SPIGGIN: A STICKY TOXICITY INDICATOR

Abstract

Endocrine-disrupting chemicals are natural or man-made chemicals that can mimic endogenous hormones and cause physiological disturbances. Released into the aquatic environment, from sources such as sewage treatment plants and pulp mills, these compounds are a perceived problem for both animals and humans as they can interact with normal hormonal function. In particular, interference with sex hormones is known to affect organisms undergoing early gonadal development and sex differentiation. In their Environmental Toxicology and Chemistry paper, Katsiadaki and colleagues continue to test and develop a novel method used to detect exposure of fish to androgenic compounds, based on the physiological effects of male sex steroids in female sticklebacks.The majority of research into endocrine-disrupting chemicals has focused on oestrogenic chemicals that mimic the female sex hormones. Less is known about the chemicals that mimic male sex hormones. But while the debate rages as to the degree of impact these chemicals are having on our environment, it is generally accepted that these endocrine-disrupting chemicals are ubiquitous contaminants of the aquatic ecosystem.Spiggin is a glycoprotein glue, which male sticklebacks use to stick together their nests. The protein is produced by the males during the breeding season in response to endogenous androgens that cause the epithelial cells of the kidney to increase in size and synthesise the protein. Histological examination of kidney epithelia cells in response to artificial administration of androgens has been used previously to monitor the physiological effects of androgens, and as an indicator of spiggin production, but this is a time-consuming method.The authors of this study aimed to test whether direct measurements of atypical production of spiggin in female sticklebacks could be used as an indicator of exposure to environmental androgens. Recently, the team developed a spiggin enzyme-linked immunosorbent assay (ELISA), which allowed them to determine the levels of spiggin in the kidney. They wondered whether this new method could be used to detect waterborne androgen exposure in a dose-dependent manner.They found that spiggin detection could be used successfully as an indicator of androgen exposure in female sticklebacks. Spiggin production in females exposed to increasing concentrations of the androgens 17α-methyltestosterone and 5α-dihydrotestosterone was strongly correlated with kidney epithelia cell height, but measurement of spiggin was a much quicker method with a considerably higher response range.This work is noteworthy for two reasons. Firstly, the authors, in combination with their previous research, have successfully developed a novel and practical method of detecting exposure to environmental androgens in vivo. Secondly, the study clearly illustrates how contamination of the aquatic environment with endocrine-disrupting chemicals can have profound effects on the physiology of the organisms that live there and how these physiological changes can be used to develop novel methods for environmental monitoring.