Accumulation of silicon in shoots is required for reducing lead uptake in rice

Silicon(Si) treatment has been shown to reduce the toxicity and accumulation of lead(Pb) in many plants,including rice.The mechanisms responsible for this effect are poorly understood.We investigated the effects of Si treatment on Pb toxicity and accumulation in two rice mutants(lsi1 and lsi2) defective in Si uptake and in their wild types.Si did not alleviate Pb-induced inhibition of root elongation in shortterm experiments,but reduced Pb accumulation in wild types,but not in mutants,in long-term experiments.Pre-treatment with Si reduced Pb concentration in xylem sap and Pb accumulation in wild types but not in mutants.In split-root experiments,Si treatment reduced Pb accumulation but did not alter Pb localization in roots.Si treatment suppressed the expression of many genes encoding proteins that may participate in Pb uptake and transport in the wild type,but not in the lsi1 mutant.These results indicate that Si accumulation in shoots is required to reduce Pb uptake in rice and that the effect is achieved via Siinduced suppression of genes encoding proteins involved in Pb uptake and/or transport.

Effects of Regulation of C/N Ratio Wheat Straw Application on Nitrogen,Phosphorus and Potassium Uptake in Tobacco

[Objective]The aim was to study the effects of regulation of C/N ratio wheat straw application on tobacco nitrogen,phosphorus and potassium uptake. [Method]Effects of regulation C/N ratio wheat straw application on the flue-cured tobacco yield,output value,nitrogen,phosphorus and potassium content and cumulative uptake of the upper,middle and bottom leaf were studied by using the field plot experiments at Banqiao town,Qujing city,Yunnan Province during the 2008-2009 summer growing seasons. [Result]The results showed that the application of wheat straw alone or after C/N regulation,could significantly increase tobacco production,potassium content,the potassium and nitrogen accumulation amount of leaf,and was more conducive to the potassium uptake of tobacco leaf with wheat straw application after C/N regulation. Compared with non-straw application,the yield of tobacco increased by 6.59%,3.58%,5.98%,8.80% with application of wheat straw alone,wheat straw and vetch,wheat straw and oilseed cake,wheat straw and urea nitrogen,the potassium content in tobacco leaf increased by 3.85%,7.76%,8.82%,11.21%,respectively,the total potassium cumulative amount of leaf increased by 10.71%,11.62%,15.32% ,21.01% and the total nitrogen cumulative amount increased by 9.76%,1.22%,8.14%,14.00%. However,the differences of tobacco leaf nitrogen content among the different treatments were not significant,the phosphorus uptake of tobacco leaf decreased. [Conclusion]application of high C/N ratio wheat straw in flue-cured tobacco production,which should be concerned not only to adjust C/N ratio by adding nitrogen,but also considering additional phosphorus application.

Effects of Slow-release Fertilizer and Balanced Fertilization on Nitrogen, Phosphorus and Potassium Uptake in Peppers

Field plot experiment was conducted to study the effects of two slow-re- lease fertilizers and balanced fertilization on dry matter accumulation, yield, fertilizer use efficiency, nitrogen, phosphorus and potassium uptake of peppers at Jiangna Town, Yanshan County, Yunnan Province in 2011. The results showed that the dry matter accumulation in dried pepper plant, pepper yield, nitrogen, phosphorus, potassium uptake in peppers were significantly increased in all the fertilizer treat- ments, compared with those in control （no fertilizer）. Compared with conventional fertilization, balanced fertilization, slow-release compound fertilizer and slow-release urea fertilizer significantly increased dried pepper economic output by 20.94%, 17.5% and 14.54%, nitrogen uptake in dried peppers by 21.53%,18.46% and 13.19%, phosphorus uptake in dried peppers by 14.08%, 15.76% and 10.44%, potassium uptake in dried peppers by 22.66%, 15.73% and 16.28%; they also in- creased nitrogen and potassium use efficiency, but reduced potassium use efficiency due to the increased potassium addition. In treatments with balanced fertilization, slow-release compound fertilizer and slow-release urea fertilizer, the nitrogen utiliza- tion was 5.84%, 7.14% and 8.33% higher and the phosphorus utilization was 3.32%, 3.27% and 2.47% higher than those in treatment with conventional fertiliza- tion. In addition, the nitrogen application could be reduced by 20%-50% by bal- anced fertilization and the two slow-release fertilizers, thereby reducing environmen- tal pollution. Slow-release fertilizers could also reduce the frequency of fertilization and labor costs.

