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Analysis of transcription and translation of glycolytic enzymes in glucose-limited continuous cultures of Saccharomyces cerevisiae.

mRNA steady-state levels and activities of enzymes of intermediary carbon metabolism (hexokinase, phosphoglucoisomerase, phosphofructokinase, glucose-6-phosphate dehydrogenase, phosphoglucomutase) and glucose-regulated enzymes (pyruvate decarboxylase, pyruvate dehydrogenase, invertase, alcohol dehydrogenase) were determined in glucose-limited continuous cultures of an industrial strain of Saccharomyces cerevisiae at different dilution rates (D) ranging from 0.05 to 0.315 h-1. The activity of most enzymes measured remained constant over this range except for alcohol dehydrogenase I/II which decreased proportionally with increasing dilution rate. A decrease in phosphoglucomutase activity occurred with increasing dilution rate but reached a minimum at D 0.2 h-1 and from thereon remained constant. A decrease in pyruvate decarboxylase activity and a slight decrease in phosphoglucoisomerase activity was observed. At D 0.29/0.315 h-1, at the onset of the Crabtree effect, most glycolytic enzymes remained constant except for pyruvate decarboxylase and glucose-6-phosphate dehydrogenase which increased at D 0.315 h-1 and alcohol dehydrogenase I/II which decreased. The ADHI/II and PDC1 mRNA levels obtained at the different dilution rates were in accordance with the activity measurements. The mRNA level of HXK1 decreased with increasing dilution rates, whereas the transcription of HXK2 increased. Pyruvate dehydrogenase (PDA1) and PGI1 mRNA fluctuated but no significant change could be detected. These results indicate that there is no transcriptional or translational regulation of glycolytic flux between D 0.05 h-1 and 0.315 h-1 except at the branch point between oxidative and fermentative metabolism (pyruvate decarboxylase/pyruvate dehydrogenase) at D 0.315 h-1. Surprisingly regulation of the Crabtree effect does not seem to involve transcriptional regulation of PDA1.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

A nitrogen-limited, glucose-repressed, continuous culture of Saccharomyces cerevisiae.

Glucose-repressed growth of Saccharomyces cerevisiae was analysed in a nitrogen-limited continuous culture at different dilution rates (D). The glucose consumption of the yeast decreased from 3.4 g g-1 h-1 to 3.0 g g-1 h-1 when D was decreased from 0.3 h-1 to 0.15 h-1. No transcripts of the SUC2 and HXK1 genes, encoding, respectively, invertase and hexokinase isoenzyme 1, could be detected. Because both genes are regulated by glucose repression at the transcriptional level, this confirmed that the culture was glucose repressed at every D. During the decrease in D, no change in the activities or mRNA levels of key enzymes in carbon metabolism was observed, except for alcohol dehydrogenases I and II and phosphoglucomutase. These enzymes increased in activity and/or mRNA level when D was decreased, which was also observed in glucose- and galactose-limited continuous cultures. This demonstrates that the expression levels of alcohol dehydrogenases I and II, and also phosphoglucomutase, are coupled to the growth rate of the organism. A comparison between the alcohol dehydrogenase II activity in glucose- and nitrogen-limited continuous cultures demonstrated that the growth rate contributes as much to repression of alcohol dehydrogenase II activity as does glucose. Both the glucose consumption and the activity of the glycolytic enzymes were relatively constant when D was decreased and, as a consequence, the concentrations of intracellular metabolites remained constant. A slight decrease in the glucose 6-phosphate concentration was observed, which could be caused by the slight decrease in glucose consumption at low D values.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbon↗

Sucrose-to-Starch Metabolism in Tomato Fruit Undergoing Transient Starch Accumulation.

