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sjtea新蟲 (初入文壇)
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[求助]
新人請教一個PCR問題,請多多幫助啦
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這是今天PCR的結(jié)果 目的片段是200bp,marker從上至下依次是2000,1000,750,500,300,100 不知道這樣的結(jié)果算得上是有條帶嗎? 不知道這種情況下該怎么改進呢? 謝謝各位了,在線等! |
【分子生物】EPI帖 | 精華帖轉(zhuǎn)載 |

木蟲 (職業(yè)作家)
哲學@草根

木蟲 (職業(yè)作家)
哲學@草根
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Troubleshooting discussion is based on the PCR protocol as described in the table below. All reactions are run for 30 cycles. From Yale University (這個是我以前做AS-PCR(SNP)的時候查的,給我不少啟示) 1. I get (many) longer unspecific products. What can I do? 擴增出比較長的非特異性產(chǎn)物? Decrease annealing time減少退火時間 Increase annealing temperature升高退火溫度 Decrease extension time減少延伸時間 Decrease extension temperature to 62-68º C降低延伸溫度到62-68º C Increase KCl (buffer) concentration to 1.2x-2x, but keep MgCl2 concentration at 1.5-2mM.增加KCl濃度到1.2-2.0倍,但是保持MgCl2濃度在1.5-2.0mM Increase MgCl2 concentration up to 3-4.5 mM but keep dNTP concentration constant.增加MgCl2濃度到3-4.5 mM,但是保持dNTP濃度不變。 Take less primer減少引物 Take less DNA template減少DNA模板濃度 Take less Taq polymerase少用些Taq酶 If none of the above works: check the primer for repetitive sequences (BLAST align the sequence with the databases) and change the primer(s)如上訴無效果:核對引物的重復序列和換引物 Combine some/all of the above 上訴方法靈活使用 -------------------------------------------------------------------------------- 2. I get (many) shorter unspecific products. What can I do? 擴增出比較短的非特異性產(chǎn)物 Increase annealing temperature升高退火溫度 Increase annealing time增加退火時間 Increase extension time增加延伸時間 Increase extension temperature to 74-78º C增加延伸溫度到74-78º C Decrease KCl (buffer) concentration to 0.7-0.8x, but keep MgCl2 concentration at 1.5-2mM減少KCl濃度至0.7-0.8倍,但是保持MgCl2濃度在1.5-2mM Increase MgCl2 concentration up to 3-4.5 mM but keep dNTP concentration constant增加MgCl2濃度到3-4.5 mM但是保持dNTP濃度不變 Take less primer少用引物 Take less DNA template少用模板 Take less Taq polymerase少用酶 If none of the above works: check the primer for repetitive sequences (BLAST align the sequence with the databases) and change the primer(s)同第一問題 Combine some/all of the above -------------------------------------------------------------------------------- 3. Reaction was working before, but now I can't get any product. 反應(yīng)以前有產(chǎn)物,可是現(xiàn)在不行。 Make sure all PCR ingredients are taken in the reaction (buffer, template, Taq, etc)確保反應(yīng)所有的成分都存在 Change the dNTP solution (very sensitive to cycles of thawing and freezing, especially in multiplex PCR)更換dNTP溶液 If you just bought new primers, check for their reliability (bad primer synthesis ?)新引物要保持其合成的準確可靠性 Increase primer amount增加引物的量 Increase template amount增加模板的量 Decrease annealing temperature by 6-10º C and check if you get any product. If you don't, check all your PCR ingredients. If you do get products (including unspecific ones) reaction conditions as described above.將退火溫度降低6-10º C后核對一下是否有產(chǎn)物,如果沒有就確認一下PCR反應(yīng)的成分是否都存在。如果能獲得產(chǎn)物(包括非特異性的產(chǎn)物)然后采取上訴方法。 Combine some/all of the above 4. My PCR product is weak. Is there a way to increase the yield? PCR的產(chǎn)物的量很少,怎樣增加產(chǎn)量? -------------------------------------------------------------------------------- Gradually decrease the annealing temperature to the lowest possible.逐漸降低退火溫度到最大可能 Increase the amount of PCR primer增加引物的量 Increase the amount of DNA template增加模板的量 Increase the amount of Taq polymerase增加酶的量 Change buffer (KCl) concentration (higher if product is lower than 1000bp or lower if product is higher than 1000bp)改變buffer中KCL的濃度(增加如果產(chǎn)物少于1000bp,減少如果大于1000bp) Add adjuvants. Best, use BSA (0.1 to 0.8 µg/µL final concentration). You can also try 5% (v/v, final concentration) DMSO or glycerol.加入輔佐劑。最好用BSA;蛘哂5%的二甲基亞砜 Check primer sequences for mismatches and/or increase the primer length by 5 nucleotides核對一下一物種錯配的,或者增加5個核苷酸 Combine some/all of the above 5. My two primers have very different melting temperatures (Tm) but I cannot change their locus. What can I do to improve PCR amplification? 兩個引物的溶解溫度非常不一樣但不能改變基因座。如何改進? -------------------------------------------------------------------------------- An easy solution is to increase the length of the primer with low Tm. If you need to keep the size of the product constant, add a few bases at the 3' end. If size is not a concern, add a few bases at either the 3' or the 5' end of that primer.增加低溶解溫度的長度。 [ Last edited by wanhscn on 2011-9-6 at 22:29 ] |

木蟲 (著名寫手)

新蟲 (初入文壇)

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