植物CytP450和抗氧化酶对土壤低浓度菲、芘胁迫的响应

Wheat (Triticum aestivum) was chosen to analyze the effect of two polycyclic aromatic hydrocarbons (PAHs), Phenanthrene (PHE) and Pyrene (PY) in brown meadow soil at low concentrations. The effects of PHE and PY were determined by analyzing the changes in activity of Cytochrome P450 (CytP450) and antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Results indicated that both PHE and PY caused changes in activity of CytP450 and the antioxidant enzymes, SOD, POD and CAT. CytP450 activity was significantly stimulated with 1 mg kg-1 of both PHE and PY individually and significantly inhibited with 4 mg kg-1, which showed that pollution stress of PHE or PY can damage the metabolism and detoxification systems of plants. Moreover, as PHE and PY combined at 1 mg kg-1, CytP450 was increased significantly more than when PHE and PY were applied individually, which illustrates obvious synergistic effects. No significant variation were found in activity of SOD in response to individual exposure of PHE or PY in soil, but SOD activity decreased slightly in response to a combined PHE and PY exposure. Great decrease variation was found in CAT and POD activity in response to individual exposure of PHE or PY in soil. No enhanced toxic effects were shown by POD in response to a PHE and PY combined exposure, however CAT showed increased inhibition. From the aspects of metabolism and detoxification as well as antioxidant enzyme activity, our study has provided experimental basis for the pollution diagnosis of PAHs in soils at low concentrations.

The influence of genetic background on the induction of oxidative stress and impaired insulin secretion in mouse islets

Aims/hypothesis We determined whether high-glucose-induced beta cell dysfunction is associated with oxidative stress in the DBA/2 mouse, a mouse strain susceptible to islet failure.

Materials and methods Glucose- and non-glucose-mediated insulin secretion from the islets of DBA/2 and control C57BL/6 mice was determined following a 48-h exposure to high glucose. Flux via the hexosamine biosynthesis pathway was assessed by determining O-glycosylated protein levels. Oxidative stress was determined by measuring hydrogen peroxide levels and the expression of anti-oxidant enzymes.

Results Exposure to high glucose levels impaired glucose-stimulated insulin secretion in DBA/2 islets but not C57BL/6 islets, and this was associated with reduced islet insulin content and lower ATP levels than in C57BL/6 islets. Exposure of islets to glucosamine for 48 h mimicked the effects of high glucose on insulin secretion in the DBA/2 islets. High glucose exposure elevated O-glycosylated proteins; however, this occurred in islets from both strains, excluding a role for O-glycosylation in the impairment of DBA/2 insulin secretion. Additionally, both glucosamine and high glucose caused an increase in hydrogen peroxide in DBA/2 islets but not in C57BL/6 islets, an effect prevented by the antioxidant N-acetyl-l-cysteine. Interestingly, while glutathione peroxidase and catalase expression was comparable between the two strains, the antioxidant enzyme manganese superoxide dismutase, which converts superoxide to hydrogen peroxide, was increased in DBA/2 islets, possibly explaining the increase in hydrogen peroxide levels.

Conclusions/interpretation Chronic high glucose culture caused an impairment in glucose-stimulated insulin secretion in DBA/2 islets, which have a genetic predisposition to failure, and this may be the result of oxidative stress.

Glutathione peroxidase-1 reduces influenza A virus-induced lung inflammation

Oxidative stress caused by excessive reactive oxygen species production is implicated in influenza A virus–induced lung disease. Glutathione peroxidase (GPx)-1 is an antioxidant enzyme that may protect lungs from  such damage. The objective of this study was to determine if GPx-1 protects the lung against influenza A virus–induced lung inflammation in vivo.

Disassociation of muscle triglyceride content and insulin sensitivity after exercise training in patients with Type 2 diabetes

