypes. Regulatory networks could constrain or facilitate evolutionary adaptation in gene expression levels. Here, we model the adaptation of regulatory networks and gene expression levels to a shift in the environment that alters the optimal expression level of a single gene. Our analyses show signatures of natural selection on regulatory networks that both constrain and facilitate rapid evolution of gene expression level towards new optima. The analyses are interpreted from the standpoint of neutral expectations and illustrate the challenge to making inferences about network adaptation. Furthermore, we examine the consequence of variable stabilizing selection across genes on the strength and direction of interactions in regulatory networks and in their subsequent adaptation. We observe that directional selection on a highly constrained gene previously under strong stabilizing selection was more efficient when the gene was embedded within a network of partners under relaxed stabilizing selection pressure. The observation leads to the expectation that evolutionarily resilient regulatory networks will contain optimal ratios of genes whose expression is under weak and strong stabilizing selection. Altogether, our results suggest that the variable strengths of stabilizing selection across genes within regulatory networks might itself contribute to the long-term adaptation of complex phenotypes. PMID:27213992

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

    SciTech Connect

    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. Proton transfer to flavin stabilizes the signaling state of the blue light receptor plant cryptochrome.

    PubMed

    Hense, Anika; Herman, Elena; Oldemeyer, Sabine; Kottke, Tilman

    2015-01-16

    Plant cryptochromes regulate the circadian rhythm, flowering time, and photomorphogenesis in higher plants as responses to blue light. In the dark, these photoreceptors bind oxidized FAD in the photolyase homology region (PHR). Upon blue light absorption, FAD is converted to the neutral radical state, the likely signaling state, by electron transfer via a conserved tryptophan triad and proton transfer from a nearby aspartic acid. Here we demonstrate, by infrared and time-resolved UV-visible spectroscopy on the PHR domain, that replacement of the aspartic acid Asp-396 with cysteine prevents proton transfer. The lifetime of the radical is decreased by 6 orders of magnitude. This short lifetime does not permit to drive conformational changes in the C-terminal extension that have been associated with signal transduction. Only in the presence of ATP do both the wild type and mutant form a long-lived radical state. However, in the mutant, an anion radical is formed instead of the neutral radical, as found previously in animal type I cryptochromes. Infrared spectroscopic experiments demonstrate that the light-induced conformational changes of the PHR domain are conserved in the mutant despite the lack of proton transfer. These changes are not detected in the photoreduction of the non-photosensory d-amino acid oxidase to the anion radical. In conclusion, formation of the anion radical is sufficient to generate a protein response in plant cryptochromes. Moreover, the intrinsic proton transfer is required for stabilization of the signaling state in the absence of ATP. PMID:25471375

  15. Proton Transfer to Flavin Stabilizes the Signaling State of the Blue Light Receptor Plant Cryptochrome*

    PubMed Central

    Hense, Anika; Herman, Elena; Oldemeyer, Sabine; Kottke, Tilman

    2015-01-01

    Plant cryptochromes regulate the circadian rhythm, flowering time, and photomorphogenesis in higher plants as responses to blue light. In the dark, these photoreceptors bind oxidized FAD in the photolyase homology region (PHR). Upon blue light absorption, FAD is converted to the neutral radical state, the likely signaling state, by electron transfer via a conserved tryptophan triad and proton transfer from a nearby aspartic acid. Here we demonstrate, by infrared and time-resolved UV-visible spectroscopy on the PHR domain, that replacement of the aspartic acid Asp-396 with cysteine prevents proton transfer. The lifetime of the radical is decreased by 6 orders of magnitude. This short lifetime does not permit to drive conformational changes in the C-terminal extension that have been associated with signal transduction. Only in the presence of ATP do both the wild type and mutant form a long-lived radical state. However, in the mutant, an anion radical is formed instead of the neutral radical, as found previously in animal type I cryptochromes. Infrared spectroscopic experiments demonstrate that the light-induced conformational changes of the PHR domain are conserved in the mutant despite the lack of proton transfer. These changes are not detected in the photoreduction of the non-photosensory d-amino acid oxidase to the anion radical. In conclusion, formation of the anion radical is sufficient to generate a protein response in plant cryptochromes. Moreover, the intrinsic proton transfer is required for stabilization of the signaling state in the absence of ATP. PMID:25471375

  16. Role of horizontal gene transfer in the evolution of photosynthetic eukaryotes and their plastids.

    PubMed

    Keeling, Patrick J

    2009-01-01

    Plastids are the organelles derived from a cyanobacterium through endosymbiosis. Unlike mitochondria, plastids are not found in all eukaryotes, but their evolution has an added layer of complexity since plastids have moved between eukaryotic lineages by secondary and tertiary endosymbiotic events. This complex history, together with the genetic integration between plastids and their host, has led to many opportunities for gene flow between phylogenetically distinct lineages. Some intracellular transfers do not lead to a protein functioning in a new environment, but many others do and the protein makeup of many plastids appears to have been influenced by exogenous sources as well. Here, different evolutionary sources and cellular destinations of gene flow that has affected the plastid lineage are reviewed. Most horizontal gene transfer (HGT) affecting the modern plastid has taken place via the host nucleus, in the form of genes for plastid-targeted proteins. The impact of this varies greatly from lineage to lineage, but in some cases such transfers can be as high as one fifth of analyzed genes. More rarely, genes have also been transferred to the plastid genome itself, and plastid genes have also been transferred to other non-plant, non-algal lineages. Overall, the proteome of many plastids has emerged as a mosaic of proteins from many sources, some from within the same cell (e.g., cytosolic genes or genes left over from the replacement of an earlier plastid), some from the plastid of other algal lineages, and some from completely unrelated sources. PMID:19271204

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

    PubMed

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

    2009-08-01

    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

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

    PubMed Central

    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

  19. Horizontally transferred genes in the genome of Pacific white shrimp, Litopenaeus vannamei

    PubMed Central

    2013-01-01

    Background In recent years, as the development of next-generation sequencing technology, a growing number of genes have been reported as being horizontally transferred from prokaryotes to eukaryotes, most of them involving arthropods. As a member of the phylum Arthropoda, the Pacific white shrimp Litopenaeus vannamei has to adapt to the complex water environments with various symbiotic or parasitic microorganisms, which provide a platform for horizontal gene transfer (HGT). Results In this study, we analyzed the genome-wide HGT events in L. vannamei. Through homology search and phylogenetic analysis, followed by experimental PCR confirmation, 14 genes with HGT event were identified: 12 of them were transferred from bacteria and two from fungi. Structure analysis of these genes showed that the introns of the two fungi-originated genes were substituted by shrimp DNA fragment, two genes transferred from bacteria had shrimp specific introns inserted in them. Furthermore, around other three bacteria-originated genes, there were three large DNA segments inserted into the shrimp genome. One segment was a transposon that fully transferred, and the other two segments contained only coding regions of bacteria. Functional prediction of these 14 genes showed that 6 of them might be related to energy metabolism, and 4 others related to defense of the organism. Conclusions HGT events from bacteria or fungi were happened in the genome of L. vannamei, and these horizontally transferred genes can be transcribed in shrimp. This is the first time to report the existence of horizontally transferred genes in shrimp. Importantly, most of these genes are exposed to a negative selection pressure and appeared to be functional. PMID:23914989

  20. Ultrasound -Assisted Gene Transfer to Adipose Tissue-Derived Stem/Progenitor Cells (ASCs)

    NASA Astrophysics Data System (ADS)

    Miyamoto, Yoshitaka; Ueno, Hitomi; Hokari, Rei; Yuan, Wenji; Kuno, Shuichi; Kakimoto, Takashi; Enosawa, Shin; Negishi, Yoichi; Yoshinaka, Kiyoshi; Matsumoto, Yoichiro; Chiba, Toshio; Hayashi, Shuji

    2011-09-01

    In recent years, multilineage adipose tissue-derived stem cells (ASCs) have become increasingly attractive as a promising source for cell transplantation and regenerative medicine. Particular interest has been expressed in the potential to make tissue stem cells, such as ASCs and marrow stromal cells (MSCs), differentiate by gene transfection. Gene transfection using highly efficient viral vectors such as adeno- and sendai viruses have been developed for this purpose. Sonoporation, or ultrasound (US)-assisted gene transfer, is an alternative gene manipulation technique which employs the creation of a jet stream by ultrasonic microbubble cavitation. Sonoporation using non-viral vectors is expected to be a much safer, although less efficient, tool for prospective clinical gene therapy. In this report, we assessed the efficacy of the sonoporation technique for gene transfer to ASCs. We isolated and cultured adipocyets from mouse adipose tissue. ASCs that have the potential to differentiate with transformation into adipocytes or osteoblasts were obtained. Using the US-assisted system, plasmid DNA containing beta-galactosidase (beta-Gal) and green fluorescent protein (GFP) genes were transferred to the ASCs. For this purpose, a Sonopore 4000 (NEPAGENE Co.) and a Sonazoid (Daiichi Sankyo Co.) instrument were used in combination. ASCs were subjected to US (3.1 MHz, 50% duty cycle, burst rate 2.0 Hz, intensity 1.2 W/cm2, exposure time 30 sec). We observed that the gene was more efficiently transferred with increased concentrations of plasmid DNA (5-150 μg/mL). However, further optimization of the US parameters is required, as the gene transfer efficiency was still relatively low. In conclusion, we herein demonstrate that a gene can be transferred to ASCs using our US-assisted system. In regenerative medicine, this system might resolve the current issues surrounding the use of viral vectors for gene transfer.

  1. Nanoalumina promotes the horizontal transfer of multiresistance genes mediated by plasmids across genera

    PubMed Central

    Qiu, Zhigang; Yu, Yunmei; Chen, Zhaoli; Jin, Min; Yang, Dong; Zhao, Zuguo; Wang, Jingfeng; Shen, Zhiqiang; Wang, Xinwei; Qian, Di; Huang, Aihua; Zhang, Buchang; Li, Jun-Wen

    2012-01-01

    Antibiotic resistance is a worldwide public health concern. Conjugative transfer between closely related strains or species of bacteria is an important method for the horizontal transfer of multidrug-resistance genes. The extent to which nanomaterials are able to cause an increase in antibiotic resistance by the regulation of the conjugative transfer of antibiotic-resistance genes in bacteria, especially across genera, is still unknown. Here we show that nanomaterials in water can significantly promote the horizontal conjugative transfer of multidrug-resistance genes mediated by the RP4, RK2, and pCF10 plasmids. Nanoalumina can promote the conjugative transfer of the RP4 plasmid from Escherichia coli to Salmonella spp. by up to 200-fold compared with untreated cells. We also explored the mechanisms behind this phenomenon and demonstrate that nanoalumina is able to induce oxidative stress, damage bacterial cell membranes, enhance the expression of mating pair formation genes and DNA transfer and replication genes, and depress the expression of global regulatory genes that regulate the conjugative transfer of RP4. These findings are important in assessing the risk of nanomaterials to the environment, particularly from water and wastewater treatment systems, and in the estimation of the effect of manufacture and use of nanomaterials on the environment. PMID:22411796

  2. Lysogen stability is determined by the frequency of activity bursts from the fate-determining gene

    PubMed Central

    Zong, Chenghang; So, Lok-hang; Sepúlveda, Leonardo A; Skinner, Samuel O; Golding, Ido

    2010-01-01

    The ability of living cells to maintain an inheritable memory of their gene-expression state is key to cellular differentiation. Bacterial lysogeny serves as a simple paradigm for long-term cellular memory. In this study, we address the following question: in the absence of external perturbation, how long will a cell stay in the lysogenic state before spontaneously switching away from that state? We show by direct measurement that lysogen stability exhibits a simple exponential dependence on the frequency of activity bursts from the fate-determining gene, cI. We quantify these gene-activity bursts using single-molecule-resolution mRNA measurements in individual cells, analyzed using a stochastic mathematical model of the gene-network kinetics. The quantitative relation between stability and gene activity is independent of the fine details of gene regulation, suggesting that a quantitative prediction of cell-state stability may also be possible in more complex systems. PMID:21119634

  3. The Replication Checkpoint Protects Fork Stability by Releasing Transcribed Genes from Nuclear Pores

    PubMed Central

    Bermejo, Rodrigo; Capra, Thelma; Jossen, Rachel; Colosio, Arianna; Frattini, Camilla; Carotenuto, Walter; Cocito, Andrea; Doksani, Ylli; Klein, Hannah; Gómez-González, Belén; Aguilera, Andrés; Katou, Yuki; Shirahige, Katsuhiko; Foiani, Marco

    2011-01-01

    Summary Transcription hinders replication fork progression and stability, and the Mec1/ATR checkpoint protects fork integrity. Examining checkpoint-dependent mechanisms controlling fork stability, we find that fork reversal and dormant origin firing due to checkpoint defects are rescued in checkpoint mutants lacking THO, TREX-2, or inner-basket nucleoporins. Gene gating tethers transcribed genes to the nuclear periphery and is counteracted by checkpoint kinases through phosphorylation of nucleoporins such as Mlp1. Checkpoint mutants fail to detach transcribed genes from nuclear pores, thus generating topological impediments for incoming forks. Releasing this topological complexity by introducing a double-strand break between a fork and a transcribed unit prevents fork collapse. Mlp1 mutants mimicking constitutive checkpoint-dependent phosphorylation also alleviate checkpoint defects. We propose that the checkpoint assists fork progression and stability at transcribed genes by phosphorylating key nucleoporins and counteracting gene gating, thus neutralizing the topological tension generated at nuclear pore gated genes. PMID:21784245

  4. Lysogen stability is determined by the frequency of activity bursts from the fate-determining gene.

    PubMed

    Zong, Chenghang; So, Lok-hang; Sepúlveda, Leonardo A; Skinner, Samuel O; Golding, Ido

    2010-11-30

    The ability of living cells to maintain an inheritable memory of their gene-expression state is key to cellular differentiation. Bacterial lysogeny serves as a simple paradigm for long-term cellular memory. In this study, we address the following question: in the absence of external perturbation, how long will a cell stay in the lysogenic state before spontaneously switching away from that state? We show by direct measurement that lysogen stability exhibits a simple exponential dependence on the frequency of activity bursts from the fate-determining gene, cI. We quantify these gene-activity bursts using single-molecule-resolution mRNA measurements in individual cells, analyzed using a stochastic mathematical model of the gene-network kinetics. The quantitative relation between stability and gene activity is independent of the fine details of gene regulation, suggesting that a quantitative prediction of cell-state stability may also be possible in more complex systems. PMID:21119634

  5. Gene transfer into experimental brain tumors mediated by adenovirus, herpes simplex virus, and retrovirus vectors.

    PubMed

    Boviatsis, E J; Chase, M; Wei, M X; Tamiya, T; Hurford, R K; Kowall, N W; Tepper, R I; Breakefield, X O; Chiocca, E A

    1994-02-01

    Three vectors derived from retrovirus, herpes simplex virus type 1 (HSV), and adenovirus were compared in cultured rat 9L gliosarcoma cells for gene transfer efficiency and in a 9L rat brain tumor model for histologic pattern and distribution of foreign gene delivery, as well as for associated tumor necrosis and inflammation. At a multiplicity of infection of 1, in vitro transfer of a foreign gene (lacZ from Escherichia coli) into cells was more efficient with either the replication-defective retrovirus vector or the replication-conditional thymidine kinase (TK)-deficient HSV vector than with the replication-defective adenovirus vector. In vivo, stereotactic injections of each vector into rat brain tumors revealed three main histopathologic findings: (i) retrovirus and HSV vector-mediated gene transfer was relatively selective for cells within the tumor, whereas adenovirus vector-mediated gene transfer occurred into several types of endogenous neural cells, as well as into cells within the tumor; (ii) gene transfer to multiple infiltrating tumor deposits without apparent gene transfer to intervening normal brain tissue occurred uniquely in one animal inoculated with the HSV vector, and (iii) extensive necrosis and selective inflammation in the tumor were evident with the HSV vector, whereas there was minimal evidence of tumor necrosis and inflammation with either the retrovirus or adenovirus vectors. PMID:8186298

  6. A linear stability analysis for nonlinear, grey, thermal radiative transfer problems

    SciTech Connect

    Wollaber, Allan B.; Larsen, Edward W.

    2011-02-20

    We present a new linear stability analysis of three time discretizations and Monte Carlo interpretations of the nonlinear, grey thermal radiative transfer (TRT) equations: the widely used 'Implicit Monte Carlo' (IMC) equations, the Carter Forest (CF) equations, and the Ahrens-Larsen or 'Semi-Analog Monte Carlo' (SMC) equations. Using a spatial Fourier analysis of the 1-D Implicit Monte Carlo (IMC) equations that are linearized about an equilibrium solution, we show that the IMC equations are unconditionally stable (undamped perturbations do not exist) if {alpha}, the IMC time-discretization parameter, satisfies 0.5 < {alpha} {<=} 1. This is consistent with conventional wisdom. However, we also show that for sufficiently large time steps, unphysical damped oscillations can exist that correspond to the lowest-frequency Fourier modes. After numerically confirming this result, we develop a method to assess the stability of any time discretization of the 0-D, nonlinear, grey, thermal radiative transfer problem. Subsequent analyses of the CF and SMC methods then demonstrate that the CF method is unconditionally stable and monotonic, but the SMC method is conditionally stable and permits unphysical oscillatory solutions that can prevent it from reaching equilibrium. This stability theory provides new conditions on the time step to guarantee monotonicity of the IMC solution, although they are likely too conservative to be used in practice. Theoretical predictions are tested and confirmed with numerical experiments.

  7. Indirect Fitness Benefits Enable the Spread of Host Genes Promoting Costly Transfer of Beneficial Plasmids

    PubMed Central

    Dimitriu, Tatiana; Misevic, Dusan; Lotton, Chantal; Brown, Sam P.; Lindner, Ariel B.; Taddei, François

    2016-01-01

    Bacterial genes that confer crucial phenotypes, such as antibiotic resistance, can spread horizontally by residing on mobile genetic elements (MGEs). Although many mobile genes provide strong benefits to their hosts, the fitness consequences of the process of transfer itself are less clear. In previous studies, transfer has been interpreted as a parasitic trait of the MGEs because of its costs to the host but also as a trait benefiting host populations through the sharing of a common gene pool. Here, we show that costly donation is an altruistic act when it spreads beneficial MGEs favoured when it increases the inclusive fitness of donor ability alleles. We show mathematically that donor ability can be selected when relatedness at the locus modulating transfer is sufficiently high between donor and recipients, ensuring high frequency of transfer between cells sharing donor alleles. We further experimentally demonstrate that either population structure or discrimination in transfer can increase relatedness to a level selecting for chromosomal transfer alleles. Both mechanisms are likely to occur in natural environments. The simple process of strong dilution can create sufficient population structure to select for donor ability. Another mechanism observed in natural isolates, discrimination in transfer, can emerge through coselection of transfer and discrimination alleles. Our work shows that horizontal gene transfer in bacteria can be promoted by bacterial hosts themselves and not only by MGEs. In the longer term, the success of cells bearing beneficial MGEs combined with biased transfer leads to an association between high donor ability, discrimination, and mobile beneficial genes. However, in conditions that do not select for altruism, host bacteria promoting transfer are outcompeted by hosts with lower transfer rate, an aspect that could be relevant in the fight against the spread of antibiotic resistance. PMID:27270455

  8. Biomaterial-Mediated Retroviral Gene Transfer Using Self-Assembled Monolayers

    PubMed Central

    Gersbach, Charles A.; Coyer, Sean R.; Le Doux, Joseph M.; García, Andrés J.

    2007-01-01

    Biomaterial-mediated gene delivery has recently emerged as a promising alternative to conventional gene transfer technologies that focus on direct delivery of viral vectors or DNA-polymer/matrix complexes. However, biomaterial-based strategies have primarily targeted transient gene expression vehicles, including plasmid DNA and adenovirus particles. This study expands on this work by characterizing biomaterial properties conducive to the surface immobilization of retroviral particles and subsequent transduction of mammalian cells at the cell-material interface. Self-assembled monolayers (SAMs) of functionally-terminated alkanethiols on gold were used to establish biomaterial surfaces of defined chemical composition. Gene transfer was observed to be greater than 90% on NH2-terminated surfaces, approximately 50% on COOH-functionalized surfaces, and undetectable on CH3-terminated SAMs, similar to controls of tissue culture-treated polystyrene. Gene delivery via the NH2-SAM was further characterized as a function of coating time, virus concentration, and cell seeding density. Finally, SAM-mediated gene delivery was comparable to fibronectin- and poly-L-lysine-based methods for gene transfer. This work is significant to establishing safe and effective gene therapy strategies, developing efficient methods for gene delivery, and supporting recent progress in the field of biomaterial-mediated gene transfer. PMID:17698189

  9. Stabilization of gene expression and cell morphology after explant recycling during fin explant culture in goldfish

    SciTech Connect

    Chenais, Nathalie; Lareyre, Jean-Jacques; Le Bail, Pierre-Yves; Labbe, Catherine

    2015-07-01

    The development of fin primary cell cultures for in vitro cellular and physiological studies is hampered by slow cell outgrowth, low proliferation rate, poor viability, and sparse cell characterization. Here, we investigated whether the recycling of fresh explants after a first conventional culture could improve physiological stability and sustainability of the culture. The recycled explants were able to give a supplementary cell culture showing faster outgrowth, cleaner cell layers and higher net cell production. The cells exhibited a highly stabilized profile for marker gene expression including a low cytokeratin 49 (epithelial marker) and a high collagen 1a1 (mesenchymal marker) expression. Added to the cell spindle-shaped morphology, motility behavior, and actin organization, this suggests that the cells bore stable mesenchymal characteristics. This contrast with the time-evolving expression pattern observed in the control fresh explants during the first 2 weeks of culture: a sharp decrease in cytokeratin 49 expression was concomitant with a gradual increase in col1a1. We surmise that such loss of epithelial features for the benefit of mesenchymal ones was triggered by an epithelial to mesenchymal transition (EMT) process or by way of a progressive population replacement process. Overall, our findings provide a comprehensive characterization of this new primary culture model bearing mesenchymal features and whose stability over culture time makes those cells good candidates for cell reprogramming prior to nuclear transfer, in a context of fish genome preservation. - Highlights: • Recycled fin explants outgrow cells bearing stable mesenchymal traits. • Cell production and quality is enhanced in the recycled explant culture system. • Fresh fin primary culture is highly variable and loose epithelial traits over time.

  10. An ancient horizontal gene transfer between mosquito and the endosymbiotic bacterium Wolbachia pipientis.

    PubMed

    Woolfit, Megan; Iturbe-Ormaetxe, Iñaki; McGraw, Elizabeth A; O'Neill, Scott L

    2009-02-01

    The extent and biological relevance of horizontal gene transfer (HGT) in eukaryotic evolution remain highly controversial. Recent studies have demonstrated frequent and large-scale HGT from endosymbiotic bacteria to their hosts, but the great majority of these transferred genes rapidly become nonfunctional in the recipient genome. Here, we investigate an ancient HGT between a host metazoan and an endosymbiotic bacterium, Wolbachia pipientis. The transferred gene has so far been found only in mosquitoes and Wolbachia. In mosquitoes, it is a member of a gene family encoding candidate receptors required for malaria sporozoite invasion of the mosquito salivary gland. The gene copy in Wolbachia has substantially diverged in sequence from the mosquito homolog, is evolving under purifying selection, and is expressed, suggesting that this gene is also functional in the bacterial genome. Several lines of evidence indicate that the gene may have been transferred from eukaryotic host to bacterial endosymbiont. Regardless of the direction of transfer, however, these results demonstrate that interdomain HGT may give rise to functional, persistent, and possibly evolutionarily significant new genes. PMID:18988686

  11. SAFETY AND EFFICIENCY OF MODULATING PARACELLULAR PERMEABILITY TO ENHANCE AIRWAY EPITHELIAL GENE TRANSFER IN VIVO

    EPA Science Inventory


    ABSTRACT

    We evaluated the safety of agents that enhance gene transfer by modulating paracellular permeability. Lactate dehydrogenase (LDH) and cytokine release were measured in polarized primary human airway epithelial (HAE) cells after luminal application of vehicle, ...

  12. An XMRV Derived Retroviral Vector as a Tool for Gene Transfer

    PubMed Central

    2011-01-01

    Background Retroviral vectors are widely used tools for gene delivery and gene therapy. They are useful for gene expression studies and genetic manipulation in vitro and in vivo. Many retroviral vectors are derived from the mouse gammaretrovirus, murine leukemia virus (MLV). These vectors have been widely used in gene therapy clinical trials. XMRV, initially found in prostate cancer tissue, was the first human gammaretrovirus described. Findings We developed a new retroviral vector based on XMRV called pXC. It was developed for gene transfer to human cells and is produced by transient cotransfection of LNCaP cells with pXC and XMRV-packaging plasmids. Conclusions We demonstrated that pXC mediates expression of inserted transgenes in cell lines. This new vector will be a useful tool for gene transfer in human and non-human cell lines, including gene therapy studies. PMID:21651801

  13. Evolutionary Advantage Conferred by an Eukaryote-to-Eukaryote Gene Transfer Event in Wine Yeasts

    PubMed Central

    Marsit, Souhir; Mena, Adriana; Bigey, Frédéric; Sauvage, François-Xavier; Couloux, Arnaud; Guy, Julie; Legras, Jean-Luc; Barrio, Eladio; Dequin, Sylvie; Galeote, Virginie

    2015-01-01

    Although an increasing number of horizontal gene transfers have been reported in eukaryotes, experimental evidence for their adaptive value is lacking. Here, we report the recent transfer of a 158-kb genomic region between Torulaspora microellipsoides and Saccharomyces cerevisiae wine yeasts or closely related strains. This genomic region has undergone several rearrangements in S. cerevisiae strains, including gene loss and gene conversion between two tandemly duplicated FOT genes encoding oligopeptide transporters. We show that FOT genes confer a strong competitive advantage during grape must fermentation by increasing the number and diversity of oligopeptides that yeast can utilize as a source of nitrogen, thereby improving biomass formation, fermentation efficiency, and cell viability. Thus, the acquisition of FOT genes has favored yeast adaptation to the nitrogen-limited wine fermentation environment. This finding indicates that anthropic environments offer substantial ecological opportunity for evolutionary diversification through gene exchange between distant yeast species. PMID:25750179

  14. The Or gene enhances carotenoid accumulation and stability during post-harvest storage of potato tubers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Provitamin A carotenoids in staple crops are not very stable during storage and their loss compromises nutritional quality. To elucidate the fundamental mechanisms underlying carotenoid accumulation and stability, we investigated transgenic potato tubers that express the cauliflower Orange (Or) gene...

  15. Evaluation of Available Transfer Capability Using Transient Stability Constrained Line Flows

    NASA Astrophysics Data System (ADS)

    Uzoechi, Lazarus Okechukwu; Mahajan, Satish M.

    2014-01-01

    This paper presents a methodology to evaluate transient stability constrained available transfer capability (ATC). A linear and fast line flow-based (LFB) method was adopted to optimize the ATC values. This enabled the direct determination of the system source-sink locations. This paper formulated different market transactions considering bilateral and multilateral impacts in the stability constrained ATC. The proposed method was demonstrated on the WECC 9-bus and IEEE 39-bus systems. The critical energy performance index (CEPI) enabled the direct identification of candidates for contingency screening based on ranking. This index helped to reduce the list of credible contingencies for ATC evaluation and, therefore, the computation time. The results of the proposed ATC method are consistent with the literature and can be deployed for fast assessment of the impact of transactions in an electric power system.

  16. STABILITY EVALUATION OF METAL CASK ATTACHED TO A TRANSFER PALLET DURING LONG-PERIOD SEISMIC MOTIONS

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Shohei; Shirai, Koji; Kanazawa, Kenji

    Rocking behavior of unfixed body is affected by center of mass, material coefficient of restitution and so on. 2/5 scale metal cask model considering these parameter was used for seismic test to evaluate stability of grounding metal cask attached to a transfer pallet under the influence of long-period earthquake motion. The newest knowledge from seismic test indicates seismic motion with high velocity over 100 kine not always cause the raise of response velocity of metal cask because of energy consumption by cask sliding and impact deformation of concrete. And new estimation method (called "Window energy spectrum method") of earthquake response spectrum gives suitable evaluation of response energy.

  17. Assessment of ICU readmission risk with the Stability and Workload Index for Transfer score*

    PubMed Central

    Oakes, Daiane Ferreira; Borges, Ingrid Nemitz Krás; Forgiarini, Luiz Alberto; Rieder, Marcelo de Mello

    2014-01-01

    Patient discharge from the ICU is indicated on the basis of clinical evidence and the result of strategies aimed at improving health care. Nevertheless, some patients might be discharged too early. We attempted to identify risk factors for unplanned ICU readmission, using a score for risk assessment, designated the Stability and Workload Index for Transfer (SWIFT) score. We evaluated 100 patients discharged from an ICU and found that the SWIFT score can be used as a tool for improving the assessment of ICU patients and the appropriateness of ICU discharge, thus preventing readmission. PMID:24626273

  18. Quantitative analysis of recombination between YFP and CFP genes of FRET biosensors introduced by lentiviral or retroviral gene transfer.

    PubMed

    Komatsubara, Akira T; Matsuda, Michiyuki; Aoki, Kazuhiro

    2015-01-01

    Biosensors based on the principle of Förster (or fluorescence) resonance energy transfer (FRET) have been developed to visualize spatio-temporal dynamics of signalling molecules in living cells. Many of them adopt a backbone of intramolecular FRET biosensor with a cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) as donor and acceptor, respectively. However, there remains the difficulty of establishing cells stably expressing FRET biosensors with a YFP and CFP pair by lentiviral or retroviral gene transfer, due to the high incidence of recombination between YFP and CFP genes. To address this, we examined the effects of codon-diversification of YFP on the recombination of FRET biosensors introduced by lentivirus or retrovirus. The YFP gene that was fully codon-optimized to E.coli evaded the recombination in lentiviral or retroviral gene transfer, but the partially codon-diversified YFP did not. Further, the length of spacer between YFP and CFP genes clearly affected recombination efficiency, suggesting that the intramolecular template switching occurred in the reverse-transcription process. The simple mathematical model reproduced the experimental data sufficiently, yielding a recombination rate of 0.002-0.005 per base. Together, these results show that the codon-diversified YFP is a useful tool for expressing FRET biosensors by lentiviral or retroviral gene transfer. PMID:26290434

  19. Microarray analysis of relative gene expression stability for selection of internal reference genes in the rhesus macaque brain

    PubMed Central

    2010-01-01

    Background Normalization of gene expression data refers to the comparison of expression values using reference standards that are consistent across all conditions of an experiment. In PCR studies, genes designated as "housekeeping genes" have been used as internal reference genes under the assumption that their expression is stable and independent of experimental conditions. However, verification of this assumption is rarely performed. Here we assess the use of gene microarray analysis to facilitate selection of internal reference sequences with higher expression stability across experimental conditions than can be expected using traditional selection methods. We recently demonstrated that relative gene expression from qRT-PCR data normalized using GAPDH, ALG9 and RPL13A expression values mirrored relative expression using quantile normalization in Robust Multichip Analysis (RMA) on the Affymetrix® GeneChip® rhesus Macaque Genome Array. Having shown that qRT-PCR and Affymetrix® GeneChip® data from the same hormone replacement therapy (HRT) study yielded concordant results, we used quantile-normalized gene microarray data to identify the most stably expressed among probe sets for prospective internal reference genes across three brain regions from the HRT study and an additional study of normally menstruating rhesus macaques (cycle study). Gene selection was limited to 575 previously published human "housekeeping" genes. Twelve animals were used per study, and three brain regions were analyzed from each animal. Gene expression stabilities were determined using geNorm, NormFinder and BestKeeper software packages. Results Sequences co-annotated for ribosomal protein S27a (RPS27A), and ubiquitin were among the most stably expressed under all conditions and selection criteria used for both studies. Higher annotation quality on the human GeneChip® facilitated more targeted analysis than could be accomplished using the rhesus GeneChip®. In the cycle study, multiple

  20. Stability and toxicity of empty or gene-loaded lipopolysaccharide-amine nanopolymersomes

    PubMed Central

    Wang, Qinmei; Chen, Ying; Wang, Lichun; Zhang, Xinchun; Huang, Hongzhang; Teng, Wei

    2015-01-01

    Successful in vivo gene delivery mediated by nonviral vectors requires efficient extracellular and intracellular gene delivery, but few studies have given attention to the former. That is why numerous gene delivery systems have succeeded in vitro, while the expected clinical success has not come about. To realize efficient extracellular gene delivery, the stability of vectors and/or their complexes with genes in body fluids is first required, which prevents loaded genes from premature unloading and degradation. Furthermore, the storage stability of vectors under common conditions is important for their widespread applications. Lipopolysaccharide-amine nanopolymersomes (NPs), a gene vector developed by our group recently, have higher than 95% in vitro transfection efficiency in mesenchymal stem cells when delivering pEGFP, and induce significant angiogenesis in zebrafish when delivering plasmid encoding vascular endothelial growth factor deoxyribonucleic acid (pVEGF). To reveal their extracellular delivery ability and storage stability, in this study their stability in various simulant physiological environments and storage conditions was systematically studied by monitoring their changes in disassembly, size, zeta potential, and transfection efficiency. Additionally, damage to the mitochondria of mesenchymal stem cells was evaluated. Results show that NPs and plasmid deoxyribonucleic acid (pDNA)-loaded NPs (pNPs) have acceptable stability against dilution, anions, salts, pH, enzyme, and serum, presumably assuring their efficient extracellular delivery in vivo. Moreover, both the lyophilized NPs at room temperature and NP/pNP solution at 4°C have high storage stability, and pNPs show low damage to the mitochondria. The acceptable stability of NPs combined with compatibility and efficient gene transfection highlight their huge potential in the clinic as a gene delivery vector. PMID:25609964

  1. Development of second- and third-generation bovine immunodeficiency virus-based gene transfer systems.

    PubMed

    Matukonis, Meghan; Li, Mengtao; Molina, Rene P; Paszkiet, Brian; Kaleko, Michael; Luo, Tianci

    2002-07-20

    Lentivirus-based gene transfer systems have demonstrated their utility in mediating gene transfer to dividing and nondividing cells both in vitro and in vivo. An early-generation gene transfer system developed from bovine immunodeficiency virus (BIV) has been described (Berkowitz et al., J. Virol. 2001;75:3371-3382). In this paper, we describe the development of second-generation (three-plasmid) and third-generation (four-plasmid) BIV-based systems. All accessory genes (vif, vpw, vpy, and tmx) and the regulatory gene tat were deleted or largely truncated from the packaging construct. Furthermore, we split the packaging function into two constructs by expressing Rev in a separate plasmid. Together with our minimal BIV transfer vector construct and a vesicular stomatitis virus G glycoprotein-expressing plasmid, the BIV vectors were generated. The vectors produced by the three- and four-plasmid systems had titers greater than 1 x 10(6) transducing units per milliliter and were fully functional as indicated by their ability to efficiently transduce both dividing and nondividing cells. These results suggest that the accessory genes vif, vpw, vpy, and tmx are dispensable for functional BIV vector development. The modifications made to the packaging constructs improve the safety profile of the vector system. Finally, BIV vectors provide an alternative to human immunodeficiency virus-based gene transfer systems. PMID:12162812

  2. Exploration of horizontal gene transfer between transplastomic tobacco and plant-associated bacteria.

    PubMed

    Demanèche, Sandrine; Monier, Jean-Michel; Dugat-Bony, Eric; Simonet, Pascal

    2011-10-01

    The likelihood of gene transfer from transgenic plants to bacteria is dependent on the transgene copy number and on the presence of homologous sequences for recombination. The large number of chloroplast genomes in a plant cell as well as the prokaryotic origin of the transgene may thus significantly increase the likelihood of gene transfer from transplastomic plants to bacteria. In order to assess the probability of such a transfer, bacterial isolates, screened for their ability to colonize decaying tobacco plant tissue and possessing DNA sequence similarity to the chloroplastic genes accD and rbcL flanking the transgene (aadA), were tested for their ability to take up extracellular DNA (broad host-range pBBR1MCS-3-derived plasmid, transplastomic plant DNA and PCR products containing the genes accD-aadA-rbcL) by natural or electrotransformation. The results showed that among the 16 bacterial isolates tested, six were able to accept foreign DNA and acquire the spectinomycin resistance conferred by the aadA gene on plasmid, but none of them managed to integrate transgenic DNA in their chromosome. Our results provide no indication that the theoretical gene transfer-enhancing properties of transplastomic plants cause horizontal gene transfer at rates above those found in other studies with nuclear transgenes. PMID:21564143

  3. Chloroplast-like transfer RNA genes expressed in wheat mitochondria.

    PubMed Central

    Joyce, P B; Gray, M W

    1989-01-01

    In the course of a systematic survey of wheat mitochondrial tRNA genes, we have sequenced chloroplast-like serine (trnS-GGA), phenylalanine (trnF-GAA) and cysteine (trnC-GCA) tRNA genes and their flanking regions. These genes are remnants of 'promiscuous' chloroplast DNA that has been incorporated into wheat mtDNA in the course of its evolution. Each gene differs by one or a few nucleotides from the authentic chloroplast homolog previously characterized in wheat or other plants, and each could potentially encode a functional tRNA whose secondary structure shows no deviations from the generalized model. To determine whether these chloroplast-like tRNA genes are actually expressed, wheat mitochondrial tRNAs were resolved by a series of polyacrylamide gel electrophoreses, after being specifically end-labeled in vitro by 3'-CCA addition mediated by wheat tRNA nucleotidyltransferase. Subsequent direct RNA sequence analysis identified prominent tRNA species corresponding to the mitochondrial and not the chloroplast trnS, trnF and trnC genes. This analysis also revealed chloroplast-like elongator methionine, asparagine and tryptophan tRNAs. Our results suggest that at least some chloroplast-like tRNA genes in wheat mtDNA are transcribed, with transcripts undergoing processing, post-transcriptional modification and 3'-CCA addition, to produce mature tRNAs that may participate in mitochondrial protein synthesis. Images PMID:2762145

  4. Lentiviral vector-mediated gene transfer and RNA silencing technology in neuronal dysfunctions.

    PubMed

    Dreyer, Jean-Luc

    2011-02-01

    Lentiviral-mediated gene transfer in vivo or in cultured mammalian neurons can be used to address a wide variety of biological questions, to design animals models for specific neurodegenerative pathologies, or to test potential therapeutic approaches in a variety of brain disorders. Lentiviruses can infect non-dividing cells, thereby allowing stable gene transfer in post-mitotic cells such as mature neurons. An important contribution has been the use of inducible vectors: the same animal can thus be used repeatedly in the doxycycline-on or -off state, providing a powerful mean for assessing the function of a gene candidate in a disorder within a specific neuronal circuit. Furthermore, lentivirus vectors provide a unique tool to integrate siRNA expression constructs with the aim to locally knockdown expression of a specific gene, enabling to assess the function of a gene in a very specific neuronal pathway. Lentiviral vector-mediated delivery of short hairpin RNA results in persistent knockdown of gene expression in the brain. Therefore, the use of lentiviruses for stable expression of siRNA in brain is a powerful aid to probe gene functions in vivo and for gene therapy of diseases of the central nervous system. In this chapter I review the applications of lentivirus-mediated gene transfer in the investigation of specific gene candidates involved in major brain disorders and neurodegenerative processes. Major applications have been in polyglutamine disorders, such as synucleinopathies and Parkinson's disease, or in investigating gene function in Huntington's disease, dystonia, or muscular dystrophy. Recently, lentivirus gene transfer has been an invaluable tool for evaluation of gene function in behavioral disorders such as drug addiction and attention-deficit hyperactivity disorder or in learning and cognition. PMID:20862616

  5. The effect of asymmetric heating on flow stability and heat transfer for flow in a vertical tube

    SciTech Connect

    Tappan, C.H.

    1987-11-01

    This study presents experimental results of combined free and forced convection heat transfer in a vertical tube with a circumferentially nonuniform constant wall heat flux. The effect of an asymmetric wall heat flux on flow stability and on the rate of heat transfer for water flowing downward in a vertical tube was investigated. Experimental results were used to develop two stability maps which identify various flow regimes, corresponding to different thermal and hydraulic conditions. Heat transfer coefficients were also determined. Experimental results in the present investigation were compared to those with uniform heating in horizontal and vertical tube flow situations discussed in the literature. 23 refs., 12 figs., 1 tab.

