Morpho-functional effects of heat stress on the gills of Antarctic T. bernacchii and C. hamatus.

Abstract The effect of increasing ocean water temperature on morpho-functional traits of Antarctic marine species is under intense attention. In this work, we evaluated the effects of acute heat stress on the gills of the Antarctic haemoglobinless Chionodraco hamatus and the red blooded Trematomus bernacchii in terms of morphology, heat shock response, antioxidant defense and NOS/NO system. We showed in both species that the exposure to high temperature (4 °C) induced structural alterations, such as epithelial lifting and oedema of secondary lamellae. By immunolocalization we also observed that HSP-90, HSP-70, Xantine Oxidase, Heme Oxigenase and NOS are expressed in both species under control conditions. After heat stress the signals increase in C. hamatus being absent/or reduced in T. bernacchii. Our preliminary results suggest a specie-specific morpho-functional response of the gills of the two Antarctic teleosts to heat stress. Highlights • Heat stress influences morphological arrangement of Antarctic fish gills. • Heat shock response and antioxidant defense in Antarctic fish gills are induced by heat stress. • Physiological response to heat stress is specie specific. • Increase of water temperature may severely affect the physiology and then survival of Antarctic stenotherm fish. [ABSTRACT FROM AUTHOR]