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Polymerase Chain Reaction (PCR)

PCR is an enzyme (polymerase) mediated process where a single copy target DNA (Deoxyribonucleic acid) sequence can be amplified in order to obtain multiple copies of the same. The reaction proceeds in an exponential fashion, hence called a chain reaction. The raw material for PCR are four nucleotide bases namely Adenine (A), Guanine (G), Thymine (T) and Cytosine (C), the building blocks of DNA.

Application of PCR in wildlife genetic studies

The very fact that multiple copies of the single target DNA sequence can be obtained through PCR opens up vast possibilities of its application in genetic studies. PCR allows selective amplification of target gene/ DNA fragment through primers specific for a particular region of the genome (the total genetic content of an organism).

Talking strictly in terms of wildlife studies, the biggest problem comes when the collection of biological samples become necessary. For a genetic study of rare or endangered species either sample are scarce or the capturing of the animal is not advisable. Only possibility of undertaking genetic work is to proceed with minimum amount of samples available (already collected specimens in the museums and other repositories) or collect samples noninvasively (i.e., without capturing the animal, e.g., faeces, hair, urine, feathers of birds, shed off skin etc.). In any of the cases, PCR allows multiplying the number of gene/ DNA fragment of interest up to a limit which can be observed through a process called electrophoresis (Gel or capillary electrophoresis, a process of separating DNA fragments on the basis of their size or molecular weight), thereby determining the size or the exact sequence of the DNA fragment (through DNA sequencing).

This size and/or sequence data can be compared across the hierarchy of classification of organisms, even up to the individual level of a species to study the variation (called polymorphism). A particular fragment of DNA used for such comparisons is a unique, signatory, polymorphic fragment of the genome called a marker locus.

To know more about this initiative please contact Mr. Gautom Uzir at Phone: +919435145166 or Mr. Ajoy Kumar Das at ajoy@aaranyak.org