Mise en evidence de l'existence de sensilles chemorecepteurs sur les antennes d'un crustace mysidace cavernicole et de l'intervention de ces sensilles dans la detection d'un extrait de nourriture

The cavernicolous crustacean Antromysis juberthiei showed unexpected behavior when presented with food extract : it avoids the area of odor inflow. This avoidance reaction is reduced by removal of various combinations of antennae and disappears almost with bilateral removal of the first antennae (the aesthetasc-bearing antennules).     

Screening method for microorganisms producing L-aminoacids from D,L-5-monosubstituted hydantoins

Summary The ability of microorganisms to produce hydantoinase and L-N-carbamoylase could be established by an overlay assay. Enzyme producing strains form clear areas around their colonies caused by the cleavage of D,L-indolylmethylhydantoin. A second overlayer with a tryptophan-auxotroph yeast enables us to detect microorganisms which are able to produce L-tryptophan from D,L-indolylmethylhydantoin.     

Comparative study of aflatoxins M1 and B1 production in solid-state and shaking liquid cultures

Production of aflatoxins M1 (AFM) and B1 (AFB) by Aspergillus flavus NRRL 3251 in solid-state and shaking liquid cultures using rice as the carbon source was compared. In general, solid-state cultures produced more aflatoxins than shaking liquid cultures on an equal rice weight basis. Solid-state cultures with continuous shaking yielded higher levels of toxins than those with intermittent shaking. However, intermittent shaking is a feasible replacement for the continuous shaking method for AFM production. A typical solid rice culture supplemented with yeast extract produced 30 and 2600 mg per kg rice of AFM and AFB, respectively, in 8 days at 29 degrees C. The optimal culture conditions for toxin production in a shaking liquid culture were also studied. Parameters under consideration included the amount of carbon (rice) and nitrogen source, initial medium pH, and aeration rate. At optimum conditions, a representative shaking liquid culture produced 18 and 1680 mg per kg rice of AFM and AFB, respectively, in 5 days at 29 degrees C. This shaking liquid culture appears feasible for scaling up and routine production of AFM and AFB for toxicological investigations.     

An optical method for the determination of the isotopic composition of 1H2O/2H2O mixtures: Eu3+ luminescence lifetimes

A spectroscopic method employing pulsed dye laser instrumentation is described for the determination of the 1H2O/2H2O composition of aqueous solutions by the measurement of reciprocal excited state lifetimes of EuEDTA-. The reciprocal lifetimes, gamma-1, of the 1H2O/2H2O mixtures increase linearly with the mole fraction of 1H2O. For EuEDTA- the relationship between gamma-1 and the mole fraction, chi H, of 1H2O in 1H2O/2H2O mixtures is expressed by the equation chi H = 0.37 gamma-1-0.152, with a sensitivity in chi H of +/- 0.02. The reciprocal lifetimes are independent of pH in the range 5.1 to 10.5, changes in ionic strength, and the type of buffer used in EuEDTA- containing solutions.