Effects of sublethal levels of tributyltin chloride on a new toxicity test organism, Liza saliens (Osteichthyes, Mugilidae)

Abstract

The histopathological effects of 10−7 and 10−9 M tributyltin(IV)chloride,TBTCl, solutions on different Liza saliens organs have been studied by light microscope. The fish were sacrificed after 3–4 h incubation in 10−7 M TBTCl solution or after 15 days incubation in 10−9 M solution. The observed histopathological changes were dose- and time-dependent. The 10−7 M TBTCl concentration resulted in major damage to the gill epithelium, indicating that TBTCl primarily interferedwith the respiration, osmoregulation, acid balance and nitrogenous waste excretion processes. After incubation in 10−9 M TBTCl solution the fish lived 20 or more days, but many of the organs were altered. Thymus atrophy, reduced spleen and altered head kidney were observed. These histological results indicated that TBTCl interfered with organ immunodefense and altered main metabolic pathways in Liza saliens. The presence of melano-macrophage centers, only in TBT-treated liver and spleen, can be considered a tool to facilitate, with other biomarkers, the detection of alterations by toxicants. Regarding the pancreas activity in 10−7 M solutions, it has been noted that, in the exocrine cells, very few zymogen granuleswere still present and the Langerhans isletsweremore altered. In 10−9M solution the exocrine pancreatic cells had no granules and the islet cells presented degenerative alterations. In addition, TBTCl, which altered the pancreas and gonad morphology, could again be considered an endocrine disrupter even if biochemical data are still necessary. Finally, the Liza saliens juveniles could be considered an interesting biological model for experiments with contaminants, due to their ease of adaptation to experimental conditions and food chain position.