Ultraviolet-sensitive vision in long-lived birds.
Long-term exposure to ultraviolet (UV) light generates substantial damage, and in mammals, visual sensitivity to UV is restricted to short-lived diurnal rodents and certain marsupials. In humans, the cornea and lens absorb all UV-A and most of the terrestrial UV-B radiation, preventing the reactive and damaging shorter wavelengths from reaching the retina. This is not the case in certain species of long-lived diurnal birds, which possess UV-sensitive (UVS) visual pigments, maximally sensitive below 400 nm. The Order Psittaciformes contains some of the longest lived bird species, and the two species examined so far have been shown to possess UVS pigments. The objective of this study was to investigate the prevalence of UVS pigments across long-lived parrots, macaws and cockatoos, and therefore assess whether they need to cope with the accumulated effects of exposure to UV-A and UV-B over a long period of time. Sequences from the SWS1 opsin gene revealed that all 14 species investigated possess a key substitution that has been shown to determine a UVS pigment. Furthermore, in vitro regeneration data, and lens transparency, corroborate the molecular findings of UV sensitivity. Our findings thus support the claim that the Psittaciformes are the only avian Order in which UVS pigments are ubiquitous, and indicate that these long-lived birds have UV sensitivity, despite the risks of photodamage.
Carvalho
Livia S
LS
UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK.
Knott
Ben
B
Berg
Mathew L
ML
Bennett
Andrew T D
AT
Hunt
David M
DM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016000:Cluster Analysis; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D008969:Molecular Sequence Data; D055355:Opsins / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D011563:Psittaciformes / Q000502:physiology*; D017422:Sequence Analysis, DNA; D013021:South Australia; D013045:Species Specificity; D014466:Ultraviolet Rays; D014785:Vision, Ocular / Q000502:physiology* / Q000528:radiation effects
D017931:DNA Primers; D018076:DNA, Complementary; D055355:Opsins