Activities Of Carbohydrate Metabolizing Enzymes Research Articles

Antidiabetic effects of nerolidol through promoting insulin receptor signaling in high-fat diet and low dose streptozotocin-induced type 2 diabetic rats.

The present study was designed to investigate the antidiabetic effect of nerolidol on high-fat diet and streptozotocin-induced diabetic rats. Type 2 diabetes was induced in animals by feeding them a high-fat diet for 4weeks and administering a single intraperitoneal dose of streptozotocin (35mg/kg body weight). Diabetic rats were treated with nerolidol (25mg/kg BW) for 28days. Results showed that nerolidol treatment significantly reduced (p < 0.05) the level of elevated glucose, glycosylated hemoglobin and improved (p < 0.05) the body weight and insulin level. Nerolidol also considerably improved (p < 0.05) the carbohydrate metabolic enzyme activities and increased the glycogen storage in the liver of diabetic rats. Increased serum triglycerides, total cholesterol (C), low-density lipoproteins-C and very low-density lipoproteins-C levels were significantly lowered (p < 0.05), while reduction of serum high-density lipoprotein-C was alleviated after administration of nerolidol. In addition, nerolidol attenuated oxidative stress markers by significantly increasing (p < 0.05) the levels of superoxide dismutase, catalase, reduced glutathione, and lowering (p < 0.05) the level of thiobarbituric acid reactive substances, and lipid hydroperoxide. Similarly, nerolidol showed its pharmacological effects against hepatic markers via restoring (p < 0.05) the alleviated level of alanine transaminase, aspartate aminotransferase, and alkaline phosphatase. Finally, it improved insulin-dependent glucose transport in skeletal muscle by enhancing and activating glucose transporter protein-4. These findings confirmed the antidiabetic potential of nerolidol in type 2 diabetic rats. This may be related to a high antioxidant capacity, the restoration of plasma insulin and lipid levels, and the activation of insulin signaling in STZ/HFD-induced diabetic rats.

Activity of Energy and Carbohydrate Metabolism Enzymes in the Juvenile Pink Salmon Oncorhynchus gorbuscha (Walb.) during the Transition from Freshwater to a Marine Environment

Biochemical adaptations of energy metabolism and some pathways of glucose oxidation during a change in salinity of the environment in larvae and smolts of the pink salmon Oncorhynchus gorbuscha (Walb.) inhabiting the White Sea were studied. We assayed the activity of energy and carbohydrate metabolism enzymes (cytochrome c oxidase (COХ), lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PDH), 1-glycerophosphate dehydrogenase (1-GPDH), and aldolase) in pink salmon larvae in a short-term aquarium experiment and in pink salmon smolts in a long-term cage experiment simulating the transition of juveniles from freshwater to a marine environment. A decrease in the activity of COX, LDH, 1‑GPDH, and aldolase already in the first hour after the transfer of larvae to seawater was shown. Smolts kept in the estuary and in the sea had low levels of activity of 1-GPDH and aldolase in comparison with individuals from the river. Most likely, in the salmon juveniles studied, there was a redistribution of carbohydrates between the reactions of aerobic and anaerobic metabolism in favor of anaerobic ATP synthesis. No changes in the enzyme activity of the pentose phosphate pathway, G-6-PDH, were found in either larvae or smolts compared with the individuals kept in freshwater. Maintenance of the required levels of anaerobic metabolism and of the pentose phosphate pathway is probably one of the mechanisms of biochemical adaptation of pink salmon to changes in salinity.

