Ann L. Koen

Retinol and alcohol dehydrogenases in retina and liver

Abstract Isozymes of alcohol dehydrogenase (alcohol: NAD + oxidoreductase, EC 1.1.1.1) and retinol (vitamin A 1 ) dehydrogenase (retinol: NAD + oxidoreductase) were studied in retina and liver extracts of rat by starch-gel electrophoresis. The retina demonstrated two zones of retinol dehydrogenase activity and a separate zone of alcohol dehydrogenase activity. The liver had single zones each of retinol and alcohol dehydrogenase activity, neither of which coincided with the three zones from the retina. It is concluded on the basis of the electrophoretic findings supplemented with inhibition, heat inactivation, and pH studies that these five zones represent five different enzymes, and that vitamin A is oxidized in the retina and the liver by specific and distinct enzymes. Liver-type alcohol dehydrogenase is absent from the eyes and eye-type is absent from the liver.

GLUCOSE 6-PHOSPHATE DEHYDROGENASE AND HEXOSE 6-PHOSPHATE DEHYDROGENASE OF MAMMALIAN TISSUES*

Glucose 6-phosphate dehydrogenase (GGPD) is among the most thoroughly studied of the enzymes. I t has been of particular interest to geneticists because it is controlled in man by a gene located on the X-chromosome. Genetic variants in man thus have been very useful markers in studies of the X-inactivation hypothesis (Lyon hypothesis), which states that in the human female, which has two X-chromosomes in each somatic cell, only one of the X-chromosomes is active; the other is in an inactive state. Studies of the G6PD locus have generally confirmed this hypothesis, particularly the demonstration (Davidson et al., 1963) that clones of cells cultured from skin of Negro females heterozygous for a G6PD variant carried either one or the other form of the enzyme, but not both. GGPD, more recently, has been shown to be X-linked also in equine species (Mathai et al., 1966) and in Dmsophila (Young et al., 1964), findings which have led to the speculation that there may be some general advantage in having this enzyme controlled by the X-chromosome. Thus, it was of particular interest when we found a G6PD in the deer mouse, Peromyscus maniculatus, which is autosomally controlled (Shaw & Barto, 1965). However, as noted in our initial report, this enzyme is probably not homologous with the Xlinked enzyme of human erythrocytes. There are two different forms of G6PD in deer mouse tissues, which were arbitrarily designated the A and B forms. The B form is the autosomally controlled type, and does not occur in deer mouse erythrocytes. The A form, which was found in all tissues studied including erythrocytes, was postulated to be homologous with the G6PD of human erythrocytes. Subsequent study has amply confirmed this impression, and the evidences will be reviewed here. A second form of G6PD also was found subsequently in human tissues (Shaw, 1966; Ohno et al., 1966), and this appears to be homologous with the B enzyme of deer mouse. The evidences for this homology will be presented, together with studies of other mammals which indicate that both homologies are rather general throughout the mammalian order, with one interesting exception.

Aconitate hydratase isozymes: subcellular location, tissue distribution and possible subunit structure.

Abstract Aconitate hydratase (citrate (isocitrate) hydro-lyase, EC 4.2.1.3) has been separated into two subcellular forms, cytoplasmic and mitochondrial. Tissue distribution of these two forms was investigated in mouse and Slow loris; spleen contains predominantly the cytoplasmic form, muscle the mitochondrial form, and other tissues varying proportions of each. Variation of the cytoplasmic isozyme was observed among Slow lorises; the patterns indicate that the subunit structure is either monomeric or polymeric without cross-association between the subunits.

MOLECULAR SYSTEMATICS AND CLINAL VARIATION IN MACAQUES

ABSTRACT . Gene frequency data were gathered on seven genetic loci from 17 populations of ten species of macaques from known geographic areas. The data were analyzed via two computer methods, each generating dendrograms depicting phylogenetic relationships. These relationships are discussed in terms of the traditional taxonomy of macaques. M. fasciculariS, M. mulatta, M. Cyctopis and M. fuscata form a closely related assemblage. M. speeiosa , the Celebes and pig-tailed macaques are the most divergent groups. The Celebes populations are joined together and form an assemblage with the M. nemestrina groups, a geographically reasonable union. Clinal patterns of genetic variation suggest the operation of natural selection.

