Bone marrow genotoxicity of N-methyl, N-nitrosourea (NMU): n-alkanols as sister chromatid exchange (SCE) anti-inducers

The in vivo SCE test was used to demonstrate significant inhibition of NMU bone marrow genotoxicity by pretreatment of Chinese hamsters with n-alkanols. Our findings exclude a loss of intracellular DNA alkylation potential through a competitive direct reaction of NMU with the weakly nucleophilic polar end of the n-alkanols, but not through methylations of nucleophilic membrane sites possibly liberated by structural modifications which the membrane-active amphiphilics induce.     

Der Einfluss des Urin-pH auf die Aktivität von Urinenzymen

Summary The relationship between the pH of urine and the measured activity of ULDH, UAP and UAA was investigated in vivo and in vitro. The activity of ULDH and UAP is only half as much, or less, in acid urine (pH 4.8–5.1) as it is in alkaline urine (pH 7.0–8.1). The UAA activity, however, does not change in the pH range measured. The isoenzymes ULDH 2–4, present in alkaline urine of normal adults, does not appear in acid urine.     

On the relative position of the centromere of chromosome 3 inDrosophila melanogaster

Zusammenfassung HomozygoteDrosophila-melanogaster-Weibchen, genetisch markiert mit scarlet (st), Kinked (Ki) und pink peach (P^p) wurden bestrahlt, um Compound-3-Chromosomen herzustellen. Es wurden ausschliesslich st/st- und P^p Ki/Ki(?) P^p-Compoundchromosomen gefunden. Dies zeigt, dass das Zentromer links der Markierung Kinked liegt.

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This work was supported by Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung.     

Lettuce seedling growth: Antagonism between gibberellic acid and Niacin

Zusammenfassung Gibberellin und Niacin sind Antagonisten, Niacin hemmt das Wurzelwachstum vonLactuca sativa, während Gibberellin diese Wirkung teilweise aufhob.     

Mécanisme d'action du chloramphénicol dans l'inhibition de la production d'anticorps induite par de différents types d'antigènes

Summary Chloramphenicol (CAF) administered to rabbits during the whole period of immunization, is able to suppress almost completely the antibody response against horse serum albumin and globulins (HSA, HSG) andEscherichia coli: on the other hand, it does not inhibit antibody response to heterologous RBC. The possible mechanism of the inhibiting action of the CAF in antibody response to HSA, HSG andE. coli is discussed, and some hypotheses are put forward on the possible reasons for the different behaviour of CAF on the immune response induced by heterologous RBC.