# Alternative splicing in a coral during heat stress acclimation and recovery

## TL;DR

This study shows how corals use alternative splicing to respond to heat stress and recover, revealing a plant-like mechanism in these marine animals.

## Contribution

The study reveals dynamic shifts in alternative splicing in corals under heat stress, linking it to recovery and photosynthetic efficiency.

## Key findings

- At least 40% of genes in corals show dynamic alternative splicing during heat stress and recovery.
- Intron retention dominates AS in heat-stressed corals, particularly in splicing-related transcripts.
- Persistent alternative splicing after high heat stress correlates with irreversible loss of symbiont photosynthetic efficiency.

## Abstract

Climate change has caused drastic declines in corals. As sessile organisms, corals acclimate to environmental shifts through genome-wide changes in gene expression, epigenetic modifications, and alterations in microbiome composition. However, alternative splicing (AS), a conserved mechanism of stress response in many organisms, has been under-explored in corals. Using short-term acute thermal stress assays, we investigated patterns of AS in the scleractinian coral
Acropora cervicornis
during response to low (33°C), medium (35°C), and high (37°C) heat stress and subsequent overnight recovery. Our findings demonstrate reproducible dynamic shifts in AS of at least 40 percent of all genes during response to heat treatment and the recovery phase. The relative proportion of AS increased in response to heat stress and was primarily dominated by intron retention in specific classes of transcripts, including those related to splicing regulation itself. While AS returned to baseline levels post-exposure to low heat, AS persisted even after reprieve from higher levels of heat stress, which was associated with irreversible loss of photosynthetic efficiency of the symbiont. Our findings demonstrate that, although animals, corals are more plant-like in their likely usage of AS for regulating thermal stress response and recovery.