The effect of fullerenols on streptozotocin-induced diabetic rats

We support the general understanding that deleterious effects induced by hyperglycemia in rats would be alleviated by means of antioxidant treatment. Also, we have been supported and encouraged by many explorations on the usage of fullerenols for treating diabetic complications. Our present study aims to examine the potentials of fullerenols against diabetes in streptozotocin-induced diabetic rats. Animals were intraperitoneally administered with fullerenols for 15 days and then sacrificed. Following parameters were assessed: blood glucose, insulin concentration, levels of redox-related parameters, liver and kidney function biomarkers, glycogen contents, carbohydrate metabolic enzyme activities and histopathological analysis. As expected, fullerenols exhibited the well-known anti-oxidative property via decreasing MDA, increasing SOD, GSH-Px and CAT levels. Fullerenol treatment also showed a slight improvement in liver and kidney functional biomarkers, inferring a marginal hepatorenal protection. However, there were insignificant changes in levels of blood glucose, insulin, the pathological state of the necrotic islets. Herein, our results revealed that fullerenols failed to improve the function of pancreas and reverse the hyperglycemia in streptozotocin-induced diabetic rats in spite of a potent antioxidant role. Our study suggested that neither diabetes nor its complications could benefit from fullerenol administration.

Histopathological, hematological, and biochemical changes in high-latitude fish Phoxinus lagowskii exposed to hypoxia.

Hypoxia is one of the most significant threats to biodiversity in aquatic systems. The ability of high-latitude fish to tolerate hypoxia with histological and physiological responses is mostly unknown. We address this knowledge gap by investigating the effects of exposures to different oxygen levels using Phoxinus lagowskii (a high-latitude, cold-water fish) as a model. Fish were exposed to different oxygen levels (0.5 mg/L and 3 mg/L) for 24 h. The loss of equilibrium (LOE), an indicator of acute hypoxia tolerance, was 0.21 ± 0.01 mg/L, revealing the ability of fish to tolerate low-oxygen conditions. We sought to determine if, in P. lagowskii, the histology of gills and liver, blood indicators, enzyme activities of carbohydrate and lipid metabolism, and antioxidants changed to relieve stress in response to acute hypoxia. Notably, changes in vigorous jumping behavior under low oxygen revealed the exceptional hypoxia acclimation response compared with other low-latitude fish. A decrease in blood parameters, including RBC, WBC, and Hb, as well as an increase in MCV was observed compared to the controls. The increased total area in lamella and decreased ILCM volume in P. lagowskii gills were detected in the present study. Our results also showed the size of vacuoles in the livers of the hypoxic fish shrunk. Interestingly, an increase in the enzyme activity of lipid metabolism but not glucose metabolism was observed in the groups exposed to hypoxia at 6 h and 24 h. After combining histology and physiology results, our findings provide evidence that lipid metabolism plays a crucial role in enhancing hypoxia acclimation in P. lagowskii. Additionally, SOD activity significantly increased during hypoxia, suggesting the presence of an antioxidant response of P. lagowskii during hypoxia. High expression levels of lipogenesis and lipolysis-related genes were detected in the 6 h 3 mg/L and 24 h 3 mg/L hypoxia group. Enhanced expression of lipid-metabolism genes (ALS4, PGC-1, and FASN) was detected during hypoxia exposure. Together, these data suggest that P. lagowskii's ability to tolerate hypoxic events is likely mediated by a comprehensive strategy.

Oral Nigella sativa oil administration alleviates arsenic-induced redox imbalance, DNA damage, and metabolic and histological alterations in rat liver.

Arsenic, an omnipresent environmental contaminant, is regarded as a potent hepatotoxin. Nigella sativa oil (NSO) consumption has been shown to improve hepatic functions in various in vivo models of acute hepatic injury. The present study evaluates the protective efficacy of NSO against sodium arsenate (As)-induced deleterious alterations in the liver. Male Wistar rats were divided into four groups, namely, control, As, NSO, and AsNSO. After pre-treating rats in AsNSO and NSO groups with NSO (2 mL/kg bwt, orally) for 14 days, NSO treatment was further extended for 30 days, with and without As treatment (5 mg/kg bwt, orally), respectively. As induced an upsurge in serum ALT and AST activities indicating liver injury, as also confirmed by the histopathological findings. As caused significant alterations in the activities of membrane marker enzymes and carbohydrate metabolic enzymes, and in the vital components of antioxidant defense system. Marked DNA damage and hepatic arsenic accumulation were also observed in As-treated rats. Oral NSO administration ameliorated these deleterious alterations and improved overall hepatic antioxidant and metabolic status in As-treated rats. Prevention of oxidative damage could be the underlying mechanism of NSO-mediated protective effects. The results suggest that NSO could be a useful dietary supplement in the management of arsenic hepatotoxicity.