Aim/hypothesis. We determined the effect of exercise training on insulin sensitivity and muscle lipids (triglyceride [TGm] and long-chain fatty acyl CoA [LCACoA] concentration) in patients with Type 2 diabetes. Methods. Seven patients with Type 2 diabetes and six healthy control subjects who were matched for age, BMI, % body fat and VO2peak participated in a 3 days per week training program for 8 weeks. Insulin sensitivity was determined pre- and post-training during a 120 min euglycaemic- hyperinsulinaemic clamp and muscle biopsies were obtained before and after each clamp. Oxidative enzyme activities [citrate synthase (CS), β-hydroxy-acyl- CoA (β-HAD)] and TGm were determined from basal muscle samples pre- and post training, while total LCACoA content was measured in samples obtained before and after insulin-stimulation, pre- and post training. Results. The training-induced increase in VO2peak (∼20%, p<0.01) was similar in both groups. Compared with control subjects, insulin sensitivity was lower in the diabetic patients before and after training (∼60%; p<0.05), but was increased to the same extent in both groups with training (∼30%; p<0.01). TGm was increased in patients with Type 2 diabetes (170%; p<0.05) before, but was normalized to levels observed in control subjects after training. Basal LCACoA content was similar between groups and was unaltered by training. Insulin-stimulation had no detectable effect on LCACoA content. CS and β-HAD activity were increased to the same extent in both groups in response to training (p<0.001). Conclusion/interpretation. We conclude that the enhanced insulin sensitivity observed after short-term exercise training was associated with a marked decrease in TGm content in patients with Type 2 diabetes. However, despite the normalization of TGm to levels observed in healthy individuals, insulin resistance was not completely reversed in the diabetic patients.

Muscle oxidative capacity is a better predictor of insulin sensitivity than lipid status

We determined whole-body insulin sensitivity, long-chain fatty acyl coenzyme A (LCACoA) content, skeletal muscle triglyceride (TGm) concentration, fatty acid transporter protein content, and oxidative enzyme activity in eight patients with type 2 diabetes (TYPE 2); six healthy control subjects matched for age (OLD), body mass index, percentage of body fat, and maximum pulmonary O2 uptake; nine well-trained athletes (TRAINED); and four age-matched controls (YOUNG). Muscle biopsies from the vastus lateralis were taken before and after a 2-h euglycemic-hyperinsulinemic clamp. Oxidative enzyme activities, fatty acid transporters (FAT/CD36 and FABPpm), and TGm were measured from basal muscle samples, and total LCACoA content was determined before and after insulin stimulation. Whole-body insulin-stimulated glucose uptake was lower in TYPE 2 (P < 0.05) than in OLD, YOUNG, and TRAINED. TGm was elevated in TYPE 2 compared with all other groups (P < 0.05). However, both basal and insulin-stimulated skeletal muscle LCACoA content were similar. Basal citrate synthase activity was higher in TRAINED (P < 0.01), whereas β-hydroxyacyl CoA dehydrogenase activity was higher in TRAINED compared with TYPE 2 and OLD. There was a significant relationship between the oxidative capacity of skeletal muscle and insulin sensitivity (citrate synthase, r = 0.71, P < 0.001; β-hydroxyacyl CoA dehydrogenase, r = 0.61, P = 0.001). No differences were found in FAT/CD36 protein content between groups. In contrast, FABPpm protein was lower in OLD compared with TYPE 2 and YOUNG (P < 0.05). In conclusion, despite markedly elevated skeletal muscle TGm in type 2 diabetic patients and strikingly different levels of whole-body glucose disposal, both basal and insulin-stimulated LCACoA content were similar across groups. Furthermore, skeletal muscle oxidative capacity was a better predictor of insulin sensitivity than either TGm concentration or long-chain fatty acyl CoA content.

N-fixing trees in restoration plantings: effects on nitrogen supply and soil microbial communities

Mixed-species restoration tree plantings are being established increasingly, contributing to mitigate climate change and restore ecosystems. Including nitrogen (N)-fixing tree species may increase carbon (C) sequestration in mixed-species plantings, as these species may substantially increase soil C beneath them. We need to better understand the role of N-fixers in mixed-species plantings to potentially maximize soil C sequestration in these systems. Here, we present a field-based study that asked two specific questions related to the inclusion of N-fixing trees in a mixed-species planting: 1) Do non-N-fixing trees have access to N derived from fixation of atmospheric N2 by neighbouring N-fixing trees? 2) Do soil microbial communities differ under N-fixing trees and non-N-fixing trees in a mixed-species restoration planting? We sampled leaves from the crowns, and litter and soils beneath the crowns of two N-fixing and two non-N-fixing tree species that dominated the planting. Using the 15N natural abundance method, we found indications that fixed atmospheric N was utilized by the non-N-fixing trees, most likely through tight root connections or organic forms of N from the litter layer, rather than through the decomposition of N-fixers litter. While the two N-fixing tree species that were studied appeared to fix atmospheric N, they were substantially different in terms of C and N addition to the soil, as well as microbial community composition beneath them. This shows that the effect of N-fixing tree species on soil carbon sequestration is species-specific, cannot be generalized and requires planting trails to determine if there will be benefits to carbon sequestration. © 2014 Elsevier Ltd.