  6. Gene transfer into hematopoietic progenitor and stem cells: progress and problems.

    PubMed

    Dunbar, C E; Emmons, R V

    1994-11-01

    Gene transfer to hematopoietic cells for the purpose of "gene therapy" is a new and rapidly developing field with clinical trials in progress. A fundamental goal of research in this field is the incorporation of exogenous genes into the chromosomes of the most primitive hematopoietic progenitor cells--stem cells. Recombinantly engineered retroviral vectors are the best characterized and are currently the only vector type in clinical trials directed at the hematopoietic system. High efficiency gene transfer and expression in murine stem cells and their progeny is now routine, but in larger animal models such as dogs or primates and preliminary clinical trials, gene transfer has been less successful. Problems such as retroviral efficiency, gene expression, insertional mutagenesis and helper virus contamination are being addressed. A promising new vector, the adeno-associated virus (AAV), has shown promise and may allow production of high titer, stable, recombinant virions without helper contamination and with potentially better safety parameters. However, the technology for AAV gene transfer is currently underdeveloped, and issues related to the reproducible production of vectors must be addressed. Other non-viral vector systems are being explored, but little data are available on applications to hematopoietic cells. Better preclinical models are needed to study gene targeting and expression in human cells. An overview of recombinant retroviral and adeno-associated viral vector production, preclinical data and preliminary clinical data will be given, and problems needing to be addressed at all stages of development before broad clinical utility can be achieved will be discussed. PMID:7881358

  7. Evolutionary transfer of the chloroplast tufA gene to the nucleus.

    PubMed

    Baldauf, S L; Palmer, J D

    1990-03-15

    Evolutionary gene transfer is a basic corollary of the now widely accepted endosymbiotic theory, which proposes that mitochondria and chloroplasts originated from once free-living eubacteria. The small organellar chromosomes are remnants of larger bacterial genomes, with most endosymbiont genes having been either transferred to the nucleus soon after endosymbiosis or lost entirely, with some being functionally replaced by pre-existing nuclear genes. Several lines of evidence indicate that relocation of some organelle genes could have been more recent. These include the abundance of non-functional organelle sequences of recent origin in nuclear DNA, successful artificial transfer of functional organelle genes to the nucleus, and several examples of recently lost organelle genes, although none of these is known to have been replaced by a nuclear homologue that is clearly of organellar ancestry. We present gene sequence and molecular phylogenetic evidence for the transfer of the chloroplast tufA gene to the nucleus in the green algal ancestor of land plants. PMID:2314461

  8. A unique horizontal gene transfer event has provided the octocoral mitochondrial genome with an active mismatch repair gene that has potential for an unusual self-contained function

    PubMed Central

    2011-01-01

    Background The mitochondrial genome of the Octocorallia has several characteristics atypical for metazoans, including a novel gene suggested to function in DNA repair. This mtMutS gene is favored for octocoral molecular systematics, due to its high information content. Several hypotheses concerning the origins of mtMutS have been proposed, and remain equivocal, although current weight of support is for a horizontal gene transfer from either an epsilonproteobacterium or a large DNA virus. Here we present new and compelling evidence on the evolutionary origin of mtMutS, and provide the very first data on its activity, functional capacity and stability within the octocoral mitochondrial genome. Results The mtMutS gene has the expected conserved amino acids, protein domains and predicted tertiary protein structure. Phylogenetic analysis indicates that mtMutS is not a member of the MSH family and therefore not of eukaryotic origin. MtMutS clusters closely with representatives of the MutS7 lineage; further support for this relationship derives from the sharing of a C-terminal endonuclease domain that confers a self-contained mismatch repair function. Gene expression analyses confirm that mtMutS is actively transcribed in octocorals. Rates of mitochondrial gene evolution in mtMutS-containing octocorals are lower than in their hexacoral sister-group, which lacks the gene, although paradoxically the mtMutS gene itself has higher rates of mutation than other octocoral mitochondrial genes. Conclusions The octocoral mtMutS gene is active and codes for a protein with all the necessary components for DNA mismatch repair. A lower rate of mitochondrial evolution, and the presence of a nicking endonuclease domain, both indirectly support a theory of self-sufficient DNA mismatch repair within the octocoral mitochondrion. The ancestral affinity of mtMutS to non-eukaryotic MutS7 provides compelling support for an origin by horizontal gene transfer. The immediate vector of transmission

  9. Horizontal Gene Transfers from Bacteria to Entamoeba Complex: A Strategy for Dating Events along Species Divergence.

    PubMed

    Romero, Miguel; Cerritos, R; Ximenez, Cecilia

    2016-01-01

    Horizontal gene transfer has proved to be relevant in eukaryotic evolution, as it has been found more often than expected and related to adaptation to certain niches. A relatively large list of laterally transferred genes has been proposed and evaluated for the parasite Entamoeba histolytica. The goals of this work were to elucidate the importance of lateral gene transfer along the evolutionary history of some members of the genus Entamoeba, through identifying donor groups and estimating the divergence time of some of these events. In order to estimate the divergence time of some of the horizontal gene transfer events, the dating of some Entamoeba species was necessary, following an indirect dating strategy based on the fossil record of plausible hosts. The divergence between E. histolytica and E. nuttallii probably occurred 5.93 million years ago (Mya); this lineage diverged from E. dispar 9.97 Mya, while the ancestor of the latter separated from E. invadens 68.18 Mya. We estimated times for 22 transferences; the most recent occurred 31.45 Mya and the oldest 253.59 Mya. Indeed, the acquisition of genes through lateral transfer may have triggered a period of adaptive radiation, thus playing a major role in the evolution of the Entamoeba genus. PMID:27239333

  10. Horizontal Gene Transfers from Bacteria to Entamoeba Complex: A Strategy for Dating Events along Species Divergence

    PubMed Central

    Romero, Miguel; Ximenez, Cecilia

    2016-01-01

    Horizontal gene transfer has proved to be relevant in eukaryotic evolution, as it has been found more often than expected and related to adaptation to certain niches. A relatively large list of laterally transferred genes has been proposed and evaluated for the parasite Entamoeba histolytica. The goals of this work were to elucidate the importance of lateral gene transfer along the evolutionary history of some members of the genus Entamoeba, through identifying donor groups and estimating the divergence time of some of these events. In order to estimate the divergence time of some of the horizontal gene transfer events, the dating of some Entamoeba species was necessary, following an indirect dating strategy based on the fossil record of plausible hosts. The divergence between E. histolytica and E. nuttallii probably occurred 5.93 million years ago (Mya); this lineage diverged from E. dispar 9.97 Mya, while the ancestor of the latter separated from E. invadens 68.18 Mya. We estimated times for 22 transferences; the most recent occurred 31.45 Mya and the oldest 253.59 Mya. Indeed, the acquisition of genes through lateral transfer may have triggered a period of adaptive radiation, thus playing a major role in the evolution of the Entamoeba genus. PMID:27239333

  11. Limitations of the murine nose in the development of nonviral airway gene transfer.

    PubMed

    Griesenbach, Uta; Sumner-Jones, Stephanie G; Holder, Emma; Munkonge, Felix M; Wodehouse, Theresa; Smith, Stephen N; Wasowicz, Marguerite Y; Pringle, Ian; Casamayor, Isabel; Chan, Mario; Coles, Rebecca; Cornish, Nikki; Dewar, Ann; Doherty, Ann; Farley, Raymond; Green, Anne-Marie; Jones, Bryony L; Larsen, Mia D B; Lawton, Anna E; Manvell, Michelle; Painter, Hazel; Singh, Charanjit; Somerton, Lucinda; Stevenson, Barbara; Varathalingam, Anusha; Siegel, Craig; Scheule, Ronald K; Cheng, Seng H; Davies, Jane C; Porteous, David J; Gill, Deborah R; Boyd, A Christopher; Hyde, Steve C; Alton, Eric W F W

    2010-07-01

    A clinical program to assess whether lipid GL67A-mediated gene transfer can ameliorate cystic fibrosis (CF) lung disease is currently being undertaken by the UK CF Gene Therapy Consortium. We have evaluated GL67A gene transfer to the murine nasal epithelium of wild-type and CF knockout mice to assess this tissue as a test site for gene transfer agents. The plasmids used were regulated by either (1) the commonly used short-acting cytomegalovirus promoter/enhancer or (2) the ubiquitin C promoter. In a study of approximately 400 mice with CF, vector-specific CF transmembrane conductance regulator (CFTR) mRNA was detected in nasal epithelial cells of 82% of mice treated with a cytomegalovirus-plasmid (pCF1-CFTR), and 62% of mice treated with an ubiquitin C-plasmid. We then assessed whether CFTR gene transfer corrected a panel of CFTR-specific endpoint assays in the murine nose, including ion transport, periciliary liquid height, and ex vivo bacterial adherence. Importantly, even with the comparatively large number of animals assessed, the CFTR function studies were only powered to detect changes of more than 50% toward wild-type values. Within this limitation, no significant correction of the CF phenotype was detected. At the current levels of gene transfer efficiency achievable with nonviral vectors, the murine nose is of limited value as a stepping stone to human trials. PMID:19648474

  12. Complexity of genetic sequences modified by horizontal gene transfer and degraded-DNA uptake

    NASA Astrophysics Data System (ADS)

    Tremberger, George; Dehipawala, S.; Nguyen, A.; Cheung, E.; Sullivan, R.; Holden, T.; Lieberman, D.; Cheung, T.

    2015-09-01

    Horizontal gene transfer has been a major vehicle for efficient transfer of genetic materials among living species and could be one of the sources for noncoding DNA incorporation into a genome. Our previous study of lnc- RNA sequence complexity in terms of fractal dimension and information entropy shows a tight regulation among the studied genes in numerous diseases. The role of sequence complexity in horizontal transferred genes was investigated with Mealybug in symbiotic relation with a 139K genome microbe and Deinococcus radiodurans as examples. The fractal dimension and entropy showed correlation R-sq of 0.82 (N = 6) for the studied Deinococcus radiodurans sequences. For comparison the Deinococcus radiodurans oxidative stress tolerant catalase and superoxide dismutase genes under extracellular dGMP growth condition showed R-sq ~ 0.42 (N = 6); and the studied arsenate reductase horizontal transferred genes for toxicity survival in several microorganisms showed no correlation. Simulation results showed that R-sq < 0.4 would be improbable at less than one percent chance, suggestive of additional selection pressure when compared to the R-sq ~ 0.29 (N = 21) in the studied transferred genes in Mealybug. The mild correlation of R-sq ~ 0.5 for fractal dimension versus transcription level in the studied Deinococcus radiodurans sequences upon extracellular dGMP growth condition would suggest that lower fractal dimension with less electron density fluctuation favors higher transcription level.

  13. Targeted gene transfer into rat facial muscles by nanosecond pulsed laser-induced stress waves.

    PubMed

    Kurita, Akihiro; Matsunobu, Takeshi; Satoh, Yasushi; Ando, Takahiro; Sato, Shunichi; Obara, Minoru; Shiotani, Akihiro

    2011-09-01

    We investigate the feasibility of using nanosecond pulsed laser-induced stress waves (LISWs) for gene transfer into rat facial muscles. LISWs are generated by irradiating a black natural rubber disk placed on the target tissue with nanosecond pulsed laser light from the second harmonics (532 nm) of a Q-switched Nd:YAG laser, which is widely used in head and neck surgery and proven to be safe. After injection of plasmid deoxyribose nucleic acid (DNA) coding for Lac Z into rat facial muscles, pulsed laser is used to irradiate the laser target on the skin surface without incision or exposure of muscles. Lac Z expression is detected by X-gal staining of excised rat facial skin and muscles. Strong Lac Z expression is observed seven days after gene transfer, and sustained for up to 14 days. Gene transfer is achieved in facial muscles several millimeters deep from the surface. Gene expression is localized to the tissue exposed to LISWs. No tissue damage from LISWs is observed. LISW is a promising nonviral target gene transfer method because of its high spatial controllability, easy applicability, and minimal invasiveness. Gene transfer using LISW to produce therapeutic proteins such as growth factors could be used to treat nerve injury and paralysis. PMID:21950944

  14. Gene Transfers Shaped the Evolution of De Novo NAD+ Biosynthesis in Eukaryotes

    PubMed Central

    Ternes, Chad M.; Schönknecht, Gerald

    2014-01-01

    NAD+ is an essential molecule for life, present in each living cell. It can function as an electron carrier or cofactor in redox biochemistry and energetics, and serves as substrate to generate the secondary messenger cyclic ADP ribose and nicotinic acid adenine dinucleotide phosphate. Although de novo NAD+ biosynthesis is essential, different metabolic pathways exist in different eukaryotic clades. The kynurenine pathway starting with tryptophan was most likely present in the last common ancestor of all eukaryotes, and is active in fungi and animals. The aspartate pathway, detected in most photosynthetic eukaryotes, was probably acquired from the cyanobacterial endosymbiont that gave rise to chloroplasts. An evolutionary analysis of enzymes catalyzing de novo NAD+ biosynthesis resulted in evolutionary trees incongruent with established organismal phylogeny, indicating numerous gene transfers. Endosymbiotic gene transfers probably introduced the aspartate pathway into eukaryotes and may have distributed it among different photosynthetic clades. In addition, several horizontal gene transfers substituted eukaryotic genes with bacterial orthologs. Although horizontal gene transfer is accepted as a key mechanism in prokaryotic evolution, it is supposed to be rare in eukaryotic evolution. The essential metabolic pathway of de novo NAD+ biosynthesis in eukaryotes was shaped by numerous gene transfers. PMID:25169983

  15. Targeted gene transfer into rat facial muscles by nanosecond pulsed laser-induced stress waves

    NASA Astrophysics Data System (ADS)

    Kurita, Akihiro; Matsunobu, Takeshi; Satoh, Yasushi; Ando, Takahiro; Sato, Shunichi; Obara, Minoru; Shiotani, Akihiro

    2011-09-01

    We investigate the feasibility of using nanosecond pulsed laser-induced stress waves (LISWs) for gene transfer into rat facial muscles. LISWs are generated by irradiating a black natural rubber disk placed on the target tissue with nanosecond pulsed laser light from the second harmonics (532 nm) of a Q-switched Nd:YAG laser, which is widely used in head and neck surgery and proven to be safe. After injection of plasmid deoxyribose nucleic acid (DNA) coding for Lac Z into rat facial muscles, pulsed laser is used to irradiate the laser target on the skin surface without incision or exposure of muscles. Lac Z expression is detected by X-gal staining of excised rat facial skin and muscles. Strong Lac Z expression is observed seven days after gene transfer, and sustained for up to 14 days. Gene transfer is achieved in facial muscles several millimeters deep from the surface. Gene expression is localized to the tissue exposed to LISWs. No tissue damage from LISWs is observed. LISW is a promising nonviral target gene transfer method because of its high spatial controllability, easy applicability, and minimal invasiveness. Gene transfer using LISW to produce therapeutic proteins such as growth factors could be used to treat nerve injury and paralysis.

  16. Synthetic gene transfer vectors II: back to the future.

    PubMed

    Behr, Jean-Paul

    2012-07-17

    The discovery of RNA interference has given a new lease on life to both the chemistry of oligonucleotides and chemical approaches for the intracellular delivery of nucleic acids. In particular, delivery of siRNA, whether in vitro for screening and target validation purposes or in humans as a new class of drugs, may revolutionize our approach to therapy. Their impact could equal that of the bioproduction and various uses of monoclonal antibodies today. Unfortunately, global pharmaceutical companies again seem to be waiting to buy the next Genentech or Genzyme of gene silencing rather than investing research and development into this promising area of research. Gene silencing encounters barriers similar to gene addition and hence may benefit from the extra decade of experience brought by gene therapy. "Chemical" transfection of cells in culture has become routine, and this Account discusses some of the reasons this success has not extended to nonviral gene therapy trials, most of which do not progress beyond the phase 2 stage. The author also discusses a (much debated) mechanism of nucleic acid cell entry and subsequent release of the polycationic particles into the cytoplasm. Both topics should be useful to those interested in delivery of siRNA. The move from gene therapy toward siRNA as an oligonucleotide-based therapy strategy provides a much wider range of druggable targets. Even though these molecules are a hundredfold smaller than a gene, they are delivered via similar cellular mechanisms. Their complexes with cationic polymers are less stable than those with a higher number of phosphate groups, which may be compensated by siRNA concatemerization or by chemical conjugation with the cationic carrier. Thus chemistry is again desperately needed. PMID:22311735

  17. Activity-stability relationships revisited in blue oxidases catalyzing electron transfer at extreme temperatures.

    PubMed

    Roulling, Frédéric; Godin, Amandine; Cipolla, Alexandre; Collins, Tony; Miyazaki, Kentaro; Feller, Georges

    2016-09-01

    Cuproxidases are a subset of the blue multicopper oxidases that catalyze the oxidation of toxic Cu(I) ions into less harmful Cu(II) in the bacterial periplasm. Cuproxidases from psychrophilic, mesophilic, and thermophilic bacteria display the canonical features of temperature adaptation, such as increases in structural stability and apparent optimal temperature for activity with environmental temperature as well as increases in the binding affinity for catalytic and substrate copper ions. In contrast, the oxidative activities at 25 °C for both the psychrophilic and thermophilic enzymes are similar, suggesting that the nearly temperature-independent electron transfer rate does not require peculiar adjustments. Furthermore, the structural flexibilities of both the psychrophilic and thermophilic enzymes are also similar, indicating that the firm and precise bindings of the four catalytic copper ions are essential for the oxidase function. These results show that the requirements for enzymatic electron transfer, in the absence of the selective pressure of temperature on electron transfer rates, produce a specific adaptive pattern, which is distinct from that observed in enzymes possessing a well-defined active site and relying on conformational changes such as for the induced fit mechanism. PMID:27315165

  18. Optical fiber-based photomechanical gene transfer system for in vivo application.

    PubMed

    Sato, Shunichi; Ando, Takahiro; Obara, Minoru

    2011-12-01

    We developed an optical-fiber-based photomechanical gene transfer system for endoscopic or catheter-based application. A fiber tip with a laser-absorbing film covered with a transparent plastic disk for plasma confinement was attached to a quartz fiber; the film was irradiated with nanosecond laser pulses transmitted through the fiber to generate photomechanical waves (PMWs). Characteristics of PMWs emitted from the fiber tip were examined to confirm the necessary conditions for gene transfer. We then attempted to transfer reporter genes to the rat skin as a test tissue in vivo with the fiber system, and the results showed significantly high protein levels and spatially selective pinpoint gene expressions in the tissue. PMID:22139237

  19. Factors affecting stepladder stability during a lateral weight transfer: a study in healthy young adults.

    PubMed

    Yang, Bing-Shiang; Ashton-Miller, James A

    2005-09-01

    A fall from a stepladder is often initiated by a loss of lateral stability. An inverted pendulum model of the human, validated by experiment, was used to determine the feasible range of whole-body center of mass (COM) states for which weight can be transferred laterally on a ladder tread without a ladder rail losing contact with the ground ("no lift-off" stability region). The results show that the size of the feasible no lift-off region was inversely proportional to the height of the tread above the ground, the distance of the stance foot from the ipsilateral rail, and lateral ground inclination angle. For given initial COM kinematics on a tread height equal to 40% human body height, a stance-foot location equal to one-eighth tread width and a 3.5 degrees ground inclination had approximately equivalent effects on the no lift-off region size. Ladder stability was three times more sensitive to tread height than to foot location. Laterally-exerted impulsive hand-tool forces should generally be limited to 8% body weight. These findings can lead to improved ladder designs and safety instructions for stepladder users. PMID:15970205

  20. 4-HNE Adduct Stability Characterized by Collision-Induced Dissociation and Electron Transfer Dissociation Mass Spectrometry

    PubMed Central

    Fritz, Kristofer S.; Kellersberger, Katherine A.; Gomez, Jose D.; Petersen, Dennis R.

    2012-01-01

    4-hydroxynonenal (4-HNE) alters numerous proteomic and genomic processes. Understanding chemical mechanisms of 4-HNE interactions with biomolecules and their respective stabilities may lead to new discoveries in biomarkers for numerous diseases of oxidative stress. Collision-induced dissociation (CID) and electron transfer dissociation (ETD) MS/MS were utilized to examine the stability of a 4-HNE-Cys Michael adduct. CID conditions resulted in the neutral loss of 4-HNE, also known as a retro-Michael addition reaction (RMA). Consequently, performing ETD fragmentation on this same adduct did not result in RMA. Interestingly, 4-HNE adduct reduction via sodium borohydride (NaBH4) treatment stabilized against the CID induced RMA. In a direct comparison of three forms of 4-HNE adducts, computational modeling revealed sizeable shifts in the shape and orientation of the lowest unoccupied molecular orbital (LUMO) density around the 4-HNE-Cys moiety. These findings demonstrate that ETD MS/MS analysis can be used to improve the detection of 4-HNE-protein modifications by preventing RMA reactions from occurring. PMID:22404378

  1. The agricultural antibiotic carbadox induces phage-mediated gene transfer in Salmonella

    PubMed Central

    Bearson, Bradley L.; Allen, Heather K.; Brunelle, Brian W.; Lee, In Soo; Casjens, Sherwood R.; Stanton, Thaddeus B.

    2013-01-01

    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 US 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 (STEC) 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 genes in the

  2. Adenovirus-mediated gene transfer to ciliated airway epithelia requires prolonged incubation time.

    PubMed Central

    Zabner, J; Zeiher, B G; Friedman, E; Welsh, M J

    1996-01-01

    The efficiency of adenovirus-mediated gene transfer to airway epithelia will be an important factor in determining whether recombinant adenoviruses can be developed as vectors for transferring cystic fibrosis transmembrane conductance regulator (CFTR) cDNA to patients with cystic fibrosis. Current understanding of the biology of CF lung disease suggests that vectors should express transgene in mature, ciliated airway epithelia. We evaluated the efficiency of adenovirus-mediated gene transfer to primary cultures of normal and CF human airway epithelia. Our studies showed that the airway cells developed from an undifferentiated epithelium with markers characteristic of basal cells and a surface covered by short microvilli 3 days after seeding to a mature epithelium whose apical surface was covered with cilia by 10 to 14 days. The ability of adenovirus vectors to express a reporter gene and to correct defective cyclic AMP-stimulated Cl- transport in CF epithelia was correlated inversely with the state of differentiation. However, the inefficiency of adenovirus-mediated gene transfer could be partially corrected when the contact time between vector and epithelium was prolonged. After prolonged contact, we observed complete correction of the CF Cl- transport defect in differentiated CF airway epithelia in culture and of the Cl- transport defect in the nasal epithelia of mice homozygous for the deltaF508 mutation. The fact that gene transfer to airway epithelia required prolonged incubation with vector contrasts with the rapid infection observed in cell models such as 293 and HeLa cells, which are commonly used to study adenovirus infection. Gene transfer observed after prolonged incubation may result from mechanisms different from those that mediate infection of 293 cells. These observations suggest that interventions that either increase the contact time or alter the epithelium or the vector may be required to facilitate gene transfer to ciliated respiratory epithelia

  3. Prokaryotic genes in eukaryotic genome sequences: when to infer horizontal gene transfer and when to suspect an actual microbe.

    PubMed

    Artamonova, Irena I; Lappi, Tanya; Zudina, Liudmila; Mushegian, Arcady R

    2015-07-01

    Assessment of phylogenetic positions of predicted gene and protein sequences is a routine step in any genome project, useful for validating the species' taxonomic position and for evaluating hypotheses about genome evolution and function. Several recent eukaryotic genome projects have reported multiple gene sequences that were much more similar to homologues in bacteria than to any eukaryotic sequence. In the spirit of the times, horizontal gene transfer from bacteria to eukaryotes has been invoked in some of these cases. Here, we show, using comparative sequence analysis, that some of those bacteria-like genes indeed appear likely to have been horizontally transferred from bacteria to eukaryotes. In other cases, however, the evidence strongly indicates that the eukaryotic DNA sequenced in the genome project contains a sample of non-integrated DNA from the actual bacteria, possibly providing a window into the host microbiome. Recent literature suggests also that common reagents, kits and laboratory equipment may be systematically contaminated with bacterial DNA, which appears to be sampled by metagenome projects non-specifically. We review several bioinformatic criteria that help to distinguish putative horizontal gene transfers from the admixture of genes from autonomously replicating bacteria in their hosts' genome databases or from the reagent contamination. PMID:25919787

  4. Formation of Stable Cationic Lipid/DNA Complexes for Gene Transfer

    NASA Astrophysics Data System (ADS)

    Hofland, Hans E. J.; Shephard, Lee; Sullivan, Sean M.

    1996-07-01

    Stable cationic lipid/DNA complexes were formed by solubilizing cationic liposomes with 1% octylglucoside and complexing a DNA plasmid with the lipid in the presence of detergent. Removal of the detergent by dialysis yielded a lipid/DNA suspension that was able to transfect tissue culture cells up to 90 days after formation with no loss in activity. Similar levels of gene transfer were obtained by mixing the cationic lipid in a liposome form with DNA just prior to cell addition. However, expression was completely lost 24 hr after mixing. The transfection efficiency of the stable complex in 15% fetal calf serum was 30% of that obtained in the absence of serum, whereas the transient complex was completely inactivated with 2% fetal calf serum. A 90-day stability study comparing various storage conditions showed that the stable complex could be stored frozen or as a suspension at 4 degrees C with no loss in transfection efficiency. Centrifugation of the stable complex produced a pellet that contained approximately 90% of the DNA and 10% of the lipid. Transfection of cells with the resuspended pellet and the supernatant showed that the majority of the transfection activity was in the pellet and all the toxicity was in the supernatant. Formation of a stable cationic lipid/DNA complex has produced a transfection vehicle that can be stored indefinitely, can be concentrated with no loss in transfection efficiency, and the toxicity levels can be greatly reduced when the active complex is isolated from the uncomplexed lipid.

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

    PubMed Central

    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

  6. CD133-targeted gene transfer into long-term repopulating hematopoietic stem cells.

    PubMed

    Brendel, Christian; Goebel, Benjamin; Daniela, Abriss; Brugman, Martijn; Kneissl, Sabrina; Schwäble, Joachim; Kaufmann, Kerstin B; Müller-Kuller, Uta; Kunkel, Hana; Chen-Wichmann, Linping; Abel, Tobias; Serve, Hubert; Bystrykh, Leonid; Buchholz, Christian J; Grez, Manuel

    2015-01-01

    Gene therapy for hematological disorders relies on the genetic modification of CD34(+) cells, a heterogeneous cell population containing about 0.01% long-term repopulating cells. Here, we show that the lentiviral vector CD133-LV, which uses a surface marker on human primitive hematopoietic stem cells (HSCs) as entry receptor, transfers genes preferentially into cells with high engraftment capability. Transduction of unstimulated CD34(+) cells with CD133-LV resulted in gene marking of cells with competitive proliferative advantage in vitro and in immunodeficient mice. The CD133-LV-transduced population contained significantly more cells with repopulating capacity than cells transduced with vesicular stomatitis virus (VSV)-LV, a lentiviral vector pseudotyped with the vesicular stomatitis virus G protein. Upon transfer of a barcode library, CD133-LV-transduced cells sustained gene marking in vivo for a prolonged period of time with a 6.7-fold higher recovery of barcodes compared to transduced control cells. Moreover, CD133-LV-transduced cells were capable of repopulating secondary recipients. Lastly, we show that this targeting strategy can be used for transfer of a therapeutic gene into CD34(+) cells obtained from patients suffering of X-linked chronic granulomatous disease. In conclusion, direct gene transfer into CD133(+) cells allows for sustained long-term engraftment of gene corrected cells. PMID:25189742

  7. Carotenoids in unexpected places: gall midges, lateral gene transfer, and carotenoid biosynthesis in animals.

    PubMed

    Cobbs, Cassidy; Heath, Jeremy; Stireman, John O; Abbot, Patrick

    2013-08-01

    Carotenoids are conjugated isoprenoid molecules with many important physiological functions in organisms, including roles in photosynthesis, oxidative stress reduction, vision, diapause, photoperiodism, and immunity. Until recently, it was believed that only plants, microorganisms, and fungi were capable of synthesizing carotenoids and that animals acquired them from their diet, but recent studies have demonstrated that two arthropods (pea aphid and spider mite) possess a pair of genes homologous to those required for the first step of carotenoid biosynthesis. Absent in all other known animal genomes, these genes appear to have been acquired by aphids and spider mites in one or several lateral gene transfer events from a fungal donor. We report the third case of fungal carotenoid biosynthesis gene homologs in an arthropod: flies from the family Cecidomyiidae, commonly known as gall midges. Using phylogenetic analyses we show that it is unlikely that lycopene cyclase/phytoene synthase and phytoene desaturase homologs were transferred singly to an ancient arthropod ancestor; instead we propose that genes were transferred independently from related fungal donors after divergence of the major arthropod lineages. We also examine variation in intron placement and copy number of the carotenoid genes that may underlie function in the midges. This trans-kingdom transfer of carotenoid genes may represent a key innovation, underlying the evolution of phytophagy and plant-galling in gall midges and facilitating their extensive diversification across plant lineages. PMID:23542649

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

    PubMed

    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

  9. Guanidinylated block copolymers for gene transfer: A comparison with amine-based materials for in vitro and in vivo gene transfer efficiency

    PubMed Central

    Choi, Jennifer L.; Tan, James-Kevin Y.; Sellers, Drew L.; Wei, Hua; Horner, Philip J.; Pun, Suzie H.

    2015-01-01

    There is currently no cure for neuron loss in the brain, which can occur due to traumatic injury or neurodegenerative disease. One method proposed to enhance neurogenesis in the brain is gene transfer to neural progenitor cells. In this work, a guanidine-based copolymer was synthesized and compared to an amine-based copolymer analog previously shown to effectively deliver genes in the murine brain. The guanidine-based copolymer was more efficient at gene transfer to immortalized, cultured cell lines; however, the amine-based copolymer was more effective at gene transfer in the brain. DNA condensation studies revealed that the nucleic acid complexes formed with the guanidine-based copolymer were more susceptible to unpackaging in the presence of heparin sulfate proteoglycans compared to complexes formed with the amine-based copolymer. Therefore, polyplexes formed from the amine-based copolymer may be more resistant to destabilization by the heparan sulfate proteoglycans present in the stem cell niches of the brain. PMID:25907042

  10. Horizontal transfer of archaeal genes into the deinococcaceae: detection by molecular and computer-based approaches

    NASA Technical Reports Server (NTRS)

    Olendzenski, L.; Liu, L.; Zhaxybayeva, O.; Murphey, R.; Shin, D. G.; Gogarten, J. P.

    2000-01-01

    Members of the Deinococcaceae (e.g., Thermus, Meiothermus, Deinococcus) contain A/V-ATPases typically found in Archaea or Eukaryotes which were probably acquired by horizontal gene transfer. Two methods were used to quantify the extent to which archaeal or eukaryotic genes have been acquired by this lineage. Screening of a Meiothermus ruber library with probes made against Thermoplasma acidophilum DNA yielded a number of clones which hybridized more strongly than background. One of these contained the prolyl tRNA synthetase (RS) gene. Phylogenetic analysis shows the M. ruber and D. radiodurans prolyl RS to be more closely related to archaeal and eukaryal forms of this gene than to the typical bacterial type. Using a bioinformatics approach, putative open reading frames (ORFs) from the prerelease version of the D. radiodurans genome were screened for genes more closely related to archaeal or eukaryotic genes. Putative ORFs were searched against representative genomes from each of the three domains using automated BLAST. ORFs showing the highest matches against archaeal and eukaryotic genes were collected and ranked. Among the top-ranked hits were the A/V-ATPase catalytic and noncatalytic subunits and the prolyl RS genes. Using phylogenetic methods, ORFs were analyzed and trees assessed for evidence of horizontal gene transfer. Of the 45 genes examined, 20 showed topologies in which D. radiodurans homologues clearly group with eukaryotic or archaeal homologues, and 17 additional trees were found to show probable evidence of horizontal gene transfer. Compared to the total number of ORFs in the genome, those that can be identified as having been acquired from Archaea or Eukaryotes are relatively few (approximately 1%), suggesting that interdomain transfer is rare.

  11. Heat Transfer and Thermal Stability Research for Advanced Hydrocarbon Fuel Technologies

    NASA Technical Reports Server (NTRS)

    DeWitt, Kenneth; Stiegemeier, Benjamin

    2005-01-01

    In recent years there has been increased interest in the development of a new generation of high performance boost rocket engines. These efforts, which will represent a substantial advancement in boost engine technology over that developed for the Space Shuttle Main Engines in the early 1970s, are being pursued both at NASA and the United States Air Force. NASA, under its Space Launch Initiative s Next Generation Launch Technology Program, is investigating the feasibility of developing a highly reliable, long-life, liquid oxygen/kerosene (RP-1) rocket engine for launch vehicles. One of the top technical risks to any engine program employing hydrocarbon fuels is the potential for fuel thermal stability and material compatibility problems to occur under the high-pressure, high-temperature conditions required for regenerative fuel cooling of the engine combustion chamber and nozzle. Decreased heat transfer due to carbon deposits forming on wetted fuel components, corrosion of materials common in engine construction (copper based alloys), and corrosion induced pressure drop increases have all been observed in laboratory tests simulating rocket engine cooling channels. To mitigate these risks, the knowledge of how these fuels behave in high temperature environments must be obtained. Currently, due to the complexity of the physical and chemical process occurring, the only way to accomplish this is empirically. Heated tube testing is a well-established method of experimentally determining the thermal stability and heat transfer characteristics of hydrocarbon fuels. The popularity of this method stems from the low cost incurred in testing when compared to hot fire engine tests, the ability to have greater control over experimental conditions, and the accessibility of the test section, facilitating easy instrumentation. These benefits make heated tube testing the best alternative to hot fire engine testing for thermal stability and heat transfer research. This investigation

  12. Horizontal Gene Transfer and the Genomics of Enterococcal Antibiotic Resistance

    PubMed Central

    Palmer, Kelli L.; Kos, Veronica N.

    2010-01-01

    Summary Enterococci are Gram-positive bacteria that normally colonize gastrointestinal tracts of humans and animals. They are of growing concern because of their ability to cause antibiotic resistant hospital infections. Antibiotic resistance has been acquired, and has disseminated throughout enterococci, via horizontal transfer of mobile genetic elements. This transmission has been mediated mainly by conjugative plasmids of the pheromone-responsive and broad host range incompatibility group 18 type. Genome sequencing is revealing the extent of diversity of these and other mobile elements in enterococci, as well as the extent of recombination and rearrangement resulting in new phenotypes. Pheromone-responsive plasmids were recently shown to promote genome plasticity in antibiotic resistant Enterococcus faecalis, and their involvement has been implicated in E. faecium as well. Further, incompatibility group 18 plasmids have recently played an important role in mediating transfer of vancomycin resistance from enterococci to methicillin resistant strains of S. aureus. PMID:20837397

  13. Evaluation and validation of reference gene stability during Marek's disease virus (MDV) infection.

    PubMed

    Neerukonda, Sabari Nath; Katneni, Upendra K; Golovan, Sergey; Parcells, Mark S

    2016-10-01

    Quantitative RT-PCR (qRT-PCR) is widely used in the study of relative gene expression in general, and has been used in the field of Marek's disease (MD) research to measure transcriptional responses to infection and/or vaccination. Studies in the past have either employed cellular β-actin (BACT) or glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as internal reference genes, although the stability of their expression in the context of Marek's disease virus (MDV) infection has never been investigated. In the present study, we compared the stability of five reference genes (BACT, 28S RNA, 18S RNA, GAPDH, Peptidyl-prolyl-isomerase B [PPIB], a.k.a. cyclophilin B) as standard internal controls in chicken embryo fibroblast (CEFs) cultures infected with either MD vaccine or oncogenic MDV1 viruses. We further extend these analyses to reference gene stability in spleen lymphomas induced by infection of commercial broiler chickens with a very virulent plus MDV1 (vv+ TK-2a virus). Two excel based algorithms, (Bestkeeper and Normfinder) were employed to compare reference gene stability. Bestkeeper and Normfinder analysis of reference gene stability in virus- and mock-infected cells, showed that 28S RNA and PPIB displayed higher stability in CEF infections with either oncogenic or vaccine viruses. In addition, both Bestkeeper and Normfinder determined 28S RNA and PPIB to be the most stably-expressed reference genes in vivo in vv+ TK-2a-induced spleen lymphomas. Furthermore, Bestkeeper and Normfinder analyses both determined BACT to be the least stable reference gene during MDV infection of CEF with oncogenic viruses, vaccine viruses, as well as in vv+ TK-2a-induced spleen lymphomas. PMID:27448823

  14. Gene Transfer to the Desiccation-Tolerant Cyanobacterium Chroococcidiopsis

    PubMed Central

    Billi, Daniela; Friedmann, E. Imre; Helm, Richard F.; Potts, Malcolm

    2001-01-01

    The coccoid cyanobacterium Chroococcidiopsis dominates microbial communities in the most extreme arid hot and cold deserts. These communities withstand constraints that result from multiple cycles of drying and wetting and/or prolonged desiccation, through mechanisms which remain poorly understood. Here we describe the first system for genetic manipulation of Chroococcidiopsis. Plasmids pDUCA7 and pRL489, based on the pDU1 replicon of Nostoc sp. strain PCC 7524, were transferred to different isolates of Chroococcidiopsis via conjugation and electroporation. This report provides the first evidence that pDU1 replicons can be maintained in cyanobacteria other than Nostoc and Anabaena. Following conjugation, both plasmids replicated in Chroococcidiopsis sp. strains 029, 057, and 123 but not in strains 171 and 584. Both plasmids were electroporated into strains 029 and 123 but not into strains 057, 171, and 584. Expression of PpsbA-luxAB on pRL489 was visualized through in vivo luminescence. Efficiencies of conjugative transfer for pDUCA7 and pRL489 into Chroococcidiopsis sp. strain 029 were approximately 10−2 and 10−4 transconjugants per recipient cell, respectively. Conjugative transfer occurred with a lower efficiency into strains 057 and 123. Electrotransformation efficiencies of about 10−4 electrotransformants per recipient cell were achieved with strains 029 and 123, using either pDUCA7 or pRL489. Extracellular deoxyribonucleases were associated with each of the five strains. Phylogenetic analysis, based upon the V6 to V8 variable regions of 16S rRNA, suggests that desert strains 057, 123, 171, and 029 are distinct from the type species strain Chroococcidiopsis thermalis PCC 7203. The high efficiency of conjugative transfer of Chroococcidiopsis sp. strain 029, from the Negev Desert, Israel, makes this a suitable experimental strain for genetic studies on desiccation tolerance. PMID:11244070

  15. Transferring Sclerotinia Resistance Genes from Wild Helianthus into Cultivated Sunflower

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To enhance resistance to Sclerotinia head and stalk rot in cultivated sunflower, mining and introgression of Sclerotinia resistance genes from diverse wild Helianthus accessions into cultivated sunflower has been conducted using backcrossing method since 2004. During the last four years, numerous in...

  16. Massive Gene Transfer and Extensive RNA Editing of a Symbiotic Dinoflagellate Plastid Genome

    PubMed Central

    Mungpakdee, Sutada; Shinzato, Chuya; Takeuchi, Takeshi; Kawashima, Takeshi; Koyanagi, Ryo; Hisata, Kanako; Tanaka, Makiko; Goto, Hiroki; Fujie, Manabu; Lin, Senjie; Satoh, Nori; Shoguchi, Eiichi

    2014-01-01

    Genome sequencing of Symbiodinium minutum revealed that 95 of 109 plastid-associated genes have been transferred to the nuclear genome and subsequently expanded by gene duplication. Only 14 genes remain in plastids and occur as DNA minicircles. Each minicircle (1.8–3.3 kb) contains one gene and a conserved noncoding region containing putative promoters and RNA-binding sites. Nine types of RNA editing, including a novel G/U type, were discovered in minicircle transcripts but not in genes transferred to the nucleus. In contrast to DNA editing sites in dinoflagellate mitochondria, which tend to be highly conserved across all taxa, editing sites employed in DNA minicircles are highly variable from species to species. Editing is crucial for core photosystem protein function. It restores evolutionarily conserved amino acids and increases peptidyl hydropathy. It also increases protein plasticity necessary to initiate photosystem complex assembly. PMID:24881086

  17. Mucus altering agents as adjuncts for nonviral gene transfer to airway epithelium.

    PubMed

    Ferrari, S; Kitson, C; Farley, R; Steel, R; Marriott, C; Parkins, D A; Scarpa, M; Wainwright, B; Evans, M J; Colledge, W H; Geddes, D M; Alton, E W

    2001-09-01

    Nonviral vectors have been shown to be a safe and valid alternative to recombinant viruses for gene therapy of cystic fibrosis (CF). Nevertheless, gene transfer efficiency needs to be increased before clinical efficacy is likely in man. One barrier to increased efficacy is normal airway mucus. Using an ex vivo model of sheep tracheal epithelium, we show that this barrier can, in part, be overcome by treatment with the mucolytic agents, Nacystelyn or N-acetylcysteine using either a cationic lipid or a cationic polymer as the gene transfer agent. Further, in vivo application of either Nacystelyn or the anticholinergic glycopyrrolate, both clinically used agents, resulted in increased reporter gene expression in the mouse lung, but no significant correction of the bioelectric defect in CF null mice. These results, whilst unlikely to be sufficient in themselves to achieve clinically relevant gene therapy, may be a further useful step in the attainment of this goal. PMID:11571577

  18. HGT-Finder: A New Tool for Horizontal Gene Transfer Finding and Application to Aspergillus genomes

    PubMed Central

    Nguyen, Marcus; Ekstrom, Alex; Li, Xueqiong; Yin, Yanbin

    2015-01-01

    Horizontal gene transfer (HGT) is a fast-track mechanism that allows genetically unrelated organisms to exchange genes for rapid environmental adaptation. We developed a new phyletic distribution-based software, HGT-Finder, which implements a novel bioinformatics algorithm to calculate a horizontal transfer index and a probability value for each query gene. Applying this new tool to the Aspergillus fumigatus, Aspergillus flavus, and Aspergillus nidulans genomes, we found 273, 542, and 715 transferred genes (HTGs), respectively. HTGs have shorter length, higher guanine-cytosine (GC) content, and relaxed selection pressure. Metabolic process and secondary metabolism functions are significantly enriched in HTGs. Gene clustering analysis showed that 61%, 41% and 74% of HTGs in the three genomes form physically linked gene clusters (HTGCs). Overlapping manually curated, secondary metabolite gene clusters (SMGCs) with HTGCs found that 9 of the 33 A. fumigatus SMGCs and 31 of the 65 A. nidulans SMGCs share genes with HTGCs, and that HTGs are significantly enriched in SMGCs. Our genome-wide analysis thus presented very strong evidence to support the hypothesis that HGT has played a very critical role in the evolution of SMGCs. The program is freely available at http://cys.bios.niu.edu/HGTFinder/HGTFinder.tar.gz. PMID:26473921

  19. GFP as a marker for transient gene transfer and expression in Mycoplasma hyorhinis.

    PubMed

    Ishag, Hassan Z A; Liu, Maojun; Yang, Ruosong; Xiong, Qiyan; Feng, Zhixin; Shao, Guoqing

    2016-01-01

    Mycoplasma hyorhinis (M. hyorhinis) is an opportunistic pathogen of pigs and has been shown to transform cell cultures, which has increased the interest of researchers. The green florescence proteins (GFP) gene of Aquorea victoria, proved to be a vital marker to identify transformed cells in mixed populations. Use of GFP to observe gene transfer and expression in M. hyorhinis (strain HUB-1) has not been described. We have constructed a pMD18-O/MHRgfp plasmid containing the p97 gene promoter, origin of replication, tetracycline resistance marker and GFP gene controlled by the p97 gene promoter. The plasmid transformed into M. hyorhinis with a frequency of ~4 × 10(-3) cfu/µg plasmid DNA and could be detected by PCR amplification of the GFP gene from the total DNA of the transformant mycoplasmas. Analysis of a single clone grown on KM2-Agar containing tetracycline, showed a green fluorescence color. Conclusively, this report suggests the usefulness of GFP to monitor transient gene transfer and expression in M. hyorhinis, eventually minimizing screening procedures for gene transfer and expression. PMID:27386255

  20. Plant expansins in bacteria and fungi: evolution by horizontal gene transfer and independent domain fusion.

    PubMed

    Nikolaidis, Nikolas; Doran, Nicole; Cosgrove, Daniel J

    2014-02-01

    Horizontal gene transfer (HGT) has been described as a common mechanism of transferring genetic material between prokaryotes, whereas genetic transfers from eukaryotes to prokaryotes have been rarely documented. Here we report a rare case of HGT in which plant expansin genes that code for plant cell-wall loosening proteins were transferred from plants to bacteria, fungi, and amoebozoa. In several cases, the species in which the expansin gene was found is either in intimate association with plants or is a known plant pathogen. Our analyses suggest that at least two independent genetic transfers occurred from plants to bacteria and fungi. These events were followed by multiple HGT events within bacteria and fungi. We have also observed that in bacteria expansin genes have been independently fused to DNA fragments that code for an endoglucanase domain or for a carbohydrate binding module, pointing to functional convergence at the molecular level. Furthermore, the functional similarities between microbial expansins and their plant xenologs suggest that these proteins mediate microbial-plant interactions by altering the plant cell wall and therefore may provide adaptive advantages to these species. The evolution of these nonplant expansins represents a unique case in which bacteria and fungi have found innovative and adaptive ways to interact with and infect plants by acquiring genes from their host. This evolutionary paradigm suggests that despite their low frequency such HGT events may have significantly contributed to the evolution of prokaryotic and eukaryotic species. PMID:24150040

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

    SciTech Connect

    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.

