PARENT SESSION
PT5 - Fate & Effects of Metals: Aquatic Biology
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P625) Cadmium induces apoptosis in reproductive tissues of topsmelt (Atherinops affinis).
Rose, Wendy*,1, Cherr, Gary1, Anderson, Susan1, 1 UC Davis Bodega Marine Laboratory, Bodega Bay, CA, USA
ABSTRACT- Cadmium (Cd), a pollutant of aquatic environments worldwide, interferes with vitellogenesis and impairs the reproductive success of fishes. However, mechanisms of reproductive impairment by Cd remain unclear. We hypothesize that Cd causes widespread apoptosis (programmed cell death) in the liver of fishes, which may reduce vitellogenin-producing hepatocytes, and alter oocyte development. Initially, we used the TUNEL assay, which measures DNA cleavage, to examine apoptosis in the chinook salmon embryonic cell line (CHSE-214) following exposure to Cd and several common aquatic pollutants. Cadmium(1 
g/ml) caused apoptosis at 100 fold levels lower than copper (100 g/ml), diazinon (none detected), and etoposide (100 g/ml) following 96 hour exposure periods. To assess the in vivo induction of apoptosis in liver and ovaries of fish, juvenile topsmelt (Atherinops affinis) were aqueously exposed to Cd (1 ppb - 10 ppm) for 96 hours. Apoptosis was detected in the liver (10 and 100 ppb Cd) and ovary (100 ppb Cd) of topsmelt at Cd concentrations considerably lower than the lethal concentration (1 ppm Cd). Recently, we measured caspase-3 activity and used the TUNEL assay to examine apoptosis in primary cultures of topsmelt hepatocytes exposed to multiple Cd concentrations (12-24 hrs, 15 °C). Cadmium (10 and 100 ng/ml) induced caspase-3 activity and caused DNA cleavage in topsmelt hepatocytes at levels below which extensive cytotoxicity was observed. Significantly higher caspase-3 activity levels and DNA cleavage were detected in topsmelt hepatocytes with increasing Cd concentration. Future in vivo studies will be performed to examine the linkages between apoptosis, impaired vitellogenesis, and oocyte development in Cd-exposed fishes.
Key words: cadmium, apoptosis, fish, reproductive tissues