Immature green tomato (Lycopersicon esculentum) fruits undergo a period of transient starch accumulation characterized by developmental changes in the activities of key enzymes in the sucrose (Suc)-to-starch metabolic pathway. Activities of Suc synthase, fructokinase, ADP-glucose (Glc) pyrophosphorylase, and soluble and insoluble starch synthases decline dramatically in parallel to the decrease in starch levels in the developing fruit. Comparison of "maximal" in vitro activities of the enzymes in the Suc-to-starch pathway suggests that these same enzymes are limiting to the rate of starch accumulation. In contrast, activities of invertase, UDP-Glc pyrophosphorylase, nucleoside diphosphate kinase, phosphoglucoisomerase, and phosphoglucomutase do not exhibit dramatic decreases in activity and appear to be in excess of starch accumulation rates. Starch accumulation is spatially localized in the inner and radial pericarp and columella, whereas the outer pericarp and seed locule contain little starch. The seed locule is characterized by lower activities of Suc synthase, UDP-Glc pyrophosphorylase, phosphoglucomutase, ADP-Glc pyrophosphorylase, and soluble and insoluble starch synthases. The outer pericarp exhibits comparatively lower activities of ADP-Glc pyrophosphorylase and insoluble starch synthase only. These data are discussed in terms of the developmental and tissue-specific coordinated control of Suc-to-starch metabolism.

Journal Article↗

Enzymes of carbohydrate metabolism in the developing endosperm of maize.

A number of enzymes presumably implicated in starch synthesis were assayed at various stages of endosperm development ranging from 8 days to 28 days after pollination. Activity for invertase, hexokinase, the glucose phosphate isomerases, the phosphoglucomutases, phosphorylase I, uridine diphosphate glucose pyrophosphorylase, and the starch granule-bound nucleoside diphosphate glucose-starch glucosyltransferase was present at the earliest stage of development (8 days) studied. Activity was detectable for phosphorylase III, the soluble adenosine diphosphate glucose-starch glucosyltransferase, adenosine diphosphate glucose pyrophosphorylase, and sucrose-uridine diphosphate glucosyltransferase at 12 days. For phosphorylase II and cytidine diphosphate glucose pyrophosphorylase, activity was first detectable at the 14- and 16-day stages, respectively. Rapid increases in starch content are observed prior to detectable activity for adenosine diphosphate glucose pyrophosphorylase, the soluble adenosine diphosphate glucose-starch glucosyltransferase and phosphorylases II and III. For all enzymes, except invertase, activity per endosperm rises to a peak at 22 or 28 days. Greatest activity for invertase is found at 12 days with a steady decline thereafter. The pattern of invertase activity in comparison with that of sucrose-uridine diphosphate glucosyltransferase supports previous suggestions, that the latter plays a key role in the conversion of sucrose to starch. In addition to phosphorylases I, II, and III, multiple forms of glucosephosphate isomerase and phosphoglucomutase were detected.

Journal Article↗

Amylopectin degradation in pea chloroplast extracts.

Phosphorolysis rather than phosphorylation of amylolysis products was found to be the major pathway of sugar phosphate formation from amylopectin by pea (Pisum sativum L.) chloroplast stromal proteins. The K(m) for inorganic phosphate incorporation was 2.5 mm, and ATP did not stimulate amylopectin-dependent phosphate incorporation. Arsenate (10 mm) inhibited phosphate incorporation into glucose monophosphates up to 46% and phosphoglucomutase activity 96%, resulting in glucose 1-phosphate accumulation as a product of amylopectin degradation. The intracellular distribution of enzymes of starch utilization was determined. Phosphorylase, phosphoglucomutase, and hexokinase were found in the chloroplast and cytoplasm, while beta-amylase was restricted to the cytoplasm. Maltase was not detectable; maltose phosphorylase was active in the chloroplast.

Journal Article↗

Isoenzymes of sugar phosphate metabolism in endosperm of germinating castor beans.

