1,720,977 research outputs found
mtDNA sequences of Sphyraena viridensis (Perciformes: Sphyraenidae) from Italy: Insights into historical events and the phylogeny of the genus
No full textThe yellowmouth barracuda, Sphyraena viridensis, is a Mediterranean native species whose exact distribution is uncertain due to a long-term taxonomic confusion with Sphyraenasphyraena. Records of this species in the Mediterranean Sea have recently increased, and a northwards expansion of its distribution has been suggested. Three mtDNA regions, namely cytochrome oxidase I, cytochrome b and the control region, were analysed in S.viridensis samples from Italian coastal regions to provide molecular markers useful in species identification, in phylogenetic analysis and in detecting the distribution of genetic variability of the yellowmouth barracuda in this area. The data clearly distinguish S.viridensis from S.sphyraena and the other four (one native and three Lessepsian) Mediterranean Sphyraena species and identify two clearly distinct lineages that diverged during the Pleistocene but are currently panmictic in the investigated area. Both lineages retain signatures of historical population expansion. © 2014 The Linnean Society of London
Distribuzione differenziale di uno spaziatore intergenico nel mtDNA di Atherina boyeri (Teleostei, Atherinidae).
No full textAnalisi citogenetica del cavedano di ruscello, Squalius lucumonis, e localizzazione comparativa dei geni ribosomali minori in altre tre specie di Leuciscinae
No full textMitochondrial DNA in Atherina (Teleostei, Atheriniformes): Differential distribution of an intergenic spacer in lagoon and marine forms of Atherina boyeri
No full textThe big-scale sand smelt Atherina boyeri lives in fresh water, brackish water and sea water of the western Atlantic Ocean and Mediterranean Sea. Previous studies concerning distribution, biometric characters and genetic molecular markers have suggested the possible existence of two or even three different groups or species of sand smelt, one 'lagoon' type and one (or two - punctuated and non-punctuated on the flanks) 'marine' type. In this study, the presence and the localization of an insertion was described, c. 200 bp in length, in the mtDNA of the lagoon and marine punctuated specimens of A. boyeri and its absence in the marine non-punctuated specimens, as well as in other two congeneric species, Atherina hepsetus and Atherina presbyter, and in the atheriniform Menidia menidia. The intergenic spacer is located between the tRNA Glu and cytochrome b (cyt b) genes and shares a c. 50% sequence similarity with cyt b. The distribution and the features of the intergenic spacer suggest that it might have originated from an event of gene duplication, which involved the cyt b gene (or, more likely, a part of it) and which took place in the common ancestor of the lagoon and the marine punctuated specimens. The data obtained therefore support the hypothesis of the existence of three cryptic and, or sibling species within the A. boyeri taxon and provide a genetic molecular marker to distinguish them. © 2008 The Authors
Molecular cytogenetic analysis of the Appenine endemic cyprinid fish Squalius lucumonis and three other Italian leuciscines using chromosome banding and FISH with rDNA probes
No full textKaryotype and other chromosomal characteristics of the Appenine endemic cyprinid fish, Toscana stream chub Squalius lucumonis, were analysed using conventional banding and FISH with 45S and 5S rDNA probes. The diploid chromosome number (2n = 50) and karyotype characteristics including pericentromeric heterochromatic blocks and GC-rich CMA(3)-positive sites corresponding to both positive Ag-NORs and 45S rDNA loci on the short arms of a single medium-sized submetacentric chromosome pair were consistent with those found in most European leuciscine cyprinids. On other hand, 5S rDNA FISH in the Toscana stream chub and three other Italian leuciscines, S. squalus, Rutilus rubilio and Telestes muticellus, revealed a species-specific hybridization pattern, i.e. signals on four (S. lucumonis), three (S. squalus and R. rubilio) and two (T. muticellus) chromosome pairs. Whereas all the species shared the 5S rDNA loci on the largest subtelocentric chromosome pair, a "leuciscine" cytotaxonomic marker, S. lucumonis showed both classes of rDNA loci tandem aligned on the short arms of chromosome pair No. 12. The present findings suggest that the observed high variability of 5S rDNA loci provides a powerful tool for investigation of karyotype differentiation in karyologically conservative leuciscine fishes
Genetic structure in lagoon samples of Atherina boyeri: effects of habitat discontinuity and low dispersal ability
No full textMolecular and morphological identification of an uncommon centrolophid fish
No full textThe use of both morphological and molecular methods has allowed a fast and reliable species assignment of a fish that local fishermen with over thirty years of experience had never seen before. The identified species, Schedophilus medusophagus, is rare along Italian coasts, and this is the first documented record in the Central Tyrrhenian Sea for over 35 years. Its abundance should be evaluated on a continuous basis, as it might reflect biological consequences of environmental and climatic change. The mitochondrial sequences obtained in this study constitute a useful molecular tag for future research and may contribute to the phylogenetic debate on the status of the genus Schedophilus, of which S. medusophagus is the type species. Based on the existing literature, these preliminary molecular data support the hypothesis that the genus is not monophyletic
Utilizzo di marcatori molecolari per la classificazione di un Teleosteo poco comune nel Tirreno centrale
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