Light-responsive cryptochromes from a simple multicellular animal, the coral Acropora millepora

Area of Science:

• Marine Biology
• Chronobiology
• Molecular Evolution

Background:

• Reef-building corals exhibit synchronized mass spawning events annually.
• Lunar cycles, specifically moonlight, are known regulators of coral spawning.
• The molecular mechanisms by which corals detect moonlight remain largely unknown.

Purpose of the Study:

• To identify the molecular photoreceptors responsible for moonlight detection in corals.
• To investigate the expression patterns of identified photoreceptors in relation to light and lunar cycles.
• To understand the evolutionary significance of these photoreceptors in early-diverging animals.

Main Methods:

• Identification and characterization of cryptochrome genes (cry1 and cry2) in the coral Acropora millepora.
• Analysis of cryptochrome gene expression levels under different light conditions.
• Comparison of cry2 expression levels during full moon and new moon nights.

Main Results:

• Cryptochromes, ancient blue-light-sensing photoreceptors, were identified in Acropora millepora.
• Both cry1 and cry2 genes were found to be expressed preferentially in the presence of light.
• Expression of cry2 was significantly higher on full moon nights compared to new moon nights, suggesting a role in lunar synchronization.

Conclusions:

• Cryptochromes are key molecular components enabling corals to detect moonlight.
• These findings highlight the conserved role of cryptochromes in mediating light-dependent behaviors across diverse animal phyla.
• The study elucidates a molecular basis for the synchronization of coral mass spawning events.