ISSN:
1550-7408
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
SYNOPSIS. In defined media growth inhibition of the flagellates Ochromonas danica and Euglena gracilis, the photosyn thetic bacterium Rhodopseudomonas palustris, and Coryne bacterium bovis was overcome for each organism, for concentrations of 4-nitroquinoline N-oxide (4-NQO) to ca. 5 μg/ml, by a combination of L-tryptophan, riboflavin, nicotinic acid, L-tyrosine, and less sharply, thymine and naphtho quinones. Tryptophan used alone was effective only in rather high concentrations—ca. 0.2 mg/ml for 4-NQO 2 μg/ml; it was competitive with 4-NQO through this range. At least for Euglena, gramine and 5-methyl-DL-tryptophan were about as effective. 4-NQO uptake may therefore be via the trypto phan transport system. 4-NQO may be a uniquely stable, accessible counterpart of the more polar, more carcinogenic compounds into which mammals oxidatively convert the azodye carcinogens by N-hydroxylation and the hydrocarbon carcinogens by hydroxylation and ketonization.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1550-7408.1963.tb01700.x
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