  2. Rare Events of Intragenus and Intraspecies Horizontal Transfer of the 16S rRNA Gene

    PubMed Central

    Tian, Ren-Mao; Cai, Lin; Zhang, Wei-Peng; Cao, Hui-Luo; Qian, Pei-Yuan

    2015-01-01

    Horizontal gene transfer (HGT) of operational genes has been widely reported in prokaryotic organisms. However, informational genes such as those involved in transcription and translation processes are very difficult to be horizontally transferred, as described by Woese’s complexity hypothesis. Here, we analyzed all of the completed prokaryotic genome sequences (2,143 genomes) in the NCBI (National Center for Biotechnology Information) database, scanned for genomes with high intragenomic heterogeneity of 16S rRNA gene copies, and explored potential HGT events of ribosomal RNA genes based on the phylogeny, genomic organization, and secondary structures of the ribosomal RNA genes. Our results revealed 28 genomes with relatively high intragenomic heterogeneity of multiple 16S rRNA gene copies (lowest pairwise identity <98.0%), and further analysis revealed HGT events and potential donors of the heterogeneous copies (such as HGT from Chlamydia suis to Chlamydia trachomatis) and mutation events of some heterogeneous copies (such as Streptococcus suis JS14). Interestingly, HGT of the 16S rRNA gene only occurred at intragenus or intraspecies levels, which is quite different from the HGT of operational genes. Our results improve our understanding regarding the exchange of informational genes. PMID:26220935

  3. Direct phylogenetic evidence for lateral transfer of elongation factor-like gene

    PubMed Central

    Kamikawa, Ryoma; Inagaki, Yuji; Sako, Yoshihiko

    2008-01-01

    Genes encoding elongation factor-like (EFL) proteins, which show high similarity to elongation factor-1α (EF-1α), have been found in phylogenetically distantly related eukaryotes. The sporadic distribution of “EFL-containing” lineages within “EF-1α-containing” lineages indirectly, but strongly, suggests lateral gene transfer as the principal driving force in EFL evolution. However, one of the most critical aspects in the above hypothesis, the donor lineages in any putative cases of lateral EFL gene transfer, remained unclear. In this study, we provide direct evidence for lateral transfer of an EFL gene through the analyses of 10 diatom EFL genes. All diatom EFL homologues tightly clustered in phylogenetic analyses, suggesting acquisition of the exogenous EFL gene early in diatom evolution. Our survey additionally identified Thalassiosira pseudonana as a eukaryote bearing EF-1α and EFL genes and secondary EFL gene loss in Phaeodactylum tricornutum, the complete genome of which encodes only the EF-1α gene. Most importantly, the EFL phylogeny recovered a robust grouping of homologues from diatoms, the cercozoan Bigelowiella natans, and the foraminifer Planoglabratella opecularis, with the diatoms nested within the Bigelowiella plus Planoglabratella (Rhizaria) grouping. The particular relationships recovered are further consistent with two characteristic sequence motifs. The best explanation of our data analyses is an EFL gene transfer from a foraminifer to a diatom, the first case in which the donor–recipient relationship was clarified. Finally, based on a reverse transcriptase quantitative PCR assay and the genome information of Thalassiosira and Phaeodactylum, we propose the loss of elongation factor function in Thalassiosira EF-1α. PMID:18458344

  4. Improving lipoprotein profiles by liver-directed gene transfer of low density lipoprotein receptor gene in hypercholesterolaemia mice.

    PubMed

    Ou, Hailong; Zhang, Qinghai; Zeng, Jia

    2016-06-01

    The defect of low density lipoprotein receptor disturbs cholesterol metabolism and causes familial hypercholesterolaemia (FH). In this study, we directly delivered exogenous Ldlr gene into the liver of FH model mice (Ldlr(-/-)) by lentiviral gene transfer system. The results showed that the Ldlr gene controlled by hepatocyte-specific human thyroxine-binding globulin (TBG) promoter successfully and exclusively expressed in livers.We found that, although, the content of high density lipoprotein in serum was not significantly affected by the Ldlr gene expression, the serum low density lipoprotein level was reduced by 46%, associated with a 30% and 28% decrease in triglyceride and total cholesterol, respectively, compared to uninjected Ldlr(-/-) mice. Moreover, the TBG directed expression of Ldlr significantly decreased the lipid accumulation in liver and reduced plaque burden in aorta (32%). Our results indicated that the hepatocyte-specific expression of Ldlr gene strikingly lowered serum lipid levels and resulted in amelioration of hypercholesterolaemia. PMID:27350674

  5. The transfer and transformation of collective network information in gene-matched networks

    PubMed Central

    Kitsukawa, Takashi; Yagi, Takeshi

    2015-01-01

    Networks, such as the human society network, social and professional networks, and biological system networks, contain vast amounts of information. Information signals in networks are distributed over nodes and transmitted through intricately wired links, making the transfer and transformation of such information difficult to follow. Here we introduce a novel method for describing network information and its transfer using a model network, the Gene-matched network (GMN), in which nodes (neurons) possess attributes (genes). In the GMN, nodes are connected according to their expression of common genes. Because neurons have multiple genes, the GMN is cluster-rich. We show that, in the GMN, information transfer and transformation were controlled systematically, according to the activity level of the network. Furthermore, information transfer and transformation could be traced numerically with a vector using genes expressed in the activated neurons, the active-gene array, which was used to assess the relative activity among overlapping neuronal groups. Interestingly, this coding style closely resembles the cell-assembly neural coding theory. The method introduced here could be applied to many real-world networks, since many systems, including human society and various biological systems, can be represented as a network of this type. PMID:26450411

  6. Eukaryote to gut bacteria transfer of a glycoside hydrolase gene essential for starch breakdown in plants

    PubMed Central

    Arias, Maria Cecilia; Danchin, Étienne G.J.; Coutinho, Pedro; Henrissat, Bernard; Ball, Steven

    2012-01-01

    Lateral gene transfer (LGT) between bacteria constitutes a strong force in prokaryote evolution, transforming the hierarchical tree of life into a network of relationships between species. In contrast, only a few cases of LGT from eukaryotes to prokaryotes have been reported so far. The distal animal intestine is predominantly a bacterial ecosystem, supplying the host with energy from dietary polysaccharides through carbohydrate-active enzymes absent from its genome. It has been suggested that LGT is particularly important for the human microbiota evolution. Here we show evidence for the first eukaryotic gene identified in multiple gut bacterial genomes. We found in the genome sequence of several gut bacteria, a typically eukaryotic glycoside-hydrolase necessary for starch breakdown in plants. The distribution of this gene is patchy in gut bacteria with presence otherwise detected only in a few environmental bacteria. We speculate that the transfer of this gene to gut bacteria occurred by a sequence of two key LGT events; first, an original eukaryotic gene was transferred probably from Archaeplastida to environmental bacteria specialized in plant polysaccharides degradation and second, the gene was transferred from the environmental bacteria to gut microbes. PMID:22934241

  7. The transfer and transformation of collective network information in gene-matched networks.

    PubMed

    Kitsukawa, Takashi; Yagi, Takeshi

    2015-01-01

    Networks, such as the human society network, social and professional networks, and biological system networks, contain vast amounts of information. Information signals in networks are distributed over nodes and transmitted through intricately wired links, making the transfer and transformation of such information difficult to follow. Here we introduce a novel method for describing network information and its transfer using a model network, the Gene-matched network (GMN), in which nodes (neurons) possess attributes (genes). In the GMN, nodes are connected according to their expression of common genes. Because neurons have multiple genes, the GMN is cluster-rich. We show that, in the GMN, information transfer and transformation were controlled systematically, according to the activity level of the network. Furthermore, information transfer and transformation could be traced numerically with a vector using genes expressed in the activated neurons, the active-gene array, which was used to assess the relative activity among overlapping neuronal groups. Interestingly, this coding style closely resembles the cell-assembly neural coding theory. The method introduced here could be applied to many real-world networks, since many systems, including human society and various biological systems, can be represented as a network of this type. PMID:26450411

  8. Mathematical modelling of antimicrobial resistance in agricultural waste highlights importance of gene transfer rate.

    PubMed

    Baker, Michelle; Hobman, Jon L; Dodd, Christine E R; Ramsden, Stephen J; Stekel, Dov J

    2016-04-01

    Antimicrobial resistance is of global concern. Most antimicrobial use is in agriculture; manures and slurry are especially important because they contain a mix of bacteria, including potential pathogens, antimicrobial resistance genes and antimicrobials. In many countries, manures and slurry are stored, especially over winter, before spreading onto fields as organic fertilizer. Thus, these are a potential location for gene exchange and selection for resistance. We develop and analyse a mathematical model to quantify the spread of antimicrobial resistance in stored agricultural waste. We use parameters from a slurry tank on a UK dairy farm as an exemplar. We show that the spread of resistance depends in a subtle way on the rates of gene transfer and antibiotic inflow. If the gene transfer rate is high, then its reduction controls resistance, while cutting antibiotic inflow has little impact. If the gene transfer rate is low, then reducing antibiotic inflow controls resistance. Reducing length of storage can also control spread of resistance. Bacterial growth rate, fitness costs of carrying antimicrobial resistance and proportion of resistant bacteria in animal faeces have little impact on spread of resistance. Therefore, effective treatment strategies depend critically on knowledge of gene transfer rates. PMID:26906100

  9. Gene gun transferring-bone morphogenetic protein 2 (BMP-2) gene enhanced bone fracture healing in rabbits

    PubMed Central

    Li, Wenju; Wei, Haifeng; Xia, Chunmei; Zhu, Xiaomeng; Hou, Guozhu; Xu, Feng; Song, Xinghua; Zhan, Yulin

    2015-01-01

    Purpose: Transferring the bone morphogenetic protein 2 (BMP-2) genes into the tissues or cells can improve the bone healing of the fracture has been widely accepted. We evaluated the efficiency of using gene gun to transfer the BMP-2 gene thereby affected the healing of a fractured bone. Methods: The vector coding for BMP-2 was constructed by a non-replicating encephalo-myocarditis virus (ECMV)-based vector. The segmental bone defect (1.5 cm) model was created by a wire-saw at the middle part of the radius bone of the New Zealand white rabbits. Then either BMP-2 gene or control vector without BMP-2 gene was injected into the tissues around the fracture site. Healing of the defects was monitored radiographically for 9 weeks, bone consolidation was determined by the Lane-Sandhu score pre- and post-operatively, which can evaluated bone formation, bone connect and bone plasticity. Results: The radiographic score and bone consolidation rates were significantly higher in animals injected with BMP-2 gene group as compared with control vector-injected animals (P<0.05). The control group still showed no radiological signs of stable healing. Western-blot and RT-PCR showed BMP-2 expression was significant increase in the tissues around the site of osseous lesions in comparison with the control vector-injected animals (P<0.05). Conclusions: Our results suggested that BMP-2 gene transferred by gene gun could increase the expression of BMP-2 protein and improved the bone callus formation therefore shortened the time of bone defect healing. PMID:26884910

  10. Adenovirus-mediated gene transfer to tumor cells.

    PubMed

    Cascalló, Manel; Alemany, Ramon

    2004-01-01

    Cell transduction in vitro is only the first step toward proving that a genetherapy vector can be useful to treat tumors. However, tumor targeting in vivo is now the milestone for gene therapy to succeed against disseminated cancer. Therefore, most valuable information is obtained from studies of vector biodistribution. Owing to the hepatotropism of adenoviral vectors, a particularly important parameter is the tumor/liver ratio. This ratio can be given at the level of gene expression if the amount of transgene expression is measured. To optimize the targeting, however, the levels of viral particles that reach the tumor compared to other organs must be studied. Most of this chapter deals with methods to quantify the virus fate in tumor-bearing animals. We present a radioactive labeling method that can be used to study biodistribution. After a small section dealing with tumor models, we describe methods to quantify different parameters related to adenovirus-mediated tumor targeting. PMID:14970588

  11. Decreasing the effects of horizontal gene transfer on bacterial phylogeny: the Escherichia coli case study.

    PubMed

    Escobar-Páramo, Patricia; Sabbagh, Audrey; Darlu, Pierre; Pradillon, Olivier; Vaury, Christelle; Denamur, Erick; Lecointre, Guillaume

    2004-01-01

    Phylogenetic reconstructions of bacterial species from DNA sequences are hampered by the existence of horizontal gene transfer. One possible way to overcome the confounding influence of such movement of genes is to identify and remove sequences which are responsible for significant character incongruence when compared to a reference dataset free of horizontal transfer (e.g., multilocus enzyme electrophoresis, restriction fragment length polymorphism, or random amplified polymorphic DNA) using the incongruence length difference (ILD) test of Farris et al. [Cladistics 10 (1995) 315]. As obtaining this "whole genome dataset" prior to the reconstruction of a phylogeny is clearly troublesome, we have tested alternative approaches allowing the release from such reference dataset, designed for a species with modest level of horizontal gene transfer, i.e., Escherichia coli. Eleven different genes available or sequenced in this work were studied in a set of 30 E. coli reference (ECOR) strains. Either using ILD to test incongruence between each gene against the all remaining (in this case 10) genes in order to remove sequences responsible for significant incongruence, or using just a simultaneous analysis without removals, gave robust phylogenies with slight topological differences. The use of the ILD test remains a suitable method for estimating the level of horizontal gene transfer in bacterial species. Supertrees also had suitable properties to extract the phylogeny of strains, because the way they summarize taxonomic congruence clearly limits the impact of individual gene transfers on the global topology. Furthermore, this work allowed a significant improvement of the accuracy of the phylogeny within E. coli. PMID:15022774

  12. Microbubble-Enhanced Ultrasound Gene Transfer into Fibroblast Cells

    NASA Astrophysics Data System (ADS)

    Hirayama, Kota; Kaneko, Yukio; Tei, Yuichi; Matsumoto, Yoichiro

    2007-05-01

    Ultrasound finds many applications in the medical field, including ultrasound imaging, non-invasive treatment of tumors and lithotripsy. Ultrasound also has a potential to deliver some therapeutic materials, such as genes, drugs or proteins into cells. It is known that microbubbles can improve the delivery efficiency. It is believed that therapeutic materials can pass through the cell membrane whose permeability is increased by microbubble destruction or the ultrasound pressure. In this study, we investigated the delivery of GFP plasmid gene into the fibroblast cells. Ultrasound (frequency = 2.1 MHz, duty cycle = 10%) was used to irradiate the cultured cells through a medium that contains microbubbles and GFP plasmid. GFP plasmid transfection could be easily observed by fluorescence microscopy. Ultrasound irradiation under a variety of conditions resulted in successful GFP plasmid delivery. Microbubbles enhanced GFP transfection, and conclusions were drawn as to the relationship between gene transfection and various ultrasound exposure parameters. We also investigated the effect of ultrasound intensity on cell viability.

  13. Gene Transfer into Rat Brain Using Adenoviral Vectors

    PubMed Central

    Puntel, Mariana; Kroeger, Kurt M.; Sanderson, Nicholas S.R.; Thomas, Clare E.; Castro, Maria G.; Lowenstein, Pedro R.

    2010-01-01

    Viral vector–mediated gene delivery is an attractive procedure for introducing genes into the brain, both for purposes of basic neuroscience research and to develop gene therapy for neurological diseases. Replication-defective adenoviruses possess many features which make them ideal vectors for this purpose—efficiently transducing terminally differentiated cells such as neurons and glial cells, resulting in high levels of transgene expression in vivo. Also, in the absence of anti-adenovirus immunity, these vectors can sustain very long-term transgene expression within the brain parenchyma. This unit provides protocols for the stereotactic injection of adenoviral vectors into the brain, followed by protocols to detect transgene expression or infiltrates of immune cells by immunocytochemistry or immunofluorescence. ELISPOT and neutralizing antibody assay methodologies are provided to quantitate the levels of cellular and humoral immune responses against adenoviruses. Quantitation of adenoviral vector genomes within the rat brain using qPCR is also described. Curr. Protoc. Neurosci. 50:4.24.1–4.24.49. © 2010 by John Wiley & Sons, Inc. PMID:20066657

  14. Designed self-assembly of molecular necklaces using host-stabilized charge-transfer interactions.

    PubMed

    Ko, Young Ho; Kim, Kyungpil; Kang, Jin-Koo; Chun, Hyungphil; Lee, Jae Wook; Sakamoto, Shigeru; Yamaguchi, Kentaro; Fettinger, James C; Kim, Kimoon

    2004-02-25

    A novel approach to the noncovalent synthesis of molecular necklaces successfully led to the first quantitative self-assembly of a molecular necklace [6]MN, in which five small rings are threaded on a large ring, from 10 components. Our strategy involves the host-guest complex formation between the molecular host cucurbit[8]uril (CB[8]) and a guest molecule in which an electron donor and an electron acceptor unit are connected by a rigid linker with a proper angle, to form a cyclic oligomer through the host-stabilized intermolecular charge-transfer (CT) complex formation. In the structure of the molecular necklace [6]MN, five molecules of the guest form a cyclic framework by the intermolecular CT interactions, on which five CB[8] molecules are threaded with an arrangement reminiscent of a five-fold propeller. The molecular necklace measures approximately 3.7 nm in diameter and approximately 1.8 nm in thickness. PMID:14971915

  15. Potential transfer of extended spectrum β-lactamase encoding gene, blashv18 gene, between Klebsiella pneumoniae in raw foods.

    PubMed

    Jung, Yangjin; Matthews, Karl R

    2016-12-01

    This study investigated the transfer frequency of the extended-spectrum β-lactamase-encoding gene (blaSHV18) among Klebsiella pneumoniae in tryptic soy broth (TSB), pasteurized milk, unpasteurized milk, alfalfa sprouts and chopped lettuce at defined temperatures. All transconjugants were characterized phenotypically and genotypically. KP04(ΔKM) and KP08(ΔKM) isolated from seed sprouts and KP342 were used as recipients in mating experiments with K. pneumoniae ATCC 700603 serving as the donor. In mating experiments, no transconjugants were detected at 4 °C in liquid media or chopped lettuce, but detected in all media tested at 15 °C, 24 °C, and 37 °C. At 24 °C, the transfer of blaSHV18 gene occurred more frequently in alfalfa sprouts (5.15E-04 transconjugants per recipient) and chopped lettuce (3.85E-05) than liquid media (1.08E-05). On chopped lettuce, transconjugants were not detected at day 1 post-mating at 15 °C, but observed on day 2 (1.43E-05). Transconjugants carried the blaSHV18 gene transferred from the donor and the virulence gene harbored by recipient. More importantly, a class 1 integrase gene and resistance to tetracycline, trimethoprim/sulfamethoxazole were co-transferred during mating. These quantitative results suggest that fresh produce exposed to temperature abuse may serve as a competent vehicle for the spread of gene encoding for antibiotic resistance, having a potential negative impact on human health. PMID:27554144

  16. Stability regulation of mRNA and the control of gene expression.

    PubMed

    Cheadle, Chris; Fan, Jinshui; Cho-Chung, Yoon S; Werner, Thomas; Ray, Jill; Do, Lana; Gorospe, Myriam; Becker, Kevin G

    2005-11-01

    Microarray technology has become highly valuable for identifying complex global changes in gene expression patterns. Standard techniques measure changes in total cellular poly(A) mRNA levels. The assumption that changes in gene expression as measured by these techniques are directly and well correlated with changes in rates of new gene synthesis form the basis of attempts to connect coordinated changes in gene expression with shared transcription regulatory elements. Yet systematic attempts at this approach remain difficult to demonstrate convincingly. One reason for this difficulty may result from the intricate convergence of both transcriptional and mRNA turnover events which, together, directly influence steady-state mRNA levels. Recent technical advances have led to the successful scale-up and application of nuclear run-on procedures directly to microarrays. This development has allowed a gene-by-gene comparison between new gene synthesis in the nucleus and measured changes in total cellular polyA mRNA. Results from these studies have begun to challenge the strict interpretation of changes in gene expression measured by conventional microarrays as being closely correlated with changes in mRNA transcription rate, but rather they tend to support the significant expansion of the role played by changes in mRNA stability regulation to standard analyses of gene expression. Gene expression profiles obtained from both polyA mRNA (whole-cell) and nuclear run-on (newly transcribed) RNA across a time course of one hour following the activation of human Jurkat T cells with PMA plus ionomycin revealed that regulation of mRNA stability may account for as much as 50% of all measurements of changes in total cellular polyA mRNA in this system. Stability regulation was inferred by the absence of corresponding regulation of nuclear gene transcription activity for groups of genes strongly regulated at the whole cell level and which were also resistant to inhibition by Actinomycin

  17. Improved performance and stability of field-effect transistors with polymeric residue-free graphene channel transferred by gold layer.

    PubMed

    Jang, Mi; Trung, Tran Quang; Jung, Jin-Heak; Kim, Bo-Yeong; Lee, Nae-Eung

    2014-03-01

    One of the most significant issues that occurs when applying chemical-vapor deposited (CVD) graphene (Gr) to various high-performance device applications is the result of polymeric residues. Polymeric residues remain on the Gr surface during Gr polymer support transfer to an arbitrary substrate, and these residues degrade CVD Gr electrical properties. In this paper, we propose that a thin layer of gold be used as a CVD Gr transfer layer, instead of a polymer support layer, to enable a polymer residue-free transfer. Comparative investigation of the surface morphological and qualitative analysis of residues on Gr surfaces and Gr field-effect transistors (GFETs) using two transfer methods demonstrates that gold-transferred Gr, with uniform, smooth, and clean surfaces, enable GFETs to perform better than Gr transferred by the polymer, polymethylmethacrylate (PMMA). In GFETs fabricated by the gold transfer method, field-effect carrier mobility was greatly enhanced and the position of the Dirac point was significantly reduced compared to GFETs fabricated by the PMMA transfer method. In addition, compared to the PMMA-transferred GFETs, the gold-transferred GFETs showed greatly increased stability with smaller hysteresis and higher resistance to gate bias stress effects. These results suggest that the gold transfer method for Gr provides significant improvements in GFET performance and reliability by minimizing the polymeric residues and defects on Gr. PMID:24448397

  18. Herpes simplex virus-mediated human hypoxanthine-guanine phosphoribosyltransferase gene transfer into neuronal cells

    SciTech Connect

    Palella, T.D.; Silverman, L.J.; Schroll, C.T.; Homa, F.L.; Levine, M.; Kelley, W.N.

    1988-01-01

    The virtually complete deficiency of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT) results in a devastating neurological disease, Lesch-Nyhan syndrome. Transfer of the HPRT gene into fibroblasts and lymphoblasts in vitro and into hematopoietic cells in vivo has been accomplished by other groups with retroviral-derived vectors. It appears to be necessary, however, to transfer the HPRT gene into neuronal cells to correct the neurological dysfunction of this disorder. The neurotropic virus herpes simplex virus type 1 has features that make it suitable for use as a vector to transfer the HPRT gene into neuronal tissue. This report describes the isolation of an HPRT-deficient rat neuroma cell line, designated B103-4C, and the construction of a recombinant herpes simplex virus type 1 that contained human HPRT cDNA. These recombinant viruses were used to infect B103-4C cells. Infected cells expressed HPRT activity which was human in origin.

  19. Adenoviral-Mediated Imaging of Gene Transfer Using a Somatostatin Receptor-Cytosine Deaminase Fusion Protein

    PubMed Central

    Lears, Kimberly A.; Parry, Jesse J.; Andrews, Rebecca; Nguyen, Kim; Wadas, Thaddeus J.; Rogers, Buck E.

    2015-01-01

    Suicide gene therapy is a process by which cells are administered a gene that encodes a protein capable of converting a nontoxic prodrug into an active toxin. Cytosine deaminase (CD) has been widely investigated as a means of suicide gene therapy due to the enzyme’s ability to convert the prodrug 5-fluorocytosine (5-FC) into the toxic compound 5-fluorouracil (5-FU). However, the extent of gene transfer is a limiting factor in predicting therapeutic outcome. The ability to monitor gene transfer, non-invasively, would strengthen the efficiency of therapy. In this regard, we have constructed and evaluated a replication-deficient adenovirus (Ad) containing the human somatostatin receptor subtype 2 (SSTR2) fused with a C-terminal yeast CD gene for the non-invasive monitoring of gene transfer and therapy. The resulting Ad (AdSSTR2-yCD) was evaluated in vitro in breast cancer cells to determine the function of the fusion protein. These studies demonstrated that the both the SSTR2 and yCD were functional in binding assays, conversion assays, and cytotoxicity assays. In vivo studies similarly demonstrated the functionality using conversion assays, biodistribution studies, and small animal positron-emission tomography (PET) imaging studies. In conclusion, the fusion protein has been validated as useful for the non-invasive imaging of yCD expression and will be evaluated in the future for monitoring yCD-based therapy. PMID:25837665

  20. Stable and Efficient Gene Transfer into the Retina Using an HIV-Based Lentiviral Vector

    NASA Astrophysics Data System (ADS)

    Miyoshi, Hiroyuki; Takahashi, Masayo; Gage, Fred H.; Verma, Inder M.

    1997-09-01

    The development of methods for efficient gene transfer to terminally differentiated retinal cells is important to study the function of the retina as well as for gene therapy of retinal diseases. We have developed a lentiviral vector system based on the HIV that can transduce terminally differentiated neurons of the brain in vivo. In this study, we have evaluated the ability of HIV vectors to transfer genes into retinal cells. An HIV vector containing a gene encoding the green fluorescent protein (GFP) was injected into the subretinal space of rat eyes. The GFP gene under the control of the cytomegalovirus promoter was efficiently expressed in both photoreceptor cells and retinal pigment epithelium. However, the use of the rhodopsin promoter resulted in expression predominantly in photoreceptor cells. Most successfully transduced eyes showed that photoreceptor cells in >80% of the area of whole retina expressed the GFP. The GFP expression persisted for at least 12 weeks with no apparent decrease. The efficient gene transfer into photoreceptor cells by HIV vectors will be useful for gene therapy of retinal diseases such as retinitis pigmentosa.

  1. Note: Space qualified photon counting detector for laser time transfer with picosecond precision and stability

    NASA Astrophysics Data System (ADS)

    Prochazka, Ivan; Kodet, Jan; Blazej, Josef

    2016-05-01

    The laser time transfer link is under construction for the European Space Agency in the frame of Atomic Clock Ensemble in Space. We have developed and tested the flying unit of the photon counting detector optimized for this space mission. The results are summarized in this Note. An extreme challenge was to build a detector package, which is rugged, small and which provides long term detection delay stability on picosecond level. The device passed successfully all the tests required for space missions on the low Earth orbits. The detector is extremely rugged and compact. Its long term detection delay stability is excellent, it is better than ±1 ps/day, in a sense of time deviation it is better than 0.5 ps for averaging times of 2000 s to several hours. The device is capable to operate in a temperature range of -55 °C up to +60 °C, the change of the detection delay with temperature is +0.5 ps/K. The device is ready for integration into the space structure now.

  2. Carbene-dichlorosilylene stabilized phosphinidenes exhibiting strong intramolecular charge transfer transition.

    PubMed

    Roy, Sudipta; Stollberg, Peter; Herbst-Irmer, Regine; Stalke, Dietmar; Andrada, Diego M; Frenking, Gernot; Roesky, Herbert W

    2015-01-14

    The unstable species dichlorosilylene was previously stabilized by carbene. The lone pair of electrons on the silicon atom of (carbene)SiCl2 can form a coordinate bond with metal-carbonyls. Herein we report that (carbene)SiCl2 can stabilize a phosphinidene (Ar-P, a carbone analogue) with the general formula carbene→SiCl2→P-Ar (carbene = cyclic alkyl(amino) carbene (cAAC; 2) and N-heterocyclic carbene (NHC; 3)). Compounds 2 and 3 are stable, isolable, and storable at 0 °C (2) to room temperature (3) under an inert atmosphere. The crystals of 2 and 3 are dark blue and red, respectively. The intense blue color of 2 arises due to the strong intramolecular charge transfer (ICT) transition from πSi═P→π*cAAC. The electronic structure and bonding of 2, 3 were studied by theoretical calculations. The HOMO of the molecule is located on the πSi═P bond, while the LUMO is located at the carbene moiety (cAAC or NHC). The dramatic change in color of these compounds from red (3, NHC) to blue (2, cAAC) is ascribed to the difference in energy of the LUMO within the carbenes (cAAC/NHC) due to a lower lying LUMO of cAAC. PMID:25539016

  3. Note: Space qualified photon counting detector for laser time transfer with picosecond precision and stability.

    PubMed

    Prochazka, Ivan; Kodet, Jan; Blazej, Josef

    2016-05-01

    The laser time transfer link is under construction for the European Space Agency in the frame of Atomic Clock Ensemble in Space. We have developed and tested the flying unit of the photon counting detector optimized for this space mission. The results are summarized in this Note. An extreme challenge was to build a detector package, which is rugged, small and which provides long term detection delay stability on picosecond level. The device passed successfully all the tests required for space missions on the low Earth orbits. The detector is extremely rugged and compact. Its long term detection delay stability is excellent, it is better than ±1 ps/day, in a sense of time deviation it is better than 0.5 ps for averaging times of 2000 s to several hours. The device is capable to operate in a temperature range of -55 °C up to +60 °C, the change of the detection delay with temperature is +0.5 ps/K. The device is ready for integration into the space structure now. PMID:27250477

  4. Photoregulation of a phytochrome gene promoter from oat transferred into rice by particle bombardment.

    PubMed Central

    Bruce, W B; Christensen, A H; Klein, T; Fromm, M; Quail, P H

    1989-01-01

    The regulatory photoreceptor phytochrome controls the transcription of its own phy genes in a negative feedback fashion. We have exploited microprojectile-mediated gene transfer to develop a rapid transient expression assay system for the study of DNA sequences involved in the phytochrome-regulated expression of these genes. The 5'-flanking sequence and part of the structural region of an oat phy gene have been fused to a reporter coding sequence (chloramphenicol acetyltransferase, CAT) and introduced into intact darkgrown seedlings by using high-velocity microprojectiles. Expression is assayable in less than 24 hr from bombardment. The introduced oat phy-CAT fusion gene is expressed and down-regulated by white light in barley, rice, and oat, whereas no expression is detected in three dicots tested, tobacco, cucumber, and Arabidopsis thaliana. In bombarded rice shoots, red/far-red light-reversible repression of expression of the heterologous oat phy-CAT gene shows that it is regulated by phytochrome in a manner parallel to that of the endogenous rice phy genes. These data indicate that the transduction pathway components and promoter sequences involved in autoregulation of phy expression have been evolutionarily conserved between oat and rice. The experiments show the feasibility of using high-velocity microprojectile-mediated gene transfer for the rapid analysis of light-controlled monocot gene promoters in monocot tissues that until now have been recalcitrant to such studies. Images PMID:2602370

  5. Horizontal Transfer of Plasmid-Mediated Cephalosporin Resistance Genes in the Intestine of Houseflies (Musca domestica).

    PubMed

    Fukuda, Akira; Usui, Masaru; Okubo, Torahiko; Tamura, Yutaka

    2016-06-01

    Houseflies are a mechanical vector for various types of bacteria, including antimicrobial-resistant bacteria (ARB). If the intestine of houseflies is a suitable site for the transfer of antimicrobial resistance genes (ARGs), houseflies could also serve as a biological vector for ARB. To clarify whether cephalosporin resistance genes are transferred efficiently in the housefly intestine, we compared with conjugation experiments in vivo (in the intestine) and in vitro by using Escherichia coli with eight combinations of four donor and two recipient strains harboring plasmid-mediated cephalosporin resistance genes and chromosomal-encoded rifampicin resistance genes, respectively. In the in vivo conjugation experiment, houseflies ingested donor strains for 6 hr and then recipient strains for 3 hr, and 24 hr later, the houseflies were surface sterilized and analyzed. In vitro conjugation experiments were conducted using the broth-mating method. In 3/8 combinations, the in vitro transfer frequency (Transconjugants/Donor) was ≥1.3 × 10(-4); the in vivo transfer rates of cephalosporin resistance genes ranged from 2.0 × 10(-4) to 5.7 × 10(-5). Moreover, cephalosporin resistance genes were transferred to other species of enteric bacteria of houseflies such as Achromobacter sp. and Pseudomonas fluorescens. These results suggest that houseflies are not only a mechanical vector for ARB but also a biological vector for the occurrence of new ARB through the horizontal transfer of ARGs in their intestine. PMID:26683492

  6. hnRNP-U enhances the expression of specific genes by stabilizing mRNA.

    PubMed

    Yugami, Masato; Kabe, Yasuaki; Yamaguchi, Yuki; Wada, Tadashi; Handa, Hiroshi

    2007-01-01

    Heterogeneous nuclear ribonucleoproteins (hnRNPs) are thought to be involved in pre-mRNA processing. hnRNP-U, also termed scaffold attachment factor A (SAF-A), binds to pre-mRNA and nuclear matrix/scaffold attachment region DNA elements. However, its role in the regulation of gene expression is as yet poorly understood. In the present study, we show that hnRNP-U specifically enhances the expression of tumor necrosis factor alpha mRNA by increasing its stability, possibly through binding to the 3' untranslated region. We also show that hnRNP-U enhances the expression of several other genes as well, including GADD45A, HEXIM1, HOXA2, IER3, NHLH2, and ZFY, by binding to and stabilizing these mRNAs. These results suggest that hnRNP-U enhances the expression of specific genes by regulating mRNA stability. PMID:17174306

  7. Stability improvement of an operational two-way satellite time and frequency transfer system

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Jiun; Fujieda, Miho; Takiguchi, Hiroshi; Tseng, Wen-Hung; Tsao, Hen-Wai

    2016-04-01

    To keep national time accurately coherent with coordinated universal time, many national metrology institutes (NMIs) use two-way satellite time and frequency transfer (TWSTFT) to continuously measure the time difference with other NMIs over an international baseline. Some NMIs have ultra-stable clocks with stability better than 10-16. However, current operational TWSTFT can only provide frequency uncertainty of 10-15 and time uncertainty of 1 ns, which is inadequate. The uncertainty is dominated by the short-term stability and the diurnals, i.e. the measurement variation with a period of one day. The aim of this work is to improve the stability of operational TWSTFT systems without additional transmission, bandwidth or increase in signal power. A software-defined receiver (SDR) comprising a high-resolution correlator and successive interference cancellation associated with open-loop configuration as the TWSTFT receiver reduces the time deviation from 140 ps to 73 ps at averaging time of 1 h, and occasionally suppresses diurnals. To study the source of the diurnals, TWSTFT is performed using a 2  ×  2 earth station (ES) array. Consequently, some ESs sensitive to temperature variation are identified, and the diurnals are significantly reduced by employing insensitive ESs. Hence, the operational TWSTFT using the proposed SDR with insensitive ESs achieves time deviation to 41 ps at 1 h, and 80 ps for averaging times from 1 h to 20 h.

  8. Charge Transfer Stabilization of Late Transition Metal Oxide Nanoparticles on a Layered Niobate Support.

    PubMed

    Strayer, Megan E; Senftle, Thomas P; Winterstein, Jonathan P; Vargas-Barbosa, Nella M; Sharma, Renu; Rioux, Robert M; Janik, Michael J; Mallouk, Thomas E

    2015-12-30

    Interfacial interactions between late transition metal/metal oxide nanoparticles and oxide supports impact catalytic activity and stability. Here, we report the use of isothermal titration calorimetry (ITC), electron microscopy and density functional theory (DFT) to explore periodic trends in the heats of nanoparticle-support interactions for late transition metal and metal oxide nanoparticles on layered niobate and silicate supports. Data for Co(OH)2, hydroxyiridate-capped IrOx·nH2O, Ni(OH)2, CuO, and Ag2O nanoparticles were added to previously reported data for Rh(OH)3 grown on nanosheets of TBA0.24H0.76Ca2Nb3O10 and a layered silicate. ITC measurements showed stronger bonding energies in the order Ag < Cu ≈ Ni ≈ Co < Rh < Ir on the niobate support, as expected from trends in M-O bond energies. Nanoparticles with exothermic heats of interaction were stabilized against sintering. In contrast, ITC measurements showed endothermic interactions of Cu, Ni, and Rh oxide/hydroxide nanoparticles with the silicate and poor resistance to sintering. These trends in interfacial energies were corroborated by DFT calculations using single-atom and four-atom cluster models of metal/metal oxide nanoparticles. Density of states and charge density difference calculations reveal that strongly bonded metals (Rh, Ir) transfer d-electron density from the adsorbed cluster to niobium atoms in the support; this mixing is absent in weakly binding metals, such as Ag and Au, and in all metals on the layered silicate support. The large differences between the behavior of nanoparticles on niobate and silicate supports highlight the importance of d-orbital interactions between the nanoparticle and support in controlling the nanoparticles' stability. PMID:26651875

  9. Improved retroviral suicide gene transfer in colon cancer cell lines after cell synchronization with methotrexate

    PubMed Central

    2011-01-01

    Background Cancer gene therapy by retroviral vectors is mainly limited by the level of transduction. Retroviral gene transfer requires target cell division. Cell synchronization, obtained by drugs inducing a reversible inhibition of DNA synthesis, could therefore be proposed to precondition target cells to retroviral gene transfer. We tested whether drug-mediated cell synchronization could enhance the transfer efficiency of a retroviral-mediated gene encoding herpes simplex virus thymidine kinase (HSV-tk) in two colon cancer cell lines, DHDK12 and HT29. Methods Synchronization was induced by methotrexate (MTX), aracytin (ara-C) or aphidicolin. Gene transfer efficiency was assessed by the level of HSV-TK expression. Transduced cells were driven by ganciclovir (GCV) towards apoptosis that was assessed using annexin V labeling by quantitative flow cytometry. Results DHDK12 and HT29 cells were synchronized in S phase with MTX but not ara-C or aphidicolin. In synchronized DHDK12 and HT29 cells, the HSV-TK transduction rates were 2 and 1.5-fold higher than those obtained in control cells, respectively. Furthermore, the rate of apoptosis was increased two-fold in MTX-treated DHDK12 cells after treatment with GCV. Conclusions Our findings indicate that MTX-mediated synchronization of target cells allowed a significant improvement of retroviral HSV-tk gene transfer, resulting in an increased cell apoptosis in response to GCV. Pharmacological control of cell cycle may thus be a useful strategy to optimize the efficiency of retroviral-mediated cancer gene therapy. PMID:21970612

  10. Transferring Gus gene into intact rice cells by low energy ion beam

    NASA Astrophysics Data System (ADS)

    Zengliang, Yu; Jianbo, Yang; Yuejin, Wu; Beijiu, Cheng; Jianjun, He; Yuping, Huo

    1993-06-01

    A new technique of transferring genes by low energy ion beam has been reported in this paper. The Gus and CAT (chloramphenicol acetyltransferase) genes, as "foreign" genetic materials, were introduced into the suspension cells and ripe embryos or rice by implantation of 20-30 keV Ar + at doses ranging from 1 × 10 15 to 4 × 10 15 ions/cm 2. The activities of CAT and Gus were detected in the cells and embryos after several weeks. The results indicate that the transfer was a success.

  11. Efficient Gene Transfer and Targeted Mutagenesis in Fusobacterium nucleatum

    PubMed Central

    Haake, Susan Kinder; Yoder, Sean; Gerardo, Sharon Hunt

    2006-01-01

    Fusobacterium nucleatum is a Gram-negative anaerobe important in dental biofilm ecology and infectious diseases with significant societal impact. The lack of efficient genetic systems has hampered molecular analyses in this microorganism. We previously reported construction of a shuttle plasmid, pHS17, using the native fusobacterial plasmid pFN1 and an erythromycin resistance cassette. However, the host range of pHS17 was restricted to F. nucleatum, ATCC 10953 and the transformation efficiency was limited. This study was undertaken to improve genetic systems for molecular analysis in F. nucleatum. We identified a second F. nucleatum strain, ATCC 23726, which is transformed with improved efficiency compared to ATCC 10953. Two novel second generation pFN1-based shuttle plasmids, pHS23 and pHS30, were developed and enable transformation of ATCC 23726 at 6.2 x 104 and 1.5 x 106 transformants/microgram of plasmid DNA, respectively. The transformation efficiency of pHS30, which harbors a catP gene conferring resistance to chloramphenicol, was more than 1,000-fold greater than that of pHS17. The improved transformation efficiency facilitated disruption of the chromosomal rnr gene using a suicide plasmid pHS19, the first demonstration of targeted mutagenesis in F. nucleatum. These results provide significant advances in the development of systems for molecular analysis in F. nucleatum. PMID:16115683

  12. Nano-vectors for efficient liver specific gene transfer

    PubMed Central

    Pathak, Atul; Vyas, Suresh P; Gupta, Kailash C

    2008-01-01

    Recent progress in nanotechnology has triggered the site specific drug/gene delivery research and gained wide acknowledgment in contemporary DNA therapeutics. Amongst various organs, liver plays a crucial role in various body functions and in addition, the site is a primary location of metastatic tumor growth. In past few years, a plethora of nano-vectors have been developed and investigated to target liver associated cells through receptor mediated endocytosis. This emerging paradigm in cellular drug/gene delivery provides promising approach to eradicate genetic as well as acquired diseases affecting the liver. The present review provides a comprehensive overview of potential of various delivery systems, viz., lipoplexes, liposomes, polyplexes, nanoparticles and so forth to selectively relocate foreign therapeutic DNA into liver specific cell type via the receptor mediated endocytosis. Various receptors like asialoglycoprotein receptors (ASGP-R) provide unique opportunity to target liver parenchymal cells. The results obtained so far reveal tremendous promise and offer enormous options to develop novel DNA-based pharmaceuticals for liver disorders in near future. PMID:18488414

  13. In situ gene transfer and suicide gene therapy of gastric cancer induced by N-ethyl-N'-nitro-N-nitrosoguanidine in dogs.

