Seabass, Dicentrachus labrax. (Foto: Kefalonia Fisheries)
PORTUGALThursday, January 29, 2015, 00:20 (GMT + 9)
An international team of researchers, which involved Portuguese scientists, has succeeded in sequencing the seabass genome, identifying a genetic basis of adaptation to salinity and differentiation of the Mediterranean and Atlantic populations.
Researchers at the Centre of Marine Sciences (CCMAR) of the University of Algarve, along with scientists from the Institute of Molecular Biology Max Planck in Berlin, the Centre for Genomics of Cologne (Germany) and the University of Montpellier (France), managed to sequence and decode the genome of seabass. This made it possible to learn more about its past and to determine that the populations of the Atlantic and the Mediterranean began to diverge around 270,000 years ago.
The European seabass (Dicentrachus labrax) is distributed along the Northwest Atlantic, the Mediterranean and the Black Sea, and is one of the most important species in terms of value for fisheries and aquaculture. It breeds at sea, usually, at the mouth of rivers. Juveniles enter rivers and coastal lagoons, and can tolerate salinities ranging from almost sweet water to hyper-saline one.
Seabass genome has 800 million nucleotide pairs (the simplest DNA units), about a quarter of the human genome, distributed over 24 chromosomes. The total number of genes is estimated at 31,500, approximately 30 per cent of the human genome.
The knowledge of the genome, that is to say, the set of codes entered into the chromosomal DNA of cells, which regulates the formation and functioning of an individual, is extremely valuable in many areas of knowledge, from medicine to animal production. It allows, for example, the discovery of the causes of certain conditions, the application of technologies for genetic selection in aquaculture, or the identification of fish stocks.
The comparative endocrinology and integrative biology team of CCMAR analyzed the relationship between the genome and its physiology. Researchers found that in the seabass genome, there are several groups of genes with functions related to the control of water flow in the body, and that as a whole, their number is higher than in other fish, especially those living permanently in fresh or salt water.
While in saltwater fish tend to lose water, as they have to drink saltwater and excrete salts, which are toxic, in freshwater the opposite happens. The abundance of genes related to osmoregulation allows the bass to adapt quickly to media with very different salinities.
The study also showed that the differentiation of populations is closely linked to the DNA exchange rates that along with the distance, define the genetic diversity.
The availability of the seabass genome sequence is considered an important step in the development of various technologies, such as genetic selection, since it can help improve the productivity and sustainability of production systems.
The results of this research were published in the prestigious journal Nature Communications.