The completion of genomic sequences of physiologically important genes frequently revealsnon-coding genetic elements such as tandem repeats (micro- and minisatellites) that areoften more polymorphic than nearby coding sequences. We obtained the complete genomicsequences of three hormone genes in sea bass Dicentrarchus labrax: growthhormone (dlGH), somatolactin (dlSL) and insulin-likegrowth factor-1 (dlIGF-1), including 5′- and 3′-untranslated regions.Mini- and microsatellites were discovered in both flanking and intron regions. Some werepartially conserved across Perciformes. To assess the usefulness and relevance of thesegene-associated markers for understanding population structure, an investigation was madeon genetic diversity and differentiation at four of them in (i) five wildpopulations from the North Sea, the Bay of Biscay and the Western Mediterranean, and(ii) two samples of hatchery-bred individuals from afreshwater-acclimation experiment. Gene and allelic diversities were lower in culturedindividuals than in wild ones. Significant genetic differentiation was demonstratedbetween Bay of Biscay + North Sea and Mediterranean populations(F st > 0.06, p < 0.001),primarily due to dlGH-associated markers. Significant geneticdifferentiation was also detected among the Atlantic and North Sea samples, but restrictedto the locus associated with dlSL. Significant genetic differentiationwas also found among experimental individuals before and after a salinity challenge(F st ≈ 0.05, p < 0.001), but was dueto dlSL and dlIGF-1 loci. Gene-associated markers provedto be more efficient than formerly used anonymous microsatellite markers in providing aclear picture of genetic differentiation.

The complete Taenia asiatica mitochondrial genome was amplified by long extension polymerase chain reaction (long PCR) to yield overlapping fragments that were then completely sequenced. The whole mitochondrial genome was 13703 bp long and contained 12 protein-encoding, 2 ribosomal RNA (small and large subunits), 22 transfer RNA genes and a short non-coding region. Thus, its gene contents are like those typically found in metazoan animal mitochondrial genomes (apart from the absence of atp8). All the genes were transcribed from the same strand. The 3′ end 34 bp region of nad4L overlapped with the 5′ end portion of nad4. The tRNA genes were 61–69 bp long, and the secondary structures of 18 tRNAs had typical clover-leaf shapes with paired DHU arms. However, trnC, trnS1, trnS2 and trnR had unpaired DHU arms that were 7–12 bp in length. The tRNAs that transferred serine lacked a DHU arm, as is also observed in a number of parasitic platyhelminths and metazoans. However, the trematode trnRs have paired DHU arms. The T. asiatica mtDNA non-coding region was like that in other cestodes since it was composed of a short non-coding region of 72 nucleotides and a long non-coding region of 176 nucleotides separated by a trnL1/, trnS2/, trnL2/, trnR/, nad5 gene cluster. The sequences of the cox1 genes between T. asiatica and T. saginata differ by 4·6%, while the T. asiatica cob gene differs by 4·1% and 12·9% from the cob genes of T. saginata and T. solium, respectively. In conclusion, the T. asiatica mitocondrial genome should provide a resource for comparative mitochondrial genomics and systematic studies of parasitic cestodes.