Cadmium delays growth hormone expression during rainbow trout development

Growth hormone (GH) mRNAs were first detected in rainbow trout Oncorhynchus mykiss during organogenesis (stage 29) within a control group while Gli ex pression in cadmium exposed embryos was not detected until a later organoge nic period (stage 31). GH transcripts were subsequently detected at all fur ther developmental stages analysed within both treatment groups. These incl uded hatching (stage 32), larval development (stages 33, 34, 35 and 36) and first feeding (stage 37). These results confirm that the GH axis is functi onal during early rainbow trout development and demonstrate an in vivo endo crine disrupting capacity at the molecular level for cadmium in teleosts. T his is of particular relevance to freshwater habitats as heavy metal induce d endocrine disruption may be a contributing factor in the decline of salmo nid populations. (C) 2001 The Fisheries Society of the British Isles.