Dark-processes following photoconversion of butterfly rhodopsins
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Photoconversion of rhodopsin to metarhodopsin by a short actinic flash creates photochemical changes in the absorbance spectrum of the butterfly rhabdom, which are measurable as changes in the reflectance spectrum of the intact eye. The difference spectrum relaxes in the dark, but changes considerably in shape when doing so. The positive peak caused by the accumulation of metarhodopsin relaxes to zero much faster than the negative peak caused by the loss of rhodopsin. The positive peak actually undershoots zero absorbance-difference before its final asymptotic approach to zero, whereas the negative peak approaches zero monotonically.
The entire temporal evolution of difference spectra can be quantitatively reproduced by only assuming different kinetics for the dark-processes of metarhodopsin's decay and of rhodopsin's recovery. A consequence of this analysis is that no long-lived, coloured intermediates can be detected in the rhabdom other than metarhodopsin.
Metarhodopsin's decay is well approximated by a first-order process, but has a time-constant that depends strongly on temperature. Examples are 71 min at 12.5‡ C, 18 min at 23‡ C, and 4 min at 26.5‡ C.
Rhodopsin's recovery is kinetically complex. The rate of recovery shortly after a small photoconversion is somewhat slower than the rate for metarhodopsin's decay. At later times, or for a large photoconversion, rhodopsin's recovery is very much slower than metarhodopsin's decay.
Key wordsInsect photoreceptors Visual pigments Unstable metarhodopsin Dark regeneration Bleaching
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- Bernard GD (1977) Noninvasive microspectrophotometry of butterfly photoreceptors. J Opt Soc Am 67: 1362Google Scholar
- Bernard GD (1979) Red-absorbing visual pigment of butterflies. Science 203: 1125–1127Google Scholar
- Bernard GD (1983) Bleaching of rhabdoms in eyes of intact butterflies. Science 219: 69–71Google Scholar
- Bernard GD, Stavenga DG (1979) Spectral sensitivities of retinular cells measured in intact, living flies by an optical method. J Comp Physiol 134: 95–107Google Scholar
- Bruno MS, Barnes SN, Goldsmith TH (1977) The visual pigment and visual cycle of the lobster, Homarus. J Comp Physiol 120: 123–142Google Scholar
- Cronin TW, Goldsmith TH (1982) Photosensitivity spectrum of crayfish rhodopsin measured using fluorescence of metarhodopsin. J Gen Physiol 79: 313–323Google Scholar
- Dartnall HJA (1953) The interpretation of spectral sensitivity curves. Br Med Bull 9: 24–30Google Scholar
- Ebrey TG, Honig B (1977) New wavelength dependent visual pigment nomograms. Vision Res 17: 147–151Google Scholar
- Franceschini N, Kirschfeld K (1971) Les phénomènes de pseueo-pupille dans l'oiel composé de Drosophila. Kybernetik 9: 159–182Google Scholar
- Goldsmith TH (1972) The natural history of invertebrate visual pigments. In: Dartnall HJA (ed) Handbook of sensory physiology, vol VII/1. Springer, Berlin Heidelberg New York, pp 685–719Google Scholar
- Hamdorf K (1977) The physiology of invertebrate visual pigments. In: Autrum H (ed) Handbook of sensory physiology, vol VII/6A. Springer, Berlin Heidelberg New York, pp 145–224Google Scholar
- Kingsolver JG, Moffat RJ (1982) Thermoregulation and the determinants of heat transfer in Colias butterflies. Oecologia (Berlin) 53: 27–33Google Scholar
- Langer H, Schlect P, Schwemer J (1982) Microspectrophotometric investigation of insect visual pigments. In: Packer L (ed) Visual pigments and purple membranes (Methods in enzymology, part H, vol 81, Academic Press, New York, pp 729–741Google Scholar
- Miller WH (1979) Ocular optical filtering. In: Autrum H (ed) Handbook of Sensory Physiology, vol VII/6A. Springer, Berlin Heidelberg New York, pp 69–143Google Scholar
- Miller WH, Bernard GD (1968) Butterfly glow. J Ultrastruct Res 24: 286–294Google Scholar
- Ribi WA (1978) Ultrastructure and migration of screening pigments in the retina of Pieris rapae. Cell Tissue Res 191: 57–73Google Scholar
- Schwemer J (1969) Der Sehfarbstoff von Eledone moschata und seine Umsetzungen in der lebenden Netzhaut. Z Vergl Physiol 62: 121–152Google Scholar
- Stavenga DG, Zantema A, Kuiper JW (1973) Rhodopsin processes and the function of the pupil mechanism in flies. In: Langer H (ed) Biochemistry and physiology of visual pigments. Springer, Berlin Heidelberg New York, pp 175–180Google Scholar
- Stavenga DG (1975a) Visual adaptation in butterflies. Nature (London) 254: 435–437Google Scholar
- Stavenga DG (1975b) Dark regeneration of invertebrate visual pigments. In: Snyder AW, Menzel R (eds) Photoreceptor optics. Springer, Berlin Heidelberg New York, pp 290–295Google Scholar
- Stavenga DG, Numan JAJ, Tinbergen J, Kuiper JW (1977) Insect pupil mechanisms. II. Pigment migration in retinula cells of butterflies. J Comp Physiol 113: 73–93Google Scholar
- Watt WB (1968) Adaptive significance of pigment polymorphisms in Colias butterflies. I. Variation of melanin pigment in relation to thermoregulation. Evolution 22: 437–458Google Scholar