The effect of ischemia and recirculation, hypoxia and recovery on anti-oxidant factors and beta-adrenoceptor density. Is the damage in the erythrocytes a reflection of brain damage caused by complete cerebral ischemia and by hypoxia?

This investigation was focussed on the gravity of tissue injury caused by complete ischemia (for five min) and hypoxia (for three weeks) in the cerebral cortex (homogenate) and the erythrocyte lysate or the erythrocyte membrane of the rat in order to investigate if the changes that occur in brain tissue are reflected in the erythrocyte. To this end, glutathione (GSH), superoxide dismutase (SOD) and catalase were measured, also alterations in beta-adrenoceptor density under these two conditions were examined. It was found that in ischemia partial parallelism in changes that occur in the central nervous system (cerebral cortex) and the erythrocyte exists. The SOD activity became higher and the beta-adrenoceptor density (measured as specific (-)-[125I] iodocyanopindolol binding) was decreased in both tissues. However after the hypoxic condition we established a decrease in the number of beta-adrenoceptors in the cerebral cortex but an increase in beta-adrenoceptor density in the erythrocyte.     

Cloning of the yeast ribosomal DNA repeat unit in SstI and HindIII lambda vectors using genetic and physical size selections.

The size of DNA fragments complementary to ribosomal RNA was determined in SstI and HindIII restriction spectra from totally and partially cleaved yeast (Saccharomyces cerevisiae) DNA. The results indicated that the yeast ribosomal RNA gene cluster consists of 9000 base-pair long tandemly repeated units. Three different repeating units, which are overlapping with respect to their sequences, were cloned as SstI and HindIII fragments with λ vectors. The isolation of these clones was facilitated by genetic or physical preselection for those recombinant phage which contained DNA inserts in the expected size range. Both preselection methods gave about a 30-fold purification with respect to the λ-rDNA clones. A heteroduplex analysis of the clones obtained with a three-component HindIII vector showed that the center part of the λ genome carrying λ recombination and regulation genes (57 to 77% λ) can become inverted without apparent decrease of growth capacities.     

Korrelation von Merkmalen der C4-Photosynthese bei Vertretern verschiedener Ordnungen der Angiospermen

Summary A study of leaf anatomy, chloroplast ultrastructure, labelling pattern after short-time ¹⁴CO₂ fixation, and CO₂ compensation point indicates that Chamaesyce buxifolia (Engelm. ex Hitche.) Small (Geraniales), Pectis leptocephala (Cass.) Urb. (Campanulales), and Imperata arundinacea Cyr. (Graminales) have typical features of plants exhibiting the C₄-dicarboxylic acid pathway of photosynthesis. Thus it is established that the correlation of these C₄ properties, well known in various orders of Monocotyledons (Graminales, Cyperales) and in the dicotyledonous order of the Centrospermae, is also characteristic of some species in other systematically widely separated orders within the Dicotyledons.     

Two-dimensional DNA gel electrophoresis as a method for analysis of eukaryotic genome structure: evaluation using Tetrahymena thermophila DNA

There is growing interest in mapping and analyzing complete eukaryotic genomes. Yee and Inouye (in Experimental Manipulation of Gene Expression, pp. 279-290, Academic Press, New York) demonstrated that bacterial chromosomes can be resolved into interpretable patterns of DNA fragments by means of restriction enzyme digestion and electrophoresis in two dimensions. We have begun to explore applications of this procedure to analysis of eukaryotic genomes, which are far more complex. Tetrahymena thermophila was selected as a model organism because its genome is small, roughly equivalent to that of a single human chromosome. In addition, each Tetrahymena cell contains two nuclei which differ in sequence composition and methylation. Our results demonstrate that the Tetrahymena genome can be resolved into complex patterns of fragments in two dimensions. Hybridization to Southern blots of these gels with a multiply repeated sequence probe yielded analyzable patterns of a subset of the genome. The blots reveal alterations in genome structure due to methylation and rearrangement. Future extensions of the method are discussed.