Genetic variation of aldehyde dehydrogenase in primates.

Genetic variation of aldehyde dehydrogenase has been demonstrated in catarrhine primates. The results are in accordance with the formal genetic interpretation: three alleles, AldDH1, AldDH2, AldDH3, at the gene locus AldDH. Obviously, the allele AldDH1 has undergone fixation in Homo and Hylobates, the allele AldDH2 in Macaca and Papio, and the allele AldDH3 in Cercopithecus.     

Alcohol dehydrogenase in the mouse epididymis. Genetic variation and cellular localization

The cellular localization of alcohol dehydrogenase (ADH) in the mouse epididymis was investigated using differential substrate specificities and genetic variation as a means of distinguishing these enzymes histochemically in tissue sections. ADH-C2 exhibited high activity in BALB/c epididymis and was observed as a discrete zone within duct epithelial cells near the nuclei. This isozyme exhibited no detectable activity in C57BL/6J epididymis extracts or histochemical sections.     

Human mitochondrial NADP-dependent isocitrate dehydrogenase in man-mouse somatic cell hybrids.

Human mitochondrial NADP-dependent isocitrate dehydrogenase (IDH-2) is expressed in man-mouse somatic cell hybrids as a dimeric molecule. The gene specifing this enzyme was observed to be syntenic with the mannose phosphate isomerase locus in the 56 primary man-mouse clones in this series. The human IDH-2 locus, therefore, may be assigned to chromosome 15.     

The soluble citric acid cycle enzymes ofDrosophila melanogaster. II. Tissue and intracellular distribution of aconitase and NADP-dependent isocitrate dehydrogenase

Aconitase (aconitate hydratase) (AH) and NADP-dependent isocitrate dehydrogenase (IDH-NADP) are found in every larval and adultDrosophila tissue. Their specific activities as well as the ratios of their absolute activities differ significantly from tissue to tissue. There are tissue-specific differences in the pattern of IDH-NADP isozymes in adults and in larvae. No clear-cut tissuespecific patterns exist for AH isozymes. Most of the activity of both enzymes is found in the supernatant fraction of whole fly homogenates. Only 35% of the AH activity and 16% of the IDH-NADP activity are associated with mitochondria. The patterns of supernatant and mitochondrial IDH-NADP isozymes are the same. On the other hand, the supernatant possesses AH isozymes not found in the mitochondria.     

Genetic control of soluble NDA-dependent sorbitol dehydrogenase in Drosophila melanogaster

Experiments utilizing standard techniques of cell fractionation and disc electrophoresis have revealed the presence of three distinctly different enzymes which catalyze the oxidation of d-sorbitol in crude extracts of Drosophila melanogaster adults. These include (1) a soluble NAD-dependent sorbitol dehydrogenase (NAD-SoDH^s), (2) a mitochondrial NAD-dependent sorbitol dehydrogenase (NAD-SoDH^m), and (3) a soluble NADP-dependent sorbitol dehydrogenase (NADP-SoDH). The structural gene for NAD-SoDH^s has been mapped to a locus between 65.3 and 65.6 on the third chromosome by means of an electrophoretic variant and a low-activity allele. Through the use of segmental aneuploidy, this gene has been localized to the region limited by salivary bands 91B–93F. Because mutants which alter either the activity or electrophoretic mobility of the soluble NAD-dependent enzyme have no significant measurable effect on the mitochondrial or NADP-dependent forms, it is suggested that the enzymes in this system are coded for autonomously by different genes.     

NADP regulates the light activation of NADP-dependent malate dehydrogenase

The chloroplastic NADP-dependent malate-dehydrogenase (EC 1.1.1.82) activity is modulated by light and dark. The enzyme is activated upon illumination of intact or broken chloroplasts or by incubation with dithiothreitol, whereas dark has the opposite effect. The present communication shows an additional regulation of the light modulation: in isolated intact pea chloroplasts, light activation was inhibited in the presence of electron acceptors such as sodium bicarbonate, 3-phosphoglycerate or oxaloacetate, which consume NADPH₂ and produce NADP. With broken chloroplasts, addition of NADP resulted in a pronounced lag phase of NADP-dependent malate dehydrogenase light activation, while NADPH₂ was without any effect. The extent of the lag phase was correlated to the amount of NADP added. When light was replaced by dithiotreitol, the inhibition effect was even more pronounced. It was assumed that NADP inhibits the modulation reaction directly: reduced thioredoxin, a potent mediator of activation by light, or dithiotreitol appear to counteract NADP in a competitive manner. The results indicate a physiological role of NADP in the regulation of chloroplastic NADP-dependent malate dehydrogenase which is capable of removing electrons from the chloroplast, via oxaloacetate reduction and malate export. Thus an NADP concentration sufficient for continuous photosynthetic electron flow may be achieved.     

Genetic variants of soluble malate dehydrogenase in new guinea populations

Summary 10 cases of an S-MDH variant have been detected in New Guinea. 3 cases were found among 199 samples from the Fore linguistic group and 6 cases among 9 related members of a family from the Agarabi linguistic group, both groups being located in the Eastern Highlands. 1 case was found in 24 samples from the Sepik district. The new variant has been given the trivial name S-MDH New Guinea-1.