Award: OCE-1061957

Sterols such as cholesterol are necessary for eukaryotic life. They primarily function to stabilize cell membranes; secondary functions include starting materials for steroid hormone production. The unusual sterols that are found in many marine algae and sponges are thought to play a protective role towards invertebrate predators which are unable to produce cholesterol on their own. These animals, which include ecologically important copepod zooplankton, instead obtain their cholesterol by modification of dietary phytosterols. Many marine sterols, especially those from algae that cause harmful algal blooms (HABs), cannot be transformed into cholesterol and therefore cannot support the growth and reproduction of zooplankton. Other sterols have been hypothesized to actively inhibit the metabolism of phytosterols into cholesterol; yet others are thought to act as hormone disrupters. This research investigated the metabolism of marine sterols by copepods, and their possible adverse effects on growth, molting and reproduction. Organic synthesis was used to obtain adequate amounts of pure sterols. Uptake and metabolism was investigated using sterols synthesized to contain a nonradioactive isotope (C-13), which was detected by NMR (nuclear magnetic resonance) spectroscopy. The sterols were fed to the copepods mixed with nutritious live algae (Rhodomonas). It was found that copepods were selective with regard to which sterols they take up and metabolize. Highly significant effects of sterols were seen on development in Eurytemora, but not on egg production and viability in Acartia. A sterol that potently inhibits the metabolism of phytosterols to cholesterol was identified and active analogs were synthesized. In the course of the project, sterol analysis was carried out for many organisms including HAB algae; biosynthetic aspects of marine sterol production was investigated; biomimetic studies of marine sterol production and metabolism were performed; and spectroscopic methods for the analysis of metabolic experiments were developed. Nine journal articles and 20 conference presentations were produced. Spectral data of 13C-labeled sterols are publically available (http://www.bco-dmo.org/dataset/565297). One Ph.D. student and 11 undergraduates received training. Instrumentation for Analytical Services at SUNY-ESF was purchased. Science demonstrations were given every year to students at Syracuse City Schools. Last Modified: 11/20/2017 Submitted by: Jose L Giner