6-phosphogluconate dehydrogenase in the housefly,Musca domestica L.: Evidence for inheritable 6PGD polymorphism

Two electrophoretic variants of the 6-phosphogluconate dehydrogenase (6 PGD) enzyme have been found in the WHO/IN/Musca domestica/l housefly laboratory strain. The patterns shown by Cellogel zone electrophoresis can be fully explained by the hypothesis of two codominant autosomal alleles. On this hypothesis, a specific Pgd locus has been postulated and the symbols PgdA and PgdB have been assigned to the two alleles causing the PGD-A and PGD-B phenotypes. The bands corresponding to the homozygous phenotypes PGD-A and PGD-B have different electrophoretic mobility and staining intensity; they can be described, respectively, as "fast-weak" and "slow-thick." The heterozygous phenotype PGD-AB gives a three-banded pattern, indicative of a dimeric structure for this enzyme; this pattern is asymmetrical. Heterozygous flies have been found both among wild-type strains of recent colonization and among old established laboratory colonies. Most strains are PgdB monomorphic; up to now only three strains have been PgdA monomorphic, all of them being multimarker strains. The Pgd locus has been traced to the housefly linkage group III.     

Starch-gel electrophoretic variants of erythrocyte 6-phosphogluconate dehydrogenase in asian macaques

Five alleles with eight electrophoretic phenotypes of 6-phosphogluconate dehydrogenase were found in 1,195 blood samples from fourteen populations of nine macaque species.Macaca fascicularis from Malaya showed the most polymorphism, with three Pgd alleles resulting in five phenotypes.Macaca mulatta, M. speciosa, M. nemestrina, andM. cyclopis had two alleles each (although the last two species showed a high percentage of homozygosity). The remaining four species (M. fuscata, M. radiata, M. maura, andM. nigra) were homozygous for the Pgd^a allele. The predominance of Pgd^a was observed in all macaque species, exceptM. speciosa which showed a high (57%) frequency of Pgd^d. The distinctive position ofM. speciosa with regard to 6PGD variants parallels observations that indicate that this species carries transferrin and carbonic anhydrase I alleles in different frequencies from those of the other macaque species. Other similarities between the patterns of transferrin and 6PGD variations include a tendency toward homozygosity at the Pgd locus in the insular macaque forms. However, in this case only the Pgd^a allele is involved, while some variation was found in the transferrin alleles fixed by the founder effect in the insular macaques.This research was supported by NSF grants GF 253, GB 7426, and GB 15060 of the U.S.-Japan Cooperative Science and Systematic Biology Programs.     

Glucose phosphate isomerase and 6-phosphogluconate dehydrogenase polymorphism in Malaysian leaf monkeys

Glucose phosphate isomerase and 6-phosphogluconate dehydrogenase were found to be polymorphic in Malaysian leaf monkeys. Two glucose phosphate isomerase electrophoretic phenotypes were presumed to be homozygous. Three 6-phosphogluconate alleles and four electrophoretic phenotypes were present. The allele frequencies inPresbytis obscura werePgd ^A=0.64,Pgd ^B=0.27 andPgd ^C=0.09. The frequencies of the 6-PGD phenotypes inP. obscura were not in accord with Hardy-Weinberg expectations. All the biochemical markers examined show identical electrophoretic patterns in the Malaysian leaf monkeys.     

Polymorphism at the G6pd and 6Pgd loci in Drosophila melanogaster. IV. Genetic factors modifying enzyme activity

Different homozygous lines of similar genotype with respect to G6pd and 6Pgd were shown to have different enzyme activities for G6PD and 6PGD. Crosses between high and low lines suggested that there were modifying genes present on the autosomes, while others were probably located on the X chromosome. Allelic variation within each electrophoretic class of G6pd and 6Pgd might, however, also have contributed to this variation. An experiment on adaptation to sodium octanoate demonstrated that in adapted flies selection for lower enzyme activity had occurred, which provided further evidence for the existence of genetic differences in activity. Furthermore, a strong positive correlation between the activities of G6PD and 6PGD was found for each genotype. Since no correlation was found between MDH and the two enzymes G6PD and 6PGD, it could be concluded that this correlation was probably rather specific for G6PD and 6PGD. Interaction between genotypes with respect to activity was also found. It was shown that the variation at 6Pgd influenced the activity of G6PD within a genotype. The data are discussed in relation to fitness differences presented in foregoing articles.     

