Photoregulation of some enzymes from Neurospora crassa

Light-grown cultures of Neurospora crassa showed photoregulation of a number of enzymes. Proteases and cytosolic malate dehydrogenase showed an increase in activity. There was a decrease in the activity of mitochondrial malate dehydrogenase, isocitrate dehydrogenase and cytosolic glucose-6P-dehydrogenase, isocitrate dehydrogenase and isocitrate lyase.     

Effect of the scorpion,Heterometrus fulvipes (C. Koch), venom on some enzyme systems in rat (albino) tissues

Summary Sublethal doses ofHeterometrus fulvipes venom decreased NADP-specific isocitrate dehydrogenase and malate dehydrogenase activity levels and increased NADP-specific glucose-6-phosphate dehydrogenase and alkaline phosphatase activity levels during a 48-h-period.Acknowledgments. D. V. thanks the Council of Scientific and Industrial Research, New Delhi, for awarding a Senior Research fellowship.     

Phosphate mediated regulation of some of the enzymes of carbohydrate metabolism inNeurospora crassa

Summary The levels of FDP aldolase, isocitrate lyase, isocitrate dehydrogenase, malate dehydrogenase and glucose-6-P dehydrogenase were found to be rugulated by inorganic phosphate in the growth medium. The possible regulatory aspects have been discussed.     

Genetic control of malate dehydrogenase inNicotiana suaveolens andN. glutinosa

Summary The study of malate dehydrogenase patterns in leaves ofNicotiana suaveolens, N. glutinosa and their interspecific hybrid has been carried out, in order to propose a model of its genetic control. Two possible explanations for the genetic control of malate dehydrogenase have been postulated forN. suaveolens, and at least two loci appear to be implicated in the control of this system inN. glutinosa.Acknowledgments. The authors thank Dr M. Pérez de la Vega for his valuable advice.     

Rhythmic variations in the activities of aldolase and isocitrate dehydrogenase in the heart muscle of the scorpion,Heterometrus fulvipes (C. Koch)

Summary The activity levels of aldolase and isocitrate dehydrogenase were assayed in the heart muscle of scorpion,Heterometrus fulvipes. The enzyme activities showed a circadian rhythmicity with a peak value at 20.00 h in the heart muscle.     

Loss of cytosolic serine hydroxymethyltransferase in a formate mutant ofNeurospora crassa

Summary In the wild type ofNeurospora crassa serine hydroxymethyltransferase occurs in the cytosol and mitochondria. The formate mutant (FGSC 9) lacks the cytosolic activity but has increased levels of isocitrate lyase and glyoxylate aminotransferase. Glycine is derived from glyoxylate in the mutant.     

Rhythmic variations in the isocitrate dehydrogenase activity in the scorpion,Heterometrus fulvipes (C. Koch)

Summary The activity of isocitrate dehydrogenase was assayed in the pedipalpal muscle and hepatopancreas of scorption, Heterometrus fulvipes. The enzyme activity showed a circadian rhythmicity with a peak value at 20.00 h in both the tissues.     

Acetaldehyde oxidation inDrosophila null-mutants for alcohol dehydrogenase

Summary Aldehyde dehydrogenase (ALDH) activity is demonstrated in four strains ofD. melanogaster lacking active alcohol dehydrogenase (ADH-null mutants). In the four strains, ALDH activities are similar to those found in a wild strain. It is concluded that ADH-null flies are able to detoxify acetaldehyde. This finding is discussed in relation with the dual function of ADH proposed recently.This work was supported by a grant from the Medical Research Council of Canada (MRC 6920) to Dr F. Garcin.     

Physiological studies on the effects of nutritional imbalance on the central nervous system. II. Effects of thiamine deficiency on oxidative enzymes in the brain of chicken,Gallus domesticus

Summary The activity levels of succinate dehydrogenase, glutamate dehydrogenase and pyruvate dehydrogenase in the fore, mid and hind brain regions of the thiamine deficient chicken,Gallus domesticus were determined. The activity levels of scccinate dehydrogenase and glutamate dehydrogenase in all the 3 regions of brain showed augmentation on inducing thiamine deficiency. In contrast the activity levels of pyruvate dehydrogenase decreased in the brain of thiamine deficient animals. It is suggested that these changes in the oxidative enzymes indicate disturbance caused in the operation of the tricarboxylic acid cycle in thiamine deficiency.     

Enzymatic processing of pheromones and pheromone analogs

Summary Pheromone perception requires rapid enzymatic degradation of the active chemical signal in the sensory hairs. Three insects are used to illustrate chemical approaches to studying the degradation of pheromones by antennal enzymes. First, hydrolysis of acetate and haloacetate esters is examined in the diamondback moth,Plutella xylostella. Second, aldehyde oxidation and the selective inhibition of the oxidase and dehydrogenase activities are described for the tobacco budworm moth,Heliothis virescens. Finally, a stereochemical analysis of the epoxide-hydrase catalyzed addition of a water molecule to the oxirane ring of disparlure is described for the gypsy moth,Lymantria dispar.     

