RESUMEN

Bistrand lesions embedded within a single helical turn of tridecameric deoxyoligonucleotide duplexes represent a model system for exploring the impact of clustered lesions that occur in vivo and pose a significant challenge to cellular repair machineries. Such investigations are essential for understanding the forces that dictate lesion-induced mutagenesis, carcinogenesis, and cytotoxicity within a context that mimics local helical perturbations caused by an ionizing radiation event. This study characterizes the structural and energy profiles of DNA duplexes harboring synthetic abasic sites (tetrahydrofuran, F) as models of clustered bistrand abasic (AP) lesions. The standard tridecameric dGCGTACCCATGCG·dCGCATGGGTACGC duplex is employed to investigate the energetic impact of single and bistrand AP sites by strategically replacing one or two bases within the central CCC/GGG triplet. Our combined analysis of temperature-dependent UV and circular dichroism (CD) profiles reveals that the proximity and relative orientation of AP sites within bistrand-damaged duplexes imparts a significant thermodynamic impact. Specifically, 3'-staggered lesions (CCF/GFG) exert a greater destabilizing effect when compared with their 5'-counterpart (FCC/GFG). Moreover, a duplex harboring the central bistrand AP lesion (CFC/GFG) is moderately destabilized yet exhibits distinct properties relative to both the 3' and 5'-orientations. Collectively, our energetic data are consistent with structural studies on bistrand AP-duplexes of similar sequence in which a 3'-staggered lesion exerts the greatest perturbation, a finding that provides significant insight regarding the impact of orientation on lesion repair processing efficiency.

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RESUMEN

Color visual cryptography (VC) encrypts a color secret message into n color halftone image shares. Previous methods in the literature show good results for black and white or gray scale VC schemes, however, they are not sufficient to be applied directly to color shares due to different color structures. Some methods for color visual cryptography are not satisfactory in terms of producing either meaningless shares or meaningful shares with low visual quality, leading to suspicion of encryption. This paper introduces the concept of visual information pixel (VIP) synchronization and error diffusion to attain a color visual cryptography encryption method that produces meaningful color shares with high visual quality. VIP synchronization retains the positions of pixels carrying visual information of original images throughout the color channels and error diffusion generates shares pleasant to human eyes. Comparisons with previous approaches show the superior performance of the new method.