Global discovery and characterization of small non-coding RNAs in marine microalgae

Area of Science:

• Marine biology
• Molecular biology
• Oceanography

Background:

• Marine phytoplankton, including diatoms and coccolithophores, are crucial for global carbon fixation and marine food webs.
• These organisms play key roles in biogeochemical cycles and carbon sequestration through blooms and biomineralization.
• Understanding gene regulation via short non-coding RNAs (sRNAs) is vital in these ecologically significant phytoplankton.

Purpose of the Study:

• To investigate the presence and regulation of sRNAs in diatoms and coccolithophores.
• To identify novel regulatory mechanisms in key marine primary producers.

Main Methods:

• Sequencing of short RNA transcriptomes from two diatom species (Thalassiosira pseudonana, Fragilariopsis cylindrus).
• Validation of sRNAs using Northern blot analysis.
• Comparative analysis with the coccolithophore Emiliania huxleyi.

Main Results:

• Canonical microRNAs (miRNAs) were not detected in diatoms.
• The most abundant sRNAs in diatoms were repeat-associated sRNAs and tRNA-derived sRNAs.
• tRNA-derived sRNAs were also found in E. huxleyi and were induced by environmental stresses (e.g., iron limitation, alkaline pH) in diatoms, being particularly abundant in F. cylindrus.

Conclusions:

• This study presents the first experimental evidence of sRNAs in marine microalgae.
• Diatoms appear to lack canonical miRNAs but utilize prominent tRNA-derived sRNAs.
• tRNA-derived sRNAs are significant in diatoms and coccolithophores and likely contribute to environmental acclimation.