Background Mepiquat chloride(MC)application and plant population density(PPD)increasing are required for modern cotton production.However,their interactive effects on leaf physiology and carbohydrate metabolism remain...Background Mepiquat chloride(MC)application and plant population density(PPD)increasing are required for modern cotton production.However,their interactive effects on leaf physiology and carbohydrate metabolism remain obscure.This study aimed to examine whether and how MC and PPD affect the leaf morpho-physiological characteristics,and thus final cotton yield.PPD of three levels(D1:2.25 plants·m^(-2),D2:4.5 plants·m^(-2),and D3:6.75 plants·m^(-2))and MC dosage of two levels(MC0:0 g·ha^(-2),MC1:82.5 g·ha^(-2))were combined to create six treatments.The dynamics of nonstructual carbohydrate concentration,carbon metabolism-related enzyme activity,and photosynthetic attributes in cotton leaves were examined during reproductive growth in 2019 and 2020.Results Among six treatments,the high PPD of 6.75 plants·m^(-2)combined with MC application(MC1D3)exhibited the greatest seed cotton yield and biological yield.The sucrose,hexose,starch,and total nonstructural carbohydrate(TNC)concentrations peaked at the first flowering(FF)stage and then declined to a minimum at the first boll opening(FBO)stage.Compared with other treatments,MC1D3 improved starch and TNC concentration by 5.4%~88.4%,7.8%~52.0% in 2019,and by 14.6%~55.9%,13.5%~39.7% in 2020 at the FF stage,respectively.Additionally,MC1D3 produced higher transformation rates of starch and TNC from the FF to FBO stages,indicating greater carbon production and utilization efficiency.MC1D3 displayed the maximal specific leaf weight(SLW)at the FBO stage,and the highest chlorophyll a(Chl a),Chl b,and Chl a+b concentration at the mid-late growth phase in both years.The Rubisco activity with MC1D3 was 2.6%~53.2% higher at the flowering and boll setting stages in both years,and 2.4%~52.7% higher at the FBO stage in 2020 than those in other treatments.These results provided a explanation of higher leaf senescence-resistant ability in MC1D3.Conclusion Increasing PPD coupled with MC application improves cotton yield by enhancing leaf carbohydrate production and utilization efficiency and delaying leaf senescence.展开更多
This study reported the influence of selenium(Se)on carbohydrate composition and some related enzymes and nutrient compositions of arsenic(As)stressed rice plants.Rice plants of cultivar PR126 were grown on soil amend...This study reported the influence of selenium(Se)on carbohydrate composition and some related enzymes and nutrient compositions of arsenic(As)stressed rice plants.Rice plants of cultivar PR126 were grown on soil amended with As in a range of 25-100μmol/kg with and without 0.5 or 1.0 mg/kg Se.Total soluble sugars(TSS)and reducing sugars(RS)increased in leaves of As stressed plants at the tillering and grain filling stages whereas sucrose and starch contents showed the reverse trend.Se supplementation to As stressed plants further increased TSS and RS,and enhanced sucrose phosphate synthase activity in rice leaves,thus improving sucrose content and the tolerance to As stress of the plants.Se alone or in combination with As resulted in lower As accumulation in rice husk and grains,and the highest reduction was observed in Se applied at 1.0 mg/kg compared to the corresponding As treatments alone.As may limit the accumulations of Na,Mg,K,Ca,Fe,Zn and Mn in rice grains,which are essential for humans.Binary application of different combinations of As and Se protected the plants against As and increased the mineral content in rice grains.Addition of Se in As treated soil significantly alleviated As stress by enhancing grain yields compared to the corresponding As treatment.It is concluded that Se induced amelioration of the toxic impact of As in rice either by modulating carbohydrate composition and/or nutrient uptake is one of the mechanisms to alleviate As stress in plants.展开更多
Auxin(indole-3-acetic acid, IAA) has a considerable impact on the regulation of plant carbohydrate levels and growth, but the mechanism by which it regulates sugar levels in plants has received little attention. In th...Auxin(indole-3-acetic acid, IAA) has a considerable impact on the regulation of plant carbohydrate levels and growth, but the mechanism by which it regulates sugar levels in plants has received little attention. In this study, we found that exogenous IAA altered fructose(Fru), glucose(Glc), and sucrose(Suc) concentrations in shoot tips mainly by regulating MdSUSY1, MdFRK2, MdHxK1 and MdSDH2 transcript levels. Additionally, we used 5-year-old ’Royal Gala’ apple trees to further verify that these genes play primary roles in regulating sink strength. The results showed that MdSUSY1, MdFRK2, MdHxK1/3 and MdSDH2 might be major contributors to sink strength regulation. Taken together, these results provide new insight into the regulation of the carbohydrate metabolism mechanism, which will be helpful for regulating sink strength and yield.展开更多
Proprotein convertase subtilisin/kexin type 9(PCSK9) plays a paramount role in the degradation of lowdensity lipoprotein(LDL) receptors(LDLR) on the hepatic cells surface and subsequently affects LDL particles catabol...Proprotein convertase subtilisin/kexin type 9(PCSK9) plays a paramount role in the degradation of lowdensity lipoprotein(LDL) receptors(LDLR) on the hepatic cells surface and subsequently affects LDL particles catabolism and LDL cholesterol(LDL-c) levels. The anti-PCSK9 monoclonal antibodies lead to substantial decrease of LDL-c concentration. PCSK9(which is also expressed in pancreatic delta-cells) can decrease LDLR and subsequently decrease cholesterol accumulation in pancreatic beta-cells, which impairs glucose metabolism and reduces insulin secretion. Thus, a possible adverse effect of PCSK9 inhibitors on carbohydrate metabolism may be expected by this mechanism, which has been supported by the mendelian studies results. On the other hand, clinical data have suggested a detrimental association of PCSK9 with glucose metabolism. So, the inhibition of PCSK9 may be seen as a double-edged sword regarding carbohydrate metabolism. Completed clinical trials have not shown a detrimental effect of PCSK9 inhibitors on diabetes risk, but their short-term duration does not allow definite conclusions.展开更多
The effects of salt stress on carbohydrate metabolism in Microcoleus vaginatus Gom., a cyanobacterium isolated from desert algal crusts, were investigated in the present study. Extracellular total carbohydrates and ex...The effects of salt stress on carbohydrate metabolism in Microcoleus vaginatus Gom., a cyanobacterium isolated from desert algal crusts, were investigated in the present study. Extracellular total carbohydrates and exopolysaccharides (EPS) in the culture medium produced by M. vaginatus increased significantly during the growth phase and reached a maximum during the stationary phase. The production of extracellular carbohydrates also significantly increased under higher salt concentrations, which was attributed to an increase in low molecular weight carbohydrates. In the presence of NaCI, the production of cellular total carbohydrates decreased and photosynthetic activity was impaired, whereas cellular reducing sugars, water-soluble sugars and sucrose content and sucrose phosphate synthase activity increased, reaching a maximum in the presence of 200 mmol/L NaCI. These parameters were restored to original levels when the algae were transferred to a non-saline medium. Sodium and K+ concentrations of stressed cells decreased significantly and H+-ATPase activity increased after the addition of exogenous sucrose or EPS. The results suggest that EPS and sucrose are synthesized to maintain the cellular osmOtic equilibrium between the intra-and extracellular environment, thus protecting algal cells from osmotic damage, which was attributed to the selective exclusion of cellular Na+ and K+ by H+-ATPase.展开更多
