In vitro experiments with saliva resulted in precipitation of a mineral substance (dahllite or carbonate hydroxyapatite) which is comparable in composition and crystal structure to oral calculus. Similar mineral substances were produced from synthetic solutions containing sodium phosphate and calcium chloride (in addition to a buffer) in the presen...
The RNA world hypothesis requires a plausible mechanism by which RNA itself (or precursor RNA-like polymers) can be synthesized nonenzymatically from the corresponding building blocks. Simulation experiments have exploited chemically reactive mononucleotides as monomers. Solutions of such monomers in the prebiotic environment were likely to be very...
Single-stranded DNA and RNA molecules in solution can be driven through a nanoscopic pore by an applied electric field. As each molecule occupies the pore, a characteristic blockade of ionic current is produced. Information about length, composition, structure, and dynamic motion of the molecule can be deduced from modulations of the current blocka...
Gene regulation in cells exposed to ionizing radiation (IR) occurs at the transcriptional and post-transcriptional levels. Recent studies have suggested that micro-RNA (miRNA) play a significant role in post-transcriptional gene regulation in irradiated cells. miRNA are RNA molecules 18-24 nucleotides in length that are involved in negatively regul...
We show that an electric field can drive single-stranded RNA and DNA molecules through a 2.6-nm diameter ion channel in a lipid bilayer membrane. Because the channel diameter can accommodate only a single strand of RNA or DNA, each polymer traverses the membrane as an extended chain that partially blocks the channel. The passage of each molecule is...
Nutrient transport, polymerization and expression of genetic information in cellular compartments are hallmarks of all life today, and must have appeared at some point during the origin and early evolution of life. Because the first cellular life lacked membrane transport systems based on highly evolved proteins, they presumably depended on simpler...
Calcium permeability of sarcoplasmic reticulum (SR) microsomes was measured after aging or after exposure to peroxydisulfate or to sulfhydryl-binding agents. Under conditions where the Ca2+-ATPase was active, the maximum net release of Ca2+ was not significantly different between control and oxidized SR. However, when calcium uptake was prevented b...
Large, unilamellar vesicles composed of equimolar amounts of acidic phosopholipids and phosphatidylethanolamine were able to deliver fluorescent dye [5(6)-carboxyfluorescein] or a monoclonal antibody directed against intermediate-filament proteins to a Drosophila cell line (Kc cells). Millimolar Ca2+ or protamine sulfate in microgram quantities tri...