Global screening of base excision repair in nucleosome core particles.

DNA damage is a fundamental molecular cause of genomic instability. Base excision repair (BER) is one line of defense to minimize the potential mutagenicity and/or toxicity derived from damaged nucleobase lesions. However, BER in the context of chromatin, in which eukaryotic genomic DNA is compacted through a hierarchy of DNA-histone protein interactions, is not fully understood.

Obstacles and opportunities for base excision repair in chromatin.

Most eukaryotic DNA is packaged into chromatin, which is made up of tandemly repeating nucleosomes. This packaging of DNA poses a significant barrier to the various enzymes that must act on DNA, including DNA damage response enzymes that interact intimately with DNA to prevent mutations and cell death. To regulate access to certain DNA regions, chromatin remodeling, variant histone exchange, and histone post-translational modifications have been shown to assist several DNA repair pathways including nucleotide excision repair, single strand break repair, and double strand break repair.

Two colorimetric fluorescent turn-on chemosensors for detection of Al and N : Synthesis, photophysical and computational studies.

Two new rhodamine derivative L and L bearing 2-methoxy-1-naphthaldehyde and 5-bromo-3-methoxy salicylaldehyde units were designed and synthesized using microwave-assisted organic synthesis and utilized towards sequential fluorescence detection of aluminum ion (Al ) and azide (N ) in aqueous acetonitrile solution. Aluminum ion (Al ) triggers the formation of highly fluorescent ring-open spirolactam. The fluorescence and colorimetric response of the L -Al and L -Al complexes were quenched by the addition of N , which extracting the Al from the complexes and turn-off the sensors, confirming that the recognition process is reversible.

Microwave-assisted synthesis of rhodamine derivatives.

The microwave synthesis of 12 rhodamine-derived imines is described. The present work involves condensation of rhodamine hydrazide with various aromatic aldehydes in ethanol under microwave irradiation. The results obtained indicate that, unlike classical heating, microwave irradiation results in higher yields, shorter reaction time, mild reaction condition and simple work-up procedure.