A biochemical some enzymes of glycolysis and a partial reversed tricarboxylic acid cycle together with hydrolytic enzymes in the cyst wall of Echinococcus granulosus was carried out. Lactate dehydrogenase (LDH), pyruv...A biochemical some enzymes of glycolysis and a partial reversed tricarboxylic acid cycle together with hydrolytic enzymes in the cyst wall of Echinococcus granulosus was carried out. Lactate dehydrogenase (LDH), pyruvate kinase (PK), phosphoenolpyruvate carboxykinase (PEPCK), and adenosine triphosphatase (ATPase) showed their high level of activity, suggesting that the proliferation of E. granulosus cyst wall is an energy-dependent process and the major pathways for glucose metabolism is glycolysis. Treatment of E. granulosus-in-fected mice with mebendazole and albendazole resulted in marked inhibition of PK, PEPCK and ATPase of E. granulosus cyst wall, whereas praziquantel had no effect, indicating that PK, PEPCK, and ATPase might be chemotherapeutic targets and the differences in the inhibitory effects might account for the efficacy of the three antihydatid drugs.展开更多
Background: Chronic intermittent hypoxia is the most remarkable feature of obstructive sleep apnea/hypopnea syndrome and it can induce the change of hypoxia-inducible factor-1α (H IF-1α) expression and contractil...Background: Chronic intermittent hypoxia is the most remarkable feature of obstructive sleep apnea/hypopnea syndrome and it can induce the change of hypoxia-inducible factor-1α (H IF-1α) expression and contractile properties in the genioglossus. To clarify the role of HIF-lot in contractile properties of the genioglossus, this study generated and compared high-throughput RNA-sequencing data from genioglossus between HIF-1α conditional knockout (KO) mice and littermate wild-type (WT) mice. Methods: KO mice were generated with cre-loxP strategy. Gene expression profile analysis was performed using gene enrichment analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of differently expressed messenger RNAs were performed to identify the related pathways and biological lhnctions. Six differentially expressed genes (DEGs) were validated by qualitative reverse transcription polymerase chain reaction. Results: A total of 142 (77 upregulated and 65 downregulated) transcripts were found to exhibit statistically significant difference between the HIF-la-KO and WT mice. GO and KEGG analyses indicated that DEGs included genes involved in "skeletal muscle cell differentiation," "muscle organ development," "glucose metabolic process," "glycogen biosynthetic and metabolic process," etc. Conclusion: This study might provide evidence that H IF-lot affects the expression of multiple genes involved in the myogenesis, muscle developrnent, and carbohydrate metabolism through transcriptome analysis in conditional HIE-1α-KO mice.展开更多
A two-factor(23)orthogonal testwas conducted to investigate the effects of dietary myo-inositol(MI)on the osmoregulation and carbohydrate metabolism of euryhaline fish tilapia(Oreochromis niloticus)under sustained hyp...A two-factor(23)orthogonal testwas conducted to investigate the effects of dietary myo-inositol(MI)on the osmoregulation and carbohydrate metabolism of euryhaline fish tilapia(Oreochromis niloticus)under sustained hypertonic stress(20 practical salinity units[psu]).6 diets containing either normal carbohydrate(NC,30%)or high carbohydrate(HC,45%)levels,with 3 levels(0,400 and 1,200 mg/kg diet)of MI,respectively,were fed to 540 fish under 20 psu for 8 weeks.Dietary MI supplementation significantly improved growth performance and crude protein content of whole fish,and decreased the content of crude lipid of whole fish(P<0.05).Curled,disordered gill lamella and cracked gill filament cartilage were observed in the gill of fish fed diets without MI supplementation.The ion transport capacity in gill was significantly improved in the 1,200 mg/kg MI supplementation groups compared with the 0 mg/kg MI groups(P<0.05).Moreover,the contents of Na^(+),K^(+),Cl^(-)in serum weremarkedly reduced with the dietary MI supplementation(P<0.05).The fish fed 1,200 mg/kg MI supplementation had the highest MI content in the gills and the lowest MI content in the serum(P<0.05).Additionally,the fish fed with 1,200 mg/kg MI supplementation had the highest MI synthesis capacity in gills and brain(P<0.05).Dietary MI markedly promoted the ability of carbohydrate metabolism in liver(P<0.05).Moreover,fish in the 1,200 mg/kg MI groups had the highest antioxidant capacity(P<0.05).This study indicated that high dietary carbohydrate would intensify stress,and impair the ability of osmoregulation in tilapia under a long-term hypersaline exposure.The supplementation of MI at 1,200 mg/kg in the high carbohydrate diet could promote carbohydrate utilization and improve the osmoregulation capacity of tilapia under long-term hypertonic stress.展开更多
W25 is a low-temperature-sensitive albino mu-tant line. Temperature not only controls thealbino phenotype expression of W25, but alsodetermines whether it could survive. When thetemperature is lower than 25℃, the lea...W25 is a low-temperature-sensitive albino mu-tant line. Temperature not only controls thealbino phenotype expression of W25, but alsodetermines whether it could survive. When thetemperature is lower than 25℃, the leaves ofW25 shows complete albino, but they exhibitsnormal green when temperature is higher than30℃. Meanwhile, at 25℃, it can be greenable展开更多
The present study aimed to evaluate the effects of chrysoeriol from Cardiospermum halicacabum in streptozotocin induced Wistar rats.Thirty rats were categorized as control,diabetic control supplemented with 0,20 mg/kg...The present study aimed to evaluate the effects of chrysoeriol from Cardiospermum halicacabum in streptozotocin induced Wistar rats.Thirty rats were categorized as control,diabetic control supplemented with 0,20 mg/kg chrysoeriol and 600μg/kg BW of glibenclamide for 45-day trial period.Our results indicated that the inclusion of chrysoeriol(20 mg/kg)showed a significant reduction in plasma glucose,hemoglobin and glycosylated hemoglobin level with a rising of plasma insulin sensitivity.Further,downregulated enzymes including glucose 6-phosphatase,fructose 1,6-bisphosphatase,and glycogen phosphorylase as well upregulated enzymes such as hexokinase,glucose-6-phosphate dehydrogenase,pyruvate kinase,and hepatic glycogen content.There was a diminish action found in liver glycogen synthase of tested rat with a rise in gamma-glutamyl transpeptidase,towards normal levels upon treatment with chrysoeriol.The histopathological study confirmed that renewal of the beta cells of pancreatic of chrysoeriol and glibenclamide treated rats.In addition,the molecular docking of chrysoeriol against glycolytic enzymes including hexokinase,glucose-6-phosphate dehydrogenase,pyruvate kinase,using Argus software shows chrysoeriol had greatest ligand binding energy as equivalent to glibenclamide,as a standard drug.Thus,chrysoeriol found to be non-toxic with potential regulation on glycemic control and upregulation of the carbohydrate metabolic enzymes.展开更多
