| Description | The content of this cell is too long for an XLSX file (more than 32767 characters). Please use the CSV format for this export | When apoptosis occurs, some DNA endonucleases will be activated. These endonucleases will cut off genomic DNA between nucleosomes and produce 180 bp-200 BP DNA fragments, which appear as a specific ladder pattern in agarose gel electrophoresis. When double strand or single strand breaks occur in When apoptosis occurs, some DNA endonucleases will be activated. These endonucleases will cut off genomic DNA between nucleosomes and produce 180 bp-200 BP DNA fragments, which appear as a specific ladder pattern in agarose gel electrophoresis. When double strand or single strand breaks occur in genomic DNA, a large number of sticky 3'-oh ends will be generated, which can interact with YF under the catalysis of deoxyribonucleotide terminal transferase (TDT) ®/ CY dUTP binding can directly detect apoptotic cells by fluorescence microscopy or flow cytometry. This kind of method is called terminal deoxynucleotidyl transferase mediated nick end labeling (TUNEL). Because normal or proliferating cells have almost no DNA breaks, there is no 3'-oh formation and they can rarely be stained. TUNEL method can stain intact single apoptotic nuclei or apoptotic bodies in situ, can accurately reflect the typical biochemical and morphological characteristics of apoptosis, and can detect a very small number of apoptotic cells, so it is widely used in the study of apoptosis. This kit has a wide range of applications and can be used to detect apoptosis in frozen or paraffin sections, as well as cultured adherent cells or suspended cells. It can selectively detect apoptotic cells, but not necrotic cells or cells with DNA strand breaks caused by irradiation and drug treatment. This kit detects cell apoptosis with a short time-consuming, one-step staining reaction and can be detected after washing. Component： Instruction： Experimental materials (self provided)PBS buffer (1 x, pH~7.4). 0.2% Triton X -100 (PBS formulation). 0.1% Triton X -100 (PBS formulation, containing 5 mg/mLBSA)4% paraformaldehyde (prepared with PBS)Immunohistochemical penDewaxing solvent (paraffin section sample)Related reagents for paraffin section processingAnti fluorescence quenching and sealing agent. ddH2Oexperimental design. A. Positive control:Prepare positive control slides using DNaseI treatment. DNaseI can digest single or double stranded DNA and expose the 3 '- OH end, artificially causing cell apoptosis. One experiment per time is sufficient. (To verify if there are any issues with the experimental operation and reagent kit)B. Negative control:Use TUNEL Reaction Buffer without TdT Enzyme and replace TdT Enzyme with ddH2O. (Mainly to exclude non-specific staining caused by cell apoptosis, operational processes, and other reasons; and to adjust the exposure intensity of the shooting.)C. Experimental processing group.The experimental group operated normally according to the instructions.D. Experimental control group.The experimental group operated normally according to the instructions.Experimental steps1. Sample preparation:(1) For adherent cells or cell smearsa. Clean once with PBS.Note: If you are concerned that the cells on the cell smear may not adhere firmly, you can dry the sample to make the cells adhere more firmly.b. Fixation: Add an appropriate amount of 4% paraformaldehyde (prepared with PBS) and fix at 4 ℃ for 30 minutes. Clean twice with PBS.c. Translucency: Add an appropriate amount of 0.2% Triton X -100 (prepared with PBS) and let it penetrate at room temperature for 20 minutes. Clean twice with PBS.d. Step 2: TUNEL reaction.(2) For suspended cells or cell suspensionsa. Collect cells (3-5 x 106 cells), centrifuge at 1000 rpm for 5 minutes, and wash twice with PBS.b. Fixation: Add an appropriate amount of 4% paraformaldehyde (prepared with PBS) and resuspend the cells thoroughly. Fix at 4 ℃ for 30 minutes. Centrifuge at 2000 rpm for 5 minutes and clean twice with PBS.c. Translucency: Add an appropriate amount of 0.2% Triton X -100 (prepared with PBS) and let it penetrate at room temperature for 20 minutes. Centrifuge at 2000 rpm for 5 minutes and clean twice with PBS.d. Step 2: TUNEL reaction.