A new molecular method for fast differentiation of cockles Cerastoderma edule and Cerastoderma glaucum

Abstract

AbstractCerastoderma edule and C. glaucum are two species of cockles that co-exist in European waters. They are morphologically similar but exhibit remarkable differences in biological, ecological, and genetic aspects, as well as in resistance to parasites (e.g., Martellia cochilia) and in disease incidence (e.g., disseminated neoplasia). Moreover, they differ in their economic significance; while C. edule represents a highly valuable marine resource, C. glaucum is only marginally fished. The aim of this work was to develop a simple and fast method that, for the first time, uses the sequence of a mitochondrial gene for the molecular differentiation of the two cockle species. A total of 304 partial sequences of the cytochrome c oxidase subunit I (COI) gene, retrieved from the Nucleotide database, were used to design two sets of species-specific primers to generate PCR products of different sizes (322 bp in C. glaucum and 247 bp in C. edule). The discriminatory ability of the PCR assay was tested in cockles from the Spanish, French, and Italian coasts with successful differentiation in all cases. This novel molecular identification method requires minimal technical equipment and can be carried out in one working day. For its simplicity, it can be very useful for conservation and sustainable management of the two cockle species, facilitating the assessment of distribution, abundance and relative sensitivity to viruses, parasites and diseases.