Description
FormerlyRNA Extraction Control 670.
RT-qPCR Extraction Control not only enables users of a diagnostic qPCR assay to determine if there are inhibitors in the PCR assay, but also to validate the success of the extraction step, reducing the chance of obtaining a false negative result in the sample RNA.Product Highlights
- Simple – streamlined protocol for straightforward validation of RNA extraction and determination of RT-qPCR assay inhibition
- Sensitive – control assay identifies even small effects on RNA extraction and inhibition of amplification
- Optimized - control RNA has a sequence with no known homology to any organism thereby avoiding detection of sample RNA
- Specific – probe-based assay designed specifically for the REC control sequence
- Flexible – ideal for use with a wide range of sample types, including inhibitor-rich samples like blood, urine and sputum samples
Product Description
A common practice in qPCR is to add a known amount of spiked control RNA after RNA extraction, this monitors PCR inhibition but has no value as an extraction control. The ideal situation is to have the test sample and internal control undergo the same processing prior to qPCR. Meridian has developed a RT-qPCR Extraction Control, which more closely mimics the test sample, as compared to spike controls. Genetic material from the test sample and the RT-qPCR Extraction Control is simultaneously extracted by common extraction methods, with the extraction control being as sensitive to inhibition and extraction failure as the test sample.
Artificial RT-qPCR Extraction Control cells are of a known concentration, containing the Internal Control RNA sequence. This sequence contains no known homology to any organism and, importantly, has minimal interference with detection of sample RNA. The RT-qPCR Extraction Control cells are spiked into the lysis buffer with the target sample, prior to RNA extraction. Control Mix, which includes primers and probe, is then added to the reaction mix before amplification. Signal derived from the Internal Control RNA confirms the success of the extraction step. RT-qPCR Extraction Control also monitors co-purification of PCR inhibitors that may cause biased or false amplification patterns.
Applications
- Pathogen detection
- Cancer risk assessment
- Gene expression analysis
- Drug therapy efficacy
- Biomarker validation
- Copy number variation (CNV) analysis
- Genotyping
- Viral loading
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1.怎么看两个反应-即目标基因和内参基因是否具有相同的扩增效率?
2.每次PCR反应的扩增情况都有差异,多次反应的扩增效率岂不是都不一样了吗?
3.如何设计才能让相对定量更可行?
由于对定量PCR的接触不多,希望各位高手多多帮助!谢谢!
检测荧光信号的步骤有误:一般SG法采用72℃延伸时采集,Taqman法则一般在退火结束时或延伸结束采集信号。
引物或探针降解:可通过PAGE电泳检测其完整性。
模板量不足:对未知浓度的样品应从系列稀释样本的最高浓度做起。
模板降解:避免样品制备中杂质的引入及反复冻融的情况。
2.Ct值出现过晚(Ct>38)
扩增效率低:反应条件不够优化。设计更好的引物或探针;改用三步法进行反应;适当降低退火温度;增加镁离子浓度等。
PCR各种反应成分的降解或加样量的不足。
PCR产物太长:一般采用80-150bp的产物长度。
3.标准曲线线性关系不佳
加样存在误差:使得标准品不呈梯度。
标准品出现降解:应避免标准品反复冻融,或重新制备并稀释标准品。
引物或探针不佳:重新设计更好的引物和探针。
模板中存在抑制物,或模板浓度过高
4.负对照有信号
引物设计不够优化:应避免引物二聚体和发夹结构的出现。
引物浓度不佳:重庆新桥医院网上预约挂号www.cqxqyy.net适当降低引物的浓度,并注意上下游引物的浓度配比。
镁离子浓度过高:适当降低镁离子浓度,或选择更合适的mix试剂盒。
模板有基因组的污染:RNA提取过程中避免基因组DNA的引入,或通过引物设计避免非特异扩增。
5.溶解曲线不止一个主峰
引物设计不够优化:应避免引物二聚体和发夹结构的出现。
引物浓度不佳:适当降低引物的浓度,并注意上下游引物的浓度配比。
镁离子浓度过高:适当降低镁离子浓度,或选择更合适的mix试剂盒。
模板有基因组的污染:RNA提取过程中避免基因组DNA的引入,或通过引物设计避免非特异扩增。
6.扩增效率低
反应试剂中部分成分特别是荧光染料降解。
反应条件不够优化:可适当降低退火温度或改为三步扩增法。
反应体系中有PCR反应抑制物:一般是加入模板时所引入,应先把模板适度稀释,再加入反应体系中,减少抑制物的影响。
7.同一试剂在不同仪器上产生不同的曲线,如何判断?
判断标准:扩增效率,灵敏度,特异性
如果扩增效率在90%-110%,都是特异性扩增,都可以把数据用于分析。
8.扩增曲线的异常?比如“S”型曲线?
参比染料设定不正确(MasterMix不加参比染料时,选NONE)
模板的浓度太高或者降解
荧光染料的降解
什么是纯荧光校正,多长时间校正一次:
纯荧光校正是测定各种纯荧光染料标准品的波长和信号强度,通俗地说是让仪器“认识”各种荧光染料。软件收集并储存各种纯荧光染料标准品的荧光信息。以后每次定量实验运行过程中,SDS软件收集样品的原始光谱信号,并将此原始光谱与纯荧光文件中的数据进行比较,精确扣除不同染料的信号重叠部分,从而确定样品中的荧光染料种类和信号强度。
推荐每半年进行一次纯荧光校正。在运行光谱校正之前,请先进行背景校正和ROI校正。
1.熔融温度为75,74,73度的样品是否是同一个产物?熔融温度为56度的是不是没有扩增产物?
2.为什么相同的标准品不同反应CT值差别这么大?是不是荧光染料降解?我用的是试剂盒中的扩增酶,还没用几次。
3.扩增曲线的形态是否说明标准品已经有降解?
4.另外,我原来做CDNA梯度稀释做的挺好,可是这个直接是RNA为标准品,我用一步法进行QRT-PCR。标准品梯度稀释线性效果不稳定,有的时候好,有的时候不好。请假大家有没有好的建议?
附件中有扩增曲线和熔融曲线,请大家帮忙分析,谢过了!
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