Purchase this article with an account.
J. Pahlberg, M. Jokela–Maatta, M. Lindstrom, K. Donner; The Effect of Screening Pigments on Spectral Sensitivity in the Opossum Shrimp (Mysis relicta) . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2262.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To study the role of screening pigments on the relation between visual–pigment absorbance spectra and electrophysiologically measured whole–eye sensitivity spectra of the opossum shrimp (Mysis relicta). Methods: Absorbance spectra of visual pigments were recorded by single–cell microspectrophotometry (MSP) and fitted with standard visual–pigment templates. Spectral sensitivity was measured by electroretinogram (ERG) recording in the intact eye. The logarithmic difference between the visual–pigment templates and the ERG spectra was calculated and compared to non–visual (screening or protective) pigments recorded from aggregates surrounding the rhabdoms in the MSP preparations. Results: The shapes of the absorbance spectra indicated that the pigments were pure porphyropsins (A2 pigments). Eye sensitivity spectra were flatter in shape and their peaks were relatively red–shifted. At the longest wavelengths (> 700nm), however, ERG spectra converge with the visual–pigment template. We found that the difference between absorbance and sensitivity spectra can be explained by the combined effect of three types of screening pigments surrounding the rhabdoms. Conclusions: In several crustaceans, including our present model species, there is a significant difference between the absorbance spectra of the visual pigments and electrophysiologically recorded sensitivity spectra of the eye. In the case studied, the discrepancy can be explained by the screening action of different non–visual pigments demonstrably present in the eye. Screening will necessarily carry a cost in terms of reduced quantum catch even if the sensitivity spectrum would seem to better match the illumination spectrum than does the visual–pigment absorbance spectrum.
This PDF is available to Subscribers Only