| The primary goal of this thesis was to identify new biomarkers of exposure for developing neural tissues in aquatic species. It was found that the cytokine, interleukin-1{dollar}beta{dollar} (IL-1{dollar}beta{dollar}) and its type 1 receptor are expressed in the very earliest functional neural circuits that regulate early locomotor behavior in the frog embryo. Even though IL-1{dollar}beta{dollar} is cleaved by ICE (interleukin-I{dollar}beta{dollar} converting enzyme), an enzyme that initiates apoptosis, IL-1{dollar}beta{dollar} expression is not associated with the expression of poly (ADP-ribose) polymerase (parp), a marker of apoptosis, indicating that IL-1{dollar}beta{dollar} expression is not a marker of programmed cell death in the developing frog embryo. Thus, IL-1{dollar}beta{dollar}, like other neurotrophins, may play a role in regulating cell growth or survival, or in regulating synapse formation and/or validation. Exposure of developing tadpoles to methylmercury chloride, a potent aquatic environmental contaminant, dramatically reduced IL-1{dollar}beta{dollar} levels within specific neural cell types. Thus, IL-1{dollar}beta{dollar} serves as a potential molecular biomarker of methylmercury exposure in the developing nervous system. |