Effect of swirling flow on LDL and ox-LDL uptake in rabbit thoracic aorta

Object To elucidate the physiological significance of the spiral flow in the arterial system from the viewpoint of atherogenic lipid transport,an ex vivo experimental comparative

Teachers' Oral Corrective Feedback and Its Influence on Learner Uptake in the Classes of Teaching English as a Foreign Language for Minority Students in Xinjiang Junior High Schools

The present study explored the features and the effectiveness of teachers' oral CF in the classrooms of Teaching English as a Foreign Language(TEFL) for minority students in Xinjiang junior high schools. The analytical framework of this study consulted Lyster's(1998) coding scheme. 720 minutes of classroom observation were recorded and transcribed. The database was coded and the distribution of errors, CF and uptake was analyzed.

Effects of Atmospheric CO_2 Enrichment, Applied Nitrogen and Soil Moisture on Dry Matter Accumulation and Nitrogen Uptake in Spring Wheat

Spring wheat (Triticum aestivum L. cv. Dingxi No. 8654) was treated with twoconcentrations of atmospheric CO_2 (350 and 700 μmol mol^(-1)), two levels of soil moisture(well-watered and drought) and five rates of nitrogen fertilizer (0, 50, 100, 150, and 200 mgkg^(-1) soil) to study the atmospheric CO_2 concentration effect on dry matter accumulation and Nuptake of spring wheat. The effects of CO_2 enrichment on the shoot and total mass depended largelyon soil nitrogen level, and the shoot and total mass increased significantly in the moderate to highN treatments but did not increase significantly in the low N treatment. Enriched CO_2 concentrationdid not increase more shoot and total mass in the drought treatment than in the well-wateredtreatment. Thus, elevated CO_2 did not ameliorate the depressive effects of drought and nitrogenstress. In addition, root mass decreased slightly and root/shoot ratio decreased significantly dueto CO_2 enrichment in no N treatment under well-watered condition. Enriched CO_2 decreased shoot Ncontent and shoot and total N uptake; but it reduced root N content and uptake slightly. Shootcritical N concentration was lower for spring wheat grown at 700 μmol mol^(-1) CO_2 than at 350μmol mol^(-1) CO_2 in both well-watered and drought treatments. The critical N concentrations were16 and 19 g kg^(-1) for the well-watered treatment and drought treatment at elevated CO_2 and 21 and26 g kg^(-1) at ambient CO_2, respectively. The reductions in the movement of nutrients to theplant roots through mass flow due to the enhancement in WUE (water use efficiency) and the increasein N use efficiency at elevated CO_2 could elucidate the reduction of shoot and root Nconcentrations.

Anti-diabetic effects of Caulerpa lentillifera:stimulation of insulin secretion in pancreatic β-cells and enhancement of glucose uptake in adipocytes

Objective:To evaluate anti-diabetic effect of Caulrpa kntillifera(C.lentillifera).Methods:The inhibitory effect of C.lentillifera extract on dipeptidyl peptidase-IV and a-glucosidase enzyme was measured in a cell free system.Then,interleukin-1βand interferon-γinduced cell death and insulin secretion were measured in rat insulinoma(RIN)cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and ELISA kit,respectively.Glucose uptake and glucose transporter expression were measured by fluorometry and western blotting,using 3T3-Ll adipocytes.Results:C.lentillifera extract significantly decreased dipeptidyl peptidase-IV and a-glucosidase enzyme activities,and effectively inhibited cell death and iNOS expression in interleukin-1βand interfcron-γinduced RIK cells.Furthermore,C.lntillifera extract significantly enhanced insulin secretion in RTN cells and glucose transporter expression and glucose uptake in 3T3-L1adipocytes.Conclusions:Thus,our results suggest that C.lentillifera could be used as a potential antidiabetic agenl.

