Ivan Chevere-Colon

Advisor: Antony O.W. Stretton

Ph.D. Abstract: Neuropeptide study in Ascaris by immunocytochemical and molecular biology methods

In order to identify the cells that contain and presumably secrete individual Ascaris FMRFamide-like (AF) peptides, we raised monoclonal and polyclonal antibodies specific to peptides AF17, AF 19, and AF9. Each of these antibodies was monospecific: it did not show detectable cross-reactivity with any of the other known AF peptides. Immunocytochemical experiments using each of these antibodies showed that in Ascaris the immunoreactivity is located in a small subset of neurons; this subset is distinct and different for each antibody. The afp genes that encode the AF peptides are organized differently with respect to the types and numbers of peptides that each produces. The afp-1 gene (Edison et al., Peptides 18: 929-935, 1997) encodes six different, but highly sequence-related AF peptides. The afp-2 gene encodes only a single peptide, AF5. In this thesis, the afp-3 gene was partially sequenced. It encodes at least three copies of peptide AF8 and none of the other AF peptides. We conclude that the AF peptides in Ascaris are expressed in different subsets of cells and are encoded by several different genes.