Two isoenzymes each of phosphoglucomutase, hexose phosphate isomerase, aldolase, fructose diphosphatase, phosphofructokinase, and 6-phosphogluconate dehydrogenase have been separated by DEAE-cellulose column chromatography of extracts from endosperm of germinating castor beans (Ricinus communis cv. Hale). One of each of the enzymes is localized in the cytosol and the other is confined to plastids. Developmental studies of these isoenzymes were carried out to clarify their roles in the endosperm. In extracts from ungerminated seeds the activities of marker enzymes of mitochondria (fumarase), plastids (ribulose bisphosphate carboxylase), and glyoxysomes (catalase) were low, but phosphoglucomutase, hexose phosphate isomerase, aldolase, and 6-phosphogluconate dehydrogenase were present in relatively high activity. The total amounts of these enzymes increased 3- to 4-fold during the first 5 days of growth. The activities of isoenzymes in the plastids rose in parallel with that of ribulose bisphosphate carboxylase to reach a maximum at day 4, and like the carboxylase they declined sharply thereafter. The activities of the cytosolic isoenzymes peaked at day 5. These changes are consistent with the roles previously proposed for the sequences present in plastid and cytosol.

Journal Article↗

Identification of allergens responsible for canine cutaneous adverse food reactions to lamb, beef and cow's milk.

Lamb, beef and cow's milk are common causes of cutaneous adverse food reactions in dogs. The aim of this study was to identify the proteins responsible for cutaneous adverse reactions to these foods. Ten dogs with allergen-specific serum immunoglobulin (Ig)E to lamb, beef and cow's milk were included in the study. These dogs had been diagnosed with cutaneous adverse food reactions by convincing clinical history and food-elimination diet trials followed by challenge exposure. Sera were analysed by enzyme-linked immunosorbent assay with bovine proteins and SDS-PAGE immunoblots with lamb, beef and cow's milk extracts. All the dogs had specific IgE against bovine IgG, and it was the only protein in the cow's milk extract that bound IgE from the sera studied. In the lamb and beef extracts, the major allergens recognized by the specific IgE of most sera had molecular masses between 51 and 58 kDa, which were identified as phosphoglucomutase and the IgG heavy chain. Other IgE-binding proteins with molecular masses of 27, 31, 33, 37 and 42 kDa were also detected with some sera. Our results indicate that bovine IgG is a major allergen in cow's milk and hence it appears to be a source of cross-reactivity with beef and probably with lamb because of the high homology with ovine immunoglobulins. These results are similar to those found for meat allergy in humans. However, this is the first time that phosphoglucomutase has been identified as an important allergen involved in allergic reactions to lamb and beef.

Allergens↗

Ontogeny of some enzymes of glycogen metabolism in rabbit fetal heart, lungs, and liver.

Optimum conditions were established for the assay of glycogen, glycogen synthase, glycogen phosphorylase, phosphoglucomutase, and glucose-6-phosphatase in rabbit fetal heart, lung, and liver. Using these methods, the pattern of appearance of glycogen and the above four enzymes was established from day 18 of gestation to day 8 after birth. The results indicate that total tissue glycogen reaches maximum levels between days 22 and 24 in the heart, days 24 and 26 in the lung, and days 30 and 31 in the liver. In all three tissues, the rapid rise or depletion of glycogen is coincident with a corresponding increase in glycogen synthase and glycogen phosphorylase activities. However, substantial amounts of glycogen synthase are present both prior to and after the accumulation of glycogen. Similarly, considerable amounts of glycogen phosphorylase are present early in gestation, yet deposition of glycogen occurs. Both the I and D forms of glycogen synthase are present in the three tissues, the major being the physiologically inactive D form. Similarly both the a and b forms of glycogen phosphorylase are present, with the a form (active form) making up about 30-60% of the total phosphorylase activity. Glucose-6-phosphatase was absent in fetal heart and lung throughout the period of gestation investigated. Low levels of this enzyme were detectable in fetal liver near term. The phosphoglucomutase activity increased progressively from day 22 of gestation in all three tissues and continues to increase after birth. The disappearance of fetal lung glycogen occurs between days 27 and 28 at a time when surfactant phospholipids first appear. These findings indicate that the breakdown of glycogen is providing the fetal lung cells with energy necessary for surfactant phospholipid biosynthesis.

Animals↗

The Nubians of Kom Ombo: serum and red cell protein types.

