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Abstract The effect of glucose and dissolved oxygen in a synthetic medium simulating the standard composition of grape juice on the production of ethyl acetate and isoamyl acetate by a Saccharomyces cerevisiae strain during alcoholic fermentation was studied. The specific in vitro activity of alcohol acetyltransferase (AATase, EC 2.3.1.84) and esterases (ESase, EC 3.1.1.1; hydrolysis and synthesis of esters) in cell-free extracts was also examined. The specific activity of AATase for ethyl acetate was found to peak at the beginning of the exponential growth phase and that for isoamyl acetate at its end. While the glucose concentration only affected the maximum specific activity of AATase, and only slightly, oxygen inhibited such activity, to a greater extent for isoamyl acetate than for ethyl acetate. On the other hand, esterases were found to catalyse the synthesis of ethyl acetate only at a low or medium glucose concentration (50 or 100 g l -1 , respectively), and to reach their maximum hydrolytic activity on isoamyl acetate during the stationary growth phase. The highest ethyl acetate and isoamyl acetate concentrations in the medium were obtained with a glucose concentration of 250 g l -1 and semianaerobic conditions.

The major surface protein MSP‐1 of Plasmodium falciparum blood‐stage malaria parasites contains notably conserved sequence blocks with unknown function. The recombinant protein 190L, which represents such a block, exhibits a high affinity for red blood cell membranes. We demonstrate that both 190L and native MSP‐1 protein bind to the inner red blood cell membrane skeleton protein spectrin. By using overlapping peptides covering the 190L molecule, we show that the spectrin contact site of 190L is included in a linear sequence of 30 amino acid residues. Association of 190L with naturally occurring spectrin deficient red blood cells is drastically reduced. In the same cells parasite invasion is normal, but the intracellular parasite development arrests late in the trophozoite stage. A similar situation arises when synthetic peptides covering the spectrin recognition sequence of 190L are added to P.falciparum cultures. These data and the cellular localization of MSP‐1 suggest the possibility that MSP‐1 associates with spectrin under natural conditions.

The major surface protein MSP‐1 of Plasmodium falciparum blood‐stage malaria parasites contains notably conserved sequence blocks with unknown function. The recombinant protein 190L, which represents such a block, exhibits a high affinity for red blood cell membranes. We demonstrate that both 190L and native MSP‐1 protein bind to the inner red blood cell membrane skeleton protein spectrin. By using overlapping peptides covering the 190L molecule, we show that the spectrin contact site of 190L is included in a linear sequence of 30 amino acid residues. Association of 190L with naturally occurring spectrin deficient red blood cells is drastically reduced. In the same cells parasite invasion is normal, but the intracellular parasite development arrests late in the trophozoite stage. A similar situation arises when synthetic peptides covering the spectrin recognition sequence of 190L are added to P.falciparum cultures. These data and the cellular localization of MSP‐1 suggest the possibility that MSP‐1 associates with spectrin under natural conditions.

Three rapid enzyme immunoassay techniques for the detection of respiratory syncytial virus antigen (Becton Dickinson Directigen RSV, Abbott RSV Testpack and Abbott RSV EIA) and cell culture were evaluated in a total of 250 nasal washings. The sensitivity and specificity were 62 % and 76 % respectively for Directigen, 64 % and 86 % for RSV Testpack, and 76 % and 81 % for RSV EIA, taking cell culture as the reference method. Agreement between cell culture and EIA techniques was 79 % (70 positive and 128 negative results). All three EIA techniques gave positive results in 69 samples (52 positive and 17 negative in the cell culture). In 121 samples all three EIA techniques gave negative results (103 negative and 18 positive in the cell culture). Using the cell culture technique 46 strains other than respiratory syncytial virus were isolated.