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Dopamine D1 and D2 receptors were determined in brain tissue taken post mortem from schizophrenic patients previously known to have had tardive dyskinesia and yet who had not received neuroleptic drug treatment for over one year prior to death. In comparison with age-matched control subjects, diminished D2 receptor density was observed in striatal regions, while these receptors appeared to be increased in the pallidum, an area of the brain particularly implicated in the production of dyskinesias. D l receptors showed similar tendencies to lower numbers in the striatum in tardive dyskinesia.

SUMMARY: Mutants of Pseudomonas aeruginosa 8602 were isolated which, unlike the wild type, were able to grow with butyramide as a carbon source. Six mutants derived from the constitutive strain c 11 were shown to produce an enzyme (B amidase) with altered electrophoretic mobility and altered substrate specificity. The apparent Km for butyramide of the B amidase was about a tenth of that of the A amidase and the Vmax was about ten-fold greater. A further mutation produced mutants able to grow on valeramide.

SUMMARY: Mutants of Pseudomonas aeruginosa 8602 were isolated which, unlike the wild-type strain, utilized butyramide as a growth substrate. One group produced amidases with altered substrate specificities, indicating that the mutations may be in the amidase structural gene. The second group of butyramide-utilizing mutants produced wild-type enzyme and were all constitutive. It was concluded that such mutants possessed mutations in an amidase regulator gene which allowed them to synthesize large amounts of amidase in the presence of butyramide. Induction of amidase synthesis by N-acetylacetamide in the wild-type strain was repressed in a competitive manner by butyramide and other amide analogues, e.g. cyanoacetamide. The constitutive mutant c11, which could not utilize butyramide for growth, was subject to severe repression of amidase synthesis by butyramide and cyanoacetamide. The regulator mutants which were able to grow on butyramide were all less sensitive to repression by butyramide. Mutant cb 2, a butyramide-utilizing regulator mutant, was relatively insensitive to repression of amidase synthesis by cyanoacetamide whereas strain b6, a butyramide-utilizing mutant producing an altered enzyme, was as sensitive to repression by cyanoacetamide as its parent strain the constitutive mutant c11. The contribution of mutations in structural and regulator genes to utilization of novel growth substrates is discussed.

Differentiation is the process by which the descendants of a single cell, the fertilized egg, come to differ from one another and to form tissues and organs performing specialized functions. A detailed picture of how embryos differentiate at the morphological level has been built by classical embryologists and developmental geneticists from detailed observations and intricate surgical experiments with normal and mutant organisms1. The central problem of developmental biology today is to understand the process in molecular terms.