FIG. 6.

Morphological effects induced by ram gene copy number. While S. lividans (strain 1326) initiated production of aerial hyphae after 3 days of growth on R2YE plates, abundant aerial hyphae were formed by S. lividans carrying the full ram cluster on the low-copy-number plasmid pIJ698 (1/1/11) or integrated as an extra copy in the genome at the ΦC31 integration site (pBK125). In addition, S. lividans transformants carrying ramR in the high-copy vector pUWL219 (pAF07) also displayed an accelerated onset of development. The development of strains carrying ramR as an extra copy integrated at the ΦC31 integration site in the genome (pAF05) was not accelerated. The development of S. lividans carrying an insertional mutation in ramR was delayed in comparison with that of wild-type strains.