Carbohydrate Regulation Research Articles

Turgor-responsive starch phosphorylation in Oryza sativa stems: A primary event of starch degradation associated with grain-filling ability.

Grain filling ability is mainly affected by the translocation of carbohydrates generated from temporarily stored stem starch in most field crops including rice (Oryza sativa L.). The partitioning of non-structural stem carbohydrates has been recognized as an important trait for raising the yield ceiling, yet we still do not fully understand how carbohydrate partitioning occurs in the stems. In this study, two rice subspecies that exhibit different patterns of non-structural stem carbohydrates partitioning, a japonica-dominant cultivar, Momiroman, and an indica-dominant cultivar, Hokuriku 193, were used as the model system to study the relationship between turgor pressure and metabolic regulation of non-structural stem carbohydrates, by combining the water status measurement with gene expression analysis and a dynamic prefixed 13C tracer analysis using a mass spectrometer. Here, we report a clear varietal difference in turgor-associated starch phosphorylation occurred at the initiation of non-structural carbohydrate partitioning. The data indicated that starch degradation in Hokuriku 193 stems occurred at full-heading, 5 days earlier than in Momiroman, contributing to greater sink filling. Gene expression analysis revealed that expression pattern of the gene encoding α-glucan, water dikinase (GWD1) was similar between two varieties, and the maximum expression level in Hokuriku 193, reached at full heading (4 DAH), was greater than in Momiroman, leading to an earlier increase in a series of amylase-related gene expression in Hokuriku 193. In both varieties, peaks in turgor pressure preceded the increases in GWD1 expression, and changes in GWD1 expression was correlated with turgor pressure. Additionally, a threshold is likely to exist for GWD1 expression to facilitate starch degradation. Taken together, these results raise the possibility that turgor-associated starch phosphorylation in cells is responsible for the metabolism that leads to starch degradation. Because the two cultivars exhibited remarkable varietal differences in the pattern of non-structural carbohydrate partitioning, our findings propose that the observed difference in grain-filling ability originated from turgor-associated regulation of starch phosphorylation in stem parenchyma cells. Further understanding of the molecular mechanism of turgor-regulation may provide a new selection criterion for breaking the yield barriers in crop production.

Validation, Identification, and Biological Consequences of the Site-specific O-GlcNAcylation Dynamics of Carbohydrate-responsive Element-binding Protein (ChREBP).

O-GlcNAcylation of carbohydrate-responsive element-binding protein (ChREBP) is believed as an important modulator of ChREBP activities, however little direct evidence of O-GlcNAcylation on ChREBP and no exact O-GlcNAcylation sites have been reported so far. Here, we validate O-GlcNAcylation on ChREBP in cell-free coupled transcription/translation system and in cells by chemoenzymatic and metabolic labeling, respectively. Moreover, for the first time, we identify O-GlcNAcylation on Ser614 in the C-terminus of ChREBP by mass spectrometry and validate two important sites, Thr517 and Ser839 for O-GlcNAcylation and their function via molecular and chemical biological method. Under high glucose conditions, Ser514 phosphorylation enhances ChREBP O-GlcNAcylation, maintaining the transcriptional activity of ChREBP; Ser839 O-GlcNAcylation is essential for Mlx-heterodimerization and DNA-binding activity enhancement, consequently inducing transcriptional activity. Ser839 O-GlcNAcylation is also crucial for ChREBP nuclear export partially by strengthening interactions with CRM1 and 14-3-3. This work is a detailed study of ChREBP O-GlcNAcylation and highlights the biological consequences of the site-specific O-GlcNAcylation dynamics of ChREBP.