    PubMed

    Matsukura, N; Hoshino, A; Igarashi, T; Hasegawa, H; Okino, T; Onda, M; Iijima, O; Akiyama, K; Goto, T; Takubo, K; Suzuki, S; Shimada, T

    1999-09-01

    Gene therapy could potentially revolutionize the treatment of gastrointestinal (GI) tract cancer. The aim of this study was to establish a practical method of gene transfer which would be applicable to human gastric cancer. Retrovirus or/and adenovirus vectors carrying the lacZ marker gene were transferred in situ by needle through an endoscopic biopsy channel into primary gastric cancer in six male beagle dogs that had been treated with N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). In addition, an adenovirus vector carrying the herpes simplex virus thymidine kinase (Ad.CAGHSV-TK) gene was introduced in situ into cancer tissues in the stomach of three dogs, and the animals were treated with intravenous ganciclovir (GCV). Retrovirus-producing cells which expressed the lacZ gene were specifically localized to the injection site in the stomach. The lacZ gene was more widely transferred into the tumor by the adenovirus vector than by retrovirus-producing cells. Improvement of the needle used for gene transfer and the use of multiple injections per tumor led to more diffuse transfer of the vector into the tumor. The Ad.CAGlacZ gene was also transferred into regional lymph nodes of the stomach. Moderate to diffuse degeneration of the primary cancer tissues of the stomach was found after Ad.CAGHSV-TK/GCV gene therapy. Moreover, almost complete tissue degeneration was observed in the regional lymph nodes of the stomach. An adverse effect of HSV-TK/GCV gene therapy was acute hepatotoxicity, which was not found after Ad.CAGlacZ gene transfer, but was found after high-titer Ad.CAGHSV-TK gene transfer followed by GCV. These findings suggest that in situ gene transfer of a suicide gene followed by prodrug treatment may be applicable not only to primary tumors, but also to lymph node metastases of gastric cancer, though further study of both beneficial and adverse effects is required before clinical usage. PMID:10551335

  14. Regulatory and ethical issues for phase I in utero gene transfer studies.

    PubMed

    Strong, Carson

    2011-11-01

    Clinical gene transfer research has involved adult and child subjects, and it is expected that gene transfer in fetal subjects will occur in the future. Some genetic diseases have serious adverse effects on the fetus before birth, and there is hope that prenatal gene therapy could prevent such disease progression. Research in animal models of prenatal gene transfer is actively being pursued. The prospect of human phase I in utero gene transfer studies raises important regulatory and ethical issues. One issue not previously addressed arises in applying U.S. research regulations to such studies. Specifically, current regulations state that research involving greater than minimal risk to the fetus and no prospect of direct benefit to the fetus or pregnant woman is not permitted. Phase I studies will involve interventions such as needle insertions through the uterus, which carry risks to the fetus including spontaneous abortion and preterm birth. It is possible that these risks will be regarded as exceeding minimal. Also, some regard the probability of therapeutic benefit in phase I studies to be so low that these studies do not satisfy the regulatory requirement that they "hold out the prospect of direct benefit" to subjects. On the basis of these considerations, investigators and institutional review boards might reasonably conclude that some phase I in utero studies are not to be permitted. This paper identifies considerations that are relevant to such judgments and explores ethically acceptable ways in which phase I studies can be designed so that they are permitted by the regulations. PMID:21846200

  15. Peptide nanofibrils boost retroviral gene transfer and provide a rapid means for concentrating viruses

    NASA Astrophysics Data System (ADS)

    Yolamanova, Maral; Meier, Christoph; Shaytan, Alexey K.; Vas, Virag; Bertoncini, Carlos W.; Arnold, Franziska; Zirafi, Onofrio; Usmani, Shariq M.; Müller, Janis A.; Sauter, Daniel; Goffinet, Christine; Palesch, David; Walther, Paul; Roan, Nadia R.; Geiger, Hartmut; Lunov, Oleg; Simmet, Thomas; Bohne, Jens; Schrezenmeier, Hubert; Schwarz, Klaus; Ständker, Ludger; Forssmann, Wolf-Georg; Salvatella, Xavier; Khalatur, Pavel G.; Khokhlov, Alexei R.; Knowles, Tuomas P. J.; Weil, Tanja; Kirchhoff, Frank; Münch, Jan

    2013-02-01

    Inefficient gene transfer and low virion concentrations are common limitations of retroviral transduction. We and others have previously shown that peptides derived from human semen form amyloid fibrils that boost retroviral gene delivery by promoting virion attachment to the target cells. However, application of these natural fibril-forming peptides is limited by moderate efficiencies, the high costs of peptide synthesis, and variability in fibril size and formation kinetics. Here, we report the development of nanofibrils that self-assemble in aqueous solution from a 12-residue peptide, termed enhancing factor C (EF-C). These artificial nanofibrils enhance retroviral gene transfer substantially more efficiently than semen-derived fibrils or other transduction enhancers. Moreover, EF-C nanofibrils allow the concentration of retroviral vectors by conventional low-speed centrifugation, and are safe and effective, as assessed in an ex vivo gene transfer study. Our results show that EF-C fibrils comprise a highly versatile, convenient and broadly applicable nanomaterial that holds the potential to significantly facilitate retroviral gene transfer in basic research and clinical applications.

  16. Different gene transfer methods at the very early, early, late and whole embryonic stages in chicken.

    PubMed

    Gong, Ping; Yang, Y P; Yang, Y; Feng, Yan P; Li, S J; Peng, Xiu L; Gong, Y Z

    2012-12-01

    New technologies in gene transfer combined with experimental embryology make the chicken embryo an excellent model system for gene function studies. The techniques of in ovo electroporation, in vitro culture for ex ovo electroporation and retrovirus-mediated gene transfer have already been fully developed in chicken. Yet to our knowledge, there are no definite descriptions on the features and application scopes of these techniques. The survival rates of different in vitro culture methods were compared and the EGFP expression areas of different gene transfer techniques were explored. It was that the optimal timings of removing embryo for EC culture and Petri dish system was at E1.5 and E2.5, respectively; and optimal timing of injecting retrovirus is at E0. Results indicated that the EC culture, in ovo electroporation, the Petri dish system and retrovirus-mediated method are, respectively, suitable for the very early, early, late and whole embryonic stages in chicken. Comparison of different gene transfer methods and establishment of optimal timings are expected to provide a better choice of the efficient method for a particular experiment. PMID:23134602

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

    PubMed Central

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

    2015-01-01

    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. PMID:26670247

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Targeting the urokinase plasminogen activator receptor enhances gene transfer to human airway epithelia

    PubMed Central

    Drapkin, Paola T.; O’Riordan, Catherine R.; Yi, Su Min; Chiorini, John A.; Cardella, Jonathan; Zabner, Joseph; Welsh, Michael J.

    2000-01-01

    Developing gene therapy for cystic fibrosis has been hindered by limited binding and endocytosis of vectors by human airway epithelia. Here we show that the apical membrane of airway epithelia express the urokinase plasminogen activator receptor (uPAR). Urokinase plasminogen activator (uPA), or a 7-residue peptide derived from this protein (u7-peptide), bound the receptor and stimulated apical endocytosis. Both ligands enhanced gene transfer by nonspecifically bound adenovirus and adeno-associated virus vectors and by a modified adenovirus vector that had been coupled to the u7-peptide. These data provide the first evidence that targeting an apical receptor can circumvent the two most important barriers to gene transfer in airway epithelia. Thus, the uPA/uPAR system may offer significant advantages for delivering genes and other pharmaceuticals to airway epithelia. PMID:10712430

  20. Targeting the urokinase plasminogen activator receptor enhances gene transfer to human airway epithelia.

    PubMed

    Drapkin, P T; O'Riordan, C R; Yi, S M; Chiorini, J A; Cardella, J; Zabner, J; Welsh, M J

    2000-03-01

    Developing gene therapy for cystic fibrosis has been hindered by limited binding and endocytosis of vectors by human airway epithelia. Here we show that the apical membrane of airway epithelia express the urokinase plasminogen activator receptor (uPAR). Urokinase plasminogen activator (uPA), or a 7-residue peptide derived from this protein (u7-peptide), bound the receptor and stimulated apical endocytosis. Both ligands enhanced gene transfer by nonspecifically bound adenovirus and adeno-associated virus vectors and by a modified adenovirus vector that had been coupled to the u7-peptide. These data provide the first evidence that targeting an apical receptor can circumvent the two most important barriers to gene transfer in airway epithelia. Thus, the uPA/uPAR system may offer significant advantages for delivering genes and other pharmaceuticals to airway epithelia. PMID:10712430

  1. Gene conversion plays the major role in controlling the stability of large tandem repeats in yeast.

    PubMed Central

    Gangloff, S; Zou, H; Rothstein, R

    1996-01-01

    The genomic stability of the rDNA tandem array in yeast is tightly controlled to allow sequence homogenization and at the same time prevent deleterious rearrangements. In our study, we show that gene conversion, and not unequal sister chromatid exchange, is the predominant recombination mechanism regulating the expansion and contraction of the rDNA array. Furthermore, we found that RAD52, which is essential for gene conversion, is required for marker duplication stimulated in the absence of the two yeast type I topoisomerases. Our results have implications for the mechanisms regulating genomic stability of repetitive sequence families found in all eukaryotes. Images PMID:8612596

  2. Rate of gene transfer from mitochondria to nucleus: effects of cytoplasmic inheritance system and intensity of intracellular competition.

    PubMed

    Yamauchi, Atsushi

    2005-11-01

    Endosymbiotic theory states that mitochondria originated as bacterial intracellular symbionts, the size of the mitochondrial genome gradually reducing over a long period owing to, among other things, gene transfer from the mitochondria to the nucleus. Such gene transfer was observed in more genes in animals than in plants, implying a higher transfer rate of animals. The evolution of gene transfer may have been affected by an intensity of intracellular competition among organelle strains and the organelle inheritance system of the organism concerned. This article reveals a relationship between those factors and the gene transfer rate from organelle to nuclear genomes, using a mathematical model. Mutant mitochondria that lose a certain gene by deletion are considered to replicate more rapidly than normal ones, resulting in an advantage in intracellular competition. If the competition is intense, heteroplasmic individuals possessing both types of mitochondria change to homoplasmic individuals including mutant mitochondria only, with high probability. According to the mathematical model, it was revealed that the rate of gene transfer from mitochondria to the nucleus can be affected by three factors, the intensity of intracellular competition, the probability of paternal organelle transmission, and the effective population size. The gene transfer rate tends to increase with decreasing intracellular competition, increasing paternal organelle transmission, and decreasing effective population size. Intense intracellular competition tends to suppress gene transfer because it is likely to exclude mutant mitochondria that lose the essential gene due to the production of lethal individuals. PMID:16079242

  3. Liver Gene Transfer of Interkeukin-15 Constructs That Become Part of Circulating High Density Lipoproteins for Immunotherapy

    PubMed Central

    Ochoa, Maria C.; Fioravanti, Jessica; Duitman, Erwin H.; Medina-Echeverz, Jose; Palazon, Asis; Arina, Ainhoa; Dubrot, Juan; Alfaro, Carlos; Morales-Kastresana, Aizea; Murillo, Oihana; Hervas-Stubbs, Sandra; Prieto, Jesus

    2012-01-01

    Apolipoprotein A-I (Apo A-I) is a major component of high density lipoproteins (HDL) that transport cholesterol in circulation. We have constructed an expression plasmid encoding a chimeric molecule encompassing interleukin-15 (IL-15) and Apo A-I (pApo-hIL15) that was tested by hydrodynamic injections into mice and was co-administered with a plasmid encoding the sushi domain of IL-15Rα (pSushi) in order to enhance IL-15 trans-presentation and thereby bioactivity. The pharmacokinetics of the Apo A-I chimeric protein were much longer than non-stabilized IL-15 and its bioactivity was enhanced in combination with IL-15Rα Sushi. Importantly, the APO-IL-15 fusion protein was incorporated in part into circulating HDL. Liver gene transfer of these constructs increased NK and memory-phenotype CD8 lymphocyte numbers in peripheral blood, spleen and liver as a result of proliferation documented by CFSE dilution and BrdU incorporation. Moreover, the gene transfer procedure partly rescued the NK and memory T-cell deficiency observed in IL-15Rα−/− mice. pApo-hIL15+ pSushi gene transfer to the liver showed a modest therapeutic activity against subcutaneously transplanted MC38 colon carcinoma tumors, that was more evident when tumors were set up as liver metastases. The improved pharmacokinetic profile and the strong biological activity of APO-IL-15 fusion protein holds promise for further development in combination with other immunotherapies. PMID:23285013

  4. Liver gene transfer of interkeukin-15 constructs that become part of circulating high density lipoproteins for immunotherapy.

    PubMed

    Ochoa, Maria C; Fioravanti, Jessica; Duitman, Erwin H; Medina-Echeverz, Jose; Palazon, Asis; Arina, Ainhoa; Dubrot, Juan; Alfaro, Carlos; Morales-Kastresana, Aizea; Murillo, Oihana; Hervas-Stubbs, Sandra; Prieto, Jesus; Berraondo, Pedro; Melero, Ignacio

    2012-01-01

    Apolipoprotein A-I (Apo A-I) is a major component of high density lipoproteins (HDL) that transport cholesterol in circulation. We have constructed an expression plasmid encoding a chimeric molecule encompassing interleukin-15 (IL-15) and Apo A-I (pApo-hIL15) that was tested by hydrodynamic injections into mice and was co-administered with a plasmid encoding the sushi domain of IL-15Rα (pSushi) in order to enhance IL-15 trans-presentation and thereby bioactivity. The pharmacokinetics of the Apo A-I chimeric protein were much longer than non-stabilized IL-15 and its bioactivity was enhanced in combination with IL-15Rα Sushi. Importantly, the APO-IL-15 fusion protein was incorporated in part into circulating HDL. Liver gene transfer of these constructs increased NK and memory-phenotype CD8 lymphocyte numbers in peripheral blood, spleen and liver as a result of proliferation documented by CFSE dilution and BrdU incorporation. Moreover, the gene transfer procedure partly rescued the NK and memory T-cell deficiency observed in IL-15Rα(-/-) mice. pApo-hIL15+ pSushi gene transfer to the liver showed a modest therapeutic activity against subcutaneously transplanted MC38 colon carcinoma tumors, that was more evident when tumors were set up as liver metastases. The improved pharmacokinetic profile and the strong biological activity of APO-IL-15 fusion protein holds promise for further development in combination with other immunotherapies. PMID:23285013

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

    SciTech Connect

    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.

  6. Inferring gene duplications, transfers and losses can be done in a discrete framework.

    PubMed

    Ranwez, Vincent; Scornavacca, Celine; Doyon, Jean-Philippe; Berry, Vincent

    2016-06-01

    In the field of phylogenetics, the evolutionary history of a set of organisms is commonly depicted by a species tree-whose internal nodes represent speciation events-while the evolutionary history of a gene family is depicted by a gene tree-whose internal nodes can also represent macro-evolutionary events such as gene duplications and transfers. As speciation events are only part of the events shaping a gene history, the topology of a gene tree can show incongruences with that of the corresponding species tree. These incongruences can be used to infer the macro-evolutionary events undergone by the gene family. This is done by embedding the gene tree inside the species tree and hence providing a reconciliation of those trees. In the past decade, several parsimony-based methods have been developed to infer such reconciliations, accounting for gene duplications ([Formula: see text]), transfers ([Formula: see text]) and losses ([Formula: see text]). The main contribution of this paper is to formally prove an important assumption implicitly made by previous works on these reconciliations, namely that solving the (maximum) parsimony [Formula: see text] reconciliation problem in the discrete framework is equivalent to finding a most parsimonious [Formula: see text] scenario in the continuous framework. In the process, we also prove several intermediate results that are useful on their own and constitute a theoretical toolbox that will likely facilitate future theoretical contributions in the field. PMID:26337177

  7. Horizontal Transfer of a Nitrate Assimilation Gene Cluster and Ecological Transitions in Fungi: A Phylogenetic Study

    PubMed Central

    Slot, Jason C.; Hibbett, David S.

    2007-01-01

    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(P)H-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. PMID:17971860

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

    PubMed

    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. PMID:19584142

  9. Preventing High Fat Diet-induced Obesity and Improving Insulin Sensitivity through Neuregulin 4 Gene Transfer

    PubMed Central

    Ma, Yongjie; Gao, Mingming; Liu, Dexi

    2016-01-01

    Neuregulin 4 (NRG4), an epidermal growth factor-like signaling molecule, plays an important role in cell-to-cell communication during tissue development. Its function to regulate energy metabolism has recently been reported. This current study was designed to assess the preventive and therapeutic effects of NRG4 overexpression on high fat diet (HFD)-induced obesity. Using the hydrodynamic gene transfer method, we demonstrate that Nrg4 gene transfer in mice suppressed the development of diet-induced obesity, but did not affect pre-existing adiposity and body weight in obese mice. Nrg4 gene transfer curbed HFD-induced hepatic steatosis by inhibiting lipogenesis and PPARγ-mediated lipid storage. Concurrently, overexpression of NRG4 reduced chronic inflammation in both preventive and treatment studies, evidenced by lower mRNA levels of macrophage marker genes including F4/80, Cd68, Cd11b, Cd11c, and macrophage chemokine Mcp1, resulting in improved insulin sensitivity. Collectively, these results demonstrate that overexpression of the Nrg4 gene by hydrodynamic gene delivery prevents HFD-induced weight gain and fatty liver, alleviates obesity-induced chronic inflammation and insulin resistance, and supports the health benefits of NRG4 in managing obesity and obesity-associated metabolic disorders. PMID:27184920

  10. Preventing High Fat Diet-induced Obesity and Improving Insulin Sensitivity through Neuregulin 4 Gene Transfer.

    PubMed

    Ma, Yongjie; Gao, Mingming; Liu, Dexi

    2016-01-01

    Neuregulin 4 (NRG4), an epidermal growth factor-like signaling molecule, plays an important role in cell-to-cell communication during tissue development. Its function to regulate energy metabolism has recently been reported. This current study was designed to assess the preventive and therapeutic effects of NRG4 overexpression on high fat diet (HFD)-induced obesity. Using the hydrodynamic gene transfer method, we demonstrate that Nrg4 gene transfer in mice suppressed the development of diet-induced obesity, but did not affect pre-existing adiposity and body weight in obese mice. Nrg4 gene transfer curbed HFD-induced hepatic steatosis by inhibiting lipogenesis and PPARγ-mediated lipid storage. Concurrently, overexpression of NRG4 reduced chronic inflammation in both preventive and treatment studies, evidenced by lower mRNA levels of macrophage marker genes including F4/80, Cd68, Cd11b, Cd11c, and macrophage chemokine Mcp1, resulting in improved insulin sensitivity. Collectively, these results demonstrate that overexpression of the Nrg4 gene by hydrodynamic gene delivery prevents HFD-induced weight gain and fatty liver, alleviates obesity-induced chronic inflammation and insulin resistance, and supports the health benefits of NRG4 in managing obesity and obesity-associated metabolic disorders. PMID:27184920

  11. Gene Transfer and the Reconstruction of Life's Early History from Genomic Data

    NASA Astrophysics Data System (ADS)

    Gogarten, J. Peter; Fournier, Gregory; Zhaxybayeva, Olga

    2008-03-01

    The metaphor of the unique and strictly bifurcating tree of life, suggested by Charles Darwin, needs to be replaced (or at least amended) to reflect and include processes that lead to the merging of and communication between independent lines of descent. Gene histories include and reflect processes such as gene transfer, symbioses and lineage fusion. No single molecule can serve as a proxy for the tree of life. Individual gene histories can be reconstructed from the growing molecular databases containing sequence and structural information. With some simplifications these gene histories can be represented by furcating trees; however, merging these gene histories into web-like organismal histories, including the transfer of metabolic pathways and cell biological innovations from now-extinct lineages, has yet to be accomplished. Because of these difficulties in interpreting the record retained in molecular sequences, correlations with biochemical fossils and with the geological record need to be interpreted with caution. Advances to detect and pinpoint transfer events promise to untangle at least a few of the intertwined histories of individual genes within organisms and trace them to the organismal ancestors. Furthermore, analysis of the shape of molecular phylogenetic trees may point towards organismal radiations that might reflect early mass extinction events that occurred on a planetary scale.

  12. Gene Transfer and the Reconstruction of Life's Early History from Genomic Data

    NASA Astrophysics Data System (ADS)

    Gogarten, J. Peter; Fournier, Gregory; Zhaxybayeva, Olga

    The metaphor of the unique and strictly bifurcating tree of life, suggested by Charles Darwin, needs to be replaced (or at least amended) to reflect and include processes that lead to the merging of and communication between independent lines of descent. Gene histories include and reflect processes such as gene transfer, symbioses and lineage fusion. No single molecule can serve as a proxy for the tree of life. Individual gene histories can be reconstructed from the growing molecular databases containing sequence and structural information. With some simplifications these gene histories can be represented by furcating trees; however, merging these gene histories into web-like organismal histories, including the transfer of metabolic pathways and cell biological innovations from now-extinct lineages, has yet to be accomplished. Because of these difficulties in interpreting the record retained in molecular sequences, correlations with biochemical fossils and with the geological record need to be interpreted with caution. Advances to detect and pinpoint transfer events promise to untangle at least a few of the intertwined histories of individual genes within organisms and trace them to the organismal ancestors. Furthermore, analysis of the shape of molecular phylogenetic trees may point towards organismal radiations that might reflect early mass extinction events that occurred on a planetary scale.

  13. AAV Vectors for Cardiac Gene Transfer: Experimental Tools and Clinical Opportunities

    PubMed Central

    Pacak, Christina A; Byrne, Barry J

    2011-01-01

    Since the first demonstration of in vivo gene transfer into myocardium there have been a series of advancements that have driven the evolution of cardiac gene delivery from an experimental tool into a therapy currently at the threshold of becoming a viable clinical option. Innovative methods have been established to address practical challenges related to tissue-type specificity, choice of delivery vehicle, potency of the delivered material, and delivery route. Most importantly for therapeutic purposes, these strategies are being thoroughly tested to ensure safety of the delivery system and the delivered genetic material. This review focuses on the development of recombinant adeno-associated virus (rAAV) as one of the most valuable cardiac gene transfer agents available today. Various forms of rAAV have been used to deliver “pre-event” cardiac protection and to temper the severity of hypertrophy, cardiac ischemia, or infarct size. Adeno-associated virus (AAV) vectors have also been functional delivery tools for cardiac gene expression knockdown studies and successfully improving the cardiac aspects of several metabolic and neuromuscular diseases. Viral capsid manipulations along with the development of tissue-specific and regulated promoters have greatly increased the utility of rAAV-mediated gene transfer. Important clinical studies are currently underway to evaluate AAV-based cardiac gene delivery in humans. PMID:21792180

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

    PubMed Central

    Monier, Adam; Claverie, Jean-Michel; Ogata, Hiroyuki

    2007-01-01

    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 modern hosts. The large

  15. Lateral Gene Transfer and Gene Duplication Played a Key Role in the Evolution of Mastigamoeba balamuthi Hydrogenosomes

    PubMed Central

    Nývltová, Eva; Stairs, Courtney W.; Hrdý, Ivan; Rídl, Jakub; Mach, Jan; Pačes, Jan; Roger, Andrew J.; Tachezy, Jan

    2015-01-01

    Lateral gene transfer (LGT) is an important mechanism of evolution for protists adapting to oxygen-poor environments. Specifically, modifications of energy metabolism in anaerobic forms of mitochondria (e.g., hydrogenosomes) are likely to have been associated with gene transfer from prokaryotes. An interesting question is whether the products of transferred genes were directly targeted into the ancestral organelle or initially operated in the cytosol and subsequently acquired organelle-targeting sequences. Here, we identified key enzymes of hydrogenosomal metabolism in the free-living anaerobic amoebozoan Mastigamoeba balamuthi and analyzed their cellular localizations, enzymatic activities, and evolutionary histories. Additionally, we characterized 1) several canonical mitochondrial components including respiratory complex II and the glycine cleavage system, 2) enzymes associated with anaerobic energy metabolism, including an unusual D-lactate dehydrogenase and acetyl CoA synthase, and 3) a sulfate activation pathway. Intriguingly, components of anaerobic energy metabolism are present in at least two gene copies. For each component, one copy possesses an mitochondrial targeting sequence (MTS), whereas the other lacks an MTS, yielding parallel cytosolic and hydrogenosomal extended glycolysis pathways. Experimentally, we confirmed that the organelle targeting of several proteins is fully dependent on the MTS. Phylogenetic analysis of all extended glycolysis components suggested that these components were acquired by LGT. We propose that the transformation from an ancestral organelle to a hydrogenosome in the M. balamuthi lineage involved the lateral acquisition of genes encoding extended glycolysis enzymes that initially operated in the cytosol and that established a parallel hydrogenosomal pathway after gene duplication and MTS acquisition. PMID:25573905

  16. Study of Lateral Gene Transfer in an Acid Mine Drainage Community Enabled by Comparative Genomics

    NASA Astrophysics Data System (ADS)

    Hugenholtz, P.; Croft, L.; Tyson, G. W.; Baker, B. J.; Detter, C.; Richardson, P. M.; Banfield, J. F.

    2002-12-01

    Lateral gene transfer (LGT) is thought to play a crucial role in the ecology and evolution of prokaryotes. We are investigating the role of LGT in an acid mine drainage community hosted in a pyrite-dominated metal sulfide deposit at the Richmond mine at Iron Mountain, CA. Due to biologically-mediated pyrite dissolution, the prevailing conditions within the mine are extremely low pH (< 1.0), very high ionic concentrations (molar concentrations of iron sulfate and mM concentrations of arsenic, copper and zinc), and moderate to high temperatures (30 to >50 C). These conditions are thought to largely isolate the community from potential external gene donors since naked DNA, phage and prokaryotes native to neutral pH habitats do not persist at pH <1.0 precluding an external influx of genes by transformation, transduction and conjugation, respectively. Microbial communities exist in several distinct habitats within Richmond mine including biofilms (subaqueous slime streamers and subaerial slimes) and cells attached directly to pyrite granules. This, however, belies an unusual simplicity in community composition. All communities investigated to date comprise only a handful of phylogenetically distinct organisms, typically dominated by the iron-oxidizing genera Leptospirillum and Ferroplasma. We have undertaken a community genomics analysis of a subaerial biofilm dominated by a Leptospirillum population to facilitate the study of LGT in this type of environment. The genome of Ferroplasma acidarmanus fer1, a minor component of the target community (but a major component of other Richmond mine communities), has been sequenced. Comparative genome analyses indicate that F. acidarmanus and the ancestor of two acidophilic Thermoplasma species belonging to the Euryarchaeota have traded many genes with phylogenetically remote acidophilic Sulfolobus species (Crenarchaeota). The putatively transferred sets of Sulfolobus genes in Ferroplasma and the Thermoplasma ancestor are distinct

  17. Characterization of DNA-hyaluronan matrix for sustained gene transfer.

    PubMed

    Kim, Angela; Checkla, Daniel M; Dehazya, Philip; Chen, Weiliam

    2003-06-01

    DNA-Hyaluronan (DNA-HA) matrix formulations intended for use as gene delivery systems have been developed and their potential for delivering DNA encoding a model therapeutic cytokine, platelet-derived growth factor (PDGF), has been evaluated. The results of enzyme-mediated release kinetics studies suggested that the rate of DNA release from the DNA-HA matrices could be modulated by changing the DNA loading or the degree of crosslinking. SEM imaging of the DNA-HA matrix showed that it was gradually eroded by enzymatic action. The results of gel electrophoresis suggested that there was some degree of interaction between DNA and native HA and that portions of the DNA released from the DNA-HA matrices were associated with crosslinked HA fragments. Only fractions of the DNA released from the DNA-HA matrices were free and the rest was entrapped by HA fragments, which could serve as a mechanism for DNA protection. The results from cell transfection studies using DNA samples collected during the course of release studies confirmed this hypothesis. The PDGF produced by transfection of the DNA released from DNA-HA matrices induced human dermal fibroblast cells to proliferate. PMID:12767709

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  19. A case of horizontal gene transfer from Wolbachia to Aedes albopictus C6/36 cell line

    PubMed Central

    Hou, Qing; He, Ji; Yu, Jing; Ye, Yuting; Zhou, Dan; Sun, Yan; Zhang, Donghui; Ma, Lei; Shen, Bo; Zhu, Changliang

    2014-01-01

    Horizontal gene transfer plays an essential role in evolution and ecological adaptation, yet this phenomenon has remained controversial, particularly where it occurs between prokaryotes and eukaryotes. There are a handful of reported examples of horizontal gene transfer occurring between prokaryotes and eukaryotes in the literature, with most of these documented cases pertaining to invertebrates and endosymbionts. However, the vast majority of these horizontally transferred genes were either eventually excluded or rapidly became nonfunctional in the recipient genome. In this study, we report the discovery of a horizontal gene transfer from the endosymbiont Wolbachia in the C6/36 cell line derived from the mosquito Aedes albopictus. Moreover, we report that this horizontally transferred gene displayed high transcription level. This finding and the results of further experimentation strongly suggest this gene is functional and has been expressed and translated into a protein in the mosquito host cells. PMID:24812591

  20. Microbubbles and ultrasound increase intraventricular polyplex gene transfer to the brain.

    PubMed

    Tan, James-Kevin Y; Pham, Binhan; Zong, Yujin; Perez, Camilo; Maris, Don O; Hemphill, Ashton; Miao, Carol H; Matula, Thomas J; Mourad, Pierre D; Wei, Hua; Sellers, Drew L; Horner, Philip J; Pun, Suzie H

    2016-06-10

    Neurons in the brain can be damaged or lost from neurodegenerative disease, stroke, or traumatic injury. Although neurogenesis occurs in mammalian adult brains, the levels of natural neurogenesis are insufficient to restore function in these cases. Gene therapy has been pursued as a promising strategy to induce differentiation of neural progenitor cells into functional neurons. Non-viral vectors are a preferred method of gene transfer due to potential safety and manufacturing benefits but suffer from lower delivery efficiencies compared to viral vectors. Since the neural stem and progenitor cells reside in the subventricular zone of the brain, intraventricular injection has been used as an administration route for gene transfer to these cells. However, the choroid plexus epithelium remains an obstacle to delivery. Recently, transient disruption of the blood-brain barrier by microbubble-enhanced ultrasound has been used to successfully improve drug delivery to the brain after intravenous injection. In this work, we demonstrate that microbubble-enhanced ultrasound can similarly improve gene transfer to the subventricular zone after intraventricular injection. Microbubbles of different surface charges (neutral, slightly cationic, and cationic) were prepared, characterized by acoustic flow cytometry, and evaluated for their ability to increase the permeability of immortalized choroid plexus epithelium monolayers in vitro. Based on these results, slightly cationic microbubbles were evaluated for microbubble and ultrasound-mediated enhancement of non-viral gene transfer in vivo. When coupled with our previously reported gene delivery vehicles, the slightly cationic microbubbles significantly increased ultrasound-mediated transfection of the murine brain when compared to commercially available Definity® microbubbles. Temporary disruption of the choroid plexus by microbubble-enhanced ultrasound is therefore a viable way of enhancing gene delivery to the brain and merits

  1. Robust H infinity-stabilization design in gene networks under stochastic molecular noises: fuzzy-interpolation approach.

    PubMed

    Chen, Bor-Sen; Chang, Yu-Te; Wang, Yu-Chao

    2008-02-01

    Molecular noises in gene networks come from intrinsic fluctuations, transmitted noise from upstream genes, and the global noise affecting all genes. Knowledge of molecular noise filtering in gene networks is crucial to understand the signal processing in gene networks and to design noise-tolerant gene circuits for synthetic biology. A nonlinear stochastic dynamic model is proposed in describing a gene network under intrinsic molecular fluctuations and extrinsic molecular noises. The stochastic molecular-noise-processing scheme of gene regulatory networks for attenuating these molecular noises is investigated from the nonlinear robust stabilization and filtering perspective. In order to improve the robust stability and noise filtering, a robust gene circuit design for gene networks is proposed based on the nonlinear robust H infinity stochastic stabilization and filtering scheme, which needs to solve a nonlinear Hamilton-Jacobi inequality. However, in order to avoid solving these complicated nonlinear stabilization and filtering problems, a fuzzy approximation method is employed to interpolate several linear stochastic gene networks at different operation points via fuzzy bases to approximate the nonlinear stochastic gene network. In this situation, the method of linear matrix inequality technique could be employed to simplify the gene circuit design problems to improve robust stability and molecular-noise-filtering ability of gene networks to overcome intrinsic molecular fluctuations and extrinsic molecular noises. PMID:18270080

  2. Editing T cell specificity towards leukemia by zinc-finger nucleases and lentiviral gene transfer

    PubMed Central

    Lombardo, Angelo; Magnani, Zulma; Liu, Pei-Qi; Reik, Andreas; Chu, Victoria; Paschon, David E.; Zhang, Lei; Kuball, Jurgen; Camisa, Barbara; Bondanza, Attilio; Casorati, Giulia; Ponzoni, Maurilio; Ciceri, Fabio; Bordignon, Claudio; Greenberg, Philip D.; Holmes, Michael C.; Gregory, Philip D.; Naldini, Luigi; Bonini, Chiara

    2016-01-01

    The transfer of high-avidity T-cell receptor (TCR) genes isolated from rare tumor-specific lymphocytes into polyclonal T cells is an attractive cancer immunotherapy strategy. However, TCR gene transfer results in competition for surface expression and inappropriate pairing between the exogenous and endogenous TCR chains, resulting in suboptimal activity and potentially harmful unpredicted specificities. We designed zinc-finger nucleases (ZFNs) promoting the disruption of endogenous TCR β and α chain genes. ZFN-treated lymphocytes lacked CD3/TCR surface expression and expanded with IL-7 and IL-15. Upon lentiviral transfer of a TCR for the WT1 tumor antigen, these TCR-edited cells expressed the new TCR at high levels, were easily expanded to near-purity, and proved superior in specific antigen recognition to matched TCR-transferred cells. In contrast to TCR-transferred cells, TCR edited lymphocytes did not mediate off-target reactivity while maintaining anti-tumor activity in vivo, thus demonstrating that complete editing of T-cell specificity generate tumor-specific lymphocytes with improved biosafety profile. PMID:22466705

  3. Gene transfer rate from CL rice to diverse red rice biotypes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The future and sustainability of ClearfieldTM (CL) technology at the producers’ level will be dictated by various factors. Among many, prominent factors which affect the transfer of ALS-resistant gene from CL rice to red rice are: disparity in red rice biotypes and CL cultivars; flowering time of re...

  4. Bacteriophage-like Particles Associated with the Gene Transfer Agent of Methanococcus Voltale PS

    NASA Technical Reports Server (NTRS)

    Bertani, G.; Eiserling, F.; Pushkin, A.; Gingery, M.

    1999-01-01

    The methanogenic archaebacterium Methanococus voltae (strain PS) is known to produce a filterable, DNase resistant agent (called VTA, for voltae transfer agent), which carries very small fragments (4,400 base pairs) of bacterial DNA and is able to transduce bacterial genes between derivatives of the strain.

  5. Transfer of herbicide-resistant gene to weedy rice populations and its implications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Red rice diversity in terms of phenology, sexual compatibility with cultivated rice, and the wide window of rice planting time can affect the rate of herbicide-resistant gene transfer from rice to RR. Experiments were conducted to a) determine the effect of red rice, rice cultivar, and planting date...

  6. Assessing the effects of a sequestered germline on interdomain lateral gene transfer in Metazoa.

    PubMed

    Jensen, Lindy; Grant, Jessica R; Laughinghouse, Haywood Dail; Katz, Laura A

    2016-06-01

    A sequestered germline in Metazoa has been argued to be an obstacle to lateral gene transfer (LGT), though few studies have specifically assessed this claim. Here, we test the hypothesis that the origin of a sequestered germline reduced LGT events in Bilateria (i.e., triploblast lineages) as compared to early-diverging Metazoa (i.e., Ctenophora, Cnidaria, Porifera, and Placozoa). We analyze single-gene phylogenies generated with over 900 species sampled from among Bacteria, Archaea, and Eukaryota to identify well-supported interdomain LGTs. We focus on ancient interdomain LGT (i.e., those between prokaryotes and multiple lineages of Metazoa) as systematic errors in single-gene tree reconstruction create uncertainties for interpreting eukaryote-to-eukaryote transfer. The breadth of the sampled Metazoa enables us to estimate the timing of LGTs, and to examine the pattern before versus after the evolution of a sequestered germline. We identified 58 LGTs found only in Metazoa and prokaryotes (i.e., bacteria and/or archaea), and seven genes transferred from prokaryotes into Metazoa plus one other eukaryotic clade. Our analyses indicate that more interdomain transfers occurred before the development of a sequestered germline, consistent with the hypothesis that this feature is an obstacle to LGT. PMID:27139503

  7. Diversity, evolution, and horizontal gene transfer (HGT) in soda lakes

    NASA Astrophysics Data System (ADS)

    Pinkart, Holly C.; Storrie-Lombardi, Michael C.

    2007-09-01

    Soap Lake is a hypersaline, alkaline lake in Central Washington State (USA). For the past five years the lake has been the site of an NSF Microbial Observatory project devoted to identifying critical geochemical and microbial characteristics of the monimolimnion sediment and water column, and has demonstrated rich multispecies communities occupy all areas of the lake. Soap Lake and similar soda lakes are subject to repeated transient periods of extreme evaporation characterized by significant repetitive alterations in salinity, pH, and total water volume, yet maintain high genetic and metabolic diversity. It has been argued that this repetitive cycle for salinity, alkalinity, and sulfur concentration has been a major driver for prokaryote evolution and diversity. The rapidity of wet-dry cycling places special demands on genome evolution, requirements that are beyond the relatively conservative eukaryotic evolutionary strategy of serial alteration of existing gene sequences in a relatively stable genome. Although HGT is most likely responsible for adding a significant amount of noise to the genetic record, analysis of HGT activity can also provide us with a much-needed probe for exploration of prokaryotic genome evolution and the origin of diversity. Packaging of genetic information within the protective protein capsid of a bacteriophage would seem preferable to exposing naked DNA to the highly alkaline conditions in the lake. In this study, we present preliminary data demonstrating the presence of a diverse group of phage integrases in Soap Lake. Integrase is the viral enzyme responsible for the insertion of phage DNA into the bacterial host's chromosome. The presence of the integrase sequence in bacterial chromosomes is evidence of lysogeny, and the diversity of integrase sequences reported here suggests a wide variety of temperate phage exist in this system, and are especially active in transition zones.

  8. Plasmid encoded antibiotic resistance: acquisition and transfer of antibiotic resistance genes in bacteria

    PubMed Central

    Bennett, P M

    2008-01-01

    Bacteria have existed on Earth for three billion years or so and have become adept at protecting themselves against toxic chemicals. Antibiotics have been in clinical use for a little more than 6 decades. That antibiotic resistance is now a major clinical problem all over the world attests to the success and speed of bacterial adaptation. Mechanisms of antibiotic resistance in bacteria are varied and include target protection, target substitution, antibiotic detoxification and block of intracellular antibiotic accumulation. Acquisition of genes needed to elaborate the various mechanisms is greatly aided by a variety of promiscuous gene transfer systems, such as bacterial conjugative plasmids, transposable elements and integron systems, that move genes from one DNA system to another and from one bacterial cell to another, not necessarily one related to the gene donor. Bacterial plasmids serve as the scaffold on which are assembled arrays of antibiotic resistance genes, by transposition (transposable elements and ISCR mediated transposition) and site-specific recombination mechanisms (integron gene cassettes). The evidence suggests that antibiotic resistance genes in human bacterial pathogens originate from a multitude of bacterial sources, indicating that the genomes of all bacteria can be considered as a single global gene pool into which most, if not all, bacteria can dip for genes necessary for survival. In terms of antibiotic resistance, plasmids serve a central role, as the vehicles for resistance gene capture and their subsequent dissemination. These various aspects of bacterial resistance to antibiotics will be explored in this presentation. PMID:18193080

  9. Plasmid encoded antibiotic resistance: acquisition and transfer of antibiotic resistance genes in bacteria.

    PubMed

    Bennett, P M

    2008-03-01

    Bacteria have existed on Earth for three billion years or so and have become adept at protecting themselves against toxic chemicals. Antibiotics have been in clinical use for a little more than 6 decades. That antibiotic resistance is now a major clinical problem all over the world attests to the success and speed of bacterial adaptation. Mechanisms of antibiotic resistance in bacteria are varied and include target protection, target substitution, antibiotic detoxification and block of intracellular antibiotic accumulation. Acquisition of genes needed to elaborate the various mechanisms is greatly aided by a variety of promiscuous gene transfer systems, such as bacterial conjugative plasmids, transposable elements and integron systems, that move genes from one DNA system to another and from one bacterial cell to another, not necessarily one related to the gene donor. Bacterial plasmids serve as the scaffold on which are assembled arrays of antibiotic resistance genes, by transposition (transposable elements and ISCR mediated transposition) and site-specific recombination mechanisms (integron gene cassettes).The evidence suggests that antibiotic resistance genes in human bacterial pathogens originate from a multitude of bacterial sources, indicating that the genomes of all bacteria can be considered as a single global gene pool into which most, if not all, bacteria can dip for genes necessary for survival. In terms of antibiotic resistance, plasmids serve a central role, as the vehicles for resistance gene capture and their subsequent dissemination. These various aspects of bacterial resistance to antibiotics will be explored in this presentation. PMID:18193080

  10. Ancient gene transfer from algae to animals: Mechanisms and evolutionary significance

    PubMed Central

    2012-01-01

    Background Horizontal gene transfer (HGT) is traditionally considered to be rare in multicellular eukaryotes such as animals. Recently, many genes of miscellaneous algal origins were discovered in choanoflagellates. Considering that choanoflagellates are the existing closest relatives of animals, we speculated that ancient HGT might have occurred in the unicellular ancestor of animals and affected the long-term evolution of animals. Results Through genome screening, phylogenetic and domain analyses, we identified 14 gene families, including 92 genes, in the tunicate Ciona intestinalis that are likely derived from miscellaneous photosynthetic eukaryotes. Almost all of these gene families are distributed in diverse animals, suggesting that they were mostly acquired by the common ancestor of animals. Their miscellaneous origins also suggest that these genes are not derived from a particular algal endosymbiont. In addition, most genes identified in our analyses are functionally related to molecule transport, cellular regulation and methylation signaling, suggesting that the acquisition of these genes might have facilitated the intercellular communication in the ancestral animal. Conclusions Our findings provide additional evidence that algal genes in aplastidic eukaryotes are not exclusively derived from historical plastids and thus important for interpreting the evolution of eukaryotic photosynthesis. Most importantly, our data represent the first evidence that more anciently acquired genes might exist in animals and that ancient HGT events have played an important role in animal evolution. PMID:22690978

  11. Energy transfer induced improvement of luminescent efficiency and thermal stability in phosphate phosphor.

    PubMed

    Zhao, Yun; Lin, Chun Che; Wei, Yi; Chan, Ting-Shan; Li, Guogang

    2016-02-22

    Ce3+ and Eu2+/Tb3+/Mn2+ ions codoped Ca6BaP4O17 (CBPO) phosphors have been prepared via a high-temperature solid state reaction. The structural refinement indicates that the as-prepared phosphors crystallize in monoclinic phase (C2/m) and there are two Ca sites and one Ba site in host lattice. The doping ions are determined to occupy Ca sites and the emission of Ce3+ and Eu2+ ions at different Ca sites were identified and discussed. Since bright blue and yellow emissions were observed from Ce3+and Eu2+ ions monodoped CBPO under n-UV excitation, respectively. They were codoped into the CBPO for designing energy transfer from Ce3+ to Eu2+ to improve the luminescence efficiency of Eu2+. In addition, Tb3+ ions were added into the CBPO:Ce3+ system for realizing highly efficient green emission. The energy transfer mechanisms from Ce3+ to Eu2+/Tb3+ ions were discussed. Interestingly, the incorporation of Mn2+ ions into the CBPO:Ce3+ system enhanced the blue emission of Ce3+ ions due to the modification of crystal lattice. Finally, the thermal stability of CBPO:Ce3+, Eu2+/Tb3+/Mn2+ phosphors were investigated systematically and corresponding mechanisms were proposed. Based on these results, the as-prepared CBPO:Ce3+, Eu2+/Tb3+/Mn2+ phosphors can act as potential blue, yellow, green, and emission-tunable phosphors for n-UV based white LEDs. PMID:26907078

  12. HIV-1 Integrase Strand Transfer Inhibitors Stabilize an Integrase-Single Blunt-Ended DNA Complex

    PubMed Central

    Bera, Sibes; Pandey, Krishan K.; Vora, Ajaykumar C.; Grandgenett, Duane P.

