Genetically Blocking the Zebrafish Pineal Clock Affects Circadian Behavior

Abstract

The master circadian clock in fish has been considered to reside in the pineal gland. This dogma is challenged, however, by the finding that most zebrafish tissues contain molecular clocks that are directly reset by light. To further examine the role of the pineal gland oscillator in the zebrafish circadian system, we generated a transgenic line in which the molecular clock is selectively blocked in the melatonin-producing cells of the pineal gland by a dominant-negative strategy. As a result, clock-controlled rhythms of melatonin production in the adult pineal gland were disrupted. Moreover, transcriptome analysis revealed that the circadian expression pattern of the majority of clock-controlled genes in the adult pineal gland is abolished. Importantly, circadian rhythms of behavior in zebrafish larvae were affected: rhythms of place preference under constant darkness were eliminated, and rhythms of locomotor activity under constant dark and constant dim light conditions were markedly attenuated. On the other hand, global peripheral molecular oscillators, as measured in whole larvae, were unaffected in this model. In conclusion, characterization of this novel transgenic model provides evidence that the molecular clock in the melatonin-producing cells of the pineal gland plays a key role, possibly as part of a multiple pacemaker system, in modulating circadian rhythms of behavior.

Resource: A multi‐species multi‐timepoint transcriptome database and webpage for the pineal gland and retina

“…In judging the utility and accuracy of the RNA‐Seq data, it should be noted that there is good agreement with data from other methods for the analysis of pineal gland and retina material, including microarray, Northern blot and qRT‐PCR as regards day/night differences 5‐13 . Accordingly, the RNA‐Seq data can be viewed as highly useful and reliable.…”

“…The pineal transcriptome has been studied for over 30 years, starting with Northern blot detection of single transcripts encoding proteins involved in melatonin synthesis, including those encoding Tph1 and Asmt (Hiomt) 1‐4 . Since then, pineal transcriptomics has spanned the development of transcriptomic assays including cDNA‐based hybridization technology, qRT‐PCR, and RNA‐Seq 5‐15 …”

Dopamine system, cerebellum, and nucleus ruber in fish and mammals

“…), neuroendocrinology (Ben‐Moshe Livne et al . ), learning and memory (Roberts et al . ; Bailey et al .…”

The not-so-long history of zebrafish research in Israel

“…This research avenue was extended to describe the entire light-induced transcriptome of the zebrafish pineal gland, resulting in functional analysis of light-induced genes and their molecular and behavioral consequences (Ben-Moshe et al, 2014a). A major current and future focus in Gothilf's lab is the importance of the central clock within the pineal gland and other brain centers, and of peripheral clocks, for the functioning of the entire circadian timing system (Ben-Moshe et al, 2016).…”