Amelioration of cognitive impairments in APPswe/PS1dE9 mice is associated with metabolites alteration induced by total salvianolic acid

PurposeTotal salvianolic acid (TSA) is extracted from salvia miltiorrhiza; however, to date, there has been limited characterization of its effects on metabolites in Alzheimer’s disease model-APPswe/PS1dE9 mice. The main objective of this study was to investigate the metabolic changes in 7-month-old APPswe/PS1dE9 mice treated with TSA, which protects against learning and memory impairment.MethodsAPPswe/PS1dE9 mice were treated with TSA (30 mg/kg·d and 60 mg/kg·d, i.p.) and saline (i.p.) daily from 3.5 months old for 14 weeks; saline-treated (i.p.) WT mice were included as the controls. The effects of TSA on learning and memory were assessed by a series of behavioral tests, including the NOR, MWM and step-through tasks. The FBG and plasma lipid levels were subsequently assessed using the GOPOD and enzymatic color methods, respectively. Finally, the concentrations of Aβ42, Aβ40 and metabolites in the hippocampus of the mice were detected via ELISA and GC-TOF-MS, respectively.ResultsAt 7 months of age, the APPswe/PS1dE9 mice treated with TSA exhibited an improvement in the preference index (PI) one hour after the acquisition phase in the NOR and the preservation of spatial learning and memory in the MWM. Treatment with TSA substantially decreased the LDL-C level, and 60 mg/kg TSA decreased the CHOL level compared with the plasma level of the APPswe/PS1dE9 group. The Aβ42 and Aβ40 levels in the hippocampus were decreased in the TSA-treated group compared with the saline-treated APPswe/PS1dE9 group. The regulation of metabolic pathways relevant to TSA predominantly included carbohydrate metabolism, such as sorbitol, glucose-6-phosphate, sucrose-6-phosphate and galactose, vitamin metabolism involved in cholecalciferol and ascorbate in the hippocampus.ConclusionsTSA induced a remarkable amelioration of learning and memory impairments in APPswe/PS1dE9 mice through the regulation of Aβ42, Aβ40, carbohydrate and vitamin metabolites in the hippocampus and LDL-C and CHOL in the plasma.

The mechanisms underlying the therapeutic effects of reflexotherapy and drinking mineral waters in the patients presenting with metabolic syndrome

The objective of the present study was to evaluate the effects produced by the intake of drinking mineral water and acupuncture on the various parameters characterizing the patients suffering from metabolic syndrome in combination with altered insulin resistance. Ninety patients with this condition included in the study underwent the analysis of their the blood pressure, body mass index, blood glucose and lipid levels, insulin and cortisol secretion. We undertook the analysis of the effects of the single and repeated intakes of Essentuki No 17 mineral water included in the combined treatment of the patients with metabolic syndrome and revealed many common responses of the organism to its therapeutic action. Specifically, the stress-type reactions suggested the initiation of the adaptive processes in the system of hormonal regulation of carbohydrate and lipid metabolism. Simultaneously, the manifestations of insulin resistance became less pronounced indicating that both acupuncture and drinking mineral water suppressed the action of the main pathogenic mechanisms underlying the development of metabolic syndrome. Moreover, it was shown that acupuncture had a stronger hypotensive effect in the combination with the decrease of the overproduction of cortisol whereas the intake of the mineral water had a greater metabolic potential and contributed to the intensification of the basal secretion of glucocorticoids. Both reflexotherapy and drinking mineral water have a well apparent effect on the pathogenetic reactions of the metabolic syndrome and therefore can be used in addition to the standard therapy to activate the non-specific, phylogenetically established and enshrined at the genetic level self-healing responses by mainstreaming the adaptation processes and the formation of the adaptive reactions initiated by stressor components. The addition of acupuncture or domestic mineral water intake to the standard therapy of the patients suffering from metabolic syndrome significantly enhances the effectiveness of the treatment. The beneficial therapeutic action of acupuncture and drinking mineral water is underlain by their impact on the mechanisms of resistance to insulin that manifests itself as a decrease of the fasting secretion of this hormone and optimization of carbohydrate and lipid metabolism. The therapeutic effect of acupuncture and drinking mineral water is realized through the induction of the stress-initiating reactions which activate the processes of adaptation, with reflexotherapy largely acting on the cardiovascular system and drinking mineral water on the system responsible for insulin regulation of the metabolic processes.

