Absence of red cell glutamic-pyruvate transaminase: discovery of a "silent" allele homozygote.

An individual with complete absence of red blood cell glutamic-pyruvate transaminase (GPT) activity has been discovered in a South African family of Lebanese origin. The subject, who also shows a low level of serum GPT, appears to be perfectly healthy. His children, all obligatory heterozygotes for the GPT0 allele, have lower than average levels of the red cell enzyme. An apparent instance of anomalous segregation of red cell GPT resulting from the inheritance of the GPT0 allele was recorded in one of the proband''s grandchildren.     

Comparative studies on the human glutamate-pyruvate transaminase phenotypes--GPT 1, GPT 2-1, GPT 2.

The quantitative differences between the activity of the 3 common phenotypes of human red cell GPT has been confirmed. In addition, the activity of red cell GPT 1 was found to be greater in young children than in adults. No such difference was found for the GPT 2 phenotype. The activity of the red cell GPT 1 was found to decrease with age, reaching the adult level at the age of 10 to 12 years. Red cell GPT of all the 3 common phenotypes in both adults and children was found to show a similar response to the addition of excess pyridoxal phosphate. A method has been devised for the partial purification of human GPT (cytoplasmic) from liver. GPT 1 and GPT 2 have been purified, and very few significant differences were found amongst the physical and kinetic parameters tested.     

Human red cell glutamic-pyruvic transaminase polymorphism in Serbia, Yugoslavia

The polymorphism of red cell glutamic-pyruvic transaminase (GPT) was studied in 277 unrelated voluntary blood donors from the population of Serbia (Yugoslavia). The following phenotype frequencies were observed: GPT 1 0.309, GPT 2-1 0.454 and GPT 2 0.206, while gene frequencies were: GPT1 0.556 and GPT2 0.454.     

Enzyme activity for monitoring the stability in a thermophilic anaerobic digestion of wastewater containing methanol

To maintain good conditions in a thermophilic methane bioreactor treating methanol as the main substrate, microbial enzyme activity in the reactor was investigated. In a preliminary study, seven enzymes were tested for their suitability as indicators using an acid-former, 22a originating from a digester with low efficiency, Methanosarcina sp. (CHTI-55) and Desulfotomaculum nigrificans (Delft 74). Among the tested strains, the activities of seven enzymes were the highest in 22a. Acidic phosphatase (ACP), glutamic-pyruvic transaminase (GPT) and α-amylase (AMY) were chosen as hopeful indicators for lab-scale tests and their activities were measured at the optimum temperature of 55°C. In the lab-scale test, reactor failure was induced by nitrogen deficiency or addition of dimethyl disulfide (DMDS) as an inhibitor. ACP, GPT and AMY outperformed the conventional parameters as indicators of any instability in the process.     

Fungal tolerance to Congo red,a cell wall integrity stress,as a promising indicator of ecological niche

Differential sensitivities to the cell wall stress caused by Congo red (CR) have been observed in many fungal species. In this study, the tolerances and sensitivities to CR was studied with an assorted collection of fungal species from three phylogenetic classes: Sordariomycetes, Dothideomycetes, and Eurotiomycetes, three orders, and eight families. These grouped into different ecological niches, such as insect pathogens, plant pathogens, saprotrophs, and mycoparasitics. The saprotroph Aspergillus niger and the mycoparasite Trichoderma atroviride stood out as the most resistant species to cell wall stress caused by CR, followed by the plant pathogenic fungi, a mycoparasite, and other saprotrophs. The insect pathogens had low tolerance to CR. The insect pathogens Metarhizium acridum and Cordyceps fumosorosea were the most sensitive to CR. In conclusion, Congo red tolerance may reflect ecological niche, accordingly, the tolerances of the fungal species to Congo red were closely aligned with their ecology.     

