Carotenoid synthesis in Streptomyces setonii ISP5395 is induced by the gene crtS, whose product is similar to a sigma factor

In many species of actinomycetes, carotenogenesis can be photoinduced. The capacity to respond to photoinduction is, however unstable and, in various strains of Streptomyces, is lost at a relatively high frequency. In Streptomyces setonii ISP5395, which normally produces no carotenoids, carotenoid-producing mutants can be obtained following protoplast regeneration. We report here the characterization of a gene, crtS, which was isolated from one such mutant and can confer on wild-type S. setonii ISP5395 cells the capacity to synthesize carotenoids. Sequence analysis of crtS reveals an open reading frame, which shows homology to genes that encode alternative sigma factors in Bacillus subtilis. We propose that crtS encodes a sigma factor which is necessary for the expression of a cryptic gene(s) for carotenoid biosynthesis in S. setonii ISP5395.     

A study of sugar beet growers' pest control decisions

The results of a survey of sugar beet growers are reported which provide subjective information on farmer perceptions of the hazard from pests and diseases on sugar beet, the control methods available and used, farmers' estimates of the costs and effect of controls, their objectives for pest control, and their attitudes to advice. In addition, objective information from research and field observations on losses and control methods is provided. The basis of pest control decisions and implications from comparisons of subjective and objective perceptions of the various problems and solutions are discussed.