Curromycin A

Protoplast regeneration carried out in a carriomycin producing organism, Streptomyces hygroscopicus 358 AV2, lose carriomycin productivity without loss of carriomycin-resistance and the ability of formation of aerial mycelium. Ethidium bromide treatment on the 358 AV2 strain generated a bald mutant that produced carriomycin and a new antibiotic curromycin. In some other media, however, the parent strain produced curromycin, indicating that the ethidium bromide treatment altered the regulation of antibiotic production. Ethidium bromide treatment on a protoplast-regenerated strain derived from the parent strain resulted in derivatives capable of producing carriomycin and curromycin. These strains were unstable and tended to lose the recovered antibiotic productivity easily.

We cloned six different DNA fragments from a curromycin producing strain, Streptomyces hygroscopicus 358AV2, which confer curromycin-resistance on a curromycin non-producing and sensitive strain, S. hygroscopicus Rgll, a protoplast regenerant of the strain 358AV2. We studied the plasmid pSHR2 carrying one of the DNA fragments. By Southern blot analysis, the cloned DNA sequence in pSHR2 was found to be deleted in the Rgll genome. From the Rgll strain, a curromycin producing revertant A-4 was obtained, indicating that the structural genes for the curromycin biosynthesis and resistance are retained in the Rgll genome. Based on the existence of A-4 and the deletion of the DNA region corresponding to the cloned DNA sequence in the Rgll genome, we conclude that the cloned DNA sequence carries a regulatory gene governing curromycin-resistance but not the resistance gene itself. The smallest DNA region in pSHR2 conferring curromycin-resistance was sequenced, and it was found that there were two small open reading frames (ORF) on each strand of the cloned DNA. In-frame fusion of ORFs to the reporter gene lacZ revealed that one ORF designated cre was indeed translated in vivo. The putative gene product deduced from the cre ORF is a basic and hydrophilic protein having a calculated molecular weight of 6 kdaltons.

Changes in medical education and in the environments in which students learn have brought about new ways of learning in undergraduate medical curricula. Amongst these have been the establishment of courses in clinical skills learning to address concerns of deficient skills amongst newly qualified doctors. Curriculum reform at Liverpool, UK, included extensive and early learning of clinical skills. Nurse tutors provide full-time teaching support in a single Clinical Skills Resource Centre. They work alongside medically qualified tutors in delivering a clinical skills learning programme. This study aimed to explore students' opinion of nurses teaching clinical skills and to compare that to their opinion of teaching by medically qualified clinicians. A questionnaire survey was used to gain the views of 206 first-year medical students. Overall, students were strongly supportive in their opinion of nurse tutors. Some small statistically significant differences are probably of little or no educational significance. This role for nurses stresses the importance of interprofessional teachers in undergraduate healthcare education.