Abstract
Vertebrate behavior is strongly influenced by light. Photoreceptors, encoded by Opsins, are present inside the vertebrate brain and peripheral tissues. Their non-visual functions are largely enigmatic.
We focus on tmt-opsin1b and 2, c-Opsins with ancestral-type sequence features, conserved across several vertebrate phyla and with partly similar expression. Their loss-of-function mutations differentially modulate medakafish behavior in a context-dependent manner. Specifically, differences in light conditions have differential effects depending on age and frequency of the light changes, part of which are mediated by TMT-Opsin1b acting outside the eyes, while the pre-pro-hormone sst1b is regulated by daylength via TMT-opsin1b in an eye-dependent manner. Analyses of tmt-opsin1b;tmt-opsin2 double mutants reveals partial complementation of single mutant behavioral and molecular phenotypes.
Our work starts to disentangle the highly complex interactions of vertebrate non-visual Opsins, suggesting that tmt-opsin-expressing cells together with other Opsins provide detailed light information to the organism for behavioral fine-tuning.
One Sentence Summary Two medakafish non-visual c-type Opsins interact non-additively, impacting the levels of the preprohormone sst1b, as well as the voltage-gated sodium channel subunit scn12aa and- at least in part independently of the eyes- the amount of larval day-time rest.