Transcriptome profile of GH/IGF system shows an early tissue-specific differentiation and hypoxia responsive genes in sea bream

Resumen del trabajo presentado en el XIII Congress of the Iberian Association of Comparative Endocrinology, celebrado en modalidad virtual del 16 al 17 de septiembre de 2021.
A customized PCR-array of 28 selected genes was used for assessing the simultaneous expression of the Gh/Igf system and related markers of muscle growth, and lipid and energy metabolism during early life stages of gilthead sea bream (60-127 days posthatching). Also, transcriptional reprogramming by mild hypoxia was assessed in fingerling fish with different history trajectories on O2 availability during the same time window. In normoxic fish, the expression of almost all the genes in the array varied over time with a prompted liver and muscle tissue-specific differentiation, which revealed temporal changes in the relative expression of markers of the full gilthead sea bream repertoire of Gh receptors, Igfs and Igf-binding proteins. Results supported a different contribution through development of ghr and igf subtypes on the type of action of GH via systemic or direct effects at the local tissue level. This was extensive to Igfbp1/2/4 and Igfbp3/5/6 clades that clearly evolved through development as hepatic and muscle Igfbp subtypes, respectively. This trade-off is however very plastic to cope changes in the environment, and ghr1 and igfbp1/3/4/5 emerged as hypoxic imprinting genes during critical early developmental windows leading to recognize individuals with different history trajectories of O2 availability and metabolic capabilities later in life. How this knowledge can contribute to establish robust criteria of larval and juvenile fish quality requires more research, though changes in the expression and the quotient expression ratio of duplicated ghr/igf/ igfbp genes can serve as a measure of developmental progression and metabolic disturbances of the offspring. Besides, growth, health and well-being also depend on the daily synchronization of endogenous biological rhythms, and the expression of selected genes from antiphase clusters can serve to find synchrony indicators of gilthead sea bream during early life.
This work was supported by National (Bream-AquaINTECH, RTI2018-094128-B-I00) and European (PerformFISH, H2020-SFS-2016-2017; 727610) projects.