Regulation of the expression of LXR in rat hypothalamic and hippocampal explants

Liver X receptors (LXR) are important transcription factors involved in the regulation of carbohydrate and lipid metabolism and are expressed in different brain areas. Recently we described that LXR expression in the hypothalamus is sensitive to serum levels of lipids and carbohydrates. Here, we further characterized the effects of glucose, insulin, cholesterol and cholic acid on the expression of LXRα and LXRβ in hypothalamus and hippocampus explants as in vitro models. The LXR activation products, GLUT2 and ABCA1, were also analyzed by Western blot. Glucose had different effects in the hypothalamus compared to the hippocampus. In the hypothalamus, increases in glucose concentrations decreased LXRβ expression while in the hippocampus increased both receptor subtypes levels. In contrast, insulin treatment decreased LXRβ in the hypothalamus while having no effects on the hippocampus. Cholic acid and cholesterol increased only LXRα expression in the hypothalamus whereas no effects on the hippocampus were detected. The newly expressed LXR receptors may be functional active since the level of the LXR activation product ABCA1 was also increased. Changes in GLUT2 expression was observed only when LXRβ levels were increased. Altogether these data show that LXR are sensitive to glucose, insulin and lipids in vitro, as well as in vivo as we previously showed, suggesting an involvement of LXR in central metabolic pathways and control of energy homeostasis.

Hypothyroidism and possible association with Metabolic Syndrome

Background: Thyroid dysfunctions are the most common forms of endocrine disorder in our country, Thyroid hormones perform a wide array of metabolic functions including regulation of lipids, carbohydrates, protein and electrolytes and mineral metabolism, Thyroid hormones are major regulatory hormones that controls the rate of metabolic function and alteration in the levels of thyroid hormones may be associated with metabolic syndrome Aim: The study was performed to investigate the association between Altered thyroid state i.e hypothyroidism and metabolic syndrome. Materials and Methods: The study was done on patients with symptoms of hypothyroidism or follow up cases of hypothyroidism having metabolic syndrome. T3, T4 and TSH and were analyzed by enzyme linked fluorescent assay (ELFA) technique using Vidas auto analyzer from Biomeriuex, France. Fasting blood sugar and lipid profile were estimated by Erba Chem 7 semi-auto analyzer. The data was analyzed using SPSS-17 software package. Results: The percentage of metabolic syndrome and hypothyroidism in each age group were determined and we have found that the percentage of metabolic syndrome is increasing with age and is highest 60 % in the age group of 61-75 years, both T3, T4 are comparably decreased but TSH is on the higher side in metabolic syndrome as compared to non-metabolic syndrome Conclusion: Patients having Thyroid dysfunction should regularly be checked for parameters of metabolic syndrome: Early detection of thyroid dysfunction and treatment can prevent the complications of metabolic syndrome.

The Non-Coding RNA Ncr0700/PmgR1 is Required for Photomixotrophic Growth and the Regulation of Glycogen Accumulation in the Cyanobacterium Synechocystis sp. PCC 6803.

Carbohydrate metabolism is a tightly regulated process in photosynthetic organisms. In the cyanobacterium Synechocystis sp. PCC 6803, the photomixotrophic growth protein A (PmgA) is involved in the regulation of glucose and storage carbohydrate (i.e. glycogen) metabolism, while its biochemical activity and possible factors acting downstream of PmgA are unknown. Here, a genome-wide microarray analysis of a ΔpmgA strain identified the expression of 36 protein-coding genes and 42 non-coding transcripts as significantly altered. From these, the non-coding RNA Ncr0700 was identified as the transcript most strongly reduced in abundance. Ncr0700 is widely conserved among cyanobacteria. In Synechocystis its expression is inversely correlated with light intensity. Similarly to a ΔpmgA mutant, a Δncr0700 deletion strain showed an approximately 2-fold increase in glycogen content under photoautotrophic conditions and wild-type-like growth. Moreover, its growth was arrested by 38 h after a shift to photomixotrophic conditions. Ectopic expression of Ncr0700 in Δncr0700 and ΔpmgA restored the glycogen content and photomixotrophic growth to wild-type levels. These results indicate that Ncr0700 is required for photomixotrophic growth and the regulation of glycogen accumulation, and acts downstream of PmgA. Hence Ncr0700 is renamed here as PmgR1 for photomixotrophic growth RNA 1.

Mutational Evidence for the Critical Role of CBF Transcription Factors in Cold Acclimation in Arabidopsis.

