| Description | Glucokinase (GK, EC 2.7.1.2) is a member of the hexokinase family, primarily found in mature hepatocytes and pancreatic islet cells. Under normal physiological conditions, the main role of GK is to monitor blood glucose levels. Glucokinase (GK) phosphorylates glucose to produce glucose-6-phosphate. Glucokinase (GK, EC 2.7.1.2) is a member of the hexokinase family, primarily found in mature hepatocytes and pancreatic islet cells. Under normal physiological conditions, the main role of GK is to monitor blood glucose levels. Glucokinase (GK) phosphorylates glucose to produce glucose-6-phosphate. This product is further coupled with glucose-6-phosphate dehydrogenase and NADP+, and the increase in NADPH absorbance is measured at 340 nm, thereby calculating the enzyme activity.Component50TStorageExtraction Buffer60 mL2-8℃Reagent 140 mL2-8℃Reagent 21EA-20℃Reagent 31EA2-8℃Reagent PreparationReagent 2 (Powder, 1 vial):Before opening, ensure the powder is at the bottom of the vial (tap manually if needed).Add 2.2 mL of distilled water to dissolve.The storage period is the same as the kit's expiry date.Reagent 3 (Powder, 1 vial):Before opening, ensure the powder is at the bottom of the vial (tap manually if needed).Add 36 mL of Reagent 1 to dissolve.The storage period is the same as the kit's expiry date.User-Prepared Instruments & MaterialsMortar (homogenizer), ice bucket (ice maker), benchtop centrifuge, adjustable pipettes, water bath (oven, incubator, metal bath), 1 ml quartz cuvette, centrifuge tubes, UV spectrophotometer, distilled water (deionized water or ultrapure water is acceptable).Sample Extraction1. Tissue Samples: Weigh approximately 0.1 g of tissue, add 1 mL of Extraction Buffer, and homogenize on ice. Centrifuge at 12000 rpm, 4°C for 10 minutes. Collect the supernatant and keep it on ice for assay.Note: If increasing the sample amount, use a ratio of 1:5 to 1:10 (tissue weight (g) : Extraction Buffer volume (mL)) for extraction.2. Bacterial/Cell Samples: Collect bacteria or cells into a centrifuge tube by centrifugation and discard the supernatant. Take 5 million bacteria or cells, add 1 mL of Extraction Buffer, and disrupt using ultrasound on ice (power 20% or 200 W, ultrasonicate for 3 s, interval 10 s, repeat 30 times). Centrifuge at 12000 rpm, 4°C for 10 minutes. Collect the supernatant and keep it on ice for assay.Note: If increasing the sample amount, use a ratio of 500-1000 (x10⁴ cells) : 1 (mL Extraction Buffer) for extraction.3. Liquid Samples: Detect directly. If the sample is turbid, centrifuge and use the supernatant for detection.Assay Procedure1. Preheat the UV spectrophotometer for at least 30 minutes. Set the wavelength to 340 nm. Zero the instrument with distilled water.2. Pre-warm the prepared Reagent 2 and Reagent 3 at 25°C for 5 minutes to reach room temperature.3. In a 1 mL quartz cuvette (1 cm light path), add sequentially:Reagent (µL)Test CuvetteSample80Reagent 240Reagent 36804. Mix well. Read the absorbance at 340 nm at 1 minute (A1) and then again at 21 minutes (i.e., after 20 minutes) (A2). Calculate ΔA = A2 - A1.Notes:1. If ΔA is close to zero, the reaction time can be appropriately extended to 30 minutes or longer before reading A2. The modified reaction time (T) must be substituted into the calculation formula. Alternatively, increase the sample volume appropriately. The modified sample volume (V1) must be substituted into the calculation formula.2. If the increasing trend is unstable, read the absorbance every 10 seconds and select a linear increasing period for calculation. The corresponding ΔA value should be substituted into the calculation formula.GK Activity Calculation1. Based on Sample Protein Concentration:Unit Definition: One unit of enzyme activity is defined as the generation of 1 nmol NADPH per minute per mg of protein.Formula:GK (nmol/min/mg prot) = [ΔA ÷ (ε × d) × V2 × 10⁹] ÷ (V1 × Cpr) ÷ T = 80.4 × ΔA ÷ Cpr2. Based on Sample Fresh Weight:Unit Definition: One unit of enzyme activity is defined as the generation of 1 nmol NADPH per minute per gram of fresh tissue.Formula:GK (nmol/min/g