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.     

High frequency of spontaneous translocations revealed by FISH in cells from patients with the cancer-prone syndromes ataxia telangiectasia and Nijmegen breakage syndrome.

The application of fluorescence in situ hybridization (FISH) using whole-chromosome paints (WCPs) is proving to be a very powerful technique for revealing chromosomal instability that, for the most part, has gone undetected by conventional cytogenetic analysis. We have analyzed the frequency of translocations in lymphocytes and lymphoblastoid cell lines from ataxia telangiectasia (AT) and Nijmegen breakage syndrome (NBS) homozygotes and heterozygotes using a three-color chromosome-painting technique (WCP 1, 2, 4). With this assay we were able to detect an increased frequency of spontaneous translocations in AT homozygotes (median, 18.47 +/- 10.82 translocations per 1,000 metaphase cells; 10 patients) and AT heterozygotes (median, 7.87 +/- 3.15 translocations per 1,000 cells; 7 patients), in comparison to controls (median, 2.26 +/- 1.75 translocations per 1,000 cells; 10 controls). Analysis of NBS homozygotes (median, 19.05 +/- 11.27 translocations per 1,000 cells; 5 patients) and NBS heterozygotes (median, 6.93 +/- 3.04 translocations per 1,000 cells; 6 patients) also showed an increased frequency of translocations in these patients compared to controls. The presence of such hitherto undetected chromosomal aberrations corroborate previous findings of spontaneous chromosomal instability in AT and NBS patients, as manifested by an increased rate of open breaks and rearrangements involving chromosomes 7 and 14. Moreover, we show that the degree of genomic instability in AT and NBS patients is even higher than previously established and that some AT and NBS heterozygotes evidence spontaneous chromosomal instability as well. These increased levels of nonspecific translocations could be an important risk factor for the development of malignancies in homozygotes and heterozygotes for ATM or NBS1 gene mutations.     

A "disproportion" between the frequency of rare electropmorphs and enzyme deficiency variants in Amerindians

Our previous studies have revealed a higher frequency of nonpolymorphic electrophoretic variants in blood samples from Amerindians than in similar samples from Caucasians and Japanese. Our present study finds, by contrast, that the frequency of deficiency variants of 11 erythrocyte enzymes, sampled in nine Amerindian tribes of Central and South America, is essentially the same (1.5/1,000 determinations) as in Caucasians or Japanese. Possible explanations of the elevated frequency of mobility variants in the tropical-zone/ unacculturated populations include: higher mutation rates resulting in both electrophoretic and activity variants in Amerindians but increased selection against deficiency variants in the Amerindians, or comparable mutation rates in both populations coupled with a greater probability of a mobility variant attaining a relatively high frequency among the Amerindians.     

Segmental Aneuploidy and Enzyme Activity as a Method for Cytogenetic Localization in DROSOPHILA MELANOGASTER

A method of mapping genes which specify enzymes without the necessity of obtaining genetic variants has been explored. Three enzymes whose structural genes have known genetic positions were chosen to see if the relationship between gene dosage and enzyme activity could be used as a tool in cytological localization. Zw, the gene specifying G6PD, is located in the X chromosome region, 18D-18F. The structural gene for 6PGD, Pgd, maps in the X chromosome bands 2C1-2E1. Idh-NADP, the gene which specifies IDH-NADP, is found on the third chromosome, in bands 66B-67C.     

Enzyme polymorphisms of Ideles populations (Ahaggar, Algeria) and the Iwellemeden Kel Kummer Twaregs (Menaka, Mali).

Surveys dealing with enzyme polymorphisms have recently been conducted in the Sahara. Results from two populations are reported here: 227 inhabitants of Ideles village (Ahaggar, Algeria); 285 nomads of a genetic isolate, the Kel Kummer Twareg tribe (Menaka, Mali). The four classical molecular variants of G6PD:A+, A-, B+, B-, are found in Ideles. The frequency of the G6PD A+ Negroid variant reaches 15% in Ideles and 7.7% among the Kel Kummer. However, gene frequencies will have to be recalculated after a study of the genetic transmission through families. The PGDC gene of 6PGD is especially frequent in the Kel Kummer where 10 'Canning' phenotypes have been observed. The PGM distribution of alleles at locus 1 in Ideles is the same as in the Mediterranean populations. The pa gene of acid phosphatase, relatively frequent in Ideles, has been excluded by drift from the Kel Kummer gene pool. AK and LDH enzymes have also been studied in both samples. The abnormal Ea1 mutation of serum pseudocholinesterase exists in Ideles and in the Kel Kummer as in other populations of the Sahara; the C5 esterase component was revealed by electrophoresis in 5% of the Kel Kummer people.     

