Interference of three weed extracts on uptake of nutrient in three different varieties of paddy through radio tracer techniques

Interference of three dominant weed extracts viz., Ageratum conyzoides L., Melilotus indica All. and Parthenium hysterophorus L. were examined on seed germination, seedling growth, and nutrient uptake (32P and 65Zn) in three different varieties (PD-10, PD-12 and PB) of paddy (Oryza sativa L.). Among the three different varieties irrespective of weed extracts, PD-10 and PD-12 were resistant and PB was susceptible in terms of seed germination, radicle length and plumule dry weight; and PD-12 and PB were resistant and susceptible, respectively, in terms of plumule length and total seedling dry weight. A. conyzoides caused maximum reduction in seed germination and M. indica in seedling growth in different varieties of paddy. The weed extracts interfered in uptake of both 32P and 65Zn and there was a gradual decrease in uptake of both nutrients with increasing concentration of extracts in both root and shoot. The uptake of 32P and 65Zn was more inhibitory with the extracts of A. conyzoides and M. indica, respectively in different varieties. The inhibition in seed germination, seedling growth and nutrient uptake may be due to the presence of phenolics and other secondary metabolities. The phenolics such as gallic, vanillic, protocatechuic and p-hydroxybenzoic acids were identified from these weed extracts.     

湖南耐寒桉树优良单株组培研究

本研究以湖南省林业技术推广总站在湖南选育的17个耐寒桉树优良单株为试验材料,进行组培繁殖,有14个优良单株成功地诱导出了愈伤组织或芽。结果表明,以一年生扦插苗的当年生嫩枝作为外植体来源,污染率低且愈伤组织和芽的诱导率高;0.25％氯化汞消毒15—20分钟,可将污染率控制在70％以下,且对外植体的损害最小;按树最佳的诱导培养基为:1/2MS+BA_(1.0)+IBA_(0.25),最佳的继代培基为:MS+BA_(1.0)+KT_(1.0)+VB2_(10)。     

酸阻滞技术的研究与应用

本文提出酸阻滞法从废液中分离，回收重金属和酸的新技术工艺，从十多种国产树脂中成功地筛选出两种可作为酸阻滞剂，有较好的分离效果。但洗脱时酸脱尾严重，当选择穿透比在０．６左右时，可以解决酸脱尾现象，使脱尾酸损失由３０％降到７％，而酸的回收率由６０％提高到９０％，采用该工艺对几种废液进行处理，重金属回收液中酸去除率大于９５％，而回用酸中金属去除率大于７０％，该工艺既可回收重金属，同时也可回收酸。     

Acid azo dye degradation by free and immobilized horseradish peroxidase (HRP) catalyzed process

Acid azo (Acid Black 10 BX) dye removal by plant based peroxidase catalyzed reaction was investigated. Horseradish peroxidase (HRP) was extracted from horseradish roots and its performance was evaluated in both free and immobilized form. HRP showed its ability to degrade the dye in aqueous phase. Studies are further carried out to understand the process parameters such as aqueous phase pH, H2O2 dose, dye and enzyme concentrations during enzyme-mediated dye degradation process. Experimental data revealed that dye (substrate) concentration, aqueous phase pH, enzyme and H2O2 dose play a significant role on the overall enzyme-mediated reaction. Acrylamide gel immobilized HRP showed effective performance compared to free HRP and alginate entrapped HRP. Alginate entrapped HRP showed inferior performance over the free enzyme due to the consequence of non-availability of the enzyme to the dye molecule due to polymeric immobilization. Standard plating studies performed with Pseudomonas putida showed enhanced degradation of HRP catalyzed dye compared to control.     

Antioxidant effect of Sargassum polycystum (Phaeophyceae) against acetaminophen induced changes in hepatic mitochondrial enzymes during toxic hepatitis

The present study was aimed to examine the protective effects of Sargassum polycystum (Phaeophyceae) alcoholic extract on changes in liver mitochondrial enzymes against acetaminophen induced toxic hepatitis in experimental rats. The levels of protein, lipid peroxide, glutathione (GSH) in mitochondrial fraction, superoxide dismutase (SOD) and catalase (CAT) were also determined. The activities of tricarboxylic acid enzymes such as isocitrate dehydrogenase (ICD), alpha-ketoglutarate dehydrogenase (alpha-KGD), succinate dehydrogenase (SD), malate dehydrogenase (MD), NADH dehydrogenase, and cytochrome-c-oxidase were determined in mitochondrial fraction. The rats intoxicated with acetaminophen showed significant elevation in the levels of lipid peroxides with decreased levels of protein, GSH, SOD, CAT and impaired tricarboxylic acid cycle enzyme activities. The prior oral administration of S. polycystum alcoholic extract showed significant diminution in the severity of toxic hepatitis in acetaminophen-induced rats by maintaining the activities of tricarboxylic acid enzymes with concomitant improvement in the hepatic mitochondrial antiperoxidative status when compared with intoxicated animals. The results obtained in the present study indicate that the protective effects of S. polycystum extract may be due to the presence of some active compounds that are inhibitory against the free radicals generated during lipid peroxidation in acetaminophen induced toxic hepatitis.     