Anaerobic induction of alanine aminotransferase in barley root tissue

Alanine aminotransferase, otherwise called glutamate-pyruvate aminotransferase (GPT), activity increases up to fourfold during several days of anaerobic induction in barley (Hordeum vulgare L.) roots, reaching a maximum activity of 13 international units per gram fresh weight. This increase in activity paralleled the increase in alcohol dehydrogenase activity in the same root tissue. Upon return to aerobic conditions, the induced GPT activity declined with an apparent half-life of 2 days. The isozyme profile of GPT in barley root tissue comprised one band of activity; in maize there were three bands of activity, the bands with greater mobility had much lower activity. Native polyacrylamide gel electrophoresis indicated that the induction of GPT activity results from an increase in the level of activity of these bands; no other activities were detected. When root tissue was induced under different levels of hypoxia (0%, 2%, 5%, and 21% O₂), changes in GPT activity were found to increase with lower levels of oxygen. Comparisons of GPT induction in barley, maize (Zea mays), rye, (Secale cereale) and wheat (Triticum aestivum) indicate that this enzyme is induced in the root tissue of all of these cereals; however, anaerobic root conditions do not result in the induction of GPT activity in leaf tissue. The dependence of GPT induction on high levels of nitrate in the media was tested by comparing activity levels in Hoagland solution and a nitrate-free nutrient solution. GPT activity was induced to similar levels under both conditions. These results indicate that alanine aminotransferase shows a very similar pattern of induction to alcohol dehydrogenase in barley root tissue and may be important in anaerobic glycolysis.     

Red cell glutamic-pyruvic transaminase polymorphism in a sample of the Italian population a new variant allele: GPT8.

247 individuals from Northern Italy have been tested for red cell glutamic-pyruvic transaminase (GPT) polymorphism. An abnormal phenotype has been detected. Family data support the hypothesis of the existence of a new variant allele, GPT8, at the GPT locus.     

Seed dispersal potential of Asian elephants

Elephants, the largest terrestrial mega-herbivores, play an important ecological role in maintaining forest ecosystem diversity. While several plant species strongly rely on African elephants (Loxodonta africana; L. cyclotis) as seed dispersers, little is known about the dispersal potential of Asian elephants (Elephas maximus). We examined the effects of elephant fruit consumption on potential seed dispersal using the example of a tree species with mega-faunal characteristics, Dillenia indica L., in Thailand. We conducted feeding trials with Asian elephants to quantify seed survival and gut passage times (GPT). In total, 1200 ingested and non-ingested control seeds were planted in soil and in elephant dung to quantify differences in germination rates in terms of GPT and dung treatment. We used survival analysis as a novel approach to account for the right-censored nature of the data obtained from germination experiments. The average seed survival rate was 79% and the mean GPT was 35 h. The minimum and maximum GPT were 20 h and 72 h, respectively. Ingested seeds were significantly more likely to germinate and to do so earlier than non-ingested control seeds (P = 0.0002). Seeds with the longest GPT displayed the highest germination success over time. Unexpectedly, seeds planted with dung had longer germination times than those planted without. We conclude that D. indica does not solely depend on but benefits from dispersal by elephants. The declining numbers of these mega-faunal seed dispersers might, therefore, have long-term negative consequences for the recruitment and dispersal dynamics of populations of certain tree species.     

Genetic polymorphism of red cell glutamate-pyruvate transaminase in Japanese

Six hundred and eight red cell hemolysates were screened for glutamate-pyruvate transaminase (GPT) by means of isoelectric focusing. Two new variant phenotypes were detected, neither of which could be distinguished from GPT2-1 and GPT2 by conventional starch gel electrophoresis. The two types were considered to correspond to GPT2B-1 and GPT2A-2C reported previously in samples of European origin.     

Cell wall glycosidase activities and protein content variations during fruit development and ripening in three texture contrasted tomato cultivars

