Deep-sea and pelagic rod visual pigments identified in the mysticete whales

The New Jersey Center for Science, Technology & Mathematics, Kean University, Union, New Jersey, USA.
Visual Neuroscience (Impact Factor: 2.21). 03/2012; 29(2):95-103. DOI: 10.1017/S0952523812000107
Source: PubMed


Our current understanding of the spectral sensitivities of the mysticete whale rod-based visual pigments is based on two species, the gray whale (Eschrichtius robustus) and the humpback whale (Megaptera novaeangliae) possessing absorbance maxima determined from difference spectra to be 492 and 497 nm, respectively. These absorbance maxima values are blueshifted relative to those from typical terrestrial mammals (≈500 nm) but are redshifted when compared to those identified in the odontocetes (479-484 nm). Although these mysticete species represent two of the four mysticete families, they do not fully represent the mysticete whales in terms of foraging strategy and underwater photic environments where foraging occurs. In order to better understand the spectral sensitivities of the mysticete whale rod visual pigments, we have examined the rod opsin genes from 11 mysticete species and their associated amino acid substitutions. Based on the amino acids occurring at positions 83, 292, and 299 along with the directly determined dark spectra from expressed odontocete and mysticete rod visual pigments, we have determined that the majority of mysticete whales possess deep-sea and pelagic like rod visual pigments with absorbance maxima between 479 and 484 nm. Finally, we have defined the five amino acid substitution events that determine the resulting absorbance spectra and associated absorbance maxima for the mysticete whale rod visual pigments examined here.

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    • "The exceptions were Chelidonichthys kumu (292A/299A), and, as previous stated, N. celidotus (292S/299S). The combination 83 N/292A/299S was detected in the rhodopsin sequence of mysticete whales with a λ max value of 493 nm (Bischoff et al. 2012). Therefore, it is likely that the combination 292A/299S detected here in most of the epipelagic species is related to an adaptation to longer wavelengths of light in comparison with the deeper species. "
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