Searching for a mate : pheromone-directed movement of the benthic diatom Seminavis robusta

Diatoms are species-rich microalgae that often have a unique life cycle with vegetative cell size reduction followed by size restoration through sexual reproduction of two mating types (MT+ and MT-). In the marine benthic diatom Seminavis robusta, mate-finding is mediated by an l-proline-derived diketopiperazine, a pheromone produced by the attracting mating type (MT-). Here, we investigate the movement patterns of cells of the opposite mating type (MT+) exposed to a pheromone gradient, using video monitoring and statistical modeling. We report that cells of the migrating mating type (MT+) respond to pheromone gradients by simultaneous chemotaxis and chemokinesis. Changes in movement behavior enable MT+ cells to locate the direction of the pheromone source and to maximize their encounter rate towards it.

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