Salamander blue-sensitive cones lost during metamorphosis.
The tiger salamander lives in shallow water with bright light in the aquatic phase, and in dim tunnels or caves in the terrestrial phase. In the aquatic phase, there are five types of photoreceptors--two types of rods and three types of cones. Our previous studies showed that the green rods and blue-sensitive cones contain the same visual pigment and have the same absorbance spectra; however, the green rods have a larger photon-catch area and thus have higher light sensitivity than the blue-sensitive cones. Here we show that after metamorphosis, the terrestrial salamander looses the blue-sensitive cones, while the density of the green rods increases. Moreover, the size of the green rod outer segments is increased in the terrestrial phase, compared to that in the aquatic phase. This switch from the blue-sensitive cones to the green rods may represent an adaptation to the dim light environment of the terrestrial phase.
Chen
Ying
Y
Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
Znoiko
Sergey
S
DeGrip
Willem J
WJ
Crouch
Rosalie K
RK
Ma
Jian-xing
JX
D000818:Animals; D008675:Metamorphosis, Biological; D051379:Mice; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology* / Q000528:radiation effects; D011817:Rabbits; D017949:Retinal Cone Photoreceptor Cells / Q000254:growth & development / Q000502:physiology*; D012168:Retinal Pigments; D014466:Ultraviolet Rays; D014867:Water
D012168:Retinal Pigments; D014867:Water