Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
The role of herbivorous fishes in maintaining low macroalgal cover was evaluated on coral reefs on several reef sites from Guadeloupe, either protected or not. Grazing by herbivorous fishes was assessed on different algal facies using fish-bite counts. Algal consumption by fish was estimated as well as algal production. Bite counts revealed that herbivorous fishes feed preferentially on algal turf and avoid brown macroalgae. The algal consumption varied between 0.4 and 2.8 g m days and was higher inside marine protected areas than outside. Comparison with algal production revealed that herbivorous fishes did not succeed in regulating algal growth. The insufficient number of grazers may lead to the dominance of stable assemblages of macroalgae on coral reefs, preventing the recovery of reef into previous coral-dominated ecosystems.
ISSN: 1438-387X

hal-00533405
https://hal.archives-ouvertes.fr/hal-00533405
https://hal.archives-ouvertes.fr/hal-00533405/document
https://hal.archives-ouvertes.fr/hal-00533405/file/PEER_stage2_10.1007%252Fs10152-009-0177-4.pdf
DOI : 10.1007/s10152-009-0177-4

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The brown algal genus Padina (Dictyotales, Phaeophyceae) is distributed worldwide in tropical and temperate seas. Global species diversity and distribution ranges, however, remain largely unknown. Species-level diversity was reassessed using DNA-based, algorithmic species delineation techniques based on cox3 and rbcL sequence data from 221 specimens collected worldwide. This resulted in estimates ranging from 39 to 61 putative species (ESUs), depending on the technique as well as the locus. We discuss the merits, potential pitfalls, and evolutionary and biogeographic significance of algorithmic species delineation. We unveil patterns whereby ESUs are in all but one case restricted to either the Atlantic or Indo-Pacific Ocean. Within ocean basins we find evidence for the vast majority of ESUs to be confined to a single marine realm. Exceptions, whereby ESUs span up to three realms, are located in the Indo-Pacific Ocean. Patterns of range-restricted species likely arise by repeated founder events and subsequent peripatric speciation, hypothesized to dominate speciation mechanisms for coastal marine organisms in the Indo-Pacific. Using a three-gene (cox3, psaA and rbcL), relaxed molecular clock phylogenetic analysis we estimated divergence times, providing a historical framework to interpret biogeographic patterns.
ISSN: 0022-3646

hal-01545323
https://hal.archives-ouvertes.fr/hal-01545323
DOI : 10.1111/jpy.12027

Éditeur(s) : HAL CCSD
Résumé : International audience
Fucoxanthin is a carotenoid present in brown micro-and macro algae, that induces apoptosis or autophagy in cancer cells grown in vitro. In vivo studies confirmed its interest as a natural anticancer compound, as it exerts antitumoral, antimetastatic and antiangiogenic activities in animal models. Studies focused on the pharmacology of fucoxanthin in cancer cells and tumors have revealed that it affects a wide panel of cellular, molecular and tissular processes, suggesting that its biological activity may be related in part to a nonspecific integration in cell membranes, and possible interaction with lipid rafts. Thus, preliminary data confirming this interaction of fucoxanthin with lipid rafts were obtained in mast cells and hepatoma WIF-B9 cells. We here discuss this hypothesis, in view of the critical function of lipid rafts in cancer cell survival, invasivity and communication with the tumoral microenvironment.
ISSN: 2141-2294

hal-01391001
https://hal.archives-ouvertes.fr/hal-01391001
https://hal.archives-ouvertes.fr/hal-01391001/document
https://hal.archives-ouvertes.fr/hal-01391001/file/could-fucoxanthin-interaction-with-lipid-rafts-mediate-its-cytotoxicity-incancer-cells-.pdf
DOI : 10.4172/jomr.1000144