The plant MITE mPing is mobilized in anther culture

Transposable elements constitute a large portion of eukaryotic genomes and contribute to their evolution and diversification. Miniature inverted-repeat transposable elements (MITEs) constitute one of the main groups of transposable elements and are distributed ubiquitously in the genomes of plants and animals such as maize, rice, Arabidopsis, human, insect and nematode. Because active MITEs have not been identified, the transposition mechanism of MITEs and their accumulation in eukaryotic genomes remain poorly understood. Here we describe a new class of MITE, called miniature Ping (mPing), in the genome of Oryza sativa (rice). mPing elements are activated in cells derived from anther culture, where they are excised efficiently from original sites and reinserted into new loci. An mPing-associated Ping element, which has a putative PIF family transposase, is implicated in the recent proliferation of this MITE family in a subspecies of rice.     

Tagesperiodik des O2-Umsatzes der Rattenleber

Summary There is a 24 h periodicity of the rat liver tissue respiration (Qo₂) with maximal values at about 07.30 h and minimal values at about 17.00 h.

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Auslandsstipendiat der Schweizerischen Regierung (1963/64).

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Die Arbeit wurde unterstützt von der Max-Planck-Gesellschaft zur Förderung der Wissenschaften, Deutschland.     

Inhibitory effect of flavonoids on DNA-dependent DNA and RNA polymerases

Summary Flavonoids, (–)-epigallocatechin (1), myricetin (2) and quercetin (3), were investigated for inhibitory effects onE. coli DNA polymerase I and T7 bacteriophage RNA polymerase. In both DNA and RNA synthesis,1 and3 inhibited enzyme reactions by non-competitive and mixed type inhibition respecitively, with regard to template DNAs. Myricetin (2) inhibited DNA and RNA polymerase reactions by mixed type and competitive type inhibition, respectively, with template DNAs. It was suggested that2 interacts with covalently closed/circular DNA.     

Inhibitory effect of flavonoids on DNA-dependent DNA and RNA polymerases

Flavonoids, (-)-epigallocatechin (1), myricetin (2) and quercetin (3), were investigated for inhibitory effects on E. coli DNA polymerase I and T7 bacteriophage RNA polymerase. In both DNA and RNA synthesis, 1 and 3 inhibited enzyme reactions by non-competitive and mixed type inhibition respectively, with regard to template DNAs. Myricetin (2) inhibited DNA and RNA polymerase reactions by mixed type and competitive type inhibition, respectively, with template DNAs. It was suggested that 2 interacts with covalently closed circular DNA.     

Temperature dependence of the deformability of Carp (Cyprinus carpio) red blood cells

Summary Measurements were made of the deformability of the red cells of carp at different temperatures and compared with previous results obtained with another teleost fish (yellowtail) and human red cells. Changes with temperature are similar to those obtained with yellowtail, but interpretation of differences in terms of mean corpuscular volume alone are insufficient to account for the variations, which seem to be mainly due to differences in cellular deformability of the cells themselves.Acknowledgment. We wish to thank Karlheinz Götz for his excellent technical assistance. Reprint requests should be addressed to G.M.H.