Cold-adapted Euplotes pheromones

Species of Euplotes rely on diffusible signal proteins (pheromones) to promote their mitotic reproduction and mating (sexual) phenomena. Two of these pheromones have recently been structurally characterized from an Antarctic species, E. nobilii, and their amino acid sequences (of 52 and 60 residues, and eight cysteines) were found to be closely related with those of E. raikovi pheromones of temperate waters. However, they diverge in physicochemical properties, such as a reduced hydrophobicity, an increased solvent accessibility and improved backbone flexibility, which together reflect their close adaptation to cold.