Diurnal oscillation of prostaglandin pathway gene expression in Skeletonema marinoi under different environmental conditions

Prostaglandins (PGs) are bioactive lipid compounds involved in physiological and environmental responses in various organisms. While their biosynthesis has been well studied in animals, recent evidence highlighted that diatoms also possess the genetic machinery for PGs synthesis; however, their function remains largely unexplored. This study investigates the diurnal oscillation of PGs pathway gene expression in Skeletonema marinoi under different environmental conditions, including variations in light intensity, temperature, and CO₂ concentration. Using two distinct strains, FE7 and FE60, we analysed the expression dynamics of three key enzymes involved in the prostaglandin biosynthesis: cyclooxygenase-1 (COX-1), microsomal prostaglandin E synthase (PTGES), and prostaglandin-H2 D-isomerase (PTGDS). Our results indicate strain-specific responses to environmental conditions that significantly altered the expression profiles of all three genes, with FE7 exhibiting greater sensitivity to temperature and light fluctuations compared to FE60. High CO₂ levels appear to positively influence the expression of COX and PTGDS and negatively those of PTGES, suggesting a potential role in modulating the production of different PGs, although the function of PGs in diatoms remains unclear. These findings provide preliminary insights into the molecular response of diatoms to environmental changes, contribute to exploring the potential role of PGs in diatoms, and highlight their potential ecological significance in phytoplankton communities, which remains speculative without functional assays and metabolite profiling by LC-MS/MS. To strengthen these findings, future studies should correlate gene expression with physiological indicators such as growth rate, cell morphology, and stress markers.