A News Focus covering a trend identified at a conference: opsins (light-responsive GPCRs) are found in myriad tissues, including primitive phylogenies (incl. sea-urchins and jelly-fish). These researches have led to an increased appreciation of the variety of roles opsins may serve:
- Light-responsive roles (cf. vision) (e.g. modulating likelihood of stinging cells firing in hydra).
- Part of multi-modal sensory cells (i.e. that integrate factors including light., e.g. and taste to provide a decision making that is less defined than any clearly delineated “sense”).
- Suggestion that they may serve light-independent functions, as in mechanosensation required for hearing in Drosophila. [without further evidence, the fact of this particular case being “light-independent” seems presumptuous] or for Drosophila larvae heat-preference.
The most interesting thing to me, here, is the range of the continuum of a sense. Consider the range between an opsin in a non-dedicated cell and an entire visual system.
- Consider a human visual system, that includes multiple cortical visual areas, multi-sensory integration, specialized receptor cells per orientation, wavelength, etc. Note especially how paltry this limited summary is.
- Consider opsins in non-specialized cells, whether that be some sort of multi-sensory cell (e.g. that qualifies the environment for the organism) or as an input-modifier to some other specialized cell (e.g. to alter the likelihood of activation).
To do here: elaborate on the concept of “continuum of a sense” (and: does evolution act on Ideas?)
