Embodiment
Primer, probe design:
The multiple NptII gene order of selecting for use among the GMO (comprise the native sequences of NptII gene and manually reconstruct sequence) is compared, and selection wherein lacks secondary structure and conservative gene regions designs many to primer.Primer length is generally about 20 bases, and GC content is 50%-60%, no secondary structure and repeatability in the primer, and with the interior no complementary sequence of primer, the melting temperature (Tm) between primer (Tm value) differs less than 5 ℃ between primer.The length of probe is about 25 bases, and the Tm value is worth high about 5 ℃ than primer Tm.As follows according to primer, probe that mentioned above principle is designed:
Upstream: NptII730u, NptII757u, nptII850u, nptII-u
Downstream: NptII897r, nptII952r, nptII850r, nptII-r
Probe: nptIIprobe, nptII890FdB
Optimum primer, probe sequence are as follows:
Primer: upstream primer: NptII 730u:AGGATCTCGTCGTGACCCAT
Downstream primer: NptII 897r:GCACGAGGAAGCGGTCA
Probe sequence: NptII890FdB:Fam-CACCCAGCCGgCCACAGTCGAt-TAMKA
The foundation of reaction system and optimization:
The target region template that is adopted in the foundation of reaction system and the optimization obtains with following method: with the transgenic rapeseed that changes this gene over to of having proved conclusively is material, extract genomic nucleic acids with Promega Purification kit, carry out pcr amplification with the primer of the longest amplified fragments in the above-mentioned detection sequence area respectively again.Amplified production carries out 10 times of gradient dilutions with 1 * TE, chooses 10
-3, 10
-4, 10
-5, 10
-6, 10
-7Totally 5 extent of dilution are serial positive template, and the template when getting Ct value 23 wherein the person is as reaction system optimization later between 27.
The screening of primer, probe:
In the primer screening experiment with above-mentioned upstream primer and downstream primer in conjunction with special probe, pairing experimentizes arbitrarily.The fluorescent PCR instrument adopts PE7700 fluorescent PCR instrument.The PCR reaction system that is adopted is as shown in the table.
The PCR reaction system
Component | Final concentration |
10 * PCR reaction buffer | 1× |
DNTP (containing dUTP) | 0.2mmol/L |
The Taq enzyme | 2Unit |
Mg2+ concentration | 2.5mmol/L |
Primer (upstream) | 0.2umol/L |
Primer (downstream) | 0.2umol/L |
Probe | 0.1μmol/L |
Template DNA | 2ul |
Mend DEPC water extremely | 40ul |
The selection of PCR condition: according to our company's experience in the past, the selection of PCR condition is as follows:
Under same template amount, same reaction conditions, the Ct value and the Rn value that are obtained with the specific fluorescence probe signals of NptII sequence are index (the two can reflect pulsating amount of amplification and matter), the amplification situation of more different primers to making up.Select Ct value and the high person of Rn value, right as the primer that DNA/PCR to be selected detects.
Selected following best primer/probe combinations is a best of breed from repeated experiments repeatedly: upstream primer: NptII 730u; Downstream primer: NptII 897r; Probe: NptII890FdB.
With the best upstream and downstream primer of selecting to carrying out the optimization of PCR reaction system.
The optimization of primer and concentration and probe concentration
In the experiment primer concentration is increased progressively with 0.1umol/L from 0.1umol/L to 0.8umol/L, concentration and probe concentration increases progressively with 0.025umol/L from 0.025umol/L to 0.2umol/L.Proportioning to primer and probe different concns compares.Best primer and probe final concentration result are as follows::
Sequence to be checked | The primer title | Best final concentration (μ M) |
NptII | Upstream primer NptII 730u | 0.2 |
Downstream primer NptII 897r | 0.2 |
The best final concentration of probe title: NptII890FdB: 0.1 μ M.
The optimization of magnesium ion concentration
In the experiment magnesium ion concentration is increased progressively with 0.5mmol/L from 1.0mmol/L to 2.5mmol/L.
From repeatedly selecting 2.5mmol/L MgCl the repeated experiments
2Be test kit reaction system magnesium ion concentration.
The optimization of Taq archaeal dna polymerase (Taq enzyme) consumption
The optimization experiment result of Taq enzyme dosage (in the U of unit), selected 2U Taq enzyme is as using Taq enzyme amount in the test kit.
The optimization of dNTPs concentration
Selected 0.2mmol/L is as the final concentration of test kit dNTPs in the optimization experiment of dNTPs concentration.
