New mitochondrial and nuclear primers for the Mediterranean marine bivalve Pinna nobilis

Pinna nobilis is the largest endemic Mediterranean marine bivalve. During past centuries various human activities led to the regression of its populations. As a consequence of stringent protection policies (P. nobilis is included in Annex IV of the Habitat Directive and Annex II of the Barcelona Convention), demographic expansion to many sites is currently reported. The aim of this study was to test a set of four species-specific primers designed by the authors, which could prove useful for the assessment of the genetic variability in P. nobilis. The level of polymorphism of two mitochondrial (nad3 and 12S) and two nuclear (18S and 28S) primers was thus assessed in 136 specimens from 28 Mediterranean localities. Furthermore, a comparison with the level of polymorphism obtained using the mitochondrial specific primers pairs so far available (COI and 16S) was performed. The mitochondrial gene nad3 showed the highest level of variability, which was comparable to those obtained for COI and 16S. Very low levels were detected for the mitochondrial 12S and the nuclear 18S and 28S genes. This research also showed that the use of nad3, COI and 16S concatenated sequences represents a useful tool for future studies devoted to infer the genetic variability of P. nobilis populations, thus allowing the development of effective conservation plans.