Transcriptome analyses of Acanthamoeba sp., Effects of photosynthetic traits of bacterial prey on predatory amoebae.

Photosynthesis generates reactive oxygen species (ROS) under light condition which damages the cell. Therefore, when unicellular transparent organisms feed on phototrophs in the daytime, light reaches the photosystems of the engulfed prey which probably generates higher levels of ROS inside the predator cells. In order to understand how unicellular predators cope with the photosynthetic oxidative stress, we examined the change in transcriptome of nonphotosynthetic predatory amoeba (Acanthamoeba sp.) feeding on a cyanobacterium (Synechococcus elongatus PCC 7942), upon illumination. As a negative control, S. elongates, which reduced their photosynthetic pigments under a nitrogen-depleted condition and thus reduced photosynthetic ability, was used. In addition, Acanthamoeba sp. was also grown in an organic medium without bacterial prey to examine effects of light stimulus on the amoeba, which is not related to photosynthetic traits of prey.