A Novel Property of DNA – As a Bioflotation Reagent in Mineral Processing

Environmental concerns regarding the use of certain chemicals in the froth flotation of minerals have led investigators to explore biological entities as potential substitutes for the reagents in vogue. Despite the fact that several microorganisms have been used for the separation of a variety of mineral systems, a detailed characterization of the biochemical molecules involved therein has not been reported so far. In this investigation, the selective flotation of sphalerite from a sphalerite-galena mineral mixture has been achieved using the cellular components of Bacillus species. The key constituent primarily responsible for the flotation of sphalerite has been identified as DNA, which functions as a bio-collector. Furthermore, using reconstitution studies, the obligatory need for the presence of non-DNA components as bio-depressants for galena has been demonstrated. A probable model involving these entities in the selective flotation of sphalerite from the mineral mixture has been discussed

UNDERSTANDING THE MECHANISM OF DRUG-RESISTANT AND TUMOR RECURRENCE IN LIVER CANCER

Chemo-resistant and tumor recurrence are the major hurdle to overcome the cancer patients. Especially in hepatocellular carcinoma (HCC) is notoriously refractory to chemotherapy because of its tendency to develop multi-drug resistance (MDR), through various mechanisms. Aim: The current research is focussed on understanding the mechanism involved in chemo-resistant and tumor recurrence in liver cancer. Methods: Human hepatocellular carcinoma cell line (Huh7) was used entire study. Huh7 cells were cultured with known chemotherapeutic drugs such as 5-FU, Paclitaxel and Cisplatin-based on their Cmax concentration, and then these drug-treated cells were examined for chemoresistant and tumor recurrence properties through flow cytometry analysis, spheroid formation assay, and morphological analysis. Results: In morphological analysis confirm these all the chemo drugs were shown more cytotoxic effete than control, even though there were few viable cells noticed in cisplatin treatment. In flow cytometry analysis cisplatin pre-treated cells were well expressed LCSC marker such as CD133 and stem cell transduction factors like Oct-4 & Nanog than control. In addition to this, all the CD133 expressed cells also expressed to EpCAM. In spheroid formation assay, cisplatin pre-treated cells shown well-defined spheroid than control. Conclusion: LCSC plays a major role in chemoresistant and tumor recurrence through PI3K/Akt/mTOR, wnt-β catenin signaling, NF-kB signaling. So, targeting LCSC through EpCAM targeted therapy along with chemotherapy might be the better option for enhanced prognosis. Keywords: LCSC, Chemoresistant, Tumor recurrence, Hepatocellular carcinoma

Basic studies on the role of components of Bacillus megaterium as flotation biocollectors in sulphide mineral separation

Studies were carried out to assess the utility of the cellular and extracellular constituents of Bacillus megaterium for the flotation of sphalerite and galena minerals. Based on the flotation results on the individual minerals, it was observed that sphalerite was preferentially floated compared to galena. A maximum selectivity index (SI) value of 11.7 was achieved in the presence of the soluble fraction of the thermolysed cells, which was higher than that obtained with the intact cells (SI of 6.5) and the insoluble fraction of the thermolysed cells (SI of 9.6). The results of the various enzymatic treatment tests revealed that extracellular DNA played a vital role in the selective flotation of sphalerite. A noteworthy finding was that the single-stranded DNA (ssDNA) had a higher biocollector capacity vis-A -vis the double-stranded DNA (dsDNA), leading to better flotation efficiency. About 95 % recovery of sphalerite could be achieved from the mineral mixture by the combined addition of the ssDNA with the non-DNA components of the bacterial cells, resulting in a maximum SI of 19.1. Calcium and phosphate components of the nutrient media were found to be essential for better selectivity of separation of sphalerite. The mechanisms of microbe-mineral interaction are discussed

Effect of the strandedness of DNA on the flotation of sphalerite.

<p>a - thermolysed cell-free supernatant; b - genomic DNA (2 mg of dsDNA); c – DNase 1 treated genomic DNA; d - ssDNA (2 mg); e - DNase 1 treated ssDNA.</p

Schematic diagram of the amphipathic nature of ssDNA.

<p>(A) Amphipathic structure of ssDNA indicating the hydrophobic and the hydrophilic faces; (B) - Effect of spermidine concentration on the ssDNA mediated flotation of sphalerite; (C) - Effect of depurination of DNA on the flotation of sphalerite a - dsDNA; b - depurinated dsDNA; c - ssDNA; d - depurinated ssDNA.</p

Selective flotation of sphalerite and galena in the presence of unfractionated or thermolysed and fractionated components of <i>B.circulans.</i>

<p>a - normal cells; b - thermolysed cells; c - thermolysed cell-free supernatant; d - thermolysed cell pellet; e – DNase 1 treated thermolysed cell-free supernatant. The numbers above the bar chart indicates the selectivity index (S.I) values.</p

Flotation recovery of sphalerite and galena as a function of the ssDNA concentration.

<p>Flotation recovery of sphalerite and galena as a function of the ssDNA concentration.</p

Effect of buffering of cells on the flotation recovery of sphalerite and galena.

<p>Effect of buffering of cells on the flotation recovery of sphalerite and galena.</p

Flotation recovery of sphalerite and galena during reconstitution of the selective flotation of sphalerite with a fixed amount (2

<p> <b>mg) of ssDNA and varying amounts of DNase 1 treated non-DNA components of cells.</b></p