Browsing by Author "Magoulas, A."
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- A genetic linkage map of the hermaphrodite teleost fish Sparus aurata L.Publication . Bargelloni, L.; Franch, R.; Patarnello, T.; Tsalavouta, M.; Sarropoulou, E.; Magoulas, A.; Kotoulas, G.; Chatziplis, D.; Georgoudis, A.; Louro, Bruno; Power, DeborahThe gilthead sea bream (Sparus aurata L.) is a marine fish of great importance for fisheries and aquaculture. It has also a peculiar sex-determination system, being a protandrous hermaphrodite. Here we report the construction of a first-generation genetic linkage map for S. aurata, based on 204 microsatellite markers. Twenty-six linkage groups (LG) were found. The total map length was 1241.9 cM. The ratio between sex-specific map lengths was 1:1.2 (male:female). Comparison with a preliminary radiation hybrid (RH) map reveals a good concordance, as all markers located in a single LG are located in a single RH group, except for Ad-25 and CId-31. Comparison with the Tetraodon nigroviridis genome revealed a considerable number of evolutionary conserved regions (ECRs) between the two species. The mean size of ECRs was 182 bp (sequence identity 60–90%). Forty-one ECRs have a known chromosomal location in the pufferfish genome. Despite the limited number of anchoring points, significant syntenic relationships were found. The linkage map presented here provides a robust comparative framework for QTL analysis in S. aurata and is a step toward the identification of genetic loci involved both in the determination of economically important traits and in the individual timing of sex reversal.
- Discord in the family Sparidae (Teleostei): divergent phylogeographical patterns across the Atlantic-Mediterranean dividePublication . Bargelloni, L.; Alarcon, J. A.; Alvarez, M. C.; Penzo, E.; Magoulas, A.; Reis, C; Patarnello, T.The Strait of Gibraltar has been proposed to be the divide between two marine biogeographical regions, the Mediterranean Sea and the Northeast Atlantic. Intraspecific studies have shown, for several of the examined species, a reduction of gene flow between the two basins. The present study examines genetic variation at nuclear and mitochondrial loci in five marine teleost species belonging to the family Sparidae. Four samples for each species were analysed spanning the Northeast Atlantic and the Mediterranean. For all individuals 17 allozyme loci were scored and a combined single strand conformation polymorphism-sequencing approach was used to survey approximately 190 bp of the mitochondrial DNA (mtDNA) D-loop region. All five species share similar biological features. For three species, namely Lithognathus mormyrus, Spondyliosoma cantharus, and Dentex dentex, large mtDNA divergence was observed between Atlantic and Mediterranean samples. Little or no mtDNA differentiation was found in the other two species, Pagrus pagrus and Pagellus bogaraveo. Allozyme data revealed strong differentiation when comparing Atlantic and Mediterranean samples of L. mormyrus and D. dentex, moderate for P. pagrus, and no differentiation for P. bogaraveo and S. cantharus. These results provide evidence for a sharp phylogeographical break (sensu Avise) between the Atlantic and the Mediterranean for two (or possibly three) sparid species of the five investigated. At the same time, the obtained results for the other two species raise the question on which ecological/historical factors might have caused the observed discrepancy in the geographical distribution of genetic variation among otherwise biologically similar species.
- Genomic resources for the aquaculture of European sea bassPublication . Volckaert, F.; Batargias, C.; Bonhomme, F.; Canario, Adelino V. M.; Chistiakov, D.; Choudhuri, J. V.; Galibert, F.; Georgoudis, A.; Haley, Chris; Hellemans, Bart; Kuhl, H.; Kotoulas, Georgios; Law, A.; Libertini, A.; Magoulas, A.; McAndrew, B. J.; Reinhardt, Richard; Senger, Fabrice; Souche, E.; Tsigenopoulos, C.; Whitaker, H. A.The BASSMAP consortium, funded by the European Union, has been set up to improve the understanding of the genome of European sea bass (Dicentrarchus labrax). The specific aim is to locate genes of known function on the physical map and to compare specific regions among perciforms. We have produced an F1 cross of outbred sea bass as mapping panel and a Bacterial Artificial Chromosome library (7× redundancy and 165 kb average insert size). End sequencing of the BAC library is in progress and a radiation hybrid panel is under construction.
- Has time come for the genetic management of sea bass?Publication . Volckaert, F.; Alvarez, M. C.; Argenton, F.; Bonhomme, F.; Chatain, B.; Colombo, L.; Castilho, Rita; Chevassus, B.; Gorshkova, G.; Kohler, M.; Magoulas, A.; Martinez, G.; McAndrew, B. J.; Piferrer, F.; Vandeputte, M.; Zanuy, S.Since 1980 the industrial production of European sea bass has risen considerably up to at least 18,000 MT in 1996 ( see also Josupeit, Aquaculture Europe 20(2):-12, 1995). This growth is remarkable since few were able to culture the species in the seventies. Several "classical" stages of development can be observed; they are typical of a rapidly expanding bioindustry.
- Mitochondrial DNA reveals a mosaic pattern of phylogeographical structure in Atlantic and Mediterranean populations of anchovy (Engraulis encrasicolus)Publication . Magoulas, A.; Castilho, Rita; Caetano, Sandra; Marcato, S.; Patarnello, T.This study extends the geographic coverage of a previous study of mitochondrial DNA restriction fragment length polymorphism in European anchovy. Both studies together include 24 samples representing 17 localities extending from the Black Sea, through the Mediterranean Sea to the eastern Atlantic as far south as Dakar, Senegal. Eighty-eight haplotypes deWne two clades (A and B) separated by 3.2% sequence divergence. Clade A has a star-like genealogy indicative of a recent population expansion. Clade B has a more complex genealogy, consisting of several haplotypes at intermediate frequencies. The distributions of these clades consist of a mosaic with abrupt changes between some areas and gradients between other areas. Clade A predominates the Black and Aegean seas, but is present throughout the Mediterranean. Unexpectedly, new data show that clade A is also at a high frequency in the Atlantic, from Portugal to at least Senegal. Overall, the level of genetic diVerentiation among populations is high (FSTD0.148, p<0.0001), with the greatest diVerences between basins. AMOVA reveals four main geographical groups: Atlantic, central Mediterranean, Aegean Sea, and Black Sea. Mismatch distribution clearly indicates historical bottleneck and population expansion for clade A, while for clade B such evidence is equivocal. This diVerence may reXect a range expansion for both clades, but with higher gene Xow (Nm values) between demes for clade A. Both contemporary and historical processes are important in shaping the complex genetic population structure of European anchovy.