Comparative study of red-cell enzyme polymorphism in the pika and the rabbit

The variants of seven red-cell enzyme systems of two families of Lagomorphae (rabbit and pika) are studied by enzymoelectrophoretic determination of isoenzyme distribution.
Polymorphism appears in five different enzymes (PGM, AK, G6PD, 6PGD and NADH diaphorase) in the pika and in one system (NADH diaphorase) in the rabbit. The electropherograms of acid phosphatase and LDH do not show any variability in either pikas or rabbits. In the pika, red-cell enzyme polymorphism is as intense as it is in man.     

Variation of several erythrocyte enzymes in the Dayaks of Sarawak.

The Land and Sea Dayaks of Sarawak were surveyed for several erythrocyte enzymes. The gene frequency of 6PGDC in 132 Land Dayaks and 127 Sea Dayaks were 0.045 and 0.047, respectively. The gene frequency of PGM1-1 IN 285 Land Dayks and 240 Sea Dayaks were 0.716 and 0.779, respectively. The ADA2 gene frequency in 283 Land Dayaks and 188 Sea Dayaks were 0.154 and 0.090. ADA 5-1 was found once in the Land Dayaks and once in the Sea Dayaks. AK 2-1 was found once in 221 Sea Dayaks but not in any of 270 Land Dayaks. No PHI, LDH or CA variants were found among the Land or Sea Dayaks.     

DUPLICATE GENE EXPRESSION FOR ISOCITRATE DEHYDROGENASE AND 6-PHOSPHOGLUCONATE DEHYDROGENASE IN DIPLOID SPECIES OF ELEUSINE (GRAMINEAE)

In the course of a survey of isozyme variation in the grass genus Eleusine, complex band patterns were observed for the enzymes isocitrate dehydrogenase (IDH) and 6-phosphogluconate dehydrogenase (6PGD). These patterns were interpreted as the result of duplicate expression for one of the two genes that ordinarily codes subcellularly compartmentalized forms of each of these enzymes. The interpretation of IDH phenotypes was facilitated by intraspecific allelic variation at one of the putatively duplicated genes (Idh-2), and was verified by examining phenotype ratios in progeny arrays from selfed heterozygotes of E. indica. The lack of analogous intraspecific variation for 6PGD precluded genetic tests, but the duplicate nature of expression was supported by interspecific patterns of variation. Four out of the five diploid species of Eleusine studied (E. indica, E. jaegeri, E. multiflora, E. tristachya) exhibited both duplications; E. floccifolia appeared to lack the IDH duplication, but possessed the 6PGD duplication. Both enzymes showed evidence of hyperduplication in the tetraploid species E. coracana.     

Biochemical genetic markers in the Kadazans of Sabah,Malaysia

Summary Kadazans, the largest indigenous group in Sabah, northern Borneo, were surveyed for glyoxalase I, phosphoglucomutase I, red cell acid phosphatase, esterase D, adenosine deaminase, soluble glutamate pyruvate transaminase, soluble glutamate oxaloacetate transaminase, 6-phosphogluconate dehydrogenase, uridine monophosphate kinase, adenylate kinase, peptidase B and D, superoxide dismutase, C₅, group specific component, haptoglobin and transferrin.Kadazans were found to be polymorphic for GLOI, PGMI, RCAP, esterase D, ADA, s-Gpt, 6PGD, UMPK, Gc, C₅, haptoglobin and peptidase B. Rare variants were found for transferrin and peptidase D. No variant was found for s-Got, SOD and AK.     

Autosomal Factors with Correlated Effects on the Activities of the Glucose 6-Phosphate and 6-Phosphogluconate Dehydrogenases in DROSOPHILA MELANOGASTER

Isogenic lines, in which chromosomes sampled from natural populations of D. melanogaster are substituted into a common genetic background, were used to detect and partially characterize autosomal factors that affect the activities of the two pentose phosphate pathway enzymes, glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD). The chromosome 3 effects on G6PD and 6PGD are clearly correlated; the chromosome 2 effects, which are not so great, also appear to be correlated, but the evidence in this case is not so strong. Examination of activity variation of ten other enzymes revealed that G6PD and 6PGD are not the only pair of enzymes showing a high positive correlation, but it is among the highest in both sets of lines. In addition, there was some evidence that the factor(s) affecting G6PD and 6PGD may also affect two other metabolically related enzymes, transaldolase and phosphoglucose isomerase.—Rocket immunoelectrophoresis was used to estimate specific CRM levels for three of the enzymes studied: G6PD, 6PGD and ME. This experiment shows that a large part of the activity variation is accounted for by variation in CRM level (especially for chromosome 3 lines), but there remains a significant fraction of the genetic component of activity variation that is not explained by CRM level.—These results suggest that the autosomal factors are modifiers involved in regulation of the expression of the X-linked structural genes for G6PD and 6PGD, but a role in determining part of the enzymes' primary structure cannot be excluded with the present evidence.     

