title: Effects of a diet deficient in tyrosine and queuine on germfree mice.
abstract: A chemically-defined diet consisting of amino acids (including tyrosine), vitamins, trace elements, glucose, etc., known to support growth and reproduction through many generations when fed to germfree mice has been in use for many years in our laboratory. Classical nutritional studies showed that tyrosine was not a dietary requirement for higher mammals if an adequate amount of phenylalanine was present. Therefore, it was unexpected that when tyrosine was removed from this diet, the germfree mice developed ocular, neurological and other abnormalities which resulted in 100% fatalities usually within two weeks. Adding tyrosine back to the diet prevented the abnormalities from occurring. Conventional mice with a normal intestinal flora showed none of these symptoms when fed the same tyrosine-deficient diet. We added queuine to the tyrosine-deficient diet at a concentration of 0.1 microM. The germfree mice that were fed the diet supplemented with queuine were asymptomatic and remained alive until the termination of the experiments.
authors.affiliation: Department of Comparative Medicine and The Graduate Program in Environmental Toxicology of The University of Tennessee, Knoxville 37901-1071, USA.
authors.forename: T
authors.initials: T
authors.lastname: Marks
authors.forename: W R
authors.initials: WR
authors.lastname: Farkas
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet; D005128:Eye Diseases / Q000209:etiology; D005527:Food, Fortified; D005856:Germ-Free Life; D006147:Guanine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D009422:Nervous System Diseases / Q000209:etiology; D014443:Tyrosine / Q000008:administration & dosage / Q000172:deficiency* / Q000494:pharmacology
chemical_list: D014443:Tyrosine; D006147:Guanine; C019549:queuine