Actinomycete bacteria produce the majority of the microbial metabolites that have found use in medicine and agriculture. Until now, these bacteria have not been sufficiently characterized to allow efficient genetic manipulation. The genes necessary to produce a given metabolite tend to be carried within gene clusters many kilobases in length. On page 343 of this issue, Sosio et al. report that they have cloned 100 kb of actinomycete DNA into bacterial artificial chromosomes, where they are stably maintained in an integrated state.

On page 345, Henegariu et al. describe a method for labeling nucleotides with fluorescent dyes that will cut the cost of procedures that use these reagents by as much as 200-fold. They demonstrate that fluorescent nucleotides prepared by their technique can be incorporated by nick translation or PCR into DNA probes, which could then be successfully used in fluorescent in situ hybridization (FISH) analysis of metaphase chromosomes.