Butenolide Exerts Antifouling Effects on the Bryozoan Bugula neritina through Activating NO/cGMP Signaling Pathway

Marine biofouling, a persistent and multifaceted challenge within the maritime realm, generates substantial economic and noneconomic loss and damage to the marine industry every year. Butenolide (BU) is a promising antifouling compound derived from a marine microbe. Although being highly effective against several major biofoulers such as the bryozoan Bugula neritina, the molecular mechanisms underlying its inhibition of B. neritina larval settlement remain largely unknown. Based on the evidence from comparative transcriptome data, we investigated the expression changes of key genes related to the nitric oxide signaling pathway upon BU treatment via quantitative real-time PCR. Results showed that the expression levels of these genes were significantly up-regulated, suggesting the nitric oxide-cyclic guanosine monophosphate (NO/cGMP) signaling pathway was stimulated in response to BU. In addition, a co-incubation assay using BU and various specific inhibitors targeting the NO pathway showed that these inhibitors could rescue the antifouling effects of BU. These findings further supported the proposition that BU inhibited bryozoan larval settlement by activating the NO/cGMP pathway. Overall, our results provided novel insights into the molecular mechanism of BU against B. neritina, which could be crucial for the development of environmentally benign antifouling strategies.