Survival and development of Pieris brassicae larvae upon application of sublethal doses of chlordimeform

Larvae of the large cabbage white butterfly, Pieris brassicae L. are important pests of cruciferous crops. Third and fifth instars were treated topically with sublethal doses of the formamidine pesticide chlordimeform. A number of excitable actions were induced but they did not persist beyond 24 hours. Following the initial period, however, subsequent development was delayed and mortality increased, particularly when third instars were treated. Dosing fifth-instar larvae caused few further deaths. A link is suggested between these results and the nutritional status of the insects, and they are discussed in terms of how they might contribute towards control.

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Résumé Les chenilles de troisième et cinquième stades de P. brassicae L. ont reçu une application superficielle de chlordiméforme, insecticide à la formamidine. Les doses inférieures à 335 g/g ont été sublétales, provoquant plusieurs formes d'excitation. Bien que leur comportement soit redevenu normal en 24 heures, les troisièmes stades traités ont eu leur développement retardé et une mortalité accrue. Le traitement des chenilles plus âgées a eu moins d'effets. Une relation est suggérée entre ces observations et le régime alimentaire de cet insecte; une réduction de l'alimentation, plus importante chez les chenilles de troisième que de cinquième stade de P. brassicae, accompagne le début des altérations du comportement provoquées par le chlordiméforme. La discussion porte sur le mécanisme de contrôle sublétal du chlordiméforme, impliquant des effects immédiats et retardés.

     

Observations on 6-mercaptopurine activity in Saccharomyces cerevisiae

Abstract Hydrogen fluoride treatment of [¹⁴C-glycerol]lipoteichoic acid synthesized by growing Streptococcus faecium ATCC9790 in the presence of 1,3[¹⁴C]glycerol produced five radioactive, water-soluble products which were identified by chromatographic and analytical techniques to be tetraglucosyl glycerol, triglucosyl glycerol, diglucosyl glycerol, monoglucosyl glycerol and unsubstituted glycerol. The percent composition of each varied modestly from culture to culture and ranged between 7 and 8% for the tetra-, 20.5 and 31.2% for the tri-, 11.3 to 23.5% for the di-, 20.9 to 26.8% for the mono-, and 23.1 to 34.8% for the unsubstituted glycerol. The same glucosylated glycerol compounds could be obtained in an in vitro reaction in which a 30 000 × g particulate enzyme catalyzed the incorporation of [³H]glucose from UDP [³H]glucose into lipoteichoic acid.     

Growth of Escherichia coli in the presence of trimethoprim-sulfamethoxazole facilitates detection of Shiga-like toxin producing strains by colony blot assay

Abstract Subinhibitory concentrations of trimethoprim-sulfamethoxazole increased the total yield of Shiga-like toxin (SLT), produced by Shigella dysenteria 1 and by enterophathogenic and enterohemorrhagic strains of Escherichia coli . Stimulation of SLT synthesis by trimethoprim-sulfamethoxazole was demonstrated by an increase in cytotoxic activity for HeLa cells and the diameter of the zone formed around bacterial colonies probed with monoclonal antibodies to SLT. Thus, supplementation of culture media with trimetroprimsulfamethoxazol will facilitate SLT purification and detection of SLT-producing bacteria.     

Assay methodology for prednisolone, prednisolone acetate and prednisolone sodium phosphate in rabbit aqueous humor and ocular physiological solutions

Prednisolone, prednisolone acetate and prednisolone sodium phosphate are glucocorticoids used for ocular, anti-inflammatory therapy. A reversed-phase high-performance liquid chromatographic assay using ultraviolet detection has been developed that affords baseline resolution of the above analytes in balanced salt solutions and rabbit aqueous humor. The drugs can be quantified at 0.025–0.05 μg/ml in the above matrices; 6α-methylprednisolone is used as the internal standard. Both esters of prednisolone are vulnerable to chemical and enzymatic hydrolysis giving prednisolone. Analysis of aqueous humor samples shows prednisolone acetate penetrating/metabolizing primarly to prednisolone; prednisolone sodium phosphate penetrates the cornea giving the ester and alcohol.     

Subacute and Chronic In Vivo Lithium Treatment Inhibits Agonist- and Sodium Fluoride-Stimulated Inositol Phosphate Production in Rat Cortex

We have investigated the effects of in vivo lithium treatment on cerebral inositol phospholipid metabolism. Twice-daily treatment of rats with LiCl (3 mEq/kg) for 3 or 16 days resulted in a 25-40% reduction in agonist-stimulated inositol phosphate production, compared with NaCl-treated controls, in cortical slices prelabelled with [3H]inositol. A small effect was also seen with 5-hydroxytryptamine (5-HT) 24 h after a single dose of LiCl (10 mEq/kg). Dose-response curves to carbachol and 5-HT showed that lithium treatment reduced the maximal agonist response without altering the EC50 value. This inhibition was not affected by the concentration of LiCl in the assay buffer. Stimulation of inositol phosphate formation by 10 mM NaF in membranes prepared from cortex of 3-day lithium-treated rats was also inhibited, by 35% compared with NaCl-treated controls. Lithium treatment did not alter the kinetic profile of inositol polyphosphate formation in cortical slices stimulated with carbachol. Muscarinic cholinergic and 5-HT2 bindings were unaltered by lithium, as was cortical phospholipase C activity and isoproterenol-stimulated cyclic AMP formation. [3H]Inositol labelling of phosphatidylinositol 4,5-bisphosphate was significantly enhanced by 3-day lithium treatment. The results, therefore, indicate that subacute or chronic in vivo lithium treatment reduces agonist-stimulated inositol phospholipid metabolism in cerebral cortex; this persistent inhibition appears to be at the level of G-protein-phospholipase C coupling.     

Characterization of waldmeister, a novel developmental mutant in Arabidopsis thaliana

A novel Arabidopsis thaliana (L.) Heynh. developmental mutant,waldmeister (wam), is described. This mutant was found in theprogeny arising from an Ac-Ds tagging experiment, but does notappear to be tagged by an introduced transposon. This recessivenuclear mutation maps between GAPB and ap1 on chromosome 1 andshows extreme morphological and physiological changes in bothfloral and vegetative tissues. Changes to the vegetative phenotypeinclude altered leaf morphology, multiple rosettes, stem fasciation,retarded senescence and disturbed geotropic growth. Changesto the floral phenotype include delayed flowering, increasednumber of inflorescences, determinate inflorescences, alterednumber and morphology of floral organs, chimeric floral organs,and ectopic ovules . wam was crossed to a number of previouslydescribed floral mutants: apetela 2, apetela 3, pistillata,agamous, and leafy. The phenotype of the double mutant was ineach case additive. In the case of agamous, however, the indeterminaterepetitive floral structure of agamous was lacking, emphasizingthe determinate inflorescence growth of wam. The extreme phenotypeof the wam mutant is suggestive of a disturbance to a gene ofglobal importance in the regulation of plant growth and development. Key words: Arabidopsis thaliana, waldmeister, developmental mutant, flower mutant