Stage and organ specificity of the degree of variegation of the 6-phosphogluconate dehydrogenase gene in Drosophila melanogaster

Summary The effects of chromosomal rearrangements pn2, pn3, TE100 and TE101 on variegation of the gene Pgd, which controls the synthesis of 6-phosphogluconate dehydrogenase (PGD), were studied in Drosophila melanogaster. The electrophoretic patterns of PGD activity were first examined at different developmental stages. The degree of variegation of Pgd caused by pn2 and pn3 was higher in adult flies (the calculated percentage of cells with inactive Pgd was 70%–80%) as compared with larvae (about 50%). This difference can be explained by the tissue-specific mosaicism of Pgd expression; variegation was high in the neural ganglia, imaginal discs, and posterior gut but relatively low in the salivary glands, fat bodies and Malpighian tubes. In the case of TE100, neither tissue specificity, nor marked differences in the degree of variegation between larvae and adults were found. None of the rearrangements examined had an effect on the expression of Pgd in the ovary cells, but repression was seen in some cells of the male gonads. The data obtained suggest that the timing of clonal initiation is influenced by the rearrangements studied. The possible mechanisms preventing changes in the expression of the Pgd gene in the nurse cells caused by these rearrangements are discussed.     

PGD variants in several wild pig populations of East Asia

PGD (6-phosphogluconate dehydrogenase) gene frequencies were reported in wild pigs, Sus scrofa, of three subspecies, i.e. Japanese wild pig, S.s. leucomystax, Ryukyu wild pig, S.s. riukiuanus, and Formosan wild pig, S.s. taivanus. Five phenotypes (A, AB, B, AC' and C') were observed. The C' variant was found only in the S.s. leucomystax, and may be identical to PGD-C reported by Archibald & McTeir (1988). PGD-A was a common variant in all the species in the genus Sus including wild pig, Sus scrofa, Javan pig, Sus verrucosus, and Bearded pig, Sus barbatus, and predominated in the whole populations examined except some of those of the S.s. riukiuanus. This suggested that the PGDA appeared before the other two alleles (B and C') during the evolution of the genus Sus.     

Maternal effect for genes encoding 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase in Drosophila melanogaster

We studied the maternal effect for two enzymes of the pentose cycle, 6-phosphogluconate dehydrogenase (6PGD) and glucose-6-phosphate dehydrogenase (G6PD), using a genetic system based on the interaction of Pgd^? and Zw^? alleles, which inactivate 6PGD and G6PD, respectively. The presence and formation of the enzymes was investigated in those individuals that had not received the corresponding genes from the mother. We revealed maternal forms of the enzymes, detectable up to the pupal stage. The activities of “maternal” 6PGD and G6PD per individual increased 20-fold to 30-fold from the egg stage to the 3rd larval instar even in the absence of normal Pgd and Zw genes. Immunologic studies have shown that the increase in 6PGD activity is due to an accumulation of the maternal form of the enzyme molecules. We revealed a hybrid isozyme resulting from an aggregation of the subunits of isozymes controlled by the genes of the mother and embryo itself. These results indicate that the maternal effect in the case of 6PGD is due to a long-lived stable mRNA transmitted with the egg cytoplasm and translated during the development of Drosophila melanogaster.     

Investigations on the organization of genetic loci in Drosophila melanogaster: lethal mutations affecting 6-phosphogluconate dehydrogenase and their suppression.

Summary The molecular nature of lethal and semilethal mutations in the Pgd locus of D. melanogaster coding for 6-phosphogluconate dehydrogenase (6PGD) was studied. All the 11 mutations affect the structural gene of the Pgd locus: 3 semilethal mutations resulted in altered 6PGD molecules with decreased catalytic activities; the rest 8 lethals were null alleles characterized by mutant polypeptides capable of reacting with antisera against highly purified 6PGD.Null or low activity alleles for glucose-6-phosphate dehydrogenase induced by ethyl methanesulfonate were shown to be suppressors for the lethal mutations in the Pgd locus.A monocistronic type of organization of the Pgd locus is suggested taking into account the biochemical mechanism of suppression of the Pgd-lethals and their location in the structural gene coding for 6PGD.     

De Novo mutation-like events observed at the 6PGD locus of the Japanese quail,and the principle of polymorphism breeding more polymorphism

In our stock of Japanese quail, four alleles which specify electrophoretic variants A, B, C, and D of an enzyme, 6PGD, are maintained. Analysis of the progeny from a mating which should have produced only known types of heterozygotes enabled us to detect a great variety of mutation-like events which affected the germ cells of the parents. A total of 1011 progeny from 26 such matings were typed for their 6PGD phenotype. Eleven showed unexpected phenotypes, some of which were apparent products of deletions or duplications. Thus, it appeared that the spontaneous rate of occurrence of all the mutation-like events per 6PGD locus per generation approaches 1×10^–2 in Japanese quail. All 11 mutation-like events occurred in the heterozygous parents. Furthermore, 8 of the 11 parents were A/D heterozygotes. A and D show the greatest difference in their electrophoretic mobility, which suggests that two variant subunits differ by several amino acid substitutions rather than by a single amino acid substitution. Of the 11 unexpected progeny, three received new, hitherto nonexistent electrophoretic variants from one of the parents. Perhaps there is a principle that mutation-like events are more likely to occur in germ cells of the parent which is heterozygous for extremely different alleles. This would imply that the new electrophoretic variants presently observed were produced by intracistronic recombination.This work was supported in part by a grant (CA 05138) from the National Cancer Institute, U.S. Public Health Service.     