fresh weight) = [ΔA ÷ (ε × d) × V2 × 10⁹] ÷ (W × V1 ÷ V) ÷ T = 80.4 × ΔA ÷ W3. Based on Bacterial/Cell Density:Unit Definition: One unit of enzyme activity is defined as the generation of 1 nmol NADPH per minute per 10⁴ bacteria/cells.Formula:GK (nmol/min/10⁴ cell) = [ΔA ÷ (ε × d) × V2 × 10⁹] ÷ (500 × V1 ÷ V) ÷ T = 0.16 × ΔA4. Based on Liquid Volume:Unit Definition: One unit of enzyme activity is defined as the generation of 1 nmol NADPH per minute per mL of liquid.Formula:GK (nmol/min/mL) = [ΔA × V2 ÷ (ε × d) × 10⁹] ÷ V1 ÷ T = 80.4 × ΔAParameter Description:ε: NADPH molar extinction coefficient, 6.22 × 10³ L/mol/cmd: Light path of the 1 mL quartz cuvette, 1 cmV: Volume of Extraction Buffer added, 1 mLV1: Volume of sample supernatant added, 0.08 mLV2: Total reaction volume, 0.8 mL = 8 × 10⁻⁴ LT: Reaction time, 20 minW: Sample mass, g500: Bacteria or cell number, in units of 10⁴Cpr: Protein concentration of the supernatant, mg/mL; Aladdin BCA Protein Quantification Kit (B665595) or Ready-to-Use BCA Protein Quantification Kit (R1491648) are recommended.PrecautionsIt is recommended to first select 1-3 samples with significant differences (e.g., different types or groups) for preliminary experiments to familiarize yourself with the procedure. Determine or adjust the sample concentration based on the preliminary results to prevent unnecessary waste of samples or reagents... Read More | Products B669892Component50 TStorageB669892ABuffer RCL3×260 mL2-8℃B669892BBuffer GR25 mLRTB669892CBuffer GL25 mLRTB669892DBuffer GW1 (concentrate)13 mLRTB669892EBuffer GW2 (concentrate)15 mLRTB669892FBuffer GE15 mLRTB669892GProteinase K50 mgRTB669892HProteinase K Storage Buffer5 Products B669892Component50 TStorageB669892ABuffer RCL3×260 mL2-8℃B669892BBuffer GR25 mLRTB669892CBuffer GL25 mLRTB669892DBuffer GW1 (concentrate)13 mLRTB669892EBuffer GW2 (concentrate)15 mLRTB669892FBuffer GE15 mLRTB669892GProteinase K50 mgRTB669892HProteinase K Storage Buffer5 mLRTB669892ISpin Columns DL with Collection Tubes50 setsRTProductsThis kit is suitable for the extraction of total DNA, including genomic DNA, mitochondrial DNA and viral DNA, from fresh or frozen whole blood (blood samplestreated with anticoagulants such as citrate, EDTA or heparin), plasma, serum, haematocrit brown and yellow layers, bone marrow, cell-free body fluids, etc. Theproduct can process 1-5 ml of whole blood, and can be purified to obtain sizes rangingfrom 100bp to 50kb. The purified DNA is of high yield and good quality, with maximumremoval of proteins, pigments, lipids and other inhibitory impurities, and can bedirectly used in PCR, fluorescence quantitative PCR, enzyme digestion and SouthernBlot.Self-contained reagent: anhydrous ethanol.Pre-experiment Preparation and Important Notes1. Add 5ml Proteinase K Storage Buffer to Proteinase K to dissolve it, and storeit at -20℃. Do not leave the prepared Proteinase K at room temperature for a longtime, and avoid repeated freezing and thawing to avoid affecting its activity.2. Repeated freezing and thawing of the sample should be avoided, as this may resultin smaller DNA fragments and a decrease in the amount of extracted DNA. 3.This kit can extract up to 1-5 ml of whole blood samples, if you need to extracta large number of blood samples, please use the blood genome non-column extractionkit. 4. Anhydrous ethanol should be added to Buffer GW1 and Buffer GW2 according to theinstructions on the label of the reagent bottle before first use.5. Please check Buffer GL for crystallization or precipitation before use, if thereis any crystallization or precipitation, please put it in 56℃water bath to re-dissolve.6. If the downstream experiments are sensitive to RNA contamination, 4µl of DNaseFree RNase A (100mg/ml) can be added, RNase A is not provided in the kit, and canbe ordered separately from our company if needed.7. The Buffer RCL in the kit cannot be used further after turbidity.procedure1. Add 1-5 ml of blood sample to a centrifuge tube (supplied) and add 3 times thevolume of Buffer RCL and gently vortex or invert to mix.2. Centrifuge at 3000 rpm (~900 x g) for 10 