Comprehensive above reaction system optimization experimental result, the PCR reaction system after the optimization sees the following form.
PCR reaction system after the optimization
Component | Final concentration |
10 * PCR reaction buffer (pH=8.9) | 1× |
Mg2+ concentration | 2.5mmol/L |
DNTPs (containing dUTP) | 0.2mmol/L |
The Taq enzyme | 2U |
Primer (upstream) | 0.2umol/L |
Primer (downstream) | 0.2umol/L |
Probe | 0.1umol/L |
Template | 2ul |
Moisturizing extremely | 40ul |
The 18s-rRNA gene test
The 18s-rRNA gene is a kind of gene that is present in all plants, so this test kit selects for use it as internal standard gene, is used for that monitoring of DNA is extracted and the whole process of fluorescent PCR, and setting up of 18s-rRNA system is the same, and primer, probe sequence are as follows:
Upstream primer sequence: 18s-rRNA1403u:cctgagaaacggctaccat
Downstream primer sequence: 18s-rRNA1449r:cgtgtcaggattgggtaat
Probe sequence: 18s-rRNA1423fb:FAM-TGCGCGCCTGCTGCCTTCCT-TAMRA
All should increase for all DNA of plants.Method by this test kit is extracted DNA, and its Ct value is between 9 to 25.
The foundation of DNA extraction method
Recommend to use traditional DNA of plants extracting method: CTAB method (specifically seeing Appendix two).Also characteristic selecting method per sample.
Nucleic acid extracting reagent also can adopt the Wizard Magnetic DNA Purififcation Systemfor Food test kit (Cat FF3750,200 tests) of Promega company.
The NptII test kit is formed
Composition (48tests/ box) | Volume |
CTAB method nucleic acid extracting reagent CTAB buffer solution CTAB precipitation buffering liquid precipitate lysate nucleic acid amplification reagent N ptII PCR reactant liquor (qualitative) 18s-rRNA PCR reactant liquor Taq enzyme (5U/ul) UNG (1U/ul) purified water reference substance NptII positive reference substance 18s-rRNA positive reference substance | 24ml * 1 pipe 40ml * 1 pipe 40ml * 1 pipe 1ml * 2 pipe 1ml * 2 pipe 40ul * 1 pipe 10ul * 1 pipe 100ul * 1 pipe 30ul * 1 pipe 30ul * 1 pipe |
Each component prescription in the test kit
NptII PCR reaction solution: get qualified 25mmol/L MgCl
2, 100mmol/L dATP, 100mmol/L dUTP, 100mmol/L dGTP, 100mmol/L dCTP, 50umol/L NptII upstream primer, 50umol/L NptII downstream primer, 50umol/L NptII probe, 10 * PCR damping fluid, 1U/ul UNG and purified water, by following formulated PCR reaction solution.
The reagent composition | Final concentration |
10×buffer | 1× |
MgCl
2 2.5mM
dNTPs(u) 200uM
Taq enzyme (adding in addition during detection) (2U)
NptII trip primer 0.2uM
NptII downstream primer 0.2uM
NptII probe 0.1uM
Template (adding in addition during detection) (5ul)
Water
Final volume (ul) 40ul
CTAB method sample process agent prescription:
CTAB damping fluid 20g CTAB/L, 1.4M NaCl, 0.1M Tris/HCl, 20mM
EDTA(ph=8.0)
CTAB precipitation buffering liquid 5g CTAB/L, 0.04M NaCl
Resolution of precipitate liquid 1.2M NaCl
18s-rRNA PCR reaction solution: get qualified 25mmol/L MgCl
2, 100mmol/L dATP, 100mmol/L dUTP, 100mmol/L dGTP, 100mmol/L dCTP, 50umol/L 18s-rRNA upstream primer, 50umol/L 18s-rRNA downstream primer, 50umol/L 18s-rRNA probe, 10 * PCR damping fluid, 1U/ul UNG and purified water, by following formulated PCR reaction solution.
Reagent composition final concentration
10×buffer 1×
MgCl
2 2.5mM
dNTPs(u) 200uM
Taq enzyme (adding in addition during detection) (2U)
18s-rRNA upstream primer 0.2uM
18s-rRNA downstream primer 0.2uM
18s-rRNA probe 0.1uM
Template (adding in addition during detection) (5ul)
Water
Final volume (ul) 40ul
Wherein, UNG is UNG enzyme (uridylic-N-Glycosylase) Uracil-N-glycosylase
The preparation of purified water
Use the tap water single flash,, collect the water of resistivity 〉=18.0M Ω .cm, store in the aseptic bottle through Millipore MILLI-Q PF PLUS pure water instrument purifying.
