Molecular cloning of partial 14-3-3 genes in the marine sponge Hymeniacidon perleve and its role in differentiating infectious and non-infectious bacteria

Sponges (phylum Porifera) are the phylogenetically oldest metazoa and highly efficient filter feeders. In the marine ecosystem, they are unconditionally exposed to environmental stresses. Understanding the sponge-bacteria interaction is hence of both ecological and biological significance. This study investigated the specific interaction between the sponge Hymeniacidon perleve and the non-infectious bacteria, Escherichia coli and infectious bacteria, Vibrio spp. by measuring the 14-3-3 mRNA expression of H. perleve. Three partial cDNAs of 14-3-3 proteins and partial 18S RNA in H. perleve were cloned and sequenced. Using Reverse-transcription real-time PCR, the 14-3-3 mRNA expression of H. perleve was examined when exposed to three common bacteria in aquatic water-E. coli and two Vibrio spp. for different time and dosages. H. perleve could efficiently remove E. coli from the water column without self-infection; however Vibrio at higher dosages infected H. perleve. When H. perleve was exposed to E. coli (1. 1-10⁷ CFU mL^-1), V. anguillarum II (1. 2-10⁶ CFU mL^-1) and V. alginolyticus (3. 6-10⁵ CFU mL^-1) for 6 h, the 14-3-3 mRNA expression in the V. anguillarum II and V. alginolyticus groups was down-regulated by 2. 67- and 2. 36-fold, respectively. The 14-3-3 mRNA expression in the E. coli group was not significantly different. However, no clear trend was observed on the 14-3-3 transcript levels of H. perleve in response to different doses of V. anguillarum II for different time. The results demonstrated that infectious bacteria can be discriminated by 14-3-3 mRNA expression of sponge H. perleve.