The three tandemly arranged CBF genes, CBF1, CBF2, and CBF3, are involved in cold acclimation. Due to the lack of stable loss-of-function Arabidopsis (Arabidopsis thaliana) mutants deficient in all three CBF genes, it is still unclear whether the CBF genes are essential for freezing tolerance and whether they may have other functions besides cold acclimation. In this study, we used the CRISPR/Cas9 system to generate cbf single, double, and triple mutants. Compared to the wild type, the cbf triple mutants are extremely sensitive to freezing after cold acclimation, demonstrating that the three CBF genes are essential for cold acclimation. Our results show that the three CBF genes also contribute to basal freezing tolerance. Unexpectedly, we found that the cbf triple mutants are defective in seedling development and salt stress tolerance. Transcript profiling revealed that the CBF genes regulate 414 cold-responsive (COR) genes, of which 346 are CBF-activated genes and 68 are CBF-repressed genes. The analysis suggested that CBF proteins are extensively involved in the regulation of carbohydrate and lipid metabolism, cell wall modification, and gene transcription. Interestingly, like the triple mutants, cbf2 cbf3 double mutants are more sensitive to freezing after cold acclimation compared to the wild type, but cbf1 cbf3 double mutants are more resistant, suggesting that CBF2 is more important than CBF1 and CBF3 in cold acclimation-dependent freezing tolerance. Our results not only demonstrate that the three CBF genes together are required for cold acclimation and freezing tolerance, but also reveal that they are important for salt tolerance and seedling development.

Apolipoprotein levels in type 2 diabetes mellitus patients

Background and objectivesDiabetes mellitus is regarded as a defective regulation of carbohydrates, lipid and protein metabolism. The worldwide prevalence of diabetes especially that of type 2 diabetes mellitus is increasing, as has the information and awareness about the disease among people. Lipids play a key role in the development of atherosclerosis and its clinical manifestation. This study intends to measure the apolipoprotein levels in type 2 diabetes mellitus patients and to correlate it with levels of LDL-C, total cholesterol and HDL, as well as with levels of glycated haemoglobin. MethodsTotal 114 patients who met inclusion criteria and exclusion criteria were subjected to detailed clinical examination and investigations. Depending upon data obtained, results were evaluated, tabulated and the various lipid parameters were correlated. ResultsIn this study, the levels of fasting and post-prandial blood glucose (161.61 and 223.61mg/dl respectively), glycated haemoglobin (8.72%), serum cholesterol (177mg/dl), LDL-C (109mg/dl), Apo B (84.5mg/dl) and Apo A-I (103.5mg/dl) were significantly higher in diabetics compared to healthy population. There was a positive correlation between HDL-C and Apo A-I in diabetic individuals according to our study. ConclusionApolipoprotein measurements present some methodological advantages when compared with LDL-C quantification. Apolipoproteins estimation can be included in the dyslipidaemia work-up of diabetics. But larger studies are still needed to confirm the practical superiority of apolipoprotein over traditional dyslipidaemia markers.

The application of transcranial magnetic stimulation for the treatment of metabolic syndrome

This article is focused n the analysis of the influence of transcranial magnetic stimulation on the hormonal regulation of carbohydrate and lipid metabolism in the patients presenting with metabolic syndrome. It is shown that the transcranial application of a magnetic field stimulates sensitivity of the tissues to insulin and thereby facilitates the reduction of arterial pressure and optimization of lipid and glucose metabolism.

