Abstract
Alternative splicing is a molecular mechanism that enables a single gene
to encode multiple transcripts and proteins by post-transcriptional
modification of pre-RNA molecules. Changes in the splicing scheme of
genes can lead to modifications of the transcriptome and the proteome.
This mechanism can enable organisms to respond to environmental
fluctuations. In this study, we investigated patterns of alternative
splicing in the liver of the coral reef fish Acanthochromis polyacanthus
in response to the 2016 marine heatwave on the Great Barrier Reef. The
differentially spliced (DS; n=40) genes during the onset of the heatwave
(i.e. 29.49°C or +1°C from average) were related to essential cellular
functions such as the MAPK signaling system, Ca(2+) binding and
homeostasis. With the persistence of the heatwave for a period of one
month (February to March), 21 DS genes were detected, suggesting that
acute warming during the onset of the heatwave is more influential on
alternative splicing than the continued exposure to elevated
temperatures. After the heatwave, the water temperature cooled to
~24.96°C, and fish showed differential splicing of genes
related to cyto-protection and post-damage recovery (n=26). Two-thirds
of the DS genes detected across the heatwave were also differentially
expressed, revealing that the two molecular mechanisms act together in
A. polyacanthus to cope with the acute thermal change. This study
exemplifies how splicing patterns of a coral reef fish can be modified
by marine heatwaves. Alternative splicing could therefore be a potential
mechanism to adjust cellular physiological states under thermal stress
and aid coral reef fishes in their response to more frequent acute
thermal fluctuations in upcoming decades.