Flying, fasting, and feeding in birds during migration: a nutritional and physiological ecology perspective

Unlike exercising mammals, migratory birds fuel very high intensity exercise (e.g., flight) with fatty acids delivered from the adipose tissue to the working muscles by the circulatory system. Given the primary importance of fatty acids for fueling intense exercise, we discuss the likely limiting steps in lipid transport and oxidation for exercising birds and the ecological factors that affect the quality and quantity of fat stored in wild birds. Most stored lipids in migratory birds are comprised of three fatty acids (16:0, 18:1 and 18:2) even though migratory birds have diverse food habits. Diet selection and selective metabolism of lipids play important roles in determining the fatty acid composition of birds which, in turn, affects energetic performance during intense exercise. As such, migratory birds offer an intriguing model for studying the implications of lipid metabolism and obesity on exercise performance. We conclude with a discussion of the energetic costs of migratory flight and stopover in birds, and its implications for bird migration strategies.

Exploring omega-3 fatty acids, enzymes and biodiesel producing thraustochytrids from Australian and Indian marine biodiversity

The marine environment harbours a vast diversity of microorganisms, many of which are unique, and have potential to produce commercially useful materials. Therefore, marine biodiversity from Australian and Indian habitat has been explored to produce novel bioactives, and enzymes. Among these, thraustochytrids collected from Indian habitats were shown to be rich in saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs), together constituting 51-76 % of total fatty acids (TFA). Indian and Australian thraustochytrids occupy separate positions in the dendrogram, showing significant differences exist in the fatty acid profiles in these two sets of thraustochytrid strains. In general, Australian strains had a higher docosahexaenoic acid (DHA) content than Indian strains with DHA at 17-31 % of TFA. A range of enzyme activities were observed in the strains, with Australian strains showing overall higher levels of enzyme activity, with the exception of one Indian strain (DBTIOC-1). Comparative analysis of the fatty acid profile of 34 strains revealed that Indian thraustochytrids are more suitable for biodiesel production since these strains have higher fatty acids content for biodiesel (FAB, 76 %) production than Australian thraustochytrids, while the Australian strains are more suitable for omega-3 (40 %) production.

Muscle redox signalling pathways in exercise. Role of antioxidants

Recent research highlights the importance of redox signalling pathway activation by contraction-induced reactive oxygen species (ROS) and nitric oxide (NO) in normal exercise-related cellular and molecular adaptations in skeletal muscle. In this review, we discuss some potentially important redox signalling pathways in skeletal muscle that are involved in acute and chronic responses to contraction and exercise. Specifically, we discuss redox signalling implicated in skeletal muscle contraction force, mitochondrial biogenesis and antioxidant enzyme induction, glucose uptake and muscle hypertrophy. Furthermore, we review evidence investigating the impact of major exogenous antioxidants on these acute and chronic responses to exercise. Redox signalling pathways involved in adaptive responses in skeletal muscle to exercise are not clearly elucidated at present, and further research is required to better define important signalling pathways involved. Evidence of beneficial or detrimental effects of specific antioxidant compounds on exercise adaptations in muscle is similarly limited, particularly in human subjects. Future research is required to not only investigate effects of specific antioxidant compounds on skeletal muscle exercise adaptations, but also to better establish mechanisms of action of specific antioxidants in vivo. Although we feel it remains somewhat premature to make clear recommendations in relation to application of specific antioxidant compounds in different exercise settings, a bulk of evidence suggests that N-acetylcysteine (NAC) is ergogenic through its effects on maintenance of muscle force production during sustained fatiguing events. Nevertheless, a current lack of evidence from studies using performance tests representative of athletic competition and a potential for adverse effects with high doses (>70 mg/kg body mass) warrants caution in its use for performance enhancement. In addition, evidence implicates high dose vitamin C (1 g/day) and E (≥260 IU/day) supplementation in impairments to some skeletal muscle cellular adaptations to chronic exercise training. Thus, determining the utility of antioxidant supplementation in athletes likely requires a consideration of training and competition periodization cycles of athletes in addition to type, dose and duration of antioxidant supplementation.

Arachidonic acid and eicosapentaenoic acid metabolism in juvenile Atlantic Salmon as affected by water temperature

