The photoactivation energy of the visual pigment in two spectrally different populations of Mysis relicta (Crustacea, Mysida)

Johan Pahlberg, Magnus Lindström, Petri Ala-Laurila, Nanna Fyhrquist-Vanni, Ari Koskelainen, Kristian Donner

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"We report the first study of the relation between the wavelength of maximum absorbance (lambda(max)) and the photoactivation energy (Ea) in invertebrate visual pigments. Two populations of the opossum shrimp Mysis relicta were compared. The two have been separated for 9,000 years and have adapted to different spectral environments (""Sea"" and ""Lake"") with porphyropsins peaking at lambda(max) = 529 nm and 554 nm, respectively. The estimation of Ea was based on measurement of temperature effects on the spectral sensitivity of the eye. In accordance with theory (Stiles in Transactions of the optical convention of the worshipful company of spectacle makers. Spectacle Makers' Co., London, 1948), relative sensitivity to long wavelengths increased with rising temperature. The estimates calculated from this effect are E-a,E-529 = 47.8 +/- 11.8 kcal/mol and E-a,E-554 = 41.5 +/- 0.7 kcal/mol (different at P < 0.01). Thus the red-shift of lambda(max) in the ""Lake"" population, correlating with the long-wavelength dominated light environment, is achieved by changes in the opsin that decrease the energy gap between the ground state and the first excited state of the chromophore. We propose that this will carry a cost in terms of increased thermal noise, and that evolutionary adaptation of the visual pigment to the light environment is directed towards maximizing the signal-to-noise ratio rather than the quantum catch."
Original languageEnglish
JournalJournal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
Pages (from-to)837-844
Number of pages8
Publication statusPublished - 2005
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 118 Biological sciences
  • 117 Geography, Environmental sciences
  • 1184 Genetics, developmental biology, physiology

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