    2011-01-01

    Summary Integration of HIV (human immunodeficiency virus) cDNA ends by integrase (IN) into host chromosomes involves a concerted integration mechanism. IN juxtaposes two DNA blunt-ends to form the synaptic complex (SC) which is the intermediate in the concerted integration pathway. SC is inactivated by strand transfer inhibitors (STI) with IC50 values of ~20 nM for inhibition of concerted integration. We detected a new nucleoprotein complex on native agarose that was produced in the presence of STI >200 nM, termed IN-single DNA (ISD) complex. Two IN dimers appear to bind in a parallel fashion at the DNA terminus producing a ~32 bp DNaseI protective footprint. In the presence of Raltegravir, MK-2048 and L-841,411, IN incorporated ~20 to 25% of the input blunt-ended DNA substrate into the stabilized ISD complex. Seven other STI also produced the ISD complex (≤ 5% of input DNA). The formation of the ISD complex was not dependent upon 3’ OH processing and the DNA was predominately blunt-ended in the complex. Raltegravir-resistant IN mutant N155H weakly form the ISD complex in the presence of Raltegravir at ~25% level of wild type IN. In contrast, MK-2048 and L-841,411 produced ~3 to 5-fold more ISD than Raltegravir with N155H IN, which is susceptible to these two inhibitors. The results suggest STI are slow binding inhibitors and the potency to form and stabilize the ISD complex is not always related to inhibition of concerted integration. Rather, the apparent binding and dissociation properties of each STI influenced the production of the ISD complex. PMID:21295584

  13. Conjugative transposons: an unusual and diverse set of integrated gene transfer elements.

    PubMed Central

    Salyers, A A; Shoemaker, N B; Stevens, A M; Li, L Y

    1995-01-01

    Conjugative transposons are integrated DNA elements that excise themselves to form a covalently closed circular intermediate. This circular intermediate can either reintegrate in the same cell (intracellular transposition) or transfer by conjugation to a recipient and integrate into the recipient's genome (intercellular transposition). Conjugative transposons were first found in gram-positive cocci but are now known to be present in a variety of gram-positive and gram-negative bacteria also. Conjugative transposons have a surprisingly broad host range, and they probably contribute as much as plasmids to the spread of antibiotic resistance genes in some genera of disease-causing bacteria. Resistance genes need not be carried on the conjugative transposon to be transferred. Many conjugative transposons can mobilize coresident plasmids, and the Bacteroides conjugative transposons can even excise and mobilize unlinked integrated elements. The Bacteroides conjugative transposons are also unusual in that their transfer activities are regulated by tetracycline via a complex regulatory network. PMID:8531886

  14. Fat-to-glucose interconversion by hydrodynamic transfer of two glyoxylate cycle enzyme genes

    PubMed Central

    Cordero, P; Campion, J; Milagro, FI; Marzo, F; Martinez, JA

    2008-01-01

    The glyoxylate cycle, which is well characterized in higher plants and some microorganisms but not in vertebrates, is able to bypass the citric acid cycle to achieve fat-to-carbohydrate interconversion. In this context, the hydrodynamic transfer of two glyoxylate cycle enzymes, such as isocytrate lyase (ICL) and malate synthase (MS), could accomplish the shift of using fat for the synthesis of glucose. Therefore, 20 mice weighing 23.37 ± 0.96 g were hydrodinamically gene transferred by administering into the tail vein a bolus with ICL and MS. After 36 hours, body weight, plasma glucose, respiratory quotient and energy expenditure were measured. The respiratory quotient was increased by gene transfer, which suggests that a higher carbohydrate/lipid ratio is oxidized in such animals. This application could help, if adequate protocols are designed, to induce fat utilization for glucose synthesis, which might be eventually useful to reduce body fat depots in situations of obesity and diabetes. PMID:19077206

  15. System and method for introduction and stabilization of genes in Thermus sp.

    DOEpatents

    Kayser, Kevin J.; Park, Ho-Shin; Kilbane, II, John J.

    2005-03-01

    A method for introducing and stabilizing heterologous and recombinant genes in a thermophilic host in which a characteristic gene defining a detectable host characteristic is inactivated or deleted from the thermophilic host, resulting in a modified thermophilic host expressing an absence of the detectable host characteristic. A DNA fragment of interest is inserted into the modified thermophilic host together with an intact characteristic gene, whereby the detectable host characteristic is restored to the thermophilic host, thereby enabling detection and confirmation of successful transformation using plasmid vectors and integration of the DNA fragment into the chromosome of the thermophilic host.

  16. Design and Fabrication of N-Alkyl-Polyethylenimine-Stabilized Iron Oxide Nanoclusters for Gene Delivery

    PubMed Central

    Liu, Gang; Wang, Zhiyong; Lee, Seulki; Ai, Hua; Chen, Xiaoyuan

    2013-01-01

    With the rapid development of nanotechnology, inorganic magnetic nanoparticles, especially iron oxide nanoparticles (IOs), have emerged as great vehicles for biomedical diagnostic and therapeutic applications. In order to rationally design IO-based gene delivery nanovectors, surface modification is essential and determines the loading and release of the gene of interest. Here we highlight the basic concepts and applications of nonviral gene delivery vehicles based on low molecular weight N-alkyl polyethylenimine-stabilized IOs. The experimental protocols related to these topics are described in this chapter. PMID:22568910

  17. Lentivirus-mediated gene transfer to the central nervous system: therapeutic and research applications.

    PubMed

    Wong, Liang-Fong; Goodhead, Lucy; Prat, Christine; Mitrophanous, Kyriacos A; Kingsman, Susan M; Mazarakis, Nicholas D

    2006-01-01

    The management of disorders of the nervous system remains a medical challenge. The key goals are to understand disease mechanisms, to validate therapeutic targets, and to develop new therapeutic strategies. Viral vector-mediated gene transfer can meet these goals and vectors based on lentiviruses have particularly useful features. Lentiviral vectors can deliver 8 kb of sequence, they mediate gene transfer into any neuronal cell type, expression and therapy are sustained, and normal cellular functions in vitro and in vivo are not compromised. After delivery into the nervous system they induce no significant immune responses, there are no unwanted side effects of the vectors per se to date, and manufacturing and safety testing for clinical applications are well advanced. There are now numerous examples of effective long-term treatment of animal models of neurological disorders, such as Parkinson's disease, Alzheimer's disease, Huntington's disease, motor neuron diseases, lysosomal storage diseases, and spinal injury, using a range of therapeutic genes expressed in lentiviral vectors. Significant issues remain in some areas of neural gene therapy including defining the optimum therapeutic gene(s), increasing the specificity of delivery, regulating expression of potentially toxic genes, and designing clinically relevant strategies. We discuss the applications of lentiviral vectors in therapy and research and highlight the essential features that will ensure their translation to the clinic in the near future. PMID:16409120

  18. Horizontal gene transfer: essentiality and evolvability in prokaryotes, and roles in evolutionary transitions.

    PubMed

    Koonin, Eugene V

    2016-01-01

    The wide spread of gene exchange and loss in the prokaryotic world has prompted the concept of 'lateral genomics' to the point of an outright denial of the relevance of phylogenetic trees for evolution. However, the pronounced coherence congruence of the topologies of numerous gene trees, particularly those for (nearly) universal genes, translates into the notion of a statistical tree of life (STOL), which reflects a central trend of vertical evolution. The STOL can be employed as a framework for reconstruction of the evolutionary processes in the prokaryotic world. Quantitatively, however, horizontal gene transfer (HGT) dominates microbial evolution, with the rate of gene gain and loss being comparable to the rate of point mutations and much greater than the duplication rate. Theoretical models of evolution suggest that HGT is essential for the survival of microbial populations that otherwise deteriorate due to the Muller's ratchet effect. Apparently, at least some bacteria and archaea evolved dedicated vehicles for gene transfer that evolved from selfish elements such as plasmids and viruses. Recent phylogenomic analyses suggest that episodes of massive HGT were pivotal for the emergence of major groups of organisms such as multiple archaeal phyla as well as eukaryotes. Similar analyses appear to indicate that, in addition to donating hundreds of genes to the emerging eukaryotic lineage, mitochondrial endosymbiosis severely curtailed HGT. These results shed new light on the routes of evolutionary transitions, but caution is due given the inherent uncertainty of deep phylogenies. PMID:27508073

  19. Gene transfer in the liver using recombinant adeno-associated virus

    PubMed Central

    Ahmed, Seemin Seher; Li, Jia; Godwin, Jonathan; Gao, Guangping; Zhong, Li

    2013-01-01

    Liver-directed gene transfer and gene therapy are rapidly gaining attention primarily because the liver is centrally involved in a variety of metabolic functions that are affected in various inherited disorders. Recombinant adeno-associated virus (rAAV) is a popular gene delivery vehicle for gene therapy and intravenous delivery of some rAAV serotypes results in very efficient transduction of the liver. rAAV-mediated and liver-directed gene transfer can help in creating somatic transgenic animals or disease models and studying the function of various genes and miRNAs. The liver is the target tissue for gene therapy of many inborn metabolic diseases and may also be exploited as a “bio-factory” for the production of coagulation factors, insulin and growth hormones and other non-hepatic proteins. Hence efficient delivery of transgenes and small RNAs to the liver by rAAV vectors has been of long-standing interest to research scientists and clinicians alike. PMID:23686826

  20. Horizontal gene transfer: essentiality and evolvability in prokaryotes, and roles in evolutionary transitions

    PubMed Central

    Koonin, Eugene V.

    2016-01-01

    The wide spread of gene exchange and loss in the prokaryotic world has prompted the concept of ‘lateral genomics’ to the point of an outright denial of the relevance of phylogenetic trees for evolution. However, the pronounced coherence congruence of the topologies of numerous gene trees, particularly those for (nearly) universal genes, translates into the notion of a statistical tree of life (STOL), which reflects a central trend of vertical evolution. The STOL can be employed as a framework for reconstruction of the evolutionary processes in the prokaryotic world. Quantitatively, however, horizontal gene transfer (HGT) dominates microbial evolution, with the rate of gene gain and loss being comparable to the rate of point mutations and much greater than the duplication rate. Theoretical models of evolution suggest that HGT is essential for the survival of microbial populations that otherwise deteriorate due to the Muller’s ratchet effect. Apparently, at least some bacteria and archaea evolved dedicated vehicles for gene transfer that evolved from selfish elements such as plasmids and viruses. Recent phylogenomic analyses suggest that episodes of massive HGT were pivotal for the emergence of major groups of organisms such as multiple archaeal phyla as well as eukaryotes. Similar analyses appear to indicate that, in addition to donating hundreds of genes to the emerging eukaryotic lineage, mitochondrial endosymbiosis severely curtailed HGT. These results shed new light on the routes of evolutionary transitions, but caution is due given the inherent uncertainty of deep phylogenies. PMID:27508073

  1. Stability of Reference Gene Expression After Porcine Sapelovirus Infection in Porcine Intestinal Epithelial Cells.

    PubMed

    Huang, Yong; Chen, Yabing; Sun, Huan; Lan, Daoliang

    2016-01-01

    Intestinal epithelial cells, which serve as the first physical barrier to protect intestinal tract from external antigens, have an important role in the local innate immunity. Screening of reference genes that have stable expression levels after viral infection in porcine intestinal epithelial cells is critical for ensuring the reliability of the expression analysis on anti-infection genes in porcine intestinal epithelial cells. In this study, nine common reference genes in pigs, including ACTB, B2M, GAPDH, HMBS, SDHA, HPRT1, TBP, YWHAZ, and RPL32, were chosen as the candidate reference genes. Porcine sapelovirus (PSV) was used as a model virus to infect porcine intestinal epithelial cell line (IPEC-J2). The expression stability of the nine genes was assessed by the geNorm, NormFinder, and BestKeeper software. Moreover, RefFinder program was used to evaluate the analytical results of above three softwares, and a relative expression experiment of selected target gene was used to verify the analysis results. The comprehensive results indicated that the gene combination of TBP and RPL32 has the most stable expression, which could be considered as an appropriate reference gene for research on gene expression after PSV infection in IPEC-J2cells. The results provided essential data for expression analysis of anti-infection genes in porcine intestinal epithelial cells. PMID:27092424

  2. Increased in vitro and in vivo gene transfer by adenovirus vectors containing chimeric fiber proteins.

    PubMed Central

    Wickham, T J; Tzeng, E; Shears, L L; Roelvink, P W; Li, Y; Lee, G M; Brough, D E; Lizonova, A; Kovesdi, I

    1997-01-01

    Alteration of the natural tropism of adenovirus (Ad) will permit gene transfer into specific cell types and thereby greatly broaden the scope of target diseases that can be treated by using Ad. We have constructed two Ad vectors which contain modifications to the Ad fiber coat protein that redirect virus binding to either alpha(v) integrin [AdZ.F(RGD)] or heparan sulfate [AdZ.F(pK7)] cellular receptors. These vectors were constructed by a novel method involving E4 rescue of an E4-deficient Ad with a transfer vector containing both the E4 region and the modified fiber gene. AdZ.F(RGD) increased gene delivery to endothelial and smooth muscle cells expressing alpha(v) integrins. Likewise, AdZ.F(pK7) increased transduction 5- to 500-fold in multiple cell types lacking high levels of Ad fiber receptor, including macrophage, endothelial, smooth muscle, fibroblast, and T cells. In addition, AdZ.F(pK7) significantly increased gene transfer in vivo to vascular smooth muscle cells of the porcine iliac artery following balloon angioplasty. These vectors may therefore be useful in gene therapy for vascular restenosis or for targeting endothelial cells in tumors. Although binding to the fiber receptor still occurs with these vectors, they demonstrate the feasibility of tissue-specific receptor targeting in cells which express low levels of Ad fiber receptor. PMID:9343173

  3. Intensive Pharmacological Immunosuppression Allows for Repetitive Liver Gene Transfer With Recombinant Adenovirus in Nonhuman Primates

    PubMed Central

    Fontanellas, Antonio; Hervás-Stubbs, Sandra; Mauleón, Itsaso; Dubrot, Juan; Mancheño, Uxua; Collantes, María; Sampedro, Ana; Unzu, Carmen; Alfaro, Carlos; Palazón, Asis; Smerdou, Cristian; Benito, Alberto; Prieto, Jesús; Peñuelas, Iván; Melero, Ignacio

    2010-01-01

    Repeated administration of gene therapies is hampered by host immunity toward vectors and transgenes. Attempts to circumvent antivector immunity include pharmacological immunosuppression or alternating different vectors and vector serotypes with the same transgene. Our studies show that B-cell depletion with anti-CD20 monoclonal antibody and concomitant T-cell inhibition with clinically available drugs permits repeated liver gene transfer to a limited number of nonhuman primates with recombinant adenovirus. Adenoviral vector–mediated transfer of the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene was visualized in vivo with a semiquantitative transgene-specific positron emission tomography (PET) technique, liver immunohistochemistry, and immunoblot for the reporter transgene in needle biopsies. Neutralizing antibody and T cell–mediated responses toward the viral capsids were sequentially monitored and found to be repressed by the drug combinations tested. Repeated liver transfer of the HSV1-tk reporter gene with the same recombinant adenoviral vector was achieved in macaques undergoing a clinically feasible immunosuppressive treatment that ablated humoral and cellular immune responses. This strategy allows measurable gene retransfer to the liver as late as 15 months following the first adenoviral exposure in a macaque, which has undergone a total of four treatments with the same adenoviral vector. PMID:20087317

  4. Myocardial Gene Transfer: Routes and Devices for Regulation of Transgene Expression by Modulation of Cellular Permeability

    PubMed Central

    Katz, Michael G.; Bridges, Charles R.

    2013-01-01

    Abstract Heart diseases are major causes of morbidity and mortality in Western society. Gene therapy approaches are becoming promising therapeutic modalities to improve underlying molecular processes affecting failing cardiomyocytes. Numerous cardiac clinical gene therapy trials have yet to demonstrate strong positive results and advantages over current pharmacotherapy. The success of gene therapy depends largely on the creation of a reliable and efficient delivery method. The establishment of such a system is determined by its ability to overcome the existing biological barriers, including cellular uptake and intracellular trafficking as well as modulation of cellular permeability. In this article, we describe a variety of physical and mechanical methods, based on the transient disruption of the cell membrane, which are applied in nonviral gene transfer. In addition, we focus on the use of different physiological techniques and devices and pharmacological agents to enhance endothelial permeability. Development of these methods will undoubtedly help solve major problems facing gene therapy. PMID:23427834

  5. Heterozygous screen in Saccharomyces cerevisiae identifies dosage-sensitive genes that affect chromosome stability.

    PubMed

    Strome, Erin D; Wu, Xiaowei; Kimmel, Marek; Plon, Sharon E

    2008-03-01

    Current techniques for identifying mutations that convey a small increased cancer risk or those that modify cancer risk in carriers of highly penetrant mutations are limited by the statistical power of epidemiologic studies, which require screening of large populations and candidate genes. To identify dosage-sensitive genes that mediate genomic stability, we performed a genomewide screen in Saccharomyces cerevisiae for heterozygous mutations that increase chromosome instability in a checkpoint-deficient diploid strain. We used two genome stability assays sensitive enough to detect the impact of heterozygous mutations and identified 172 heterozygous gene disruptions that affected chromosome fragment (CF) loss, 45% of which also conferred modest but statistically significant instability of endogenous chromosomes. Analysis of heterozygous deletion of 65 of these genes demonstrated that the majority increased genomic instability in both checkpoint-deficient and wild-type backgrounds. Strains heterozygous for COMA kinetochore complex genes were particularly unstable. Over 50% of the genes identified in this screen have putative human homologs, including CHEK2, ERCC4, and TOPBP1, which are already associated with inherited cancer susceptibility. These findings encourage the incorporation of this orthologous gene list into cancer epidemiology studies and suggest further analysis of heterozygous phenotypes in yeast as models of human disease resulting from haplo-insufficiency. PMID:18245329

  6. ''Pulling'' Nanoparticles into Water: Phase Transfer of Oleic Acid Stabilized Monodisperse Nanoparticles into Aqueous Solutions of alpha-Cyclodextrin

    SciTech Connect

    Wang, Y.; Wong, J.F.; Teng, X.; Lin, X.Z.; Yang, H.

    2003-10-18

    (B204)This paper describes a general method to drastically improve the disparity of oleic acid stabilized nanoparticles in aqueous solutions. We use oleic acid stabilized monodisperse nanoparticles of iron oxides and silver as model systems, and have modified the surface properties of these nanoparticles through the formation of an inclusion complex between surface-bound surfactant molecules and alpha-cyclodextrin (alpha-CD). After the modification, the nanoparticles of both iron oxide and Ag can transfer from hydrophobic solvents, such as hexane, to alpha-CD aqueous phase. The efficiency of the phase transfer to the aqueous solutions depend son the initial alpha-CD concentration. The alpha-CD/oleic acid complex stabilized nanoparticles can be stable for long periods of time in aqueous phase under ambient atmospheric conditions. Transmission electron microscopy (TME), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform-infrared (FT-IR) spectroscopy, and colorimetric methods have been used in the characterization of these nanoparticles.

  7. Targeting a newly established spontaneous feline fibrosarcoma cell line by gene transfer.

    PubMed

    Nande, Rounak; Di Benedetto, Altomare; Aimola, Pierpaolo; De Carlo, Flavia; Carper, Miranda; Claudio, Charlene D; Denvir, Jim; Valluri, Jagan; Duncan, Gary C; Claudio, Pier Paolo

    2012-01-01

    Fibrosarcoma is a deadly disease in cats and is significantly more often located at classical vaccine injections sites. More rare forms of spontaneous non-vaccination site (NSV) fibrosarcomas have been described and have been found associated to genetic alterations. Purpose of this study was to compare the efficacy of adenoviral gene transfer in NVS fibrosarcoma. We isolated and characterized a NVS fibrosarcoma cell line (Cocca-6A) from a spontaneous fibrosarcoma that occurred in a domestic calico cat. The feline cells were karyotyped and their chromosome number was counted using a Giemsa staining. Adenoviral gene transfer was verified by western blot analysis. Flow cytometry assay and Annexin-V were used to study cell-cycle changes and cell death of transduced cells. Cocca-6A fibrosarcoma cells were morphologically and cytogenetically characterized. Giemsa block staining of metaphase spreads of the Cocca-6A cells showed deletion of one of the E1 chromosomes, where feline p53 maps. Semi-quantitative PCR demonstrated reduction of p53 genomic DNA in the Cocca-6A cells. Adenoviral gene transfer determined a remarkable effect on the viability and growth of the Cocca-6A cells following single transduction with adenoviruses carrying Mda-7/IL-24 or IFN-γ or various combination of RB/p105, Ras-DN, IFN-γ, and Mda-7 gene transfer. Therapy for feline fibrosarcomas is often insufficient for long lasting tumor eradication. More gene transfer studies should be conducted in order to understand if these viral vectors could be applicable regardless the origin (spontaneous vs. vaccine induced) of feline fibrosarcomas. PMID:22666387

  8. Targeting a Newly Established Spontaneous Feline Fibrosarcoma Cell Line by Gene Transfer

    PubMed Central

    Nande, Rounak; De Carlo, Flavia; Carper, Miranda; Claudio, Charlene D.; Denvir, Jim; Valluri, Jagan; Duncan, Gary C.; Claudio, Pier Paolo

    2012-01-01

    Fibrosarcoma is a deadly disease in cats and is significantly more often located at classical vaccine injections sites. More rare forms of spontaneous non-vaccination site (NSV) fibrosarcomas have been described and have been found associated to genetic alterations. Purpose of this study was to compare the efficacy of adenoviral gene transfer in NVS fibrosarcoma. We isolated and characterized a NVS fibrosarcoma cell line (Cocca-6A) from a spontaneous fibrosarcoma that occurred in a domestic calico cat. The feline cells were karyotyped and their chromosome number was counted using a Giemsa staining. Adenoviral gene transfer was verified by western blot analysis. Flow cytometry assay and Annexin-V were used to study cell-cycle changes and cell death of transduced cells. Cocca-6A fibrosarcoma cells were morphologically and cytogenetically characterized. Giemsa block staining of metaphase spreads of the Cocca-6A cells showed deletion of one of the E1 chromosomes, where feline p53 maps. Semi-quantitative PCR demonstrated reduction of p53 genomic DNA in the Cocca-6A cells. Adenoviral gene transfer determined a remarkable effect on the viability and growth of the Cocca-6A cells following single transduction with adenoviruses carrying Mda-7/IL-24 or IFN-γ or various combination of RB/p105, Ras-DN, IFN-γ, and Mda-7 gene transfer. Therapy for feline fibrosarcomas is often insufficient for long lasting tumor eradication. More gene transfer studies should be conducted in order to understand if these viral vectors could be applicable regardless the origin (spontaneous vs. vaccine induced) of feline fibrosarcomas. PMID:22666387

  9. Networks of lexical borrowing and lateral gene transfer in language and genome evolution

    PubMed Central

    List, Johann-Mattis; Nelson-Sathi, Shijulal; Geisler, Hans; Martin, William

    2014-01-01

    Like biological species, languages change over time. As noted by Darwin, there are many parallels between language evolution and biological evolution. Insights into these parallels have also undergone change in the past 150 years. Just like genes, words change over time, and language evolution can be likened to genome evolution accordingly, but what kind of evolution? There are fundamental differences between eukaryotic and prokaryotic evolution. In the former, natural variation entails the gradual accumulation of minor mutations in alleles. In the latter, lateral gene transfer is an integral mechanism of natural variation. The study of language evolution using biological methods has attracted much interest of late, most approaches focusing on language tree construction. These approaches may underestimate the important role that borrowing plays in language evolution. Network approaches that were originally designed to study lateral gene transfer may provide more realistic insights into the complexities of language evolution. PMID:24375688

  10. Parallel Evolution and Horizontal Gene Transfer of the pst Operon in Firmicutes from Oligotrophic Environments

    PubMed Central

    Moreno-Letelier, Alejandra; Olmedo, Gabriela; Eguiarte, Luis E.; Martinez-Castilla, Leon; Souza, Valeria

    2011-01-01

    The high affinity phosphate transport system (pst) is crucial for phosphate uptake in oligotrophic environments. Cuatro Cienegas Basin (CCB) has extremely low P levels and its endemic Bacillus are closely related to oligotrophic marine Firmicutes. Thus, we expected the pst operon of CCB to share the same evolutionary history and protein similarity to marine Firmicutes. Orthologs of the pst operon were searched in 55 genomes of Firmicutes and 13 outgroups. Phylogenetic reconstructions were performed for the pst operon and 14 concatenated housekeeping genes using maximum likelihood methods. Conserved domains and 3D structures of the phosphate-binding protein (PstS) were also analyzed. The pst operon of Firmicutes shows two highly divergent clades with no correlation to the type of habitat nor a phylogenetic congruence, suggesting horizontal gene transfer. Despite sequence divergence, the PstS protein had a similar 3D structure, which could be due to parallel evolution after horizontal gene transfer events. PMID:21461370

  11. Parallel Evolution and Horizontal Gene Transfer of the pst Operon in Firmicutes from Oligotrophic Environments.

    PubMed

    Moreno-Letelier, Alejandra; Olmedo, Gabriela; Eguiarte, Luis E; Martinez-Castilla, Leon; Souza, Valeria

    2011-01-01

    The high affinity phosphate transport system (pst) is crucial for phosphate uptake in oligotrophic environments. Cuatro Cienegas Basin (CCB) has extremely low P levels and its endemic Bacillus are closely related to oligotrophic marine Firmicutes. Thus, we expected the pst operon of CCB to share the same evolutionary history and protein similarity to marine Firmicutes. Orthologs of the pst operon were searched in 55 genomes of Firmicutes and 13 outgroups. Phylogenetic reconstructions were performed for the pst operon and 14 concatenated housekeeping genes using maximum likelihood methods. Conserved domains and 3D structures of the phosphate-binding protein (PstS) were also analyzed. The pst operon of Firmicutes shows two highly divergent clades with no correlation to the type of habitat nor a phylogenetic congruence, suggesting horizontal gene transfer. Despite sequence divergence, the PstS protein had a similar 3D structure, which could be due to parallel evolution after horizontal gene transfer events. PMID:21461370

  12. Growth enhancement of shrimp (Litopenaeus schmitti) after transfer of tilapia growth hormone gene.

    PubMed

    Arenal, Amilcar; Pimentel, Rafael; Pimentel, Eulogio; Martín, Leonardo; Santiesteban, Dayamí; Franco, Ramón; Aleström, Peter

    2008-05-01

    Electroporation of Litopenaeus schmitti embryos was used to transfer the pE300tiGH15 plasmid that contains the tilapia growth hormone gene (tiGH) complexed with a nuclear localization signal peptide into the zygotes. The gene construct was detected in 35 (36%) of the 98 larvae screened by PCR and Southern blot analyses. Western blot analyses revealed that 34% of the screened larvae expressed a single tiGH-specific band with the expected molecular mass (23.1 kDa). The development index and larval length indicated a significant growth enhancement from day 3 on after electroporation, with an average of 32% of the growth enhancement. To our knowledge, this is the first report on gene transfer enhanced growth in crustaceans. PMID:18204820

  13. Detecting horizontal gene transfer with T-REX and RHOM programs.

    PubMed

    Li, Zuofeng; Wang, Li; Zhong, Yang

    2005-12-01

    As the Human Genome Project and other genome projects experience remarkable success and a flood of biological data is produced by means of high-throughout sequencing techniques, detection of horizontal gene transfer (HGT) becomes a promising field in bioinformatics. This review describes two freeware programs: T-REX for MS Windows and RHOM for Linux. T-REX is a graphical user interface program that offers functions to reconstruct the HGT network among the donor and receptor hosts from the gene and species distance matrices. RHOM is a set of command-line driven programs used to detect HGT in genomes. While T-REX impresses with a user-friendly interface and drawing of the reticulation network, the strength of RHOM is an extensive statistical framework of genome and the graphical display of the estimated sequence position probabilities for the candidate horizontally transferred genes. PMID:16420738

  14. Stable Bacillus thuringiensis (Bt) toxin content in interspecific F1 and backcross populations of wild Brassica rapa after Bt gene transfer.

    PubMed

    Zhu, B; Lawrence, J R; Warwick, S I; Mason, P; Braun, L; Halfhill, M D; Stewart, C N

    2004-01-01

    Stable expression of a transgene may lead to increased fitness for wild plants after acquiring the transgene via crop-weed hybridization. Here, we investigate the stability of Bt toxin content in wild Brassica rapa acquiring the Bt gene from Bt Brassica napus. The Bt toxin content in nine Bt-expressing B. napus lines was 0.80-1.70 micro g/g leaf tissue throughout the growing season. These nine lines were crossed with three accessions of wild B. rapa and the Bt gene was successfully transferred to interspecific hybrids (F1) and successive backcross generations (BC1 to BC4). The Bt toxin level in F1 and BC progenies containing the Bt gene remained at 0.90-3.10 micro g/g leaf tissue. This study indicates that the Bt gene can persist and be stably expressed in wild B. rapa. PMID:14653804

  15. Latest developments in gene transfer technology: achievements, perspectives, and controversies over therapeutic applications.

    PubMed

    Romano, G; Michell, P; Pacilio, C; Giordano, A

    2000-01-01

    Over the last decade, more than 300 phase I and phase II gene-based clinical trials have been conducted worldwide for the treatment of cancer and monogenic disorders. Lately, these trials have been extended to the treatment of AIDS and, to a lesser extent, cardiovascular diseases. There are 27 currently active gene therapy protocols for the treatment of HIV-1 infection in the USA. Preclinical studies are currently in progress to evaluate the possibility of increasing the number of gene therapy clinical trials for cardiopathies, and of beginning new gene therapy programs for neurologic illnesses, autoimmuno diseases, allergies, regeneration of tissues, and to implement procedures of allogeneic tissues or cell transplantation. In addition, gene transfer technology has allowed for the development of innovative vaccine design, known as genetic immunization. This technique has already been applied in the AIDS vaccine programs in the USA. These programs aim to confer protective immunity against HIV-1 transmission to individuals who are at risk of infection. Research programs have also been considered to develop therapeutic vaccines for patients with AIDS and generate either preventive or therapeutic vaccines against malaria, tuberculosis, hepatitis A, B and C viruses, influenza virus, La Crosse virus, and Ebola virus. The potential therapeutic applications of gene transfer technology are enormous. However, the effectiveness of gene therapy programs is still questioned. Furthermore, there is growing concern over the matter of safety of gene delivery and controversy has arisen over the proposal to begin in utero gene therapy clinical trials for the treatment of inherited genetic disorders. From this standpoint, despite the latest significant achievements reported in vector design, it is not possible to predict to what extent gene therapeutic interventions will be effective in patients, and in what time frame. PMID:10661569

  16. Silica Modified Chitosan/Polyethylenimine Nanogel for Improved Stability and Gene Carrier Ability.

    PubMed

    Tian, Rui; Xian, Lei; Li, Yuan; Zheng, Xingwang

    2016-05-01

    Although chitosan-based hydrogel has been widely used as a gene carrier material, further improvement in this aspect is still needed. Herein a new method was proposed for preparing the effective chitosan-based gene carrier nanogel. The new method based on the fact that supra-molecular interactions between silica, polyethylenimine (PEI) and chitosan could be used to self-assemble them together to form a rigid and stable gene carrier material in the reverse microemulsion system. When compared with chemical cross-linking route, the proposed method is simple and easy to adjust components of the resulting nanogel and, therefore, can improve its gene carrying ability. Our results showed that, doping of the PEI and silica into the chitosan hydrogel obviously increased its strength, stability and gene carrying ability. PMID:27483943

  17. Stability analysis of a model gene network links aging, stress resistance, and negligible senescence.

    PubMed

    Kogan, Valeria; Molodtsov, Ivan; Menshikov, Leonid I; Shmookler Reis, Robert J; Fedichev, Peter

    2015-01-01

    Several animal species are considered to exhibit what is called negligible senescence, i.e. they do not show signs of functional decline or any increase of mortality with age. Recent studies in naked mole rat and long-lived sea urchins showed that these species do not alter their gene-expression profiles with age as much as other organisms do. This is consistent with exceptional endurance of naked mole rat tissues to various genotoxic stresses. We conjectured, therefore, that the lifelong transcriptional stability of an organism may be a key determinant of longevity. We analyzed the stability of a simple genetic-network model and found that under most common circumstances, such a gene network is inherently unstable. Over a time it undergoes an exponential accumulation of gene-regulation deviations leading to death. However, should the repair systems be sufficiently effective, the gene network can stabilize so that gene damage remains constrained along with mortality of the organism. We investigate the relationship between stress-resistance and aging and suggest that the unstable regime may provide a mathematical basis for the Gompertz "law" of aging in many species. At the same time, this model accounts for the apparently age-independent mortality observed in some exceptionally long-lived animals. PMID:26316217

  18. Stability analysis of a model gene network links aging, stress resistance, and negligible senescence

    PubMed Central

    Kogan, Valeria; Molodtsov, Ivan; Menshikov, Leonid I.; Reis, Robert J. Shmookler; Fedichev, Peter

    2015-01-01

    Several animal species are considered to exhibit what is called negligible senescence, i.e. they do not show signs of functional decline or any increase of mortality with age. Recent studies in naked mole rat and long-lived sea urchins showed that these species do not alter their gene-expression profiles with age as much as other organisms do. This is consistent with exceptional endurance of naked mole rat tissues to various genotoxic stresses. We conjectured, therefore, that the lifelong transcriptional stability of an organism may be a key determinant of longevity. We analyzed the stability of a simple genetic-network model and found that under most common circumstances, such a gene network is inherently unstable. Over a time it undergoes an exponential accumulation of gene-regulation deviations leading to death. However, should the repair systems be sufficiently effective, the gene network can stabilize so that gene damage remains constrained along with mortality of the organism. We investigate the relationship between stress-resistance and aging and suggest that the unstable regime may provide a mathematical basis for the Gompertz “law” of aging in many species. At the same time, this model accounts for the apparently age-independent mortality observed in some exceptionally long-lived animals. PMID:26316217

  19. Effect of Plant and Environmental Factors on ALS-resistant Gene Transfer from ClearfieldTM Rice to Red Rice.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Imazethapyr-resistant gene from ClearfieldTM (CL) rice varieties transfers through pollen flow to red rice (Oryza sativa L.), a noxious weed in rice production in southern states. Factors which affect gene transfer rate include, but are not limited to, plant and environmental factors. Thus, we aimed...

  20. Intraspecies Transfer of the Chromosomal Acinetobacter baumannii blaNDM-1 Carbapenemase Gene.

    PubMed

    Krahn, Thomas; Wibberg, Daniel; Maus, Irena; Winkler, Anika; Bontron, Séverine; Sczyrba, Alexander; Nordmann, Patrice; Pühler, Alfred; Poirel, Laurent; Schlüter, Andreas

    2016-05-01

    The species Acinetobacter baumannii is one of the most important multidrug-resistant human pathogens. To determine its virulence and antibiotic resistance determinants, the genome of the nosocomial blaNDM-1-positive A. baumannii strain R2090 originating from Egypt was completely sequenced. Genome analysis revealed that strain R2090 is highly related to the community-acquired Australian A. baumannii strain D1279779. The two strains belong to sequence type 267 (ST267). Isolate R2090 harbored the chromosomally integrated transposon Tn125 carrying the carbapenemase gene blaNDM-1 that is not present in the D1279779 genome. To test the transferability of the metallo-β-lactamase (MBL) gene region, the clinical isolate R2090 was mated with the susceptible A. baumannii recipient CIP 70.10, and the carbapenem-resistant derivative R2091 was obtained. Genome sequencing of the R2091 derivative revealed that it had received an approximately 66-kb region comprising the transposon Tn125 embedding the blaNDM-1 gene. This region had integrated into the chromosome of the recipient strain CIP 70.10. From the four known mechanisms for horizontal gene transfer (conjugation, outer membrane vesicle-mediated transfer, transformation, and transduction), conjugation could be ruled out, since strain R2090 lacks any plasmid, and a type IV secretion system is not encoded in its chromosome. However, strain R2090 possesses three putative prophages, two of which were predicted to be complete and therefore functional. Accordingly, it was supposed that the transfer of the resistance gene region from the clinical isolate R2090 to the recipient occurred by general transduction facilitated by one of the prophages present in the R2090 genome. Hence, phage-mediated transduction has to be taken into account for the dissemination of antibiotic resistance genes within the species A. baumannii. PMID:26953198

  1. Immune Recognition of Gene Transfer Vectors: Focus on Adenovirus as a Paradigm

    PubMed Central

    Aldhamen, Yasser Ali; Seregin, Sergey S.; Amalfitano, Andrea

    2011-01-01

    Recombinant Adenovirus (Ad) based vectors have been utilized extensively as a gene transfer platform in multiple pre-clinical and clinical applications. These applications are numerous, and inclusive of both gene therapy and vaccine based approaches to human or animal diseases. The widespread utilization of these vectors in both animal models, as well as numerous human clinical trials (Ad-based vectors surpass all other gene transfer vectors relative to numbers of patients treated, as well as number of clinical trials overall), has shed light on how this virus vector interacts with both the innate and adaptive immune systems. The ability to generate and administer large amounts of this vector likely contributes not only to their ability to allow for highly efficient gene transfer, but also their elicitation of host immune responses to the vector and/or the transgene the vector expresses in vivo. These facts, coupled with utilization of several models that allow for full detection of these responses has predicted several observations made in human trials, an important point as lack of similar capabilities by other vector systems may prevent detection of such responses until only after human trials are initiated. Finally, induction of innate or adaptive immune responses by Ad vectors may be detrimental in one setting (i.e., gene therapy) and be entirely beneficial in another (i.e., prophylactic or therapeutic vaccine based applications). Herein, we review the current understanding of innate and adaptive immune responses to Ad vectors, as well some recent advances that attempt to capitalize on this understanding so as to further broaden the safe and efficient use of Ad-based gene transfer therapies in general. PMID:22566830

  2. Evolution and Horizontal Transfer of dUTPase-Encoding Genes in Viruses and Their Hosts

    PubMed Central

    Baldo, Angela M.; McClure, Marcella A.

    1999-01-01

    dUTPase is a ubiquitous and essential enzyme responsible for regulating cellular levels of dUTP. The dut gene exists as single, tandemly duplicated, and tandemly triplicated copies. Crystallized single-copy dUTPases have been shown to assemble as homotrimers. dUTPase is encoded as an auxiliary gene in a number of virus genomes. The origin of viral dut genes has remained unresolved since their initial discovery. A comprehensive analysis of dUTPase amino acid sequence relationships was performed to explore the evolutionary dynamics of dut in viruses and their hosts. Our data set, comprised of 24 host and 51 viral sequences, includes representative sequences from available eukaryotes, archaea, eubacteria cells, and viruses, including herpesviruses. These amino acid sequences were aligned by using a hidden Markov model approach developed to align divergent data. Known secondary structures from single-copy crystals were mapped onto the aligned duplicate and triplicate sequences. We show how duplicated dUTPases might fold into a monomer, and we hypothesize that triplicated dUTPases also assemble as monomers. Phylogenetic analysis revealed at least five viral dUTPase sequence lineages in well-supported monophyletic clusters with eukaryotic, eubacterial, and archaeal hosts. We have identified all five as strong examples of horizontal transfer as well as additional potential transfer of dut genes among eubacteria, between eubacteria and viruses, and between retroviruses. The evidence for horizontal transfers is particularly interesting since eukaryotic dut genes have introns, while DNA virus dut genes do not. This implies that an intermediary retroid agent facilitated the horizontal transfer process between host mRNA and DNA viruses. PMID:10438861

  3. Mechanism of proton transfer to coordinated thiolates: encapsulation of acid stabilizes precursor intermediate.

    PubMed

    Alwaaly, Ahmed; Clegg, William; Harrington, Ross W; Petrou, Athinoula L; Henderson, Richard A

    2015-07-14

    Earlier kinetic studies on the protonation of the coordinated thiolate in the square-planar [Ni(SC6H4R'-4)(triphos)](+) (R' = NO2, Cl, H, Me or MeO) by lutH(+) (lut = 2,6-dimethylpyridine) indicate a two-step mechanism involving initial formation of a (kinetically detectable) precursor intermediate, {[Ni(SC6H4R'-4)(triphos)]···Hlut}(2+) (K(R)1), followed by an intramolecular proton transfer step (k(R)2). The analogous [Ni(SR)(triphos)]BPh4 {R = Et, Bu(t) or Cy; triphos = PhP(CH2CH2PPh2)2} have been prepared and characterized by spectroscopy and X-ray crystallography. Similar to the aryl thiolate complexes, [Ni(SR)(triphos)](+) are protonated by lutH(+) in an equilibrium reaction but the observed rate law is simpler. Analysis of the kinetic data for both [Ni(SR)(triphos)](+) and [Ni(SC6H4R'-4)(triphos)](+) shows that both react by the same mechanism, but that K(R)1 is largest when the thiolate is poorly basic, or the 4-R' substituent in the aryl thiolates is electron-withdrawing. These results indicate that it is both NH···S hydrogen bonding and encapsulation of the bound lutH(+) (by the phenyl groups on triphos) which stabilize the precursor intermediate. PMID:26074501

  4. Epoxidized Soybean Oil: Evaluation of Oxidative Stabilization and Metal Quenching/Heat Transfer Performance

    NASA Astrophysics Data System (ADS)

    Simencio Otero, Rosa L.; Canale, Lauralice C. F.; Said Schicchi, Diego; Agaliotis, Eliana; Totten, George E.; Sánchez Sarmiento, Gustavo

    2013-07-01

    Vegetable and animal oils as a class of fluids have been used for hundreds of years, if not longer, as quenchants for hardening steel. However, when petroleum oils became available in the late 1800s and early 1900s, the use of these fluids as quenchants, in addition to their use in other industrial oil applications, quickly diminished. This was primarily, but not exclusively, due to their generally very poor thermal-oxidative instability and the difficulty for formulating fluid analogs with varying viscosity properties. Interest in the use of renewable fluids, such as vegetable oils, has increased dramatically in recent years as alternatives to the use of relatively non-biodegradable and toxic petroleum oils. However, the relatively poor thermal-oxidative stability has continued to be a significant reason for their general non-acceptance in the marketplace. Soybean oil (SO) is one of the most highly produced vegetable oils in Brazil. Currently, there are commercially produced epoxidized versions of SO which are available. The objective of this paper is to discuss the potential use of epoxidized SO and its heat transfer properties as a viable alternative to petroleum oils for hardening steel.

