Control of Biohazards: A High Performance Energetic Polycyclized Iodine-Containing Biocide.

Biohazards and chemical hazards as well as radioactive hazards have always been a threat to human health. The search for solutions to these problems is an ongoing worldwide effort. In order to control biohazards by chemical methods, a synthetically useful fused tricyclic iodine-rich compound, 2,6-diiodo-3,5-dinitro-4,9-dihydrodipyrazolo [1,5- a:5',1'- d][1,3,5]triazine (5), with good detonation performance was synthesized, characterized, and its properties determined. This compound which acts as an agent defeat weapon has been shown to destroy certain microorganisms effectively by releasing iodine after undergoing decomposition or combustion. The small iodine residues remaining will not be deleterious to human life after 1 month.

Foliar potassium nitrate application improves the tolerance of Citrus macrophylla L. seedlings to drought conditions.

Scarcity of water is a severe limitation in citrus tree productivity. There are few studies that consider how to manage nitrogen (N) nutrition in crops suffering water deficit. A pot experiment under controlled-environment chambers was conducted to explore if additional N supply via foliar application could improve the drought tolerance of Citrus macrophylla L. seedlings under dry conditions. Two-month-old seedlings were subjected to a completely random design with two water treatments (drought stress and 100% water/field capacity). Plants under drought stress (DS) received three different N supplies via foliar application (DS: 0, DS + NH4NO3: 2% NH4NO3, DS + KNO3: 2% KNO3). KNO3-spraying increased leaf and stem DW as compared with DS + NH4NO3 and DS treatments. Leaf water potential (Ψw) was decreased by drought stress in all the treatments. However, in plants from DS + NH4NO and DS + KNO3, this was due to a decrease in the leaf osmotic potential, whereas the decrease in those from the DS treatment was due to a decrease in the leaf turgor potential. These responses were correlated with the leaf proline and K concentrations. DS + KNO3-treated plants had a higher leaf proline and K concentration than DS-treated plants. In terms of leaf gas exchange parameters, it was observed that net assimilation of CO2 [Formula: see text] was decreased by drought stress, but this reduction was much lower in DS + KNO3-treated plants. Thus, when all results are taken into account, it can be concluded that a 2% foliar-KNO3 application can enhance the tolerance of citrus plants to water stress by increasing the osmotic adjustment process.

Transferases and transporters mediate the detoxification and capacity to tolerate trinitrotoluene in Arabidopsis.

The effect of recalcitrant soil and water pollutant 2,4,6-trinitrotoluen (TNT) on gene expression in Arabidopsis thaliana rosettes and roots was studied separately for the first time using microarrays. Seven-day exposure to TNT resulted in 170 up- and 122 down-regulated genes in the rosettes and 61 up- and 51 down-regulated genes in the roots (expression difference > 1.5-fold; p[t test] < 0.05). TNT concentration, 5 µg/ml, was selected according to the dose response analysis and study of TNT uptake from liquid media. Although many TNT induced genes fell into ontology groups annotated as response to biotic and abiotic stresses in rosettes and roots, only a small overlap of TNT effects on transcriptome was observed between rosettes and roots. The rosettes exhibited induction of several genes associated with toxin metabolism, such as UDP-glycosyltransferases and ATP-binding cassette (ABC) family transporters. On the other side, no genes known to be involved in TNT transformation were found to be up-regulated in the roots. The genes coding for enzymes involved in the cell wall modifications were abundantly up-regulated in roots. Microarray data indicated that after a relatively long incubation with TNT (7 days), metabolism of this xenobiotic proceeded mainly in aerial parts, while its translocation into cell walls still took place in the roots. Results obtained by microarray hybridization were validated by quantitative real-time reverse-transcription PCR. Nitrate reductase 1, several glycosyltransferases and ABC transporters, sucrose-proton symporter 2, thioredoxin-dependent peroxidase 2, and gamma-glutamyltransferase are discussed for their potential to enhance detoxification and toleration capability of plants to TNT.