The preparation of positive reference substance
Get corresponding positive, CTAB method sample process reagent extracts DNA, with the above-mentioned DNA for preparing, with the primer amplification longer (using dTTP but not dUTP) than detection reaction amplified fragments, purpose nucleic acid fragment in the above-mentioned PCR product of Wizard PCRPreps DNA Purification System test kit purifying of employing Promega company, with the method for 1.5% agarose gel electrophoresis the amplified production of purifying is carried out quantitatively roughly again, the PGEM-TEasy Vector System II test kit with Promega company is connected the purpose fragment with the T carrier then; To connect product again and be transformed into the JM109 competent cell, use X-Gal and IPTG agar plate screening and cloning purpose bacterium colony then, PCR reaction evaluation.Carry out the amplification of plasmid with the LB liquid nutrient medium.Wizard Plus Minipreps DNAPurification System test kit with Promega company carries out the purification of plasmid at last, still the plasmid of purifying is carried out purity detecting, the positive reference substance mother liquor of eligible with the method for 1.5% agarose gel electrophoresis.Carry out Macrodilution with 1X TE.
The plasmid of dilution detects with qualified test kit, gets the Ct value 28~30, keeps somewhere in a large number, is used as and joins test kit, also is used as tentative company standard product.
Provide equipment and reagent for oneself
Water-bath, whizzer; Chloroform, Virahol (20 ℃ of precoolings), 70% ethanol (20 ℃ of precoolings)
Be suitable for instrument PE Gene Amp7700 fluorescent PCR detector or her suitable fluorescent PCR instrument secondly
Preserve and the validity period test
Sample process reagent is put room temperature preservation, and other reagent are put-20 ℃ of preservations, avoid multigelation.From the calibrating qualified from validity period be 12 months.Preserve under the storing temp that test kit requires from three batches of test kit assay approvals of quantity-produced, every month, proportionately product examine set pattern journey detected once, and in the time of 14 months, every index is all qualified, determines that therefore the test kit validity period is 12 months.
Using method
The sample nucleic acid extraction
1.1CTAB method is extracted DNA
1.1.1 the plant sample that takes by weighing after 100mg fully pulverizes is put into the 2ml centrifuge tube, adds 800ul CTAB damping fluid, behind the mixing in 65 ℃ of incubations 30 minutes;
1.1.2 centrifugal 10 minutes of 15500g shifts upper strata liquid to the pipe that contains the 400ul chloroform, mixing 30 seconds, again with centrifugal 10 minutes of 15500g until stratified liquid, draw upper strata liquid to clean centrifuge tube;
1.1.3 add 2V CTAB precipitation buffering liquid, incubation is 60 minutes under the room temperature;
1.1.4 mixed solution centrifugal 5 minutes with 15500g is abandoned supernatant;
1.1.5 add 500ul resolution of precipitate liquid dissolution precipitation, and add the 500ul chloroform, mixing after 30 seconds centrifugal 10 minutes with 15500g;
1.1.6 shift supernatant to another new pipe, add 0.6 times of volume Virahol, 15500g is centrifugal 10 minutes behind the abundant mixing, abandons supernatant liquor;
1.1.7 add 70% ethanol 500ul in containing sedimentary tubule, behind the careful mixing washing tube wall centrifugal 10 minutes (15500g), abandon supernatant;
1.1.8 drying at room temperature is dissolved in DNA (if sample DNA did not use the same day, please in-20 ℃ of preservations) in the 100ul aseptic deionized water then.
1.2Promega method is extracted the step (alternative) of DNA
The former method sample amount of taking by weighing is 200mg.According to the experience of our company, this measures extremely difficult mixing, so change the sample amount of taking by weighing into 100mg, reagent dosage thereafter and operation steps are then undertaken by former method fully.
2. reagent preparation (area in preparation before the PCR)
Take out from test kit and respectively manage reagent, room temperature is melted, centrifugal 5 seconds of 2000rpm.