  5. Investigating the Energy Transfer from Dye Molecules to DNA Stabilized Au Nanoparticles.

    PubMed

    Patel, Arun Singh; Sahoo, Harekrushna; Mohanty, T

    2016-09-01

    Double-stranded DNA stabilized gold nanoparticles (Au NPs) are synthesized by chemical reduction method and characterized with different spectroscopic techniques such as UV-Visible absorption, Fourier transform infrared (FTIR), & circular-dichroism (CD) as well as transmission electron microscopy (TEM). These NPs show absorption maximum at 520 nm and size of most of the particles are of the order of 3.5 ± 1.0 nm. These Au NPs show crystalline nature as confirmed from electron diffraction pattern. The effect of formation of Au NPs on the macromolecule has been studied using infrared and circular dichroism spectroscopy. Formation of NPs causes conformational changes in the DNA molecules. These Au NPs are further used as resonant energy acceptor of fluorescence emission from dye molecules (Rhodamine 6G). The fluorescence intensity of Rhodamine 6G (R6G) is quenched in presence of Au NPs. The effect of DNA molecules on the fluorescence quenching and the rate of energy transfer from R6G molecules to Au NPs have been explored. PMID:27422695

  6. Divergence of genes encoding non-specific lipid transfer proteins in the poaceae family.

    PubMed

    Jang, Cheol Seong; Jung, Jae Hyeong; Yim, Won Cheol; Lee, Byung-Moo; Seo, Yong Weon; Kim, Wook

    2007-10-31

    The genes encoding non-specific lipid transfer proteins (nsLTPs), members of a small multigene family, show a complex pattern of expressional regulation, suggesting that some diversification may have resulted from changes in their expression after duplication. In this study, the evolution of nsLTP genes within the Poaceae family was characterized via a survey of the pseudogenes and unigenes encoding the nsLTP in rice pseudomolecules and the NCBI unigene database. nsLTP-rich regions were detected in the distal portions of rice chromosomes 11 and 12; these may have resulted from the most recent large segmental duplication in the rice genome. Two independent tandem duplications were shown to occur within the nsLTP-rich regions of rice. The genomic distribution of the nsLTP genes in the rice genome differs from that in wheat. This may be attributed to gene migration, chromosomal rearrangement, and/or differential gene loss. The genomic distribution pattern of nsLTP genes in the Poaceae family points to the existence of some differences among cereal nsLTP genes, all of which diverged from an ancient gene. The unigenes encoding nsLTPs in each cereal species are clustered into five groups. The somewhat different distribution of nsLTP-encoding EST clones between the groups across cereal species imply that independent duplication(s) followed by subfunctionalization (and/or neofunctionalization) of the nsLTP gene family in each species occurred during speciation. PMID:17978574

  7. [Plasmid pJP4 mediated gene horizontal transfer in a biofilm system and its effect on 2, 4-D degradation].

    PubMed

    Quan, Xiang-Chun; Tang, Hua; Hu, Li-Juan; Wang, Ran; Zhang, Ning

    2009-09-15

    With plasmid pJP4 (which contains functional gene cluster (tfd) encoding 2,4-D degradation) carrying genetic microorganism Pseudomonas putida SM1443:: gfp2x (pJP4:: dsRed) as the donor strain, events of plasmid mediated gene horizontal transfer and its effect on 2,4-D degradation was investigated in a biofilm system operated under fed-batch mode. The surviving status of the functional gene element in the gene-augmented system and effects of gene-augmentation on microbial community structure were also investigated. Results showed that introduction of pJP4 carrying strain to the biofilm system with 2, 4-D (initial concentration at 170 mg/L +/- 10 mg/L) as the sole carbon source could enhance the degradation of 2, 4-D. Enhancement was slight during the initial stage of operation, but it increased with increasing of fed batch runs. Difference in 2, 4-D average degradation rate between gene-augmented system and the control system achieved up to 13.3 mg/(L x h) at most. Through detecting functional gene tfdB and reporter gene gfp, pJP4 mediated gene horizontal transfer to the bacteria on biofilm was further approved. Effects of gene augmentation on microbial community structure was analyzed by PCR-DGGE analysis, and results showed that relatively higher stability of microbial community was maintained for the gene-augmented biofilm system compared to the control system when facing 2,4-D shock loadings. PMID:19927832

  8. Embedding mRNA Stability in Correlation Analysis of Time-Series Gene Expression Data

    PubMed Central

    Farina, Lorenzo; De Santis, Alberto; Salvucci, Samanta; Morelli, Giorgio; Ruberti, Ida

    2008-01-01

    Current methods for the identification of putatively co-regulated genes directly from gene expression time profiles are based on the similarity of the time profile. Such association metrics, despite their central role in gene network inference and machine learning, have largely ignored the impact of dynamics or variation in mRNA stability. Here we introduce a simple, but powerful, new similarity metric called lead-lag R2 that successfully accounts for the properties of gene dynamics, including varying mRNA degradation and delays. Using yeast cell-cycle time-series gene expression data, we demonstrate that the predictive power of lead-lag R2 for the identification of co-regulated genes is significantly higher than that of standard similarity measures, thus allowing the selection of a large number of entirely new putatively co-regulated genes. Furthermore, the lead-lag metric can also be used to uncover the relationship between gene expression time-series and the dynamics of formation of multiple protein complexes. Remarkably, we found a high lead-lag R2 value among genes coding for a transient complex. PMID:18670596

  9. Evidence for extensive horizontal gene transfer from the draft genome of a tardigrade

    PubMed Central

    Boothby, Thomas C.; Tenlen, Jennifer R.; Smith, Frank W.; Wang, Jeremy R.; Patanella, Kiera A.; Osborne Nishimura, Erin; Tintori, Sophia C.; Li, Qing; Jones, Corbin D.; Yandell, Mark; Glasscock, Jarret; Goldstein, Bob

    2015-01-01

    Horizontal gene transfer (HGT), or the transfer of genes between species, has been recognized recently as more pervasive than previously suspected. Here, we report evidence for an unprecedented degree of HGT into an animal genome, based on a draft genome of a tardigrade, Hypsibius dujardini. Tardigrades are microscopic eight-legged animals that are famous for their ability to survive extreme conditions. Genome sequencing, direct confirmation of physical linkage, and phylogenetic analysis revealed that a large fraction of the H. dujardini genome is derived from diverse bacteria as well as plants, fungi, and Archaea. We estimate that approximately one-sixth of tardigrade genes entered by HGT, nearly double the fraction found in the most extreme cases of HGT into animals known to date. Foreign genes have supplemented, expanded, and even replaced some metazoan gene families within the tardigrade genome. Our results demonstrate that an unexpectedly large fraction of an animal genome can be derived from foreign sources. We speculate that animals that can survive extremes may be particularly prone to acquiring foreign genes. PMID:26598659

  10. Growth factor enhanced retroviral gene transfer to the adult central nervous system.

    PubMed

    King, L A; Mitrophanous, K A; Clark, L A; Kim, V N; Rohll, J B; Kingsman, A J; Colello, R J

    2000-07-01

    The use of viral vectors for gene delivery into mammalian cells provides a new approach in the treatment of many human diseases. The first viral vector approved for human clinical trials was murine leukemia virus (MLV), which remains the most commonly used vector in clinical trials to date. However, the application of MLV vectors is limited since MLV requires cells to be actively dividing in order for transduction and therefore gene delivery to occur. This limitation precludes the use of MLV for delivering genes to the adult CNS, where very little cell division is occurring. However, we speculated that this inherent limitation of ML V may be overcome by utilizing the known mitogenic effect of growth factors on cells of the CNS. Specifically, an in vivo application of growth factor to the adult brain, if able to induce cell division, could enhance MLV-based gene transfer to the adult brain. We now show that an exogenous application of basic fibroblast growth factor induces cell division in vivo. Under these conditions, where cells of the adult brain are stimulated to divide, MLV-based gene transfer is significantly enhanced. This novel approach precludes any vector modifications and provides a simple and effective way of delivering genes to cells of the adult brain utilizing MLV-based retroviral vectors. PMID:10918476

  11. Gene transfer of arginine kinase to skeletal muscle using adeno-associated virus

    PubMed Central

    Forbes, Sean C.; Bish, Lawrence T.; Ye, Fan; Spinazzola, Janelle; Baligand, Celine; Plant, Daniel; Vandenborne, Krista; Barton, Elisabeth R.; Sweeney, H. Lee; Walter, Glenn A.

    2014-01-01

    In this study we tested the feasibility of non-invasively measuring phosphoarginine (PArg) after gene delivery of arginine kinase (AK) using an adeno-associated virus (AAV) to murine hindlimbs. This was achieved by evaluating the time course, regional distribution, and metabolic flux of PArg using 31 phosphorus magnetic resonance spectroscopy (31P-MRS). AK gene was injected into the gastrocnemius of the left hindlimb of C57Bl10 mice (age 5wk, male) using self-complementary AAV, type 2/8 with desmin promoter. Non-localized 31P-MRS data were acquired over nine months after injection using 11.1-T and 17.6-T Bruker Avance spectrometers. In addition, 31P 2-D chemical shift imaging and saturation transfer experiments were performed to examine the spatial distribution and metabolic flux of PArg, respectively. PArg was evident in each injected mouse hindlimb after gene delivery, increased until 28 weeks, and remained elevated for at least nine months (p<.05). Furthermore, PArg was primarily localized to the injected posterior hindimb region with the metabolite being in exchange with ATP. Overall, the results show the viability of AAV gene transfer of AK gene to skeletal muscle, and provide support of PArg as a reporter that can be utilized to non-invasively monitor the transduction of genes for therapeutic interventions. PMID:24572791

  12. Targeted disruption of Ataxia-telangiectasia mutated gene in miniature pigs by somatic cell nuclear transfer

    SciTech Connect

    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

    2014-10-03

    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.

  13. Gene transfer of arginine kinase to skeletal muscle using adeno-associated virus.

    PubMed

    Forbes, S C; Bish, L T; Ye, F; Spinazzola, J; Baligand, C; Plant, D; Vandenborne, K; Barton, E R; Sweeney, H L; Walter, G A

    2014-04-01

    In this study, we tested the feasibility of non-invasively measuring phosphoarginine (PArg) after gene delivery of arginine kinase (AK) using an adeno-associated virus (AAV) to murine hindlimbs. This was achieved by evaluating the time course, regional distribution and metabolic flux of PArg using (31)phosphorus magnetic resonance spectroscopy ((31)P-MRS). AK gene was injected into the gastrocnemius of the left hindlimb of C57Bl10 mice (age 5 weeks, male) using self-complementary AAV, type 2/8 with desmin promoter. Non-localized (31)P-MRS data were acquired over 9 months after injection using 11.1-T and 17.6-T Bruker Avance spectrometers. In addition, (31)P two-dimensional chemical shift imaging and saturation transfer experiments were performed to examine the spatial distribution and metabolic flux of PArg, respectively. PArg was evident in each injected mouse hindlimb after gene delivery, increased until 28 weeks, and remained elevated for at least 9 months (P<0.05). Furthermore, PArg was primarily localized to the injected posterior hindimb region and the metabolite was in exchange with ATP. Overall, the results show the viability of AAV gene transfer of AK gene to skeletal muscle, and provide support of PArg as a reporter that can be used to non-invasively monitor the transduction of genes for therapeutic interventions. PMID:24572791

  14. Non-Invasive Gene Transfer by Iontophoresis for Therapy of an Inherited Retinal Degeneration

    PubMed Central

    Souied, Eric H.; Reid, Silvia N. M.; Piri, Natik I.; Lerner, Leonid E.; Nusinowitz, Steven; Farber, Debora B.

    2009-01-01

    Despite extensive research on many of the genes responsible for inherited retinal degenerations leading to blindness, no effective treatment is currently available for patients affected with these diseases. Among the therapeutic approaches tested on animal models of human retinal degeneration, gene therapy using different types of viral vectors as delivery agents has yielded promising results. We report here our results on a non-invasive, non-viral delivery approach using transscleral iontophoresis for transfer of plasmid DNA into mouse retina. Proof of principle experiments were carried out using plasmid containing GFP cDNA to demonstrate expression of the transferred gene in the retina after single applications of iontophoresis. Various parameters for multiple applications of iontophoresis were optimized to sustain GFP gene expression in mouse photoreceptors. Subsequently, repeated iontophoresis of plasmid containing normal β-phosphodiesterase (β-PDE) cDNA was performed in the rd1 mouse, an animal model of autosomal recessive retinitis pigmentosa caused by a mutant β-PDE gene. In normal mice, transscleral iontophoresis of the GFP plasmid provided a significant increase in fluorescence of the retina in the treated versus non-treated eyes. In rd1 mice, repeated iontophoresis of β-PDE cDNA plasmid partially rescued photoreceptors morphologically, as observed by microscopy, and functionally, as recorded on ERG measurements, without adverse effects. Therefore, transscleral iontophoresis of plasmid DNA containing therapeutic genes may be an efficient, safe and non-invasive method for the treatment of retinal degenerations. PMID:18653181

  15. Evidence for extensive horizontal gene transfer from the draft genome of a tardigrade.

    PubMed

    Boothby, Thomas C; Tenlen, Jennifer R; Smith, Frank W; Wang, Jeremy R; Patanella, Kiera A; Osborne Nishimura, Erin; Tintori, Sophia C; Li, Qing; Jones, Corbin D; Yandell, Mark; Messina, David N; Glasscock, Jarret; Goldstein, Bob

    2015-12-29

    Horizontal gene transfer (HGT), or the transfer of genes between species, has been recognized recently as more pervasive than previously suspected. Here, we report evidence for an unprecedented degree of HGT into an animal genome, based on a draft genome of a tardigrade, Hypsibius dujardini. Tardigrades are microscopic eight-legged animals that are famous for their ability to survive extreme conditions. Genome sequencing, direct confirmation of physical linkage, and phylogenetic analysis revealed that a large fraction of the H. dujardini genome is derived from diverse bacteria as well as plants, fungi, and Archaea. We estimate that approximately one-sixth of tardigrade genes entered by HGT, nearly double the fraction found in the most extreme cases of HGT into animals known to date. Foreign genes have supplemented, expanded, and even replaced some metazoan gene families within the tardigrade genome. Our results demonstrate that an unexpectedly large fraction of an animal genome can be derived from foreign sources. We speculate that animals that can survive extremes may be particularly prone to acquiring foreign genes. PMID:26598659

  16. An Adenovirus Vector Incorporating Carbohydrate Binding Domains Utilizes Glycans for Gene Transfer

    PubMed Central

    Nakayama, Masaharu; Ak, Ferhat; Ugai, Hideyo; Curiel, David T.

    2013-01-01

    Background 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. Methodology/Principal Findings 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. Conclusions/Significance 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. PMID:23383334

  17. Horizontal transfer of the msp130 gene supported the evolution of metazoan biomineralization.

    PubMed

    Ettensohn, Charles A

    2014-05-01

    It is widely accepted that biomineralized structures appeared independently in many metazoan clades during the Cambrian. How this occurred, and whether it involved the parallel co-option of a common set of biochemical and developmental pathways (i.e., a shared biomineralization "toolkit"), are questions that remain unanswered. Here, I provide evidence that horizontal gene transfer supported the evolution of biomineralization in some metazoans. I show that Msp130 proteins, first described as proteins expressed selectively by the biomineral-forming primary mesenchyme cells of the sea urchin embryo, have a much wider taxonomic distribution than was previously appreciated. Msp130 proteins are present in several invertebrate deuterostomes and in one protostome clade (molluscs). Surprisingly, closely related proteins are also present in many bacteria and several algae, and I propose that msp130 genes were introduced into metazoan lineages via multiple, independent horizontal gene transfer events. Phylogenetic analysis shows that the introduction of an ancestral msp130 gene occurred in the sea urchin lineage more than 250 million years ago and that msp130 genes underwent independent, parallel duplications in each of the metazoan phyla in which these genes are found. PMID:24735463

  18. Ionizing and ultraviolet radiation enhances the efficiency of DNA mediated gene transfer in vitro

    SciTech Connect

    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.

  19. Hyperactive piggyBac Gene Transfer in Human Cells and In Vivo

    PubMed Central

    Doherty, Joseph E.; Huye, Leslie E.; Yusa, Kosuke; Zhou, Liqin; Craig, Nancy L.

    2012-01-01

    Abstract We characterized a recently developed hyperactive piggyBac (pB) transposase enzyme [containing seven mutations (7pB)] for gene transfer in human cells in vitro and to somatic cells in mice in vivo. Despite a protein level expression similar to that of native pB, 7pB significantly increased the gene transfer efficiency of a neomycin resistance cassette transposon in both HEK293 and HeLa cultured human cells. Native pB and SB100X, the most active transposase of the Sleeping Beauty transposon system, exhibited similar transposition efficiency in cultured human cell lines. When delivered to primary human T cells ex vivo, 7pB increased gene delivery two- to threefold compared with piggyBac and SB100X. The activity of hyperactive 7pB transposase was not affected by the addition of a 24-kDa N-terminal tag, whereas SB100X manifested a 50% reduction in transposition. Hyperactive 7pB was compared with native pB and SB100X in vivo in mice using hydrodynamic tail-vein injection of a limiting dose of transposase DNA combined with luciferase reporter transposons. We followed transgene expression for up to 6 months and observed approximately 10-fold greater long-term gene expression in mice injected with a codon-optimized version of 7pB compared with mice injected with native pB or SB100X. We conclude that hyperactive piggyBac elements can increase gene transfer in human cells and in vivo and should enable improved gene delivery using the piggyBac transposon system in a variety of cell and gene-therapy applications. PMID:21992617

  20. Lateral Transfer of the Denitrification Pathway Genes among Thermus thermophilus Strains▿

    PubMed Central

    Alvarez, Laura; Bricio, Carlos; José Gómez, Manuel; Berenguer, José

    2011-01-01

    Nitrate respiration is a common and strain-specific property in Thermus thermophilus encoded by the nitrate respiration conjugative element (NCE) that can be laterally transferred by conjugation. In contrast, nitrite respiration and further denitrification steps are restricted to a few isolates of this species. These later steps of the denitrification pathway are under the regulatory control of an NCE-encoded transcription factor, but nothing is known about their coding sequences or its putative genetic linkage to the NCE. In this study we examine the genetic linkage between nitrate and nitrite respiration through lateral gene transfer (LGT) assays and describe a cluster of genes encoding the nitrite-nitric oxide respiration in T. thermophilus PRQ25. We show that the whole denitrification pathway can be transferred from the denitrificant strain PRQ25 to an aerobic strain, HB27, and that the genes coding for nitrite and nitric oxide respiration are encoded near the NCE. Sequence data from the draft genome of PRQ25 confirmed these results and allowed us to describe the most compact nor-nir cluster known thus far and to demonstrate the expression and activities of the encoded enzymes in the HB27 denitrificant derivatives obtained by LGT. We conclude that this NCE nor-nir supercluster constitutes a whole denitrification island that can be spread by lateral transfer among Thermus thermophilus strains. PMID:21169443

  1. Evolution and Distribution of the ospC Gene, a Transferable Serotype Determinant of Borrelia burgdorferi

    PubMed Central

    Barbour, Alan G.; Travinsky, Bridgit

    2010-01-01

    Borrelia burgdorferi, an emerging bacterial pathogen, is maintained in nature by transmission from one vertebrate host to another by ticks. One of the few antigens against which mammals develop protective immunity is the highly polymorphic OspC protein, encoded by the ospC gene on the cp26 plasmid. Intragenic recombination among ospC genes is known, but the extent to which recombination extended beyond the ospC locus itself is undefined. We accessed and supplemented collections of DNA sequences of ospC and other loci from ticks in three U.S. regions (the Northeast, the Midwest, and northern California); a total of 839 ospC sequences were analyzed. Three overlapping but distinct populations of B. burgdorferi corresponded to the geographic regions. In addition, we sequenced 99 ospC flanking sequences from different lineages and compared the complete cp26 sequences of 11 strains as well as the cp26 bbb02 loci of 56 samples. Besides recombinations with traces limited to the ospC gene itself, there was evidence of lateral gene transfers that involved (i) part of the ospC gene and one of the two flanks or (ii) the entire ospC gene and different lengths of both flanks. Lateral gene transfers resulted in different linkages between the ospC gene and loci of the chromosome or other plasmids. By acquisition of the complete part or a large part of a novel ospC gene, an otherwise adapted strain would assume a new serotypic identity, thereby being comparatively fitter in an area with a high prevalence of immunity to existing OspC types. PMID:20877579

  2. Inducible long-term gene expression in brain with adeno-associated virus gene transfer.

    PubMed

    Haberman, R P; McCown, T J; Samulski, R J

    1998-12-01

    Recombinant adeno-associated virus (rAAV) vectors hold promise for treating a number of neurological disorders due to the ability to deliver long-term gene expression without toxicity or immune response. Critical to these endeavors will be controlled expression of the therapeutic gene in target cells. We have constructed and tested a dual cassette rAAV vector carrying a reporter gene under the control of the tetracycline-responsive system and the tetracycline transactivator. Transduction in vitro resulted in stable expression from the vector that can be suppressed 20-fold by tetracycline treatment. In vivo experiments, carried out to 6 weeks, demonstrated that vector-transduced expression is sustained until doxycycline administration upon which reporter gene expression is reduced. Moreover, the suppression of vector-driven expression can be reversed by removal of the drug. These studies demonstrate long-term regulated gene expression from rAAV vectors. This system will provide a valuable approach for controlling vector gene expression both in vitro and in vivo. PMID:10023439

  3. Transcriptional Analysis of the Conjugal Transfer Genes of Rickettsia bellii RML 369-C

    PubMed Central

    Heu, Chan C.; Kurtti, Timothy J.; Nelson, Curtis M.; Munderloh, Ulrike G.

    2015-01-01

    Rickettsia bellii is an obligate intracellular bacterium that is one of the few rickettsiae that encode a complete set of conjugative transfer (tra) genes involved in bacterial conjugation and has been shown to exhibit pili-like structures. The reductive genomes of rickettsiae beg the question whether the tra genes are nonfunctional or functioning to enhance the genetic plasticity and biology of rickettsiae. We characterized the transcriptional dynamics of R. bellii tra genes in comparison to genes transcribed stably and above the background level to understand when and at what levels the tra genes are active or whether the tra genes are degenerative. We determined that the best reference genes, out of 10 tested, were methionyl tRNA ligase (metG) or a combination of metG and ribonucleoside diphosphate reductase 2 subunit beta (nrdF), using statistical algorithms from two different programs: Normfinder and BestKeeper. To validate the use of metG with other rickettsial genes exhibiting variable transcriptional patterns we examined its use with sca2 and rickA, genes involved in actin based motility. Both were shown to be up-regulated at different times of replication in Vero cells, showing variable and stable transcription levels of rickA and sca2, respectively. traATi was up-regulated at 72 hours post inoculation in the tick cell line ISE6, but showed no apparent changes in the monkey cell line Vero and mouse cell line L929. The transcription of tra genes was positively correlated with one another and up-regulated from 12 to 72 hours post inoculation (HPI) when compared to RBE_0422 (an inactivated transposase-derivative found within the tra cluster). Thus, the up-regulation of the tra genes indicated that the integrity and activity of each gene were intact and may facilitate the search for the optimal conditions necessary to demonstrate conjugation in rickettsiae. PMID:26352829

  4. Horizontal gene transfers and cell fusions in microbiology, immunology and oncology (Review).

    PubMed

    Sinkovics, Joseph G

    2009-09-01

    Evolving young genomes of archaea, prokaryota and unicellular eukaryota were wide open for the acceptance of alien genomic sequences, which they often preserved and vertically transferred to their descendants throughout three billion years of evolution. Established complex large genomes, although seeded with ancestral retroelements, have come to regulate strictly their integrity. However, intruding retroelements, especially the descendents of Ty3/Gypsy, the chromoviruses, continue to find their ways into even the most established genomes. The simian and hominoid-Homo genomes preserved and accommodated a large number of endogenous retroviral genomic segments. These retroelements may mature into exogenous retroviruses, or into functional new genes. Phages and viruses have been instrumental in incorporating and transferring host cell genes. These events profoundly influenced and altered the course of evolution. Horizontal (lateral) gene transfers (HGT) overwhelmed the genomes of the ancient protocells and the evolving unicellular microorganisms, actually leading to their Cambrian explosion. While the rigidly organized genomes of multicellular organisms increasingly resist H/LGT, de-differentiated cells assuming the metabolism of their onto- or phylogenetic ancestors, open up widely to the practice of H/LGT by direct transfer, or to transfers mediated by viruses, or by cell fusions. This activity is intensified in malignantly transformed cells, thus rendering these subjects receptive to therapy with oncolytic viruses and with viral vectors of tumor-suppressive or immunogenic genetic materials. Naturally formed hybrids of dendritic and tumor cells are often tolerogenic, whereas laboratory products of these unisons may be immunogenic in the hosts of origin. As human breast cancer stem cells are induced by a treacherous class of CD8+ T cells to undergo epithelial to mesenchymal (ETM) transition and to yield to malignant transformation by the omnipresent proto

  5. Plant–Agrobacterium interaction mediated by ethylene and super-Agrobacterium conferring efficient gene transfer

    PubMed Central

    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-promoting rhizobacteria (PGPR) can reduce ethylene levels in plants through 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, which cleaves the ethylene precursor ACC into α-ketobutyrate and ammonia, resulting in reduced ethylene production. The whole genome sequence data showed that A. tumefaciens does not possess an ACC deaminase gene in its genome. Therefore, providing ACC deaminase activity to the bacteria would improve gene transfer. As expected, A. tumefaciens with ACC deaminase activity, designated as super-Agrobacterium, could suppress ethylene evolution and increase the gene transfer efficiency in several plant species. In this review, we summarize plant–Agrobacterium interactions and their applications for improving Agrobacterium-mediated genetic engineering techniques via super-Agrobacterium. PMID:25520733

  6. Cell-specific expression of the carrot EP2 lipid transfer protein gene.

    PubMed Central

    Sterk, P; Booij, H; Schellekens, G A; Van Kammen, A; De Vries, S C

    1991-01-01

    A cDNA corresponding to a 10-kD protein, designated extracellular protein 2 (EP2), that is secreted by embryogenic cell cultures of carrot was obtained by expression screening. The derived protein sequence and antisera against heterologous plant lipid transfer proteins identified the EP2 protein as a lipid transfer protein. Protein gel blot analysis showed that the EP2 protein is present in cell walls and conditioned medium of cell cultures. RNA gel blot analysis revealed that the EP2 gene is expressed in embryogenic cell cultures, the shoot apex of seedlings, developing flowers, and maturing seeds. In situ hybridization showed expression of the EP2 gene in protoderm cells of somatic and zygotic embryos and transient expression in epidermis cells of leaf primordia and all flower organs. In the shoot apical meristem, expression is found in the tunica and lateral zone. In maturing seeds, the EP2 gene is expressed in the outer epidermis of the integument, the seed coat, and the pericarp epidermis, as well as transiently in between both mericarps. Based on the extracellular location of the EP2 protein and the expression pattern of the encoding gene, we propose a role for plant lipid transfer proteins in the transport of cutin monomers through the extracellular matrix to sites of cutin synthesis. PMID:1822991

  7. Regulation of Nitrogenase Gene Expression by Transcript Stability in the Cyanobacterium Anabaena variabilis

    PubMed Central

    Pratte, Brenda S.

    2014-01-01

    The nitrogenase gene cluster in cyanobacteria has been thought to comprise multiple operons; however, in Anabaena variabilis, the promoter for the first gene in the cluster, nifB1, appeared to be the primary promoter for the entire nif cluster. The structural genes nifHDK1 were the most abundant transcripts; however, their abundance was not controlled by an independent nifH1 promoter, but rather, by RNA processing, which produced a very stable nifH1 transcript and a moderately stable nifD1 transcript. There was also no separate promoter for nifEN1. In addition to the nifB1 promoter, there were weak promoters inside the nifU1 gene and inside the nifE1 gene, and both promoters were heterocyst specific. In an xisA mutant, which effectively separated promoters upstream of an 11-kb excision element in nifD1 from the downstream genes, the internal nifE1 promoter was functional. Transcription of the nif1 genes downstream of the 11-kb element, including the most distant genes, hesAB1 and fdxH1, was reduced in the xisA mutant, indicating that the nifB1 promoter contributed to their expression. However, with the exception of nifK1 and nifE1, which had no expression, the downstream genes showed low to moderate levels of transcription in the xisA mutant. The hesA1 gene also had a promoter, but the fdxH gene had a processing site just upstream of the gene. The processing of transcripts at sites upstream of nifH1 and fdxH1 correlated with increased stability of these transcripts, resulting in greater amounts than transcripts that were not close to processing sites. PMID:25092030

  8. Regulation of nitrogenase gene expression by transcript stability in the cyanobacterium Anabaena variabilis.

    PubMed

    Pratte, Brenda S; Thiel, Teresa

    2014-10-01

    The nitrogenase gene cluster in cyanobacteria has been thought to comprise multiple operons; however, in Anabaena variabilis, the promoter for the first gene in the cluster, nifB1, appeared to be the primary promoter for the entire nif cluster. The structural genes nifHDK1 were the most abundant transcripts; however, their abundance was not controlled by an independent nifH1 promoter, but rather, by RNA processing, which produced a very stable nifH1 transcript and a moderately stable nifD1 transcript. There was also no separate promoter for nifEN1. In addition to the nifB1 promoter, there were weak promoters inside the nifU1 gene and inside the nifE1 gene, and both promoters were heterocyst specific. In an xisA mutant, which effectively separated promoters upstream of an 11-kb excision element in nifD1 from the downstream genes, the internal nifE1 promoter was functional. Transcription of the nif1 genes downstream of the 11-kb element, including the most distant genes, hesAB1 and fdxH1, was reduced in the xisA mutant, indicating that the nifB1 promoter contributed to their expression. However, with the exception of nifK1 and nifE1, which had no expression, the downstream genes showed low to moderate levels of transcription in the xisA mutant. The hesA1 gene also had a promoter, but the fdxH gene had a processing site just upstream of the gene. The processing of transcripts at sites upstream of nifH1 and fdxH1 correlated with increased stability of these transcripts, resulting in greater amounts than transcripts that were not close to processing sites. PMID:25092030

  9. Pigment-cell-specific genes from fibroblasts are transactivated after chromosomal transfer into melanoma cells

    SciTech Connect

    Powers, T.P.; Davidson, R.L.; Shows, T.B.

    1994-02-01

    Human and mouse fibroblast chromosomes carrying tyrosinase or b-locus genes were introduced, by microcell hybridization, into pigmented Syrian hamster melanoma cells, and the microcell hybrids were tested for transactivation of the fibroblast tyrosinase and b-locus genes. By using species-specific PCR amplification to distinguish fibroblast and melanoma cDNAs, it was demonstrated that the previously silent fibroblast tyrosinase and b-locus genes were transactivated following chromosomal transfer into pigmented melanoma cells. However, transactivation of the mouse fibroblast tyrosinase gene was unstable in microcell hybrid subclones and possibly dependent on a second fibroblast locus that could have segregated in the subclones. This second locus was not necessary for transactivation of the fibroblast b-locus gene, thus demonstrating noncoordinate transactivation of fibroblast tyrosinase and b-locus genes. Transactivation of the fibroblast tyrosinase gene in microcell hybrids apparently is dependent on the absence of a putative fibroblast extinguisher locus for tyrosinase gene expression, which presumably is responsible for the extinction of pigmentation in hybrids between karyotypically complete fibroblasts and melanoma cells. 46 refs., 5 figs., 2 tabs.

  10. Molten pool quenching phenomena: Stability and heat transfer with multiphase injection

    NASA Astrophysics Data System (ADS)

    Klockow, Helge B.

    In the design of the next generation of nuclear reactors and in the safety assessment of the currently operating nuclear power plants, it is necessary to evaluate the possibility of experiencing a degraded-core accident and to identify the key strategies to follow in order to mitigate the possible consequences. The ex-vessel cooling by bottom water injection strategy presumes the failure of the reactor pressure vessel. This project is focused on determining the influence of water mass flow rate, system pressure and co-injected gas flow rate on the volumetric heat removal rate, flow stability and molten pool void fraction of the system. An apparatus has been designed, which uses molten lead at a temperature of 500°C as a corium simulant. A wide array of experiments are being performed focused on co-injection of 1--6 g/s of water and up to 30 slpm of Argon at system pressures of up to 5 bar, typical of that expected in accident scenarios. Important parameters for the heat transfer characteristics are measured and flow instability is investigated. The experiments indicate that the heat removal rate from the melt increases with increasing water injection rate. The void fraction increases with increasing water mass flow rate as expected. An increase from low to medium pressure (0--2.5 bar) decreases the void fraction, while there is a modest decrease due to a pressure increase from medium to high pressures (2.5--5 bar). Increasing the water flow rate results in a shift towards an unstable flow regime. An increase in system pressure suppresses the observed flow instabilities. The presence of non-condensable gas also stabilizes the system. Beyond some limit, the heat removal rate appears to be independent of the water injection rate. These findings suggest that there exist an optimum water mass flow rate for melt quenching between 0.3 and 1.0 kg/m2-s under the current composition, geometric scale, and anticipated accident condition pressures. Suggestions on how to

  11. Recommended Reference Genes for Quantitative PCR Analysis in Soybean Have Variable Stabilities during Diverse Biotic Stresses

    PubMed Central

    Bansal, Raman; Mittapelly, Priyanka; Cassone, Bryan J.; Mamidala, Praveen; Redinbaugh, Margaret G.; Michel, Andy

    2015-01-01

    For real-time reverse transcription-PCR (qRT-PCR) in soybean, reference genes in different tissues, developmental stages, various cultivars, and under stress conditions have been suggested but their usefulness for research on soybean under various biotic stresses occurring in North-Central U.S. is not known. Here, we investigated the expression stabilities of ten previously recommended reference genes (ABCT, CYP, EF1A, FBOX, GPDH, RPL30, TUA4, TUB4, TUA5, and UNK2) in soybean under biotic stress from Bean pod mottle virus (BPMV), powdery mildew (PMD), soybean aphid (SBA), and two‐spotted spider mite (TSSM). BPMV, PMD, SBA, and TSSM are amongst the most common pest problems on soybean in North-Central U.S. and other regions. Reference gene stability was determined using three software algorithms (geNorm, NormFinder, BestKeeper) and a web-based tool (RefFinder). Reference genes showed variability in their expression as well as stability across various stressors and the best reference genes were stress-dependent. ABCT and FBOX were found to be the most stable in soybean under both BPMV and SBA stress but these genes had only minimal to moderate stability during PMD and TSSM stress. Expression of TUA4 and CYP was found to be most stable during PMD stress; TUB4 and TUA4 were stable under TSSM stress. Under various biotic stresses on soybean analyzed, GPDH expression was found to be consistently unstable. For all biotic stressors on soybean, we obtained pairwise variation (V2/3) values less than 0.15 which suggested that combined use of the two most stable reference genes would be sufficient for normalization. Further, we demonstrated the utility of normalizing the qRT-PCR data for target genes using the most stable reference genes validated in current study. Following of the recommendations from our current study will enable an accurate and reliable normalization of qRT-PCR data in soybean under biotic stress. PMID:26244340

  12. Enterococcus faecalis Gene Transfer under Natural Conditions in Municipal Sewage Water Treatment Plants†

    PubMed Central

    Marcinek, Herbert; Wirth, Reinhard; Muscholl-Silberhorn, Albrecht; Gauer, Matthias

    1998-01-01

    The ability of Enterococcus faecalis to transfer various genetic elements under natural conditions was tested in two municipal sewage water treatment plants. Experiments in activated sludge basins of the plants were performed in a microcosm which allowed us to work under sterile conditions; experiments in anoxic sludge digestors were performed in dialysis bags. We used the following naturally occurring genetic elements: pAD1 and pIP1017 (two so-called sex pheromone plasmids with restricted host ranges, which are transferred at high rates under laboratory conditions); pIP501 (a resistance plasmid possessing a broad host range for gram-positive bacteria, which is transferred at low rates under laboratory conditions); and Tn916 (a conjugative transposon which is transferred under laboratory conditions at low rates to gram-positive bacteria and at very low rates to gram-negative bacteria). The transfer rate between different strains of E. faecalis under natural conditions was, compared to that under laboratory conditions, at least 105-fold lower for the sex pheromone plasmids, at least 100-fold lower for pIP501, and at least 10-fold lower for Tn916. In no case was transfer from E. faecalis to another bacterial species detected. By determining the dependence of transfer rates for pIP1017 on bacterial concentration and extrapolating to actual concentrations in the sewage water treatment plant, we calculated that the maximum number of transfer events for the sex pheromone plasmids between different strains of E. faecalis in the municipal sewage water treatment plant of the city of Regensburg ranged from 105 to 108 events per 4 h, indicating that gene transfer should take place under natural conditions. PMID:9464401

  13. Phylogeographic reconstruction of a bacterial species with high levels of lateral gene transfer

    USGS Publications Warehouse

    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

  14. Optimizing in vivo gene transfer into mouse corpus cavernosum by use of surface electroporation

    PubMed Central

    Song, Kang-Moon; Choi, Min Ji; Kwon, Mi-Hye; Ghatak, Kalyan; Park, Soo-Hwan; Ryu, Dong-Soo; Ryu, Ji-Kan

    2015-01-01

    Purpose Electroporation is known to enhance the efficiency of gene transfer through a transient increase in cell membrane permeability. The aim of this study was to determine the optimal conditions for in vivo electroporation-mediated gene delivery into mouse corpus cavernosum. Materials and Methods Diabetes was induced in C57BL/6 mice by intraperitoneal injections of streptozotocin. After intracavernous injection of pCMV-Luc (100 µg/40 µL), different electroporation settings (5-50 V, 8-16 pulses with a duration of 40-100 ms) were applied to the penis to establish the optimal conditions for electroporation. Gene expression was evaluated by luciferase assay. We also assessed the undesired consequences of electroporation by visual inspection and hematoxylin-eosin staining of penile tissue. Results Electroporation profoundly induced gene expression in the corpus cavernosum tissue of normal mice in a voltage-dependent manner. We observed electrical burn scars in the penis of normal mice who received electroporation with eight 40-ms pulses at a voltage of 50 V and sixteen 40-ms pulses, eight 100-ms pulses, and sixteen 100-ms pulses at a voltage of 30 V. No detectable burn scars were noted in normal mice stimulated with eight 40-ms pulses at a voltage of 30 V. Electroporation also significantly induced gene expression in diabetic mice stimulated with 40-ms pulse at a voltage of 30 V without injury to the penis. Conclusions We have established the optimal electroporation conditions for maximizing gene transfer into the corpus cavernosum of mice while avoiding damage to the erectile tissue. The electroporation-mediated gene delivery technique will be a valuable tool for gene therapy in the field of erectile dysfunction. PMID:25763123

  15. Bacterial α2-macroglobulins: colonization factors acquired by horizontal gene transfer from the metazoan genome?

    PubMed Central

    Budd, Aidan; Blandin, Stephanie; Levashina, Elena A; Gibson, Toby J

    2004-01-01

    Background Invasive bacteria are known to have captured and adapted eukaryotic host genes. They also readily acquire colonizing genes from other bacteria by horizontal gene transfer. Closely related species such as Helicobacter pylori and Helicobacter hepaticus, which exploit different host tissues, share almost none of their colonization genes. The protease inhibitor α2-macroglobulin provides a major metazoan defense against invasive bacteria, trapping attacking proteases required by parasites for successful invasion. Results Database searches with metazoan α2-macroglobulin sequences revealed homologous sequences in bacterial proteomes. The bacterial α2-macroglobulin phylogenetic distribution is patchy and violates the vertical descent model. Bacterial α2-macroglobulin genes are found in diverse clades, including purple bacteria (proteobacteria), fusobacteria, spirochetes, bacteroidetes, deinococcids, cyanobacteria, planctomycetes and thermotogae. Most bacterial species with bacterial α2-macroglobulin genes exploit higher eukaryotes (multicellular plants and animals) as hosts. Both pathogenically invasive and saprophytically colonizing species possess bacterial α2-macroglobulins, indicating that bacterial α2-macroglobulin is a colonization rather than a virulence factor. Conclusions Metazoan α2-macroglobulins inhibit proteases of pathogens. The bacterial homologs may function in reverse to block host antimicrobial defenses. α2-macroglobulin was probably acquired one or more times from metazoan hosts and has then spread widely through other colonizing bacterial species by more than 10 independent horizontal gene transfers. yfhM-like bacterial α2-macroglobulin genes are often found tightly linked with pbpC, encoding an atypical peptidoglycan transglycosylase, PBP1C, that does not function in vegetative peptidoglycan synthesis. We suggest that YfhM and PBP1C are coupled together as a periplasmic defense and repair system. Bacterial α2-macroglobulins might

  16. Stability maps, unstable periodic orbits and transfers in the Jovian system

    NASA Technical Reports Server (NTRS)

    Villac, Benjamin; Lara, Martin

    2005-01-01

    Low cost transfers of a spacecraft in a multi-gravitational orbital environment, which are based on connections between unstable periodic orbits, present several trade-offs, such time-of-flight v.s transfer fuel cost.

  17. High-efficiency gene transfer into CD34+ cells with a human immunodeficiency virus type 1-based retroviral vector pseudotyped with vesicular stomatitis virus envelope glycoprotein G.