Interaction effect of nitrogen form and planting density on plant growth and nutrient uptake in maize seedlings

High planting density is essential to increasing maize grain yield.However,single plants suffer from insufficient light under high planting density.Ammonium(NH_4^+)assimilation consumes less energy converted from radiation than nitrateIt is hypothesized that a mixed NO_3~–/NH_4^+supply is more important to improving plant growth and population productivity under high vs.low planting density.Maize plants were grown under hydroponic conditions at two planting densities(low density:only).A significant interaction effect was found between planting density and N form on plant biomass.Compared to nitrate only,75/25NO_3~–/NH_4^+increased per-plant biomass by 44%under low density,but by 81%under high density.Treatment with 75/25NO_3~–/NH_4^+increased plant ATP,photosynthetic rate,and carbon amount per plant by 31,7,and 44%under low density,respectively,but by 51,23,and 95%under high density.Accordingly,carbon level per plant under 75/25NO_3~–/NH_4^+was improved,which increased leaf area,specific leaf weight and total root length,especially for high planting density,increased by 57,17 and 63%,respectively.Furthermore,under low density,75/25NO_3~–/NH_4^+increased nitrogen uptake rate,while under high density,75/25NO_3~–/NH_4^+increased nitrogen,phosphorus,copper and iron uptake rates.By increasing energy use efficiency,an optimum NO_3~–/NH_4^+ratio can improve plant growth and nutrient uptake efficiency,especially under high planting density.In summary,an appropriate supply of NH_4^+in addition to nitrate can greatly improve plant growth and promote population productivity of maize under high planting density,and therefore a mixed N form is recommended for high-yielding maize management in the field.

Cd uptake in rice cultivars treated with organic acids and EDTA

A pot experiment was conducted to examine the activity of antioxidant enzymes, the content of malondialdehyde （MDA）, proline and protein, and Cd uptake in different rice cultivars exposed to Cd （0, 1 and 5 mg/kg） in the presence of organic acids and ethylenediamine tetraacetic acid （EDTA）. The results showed the increase in activity of dismutase （SOD）, contents of proline and protein but a decline in activities of peroxidase （POD） and catalase （CAT）, and MDA content for cultivars Xiushui63 and IIyou527. The resistance to Cd was higher in Xiushui63 than that in IIyou527 under the same Cd treatment. Cadmium contents in grain, straw and roots of both cultivars were markedly reduced in the presence of organic acids and EDTA. Grain Cd contents was the highest for plants treated with organic acids, followed by organic acids ＋ 1/2EDTA, and the lowest with EDTA; Cd contents in straw and root were the lowest for plants treated with organic acids, followed by organic acids ＋ 1/2EDTA, and the highest with EDTA treatment when exposed to Cd.

Plant Phosphorus Uptake in a Soybean-Citrus Intercropping System in the Red Soil Hilly Region of South China

A field microplot experiment was conducted in the red soil hilly region of South China to evaluate plant phosphorus (P)uptake under soybean and citrus monoculture and the soybean-citrus intercropping system using the 32P tracer technique.P fertilizer was applied at three depths(15,35,and 55 cm).The experimental results showed that the planting pattern and 32P application depth significantly affected the characteristics of P uptake by soybean and citrus.Under the soybean-citrus intercropping system,considerable competition was observed when the 32P fertilizer was applied to the topsoil(15 cm);therefore,the 32P recovery rate declined by 41.5%and 14.7%for soybean and citrus,and 32P supplying amount of topsoil to soybean and citrus decreased by 346.8 and 148.1 mg plot-1,respectively,compared to those under the monoculture.However,32P recovery of soybean was promoted when 32P fertilizer was applied to the deeper soil layers (35 and 55 cm)under soybean-citrus intercropping.Under the soybean monoculture,32P fertilizer could hardly be used by soybean when 32P fertilizer was applied at the 55 cm depth or below,with the recovery rate being less than 0.1%;it was up to 0.253%by soybean under intercropping.The higher P recovery of soybean under soybean-citrus intercropping when P was applied in the deeper soil layers was because part of the P nutrient that the citrus absorbed from the deeper soil layers could be released into the topsoil and then it could be used by the soybean.

