Meeting Abstract
The colonial marine bryozoan Bugula neritina hosts an uncultured microbial symbiont that produces bioactive natural products, the bryostatins. These compounds have been shown to be ecologically relevant as they are unpalatable and deter predation on the host’s vulnerable larvae. Bryostatins are potent activators of some forms of protein kinase C (PKC), a eukaryotic signaling protein involved in many cellular processes. We observed that hosts with reduced symbiont-titers (both naturally and through antibiotic curing) had decreased fecundity compared to colonies with normal symbiont loads, suggesting that host reproduction may be dependent on the presence of the symbiont and/or symbiont-produced bryostatins. Western blot analysis indicated that bryostatin-activated PKC expression in hosts with normal symbiont titers was different from that in hosts with reduced symbiont loads. In contrast, expression of PKC forms that are not activated by bryostatins was not different in the two forms of the colonies. Taken together, this suggests that the symbiont-produced bryostatins affect the host cellular biochemistry. Host transcriptome sequencing revealed the presence of 5 PKC isoforms. Sequence analysis suggests that the isoforms from B. neritina may have different amino acid residues that could result in differing bryostatin binding affinities. As PKCs can play an important role in the regulation of reproductive processes, we suggest that the host may utilize the presence of symbiont-produced bioactive bryostatins as a cue for reproduction via PKC activation.
