Temperature responsiveness of gilthead sea bream bone: an in vitro and in vivo approach

Abstract

This study aimed to characterize the molecules involved in osteogenesis in seabream and establish using in vitro/in vivo approaches the responsiveness of selected key genes to temperature. The impact of a temperature drop from 23 to 13ºC was evaluated in juvenile fish thermally imprinted during embryogenesis. Both, in vitro/in vivo, Fib1a, appeared important in the first stages of bone formation, and Col1A1, ON and OP, in regulating matrix production and mineralization. OCN mRNA levels were up-regulated in the final larval stages when mineralization was more intense. Moreover, temperature-dependent differential gene expression was observed, with lower transcript levels in the larvae at 18ºC relative to those at 22ºC, suggesting bone formation was enhanced in the latter group. Results revealed that thermal imprinting affected the long-term regulation of osteogenesis. Specifically, juveniles under the low and low-to-high-temperature regimes had reduced levels of OCN when challenged, indicative of impaired bone development. In contrast, gene expression in fish from the high and high-to-low-temperature treatments was unchanged, suggesting imprinting may have a protective effect. Overall, the present study revealed that thermal imprinting modulates bone development in seabream larvae, and demonstrated the utility of the in vitro MSC culture as a reliable tool to investigate fish osteogenesis.