Salmons raised in aquaculture farms around the world are increasingly subjected to sub-optimal environmental conditions, such as high water temperatures during summer seasons. Aerobic scope increases and lipid metabolism changes are known plasticity responses of fish for a better acclimation to high water temperature. The present study aimed at investigating the effect of high water temperature on the regulation of fatty acid metabolism in juvenile Atlantic salmon fed different dietary ARA/EPA ratios (arachidonic acid, 20:4n-6/ eicosapentaenoic acid, 20:5n-3), with particular focus on apparent in vivo enzyme activities and gene expression of lipid metabolism pathways. Three experimental diets were formulated to be identical, except for the ratio EPA/ARA, and fed to triplicate groups of Atlantic salmon (Salmo salar) kept either at 10°C or 20°C. Results showed that fatty acid metabolic utilisation, and likely also their dietary requirements for optimal performance, can be affected by changes in their relative levels and by environmental temperature in Atlantic salmon. Thus, the increase in temperature, independently from dietary treatment, had a significant effect on the β-oxidation of a fatty acid including EPA, as observed by the apparent in vivo enzyme activity and mRNA expression of pparα -transcription factor in lipid metabolism, including β-oxidation genes- and cpt1 -key enzyme responsible for the movement of LC-PUFA from the cytosol into the mitochondria for β-oxidation-, were both increased at the higher water temperature. An interesting interaction was observed in the transcription and in vivo enzyme activity of Δ5fad-time-limiting enzyme in the biosynthesis pathway of EPA and ARA. Such, at lower temperature, the highest mRNA expression and enzyme activity was recorded in fish with limited supply of dietary EPA, whereas at higher temperature these were recorded in fish with limited ARA supply. In consideration that fish at higher water temperature recorded a significantly increased feed intake, these results clearly suggested that at high, sub-optimal water temperature, fish metabolism attempted to increment its overall ARA status -the most bioactive LC-PUFA participating in the inflammatory response- by modulating the metabolic fate of dietary ARA (expressed as % of net intake), reducing its β-oxidation and favouring synthesis and deposition. This correlates also with results from other recent studies showing that both immune- and stress- responses in fish are up regulated in fish held at high temperatures. This is a novel and fundamental information that warrants industry and scientific attention, in consideration of the imminent increase in water temperatures, continuous expansion of aquaculture operations, resources utilisation in aquafeed and much needed seasonal/adaptive nutritional strategies.

Antimicrobial, antioxidant and anti-inflammatory phenolic activities in extra virgin olive oil

The Mediterranean diet is associated with a lower incidence of chronic degenerative diseases and higher life expectancy. These health benefits have been partially attributed to the dietary consumption of extra virgin olive oil (EVOO) by Mediterranean populations, and more specifically the phenolic compounds naturally present in EVOO. Studies involving humans and animals (in vivo and in vitro) have demonstrated that olive oil phenolic compounds have potentially beneficial biological effects resulting from their antimicrobial, antioxidant and anti-inflammatory activities. This paper summarizes current knowledge on the biological activities of specific olive oil phenolic compounds together with information on their concentration in EVOO, bioavailability and stability over time.

Relationship between genotype and enzyme activity of glutathione S-transferases M1 and P1 in Chinese

Glutathione S-transferases (GSTs) are the major detoxifying Phase II enzyme for eliminating electrophilic compounds. Mutations in GSTM1, GSTP1 and GSTT1 in Caucasian and GSTA1 in Chinese have been found to reduce enzyme activity. However, data on the impact of common genetic polymorphisms of GSTM1 and GSTP1 on enzyme activity in Chinese is lacking. This study aimed to investigate the effect of common GSTP1 and GSTM1 polymorphisms on erythrocyte GST activity in healthy Chinese (n = 196). GSTM1 null mutation (GSTM1*0) was analyzed by a PCR-Multiplex procedure, whereas GSTP1 313A → G polymorphism (resulting in Ile105Val at codon 105) was analyzed by PCR-restriction fragment length polymorphism (RFLP) analysis. Erythrocyte GST activity was measured using 1-chloro-2,4-dinitro-bezene (CDNB) as the model substrate. The frequency of GSTM1 null genotype was 54.3% and the frequency of GSTP1-Ile/Ile, -Ile/Val, and -Val/Val genotype was 60.7%, 35.2% and 4.1%, respectively, with a frequency of 21.7% for the 105 valine allele. Age, gender and smoking did not significantly affect the erythrocyte GST activities. The mean erythrocyte GST enzyme activity for GSTP1*-Ile/Val genotype group (3.53 ± 0.63 U/g Hb) was significantly lower than that for subjects with GSTP1-Ile/Ile genotype (4.25 ± 1.07 U/g Hb, P = 0.004), while subjects with the GSTP1-Val/Val genotype had the lowest enzyme activity (2.44 ± 0.67 U/g Hb). In addition, the GST activity in carriers of GSTM1*0/GSTP1-Ile/Ile was significantly higher than that of subjects inherited GSTM1*0/GSTP1-Ile/Val or GSTM1*0/GSTP1-Val/Val. However, there is no association between GSTM1 null mutation and reduced enzyme activity. GSTP1 codon 105 mutation led to reduced erythrocyte GST activity in Chinese. A combined GSTP1 and GSTM1 null mutations also resulted in significantly reduced GST activity. Further studies are needed to explore the clinical implications of GSTM1 and GSTP1 polymorphisms.