Excessive softening is the main factor limiting fruit shelf life and storage. It is generally acceptable now that softening of fruit which occurs during the ripening is due to synergistic actions of several enzymes on cell wall polysaccharides. As a subject for this study, we have assayed some glycosidase activities using three tomato species (Lycopersicon esculentum) contrasted for their texture phenotypes; the cherry tomato line Cervil (Solanum lycopersicum var. cerasiforme), a common taste tomato line Levovil (S. lycopersicum Mill.) and VilB a modern line, large, firmer and with good storage capability. Four glycosidase activities namely α-galactosidase, β-galactosidase, β-mannosidase and β-glucosidase were extracted from tomato’s cell wall of the three species. Cell wall protein from fruits pericarp was extracted and compared among the three cultivars at the following stages; 14 days post anthesis (14DPA) fruit; 21 days post anthesis (21DPA), turning (breaker), red and over ripe. When glycolytic activities were also compared among these cultivars at the precited development stages, gross variations were noticed from stage to stage and also from species to species in accordance with the fruit firmness status. Interestingly, VilB cultivar, the firmer among the other two, though possessed the highest total protein content, exhibited the lowest enzymatic activities. Taken together, these results may therefore allow us to conclude that studies of glycolytic activities in a single tomato cultivar cannot be generalized to all species. On the other hand, relating fruit development to glycosidase activities should logically be coupled to these enzymes from cell wall compartment.     

Red cell glutamate-pyruvate transaminase gene frequencies in Gambia, West Africa.

The red cell GPT phenotypes have been determined in two village populations in Gambia, West Africa. A total of 887 people have been investigated. The results confirm the previous observations that the frequency of the GPT gene is far higher in African populations than Caucasian populations.     

Population genetics of red cell enzymes in Pygmies: a conclusive account

In the course of a long-term research project, three groups of Pygmies and some non-Pygmy Central Africans have been examined for the following red cell enzyme markers: ACP, PGM1, PGM2, PEPA, PEPB, and PEPC, AK, ADA, and PHI. Several other red cell enzymes (ESD, CA1 and CA2, GPT, GLO, and DIA1) have been studied in only some of these groups. This paper reports all the information we obtained, including what we have already published. The following conclusions can be drawn from the whole body of data: (1) Gene patterns of Pygmies are those typical of other Africans (e.g.: lack of ADA2 and AK2 genes, low GPT2 gene frequency, polymorphism of the CA2 locus, and presence at polymorphic frequencies of PEPA2 allele. (2) Superimposed on this African genetic makeup, a number of Pygmy characters were identified, namely, a private polymorphism for the PGM26 Pygmy allele and possibly one for the PEPC2 allele, and particularly high ACPR and low PGM12 gene frequencies. (3) Some markers, especially PGM1 and ACP, turned out also to discriminate efficiently among different groups of Pygmies.     

Alanine:glyoxylate aminotransferase activities in liver of Suncus murinus (insectivora)

1. The distribution of L-alanine:glyoxylate aminotransferase (AGT) activities were found in Suncus liver, 55% in particulate fraction and 45% in supernatant. 2. 65% of AGT activities in particulate were dependent on AGT isoenzyme 2 (AGT 2) having molecular weight 210,000, the remainder (35%) of AGT activities were dependent on AGT isoenzyme 1 (AGT 1) which have aminotransferase activity for serine. AGT activities in supernatant were dependent on AGT 1, AGT 2 and alanine:2-oxoglutarate aminotransferase (GPT), and their activity ratios were 10, 15 and 75%, respectively. 3. Km values for alanine were 0.52 mM; AGT 1, 3.3 mM; AGT 2, 0.88 mM; GPT measuring with AGT activity. AGT activity of GPT was inhibited by addition of glutamate and its Ki value was 1.8 mM. 4. Some other properties of AGT 1, AGT 2 and GPT are described.     

A recessive deletion in the GlcNAc-1-phosphotransferase gene results in peri-implantation embryonic lethality.

Formation of the dolichol oligosaccharide precursor is essential for the production of asparagine- (N-) linked oligosaccharides (N-glycans) in eukaryotic cells. The first step in precursor biosynthesis requires the enzyme UDP-GlcNAc: dolichol phosphate N-acetylglucosamine-1-phosphate transferase (GPT). Without GPT activity, subsequent steps necessary in constructing the oligosaccharide precursor cannot occur. Inhibition of this biosynthetic step using tunicamycin, a GlcNAc analog, produces a deficiency in N-glycosylation in cell lines and embryonic lethality during preimplantation development in vitro, suggesting that N-glycan formation is essential in early embryogenesis. In exploring structure-function relationships among N-glycans, and since tunicamycin has various reported biochemical activities; we have generated a germline deletion in the mouse GPT gene. GPT mutant embryos were analyzed and the phenotypes obtained were compared with previous studies using tunicamycin. We find that embryos homozygous for a deletion in the GPT gene complete preimplantation development and also implant in the uterine epithelium, but die shortly thereafter between days 4-5 postfertilization with cell degeneration apparent among both embryonic and extraembryonic cell types. Of cells derived from these early embryos, neither trophoblast nor embryonic endodermal lineages are able to survive in culture in vitro. These results indicate that GPT function is essential in early embryogenesis and suggest that N-glycosylation is needed for the viability of cells comprising the peri-implantation stage embryo.     