    PubMed Central

    Akkina, R K; Walton, R M; Chen, M L; Li, Q X; Planelles, V; Chen, I S

    1996-01-01

    Currently, amphotropic retroviral vectors are widely used for gene transfer into CD34+ hematopoietic progenitor cells. The relatively low levels of transduction efficiency associated with these vectors in human cells is due to low viral titers and limitations in concentrating the virus because of the inherent fragility of retroviral envelopes. Here we show that a human immunodeficiency virus type 1 (HIV-1)-based retroviral vector containing the firefly luciferase reporter gene can be pseudotyped with a broad-host-range vesicular stomatitis virus envelope glycoprotein G (VSV-G). Higher-efficiency gene transfer into CD34+ cells was achieved with a VSV-G-pseudotyped HIV-1 vector than with a vector packaged in an amphotropic envelope. Concentration of virus without loss of viral infectivity permitted a higher multiplicity of infection, with a consequent higher efficiency of gene transfer, reaching 2.8 copies per cell. These vectors also showed remarkable stability during storage at 4 degrees C for a week. In addition, there was no significant loss of titer after freezing and thawing of the stock virus. The ability of VSV-G-pseudotyped retroviral vectors to achieve a severalfold increase in levels of transduction into CD34+ cells will allow high-efficiency gene transfer into hematopoietic progenitor cells for gene therapy purposes. Furthermore, since it has now become possible to infect CD34+ cells with pseudotyped HIV-1 with a high level of efficiency in vitro, many important questions regarding the effect of HIV-1 on lineage-specific differentiation of hematopoietic progenitors can now be addressed. PMID:8642689

  18. Gene Transfer by Guanidinium-Cholesterol Cationic Lipids into Airway Epithelial Cells in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Oudrhiri, Noufissa; Vigneron, Jean-Pierre; Peuchmaur, Michel; Leclerc, Tony; Lehn, Jean-Marie; Lehn, Pierre

    1997-03-01

    Synthetic vectors represent an attractive alternative approach to viral vectors for gene transfer, in particular into airway epithelial cells for lung-directed gene therapy for cystic fibrosis. Having recently found that guanidinium-cholesterol cationic lipids are efficient reagents for gene transfer into mammalian cell lines in vitro, we have investigated their use for gene delivery into primary airway epithelial cells in vitro and in vivo. The results obtained indicate that the lipid bis (guanidinium)-tren-cholesterol (BGTC) can be used to transfer a reporter gene into primary human airway epithelial cells in culture. Furthermore, liposomes composed of BGTC and dioleoyl phosphatidylethanolamine (DOPE) are efficient for gene delivery to the mouse airway epithelium in vivo. Transfected cells were detected both in the surface epithelium and in submucosal glands. In addition, the transfection efficiency of BGTC/DOPE liposomes in vivo was quantitatively assessed by using the luciferase reporter gene system.

  19. Gene transfer into hematopoietic stem cells as treatment for primary immunodeficiency diseases.

    PubMed

    Candotti, Fabio

    2014-04-01

    Gene transfer into the hematopoietic stem cell has shown curative potential for a variety of hematological disorders. Primary immunodeficiency diseases have led to the way in this field of gene therapy as an example and a model. Clinical results from the past 15 years have shown that significant improvement and even cure can be achieved for diseases such as X-linked severe combined immunodeficiency, adenosine deaminase deficiency, chronic granulomatous disease and Wiskott-Aldrich syndrome. Unfortunately, with the initial clear clinical benefits, the first serious complications of gene therapy have also occurred. In a significant number of patients treated using vectors based on murine gamma-retroviruses and carrying powerful viral enhancer elements, insertional oncogenesis events have resulted in acute leukemias that, in some cases, have had fatal outcomes. These serious adverse events have sparked a revision of the assessment of risks and benefits of integrating gene transfer for hematological diseases and prompted the development and application of new generations of viral vectors with recognized superior safety characteristics. This review summarizes the clinical experience of gene therapy for primary immunodeficiencies and discusses the likely avenues of progress in the future development of this expanding field of clinical investigations. PMID:24488786

  20. Sleeping Beauty-Mediated Drug Resistance Gene Transfer in Human Hematopoietic Progenitor Cells.

    PubMed

    Hyland, Kendra A; Olson, Erik R; McIvor, R Scott

    2015-10-01

    The Sleeping Beauty (SB) transposon system can insert sequences into mammalian chromosomes, supporting long-term expression of both reporter and therapeutic genes. Hematopoietic progenitor cells (HPCs) are an ideal therapeutic gene transfer target as they are used in therapy for a variety of hematologic and metabolic conditions. As successful SB-mediated gene transfer into human CD34(+) HPCs has been reported by several laboratories, we sought to extend these studies to the introduction of a therapeutic gene conferring resistance to methotrexate (MTX), potentially providing a chemoprotective effect after engraftment. SB-mediated transposition of hematopoietic progenitors, using a transposon encoding an L22Y variant dihydrofolate reductase fused to green fluorescent protein, conferred resistance to methotrexate and dipyridamole, a nucleoside transport inhibitor that tightens MTX selection conditions, as assessed by in vitro hematopoietic colony formation. Transposition of individual transgenes was confirmed by sequence analysis of transposon-chromosome junctions recovered by linear amplification-mediated PCR. These studies demonstrate the potential of SB-mediated transposition of HPCs for expression of drug resistance genes for selective and chemoprotective applications. PMID:26176276

  1. Influence of microarrays experiments missing values on the stability of gene groups by hierarchical clustering

    PubMed Central

    de Brevern, Alexandre G; Hazout, Serge; Malpertuy, Alain

    2004-01-01

    Background Microarray technologies produced large amount of data. The hierarchical clustering is commonly used to identify clusters of co-expressed genes. However, microarray datasets often contain missing values (MVs) representing a major drawback for the use of the clustering methods. Usually the MVs are not treated, or replaced by zero or estimated by the k-Nearest Neighbor (kNN) approach. The topic of the paper is to study the stability of gene clusters, defined by various hierarchical clustering algorithms, of microarrays experiments including or not MVs. Results In this study, we show that the MVs have important effects on the stability of the gene clusters. Moreover, the magnitude of the gene misallocations is depending on the aggregation algorithm. The most appropriate aggregation methods (e.g. complete-linkage and Ward) are highly sensitive to MVs, and surprisingly, for a very tiny proportion of MVs (e.g. 1%). In most of the case, the MVs must be replaced by expected values. The MVs replacement by the kNN approach clearly improves the identification of co-expressed gene clusters. Nevertheless, we observe that kNN approach is less suitable for the extreme values of gene expression. Conclusion The presence of MVs (even at a low rate) is a major factor of gene cluster instability. In addition, the impact depends on the hierarchical clustering algorithm used. Some methods should be used carefully. Nevertheless, the kNN approach constitutes one efficient method for restoring the missing expression gene values, with a low error level. Our study highlights the need of statistical treatments in microarray data to avoid misinterpretation. PMID:15324460

  2. Multiple Phenotypic Changes Associated with Large-Scale Horizontal Gene Transfer

    PubMed Central

    Dougherty, Kevin; Smith, Brian A.; Moore, Autumn F.; Maitland, Shannon; Fanger, Chris; Murillo, Rachel; Baltrus, David A.

    2014-01-01

    Horizontal gene transfer often leads to phenotypic changes within recipient organisms independent of any immediate evolutionary benefits. While secondary phenotypic effects of horizontal transfer (i.e., changes in growth rates) have been demonstrated and studied across a variety of systems using relatively small plasmids and phage, little is known about the magnitude or number of such costs after the transfer of larger regions. Here we describe numerous phenotypic changes that occur after a large-scale horizontal transfer event (∼1 Mb megaplasmid) within Pseudomonas stutzeri including sensitization to various stresses as well as changes in bacterial behavior. These results highlight the power of horizontal transfer to shift pleiotropic relationships and cellular networks within bacterial genomes. They also provide an important context for how secondary effects of transfer can bias evolutionary trajectories and interactions between species. Lastly, these results and system provide a foundation to investigate evolutionary consequences in real time as newly acquired regions are ameliorated and integrated into new genomic contexts. PMID:25048697

  3. Enhanced Horizontal Transfer of Antibiotic Resistance Genes in Freshwater Microcosms Induced by an Ionic Liquid

    PubMed Central

    Wang, Qing; Mao, Daqing; Mu, Quanhua; Luo, Yi

    2015-01-01

    The spread and propagation of antibiotic resistance genes (ARGs) is a worldwide public health concern. Ionic liquids (ILs), considered as “environmentally friendly” replacements for industrial organic solvents, have been widely applied in modern industry. However, few data have been collected regarding the potential ecological and environmental risks of ILs, which are important for preparing for their potential discharge into the environment. In this paper, the IL 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) (0.001-5.0 g/L) was tested for its effects on facilitating ARGs horizontal transfer mediated by plasmid RP4 in freshwater microcosms. In the horizontal transfer microcosms, the transfer frequency of plasmid RP4 was significantly enhanced (60-fold higher than untreated groups) by the IL [BMIm][PF6] (1.0 g/L). Meanwhile, two strains of opportunistic pathogen Acinetobacter spp. and Salmonella spp. were isolated among the transconjugants, illustrating plasmid RP4 mediated horizontal transfer of ARGs occurred in pathogen. This could increase the risk of ARGs dissemination to human pathogens and pose great threat to public health. The cause that [BMIm[PF6] enhanced the transfer frequency of plasmid RP4 was proposed by suppressed cell membrane barrier and enhanced cell membrane permeability, which was evidenced by flow cytometry (FCM). This is the first report that some ILs facilitate horizontal transfer of plasmid RP4 which is widely distributed in the environment and thus add the adverse effects of the environmental risk of ILs. PMID:25951456

  4. Stability of gene contributions and identification of outliers in multivariate analysis of microarray data

    PubMed Central

    Baty, Florent; Jaeger, Daniel; Preiswerk, Frank; Schumacher, Martin M; Brutsche, Martin H

    2008-01-01

    Background Multivariate ordination methods are powerful tools for the exploration of complex data structures present in microarray data. These methods have several advantages compared to common gene-by-gene approaches. However, due to their exploratory nature, multivariate ordination methods do not allow direct statistical testing of the stability of genes. Results In this study, we developed a computationally efficient algorithm for: i) the assessment of the significance of gene contributions and ii) the identification of sample outliers in multivariate analysis of microarray data. The approach is based on the use of resampling methods including bootstrapping and jackknifing. A statistical package of R functions was developed. This package includes tools for both inferring the statistical significance of gene contributions and identifying outliers among samples. Conclusion The methodology was successfully applied to three published data sets with varying levels of signal intensities. Its relevance was compared with alternative methods. Overall, it proved to be particularly effective for the evaluation of the stability of microarray data. PMID:18570644

  5. [Viral transfer of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in gene therapy].

    PubMed

    Wędrowska, Ewelina; Wandtke, Tomasz; Dyczek, Andrzej; Woźniak, Joanna

    2015-01-01

    Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively induces carcinoma cell death through the extrinsic pathway of apoptosis. Preclinical trials of gene therapy have been conducted using viral transfer of the TRAIL transgene into prostate, bladder, breast, kidney, liver, non-small cell lung cancer and also glioblastoma cells. Experiments in vitro demonstrated the extensive apoptosis of target cells as well as frequent disease regression or remission. TRAIL transfer did not show any side effects, opposite to chemotherapy. Encouraging results of TRAIL-related gene therapy were observed in rheumatoid arthritis and type 1 diabetes. Adenoviral vectors (AdV) encoding TRAIL are the most promising tool in anti-tumor therapy. They have undergone numerous modifications by increasing transfection efficiency and transgene expression in target cells. However, only one clinical phase I trial has been performed. AdV encoding the TRAIL transgene caused local inflammation and apoptosis in patients with prostate cancer. PMID:27259213

  6. Transfer of antibiotic-resistance genes via phage-related mobile elements.

    PubMed

    Brown-Jaque, Maryury; Calero-Cáceres, William; Muniesa, Maite

    2015-05-01

    Antibiotic resistance is a major concern for society because it threatens the effective prevention of infectious diseases. While some bacterial strains display intrinsic resistance, others achieve antibiotic resistance by mutation, by the recombination of foreign DNA into the chromosome or by horizontal gene acquisition. In many cases, these three mechanisms operate together. Several mobile genetic elements (MGEs) have been reported to mobilize different types of resistance genes and despite sharing common features, they are often considered and studied separately. Bacteriophages and phage-related particles have recently been highlighted as MGEs that transfer antibiotic resistance. This review focuses on phages, phage-related elements and on composite MGEs (phages-MGEs) involved in antibiotic resistance mobility. We review common features of these elements, rather than differences, and provide a broad overview of the antibiotic resistance transfer mechanisms observed in nature, which is a necessary first step to controlling them. PMID:25597519

  7. Light-controlled inhibition of malignant glioma by opsin gene transfer

    PubMed Central

    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

  8. Interkingdom Gene Transfer May Contribute to the Evolution of Phytopathogenicity in Botrytis Cinerea

    PubMed Central

    Zhu, Bo; Zhou, Qing; Xie, Guanlin; Zhang, Guoqing; Zhang, Xiaowei; Wang, Yanli; Sun, Gunchang; Li, Bin; Jin, Gulei

    2012-01-01

    The ascomycete Botrytis cinerea is a phytopathogenic fungus infecting and causing significant yield losses in a number of crops. The genome of B. cinerea has been fully sequenced while the importance of horizontal gene transfer (HGT) to extend the host range in plant pathogenic fungi has been recently appreciated. However, recent data confirm that the B. cinerea fungus shares conserved virulence factors with other fungal plant pathogens with narrow host range. Therefore, interkingdom HGT may contribute to the evolution of phytopathogenicity in B. cinerea. In this study, a stringent genome comparison pipeline was used to identify potential genes that have been obtained by B. cinerea but not by other fungi through interkingdom HGT. This search led to the identification of four genes: a UDP-glucosyltransferase (UGT), a lipoprotein and two alpha/beta hydrolase fold proteins. Phylogenetic analysis of the four genes suggests that B. cinerea acquired UGT from plants and the other 3 genes from bacteria. Based on the known gene functions and literature searching, a correlation between gene acquision and the evolution of pathogenicity in B. cinerea can be postulated. PMID:22346340

  9. Effects of laser parameters on propagation characteristics of laser-induced stress wave for gene transfer

    NASA Astrophysics Data System (ADS)

    Ando, Takahiro; Sato, Shunichi; Terakawa, Mitsuhiro; Ashida, Hiroshi; Obara, Minoru

    2010-02-01

    Laser-based gene delivery is attractive as a new method for topical gene therapy because of the high spatial controllability of laser energy. Previously, we demonstrated that an exogenous gene can be transferred to cells both in vitro and in vivo by applying nanosecond pulsed laser-induced stress waves (LISWs) or photomechanical waves (PMWs). In this study, we investigated effects of laser parameters on the propagation characteristics of LISWs in soft tissue phantoms and depth-dependent properties of gene transfection. Temporal pressure profiles of LISWs were measured with a hydrophone, showing that with a larger laser spot diameter, LISWs can be propagated more efficiently in phantoms with keeping flat wavefront. Phantoms with various thicknesses were placed on the rat dorsal skin that had been injected with plasmid DNA coding for reporter gene, and LISWs were applied from the top of the phantom. Efficient gene expression was observed in the rat skin that had interacted with LISWs propagating through a 15-mm-thick phantom. These results would be useful to determine appropriate laser parameters for gene delivery to deep-located tissue by transcutaneous application of LISWs.

  10. Bacteriophages Isolated from Chicken Meat and the Horizontal Transfer of Antimicrobial Resistance Genes.

    PubMed

    Shousha, Amira; Awaiwanont, Nattakarn; Sofka, Dmitrij; Smulders, Frans J M; Paulsen, Peter; Szostak, Michael P; Humphrey, Tom; Hilbert, Friederike

    2015-07-01

    Antimicrobial resistance in microbes poses a global and increasing threat to public health. The horizontal transfer of antimicrobial resistance genes was thought to be due largely to conjugative plasmids or transposons, with only a minor part being played by transduction through bacteriophages. However, whole-genome sequencing has recently shown that the latter mechanism could be highly important in the exchange of antimicrobial resistance genes between microorganisms and environments. The transfer of antimicrobial resistance genes by phages could underlie the origin of resistant bacteria found in food. We show that chicken meat carries a number of phages capable of transferring antimicrobial resistance. Of 243 phages randomly isolated from chicken meat, about a quarter (24.7%) were able to transduce resistance to one or more of the five antimicrobials tested into Escherichia coli ATCC 13706 (DSM 12242). Resistance to kanamycin was transduced the most often, followed by that to chloramphenicol, with four phages transducing tetracycline resistance and three transducing ampicillin resistance. Phages able to transduce antimicrobial resistance were isolated from 44% of the samples of chicken meat that we tested. The statistically significant (P = 0.01) relationship between the presence of phages transducing kanamycin resistance and E. coli isolates resistant to this antibiotic suggests that transduction may be an important mechanism for transferring kanamycin resistance to E. coli. It appears that the transduction of resistance to certain antimicrobials, e.g., kanamycin, not only is widely distributed in E. coli isolates found on meat but also could represent a major mechanism for resistance transfer. The result is of high importance for animal and human health. PMID:25934615

  11. Bacteriophages Isolated from Chicken Meat and the Horizontal Transfer of Antimicrobial Resistance Genes

    PubMed Central

    Shousha, Amira; Awaiwanont, Nattakarn; Sofka, Dmitrij; Smulders, Frans J. M.; Paulsen, Peter; Szostak, Michael P.; Humphrey, Tom

    2015-01-01

    Antimicrobial resistance in microbes poses a global and increasing threat to public health. The horizontal transfer of antimicrobial resistance genes was thought to be due largely to conjugative plasmids or transposons, with only a minor part being played by transduction through bacteriophages. However, whole-genome sequencing has recently shown that the latter mechanism could be highly important in the exchange of antimicrobial resistance genes between microorganisms and environments. The transfer of antimicrobial resistance genes by phages could underlie the origin of resistant bacteria found in food. We show that chicken meat carries a number of phages capable of transferring antimicrobial resistance. Of 243 phages randomly isolated from chicken meat, about a quarter (24.7%) were able to transduce resistance to one or more of the five antimicrobials tested into Escherichia coli ATCC 13706 (DSM 12242). Resistance to kanamycin was transduced the most often, followed by that to chloramphenicol, with four phages transducing tetracycline resistance and three transducing ampicillin resistance. Phages able to transduce antimicrobial resistance were isolated from 44% of the samples of chicken meat that we tested. The statistically significant (P = 0.01) relationship between the presence of phages transducing kanamycin resistance and E. coli isolates resistant to this antibiotic suggests that transduction may be an important mechanism for transferring kanamycin resistance to E. coli. It appears that the transduction of resistance to certain antimicrobials, e.g., kanamycin, not only is widely distributed in E. coli isolates found on meat but also could represent a major mechanism for resistance transfer. The result is of high importance for animal and human health. PMID:25934615

  12. Transcriptional reprogramming of gene expression in bovine somatic cell chromatin transfer embryos

    PubMed Central

    Rodriguez-Osorio, Nelida; Wang, Zhongde; Kasinathan, Poothappillai; Page, Grier P; Robl, James M; Memili, Erdogan

    2009-01-01

    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. PMID:19393066

  13. Glutaric acidemia type II: gene structure and mutations of the electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO) gene.

    PubMed

    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. PMID:12359134

  14. Determination of lateral-stability derivatives and transfer-function coefficients from frequency-response data for lateral motions

    NASA Technical Reports Server (NTRS)

    Donegan, James J; Robinson, Samuel W , Jr; Gates, Ordway, B , jr

    1955-01-01

    A method is presented for determining the lateral-stability derivatives, transfer-function coefficients, and the modes for lateral motion from frequency-response data for a rigid aircraft. The method is based on the application of the vector technique to the equations of lateral motion, so that the three equations of lateral motion can be separated into six equations. The method of least squares is then applied to the data for each of these equations to yield the coefficients of the equations of lateral motion from which the lateral-stability derivatives and lateral transfer-function coefficients are computed. Two numerical examples are given to demonstrate the use of the method.

  15. Loss and stabilization of amplified dihydrofolate reductase genes in mouse sarcoma S-180 cell lines

    SciTech Connect

    Kaufman, R.J.; Brown, P.C.; Schimke, R.T.

    1981-12-01

    The authors studied the loss and stabilization of dihydrofolate reductase genes in clones of a methotrexate-resistant murine S-180 cell line. These cells contained multiple copies of the dihydrofolate reductase gene which were associated with double minute chromosomes. The growth rate of these cells in the absence of methotrexate was inversely related to the degree of gene amplification (number of double minute chromosomes). Cells could both gain and lose genes as a result of an unequal distribution of double minute chromosomes into daughter cells at mitosis. The loss of amplified dihydrofolate reductase genes during growth in the absence of methotrexate resulted from the continual generation of cells containing lower numbers of double minute chromosomes. Because of the growth advantage of these cells, they became dominant in the population. They also studied an unstably resistant S-180 cell line (clone) that, after 3 years of continuous growth in methotrexate, generated cells containing stably amplified dihydrofolate reductase genes. These genes were present on one or more chromosomes, and they were retained in a stable state.

  16. Phage-mediated transfer of a dextranase gene in Lactobacillus sanfranciscensis and characterization of the enzyme.

    PubMed

    Picozzi, Claudia; Meissner, Daniel; Chierici, Margherita; Ehrmann, Matthias A; Vigentini, Ileana; Foschino, Roberto; Vogel, Rudi F

    2015-06-01

    While phages of lactobacilli are extensively studied with respect to their structure and role in the dairy environment, knowledge about phages in bacteria residing in sourdough fermentation is limited. Based on the previous finding that the Lactobacillus sanfranciscensis phage EV3 carries a putative dextranase gene (dex), we have investigated the distribution of similar dex(+) phages in L. sanfranciscensis, the chance of gene transfer and the properties of the dextranase encoded by phage EV3. L. sanfranciscensis H2A (dex(-)), originally isolated from a wheat sourdough, expressed a Dex(+) phenotype upon infection with EV3. The dextranase gene was isolated from the transductant and heterologously expressed in Escherichia coli. The gene encoded a protein of 801 amino acids with a calculated molecular weight (Mw) of 89.09 kDa and a calculated pI of 5.62. Upon purification aided by a 6-His tag, enzyme kinetic parameters were determined. The Km value was 370 mM, and the Vmax was calculated in about 16 μmol of glucose released from dextran by 1 mg of enzyme in 1 min in a buffer solution at pH 5.0. The optimum conditions were 60 °C and pH 4.5. The enzyme retained its activity for >3h at 60 °C and exhibited only 40% activity at 30 °C; the highest homology of 72% was found to a dextranase gene from Lactobacillus fermentum phage φPYB5. Within 25 L. sanfransiscensis isolates tested, the strain 4B5 carried a similar prophage encoding a dextranase gene. Our data suggest a phage-mediated transfer of dextranase genes in the sourdough environment resulting in superinfection-resistant L. sanfranciscensis Dex(+) strains with a possible ecological advantage in dextran-containing sourdoughs. PMID:25771219

  17. Clinical trial design issues raised during recombinant DNA advisory committee review of gene transfer protocols.

    PubMed

    Scharschmidt, Tiffany; Lo, Bernard

    2006-04-01

    Gene transfer clinical trial protocols are reviewed by the Recombinant DNA Advisory Committee (RAC). Identifying the design concerns and suggestions commonly raised during RAC review may help investigators and sponsors shorten the process of protocol development and improve the quality of gene transfer trials. We therefore examined 53 full public reviews of gene transfer clinical trial protocols performed by the RAC between December 2000 and June 2004 to determine what trial design concerns or suggestions RAC members raised during written review or public discussion or in the formal letter to investigators after the review was completed. We also determined how frequently these concerns were raised. We found that RAC members raised issues regarding selection of subjects in 89% of reviews, dose escalation in 77%, selection of safety end points in 76%, biological activity measures in 66%, and overall design in 60% of reviews. The most common issue raised by RAC reviewers was the need to exclude subjects at increased risk for adverse events. Furthermore, in 89% of reviews, at least one design issue pertaining to safety of participants was raised. In 91% of reviews, at least one design concern was presented as a written RAC recommendation or concern to the investigator after the public review. When submitting protocols for RAC review, investigators and sponsors might devote more attention to issues that RAC reviewers commonly raise. Such attention might help strengthen clinical trial protocols, shorten the protocol development process, and enhance the protection of research participants. PMID:16610932

  18. The Use of Chromatin Insulators to Improve the Expression and Safety of Integrating Gene Transfer Vectors

    PubMed Central

    2011-01-01

    Abstract The therapeutic application of recombinant retroviruses and other integrating gene transfer vectors has been limited by problems of vector expression and vector-mediated genotoxicity. These problems arise in large part from the interactions between vector sequences and the genomic environment surrounding sites of integration. Strides have been made in overcoming both of these problems through the modification of deleterious vector sequences, the inclusion of better enhancers and promoters, and the use of alternative virus systems. However, these modifications often add other restrictions on vector design, which in turn can further limit therapeutic applications. As an alternative, several groups have been investigating a class of DNA regulatory elements known as chromatin insulators. These elements provide a means of blocking the interaction between an integrating vector and the target cell genome in a manner that is independent of the vector transgene, regulatory elements, or virus of origin. This review outlines the background, rationale, and evidence for using chromatin insulators to improve the expression and safety of gene transfer vectors. Also reviewed are topological factors that constrain the use of insulators in integrating gene transfer vectors, alternative sources of insulators, and the role of chromatin insulators as one of several components for optimal vector design. PMID:21247248

  19. Mechanism by which calcium phosphate coprecipitation enhances adenovirus-mediated gene transfer.

    PubMed

    Walters, R; Welsh, M

    1999-11-01

    Delivery of a normal copy of CFTR cDNA to airway epithelia may provide a novel treatment for cystic fibrosis lung disease. Unfortunately, current vectors are inefficient because of limited binding to the apical surface of airway epithelia. We recently reported that incorporation of adenovirus in a calcium phosphate coprecipitate (Ad:CaPi) improves adenovirus-mediated gene transfer to airway epithelia in vitro and in vivo. To understand better how coprecipitation improves gene transfer, we tested the hypothesis that incorporation in a CaPi coprecipitate increases the binding of adenovirus to the apical surface of differentiated human airway epithelia. When a Cy3-labelled adenovirus was delivered in a coprecipitate, binding increased 54-fold as compared with adenovirus alone. Moreover, infection by Ad:CaPi was independent of fiber knob-CAR and penton base-integrin interactions. After binding to the cell surface, the virus must enter the cell in order to infect. We hypothesized that Ad:CaPi may stimulate fluid phase endocytosis, thereby facilitating entry. However, we found that neither adenovirus nor Ad:CaPi coprecipitates altered fluid phase endocytosis. Nevertheless, Ad:CaPi preferentially infected cells showing endocytosis. Thus, CaPi coprecipitation improves adenovirus-mediated gene transfer by coating the epithelial surface with a layer of virus which enters cells during the normal process of endocytosis. PMID:10602380

  20. Cross-species gene-family fluctuations reveal the dynamics of horizontal transfers

    PubMed Central

    Grilli, Jacopo; Romano, Mariacristina; Bassetti, Federico; Cosentino Lagomarsino, Marco

    2014-01-01

    Prokaryotes vary their protein repertoire mainly through horizontal transfer and gene loss. To elucidate the links between these processes and the cross-species gene-family statistics, we perform a large-scale data analysis of the cross-species variability of gene-family abundance (the number of members of the family found on a given genome). We find that abundance fluctuations are related to the rate of horizontal transfers. This is rationalized by a minimal theoretical model, which predicts this link. The families that are not captured by the model show abundance profiles that are markedly peaked around a mean value, possibly because of specific abundance selection. Based on these results, we define an abundance variability index that captures a family's evolutionary behavior (and thus some of its relevant functional properties) purely based on its cross-species abundance fluctuations. Analysis and model, combined, show a quantitative link between cross-species family abundance statistics and horizontal transfer dynamics, which can be used to analyze genome ‘flux’. Groups of families with different values of the abundance variability index correspond to genome sub-parts having different plasticity in terms of the level of horizontal exchange allowed by natural selection. PMID:24829449

  1. Novel recA-Independent Horizontal Gene Transfer in Escherichia coli K-12

    PubMed Central

    Kingston, Anthony W.; Raleigh, Elisabeth A.

    2015-01-01

    In bacteria, mechanisms that incorporate DNA into a genome without strand-transfer proteins such as RecA play a major role in generating novelty by horizontal gene transfer. We describe a new illegitimate recombination event in Escherichia coli K-12: RecA-independent homologous replacements, with very large (megabase-length) donor patches replacing recipient DNA. A previously uncharacterized gene (yjiP) increases the frequency of RecA-independent replacement recombination. To show this, we used conjugal DNA transfer, combining a classical conjugation donor, HfrH, with modern genome engineering methods and whole genome sequencing analysis to enable interrogation of genetic dependence of integration mechanisms and characterization of recombination products. As in classical experiments, genomic DNA transfer begins at a unique position in the donor, entering the recipient via conjugation; antibiotic resistance markers are then used to select recombinant progeny. Different configurations of this system were used to compare known mechanisms for stable DNA incorporation, including homologous recombination, F’-plasmid formation, and genome duplication. A genome island of interest known as the immigration control region was specifically replaced in a minority of recombinants, at a frequency of 3 X 10-12 CFU/recipient per hour. PMID:26162088

  2. Novel recA-Independent Horizontal Gene Transfer in Escherichia coli K-12.

    PubMed

    Kingston, Anthony W; Roussel-Rossin, Chloé; Dupont, Claire; Raleigh, Elisabeth A

    2015-01-01

    In bacteria, mechanisms that incorporate DNA into a genome without strand-transfer proteins such as RecA play a major role in generating novelty by horizontal gene transfer. We describe a new illegitimate recombination event in Escherichia coli K-12: RecA-independent homologous replacements, with very large (megabase-length) donor patches replacing recipient DNA. A previously uncharacterized gene (yjiP) increases the frequency of RecA-independent replacement recombination. To show this, we used conjugal DNA transfer, combining a classical conjugation donor, HfrH, with modern genome engineering methods and whole genome sequencing analysis to enable interrogation of genetic dependence of integration mechanisms and characterization of recombination products. As in classical experiments, genomic DNA transfer begins at a unique position in the donor, entering the recipient via conjugation; antibiotic resistance markers are then used to select recombinant progeny. Different configurations of this system were used to compare known mechanisms for stable DNA incorporation, including homologous recombination, F'-plasmid formation, and genome duplication. A genome island of interest known as the immigration control region was specifically replaced in a minority of recombinants, at a frequency of 3 X 10(-12) CFU/recipient per hour. PMID:26162088

  3. Age-related changes in relative expression stability of commonly used housekeeping genes in selected porcine tissues

    PubMed Central

    2011-01-01

    Background Gene expression analysis using real-time RT-PCR (qRT-PCR) is increasingly important in biological research due to the high-throughput and accuracy of qRT-PCR. For accurate and reliable gene expression analysis, normalization of gene expression data against housekeeping genes or internal control genes is required. The stability of reference genes has a tremendous effect on the results of relative quantification of gene expression by qRT-PCR. The expression stability of reference genes could vary according to tissues, age of individuals and experimental conditions. In the pig however, very little information is available on the expression stability of reference genes. The aim of this research was therefore to develop a new set of reference genes which can be used for normalization of mRNA expression data of genes expressed in varieties of porcine tissues at different ages. Results The mRNA expression stability of nine commonly used reference genes (B2M, BLM, GAPDH, HPRT1, PPIA, RPL4, SDHA, TBP and YWHAZ) was determined in varieties of tissues collected from newborn, young and adult pigs. geNorm, NormFinder and BestKeeper software were used to rank the genes according to their stability. geNorm software revealed that RPL4, PPIA and YWHAZ showed high stability in newborn and adult pigs, while B2M, YWHAZ and SDHA showed high stability in young pigs. In all cases, GAPDH showed the least stability in geNorm. NormFinder revealed that TBP was the most stable gene in newborn and young pigs, while PPIA was most stable in adult pigs. Moreover, geNorm software suggested that the geometric mean of three most stable gene would be the suitable combination for accurate normalization of gene expression study. Conclusions Although, there was discrepancy in the ranking order of reference genes obtained by different analysing software methods, the geometric mean of the RPL4, PPIA and YWHAZ seems to be the most appropriate combination of housekeeping genes for accurate

  4. Long Term Thermal Stability In Air Of Ionic Liquid Based Alternative Heat Transfer Fluids For Clean Energy Production

    SciTech Connect

    Fox, Elise B; Kendrick, Sarah E.; Visser, Ann E.; Bridges, Nicholas J.

    2012-10-15

    The purpose of this study was to investigate the effect of long-term aging on the thermal stability and chemical structure of seven different ILs so as to explore their suitability for use as a heat transfer fluid. This was accomplished by heating the ILs for 15 weeks at 200°C in an oxidizing environment and performing subsequent analyses on the aged chemicals.

  5. In Vivo Gene Transfer Strategies to Achieve Partial Correction of von Willebrand Disease

    PubMed Central

    Wang, Lan; Rosenberg, Jonathan B.; De, Bishnu P.; Ferris, Barbara; Wang, Rui; Rivella, Stefano; Kaminsky, Stephen M.

    2012-01-01

    Abstract von Willebrand disease (VWD), the most common hereditary coagulation disorder, results from mutations in the 52-exon gene for von Willebrand factor (VWF), which encodes an 8.4-kB cDNA. Studies with VWF cDNA plasmids have demonstrated that in vivo gene transfer to the liver will correct the coagulation dysfunction in VWF−/− mice, but the correction is transient. To develop gene therapy for VWF that would mediate long-term expression of the VWF cDNA in liver, we first evaluated segmental pre-mRNA trans-splicing (SPTS) with two adeno-associated virus (AAV) serotype 8 vectors, each delivering one-half of the VWF cDNA. However, although the two vectors functioned well to generate VWF multimers after infection of cells in vitro, the efficiency of SPTS was insufficient to correct the VWF−/− mouse in vivo. As an alternative, we assessed the ability of a lentiviral vector to transfer the intact murine VWF cDNA in vivo directly to the neonatal liver of VWF−/− mice, using generation of VWF multimers, bleeding time, and bleeding volume as efficacy parameters. The VWF lentivirus generated VWF multimers and partially or completely corrected the coagulation defect on a persistent basis in 33% of the treated VWF-deficient mice. On the basis of the concept that partial persistent correction with gene transfer could be beneficial in VWD patients, these observations suggest that lentiviral delivery of VWF cDNA should be explored as a candidate for gene therapy in patients with a severe form of VWD. PMID:22482515

  6. Gene therapy approaches against cancer using in vivo and ex vivo gene transfer of interleukin-12.

    PubMed

    Hernandez-Alcoceba, Ruben; Poutou, Joanna; Ballesteros-Briones, María Cristina; Smerdou, Cristian

    2016-02-01

    IL-12 is an immunostimulatory cytokine with strong antitumor properties. Systemic administration of IL-12 in cancer patients led to severe toxic effects, prompting the development of gene therapy vectors able to express this cytokine locally in tumors. Both nonviral and viral vectors have demonstrated a high antitumor efficacy in preclinical tumor models. Some of these vectors, including DNA electroporation, adenovirus and ex vivo transduced dendritic cells, were tested in patients, showing low toxicity and moderate antitumor efficacy. IL-12 activity can be potentiated by molecules with immunostimulatory, antiangiogenic or cytotoxic activity. These combination therapies are of clinical interest because they could lower the threshold for IL-12 efficacy, increasing the therapeutic potential of gene therapy and preventing the toxicity mediated by this cytokine. PMID:26786809

  7. Airway gene transfer in a non-human primate: lentiviral gene expression in marmoset lungs.

    PubMed

    Farrow, N; Miller, D; Cmielewski, P; Donnelley, M; Bright, R; Parsons, D W

    2013-01-01

    Genetic therapies for cystic fibrosis (CF) must be assessed for safety and efficacy, so testing in a non-human primate (NHP) model is invaluable. In this pilot study we determined if the conducting airways of marmosets (n = 2) could be transduced using an airway pre-treatment followed by an intratracheal bolus dose of a VSV-G pseudotyped HIV-1 based lentiviral (LV) vector (LacZ reporter). LacZ gene expression (X-gal) was assessed after 7 days and found primarily in conducting airway epithelia as well as in alveolar regions. The LacZ gene was not detected in liver or spleen via qPCR. Vector p24 protein bio-distribution into blood was transient. Dosing was well tolerated. This preliminary study confirmed the transducibility of CF-relevant airway cell types. The marmoset is a promising NHP model for testing and translating genetic treatments for CF airway disease towards clinical trials. PMID:23412644

  8. Extensive horizontal gene transfer, duplication, and loss of chlorophyll synthesis genes in the algae

    DOE PAGESBeta

    Hunsperger, Heather M.; Randhawa, Tejinder; Cattolico, Rose Ann

    2015-02-10

    Two non-homologous, isofunctional enzymes catalyze the penultimate step of chlorophyll a synthesis in oxygenic photosynthetic organisms such as cyanobacteria, eukaryotic algae and land plants: the light independent (LIPOR) and light-dependent (POR) protochlorophyllide oxidoreductases. Whereas the distribution of these enzymes in cyanobacteria and land plants is well understood, the presence, loss, duplication, and replacement of these genes have not been surveyed in the polyphyletic and remarkably diverse eukaryotic algal lineages.

  9. Cancer-predisposition gene KLLN maintains pericentric H3K9 trimethylation protecting genomic stability

    PubMed Central

    Nizialek, Emily A.; Sankunny, Madhav; Niazi, Farshad; Eng, Charis

    2016-01-01

    Maintenance of proper chromatin states and genomic stability is vital for normal development and health across a range of organisms. Here, we report on the role of KLLN in maintenance of pericentric H3K9 trimethylation (H3K9me3) and genomic stability. Germline hypermethylation of KLLN, a gene uncovered well after the human genome project, has been linked to Cowden cancer-predisposition syndrome (CS) in PTEN wild-type cases. KLLN first identified as a p53-dependent tumor suppressor gene, was believed to bind randomly to DNA and cause S-phase arrest. Using chromatin immunoprecipitation-based sequencing (ChIP-seq), we demonstrated that KLLN binds to DNA regions enriched with H3K9me3. KLLN overexpression correlated with increased H3K9 methyltransferase activity and increased global H3K9me3, while knockdown of KLLN had an opposite effect. We also found KLLN to localize to pericentric regions, with loss of KLLN resulting in dysregulation of pericentric heterochromatin, with consequent chromosomal instability manifested by increased micronuclei formation and numerical chromosomal aberrations. Interestingly, we show that KLLN interacts with DBC1, with consequent abrogation of DBC1 inhibition of SUV39H1, a H3K9 methyltransferase, suggesting the mode of KLLN regulating H3K9me3. These results suggest a critical role for KLLN as a potential regulator of pericentric heterochromatin formation, genomic stability and gene expression. PMID:26673699

  10. Low-level infrared laser modulates muscle repair and chromosome stabilization genes in myoblasts.

    PubMed

    da Silva Neto Trajano, Larissa Alexsandra; Stumbo, Ana Carolina; da Silva, Camila Luna; Mencalha, Andre Luiz; Fonseca, Adenilson S

    2016-08-01

    Infrared laser therapy is used for skeletal muscle repair based on its biostimulative effect on satellite cells. However, shortening of telomere length limits regenerative potential in satellite cells, which occurs after each cell division cycle. Also, laser therapy could be more effective on non-physiologic tissues. This study evaluated low-level infrared laser exposure effects on mRNA expression from muscle injury repair and telomere stabilization genes in myoblasts in normal and stressful conditions. Laser fluences were those used in clinical protocols. C2C12 myoblast cultures were exposed to low-level infrared laser (10, 35, and 70 J/cm(2)) in standard or normal (10 %) and reduced (2 %) fetal bovine serum concentrations; total RNA was extracted for mRNA expression evaluation from muscle injury repair (MyoD and Pax7) and chromosome stabilization (TRF1 and TRF2) genes by real time quantitative polymerization chain reaction. Data show that low-level infrared laser increases the expression of MyoD and Pax7 in 10 J/cm(2) fluence, TRF1 expression in all fluences, and TRF2 expression in 70 J/cm(2) fluence in both 10 and 2 % fetal bovine serum. Low-level infrared laser increases mRNA expression from genes related to muscle repair and telomere stabilization in myoblasts in standard or normal and stressful conditions. PMID:27220530

  11. Cancer-predisposition gene KLLN maintains pericentric H3K9 trimethylation protecting genomic stability.

    PubMed

    Nizialek, Emily A; Sankunny, Madhav; Niazi, Farshad; Eng, Charis

    2016-05-01

    Maintenance of proper chromatin states and genomic stability is vital for normal development and health across a range of organisms. Here, we report on the role of KLLN in maintenance of pericentric H3K9 trimethylation (H3K9me3) and genomic stability. Germline hypermethylation of KLLN, a gene uncovered well after the human genome project, has been linked to Cowden cancer-predisposition syndrome (CS) in PTEN wild-type cases. KLLN first identified as a p53-dependent tumor suppressor gene, was believed to bind randomly to DNA and cause S-phase arrest. Using chromatin immunoprecipitation-based sequencing (ChIP-seq), we demonstrated that KLLN binds to DNA regions enriched with H3K9me3. KLLN overexpression correlated with increased H3K9 methyltransferase activity and increased global H3K9me3, while knockdown of KLLN had an opposite effect. We also found KLLN to localize to pericentric regions, with loss of KLLN resulting in dysregulation of pericentric heterochromatin, with consequent chromosomal instability manifested by increased micronuclei formation and numerical chromosomal aberrations. Interestingly, we show that KLLN interacts with DBC1, with consequent abrogation of DBC1 inhibition of SUV39H1, a H3K9 methyltransferase, suggesting the mode of KLLN regulating H3K9me3. These results suggest a critical role for KLLN as a potential regulator of pericentric heterochromatin formation, genomic stability and gene expression. PMID:26673699

  12. Horizontal gene transfer events reshape the global landscape of arm race between viruses and homo sapiens.

    PubMed

    Chen, Dong-Sheng; Wu, Yi-Quan; Zhang, Wei; Jiang, San-Jie; Chen, Shan-Ze

    2016-01-01

    Horizontal gene transfer (HGT) drives the evolution of recipient organism particularly if it provides a novel function which enhances the fitness or its adaption to the environment. Virus-host co-evolution is attractive for studying co-evolutionary processes, since viruses strictly replicate inside of the host cells and thus their evolution is inexorably tangled with host biology. HGT, as a mechanism of co-evolution between human and viruses, has been widely documented, however, the roles HGT play during the interaction between human and viruses are still in their infancy. In this study, we performed a comprehensive analysis on the genes horizontally transferred between viruses and their corresponding human hosts. Our study suggests that the HGT genes in human are predominantly enriched in immune related GO terms while viral HGT genes are tend to be encoded by viruses which promote the invasion of immune system of hosts. Based on our results, it gives us a hint about the evolution trajectory of HGT events. Overall, our study suggests that the HGT between human and viruses are highly relevant to immune interaction and probably reshaped the arm race between hosts and viruses. PMID:27270140

  13. Endothelial nitric oxide synthase gene transfer enhances dilation of newborn piglet pulmonary arteries.

    PubMed

    Aschner, J L; Kovacs, N; Perciaccante, J V; Figueroa, J P; Thrikawala, N; Robins, G S; Busija, D W

    1999-07-01

    We determined the expression and functional correlate of in vitro transfection with a recombinant adenoviral vector encoding the gene for bovine endothelial nitric oxide synthase (AdCMVeNOS) or Escherichia coli beta-galactosidase (AdCMVLacZ) in pulmonary endothelial cells (EC), vascular smooth muscle cells (VSMC), and pulmonary arteries (PA) from newborn piglets. AdCMVeNOS and AdCMVeLacZ vectors, grown in 293-cell monolayers, were purified by double-cesium gradient ultracentrifugation. Cell cultures and PA were incubated with increasing vector titers for 30 or 60 min, followed by incubation in fresh medium for 18 h at 37 degrees C. LacZ expression was assessed by histochemical staining; eNOS expression was evaluated by Western blot analysis. Functional eNOS expression was determined by measurement of cGMP and quantification of the relaxation response to bradykinin (BK). In PA, LacZ transgene expression was preferentially localized to the adventitia and endothelium. Increased eNOS protein expression was observed in EC and VSMC transfected with AdCMVeNOS. Functional studies revealed increased cGMP abundance in cultured cells and enhanced relaxation to BK in AdCMVeNOS-transfected PA. These studies demonstrate that gene transfer with AdCMVeNOS results in functional expression and altered vasoactive responses in the neonatal pulmonary vasculature. Gene transfer with replication-deficient adenovirus vectors is a useful tool for the study of targeted genes in vascular biology. PMID:10409217

  14. Mutations of the microsomal triglyceride-transfer-protein gene in abetalipoproteinemia.

    PubMed

    Narcisi, T M; Shoulders, C C; Chester, S A; Read, J; Brett, D J; Harrison, G B; Grantham, T T; Fox, M F; Povey, S; de Bruin, T W

    1995-12-01

    Elevated plasma levels of apolipoprotein B (apoB)-containing lipoproteins constitute a major risk factor for the development of coronary heart disease. In the rare recessively inherited disorder abetalipoproteinemia (ABL) the production of apoB-containing lipoproteins is abolished, despite no abnormality of the apoB gene. In the current study we have characterized the gene encoding a microsomal triglyceride-transfer protein (MTP), localized to chromosome 4q22-24, and have identified a mutation of the MTP gene in both alleles of all individuals in a cohort of eight patients with classical ABL. Each mutant allele is predicted to encode a truncated form of MTP with a variable number of aberrant amino acids at its C-terminal end. Expression of genetically engineered forms of MTP in Cos-1 cells indicates that the C-terminal portion of MTP is necessary for triglyceride-transfer activity. Deletion of 20 amino acids from the carboxyl terminus of the 894-amino-acid protein and a missense mutation of cysteine 878 to serine both abolished activity. These results establish that defects of the MTP gene are the predominant, if not sole, cause of hereditary ABL and that an intact carboxyl terminus is necessary for activity. PMID:8533758

  15. Horizontal gene transfer events reshape the global landscape of arm race between viruses and homo sapiens

    PubMed Central

    Chen, Dong-Sheng; Wu, Yi-Quan; Zhang, Wei; Jiang, San-Jie; Chen, Shan-Ze

    2016-01-01

    Horizontal gene transfer (HGT) drives the evolution of recipient organism particularly if it provides a novel function which enhances the fitness or its adaption to the environment. Virus-host co-evolution is attractive for studying co-evolutionary processes, since viruses strictly replicate inside of the host cells and thus their evolution is inexorably tangled with host biology. HGT, as a mechanism of co-evolution between human and viruses, has been widely documented, however, the roles HGT play during the interaction between human and viruses are still in their infancy. In this study, we performed a comprehensive analysis on the genes horizontally transferred between viruses and their corresponding human hosts. Our study suggests that the HGT genes in human are predominantly enriched in immune related GO terms while viral HGT genes are tend to be encoded by viruses which promote the invasion of immune system of hosts. Based on our results, it gives us a hint about the evolution trajectory of HGT events. Overall, our study suggests that the HGT between human and viruses are highly relevant to immune interaction and probably reshaped the arm race between hosts and viruses. PMID:27270140

  16. Mutations of the microsomal triglyceride-transfer-protein gene in abetalipoproteinemia

    SciTech Connect

    Narcisi, T.M.E.; Shoulders, C.C.; Chester, S.A.

