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The calcium-dependent antibiotic (CDA) is a non-ribosomally synthesised lipopeptide produced by Streptomyces coelicolor A3(2). The cda biosynthesis gene cluster occupies approximately 83 kb at the 10 o'clock region of the chromosome. A gene encoding a positive regulator of CDA production, designated cdaR, had been previously identified. Sequence similarly suggests that CdaR is a member of the Streptomyces antibiotic regulatory protein (SARP) family. CdaR is predicted to be 638 amino acid residues in size with a putative ATP/GTP-binding site motif A located in its C-terminal region. Mapping of the transcription start point of cdaR found that it possesses an unusually long untranslated leader sequence of 358 nt. cdaR transcripts were easily detectable at the earliest time point examined (24 h) and decreased over time. A 0.75 kb in-frame deletion in cdaR abolished CDA production. Nuclease protection experiments, using RNA isolated from a S. coelicolor cdaR deletion mutant, indicated that CdaR is required for transcription of some of the genes within the cda cluster, including itself. His6-tagged CdaR was produced in E. coli. Preliminary evidence from mobility shift assays suggested that CdaR binds directly to the 5' end of cdaR and also possibly to the promoter region of cdaPSI (peptide synthetase 1). Unexpectedly, introducing multiple copies of cdaR (approximately 50 copies/chromosome) into S. coelicolor 2377 and MT1110 did not detectably increase CDA production. Correspondingly cdaR transcripts only increased by ~ 30% in S. coelicolor MT1110 containing multiple copies of cdaR; this result suggests that transcription of cdaR is very tightly regulated.

This research presents a detailed study of the planktonic foraminiferal records of eleven sediment cores taken from a west-east transect in the Mediterranean Sea. Correlations are based on biostratigraphy, oxygen isotope stratigraphy and assisted by AMS 14C dating. This study assesses the potential to define a foraminiferal biostratigraphy of basin-wide validity. Principal Component Analysis (PCA) is used to determine variabilities in the planktonic foraminiferal records. The first principal component groups species on its positive and negative sides in such a way that this axis may be interpreted as an expression of SST variations. This interpretation is corroborated by its close similarity to oxygen isotope records. Mean PCA scores confirm previous observations that the temperature gradient in the eastern Mediterranean basin follows the same eastward increasing trend at glacial times as it does today. In contrast, the inferred sea surface temperatures (SST) from the western Mediterranean basin suggest a reversed gradient compared to the present. Preliminary results are discussed from the unprecedented high resolution marine records from two eastern Mediterranean cores. Based on PCA and planktonic foraminiferal ratios of warm, oligotrophic mixed layer species relative to cool, more eutrophic species, a series of cool episodes is observed throughout the Holocene. The cyclicity of these events is calculated at approximately 1300 years, a figure comparable with Holocene climate fluctuations recognised previously in the North Atlantic Ocean and the Greenland Ice Sheet. Micropalaeontological investigation of two western Mediterranean cores shows for the first time that abrupt cold spells, associated with Atlantic Heinrich-events, affected the Mediterranean Sea. Unusually high abundances of the subpolar species N. pachyderma (leftcoiling) in the Gulf of Lions reflect a thriving of a normally rare taxon in the western Mediterranean, in response to distinct, short term, episodes of favourable habitat development.