Phenotype and gene frequencies are presented for eight polymorphic systems among the Nubians of South Egypt, namely, acid phosphatase, glucose-6-phosphate dehydrogenase, adenylate kinase, 6-phosphogluconate dehydrogenase, esterase D, phosphoglucomutase I, peptidase A, and haptoglobin. Eleven systems, namely, albumin, ceruloplasmin, hemoglobin, lactate dehydrogenase, isocitrate dehydrogenase, phosphohexose isomerase, malate dehydrogenase, peptidase B and C, phosphoglucomutase II, and transferrin were found to be monomorphic. A single electrophoretic variant of phosphohexose isomerase were observed.

Blood Proteins↗

Effect of hypoxia on the activity and binding of glycolytic and associated enzymes in sea scorpion tissues.

The effect of hypoxia on the levels of glycogen, glucose and lactate as well as the activities and binding of glycolytic and associated enzymes to subcellular structures was studied in brain, liver and white muscle of the teleost fish, Scorpaena porcus. Hypoxia exposure decreased glucose levels in liver from 2.53 to 1.70 mumol/g wet weight and in muscle led to its increase from 3.64 to 25.1 mumol/g wet weight. Maximal activities of several enzymes in brain were increased by hypoxia: hexokinase by 23%, phosphoglucoisomerase by 47% and phosphofructokinase (PFK) by 56%. However, activities of other enzymes in brain as well as enzymes in liver and white muscle were largely unchanged or decreased during experimental hypoxia. Glycolytic enzymes in all three tissues were partitioned between soluble and particulate-bound forms. In several cases, the percentage of bound enzymes was reduced during hypoxia; bound aldolase in brain was reduced from 36.4 to 30.3% whereas glucose-6-phosphate dehydrogenase fell from 55.7 to 28.7% bound. In muscle PFK was reduced from 57.4 to 41.7% bound. Oppositely, the proportion of bound aldolase and triosephosphate isomerase increased in hypoxic muscle. Phosphoglucomutase did not appear to occur in a bound form in liver and bound phosphoglucomutase disappeared in muscle during hypoxia exposure. Anoxia exposure also led to the disappearance of bound fructose-1,6-bisphosphatase in liver, whereas a bound fraction of this enzyme appeared in white muscle of anoxic animals. The possible function of reversible binding of glycolytic enzymes to subcellular structures as a regulatory mechanism of carbohydrate metabolism is discussed.

Animals↗

[Activity of carbohydrate-metabolizing enzymes and content of carbohydrate and nitrogen compounds in muscles of young cattle depending on breed and sex].

The activity of glycolysis and glyconeogenesis enzymes, content of carbohydrate and nitrogen compounds were studied in muscles of 15-month cattle of different sex of the black-piebald breed and its crosses with bulls of two meat breeds Hereford and Limousine. In the muscles of bulls the activity of phosphoglucomutase, phosphohexoisomerase, aldolase and fructose-1,6-diphosphatase is considerably higher (except of the activity of phosphoglucomutase and phosphohexoisomerase in the muscles of pure-bred black-piebald animals for which difference is not statistically reliable) and the content of glycogen, glucose, fructose, lactic acid, free and phosphorylated pentoses of nonadenylic compounds is essentially lower than in the muscle tissue of heifers of analogous breed groups. A higher activity of carbohydrate metabolism enzymes (especially aldolase and fructose-1,6-diphosphate) and a higher content of total pentoses, the adenylic system pentoses, ATP phosphorus in the muscles of the cross Limousine and Hereford bulls and Limousine heifers as compared to the pure-bred black-piebald animals of the corresponding sex coincide with a greater increase in the muscular tissue and more intensive synthesis of proteins in it. A considerably lower level of glycogen, glucose, fructose and a relatively high activity of carbohydrate metabolism enzymes in the muscles of cross young cattle show that disintegration of these carbohydrates is in excess of their synthesis, that is due to an increase in the energy demand connected with a more intensive synthesis of proteins in the muscular tissue. Therefore, in the authors opinion the performed kill of the cross Limousine and Hereford bulls as well as Limousine heifers, is somewhat untimely and unreasonable. At the same time the activity of all the studied enzymes in the muscles of the cross Hereford heifers, vice versa, is considerably lower as compared to the black-piebald heifers and coincides with a low gain in live weight and muscular tissue, a more rapid accumulation of glycogen and lipids and a more delayed--of proteins in the muscular tissue, that evidences for their early maturity. Therefore the further raising of the cross Hereford heifers in the farm for obtaining meat is economically less profitable. The data obtained give grounds to recommend determination of the activity of carbohydrate metabolism enzymes, especially of aldolase and fructose-1,6-diphosphate, as a test for checking the muscular tissue growth and for prognosing the meat productivity in the growing pure-bred and cross young cattle of different sex.

