稀土等对三七及土壤中六六六、滴滴涕降解作用研究

通过采用稀土等5种改良剂对六六六、滴滴涕污染的三七栽培土壤进行处理,而后测定三七茎叶、块根及土壤中六六六、滴滴涕的残留量。结果表明,稀土等5种改良剂对三七茎叶及块根中六六六残留具有明显的降解作用,但对土壤中六六六残留除稀土、NH3HCO3＋泥碳土及NaHCO3有明显的降解作用外,NH3HCO3、腐殖酸钠只有一定的降解作用;其次,稀土等5种改良剂对三七茎叶及其栽培土壤中滴滴涕残留具有明显的降解作用,而对三七块根中滴滴涕残留除稀土、NH3HCO3＋泥碳土（1：1）及NaHCO3有一定的降解作用外,NH3HCO3、腐殖酸钠没有降解作用。由此认为,利用稀土、NH3HCO3＋泥碳土（1：1）及NaHCO3处理六六六、滴滴涕污染土壤可以成为三七及其栽培土壤中六六六、滴滴涕残留的降解技术措施。     

Azidoatrazine: photoaffinity label for the site of triazine herbicide action in chloroplasts

Binding of the 4-azido analog of the herbicide atrazine to pea chloroplast membranes was compared with that of atrazine. When [(14)C]azidoatrazine was treated with 300-nanometer ultraviolet light in situ, reversibility of binding was lost in proportion to the duration of irradiation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of chloroplast membranes irradiated in the presence of [(l4)C]-azidoatrazine indicated radioactivity in only one region, corresponding to a protein with a molecular weight of approximately 32,000. Azidoatrazine is a photoaffinity reagent for the triazine binding site in chloroplasts and serves as a label to identify this site, which may be the apoprotein of the secondary electron acceptor in photosystem II.     

Acetolactate synthase is the site of action of two sulfonylurea herbicides in higher plants

Biochemical and genetic studies of a tobacco mutant resistant to the herbicides chlorsulfuron and sulfometuron methyl have demonstrated that these sulfonylurea herbicides inhibit acetolactate synthase, the first enzyme specific to the branched chain amino acid biosynthetic pathway. Resistance of this mutant is accomplished by production of a form of the enzyme that is insensitive to inhibition by the two herbicides.     

Transplantation of the cockroach circadian pacemaker

Surgical removal of the optic lobes of the cockroach Leucophaea maderae followed by transplantation of the optic lobes from another individual led to a restoration of the circadian activity rhythm in 4 to 8 weeks. The free-running period of the restored rhythm was determined by the period of the donor rhythm before surgery. The results suggest that the transplanted optic lobe contains a circadian clock that regenerates those neural connections with the host brain that are necessary to drive the circadian rhythm of activity.     

Tricyclic antidepressants: evidence for an intraneuronal site of action

Desipramine, a tricyclic antidepressant drug, almost completely prevents the accumulation of tritiated norepinephrine by sympathetic neurons of the rat heart after the injection of a tracer dose of the labeled amine. However, desipramine does not alter the accumulation of norepinephrine after the injection of a large dose of the neurohormone. Despite the failure of desipramine to block the neuronal uptake of norepinephrine, it still prevents exogenous norepinephrine from displacing the endogenous neurohormone (previously labeled with H(3)-norepinephrine) from intraneuronal storage sites.     

Dechlorination of DDT in frozen blood

Dechilorination of a commercial mixture of o, p'-DDT and p, ppDDT to p, p'-DDD and p, p'-DDE occiurs in avian blood stored at-20 degrees C, indicatinig nonenzymalic degradation. The subsequent disappearance of these two metabolites suggests conversion to other metabolites which cannot be detected by gas chromatography with an electron-captutre detector.     

Induced photolysis of DDT

Photolysis of mixtures of certain alkyl halides and aromatic amines produces dehalogenation of the halide. These reactions involve a photoinduced charge transfer from the amine to the halide. Photolysis of tritolylamine and carbon tetrachloride produces tritolylaminium chloride. Photolysis of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and diethylaniline at 3100 angstroms yields 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), p,p'-dichlorobenzophenone (DDCO), and hydrogen chloride. Photolysis of DDT does not occur unless an inducer which has a low ionization potential, such as diethylaniline, is present. The DDT-diethylaniline mixture is stable in the dark, and the induced photolysis is not affected by triplet quenchers.     

室内人工繁殖美洲大蠊的产卵习性

美洲大蠊从4月份开始活动,产卵高峰期发生在6月下旬至9月中旬,它喜欢于角落产卵,并有自食其卵的习性.用标准饲料饲养美洲大蠊,并提供足够的水,增大养虫笼容积,增设阻隔层,可降低美洲大蠊食卵率.     

DDT tissue retention: sudden rise induced by the addition of aldrin to a fixed DDT intake

The oral administration of aldrin to male and female beagles, whose diet already included a fixed, regular oral dosage of DDT, resulted in a dramatic rise in the concentrations of DDT, DDE, and DDD in blood and fat.     

河北省土壤中滴滴涕的残留量分析

采用快速溶剂萃取仪和气相色谱仪研究了河北省土壤中有机氯农药滴滴涕的残留状况.结果表明,河北省土壤中滴滴涕的残留量均值为51.52 ng/g,经对比相关标准,河北省土壤中的滴滴涕残留量处于较低的污染水平.     

Decline of DDT residues in migratory songbirds

Analyses of ten species of migratory songbirds killed when the birds flew into television towers in Florida showed a progressive decline in the concentration of DDT and its metabolites (DDD and DDE) in their fat depots for the period 1964 to 1973. This decline is apparently correlated with the decreased usage of DDT in the United States during the same time.