Of the various strategies adopted by an invasive plant species for expanding its niche breadth,phenotypic differentiation(either due to plasticity and/or adaptive evolution) is proven to be the most successful.Lately,...Of the various strategies adopted by an invasive plant species for expanding its niche breadth,phenotypic differentiation(either due to plasticity and/or adaptive evolution) is proven to be the most successful.Lately,we studied the persistence of substantial morpho-functional variations within the individuals of alien invasive plant,Parthenium hysterophorus in Chandigarh,India,through field surveys.Based on observed differences,the individuals were categorized into two morphotypes,PAand PB.PAhad higher leaf area,leaf biomass,and chlorophyll content as compared with PB.However,PBhad a higher stem circumference,stem specific density,twig dry matter content,profuse branching,bigger canopy,and better reproductive output than PA.To substantiate the persistence of intraspecific variations in P. hysterophorus and to deduce the possible genesis of these variations,we propagated both the morphotypes under experimental conditions in winter and summer.Apart from the key morpho-functional differences observed during the field studies,protein and carbohydrate metabolism were studied in leaves and roots of the propagated plants.Differences in plant metabolism were observed only during the early growth period,whereas the morpho-functional traits varied in the mature flowering plants.The effect of growth season was highly significant on all the studied morpho-functional and biochemical parameters(p ≤0.05).Parent morphotypes(P) and interactions between morphotypes and seasons significantly affected several growth parameters(p ≤0.05).The analyses revealed that the contrasting growth conditions at the time of transplantation and early growth may regulate the phenotype of P. hysterophorus.The pattern of intraspecific variations observed during the study is justified to consider morphotype PAas winter biotype and morphotype PBas summer biotype of P. hysterophorus.The study points towards the role of plasticity or a combination of genetic and environmental(G×E) factors in producing the phenotypic variability observed in the population of P. hysterophorus.展开更多
Cellular metabolism is a very complex process. The biochemical pathways are fundamental structures of biology. These pathways possess a number of regeneration steps which facilitate energy shuttling on a massive scale...Cellular metabolism is a very complex process. The biochemical pathways are fundamental structures of biology. These pathways possess a number of regeneration steps which facilitate energy shuttling on a massive scale. This facilitates the biochemical pathways to sustain the energy currency of the cells. This concept has been mimicked using electronic circuit components and it has been used to increase the efficiency of bio-energy generation. Six of the carbohydrate biochemical pathways have been chosen in which glycolysis is the principle pathway. All the six pathways are interrelated and coordinated in a complex manner. Mimic circuits have been designed for all the six biochemical pathways. The components of the metabolic pathways such as enzymes, cofactors etc., are substituted by appropriate electronic circuit components. Enzymes are related to the gain of transistors by the bond dissociation energies of enzyme-substrate molecules under consideration. Cofactors and coenzymes are represented by switches and capacitors respectively. Resistors are used for proper orientation of the circuits. The energy obtained from the current methods employed for the decomposition of organic matter is used to trigger the mimic circuits. A similar energy shuttle is observed in the mimic circuits and the percentage rise for each cycle of circuit functioning is found to be 78.90. The theoretical calculations have been made using a sample of domestic waste weighing 1.182 kg. The calculations arrived at finally speak of the efficiency of the novel methodology employed.展开更多
Lung cancer has become one of the most common types of cancer,and has the highest morbidity and mortality rates.We herein performed a bioinformatic analysis to explore the gene expression of hexokinase domain containi...Lung cancer has become one of the most common types of cancer,and has the highest morbidity and mortality rates.We herein performed a bioinformatic analysis to explore the gene expression of hexokinase domain containing 1(HKDC1)to further illuminate the molecular mechanisms involved in non-small cell lung cancer(NSCLC).We also examined the relationship between HKDC1 expression and patient survival.The Oncomine and cBioPortal cancer genomics databases were used to investigate the expression of HKDC1 in NSCLC.Then the protein-protein interaction network and protein expression intensity of HKDC1 were examined with the Gene MANIA and The Human Protein Atlas databases.Finally,the prognostic impact of HKDC1 was evaluated via the GEPIA,Oncolnc and Kaplan-Meier Plotter online tools.HKDC1 was significantly up-regulated in NSCLC patients.In addition,the mutation frequency of HKDC1 in NSCLC was high in a large number of studies.Moreover,HKDC1 expression was correlated with a poor prognosis in NSCLC patients.These findings suggest that HKDC1 represents a novel therapeutic target for NSCLC.展开更多
The study was conducted on six reindeers in December.It was established that concentration of reducing sugars in the chyme of jejunum increases substantially(6 times in comparison with abomasum),whereas concentration ...The study was conducted on six reindeers in December.It was established that concentration of reducing sugars in the chyme of jejunum increases substantially(6 times in comparison with abomasum),whereas concentration cellulose,on the contrary,decreases(4.5 times).The maximal increase of monosaccharides in the small intestine testifies to formation of metabolic fund of sugars in this part of the alimentary tract due to high degree of polysaccharides hydrolysis of exogenous,as well as endogenous,microbial formation.Obtained data assume that the need of the reindeer for glucose is provided for not only by gluconeogenesis as it was considered before,but also by absorption of monosaccharides from the alimentary tract.展开更多
Aims: To determine correlations of insulin sensitivity to gene expression in omental and subcutaneous adipose tissue of non-obese, non-diabetic pregnant women. Methods: Microarray gene profiling was performed on subcu...Aims: To determine correlations of insulin sensitivity to gene expression in omental and subcutaneous adipose tissue of non-obese, non-diabetic pregnant women. Methods: Microarray gene profiling was performed on subcutaneous and omental adipose tissue from 14 patients and obtained while fasting during non-laboring Cesarean section, using Illumina HumanHT-12 V4 Expression BeadChips. Findings were validated by real-time PCR. Matusda-Insulin sensitivity index (IS) and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated from glucose and insulin levels obtained from a frequently sampled oral glucose tolerance test, and correlated with gene expression. Results: Of genes differentially expressed in omental vs. subcutaneous adipose, in omentum 12 genes were expressed toward insulin resistance, whereas only 5 genes were expressed toward insulin sensitivity. In particular, expression of the insulin receptor gene (INSR), which initiates the insulin signaling cascade, is strongly positively correlated with IS and negatively with HOMA-IR in omental tissue (r = 0.84). Conclusion: Differential gene expression in omentum relative to subcutaneous adipose showed a pro-insulin resistance profile in omentum. A clinical importance of omental adipose is observed here, as downregulation of insulin receptor in omentum is correlated with increased systemic insulin resistance.展开更多
