Keep the lights on: regulation of sexual reproduction of the pennate diatom Seminavis robusta by irradiance intensity and spectral quality.

Master Thesis subject (30 ECTS)
Diatoms are micro-algae that live in a glass-like shell and have a fascinating life cycle. In this so-called cell size reduction-restitution cycle, every cell division results in a small decrease in size of each of the daughter cells, resulting in a gradually declining average cell size of diatom population. Below a species-specific cells size, however, sexual reproduction becomes possible, resulting in recombination of parental genomes and the establishment of the original larger cell size. The diatom Seminavis robusta is the current model system for studies of the life cycle and sexual reproduction in pennate diatoms. This species has two mating types (‘sexes’), which are morphologically identical, but behave differently during sexual reproduction. During the mating process, these two mating types were shown to communicate through the action of multiple pheromones. During this master thesis, we will attempt to determine the effect of light intensity, spectral composition and photoperiod on the mating process. In order to quantify ‘mating’, different steps in the mating process will be analysed: pheromone production, sensitivity to pheromones from the other mating type, mitotic cell division and sexual reproduction (zygote formation). First of all, we will test whether mating is light dependent and which light intensities allow sexual reproduction. Secondly, we will test which light spectra/wavelength bands (red, green, blue) are able to induce a sexual response. This may give us a hint about which photoreceptor(s) are upstream in the mating process. Depending on initial results and the time available, follow-up studies might be set up to compare expression levels of certain photoreceptors in sexual versus non-sexual cultures which have been identified in Seminavis robusta.
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Gust Bilcke ( Lieven De Veylder (
Reference Number: RP-48411