| Description | Lactic acid is an important intermediate product in the metabolic processes of organisms, closely related to carbohydrate metabolism, lipid metabolism, protein metabolism, and intracellular energy metabolism. Lactic acid concentration is a key indicator for evaluating glycogen metabolism and aerobicLactic acid is an important intermediate product in the metabolic processes of organisms, closely related to carbohydrate metabolism, lipid metabolism, protein metabolism, and intracellular energy metabolism. Lactic acid concentration is a key indicator for evaluating glycogen metabolism and aerobic metabolism. Abnormally high concentrations of lactic acid are associated with pathological conditions such as cancer, diabetes, and lactic acidosis.The detection principle of this kit is as follows: Lactate dehydrogenase catalyzes the conversion of L-lactate to pyruvate, simultaneously reducing NAD+ to NADH and H+. Further, through the hydrogen transfer action of 1-mPMS, WST-8 reacts to form a yellow, soluble formazan. The absorbance at 450 nm is measured to calculate the L-lactate content in the sample.Detection Range: 0.03-2 mMSensitivity: 0.03 mMApplicable Samples: Animal and plant tissues, cells, bacteria, serum (plasma), or other liquids.L1501211Component48T96TStorageL1501211ALactate Assay Buffer70 mL70 mL×22-8℃L1501211BLactate Dehydrogenase0.7 mL1.4 mL-20℃L1501211CLactate Dehydrogenase Cofactor0.5 mL1 mL-20℃L1501211DWST-8350 µL700 µL-20℃. Store in the dark.L1501211EEnhancer70 µL140 µL-20℃. Store in the dark.L1501211FL(+)-Lactate Standard (100 mM)50 µL100 µL-20℃Please check the quantity of each component before the experiment.An additional 10% of each component is provided beyond the specified volume for standard curve preparation or preliminary experiments.User-Provided Instruments and ReagentsTypeNameNotesInstrumentMicroplate ReaderCapable of measuring absorbance at 450 nm.Consumables96-well MicroplateStandard transparent plate.ReagentsPBS (pH 7.4)For washing samples.OthersHomogenizer (for tissue samples), incubator, ice machine, low-temperature centrifuge, adjustable pipettes and tipsUsing a multichannel pipette for large-scale detection can improve efficiency.Experimental Procedure1. Reagent PreparationReagent NameReagent PreparationPrecautionsLactate Assay BufferReady-to-use; equilibrate to room temperature before use.4℃保存 Store at 4°C.Lactate DehydrogenaseReady-to-use;Keep on ice during the experiment; store aliquots at -20°C.Lactate Dehydrogenase CofactorReady-to-use;Keep on ice during the experiment; store aliquots at -20°C.WST-8Ready-to-use;Keep on ice during the experiment; store aliquots at -20°C.EnhancerReady-to-use;Keep on ice protected from light during the experiment; store aliquots at -20°C protected from light.L(+)-Lactate Standard (100 mM)Equilibrate to room temperature before use.100 mM, store aliquots at -20°C.2. Standard PreparationAdd 20 µL of the 100 mM standard to 980 µL of Lactate Assay Buffer to prepare a 2 mM standard stock solution. Aliquot and store at -20°C for up to 6 months. Dilute the 2 mM standard stock solution sequentially with Lactate Assay Buffer to prepare standard working solutions with final concentrations of 1 mM, 0.5 mM, 0.25 mM, 0.125 mM, 0.0625 mM, and 0.03125 mM. Use Lactate Assay Buffer as the blank.Standard Working SolutionStandard (µL)Lactate Assay Buffer (µL)Concentration (mM)1200 µL of 2 mM022200 µL of 2 mM20013200 µL of 1 mM2000.54200 µL of 0.5 mM2000.255200 µL of 0.25 mM2000.1256200 µL of 0.125 mM2000.06257200 µL of 0.0625 mM2000.03125Blank020003. Sample PreparationNote: Fresh samples are recommended. If not used immediately, samples can be stored at -80°C for up to 1 month. NADH or NADPH present in cell or tissue extracts can create background for lactate assay. To remove NADH or NADPH background, an equal amount of sample can be assayed without lactate dehydrogenase, and the background reading should be subtracted from the lactate reading. Endogenous lactate dehydrogenase (LDH) can degrade lactate. Samples containing LDH (e.g., cell culture medium, cell or tissue lysates) should be processed using a 10 kDa MW cutoff ultrafiltration tube (centrifuge at 12,000 g, 4°C for 10 min; follow the filter instructions) to remove all proteins. Use the filtrate for detection, then store at -80°C.3.1 Animal/Plant Tissues: Weigh approximately 0.1 g of tissue sample, add 1 mL of Lactate