Episomic control of mutation in Salmonella typhimurium

Unstable mutation in Neurospora

“…As with many other instances of gene instability (for a recent summary see Dawson and Smith Keary, 1963) the instability reported here may be due to the attachment of episomic elements to either the his or a suppressor, (su-his) site with the latter fitting the data best. If the episome factors detached from the su-his site without attaching to other sites in most of the cells then a change of character from j-÷his would result.…”

Bacterial Conjugation and Extrachromosomal Elements

“…These include the genetic determinants for colicin production (94-97), Fo-lac+ (98), P-lac+ (99) multiple drug resistance factors in enteric spe cies (100-103) and staphylococci (104-106), a sporulation factor in Bacillus sltbtilis (93), and several suppressor and mutagenic factors (107)(108)(109). Most of these elements possess episomal qualities but fall short of the strict defi nition of an episome, since evidence for a stable integrated state is lacking.…”

Mutatorfaktor bei Staphylococcus pyogenes aureus?

“…Diese könnten durch An heftung an das Bakterienchromosom entweder Mutationen im Chromosom induzieren oder die phänotypische Expression der an der Anheflungsstelle lokalisierten Eigenschaft verhindern (1,4,15,17).…”