Gene dosage effect in human triploid fibroblasts

Summary The activity of 13 cytoplasmic enzymes has been determined in fibroblast extracts from 9 triploid and 13 control lines. The results show a high activity for 2 X-linked enzymes, glucose 6-phosphate dehydrogenase and phosphoglycerate kinase. These data, together with cytogenetic observations, support the contention that 2 X chromosomes were active in the triploid lines.Abbreviations G6PD Glucose 6-phosphate dehydrogenase - 6PGD 6-phosphogluconate dehydrogenase - HK hexokinase - PGM phosphoglucomutase - PHI phosphohexoisomerase - PFK phosphofructokinase - ALD aldolase - TPI triosephosphate isomerase - PGK phosphoglycerate kinase - ENOL enolase - AK adenylate kinase - LDH lactic dehydrogenase - HBDH hydroxybutyrate dehydrogenase INSERM U. 129.INSERM U. 73.     

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.     

Haemolytic anaemia in Basenji dogs. 2. Partial deficiency of erythrocyte pyruvate kinase (PK; EC 2.7.1.40) in heterozygous carriers

Congenital nonspherocytic haemolytic anaemia (HA) in dogs of the Basenji breed is inherited as a simple, autosomal recessive trait. Previous results of pyruvate kinase (PK) assays suggest a causal relationship between the anaemia and PK deficiency in erythrocytes. In the present investigation assays of this enzyme have been performed on haemolysates from 45 Basenji dogs, comprising 3 anaemic and 42 non-anaemic individuals of which 13 were known heterozygotes. The PK activity in haemolysates from the 42 non-anaemic dogs exhibited a bimodal distribution corresponding to the genotypic classes: heterozygotes and normal homozygotes. The results indicate that heterozygotes have a partial, detectable enzyme deficiency, not reflected in clinical disease, and thus give evidence of a gene dosage effect in agreement with observations in man. The proposed genotypes PK PK, PK pk and pk pk refer to normal homozygotes, heterozygotes, and anaemic individuals, respectively. The findings strengthen the genetic hypothesis of recessiveness of the anaemia by direct detection of heterozygosity of parents of affected individuals. Moreover, the results are of value in comparative studies and they have practical application in connection with eradication programmes.     

Primate red cell enzymes: glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase

Glucose-6-phosphate dehydrogenase (E. C.: 1.1.1.49) phenotypes and 6-phosphogluconate dehydrogenase (E. C.: 1.1.1.44) phenotypes were determined by starch-gel electrophoresis of red cell hemolysates of Galago crassicaudatus subspp., Propithecus verreauxi, Lemur spp., Hapalemur griseus, and Macaca mulatta. A single glucose-6-phosphate dehydrogenase (G6PD) phenotype was found in each species. A single 6-phosphogluconate dehydrogenase (6PGD) phenotype was found in Lemur spp., Hapalemur griseus, and Galago crassicaudatus argentatus. In a group of six Propithecus verreauxi, three 6PGD phenotypes, PGD A, PGD AB, and PGD B, were found. Three phenotypes, PGD A, PGD AB, and PGD B, were found in 38 G. c. crassicaudatus. The three phenotypes in each species are apparently the products of two codominant autosomal alleles, PGD^A and PGD^B. The frequency of PGD^A in G. c. crassicaudatus is 0.263. A population of 260 free-ranging macaques displays a polymorphism at the 6PGD locus. Three phenotypes, PGD A, PGD AB, and PGD B, were found. These also appear to be controlled by two codominant autosomal alleles, PGD^A and PGD^B the frequency of PGD^A = 0.913. Additional analysis of three well-defined troops within the macaque population indicated that there are no significant differences between the troops or within the population at the 6PGD locus.     

