Transcriptome dynamics over a lunar month in a broadcast spawning acroporid coral

Abstract

On one night per year, at a specific point in the lunar cycle, one of the most extraordinary reproductive events on the planet unfolds as hundreds of millions of broadcast spawning corals release their trillions of gametes into the waters of the tropical seas. Each species spawns on a specific night within the lunar cycle, typically from full moon to third quarter moon, and in a specific time window after sunset. This accuracy is essential to achieve efficient fertilization in the vastness of the oceans. In this report, we use transcriptome sequencing at noon and midnight across an entire lunar cycle to explore how acroporid corals interpret lunar signals. The data were interrogated by both time-of-day-dependent and time-of-day-independent methods to identify different types of lunar cycles. Time-of-day methods found that genes associated with biological clocks and circadian processes change their diurnal cycles over the course of a synodic lunar cycle. Some genes have large differences between day and night at some lunar phases, but little or no diurnal differences at other phases. Many clock genes display an oscillation pattern indicative of phase shifts linked to the lunar cycle. Time-independent methods found that signal transduction, protein secretion and modification, cell cycle and ion transport change over the lunar timescale and peak at various phases of the moon. Together these data provide unique insights into how the moon impinges on coral transcription cycles and how lunar light may regulate circalunar timing systems and coral biology.

Seasonal temperature, the lunar cycle and diurnal rhythms interact in a combinatorial manner to modulate genomic responses to the environment in a reef‐building coral

“…There were 1,015 genes that were differentially expressed due to the interactions of the lunar phase and daily rhythms and the majority (80%) of these genes are strikingly different from those discussed above. Furthermore, these genes are largely different from those we expected and predicted in previous publications (Brady et al, ; Oldach et al, ). The majority of enriched terms identified by a GSEA of interacting genes were associated with post‐transcriptional control, including the terms mRNA processing, RNA processing, mRNA metabolic process and translation (Table , for full results see Table ).…”

“…Our objective in this study was to determine how the effects of seasonal temperature, the lunar phase and time of the day interact at a transcriptomic level in a reef‐building coral, as intersecting rhythms may enable corals to generate precisely timed behaviours. Previous studies have explored some of these changes in cnidarians over shorter time periods in a variety of scenarios, including natural temperature flux and the lunar phase (e.g., Brady, Willis, Harder, & Vize, ; Crowder et al, ; Hoadley et al, ; Kaniewska et al, ; Oldach, Workentine, Matz, Fan, & Vize, ; Reitzel et al, ), but an in‐depth sampling and transcriptomic analysis of diurnal patterns over an entire lunar month at multiple temperatures has not been attempted. We present multiple distinct analyses that uncouple how different environmental rhythms interact and identify genes and pathways that are regulated by environmental rhythms.…”

Transcriptional remodelling upon light removal in a model cnidarian: Losses and gains in gene expression

“…More recently, phylogenomic studies have shown cnidarians have many of the genes that compose the core bilaterian clockwork (Levy et al, 2007;Reitzel, Behrendt, & Tarrant, 2010;Vize, 2009), most of which are expressed in an oscillating pattern under diel lighting conditions (Brady, Snyder, & Vize, 2011;Oren et al, 2015;Reitzel et al, 2010). Additional studies, primarily with corals, have also shown that hundreds of genes are differentially expressed under light:dark (Brady et al, 2011;Ruiz-Jones & Palumbi, 2015), and lunar (Oldach, Workentine, Matz, Fan, & Vize, 2017) conditions, many of which appear to dissipate once the entraining cue is removed (Brady et al, 2011;Peres et al, 2014). It remains unclear how much of the differential gene expression is a product of a direct light response or from an endogenous oscillator (Oldach et al, 2017).…”

“…Additional studies, primarily with corals, have also shown that hundreds of genes are differentially expressed under light:dark (Brady et al, 2011;Ruiz-Jones & Palumbi, 2015), and lunar (Oldach, Workentine, Matz, Fan, & Vize, 2017) conditions, many of which appear to dissipate once the entraining cue is removed (Brady et al, 2011;Peres et al, 2014). It remains unclear how much of the differential gene expression is a product of a direct light response or from an endogenous oscillator (Oldach et al, 2017).…”

An Overview of Monthly Rhythms and Clocks

“…Two sets of regulated transcript types were identified from the quantitative RNA sequencing: one set (55 isogroups) showed diurnal expression patterns that fluctuated over the course of the lunar cycle, whereas the second set (273 isogroups) exhibited differential expression over the lunar cycle when noon and midnight sampling timepoints were combined (26). These two gene sets were largely non-overlapping, resulting in an overall detected change of transcripts over the lunar cycle of about 0.6% [Ref.…”