Abstract
Effects of ultraviolet rays and temperature upon drag lines of mature spider Argiope amoena were studied by the electron spin resonance ESR method. The relative signal intensity as a measure of decomposition of protein molecules increased at room temperature with irradiation time of ultraviolet rays. This shows that the protein molecules constituting drag lines were decomposed by the ultraviolet rays. The signal intensity without ultraviolet rays decreased gradually to 100°C, above 100°C increased, and then showed a peak at about 170°C. The peak may come from the superposition of two factors such as an increase in radicals ascribed to chemical decomposition at high temperatures and a decrease in radicals ascribed to the enhancement of molecular motion of silk protein.
