Toxicity of Bacillus thuringienses var. israelensis for larvae of Aedes aegypti and Anopheles stephensi]

The comparative study of the larvicidal action of B. thuringiensis var. israelensis on A. aegypti and A. stephensi shows the greater sensitivity of A. aegypti, with 100% of mortality in 30 to 40 min. at high doses. But, for both species of Mosquito, the toxicity of these bacteria is very high, as shown by the mortality regression curves and by the LC50. This toxicity is associated with the crystals and can be extracted from them by dilute alkali solution, like the general case of the other serotypes of B. thuringiensis. In contrast with these serotypes, B. thuringiensis var. israelensis is not pathogenic to the tested larvae of Lepidoptera.     

A method for chromosome preparations from large fish specimens using in vitro short-term treatment with colchicine

This paper describes a new technique for preparing mitotic fish chromosomes using short-term in vitro treatment with colchicine. The results show that a large number of good quality metaphases (many suitable for chromosome banding) can be obtained by this technique, which requires an average of 1 h and 30 min for all steps. The procedure considerably reduces the time normally required for chromosome preparations in fish.This work was supported by grants FUNCUNESP, FAPESP and CNPq.The authors are grateful to Mr Renato Devidé for technical assistance.     

Sorbitol dehydrogenase in Anas platyrhynchos and Zenaida auriculata auriculata during development.

Sorbitol dehydrogenase (E.C.N. 1.1.1.14) was studied in liver, kidney and gonads of Zenaida auriculata auriculata (golden pigeon) and of Anas platyrhynchos (creole domestic duck) from South American faunes. The specific activity of SDH increased from embryonic to adult stage and is higher in the Anas platyrhynchos tissues. The electrophoretic studies performed in liver and kidney of both species during development showed variations in the number and intensity of the bands in accordance with the age and the species.     

Corticotrophin-releasing action of adrenaline,serotonin and pitressin

Zusammenfassung Der Einfluss von Serotonin, Adrenalin und Pitressin auf den Mechanismus der ACTH-Ausschüttung durch den Hypophysenvorderlappen wurde unter verschiedenen experimentellen Bedingungen untersucht.Bei normalen Ratten zeigten alle geprüften Pharmaka auf die Adenohypophyse eine stimulierende Wirkung, welche nach der Abnahme des suprarenalen Askorbinsäuregehaltes beurteilt wurde.     

Characterization of prehistoric flint mine products

Trace element analyses of flint show statistically valid differences between products of major British and European Neolithic flint mines.     

Morphological effects of serotonin and ketanserin on embryonic chick skin in vitro

Summary Cell and organotypical cultures are used to study the direct effect of serotonin and of ketanserin, a serotonin antagonist, on dermal and epidermal cells of embryonic chick skin. Ketanserin stimulates the increase in cell number and inhibits the differentiation, whereas serotonin stimulates differentiation and inhibits the increase in cell number.     

Endocytotic activity in lizard erythroblasts

Zusammenfassung In Eidechsen-Erythroblasten mit Blutungsanämie wurden elektronenmikroskopisch Zellorganellen und eine aktive Pinocytose nachgewiesen bei gleichzeitiger Aktivitätssteigerung der sauren Phosphatase, die durch Eisenzufuhr noch-verstärkt wurde.

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Dr. C. C.Monteiro carried out this work with the aid of a grant from the Gulbekian Foundation, Lisboa (Portugal).