Unique evolution of Bivalvia arginine kinases

The clams Pseudocardium, Solen, Corbicula and Ensis possess a unique form of arginine kinase (AK) with a molecular mass of 80 kDa and an unusual two-domain structure, a result of gene duplication and subsequent fusion. These AKs also lack two functionally important amino acid residues, Asp⁶² and Arg¹⁹³, which are strictly conserved in other 40-kDa AKs and are assumed to be key residues for stabilizing the substrate-bound structure. However, these AKs show higher enzyme activity. The cDNA-derived amino acid sequences of 40-kDa AKs from the blood clam Scapharca broughtonii and the oyster Crassostrea gigas were determined. While Asp⁶² and Arg¹⁹³ are conserved in Scapharca AK, these two key residues are replaced by Asn and Lys, respectively, in Crassostrea AK. The native enzyme from Crassostrea and both of the recombinant enzymes show an enzyme activity similar to that of two-domain clam AKs and at least twofold higher than that of other molluskan AKs. Although the replacement of Asp⁶² or Arg¹⁹³ by Gly in normal AK causes a considerable decrease in V_max (6–15% of wild-type enzyme) and a two- to threefold increase in K_m for arginine, the same replacement in Scapharca AK had no pronounced effect on enzyme activity. Together with the observation that bivalve AKs are phylogenetically distinct from other molluskan AKs, these results suggest that bivalve AKs have undergone a unique molecular evolution; the characteristic stabilizing function of residues 62 and 193 has been lost and, consequently, the enzyme shows higher activity than normal.Received 14 October 2003; accepted 1 November 2003     

Relationship of prodigiosin condensing enzyme activity to the biosynthesis of prodigiosin and its precursors inSerratia marcescens

Summary Prodigiosin condensing enzyme (PCE) activities were present inSerratia marcescens wild type 08, mutants OF, WF and 9-3-3. Their specific activities exhibited different maxima and at different times during the late log phase or the early stationary phase of cell growth. The levels of prodigiosin and its precursors also showed a significant increase at this period. The results support that prodigiosin and/or its precursors are secondary metabolites. The ubiquity of the PCE activity in mutants deficient in prodigiosin biosynthesis suggest that this particular enzyme may also be present in non-pigmented clinical isolates.     

Dominance for enzyme activity inDrosophila melanogaster

Summary A regulatory element tightly linked to theGpdh locus inDrosophila melanogaster has been isolated from a natural population. Flies homozygous for second chromosomes bearing the element,H31, have half the GPDH activity of normal homozygotes. Heterozygotes betweenH31 andF orS alleles exhibit dominance in GPDH activity. Heterozygotes betweenH31, F orS andDf(2L) GdhA have half the diploid level. The contribution of theS allele to the activity inS/H31 heterozygotes is more than four times that ofH31. The regulatory element distinguishingH31 is tightly linked to theGpdh ⁺ locus.     

Sperm enzyme activity analysis in individual sperm for detection of heritable mutations in mammals

Summary Male mice were injected i.p. with 2.5 mg/kg mitomycin C, 100 mg/kg ethyl nitrosourea or saline and mated with untreated virgin females five weeks later. Sperm from 64 of the F₁ male progeny were analyzed histochemically for acrosin, succinic dehydrogenase and alpha-glycerophosphate dehydrogenase activity. The frequency of F₁ males with sub-normal sperm enzyme activity was significantly higher among progeny from treated males than in controls. These results show that analysis of sperm enzyme activity in F₁ males is a practical method for detection of transmitted mutations induced in a treated parent.We gratefully acknowledge USPHS, NIEHS grant 1 RO1 ES02607-02 and technical assistance by G. M. Oldford.     

Ethanol metabolizing system inDrosophila melanogaster: subcellular distribution of some main enzymes

Summary The subcellular distribution of some enzymes which play a part in ethanol metabolism have been determined by differential centrifugation of homogenates of adultD. melanogaster flies of various genotypes. Aldehyde dehydrogenase, recently discovered inD. melanogaster, is present in the five genotypes studied. It has been found however to be, in vitro at least, most active in a strain lacking both alcohol dehydrogenase and aldehyde oxidase.     

Biochemical polymorphism of Japanese quail (Coturnix coturnix japonica): comparison of functionally different proteins (author's transl)]

The polymorphism observed among the enzymes involved in the respiratory metabolism (lactate dehydrogenase, malate dehydrogenase, phosphoglucomutase, phosphohexoseisomerase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase fructose 1-6 diphosphate dehydrogenase) is less important than that of the enzymes physiologically less essential, such as the various esterases, the alkaline phosphatase, the alcohol dehydrogenase, and of the non-enzymatic proteins (ovalbumin, ovoglobulins, ovomucoid, conalbumin, transferrin, etc.).     

Drosophila melanogaster aldehyde dehydrogenase

Summary Subcellular fractionation by differential centrifugation confirms the presence of aldehyde dehydrogenase inD. melanogaster. It is found principally in the heavy mitochondrial fraction.     

Aldolase and dehydrogenase activities inSpirillum bengal

Summary Spirillum bengal is unable to grow on sugars, but can utilize different organic acids as carbon sources. Dehydrogenase activities were tested with different substrates and were found highest with lactate, glutamate, acetate, succinate and malate. A low aldolase activity was also detectable.     

Localization of pyruvate carboxylase in the cells ofNeurospora crassa

Summary The cell wall ofNeurospora crassa was digested enzymatically and the cytosolic and the mitochondrial fractions were separated. The activity of pyruvate carboxylase (EC 6.4.1.1) was detected entirely in the cytosolic fraction. This indicates that the location of pyruvate carboxylase ofN. crassa is in the cytosol, but is not in the mitochondria; this is different from the situation in animal tissues.     

Ethanol as a ‘food’ forDrosophila melanogaster: Influence of theEbony gene

Summary The survival time of adultDrosophila melanogaster flies without food is greater in the presence of ethanol, especially for flies of strains or lines with a higher alcohol dehydrogenase activity. It seems that theebony gene can act in some populations as a selective factor favoring the ADH^F allele, as well as the minor genes enhancing the alcohol dehydrogenase activity level.Chargé de Recherches au F. N. R. S.