Assay Buffer, and homogenize on ice. Centrifuge at 12,000 g, 4°C for 5 min. Transfer the supernatant to a new tube and keep on ice for detection.3.2 Cells or Bacteria: Collect 5×10^6 cells. Wash the cells or bacteria with pre-cooled PBS. Centrifuge at 800 g for 2 min, discard the supernatant. Add 1 mL of Lactate Assay Buffer, and disrupt using an ultrasonic homogenizer on ice for 5 min (power 20% or 200 W, ultrasonic 3 s, interval 7 s, repeat 30 times). Centrifuge at 12,000 g, 4°C for 5 min. Collect the supernatant and keep on ice for detection.3.3 Plasma and Serum (Other Biological Fluids): Detect directly.4. Experimental Steps4.1 Microplate Reader Preparation: Preheat for at least 30 minutes, set wavelength to 450 nm.4.2 Working Reagent Preparation: 50 µL of Working Reagent is required per well. To avoid loss, prepare for 55 µL per single well system: Pipette 31 µL Lactate Assay Buffer, 8 µL Lactate Dehydrogenase Cofactor, 5 µL WST-8, 1 µL Enhancer, and 10 µL Lactate Dehydrogenase. Mix well. The Working Reagent must be prepared freshly and used immediately.4.3 Assay System Setup: Set up the detection system in the microplate according to the table below. The standard curve generally needs to be performed only once.ReagentStandard Well (µL)Test Well (µL)Sample050Standard Working Solution500Working Reagent50504.4 Absorbance Measurement: Mix well and incubate at 37°C protected from light for 30 min. Read the absorbance at 450 nm, recorded as Ablank, Astandard, and Atest. 5. Result CalculationThe following provides both the derived formula and the simplified calculation formula, which are completely equivalent.5.1 Data ProcessingCalculate ΔAstandard= Astandard- Ablank, ΔAtest = Atest - Ablank.5.2 Standard Curve PlottingPlot the standard curve with standard concentration as the y-axis and ΔAstandard as the x-axis. Substitute ΔAstandard into the equation to obtain the y value (mM).5.3 Sample L-Lactate Content Calculation① Calculated based on sample weight:L-Lactate (µmol/g) = y × Vsample ÷ (W × Vsample ÷ Vtotal) × n = y ÷ W × n② Calculated based on cell or bacterial count:L-Lactate (µmol/10⁴ cells) = y × Vsample ÷ (500 × Vsample ÷ Vtotal) × n = y ÷ 500 × n③ Calculated based on liquid volume:L-Lactate (mM) = y × Vsample ÷ Vsample × n = y × n④ Calculated based on protein concentration:L-Lactate (µmol/mg prot) = y × Vsample ÷ (Vsample × Cpr) × n = y ÷ Cpr × nParameter Description:1 mM = 1 mmol/L;Vsample : Volume of sample added, 0.05 mL;n: Sample dilution factor;Cpr: Sample protein concentration, mg/mL;W: Sample weight, g;Vtotal: Total volume of sample extract, 1 mL;500: Cell or bacterial count, 5×10⁶, converted to units of 10⁴.Result Presentation Using Previous Standard CurveTypical Standard Curve: y = 2.2613x - 0.0531Example-1: 50 µL of chicken serum was taken and processed according to the assay steps using a 96-well plate. The measured ΔAtest = Atest - Ablank= 0.435 - 0.096 = 0.339. Substituting into the standard curve, y = 0.713 mM. Calculated based on liquid volume: Lactate content (mM) = y × n = 0.713 × 5 = 3.565 mM.PrecautionsIt is recommended to perform preliminary experiments using 2-3 samples expected to have significant differences before formal testing.For tissue and cell samples, results can be normalized by measuring the protein concentration.This kit is compatible with spectrophotometer detection. Adjust the preparation volume of detection reagents proportionally according to the spectrophotometer's requirements.It is recommended to establish your own standard curve for improved accuracy. If not, you may refer to the typical standard curve formula provided in the results section for calculation.Biochemical reagents are generally irritating and biologically toxic. For your safety and health, please wear appropriate personal protective equipment (lab coat, mask, gloves, hair cap, etc.) throughout the experiment and perform experiments in a fume hood or biosafety cabinet.This product is for scientific research use only. Not intended for clinical diagnosis.Frequently Asked QuestionsWhat should I do if the sample ΔAtest is too high or too low?If the sample ΔAtest is >1.0, the lactate content in the sample is too high. Dilute the sample appropriately with Lactate Assay Buffer (multiply by the dilution factor in the calculation). If the sample ΔAtest is <0.13, increase the sample amount... Read More | Inquire | Product introduction：Dualucif