Additional microsatellites for Sparus aurata and cross-species amplification within the Sparidae family

Six new microsatellite loci were isolated and characterized in 32 individuals from a farm population of gilthead seabream (Sparus aurata). Expected heterozygosity at all loci was high, ranging from 0.835 to 0.958 with between 10 and 27 alleles per locus. A multiplex polymerase chain reaction protocol was developed using four of the loci. Cross-species amplification of the loci was tested in six species of the Sparidae family and four loci were successfully amplified in two or more related species

Left/right asymmetric collective migration of parapineal cells is mediated by focal FGF signaling activity in leading cells

International audienceThe ability of cells to collectively interpret surrounding environmental signals underpins their capacity to coordinate their migrationin various contexts, including embryonic development and cancer metastasis. One tractable model for studying collectivemigration is the parapineal, a left-sided group of neurons that arises from bilaterally positioned precursors that undergo acollective migration to the left side of the brain. In zebrafish, the migration of these cells requires Fgf8 and, in this study, we resolvehow FGF signaling correlates with—and impacts the migratory dynamics of—the parapineal cell collective. The temporal and spatialdynamics of an FGF reporter transgene reveal that FGF signaling is activated in only few parapineal cells usually located at theleading edge of the parapineal during its migration. Overexpressing a constitutively active Fgf receptor compromises parapinealmigration in wild-type embryos, while it partially restores both parapineal migration and mosaic expression of the FGF reportertransgene in fgf8−/− mutant embryos. Focal activation of FGF signaling in few parapineal cells is sufficient to promote the migrationof the whole parapineal collective. Finally, we show that asymmetric Nodal signaling contributes to the restriction and leftwards biasof FGF pathway activation. Our data indicate that the first overt morphological asymmetry in the zebrafish brain is promoted byFGF pathway activation in cells that lead the collective migration of the parapineal to the left. This study shows that cell-state differencesin FGF signaling in front versus rear cells is required to promote migration in a model of FGF-dependent collective migration

A genetic linkage map of the hermaphrodite teleost fish Sparus aurata L.

The 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