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- W199393497 abstract "The photoreceptor cells of invertebrate animals differ from those of vertebrates in morphology and physiology. Our present knowledge of the different structures and transduction mechanisms of the two animal groups is described. In invertebrates, rhodopsin is converted by light into a meta-rhodopsin which is thermally stable and is usually re-isomerized by light. In contrast, photoisomerization in vertebrates leads to dissociation of the chromophore from opsin, and a metabolic process is necessary to regenerate rhodopsin. The electrical signals of visual excitation have opposite character in vertebrates and invertebrates: the vertebrate photoreceptor cell is hyperpolarized because of a decrease in conductance and invertebrate photoreceptors are depolarized owing to an increase in conductance. Single-photon-evoked excitatory events, which are believed to be a result of concerted action (the opening in invertebrates and the closing in vertebrates) of many light-modulated cation channels, are very different in terms of size and time course of photoreceptors for invertebrates and vertebrates. In invertebrates, the single-photon events (bumps) produced under identical conditions vary greatly in delay (latency), time course and size. The multiphoton response to brighter stimuli is several times as long as a response evoked by a single photon. The single-photon response of vertebrates has a standard size, a standard latency and a standard time course, all three parameters showing relatively small variations. Responses to flashes containing several photons have a shape and time scale that are similar to the single-photon-evoked events, varying only by an amplitude scaling factor, but not in latency and time course. In both vertebrate and invertebrate photoreceptors the single-photon-evoked events become smaller (in size) and faster owing to light adaptation. Calcium is mainly involved in these adaptation phenomena. All light adaptation in vertebrates is primarily, or perhaps exclusively, attributable to calcium feedback. In invertebrates, cyclic AMP (cAMP) is apparently another controller of sensitivity in dark adaptation. The interaction of photoexcited rhodopsin with a G-protein is similar in both vertebrate and invertebrate photoreceptors. However, these G-proteins activate different photoreceptor enzymes (phosphodiesterases): phospholipase C in invertebrates and cGMP phosphodiesterase in vertebrates. In the photoreceptors of vertebrates light leads to a rapid hydrolysis of cGMP which results in closing of cation channels. At present, the identity of the internal terminal messenger in invertebrate photoreceptors is still unsolved. Calcium and cGMP are probable candidates. Several turn-off mechanisms are known, coming into action at different positions of the transduction cascade. Phosphorylation of activated rhodopsin and subsequent binding of arrestin is the decisive mechanism in vertebrate photoreceptors. This mechanism seems to be similar in invertebrate photoreceptor cells." @default.
- W199393497 created "2016-06-24" @default.
- W199393497 creator A5019150462 @default.
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- W199393497 date "1990-11-01" @default.
- W199393497 modified "2023-09-27" @default.
- W199393497 title "New trends in photobiology" @default.
- W199393497 cites W1015587828 @default.
- W199393497 cites W111988334 @default.
- W199393497 cites W1481153288 @default.
- W199393497 cites W1543217424 @default.
- W199393497 cites W1544814976 @default.
- W199393497 cites W1566050966 @default.
- W199393497 cites W1570762629 @default.
- W199393497 cites W1586666367 @default.
- W199393497 cites W1590951841 @default.
- W199393497 cites W1595948784 @default.
- W199393497 cites W1603066709 @default.
- W199393497 cites W1629857769 @default.
- W199393497 cites W1653853239 @default.
- W199393497 cites W1667685119 @default.
- W199393497 cites W1700760551 @default.
- W199393497 cites W1819679577 @default.
- W199393497 cites W187222491 @default.
- W199393497 cites W1945745853 @default.
- W199393497 cites W1963653553 @default.
- W199393497 cites W1964135715 @default.
- W199393497 cites W1964674454 @default.
- W199393497 cites W1965325003 @default.
- W199393497 cites W1971716310 @default.
- W199393497 cites W1973326681 @default.
- W199393497 cites W1973610140 @default.
- W199393497 cites W1974064985 @default.
- W199393497 cites W1974191268 @default.
- W199393497 cites W1974978517 @default.
- W199393497 cites W1977379050 @default.
- W199393497 cites W1977460665 @default.
- W199393497 cites W1977571897 @default.
- W199393497 cites W1977970108 @default.
- W199393497 cites W1978789853 @default.
- W199393497 cites W1979356484 @default.
- W199393497 cites W1979643377 @default.
- W199393497 cites W1980322773 @default.
- W199393497 cites W1980548134 @default.
- W199393497 cites W1980862726 @default.
- W199393497 cites W1981365824 @default.
- W199393497 cites W1983877651 @default.
- W199393497 cites W1985163705 @default.
- W199393497 cites W1986553306 @default.
- W199393497 cites W1987155732 @default.
- W199393497 cites W1987347647 @default.
- W199393497 cites W1987718946 @default.
- W199393497 cites W1987929481 @default.
- W199393497 cites W1990218841 @default.
- W199393497 cites W1990927579 @default.
- W199393497 cites W1991298303 @default.
- W199393497 cites W1992004763 @default.
- W199393497 cites W1993668198 @default.
- W199393497 cites W1993755473 @default.
- W199393497 cites W1996438246 @default.
- W199393497 cites W1997110018 @default.
- W199393497 cites W1999170605 @default.
- W199393497 cites W2003563916 @default.
- W199393497 cites W2003742541 @default.
- W199393497 cites W2004196814 @default.
- W199393497 cites W2004697473 @default.
- W199393497 cites W2004899273 @default.
- W199393497 cites W2006842412 @default.
- W199393497 cites W2007354147 @default.
- W199393497 cites W2007606079 @default.
- W199393497 cites W2008788879 @default.
- W199393497 cites W2008968750 @default.
- W199393497 cites W2009316430 @default.
- W199393497 cites W2010194803 @default.
- W199393497 cites W2010415181 @default.
- W199393497 cites W2010921442 @default.
- W199393497 cites W2011693061 @default.
- W199393497 cites W2016537683 @default.
- W199393497 cites W2016542329 @default.
- W199393497 cites W2016969524 @default.
- W199393497 cites W2017598654 @default.
- W199393497 cites W2018524991 @default.
- W199393497 cites W2019447882 @default.
- W199393497 cites W2019669546 @default.
- W199393497 cites W2019875735 @default.
- W199393497 cites W2020007950 @default.
- W199393497 cites W2020317085 @default.
- W199393497 cites W2021149824 @default.
- W199393497 cites W2021576673 @default.
- W199393497 cites W2022909393 @default.
- W199393497 cites W2025364863 @default.
- W199393497 cites W2025942131 @default.
- W199393497 cites W2026042821 @default.
- W199393497 cites W2026390924 @default.
- W199393497 cites W2028851412 @default.
- W199393497 cites W2029232890 @default.
- W199393497 cites W2029347326 @default.