Expression of glutathione S-transferases in poplar trees (Populus trichocarpa) exposed to 2,4,6-trinitrotoluene (TNT).

Twelve Populus genes were identified from Arabidopsis thaliana sequences previously shown to be induced by exposure to 2,4,6-trinitrotoluene (TNT). Using the resources of the Poplar Genome Project and National Center for Biotechnology Information databases, Populus conserved domains were identified and used to design gene specific primers. RNA extracted from root tissues of TNT-exposed hydroponic poplar plants was used to quantify the expression of genes by reverse-transcriptase real-time polymerase chain reaction. Cyclophilin and 18S ribosomal DNA genes were used as internal standards. Exposure to TNT resulted in a significant increase of gene expression of two glutathione S-transferases (GST), peaking at levels of 25.0 +/- 13.1 and 10 +/- 0.7 fold the expression level of non-exposed plants after 24 h for each of the GST genes, respectively. This paper demonstrates the use of functional genomics information from the model plant species, Arabidopsis, to identify genes which may be important in detoxification of TNT in the model phytoremediation species, Populus trichocarpa.

Examination of the mutagenicity of RDX and its N-nitroso metabolites using the Salmonella reverse mutation assay.

The mutagenicity of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and its N-nitroso derivatives hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) were evaluated using the Salmonella tryphimurium reverse mutation assay (Ames assay) with strains TA97a, TA98, TA100, and TA102. Using a preincubation procedure and high S9 activation (9%), RDX was observed to induce weak mutagenesis to strain TA97a with a mutagenicity index (MI) of 1.5-2.0 at a dose range of 32.7-1090microg/plate. MNX induced moderate mutagenesis to strain TA97a with an MI of 1.6-2.8 at a dose range of 21.7-878microg/plate. TNX also induced moderate mutagenesis in strain TA97a with an MI of 2.0-3.5 to TA97a at a dose range of 22.7-1120microg/plate. TNX also caused weak mutagenesis to strain TA100 with S9 activation at the dose of 1200microg/plate. MNX and TNX induced weak to moderate mutagenesis to strain TA102. Strain TA97a was found to be the most sensitive strain among these four strains. No cytotoxicity of RDX, MNX, and TNX was observed at the concentrations used in this study. Doses were verified by HPLC.

Analysis of gene expression in poplar trees (Populus deltoides x nigra, DN34) exposed to the toxic explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX).

Poplar plants (Populus deltoides x nigra, DN34) growing under hydroponic conditions were exposed to 50 mg L(-1) of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) for 24 h. The expression of genes potentially involved in the metabolism of toxic explosives was analyzed by reverse-transcriptase (RT) real-time PCR. Genes under study were selected by reference to corresponding genes that were previously shown to be upregulated in the model plant Arabidopsis thaliana by exposure to 2,4,6-trinitrotoluene (TNT) (Ekman et al., 2003. Plant Physiol., 133, 1397-1406). The target genes investigated include several genes encoding for enzymes known to be involved in the detoxification of xenobiotic pollutants, such as glutathione S-transferases (GSTs), cytochrome P-450s (CYPs), NADPH-dependent reductases, and peroxidases. Starting from A. thaliana TNT-inducible genes, corresponding Populus sequences were retrieved from the JGI Poplar Genome Project database and were used to design gene-specific primers. 18S ribosomal DNA (rDNA) was used as an internal standard and recorded gene expression levels were normalized by reference to nonexposed plants. In three separate experiments, five genes were found to be significantly amplified in leaf tissues by exposure to RDX, including GST (9.7 fold), CYP (1.6 fold), reductases (1.6-1.7 fold), and peroxidase (1.7 fold). In root tissues, only a single GST gene was found to be significantly amplified by exposure to RDX (2.0 fold). These results show, for the first time, that the exposure of poplar plants to RDX results in the induction of several genes that are potentially involved in explosive detoxification.