Effect of obestatin on normal, diabetic, and obese male albino rats

Aim This work was performed to study the effect of obestatin on normal, diabetic, and obese male albino rats. Materials and methods A total of 60 male albino rats were divided into six groups: group 1 was the normal control group; group 2, the obestatin-treated group, was injected with 100 μg/kg of obestatin subcutaneously twice daily for 1 week; group 3 was the diabetic control group; group 4, the obestatin-treated diabetic group, was injected with obestatin as in group 2; group 5 was the obese control group; and group 6, the obestatin-treated obese group, was injected with obestatin as in group 2. At the end of the experimental period, serum samples were collected after decapitation for estimation of fasting glucose, insulin, triglyceride (TG), and total cholesterol. BMI was also measured. Results After 1 week of obestatin treatment, the obestatin-treated control group showed insignificant changes in serum fasting glucose, insulin, TG, and total cholesterol levels with the exception of BMI, which showed a significant decrease as compared with the normal control group. However, the obestatin-treated diabetic group showed a significant decrease in serum fasting glucose, TG, and total cholesterol levels, with a significant increase in insulin level, but an insignificant change in BMI as compared with the diabetic control group. In contrast, the obestatin-treated obese group showed insignificant changes in serum fasting glucose and insulin, but significant decrease in serum TG, total cholesterol levels, and BMI as compared with the obese control group. Conclusion From these results, we conclude that there is a significant role for obestatin in the regulation of carbohydrate and lipid metabolism, shown from its effect on glucose, insulin, and serum lipids. Thus, obestatin administration develops new and more efficient therapeutic approaches to treat diabetes and obesity.

Impact of SIRT1 gene expression on the development and treatment of the metabolic syndrome in oncological patients

Sirtuins - products of gene SIRT expression have been divided into 7 classes, according to the amino acid composition and location of the cell. Those factors, called longevities proteins, are a group of histone deacetylases, depend on nicotinamide adenine dinucleotide (NAD). Particularly noteworthy is the protein sirtuin 1, which further deacetylates numerous transcription factors, receptors and enzymes. Through its action reduces the activity of glucocorticoid receptors in the body. Products of gene SIRT1 expression is responsible for apoptosis, differentiation, senescence cells, also affect the regulation of carbohydrate and lipid metabolism. Cardioprotective and hypotensive impact is also very important. SIRT1 reduces the accumulation of fat and decreases the risk of visceral obesity. Low gene expression of SIRT1 therefore predispose to the development of metabolic syndrome. Homeostasis sirtuin 1 disorders can also be observed in certain neoplastic diseases, primarily hormone-dependent breast, ovarian and prostate cancer, as well as it can cause leukemias and lymphomas. Components, activating expression of gen SIRT1 or a molecule with biological properties sirtuin 1, may have promising impact for treatment of diabetes mellitus type 2, obesity, hypertension, dyslipidemia. Analyzing, the pleiotropic effect of sirtuin 1 and numerous metabolic pathways, appear to be particularly beneficial effect of supplementation molecules increasing the level of expression gene SIRT1, in treatment of acute lymphoblastic leukemia with using high-dosing glicocorticosteroid therapy. Which would reduce the number of early and late complications of oncological treatment and increase patient survival. Compound requires further study.

Pharmacological characterization and use myo-inositol in gynecological practice

Inositol is a six atom cyclohexane alcohol, which has 9 isomers, one of which (myo-inositol) has a vitamin activity and has been classified as B vitamins (B8). The biological function of myo-inositol is an intracellular signaling. Signal molecules that are synthesized from or by using myo-inositol, participate in functioning of the reproductive, central nervous system, metabolism of carbohydrates. More than 120 inositol-dependent proteins are involved in various physiological processes, including the implementation of reproductive function. Through participation GNRHR and KISS1R genes in the synthesis of proteins that includes receptors of the gonadotropin-releasing hormone, myo-inositol participates in the production of luteinizing hormone and follicle stimulating hormone, steroidogenesis, including the synthesis of several key hormones of the female reproductive system such as estriol and estradiol. Inozitol-depending proteins play an important role in the regulation of carbohydrate and lipid metabolism. They participate in transmits the signal from the insulin receptor to the cytoplasm of cells that is increase expression of glucose transporter and thus stimulates the metabolism of carbohydrates and fats. In the end, this is leads to a decrease of insulin resistance, prevents the development of overweight, obesity, diabetes. It is equally important that myo-inositol helps to reduce elevated levels of triglycerides and cholesterol, especially low density lipoprotein. In turn, disruption of lipid and cholesterol metabolism often caused by reduced production of key hormones (luteinizing hormone and follicle stimulating hormone) that regulate processes of folliculogenesis and oogenesis. Myo-inositol level in follicular fluid of mature fertilized oocytes significantly higher than that in the liquid of immature unfertilized oocytes, and its level correlates with the estriol level in follicular fluid. This is indicates that myo-inositol play role in the process of oocytes maturing. A number of studies confirming the efficiency of myo-inositol in the complex treatment of a frequent complication of this disease - polycystic ovary syndrome and infertility.