The firefly & Renilla assay kit (dual luciferase reporter assay kit) provides an effective means to detect the expression of genes. In DLR detection, the activities of firefly luciferase and Renilla luciferase can be detected in a single sample in turn. FirstProduct introduction：Dualucif The firefly & Renilla assay kit (dual luciferase reporter assay kit) provides an effective means to detect the expression of genes. In DLR detection, the activities of firefly luciferase and Renilla luciferase can be detected in a single sample in turn. First, luciferin was used as substrate to detect the activity of firefly luciferase, then substances inhibiting the catalysis of firefly luciferase were added, and coelenterazine was added to detect the activity of Renilla luciferase to achieve dual luciferase reporter gene detection. The bioluminescence system of luciferase and its substrate can detect gene expression very sensitively and efficiently. Usually, the transcriptional regulatory element or 5'promoter region of the gene of interest is cloned upstream of luciferase, or the 3'-utr region is cloned downstream of luciferase to construct a reporter gene plasmid, and then transfect the cells. After the cells are treated with appropriate drugs, the cells are lysed, and the transcriptional regulation effect of drug treatment on the target gene is judged by detecting the luciferase activity. Renilla luciferase is more often used as an internal reference for detecting transfection efficiency to eliminate the difference in cell number and transfection efficiency. Firefly luciferase is a protein with a molecular weight of about 61 kDa. In the presence of ATP, magnesium ions and oxygen, it can catalyze the production of oxyluciferin from luciferin. In the process of luciferin oxidation, it will produce a light signal. Renilla luciferase is a protein with a molecular weight of about 36 kDa. In the presence of oxygen, it can catalyze the oxidation of coelenteramide to coelenteramide, and also produce light signals in the process of coelenteramide oxidation. The optical signal of this kit can be measured by chemiluminescence instrument, microplate reader or liquid scintillation tester. The kit has the characteristics of rapid detection, high sensitivity, wide detection range and no interference of cell endogenous activity.Instruction：1.Cell lysis ( 1 ) Remove the medium and gently wash twice with PBS ( adherent cells can be operated directly, suspension cells need to be centrifuged to collect cells ). Add 1 × Lysis Buffer ( diluted component A with sterile water at 4 : 1 ) according to the following scheme, and then place the culture plate on a micro-oscillator at room temperature for 15 min to fully lyse the cells. Note : The pyrolysis products can be stored at room temperature for 6 h, and can be stored at − 70 °C for a long time ( the pyrolysis products cannot be repeatedly frozen and thawed ). ( 2 ) The pyrolysis products were centrifuged at 10000-15000 rpm for 3-5 min. After centrifugation, the supernatant was transferred into a new EP tube for subsequent detection. Note : Cells can be detected immediately after lysis, or frozen, and re-detected when needed. The frozen samples need to be thawed to room temperature for detection. 2. Preparation of working fluid ( 1 ) Restore all components to room temperature. ( 2 ) Dilute component C with component B to 0.2 mg / mL firefly luciferase working solution. Note : The firefly luciferase working solution cannot be repeatedly frozen and thawed. If the amount of a single experiment is small, it is recommended to be subpackaged into small specifications according to a single amount of use. ( 3 ) The E component was diluted into the renilla luciferase working solution with the D component, and the dilution method was 1 µL E component was added to the 49 µL D component. Note : Renilla luciferase working solution needs to be prepared now. 3.chemiluminescence value detection ( 1 ) According to the operation instructions of the instrument, the instrument with chemiluminescence detection function was opened, such as multifunctional microplate reader. The parameters were set, the determination time was 10 s, and the determination interval was 2 s. ( 2 ) each sample determination, take the sample 20-100 µL ( if the sample volume is enough, please add 100 µL ; if the sample amount is insufficient, the amount can be appropriately reduced, but the amount of detection holes needs to be consistent ). 