An analytical study of in vivo survival of limited populations of animal red blood cells tagged with radio-iron

Animal red blood cell in vivo survival curves, obtained by the radioiron tagging of populations of approximately the same age followed by the administration of non-radioactive iron to suppress radioiron reutilization, have been subjected to mathematical analysis on the basis of the three following assumptions:— (A) Red blood cells disappear from the circulation as the result of senescence: there is an average life span around which the life spans of individual cells are distributed in the usual way. (B) Red blood cells may be removed from the circulation by a process of random destruction which continuously removes a constant fraction of the cells present at any moment irrespective of age or other characteristics. (C) Under the conditions of the experiments described, a fraction of the radioiron, constant for each animal, is reutilized in new red cell formation when released by red cell destruction. This mathematical analysis indicates the following average life spans with the respective standard errors of the mean: dog 107 days ± 1.14; rabbit 67.6 days ± 1.94; cat 68.4 ± 1.50. The mathematical treatment presented has permitted a consideration of the theoretical variation of red cell life spans which was found in these experiments to be relatively small for all three species studied. In the rabbit and cat 2.5 per cent of tagged populations of red cells of the same age would theoretically have disappeared by senescence 17 days before the average life span was reached. The variation of red cell life in the dog was slightly less. Animals of the three species studied, in spite of apparently normal health, exhibited varying degrees of random destruction of both autogenous and transfused fresh normal homologous red cells. As yet, we have no explanation for this random loss of cells occurring in apparently healthy normal animals. The method of mathematical analysis presented is applicable to animal red cell survival studies employing radioiron in which differing rates of random destruction are operating in the removal of red cells.     

Genetic structures in the population of Veneto.

The genetic structures of the population residing in the provinces of Venice and Rovigo in the Veneto region at the north of the Po delta in Italy was studied in 1,210 individuals residing in 18 sampling areas, using the phenotype and gene frequencies of 7 red cell enzymes: acid phosphatase (ACP1), esterase D (ESD), glyoxalase I (GLOI), glutamic-pyruvic transaminase (GPT), 6-phosphogluconate dehydrogenase (6-PGD), phosphoglucomutase 1 (PGM1), and phosphoglycollate phosphatase (PGP). For the analysis of the distributions of phenotype and gene frequencies, standardized variance and kinship profiles were used. It was found that the genetic differentiation within each province is low, and that only two systems, GPT and PGP, are significantly different between the two provinces. The samples studied seem to belong to a mainly homogeneous population.     

Glutamic-pyruvic transaminase activity related to red blood cell age.

Red blood cell glutamic-pyruvic transaminase (GPT) phenotypes and catalytic activities were studied in normal subjects and in patients with various hemolytic syndromes associated with reticulocytosis. To assess the effect of cell age of GPT activity, young cells were separated from older cells by centrifugation, and the catalytic activities were compared. In normal blood, there was a progressive fall in GPT activity from the top layer (younger cells) to the bottom layer (older cells), with a mean ratio of 1.90 plus or minus 0.42. Similarly, in the blood of patients with reticulocytosis, the enzyme activity of the reticulocyte-rich layer was higher than that of the layer containing older cells (mean ratio 1.94 plus or minus 0.95).     

