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At least 703 records · Page 39Linked to original sources
PubMed2003

Enduring toxicity of transgenic Anabaena PCC 7120 expressing mosquito larvicidal genes from Bacillus thuringiensis ssp. israelensis.

Persistence of biological control agents against mosquito larvae was tested under simulated field conditions. Mosquito larvicidal activity of transgenic Anabaena PCC 7120 expressing cry4Aa, cry11Aa and p20 from Bacillus thuringiensis ssp. israelensis was greater than B. thuringiensis ssp. israelensis primary powder (fun 89C06D) or wettable powder (WP) (Bactimos products) when either mixed with silt or exposed to sunlight outdoors. Reduction of Bactimos primary powder toxicity was at least 10-fold higher than Anabaena's after mixing with silt. In outdoors experiments, Bactimos WP remained toxic (over 30% mortality of 3rd instar Aedes aegypti larvae) for 2-4 days only, while transgenic Anabaena's toxicity endured 8-21 days.

Aedes↗
PubMedDate not supplied

The DAL10 gene from Norway spruce (Picea abies) belongs to a potentially gymnosperm-specific subclass of MADS-box genes and is specifically active in seed cones and pollen cones.

Transcription factors encoded by different members of the MADS-box gene family have evolved central roles in the regulation of reproductive organ development in the flowering plants, the angiosperms. Development of the stamens and carpels, the pollen- and seed-bearing organs, involves the B- and C-organ-identity MADS-box genes. B- and C-type gene orthologs with activities specifically in developing pollen- and seed-bearing organs are also present in the distantly related gymnosperms: the conifers and the gnetophytes. We now report on the characterization of DAL10, a novel MADS-box gene from the conifer Norway spruce, which unlike the B- and C-type conifer genes shows no distinct orthology relationship to any angiosperm gene or clade in phylogenetic analyses. Like the B- and C-type genes, it is active specifically in developing pollen cones and seed cones. In situ RNA localization experiments show DAL10 to be expressed in the cone axis, which carry the microsporophylls of the young pollen cone. In contrast, in the seed cone it is expressed both in the cone axis and in the bracts, which subtend the ovuliferous scales. Expression data and the phenotype of transgenic Arabidopsis plants expressing DAL10 suggest that the gene may act upstream to or in concert with the B- and C-type genes in the establishment of reproductive identity of developing cones.

Base Sequence↗
PubMed2002

Towards safer vectors for the field release of recombinant bacteria.

The prospect of the deliberate environmental release of genetically manipulated microorganisms has given rise to a great deal of polemic. Amongst the rational scientific concerns are those concerned with the fate of the released bacteria, the fate of the recombinant genes that they carry, the selective pressures acting upon them in different environmental situations and the long term effects on the environment and human health. All recombinant DNA is carried by vectors (plasmids, transposons or bacteriophage or remnants of these). Thus the way in which recombinant constructions are made may itself lead to potential biosafety concerns, irrespective of the host bacterium and the recombinant DNA fragment of primary interest. The purpose of the present review is to assess progress in improved vector design aimed at eliminating risks due to the way recombinant vectors are constructed. Improved vector constructions include the avoidance of the use, or removal, of antibiotic resistance genes, the use of defective transposons rather than plasmids in order to reduce horizontal transfer and the development of conditionally lethal suicide systems. More recently, new site-specific recombination systems have permitted transposon vectors to be manipulated following strain construction, but before environmental release, so that virtually all recombinant DNA not directly involved in the release experiment is eliminated. Such bacteria are thus pseudo-wild type in that they contain no heterologous DNA other than the genes of interest.

Bacteria↗
PubMedDate not supplied

Effects of temperature on detection of plasmid or chromosomally encoded gfp- and lux-labeled Pseudomonas fluorescens in soil.