minutes and carefully aspirate thesupernatant.3. Add 400 µl Buffer GR to the precipitate and resuspend the precipitate. Note: If the downstream assay is sensitive to RNA, add 4 µl of RNase A (100 mg/ml)solution, shake for 15 seconds, and leave at room temperature for 5 minutes.4. For 1-2 ml blood sample extraction, add 40µl Proteinase K to the above solutionand mix well; for 2-5 ml blood sample extraction, add 100µl Proteinase K to theabove solution and mix well.5. Add 400 µl of Buffer GL, mix upside down 15 times, and vigorously vortex andshake for at least 1 minute. Note: Do not add Proteinase K directly to Buffer GL.6. Incubate at 70°C for 10 minutes, during which time mixing was inverted severaltimes.Note: 1) If the solution is not completely clear, add appropriate amount of Proteinase K and incubate. Extend the incubation time until the solution is completely clear. 2) The yield of DNA has been maximized by 10 minutes of incubation, and continuedprolongation of the incubation time has no effect on DNA yield or purity.7. Add 400 µl of anhydrous ethanol and mix upside down 10 times. Centrifuge brieflyto concentrate the liquid on the walls and cap to the bottom of the tube.8. Add all of the solution obtained in the previous step to the Spin Columns DL inthe collection tube. If the solution cannot be added all at once, transfer it severaltimes. centrifuge at 12,000 rpm (~13,400 x g) for 1 minute, pour off the waste liquidfrom the collection tube, and put the column back into the collection tube.9. Add 500 µl of Buffer GW1 to the adsorption column (check that anhydrous ethanolis added before use), centrifuge at 12,000 rpm for 1 minute, pour off the waste liquidin the collection tube, and put the adsorption column back into the collection tube.Note: It is recommended that step 9 be repeated if the sample being extracted isthe blood genome of a species such as mice or monkeys from which hemoglobin isdifficult to remove.10. Add 500 µl Buffer GW2 to the adsorption column (check that anhydrous ethanolis added before use), centrifuge at 12,000 rpm for 1 minute, pour off the waste liquidin the collection tube, and put the adsorption column back into the collection tube.Note: Step 10 can be repeated if further DNA purity is required.11. Centrifuge at 12,000 rpm for 2 minutes and pour off the waste liquid in thecollection tube. Leave the adsorption column at room temperature for several minutesto dry thoroughly. Note: The purpose of this step is to remove residual ethanol from the adsorptioncolumn, which can interfere with subsequent enzymatic reactions (digestion, PCR,etc.)12. Place the adsorption column in a new centrifuge tube, add 50-200 µl of BufferGE or sterilized water to the middle of the adsorption column overhanging the column,leave it at room temperature for 2-5 minutes, centrifuge at 12,000 rpm for 1 minute,collect the DNA solution, and store the DNA at -20℃.Note: 1) If the downstream experiment is sensitive to pH or EDTA, you can use sterilized water for elution. The pH of the eluent has a great influence on theelution efficiency, if water is used as the eluent should ensure that its pH is7.0-8.5 (you can use NaOH to adjust the pH of the water to this range), and the elutionefficiency is not high when the pH is lower than 7.0.2) Incubation at room temperature for 5 minutes prior to centrifugation increasesyield.3) Re-elution with an additional 50-200 µl Buffer GE or sterilized water can increase the yield.4) If the final concentration of DNA is to be increased, the DNA eluate obtainedin step 12 can be re-spiked onto the adsorbent membrane and centrifuged at 12,000rpm. 1min; if the elution volume is less than 200µl, the final concentration of DNA canbe increased, but the total yield may be reduced. If the amount of DNA is less than1 µg, elution with 50 µl Buffer GE or sterilized water is recommended.5) Because DNA preserved in water is subject to acidic hydrolysis, for long-termstorage, it is recommended that it be eluted with Buffer GE and stored at -20℃... Read More | Product content:M665754Component25 TStorageM665754ATris-HCl, 1 mM, PH 8.01 