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Copepods can induce changes in proteomes and neurotoxin profiles in two mediterranean strains of Alexandrium pacificum
 

Copepods can induce changes in proteomes and neurotoxin profiles in two mediterranean strains of Alexandrium pacificum

Roua Jeridi, Thierry Balliau, Véronique Savar, Jérôme Ghersy, Christian Martino, Mohamed Laabir, Amandine M. N. Caruana Natacha Jean
Harmful Algae
2026
: https://doi.org/10.1016/j.hal.2026.103146
copepods, proteomics, Harmful Algal Blooms, DEP, Differentially Expressed Protein, DTT, DiThioThreitol, FDR, False Discovery Rate, HAB, Harmful Algal Bloom, HILIC-MS/MS, Hydrophilic Interaction LIquid Chromatography in tandem, LC/FLD, Liquid Chromatography/FLuorescence Detector, MS/MS, Tandem mass spectrometry, Paralytic Shellfish Toxins, PCA, Principal Component Analysis, PCOX, Post-Column OXidation, PSP, Paralytic Shellfish Poisoning, PST, Paralytic Shellfish Toxin, ROS, Reactive Oxygen Species, SPE, Solid Phase Extraction, stress proteins. ANOVA, ANalysis Of VAriance, STX, Saxitoxin, TEF, Toxicity Equivalency Factor, XIC,eXtracted Ion Chromatography
We studied total proteomes and paralytic shellfish toxin (PST) profiles in two mediterranean strains of the dinoflagellate Alexandrium pacificum exposed to the copepods Acartia tonsa or Oithona nana. Although the total PST contents remained unchanged in the presence of copepods, some modifications were observed in the PST profiles, principally in A. pacificum SG C10-3 exposed to O. nana. Compared to A. pacificum TAR C5-4F, A. pacificum SG C10-3 produced higher total PSTs and C2 toxin in presence of O. nana; it produced NeoSTX and higher amounts of C1, C3 and GTX1 toxins in presence of both copepods. A. pacificum SG C10-3 produced higher levels of C2 and C4 toxins in the presence of O. nana than in that of A. tonsa, whereas A. pacificum TAR C5-4F slightly increased GTX5 in presence of O. nana compared to control. Compared to A. pacificum TAR C5-4F, A. pacificum SG C10-3 has modified further its proteome by 9.6 %, particularly when incubated with O. nana, this cyclopoid inducing higher global protein contents in A. pacificum SG C10-3 than in A. pacificum TAR C5-4F. The A. pacificum SG C10-3 modified proteome was mostly down-regulated in presence of O. nana, whereas it was primarily up-regulated in that of A. tonsa, perhaps due to differences in perception of the respective copepods signals. This could be confirmed by the signal transduction proteins down-regulated by A. pacificum SG C10-3 in presence of O. nana, whereas these were up-regulated in that of A. tonsa, this can lead to the different proteomic responses that we observed. Finally, proteomic changes observed in the A. pacificum strains in presence of the copepods could be associated with regulation of certain metabolic pathways: carbohydrate/lipid metabolism could be more sollicitated by A. pacificum SG C10-3 in these conditions, while this could be photosynthesis for A. pacificum TAR C5-4F.

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