Haemolytic anaemia in Basenji dogs. 2. Partial deficiency of erythrocyte pyruvate kinase (PK; EC 2.7.1.40) in heterozygous carriers1

Congenital nonspherocytic haemolytic anaemia (HA) in dogs of the Basenji breed is inherited as a simple, autosomal recessive trait. Previous results of pyruvate kinase (PK) assays suggest a causal relationship between the anaemia and PK deficiency in erythrocytes. In the present investigation assays of this enzyme have been performed on haemolysates from 45 Basenji dogs, comprising 3 anaemic and 42 non-anaemic individuals of which 13 were known heterozygotes. The PK activity in haemolysates from the 42 non-anaemic dogs exhibited a bimodal distribution corresponding to the genotypic classes: heterozygotes and normal homozygotes. The results indicate that heterozygotes have a partial, detectable enzyme deficiency, not reflected in clinical disease, and thus give evidence of a gene dosage effect in agreement with observations in man. The proposed genotypes PK PK, PK pk and pk pk refer to normal homozygotes, heterozygotes, and anaemic individuals, respectively. The findings strengthen the genetic hypothesis of recessiveness of the anaemia by direct detection of heterozygosity of parents of affected individuals. Moreover, the results are of value in comparative studies and they have practical application in connection with eradication programmes.     

Genetic blood markers in Arab Druze of Israel

A sample of 153 individuals from a Druze village, in northern Israel, was typed for the following genetic markers--ABO, MNSs, Rh, P, Kell, and Duffy in the blood groups AcP, AK, ADA, EsD, GL01, ICD, LDH, G6PD, PGM 1 & 2, PHI, PGD and peptidases A, B, C, and D in the red cell enzymes and for the serum proteins Hp and GC subtypes. Rare variants were observed in the following systems: PGD, a new slow variant, PGM, type 8-1; Pep A, types 2-1 and 3-1, Pep B, type 2-1; Pep D, types 3-1 and 3-3; and type GC, 2-V. Significant deviations from Hardy-Weinberg expectations were observed for MNSs and Duffy because of increased homozygosity, which was also observed in three other systems. Gene frequencies compared well with those of Arab Druze and Moslems in Lebanon and of Israeli Moslems in most of the systems, except for the lower frequencies of blood group B, the NS chromosome, the cde haplotype, and the AcPA allele in the present sample. A considerably lower frequency of the Fy allele was found in the Druze compared with Arab Moslems. It may be due to the Druze having been less exposed to inflow of African genes, to their being highlanders, and, therefore, less exposed to Plasmodium vivax malaria, or to both of the above.     

Evidence against a common subunit in adenylate kinase and pyruvate kinase

Summary A modified technique has been introduced which allows detection of PK in the presence of AK after starch-gel electrophoresis. It is shown that the PK isoenzyme patterns of different human tissues are independent of the AK phenotype of the person concerned. It is concluded that there is no basis for the previously held assumption that these two enzymes share a common polypeptide chain.This work was supported by a grant from the Scottish Hospital Endowments Research Trust (HERT 309).     

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.     

The distribution of serum protein and enzyme groups among the Batak of Samosir Island (Sumatra,Indonesia)

Summary 188 blood samples from Batak of Samosir Island (Sumatra, Indonesia) have been studied for electrophoretic variants of haemoglobin, 14 red cell enzyme and 5 serum protein systems. The acid phosphatase, 6 PGD, PGM₁ and ADA enzyme systems are polymorphic, and a single AK 2-1 person was detected. Polymorphism is present in the haptoglobin, transferrin and protease inhibitor systems. Two variant alleles, Tf ^Dchi and Tf ^B are present in the transferrin system, but the B variant has not been identified. Similarly, 3 persons with caeruloplasmin variants were found, but also these variants have not been identified. No abnormal haemoglobins were detected. All other systems revealed the presence of only normal phenotypes.

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Zusammenfassung 188 Blutproben des Batak-Stammes von Samosir Island (Sumatra, Indonesien) wurden auf elektrophoretische Varianten des Hämoglobins in 14 Erythrocyten-enzym-und 5 Serumprotein-Systemen untersucht. Die Saure Phosphatase, 6GPD, PGM₁ und ADA-Systeme sind polymorph, und eine einzige AK 2-1-Person wurde gefunden. In den Haptoglobin-, Transferrin- und Pi-Systemen treten Polymorphismen auf. Zwei abweichende Allele, Tf ^Dchi und Tf ^B, sind im Transferrin-System zu finden, aber die B-Variante ist nicht bestimmt worden. Ebenso wurden 3 Personen mit Ceruloplasmin-Varianten gefunden, doch auch diese Varianten wurden nicht identifiziert. Keine abnormen Hämoglobine wurden gefunden. Alle anderen Systeme wiesen nur normale Phenotypen auf.