VERBI VEnice Research BIbliography

In regard to the research project “Analisi neurochimica e comportamentale degli effetti del cambiamento climatico e conseguente aumento della temperatura sull’attività del sistema nervoso centrale nelle specie ittiche di interesse alieutica quali spigola (Dicentratchus labrax) e orata (Sparus aurata)”, experiments under laboratory conditions on juveniles (10-15 cm, Standard Length) and post-larval stages (13-20 mm, Standard Length) of European sea bass were carried out.
We present preliminary results on swimming activity, affiliative and feeding behaviours. Moreover, results of western blot and immunofluorescence analysis on the effects of the increased temperature on cholinergic and nitrergic systems of juveniles are reported.
Behavioural tests such as prey presence, olfactive cue and object introduction were proposed to juveniles maintained at 18 and 22 °C over a period of 21 days to investigate the effects of temperature on swimming activity and affiliative behavior. Furthermore, effects of increased temperatures (19, 22, 26 °C) and prey density (Artemia nauplii) were tested on feeding behaviour of post-larval stages. Results showed that juveniles changed their swimming activity with a reduction of the time spent on bottom after 21 days at the upper temperature and the presence of peer groups in the area with olfactive cue resulted to be higher at 22 than 18 °C. Conversely, affiliative behaviour did not affect from temperature in response to object presence. Post-larval stages adjusted their feeding tactics in relation to both temperature and density, reducing predatory attacks at low temperatures and high density, and increasing predatory attacks at higher temperatures, at the expense of swimming activity.
Western blot analysis performed on the brain homogenates of the juveniles observed in behaviour tests, demonstrated that both the enzymes choline acetyltransferase (ChAT) and neuronal nitric oxide synthase (nNOS/NOS1) are expressed with a similar pattern at both 18°C and 22°C. Neither the heat-shock protein HSP70 nor the inducible isoform of nitric oxide synthase (iNOS/NOS2) were expressed at both temperatures. These results suggested that the tested increased temperature does not induce detectable stressor effects at the cellular level.