As an important fruit pest of global significance,Drosophila suzukii occupies a special ecological niche,with the characteristics of high sugar and low protein contents.This niche differs from those occupied by other ...As an important fruit pest of global significance,Drosophila suzukii occupies a special ecological niche,with the characteristics of high sugar and low protein contents.This niche differs from those occupied by other fruit-damaging Drosophila species.Gut bacteria substantially impact the physiology and ecology of insects.However,the contribution of gut microbes to the fitness of D.suzukii in their special ecological niche remains unclear.In this study,the effect of Klebsiella oxytoca on the development of D.suzukii was examined at physiological and molecular levels.The results showed that,after the removal of gut microbiota,the survival rate and longevity of axenic D.suzukii decreased significantly.Reintroduction of K.oxytoca to the midgut of D.suzukii advanced the development level of D.suzukii.The differentially expressed genes and metabolites between axenic and K.oxytoca-reintroduced D.suzukii were enriched in the pathways of carbohydrate metabolism.This advancement was achieved through an increased glycolysis rate and the regulation of the transcript level of key genes in the glycolysis/gluconeogenesis pathway.Klebsiella oxytoca is likely to play an important role in increasing host fitness in their high-sugar ecological niche by stimulating the glycolysis/gluconeogenesis pathway.As a protein source,bacteria can also provide direct nutrition for D.suzukii,which depends on the quantity or biomass of K.oxytoca.This result may provide a new target for controlling D.suzukii by inhibiting sugar metabolism through eliminating the effect of K.oxytoca and thus disrupting the balance of gut microbial communities.展开更多
In most plants, a large fraction of photo-assimilated carbon is stored in the chloroplasts during the day as starch and remobilized during the subsequent night to support metabolism. Mutations blocking either starch s...In most plants, a large fraction of photo-assimilated carbon is stored in the chloroplasts during the day as starch and remobilized during the subsequent night to support metabolism. Mutations blocking either starch synthesis or starch breakdown in Arabidopsis thaliana reduce plant growth. Maltose is the major product of starch breakdown exported from the chloroplast at night. The maltose excess 1 mutant (mex1), which lacks the chloroplast envelope maltose transporter, accumulates high levels of maltose and starch in chloroplasts and develops a distinctive but previously unexplained chlorotic phenotype as leaves mature. The introduction of additional mutations that prevent starch synthesis, or that block maltose production from starch, also prevent chlorosis of mex1. In contrast, introduction of mutations in disproportionating enzyme (DPE1) results in the accumulation of maltotriose in addition to maltose, and greatly increases chlorosis. These data suggest a link between maltose accumulation and chloroplast homeostasis. Microscopic analyses show that the mesophyll cells in chlorotic mex1 leaves have fewer than half the number of chloroplasts than wild-type cells. Transmission electron microscopy reveals autophagy-like chloroplast degradation in both mex1 and the dpe1/mex1 double mutant. Microarray analyses reveal substantial reprogramming of metabolic and cellular processes, suggesting that organellar protein turnover is increased in mex1, though leaf senescence and senescence-related chlorophyll catabolism are not induced. We propose that the accumulation of maltose and malto-oligosaccharides causes chloroplast dysfunction, which may by signaled via a form of retrograde signaling and trigger chloroplast degradation.展开更多
The biosynthesis of isoprenoids in plant cells occurs from precursors produced in the cytosol by the mevalonate (MVA) pathway and in the plastid by the methylerythritol 4-phosphate (MEP) pathway, but little is kno...The biosynthesis of isoprenoids in plant cells occurs from precursors produced in the cytosol by the mevalonate (MVA) pathway and in the plastid by the methylerythritol 4-phosphate (MEP) pathway, but little is known about the mechanisms coordinating both pathways. Evidence of the importance of sugar signaling for such coordination in Arabi- dopsis thaliana is provided here by the characterization of a mutant showing an increased accumulation of MEP-derived isoprenoid products (chlorophylls and carotenoids) without changes in the levels of relevant MEP pathway transcripts, proteins, or enzyme activities. This mutant was found to be a new loss-of-function allele of PRL1 (Pleiotropic Regulatory Locus 1), a gene encoding a conserved WD-protein that functions as a global regulator of sugar, stress, and hormone responses, in part by inhibition of SNFl-related protein kinases (SnRK1). Consistent with the reported role of SnRK1 kinases in the phosphorylation and inactivation of the main regulatory enzyme of the MVA pathway (hydroxymethylglutaryl coenzyme-A reductase), its activity but not transcript or protein levels was reduced in prll seedlings. However, the accumulation of MVA-derived end products (sterols) was unaltered in mutant seedlings. Sucrose supplementation to wild- type seedlings phenocopied the prll mutation in terms of isoprenoid metabolism, suggesting that the observed isoprenoid phenotypes result from the increased sugar accumulation in the prll mutant. In summary, PRL1 appears to coordinate isoprenoid metabolism with sugar, hormone, and stress responses.展开更多
Arabinans are found in the pectic network of many cell walls, where, along with galactan, they are present as side chains of Rhamnogalacturonan I. Whilst arabinans have been reported to be abundant polymers in the cel...Arabinans are found in the pectic network of many cell walls, where, along with galactan, they are present as side chains of Rhamnogalacturonan I. Whilst arabinans have been reported to be abundant polymers in the cell walls of seeds from a range of plant species, their proposed role as a storage reserve has not been thoroughly investigated. In the cell walls of Arabidopsis seeds, arabinose accounts for approximately 40% of the monosaccharide composition of non- cellulosic polysaccharides of embryos. Arabinose levels decline to -15% during seedling establishment, indicating that cell wall arabinans may be mobilized during germination. Immunolocalization of arabinan in embryos, seeds, and seedlings reveals that arabinans accumulate in developing and mature embryos, but disappear during germination and seedling establishment. Experiments using 14C-arabinose show that it is readily incorporated and metabolized in growing seedlings, indicating an active catabolic pathway for this sugar. We found that depleting arabinans in seeds using a fungal arabinanase causes delayed seedling growth, lending support to the hypothesis that these polymers may help fuel early seedling growth.展开更多
