Browsing by Author "Sarropoulou, Elena"
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- Comparative analysis and characterization of expressed sequence tags in gilthead sea bream (Sparus aurata) liver and embryosPublication . Sarropoulou, Elena; Power, Deborah; Magoulas, Antonio; Geisler, Robert; Kotoulas, GeorgiosThe gilthead sea bream (Sparus aurata) is one of the main European aquaculture products and a prospective model species for the Sparidae, which includes several other commercially important species. Future selective breeding of aquaculture stocks will be heavily underpinned by molecular genetic techniques, especially by marker-assisted selection (MAS). Gene marker resources in marine fish species, however, lag behind those of other agricultural animals, and only scanty information exists about the genetic source of phenotypic variation and the identity of quantitative trait loci (QTL). In order to develop molecular resources in gilthead sea bream, complementary DNA libraries were constructed from liver and mixed embryo and larval stages by unidirectional cloning. A long-read expressed sequence tag (EST) database was generated, containing 1394 cDNA clones representing 852 unique cDNA sequence-reads. Tissue-specific patterns of gene expression were determined when grouped using the proposal for characterizing cellular component put forward by the Gene Ontology consortium. Transcripts encoding cytoskeletal proteins were most abundant in the embryonic/larval library, while the most abundant transcripts in the liver library encoded secreted and extracellular proteins. Of both libraries, 505 clones were sequenced in both orientations (5Vand 3Vend sequencing), where 226 clones were determined as full-length sequence reads. Cluster analysis of 3Vend-sequenced clones from both libraries revealed that alternative polyadenylation signals were utilized, although no evidence of alternative splicing was found. We report for the first time for gilthead sea bream or any sparid a transcriptional analysis of two tissues and briefly consider the utility of ESTs for characterizing tissue-specific expression profiles. D 2004 Elsevier B.V. All rights reserved.
- Gene expression profiling of gilthead sea bream during early development and detection of stress-related genes by the application of cDNA microarray technologyPublication . Sarropoulou, Elena; Kotoulas, Georgios; Power, Deborah; Geisler, RobertGene expression profiling of gilthead sea bream during early development and detection of stress-related genes by the application of cDNA microarray technology. Physiol Genomics 23: 182–191, 2005. First published July 26, 2005; doi:10.1152/physiolgenomics.00139.2005.—Large-scale gene expression studies were performed for one of the main European aquaculture species, the gilthead sea bream Sparus auratus L. For this purpose, a cDNA microarray containing 10,176 clones from a cDNA library of mixed embryonic and larval stages was constructed. In addition to its importance for aquaculture, the taxonomic position and the relatively small genome size of sea bream makes it a prospective model for evolutionary biology and comparative genomics. However, so far, no large-scale analysis of gene expression exists for this species. In the present study, gene expression was analyzed in gilthead sea bream during early development, a significant period in the determination of quantitative traits and therefore of considerable interest for aquaculture. Synexpression groups expressed primarily early and late in development were determined and were composed of both known and novel genes. Furthermore, it was possible to identify stress response genes induced by cortisol injections using the cDNA microarray generated. The creation of gene expression profiles for sea bream by microarray hybridization will accelerate identification of candidate genes involved in multifactorial traits and certain regulatory pathways and will also contribute to a better understanding of the genetic background of fish physiology, which may help to improve aquaculture practices.
- A gene-based radiation hybrid map of the gilthead sea bream Sparus aurata refines and exploits conserved synteny with Tetraodon nigroviridisPublication . Sarropoulou, Elena; Franch, Rafaella; Louro, Bruno; Power, Deborah; Bargelloni, Luca; Magoulas, Antonio; Senger, Fabrice; Kotoulas, Georgios; Geisler, RobertBackground: Comparative teleost studies are of great interest since they are important in aquaculture and in evolutionary issues. Comparing genomes of fully sequenced model fish species with those of farmed fish species through comparative mapping offers shortcuts for quantitative trait loci (QTL) detections and for studying genome evolution through the identification of regions of conserved synteny in teleosts. Here a comparative mapping study is presented by radiation hybrid (RH) mapping genes of the gilthead sea bream Sparus aurata, a non-model teleost fish of commercial and evolutionary interest, as it represents the worldwide distributed species-rich family of Sparidae. Results: An additional 74 microsatellite markers and 428 gene-based markers appropriate for comparative mapping studies were mapped on the existing RH map of Sparus aurata. The anchoring of the RH map to the genetic linkage map resulted in 24 groups matching the karyotype of Sparus aurata. Homologous sequences to Tetraodon were identified for 301 of the gene-based markers positioned on the RH map of Sparus aurata. Comparison between Sparus aurata RH groups and Tetraodon chromosomes (karyotype of Tetraodon consists of 21 chromosomes) in this study reveals an unambiguous one-to-one relationship suggesting that three Tetraodon chromosomes correspond to six Sparus aurata radiation hybrid groups. The exploitation of this conserved synteny relationship is furthermore demonstrated by in silico mapping of gilthead sea bream expressed sequence tags (EST) that give a significant similarity hit to Tetraodon. Conclusion: The addition of primarily gene-based markers increased substantially the density of the existing RH map and facilitated comparative analysis. The anchoring of this gene-based radiation hybrid map to the genome maps of model species broadened the pool of candidate genes that mainly control growth, disease resistance, sex determination and reversal, reproduction as well as environmental tolerance in this species, all traits of great importance for QTL mapping and marker assisted selection. Furthermore this comparative mapping approach will facilitate to give insights into chromosome evolution and into the genetic make up of the gilthead sea bream.
