Search Results (2)

Arthrospira platensis extract is incorporated into sunscreen formulations for its beneficial and UV-protective properties on cultured human cells. However, its effects have not yet been assessed on non-target organisms such as endosymbiotic microalgae in coral tissue. To evaluate its effects, we investigated the photophysiology of the cultured dinoflagellate Cladocopium goreaui using PAM fluorometry (RLC, OJIP) after a 5-day exposure to different extract concentrations. Our results show that, through a hormetic effect, A. platensis enhances the performance index (Pi_Abs) at 0.018 mg L⁻¹ by increasing the number of active reaction centers (RC/ABS) and improving electron transfer efficiency (φEo, ψEo) along the electron transport chain. Conversely, beyond 108.8 mg L⁻¹, negative impacts appear on PSII, increasing the apparent antenna size (ABS/RC) and impairing the oxygen-evolving complex (K-peak), ultimately reducing the maximum relative electron transport rate (rETR_m). This relative toxicity, obtained only for the highest concentrations, supports its potential incorporation into cosmetic formulations. This study contributes to improving the ecotoxicity assessment of cosmetic products on non-target organisms. Full article

Dinoflagellates of the family Symbiodiniaceae are crucial photosymbionts in corals and other marine organisms. Of these, Cladocopium goreaui is one of the most dominant symbiont species in the Indo-Pacific. Here, we present an improved genome assembly of C. goreaui combining new long-read sequence data with previously generated short-read data. Incorporating new full-length transcripts to guide gene prediction, the C. goreaui genome (1.2 Gb) exhibits a high extent of completeness (82.4% based on BUSCO protein recovery) and better resolution of repetitive sequence regions; 45,322 gene models were predicted, and 327 putative, topologically associated domains of the chromosomes were identified. Comparison with other Symbiodiniaceae genomes revealed a prevalence of repeats and duplicated genes in C. goreaui, and lineage-specific genes indicating functional innovation. Incorporating 2,841,408 protein sequences from 96 taxonomically diverse eukaryotes and representative prokaryotes in a phylogenomic approach, we assessed the evolutionary history of C. goreaui genes. Of the 5246 phylogenetic trees inferred from homologous protein sets containing two or more phyla, 35–36% have putatively originated via horizontal gene transfer (HGT), predominantly (19–23%) via an ancestral Archaeplastida lineage implicated in the endosymbiotic origin of plastids: 10–11% are of green algal origin, including genes encoding photosynthetic functions. Our results demonstrate the utility of long-read sequence data in resolving structural features of a dinoflagellate genome, and highlight how genetic transfer has shaped genome evolution of a facultative symbiont, and more broadly of dinoflagellates. Full article