Cone photoreceptor diversity in the retinas of fruit bats (megachiroptera).
Older studies have claimed that bats including the Megachiroptera (fruit bats or flying foxes) have pure-rod retinas and possess no cone photoreceptors. We have determined the presence and the population densities of spectral cone types in six megachiropteran species belonging to four genera: Pteropus rufus, P. niger, P. rodricensis, Rousettus madagascariensis, Eidolon dupreanum, and Epomophorus gambianus. Spectral cone types and rods were assessed immunocytochemically with opsin-specific antibodies. All six species have rod-dominated retinas but possess significant cone populations. The high rod densities (range 350,000-800,000/mm(2), depending on species and retinal location) provide good scotopic sensitivity in these predominantly nocturnal animals. With the cones (density range 1,300-11,000/mm(2), corresponding to 0.25-0.6% of the photoreceptors, depending on species and retinal location) the retinas also possess the prerequisite for vision at photopic light levels. The three Pteropus species have two spectral cone types, a majority of middle-to-long-wave sensitive (L-) cones, and a minority of short-wave sensitive (S-) cones, indicating the potential for dichromatic color vision. This conforms to the pattern found in most mammals. In contrast, Rousettus, Eidolon and Epomophorus have L-cones but completely lack S-cones, indicating cone monochromacy and color blindness. The discussion relates these findings to the visual behavior of fruit bats.
Müller
Brigitte
B
Max Planck Institute for Brain Research, Frankfurt am Main, Germany. bmueller@mpih-frankfurt.mpg.de
Goodman
Steven M
SM
Peichl
Leo
L
D000818:Animals; D002685:Chiroptera / Q000033:anatomy & histology*; D012160:Retina / Q000166:cytology* / Q000378:metabolism; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism*; D017299:Rod Opsins / Q000378:metabolism; D013045:Species Specificity
D017299:Rod Opsins