A) establishing the needed pipe number of Npt.PCR is n (n=sample number * 2+1 pipe blank+1 pipe NptII positive reference substance);
B) establishing the needed pipe number of 18s-rRNA PCR is m (m=sample number * 2+1 pipe blank+1 pipe 18s-rRNA positive reference substance);
Each test reaction system is formulated as follows table:
NptII PCR reaction system | NptII PCR reaction solution 34.6ul | Taq enzyme 0.4ul | UNG 0.06ul |
The 18s-rRNA reaction system | 18s-rRNA PCR reaction solution 34.6ul | Taq enzyme 0.4ul | UNG 0.06ul |
Calculate the usage quantity of good each reagent, add in the proper volume test tube, thorough mixing is even, adds each 35ul of NptII PCR reaction solution respectively in n the PCR reaction tubes of setting; In m the PCR reaction tubes of setting, add each 35ul of 18s-rRNA PCR reaction solution reaction solution respectively, together be transferred to the sample process district.
2.1 application of sample (sample process district)
If sample DNA is kept at-20 ℃, puts room temperature earlier and thaw.
In the PCR of each setting reaction tubes, add above-mentioned sample DNA solution, purified water (blank) and each 5ul of corresponding positive reference substance respectively, build PCR reaction tubes lid, be transferred to detection zone, place on the quantitative PCR detector and write down sample and put order.
2.2.PCR amplification (detection zone)
2.2.1 cycling condition setting
37℃:5min;95℃:3min;
95 ℃: 15sec, 60 ℃: 1min, 40 circulations.Reaction system is made as 40ul.
(different fluorescent PCR instrument cycling conditions may slightly be adjusted)
2.2.2 instrument detecting channel selecting
All PCR reaction tubes fluorescent signals are collected and are made as the Fam fluorescence channel.
Concrete method to set up please refer to the instrument working instructions.
3. quality control standard
The detected result of Npt blank should be negative;
Ct value≤32.0 of NptII positive reference substance;
The detected result of 18s-rRNA blank should be negative;
Ct value≤30.0 of 18s-rRNA positive reference substance;
These parameters has the person of not meeting, the pcr amplification of should reforming.
4. the result judges
4.1. the threshold setting principle makes the negative control product become negative findings to be as the criterion with the vertex of threshold line just above normal negative control product amplification curve.
4.2. sample to be tested 18s-rRNA Ct value should≤17.0, if not in this scope, then need extract sample DNA again, the pcr amplification of reforming.
4.3. the Ct value of two parallel pipes of same sample is averaged, as the testing sample Ct value of judging usefulness.
Equal 40.0 4.4. sample to be tested NptII measures Ct value, report NptII gene order feminine gender (other fluorescent PCR instrument to the expression of feminine gender also may for 0.0 or the no numerical value of blank).
4.5. sample to be tested NptII measures Ct value≤34.0, reports the NptII gene order positive.
If 4.6. 34.0<sample to be tested Npt II genetic testing Ct value<40.0 need be done pcr amplification again.
Still<40.0 report the NptII gene order positive as amplification NptII genetic testing Ct value once more.
Equal 40.0 as amplification NptII genetic testing Ct value once more, then report NptII gene order feminine gender.
The test kit application notice
Relevant Good Laboratory Practice is please carried out in strict accordance with the breadboard management regulation of related gene amplification check of industry administrative responsibile institution promulgation.
Embodiment 1
Choose transgenosis and not genetically modified agricultural-food such as soybean, corn, rape, tomato, potato, extract genomic dna with the Promega paramagnetic particle method, be specially: the 100mg vegetable material of weighing places the 2ml centrifuge tube; Add 500ul LysisBuffer A and 5ul RNase A, with the material mixing; Add 250ul Lysis Buffer B, mixing, room temperature was placed 10 minutes; Add 750ul precipitation buffering liquid, high speed centrifugation behind the mixing (13000 * g) 10 minutes; Draw supernatant in clean 2ml centrifuge tube, add the 50ul magnetic powder fluid, mixing; Add 0.8 volume Virahol in the mixed solution, mixing, room temperature was placed 5 minutes; Centrifuge tube is placed magnet stand last 1 minute, remove clear liquor; Take out centrifuge tube, add 250ul Lysis Buffer B again, mixing is placed on magnet stand last 1 minute, removes clear liquor; Clean magnetic with 1ml 70% ethanol, place magnet stand last 1 minute, remove clear liquor; Step repeats 2 times; Take out centrifuge tube, in 65 ℃ of dried baths under dry 5 minutes or the room temperature dry 15-30 minute; Add the 100ul deionized water in the centrifuge tube, in 65 ℃ of dried baths, hatched 5 minutes behind the mixing, move to magnet stand last 1 minute again, draw clear liquor in the clean centrifuge tube of 0.5ml, standby as dna profiling.
