Function of phospholipids in Escherichia coli. Characterization of a mutant deficient in cardiolipin synthesis.

Screening of a collection of temperature-sensitive mutants of Escherichia coli for defects in phospholipid metabolism led to the isolation of a mutant deficient in cardiolipin synthesis. The defective gene, named cls, is closely linked to the trp marker and maps at about Minute 27 on the E. coli chromosome. After transfer of cls to a defined genetic background by transduction, the mutant has the following properties as compared to an isogenic wild type. Exponentially growing cells show a reduction in cardiolipin content by a factor of at least 15 (less than 0.2 mol % of the total phospholipids). A crude membrane fraction derived from the mutant is unable to synthesize cardiolipin from phosphatidylglycerol in vitro. The mutant has no distinctive phenotype regarding its growth properties, membrane-associated respiratory functions, or the ability to insert bacteriophage M13 coat protein into the cell envelope. The cls mutation confers a 5-times reduction in the turnover of the phosphate moiety of phosphatidylglycerol.     

DDT induced ethological changes in estuarine fish

Synopsis Experiments were carried out to study the feeding rates of the predator fish Therapon jarbua (Forsk) on mullet juveniles, before and after treatment with DDT. Mullet juveniles treated with a subacute concentration, were refused by the control predators, whereas predators treated with a subacute concentration consumed more mullet juveniles. In the present study crescent perch T. jarbua were exposed to subacute and acute concentrations of DDT, and their behaviour was compared with that of the control predators. There were changes in oriented behaviour and co-ordinated movements, and in feeding, aggression and comfort behaviour of the fish. Inflammation in the gills, and caudal fin serration, were noticed in treated fishes. The findings presented here throw light on fundamental pathways by which pollutants interact with the behaviour of fishes.     

Activity of the respiratory inhibitor RF in human red cells in anaemia

Stroma-free haemolysates of red cells from patients with acute or latent anaemia inhibit the NADH oxidase activity of submitochondrial particles from beef heart. The inhibitory activities appeared significantly more frequently in anaemic patients than in normal persons and are likely due to the action of a factor which is identical or similar to the inhibitory protein RF present in rabbit reticulocytes. The possible use of the inhibitor assay for clinical purpose is under discussion.