Project description:The largest of the tuna species, Atlantic bluefin tuna, Thunnus thynnus (Linnaeus, 1758), inhabits the North Atlantic Ocean and the Mediterranean Sea and is considered to be an endangered species, largely through overfishing. Thus, the development of aquaculture practices independent of wild resources can provide an important contribution towards ensuring security and sustainability of this species in the longer-term. In order to provide a resource for ongoing studies, we have used 454 pyrosequencing technology to sequence a mixed-tissue normalized cDNA library, derived from adult individuals. Transcript sequences were used to develop a novel 15K Agilent oligo microarray for T. thynnus and comparative tissue gene expression profiles were inferred for gill, heart, liver, ovaries and testes.
Project description:This study elucidated the role of DHA-modulated genes in the development and growth of bluefin tuna (Thunnus thynnus) larvae ingesting increasing levels of DHA in their rotifer prey. The effect of feeding low, medium, and high rotifer (Brachionus rotundiformis) DHA levels (2.0, 3.6 and 10.9 mg DHA g-1 DW, respectively) was tested on 2-15 days post hatching (dph) bluefin tuna larvae. Larval DHA content markedly (P < 0.05) increased in a DHA dose-dependent manner (1.5, 3.9, 6.1 mg DHA g-1 DW larva, respectively), that was positively correlated with larval prey consumption, and growth (P < 0.05). Gene ontology enrichment analyses of DEGs demonstrated dietary DHA significantly (P < 0.05) affected different genes and biological processes at different developmental ages. The number of DHA up-regulated DEGs was highest in 10 dph larvae (408), compared to 5 (11) and 15 dph fish (34), and were mainly involved in neural and synaptic development in the brain and spinal cord. In contrast, DHA in older 15 dph larvae elicited fewer DEGs but played critical roles over a wider range of developing organs. The emerging picture underscores the importance of DHA-modulated gene expression as a driving force in bluefin tuna larval development and growth.
