Nitrogen-Dependent Regulation of Nitrate Reductase in Coral Symbioses.

Nitrate reductase in coral symbionts is regulated by nitrogen availability, light, and photosynthesis, enabling rapid and reversible nitrate assimilation in nutrient-variable environments.

• Why it matters: Understanding how nitrate reductase is controlled in coral symbionts is crucial because it influences nitrogen homeostasis in nutrient-poor reef ecosystems, impacting coral health and resilience.
• What they did: The study characterized nitrate reductase protein and gene expression in cultured Symbiodiniaceae under varying nitrogen and light conditions, including in hospite coral samples, and used pharmacological inhibition to explore regulation mechanisms.
• The result: Findings show nitrate reductase acts as a substrate-induced enzyme with post-transcriptional regulation, allowing corals to adapt nitrate assimilation rapidly when nitrogen sources fluctuate.