TMT-Opsins differentially modulate medaka brain function in a context-dependent manner

Abstract

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.

Functional, molecular and morphological heterogeneity of superficial interneurons in the larval zebrafish tectum

“…Extraretinal opsins are found in the zebrafish brain (Fischer et al, 2013), and deep brain photoreceptors have been shown to influence light‐mediated behavior (Fernandes et al, 2012; Fischer et al, 2013; Fontinha et al, 2020). Moreover, the specific SIN marker LCR RH2 ‐RH2‐2:GFP was generated by linking GFP to the green cone opsin enhancer.…”

Spherical arena reveals optokinetic response tuning to stimulus location, size, and frequency across entire visual field of larval zebrafish

“…Genetic zebrafish variants with altered photoreceptor distributions would thus be a valuable tool for further studies. Recent studies suggest that melanopsin-expressing ganglion cells also contribute to form vision (59,60), and melanopsins as well as a plethora of other opsins are expressed in the zebrafish retina and brain (61,62). It is therefore possible that photoreception via opsin-expressing neurons in the inner retina contributes to zebrafish OKR as well.…”