mL-20℃. Avoid freeze/thaw cycleM665754BE. coli Poly(A) Polymerase, 5 U/µL15 µL-20℃. Avoid freeze/thaw cycleM665754C10×Poly(A) Polymerase Buffer80 µL-20℃. Avoid freeze/thaw Product content:M665754Component25 TStorageM665754ATris-HCl, 1 mM, PH 8.01 mL-20℃. Avoid freeze/thaw cycleM665754BE. coli Poly(A) Polymerase, 5 U/µL15 µL-20℃. Avoid freeze/thaw cycleM665754C10×Poly(A) Polymerase Buffer80 µL-20℃. Avoid freeze/thaw cycleM665754DATP, 10 mM15 µL-20℃. Avoid freeze/thaw cycleM665754ERT Primer, 25 µM90 µL-20℃. Avoid freeze/thaw cycleM665754F5×SuperRT Buffer120 µL-20℃. Avoid freeze/thaw cycleM665754GUltraPure dNTP Mix, 10 mM each30 µL-20℃. Avoid freeze/thaw cycleM665754HSuperRT, 200 U/µL15 µL-20℃. Avoid freeze/thaw cycleM665754IRNase-Free Water1 mL-20℃. Avoid freeze/thaw cycle Product Introduction:This kit uses the method of adding a poly (A) tail at the 3 'end of miRNA to give miRNA a Poly (A) tail, followed by reverse transcription using Oligo (dT) - Universal tag universal reverse transcription primers to synthesize the first stranded cDNA corresponding to miRNA. The miRNA cDNA first strand synthesis kit contains all the reagents required for the miRNA 3 'end Poly (A) tail modification process and the reverse transcription process after modification. This kit has a very high Poly (A) modification and reverse transcription efficiency, which can range from 1 ng-2 µ The first strand of cDNA corresponding to miRNA was effectively obtained from the total RNA of g. And the operation is simple and fast, which can be used to simultaneously detect multiple miRNAs from a synthesized cDNA reaction. This not only reduces errors and saves samples, but also achieves high-throughput detection.Note: This kit must be used in conjunction with the miRNA fluorescence quantitative detection kit.Self prepared experimental materials: 1 ng-2 µ Total RNA of g, or 0.1 ng-1 µ Small molecule RNA of g.Notes:To prevent RNase pollution, attention should be paid to the following aspects:1. Use plastic products and gun heads without RNase to avoid cross contamination.2. Glassware should be dry baked at a high temperature of 180 ℃ for 4 hours before use. Plastic containers can be soaked in 0.5 M NaOH for 10 minutes, thoroughly rinsed with water, and then sterilized under high pressure.3. The solution should be prepared using water without RNase.4. Operators should wear disposable masks and gloves, and change gloves frequently during the experiment.Usage:A. The process of miRNA adding Poly (A) tail:1.based on the amount of RNA used, dilute the total RNA of 10 mM ATP with 1 mM Tris (pH 8.0) according to the following formula: ATP dilution coefficient=5000/__ ngExample: If the initial amount of total RNA is 100 ng, then the ATP dilution coefficient is 5000/100=50. About to dilute ATP 50 times (1 µ 10 mM ATP plus 49 for l µ 1 mM Tris at pH 8.0.2. Add the following reagents to the pre cooled RNase free reaction tube in the ice bath to a total volume of 25 µ L. reagent 25 µlReaction system final concentration total RNA* X µl Up to 2 µg 10×Poly(A) Polymerase Buffer 2.5 µl 1× Diluted ATP in step "1" 1 µl / E. coli Poly(A) Polymerase, 5U/µl 0.5 µl 2.5 U RNase-Free Water up to 25 µl /*The total RNA used in the reaction must contain small molecule RNA.This process can also directly use small molecule RNA (recommended dosage of 2-5) µ L. Please determine the amount added based on the abundance of the target miRNA.3. Gently mix the above reaction solution and briefly centrifuge to collect the liquid at the bottom of the tube. Incubate at 37 ℃ for 15 minutes. After this process is completed, immediately proceed with the synthesis of the first strand cDNA or temporarily store it at -20 ℃. If long-term storage is required, it is recommended to store at -80 ℃.B. The process of synthesizing the first strand of modified miRNA cDNA:1. Add the reagents in the table below to the pre cooled RNase free reaction tube in the ice bath until the final volume reaches 20µl: reagent 20 µlReaction system The above Poly (A) reaction solution 4 µl UltraPure dNTP Mix ，10 mM each 1 µl RT Primer ，25 µM 3 µl 5×SuperRT Buffer 