Effects of salinity on life history traits and fatty acid-binding proteins in the marine rotifer, Brachionus plicatilis

We present a comprehensive analysis of the impact of increased salinity on Brachionus plicatilis, focusing on growth, reproduction, behavior, and fatty acid-binding protein (FABP) gene expression. We discovered delays in maturation and potential disruptions in the reproductive process under conditions of high salinity. Experiments demonstrated that while the total number of B. plicatilis offspring remained unchanged across different salinity levels, the peak daily offspring count was delayed, and the pace of reproduction was slower at higher salinity. However, the pre-reproductive and reproductive periods at 35 practical saline units were extended, contributing to longer timeframes to produce all offspring, but the post-reproductive period was shortened, thus balancing the overall lifespan across different salinity levels. Furthermore, we noted that high salinity impedes the growth of B. plicatilis and causes alterations in swimming behavior. Our findings also demonstrated five pairs of FABPs within the three Brachionus species (B. plicatilis, B. rotundiformis, and B. koreanus) with distinctive sequences. Phylogenetic analysis revealed that Brachionus FABPs diverged before the speciation of the three species and were found outside the vertebrate FABP group. The results contribute to our understanding of the impact of high salinity on B. plicatilis and the evolutionary positioning of FABPs in these species, while also highlighting the need for further research into specific FABP differentiation and expression patterns in Brachionus species.