Elevated carbon dioxide alleviates the negative impact of drought on wheat by modulating plant metabolism and physiology

This study was conducted to understand the mechanism of wheat yield decrease under drought stress and the role of CO2 in modulating physiological and metabolic drought effects. Wheat was grown under ambient and elevated CO2 (400 and 800 ppm, respectively), and plants were subjected to drought stress prior to anthesis. Photosynthetic rate (An), stomatal conductance (Gs), transpiration rate (E) and activities of carbohydrate metabolic enzymes were decreased in leaf and increased in spikes during drought. Total antioxidant potential (TAP) was decreased under drought both in leaf and spike. Grain yield parameters were again reduced under drought, while An, E and most of the yield traits were increased under elevated CO2. The number of grains spike-1 correlated positively with An, TAP and cell wall invertase activity, while it negatively correlated with ascorbate peroxidase, cell wall peroxidase and glutathione reductase activities in leaves. Thousand kernel weight positively correlated with leaf phosphoglucoisomerase and spike glucose-6-phosphate dehydrogenase activities. This indicates that elevated CO2 could boost CO2 assimilation through an increase in antioxidant potential and facilitate more photosynthate supply via various increased carbohydrate metabolic enzyme activities, and thus increases yield. This could be a possible mechanism of grain yield increase caused by elevated CO2.

Coexistence of Lateriporus teres (Cestoda: Dilepididae) and Polymorphus phippsi (Palaeacanthocephala: Polymorphidae) in the intestine of common eider

The purpose of the research is studying the peculiarities of parasite infection of the cestodes Lateriporus teres Krabbe, 1869 (Cestoda: Dilepididae) and acanthocephalans Polymorphus phippsi Kostylew, 1922 (Palaeacanthocephala: Polymorphidae) during coexistence in the intestine of the common eider, particularly, the localization of these parasites, the activity of protein and carbohydrate metabolism enzymes on the tegument of the worms, the degree of parasite influence on the host digestion, as well as to assess total digestive activity in the gastrointestinal tract of birds infected with these helminths.Materials and methods. Using methods of biochemical analysis, the activity of digestive enzymes (protease and glycosidase) and the intensity of a digestion with the participation of these enzymes along the intestine of the common eider were determined. The digestive activity of enzymes in the body of helminthes was measured, and the intensity of membrane digestion on the surface of their tegument was estimated.Results and discussion. During coexistence, L. teres were observed mainly in the proximal parts of the intestine of the birds, P. phippsi in the distal parts. Membrane digestion, involving the action of proteases and glycosidases, occurred on the surface of the tegument of both cestodes and acanthocephalans. The protein metabolism intensity in both helminth species was nearly the same, but the glycosidase activity was higher on the tegument of L. teres. The glycosidase activity in the body of the acanthocephalans exceeded that in the cestodes strobile six times. In the intestine parts inhabited by L. teres, both protease and glycosidase activity decreased. In the intestine parts where P. phippsi parasitized, protease activity increased in the intestinal mucosa of the common eider. The total activity of protease and glycosidase along the entire length of the intestine in common eider infected with L. teres and P. phippsi was lower compared to the uninfected birds.

