An experimental approach to study the biosynthesis of brominated metabolites by the red algal genus Laurencia.

The production of labeled brominated metabolites with radioactive (82)Br in Laurencia species was investigated as part of a study of the biosynthesis of halogenated metabolites from species belonging to the red algal genus Laurencia (Rhodomelaceae, Ceramiales). Radiobromide [(82)Br], thin-layer chromatography (TLC), and TLC-autoradioluminography (ARLG) were used. When cultured in artificial seawater medium (ASP(12)NTA including Na(82)Br) under 16:8 h light:dark (LD) illumination cycles for 24 h, each of the strains of Laurencia, Laurencia japonensis Abe et Masuda, Laurencia nipponica Yamada (laurencin-producing race and laureatin-producing race), and Laurencia okamurae Yamada, produced species- (or race-) specific (82)Br-containing metabolites. In the case of the laurencin-producing race of L. nipponica, laurencin and deacetyllaurencin were found to be produced in approximately 1:1 ratio, though laurencin is the major metabolite in the wild sample. Furthermore, when cultured in the dark, the production rates of brominated metabolites in Laurencia spp. were found to be diminished. The present study strongly indicates that the use of radiobromine [(82)Br] in combination with the TLC-ARLG method is an effective approach for investigating the biosynthesis of brominated metabolites in Laurencia.

Striatal D2 dopaminergic receptors assessed with positron emission tomography and [76Br]bromospiperone in untreated schizophrenic patients.

Striatal D2 dopaminergic receptors of 12 drug-free schizophrenic patients and 12 normal subjects were investigated with positron emission tomography and [76Br]bromospiperone. Patients were classified according to DSM-III criteria, and their clinical symptoms were rated according to Andreasen's negative and positive symptom scales. The ratio of striatal to cerebellar radioactivity was taken as an index of striatal D2 dopamine receptor density. There was no significant difference between the control subjects and the overall schizophrenic group and no significant relationship between this index and the symptom ratings. However, state-dependent variables could partly account for the striatal D2 receptor density variability.