Immunotoxicity in ascidians: Antifouling compounds alternative to organotins – II. The case of Diuron and TCMS pyridine

Abstract

Using short-term hemocyte cultures of the colonial ascidian Botryllus schlosseri exposed to various sublethal concentrations of Diuron (3-(3,4-diclorophenyl)-1,1-dimethylurea) and TCMS pyridine (2,3,5,6-tetrachloro-4-(metylsulphonyl)pyridine), we evaluated their immunotoxic effects through a series of cytochemical assays previously used for organotin compounds. At concentrations higher than 250 μ M and 10 μ M for Diuron and TCMS pyridine, respectively, both biocides exerted immunosuppressant effects on Botryllus hemocytes, causing i) deep changes in the cytoskeleton that irreversibly affect cell morphology and phagocytosis, ii) induction of DNA damage, iii) leakage of oxidative and hydrolytic enzymes due to membrane alteration. Unlike organotin compounds, Diuron and TCMS pyridine do not inhibit cytochrome-c-oxidase, and only TCMS pyridine triggers oxidative stress. When co-present, they exert an antagonistic interaction on cytoskeletal components.

Keywords:

• Botryllus
• Diuron
• TCMS pyridine
• phagocytes
• immunotoxicity

Acknowledgments

We thank Mr. M. Del Favero for technical help. This work was supported by the Italian Co.Ri.La. and M.I.U.R.

This paper was presented at the CEMEPE conference held on June 24–28, 2007 at the Skiathos Island, Greece.