Effect of Chelation on Phosphorus Metabolism in Experimental Atherosclerosis

MgNa2EDTA is shown to have an ameliorating effect of fat-induced atherosclerosis in rabbits. The compound was shown to decrease not only the general extent of atheromatosis, but to influence phosphate metabolism in induced atherosclerosis. Some credence is lent to a previously outlined hypothesis suggesting that the parathyroids mediate this effect.

Some in vivo effects of chelation. II. Animal experimentation.

Abstract In vivo effects of EDTA on a number of elements including potassium, sodium, calcium, copper, manganese, sulfur (as sulfate) and phosphorus are reviewed. Data are presented to show that EDTA given to rabbits after cessation of an atherogenic diet greatly accelerates the natural rate of plaque removal from aortas. An effect on phosphate metabolism was also demonstrated particularly on the aortic phospholipids and residue phosphate (obtained after extraction of the phospholipids and the acid soluble phosphorus).

A tissue-specific shift in lactate dehydrogenase sub-band patterns of the house mouse

Abstract 1. 1.Lactate dehydrogenase ( l -lactate:NAD oxidoreductase, EC 1.1.1.27) from tissues of the house mouse was separated into multiple bands and sub-bands by starch-gel electrophoresis. Sub-band patterns of kidney and lung differ from each other in fresh extracts, the lung sub-bands migrating faster than kidney ones. These patterns remain constant throughout an aging period of 8 days. Muscle and liver sub-bands undergo a shift in distribution from cathodal to anodal type as extracts age. This shift terminates in a pattern very similar to fresh lung pattern. It was concluded that the shift in pattern of muscle and liver was due to non-random conformational changes in sub-band molecules, and further that a macromolecular factor present in house-mouse kidney stabilizes the more cathodal sub-band forms. This factor is probably absent or partially absent from other tissues. Tissues from other animals do not exhibit this sub-band shift. 2. 2.Substrates and coenzymes were tested for their effects on the enzyme. Lactate, pyruvate, NAD + and NADH were found to have adverse effects at higher concentrations, while at physiological concentrations, NAD + and NADH had no effect.

Lactate dehydrogenase isozyme sub-bands: New bands derived from isolated sub-bands

Abstract Lactate dehydrogenase ( l -lactate:NAD oxidoreductase, EC 1.1.1.27) isozyme 5 from ICR mouse tissues was separated by starch-gel electrophoresis into multiple zones, or sub-bands. When individual sub-bands were removed from the gel by electrodialysis and re-run in another gel under identical conditions, other new bands occurred in addition to the original one. The new bands, called Z bands, appeared at some distance toward the anode, near the position of lactate dehydrogenase 4. Each of these occupied a characteristic position depending upon which sub-band of lactate dehydrogenase 5 gave rise to it. The differences in mobility between the Z bands were one-half those between the sub-bands of lactate dehydrogenase 5.

RELATIVE SIGNIFICANCE OF ISOZYMES, CONTROL GENES, AND CHROMOSOMES IN GRADE EVOLUTION

ABSTRACT . Some of the results of isozymic analysis of primates are not adequately explained by theories of cladogenetic evolution. A combination of the cladogenetic theories, with some modifications, and with incorporation of recent chromosome data led to the formulation of a theory of grade or anagenetic evolution. Control genes in the form of centromeric heterochromatin may have been agglutinating at the centromeres of certain chromosomes throughout primate evolution. Extrapolation of this theory may help to explain such results as progressive, directional changes in isozyme ratios and appearance of isozymes in one species which properly belong to other species that separate later from the primate line.