Drought- and frost-induced accumulation of soluble carbohydrates during accelerated senescence in Quercus pubescens

Different environmental conditions affect tree senescence by different patterns of carbohydrate concentrations and have specific impact on the dissection of the photosynthetic apparatus. A proactive cultivation of Mediterranean broadleaf species, including oaks, has been suggested to fill possible temporal and spatial gaps in forestry created by Climate Change in Central Europe in the future. Climate can affect trees in several different ways, e.g., by modulating the course of leaf senescence. Senescence-associated processes, like regulation of carbohydrates and changes in chlorophyll fluorescence under drought stress conditions were studied with leaf tissue of drought-tolerant downy oak (Quercus pubescens). Two months of consistent drought stress in a frost-free greenhouse led to significantly earlier senescence and significant increased amounts of soluble sugars in the leaves of the drought-stressed group in comparison to a well-watered control group. Similar sugar accumulation was observed in trees outdoors, after exposure to frost. In contrast to monocarpic plants the accumulation of free sugars is neither triggering leaf senescence, nor is it a side effect of age-depending changes in Q. pubescens. Instead, sugar accumulation is induced by abiotical factors, like drought and frost. Furthermore, we suggest that the senescence process in the absence of drought stress or frost depends on the source status of the leaf, which, in term, is a function of light (through photosynthesis) and night temperature (through respiration). Contents of the storage metabolite starch decreased during late summer in all three groups. Drought-stressed plants showed a decline of the connectivity of photosystem II antenna, reflected as the L-band in the chlorophyll fluorescence induction curves, and stronger correlations between the declines in the capacity of photosynthetic dark reactions and electron transport-associated chlorophyll fluorescence parameters. We conclude that the disassembly of single parts of the photosynthetic apparatus during leaf senescence is a uniform process, but the onset of this process depends on abiotical environmental factors.

Phylogeny of the Vitamin K 2,3-Epoxide Reductase (VKOR) Family and Evolutionary Relationship to the Disulfide Bond Formation Protein B (DsbB) Family.

In humans and other vertebrate animals, vitamin K 2,3-epoxide reductase (VKOR) family enzymes are the gatekeepers between nutritionally acquired K vitamins and the vitamin K cycle responsible for posttranslational modifications that confer biological activity upon vitamin K-dependent proteins with crucial roles in hemostasis, bone development and homeostasis, hormonal carbohydrate regulation and fertility. We report a phylogenetic analysis of the VKOR family that identifies five major clades. Combined phylogenetic and site-specific conservation analyses point to clade-specific similarities and differences in structure and function. We discovered a single-site determinant uniquely identifying VKOR homologs belonging to human pathogenic, obligate intracellular prokaryotes and protists. Building on previous work by Sevier et al. (Protein Science 14:1630), we analyzed structural data from both VKOR and prokaryotic disulfide bond formation protein B (DsbB) families and hypothesize an ancient evolutionary relationship between the two families where one family arose from the other through a gene duplication/deletion event. This has resulted in circular permutation of primary sequence threading through the four-helical bundle protein folds of both families. This is the first report of circular permutation relating distant α-helical membrane protein sequences and folds. In conclusion, we suggest a chronology for the evolution of the five extant VKOR clades.

Revisiting macronutrient regulation in the polyphagous herbivore Helicoverpa zea (Lepidoptera: Noctuidae): New insights via nutritional geometry