4 µl SuperRT ，200 U/µl 0.5 µl RNase-Free Water 7.5 µl2. Gently mix the above reaction solution and briefly centrifuge to collect the liquid at the bottom of the tube. Incubate at 42 ℃ for 50 minutes.3.85 ℃ for 5 minutes and terminate the reaction. The synthesized cDNA reaction solution can be directly used for fluorescence quantitative detection experiments or stored at -20 ℃ for future use... Read More | Products contentN669983Component240 TStorageN669983AIndex N501 Primers for Illumina240 µL-20℃. Avoid freeze/thaw cycle.N669983BIndex N973-N996 Primers for Illumina24×10 µL-20℃. Avoid freeze/thaw cycle. Products IntroductionThis kit is a companion kit to the transposase-Products contentN669983Component240 TStorageN669983AIndex N501 Primers for Illumina240 µL-20℃. Avoid freeze/thaw cycle.N669983BIndex N973-N996 Primers for Illumina24×10 µL-20℃. Avoid freeze/thaw cycle. Products IntroductionThis kit is a companion kit to the transposase-based Rapid DNA Library Construction Kit for Illumina platform library construction. Each kit contains one N5 primer and 24 N7 primers, which can be used to prepare 24 different single-ended Index libraries. All reagents provided in the kits have been subjected to stringent quality control and functional validation to maximize the stability and reproducibility of library construction. The libraries can be used for sequencing on Illumina platforms such as HiSeq X-10/4000/2500/2000 and MiSeq. Provide your own instruments, reagents and consumables1. Magnetic frame: DynaMagTM-2 is recommended.2. DNA purification and recovery kit: It is recommended to use DNA purification and recovery kit by magnetic bead method.3. DNA building kit: It is recommended to use the Century transposase method second-generation sequencing rapid DNA building kit.4. Anhydrous ethanol.5. Reaction tubes: It is recommended to use low adsorption PCR tubes with 1.5 ml centrifuge tubes;Tip: It is recommended to use a high quality filter tip to prevent contamination of kits and library samples. Pre-experiment Preparation and Important NotesPlease centrifuge briefly before opening the cap so that the liquid collects at the bottom of the tube to avoid cross-contamination between different primers. ProcedureFor the use of the CombiVision Second Generation Sequencing Multisample Primer Kit, please follow the CombiVision Second Generation Sequencing Rapid DNA Library Kit protocol.Index N501 Primer for IlluminaIndex N901-N996 Primer for Illumina... Read More | Component Description T665563Component50 TStorageApplicationT665563AVNTR3820 1 mL-20℃. Avoid freeze/thaw cycle.High resolution 3-lite VNTR detectionT665563BVNTR41201 mL-20℃. Avoid freeze/thaw cycle.High resolution 3-lite VNTR detectionT665563CVNTR32321 mL-20℃. Avoid freeze/thaw Component Description T665563Component50 TStorageApplicationT665563AVNTR3820 1 mL-20℃. Avoid freeze/thaw cycle.High resolution 3-lite VNTR detectionT665563BVNTR41201 mL-20℃. Avoid freeze/thaw cycle.High resolution 3-lite VNTR detectionT665563CVNTR32321 mL-20℃. Avoid freeze/thaw cycle.High resolution 3-lite VNTR detectionT665563DMarkerⅠ300 µL-20℃. Avoid freeze/thaw cycle.DNA Molecular Weight Standard IT665563EMarkerⅡ250 µL-20℃. Avoid freeze/thaw cycle.DNA Molecular Weight Standard IIProduct IntroductionThis kit is a genotyping product for human Mycobacterium tuberculosis based on the latest research progress in molecular epidemiology1) and optimized by process. It utilizes variable-number tandem repeats (VNTR) polymorphisms in the Mycobacterium tuberculosis genome for genotyping to differentiate clinical strains, and is a powerful tool for studying the molecular epidemiology of Mycobacterium tuberculosis and monitoring the status of tuberculosis transmission. Compared with other existing Mycobacterium tuberculosis VNTR typing systems based on the VNTR principle, this typing system has a stronger ability to discriminate strains prevalent in China1,2,3), and is therefore particularly suitable for the needs of Chinese users.By carefully optimizing the primer sequences of each PCR reaction and the composition of the premixed reaction