
Thermal and Spectral Sensitivities of Discrete Slow Potentials in Limulus Eye
Author(s) -
Alan R. Adolph
Publication year - 1968
Publication title -
the journal of general physiology/the journal of general physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.064
H-Index - 127
eISSN - 1540-7748
pISSN - 0022-1295
DOI - 10.1085/jgp.52.3.584
Subject(s) - limulus , spectral sensitivity , biophysics , chemistry , physics , biology , optics , evolutionary biology , wavelength
The discrete, subthreshold, slow potential fluctuations (SPF's) which can be recorded intracellularly in Limulus ommatidia are sensitive to temperature and light wavelength. SPF frequency increases with increasing temperature (Q(10) about 3.5) and light intensity. The effects are additive. SPF rise and decay time decrease with increasing temperature (Q(10) between 2 and 3). There is a peak, near 520 nm, in the spectral sensitivity of SPF frequency. This peak may correspond to the wavelength of maximum absorption by rhodopsin in the ommatidia. Hydroxylamine produces a rapid, irreversible reduction of SPF frequency and amplitude perhaps owing to its action on the photopigment. The cornea and crystalline cones fluoresce (peak about 445 nm) when excited by near-ultraviolet energy (380 nm peak) and this fluorescence may influence SPF spectral sensitivity measurements. These findings suggest that the SPF's are the results of photolytic and thermolytic reactions occurring in the ommatidial visual pigments and that they have a role in the mechanisms which transduce light to electrical activity in the visual receptors.