Dosage compensation of sex-linked genes in Drosophila melanogaster. The activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in flies with normal and disturbed genetic balance

Summary The phenomenon of dosage compensation in Drosophila melanogaster which consists in doubling of the activity of the X-chromosome genes in males as compared to those in females was studied.The specific activities of 6-phosphogluconate dehydrogenase (6PGD) and glucose-6-phosphate dehydrogenase (G6PD) determined by the sex-linked structural genes Pgd and Zw respectively were studied in flies carrying duplications for different regions of the X-chromosome. The increase in dose of Pgd and Zw in females resulting from the addition of an extra X-chromosome or X-fragments leads to a proportional rise in the specific activities of 6PGD and G6PD. On the other had the addition to females of the X-chromosome carrying no Pgd gene or X-fragments lacking Pgd and Zw has no effect on the enzyme activities. Thus we failed to reveal in the X-chromosome any compensatory genes envisaged by Muller, which would repress sex-linked structural genes proportional to their dose.The 6PGD and G6PD levels in phenotypically male-like intersexes carrying two X-chromosomes and three autosome sets (2X3A) is 30% higher than in diploid (2X2A) or triploid (3X3A) females. However the specific activities of the enzymes in female-like intersexes are the same as in regular females. The levels of 6PGD and G6PD per one X-chromosome are 1.5–2.0 times higher in the intersexes than in the normal females and metafemales (3X2A). The results indicate that the level of expression of the X-chromosome is determined by the X:A ratio. It is suggested that the decreased X:A ratio in males is responsible for the hyperactivation of their X-chromosomes.     

Variability of Alcohol Dehydrogenase Activity in a Natural Population of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

MANY natural populations of Drosophila melanogaster are polymorphic for genetically determined electrophoretic variants of the enzyme alcohol dehydrogenase (ADH). Two alleles have been found, ADH-S (the slow variant) and ADH-F (the fast variant)¹ and crude extracts of ADH-F homozygotes typically have a higher enzyme activity than extracts from ADH-S homozygotes^{2, 3}.     

Genetic analysis of an electrophoretic variant for the chloroplast-associated form of Cu/Zn superoxide dismutase in sunflower (Helianthus annuus L.)

Polyacrylamide gel electrophoresis of water-soluble proteinsfrom sunflower (Helianthus annuus L.) cotyledons, followed byspecific staining for superoxide dismutase activity, discriminated,according to their electrophoretic mobility, two distinct achromaticbands for Cu/Zn superoxide dismutase. Zymograms of proteinsfrom isolated chloroplasts showed that the chloroplast-locatedCu/Zn superoxide dismutase (Cu/ZnSOD_Chl) migrated faster inthe SOD activity-stained gels. An electrophoretic variant pattern,whose mobility is lower than the control pattern, was identifiedin the ABA-deficient mutant w-1. The variant is coded by a nucleargene with two codominant alleles. Key words: Sunflower, Helianthus annuus L., ABA-deficient mutant, electrophoretic isozyme variant, superoxide dismutase     

Dietary rescue of a lethal “null” activity allele of 6-phosphogluconate dehydrogenase in Drosophila melanogaster

The genetic rescue of Pgd ⁿ lethal alleles, accomplished by combining them with mutations lacking glucose-6-phosphate dehydrogenase activity, has led to the hypothesis that Pgd ⁿ lethality may be due to the accumulation of 6-phosphogluconate. In this article we report the rescue of Pgd ⁿ /Y males by dietary supplements (fructose and linolenate) designed to minimize 6-phosphogluconate production.This investigation was supported by Research Grant GM-15691 and Training Grant T01-GM-0685 of the National Institutes of Health.     

Variation in Biochemical Properties of Allozymes of Xanthine Dehydrogenase in DROSOPHILA PSEUDOOBSCURA

Twenty-six D. pseudoobscura strains isogenic for xanthine dehydrogenase alleles from Mesa Verde, Colorado, were tested for differences in the biochemical properties of different allelic forms of xanthine dehydrogenase. No significant differences in binding affinity (K_m) or substrate specificity of the enzyme were found. Significant variation among strains, in activity (V_max) and among electromorphs, as well as among strains, in thermolability was found. For the few strains tested, the activity and thermolability differences were shown to co-segregate with the electrophoretic mobility of the variant allele.     

