Outbreak of Meningococcal Disease in Devon

In a recent outbreak of 31 cases of meningococcal disease in Devon there were six deaths. Several patients had an unusual rash as the presenting feature and there was an unusually high incidence of complications, affecting the central nervous system, joints, and the heart among other sites.     

Flash photolysis of vertebrate photoreceptors

We consider the flash photolysis of visual pigment in a layered array of absorbers as in a vertebrate photoreceptor. The absorbers can be in three states, corresponding to the original product, an intermediate state and the final product. We include in our analysis photoreversal and transition quantum efficiency. We derive expressions for each layer and for the receptor as a whole, of photon incidence and absorption probabilities and of pigment bleaching. Our theoretical expressions agree under suitable conditions with equations derived by others on an empirical basis; and our computed results are in satisfactory agreement with experimental data. Our model should therefore prove useful in analyzing photolysis under physiological conditions.     

Dominant spore color mutants of Aspergillus nidulans defective in germination and sexual development.

The ascomycete Aspergillus nidulans produces green conidia (asexual spores). Recessive mutants which produce yellow conidia have been previously isolated from haploid strains and have been shown to be deficient in laccase (diphenol oxidase), an enzyme that requires copper for activity. Using a diploid parent strain, we isolated dominant yellow conidial mutants which, in the haploid state, produced even less laccase activity than a recessive mutant. Three isolates of such mutants behaved similarly and define a single complementation group (yB) on chromosome VIII distinct from the yA locus on chromosome I defined by recessive mutants. Unlike yA mutants, whose only discernable phenotype is their conidial color, yB mutants are pleiotropic: conidial germination was delayed relative to the wild type, and sexual development was blocked at an early stage. The three phenotypes of yB mutants were expressed on yeast extract-glucose medium containing 1.6 microM of added copper. When copper was added to above 5 microM, all three phenotypes were remediated, and near wild-type levels of laccase were produced. We conclude that yB mutants have a reduced availability of copper. The dominance of yB mutants could result, for example, from an alteration in transport or storage of copper. Using an immunological assay, we detected no laccase antigenic cross-reacting material in yB mutants grown on medium of low copper content. We conclude that either the synthesis or the stability of laccase is copper dependent.