Do fluorescent PCR with this test kit and detect, be specially: in the 40ul reaction system, add plant genome DNA 5ul, carry out fluorescent PCR and detect, concrete reaction conditions is the same.After testing, the amplification that all is positive of the genetically modified crops of the above-mentioned Npt of changing over to II gene, its detection sensitivity all can reach 0.1%; And not genetically modified agricultural-food such as conventional corn, white maize etc. all do not have amplified signal, point out this primer to having good sensitivity and specificity (specifically seeing figure one).
Test kit sensitivity is: 0.1%GMO, 0.1% standard substance are done 5 times of dilutions after, still can detect target fragment.
The test of test kit accuracy
3 operator that are skilled in technique respectively do 3 accuracy test experience (amounting to 9 times) at 3 different times in the company, each 10 parts of accuracy reference products of parallel processing.Ct value to per 10 gained is carried out statistical procedures with Microsoft Excel analysis software, draws the CV value of mean value and 10 Ct values, and experimental result shows that the CV value of Ct value shows that below 5.0% this test kit has good accuracy.
The test of test kit specificity
This test kit does not all have non-specific amplification to negative soybean, corn, rape, potato sample, shows that this test kit has good specificity.
All should increase for all DNA of plants.Method by this test kit is extracted DNA, and its Ct value is between 9 to 25.
The invention effect: through repeated screening, obtaining best of breed is upstream primer: NptII730u; Downstream primer: Npt897r; Probe: NptII890FdB.
The DNA that extracts with 0.1% transgenic rapeseed does template, and the Ct value that obtains is between 29.0-33.0, and this is the reliable detection lower limit of present different fluorometric assay instruments; And 0.1% detection sensitivity has reached the examination criteria of present international like product.
Primer probe in this test kit can also detect the genetically modified crops that contain the NptII gene as hybridization probe.
The methodology principle brief introduction of PCR-ELISA
This experiment will design one couple of PCR primers and a probe, they all with the complementation of template DNA chain, and the combining site of probe is between the primer combining site.With fluorescein (Fluorescein) on a primer 5 ' the end mark of PCR, carry out pcr amplification, the amplified production that obtains has fluorescein-labelled.With vitamin H (Biotin) on 5 ' the end mark of probe, be coated with avidin (Avidin) on the elisa plate simultaneously, the affinity interaction by vitamin H and avidin is coated on probe on the elisa plate.During detection, the amplified production sex change is become strand, on elisa plate, carry out special combining with probe, wash plate, add the fluorescein antibody of horseradish peroxidase again, pass through chromogenic reagent, on enzyme plate, read the OD value, according to the yin and yang attribute of OD value judgement sample.
Embodiment
With 5 ' the end mark vitamin H of above-mentioned probe NptII890FdB, 3 ' end does not make marks; With fluorescein on 5 ' the end mark of primer NptII 730u.Probe is coated on the elisa plate of avidin in advance.
(CTAB method or paramagnetic particle method) extracts the DNA in the sample according to a conventional method.By 10 * PCR damping fluid, dNTPs, Mg2+, Taq enzyme, upstream and downstream primer, H2O, and dna profiling composition PCR reaction system, increase.
Amplification becomes strand with the amplified production sex change after finishing, and is added to bag by on the elisa plate of probe, if specific amplification is arranged, chain in the amplified production and probe hybridization are washed plate, add enzyme connection fluorescein antibody, wash plate, add developer, developed the
color 10 minutes, stop colour developing, on microplate reader, read the OD value, according to the yin and yang attribute of OD value judgement sample.Following table is an experimental result once:
Sample | 0.0% corn | 0.1% corn | The Cry9c corn | The GMO rape | U.S. soybean | Argentina soybean | 0.1%Fluka soybean mark |
The OD value | 0.169 | 0.182 | 0.124 | >3.000 | 0.156 | 0.135 | 0.176 |
The result judges | - | - | - | + | - | - | - |
Sample |
Blank |
The Mon810 soybean |
0% soybean |
Potato |
The GMO tomato |
The GMO cotton |
The OD value |
0.108 |
0.164 |
0.176 |
>3.000 |
>3.000 |
>3.000 |
The result judges |
- |
- |
- |
+ |
+ |
+ |
Experimental result shows: as long as it is all positive through this system's detected result to contain the genetically modified crops of NptII gene order, and the crop that does not contain the NptII gene order detects all negative through this system.
<110〉National Entry-Exit Inspection and Quarantine Bureau Animals and Plants Quarantine Laboratory PiJi Biology Engineering Co., Ltd., Shenzhen City
<120〉the fluorescent PCR qualitative detection contains NptII gene transgenic crop probe sequence and test kit