[Polarization and spectral sensitivity of individual house cricket photoreceptors]

Polarization and spectral sensitivities of single photoreceptors of a house-cricket were measured. Morphologically, the cricket rhabdom is a symmetric model in which the polarization sensitivity of a single photoreceptor is equal to the dichroic ratio of a single microvillus. The spectral sensitivity curves of all the photoreceptors measured (24 cells) appeared to be similar and showed the main peak of sensitivity at 500 nm and the secondary peak at 360 nm--the situation reminding properties of vertebrate rhodopsin. The polarization sensitivity measured was equal to 2.28 +/- 0.85 (mean for 70 cells +/- standard deviation). This value is in favour of small preferential orientation of the dipole moments of the pigment molecules along the microvillar axes.