DNA Barcoding for Species Identification

ECACC uses DNA barcoding for the speciation of cell lines; this has superseded the use of isoenzyme analysis. DNA barcoding utilizes the amplification and sequencing of a portion of one of the mitochondrial protein-coding genes.

Mitochondria have their own genome, distinct from the nuclear genome. There are 5-10 fold more differences between species in the mitochondrial genome compared to the nuclear genome. Also, mitochondrial DNA generally does not contain introns thus shorter regions need to be analysed to distinguish species greatly simplifying the genetic analysis required. Generally, only a single PCR and sequencing reaction are required. In addition, intra-specific variation is low. This coupled to the large inter-specific variation make analysis of mitochondrial DNA an ideal candidate for identification of species.

Among protein coding gene candidates, the cytochrome c oxidase sub-unit 1 gene (CO1) was one of the first genes to be studied for the purpose of species identification and has since been shown to contain sequence differences representative of the other mitochondrial genes. The availability of published PCR primer sequences for this region has therefore increased this genes currency as the region of choice for speciation using this method.