Polystyrene microplastics disturb the redox homeostasis, carbohydrate metabolism and phytohormone regulatory network in barley

As emerging contaminants, microplastics (mPS, <5 mm) have been reported to adversely affect the plant growth; however, the mechanisms of mPS-induced growth limitation are rarely known. Here, it was found that the plastic particles were absorbed and accumulated in barley plants, which limited the development of rootlets. The mPS-treated plants had significantly higher concentrations of H2O2 and O2- in roots than the control. The mPS significantly increased the activities of dehydroascorbate reductase, glutathione reductase, ADP-Glucose pyrophosphorylase, fructokinase and phosphofructokinase, while decreased the activities of cell wall peroxidase, vacuolar invertase, sucrose synthase, phosphoglucomutase, glucose-6-phosphate dehydrogenase and phosphoglucoisomerase in roots. The changes in activities of carbohydrate and ROS metabolism enzymes in leaves showed a different trend from that in roots. The mPS plants possessed a higher trans-zeatin concentration while lower concentrations of indole-3-acetic acid, indole-3-butyric acid and dihydrozeatin than the control plants in leaves. However, the phytohormone changes in roots were distinct from those in leaves under mPS. In addition, significant correlations between enzyme activities and phytohormone concentrations were found. It was suggested that the phytohormone regulatory network plays key roles in regulating the activities of key enzymes involved in carbohydrate and ROS metabolisms in response to mPS in barley.

Induction of Low Temperature Tolerance in Wheat by Pre-Soaking and Parental Treatment with Melatonin

Low temperatures seriously depress germination and seedling establishment in wheat and it is of great significance to explore approaches to improve wheat tolerance to low temperatures. In this study, the effects of seed pre-soaking and parental treatment with melatonin on seed germination and low temperature tolerance during the early growing stage in wheat were studied. The results showed that pre-soaking with melatonin increased the germination rate, improved antioxidant capacity and accelerated starch degradation under low temperature, which alleviated low temperature-induced damage to the chloroplasts in coleoptiles of wheat seedlings. Parental melatonin treatment during grain filling stage significantly decreased the grain weight. Seeds from parental melatonin-treated plants showed higher germination rates and higher antioxidant enzyme activity than the control seeds under low temperature. In addition, parental treatment with melatonin modulated the activities of carbohydrate metabolism enzymes, which contributes to enhanced low temperature tolerance in wheat offspring. It was suggested that both seed pre-soaking and parental treatment with melatonin could be the effective approaches for low temperature tolerance induction in wheat.

Hepatoprotective Effects of Polydatin-Loaded Chitosan Nanoparticles in Diabetic Rats: Modulation of Glucose Metabolism, Oxidative Stress, and Inflammation Biomarkers.

Polydatin (PD) has a broad range of pharmacological activities; however, its effects on diabetic liver damage are poorly studies. This work is aimed to explore possible protective effects of polydatin-loaded chitosan nanoparticles (PD-CSNPs) or PD against liver damage associated with diabetes. Diabetes was induced in rats using nicotinamide/streptozotocin treatment. Diabetic rats were then divided into six groups: normal control rats, diabetic control rats, and rats orally treated with PD, PD-CSNPs, equivalent unloaded CSNPs, or metformin daily for 4 weeks. Treatment with PD and PD-CSNPs significantly reduced the blood glucose content, lipid peroxidation in the liver, and activities of serum transaminases and carbohydrate metabolism enzymes (including succinate dehydrogenase and pyruvate kinase); by contrast, liver glycogen content, glutathione concentration, and activities of the antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase, and glucose-6-phosphate dehydrogenase) were markedly increased compared with the control diabetic rats. Furthermore, expression of the tumor necrosis factor α and interleukin-1β mRNAs was significantly downregulated, while expression of glucose transporter 2 and glucokinase mRNAs was strongly upregulated vs. control diabetic rats. We concluded that PD-CSNPs and PD ameliorate diabetic liver damage by modulating glucose transporter 2 expression, affecting the activity of carbohydrate metabolism enzymes, and suppressing oxidative stress and inflammation, PD-CSNPs being more efficient than PD, probably due to higher bioavailability and prolonged release.

Effect of Exogenous Gibberellin, Paclobutrazol, Abscisic Acid, and Ethrel Application on Bulblet Development in Lycoris radiata.