Biological nitrogen removal with enhanced phosphate uptake in (AO)2SBR using single sludge system

Simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake via nitrite was investigated in an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor((AO)2 SBR). The system showed stable phosphorus and nitrogen removal performance, and average removals for COD, TN and TP were 90%, 91% and 96%, respectively. The conditions of pH 7.5—8.0 and temperature 32℃ were found detrimental to nitrite oxidation bacteria but favorable to ammonia oxidizers, and the corresponding specific oxygen uptake rates(SOUR) for phase 1 and 2 of nitrification process were 0.7 and 15 mgO 2/(gVSS·h) in respect, which led to the nitrite accumulation in aerobic phase of(AO)2 SBR. Respiratory tests showed that 40 mgNO 2-N/L did not deteriorate the sludge activity drastically, and it implied that exposure of sludge to nitrite periodically enabled the biomass to have more tolerance capacity to resist the restraining effects from nitrite. In addition, batch tests were carried out and verified that denitrifying phosphorus accumulation organisms(DPAOs) could be enriched in a single sludge system coexisting with nitrifiers by introducing an anoxic phase in an anaerobic-aerobic SBR, and the ratio of the anoxic phosphate uptake capacity to aerobic phosphate uptake capacity was 45%. It was also found that nitrite(up to 20 mgNO 2-N/L) was not inhibitory to anoxic phosphate uptake and could serve as an electron acceptor like nitrate, but presented poorer efficiency compared with nitrate.

Estimates of Anthropogenic CO_2 Uptake in a Global Ocean Model

A global ocean general circulation model （L30T63） is employed to study the uptake and distribution of anthropogenic CO2 in the ocean. A subgrid-scale mixing scheme called GM90 is used in the model. There are two main GM90 parameters including isopycnal diffusivity and skew （thickness） diffusivity. Sensitivities of the ocean circulation and the redistribution of dissolved anthropogenic CO2 to these two parameters are examined. Two runs estimate the global oceanic anthropogenic CO2 uptake to be 1.64 and 1.73 Pg C yr^-1 for the 1990s, and that the global ocean contained 86.8 and 92.7 Pg C of anthropogenic CO2 at the end of 1994, respectively. Both the total inventory and uptake from our model are smaller than the data-based estimates. In this presentation, the vertical distributions of anthropogenic CO2 at three meridional sections are discussed and compared with the available data-based estimates. The inventory in the individual basins is also calculated. Use of large isopycnal diffusivity can generally improve the simulated results, including the exchange flux, the vertical distribution patterns, inventory, storage, etc. In terms of comparison of the vertical distributions and column inventory, we find that the total inventory in the Pacific Ocean obtained from our model is in good agreement with the data-based estimate, but a large difference exists in the Atlantic Ocean, particularly in the South Atlantic. The main reasons are weak vertical mixing and that our model generates small exchange fluxes of anthropogenic CO2 in the Southern Ocean. Improvement in the simulation of the vertical transport and sea ice in the Southern Ocean is important in future work.

A New Method to Determine Central Wavelength and Optimal Bandwidth for Predicting Plant Nitrogen Uptake in Winter Wheat

Plant nitrogen （N） uptake is a good indicator of crop N status. In this study, a new method was designed to determine the central wavelength, optimal bandwidth and vegetation indices for predicting plant N uptake （g N m-2） in winter wheat （Triticum aestivum L.）. The data were collected from the ground-based hyperspectral reflectance measurements in eight field experiments on winter wheat of different years, eco-sites, varieties, N rates, sowing dates, and densities. The plant N uptake index （PNUI） based on NDVI of 807 nm combined with 736 nm was selected as the optimal vegetation index, and a linear model was developed with R2 of 0.870 and RMSE of 1.546 g N m-2 for calibration, and R2 of 0.834, RMSE of 1.316 g N m-2, slope of 0.934, and intercept of 0.001 for validation. Then, the effect of the bandwidth of central wavelengths on model performance was determined based on the interaction between central wavelength and bandwidth expansion. The results indicated that the optimal bandwidth varies with the changes of the central wavelength and with the interaction between the two bands in one vegetation index. These findings are important for prediction and diagnosis of plant N uptake more precise and accurate in crop management.

