DETERMINATION OF THE AVERAGE ORIENTATION OF DNA IN THE OCTOPUS SPERM ELEDONE-CIRRHOSSA THROUGH POLARIZED-LIGHT SCATTERING

The coupled-dipole approximation has been used to model polarized ligh t-scattering data obtained from the sperm of the octopus Eledone cirrh osa. Mueller scattering-matrix elements (which describe how a sample a lters the intensity and degree of polarization of scattered light) wer e measured as a function of angle. The sample was modeled as a helical fiber believed to correspond to a DNA protein complex. It was necessa ry to propose an inherent anisotropy in the polarizability of the fibe r in order to fit the data. The direction of the principle axes of the polarizability were determined by comparing the model with experiment al data. The results suggest that the 2-nm DNA fibers are perpendicula r to the thick fiber that defines the helical geometry of the octopus sperm head.