(3) Paraffin tissue sectioninga. Dewaxing and hydration: Place the sliced samples sequentially in xylene I (10 min) → xylene II (10 min) → 100% ethanol I (5 min) → 100% ethanol II (5 min) → 95% ethanol (5 min) → 90% ethanol (5 min) → 80% ethanol (5 min) → 70% ethanol (5 min) → ddH2O rinse for 5 min, rinse twice.Note: Xylene is toxic and volatile. Please perform this operation in a fume hood.b. Use filter paper to dry the liquid around the sliced sample, and circle the sample contour with an immunohistochemical pen for downstream transparency and labeling.Note: If it is found that the contour circle of immunohistochemistry strokes is damaged in subsequent experimental operations, it needs to be redrawn in a timely manner.c. Transparency: Dilute 2 mg/mL of ProteinaseK solution with PBS in a ratio of 1:100 to a final concentration of 20 µ g/mL. Add 100 µ L dropwise to each sample to cover all sample areas. Incubate at 20-37 ℃ for 20 minutes.Note: Protein K can penetrate the cell membrane and nuclear membrane, allowing subsequent staining reagents to fully enter the nucleus for reaction and improve labeling efficiency. An excessively long incubation time increases the risk of tissue slices falling off the carrier film during subsequent washing steps, while a too short incubation time may result in insufficient permeability treatment and affect labeling efficiency. To obtain better results, the concentration, incubation time, and temperature of Protein K need to be optimized according to different types of tissue samples.d. Wash the slices twice with PBS, each time for 5 minutes. Use filter paper to remove excess liquid, and place the processed sample in a wet box to keep it moist.Note: Protein K must be washed thoroughly in this step, otherwise it will seriously interfere with subsequent labeling reactions.e. Step 2: TUNEL reaction.(4) Frozen tissue sectionsa. Fixation: Take out frozen sections and warm them back to room temperature. Add an appropriate amount of 4% paraformaldehyde (prepared with PBS) and fix at room temperature for 30 minutes. Wash twice with PBS for 10 minutes each time.Note: If you are concerned that formaldehyde cleaning may not be clean enough, it may affect the final dyeing effect. After formaldehyde fixation is completed, an appropriate amount of 2 mg/mL glycine can be added and washed for 10 minutes to neutralize the residual fixing solution, and then PBS cleaning can be carried out.b. Use filter paper to dry the liquid around the sliced sample, and circle the sample contour with an immunohistochemical pen for downstream transparency and labeling.Note: If it is found that the contour circle of immunohistochemistry strokes is damaged in subsequent experimental operations, it needs to be redrawn in a timely manner.c. Transparency: Dilute 2 mg/mL of ProteinaseK solution with PBS in a ratio of 1:100 to a final concentration of 20 µ g/mL. Add 100 µ L dropwise to each sample to cover all sample areas. Incubate at 20-37 ℃ for 20 minutes.Note: Protein K can penetrate the cell membrane and nuclear membrane, allowing subsequent staining reagents to fully enter the nucleus for reaction and improve labeling efficiency. An excessively long incubation time increases the risk of tissue slices falling off the carrier film during subsequent washing steps, while a too short incubation time may result in insufficient permeability treatment and affect labeling efficiency. To obtain better results, the concentration, incubation time, and temperature of Protein K need to be optimized according to different types of tissue samples.d. Wash the slices twice with PBS, each time for 5 minutes. Use filter paper to remove excess liquid, and place the processed sample in a wet box to keep it moist.Note: Protein K must be washed thoroughly in this step, otherwise it will seriously interfere with subsequent labeling reactions.e. Step 2: TUNEL reaction.