Role of polynucleotide kinase/phosphatase in mitochondrial DNA repair

Mutations in mitochondrial DNA (mtDNA) are implicated in a broad range of human diseases and in aging. Compared to nuclear DNA, mtDNA is more highly exposed to oxidative damage due to its proximity to the respiratory chain and the lack of protection afforded by chromatin-associated proteins. While repair of oxidative damage to the bases in mtDNA through the base excision repair pathway has been well studied, the repair of oxidatively induced strand breaks in mtDNA has been less thoroughly examined. Polynucleotide kinase/phosphatase (PNKP) processes strand-break termini to render them chemically compatible for the subsequent action of DNA polymerases and ligases. Here, we demonstrate that functionally active full-length PNKP is present in mitochondria as well as nuclei. Downregulation of PNKP results in an accumulation of strand breaks in mtDNA of hydrogen peroxide-treated cells. Full restoration of repair of the H2O2-induced strand breaks in mitochondria requires both the kinase and phosphatase activities of PNKP. We also demonstrate that PNKP contains a mitochondrial-targeting signal close to the C-terminus of the protein. We further show that PNKP associates with the mitochondrial protein mitofilin. Interaction with mitofilin may serve to translocate PNKP into mitochondria

Superhydrophobic paper in the development of disposable labware and lab-on-paper devices

Traditionally in superhydrophobic surfaces history, the focus has frequently settled on the use of complex processing methodologies using nonbiodegradable and costly materials. In light of recent events on lab-on-paper emergence, there are now some efforts for the production of superhydrophobic paper but still with little development and confined to the fabrication of flat devices. This work gives a new look at the range of possible applications of bioinspired superhydrophobic paper-based substrates, obtained using a straightforward surface modification with poly(hydroxybutyrate). As an end-of-proof of the possibility to create lab-on-chip portable devices, the patterning of superhydrophobic paper with different wettable shapes is shown with low-cost approaches. Furthermore, we suggest the use of superhydrophobic paper as an extremely low-cost material to design essential nonplanar lab apparatus, including reservoirs for liquid storage and manipulation, funnels, tips for pipettes, or accordion-shaped substrates for liquid transport or mixing. Such devices take the advantage of the self-cleaning and extremely water resistance properties of the surfaces as well as the actions that may be done with paper such as cut, glue, write, fold, warp, or burn. The obtained substrates showed lower propensity to adsorb proteins than the original paper, kept superhydrophobic character upon ethylene oxide sterilization and are disposable, suggesting that the developing devices could be especially adequate for use in contact with biological and hazardous materials

Shrink-Induced Superhydrophobic and Antibacterial Surfaces in Consumer Plastics

<div><p>Structurally modified superhydrophobic surfaces have become particularly desirable as stable antibacterial surfaces. Because their self-cleaning and water resistant properties prohibit bacteria growth, structurally modified superhydrophobic surfaces obviate bacterial resistance common with chemical agents, and therefore a robust and stable means to prevent bacteria growth is possible. In this study, we present a rapid fabrication method for creating such superhydrophobic surfaces in consumer hard plastic materials with resulting antibacterial effects. To replace complex fabrication materials and techniques, the initial mold is made with commodity shrink-wrap film and is compatible with large plastic roll-to-roll manufacturing and scale-up techniques. This method involves a purely structural modification free of chemical additives leading to its inherent consistency over time and successive recasting from the same molds. Finally, antibacterial properties are demonstrated in polystyrene (PS), polycarbonate (PC), and polyethylene (PE) by demonstrating the prevention of gram-negative <i>Escherichia coli</i> (<i>E. coli</i>) bacteria growth on our structured plastic surfaces.</p></div

Calculated values of the solid fraction (Φ) were found using the average flat CA (<i>θ_Y</i>) and the average structurally modified CA (<i>θ_C</i>).

<p>Calculated values of the solid fraction (Φ) were found using the average flat CA (<i>θ_Y</i>) and the average structurally modified CA (<i>θ_C</i>).</p

Top down SEM images and AFM of the structurally modified surfaces' multiscale structures were taken.

<p>Features are shown in (<b>A</b>) shrunk, bimetallic PO, (<b>B</b>) transferred in PDMS, and (<b>C</b>) imprinted in PS from PDMS. Scale bar is 10 µm for the large SEM images and 2 µm for the insets. (<b>D</b>) AFM 3D image of the morphology and height profile.</p

The low SA of superhydrophobic PDMS allows the water droplet to easily roll off the surface.

<p>(<b>A–C</b>) A droplet being placed on the surface of superhydrophobic PDMS retracts onto the dropper. (<b>D–F</b>) A droplet rolling off the same surface immediately after placement at a 5° angle.</p

PS, PC, and PE structured and flat substrates were contaminated with a bacteria solution and either rinsed or not rinsed.

<p>The resulting bacterial growth can be observed in each plate in the form of colonies following 24 hour incubation. (<b>A</b>) Substrates were rinsed with 50 µL of PBS after bacteria solution was deposited on the surface. (<b>B</b>) Substrates were not rinsed.</p