OPTIMIZATION OF SINGLE-STRAND CONFORMATION POLYMORPHISM AND SEQUENCE-ANALYSIS OF THE MITOCHONDRIAL CONTROL REGION IN PAGELLUS-BOGARAVEO (SPARIDAE, TELEOSTEI) - RATIONALIZED TOOLS IN FISH POPULATION BIOLOGY

We report the isolation and sequencing of 400-550 base pairs (bp) of t he mitochondrial DNA (mtDNA) control region of eight species of Sparid ae (Perciformes, Teleostei). This sequence information allowed us to d esign specific primers to one of these species (Pagellus bogaraveo). T he new set of primers was used to test a rationalized approach to stud y the mtDNA nucleotide variability at the intraspecific level. The sin gle-strand conformation polymorphism (SSCP) technique was applied to d etect sequence variation in two non-overlapping fragments of the contr ol region of 32 individuals of P. bogaraveo. To assess the sensitivity of the method, the nucleotide sequence of the analysed region was det ermined for all the specimens. The results showed that, for one of the two fragments, SSCP analysis was able to detect 100% of the underlyin g genetic variability. In sharp contrast, nucleotide variation of the second DNA fragment was completely unresolved by SSCP under different experimental conditions. This suggests that the resolution power of SS CP is crucially dependent on the nature of the fragment subjected to t he analysis; therefore, a preliminary test of the sensitivity of the m ethod should be performed on each specific DNA fragment before startin g a large-scale survey. A rationalized approach, combining the SSCP te chnique and a simplified sequencing procedure, is proposed for studyin g intraspecific polymorphism at the mtDNA control region in fish.