Lycoris species have great ornamental and medicinal values; however, their low regeneration efficiency significantly restricts their commercial production. Exogenous hormone application is an effective way to promote bulblet development, but their effect on Lycoris radiata has not been verified to date. In the present study, we examined the effect of different exogenous hormones on bulblet development in L. radiata, and found that gibberellic acid (GA) significantly inhibited, whereas paclobutrazol (PBZ), abscisic acid (ABA), and ethrel promoted bulblet development, especially PBZ, a GA biosynthesis inhibitor. Furthermore, GA reduced endogenous cytokinin (CK) content, as well as the activities of carbohydrate metabolism enzymes, including sucrose synthase (SUS) and glucose-1-phosphate adenylyltransferase (AGPase), by downregulating the expression levels of LrSUS1, LrSUS2, and genes encoding AGPase large and small subunits. This resulted in the decrease in carbohydrate accumulation in the bulblets, thus hindering their development. PBZ had the opposite effect to GA on carbohydrate metabolism; it decreased endogenous GA15 and GA24, thereby promoting bulblet development. ABA promoted endogenous auxin content and the activities of starch synthesis enzymes, especially soluble starch synthase (SSS) and granule-bound SS (GBSS), through the up-regulation of the expression levels of LrSS1, LrSS2, and LrGBSS1 genes, which could also result in the accumulation of carbohydrates in the bulblets and promote their development. In addition, ethrel application partly promoted bulblet development by promoting endogenous CK content. Although the accumulation of carbohydrates and the activity of starch enzymes were increased by ethrel treatment, we hypothesized that the effect of ethrel on regulating carbohydrate metabolism may be indirect. Our results could provide a basis for improving the propagation efficiency of L. radiata for production, as well as propose some directions for future research.

Impaired chloroplast positioning affects photosynthetic capacity and regulation of the central carbohydrate metabolism during cold acclimation

Photosynthesis and carbohydrate metabolism of higher plants need to be tightly regulated to prevent tissue damage during environmental changes. The intracellular position of chloroplasts changes due to a changing light regime. Chloroplast avoidance and accumulation response under high and low light, respectively, are well known phenomena, and deficiency of chloroplast movement has been shown to result in photodamage and reduced biomass accumulation. Yet, effects of chloroplast positioning on underlying metabolic regulation are less well understood. Here, we analysed photosynthesis together with metabolites and enzyme activities of the central carbohydrate metabolism during cold acclimation of the chloroplast unusual positioning 1 (chup1) mutant of Arabidopsis thaliana. We compared cold acclimation under ambient and low light and found that maximum quantum yield of PSII was significantly lower in chup1 than in Col-0 under both conditions. Our findings indicated that net CO2 assimilation in chup1 is rather limited by biochemistry than by photochemistry. Further, cold-induced dynamics of sucrose phosphate synthase differed significantly between both genotypes. Together with a reduced rate of sucrose cycling derived from kinetic model simulations our study provides evidence for a central role of chloroplast positioning for photosynthetic and metabolic acclimation to low temperature.

Abscisic acid-mimicking ligand AMF4 induced cold tolerance in wheat by altering the activities of key carbohydrate metabolism enzymes

AMF4, a recently synthetic ABA-mimicking ligand, has been reported to have long-lasting effects in inducing the expression of stress-responsive genes, hence conferring abiotic tolerance in plants. To test the effect of AMF4 on cold tolerance induction, the wheat plants were firstly foliar sprayed with AMF4 (10 μM), then the AMF4 treated and the control plants were exposed to a 24-h low temperature treatment (2/0 °C). Under low temperature stress, the AMF plants possessed significantly higher relative water content, membrane stability index and ATP concentration in leaf, while lower leaf H2O2 concentration, compared with the control plants. The AMF4 treatment significantly increased the activities of APX, Ca2+-ATPase in the chloroplasts, while decreased SOD activity under low temperature, in relation to the control plants. In addition, the AMF plants showed significantly higher activities of key carbohydrate metabolism enzymes, such as UDP-glucose pyrophorylase, hexokinase, fructokinase, ADP-Glucose pyrophosphorylase, phosphoglucomutase, glucose-6-phosphate dehydrogenase and phosphoglucoisomerase, in relation to the control plants under low temperature. These results demonstrate that AMF4 could be used to induce cold tolerance in wheat, and provide novel insights into the potential ways to enhance abiotic stress tolerance using the synthetic ABA-mimicking ligands.