Insect herbivores that ingest protein and carbohydrates in physiologically-optimal proportions and concentrations show superior performance and fitness. The first-ever study of protein–carbohydrate regulation in an insect herbivore was performed using the polyphagous agricultural pest Helicoverpa zea. In that study, experimental final instar caterpillars were presented two diets – one containing protein but no carbohydrates, the other containing carbohydrates but no protein – and allowed to self-select their protein–carbohydrate intake. The results showed that H. zea selected a diet with a protein-to-carbohydrate (p:c) ratio of 4:1. At about this same time, the geometric framework (GF) for the study of nutrition was introduced. The GF is now established as the most rigorous means to study nutrient regulation (in any animal). It has been used to study protein–carbohydrate regulation in several lepidopteran species, which exhibit a range of self-selected p:c ratios between 0.8 and 1.5. Given the economic importance of H. zea, and it is extremely protein-biased p:c ratio of 4:1 relative to those reported for other lepidopterans, we decided to revisit its protein–carbohydrate regulation. Our results, using the experimental approach of the GF, show that H. zea larvae self-select a p:c ratio of 1.6:1. This p:c ratio strongly matches that of its close relative, Heliothis virescens, and is more consistent with self-selected p:c ratios reported for other lepidopterans. Having accurate protein and carbohydrate regulation information for an insect herbivore pest such as H. zea is valuable for two reasons. First, it can be used to better understand feeding patterns in the field, which might lead to enhanced management. Second, it will allow researchers to develop rearing diets that more accurately reflect larval nutritional needs, which has important implications for resistance bioassays and other measures of physiological stress.

Is 5´-AMP-Activated Protein Kinase Both Jekyll and Hyde in Bladder Cancer?

The 5´-AMP-activated protein kinase (AMPK) is a key regulator of cellular metabolism and energy homeostasis in mammalian tissues. Metabolic adaptation is a critical step in ensuring cell survival during metabolic stress. Because of its critical role in the regulation of glucose homeostasis and carbohydrate, lipid, and protein metabolism, AMPK is involved in many human diseases, including cancers. Although AMPK signaling was originally characterized as a tumor-suppressive signaling pathway, several lines of evidence suggest that AMPK plays a much broader role and cannot simply be defined as either an oncogenic regulator or tumor suppressor. Notably, several recent studies demonstrated that the antitumorigenic effects of many indirect AMPK activators, such as metformin, do not depend on AMPK. Conversely, activation of AMPK induces the progression of cancers, emphasizing its oncogenic effect. Bladder cancer can be divided into two groups: non–muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC). The molecular mechanisms underlying these two types of cancer are distinct: NMIBC is associated with activation of the Ras pathway, whereas MIBC is characterized by loss of major tumor suppressors. Importantly, both pathways are connected to the mammalian target of rapamycin (mTOR) pathway. In addition, our recent metabolomic findings suggest that β-oxidation of fatty acids is an important factor in the development of bladder cancer. Both mTOR and β-oxidation are tightly associated with the AMPK pathway. Here, I summarize and discuss the recent findings on the two distinct roles of AMPK in cancer, as well as the relationship between bladder cancer and AMPK.

An integrative approach to identify hexaploid wheat miRNAome associated with development and tolerance to abiotic stress.

BackgroundWheat is a major staple crop with broad adaptability to a wide range of environmental conditions. This adaptability involves several stress and developmentally responsive genes, in which microRNAs (miRNAs) have emerged as important regulatory factors. However, the currently used approaches to identify miRNAs in this polyploid complex system focus on conserved and highly expressed miRNAs avoiding regularly those that are often lineage-specific, condition-specific, or appeared recently in evolution. In addition, many environmental and biological factors affecting miRNA expression were not yet considered, resulting still in an incomplete repertoire of wheat miRNAs.ResultsWe developed a conservation-independent technique based on an integrative approach that combines machine learning, bioinformatic tools, biological insights of known miRNA expression profiles and universal criteria of plant miRNAs to identify miRNAs with more confidence. The developed pipeline can potentially identify novel wheat miRNAs that share features common to several species or that are species specific or clade specific. It allowed the discovery of 199 miRNA candidates associated with different abiotic stresses and development stages. We also highlight from the raw data 267 miRNAs conserved with 43 miRBase families. The predicted miRNAs are highly associated with abiotic stress responses, tolerance and development. GO enrichment analysis showed that they may play biological and physiological roles associated with cold, salt and aluminum (Al) through auxin signaling pathways, regulation of gene expression, ubiquitination, transport, carbohydrates, gibberellins, lipid, glutathione and secondary metabolism, photosynthesis, as well as floral transition and flowering.ConclusionThis approach provides a broad repertoire of hexaploid wheat miRNAs associated with abiotic stress responses, tolerance and development. These valuable resources of expressed wheat miRNAs will help in elucidating the regulatory mechanisms involved in freezing and Al responses and tolerance mechanisms as well as for development and flowering. In the long term, it may help in breeding stress tolerant plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1490-8) contains supplementary material, which is available to authorized users.