- A genetic linkage map of the hermaphrodite teleost fish Sparus aurata L.Publication . Franch, Rafaella; Louro, Bruno; Tsalavouta, Matina; Chatziplis, Dimitris; Tsigenopoulos, C.; Sarropoulou, Elena; Antonello, Jenny; Magoulas, Andonis; Mylonas, Constantinos C.; Babbucci, Massimiliano; Patarnello, T.; Power, Deborah; Kotoulas, Georgios; Bargelloni, LucaThe 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.
- Genomic analysis of Sparus aurata reveals the evolutionary dynamics of sex-biased genes in a sequential hermaphrodite fishPublication . Pauletto, Marianna; Manousaki, Tereza; Ferraresso, Serena; Babbucci, Massimiliano; Tsakogiannis, Alexandros; Louro, Bruno; Vitulo, Nicola; Quoc, Viet Ha; Carraro, Roberta; Bertotto, Daniela; Franch, Rafaella; Maroso, Francesco; Aslam, Muhammad L.; Sonesson, Anna K.; Simionati, Barbara; Malacrida, Giorgio; Cestaro, Alessandro; Caberlotto, Stefano; Sarropoulou, Elena; Mylonas, Costantinos C.; Power, Deborah; Patarnello, Tomaso; Canario, Adelino; Tsigenopoulos, Costas; Bargelloni, LucaSexual dimorphism is a fascinating subject in evolutionary biology and mostly results from sex-biased expression of genes, which have been shown to evolve faster in gonochoristic species. We report here genome and sex-specific transcriptome sequencing of Sparus aurata, a sequential hermaphrodite fish. Evolutionary comparative analysis reveals that sex-biased genes in S. aurata are similar in number and function, but evolved following strikingly divergent patterns compared with gonochoristic species, showing overall slower rates because of stronger functional constraints. Fast evolution is observed only for highly ovary-biased genes due to female-specific patterns of selection that are related to the peculiar reproduction mode of S. aurata, first maturing as male, then as female. To our knowledge, these findings represent the first genome-wide analysis on sex-biased loci in a hermaphrodite vertebrate species, demonstrating how having two sexes in the same individual profoundly affects the fate of a large set of evolutionarily relevant genes.
- The first radiation hybrid map of a perch-like fish: the gilthead seabream (Sparus aurata L)Publication . Senger, Fabrice; Priat, Catherine; Hitte, Christophe; Sarropoulou, Elena; Franch, Rafaella; Geisler, Robert; Bargelloni, Luca; Power, Deborah; Galibert, F.Among Teleosts, Perciformes are the largest order of fishes and include numerous species of commercial importance. Perciformes also comprise species of primary interest for evolutionary studies and analysis of the sex determination systems and sex chromosome plasticity. Unfortunately, genomics tools and resources for Perciformes remain to be developed. Here, we report the production of a seabream whole-genome radiation hybrid (RH) panel in which quality was ascertained by the construction of a 2-Mb-resolution RH map. The map encompasses 440 markers (288 microsatellites, 82 gene-based markers, and 70 STS) suitable for linkage analysis and comparative mapping studies. Achievement of a RHpanel and a whole-genome RH map should contribute to establishing seabream as a fish model among the Perciformes and should be of importance in aquaculture for marker-assisted selection, improvement of growth performance, and disease management. Development of RH maps in a costeffective manner for other fishes with the described methodology will offer a powerful approach in aquaculture and will provide extended capabilities for comparing vertebrate genome evolution.
- Transient up- and down-regulation of expression of myosin light chain 2 and myostatin mRNA mark the changes from stratified hyperplasia to muscle fiber hypertrophy in larvae of gilthead sea bream (Sparus aurata L.)Publication . Georgiou, Stella; Alami-Durante, Helene; Power, Deborah M.; Sarropoulou, Elena; Mamuris, Zissis; Moutou, Katerina A.Hyperplasia and hypertrophy are the two mechanisms by which muscle develops and grows. We study these two mechanisms, during the early development of white muscle in Sparus aurata, by means of histology and the expression of structural and regulatory genes. A clear stage of stratified hyperplasia was identified early in the development of gilthead sea bream but ceased by 35 dph when hypertrophy took over. Mosaic recruitment of new white fibers began as soon as 60 dph. The genes mlc2a and mlc2b were expressed at various levels during the main phases of hyperplasia and hypertrophy. The genes myog and mlc2a were significantly up-regulated during the intensive stratified formation of new fibers and their expression was significantly correlated. Expression of mstn1 and igf1 increased at 35 dph, appeared to regulate the hyperplasia-to-hypertrophy transition, and may have stimulated the expression of mlc2a, mlc2b and col1a1 at the onset of mosaic hyperplasia. The up-regulation of mstn1 at transitional phases in muscle development indicates a dual regulatory role of myostatin in fish larval muscle growth.