Pseudomonas fluorescens is a normal inhabitant of the soil rhizosphere. The use of genetically altered strains of P. fluorescens in bioremediation has led to the need for effective monitoring of such cells released into the environment. In this study, we present data on the persistence in soil of P. fluorescens harboring gfp (green fluorescent protein) or lux (bioluminescence) genes. Comparisons were made between strains marked chromosomally and strains carrying these markers on a plasmid. Overall effects of plasmid carriage on culturability were also examined. Sterile soil microcosms were inoculated with washed cells to a final concentration of ca. 10(6) CFU.g(-1) and placed at 5, 23, and 35-37 degrees C. Samples were taken periodically and examined for culturability and viability, using the substrate responsiveness assay. Our results indicated no significant loss of culturability at 5 and 23 degrees C for a period of over one year. In contrast, cells of P. fluorescens incubated at 35-37 degrees C entered the viable but nonculturable state within 7 days. All cells labeled with gfp retained fluorescence regardless of culturability, suggesting that the green fluorescent protein can be of value in monitoring the presence of cells following their release to the environment. Because fluorescence was maintained regardless of the cells' physiological state, this protein may also be an indicator of cell viability.

Bacteriological Techniques↗
PubMed2006

[Scientific progress and new biological weapons].

The biological weapons are different from conventional weapons, because living germs hold an extraordinary and predictable potential for multiplication, propagation and genetic variation during their dissemination in a susceptible population. Only natural pathogens (1rst generation weapons) have been used in the past (smallpox virus, plague, anthrax, toxins...). However, new threats are emerging, due to the rapid progress of scientific knowledge and its exponential worldwide diffusion. It is possible to synthesize microorganisms from in silico sequences widely diffused on Internet (poliovirus, influenza...), thus resulting in the accessibility of very dangerous virus confined today in high-security laboratories (virus Ebola...). It is possible also to "improve" pathogens by genetic manipulations, becoming more resistant or virulent (2nd generation weapons). Finally, one can now create de novo new pathogens by molecular breeding (DNA shuffling), potentially highly dangerous for naive populations (3rd generation weapons). Making biological weapons does not require too much technological resources and appears accessible to terrorists, due to low cost and easy use. Although the destructive consequences are difficult to predict, the psychological and social damages should be considerable, because of the highly emotional burden in the population associated to the transgression by man of a taboo of life.

Biological Warfare↗
PubMed2006

Activity of quinones from teak (Tectona grandis) on fungal cell wall stress.

Teak ( Tectona grandis L.f., Verbenaceae) sawdust extract inhibited the growth of Aspergillus niger. Centrifugal partition chromatography was used to isolate the active compounds. By (1)H-NMR the active compounds were identified as deoxylapachol and tectoquinone. Two A. niger transgenic strains which show induction of 1,3 -alpha-D-glucan synthase were used as a cell wall damage model. The result showed that deoxylapachol from T. grandis extract induced fungal cell wall stress.

Antifungal Agents↗
PubMed2005

Homoserine and asparagine are host signals that trigger in planta expression of a pathogenesis gene in Nectria haematococca.

Some pathogenesis-related genes are expressed in fungi only when the pathogen is in the host, but the host signals that trigger these gene expressions have not been identified. Virulent Nectria haematococca infects pea plants and requires either pelA, which is induced by pectin, or pelD, which is induced only in planta. However, the host signal(s) that trigger pelD expression was unknown. Here we report the isolation of the host signals and identify homoserine and asparagine, two free amino acids found in uniquely high levels in pea seedlings, as the pelD-inducing signals. N. haematococca has evolved a mechanism to sense the host tissue environment by using the high levels of two free amino acids in this plant, thereby triggering the expression of pelD to assist the pathogenic process.

Asparagine↗
PubMed2006

Dual targeting of a single tRNA(Trp) requires two different tryptophanyl-tRNA synthetases in Trypanosoma brucei.

