Vertebrate behavior is strongly influenced by light. Light receptors, encoded by functional opsin proteins, are present inside the vertebrate brain and peripheral tissues. This expression feature is present from fishes to human and appears to be particularly prominent in diurnal vertebrates. Despite their conserved widespread occurrence, the nonvisual functions of opsins are still largely enigmatic. This is even more apparent when considering the high number of opsins. Teleosts possess around 40 opsin genes, present from young developmental stages to adulthood. Many of these opsins have been shown to function as light receptors. This raises the question of whether this large number might mainly reflect functional redundancy or rather maximally enables teleosts to optimally use the complex light information present under water. We focus on tmt-opsin1b and tmt-opsin2, c-opsins with ancestral-type sequence features, conserved across several vertebrate phyla, expressed with partly similar expression in non-rod, non-cone, non-retinal-ganglion-cell brain tissues and with a similar spectral sensitivity. The characterization of the single mutants revealed age- and light-dependent behavioral changes, as well as an impact on the levels of the preprohormone sst1b and the voltage-gated sodium channel subunit scn12aa. The amount of daytime rest is affected independently of the eyes, pineal organ, and circadian clock in tmt-opsin1b mutants. We further focused on daytime behavior and the molecular changes in tmt-opsin1b/2 double mutants, and found that—despite their similar expression and spectral features—these opsins interact in part nonadditively. Specifically, double mutants complement molecular and behavioral phenotypes observed in single mutants in a partly age-dependent fashion. Our work provides a starting point to disentangle the highly complex interactions of vertebrate nonvisual opsins, suggesting that tmt-opsin-expressing cells together with other visual and nonvisual opsins provide detailed light information to the organism for behavioral fine-tuning. This work also provides a stepping stone to unravel how vertebrate species with conserved opsins, but living in different ecological niches, respond to similar light cues and how human-generated artificial light might impact on behavioral processes in natural environments.
One Sentence SummaryTwo 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. AbstractVertebrate 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-visualOpsins, suggesting that tmt-opsin-expressing cells together with other Opsins provide detailed light information to the organism for behavioral fine-tuning.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.