Thyroxine induces a precocial loss of ultraviolet photosensitivity in rainbow trout (Oncorhynchus mykiss, Teleostei).
Small (< 30 g) juvenile rainbow trout (Oncorhynchus mykiss) possess retinal photoreceptor mechanisms sensitive to ultraviolet (UV), short (S), middle (M) and long (L) wavelengths. During normal development, the sensitivity peak of the UV cone mechanism (360 nm) shifts towards the S-wavelengths (to an intermediate lambda max of 390 nm) until, at approx. 60 g, individuals are no longer sensitive in the UV (only a S-wavelength peak at 430 nm remains). This shift in spectral sensitivity is associated with the loss of small accessory corner cones from the retinal photoreceptor cell mosaic. Treating small (< 30 g) rainbow trout with thyroid hormone induced a precocial loss of UV photosensitivity and an associated change in the retinal photoreceptor cell mosaic, identical to the events that occur during normal development.
Browman
H I
HI
Department of Biology, University of Victoria, British Columbia, Canada.
Hawryshyn
C W
CW
D000375:Aging / Q000502:physiology; D000818:Animals; D003118:Color Perception / Q000187:drug effects*; D010786:Photoreceptor Cells / Q000502:physiology; D012160:Retina / Q000166:cytology; D012168:Retinal Pigments / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology; D013053:Spectrophotometry; D013974:Thyroxine / Q000494:pharmacology*; D014337:Trout / Q000502:physiology*; D014466:Ultraviolet Rays
D012168:Retinal Pigments; D013974:Thyroxine