Hepatic metallothionein was measured in livers of freshly killed rainbow trout (Salmo gairdneri) using differential pulse polarography. The fish were caught in metal-contaminated lakes of the Campbell River watershed and in a nearby control lake. The livers were analyzed for zinc, copper, and cadmium using atomic absorption spectrophotometry. High and low molecular weight protein fractions were separated by gel chromatography from liver cytosols and analyzed for metals. A downward trend from the most contaminated lake to the least was found in levels of zinc in the water, of cadmium and copper in high molecular weight fractions, and of copper in low molecular weight fractions and metallothionein. The concentration of metallothionein is a useful quantitative measure of the degree of exposure of fish to heavy metals.Key words: metallothionein, rainbow trout, Salmo gairdneri; heavy metal pollution, sublethal exposures, mine wastes
A temperature-sensitive mutant of Moloney murine leukemia virus defective in an early function and injected into newborn mice produced lower limb paralysis. Susceptible mice were inbred strains CFW/D, CBA/H, C3H/Bi/Ka, and outbred NIH Swiss stock. Inbred W/Fu rats and C57BL/Ka mice did not develop the paralysis, though the latter were infected with virus; the sera from these mice produced paralysis in susceptible CFW mice.
SUMMARYA highly leukaemogenic virus isolate (DMBA-LV) endogenous to the CFW/D mouse has been found to contain two viral genomes. One was closely related to the type B milk-borne mouse mammary tumour virus (MMTV) and present in tenfold excess over a type C viral genome which was only partially related to xenotropic and polytropic isolates from the CFW/D mouse as well as to the ecotropic Moloney routine leukaemia virus isolate. The thymic lymphoma cell line that produced DMBA-LV expressed high levels of MMTV viral RNA (35S and the 24S envelope mRNA). Both the virus and the virus-producing cell line expressed multiple species of type C viral RNA. Similar species of type C viral RNA were also associated with non-infectious, non-leukaemogenic viral particles present in both normal lymphoid cells and in a MMTV-free thymic lymphoma cell line established from a second chemical carcinogen-induced tumour.
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