The ability of oligodeoxynucleotides to form specific triple helical structures with critical regulatory sequences in the human dihydrofolate reductase (DHFR) promoter was investigated. A battery of purine-rich oligonucleotides targeted to the two purine.pyrimidine strand biased regions near the DHFR transcription initiation site was developed. The stable triple helical structures formed by bin...

Molecular strands incorporating three hydrogen bond donor (D) or acceptor (A) heterocycles form highly stable double helical complexes through a complementary AAA-DDD array structure.

Self-assembly of ABC star triblock copolymers confined in cylindrical nanopores is studied using self-consistent mean-field theory. With an ABC terpolymer forming hexagonally-arranged cylinders, segmented into alternative B and C domains, in the bulk, we observe the formation in the nanopore of a segmented single circular and non-circular cylinder, a segmented single-helix, and a segmented doub...

In flowering plants, double fertilization is normally accomplished by the first pollen tube, with the fertilized ovule subsequently inhibiting the attraction of a second pollen tube. However, the mechanism of second-pollen-tube avoidance remains unknown. We discovered that failure to fertilize either the egg cell or the central cell compromised second-pollen-tube avoidance in Arabidopsis thalia...

The theory of X-ray diffraction from ideal, rigid helices allowed Watson and Crick to unravel the DNA structure, thereby elucidating functions encoded in it. Yet, as we know now, the DNA double helix is neither ideal nor rigid. Its structure varies with the base pair sequence. Its flexibility leads to thermal fluctuations and allows molecules to adapt their structure to optimize their intermole...

The internal flow in corrugated tubes of different helical pitch, covering from the laminar to turbulent regime, was studied order characterize three-dimensional and influence corrugation geometry on pressure drop convective heat transfer. With water as working fluid an imposed wall flux, ranging around 4 33 kW/m2, a numerical model developed with CFD commercial software, where k?? SST used tur...

Double-helical architectures obtained from achiral ligands and metal ions present supramolecular homochirality in the single -crystal state under constitutional self-sorting.