(5) Positive treatment (only the positive control is subjected to this step, and other samples are directly subjected to the TUNEL reaction step)a. Dilute 10 x DNase I Buffer with ddH2O in a ratio of 1:10 to 1 x DNase I Buffer for later use.b. Drip 100 µ L of 1xDNase I Buffer onto the processed sample, covering all sample areas, and equilibrate at room temperature for 5 minutes.c. Dilute DNase I (2 U) with 1 x DNase I Buffer at a ratio of 1:100/ µ L) A working solution with a final concentration of 20 U/mL.d. Discard the buffer and add 100 µ Incubate DNase I working solution with a concentration of 20 U/mL at room temperature for 10 minutes.e. Discard DNase I working solution and clean twice with PBS.f. Step 2: TUNEL reaction.2. TUNEL reaction(1) Prepare TUNEL reaction solution (ready to use): / 1 sample 5 sample 10 sample TdT enzyme 1 µL 5 µL 10 µL YF®488/555/594/640 TUNEL Reaction Buffer 49 µL 245 µL 490 µL TUNEL Total volume of reaction solution 50 µL 250 µL 500 µL (2) For adherent cells, cell smears, or tissue sectionsa. Add 50 to each sample µ L TUNEL reaction solution, evenly cover the sample with the reaction solution. The appropriate time for dark incubation at 37 ℃ (recommended staining time for cells is 30 minutes to 1 hour, and tissue staining time is 2 hours).Note: 50 µ L TUNEL reaction solution is suitable for smear, slicing, or 96 well plates (other different well plates can adjust the volume of TUNEL reaction solution appropriately to cover cells). If the sample to be tested is a smear, slice, or in a 24 well plate, 12 well plate, or 6 well plate, anti evaporation film can be used, or self sealing bags or other appropriate materials can be used to cut circular plastic sheets slightly smaller than the holes. After adding TUNEL reaction solution dropwise, cover the sample to prevent the evaporation of TUNEL reaction solution and make the TUNEL reaction solution evenly cover the sample.b. Discard the TUNEL reaction solution, wash twice with PBS, and then wash three times with 0.1% Triton X -100 (PBS preparation, containing 5 mg/mL BSA) for 5 minutes each time. This way, free unreacted markers can be removed cleanly.c. (Optional) Add an appropriate concentration of 5 to each sample µ DAPI staining solution with a concentration of g/mL, incubated at room temperature in dark for 5 minutes. After staining, discard DAPI staining solution and wash twice with PBS for 5 minutes each time.d. (Optional) Slice sealing: Add 50 drops to each sample µ L anti fluorescence quenching sealing agent (anti fluorescence quenching sealing agent may not be suitable for certain dyes, it is recommended to conduct pre experimental testing for compatibility before the experiment), cover the cover glass, gently tap the cover glass with the blunt end of tweezers to remove bubbles and ensure complete sealing.e. Use filter paper to remove excess liquid and add 100 to the sample area µ Keep the sample moist with PBS and immediately observe under a fluorescence microscope.(3) For suspended cells or cell suspensionsa. Add 50 to each sample tube µ Gently resuspend cells in LTUNEL reaction solution and incubate at 37 ℃ in the dark for 30-1 hour. Gently resuspend cells with a micropipette every 15 minutes.b. Centrifuge at 2000 rpm for 5 minutes, discard TUNEL reaction solution, and wash twice with 0.1% Triton X -100 (PBS preparation, containing 5 mg/mLBSA) for 5 minutes each time. This way, free unreacted markers can be removed cleanly.c. Add 100 to each sample tube µ L concentration is 5 µ DAPI staining solution with a concentration of g/mL, incubated at room temperature in dark for 5 minutes.d. Join 400 µ L PBS resuspended cells and immediately detected with a flow cytometer or observed under a fluorescence microscope after smearing.Matters needing attention：1. please centrifuge the product to the bottom of the tube immediately before use, and then conduct subsequent experiments. 2. when the staining background is heavy or non-specific staining is obvious, the staining time can be appropriately reduced. 3. it is recommended to add negative control and positive control groups during the experiment. 4. please wear mask and gloves when using component A. if it contacts the skin, please wash it with plenty of water immediately. 5. fluorescent dyes have quenching problems. Please try to avoid light to slow down fluorescence quenching. 6. for your safety and health, please wear experimental clothes and disposable gloves. Product parameters：590/617nm； Scope of application：Late apoptosis detection, TUNEL Kit... Read More | Product Characteristics Effect Diluents, Animal-free are effective buffers free of any animal components. They can be used for the dilution of serum, plasma, blood, stool or urine samples, as well as the dilution of primary and secondary antibodies. Effect Diluents, Animal-free efficiently minimize Product Characteristics Effect Diluents, Animal-free are effective buffers free of any animal components. They can be used for the dilution of serum, plasma, blood, stool or urine samples, as