Threonine Affects Intestinal Function,Protein Synthesis and Gene Expression of TOR in Jian Carp (Cyprinus carpio var. Jian)

This study aimed to investigate the effects of threonine (Thr) on the digestive and absorptive ability, proliferation and differentiation of enterocytes, and gene expression of juvenile Jian carp (Cyprinus carpio var. Jian). First, seven isonitrogenous diets containing graded levels of Thr (7.4–25.2 g/kg diet) were fed to the fishes for 60 days. Second, enterocyte proliferation and differentiation were assayed by culturing enterocytes with graded levels of Thr (0–275 mg/l) in vitro. Finally, enterocytes were cultured with 0 and 205 mg/l Thr to determine protein synthesis. The percent weight gain (PWG), specific growth rate, feed intake, feed efficiency, protein retention value, activities of trypsin, lipase and amylase, weights and protein contents of hepatopancreas and intestine, folds heights, activities of alkaline phosphatase (AKP), γ- glutamyl transpeptidase and Na⁺/K⁺-ATPase in all intestinal segments, glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities in hepatopancreas, and 4E-BP2 gene expression in muscle, hepatopancreas and intestinal segments were significantly enhanced by Thr (p<0.05). However, the plasma ammonia concentration and TOR gene expression decreased (p<0.05). In vitro, Thr supplement significantly increased cell numbers, protein content, the activities of GOT, GPT, AKP and Na⁺/K⁺-ATPase, and protein synthesis rate of enterocytes, and decreased LDH activity and ammonia content in cell medium (p<0.05). In conclusion, Thr improved growth, digestive and absorptive capacity, enterocyte proliferation and differentiation, and protein synthesis and regulated TOR and 4E-BP2 gene expression in juvenile Jian carp. The dietary Thr requirement of juvenile Jian carp was 16.25 g/kg diet (51.3 g/kg protein) based on quadratic regression analysis of PWG.     

Species-related variations in tissue antioxidant status--I. Differences in antioxidant enzyme profiles.

1. Antioxidant enzyme activity profiles in red cells of man, rabbit, quail, pig and rat have been investigated and found to exhibit striking differences. 2. No direct correlations between activities of "functionally coupled" enzymes (superoxide dismutase/catalase and glutathione peroxidase/glutathione reductase) were apparent, suggesting their independent regulation. 3. However, activities of red cell catalase and glutathione peroxidase in the various species studied were inversely correlated. 4. This was most evident in quail red cells, which showed negligible catalase activity but the highest levels of glutathione peroxidase of all the species examined. 5. A significant positive correlation between catalase and glutathione reductase activities was also demonstrated. 6. This may be relevant to the suggestion that the binding of NADPH to catalase may serve to decrease the intracellular inactivation of this reducing cofactor which may be limiting in the glutathione reductase reaction. 7. Basal levels of glutathione, which have been claimed to be limiting for the glutathione peroxidase reaction, were found to correlate positively with the activity of this enzyme in red cells. 8. Myocardial tissues also exhibited species-related differences in antioxidant enzyme profiles but these did not bear any obvious relationship to patterns observed in the corresponding red cells.     

Respiratory enzyme activities correlate with anoxia tolerance in salt marsh grasses

Salt marsh communities are known for well-defined species zonation patterns. Lower limits of plant growth are thought to be set by an ability to tolerate anoxic sediments, but the physiological differences between species have not previously been examined. To investigate responses to anoxic sediments, several estuarine species were grown in greenhouse experiments to compare how respiratory processes were affected by flooding. Metabolic characteristics related to respiration and anoxia tolerance were studied in the emergent estuarine species Spartina alterniflora, S. anglica, S. densiflora, S. foliosa, S. alterniflora × S. foliosa hybrids, S. patens, and Distichlis spicata and compared to the inland species maize (Zea mays). All species showed a strong ability to respire anaerobically, indicating flooding tolerance. High intertidal marsh species had significantly higher root aerobic respiration enzyme activities compared to low intertidal species that may suggest lower aerobic demand in low marsh species. Some higher marsh species showed an apparent high sensitivity to sulfide that may be related to high cytochrome c oxidase activities. In contrast, the low marsh species S. alterniflora and S. anglica had lower aerobic respiration enzyme activities and a lower sensitivity to sulfide. Thus differences in aerobic demand and sulfide sensitivity may influence estuarine species zonation.