Motivated by evidence that the diffusion of presynthesized protein from the interior of the cell to and incorporation into the cell border is the mechanism of endothelial tight junctional sealing, we develop a diffusion-limited mathematical model of intercellular gap sealing.
It was the middle of another perfectly sunny day in Los Angeles, but the trailer was pitch-black, with the doors closed and gaps sealed with duct tape to prevent the light from leaking through.
In this method, a liquid-state gap-sealing foam is injected within the enclosed spaces of a structure.
A simple demonstration of the proposed technique is provided by load-testing thin-wall beverage cans, and also both intact and damaged aluminum honeycomb, filled with commercially available gap-sealing polyurethane foam.
Gap-sealing was fastest for tethered dC and dG, followed by tethered dI, and it was considerably slower for tethered dT and dA.
The "universal" base dNI, which has found utility within PCR primers [25], [26], [27], [28], was efficiently adenylated but did not support gap-sealing under these conditions, perhaps due to distortions of local helical structure.
To dissect quantitatively the effects of tethered mononucleotide identity on the rates of adenylate formation and gap-sealing, ligation complexes were assembled with each radiolabeled dXHr8 substrate using the corresponding Watson-Crick paired A2 bridges, and samples were collected every 15 to 30 minutes for 6 h.
Reactions that included labeled dCHr8 or dGHr8 were the most efficient (>60% yield after 20 h), while the other three were much less efficient (Table 2), probably as a result of faster gap-sealing kinetics of these two substrates relative to the others (see above).
We measured rates of the individual steps in the ligation reaction (adenylation and gap-sealing) under optimized conditions on a variety of tethered monodeoxynucleotide substrates including dC, dT, dA, dG, dI, and deoxy 5-Nitroindole (dNI in combination with both cognate and mismatched bridging templates.
Analysis of retarded repair sites following ultraviolet irradiation indicated those sites to be nonligatable in polyamine-depleted and nickel-treated cells, suggesting a block in the normal gap-sealing process.