Antioxidant activity of β-lactoglobulin and its modified derivatives

Both native ss-lactoglobulin and its modified derivatives (Figure 1) exhibited antioxidant activity when assessed by the FRAP assay (which measures total reducing power of the sample). A positive correlation was observed between antioxidant activity and protein concentration in all samples. Compared to the native protein, the concentration dependence of the antioxidant activity was significantly greater when ss-lactoglobulin was modified with the Maillard reaction (p=0.000) and Enzyme hydrolysis (p=0.022)....

Gut health immunomodulatory and anti-inflammatory functions of gut enzyme digested high protein micro-nutrient dietary supplement-Enprocal

Background: Enprocal is a high-protein micro-nutrient rich formulated supplementary food designed to meet the nutritional needs of the frail elderly and be delivered to them in every day foods. We studied the potential of Enprocal to improve gut and immune health using simple and robust bioassays for gut cell proliferation, intestinal integrity/permeability, immunomodulatory, anti-inflammatory and anti-oxidative activities. Effects of Enprocal were compared with whey protein concentrate 80 (WPC), heat treated skim milk powder, and other commercially available milk derived products.

Results: Enprocal (undigested) and digested (Enprocal D) selectively enhanced cell proliferation in normal human intestinal epithelial cells (FHs74-Int) and showed no cytotoxicity. In a dose dependent manner Enprocal induced cell death in Caco-2 cells (human colon adencarcinoma epithelial cells). Digested Enprocal (Enprocal D: gut enzyme cocktail treated) maintained the intestinal integrity in transepithelial resistance (TEER) assay, increased the permeability of horseradish peroxidase (HRP) and did not induce oxidative stress to the gut epithelial cells. Enprocal D upregulated the surface expression of co-stimulatory (CD40, CD86, CD80), MHC I and MHC II molecules on PMA differentiated THP-1 macrophages in coculture transwell model, and inhibited the monocyte/lymphocyte (THP-1/Jurkat E6-1 cells)-epithelial cell adhesion. In cytokine secretion analyses, Enprocal D down-regulated the secretion of proinflammatory cytokines (IL-1β and TNF-α) and up-regulated IFN-γ, IL-2 and IL-10.

Conclusion: Our results indicate that Enprocal creates neither oxidative injury nor cytotoxicity, stimulates normal gut cell proliferation, up regulates immune cell activation markers and may aid in the production of antibodies. Furthermore, through downregulation of proinflammatory cytokines, Enprocal appears to be beneficial in reducing the effects of chronic gut inflammatory diseases such as inflammatory bowel disease (IBD). Stimulation of normal human fetal intestinal cell proliferation without cell cytotoxicity indicates it may also be given as infant food particularly for premature babies.

Amylase and glucosidase enzyme inhibitory activity of ginger (Zingiber officinale Roscoe) an in vitro study

The prevalence of type 2 diabetes has reached to an epidemic proportion in Sri Lanka. The need for achieving better control of blood glucose level has been evident in diabetes management. However it is not easy to achieve this goal in a large proportion of patients. This is partly due to limitations of currently available pharmacological agents which stimulate research on novel anti-diabetic agents with different mechanisms. Digestive enzymes have been targeted as potential avenues for modulation of blood glucose concentration through inhibition of the enzymatic breakdown of complex carbohydrates to meal derived glucose absorption. Acarbose is a widely used oral anti-diabetic drug which inhibits the α-glucosidase, enzyme responsible for breaking down of disaccharides and polysaccharides into glucose. Many herbal extracts have been found to posses similar inhibitory effects. Ginger (Zingiber officinale Roscoe) has developed a reputation in treatment of several diseases. In vitro enzymic inhibitory effect of ginger was investigated in this study. Enzymes α -amylase and α -glucosidase treated with either Acarbose or ginger extract were allowed to react with cooked rice and percentages of glucose content were measured. The glucosidase and amylase activities on the rice were inhibited by addition of ginger cause significant reduction in glucose percentages (36.86± 1.05 to 26.87± 2.17, P<0.05 and 49.04±0.65 to 35.35±2.22, P<0.05) which showed comparable results with Acarbose on glucosidase activity (36.86± 1.05 to, 27.8±1.32 P<0.05). Results of the study indicates ginger as a potential plant based amylase and glucosidase inhibitor in carbohydrate digestion but usage in glycaemic control in human has to be investigated further.