Carbohydrate regulation of photosynthesis and respiration from branch girdling in four species of wet tropical rain forest trees.

How trees sense source-sink carbon balance remains unclear. One potential mechanism is a feedback from non-structural carbohydrates regulating photosynthesis and removing excess as waste respiration when the balance of photosynthesis against growth and metabolic activity changes. We tested this carbohydrate regulation of photosynthesis and respiration using branch girdling in four tree species in a wet tropical rainforest in Costa Rica. Because girdling severs phloem to stop carbohydrate export while leaving xylem intact to allow photosynthesis, we expected carbohydrates to accumulate in leaves to simulate a carbon imbalance. We varied girdling intensity by removing phloem in increments of one-quarter of the circumference (zero, one--quarter, half, three-quarters, full) and surrounded a target branch with fully girdled ones to create a gradient in leaf carbohydrate content. Light saturated photosynthesis rate was measured in situ, and foliar respiration rate and leaf carbohydrate content were measured after destructive harvest at the end of the treatment. Girdling intensity created no consistent or strong responses in leaf carbohydrates. Glucose and fructose slightly increased in all species by 3.4% per one-quarter girdle, total carbon content and leaf mass per area increased only in one species by 5.4 and 5.5% per one-quarter girdle, and starch did not change. Only full girdling lowered photosynthesis in three of four species by 59-69%, but the decrease in photosynthesis was unrelated to the increase in glucose and fructose content. Girdling did not affect respiration. The results suggest that leaf carbohydrate content remains relatively constant under carbon imbalance, and any changes are unlikely to regulate photosynthesis or respiration. Because girdling also stops the export of hormones and reactive oxygen species, girdling may induce physiological changes unrelated to carbohydrate accumulation and may not be an effective method to study carbohydrate feedback in leaves. In three species, removal of three-quarters of phloem area did not cause leaf carbohydrates to accumulate nor did it change photosynthesis or respiration, suggesting that phloem transport is flexible and transport rate per unit phloem can rapidly increase under an increase in carbohydrate supply relative to phloem area. Leaf carbohydrate content thus may be decoupled from whole plant carbon balance by phloem transport in some species, and carbohydrate regulation of photosynthesis and respiration may not be as common in trees as previous girdling studies suggest. Further studies in carbohydrate regulation should avoid using girdling as girdling can decrease photosynthesis through unintended means without the tested mechanisms of accumulating leaf carbohydrates.

Effect of Long‐term Supplementation of Selected Medicinal Herbs on Activity of Intestinal α‐Glucosidase and Expression of SI‐complex in Rat Model

In this study, we investigated the effect of long‐term supplementation of selected medicinal herbs such as Cinnamomum loureirii Nees, Magnolia officinale Rehder et Wils, Brassica oleracea var. capitata L., and Ficus carica L. on activity of intestinal a‐glucosidases and expression of sucrase‐isomaltase complex (SI‐complex) in Sprague‐Dawley (SD) rat model, and also evaluated effect of herbal mixture administration on carbohydrate digestibility by postprandial blood glucose lowering test. Using 4 groups of 11 male SD rats, each group were treated with Cabagin‐S® (positive control) and herbal mixture at low or high concentration given daily for 2 weeks. After 2 weeks administration, postprandial blood glucose lowering effect was evaluated and then small intestine biopsy was collected from each tested rat. To confirm the mechanism of action of herbal administration via regulation of carbohydrate hydrolyzing enzymes, the changes of sucrase/glucoamylase activities and expression of SI‐complex in small intestine were determined. Herbs have regulatory effects on both activity and expression of carbohydrate hydrolyzing enzymes in a similar manner with a known anti‐gastroenteric disorder drug, Cabagin‐S®. Furthermore, our findings confirm previous in vitro observations that herbs have inhibitory effect on carbohydrate hydrolyzing enzymes, namely sucrase, maltase, and SI‐complex.