Non-leguminous winter cover crop and nitrogen rate in relation to double rice grain yield and nitrogen uptake in Dongting Lake Plain, Hunan Province, China

Annual ryegrass（Lolium multiflorum Lam.）, a non-leguminous winter cover crop, has been adopted to absorb soil native N to minimize N loss from an intensive double rice cropping system in southern China, but a little is known about its effects on rice grain yield and rice N use efficiency. In this study, effects of ryegrass on double rice yield, N uptake and use efficiency were measured under different fertilizer N rates. A 3-year（2009–2011） field experiment arranged in a split-plot design was undertaken. Main plots were ryegrass（RG） as a winter cover crop and winter fallow（WF） without weed. Subplots were three N treatments for each rice season： 0（N_0）, 100（N_（100）） and 200 kg N ha–1（N_（200））. In the 3-year experiment, RG reduced grain yield and plant N uptake for early rice（0.4–1.7 t ha–1 for grain yield and 4.6–20.3 kg ha–1 for N uptake） and double rice（0.6–2.0 t ha–1 for grain yield and 6.3–27.0 kg ha–1 for N uptake） when compared with WF among different N rates. Yield and N uptake decrease due to RG was smaller in N_（100） and N_（200） plots than in N_0 plots. The reduction in early rice grain yield in RG plots was associated with decrease number of panicles. Agronomic N use efficiency and fertilizer N recovery efficiency were higher in RG plots than winter fallow for early rice and double rice among different N rates and experimental years. RG tended to have little effect on grain yield, N uptake, agronomic N use efficiency, and fertilizer N recovery efficiency in the late rice season. These results suggest that ryegrass may reduce grain yield while it improves rice N use efficiency in a double rice cropping system.

Evaluation of the net CO_2 uptake in the Canada Basin in the summer of 2008

The third Chinese National Arctic Research Expedition （CHINARE） was conducted in the summer of 2008. During the survey, the surface seawater partial pressure of CO2 （pCO2） was measured, and sea water samples were collected for CO2 measurement in the Canada Basin. The distribution of pCO2 in the Canada Basin was determined, the influencing factors were addressed, and the air-sea CO2 flux in the Canada Basin was evaluated. The Canada Basin was divided into three regions： the ice-free zone （south of 77°N）, the partially ice-covered zone （77°-80°N）, and the heavily ice-covered zone （north of 80°N）. In the ice-free zone, pCO2 was high （320 to 368 patm, 1 patm=0.101 325 Pa）, primarily due to rapid equilibration with atmospheric CO2 over a short time. In the partially ice-covered zone, the surface pCOs was relatively low （250 to 270 patm） due to ice-edge blooms and icemelt water dilution. In the heavily ice-covered zone, the seawater pCO2 varied between 270 and 300 laatm due to biological COs removal, the transportation of low pCOs water northward, and heavy ice cover. The surface seawater pCO2 during the survey was undersaturated with respect to the atmosphere in the Canada Basin, and it was a net sink for atmospheric CO2. The summertime net CO2 uptake of the ice-free zone, the partially ice-covered zone and the heavily ice-covered zone was （4.14±1.08）, （1.79±0.19）, and （0.57±0.03） Tg/a （calculated by carbon, 1 Tg=10^12 g）, respectively. Overall, the net COs sink of the Canada Basin in the summer of 2008 was （6.5＋1.3） Tg/a, which accounted for 4%-10% of the Arctic Ocean COs sink.