well as the dilution of primary and secondary antibodies. Effect Diluents, Animal-free efficiently minimize matrix effects, cross-reactions and unspecific binding in immunoassays like ELISA, Western blotting, Immunohistochemistry, protein arrays and immuno-PCR.The Effect Diluents, Animal-free are used alternatively to the standard sample or antibody dilution buffers: In ELISA for the dilution of specimen and detection antibodies. In Western Blotting for the dilution of primary and secondary antibodies. In Protein arrays for the dilution of specimen and detection antibodies. In immuno-PCR as a washing buffer.Three versions of the diluent are offered: Low, Medium and High for optimal discrimination between specific and unspecific reaction and for minimizing strong interference effects e.g., by RF (rheumatoid factors), HAMAs (human-a-mouse Abs) or by endogenous components that bind and mask the analyte.Composition & Properties The Effect Diluents, Animal free contain no animal components and are free of phosphates.Working Procedure 1.Mix thoroughly prior to use. 2.Dilution recommendations a.Dilute antibodies according to the instruction of the antibody b.Dilution of the specimen is recommended at 1:2 or higherTips & TricksEffect Diluents must not be considered as blocking buffers. Recommended blocking buffers are: Synthetic Blocking Buffer, ELISA (cat. no. S494401), Synthetic Blocking Buffer, Blotting (cat. no. S494457) and WellChampion (cat. no. W494467) for plate blocking and stabilization (preparation of pre-coated plates). Complex sample matrices, such as serum and plasma, may contain interfering factors that affect the ability of the assay to accurately quantify the target analyte. Strong interferences are often caused by RFs and HAMAs. This matrix effect can cause high background in the negative control or false negatives in the sample measurement. To reduce this effect the samples can be diluted in the Effect Diluents, Animalfree.Handling & Storage Store solution 2-8°C or -15 to -30°C (tolerates freezing and thawing cycles)... Read More | G665573 Component 10 T Storage G665573A Buffer P1 30 mL RT G665573B Buffer P2 30 mL RT G665573C Buffer E3 30 mL RT G665573D Buffer PS 15 mL RT G665573E Buffer PW (concentrate) 10 mL RT G665573F Endo-Free Buffer EB 30 mL RT G665573G RNase A (10 mg/mL) 600 碌L RT G665573H Endo-Remover FX 10 EA G665573 Component 10 T Storage G665573A Buffer P1 30 mL RT G665573B Buffer P2 30 mL RT G665573C Buffer E3 30 mL RT G665573D Buffer PS 15 mL RT G665573E Buffer PW (concentrate) 10 mL RT G665573F Endo-Free Buffer EB 30 mL RT G665573G RNase A (10 mg/mL) 600 碌L RT G665573H Endo-Remover FX 10 EA RT G665573I Plungers 10 EA RT G665573J Spin Columns DX with Collection Tubes 10 EA RT G665573K Centrifuge Tubes (15 mL) 10 EA RTProduct IntroductionThis kit is specially designed for the efficient and rapid extraction of plasmids from 15-50 ml of bacterial fluids. On the basis of cell lysis by alkaline lysis method, it adopts unique silicon matrix membrane adsorption technology to bind plasmid DNA efficiently and exclusively, and each adsorption column can adsorb up to 250 µg of plasmid DNA; at the same time, it adopts a special buffer system and endotoxin removal filter to effectively remove endotoxin, genomic DNA, RNA, protein and other impurities. The plasmids obtained from this kit are of high purity and stable quality, and can be used for cell transfection, as well as DNA sequencing, PCR, in vitro transcription, endonuclease digestion and other experiments.Self-contained reagents: anhydrous ethanol, isopropanol.Pre-experiment Preparation and Important Notes1. All components are stable for 1 year in a dry, room temperature (15-30°C) environment, and longer by placing the adsorption columns at 2-8°C. Buffer P1 with RNase A is stable for 6 months at 2-8°C.2. Before the first use, add all of the RNase A solution to Buffer P1, mix well, and store at 2-8°C. Before use, it needs to be left at room temperature for a period of time, return to room temperature and then use.3. Anhydrous ethanol should be added to Buffer PW before the first use according to the instructions on the reagent bottle label.4. Please check Buffer P2 and Buffer E3 for crystallization or precipitation before use. If there is any crystallization or precipitation, the clarification can be restored by taking a water bath at 37℃ for a few minutes.5. Be careful not