Biological relevance and intent of the experiment: Given their abundance in the oceans and the exceptional adaptive capacities that make them capable of colonizing the most disparate habitats, diatoms constitute a group of microalgae of considerable ecological importance. This experiment aims to provide a molecular characterization of sexual reproduction for the diatom Pseudo-nitzschia multistriata, in relation to the consumption of nutrients and the impact on the marine ecosystem, by exploring the gene expression changes occurring at different time points in the cells involved in the process. Experimental workflow: Cell cultures of P. multistriata belonging to opposite mating types (MT- and MT+) were grown in 12L/12D cycles at 18°C under normal light conditions (60 uE) and crossed at a final cell density of 20.000 cells/ml using half volume from each MT. Samples for transcriptomic analyses were collected at three time points for sexually reproducing cells (1 hour: T1, 24 hours: T2 and 120 hours: T3), and at one time point (24 hours: T2) for parental monocultures grown in parallel as control condition.