Early-stage sugar beet taproot development is characterized by three distinct physiological phases.

Despite the agronomic importance of sugar beet (Beta vulgaris L.), the early‐stage development of its taproot has only been poorly investigated. Thus, the mechanisms that determine growth and sugar accumulation in sugar beet are largely unknown. In the presented study, a physiological characterization of early‐stage sugar beet taproot development was conducted. Activities were analyzed for fourteen key enzymes of carbohydrate metabolism in developing taproots over the first 80 days after sowing. In addition, we performed in situ localizations of selected carbohydrate‐metabolic enzyme activities, anatomical investigations, and quantifications of soluble carbohydrates, hexose phosphates, and phytohormones. Based on the accumulation dynamics of biomass and sucrose, as well as on anatomical parameters, the early phase of taproot development could be subdivided into three stages—prestorage, transition, secondary growth and sucrose accumulation stage—each of which was characterized by distinct metabolic and phytohormonal signatures. The enzyme activity signatures corresponding to these stages were also shown to be robustly reproducible in experiments conducted in two additional locations. The results from this physiological phenotyping approach contribute to the identification of the key regulators of sugar beet taproot development and open up new perspectives for sugar beet crop improvement concerning both physiological marker‐based breeding and biotechnological approaches.

In Vitro and In Vivo Anti-diabetic Activity of Fractions Obtained from the Unexplored Hedychium coronarium Rhizome

Despite the availability of numerous medicines for diabetes treatment, compounds derived from plants are gaining popularity due to their lesser side effects. The present investigation was carried out to determine the anti-diabetic activity of a terpenoid-rich fraction obtained from the rhizomes of Hedychium coronarium under in vitro and in vivo. The authors performed in vitro assays to determine glucose uptake in insulin-resistant cell lines. Further, the effect of terpenoid fraction was tested using albino Wistar rats. The streptozotocin-induced diabetic rats were treated with different concentrations of most active fraction, and results were compared with the standard drug insulin. At regular intervals, the blood glucose level and the bodyweight of the rats were monitored. The serum, biochemical and histological parameters related to the liver and kidney were also estimated. The fraction at 10 mg/kg.b.wt. has shown a significant reduction in blood glucose level and an increase in bodyweight. This specific concentration increases the activity of antioxidant enzymes, but reduces the activity of carbohydrate-metabolizing enzymes leading to normal blood glucose level. The normal cellular architecture of liver and kidney tissue was also retained. The significant observations obtained from both in vitro and in vivo studies suggest the potential role of terpene-rich fraction obtained from H. coronarium rhizomes in the treatment of diabetes. It also inferred that the fraction controls diabetes by regulating various parameters associated with diabetes-related complications.

Types of carbohydrate in feed affect the growth performance, antioxidant capacity, immunity, and activity of digestive and carbohydrate metabolism enzymes in juvenile Macrobrachium nipponense