Adenosine Triphosphate↗

[Schistosoma species in Senegal with special reference to the biology, epidemiology and pathology of Schistosoma curassoni Brumpt, 1931].

By combining field and experimental investigations, we were able to study several new aspects of fundamental problems concerning human and animal schistosomiasis in Senegal. Because of the controversy about the identity of Schistosoma curassoni and the possibly connected zoonosis, this parasite has been described once more. A great variety of experimental techniques were used. The eggs of S. curassoni are significantly smaller than those of the two other African species of Schistosoma we know of in ruminants (S. bovis and S. mattheei). But eggs of S. curassoni cannot be distinguished from those of the human, pathogenic S. haematobium. The study of the tegument of adult male worms shows a clear difference between S. bovis on one hand, and S. curassoni and S. haematobium on the other hand. S. bovis' tubercles are well formed, but have no stings at all. The tubercles of S. haematobium and of S. curassoni definitely possess stings. S. curassoni, S. haematobium and S. bovis are also clearly different as to their development in hamsters (Mesocricetus auratus). S. curassoni develops more rapidly and gets bigger than S. bovis and S. haematobium. Finally, different enzymatic systems allow us to distinguish S. curassoni from other schistosoma's of the haematobium group. S. curassoni has a typical pattern for phosphoglucomutase and hexokinase, differing from S. haematobium's patterns. In S. bovis, it differs by the patterns of phosphoglucomutase, glucosephosphate-isomerase, hexokinase and acid phosphatase. Epidemiological studies proved that, in Senegal, Bulinus guernei is the main vector of S. bovis, Bulinus senegalensis of S. haematobium (Northern Senegal) and Bulinus umbilicatus of S. curassoni and S. haematobium (Southern Senegal). There is no indication to consider S. curassoni as a zoonosis. When ruminants are infested by S. curassoni, the symptoms are light and the most important lesions can be found in the liver, the intestines and, in a lesser degree, in the bladder. S. curassoni develops easily in laboratory animals, giving severe lesions in liver and bowels. That makes it an interesting new model for studying the pathogenesis of schistosomes of the haematobium group and the action of new anthelmintics to be used against them.

Animals↗

Oscillatory synthesis of glucose 1,6-bisphosphate and frequency modulation of glycolytic oscillations in skeletal muscle extracts.

Oscillatory behavior of glycolysis in cell-free extracts of rat skeletal muscle involves bursts of phosphofructokinase activity, due to autocatalytic activation by fructose-1,6-P2. Glucose-1,6-P2 similarly might activate phosphofructokinase in an autocatalytic manner, because it is produced in a side reaction of phosphofructokinase and in a side reaction of phosphoglucomutase using fructose-1,6-P2. When muscle extracts were provided with 1 mM ATP and 10 mM glucose, glucose-1,6-P2 accumulated in a stepwise, but monotonic, manner to 0.7 microM in 1 h. The stepwise increases occurred during the phases when fructose-1,6-P2 was available, consistent with glucose-1,6-P2 synthesis in the phosphoglucomutase side reaction. Addition of 5-20 microM glucose-1,6-P2 increased the frequency of the oscillations in a dose-dependent manner and progressively shortened the time interval before the first burst of phosphofructokinase activity. Addition of 30 microM glucose-1,6-P2 blocked the oscillations. The peak values of the [ATP]/[ADP] ratio were then eliminated, and the average [ATP]/[ADP] ratio was reduced by half. In the presence of higher, near physiological concentrations of ATP and citrate (which reduce the activation of phosphofructokinase by glucose-1,6-P2), high physiological concentrations of glucose-1,6-P2 (50-100 microM) increased the frequency of the oscillations and did not block them. We conclude that autocatalytic activation of phosphofructokinase by fructose-1,6-P2, but not by glucose-1,6-P2, is the mechanism generating the oscillations in muscle extracts. Glucose-1,6-P2 may nevertheless play a role in facilitating the initiation of the oscillations and in modulating their frequency.

