b'Modulation of the Callinectes sapidus Cardiac System by SerotoninJeanie F. Hall and Gena L. CodySponsor: Dr. Timothy J. Fort, Department of BiologyThe heart of the blue crab, Callinectes sapidus, is a simple central pattern generator-effector system. The 9 neuron cardiac ganglion (CG), embedded within the cardiac muscle, sets the basic rhythm of the heart. The activity of the CG is modulated by both neuronal (via cardioregulatory fibers) and hormonal signals (via the pericardial organs). Gamma aminobutyric acid (GABA) and dopamine have previously been identified as the neurotransmitters of two of the three cardioregulatory fibers and are both present in the pericardial organs (PO). In this study, we used immunohistochemistry to determine the distribution of the biogenic amine, Serotonin (5-Hydroxytryptamine) in the central nervous system of the blue crab. Serotonin-like immunoreactivity (5-HT-li) was observed in cells in the brain and thoracic ganglion and in fibers within the brain-thoracic connectives. 5-HT-li fibers projected via segmental nerve 1 towards the PO. Multiple branching fine caliber fibers and varicosities expressed 5-HT-li within the PO. 5-HT-li was not observed in the dorsal nerve or CG. Serotonin induced both positive chronotropic and inotropic effects in isolated heart preparations at concentrations consistent with hormonal signaling. The 5-HT-li distribution and cardiac responsiveness to serotonin both suggest a possible cardiomodulatory role for serotonin in the heart of the blue crab.Comparing Spore Collection Techniques of Nothopassalora PersonataGaylyn W. FarmerSponsor: Dr. Emily Cantonwine, Department of BiologyNothopassalora personata is a fungal pathogen that causes late leaf spot of peanut. Because this fungus does not sporulate on media, laboratory inoculation studies rely on spores collected from field-infected peanuts as the inoculum source. Recent studies have shown that inoculum solutions prepared using a vacuum spore collector do not germinate as well as inoculum solutions prepared using sporulating leaf spots that have been cut from peanut tissues and dried. An experiment was conducted to see if the poor germination rates were caused by the vacuum process or by a toxic effect of the dissolvable capsule that the vacuumed spores are stored in. Treatments included a negative control inoculum solution (vacuumed spores prepared in a dissolvable capsule), a positive control solution (spores from dried leaf spots prepared in a microfuge tube), a solution prepared in the dissolvable capsule using spores from dried leaf spots, and a solution prepared in a microfuge tube using vacuumed spores. The results demonstrated a higher percent germination of N. personata spores from both unvacuumed treatments versus the ones that were vacuumed. There was no effect from the dissolvable capsule. These results suggest that the vacuum process reduces spore health.19'