The mitochondrion of Trypanosoma brucei does not encode any tRNAs. This deficiency is compensated for by the import of a small fraction of nearly all of its cytosolic tRNAs. Most trypanosomal aminoacyl-tRNA synthetases are encoded by single-copy genes, suggesting the use of the same enzyme in the cytosol and mitochondrion. However, the T. brucei genome contains two distinct genes for eukaryotic tryptophanyl-tRNA synthetase (TrpRS). RNA interference analysis established that both TrpRS1 and TrpRS2 are essential for growth and required for cytosolic and mitochondrial tryptophanyl-tRNA formation, respectively. Decoding the mitochondrial tryptophan codon UGA requires mitochondria-specific C-->U RNA editing in the anticodon of the imported tRNA(Trp). In vitro charging assays with recombinant TrpRS enzymes demonstrated that the edited anticodon and the mitochondria-specific thiolation of U33 in the imported tRNA(Trp) act as antideterminants for the cytosolic TrpRS1. The existence of two TrpRS enzymes, therefore, can be explained by the need for a mitochondrial synthetase with extended substrate specificity to achieve aminoacylation of the imported thiolated and edited tRNA(Trp). Thus, the notion that, in an organism, all nuclear-encoded tRNAs assigned to a given amino acid are charged by a single aminoacyl-tRNA synthetase, is not universally valid.

Amino Acid Sequence↗
PubMed2004

Translation of a yeast mitochondrial tRNA synthetase initiated at redundant non-AUG codons.

Although initiation of translation at non-AUG codons occurs occasionally in prokaryotes and higher eukaryotes, it has not been reported in yeast until very recently. Evidence presented here shows that redundant ACG codons are recognized as alternative translation start sites for ALA1, the only gene in Saccharomyces cerevisiae coding for alanyl-tRNA synthetase. ALA1 is shown to be a bifunctional gene that provides both cytoplasmic and mitochondrial activities. Unlike most bifunctional genes that contain alternative in-frame AUG initiators, there is only one AUG codon, designated AUG1, close to the 5'-end of the ALA1 open reading frame. Transcriptional mapping identified three overlapping transcripts, with 5'-ends at positions 54, 105, and 117 nucleotides upstream of AUG1, respectively. Site-specific mutagenesis demonstrated that the cytoplasmic and mitochondrial functions of ALA1 are provided by two protein isoforms with distinct amino termini; that is, a short cytoplasmic form initiated at AUG1 and a longer mitochondrial isoform initiated at two upstream in-frame ACG codons, i.e. ACG(-25) and ACG(-24). These two ACG codons function redundantly in initiation of translation. Either codon can function in the absence of the other. The short transcript appears to serve as the template for the cytoplasmic form, whereas the longer transcripts are likely to code for both isoforms via alternative initiation. Because yeast ribosomes in general cannot efficiently recognize a non-AUG initiator, this unique feature of redundancy of non-AUG initiators in a single mRNA may in itself represent a novel paradigm for translation initiation from poor initiators.

Amino Acyl-tRNA Synthetases↗
PubMed2005

Overexpression of glutamate-cysteine ligase extends life span in Drosophila melanogaster.

The hypothesis that overexpression of glutamate-cysteine ligase (GCL), which catalyzes the rate-limiting reaction in de novo glutathione biosynthesis, could extend life span was tested in the fruit fly, Drosophila melanogaster. The GAL4-UAS binary transgenic system was used to generate flies overexpressing either the catalytic (GCLc) or modulatory (GCLm) subunit of this enzyme, in a global or neuronally targeted pattern. The GCL protein content of the central nervous system was elevated dramatically in the presence of either global or neuronal drivers. GCL activity was increased in the whole body or in heads, respectively, of GCLc transgenic flies containing global or neuronal drivers. The glutathione content of fly homogenates was increased by overexpression of GCLc or GCLm, particularly in flies overexpressing either subunit globally, or in the heads of GCLc flies possessing neuronal drivers. Neuronal overexpression of GCLc in a long-lived background extended mean and maximum life spans up to 50%, without affecting the rate of oxygen consumption by the flies. In contrast, global overexpression of GCLm extended the mean life span only up to 24%. These results demonstrate that enhancement of the glutathione biosynthetic capability, particularly in neuronal tissues, can extend the life span of flies, and thus support the oxidative stress hypothesis of aging.