1 × Lysis Buffer was blank control. ( 3 ) 100 µL firefly luciferase working solution was added to determine the RLU ( relative light unit ) value ( it is recommended that the microplate reader set up the Shaking mixing function ). Note : Since the luminescence is instantaneous, it is recommended to detect immediately after adding the firefly luciferase working solution. ( 4 ) 100 µL renilla luciferase working solution was added to determine the RLU ( relative light unit ) value ( Shaking mixing function is recommended for microplate reader ). ( 5 ) In the case of renilla luciferase as an internal reference, the RLU value measured by firefly luciferase was divided by the RLU value measured by renilla luciferase. According to the obtained ratio, the activation degree of the target reporter gene between different samples was compared. If firefly luciferase is used as an internal reference, similar calculations can also be performed.Component：Recommendation：It is recommended to use component B in advance to prepare 2 mg / mL storage solution, component B, component D and component C prepared as storage solution, and to carry out small batch packing according to the experimental requirements. All test working fluids are recommended to be used now to avoid repeated freezing and thawing.Matters needing attention：1. please centrifuge the product to the bottom of the tube immediately before use, and then conduct subsequent experiments. 2. in order to obtain the best determination effect, when using a single tube chemiluminescence instrument for determination, the time from the mixing of sample and determination reagent to the pre determination should be controlled as much as possible; When using a multi-functional fluorescent microplate reader with chemiluminescence detection function, it is advisable to add all samples first, and then uniformly add firefly luciferase detection reagent. 3. the strongest wavelength of firefly luciferase catalyzed bioluminescence is 560 nm, and the strongest wavelength of Renilla luciferase catalyzed bioluminescence is 480 nm. 4. to prevent interference between holes, it is recommended to use white opaque orifice plate. 5. due to the influence of temperature on enzyme reaction, the sample and reagent should be measured after reaching room temperature. 6. for your safety and health, please wear experimental clothes and disposable gloves.Scope of application：Study on gene expression regulation and promoter... Read More | The content of this cell is too long for an XLSX file (more than 32767 characters). Please use the CSV format for this export | Product introduction： The MA qPCR live bacteria detection kit provides an effective means for detecting bacterial activity. The kit provides a mixture of PMA dye and qPCR based on SYBR Green dye. The optimal amount of dye and the number of samples that can be treated may vary depending on theProduct introduction： The MA qPCR live bacteria detection kit provides an effective means for detecting bacterial activity. The kit provides a mixture of PMA dye and qPCR based on SYBR Green dye. The optimal amount of dye and the number of samples that can be treated may vary depending on the type of sample. PMA is a high-affinity DNA-binding dye, especially with double-stranded DNA. The dye itself has weak fluorescence, but it can emit brighter fluorescence after binding to nucleic acids. PMA is impermeable to cell membranes, so it can selectively modify the DNA of dead cells with damaged membranes. After the PMA-modified DNA is photolyzed by blue light ( ~ 464 nm ), the photoreactive azide group on the PMA is converted into a highly reactive nitrene radical, which reacts with any hydrocarbon near the DNA binding site to form a stable covalent nitrogen-carbon bond, resulting in permanent DNA modification. This modification process will make DNA insoluble and lost with cell debris during the later genomic DNA extraction process. The unbound PMA remaining in the solution reacts with water molecules under strong light irradiation to decompose into hydroxylamine compounds without cross-linking activity, so that it can no longer covalently bind to DNA. Based on this feature of PMA, PMA was combined with qPCR technology to form a new detection method, PMA-qPCR, for the screening of live bacteria. At present, the method has been verified in a variety of bacterial strains, yeast, fungi, viruses and parasites. The treatment of complex samples, such as manure or soil, may require optimization of sample dilution, dye concentration, and light treatment time. The treatment of diluted samples, such as water testing, may require filtration or concentration prior to dye treatment. Matters needing attention：1. please centrifuge the product to the bottom of the tube immediately before use, and then conduct subsequent experiments. 