Showing papers by "Yuan-Chih Chang published in 2004"

Heterodimeric complexes of Hop2 and Mnd1 function with Dmc1 to promote meiotic homolog juxtaposition and strand assimilation

Abstract: Saccharomyces cerevisiae Hop2 and Mnd1 are abundant meiosisspecific chromosomal proteins, and mutations in the corresponding genes lead to defects in meiotic recombination and in homologous chromosome interactions during mid-prophase. Analysis of various double mutants suggests that HOP2, MND1, and DMC1 act in the same genetic pathway for the establishment of close juxtaposition between homologous meiotic chromosomes. Biochemical studies indicate that Hop2 and Mnd1 proteins form a stable heterodimer with a higher affinity for double-stranded than single-stranded DNA, and that this heterodimer stimulates the strand assimilation activity of Dmc1 in vitro. Together, the genetic and biochemical results suggest that Hop2, Mnd1, and Dmc1 are functionally interdependent during meiotic DNA recombination.

Nanoscale imaging of biomolecules by controlled carbon nanotube probes

Abstract: We use a carbon nanotube (CNT) probe to observe the details in double-stranded deoxyribonucleic acid (DNA) and proteins under atomic force microscopy (AFM) tapping mode in air. The DNA has periodic helical turns of approximately 4 nm interval. Fine ring like and helical structures in the proteins adsorbed on graphite have also been resolved. These results cannot be reproduced using conventional AFM silicon probes. The superiority of the CNT probe applied with the AFM tapping mode lies in both the unique mechanical and chemical properties of the carbon nanotube, and in our ability to tailor the length and adjust the angle of the CNT probe attached to a commercial AFM tip.