solution, this product has a strong anti-interference power. Compared with the user's own reagents, this product significantly improves the signal intensity of specific bands and reduces the appearance of non-specific bands when using crude templates (boiling bacterial solution), which makes the experimental operation easier and quicker, and at the same time, improves the success rate of the test. The premixed reaction solution is chemically stable and can effectively withstand repeated freezing and thawing (10 times) and a longer period of time (one week) at room temperature, which is better adapted to the user's need for flexibility in the detection work.This kit is a companion product to the TB Genotyping Kit VNTR-9. For samples identified as clustered or identical strains by the VNTR-9 kit, this product can be used for finer further typing identification if necessary. The three high-resolution detection sites VNTR3820, VNTR4120 and VNTR3232 in this product can be used in combination with the nine detection sites in the VNTR-9 to increase the resolution index (Hunter-Gaston index (HGI) to 0.9931).References1) Luo T et al. Development of a hierarchical variable-number tandem repeat typing scheme for Mycobacterium tuberculosis in China. PLoS One. 2014 Feb 25. 9(2)2)Sun G et al. Discriminatory potential of a novel set of Variable Number of Tandem Repeats for genotyping Mycobacterium marinum. Vet Microbiol. 2011 Aug Vet Microbiol. 2011 Aug 26;152(1-2)3) Zhang L et al. Highly polymorphic variable-number tandem repeats loci for differentiating Beijing genotype strains of Mycobacterium tuberculosis in Shanghai, China. FEMS Microbiol Lett. 2008 May;282(1):22-31.matters needing attention1.This product is a companion to the TB genotyping kit VNTR-9. The strains to be tested should be tested by VNTR-9 typing test first, and then use this product for testing. And the results of this product should be integrated and analyzed with the results of VNTR-9.2.To avoid contamination, it is recommended that the preparation of the organisms be done within a different location than the preparation of the PCR Mix and that different pipettes be used.3.Care should be taken at all stages of sample DNA collection, extraction and amplification to ensure proper labeling and to prevent cross-contamination between different samples.4.Commonly used reagents and consumables need to be autoclaved before experimentation.5.Each tube of PCR Mix contains different primers and cannot be mixed. It can be dispensed into different amounts at once according to the experimental needs to avoid repeated freezing and thawing.6.To avoid splashing the reaction solution when opening the reaction tube, centrifuge briefly before opening the cap and collect the liquid at the bottom of the tube. In case of accidental splashing on gloves or table, change gloves immediately and wipe the table with 75% alcohol or dilute acid.7.Be careful not to cross-contaminate the PCR Mix when aspirating, and it is recommended that the pipette tip be wiped with 75% alcohol 2 times before taking Mix each time.8.Pre-experiment preparation: 1×TE buffer (PH=8.0), 0.5×TBE buffer, agarose, ethidium bromide (EB), normal PCR instrument, DNA electrophoresis equipment and gel imager, 0.2 ml PCR reaction tubes, octuplex or 96-well PCR tubes, pipettes of different sizes: 0.5-10 µl and 20-200 µl.Operation steps1. DNA template preparation:1.1. scrape a small amount (1-2 inoculation loops) of sample from solid medium, resuspend in 100ul TE and inactivate at 80°C for 30 minutes.1.2. The inactivated strain was taken out of the P3 laboratory as follows:Boil at 100°C for 10 minutes (be careful to avoid bursting the cap of the EP tube during boiling to avoid letting water into the tube), place immediately on ice for 2 minutes, centrifuge at 12,000 rpm (~13,400 × g) for 10 minutes, take the supernatant and place in another sterile EP tube, label it, and store at -20°C.2. Testing procedures:2.1. Remove the TB Genotyping Kit HV-3, allow the liquid to equilibrate to room temperature, mix by shaking slightly 3-4 times, and then centrifuge at 