2. the components of the kit contain fluorescent dyes. Avoid light during use and storage. 3. for your safety and health, please wear experimental clothes and disposable gloves.Product parameters:Spectral characteristics :PMA: Ex = 464 nm; Ex/Em = 510/610 nm (following photolysis and reaction with DNA/RNA)Component： PMA：Ex = 464 nm; Ex/Em = 510/610 nm (following photolysis and reaction with DNA/RNA) Instruction： Precautions before use： 1.This live bacteria detection kit distinguishes dead bacteria and live bacteria according to cell membrane permeability. Many methods of killing bacteria cause damage to the cell membrane and are therefore compatible with this kit. But some methods, such as ultraviolet irradiation, may not immediately cause cell membrane rupture. Therefore, before selecting this kit, it is necessary to carry out literature search and pre-experiment to determine whether the kit is suitable for the bacterial type and killing method you choose. 2.After PMA treatment, the bacteria need to be photolyzed to covalently bind the dye to dead cell DNA. Photolysis operations can use blue or white light sources. Generally speaking, the brighter the lamp, the higher the efficiency of the photolysis step. Non-LED lamps ( such as halogen lamps ) may heat your sample and have a negative impact on the analysis. Ice is required to cool the sample during irradiation. 3.Sample can be cryopreservation after photolysis. Frozen samples before PMA treatment photolysis may damage the cell membrane and produce false negative results. If the sample needs to be frozen before detection, it is recommended to perform a pre-experiment first. 4.Part of the mechanism of PMA is to remove PMA covalently modified DNA from the sample by precipitation ; therefore, when extracting genomic DNA, it is necessary to use the same volume of genomic DNA eluent for volume normalization. The positive control can use the genomic DNA of living cells. 5.In order to verify the effectiveness of PMA in the test sample, the Ct ( dCt ) changes between- / + PMA can be compared. Experimental materials ( self-provided )：①Light source ( for the photolysis step after PMA modification of DNA ) ; ② Bacterial genomic DNA extraction kit ; ③ effective qPCR primers corresponding to the sample type Experimental procedure： 1.Suck 10 µL of E.coli bacterial solution in liquid LB medium, and culture E.coli in the bacterial incubator overnight or longer to the logarithmic growth phase ( OD600 ≈ 1.0 ) ; Note : The culture time is adjusted according to the experiment. 2.Two portions of live E.coli, 400 µL each, were placed in a clean centrifuge tube ; 3. ( Recommended ) Preparation of dead E.coli. If the dead E.coli is needed as a control, the dead E.coli can be obtained by heating the living E.coli in a water bath at 95 °C for 5 min, or at 58 °C for 3 h. the subsequent operation of the dead E. coli is the same as that of the living E. coli ; 4.Two copies of live E.coli, one without PMA treatment, and one with 25 µM PMA treatment ( the optimal PMA concentration for treating different types or different sources of bacteria needs to be consulted in the relevant literature ) ; 5.The PMA-treated samples were placed on a shaker at room temperature and incubated in the dark for 10 min to fully mix the dye with the sample ; 6.Exposure of the sample, you can use blue or white light source, irradiation time to explore their own. For example, a 60 W blue light can be used for 15 min. Note : 1 If a halogen lamp is used, we recommend that the PMA-treated sample tube be placed on an ice block 20 cm away from the light source. Ice should be placed in a transparent tray. Adjust the light source to point directly to the sample, photolysis for 5-15 min ; if the bacteria obtained from the environment are directly used for experiments, due to the complexity or turbidity of the environmental samples, the photolysis time needs to be prolonged appropriately. 