Glutamine synthetase activity and glutamate uptake in hippocampus and frontal cortex in portal hypertensive rats

AIM: To study glutamine synthetase (GS) activity and glutamate uptake in the hippocampus and frontal cortex (FC) from rats with prehepatic portal vein hypertension. METHODS: Male Wistar rats were divided into shamoperated group and a portal hypertension (PH) group with a regulated stricture of the portal vein. Animals were sacrificed by decapitation 14 d after portal vein stricture. GS activity was determined in the hippocampus and FC. Specific uptake of radiolabeled L-glutamate was studied using synaptosome-enriched fractions that were freshly prepared from both brain areas. RESULTS: We observed that the activity of GS increased in the hippocampus of PH rats, as compared to control animals, and decreased in the FC. A significant decrease in glutamate uptake was found in both brain areas, and was more marked in the hippocampus. The decrease in glutamate uptake might have been caused by a deficient transport function, signif icantly and persistent increase in this excitatory neurotransmitter activity. CONCLUSION: The presence of moderate ammonia blood levels may add to the toxicity of excitotoxic glutamate in the brain, which causes alterations in brain function. Portal vein stricture that causes portal hypertension modif ies the normal function in some brain regions.

STUDY ON LAWS OF ANNUAL NUTRIENT UPTAKE IN A PAU LOWNIA PLANTATION

Laws of annual nutrient uptake of 8-yr.-old paulowia (Paulownia Sieb. et Zucc.)plantation (spacing in row 6m, row spacing 10m) in Fengqiu paulownia experimental spot in Huanghuaihai plain was studied for 2 years by using scientific methods and became clear. Annual total uptakes of 5 macronutrients (N, P, K, Ca, and Mg) in 1989 and 1990 were 287.3238 and 242.4234Kg/hm2 a respectively. The study found the following laws, (1 ) the nutrient uptakes of different paulownia organs came in the following order: foliage> branches > flowers> stems> roots, (2) the uptake of different nutrient elements came in the following sequence: N> Ca> K> P> Mg, (3)paulownia's uptake rate of nutrient elememnts was mainly conducted during the period between the beginning of growth and the end of July.

Fluorodeoxyglucose uptake in absence of CT abnormality on PET-CT: What is it?

The purpose of this article is to provide a pictorial review of the findings and interpretative pitfalls about focal fluorodeoxyglucose(FDG)uptake in the absence of corresponding computer tomography(CT)lesion or abnormality on an integrated positron emission tomography(PET)-CT.The integrated CT images in the PET-CT scanner allow correct co-registration and fused imaging of anatomical and functional data.On FDG PET-CT imaging,a real pathologic process often demonstrates abnormal uptake associated with a visible corresponding CT lesion or abnormality.When focal uptake is seen on PET imaging but no corresponding anatomic abnormality is visualized on the integrated CT,one should always be aware of possible mis-registration or mismatch of the PET and CT images due to the patient’s respiratory or body motion.While most of the hot spots in the absence of corresponding anatomic abnormalities are artefactual or secondary to benign etiologies,some may represent small sized or early staged neoplasm or metastases,especially in the gastrointestinal tract and skeletons.Caution should be exercised to simply diagnose a pathology based on the presence of the uptake only,or exclude the disease based on the absence of anatomic abnormality.

Brassinosteroids modulate nitrogen physiological response and promote nitrogen uptake in maize(Zea mays L.)

