b'Synergism of Sulfur and Systemic Fungicides to Treat Sclerotium rolfsiiAlexander Gomez and Gaylyn W FarmerSponsor: Dr. Emily Cantonwine, Department of BiologyRecent studies have shown that mixing sulfur and systemic fungicides have a synergetic effect on disease management for some fungi. Synergistic action occurs when two or more fungicides produce a greater action together than expected. This study will see if this effect occurs for the fungus Sclerotium rolfsii, an important pathogen of peanut and other crops. Two systemic fungicides with sulfur or without sulfur will be evaluated, tebuconazole and azoxystrobin. Treatments will also include an untreated control and a sulfur only treatment. The treatments will be created using fungicide amended media with plugs of S. rolfsii transferred onto each plate. Fungal growth will be measured after three days. Synergism will be detected if the reduction in growth by the mixture treatments are greater than reduction in growth in the sulfur and systemic fungicide alone treatments. If synergistic activity is observed, experiments will be conducted to see if the effect occurs in the peanut field. If so, this will improve management of S. rolfsii and help extend in activity of systemic fungicidal products.Modulation of Cardiac Performance in the Blue Crab Callinectes sapidusLaura Ramirez, Magnolia G. Rodriguez Mendoza and Kahleel E. GuerrierSponsor: Dr. Timothy Fort, Department of Biology Blue crabs are poikilotherms that are exposed to a range of environmental temperatures due to their distribution (western Atlantic from Cape Cod to Argentina) and seasonal variations. Changes in temperature pose physiological challenges to poikilotherms. The heart of the blue crab, Callinectes sapidus, is neurogenic. The 9 neuron cardiac ganglion (CG), embedded within the wall of the heart, sets the basic rhythm and drives contractions of the heart. The CG and cardiac musculature can be modulated neuronally (via cardioregulatory fibers) and hormonally (via the pericardial organs [PO]). Two of the neurohormones released from the PO into the hemolymph are the biogenic amines, Dopamine (DA) and Serotonin (5HT). Here we present preliminary data on the modulation of cardiac performance by biogenic amines and temperature. Contraction amplitude decreases and contraction frequency increases with increasing experimental temperatures. DA and 5HT induced both positive chronotropic and inotropic effects in isolated working heart preparations at concentrations consistent with neurohormonal signaling. The positive chronotropic and inotropic effects of DA and 5HT appear to be temperature independent.20'