to touch Buffer P2 and Buffer E3 directly, and tighten the lid immediately after use.6. The amount and purity of extracted plasmid is related to the concentration of bacterial culture, strain type, plasmid size, plasmid copy number and other factors.7. The adsorption columns treated with Buffer PS should be used immediately to avoid leaving them for too long.Operation steps1.Take 15-50 ml of fresh bacterial solution from the overnight culture, add it to a centrifuge tube (self-prepared) and centrifuge at 5000 × g for 10 minutes to collect the bacteria, and aspirate all the supernatant as much as possible.2.Add 2.5 ml of Buffer P1 to the centrifuge tube in which the bacterial precipitate has been left (please check that RNase A has been added first) and suspend the bacterial precipitate by mixing thoroughly using a pipette or vortex shaker. Note: If the bacterial mass is not thoroughly mixed, it will affect the lysis effect and make the extraction amount and purity low.3.Add 2.5 ml of Buffer P2 to the centrifuge tube, mix gently up and down 8-10 times to fully lyse the organisms, and leave at room temperature for 3-5 minutes. At this point the solution should become clear and viscous. Note: Mix gently, do not shake vigorously, so as not to interrupt the genomic DNA and cause genomic DNA fragments to be mixed in the extracted plasmid. If the solution does not become clear, it suggests that the amount of bacteria may be too large and the lysis is not complete, and the amount of bacteria should be reduced.4.Add 2.5 ml of Buffer E3 to the centrifuge tube and mix immediately by turning up and down 8-10 times, at which time a white flocculent precipitate appears. Note: Buffer E3 should be mixed immediately after addition to avoid localized precipitation.5.Install the cap of the filter (Endo-Remover FX), transfer the solution obtained in step 4 to the filter, wait until the white flocculent precipitate floats on the upper layer of the solution, remove the cap of the filter, align the filter with a clean 15 ml centrifuge tube (supplied), and slowly push the handle (Plungers) to filter, so that as much as possible of the solution passes through, and the filtrate is collected in the centrifuge tube.6.Add 1/3 solution volume of isopropanol to the filtrate and mix upside down.7.Column Equilibrium: Add 1ml Buffer PS to the adsorption column (Spin Columns DX) that has been loaded into a 15ml centrifuge tube, centrifuge for 2 minutes at 2500 x g. Pour off the waste liquid from the centrifuge tube and put the adsorption column back into the centrifuge tube.8.The mixture of filtrate and isopropanol from step 6 was transferred to the equilibrated adsorption column (which had been loaded into a collection tube).9.Centrifuge at 2500 x g for 1 minute, pour off the waste solution in the collection tube and put the adsorption column back into the collection tube. Note: The maximum volume of the adsorption column is 4 ml, so the solution obtained in step 8 is passed through the column in 2 times.10.Add 2 ml of Buffer PW to the adsorption column (please check that anhydrous ethanol has been added first), centrifuge at 2500 × g for 1 min, and pour off the waste liquid in the collection tube.11.Repeat step 10.12.The adsorbent column was put back into the collection tube and centrifuged at 2500 × g for 2 min, the waste liquid was poured off, and the column was left to dry at room temperature for 5 min.Note: The purpose of this step is to remove residual ethanol from the adsorption column, which can interfere with subsequent enzymatic reactions (digestion, PCR, etc.)13. Place the adsorption column in a new 15 ml centrifuge tube, add 0.5-1 ml Endo-Free Buffer EB to the middle of the adsorbent membrane, leave it at room temperature for 2-5 minutes, centrifuge it at 2500 × g for 2 minutes, and collect the plasmid solution into the centrifuge tube. -20°C to store the plasmid.Note: 1) In order to increase the recovery efficiency of the plasmid, the obtained solution can be reintroduced into the adsorption column, left at room temperature for 2-5 minutes, centrifuged at 2500 x g for 2 minutes, and the plasmid solution can be collected into a centrifuge tube.2) When the plasmid copy number is low or >10kb, Endo-Free Buffer EB can increase the extraction efficiency by preheating at 65-70°C in a water bath... Read More | 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 |