Calf thymus dna sodium salt

Calf thymus DNA sodium salt (type I fibers, 42% GC content, Sigma-Aldrich, USA) was dissolved in distilled water. The concentration of double-stranded DNA (dsDNA) (~90%) present in the DNA stock solution was quantified using a broad range double stranded DNA fluorescent dye assay (Qubit, Invitrogen, USA). Total RNA was extracted from P. aeruginosaPA14 cultures at mid-logarithmic growth phase using RNeasy Mini Kit (QIAGEN, Germany). Prodigiosin and Prd/Cu(II) treated dsDNA (~200 ng/μl) and RNA (~120 ng/μl) samples were incubated overnight at 37°C and room temperature, respectively. Tert-butanol (2 M) and N-acetylcysteine (NAC) (10 mM) were used as hydroxyl radical (^•OH) scavenger and reactive oxygen species scavenger, respectively, where it is necessary. Decrease in dsDNA concentration due to the cleaving was monitored by agarose gel electrophoresis. Gels were supplemented with GelRed (Biotium, USA) and visualized by the GeneGenius Gel Imaging System (Syngene, UK). Relative intensity of DNA bands on agarose gels were measured with ImageJ software. Decrease in RNA concentration due to the cleaving was measured with broad range RNA fluorescent dye assay (Qubit, Invitrogen, USA) according to manufacturer‘s instructions. Non-treated dsDNA and RNA were used as control. All samples were analyzed at least 3 times.

Anti-double-stranded DNA (dsDNA) antibody titres were measured by ELISA using a modified version of a previously described method [33 (link)].
Briefly, calf thymus DNA sodium salt (Sigma Aldrich) was used to coat 96-well plates overnight at 20 μg/mL at 4°C and then blocked with /PBS / 2% BSA (KPL) for 1 h at 37 °C. After washing, samples were added; plasma samples were diluted 1:800 in PBS / 1% BSA / 0,2% Tween, and salivary gland homogenates were left undiluted. After 1 h incubation at 37 °C, anti-mouse polyvalent immunoglobulins (IgG, IgM)–alkaline phosphatase antibody (Sigma Aldrich) was added for 2 h at 37 °C, and the reaction developed with Alkaline Phosphate Yellow Liquid substrate (Sigma Aldrich) for 1 h at 37 °C. The absorption was read at 405 nm using a Spectromax 384 microplate reader (Spectromax Molecular Devices). Results are expressed as optical density after subtraction of the blank value (dilution buffer). They were normalized to the whole left salivary gland.

Halloysite nanoclays and Calf Thymus DNA sodium salt were purchased from Sigma Aldrich (St Louis, MO, USA) and used without further purification. Morphological properties of the sample used in the present investigation have been accurately measured by Transmission Electron Microscopy. Results have been reported in Supplementary Information of our previous work [29 (link)]. We found that HNs have an average length of 400 nm, an average outer diameter of 50 nm and lumen size of 13 nm. Calf thymus-DNA is a linear chromosomal DNA with ${10}^4$ base pairs as determined by gel electrophoresis [30 (link)].