    1995-12-01

    Elevated plasma levels of apolipoprotein B (apoB)-containing lipoproteins constitute a major risk factor for the development of coronary heart disease. In the rare recessively inherited disorder abetalipoproteinemia (ABL) the production of apoB-containing lipoproteins is abolished, despite no abnormality of the apoB gene. In the current study we have characterized the gene encoding a microsomal triglyceride-transfer protein (MTP), localized to chromosome 4q22-24, and have identified a mutation of the MTP gene in both alleles of all individuals in a cohort of eight patients with classical ABL. Each mutant allele is predicted to encode a truncated form of MTP with a variable number of aberrant amino acids at its C-terminal end. Expression of genetically engineered forms of MTP in Cos-1 cells indicates that the C-terminal portion of MTP is necessary for triglyceride-transfer activity. Deletion of 20 amino acids from the carboxyl terminus of the 894-amino-acid protein and a missense mutation of cysteine 878 to serine both abolished activity. These results establish that defects of the MTP gene are the predominant, if not sole, cause of hereditary ABL and that an intact carboxyl terminus is necessary for activity. 49 refs., 4 figs., 5 tabs.

  17. Intraarticular expression of biologically active interleukin 1-receptor-antagonist protein by ex vivo gene transfer.

    PubMed Central

    Bandara, G; Mueller, G M; Galea-Lauri, J; Tindal, M H; Georgescu, H I; Suchanek, M K; Hung, G L; Glorioso, J C; Robbins, P D; Evans, C H

    1993-01-01

    Gene therapy offers a radical different approach to the treatment of arthritis. Here we have demonstrated that two marker genes (lacZ and neo) and cDNA coding for a potentially therapeutic protein (human interleukin 1-receptor-antagonist protein; IRAP or IL-1ra) can be delivered, by ex vivo techniques, to the synovial lining of joints; intraarticular expression of IRAP inhibited intraarticular responses to interleukin 1. To achieve this, lapine synoviocytes were first transduced in culture by retroviral infection. The genetically modified synovial cells were then transplanted by intraarticular injection into the knee joints of rabbits, where they efficiently colonized the synovium. Assay of joint lavages confirmed the in vivo expression of biologically active human IRAP. With allografted cells, IRAP expression was lost by 12 days after transfer. In contrast, autografted synoviocytes continued to express IRAP for approximately 5 weeks. Knee joints expressing human IRAP were protected from the leukocytosis that otherwise follows the intraarticular injection of recombinant human interleukin 1 beta. Thus, we report the intraarticular expression and activity of a potentially therapeutic protein by gene-transfer technology; these experiments demonstrate the feasibility of treating arthritis and other joint disorders with gene therapy. Images Fig. 1 Fig. 2 PMID:8248169

  18. Active quenching and gating circuit of the photon counting detector for laser time transfer with improved timing resolution and stability

    NASA Astrophysics Data System (ADS)

    Prochazka, Ivan; Blazej, Josef; Kodet, Jan; Michalek, Vojtech

    2015-05-01

    We are presenting the results of research and development of a new active quenching and gating electronics for Single Photon Avalanche Detector (SPAD). The goal of the work was to develop a new SPAD detector package for Laser Time Transfer ground to space with improved timing resolution and stability. The first version of a SPAD detector is operational on board of GNSS navigation satellites. They are based on 25 μm diameter K14 series SPAD chips. They do provide timing resolution of typically 125 ps and stability of the order of 10 ps. The new control electronics provides timing resolution of 25 ps and timing stability and drifts of the order of one picosecond. The device is constructed on a basis of electronics components for which the space qualified equivalents are commercially available. The device construction, tests and results will be presented in detail.

  19. Horizontal Transfer of Tetracycline Resistance Genes in the Subsurface of a Poultry Farm

    NASA Astrophysics Data System (ADS)

    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.

  20. Ocular gene transfer in the spotlight: implications of newspaper content for clinical communications

    PubMed Central

    2014-01-01

    Background 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. Methods 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. Results 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

  1. Murine somatic cell nuclear transfer using reprogrammed donor cells expressing male germ cell-specific genes.

    PubMed

    Kang, Hoin; Park, Jong Im; Roh, Sangho

    2016-01-01

    In vivo-matured mouse oocytes were enucleated, and a single murine embryonic fibroblast (control or reprogrammed by introducing extracts from murine testis tissue, which showed expression of male germ cell-specific genes) was injected into the cytoplasm of the oocytes. The rate of blastocyst development and expression levels of Oct-4, Eomes and Cdx-2 were not significantly different in both experimental groups. However, the expression levels of Nanog, Sox9 and Glut-1 were significantly increased when reprogrammed cells were used as donor nuclei. Increased expression of Nanog can be supportive of complete reprogramming of somatic cell nuclear transfer murine embryos. The present study suggested that donor cells expressing male germ cell-specific genes can be reconstructed and can develop into embryos with normal high expression of developmentally essential genes. PMID:26369430

  2. Direct generation of oxygen-stabilized radicals by H• transfer from transition metal hydrides.

    PubMed

    Kuo, Jonathan L; Hartung, John; Han, Arthur; Norton, Jack R

    2015-01-28

    Transition-metal hydrides generate α-alkoxy radicals by H• transfer to enol ethers. We have measured the rate constant for transfer from CpCr(CO)3H to n-butyl vinyl ether and have examined the chemistry of radicals generated by such transfers. Radicals from appropriate substrates undergo 5-exo cyclization, with higher diastereoselectivity than the analogous all-carbon radicals. From such radicals it is straightforward to make substituted tetrahydrofurans. PMID:25569214

  3. Evaluation of tetrafunctional block copolymers as synthetic vectors for lung gene transfer.

    PubMed

    Richard-Fiardo, Peggy; Hervouet, Catherine; Marsault, Robert; Franken, Philippe R; Cambien, Béatrice; Guglielmi, Julien; Warnez-Soulie, Julie; Darcourt, Jacques; Pourcher, Thierry; Colombani, Thibault; Haudebourg, Thomas; Peuziat, Pauline; Pitard, Bruno; Vassaux, Georges

    2015-03-01

    In the present study, we evaluated, in mice, the efficacy of the tetrafunctional block copolymer 704 as a nonviral gene delivery vector to the lungs. SPECT/CT molecular imaging of gene expression, biochemical assays, and immunohistochemistry were used. Our dataset shows that the formulation 704 resulted in higher levels of reporter gene expression than the GL67A formulation currently being used in a clinical trial in cystic fibrosis patients. The inflammatory response associated with this gene transfer was lower than that induced by the GL67A formulation, and the 704 formulation was amenable to repeated administrations. The cell types transfected by the 704 formulation were type I and type II pneumocytes, and transgene expression could not be detected in macrophages. These results emphasize the relevance of the 704 formulation as a nonviral gene delivery vector for lung gene therapy. Further studies will be required to validate this vector in larger animals, in which the lungs are more similar to human lungs. PMID:25662490

  4. Contribution of Multiple Inter-Kingdom Horizontal Gene Transfers to Evolution and Adaptation of Amphibian-Killing Chytrid, Batrachochytrium dendrobatidis

    PubMed Central

    Sun, Baofa; Li, Tong; Xiao, Jinhua; Liu, Li; Zhang, Peng; Murphy, Robert W.; He, Shunmin; Huang, Dawei

    2016-01-01

    Amphibian populations are experiencing catastrophic declines driven by the fungal pathogen Batrachochytrium dendrobatidis (Bd). Although horizontal gene transfer (HGT) facilitates the evolution and adaptation in many fungi by conferring novel function genes to the recipient fungi, inter-kingdom HGT in Bd remains largely unexplored. In this study, our investigation detects 19 bacterial genes transferred to Bd, including metallo-beta-lactamase and arsenate reductase that play important roles in the resistance to antibiotics and arsenates. Moreover, three probable HGT gene families in Bd are from plants and one gene family coding the ankyrin repeat-containing protein appears to come from oomycetes. The observed multi-copy gene families associated with HGT are probably due to the independent transfer events or gene duplications. Five HGT genes with extracellular locations may relate to infection, and some other genes may participate in a variety of metabolic pathways, and in doing so add important metabolic traits to the recipient. The evolutionary analysis indicates that all the transferred genes evolved under purifying selection, suggesting that their functions in Bd are similar to those of the donors. Collectively, our results indicate that HGT from diverse donors may be an important evolutionary driver of Bd, and improve its adaptations for infecting and colonizing host amphibians.

  5. Mutation and gene transfer of neutral amino acid transport System L genes in mammalian cells

    SciTech Connect

    El-Gewely, M.R.; Collarini, E.J.; Campbell, G.S.; Oxender, D.L.

    1987-05-01

    The authors are attempting to clone the genes coding for amino acid transport System L. Chinese hamster ovary (CHO) cell mutants that are temperature sensitive in their leucyl-tRNA synthetase show temperature-dependent regulation of System L. Temperature resistant mutants isolated from these cells have constitutively derepressed System L activity. Somatic cell fusion studies using these mutants have suggested that a trans-acting element controls regulation of System L. Mutants with reduced transport activity were isolated by a TH-suicide selection. The growth of these mutant cells is limited by the transport defect. CHO mutants were transformed with a human cosmid library, followed by selection at high temperatures and low leucine concentrations. Some transformants have increased levels of System L activity, suggesting that human genes coding for leucine transport have been incorporated into the CHO genome. Human sequences were rescued by a lambda in vitro packaging system. These sequences hybridize to vector and total human DNA. Experiments are being done to confirm that these sequences indeed code for transport System L. They are also attempting to label membrane components of amino acid transporters by group-specific modifying reagents.

  6. Multiplexed analysis of genes using nucleic acid-stabilized silver-nanocluster quantum dots.

    PubMed

    Enkin, Natalie; Wang, Fuan; Sharon, Etery; Albada, H Bauke; Willner, Itamar

    2014-11-25

    Luminescent nucleic acid-stabilized Ag nanoclusters (Ag NCs) are applied for the optical detection of DNA and for the multiplexed analysis of genes. Two different sensing modules including Ag NCs as luminescence labels are described. One sensing module involves the assembly of a three-component sensing module composed of a nucleic acid-stabilized Ag NC and a quencher-modified nucleic acid hybridized with a nucleic acid scaffold that is complementary to the target DNA. The luminescence of the Ag NCs is quenched in the sensing module nanostructure. The strand displacement of the scaffold by the target DNA separates the nucleic acid-functionalized Ag NCs, leading to the turned-on luminescence of the NCs and to the optical readout of the sensing process. By implementing two different-sized Ag NC-modified sensing modules, the parallel multiplexed analysis of two genes (the Werner Syndrome gene and the HIV, human immunodeficiency, gene), using 615 and 560 nm luminescent Ag NCs, is demonstrated. The second sensing module includes the nucleic acid functionalized Ag NCs and the quencher-modified nucleic acid hybridized with a hairpin DNA scaffold. The luminescence of the Ag NCs is quenched in the sensing module. Opening of the hairpin by the target DNA triggers the luminescence of the Ag NCs, due to the spatial separation of the Ag NCs/quencher units. The system is applied for the optical detection of the BRAC1 gene. In addition, by implementing two-sized Ag NCs, the multiplexed analysis of two genes by the hairpin sensing module approach is demonstrated. PMID:25327411

  7. The influence of horizontal gene transfer on the mean fitness of unicellular populations in static environments.

    PubMed

    Raz, Yoav; Tannenbaum, Emmanuel

    2010-05-01

    Horizontal gene transfer (HGT) is believed to be a major source of genetic variation, particularly for prokaryotes. It is believed that horizontal gene transfer plays a major role in shaping bacterial genomes and is also believed to be responsible for the relatively rapid dissemination and acquisition of new, adaptive traits across bacterial strains. Despite the importance of horizontal gene transfer as a major source of genetic variation, the bulk of research on theoretical evolutionary dynamics and population genetics has focused on point mutations (sometimes coupled with gene duplication events) as the main engine of genomic change. Here, we seek to specifically model HGT processes in bacterial cells, by developing a mathematical model describing the influence that conjugation-mediated HGT has on the mutation-selection balance in an asexually reproducing population of unicellular, prokaryotic organisms. It is assumed that mutation-selection balance is reached in the presence of a fixed background concentration of antibiotic, to which the population must become resistant to survive. We find that HGT has a nontrivial effect on the mean fitness of the population. However, one of the central results that emerge from our analysis is that, at mutation-selection balance, conjugation-mediated HGT has a slightly deleterious effect on the mean fitness of a population. Therefore, we conclude that HGT does not confer a selection advantage in static environments. Rather, its advantage must lie in its ability to promote faster adaptation in dynamic environments, an interpretation that is consistent with the observation that HGT can be promoted by environmental stresses on a population. PMID:20194966

  8. Identification of Valid Housekeeping Genes for Real-Time Quantitative PCR Analysis of Collapsed Lung Tissues of Neonatal Somatic Cell Nuclear Transfer-Derived Cattle.

    PubMed

    Liu, Yan; Zhang, Yunhai; Jiang, Qiuling; Rao, Man; Sheng, Zheya; Zhang, Yu; Du, Weihua; Hao, Haisheng; Zhao, Xueming; Xu, Zhe; Liu, Jianning; Zhu, Huabin

    2015-10-01

    Cloned calves produced by somatic cell nuclear transfer frequently suffer alveolar collapse as newborns. To study the underlying pathophysiological mechanisms responsible for this phenomenon, the expression profiles of numerous genes involved in lung development need to be investigated. Quantitative real-time PCR is commonly adopted in gene expression analysis. However, selection of an appropriate reference gene for normalization is critical for obtaining reliable and accurate results. Seven housekeeping genes-β-glucuronidase (GUSB), phosphoglycerate kinase 1 (PGK1), β-2-microglobolin (B2M), peptidylprolyl isomerase A (PPIA), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), TATA-box binding protein (TBP), and 5.8S ribosomal RNA (5.8S rRNA)-were selected and evaluated as candidates. Their gene expression levels in the collapsed lungs of deceased neonate cloned calves and normal lung derived from normal calves were assessed. The ranking of gene expression stability was estimated by the geNorm, NormFinder, and BestKeeper programs. 5.8S rRNA and PPIA were determined to be the most stable reference genes by geNorm and BestKeeper, whereas the combination of GAPDH and TBP was suggested as reference genes by NormFinder. Taking these results into account, we conclude that 5.8S rRNA and PPIA could be the most reliable reference genes for studying the genes involved in alveolar collapse. Moreover, 5.8S rRNA could be represented as a uniform reference gene in similar cases. PMID:26393896

  9. Genome-Wide Molecular Clock and Horizontal Gene Transfer in Bacterial Evolution

    PubMed Central

    Novichkov, Pavel S.; Omelchenko, Marina V.; Gelfand, Mikhail S.; Mironov, Andrei A.; Wolf, Yuri I.; Koonin, Eugene V.

    2004-01-01

    We describe a simple theoretical framework for identifying orthologous sets of genes that deviate from a clock-like model of evolution. The approach used is based on comparing the evolutionary distances within a set of orthologs to a standard intergenomic distance, which was defined as the median of the distribution of the distances between all one-to-one orthologs. Under the clock-like model, the points on a plot of intergenic distances versus intergenomic distances are expected to fit a straight line. A statistical technique to identify significant deviations from the clock-like behavior is described. For several hundred analyzed orthologous sets representing three well-defined bacterial lineages, the α-Proteobacteria, the γ-Proteobacteria, and the Bacillus-Clostridium group, the clock-like null hypothesis could not be rejected for ∼70% of the sets, whereas the rest showed substantial anomalies. Subsequent detailed phylogenetic analysis of the genes with the strongest deviations indicated that over one-half of these genes probably underwent a distinct form of horizontal gene transfer, xenologous gene displacement, in which a gene is displaced by an ortholog from a different lineage. The remaining deviations from the clock-like model could be explained by lineage-specific acceleration of evolution. The results indicate that although xenologous gene displacement is a major force in bacterial evolution, a significant majority of orthologous gene sets in three major bacterial lineages evolved in accordance with the clock-like model. The approach described here allows rapid detection of deviations from this mode of evolution on the genome scale. PMID:15375139

  10. Microsporidia: Eukaryotic Intracellular Parasites Shaped by Gene Loss and Horizontal Gene Transfers.

    PubMed

    Corradi, Nicolas

    2015-01-01

    Microsporidia are eukaryotic parasites of many animals that appear to have adapted to an obligate intracellular lifestyle by modifying the morphology and content of their cells. Living inside other cells, they have lost many, or all, metabolic functions, resulting in genomes that are always gene poor and often very small. The minute content of microsporidian genomes led many to assume that these parasites are biochemically static and uninteresting. However, recent studies have demonstrated that these organisms can be surprisingly complex and dynamic. In this review I detail the most significant recent advances in microsporidian genomics and discuss how these have affected our understanding of many biological aspects of these peculiar eukaryotic intracellular pathogens. PMID:26195306

  11. Survival of Antibiotic Resistant Bacteria and Horizontal Gene Transfer Control Antibiotic Resistance Gene Content in Anaerobic Digesters

    PubMed Central

    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

  12. Survival of Antibiotic Resistant Bacteria and Horizontal Gene Transfer Control Antibiotic Resistance Gene Content in Anaerobic Digesters.

    PubMed

    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

  13. Broad-Host Range Vector-Particle: Gene Transfer Particles From Thermal Vents

    NASA Astrophysics Data System (ADS)

    Chiura, H. X.; Nakamura, K.; Fukazawa, Y.; Nakata, D.; Tomaru, A.; Okita, N.; Hoaki, T.

    2002-12-01

    Viruses or virus-like particles (VLPs) are common in aquatic ecosystems, however, VLP-host interactions and its commitments to gene transfer in the environment is yet unclear. We have proposed that at least some of the widely distributed VLPs could be general gene transfer agents among a wide range of microbial host cells, and might function as a universal vector (1-4). To elucidate such a broad host range gene transfer mediated by "VLP", the sampling site was extended to the hyper hydrothermal vent, and boring cores. VLP (v) and cell (b) abundances per ml water samples from drilling holes of Suiyo seamount were: APSK04 (28°34.303'N, 140°38.618'E, 1385 m deep, 21°C, b = 8.26 *E^{6}, v = 6.03 x 10^{6}); APSK07 (28°34.299'N, 140°38.690'E, 1386 m deep, 250.5°C, b = 5.33 \\times 104, v = 2.52 \\times 104); a natural vent near APSK05 (28°34.322'N, 140°38.594'E, 1382 m deep, 304.7°C, b = 3.23 x 10^{4}, v = 1.85 x 10^{4}). A boring core sample was obtained from APSK06 (28°34.313'N, 140°38.617', 1386 m deep), from which a hyper thermophilic Archaean, Thermococcus kodakaraensis was successfully cultivated in sulphur supplemented medium between 70 and 90°C. VLP production was observed from T. kodakaraensis, whose VLP (v) and cell (b) abundances per ml at 480 h culture at 70°C were: b = 3.61 *E^{9}, v = 3.46 *E^{9}. Transduction experiment at multiplicity of infection of ca 0.2 using particles from APSK07 and T. kodakaraensis showed a plate efficiency on recipient Escherichia coli AB1157 by ca 72 % and ca 89 % regardless of UV treatment of the particle. Gene transfer frequency of APSK07 particle was (x 10^{-5} cfu/particle) between 2.4 and 0.92, and that of T. kodakaraensis particle was between x 10^{-4} and x 10^{-5}$ cfu/particle. These findings suggest the non-specific gene transfer by such particles may be a ubiquitous event in the natural environment. Such gene transfer particles may have mediated gene flux among phylogenetically diverse microbial

  14. Gene transfer to the developing mouse inner ear by in vivo electroporation.

    PubMed

    Wang, Lingyan; Jiang, Han; Brigande, John V

    2012-01-01

    The mammalian inner ear has 6 distinct sensory epithelia: 3 cristae in the ampullae of the semicircular canals; maculae in the utricle and saccule; and the organ of Corti in the coiled cochlea. The cristae and maculae contain vestibular hair cells that transduce mechanical stimuli to subserve the special sense of balance, while auditory hair cells in the organ of Corti are the primary transducers for hearing. Cell fate specification in these sensory epithelia and morphogenesis of the semicircular canals and cochlea take place during the second week of gestation in the mouse and are largely completed before birth. Developmental studies of the mouse inner ear are routinely conducted by harvesting transgenic embryos at different embryonic or postnatal stages to gain insight into the molecular basis of cellular and/or morphological phenotypes. We hypothesize that gene transfer to the developing mouse inner ear in utero in the context of gain- and loss-of-function studies represents a complimentary approach to traditional mouse transgenesis for the interrogation of the genetic mechanisms underlying mammalian inner ear development(6). The experimental paradigm to conduct gene misexpression studies in the developing mouse inner ear demonstrated here resolves into three general steps: 1) ventral laparotomy; 2) transuterine microinjection; and 3) in vivo electroporation. Ventral laparotomy is a mouse survival surgical technique that permits externalization of the uterus to gain experimental access to the implanted embryos. Transuterine microinjection is the use of beveled, glass capillary micropipettes to introduce expression plasmid into the lumen of the otic vesicle or otocyst. In vivo electroporation is the application of square wave, direct current pulses to drive expression plasmid into progenitor cells. We previously described this electroporation-based gene transfer technique and included detailed notes on each step of the protocol(11). Mouse experimental

  15. Intergeneric transfer and recombination of the 6-phosphogluconate dehydrogenase gene (gnd) in enteric bacteria.

    PubMed Central

    Nelson, K; Selander, R K

    1994-01-01

    The gnd gene, encoding 6-phosphogluconate dehydrogenase (EC 1.1.1.44), was sequenced in 87 strains of 15 species assigned to five nominal genera of the Enterobacteriaceae, including 36 isolates of Salmonella enterica and 32 strains of Escherichia coli. In S. enterica, the effective (realized) rate of recombination of horizontally transferred gnd sequences is only moderately higher than the rates for other chromosomal housekeeping genes. In contrast, recombination at gnd has occurred with such high frequency in Escherichia coli that the indicated evolutionary relationships among strains are not congruent with those estimated by sequence analysis of other genes and by multilocus enzyme electrophoresis. E. coli and S. enterica apparently have not exchanged gnd sequences, but those of several strains of E. coli have been imported from species of Citrobacter and Klebsiella. The relatively frequent exchange of gnd within and among taxonomic groups of the Enterobacteriaceae, compared with other housekeeping genes, apparently results from its close linkage with genes that are subject to diversifying selection, including those of the rfb region determining the structure of the O antigen polysaccharide. PMID:7937867

  16. No evidence for extensive horizontal gene transfer in the genome of the tardigrade Hypsibius dujardini

    PubMed Central

    Koutsovoulos, Georgios; Laetsch, Dominik R.; Stevens, Lewis; Daub, Jennifer; Conlon, Claire; Maroon, Habib; Thomas, Fran; Aboobaker, Aziz A.

    2016-01-01

    Tardigrades are meiofaunal ecdysozoans that are key to understanding the origins of Arthropoda. Many species of Tardigrada can survive extreme conditions through cryptobiosis. In a recent paper [Boothby TC, et al. (2015) Proc Natl Acad Sci USA 112(52):15976–15981], the authors concluded that the tardigrade Hypsibius dujardini had an unprecedented proportion (17%) of genes originating through functional horizontal gene transfer (fHGT) and speculated that fHGT was likely formative in the evolution of cryptobiosis. We independently sequenced the genome of H. dujardini. As expected from whole-organism DNA sampling, our raw data contained reads from nontarget genomes. Filtering using metagenomics approaches generated a draft H. dujardini genome assembly of 135 Mb with superior assembly metrics to the previously published assembly. Additional microbial contamination likely remains. We found no support for extensive fHGT. Among 23,021 gene predictions we identified 0.2% strong candidates for fHGT from bacteria and 0.2% strong candidates for fHGT from nonmetazoan eukaryotes. Cross-comparison of assemblies showed that the overwhelming majority of HGT candidates in the Boothby et al. genome derived from contaminants. We conclude that fHGT into H. dujardini accounts for at most 1–2% of genes and that the proposal that one-sixth of tardigrade genes originate from functional HGT events is an artifact of undetected contamination. PMID:27035985

  17. Characterization of horizontally transferred β-fructofuranosidase (ScrB) genes in Agrilus planipennis.

    PubMed

    Zhao, C; Doucet, D; Mittapalli, O

    2014-12-01

    The emerald ash borer (Agrilus planipennis) is an important invasive insect pest of Fraxinus spp. that feeds on host tissues containing high levels of sucrose. However, little is known about how it digests sucrose. Here, using larval midgut transcriptome data and preliminary genome sequence efforts, two β-fructofuranosidase-encoding ScrB genes, AplaScrB-1 and AplaScrB-2, were identified, and proved to reside within the A. planipennis genome. Homology and phylogenetic analysis revealed that they were acquired by A. planipennis via horizontal gene transfer (HGT) from bacteria, possibly an event independent from that reported in bark beetles (eg ScrB genes). Microsynteny between A. planipennis DNA scaffold #2042940, which hosts AplaScrB-1, and a region in the Tribolium castaneum chromosome LG4 suggested that A. planipennis gained this gene after the separation of Buprestidae and Tenebrionidae. Although both of the putative AplaScrB proteins have conserved β-fructofuranosidase motifs, only AplaScrB-2 was predicted to be a secretory protein. Expression of AplaScrB-1 seemed constitutive during development and in all tissues examined, whereas AplaScrB-2 showed a peak expression in adults and in the midgut. We propose that acquisition of these genes by A. planipennis from bacteria is adaptive, and specifically AplaScrB-2 is involved in breaking down dietary sucrose to obtain energy for development. PMID:25224649

  18. Ancient horizontal transfer of transaldolase-like protein gene and its role in plant vascular development.

    PubMed

    Yang, Zefeng; Zhou, Yong; Huang, Jinling; Hu, Yunyun; Zhang, Enying; Xie, Zhengwen; Ma, Sijia; Gao, Yun; Song, Song; Xu, Chenwu; Liang, Guohua

    2015-04-01

    A major event in land plant evolution is the origin of vascular tissues, which ensure the long-distance transport of water, nutrients and organic compounds. However, the molecular basis for the origin and evolution of plant vascular tissues remains largely unknown. Here, we investigate the evolution of the land plant TAL-type transaldolase (TAL) gene and its potential function in rice (Oryza sativa) based on phylogenetic analyses and transgenic experiments, respectively. TAL genes are only present in land plants and bacteria. Phylogenetic analyses suggest that land plant TAL genes are derived from Actinobacteria through an ancient horizontal gene transfer (HGT) event. Further evidence reveals that land plant TAL genes have undergone positive selection and gained several introns following its acquisition by the most recent common ancestor of land plants. Transgenic plant experiments show that rice TAL is specifically expressed in vascular tissues and that knockdown of TAL expression leads to changes in both the number and pattern of vascular bundles. Our findings show that the ancient HGT of TAL from bacteria probably plays an important role in plant vascular development and adaptation to land environments. PMID:25420550

  19. No evidence for extensive horizontal gene transfer in the genome of the tardigrade Hypsibius dujardini.

    PubMed

    Koutsovoulos, Georgios; Kumar, Sujai; Laetsch, Dominik R; Stevens, Lewis; Daub, Jennifer; Conlon, Claire; Maroon, Habib; Thomas, Fran; Aboobaker, Aziz A; Blaxter, Mark

    2016-05-01

    Tardigrades are meiofaunal ecdysozoans that are key to understanding the origins of Arthropoda. Many species of Tardigrada can survive extreme conditions through cryptobiosis. In a recent paper [Boothby TC, et al. (2015) Proc Natl Acad Sci USA 112(52):15976-15981], the authors concluded that the tardigrade Hypsibius dujardini had an unprecedented proportion (17%) of genes originating through functional horizontal gene transfer (fHGT) and speculated that fHGT was likely formative in the evolution of cryptobiosis. We independently sequenced the genome of H. dujardini As expected from whole-organism DNA sampling, our raw data contained reads from nontarget genomes. Filtering using metagenomics approaches generated a draft H. dujardini genome assembly of 135 Mb with superior assembly metrics to the previously published assembly. Additional microbial contamination likely remains. We found no support for extensive fHGT. Among 23,021 gene predictions we identified 0.2% strong candidates for fHGT from bacteria and 0.2% strong candidates for fHGT from nonmetazoan eukaryotes. Cross-comparison of assemblies showed that the overwhelming majority of HGT candidates in the Boothby et al. genome derived from contaminants. We conclude that fHGT into H. dujardini accounts for at most 1-2% of genes and that the proposal that one-sixth of tardigrade genes originate from functional HGT events is an artifact of undetected contamination. PMID:27035985

  20. Massive intracellular gene transfer during plastid genome reduction in nongreen Orobanchaceae.

    PubMed

    Cusimano, Natalie; Wicke, Susann

    2016-04-01

    Plastid genomes (plastomes) of nonphotosynthetic plants experience extensive gene losses and an acceleration of molecular evolutionary rates. Here, we inferred the mechanisms and timing of reductive genome evolution under relaxed selection in the broomrape family (Orobanchaceae). We analyzed the plastomes of several parasites with a major focus on the genus Orobanche using genome-descriptive and Bayesian phylogenetic-comparative methods. Besides this, we scanned the parasites' other cellular genomes to trace the fate of all genes that were purged from their plastomes. Our analyses indicate that the first functional gene losses occurred within 10 Myr of the transition to obligate parasitism in Orobanchaceae, and that the physical plastome reduction proceeds by small deletions that accumulate over time. Evolutionary rate shifts coincide with the genomic reduction process in broomrapes, suggesting that the shift of selectional constraints away from photosynthesis to other molecular processes alters the plastid rate equilibrium. Most of the photosynthesis-related genes or fragments of genes lost from the plastomes of broomrapes have survived in their nuclear or mitochondrial genomes as the results of multiple intracellular transfers and subsequent fragmentation. Our findings indicate that nonessential DNA is eliminated much faster in the plastomes of nonphotosynthetic parasites than in their other cellular genomes. PMID:26671255

  1. Site-specific gene transfer into the rat spinal cord by photomechanical waves

    NASA Astrophysics Data System (ADS)

    Ando, Takahiro; Sato, Shunichi; Toyooka, Terushige; Uozumi, Yoichi; Nawashiro, Hiroshi; Ashida, Hiroshi; Obara, Minoru

    2011-10-01

    Nonviral, site-specific gene delivery to deep tissue is required for gene therapy of a spinal cord injury. However, an efficient method satisfying these requirements has not been established. This study demonstrates efficient and targeted gene transfer into the spinal cord by using photomechanical waves (PMWs), which were generated by irradiating a black laser absorbing rubber with 532-nm nanosecond Nd:YAG laser pulses. After a solution of plasmid DNA coding for enhanced green fluorescent protein (EGFP) or luciferase was intraparenchymally injected into the spinal cord, PMWs were applied to the target site. In the PMW application group, we observed significant EGFP gene expression in the white matter and remarkably high luciferase activity only in the spinal cord segment exposed to the PMWs. We also assessed hind limb movements 24 h after the application of PMWs based on the Basso-Beattie-Bresnahan (BBB) score to evaluate the noninvasiveness of this method. Locomotor evaluation showed no significant decrease in BBB score under optimum laser irradiation conditions. These findings demonstrated that exogenous genes can be efficiently and site-selectively delivered into the spinal cord by applying PMWs without significant locomotive damage.

  2. Magnetically Responsive Biodegradable Nanoparticles Enhance Adenoviral Gene Transfer in Cultured Smooth Muscle and Endothelial Cells

    PubMed Central

    Chorny, Michael; Fishbein, Ilia; Alferiev, Ivan; Levy, Robert J.

    2012-01-01

    Replication-defective adenoviral (Ad) vectors have shown promise as a tool for gene delivery-based therapeutic applications. Their clinical use is however limited by therapeutically suboptimal transduction levels in cell types expressing low levels of Coxsackie-Ad receptor (CAR), the primary receptor responsible for the cell entry of the virus, and by systemic adverse reactions. Targeted delivery achievable with Ad complexed with biodegradable magnetically responsive nanoparticles (MNP) may therefore be instrumental for improving both the safety and efficiency of these vectors. Our hypothesis was that magnetically driven delivery of Ad affinity-bound to biodegradable MNP can substantially increase transgene expression in CAR deficient vascular cells in culture. Fluorescently labeled MNP were formulated from polylactide with inclusion of iron oxide and surface-modified with the D1 domain of CAR as an affinity linker. MNP cellular uptake and GFP reporter transgene expression were assayed fluorimetrically in cultured endothelial and smooth muscle cells using λex/λem of 540 nm/575 nm and 485 nm/535 nm, respectively. Stable vector-specific association of Ad with MNP resulted in formation of MNP–Ad complexes displaying rapid cell binding kinetics following a brief exposure to a high gradient magnetic field with resultant gene transfer levels significantly increased compared to free vector or nonmagnetic control treatment. Multiple regression analysis suggested a mechanism of MNP–Ad mediated transduction distinct from that of free Ad, and confirmed the major contribution of the complexes to the gene transfer under magnetic conditions. The magnetically enhanced transduction was achieved without compromising the cell viability or growth kinetics. The enhancement of adenoviral gene delivery by affinity complexation with biodegradable MNP represents a promising approach with a potential to extend the applicability of the viral gene therapeutic strategies. PMID:19496618

  3. Root parasitic plant Orobanche aegyptiaca and shoot parasitic plant Cuscuta australis obtained Brassicaceae-specific strictosidine synthase-like genes by horizontal gene transfer

    PubMed Central

    2014-01-01

    Background 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. Results 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. Conclusions 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

  4. AAV9-mediated gene transfer of desmin ameliorates cardiomyopathy in desmin-deficient mice.

    PubMed

    Heckmann, M B; Bauer, R; Jungmann, A; Winter, L; Rapti, K; Strucksberg, K-H; Clemen, C S; Li, Z; Schröder, R; Katus, H A; Müller, O J

    2016-08-01

    Mutations of the human desmin (DES) gene cause autosomal dominant and recessive myopathies affecting skeletal and cardiac muscle tissue. Desmin knockout mice (DES-KO), which develop progressive myopathy and cardiomyopathy, mirror rare human recessive desminopathies in which mutations on both DES alleles lead to a complete ablation of desmin protein expression. Here, we investigated whether an adeno-associated virus-mediated gene transfer of wild-type desmin cDNA (AAV-DES) attenuates cardiomyopathy in these mice. Our approach leads to a partial reconstitution of desmin protein expression and the de novo formation of the extrasarcomeric desmin-syncoilin network in cardiomyocytes of treated animals. This finding was accompanied by reduced fibrosis and heart weights and improved systolic left-ventricular function when compared with control vector-treated DES-KO mice. Since the re-expression of desmin protein in cardiomyocytes of DES-KO mice restores the extrasarcomeric desmin-syncoilin cytoskeleton, attenuates the degree of cardiac hypertrophy and fibrosis, and improves contractile function, AAV-mediated desmin gene transfer may be a novel and promising therapeutic approach for patients with cardiomyopathy due to the complete lack of desmin protein expression. PMID:27101257

  5. Targeted adenovirus gene transfer to endothelial and smooth muscle cells by using bispecific antibodies.

    PubMed Central

    Wickham, T J; Segal, D M; Roelvink, P W; Carrion, M E; Lizonova, A; Lee, G M; Kovesdi, I

    1996-01-01

    A major hurdle to adenovirus (Ad)-mediated gene transfer is that the target issue lacks sufficient levels of receptors to mediate vector attachment via its fiber coat protein. Endothelial and smooth muscle cells are primary targets in gene therapy approaches to prevent restenosis following angioplasty or to promote or inhibit angiogenesis. However, Ad poorly binds and transduces these cells because of their low or undetectable levels of functional Ad fiber receptor. The Ad-binding deficiency of these cells was overcome by targeting Ad binding to alpha v integrin receptors that are sufficiently expressed by these cells. In order to target alpha v integrins, a bispecific antibody (bsAb) that comprised a monoclonal Ab to the FLAG peptide epitope, DYKDDDDK, and a monoclonal Ab to alpha v integrins was constructed. In conjunction with the bsAb, a new vector, AdFLAG, which incorporated the FLAG peptide epitope into its penton base protein was constructed. Complexing AdFLAG with the bsAb increased the beta-glucuronidase transduction of human venule endothelial cells and human intestinal smooth muscle cells by seven- to ninefold compared with transduction by AdFLAG alone. The increased transduction efficiency was shown to occur through the specific interaction of the complex with alpha v integrins. These results demonstrate that bsAbs can be successfully used to target Ad to a specific cellular receptor and thereby increase the efficiency of gene transfer. PMID:8794324

  6. Recent Origin of the Methacrylate Redox System in Geobacter sulfurreducens AM-1 through Horizontal Gene Transfer

    PubMed Central

    Arkhipova, Oksana V.; Meer, Margarita V.; Mikoulinskaia, Galina V.; Zakharova, Marina V.; Galushko, Alexander S.; Kondrashov, Fyodor A.

    2015-01-01

    The origin and evolution of novel biochemical functions remains one of the key questions in molecular evolution. We study recently emerged methacrylate reductase function that is thought to have emerged in the last century and reported in Geobacter sulfurreducens strain AM-1. We report the sequence and study the evolution of the operon coding for the flavin-containing methacrylate reductase (Mrd) and tetraheme cytochrome с (Mcc) in the genome of G. sulfurreducens AM-1. Different types of signal peptides in functionally interlinked proteins Mrd and Mcc suggest a possible complex mechanism of biogenesis for chromoproteids of the methacrylate redox system. The homologs of the Mrd and Mcc sequence found in δ-Proteobacteria and Deferribacteres are also organized into an operon and their phylogenetic distribution suggested that these two genes tend to be horizontally transferred together. Specifically, the mrd and mcc genes from G. sulfurreducens AM-1 are not monophyletic with any of the homologs found in other Geobacter genomes. The acquisition of methacrylate reductase function by G. sulfurreducens AM-1 appears linked to a horizontal gene transfer event. However, the new function of the products of mrd and mcc may have evolved either prior or subsequent to their acquisition by G. sulfurreducens AM-1. PMID:25962149

  7. A Versatile Vector for Gene and Oligonucleotide Transfer into Cells in Culture and in vivo: Polyethylenimine

    NASA Astrophysics Data System (ADS)

    Boussif, Otmane; Lezoualc'h, Frank; Zanta, Maria Antonietta; Djavaheri Mergny, Mojgan; Scherman, Daniel; Demeneix, Barbara; Behr, Jean-Paul

    1995-08-01

    Several polycations possessing substantial buffering capacity below