title: Induction of apoptosis in testis of the marine teleost mummichog Fundulus heteroclitus after in vivo exposure to the antifouling biocide 4,5-dichloro-2-n-octyl-3(2H)-isothiazolone (Sea-Nine 211).
abstract: 4,5-dichloro-2-n-octyl-3(2H)-isothiazolone (Sea-Nine 211) has been widely used as an effective antifouling biocide. However, little is known about its reproductive toxicity in fish. Here we investigated testicular toxicity in a marine teleost, the mummichog Fundulus heteroclitus, after exposure to Sea-Nine 211 for 28 d. Although Sea-Nine 211 exposure did not affect germ cell proliferation in testis, terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick-end labeling revealed that the number of apoptotic spermatocytes was increased in the 1.0- and 3.0-μg L(-1) groups, and significant differences emerged between the 1.0-μg L(-1) group and control groups. Immunohistochemistry showed that the numbers of cysts expressing caspases 2, 3, 6, and 8 (apoptosis-associated proteins) were significantly increased in the 1.0-μg L(-1) group, whereas the signal intensity of an anti-apoptotic protein Bcl-xL was reduced in a dose-dependent manner. Moreover, the number of cysts positive for neuronal nitric oxide synthase was twofold higher in the 1.0-μg L(-1) group than in the control groups. These results suggest that long-term exposure to Sea-Nine 211 induces apoptosis in the testicular germ cells of mummichogs via a caspase-dependent pathway and that oxidative stress via nitric oxide synthesized by neuronal nitric oxide synthase is involved in this induction.
authors.affiliation: National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Research Agency, Maruishi 2-17-5, Hatsukaichi, Hiroshima 739-0452, Japan.
authors.forename: Mana
authors.initials: M
authors.lastname: Ito
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Mochida
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Ito
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Onduka
authors.forename: Kazunori
authors.initials: K
authors.lastname: Fujii
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D004202:Disinfectants / Q000378:metabolism* / Q000633:toxicity; D023781:Fundulidae / Q000378:metabolism*; D020287:In Situ Nick-End Labeling; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D013090:Spermatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013737:Testis / Q000187:drug effects*; D013844:Thiazoles / Q000378:metabolism* / Q000633:toxicity; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: D004202:Disinfectants; D013844:Thiazoles; D051020:bcl-X Protein; C080469:Kathon 930; D020169:Caspases