PCR products from Colpophyllia natans and Diploria strigosa separating on a perpendicular denaturing gel

Denaturing gradient gel electrophoresis (DGGE) is often used in the analysis of microbial community structures. We are developing DGGE based methods of identifying which species of coral are present in plankton tows taken adjacent to recruitment survey sites.

DGGE utilises the difference in melting characteristics of same-length DNA fragments with different base compositions. The figure on the left shows how the melting profiles of two corals, Colpophyllia natans and Diploria strigosa, differ in a denaturing gradient gel, allowing both to be detected in an environmental sample.

The inability to identify coral planulae from morphology alone cripples attempts to link planktonic larval and sessile adult community structures. By providing a molecular means to evaluate the contents of plankton tows, empirical investigations of the relationship between larval supply and recruitment will finally become possible.