Adenine Nucleotides↗

[Genetic structure of the populations of native inhabitants in the northeastern USSR. V. The Chukot Evens].

The genetic structure of two Chukot Evens subpopulations (314 individuals) for electrophoretic protein systems and taste sensitivity to PTC was studied. 17 of the 39 loci were polymorphic (43.59%). The following systems were completely monomorphic: diaphorase NAD H (Dia); glucose-6-phosphate dehydrogenase (G-6-PD); glutamatoxalate transaminase (GOT); carbonic anhydrase (Ca-1); catalase (Ct), lactate dehydrogenase (loci LDH-A and LDH-B); leucine aminopeptidase (Lap); malate dehydrogenase (MDH); purine nucleoside phosphorylase (PNP); superoxide phosphorylase (PNP); superoxide dismutase (SOD); phosphoglucomutase-2 (PGM2); cholinesterase (locus E1); red cell esterase (4 loci); albumin (Alb); hemoglobin (Hb A and B); ceruloplasmin (Cp); and blood, gren, using the standard method. The following systems were polymorphic: red cell acid phosphatase (AcP); phosphoglucomutase-1 (PGM1); 6-phosphogluconate dehydrogenase (PGD); glutamatepyruvate transaminase (GPT); glyoxalase-1 (GLO-1); esterase (EsD); adenilatkinase (AK); alkaline phosphatase (Pp); cholinesterase (locus E2); haptoglobin (Hp); transferrin (Tf); group-specific component (Gc) and ABO, MN, Lewis, P blood groups and taste sensitivity to PTC. The following allele frequencies for polymorphic loci have been detected: AKI = 0.994; GLO = 1I = 0.082; GPT1 = 0.653; AcPA = 0.400; AcPB = 0.599; AcPC = 0.001; PGDA = 0.944; PGM1(1) = 0.906; EsD1 = 0.897; E2+ = 0.048; HpI = 0.394; GcI = 0,919; Tfc = 0.987; r(O) = 0.669; p(A) = 0.184; q(B) = 0.146; M = 0.711; Le = 0.411; P1+ = 0.521; t = 0.295. The genetic structure of Chukot Evens population is significantly nearer to that of the other ethnic groups of the North-East, in comparison with the genetic structure of Evenks of the Middle Siberia.

Blood Group Antigens↗

Developmentally regulated proteases from the basidiomycete Schizophyllum commune.

The basidiomycete Schizophyllum commune produces three chromatographically distinguishable proteases which are capable of attack on a variety of other enzymes from S. commune and other sources. These proteases, which are produced during a specific phase of the development cycle, exhibit typical enzyme kinetic patterns, are active in the neutral to weakly alkaline pH range and are inhibited by phenylmethylsulfonyl fluoride, soybean trypsin inhibitor, and ovomucoid. No pattern of specificity toward the test enzymes could be discerned. The proteases co-purify with the activity which causes the increase in cold lability of S. commune phosphoglucomutase reported previously. In addition, one of the protease enzymes could be purified to the point where it had no significant ability to release trichloroacetic acid products from denatured substrates at pH 3 or pH 7. When undenatured hemoglobin was used as a substrate, the purified protease releases a relatively large molecular weight nonheme peptide. Relatively large peptides are also formed after proteolysis of rabbit muscle phosphoglucomutase. These results suggest that the protease carries out only limited proteolysis.

