Biology subjects

Le Panse, S.

Publications and source records attributed to Le Panse, S..

3 recordsLinked to original sources

bioRxiv2026

The cuticle lamellae responsible for structural coloration in red algae display common features with the metazoan extracellular matrix

Structural coloration is a physical phenomenon observed in many living organisms, including seaweeds, via the formation of highly organized nanostructures. Although the deposition of multilayer thin-film in the extracellular matrix (ECM) is a widespread characterized system, enabling light interference, to date such lamellae have only been described in the cuticle of red algae belonging to the Gigartinaceae family within macroalgae. Here, we determine the composition of the multilayered cuticle components in the model species Chondrus crispus (Rhodophyta), using genomic, transcriptomic, proteomic, metabolomic and analytical profiling of carbohydrates. The complex structural assembly revealed common features with the ECM of animals. The carbohydrate fraction consists of a complex mixture of ECM carrageenans and glycosaminoglycan-like structures. A major von Willerbrand factor A domain (VWA) protein plays a critical role for the adhesion of macromolecules, including protein-protein interactions and to sulfated polysaccharides. We propose the name of Lamellae Cohesive Protein (LCP) regarding the alternate distribution of chemically distinct constituents within the cuticle. For the first time, we identified major proteins of the algal cuticle, providing a framework for addressing the evolutionary origins of the algal cuticle biosynthesis and raise important questions regarding its role, particularly across the life cycle marked by major structural ECM modifications.

biochemistry↗

bioRxiv2025

Two Spore Types in a Marine Parasite of Dinoflagellates

Marine alveolates (MALVs) are diverse, primarily parasitic micro-eukaryotes that significantly impact marine ecosystems. The life cycles of most MALVs remain elusive and the role of sexual reproduction in these organisms is a key question that may determine their ecological success. In this study we focus on a widespread dinoflagellate parasite of bloom-forming dinoflagellates, Amoebophrya. After infection, we identified two distinct spores, differing in size, ultrastructure, swimming behavior, lifespan, gene expression, and metabolite composition. The smaller spores serve as infectious propagules, equipped with an apical complex for host invasion. They exhibit a distinct, shorter, and straighter swimming pattern, likely optimized for an extended lifespan while enhancing dispersion and chance for host encounters. Transcriptomic analysis reveals that these smaller spores are primed for efficient protein synthesis upon initiating a new infection. Conversely, the larger spores cannot infect new hosts and are characterized by the expression of meiotic genes, underscoring their sexual nature. They have a shorter lifespan, exhibit more tortuous movement, along display condensed chromosomes, signaling readiness for mating. Interestingly, infected hosts already express meiotic genes, and a single infected host only produces progeny of the same spore type, suggesting that cell fate is determined prior to spore release. Our study provides one of the first formal demonstrations of a sexually specialized cell in MALVs. Isolating compatible strains for cross-breeding and understanding how environmental conditions favor each reproductive route are the next key questions for elucidating the ecological success of MALVs in marine waters. Significance StatementMarine alveolates (MALVs) are ecologically significant parasites that impact carbon cycling, causing major disease outbreaks affecting fisheries and aquaculture, and influencing the dynamics of harmful algal blooms. Despite their diversity and wide host range, much of our knowledge comes from environmental DNA, leaving important aspects of their biology, such as their life cycles, largely unknown. This study provides the first evidence of sexual reproduction in MALVs, linking spore polymorphism to infective or sexual routes. This discovery is crucial as sexual reproduction increases genetic diversity and adaptability, aiding MALVs resilience in changing environments. Understanding MALVs reproductive strategies deepens our insight into their ecological roles and their broader impact on marine ecosystems.

microbiology↗

bioRxiv2021

Marine gregarine genomes illuminate current understanding of apicomplexan glideosome

Our current view of the evolutionary history, coding and adaptive capacities of Apicomplexa, protozoan parasites of a wide range of metazoan, is currently strongly biased toward species infecting humans, as data on early diverging apicomplexan lineages infecting invertebrates is extremely limited. Here, we characterized the genome of the marine eugregarine Porospora gigantea, intestinal parasite of Lobsters, remarkable for the macroscopic size of its vegetative feeding forms (trophozoites) and its gliding speed, the fastest so far recorded for Apicomplexa. Two highly syntenic genomes named A and B were assembled. Similar in size (~9 Mb) and coding capacity (~5300 genes), A and B genomes are 10.8% divergent at the nucleotide level, corresponding to 16-38 My in divergent time. Orthogroup analysis across 25 (proto)Apicomplexa species, including Gregarina niphandrodes, showed that A and B are highly divergent from all other known apicomplexan species, revealing an unexpected breadth of diversity. Phylogenetically these two species branch sister to Cephaloidophoroidea, and thus expand the known crustacean gregarine superfamily. The genomes were mined for genes encoding proteins necessary for gliding, a key feature of apicomplexans parasites, currently studied through the molecular model called glideosome. Sequence analysis shows that actin-related proteins and regulatory factors are strongly conserved within apicomplexans. In contrast, the predicted protein sequences of core glideosome proteins and adhesion proteins are highly variable among apicomplexan lineages, especially in gregarines. These results confirm the importance of studying gregarines to widen our biological and evolutionary view of apicomplexan species diversity, and to deepen our understanding of the molecular bases of key functions enabling parasitism, such as the glideosome.

genomics↗