Allozyme differentiation in the Mediterranean firs (Abies, Pinaceae). A first comparative study with phylogenetic implications

Nineteen natural Mediterranean fir populations, belonging to eight species and to one natural hybrid (A. ×borisii-regis), were investigated by starch and polyacrylamide gel electrophoresis. A total of 31 alleles was scored at eight loci (IDH-B, ACP-A, PER-B, 6PGD-A, 6PGD-B, MNR-B, PGI-B, PGM-A. Great variation was observed in the heterozygosity among the population studied and ranged from 0.010 (A. pinsapo) to 0.328 (A. cephalonica). The interpopulation genetic diversity was about 26% of the total genetic diversity. From the dendrogram, new phylogenetic relationships were revealed. High affinity was observed between the Calabrian fir population and the one from north-west Greece as well as betweenA. equi-trojani grown in Asia Minor and the southern Greek populations. Species specific alleles were found inA. cilicica. From the findings of the present work, a new hypothesis concerning the taxonomy, distribution and evolution ofAbies species in the Balkan Peninsula is supported.     

Mitochondrial proline dehydrogenase deficiency in hyperprolinemic PRO/Re mice: Genetic and enzymatic analyses

Genetic analyses, involving backcross and F₂ matings, demonstrate that the type I hyperprolinemia of PRO/Re mice is caused by an abnormal allele at a single locus designated pro-1. Mice homozygous for this allele (pro-1 ^b /pro-1^b) possess a deficiency in the activity of component 1 of mitochondrial proline dehydrogenase. In liver mitochondria of normal C57BL/6J mice, two proline dehydrogenase activity components are demonstrable by electrophoretic resolution of Triton X-100 solubilized extracts. In mitochondria of PRO/Re mice, the activity of component 1 is not readily detectable. Residual proline dehydrogenase activity in PRO/Re mitochondria appears, therefore, to be due in large measure to activity component 2 which is more stable to incubation at 40 C, exhibits slower electrophoretic mobility, and is less reactive to menadione. Kinetic analyses demonstrate a K _m (proline) for the Triton X-100 solubilized enzyme activities of PRO/Re and C57BL/6J liver mitochondria of 0.4 M and 2.9×10^?3 M, respectively. C57BL/6J enzyme activity is inhibited by high substrate concentration. The activity of component 1 was not detected in other subcellular fractions of PRO/Re liver obtained by differential centrifugation. Abnormal control of respiratory chain function in PRO/Re mitochondria appears to involve primarily proline oxidation, as indicated by the level of activity of several inner membrane enzymes.     

Genetic polymorphisms of blood proteins in the troops of Japanese macaques,Macaca fuscata: IV. Erythrocyte esterase polymorphism inMacaca fuscata

Genetic variation at the locus controlling A₁ band of erythrocyte esterase was found in the Japanese macaque,Macaca fuscata. Existence of four alleles,Es-A ₁ ¹ ,Es-A ₁ ² ,Es-A ₁ ³ , andEs-A ₁ ⁴ , controlling the mobility of the band and codominance relation between them were postulated. A majority of the troops examined were monomorphic inEs-A ₁ 1-1 phenotype, and the variant phenotypes were observed to occur only in Yugawara-Ihama, Arashiyama, and Koshima areas.     

Functional hemizygosity in the human genome: direct estimate from twelve erythrocyte enzyme loci

Summary Cord blood samples from 2020 unrelated newborns were screened for levels of enzyme activity for twelve enzymes. The level of enzymatic activity for 100 determinations were consistent with the existence of an enzyme-deficiency allele. The frequency of deficiency alleles in the Black population (0.0071) was four times higher (after removal of the G6PD^*A^- variant) than in the Caucasian sample (0.0016). These frequencies are approximately double the frequency of rare electrophoretic mobility variants at similar loci in the same population. Given the number of functionally important loci in the human genome, these enzyme deficiency variants could constitute a significant health burden.     

IN VIVO Function of Rare G6pd Variants from Natural Populations of DROSOPHILA MELANOGASTER

From 1981 to 1983, 15,097 X-chromosomes were genetically extracted from a number of North American populations of D. melanogaster and were electrophoretically screened for rare mobility and activity variants of glucose-6-phosphate dehydrogenase (G6PD). Overall, 13 rare variants were recovered for a frequency of about 10^-3. Eleven variants affect electrophoretic mobility and are apparently structural, and two variants exhibit low G6PD activity. One low activity variant is closely associated with a P-element insertion at 18D12-13—all of the variants were subjected to the previously described genetic scheme used to identify relative in vivo activity differences between the two common electrophoretic variants associated with the global polymorphism. Most of the rare variants exhibit apparent in vivo activities that are similar to one or the other of the common variants, and these specific rare variants appear to be geographically widespread. Several variants have significantly reduced function. All of the variants were measured for larval specific activity for G6PD as a first measure of in vitro activity. It appears that specific activity alone is not a sufficient predictor for G6PD in vivo function.