Living immobilized Acetobacter in Ca-alginate in vinegar production: Perliminary study on optimum conditions for immobilization

Summary The optimum conditions forAcetobacter immobilization were investigated. The results show that: 1) the maximum oxygen uptake rate (OURm) and cell release are related to alginate and cell concentration in the gel; 2)different alginate concentration does not affect cell viability, but long storage in CaCl₂ reduces the number of living cells; 3)the double alginate gel layers had no influence on cell viability and on the OURm and prevented cell leakage from the gel matrix.     

Trehalase activity and its regulation during growth of Saccharomyces cerevisiae.

Trehalase activity decreased in 95% at the onset of the transition phase of growth of S. cerevisiae. The question which we raised was whether this phenomenon was due to proteolysis or to conversion of the enzyme to a less active form (dephosphorylation). Immunological methods allowed to identify the presence of the trehalase protein during cell growth. At the same stage of growth, an increase in the non-phosphorylated enzyme was detected "in vitro". Results utilizing mutant strains also indicated that regulation occurred by interconversion of forms. The same mechanism also seems to control trehalase activity in non proliferating conditions.     

A new microtitration method for the enumeration of contagious bovine pleuropneumonia (CBPP) vaccines.

A new method is proposed for the microtitration of CBPP vaccines by performing eight parallel endpoint two-fold dilutions. When performed on a 96-well plate, it gives a titre with a precision of +/- 0.2 log10. By comparison, the established method, performed in tubes, gives a precision of only +/- 0.6 log10. The adaptation to microtitre plates allows much more economical culture of larger numbers of samples. Statistical analysis permits determination of vial-to-vial homogeneity of a batch and calculation of a titre with a precision of +/- 0.09 log10. The new method may be applied for the titration of mycoplasmas.     

Role of tissue hypoxia as the mechanism of lactic acidosis during E. coli endotoxemia.

We compared the hemodynamic and metabolic alterations produced in rabbits by similar decreases in cardiac output created by inflating a balloon placed in the right ventricle (n = 6) with those produced by an intravenous bolus of Escherichia coli lipopolysaccharide (LPS; SEP group; n = 6). We measured O2 consumption (VO2), O2 transport (TO2), and O2 extraction ratio (ERO2) for the whole animal and also for the left hindlimb. Both groups experienced similar decreases in cardiac output, systemic TO2, and VO2 and similar increases in ERO2. For the hindlimb, TO2 was similar, but VO2 and ERO2 were lower for the SEP group 30 min after LPS administration (P less than 0.05); however, this difference disappeared during the remainder of the experiment. Arterial lactate concentration was greater (P less than 0.05) for the SEP group. There were no differences in skeletal muscle PO2, measured with a multiwire surface electrode, or in cardiac and skeletal muscle concentrations of high-energy phosphates. We hypothesize that a direct effect of LPS on cellular metabolism may have resulted in greater arterial lactate concentration for the SEP group.     

Actin organization and fibrin-clot retractile activity of cultured mouse fibroblasts

Summary It is known that human and animal fibroblasts are able to induce the retraction of a fibrin clot. In the present study the correlation between (i) fibrinclot retractile (FCR) activity, (ii) the number of actin stress-lines in mouse fibroblasts during growth in culture, and (iii) the sensitivity of actin stress-lines to a powerful actin-depolymerizing factor (ADF), present in plasma and serum of humans and laboratory animals was investigated. Fibroblasts at early passages (2–4) were tested for these parameters at various intervals after seeding (24, 96, and 168 h). The number of actin stress-lines was progressively higher, while the sensitivity to ADF action was progressively lower in cells cultured from 24 to 168 h; the FCR capacity was significantly decreased at 168 h. These data suggest that cells containing weakly polymerized and/or stabilized actin are more active than those containing highly polymerized and/or stabilized actin in triggering fibroblast contraction.     

Age-dependent population diffusion with external constraint

We present a simple model for age dependent population diffusion when the dynamics is submitted to external constraints. Existence, uniqueness and dependence on the parameters of the solution are discussed.This work has been done within the framework of the cultural agreement between the Universities of Bordeaux and Rome     

The Roberts syndrome

Summary Four siblings with the autosomal recessive Roberts syndrome are reported, and we discuss the phenotypic overlap of this syndrome with other similar radial, aplasia syndromes.     

Fast atom bombardment: A new mass spectrometric method for peptide sequence analysis

We have studied a selection of peptides using a new mass spectrometric ionisation technique - fast atom bombardment (FAB). We define the fragmentation pathways observed and comment on the utility in sequence analysis. A simple acetylation experiment is shown to aid rapid sequence assignment.     

Activation of old cuticle chitin as a substrate for chitinase in the molt of Manduca

During the molt, chitin in the old cuticle of $\text{Manduca}$ is digested by chitinase taken up from molting fluid, but the chitin in intact (= premolt) cuticle is not accessible to chitinase. As a prerequisite of digestion, old cuticle chitin is rendered competent to serve as chitinase substrate in a reaction attributable to trypsin-like proteolytic activity of molting fluid.     

Induced azygospore formation in Mucor (Rhizomucor) pusillus by Absidia corymbifera

Attempts to determine the mating reaction type of heterothallic strains of Mucor pusillus in interspecific contrasts with Mucor strains of known mating reaction type were unsuccessful. Contrasts with Absidia corymbifera strains resulted in the production of azygospores in Mucor pusillus.