T. Marks et Wr. Farkas, EFFECTS OF A DIET DEFICIENT IN TYROSINE AND QUEUINE ON GERM-FREE MICE, Biochemical and biophysical research communications, 230(2), 1997, pp. 233-237
A chemically-defined diet consisting of amino acids (including tyrosin
e), vitamins, trace elements, glucose, etc., known to support growth a
nd reproduction through many generations when fed to germfree mice has
been in use for many years in our laboratory. Classical nutritional s
tudies showed that tyrosine was not a dietary requirement for higher m
ammals if an adequate amount of phenylalanine was present. Therefore,
it was unexpected that when tyrosine was removed from this diet, the g
ermfree mice developed ocular, neurological and other abnormalities wh
ich resulted in 100% fatalities usually within two weeks. adding tyros
ine back to the diet prevented the abnormalities from occurring. Conve
ntional mice with a normal intestinal flora showed none of these sympt
oms when fed the same tyrosine deficient diet. We added queuine to the
tyrosine-deficient diet at a concentration of 0.1 mu M. The germfree
mice that were fed the diet supplemented with queuine were asymptomati
c and remained alive until the termination of the experiments. (C) 199
7 Academic Press