Electroretinographic evaluation and SWS1 opsin gene expression in the vision of juvenile longtooth grouper Epinephelus bruneus (Bloch, 1793)

Abstract

Electroretinogram (ERG) recordings and short-wave sensitive 1 (SWS1: ultraviolet sensitive) opsin gene expression data were obtained to investigate the spectral sensitivity and scotopic luminous sensitivity of juvenile longtooth groupers Epinephelus bruneus. The ERG showed broad spectral sensitivity (350–600 nm; λmax = 560 nm approx.) in the photopic condition. The scotopic vision was maximally sensitive to green light (λmax = 500 nm approx.). SWS1 opsin gene expression was measured in the eyes using the reverse transcription–polymerase chain reaction method (RT-PCR). This indicated that the ultraviolet sensitivity in the photopic spectral response curve (360 nm approx.) was attributable to SWS1 opsin absorption. The contribution of the β-band cannot rule out. Scotopic luminous sensitivity in this species similar to that in other coastal fishes and higher than that in pelagic fishes. These results suggest that the vision of a juvenile longtooth grouper is adapted to conditions in shallow coastal waters.