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Cat's Claw (Uncaria tomentosa) water extracts, essentially free of oxindole alkaloids, have been shown to possess a broad spectrum of biological activity including DNA repair enhancement and antiinflammatory properties. These two biological mechanisms are key molecular targets to develop treatments that protect skin exposed to ultraviolet light from the sun. Because C-Med-100, a Cat's Claw water extract, is the only documented natural source of components that can up-regulate simultaneously both DNA repair and antiinflammation, its ability to modulate DNA repair in human skin organ cultures was undertaken. For this purpose skin cultures were treated with or without 5 mg/mL C-Med-100, irradiated with 0-100 mJ/cm2 UVB, and microscopically analysed for necrosis as well as the level of pyrimidine dimers using immunofluorescent TT-dimer antibody staining. The data clearly demonstrated that co-incubation with C-Med-100 reduced skin cell death from UV exposure, and this protection was accounted for by a concomitant increase in DNA repair. Based on these results, it was concluded that C-Med-100 was a natural plant extract worthy of further consideration as a sunscreen product.

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A high density sugar beet RFLP map with an average distance of 1.5 cM between markers has been constructed. The map covers 621 cM and includes 413 markers distributed over the nine linkage groups of sugar beet. The map is based on two F2 populations representing two different pairs of parents. The two sets of data were integrated into a single map using 90 markers that were common to both data sets. The quality of the map was assessed in several ways. The common markers were used to investigate how often the loci had been mapped in the same order in the two F2 populations. For closely situated markers (<1.5 cM) the order specified in the map is uncertain, but for markers separated by more than 2 cM the locus order is highly reliable. The error rate of the overall process was estimated at 0.3% by independently repeating the analysis of 41 markers. The map is comparatively short, with a map length corresponding to approximately 1.4 crossovers per bivalent. Another feature of the map is a high degree of clustering of markers along the linkage groups. With the possible exception of linkage group 2, each linkage group shows one major cluster, which in most cases is situated in the centre of the linkage group. Our interpretation is that sugar beet, in comparison with most other species, has an extreme localization of recombination. Key words : sugar beet, linkage, RFLP, clustering.