A pigment whose chemical state depends on its degree of illumination, such as those in the retina of the eye.
- ‘The difference absorption spectroscopy in both living plasmodium and cell homogenate shows that there is a photopigment which converts reversibly between red and far-red types.’
- ‘It could involve retinal photoreceptors, extraretinal photoreceptors in the pineal or elsewhere, photopigments such as cryptochromes within the retina or brain, or it might be mediated through a non-visual pathway.’
- ‘Their physiological basis is reasonably well understood; they result from the saturation or bleaching of retinal photopigments under intense or prolonged illumination.’
- ‘The green and red genes encode photopigments that respond to different, overlapping regions in the middle-to-long wavelength spectrum and are adjacent to each other on the X chromosome.’
- ‘There is no physiological evidence for a third photopigment sensitive to blue wavelengths.’
We take a look at several popular, though confusing, punctuation marks.