Bacterial degradation of styrene involving a novel flavin adenine dinucleotide-dependent styrene monooxygenase.

By using styrene as the sole source of carbon and energy in concentrations of 10 to 500 microM, 14 strains of aerobic bacteria and two strains of fungi were isolated from various soil and water samples. In cell extracts of 11 of the bacterial isolates, a novel flavin adenine dinucleotide-requiring styrene monooxygenase activity that oxidized styrene to styrene oxide (phenyl oxirane) was detected. In one bacterial strain (S5), styrene metabolism was studied in more detail. In addition to styrene monooxygenase, cell extracts from strain S5 contained styrene oxide isomerase and phenylacetaldehyde dehydrogenase activities. A pathway for styrene degradation via styrene oxide and phenylacetaldehyde to phenylacetic acid is proposed.     

A general method for the synthesis of 5'-monophosphates of DNA fragments via phosphotriester intermediates.

A new and attractive phosphorylation procedure which allows the introduction, via phosphotriester intermediates, of 5'-phosphate functions of DNA fragments is described. The method is based on the activation of bifunctional phosphorylating agents with 1-hydroxybenzotriazole. The approach will be exemplified by the synthesis of pACGC using four different 5'-phosphotriester intermediates.     

Characterization of cloned murine cytolytic T cell lines

Murine cytolytic T lymphocytes can be kept in continuous culture apparently indefinitely by repeated passage in a concanavalin A-induced growth promoting medium. Some of these long-term cell lines maintain their cytolytic activity. Starting from three such populations, several cloned cytolytic T cell lines were derived and subsequently subcloned one or more times. Considerable variation in the levels of cytolytic activity was observed between different subclones; some initially active subclones lost activity with prolonged culture. In addition, one of the clones appeared to progressively lose the relative specificity demonstrated during the earlier passages of the parent cell line.     

Polymorphism at the G6pd and 6Pgd loci in Drosophila melanogaster. III. Developmental and biochemical aspects

The electrophoretic variants of G6PD and 6PGD isolated from the Bogota Drosophila melanogaster population were characterized developmentally and biochemically. Changes in in vitro enzyme activity during development were comparable to those found for other dehydrogenases: an increase in the larval and adult stage and a decrease in the pupal stage. During the whole life cycle the "S" enzyme of both loci showed a higher activity than the "F" enzyme. MgCl2 had a stimulating effect on the activity of both enzymes whereas their heat stability was decreased. The allozymes of 6PGD had different Vmax's but were comparable with respect to Km values, pH optimum, and stability at 45 C. the allozymes of G6PD showed different Vmax's and differed in stability at 35 C, but had similar Km values and pH optima. As the difference in stability was probably due to differences in molecular structure of the allozymes, the differences in activity found at high pH and high MgCl2 concentration were most probably due to this difference in stability.     

Suspension cultures of mononuclear phagocytes in the teflon culture bag.

The Teflon culture bag (TCB) provides a cheap and simple method for culturing mononuclear phagocytes in suspension. The cells can easily be recovered intact and used in further experiments. The Teflon membrane is permeable to O₂, CO₂, and water vapor. Therefore, gas exchange is guaranteed when the bags are sealed after being filled with medium and cells. The risk of infection is minimized since the cultures are incubated in closed bags.     

Ultrastructure of reticulum cells in the bone marrow

In this study the attempt was made to classify the reticulum cells of the bone marrow on the basis of electron-microscopic findings. The basis of the differentiation was the ability of the cells to phagocytize substances or not. For two cell types the intracytoplasmic filaments were used as distinctive marks. The following classification resulted: (a) phagocytic reticulum cells, (b) undifferentiated reticulum cells, (c) fibrous reticulum cells of type I, which contain filaments of 4-8 nm diameter and are located near the blood sinus of the bone marrow, (d) fibrous reticulum cells of type II, which contain intracytoplasmic filaments of 10 nm diameter; since these cells contain neutral fat bodies, the possibility of a reversible conversion to fat cells has to be assumed and (e) fibroblasts, cells which synthesize the substance of the extracellular space. A connection of reticulum cells to haematopoietic functions or to stem cell functions could be found.