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Science Info, LLC, in partnership with the Electric Book Company, is pleased to present this month's online journal club. This month's online journal topic covers an overview of polymerase chain reaction (PCR). We hope you find this month's presentation of value to you and your team as you continue your important work in medical research.

PCR is a method that allows exponential amplification of short DNA sequences (usually 100 to 600 bases) or number of copies of a specific region, within a longer double stranded DNA molecule.

PCR entails the use of a pair of primers, each about 20 nucleotides in length that are complementary to a defined sequence on each of the two strands of the DNA. These primers are extended by a DNA polymerase so that a copy is made of the designated sequence. After making this copy, the same primers can be used again, not only to make another copy of the input DNA strand but also of the short copy made in the first round of synthesis. This leads to exponential amplification.

Based on the same principal new PCR technique has been developed for RNA amplification. This is referred to as RT PCR (reverse transcriptase-PCR) not to be confused with Real time PCR which would be described later.

In RT PCR an additional step is involved. Functional RNA (mRNA) initially transcribed to cDNA (complementary DNA) which was then amplified by PCR and again analyzed by agarose gel electrophoresis.

In Real-time PCR monitors the fluorescence emitted during the reaction as an indicator of amplicon production during each PCR cycle (i.e., in real time) as opposed to the endpoint detection

This technique can be used to identify with a very high-probability, disease-causing viruses and/or bacteria, a deceased person, or a criminal suspect.

Two recent papers we choose for this month Journal club explain how this basic technology can be modified to be used as diagnostic tool

The paper by Mehta et al. [1] describes a method in which very low quantity blood can be used to measure the HIV viral loads. This is particularly significant because of this method can be used to diagnose from dry blood spots obtain from infants. This method also overcomes the limitation of serologic assays which requires large quantity of blood.

This paper describe a method in which real time PCR assay was employed using LightCycler [2] , to quantify viral loads using RNA extracted from dried blood spots. Authors claim its reproducibility, diagnostic accuracy, specificity and lower cost compared to the currently available commercial assays make this method adaptable for future diagnostic method.

The Second Paper by Spurgeon et al, [3] describes how the microfluidic and PCR technology can be combined to further modify gene expression assays - the combination sets the stage for the next generation of high throughput gene expression platform on a single chip.

Authors explain that this new chip based platform [4]requires less pipetting than regular 96 well plates. They further claim that this robust method can measure the expression of 45 different genes in 18 tissues with replicate in a single chip.

So take the time to review this month's papers - and if so inclined, don't hesitate to register- only registered members can post topics and exchange messages with other members of our 'online journal club'.

We hope you enjoy this month's issue, and we look forward to another month of delivering the best content that makes a difference in your professional development.

Regards to all.

Jeya Chelliah
Editor
ScienceInfo Journal Club