Untitled

Funder

Organizational Unit

Publications

Photoperiodic Modulation of Circadian Clock and Reproductive Axis Gene Expression in the Pre-Pubertal European Sea Bass Brain

Publication . Martins, Rute S. T.; Gomez, Ana; Zanuy, Silvia; Carrillo, Manuel; Canario, Adelino V. M.

The acquisition of reproductive competence requires the activation of the brain-pituitary-gonad (BPG) axis, which in most vertebrates, including fishes, is initiated by changes in photoperiod. In the European sea bass long-term exposure to continuous light (LL) alters the rhythm of reproductive hormones, delays spermatogenesis and reduces the incidence of precocious males. In contrast, an early shift from long to short photoperiod (AP) accelerates spermatogenesis. However, how photoperiod affects key genes in the brain to trigger the onset of puberty is still largely unknown. Here, we investigated if the integration of the light stimulus by clock proteins is sufficient to activate key genes that trigger the BPG axis in the European sea bass. We found that the clock genes clock, npas2, bmal1 and the BPG genes gnrh, kiss and kissr share conserved transcription factor frameworks in their promoters, suggesting co-regulation. Other gene promoters of the BGP axis were also predicted to be co-regulated by the same frameworks. Co-regulation was confirmed through gene expression analysis of brains from males exposed to LL or AP photoperiod compared to natural conditions: LL fish had suppressed gnrh1, kiss2, galr1b and esr1, while AP fish had stimulated npas2, gnrh1, gnrh2, kiss2, kiss1rb and galr1b compared to NP. It is concluded that fish exposed to different photoperiods present significant expression differences in some clock and reproductive axis related genes well before the first detectable endocrine and morphological responses of the BPG axis.

2015-12Journal article

Open access

Vertebrate SLRP family evolution and the subfunctionalization of osteoglycin gene duplicates in teleost fish

Publication . Costa, Rita; Brazona, Rute Sofia Tavares Martins; Capilla, E.; Anjos, Liliana; Power, Deborah

Background Osteoglycin (OGN, a.k.a. mimecan) belongs to cluster III of the small leucine-rich proteoglycans (SLRP) of the extracellular matrix (ECM). In vertebrates OGN is a characteristic ECM protein of bone. In the present study we explore the evolution of SLRP III and OGN in teleosts that have a skeleton adapted to an aquatic environment. Results The SLRP gene family has been conserved since the separation of chondrichthyes and osteichthyes. Few gene duplicates of the SLRP III family exist even in the teleosts that experienced a specific whole genome duplication. One exception is ogn for which duplicate copies were identified in fish genomes. The ogn promoter sequence and in vitro mesenchymal stem cell (MSC) cultures suggest the duplicate ogn genes acquired divergent functions. In gilthead sea bream (Sparus aurata) ogn1 was up-regulated during osteoblast and myocyte differentiation in vitro, while ogn2 was severely down-regulated during bone-derived MSCs differentiation into adipocytes in vitro. Conclusions Overall, the phylogenetic analysis indicates that the SLRP III family in vertebrates has been under conservative evolutionary pressure. The retention of the ogn gene duplicates in teleosts was linked with the acquisition of different functions. The acquisition by OGN of functions other than that of a bone ECM protein occurred early in the vertebrate lineage.

2018-12-13Journal article

Open access

SuperSAGE digital expression analysis of differential growth rate in a European sea bass population

Publication . Louro, Bruno; Martins, Rute S.T.; Pinto, Patricia IS; Reinhardt, Richard; de Koning, Dirk-Jan; Canario, Adelino; Power, Deborah

One of the goals of the aquaculture industry is to understand and control growth associated traits through selective breeding. In the present study the molecular basis of growth heterogeneity in the European sea bass (Dicentrarchus labrax) was addressed. To establish growth heterogeneity in a group of hatchery bred sea bass individuals were tagged and their specific growth rates (SGR) determined at monthly intervals. Gene expression in the brain, liver and white muscle from fish with the most divergent sustained SGR (6 individuals of the first and last quartile) was assessed using SuperSAGE (Serial Analysis Gene Expression) combined with next generation SOLiD4 sequencing. A total of approx. 11 million edited tags (26 bp), on average 2 million tags per SAGE library, that represented 47.071 unique transcripts were identified. Comparison of transcripts in fish with high and low SGR yielded 344, 698 and 601 differently expressed tags (0.01% false discovery rate and 4-fold change) in brain, liver and muscle, respectively. The tags were mapped onto the sea bass genome and approximately one third of the tags could be assigned to annotated genes. Pathway enrichment analysis revealed in liver, muscle and brain intricate gene expression changes in endocrine regulatory pathways involved in growth, metabolic and the stress axis, underlying divergent SGR in sea bass.

2019Journal article

Open access