The present study evaluated the effect of different sources of dietary carbohydrate on the growth, immunity, antioxidant capacity, and digestive enzyme and carbohydrate metabolism enzyme activities in the juvenile oriental river prawn, Macrobrachium nipponense. The experimental diets, which comprised raw maize starch, pregelatinized maize starch, dextrin, maltose, glucose or cellulose, were fed to juvenile prawns for 56 days, respectively. We found that prawns fed with starch, dextrin or maltose achieved better growth. The highest digestive enzyme activities were noted in prawns fed with starch or dextrin. Furthermore, the prawns fed with starch, dextrin or maltose exhibited significantly higher levels of hepatopancreas hexokinase (HK) and phosphofructokinase (PFK) activities. Phosphoenolpyruvate carboxykinase (PEPCK) activity was higher in prawns fed with dextrin, maltose or cellulose, and higher glucose-6-phosphate dehydrogenase (G6PDH) activities were observed in prawns fed with starch or dextrin. We further evaluated the effect of different dietary carbohydrate sources on antioxidant capacity and immune competence. Prawns supplied with starch exhibited superior activities of superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (T-AOC), lysozyme and respiration burst, and had lower level of maleic dialdehyde (MDA). In summary, the dietary addition of starch is a promising option for juvenile prawn farming, given its positive effect on the growth, glycolysis, pentose phosphate pathway, antioxidant activity and immunity of prawns.

The changes of activity of separate carbohydrate metabolism enzymes in blood erythrocytes of pregnant rats under vanadium citrate

The aim of the work was to study the effect of vanadium citrate on the activity of glucose-6-phosphate dehydrogenase, lactate dehydrogenase, estradiol content and to establish correlations between the activity of the studied enzymes and the estradiol content in pregnant female rats under the effect of vanadium compound. The study was carried out on 25 female Wistar rats, divided into five groups: group I - non-pregnant, group II - pregnant consuming pure water without additives, groups III, IV, V - females which during the mating and pregnancy periods received the solution of vanadium citrate at the concentrations of 3.75, 15.63 and 62.5 μgV/kg of body weight, respectively. Glucose-6-phosphate dehydrogenase, lactate dehydrogenase and estradiol content increase in pregnant females of group II compared to group I of non-pregnant animals. In pregnant females, the effect of vanadium citrate resulted in the decrease in the activity of glucose-6-phosphate dehydrogenase and lactate dehydrogenase in the blood of animals in groups IV and V, and the content of estradiol in the animals of all three experimental groups (III, IV, V), compared to group II of pregnant females. The values of glucose-6-phosphate dehydrogenase activity in the animals of group IV, which received the solution of vanadium citrate at the concentration of 15.63 μgV/kg of body weight, was similar to that of the animals in group I. This may indicate the normalizing effect of vanadium citrate on the activity of glucose-6-phosphate dehydrogenase at the indicated concentration, which is probably due to the ability of the vanadium microelement to inhibit the activity of this enzyme. Vanadium citrate at the concentration of 15.63 μgV/kg of body weight caused the recovery of the enzyme activity to the values of the activity in group І.

Responses of carbohydrate metabolism enzymes in leaf and spike to CO2 elevation and nitrogen fertilization and their relations to grain yield in wheat

Elevated CO2 generally increases wheat grain yield, which may be affected by nitrogen fertilization. The aim of this study was to investigate the responses of carbohydrate metabolism enzymes in source leaves and sink spikes in wheat to elevated CO2 and nitrogen fertilization and their relation to grain yield. The wheat plants were grown at different atmospheric [CO2] (400 and 800 ppm) and nitrogen fertilizer rates, and the activities of 13 key carbohydrate metabolism enzymes, carbon and nitrogen concentrations in leaves and spikes, and grain yield were analyzed. Elevated CO2 (e[CO2]) increased the photosynthetic rate while decreased the chlorophyll content in flag leaf, compared with plants grown at ambient CO2 (a[CO2]). In source leaf, activity of invertase, including vacInv and cwInv, were depressed by e[CO2]. In leaf the PGI activity was enhanced, while the Ald activity was reduced by high N, compared with normal N supply. Among the enzymes involved in starch biosynthesis, only PGM activity was enhanced by e[CO2] in spike, compared with those grown at a[CO2]. For the glycolysis pathway in spike, the PFK activity was not affected by e[CO2], but the Ald activity was promoted by e[CO2], in relation to those grown at a[CO2]. Grain yield and shoot biomass were significantly enhanced by e[CO2], compared with a[CO2]. In addition, high N supply enhanced the grain number per spike in wheat grown under e[CO2]. The activities of major carbohydrate metabolism enzymes in source and sink organs show different responses to e[CO2] and N fertilizer rates, which could have contributed to the changes in grain yield. The variation in N supply could be a key contributing factor to the variable responses of wheat grain yield to e[CO2].

