T6 PM Immune and Endocrine Disruption: Detection and Implication
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 324-326

(RIC-1117-821459) A model system for examining the developmental immunotoxicology of environmental contaminants in fish.

Hunt, L¹, Rice, C¹, ¹ CIET/Biological Sciences, Clemson University, Clemson, USA

ABSTRACT- At least in mammals, the developing immune system is a sensitive target organ for environmental contaminants. Little is known about the sensitivity of the developing immune system of aquatic organisms to xenobiotics. The transparent embryo and well-characterized developmental stages of the mummichog, Fundulus heteroclitus, make this organism an ideal model for studying the developmental immunotoxicology of contaminants in drugs. Contributing to the utility of the mummichog model is the emerging molecular and immunological tool box of reagents now available for measuring immune responses in mummichogs. We identified three critical points in the development of the immune system of mummichogs, now referred to as early-, mid-, and late-stage organogenesis, that serve as critical points for exposing mummichog embryos to model contaminants. Fertilized eggs were treated as individual embryos in 96-well plates with three levels of PCB-126 for 24 hrs during the early stage of organogenesis, then either snap frozen for molecular and protein analysis, or grown out for 3 months in 1 L tanks designed for growing zebra fish larvae (Aquaneering, Inc., San Diego, CA.). Recombination activating gene-1 (RAG-1), an enzyme critical for B-cell receptor recombination and antibody production, was partially sequenced to develop a PCR probe for quantifying RAG-1 expression in developing mummichog embryos. Twenty ng/L PCB-126 shut down expression of the RAG-1 gene, while inducing CYP1A gene expression. Both lysozyme and IgM protein levels were suppressed by 20 ng/L PCB-126. Suppressed RAG-1 expression should result in impaired antibody production and antibody responses later in development, a hypothesis that will be tested in individuals at the end of the 3 month grow-out period now in progress. To our knowledge, this is the first model of developmental immunotoxicology in fish and the first intensive examination of the effects of embryological exposure to contaminants on immune functions later in life.

Key words: developmental immunotoxicology, RAG-1, mummichog, antibody response