Agaricales↗

DNA sequencing and analysis of a 40 kb region from the right arm of chromosome II from Schizosaccharomyces pombe.

We have determined the complete nucleotide sequence of a 39,648 bp segment, contained in cosmid c32F12, derived from the right arm of chromosome II from the fission yeast Schizosaccharomyces pombe. Computer analysis of the sequence revealed the presence of 15 non-overlapping open reading-frames (ORFs) longer than 300 bp and one tRNA-Thr gene. Six ORFs correspond to the previously known rec14+, tug1+, rum1+, pch1+, gpd1+ and cyr1+ genes. Five ORFs code for putative proteins with significant homology to proteins from other organisms. SPBC32F12.01c shows considerable similarity to human neutral sphingomyelinase, whereas SPBC32F12.03c, SPBC32F12.10 and SPBC32F12.14 exhibit strong homology to glutathione peroxidase, phosphoglucomutase and ubiquitin protein ligase E-3 components from various organisms, respectively. The four remaining ORFs identified show weak or non-significant homology to previously sequenced genes. The nucleotide sequence has been submitted to the EMBL database under Accession Number AL023796.

Amino Acid Sequence↗

Unexpected ratio of allozyme expression in diploid and triploid individuals of the clonal hybrid fish Phoxinus eos-neogaeus.

Phoxinus eos-neogaeus, a North American freshwater fish, was formed by hybridization between P. neogaeus and P. eos. Individuals of P. eos-neogaeus express one allozyme of P. eos and one allozyme of P. neogaeus for enzymes for which the parental allozymes are distinctive. We performed densitometry on phosphoglucomutase (PGM) and one glucose-6-phosphate isomerase locus (GPI-A) separated by cellulose acetate electrophoresis to determine if the parental species' allozymes are expressed in proportion to the number of genomes present in diploid and triploid individuals, and if these enzymes are regulated separately in different tissues. In diploids, activity of the P. eos allozyme was greater than the P. neogaeus allozyme in eye, liver, and muscle but not in heart (one sample t-test, P = 0.05) for PGM. The activity of the P. eos GPI-A allozyme was significantly greater than the P. neogaeus allozyme in heart, eye and muscle but not in liver (one sample t-test, P = 0.05). The expected ratio of eos:neogaeus expression in triploid P. eos-neogaeus x eos individuals is 2:1. For PGM, the observed ratio of eos:neogaeus expression was not significantly different from 2:1 in all four tissues. The P. eos allozyme for GPI was expressed less than expected in all four tissues (one-sample t-test, P = 0.05). Thus, greater than expected expression of the P. eos allozyme was not observed in triploid individuals as it was in the diploids. These data show that PGM and GPI are regulated separately, and that regulation differs by tissue, and in fish of distinct ploidy levels. J. Exp. Zool. 284:663-674, 1999.

Animals↗

Isozyme patterns in erythrocytes from human fetuses.

Starch gel electrophoretic patterns of 26 enzymes (corresponding to 36 gene loci) were examined in hemolysates of erythrocytes from 11 first-trimester and mid-trimester human fetuses (65-138 gestation days). The zymograms of 16 enzymes were identical in fetal and control adult red cells. Six enzymes (enolase, guanylate kinase, lactate dehydrogenase, nucleoside phosphorylase, phosphofructokinase, hexokinase) showed differences in the staining intensity of certain isozyme zones as compared with the controls. Also, the fetal red cell zymograms, in contrast to those of adults, contained the mitochondrial forms of isocitric dehydrogenase and glutamic oxaloacetic transaminase as well as more definite zones of phosphoglucomutase-3. Finally, some of the isozymes of uridine diphosphate kinase in the fetal cells had slightly retarded mobility. These observed differences between fetal and adult red cells could reflect the expression of a different program of protein synthesis in red cells of the fetuses or the epigenetic modifications of isozymes in immature red cells.

Electrophoresis, Starch Gel↗