Animals↗
PubMed2006

Identification of proinflammatory flagellin proteins in supernatants of Vibrio cholerae O1 by proteomics analysis.

The genome of Vibrio cholerae contains five flagellin genes that encode proteins (FlaA-E) of 39-41 kDa with 61-82% identity among them. Although the existing live oral attenuated vaccine strains against cholera are protective in humans, there is an intrinsic residual cytotoxic and inflammatory component associated with these candidate vaccine strains. Bacterial flagellins are known to be potent inducers of proinflammatory molecules via activation of Toll-like receptor 5. Here we found that purified flagella from wild type V. cholerae 395 induced significant release of interleukin (IL)-8 from cultured HT-29 human colonic epithelial cells. Furthermore we found that filtered supernatants of KKV90, a DeltaflaA isogenic strain unable to produce flagella, were still able to activate production of IL-8 albeit to significantly lower levels than the wild type, suggesting that other activators of proinflammatory molecules were still present in these supernatants. A comparative proteomics analysis of secreted proteins of V. cholerae 395 and KKV90 identified additional proteins with potential to induce IL-8 release in HT-29 cells. Secreted proteins in the range of 30-45 kDa identified by two-dimensional electrophoresis and mass spectrometry revealed the presence of two additional flagellins, FlaC and FlaD, that appeared to be secreted 3- and 6-fold more, respectively, in the mutant compared with the wild type. Double isogenic mutants flaAC and flaAD were unable to trigger IL-8 release from HT-29 cells. In sum, we have shown that purified flagella and secreted flagellin proteins (FlaC and FlaD) are inducers of IL-8 release from epithelial cells via Toll-like receptor 5. This observation may explain, in part, the observed reactogenicity of cholera vaccine strains in humans.

Culture Media, Conditioned↗
PubMed2002

Persistence and functional impact of a microbial inoculant on native microbial community structure, nutrient digestion and fermentation characteristics in a rumen model.

Small sub-unit (SSU) rRNA-targeted oligonucleotide probes were used to monitor the persistence of a genetically engineered bacterium inoculated in model rumens. Eight dual flow continuous culture fermenters were operated with either standard artificial saliva buffer or buffer with chondroitin sulfate (0.5 g/l) added. After 168 h of operation, fermenters were inoculated with Bacteroides thetaiotaomicron BTX (BTX), at approximately 1% of total bacteria. B. thetaiotaomicron was quantified using a species-specific probe and shown to persist in fermenters 144 h after inoculation (relative abundance 0.48% and 1.42% of total SSU rRNA with standard and chondroitin sulfate buffers, respectively). No B. thetaiotaomicron SSU rRNA was detected in fermenter samples prior to inoculation with strain BTX. Relative abundances of Bacteria, Eucarya and Archaea were not affected by either inoculation or buffer type. Fiber digestion, in particular the hemicellulose fraction, increased after strain BTX addition. Chondroitin sulfate addition to the buffer increased bacterial nitrogen flow in fermenters, but did not alter fiber digestion. Neither inoculum nor buffer type altered total short chain fatty acid (VFA) concentrations but proportions of individual VFA differed. In model rumens, B. thetaiotaomicron BTX increased fiber digestion when added to mixed ruminal microbes, independent of chondroitin sulfate addition; but further study is needed to determine effects on other fiber-digesting bacteria.

Animals↗
PubMed2005

Risk perception and communication: lessons for the food and food packaging industry.

Health risks are front-page news. Be it bovine spongiform encephalitis (BSE), surface ozone, or radiation from transmitter stations or mobile phones, the popular press puts out a constant stream of risk warnings and sensational reports about potential health threats. This paper examines how the general public perceives and assesses such information when it comes to food and food packaging risks. In the first part, the basic components of food risks are discussed and then compared with the perceptions of these risks. The main emphasis is on the risks from food packaging. The term 'perception' as used in cognitive psychology applies to the mental processes through which a person takes in, deals with and assesses information from the environment (physical and communicative) via the senses. The last part of the paper deals with the consequences of risk assessment and risk perception for risk management and risk communication.

Attitude to Health↗