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Liver cell carcinoma (hepatoma) in rainbow
trout, caused by aflotoxins produced by the fungus Aspergillus flavus
attacking cottonseed meal is a clear case of cancer in fishes. Although
trout are susceptible to this aflotoxin damage, carp are resistant. Normal
hepatocytes are replaced by small hyperplastic cells that stain deeply as
normal sinusoids are lost. Cancer is rare in fishes and the effects of diet
are virtually unknown. Since 1965, the Registry of Tumors in Lower
Vertebrates, US National Museum of Natural History, Washington has offered
diagnostic help. The PLHC-1 fish hepatoma cell line (Poeciliopsis lucida) is
used to evaluate the acute cytotoxicities of direct-acting (alkylbenzenes,
phthalate diesters, pesticides and metabolism-mediated benzo[a]pyrene
toxicants along with Aroclor 1254. It is a chemical inducer of cytochrome
P450-dependent monooxygenase activity), and was reduced by EPN (an inhibitor
of P450 activity). Such pioneer cancer assessment efforts deserve MUCH MORE
SUPPORT. |