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In aqueous solution DNA intercalating ellipticine derivatives aggregate in n-mers. The self-association constants K are higher than those of 2-methoxy-6-chloro-9-[3-dimethylaminopropyl-amino]-acridine and ethidium bromide. They are of the same order as that of actinomycin D but inferior to that of acridine orange. The increase of the 9-hydroxy-ellipticine constant by addition of sodium chloride shows the importance of anion participation in the mechanism of stacking in accordance with the high energy of self-association. In the stacked n-mers the ellipticine rings are inverted. The geometry shows the importance of the orientation of the quadrupole axis in the intermolecular association of the intercalating drugs.

The helix-coil transition and conformation of d-CCATGG were investigated using 1H-NMR spectroscopy at various frequencies (90, 276, 400 MHz). The changes in the chemical shifts and linewidths of imino protons between 5 degrees and 35 degrees C show that the d-CCATGG fraying process consists of two stages: the external dC.dG base pairs open at first, th internal dC.dG and central dA.dT base pairs then open simultaneously at higher temperatures similar to the case of d-ACATGT. The midpoint temperatures, the helix and coil proportions and the dissociation constant were determined from the sigma = f(t degree) curves of the base and sugar protons. The results indicate that the midpoint temperature increases with the number of the dG.dC base pair in a given size sequence, while the dissociation enthalpy appears to be independent. The difference between the T1 value of a base proton of the external and internal residues of the same nature is found to be a good criterion for base proton assignment. The high predominance of the S conformation for all residues shows that d-CCATGG duplexes adopt the B-helical conformation.

ISSR amplification was evaluated for its applicability to strawberry varietal identification. Eighteen primers based on various di- tri- or tetra- SSR motifs with 3 or 0 5'-selective nucleotides for anchoring were screened against the strawberry genome by agarose gel electrophoresis. PCR conditions were optimised to obtain high quality patterns. Five primers that gave informative patterns were selected and used to characterise, by polyacrylamide gel electrophoresis, 30 strawberry varieties of various geographic and genetic origins. A total of 390 bands, 113 of which were polymorphic (30%), were generated using these five primers. Genetic similarity between varieties was estimated using Jaccard's coefficient of similarity. The associations between varieties revealed by UPGMA analysis were consistent with pedigree data. With only one primer, all the varieties were distinguished including those with a common pedigree. Banding patterns were highly reproducible for DNA samples extracted from different tissues (leaves, sepals, and rhizomes) of the same plant, or from different plants (clones) of the same variety. ISSR technique is therefore a potentially useful tool for the identification of strawberry varieties because it is simple, fast, cost-effective, highly discriminant and highly reliable. [ABSTRACT FROM AUTHOR]