Oxygenated fuel induced cosolvent effects on the dissolution of polynuclear aromatic hydrocarbons from contaminated soil

The cosolvent-induced dissolution of polynuclear aromatic hydrocarbons (PAHs) from contaminated soil caused by oxygenated fuel spills was studied. Oxygenated fuel induces a solvent flushing effect on the contaminated soil due to the high content of oxygenated compounds (i.e., methanol, ethanol, and methyl tert butyl ether (MTBE)). The miscible displacement techniques were applied to evaluate the increased potential for secondary contamination in an impacted site. Significant solubility enhancement of the 18 PAHs monitored during fuel spill simulation and cosolvent flushing is clearly evident when compared to normal water dissolution. The breakthrough concentration profile for each PAH constituent was integrated over the cumulative effluent volume (i.e., the zeroth moment) to determine the total PAH mass removed during the experiment. The removal efficiency of PAHs ranges from 46.6% to 99.9% in three oxygenated fuels (i.e., M85, E85, and oxygenated gasoline) during the fuel spill. Several factors including hydrophobicity of compounds, nonequilibrium dissolution due to nonuniform coal tar distribution, and heterogeneous media properties affect the oxygenated compound-induced dissolution process. This study provides a basis to predict the facilitated transport of hydrophobic organic compounds from subsurface environment due to the cosolvent effects of oxygenated fuels.     

Bacterial communities and enzyme activities of PAHs polluted soils

Three soils (i.e. a Belgian soil, B-BT, a German soil, G, and an Italian agricultural soil, I-BT) with different properties and hydrocarbon-pollution history with regard to their potential to degrade phenanthrene were investigated. A chemical and microbiological evaluation of soils was done using measurements of routine chemical properties, bacterial counts and several enzyme activities. The three soils showed different levels of polycyclic aromatic hydrocarbons (PAHs), being their contamination strictly associated to their pollution history. High values of enzyme activities and culturable heterotrophic bacteria were detected in the soil with no or negligible presence of organic pollutants. Genetic diversity of soil samples and enrichment cultures was measured as bands on denaturing gradient gel electrophoresis (DGGE) of amplified 16S rDNA sequences from the soil and enrichment community DNAs. When analysed by Shannon index (H'), the highest genetic biodiversity (H'=2.87) was found in the Belgian soil B-BT with a medium-term exposition to PAHs and the poorest biodiversity (H'=0.85) in the German soil with a long-term exposition to alkanes and PAHs and where absence, or lower levels of enzyme activities were measured. For the Italian agricultural soil I-BT, containing negligible amounts of organic pollutants but the highest Cu content, a Shannon index=2.13 was found. The enrichment of four mixed cultures capable of degrading solid phenanthrene in batch liquid systems was also studied. Phenanthrene degradation rates in batch systems were culture-dependent, and simple (one-slope) and complex (two-slope) kinetic behaviours were observed. The presence of common bands of microbial species in the cultures and in the native soil DNA indicated that those strains could be potential in situ phenanthrene degraders. Consistent with this assumption are the decrease of PAH and phenanthrene contents of Belgian soil B-BT and the isolation of phenanthrene-degrading bacteria. From the fastest phenanthrene-degrading culture C(B-BT), representative strains were identified as Achromobacter xylosoxidans (100%), Methylobacterium sp. (99%), Rhizobium galegae (99%), Rhodococcus aetherovorans (100%), Stenotrophomonas acidaminiphila (100%), Alcaligenes sp. (99%) and Aquamicrobium defluvium (100%). DGGE-profiles of culture C(B-BT) showed bands attributable to Rhodococcus, Achromobacter, Methylobacterium rhizobium, Alcaligenes and Aquamicrobium. The isolation of Rhodococcus aetherovorans and Methylobacterium sp. can be consistent with the hypothesis that different phenanthrene-degrading strategies, cell surface properties, or the presence of xenobiotic-specific membrane carriers could play a role in the uptake/degradation of solid phenanthrene.     

Chronic effects of mercuric chloride on the activities of some enzymes in certain tissues of the fresh water murrel,

Alterations in the activities of some enzymes in the brain, gills, intestine, kidney, liver and muscles have been examined in the fresh water murrel, , after exposure to a sublethal concentration of mercuric chloride (3 μg/1) for 15, 30 and 60 days. The results revealed that after 15 days of exposure amino acid oxidase activity was elevated in brain and liver and inhibited in intestine. The activity of xanthine oxidase was increased in gills, and inhibited in kidney. Thirty days exposure produced significant inhibition in the activities of malate dehydrogenase in liver, glutamate dehydrogenase in gills and brain, aminoacid oxidase in gills, and xanthine oxidase in liver and intestine. In contrast, glutamate dehydrogenase in intestine, kidney and liver and aminoacid oxidase in brain and liver were elevated. After 60 days of treatment, a decrease in the activity of glucose-6-phosphatase was recorded in gills, intestine, kidney and liver. Hexokinase activity in kidney and liver, and malate dehydrogenase in all the six tissues were inhibited. Glutamate dehydrogenase activity in intestine, kidney and liver remained higher than in control fish. In brain, kidney and liver the activity of aminoacid oxidase was elevated, but in gills the enzyme activity decreased. Xanthine oxidase activity was inhibited in intestine and liver.