MicroRNA Applications in Marine Biology

Abstract

MicroRNAs (miRNAs) are single-stranded, short (~ 22 nt) non-coding RNAs that control gene expression in most metazoan taxa. These vital post-transcriptional regulators are emerging as a novel class of relatively well-conserved biomarkers useful to molecular ecologists working on non-model marine organisms. The purpose of this review is to provide researchers with a brief background on miRNAs and to explore recent applications in marine biology. MiRNA datasets have been broadly employed in studies concerning commercially important species (oysters and crustaceans), phylogenetics (particularly deep evolutionary splits), and environmental stressor responses (temperature and salinity). Most progress has been made in the characterization of cnidarian miRNAs and bivalve and crustacean immune-related miRNAs. The use of miRNAs in phylogenetics is still under debate due to the secondary loss of miRNAs in some lineages, but they have been successfully applied in the resolution of deep evolutionary splits. Finally, miRNAs have been investigated in abiotic stress responses, but data interpretation is limited by the high number of species-specific miRNAs detected in these studies. Improvements in miRNA database curation and functional annotation should provide more confidence in their use. Due to their evolutionary conservation, resilience to degradation, and amenable bioinformatics workflows, miRNAs are a powerful molecular tool in marine genomics. MiRNA investigations regarding environmental stress response will be particularly useful due to their potential to reveal physiological alterations and disease. Thus, they may be ultimately utilized as bio-indicators of environmental health.