12,000 rpm (~13,400 x g) for 5 seconds to allow the capped liquid to fall back into the tube.2.2.Three-locus VNTR typing: strains with identical results at 12 loci need to be further VNTR typed, i.e., the following four loci are added for comparison.1）PCR amplification: the reaction system was 20 µl. 19 µl of PCR Mix of VNTR3820, VNTR4120, and VNTR3232 were added to each PCR tube, 1 µl of DNA template was added, and mixed well.2）Amplification conditions:3) Gel preparation and electrophoresis:a: Notes:Important! Positive (H37Rv strain DNA) and negative controls (deionized water) need to be set up for each experiment.Key! This experiment is based on agarose gel electrophoresis to interpret the genotype of VNTR locus, therefore, in order to make the results accurate, it is necessary to follow the unified standard operation in this step of electrophoresis, and the following points should be noted:a-1: The comb used for glue making is 18 holes.a-2: The two wells on the left and right sides of the gel were discarded due to the tendency to distort the bands during electrophoresis, affecting the interpretation of the results, or a negative control was spotted in one of the wells. The remaining 16 wells were divided into 12 samples, 3 DNA Markers and 1 positive control. The order of spotting was "1, 2, M, 3, 4, 5, 6, M, 7, 8, 9, 10, M, 11, 12, H37Rv", the numbers represent samples, and M represents DNA Marker.a-3: When PCR amplification products are subjected to the first electrophoresis and Marker I is used, the gel concentration is 1%, the voltage is 150 V, and the time is 100-120 min.a-4: If the amplification product fragment is too large (>1000bp) and needs to be electrophoresed again and Marker II is used, the gel concentration is 0.8%, the voltage is 150V and the time is 150 minutes.b: Gluing as well as the electrophoresis process:PCR amplification products were electrophoresed using a 1% agarose gel.To prepare 1% agarose gel, 12×12 cm gel tray was used to make the gel, each gel was 80 ml.b-1: Weigh 0.8g of agarose, add 80ml of 0.5×TBE, weigh it on the balance and put it into the microwave oven, heat it on high for 2-3 minutes to make the agarose dissolve completely, shake it well, and observe it as a homogeneous and transparent solution without particles, then weigh it again on the balance and make up the appropriate amount of double-distilled water to keep the concentration of the gum unaffected.b-2: When the melted gel was cooled to about 55°C add 4 µl of ethidium bromide (10ug/ml) and gently swirl to mix well. The gel was made with an 18-tooth comb and the warm gel was poured into a 12 × 12 cm gel tray.b-3: Allow the gel to completely set (40 minutes at room temperature), carefully pull out the comb, remove the tray, and place it in the electrophoresis tank. Add 0.5× TBE buffer to the electrophoresis tank, not exceeding the gel surface by 1-2mm.b-4: Sample electrophoresis: add 12 samples to each gel (the topmost wells are not sampled), add 3-5µl PCR products to each well, and at the same time add three 5µl DNA MarkerⅠ to each gel. The voltage is 150V and the electrophoresis time is 100-120 minutes. This step is the key to the accuracy of the final readings of each point, and needs to be operated uniformly according to this standard.b-5: Some loci have amplification products greater than 1000bp in clinical strains, and these amplification products were then electrophoresed using 0.8% agarose gel, with DNA Marker II added as a control for the band size, voltage 150V, electrophoresis time 150 minutes.4) Results display:5) Analysis of results:a. If the genotypes of the three highly variable loci are also the same in different strains, they can be identified as clustered strains;b. If the high variant readings are highly similar, i.e., only 1-2 high variant sites are different, they need to be combined with epidemiologic data to identify if they are clustered strains;c. If all 3 high variant loci are genotypically discordant, identify as a single strain.Appendix 1: Rules for reading VNTR lociAppendix 2: VNTR locus repeat unit readout table... Read More |