Acetaldehyde utilization and toxicity in Drosophila adults lacking alcohol dehydrogenase or aldehyde oxidase.

Metabolic utilization and toxicity of acetaldehyde were studied in flies lacking alcohol dehydrogenase (ADH), aldehyde oxidase (AO), or both functions. Prior to the experiments, mutant alleles Adhn4 and mal were transferred to the same genetic background by 10 successive backcrosses. By comparison with wild-type flies, various deleterious, pleiotropic effects could be attributed to the mal allele but not to Adhn4. Of the four genotypes studied (mal, Adhn4, mal Adhn4, and wild), all were able to use acetaldehyde as a resource in a similar way. In spite of its high toxicity, acetaldehyde appeared a better resource than ethanol. Flies treated with intermediate acetaldehyde concentrations (around 0.5%) exhibited a very high interindividual heterogeneity which could reflect a physiological adaptation occurring as a consequence of the aldehyde treatment. Toxicity tests showed that ADH-negative flies were more sensitive to acetaldehyde than wild type, but this is most likely explained by the transformation of the aldehyde into alcohol. Our results show that the aldehyde metabolizing enzyme (AME) system in Drosophila is neither ADH nor AO. The existence of an aldehyde dehydrogenase is plausible.

Alcohol tolerance and alcohol utilisation in Drosophila: partial independence of two adaptive traits.

Three natural populations of D. melanogaster with different ethanol tolerance, and a population of D. simulans were successfully selected for an increased capacity to withstand alcohol. Alcohol utilisation, measured by the increase of life duration in the presence of low concentrations of alcohol, was clearly improved only in two cases. Alcohol tolerance and utilisation, two physiological traits that both depend on the presence of an active ADH, are thus controlled, at least partly, by different genetic mechanisms. In Drosophila species breeding on fermenting fruits or in wine cellars, both traits may be under the control of natural selection.

[Utilization of casein by adult drosophila : role of ethanol and a non-metabolizable phagostimulant]. / Utilisation de la caséine par les drosophiles adultes : rôle de l'éthanol et d'un phagostimulant non métabolisable.

Given alone to Drosophila adults, casein is almost not used because it is not ingested. L arabinose, which is a powerful phagostimulant allows a convenient utilisation of casein, resulting in an increase of life duration and egg production. The utilisation is still improved when a small amount of alcohol is added. Ethanol acts both as an energy source and as a phagostimulant.

Drosophila alcohol dehydrogenase activity in vitro and in vivo: effects of acetone feeding.

When adult Drosophila are placed on medium containing 0.5% acetone, their level of alcohol dehydrogenase activity drops rapidly. At the same time, the proportion of activity in the various electrophoretic forms of the enzyme shifts; most of the activity becomes localized in what is ordinarily a minor form of the enzyme. Moreover, the loss of enzyme activity occurs in vivo as well, as shown by sensitivity to ethanol poisoning, insensitivity to pentenol treatment, and inability to utilize ethanol as an energy source. These observations are discussed in light of a model advanced for the origin of the multiple forms of alcohol dehydrogenase in Drosophila.

Alcohol metabolism in Drosophila melanogaster: uselessness of the most active aldehyde oxidase produced by the aldox locus.

Alcohol dehydrogenase is necessary for ethanol detoxification and metabolic utilization. It has been generally assumed that aldehyde oxidase (AO) produced by the Aldox locus (3-56.7) is necessary for a further transformation of acetaldehyde into acetate. We find that various mutant strains (ma-l or Aldoxn) which do not produce an active enzyme show about the same tolerance to alcohol as do wild strains. This physiological paradox is probably to be explained by the discovery of another locus (not localized) which produced a small amount of AO in all tested strains. The adaptive significance of the genetically polymorphic Aldox locus is probably to be looked for in physiological pathways other than ethanol metabolism.

[Nutritional needs of adult Drosophila: influence of lecithins and of choline chloride on the fecundity, the fertility and the size of ova]. / Besoins nutritionnels de la Drosophile adulte: influence des lécithines et du chlorure de choline sur la fécondité, la fertilité et la taille des oeufs

The lecithin or choline chloride deficiency, in Drosophila, results in an important decrease of the number of eggs produced, hatching and egg size. However, the ovogenesis is not completely stopped, even after 15 days. This effects seem caused by the choline deficiency. When used under the chloride form, choline has no toxic effect even at a rate as high as 3 g/litre. However, the lecithin has toxic effects for amounts up to 4 g/litre. In the adults, the optimal concentration could be about 2 g/litre for the lecithin and 300 mg/litre for the cholin chloride.