Effect of Dietary Carbohydrate/Protein Ratios and Feeding Frequency on Carbohydrate Metabolism of Common Carp

A 8-week 3×2 two-factorial experiment was conducted to investigate effects of dietary carbohydrate to protein ratio (C5%/P32%, C10%/P30%, C20%/P28%) and feeding frequencies (fourth daily and twice daily) on the hepatic carbohydrate metabolic enzyme activities, regulatory factor contents related to glycometabolism, the insulin receptor (IR), GLUT2, hexokinase (HK), GLUT2 and SGLTlmRNA expression levels of common carp with initial average weight of 55.37±3.55 g. Three replicates with 150 common carp were randomly allotted to one treatment with combination of dietary carbohydrate level and feeding frequency in a complete randomized design. The results indicated that: (1) Dietary C/P ratio and feeding frequency significantly influenced the amylase activities of midgut (P<0.05). Amylase activities of midgut of fish fed fourth daily were significantly lower than those fed twice daily (P<0.05). (2) The phosphofructokinase (PFK) and glucose 6 phosphate dehydrogenase (G6PD) activities were significantly affected only by dietary C/P ratio. In addition, the phosphoenolpyruvate carboxykinase (PEPCK) and Glycogen synthase (GS) activities were significantly affected by dietary C/P ratio and feeding frequency, and there was a significant positive correlation between those activities and dietary C/P ratio (P<0.05). (3) The IR, GLUT2 and HK mRNA expression levels of hepatopancreas and GLUT2 and SGLT1 mRNA expression levels of intestine were significantly affected by dietary C/P ratio and feeding frequency, which were significantly increased with increasing feeding frequency (P<0.05). Furthermore, the highest values of those expression levels were observed in the C10%/P30% group and these were significantly higher than those in other groups (P<0.05). Above all, fish fed C10%/P30% diet was suitable with feeding frequency at fourth daily in this study.

Evaluation of biochemical mechanisms of anti-diabetic functions of Anisomeles malabarica

Anisomeles malabarica (AM) is an aromatic plant traditionally used for the treatment of diabetes mellitus in India. Following bioassay guided fractionation, we recently identified an active fraction of AM (AMAF, with potential mix of active principles) that showed significant antihyperglycemic and antihyperlipidemic activities. In addition, AMAF treatment improved insulin levels. However, the biochemical mechanism/s through which AMAF demonstrates the antidiabetic effects is largely unknown. Based on its beneficial effects we investigated the biochemical mechanism of the anti-diabetic activity of A.malabarica active fraction (AMAF) in streptozotocin (STZ) induced diabetic rats. Streptozotocin induced diabetic rats were treated with AMAF (50 mg AMAF/kg/day) for 30 days and alterations in the body weights, glycogen and protein content of tissues, functional markers of hepatic and renal tissues, carbohydrate metabolic enzymes and their genes expression were evaluated. Lipid peroxides levels and activities of antioxidant enzymes of hepatic and renal tissues were also measured. The AMAF treatment resulted in increase in body weights, hepatic and renal protein and tissue glycogen levels in diabetic treated rats compared to diabetic rats. In addition, the treatment improved activities of carbohydrate metabolic enzymes, antioxidant enzymes and, liver and renal functional markers in the AMAF treated diabetic rats. Gene expressions of key carbohydrate metabolic enzymes/factors glucokinase, glucose transporter protein (GLUT-2) and phosphoenolpyruvate carboxykinase (PEPCK) were also normalized up on AMAF treatment in diabetic rats. Our studies indicate that the isolated active fraction of AM (AMAF) from the leaves of A.malabarica positively regulated the glucose homeostasis and oxidative stress through carbohydrate metabolism and antioxidant enzyme activities respectively in hepatic and renal tissues.