The aim of this study was to observe the changes in glucose metabolism after antipsychotic(APS)therapy,to note the influencing factors,as well as to discuss the relationship between the occurrence of glucose metabolis...The aim of this study was to observe the changes in glucose metabolism after antipsychotic(APS)therapy,to note the influencing factors,as well as to discuss the relationship between the occurrence of glucose metabolism disorders of APS origin and abnormal glycosylated hemoglobin(HbA1c)levels.One hundred and fifty-two patients with schizophrenia,whose fasting plasma glucose(FPG)and 2-h plasma glucose(2hPG)in the oral glucose tolerance test(2HPG)were normal,were grouped according to the HbA1c levels,one normal and the other abnormal,and were randomly enrolled into risperidone,clozapine and chlorpromazine treatment for six weeks.The FPG and 2hPG were measured at the baseline and at the end of the study.In the group with abnormal HbA1c and clozapine therapy,2HPG was higher after the study[(9.5±1.8)mmol/L]than that before the study[(7.2±1.4)mmol/L]and the difference was statistically significant(P<0.01).FPG had no statistically significant difference before and after the study in any group(P>0.05).HbA1c levels and drugs contributing to 2HPG at the end of study had statistical cross-action(P<0.01).In the abnormal HbA1c group,2HPG after the study was higher in the clozapine treatment group[(9.5±1.8)mmol/L]than in the risperidone treatment group[(7.4±1.7)mmol/L]and the chlorpromazine treatment group[(7.3±1.6)mmol/L].The differences were statistically significant(P<0.01).In the normal HbA1c group there was no statistically significant difference before and after the study in any group(P>0.05).2HPG before[(7.1±1.6)mmol/L]and after the study[(8.1±1.9)mmol/L]was higher in the abnormal HbA1c group than in the normal HbA1c group[(6.2±1.4)mmol/L vs(6.5±1.4)mmol/L]with the difference being statistically significant(P<0.01 vs P<0.001).As compared with normal HbA1c group,the relative risk(RR)of glucose metabolism disease occurrence was 4.7 in the abnormal HbA1c group with the difference being statistically significant(P<0.001).Patients with abnormal HbA1c are more likely to have a higher risk of having glucose metabolism disorders after APS treatment.展开更多
基金supported by the National Natural Science Foundation of China(grant no.31960385)the Natural Science Foundation of Jiangxi,China(grant no.20212BAB215009)。
文摘Background Mepiquat chloride(MC)application and plant population density(PPD)increasing are required for modern cotton production.However,their interactive effects on leaf physiology and carbohydrate metabolism remain obscure.This study aimed to examine whether and how MC and PPD affect the leaf morpho-physiological characteristics,and thus final cotton yield.PPD of three levels(D1:2.25 plants·m^(-2),D2:4.5 plants·m^(-2),and D3:6.75 plants·m^(-2))and MC dosage of two levels(MC0:0 g·ha^(-2),MC1:82.5 g·ha^(-2))were combined to create six treatments.The dynamics of nonstructual carbohydrate concentration,carbon metabolism-related enzyme activity,and photosynthetic attributes in cotton leaves were examined during reproductive growth in 2019 and 2020.Results Among six treatments,the high PPD of 6.75 plants·m^(-2)combined with MC application(MC1D3)exhibited the greatest seed cotton yield and biological yield.The sucrose,hexose,starch,and total nonstructural carbohydrate(TNC)concentrations peaked at the first flowering(FF)stage and then declined to a minimum at the first boll opening(FBO)stage.Compared with other treatments,MC1D3 improved starch and TNC concentration by 5.4%~88.4%,7.8%~52.0% in 2019,and by 14.6%~55.9%,13.5%~39.7% in 2020 at the FF stage,respectively.Additionally,MC1D3 produced higher transformation rates of starch and TNC from the FF to FBO stages,indicating greater carbon production and utilization efficiency.MC1D3 displayed the maximal specific leaf weight(SLW)at the FBO stage,and the highest chlorophyll a(Chl a),Chl b,and Chl a+b concentration at the mid-late growth phase in both years.The Rubisco activity with MC1D3 was 2.6%~53.2% higher at the flowering and boll setting stages in both years,and 2.4%~52.7% higher at the FBO stage in 2020 than those in other treatments.These results provided a explanation of higher leaf senescence-resistant ability in MC1D3.Conclusion Increasing PPD coupled with MC application improves cotton yield by enhancing leaf carbohydrate production and utilization efficiency and delaying leaf senescence.
文摘This study reported the influence of selenium(Se)on carbohydrate composition and some related enzymes and nutrient compositions of arsenic(As)stressed rice plants.Rice plants of cultivar PR126 were grown on soil amended with As in a range of 25-100μmol/kg with and without 0.5 or 1.0 mg/kg Se.Total soluble sugars(TSS)and reducing sugars(RS)increased in leaves of As stressed plants at the tillering and grain filling stages whereas sucrose and starch contents showed the reverse trend.Se supplementation to As stressed plants further increased TSS and RS,and enhanced sucrose phosphate synthase activity in rice leaves,thus improving sucrose content and the tolerance to As stress of the plants.Se alone or in combination with As resulted in lower As accumulation in rice husk and grains,and the highest reduction was observed in Se applied at 1.0 mg/kg compared to the corresponding As treatments alone.As may limit the accumulations of Na,Mg,K,Ca,Fe,Zn and Mn in rice grains,which are essential for humans.Binary application of different combinations of As and Se protected the plants against As and increased the mineral content in rice grains.Addition of Se in As treated soil significantly alleviated As stress by enhancing grain yields compared to the corresponding As treatment.It is concluded that Se induced amelioration of the toxic impact of As in rice either by modulating carbohydrate composition and/or nutrient uptake is one of the mechanisms to alleviate As stress in plants.
基金supported by the National Natural Science Foundation of China(31672128)the Chinese Universities Scientific Fund(2452020007)。
文摘Auxin(indole-3-acetic acid, IAA) has a considerable impact on the regulation of plant carbohydrate levels and growth, but the mechanism by which it regulates sugar levels in plants has received little attention. In this study, we found that exogenous IAA altered fructose(Fru), glucose(Glc), and sucrose(Suc) concentrations in shoot tips mainly by regulating MdSUSY1, MdFRK2, MdHxK1 and MdSDH2 transcript levels. Additionally, we used 5-year-old ’Royal Gala’ apple trees to further verify that these genes play primary roles in regulating sink strength. The results showed that MdSUSY1, MdFRK2, MdHxK1/3 and MdSDH2 might be major contributors to sink strength regulation. Taken together, these results provide new insight into the regulation of the carbohydrate metabolism mechanism, which will be helpful for regulating sink strength and yield.
文摘Proprotein convertase subtilisin/kexin type 9(PCSK9) plays a paramount role in the degradation of lowdensity lipoprotein(LDL) receptors(LDLR) on the hepatic cells surface and subsequently affects LDL particles catabolism and LDL cholesterol(LDL-c) levels. The anti-PCSK9 monoclonal antibodies lead to substantial decrease of LDL-c concentration. PCSK9(which is also expressed in pancreatic delta-cells) can decrease LDLR and subsequently decrease cholesterol accumulation in pancreatic beta-cells, which impairs glucose metabolism and reduces insulin secretion. Thus, a possible adverse effect of PCSK9 inhibitors on carbohydrate metabolism may be expected by this mechanism, which has been supported by the mendelian studies results. On the other hand, clinical data have suggested a detrimental association of PCSK9 with glucose metabolism. So, the inhibition of PCSK9 may be seen as a double-edged sword regarding carbohydrate metabolism. Completed clinical trials have not shown a detrimental effect of PCSK9 inhibitors on diabetes risk, but their short-term duration does not allow definite conclusions.
