Publication Abstract

The three-spined stickleback: an emerging model in environmental endocrine disruption

I. Katsiadaki, M. Sanders, M. Sebire, M. Nagae, K. Soyano and A.P. Scott

The three-spined stickleback (Gasterosteus aculeatus) is a small teleost species with exceptionally wide geographic distribution that shows remarkable speciation. Its origin lies in the marine environment since both geographic and genetic evidence shows that freshwater populations have been derived repeatedly from a marine ancestor (1). Their ubiquity and ease to obtain and keep in the laboratory are factors that have contributed to the use of this species as a vertebrate model for studies in behaviour, physiology, evolution and ecology. In more recent years, the stickleback has also attracted the interest of molecular biologists, resulting in a dramatic increase in the available resources. The main drive for such an explosive research activity was the realisation that sticklebacks offered a useful model for the study of the molecular basis of vertebrate evolution (2). Fossil records show that although the general morphology of marine groups of sticklebacks have changed very little over time, freshwater groups exhibit a wide variety of morphs in different environments. There appears to have been repeated evolution of similar traits in many widely separated freshwater environments. The consistent association of particular phenotypes with particular ecological conditions provides a strong argument that the corresponding traits are adaptive and have been repeatedly selected in different locations. This observation formed the basis for a successful proposal to sequence the stickleback genome. The consequent flood of information has produced an increased interest by the research community in other (less historically popular) fields, of biological research including ecotoxicology. The relatively small genome of the stickleback (estimated at 675 mega bases) implies that intron size is small and that a second genome duplication event did not take place in the stickleback (as it did in many other fish species), aiding the speed of annotation and the functional characterisation of genes of interest. The he fascinating reproductive behaviour displayed by males has given the stickleback a special place in fish reproduction studies. The strong secondary sexual characters of the male are androgen dependent and provide a unique animal model for the study of the factors affecting male sexual differentiation and reproductive performance in both fundamental biological research and ecotoxicology.

Reference

I. Katsiadaki, M. Sanders, M. Sebire, M. Nagae, K. Soyano and A.P. Scott (2007) The three-spined stickleback: an emerging model in environmental endocrine disruption. Environmental Sciences 2007;14(5):263-283.