A rapid electrical potential, which we have named the M-potential, can be obtained from the Drosophila eye using a high energy flash stimulus. The potential can be elicited from the normal fly, but it is especially prominent in the mutant norp AP12 (a phototransduction mutant), particularly if the eye color pigments are genetically removed from the eye. Several lines of evidence suggest that the M-potential arises from photoexcitation of long-lived metarhodopsin. Photoexcitation of rhodopsin does not produce a comparable potential. The spectral sensitivity of the M-potential peaks at about 575 nm. The M-potential pigment (metarhodopsin) can be shown to photoconvert back and forth with a "silent pigment(s)" absorbing maximally at about 485 nm. The silent pigment presumably is rhodopsin. These results support the recent spectrophotometric findings that dipteran metarhodopsin absorbs at much longer wavelengths than rhodopsin. The M-potential probably is related to the photoproduct component of the early receptor potential (ERP). Two major differences between the M-potential and the classical ERP are: (a) Drosophila rhodopsin does not produce a rapid photoresponse, and (b) an anesthetized or freshly sacrificed animal does not yield the M-potential. As in the case of the ERP, the M-potential appears to be a response associated with a particular state of the fly visual pigment. Therefore, it should be useful in in vivo investigations of the fly visual pigment, about which little is known.
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1 June 1974
Article|
June 01 1974
Fast Electrical Potential from a Long-Lived, Long-Wavelength Photoproduct of Fly Visual Pigment
William L. Pak,
William L. Pak
From the Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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Kellie J. Lidington
Kellie J. Lidington
From the Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
Search for other works by this author on:
William L. Pak
From the Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
Kellie J. Lidington
From the Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
Received:
October 05 1973
Online ISSN: 1540-7748
Print ISSN: 0022-1295
1974
J Gen Physiol (1974) 63 (6): 740–756.
Article history
Received:
October 05 1973
Citation
William L. Pak, Kellie J. Lidington; Fast Electrical Potential from a Long-Lived, Long-Wavelength Photoproduct of Fly Visual Pigment . J Gen Physiol 1 June 1974; 63 (6): 740–756. doi: https://doi.org/10.1085/jgp.63.6.740
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