基金Supported by the National Natural Science Foundation of China(30500068, 30170112)the Chinese Academy of Sciences(KSCX2-SW-322)
文摘The effects of salt stress on carbohydrate metabolism in Microcoleus vaginatus Gom., a cyanobacterium isolated from desert algal crusts, were investigated in the present study. Extracellular total carbohydrates and exopolysaccharides (EPS) in the culture medium produced by M. vaginatus increased significantly during the growth phase and reached a maximum during the stationary phase. The production of extracellular carbohydrates also significantly increased under higher salt concentrations, which was attributed to an increase in low molecular weight carbohydrates. In the presence of NaCI, the production of cellular total carbohydrates decreased and photosynthetic activity was impaired, whereas cellular reducing sugars, water-soluble sugars and sucrose content and sucrose phosphate synthase activity increased, reaching a maximum in the presence of 200 mmol/L NaCI. These parameters were restored to original levels when the algae were transferred to a non-saline medium. Sodium and K+ concentrations of stressed cells decreased significantly and H+-ATPase activity increased after the addition of exogenous sucrose or EPS. The results suggest that EPS and sucrose are synthesized to maintain the cellular osmOtic equilibrium between the intra-and extracellular environment, thus protecting algal cells from osmotic damage, which was attributed to the selective exclusion of cellular Na+ and K+ by H+-ATPase.
文摘A biochemical some enzymes of glycolysis and a partial reversed tricarboxylic acid cycle together with hydrolytic enzymes in the cyst wall of Echinococcus granulosus was carried out. Lactate dehydrogenase (LDH), pyruvate kinase (PK), phosphoenolpyruvate carboxykinase (PEPCK), and adenosine triphosphatase (ATPase) showed their high level of activity, suggesting that the proliferation of E. granulosus cyst wall is an energy-dependent process and the major pathways for glucose metabolism is glycolysis. Treatment of E. granulosus-in-fected mice with mebendazole and albendazole resulted in marked inhibition of PK, PEPCK and ATPase of E. granulosus cyst wall, whereas praziquantel had no effect, indicating that PK, PEPCK, and ATPase might be chemotherapeutic targets and the differences in the inhibitory effects might account for the efficacy of the three antihydatid drugs.
基金This study was supported by grants from the National Natural Science Foundation of China (No. 81271192 and No. 81600897), and the Shanghai Science and Technology Committee of China (No. 15140903500).
文摘Background: Chronic intermittent hypoxia is the most remarkable feature of obstructive sleep apnea/hypopnea syndrome and it can induce the change of hypoxia-inducible factor-1α (H IF-1α) expression and contractile properties in the genioglossus. To clarify the role of HIF-lot in contractile properties of the genioglossus, this study generated and compared high-throughput RNA-sequencing data from genioglossus between HIF-1α conditional knockout (KO) mice and littermate wild-type (WT) mice. Methods: KO mice were generated with cre-loxP strategy. Gene expression profile analysis was performed using gene enrichment analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of differently expressed messenger RNAs were performed to identify the related pathways and biological lhnctions. Six differentially expressed genes (DEGs) were validated by qualitative reverse transcription polymerase chain reaction. Results: A total of 142 (77 upregulated and 65 downregulated) transcripts were found to exhibit statistically significant difference between the HIF-la-KO and WT mice. GO and KEGG analyses indicated that DEGs included genes involved in "skeletal muscle cell differentiation," "muscle organ development," "glucose metabolic process," "glycogen biosynthetic and metabolic process," etc. Conclusion: This study might provide evidence that H IF-lot affects the expression of multiple genes involved in the myogenesis, muscle developrnent, and carbohydrate metabolism through transcriptome analysis in conditional HIE-1α-KO mice.
基金grants from the National Natural Science Foundation of China(No.32172946)China Postdoctoral Science Foundation(2018 M630418)the Fundamental Research Funds for the Central Universities,ECNU and China Agriculture Research System-46(CARS-46).
文摘A two-factor(23)orthogonal testwas conducted to investigate the effects of dietary myo-inositol(MI)on the osmoregulation and carbohydrate metabolism of euryhaline fish tilapia(Oreochromis niloticus)under sustained hypertonic stress(20 practical salinity units[psu]).6 diets containing either normal carbohydrate(NC,30%)or high carbohydrate(HC,45%)levels,with 3 levels(0,400 and 1,200 mg/kg diet)of MI,respectively,were fed to 540 fish under 20 psu for 8 weeks.Dietary MI supplementation significantly improved growth performance and crude protein content of whole fish,and decreased the content of crude lipid of whole fish(P<0.05).Curled,disordered gill lamella and cracked gill filament cartilage were observed in the gill of fish fed diets without MI supplementation.The ion transport capacity in gill was significantly improved in the 1,200 mg/kg MI supplementation groups compared with the 0 mg/kg MI groups(P<0.05).Moreover,the contents of Na^(+),K^(+),Cl^(-)in serum weremarkedly reduced with the dietary MI supplementation(P<0.05).The fish fed 1,200 mg/kg MI supplementation had the highest MI content in the gills and the lowest MI content in the serum(P<0.05).Additionally,the fish fed with 1,200 mg/kg MI supplementation had the highest MI synthesis capacity in gills and brain(P<0.05).Dietary MI markedly promoted the ability of carbohydrate metabolism in liver(P<0.05).Moreover,fish in the 1,200 mg/kg MI groups had the highest antioxidant capacity(P<0.05).This study indicated that high dietary carbohydrate would intensify stress,and impair the ability of osmoregulation in tilapia under a long-term hypersaline exposure.The supplementation of MI at 1,200 mg/kg in the high carbohydrate diet could promote carbohydrate utilization and improve the osmoregulation capacity of tilapia under long-term hypertonic stress.
文摘W25 is a low-temperature-sensitive albino mu-tant line. Temperature not only controls thealbino phenotype expression of W25, but alsodetermines whether it could survive. When thetemperature is lower than 25℃, the leaves ofW25 shows complete albino, but they exhibitsnormal green when temperature is higher than30℃. Meanwhile, at 25℃, it can be greenable
文摘The present study aimed to evaluate the effects of chrysoeriol from Cardiospermum halicacabum in streptozotocin induced Wistar rats.Thirty rats were categorized as control,diabetic control supplemented with 0,20 mg/kg chrysoeriol and 600μg/kg BW of glibenclamide for 45-day trial period.Our results indicated that the inclusion of chrysoeriol(20 mg/kg)showed a significant reduction in plasma glucose,hemoglobin and glycosylated hemoglobin level with a rising of plasma insulin sensitivity.Further,downregulated enzymes including glucose 6-phosphatase,fructose 1,6-bisphosphatase,and glycogen phosphorylase as well upregulated enzymes such as hexokinase,glucose-6-phosphate dehydrogenase,pyruvate kinase,and hepatic glycogen content.There was a diminish action found in liver glycogen synthase of tested rat with a rise in gamma-glutamyl transpeptidase,towards normal levels upon treatment with chrysoeriol.The histopathological study confirmed that renewal of the beta cells of pancreatic of chrysoeriol and glibenclamide treated rats.In addition,the molecular docking of chrysoeriol against glycolytic enzymes including hexokinase,glucose-6-phosphate dehydrogenase,pyruvate kinase,using Argus software shows chrysoeriol had greatest ligand binding energy as equivalent to glibenclamide,as a standard drug.Thus,chrysoeriol found to be non-toxic with potential regulation on glycemic control and upregulation of the carbohydrate metabolic enzymes.