7.Treated and untreated live E.coli 5000 × g, centrifuged for 10 min, remove the supernatant ; 8.Select the appropriate genomic DNA extraction kit according to the sample type, and use the same elution volume for each group of samples when elution DNA. Note : DNA extraction steps refer to the instructions of the kit used. Part of the mechanism of action of PMA is to remove PMA-bound DNA from the sample by precipitation ; therefore, when extracting genomic DNA, each group should use the same volume of genomic DNA eluent for volume normalization ( the amount of genomic DNA extracted from dead bacteria and live bacteria is inconsistent, so the concentration of the two is significantly different ). 9.Preparation of reaction mixture according to the following system : Note : 1 For the DNA extracted by commercial DNA extraction kit, the qPCR template was optimized with 2 µL as the initial volume ; 2 The template volume should not exceed 10 % of the final reaction volume ; 3 Template concentration : gDNA as template, usually 1-10 ng ; the final concentration of PCR primers is usually 0.4µM, which can get better results. When the reaction performance is poor, the primer concentration can be adjusted in the range of 0.2-1µM. 10.Slightly vortex the reaction mixture, transfer the fixed volume to the PCR tube. 11. Test procedure Note : 1 The extension time is adjusted according to the instrument ; the Taq enzyme in mix can be activated within 2 min, but the genomic DNA may require longer denaturation time, which can be increased at this time, and the specific denaturation time can be adjusted according to the sample type.12. ( Optional ) Data analysis Using live bacteria and dead bacteria as controls, the number of live cells in the sample was analyzed and calculated. It is recommended to verify the suitability of primers and PCR procedures before starting PMA qPCR detection of live bacteria. Calculation of dead and living bacteria control dCt ( 1 ) After the end of qPCR, the Ct value of each sample was calculated by instrument software ; ( 2 ) By calculating the dCt of each control bacteria, it was judged whether PMA successfully inhibited the amplification of dead bacterial DNA. The calculation is as follows : dCt live = Ct ( live, PMA treated ) -Ct ( live, PMA untreated ) dCt die = Ct ( die, PMA treated ) -Ct ( die, PMA untreated ) ( 3 ) The dCt expectation of living bacteria is close to 0 ± 1, which indicates that PMA does not affect the amplification of living cell DNA ;( 4 ) The expected value of dCt of dead bacteria is greater than 4 ( dCt is 4 means that it is reduced by about 16 times, that is, 94 % of dead bacterial DNA is removed ; a dCt of 8 indicated a decrease of about 250 times, that is, 99.6 % of the dead bacterial DNA was removed ).( 5 ) The dCt of dead bacteria depends on many factors, including : strain / cell type ; the way bacteria are killed ; the concentration of PMA used ; amplified sequence length. 13. Calculation of the proportion of viable ( optional ) bacteria If the control results of dead and live bacteria are normal, the proportion of live bacteria in the sample can be calculated.( 1 ) Calculate the dCt value of the sample : dCt sample = Ct ( sample, PMA treated ) -Ct ( sample, PMA untreated ) ( 2 ) Conversion of dCt value to live bacteria ratio : PMA inhibition multiple = 2 ( sample dCt ) Viable bacteria % = 100 / PMA inhibition multiple 14. ( Optional ) Calculate the absolute number of live bacteria If you want to calculate the absolute number of viable bacteria in the sample, you need to use a known number of target bacteria genomic DNA to make a standard curve. It is recommended that the diluted concentrations of several groups of genomes are within the range of the qPCR analysis system.( 1 ) qPCR was performed with the appropriate genome, and the Ct value was used as the ordinate, and the number of cells was used as the abscissa. The R2 value is calculated to determine the linearity, and the slope and y-axis intercept are displayed. ( 2 ) Calculate the copy number of the experimental samples : Ct = slope * cell number + y axis intercept ( y = mx + b ) Bacterial count sample = ( Ct-y axis intercept ) / slope Note : The live bacterial DNA was not lost during the purification process. Examples : Scope of application：Live bacteria detection... Read More |