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Abstract
Balb/c mice that have received an intravenous, sublethal injection of Nocardia asteroides strain GUH-2 (GUH-2) exhibit a variety of neurological dysfunctions, including a Parkinsonian-like movement disorder. In order to understand this disease process better, two mutants of GUH-2 were isolated for comparative studies with the parent. One mutant induced a greater frequency of neurologic signs than the parent, while the other mutant induced a lower frequency. Brain microdissection studies, which involved the three strains, demonstrated that both mutants attached at significantly lower levels than the parent and suggested that attachment involved a specific receptor. Studies of growth rates in localized brain regions revealed differences in the site-specific growth of the parent and mutants. Additionally, the results suggested that the Parkinsonian-like movement disorder may be related to damage in the substantia nigra. Examination of a water-soluble, orange pigment, that was secreted by each organism during growth in a chemically defined medium containing tyrosine, demonstrated that the compound contained tyrosine and that it may be a siderophore. Comparative studies revealed differences in both the amount of pigment produced by each organism and the effects of Fe(III) upon pigment production. The alterations in attachment, growth, and pigment production that were demonstrated for the mutants may be significant to their altered frequencies of induction of neurologic signs.
