Microorganisms capable of metabolizing the herbicide metolachlor

We screened several strains of microorganisms and microbial populations for their ability to mineralize or transform the herbicide metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetami de] because such cultures would potentially be useful in the cleanup of contaminated sites. Although we used various inocula and enrichment culture techniques, we were not able to isolate microorganisms that could mineralize metolachlor. However, strains of Bacillus circulans, Bacillus megaterium, Fusarium sp., Mucor racemosus, and an actinomycete were found to transform metolachlor. Several metabolites could be determined with high-performance liquid chromatography. The tolerance of the strains to high concentrations of metolachlor was also evaluated for the usefulness of the strains for decontamination. Tolerance of the actinomycete to metolachlor concentrations over 200 ppm (200 micrograms/ml) was low and could not be increased by doubling the sucrose concentration in the growth medium or by using a large biomass as inoculum. However, a Fusarium sp. could grow and transform metolachlor up to a concentration of 300 ppm.     

Molecular cloning of a cDNA for the E1 alpha subunit of rat liver branched chain alpha-ketoacid dehydrogenase

We have isolated a cDNA encoding the branched chain alpha-ketoacid dehydrogenase E1 alpha subunit. A rat liver lambda gt11 expression library was screened with antibody reactive with the 2-oxoisovalerate dehydrogenase (lipoamide) component. A positive clone, lambda BZ304, contains a 1.7-kilobase pair cDNA insert with a 1323-base pair open reading frame. Translation of the open reading frame predicts the 24 residues of the previously reported phosphorylation sites 1 and 2 for the bovine kidney and rabbit heart enzymes. The N-terminal sequence of purified E1 alpha was determined, and this sequence was found 40 residues from the beginning of the deduced peptide sequence. Northern blots of rat liver and muscle RNA demonstrate a single mRNA species of approximately 1.8 kilobase pairs in each tissue, suggesting that this cDNA is nearly full length.     

Antimutagenic effect of garlic (Allium sativum L.) on 4NQO-induced mutagenesis in Escherichia coli WP2

Aqueous extract prepared from garlic bulbs markedly suppressed the mutagenesis in both E. coli WP2 trp- and E. coli WP2 trp- uvrA- induced by 4-nitroquinoline 1-oxide (4NQO), but not that induced by UV. Cellular toxicity, inhibition of the expression of the Trp+ phenotype and delay of the first cell division after 4NQO treatment were not observed in the presence of the extract. Since the extract showed identical antimutagenic effects against 4NQO in both test strains but no effect on the mutagenesis of UV, it seems that the extract might act by inactivating the electrophilic group(s) of 4NQO or inhibiting its metabolic activation.     

Water status of drought-resistant and drought-sensitive sorghum treated with ethephon

The effects of ethephon on stomatal resistance, water potential, osmotic potential, turgor potential, and ethylene production were determined on leaves of a drought-resistant (KS 65) and a drought-sensitive (IA 25) genotype of sorghum [Sorghum bicolor (L.) Moench] grown under wellwatered or drought-stressed conditions. With both sufficient and limited water supply, ethephon had no effect on the adaxial, abaxial, or total stomatal resistance of either genotype. For both water treatments, the adaxial stomatal resistance of the drought-sensitive genotype was higher than that of the drought-resistant genotype. Ethephon increased the amount of ethylene produced by the plants under both levels of water. For plants with sufficient water, water potentials of both genotypes were lowered by ethephon. Ethephon had no effect on the water potentials under drought or on the osmotic potentials under either water regime. With drought, the turgor potential of the drought-sensitive genotype, but not that of the drought-resistant, was increased by ethephon.     

Role of oxidatively modified LDL in atherosclerosis

Oxidative modification of LDL is accompanied by a number of compositional and structural changes, including increased electrophoretic mobility, increased density, fragmentation of apolipoprotein B, hydrolysis of phosphatidylcholine, derivatization of lysine amino groups, and generation of fluorescent adducts due to covalent binding of lipid oxidation products to apo B. In addition, oxidation of LDL has been shown to result in numerous changes in its biologic properties that could have pathogenetic importance, including accelerated uptake in macrophages, cytotoxicity, and chemotactic activity for monocytes. The present article summarizes very recent developments related to the mechanism of oxidation of LDL by cells, receptor-mediated uptake of oxidized LDL in macrophages, the mechanism of phosphatidylcholine hydrolysis during LDL oxidation, and other biologic actions of oxidized LDL including cytotoxicity, altered eicosanoid metabolism, and effects on the secretion of growth factors and chemotactic factors. In addition, this review will examine the evidence for the presence of oxidized LDL in vivo and the evidence that oxidized LDL plays a pathogenetic role in atherosclerosis.     

Specific binding and uptake of apolipoprotein E-free high density lipoproteins by cultured liver parenchymal cells of copper-deficient rats

The influence of copper deficiency on the binding and uptake of apolipoprotein E-free high density lipoprotein (apo E-free HDL) in cultured rat hepatic parenchymal cells was examined in this study. Male weanling Sprague-Dawley rats were randomly divided into two treatments, a Cu-adequate (7.33 mg Cu/kg diet) or a Cu-deficient (1.04 mg Cu/kg diet) group. After 7 weeks, plasma apo E-free HDL were isolated by a combination of ultracentrifugation, gel filtration, and heparin-Sepharose affinity chromatography. Parenchymal cells were isolated from collagenase perfused liver of Cu-deficient and adequate rats and cultured for 16 hours at 37 degrees C prior to incubation with iodinated apo E-free HDL from the same treatment group. Cells were incubated with 5 microg/ml(125) I-apo E-free HDL for 2, 6, or 12 hours in the presence or absence of 200 microg/ml (40-fold) excess unlabeled apo E-free HDL. Increases in specific binding at 4 degrees C and specific cell-associated uptake at 37 degrees C as a function of time were observed with cells and HDL from Cu-deficient rats. Cells were also incubated for 6 hours with 8 concentrations of (125)I-apo E-free HDL in the presence or absence of excess unlabeled HDL. Although no significant increase in specific binding was detected at 4 degrees C as a function of ligand concentration, the response tended to be higher at 5 to 15 microg HDL/ml for the Cu-deficient treatment. However, at 37 degrees C the specific cell-associated uptake was increased markedly with cells and HDL from Cu-deficient rats. The observed increases in HDL binding and uptake indicate that these processes may be enhanced in Cu-deficient rats. These data are also consistent with recent in vivo results which indicate that plasma clearance and tissue uptake of HDL are increased in Cu-deficient rats.     

大麦染色体银带的研究

本文以六棱、四棱和二棱大麦为材料,用去壁低渗火焰干燥法制备染色体标本,标本在60℃恒温下经70—80％AgNO_3水溶液处理12—14小时,可在核仁组成区、着丝粒和端粒出现黑色银染区。细胞化学反应说明这些不同区域的银染物质具有相同的性质。银染带型与C带型和N带型迥然不同,3种大麦的银染带型也有差别。试验还证明染色体标本制备技术对银染效果影响极大,只有合适的酶解和火焰干燥处理才能促使着丝粒和端粒显示出银染正反应。