In the present study we have investigated the population genetic structure of albacore (Thunnus alalunga, Bonnaterre 1788) and assessed the loss of genetic diversity, likely due to overfishing, of albacore population in the North Atlantic Ocean. For this purpose, 1,331 individuals from 26 worldwide locations were analyzed by genotyping 75 novel nuclear SNPs. Our results indicated the existence of four genetically homogeneous populations delimited within the Mediterranean Sea, the Atlantic Ocean, the Indian Ocean and the Pacific Ocean. Current definition of stocks allows the sustainable management of albacore since no stock includes more than one genetic entity. In addition, short- and long-term effective population sizes were estimated for the North Atlantic Ocean albacore population, and results showed no historical decline for this population. Therefore, the genetic diversity and, consequently, the adaptive potential of this population have not been significantly affected by overfishing.
The molecular basis underlying the mechanisms at the origin of growth variation in bivalves is still poorly understood, although several genes have been described as upregulated in fast-growing individuals. In the present study, we reared mussel spat of the species Mytilus galloprovincialis under diets below the pseudofaeces threshold (BP) and above the pseudofaeces threshold (AP). After 3 months, F and S mussels from each condition were selected to obtain 4 experimental groups: FBP, SBP, FAP and SAP. We hypothesized that the nurturing conditions during the growing period would modify the molecular basis of their growth rate differences. To decipher the molecular mechanisms underlying the growth variation, the gill transcriptomes for the four mussel groups were analysed. Gene expression analysis revealed i) a low number (12) of genes differentially expressed in association with diet and ii) 117 genes differentially expressed by the fast-and slow-growing mussels. According to Biological Process GO term analysis transcriptomic differences between the F and S mussels were mainly based on the upregulation of: response to the stimulus, growth and cell activity. Regarding the KEGG terms, carbohydrate metabolism and the Krebs cycle were upregulated in F mussels, whereas biosynthetic processes were upregulated in S mussels. In accordance with their larger gill surface area and higher rates of feeding and growth, the F individuals overexpressed genes in their gill tissues, and these were involved in i) growth (insulin-like growth factors and myostatin); ii) maintenance of the structure and functioning of extracellular matrix (collagen, laminin, fibulin and decorin); iii) filtration and ciliary activity (mucin, fibrocystin, dynein and tilB homolog protein genes); iv) aerobic metabolism (citrate synthase and carbonic anhydrase); and v) the immune-system, probably in association with haemocytes. In contrast, S individuals overexpressed a different series of genes pertaining to immune system (leucine-rich repeat protein and galectin), along with genes involved in the response to cellular stress (Heat shock protein (HSP24) and metalloendopeptidase) as well as anaerobic metabolism (C4-dicarboxylate transporter). These results might suggest that S individuals would have a greater prevalence of pathogens/diseases or a higher susceptibility to the pathogens. Highlights ► Fast-and slow-growing mussel (Mytilus galloprovincialis) spat were found to differentially express 117 genes in gill tissue. ► Fast-growing mussels overexpressed genes involved in response to stimulus,growth and cell activity processes. ► Slow-growing mussels overexpressed genes involved in immune and defence processes. ► Feeding above or below the pseudofaeces production threshold did not exert a relevant effect on the gill transcriptome.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.