文摘Of the various strategies adopted by an invasive plant species for expanding its niche breadth,phenotypic differentiation(either due to plasticity and/or adaptive evolution) is proven to be the most successful.Lately,we studied the persistence of substantial morpho-functional variations within the individuals of alien invasive plant,Parthenium hysterophorus in Chandigarh,India,through field surveys.Based on observed differences,the individuals were categorized into two morphotypes,PAand PB.PAhad higher leaf area,leaf biomass,and chlorophyll content as compared with PB.However,PBhad a higher stem circumference,stem specific density,twig dry matter content,profuse branching,bigger canopy,and better reproductive output than PA.To substantiate the persistence of intraspecific variations in P. hysterophorus and to deduce the possible genesis of these variations,we propagated both the morphotypes under experimental conditions in winter and summer.Apart from the key morpho-functional differences observed during the field studies,protein and carbohydrate metabolism were studied in leaves and roots of the propagated plants.Differences in plant metabolism were observed only during the early growth period,whereas the morpho-functional traits varied in the mature flowering plants.The effect of growth season was highly significant on all the studied morpho-functional and biochemical parameters(p ≤0.05).Parent morphotypes(P) and interactions between morphotypes and seasons significantly affected several growth parameters(p ≤0.05).The analyses revealed that the contrasting growth conditions at the time of transplantation and early growth may regulate the phenotype of P. hysterophorus.The pattern of intraspecific variations observed during the study is justified to consider morphotype PAas winter biotype and morphotype PBas summer biotype of P. hysterophorus.The study points towards the role of plasticity or a combination of genetic and environmental(G×E) factors in producing the phenotypic variability observed in the population of P. hysterophorus.
文摘Cellular metabolism is a very complex process. The biochemical pathways are fundamental structures of biology. These pathways possess a number of regeneration steps which facilitate energy shuttling on a massive scale. This facilitates the biochemical pathways to sustain the energy currency of the cells. This concept has been mimicked using electronic circuit components and it has been used to increase the efficiency of bio-energy generation. Six of the carbohydrate biochemical pathways have been chosen in which glycolysis is the principle pathway. All the six pathways are interrelated and coordinated in a complex manner. Mimic circuits have been designed for all the six biochemical pathways. The components of the metabolic pathways such as enzymes, cofactors etc., are substituted by appropriate electronic circuit components. Enzymes are related to the gain of transistors by the bond dissociation energies of enzyme-substrate molecules under consideration. Cofactors and coenzymes are represented by switches and capacitors respectively. Resistors are used for proper orientation of the circuits. The energy obtained from the current methods employed for the decomposition of organic matter is used to trigger the mimic circuits. A similar energy shuttle is observed in the mimic circuits and the percentage rise for each cycle of circuit functioning is found to be 78.90. The theoretical calculations have been made using a sample of domestic waste weighing 1.182 kg. The calculations arrived at finally speak of the efficiency of the novel methodology employed.
基金the National Natural Science Foundation of China(No.81860494).
文摘Lung cancer has become one of the most common types of cancer,and has the highest morbidity and mortality rates.We herein performed a bioinformatic analysis to explore the gene expression of hexokinase domain containing 1(HKDC1)to further illuminate the molecular mechanisms involved in non-small cell lung cancer(NSCLC).We also examined the relationship between HKDC1 expression and patient survival.The Oncomine and cBioPortal cancer genomics databases were used to investigate the expression of HKDC1 in NSCLC.Then the protein-protein interaction network and protein expression intensity of HKDC1 were examined with the Gene MANIA and The Human Protein Atlas databases.Finally,the prognostic impact of HKDC1 was evaluated via the GEPIA,Oncolnc and Kaplan-Meier Plotter online tools.HKDC1 was significantly up-regulated in NSCLC patients.In addition,the mutation frequency of HKDC1 in NSCLC was high in a large number of studies.Moreover,HKDC1 expression was correlated with a poor prognosis in NSCLC patients.These findings suggest that HKDC1 represents a novel therapeutic target for NSCLC.
文摘The study was conducted on six reindeers in December.It was established that concentration of reducing sugars in the chyme of jejunum increases substantially(6 times in comparison with abomasum),whereas concentration cellulose,on the contrary,decreases(4.5 times).The maximal increase of monosaccharides in the small intestine testifies to formation of metabolic fund of sugars in this part of the alimentary tract due to high degree of polysaccharides hydrolysis of exogenous,as well as endogenous,microbial formation.Obtained data assume that the need of the reindeer for glucose is provided for not only by gluconeogenesis as it was considered before,but also by absorption of monosaccharides from the alimentary tract.
文摘Aims: To determine correlations of insulin sensitivity to gene expression in omental and subcutaneous adipose tissue of non-obese, non-diabetic pregnant women. Methods: Microarray gene profiling was performed on subcutaneous and omental adipose tissue from 14 patients and obtained while fasting during non-laboring Cesarean section, using Illumina HumanHT-12 V4 Expression BeadChips. Findings were validated by real-time PCR. Matusda-Insulin sensitivity index (IS) and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated from glucose and insulin levels obtained from a frequently sampled oral glucose tolerance test, and correlated with gene expression. Results: Of genes differentially expressed in omental vs. subcutaneous adipose, in omentum 12 genes were expressed toward insulin resistance, whereas only 5 genes were expressed toward insulin sensitivity. In particular, expression of the insulin receptor gene (INSR), which initiates the insulin signaling cascade, is strongly positively correlated with IS and negatively with HOMA-IR in omental tissue (r = 0.84). Conclusion: Differential gene expression in omentum relative to subcutaneous adipose showed a pro-insulin resistance profile in omentum. A clinical importance of omental adipose is observed here, as downregulation of insulin receptor in omentum is correlated with increased systemic insulin resistance.
基金supported financially through grants from the National Natural Science Foundation of China(31801750,31972273)Science and Technology In-novation Project of Shandong Academy of Agricul-tural Sciences(CXG2023A24,CXG2023A47)National.Natural Science Foundation of Shandong province(ZR2021YQ21,ZR2021QC218).
文摘As an important fruit pest of global significance,Drosophila suzukii occupies a special ecological niche,with the characteristics of high sugar and low protein contents.This niche differs from those occupied by other fruit-damaging Drosophila species.Gut bacteria substantially impact the physiology and ecology of insects.However,the contribution of gut microbes to the fitness of D.suzukii in their special ecological niche remains unclear.In this study,the effect of Klebsiella oxytoca on the development of D.suzukii was examined at physiological and molecular levels.The results showed that,after the removal of gut microbiota,the survival rate and longevity of axenic D.suzukii decreased significantly.Reintroduction of K.oxytoca to the midgut of D.suzukii advanced the development level of D.suzukii.The differentially expressed genes and metabolites between axenic and K.oxytoca-reintroduced D.suzukii were enriched in the pathways of carbohydrate metabolism.This advancement was achieved through an increased glycolysis rate and the regulation of the transcript level of key genes in the glycolysis/gluconeogenesis pathway.Klebsiella oxytoca is likely to play an important role in increasing host fitness in their high-sugar ecological niche by stimulating the glycolysis/gluconeogenesis pathway.As a protein source,bacteria can also provide direct nutrition for D.suzukii,which depends on the quantity or biomass of K.oxytoca.This result may provide a new target for controlling D.suzukii by inhibiting sugar metabolism through eliminating the effect of K.oxytoca and thus disrupting the balance of gut microbial communities.
