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Determining the optimal reference gene, Determining the optimal reference gene 7 – Bio-Rad SsoAdvanced™ Universal Probes Supermix User Manual

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SsoAdvanced

Universal Probes Supermix Instruction Manual

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Real-Time PCR Validation for Gene Expression Experiments

The following validation experiments are critical for obtaining valid and publishable real-time
PCR data following the MIQE guidelines. These simple-to-follow experiments should be
completed prior to starting a new real-time PCR project.

Determining the Optimal Reference Gene

To properly perform a gene expression experiment, it is imperative that an optimal
reference gene(s) is used. The reference gene(s) must maintain a consistent expression
level across all samples in the project regardless of treatment, source, or extraction
method. The variation in reference gene expression is somewhat dependent on the level
of fold change discrimination desired. For example, if a twofold change in expression is
important, then the reference gene should have little to no variation in expression. However,
if a 20-fold change in expression is important, then the reference gene expression can have
some variability. To validate a reference gene(s), follow the steps on the next page.

1. Begin searching for a candidate list of reference genes by searching publications, speaking

with researchers using similar model systems, and mining microarray data, if available.
Minimally, five reference genes should be selected for evaluation. For your convenience,
Bio-Rad offers pre-plated reference gene panels using our highly validated and optimized

PrimePCR assays

.

Table 2. Thermal cycling protocol.

Amplification

Polymerase

Annealing/

Setting/Scan Activation and

Denaturation Extension + Plate

Real-Time PCR System

Mode

DNA Denaturation at 95/98°C

Read at 60°C** Cycles

Bio-Rad

®

CFX96

, CFX384

,

CFX96 Touch

, CFX384 Touch

, All channels

10–30 sec

CFX Connect

Bio-Rad

®

iQ

5, MiniOpticon

,

Standard

15–30 sec

Chromo4

, MyiQ

ABI 7500, StepOne,

Fast

5–15 sec

10–30 sec 35–40

StepOnePlus, 7900HT

Standard

60 sec

and ViiA7

Roche LightCycler 480

Fast

10–30 sec

Standard

60 sec

Qiagen Rotor-Gene and

Fast

10–30 sec

Stratagene Mx series

* 2–3 min denaturation at 95°C is highly recommended for genomic DNA template to ensure complete denaturation.

** Shorter annealing/extension times (1–10 sec) can be used for amplicons <100 bp. Longer annealing/extension

times (30–60 sec or more) can be used for amplicons >250 bp, GC- or AT-rich targets, low expressing targets,
crude samples, or for higher input amounts (for example, 100 ng of cDNA or 500 ng of genomic DNA).

30 sec at 95°C for
cDNA
or

5–15 sec

2–3 min at 95°C

for genomic DNA*



35–40