Brassinosteroids(BRs)are steroid hormones that function in plant growth and development and response to environmental stresses and nutrient supplies.However,few studies have investigated the effect of BRs in modulating the physiological response to nitrogen(N)supply in maize.In the present study,BR signalingdeficient mutant zmbri1-RNAi lines and exogenous application of 2,4-epibrassinolide(e BL)were used to study the role of BRs in the regulation of physiological response in maize seedlings supplied with N.Exogenous application of e BL increased primary root length and plant biomass,but zmbri1 plants showed shorter primary roots and less plant biomass than wild-type plants under low N(LN)and normal N(NN)conditions.LN induced the expression of the BR signaling-associated genes Zm DWF4,Zm CPD,Zm DET2,and Zm BZR1 and the production of longer primary roots than NN.Knockdown of Zm BRI1 weakened the biological effects of LN-induced primary root elongation.e BL treatment increased N accumulation in shoots and roots of maize seedlings exposed to LN or NN treatment.Correspondingly,zmbri1 plants showed lower N accumulation in shoots and roots than wild-type plants.Along with reduced N accumulation,zmbri1 plants showed lower NO3-fluxes and^(15)NO_(3)^(-)uptake.The expression of nitrate transporter(NRT)genes(Zm NPF6.4,Zm NPF6.6,Zm NRT2.1,Zm NRT2.2)was lower in zmbri1 than in wild-type roots,but e BL treatments up-regulated the transcript expression of NRT genes.Thus,BRs modulated N physiological response and regulated the transcript expression of NRT genes to promote N uptake in maize.

Decarboxylated osteocalcin,a possible drug for type 2 diabetes,triggers glucose uptake in MG63 cells

BACKGROUND Uncarboxylated osteocalcin(GluOC)has been reported to improve glucose metabolism,prevent type 2 diabetes,and decrease the severity of obesity in mice with type 2 diabetes.GluOC can increase glucose uptake in a variety of cells.Glucose metabolism is the main source of energy for osteoblast proliferation and differentiation.We hypothesized that decarboxylated osteocalcin(dcOC),a kind of GluOC,can increase glucose uptake in MG63 cells(osteoblast-like osteosarcoma cells)and influence their proliferation and differentiation.AIM To investigate the effects of dcOC on glucose uptake in human osteoblast-like osteosarcoma cells and the possible signaling pathways involved.METHODS MG63 cells(human osteoblast-like osteosarcoma cells)were treated with dcOC(0,0.3,3,10,or 30 ng/mL)for 1 and 72 h,and glucose uptake was measured by flow cytometry.The effect of dcOC on cell proliferation was measured with a CCK-8 assay,and alkaline phosphatase(ALP)enzyme activity was measured.PI3K was inhibited with LY294002,and hypoxia-inducible factor 1 alpha(HIF-1α)was silenced with siRNA.Then,GPRC6A(G protein-coupled receptor family C group 6 subtype A),total Akt,phosphorylated Akt,HIF-1α,and glucose transporter 1(GLUT1)levels were measured by Western blot to elucidate the possible pathways by which dcOC modulates glucose uptake.RESULTS The glucose uptake of MG63 cells was significantly increased compared with that of the paired control cells after short-term(1 h)treatment with dcOC at different concentrations(0.3,3,and 10 ng/mL groups,P<0.01;30 ng/mL group,P<0.05).Glucose uptake of MG63 cells was significantly increased compared with that of the paired control cells after long-term(72 h)treatment with dcOC at different concentrations(0.3,3,and 10 ng/mL groups,P<0.01;30 ng/mL group,P<0.05).DcOC triggered Akt phosphorylation in a dose-dependent manner,and the most effective stimulatory concentration of dcOC for short-term(1 h)was 3 ng/mL(P<0.01).LY294002 abolished the dcOC-mediated(1 h)promotion of Akt phosphorylation and glucose uptake without affecting GLUT1 protein expression.Long-term dcOC stimulation triggered Akt phosphorylation and increased the protein levels of HIF-1α,GLUT1,and Runx2 in a dose-dependent manner.Inhibition of HIF-1αwith siRNA abolished the dcOC-mediated glucose uptake and substantially decreased GLUT1 protein expression.DcOC interven-tion promoted cell proliferation in a time-and dose-dependent manner as determined by the CCK-8 assay.Treatment with both 3 ng/mL and 10 ng/mL dcOC affected the ALP activity in MG63 cells after 72 h(P<0.01).CONCLUSION Short-and long-term dcOC treatment can increase glucose uptake and affect proliferation and ALP activity in MG63 cells.This effect may occur through the PI3K/Akt,HIF-1α,and GLUT1 signaling factors.