基金ACKNOWLEDGMENTS We thank Sabine Klarer for help growing plants, Martine Trevisan for technical assistance, Phillip Zimmermann, Lars Hennig, Hubert Rehrauer, and Marzanna Kuenzli for advice and assistance with the microarray analysis, Teresa Koller for assistance with quantitative RT-PCR, Miriam Lucas, Stephan Handschin, Heinz Gross, and Roger A. Wepf for advice and assistance with electron microscopy, and Jean-David Rochaix for advice on chlorophyll fluorescence measurements. The GWD antibody was a gift from Dr G. Ritte and Prof.M. Steup, University of Potsdam, a gift from Prof. S. Smith, Univers No conflict of interest declared. Germany. The DPE1 antibody was ty of Western Australia, Australia.This work was funded by the ETH Zurich, the Swiss National Science Foundation (National Centre of Competence in Research- Plant Survival), and SystemsX.ch (Plant Growth in a Changing Environment).
文摘In most plants, a large fraction of photo-assimilated carbon is stored in the chloroplasts during the day as starch and remobilized during the subsequent night to support metabolism. Mutations blocking either starch synthesis or starch breakdown in Arabidopsis thaliana reduce plant growth. Maltose is the major product of starch breakdown exported from the chloroplast at night. The maltose excess 1 mutant (mex1), which lacks the chloroplast envelope maltose transporter, accumulates high levels of maltose and starch in chloroplasts and develops a distinctive but previously unexplained chlorotic phenotype as leaves mature. The introduction of additional mutations that prevent starch synthesis, or that block maltose production from starch, also prevent chlorosis of mex1. In contrast, introduction of mutations in disproportionating enzyme (DPE1) results in the accumulation of maltotriose in addition to maltose, and greatly increases chlorosis. These data suggest a link between maltose accumulation and chloroplast homeostasis. Microscopic analyses show that the mesophyll cells in chlorotic mex1 leaves have fewer than half the number of chloroplasts than wild-type cells. Transmission electron microscopy reveals autophagy-like chloroplast degradation in both mex1 and the dpe1/mex1 double mutant. Microarray analyses reveal substantial reprogramming of metabolic and cellular processes, suggesting that organellar protein turnover is increased in mex1, though leaf senescence and senescence-related chlorophyll catabolism are not induced. We propose that the accumulation of maltose and malto-oligosaccharides causes chloroplast dysfunction, which may by signaled via a form of retrograde signaling and trigger chloroplast degradation.
文摘The biosynthesis of isoprenoids in plant cells occurs from precursors produced in the cytosol by the mevalonate (MVA) pathway and in the plastid by the methylerythritol 4-phosphate (MEP) pathway, but little is known about the mechanisms coordinating both pathways. Evidence of the importance of sugar signaling for such coordination in Arabi- dopsis thaliana is provided here by the characterization of a mutant showing an increased accumulation of MEP-derived isoprenoid products (chlorophylls and carotenoids) without changes in the levels of relevant MEP pathway transcripts, proteins, or enzyme activities. This mutant was found to be a new loss-of-function allele of PRL1 (Pleiotropic Regulatory Locus 1), a gene encoding a conserved WD-protein that functions as a global regulator of sugar, stress, and hormone responses, in part by inhibition of SNFl-related protein kinases (SnRK1). Consistent with the reported role of SnRK1 kinases in the phosphorylation and inactivation of the main regulatory enzyme of the MVA pathway (hydroxymethylglutaryl coenzyme-A reductase), its activity but not transcript or protein levels was reduced in prll seedlings. However, the accumulation of MVA-derived end products (sterols) was unaltered in mutant seedlings. Sucrose supplementation to wild- type seedlings phenocopied the prll mutation in terms of isoprenoid metabolism, suggesting that the observed isoprenoid phenotypes result from the increased sugar accumulation in the prll mutant. In summary, PRL1 appears to coordinate isoprenoid metabolism with sugar, hormone, and stress responses.
文摘Arabinans are found in the pectic network of many cell walls, where, along with galactan, they are present as side chains of Rhamnogalacturonan I. Whilst arabinans have been reported to be abundant polymers in the cell walls of seeds from a range of plant species, their proposed role as a storage reserve has not been thoroughly investigated. In the cell walls of Arabidopsis seeds, arabinose accounts for approximately 40% of the monosaccharide composition of non- cellulosic polysaccharides of embryos. Arabinose levels decline to -15% during seedling establishment, indicating that cell wall arabinans may be mobilized during germination. Immunolocalization of arabinan in embryos, seeds, and seedlings reveals that arabinans accumulate in developing and mature embryos, but disappear during germination and seedling establishment. Experiments using 14C-arabinose show that it is readily incorporated and metabolized in growing seedlings, indicating an active catabolic pathway for this sugar. We found that depleting arabinans in seeds using a fungal arabinanase causes delayed seedling growth, lending support to the hypothesis that these polymers may help fuel early seedling growth.
文摘The aim of this study was to observe the changes in glucose metabolism after antipsychotic(APS)therapy,to note the influencing factors,as well as to discuss the relationship between the occurrence of glucose metabolism disorders of APS origin and abnormal glycosylated hemoglobin(HbA1c)levels.One hundred and fifty-two patients with schizophrenia,whose fasting plasma glucose(FPG)and 2-h plasma glucose(2hPG)in the oral glucose tolerance test(2HPG)were normal,were grouped according to the HbA1c levels,one normal and the other abnormal,and were randomly enrolled into risperidone,clozapine and chlorpromazine treatment for six weeks.The FPG and 2hPG were measured at the baseline and at the end of the study.In the group with abnormal HbA1c and clozapine therapy,2HPG was higher after the study[(9.5±1.8)mmol/L]than that before the study[(7.2±1.4)mmol/L]and the difference was statistically significant(P<0.01).FPG had no statistically significant difference before and after the study in any group(P>0.05).HbA1c levels and drugs contributing to 2HPG at the end of study had statistical cross-action(P<0.01).In the abnormal HbA1c group,2HPG after the study was higher in the clozapine treatment group[(9.5±1.8)mmol/L]than in the risperidone treatment group[(7.4±1.7)mmol/L]and the chlorpromazine treatment group[(7.3±1.6)mmol/L].The differences were statistically significant(P<0.01).In the normal HbA1c group there was no statistically significant difference before and after the study in any group(P>0.05).2HPG before[(7.1±1.6)mmol/L]and after the study[(8.1±1.9)mmol/L]was higher in the abnormal HbA1c group than in the normal HbA1c group[(6.2±1.4)mmol/L vs(6.5±1.4)mmol/L]with the difference being statistically significant(P<0.01 vs P<0.001).As compared with normal HbA1c group,the relative risk(RR)of glucose metabolism disease occurrence was 4.7 in the abnormal HbA1c group with the difference being statistically significant(P<0.001).Patients with abnormal HbA1c are more likely to have a higher risk of having glucose metabolism disorders after APS treatment.