title: Spectral sensitivity of guppy visual pigments reconstituted in vitro to resolve association of opsins with cone cell types.
abstract: The guppy (Poecilia reticulata) shows remarkable variation of photoreceptor cells in the retina, especially those sensitive to middle-to-long wavelengths of light. Microspectrophotometry (MSP) has revealed varying "green", "green-yellow" and "yellow" cone cells among guppies in Trinidad and Venezuela (Cumana). In the guppy genome, there are four "long-wave" opsin loci (LWS-1, -2, -3 and -4). Two LWS-1 alleles have potentially differing spectral sensitivity (LWS-1/180Ser and LWS-1/180Ala). In addition, two "middle-wave" loci (RH2-1 and -2), two "short-wave" loci (SWS2-A and -B), and a single "ultraviolet" locus (SWS1) as well as a single "rhodopsin" locus (RH1) are present. However, the absorption spectra of these photopigments have not been measured directly and the association of cell types with these opsins remains speculative. In the present study, we reconstituted these opsin photopigments in vitro. The wavelengths of maximal absorbance (λmax) were 571nm (LWS-1/180Ser), 562nm (LWS-1/180Ala), 519nm (LWS-3), 516nm (LWS-2), 516nm (RH2-1), 476nm (RH2-2), 438nm (SWS2-A), 408nm (SWS2-B), 353nm (SWS1) and 503nm (RH1). The λmax of LWS-3 is much shorter than the value expected (560nm) from the "five-sites" rule. The two LWS-1 alleles could explain difference of the reported MSP λmax values for the yellow cone class between Trinidad and Cumana guppies. Absence of the short-wave-shifted LWS-3 and the green-yellow cone in the green swordtail supports the hypothesis that this cell class of the guppy co-expresses the LWS-1 and LWS-3. These results reveal the basis of variability in the guppy visual system and provide insight into the behavior and ecology of these tropical fishes.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Bioscience BLDG Room 502, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan. Electronic address: kawamura@k.u-tokyo.ac.jp.
authors.forename: Shoji
authors.initials: S
authors.lastname: Kawamura
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Bioscience BLDG Room 502, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan; School of Marine Biosciences, Kitasato University, Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan. Electronic address: kasagi@kitasato-u.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kasagi
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Bioscience BLDG Room 502, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan. Electronic address: rainbow.from.porno@gmail.com.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kasai
authors.affiliation: Department of Ecology and Evolutionary Biology, Graduate School of Life Sciences, Tohoku University, Aramaki Aza Aoba 6-3, Aobaku, Sendai, Miyagi 980-8578, Japan. Electronic address: ayumi.tezuka@gmail.com.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Tezuka
authors.affiliation: Department of Ecology and Evolutionary Biology, Graduate School of Life Sciences, Tohoku University, Aramaki Aza Aoba 6-3, Aobaku, Sendai, Miyagi 980-8578, Japan. Electronic address: mountain-ash795@nifty.com.
authors.forename: Ayako
authors.initials: A
authors.lastname: Shoji
authors.affiliation: School of Marine Biosciences, Kitasato University, Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan. Electronic address: akiyoshi@kitasato-u.ac.jp.
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Takahashi
authors.affiliation: Department of Cellular and Molecular Biology, Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan. Electronic address: imai.hiroo.5m@kyoto-u.ac.jp.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Imai
authors.affiliation: Department of Ecology and Evolutionary Biology, Graduate School of Life Sciences, Tohoku University, Aramaki Aza Aoba 6-3, Aobaku, Sendai, Miyagi 980-8578, Japan. Electronic address: kawata@m.tohoku.ac.jp.
authors.forename: Masakado
authors.initials: M
authors.lastname: Kawata
mesh_terms: D000483:Alleles; D000818:Animals; D003118:Color Perception / Q000235:genetics / Q000502:physiology*; D055358:Cone Opsins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D011036:Poecilia / Q000235:genetics / Q000502:physiology*; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism*; D012168:Retinal Pigments / Q000502:physiology*
chemical_list: D055358:Cone Opsins; D012168:Retinal Pigments
keywords: Cone photoreceptor; Guppy; In vitro reconstitution; Opsin