Hydrogen production and anaerobic decolorization of wastewater containing Reactive Blue 4 by a bacterial consortium of Salmonella subterranea and Paenibacillus polymyxa

Anaerobic biodegradability of wastewater (3,000 mg CODcr/l) containing 300 mg/l Reactive Blue 4, with different co-substrates, glucose, butyrate and propionate by a bacterial consortium of Salmonella subterranea and Paenibacillus polymyxa, concomitantly with hydrogen production was investigated at 35°C. The accumulative hydrogen production at 3,067 mg CODcr/l was obtained after 7 days of incubation with glucose, sludge, the bacterial consortium. The volatile fatty acids, residual glucose and the total organic carbon were correlated to hydrogen obtained. Interestingly, the bacterial consortium possess decolorization ability showing approximately 24% dye removal after 24 h incubation using glucose as a co-substrate, which was about two and eight times those of butyrate (10%), propionate (12%) and control (3%), respectively. RB4 decolorization occurred through acidogenesis, as high volatile fatty acids but low methane was detected. The bacterial consortium will be the bacterial strains of interest for further decolorization and hydrogen production of industrial waste water.     

Autophagy in the thymic epithelium is dispensable for the development of self-tolerance in a novel mouse model

The thymic epithelium plays critical roles in the positive and negative selection of T cells. Recently, it was proposed that autophagy in thymic epithelial cells is essential for the induction of T cell tolerance to self antigens and thus for the prevention of autoimmune diseases. Here we have tested this hypothesis using mouse models in which autophagy was blocked specifically in epithelial cells expressing keratin 14 (K14), including the precursor of thymic epithelial cells. While the thymic epithelial cells of mice carrying the floxed Atg7 gene (ATG7 f/f) showed a high level of autophagy, as determined by LC3 Western blot analysis and fluorescence detection of the recombinant green fluorescent protein (GFP)-LC3 reporter protein on autophagosomes, autophagy in the thymic epithelium was efficiently suppressed by deletion of the Atg7 gene using the Cre-loxP system (ATG7 f/f K14-Cre). Suppression of autophagy led to the massive accumulation of p62/sequestosome 1 (SQSTM1) in thymic epithelial cells. However, the structure of the thymic epithelium as well as the organization and the size of the thymus were not altered in mutant mice. The ratio of CD4 to CD8-positive T cells, as well as the frequency of activated (CD69+) CD4 T cells in lymphoid organs, did not differ between mice with autophagy-competent and autophagy-deficient thymic epithelium. Inflammatory infiltrating cells, potentially indicative of autoimmune reactions, were present in the liver, lung, and colon of a similar fraction of ATG7 f/f and ATG7 f/f K14-Cre mice. In contrast to previously reported mice, that had received an autophagy-deficient thymus transplant, ATG7 f/f K14-Cre mice did not suffer from autoimmunity-induced weight loss. In summary, the results of this study suggest that autophagy in the thymic epithelium is dispensable for negative selection of autoreactive T cells.     

Solid phase synthesis of novel asymmetric hydrophilic head cholesterol-based cationic lipids with potential DNA delivery

Twenty-four asymmetric divalent head group cholesterol-based cationic lipids were designed and synthesized by parallel solid phase chemistry. These asymmetric head groups composed of amino functionality together with trimethylamino, di(2-hydroxyethyl)amino or guanidinyl groups. Spacers between cationic heads and linker were both equal and unequal in length. These lipids were subjected to evaluation for DNA binding affinities by gel retardation assay and were screened for their transfection efficiency on HEK293 cells. Cationic lipids with equal chain length exhibited high transfection efficiency when polar part contained asymmetric polar heads. In contrast, lipids with unequal chain length exhibited high transfection efficiency when polar part contained symmetric heads. According to the optimal formulation, seven lipids exhibited higher transfection efficiency than the commercially available transfection agents, Effectene?, DOTAP and DC-Chol, to deliver DNA into PC3 human prostate adenocarcinoma cells. 3β-[N-(N′-Guanidinyl)-2′-aminoethyl)-N-(2-aminoethyl)carbamoyl] cholesterol (5) bearing amino and guanidinyl polar heads exhibited highest transfection efficiency with minimal toxicity. The morphology of active liposomes was observed by transmission electron microscopy (TEM) and size of liposomes were around 200–700 nm.     

High transfection efficiency and low toxicity cationic lipids with aminoglycerol–diamine conjugate

The solid phase synthesis of a library of aminoglycerol–diamine conjugate-based transfection agents having urea linkage between diverse length of diamines and various lengths of hydrophobic tails is described. These compounds were characterized and structure–activity relationships were determined for DNA binding and transfection ability when formulated as cationic liposomes. Cationic lipids with short spacer length and short hydrophobic tails bound to DNA and delivered DNA into HEK293 cells more efficient than those with longer ones. Transfection efficiency of some of the cationic liposomes was superior to that of the commercial transfection agents, Effectene^TM_, DOTAP and DC-Chol. The lipids 6Ab and 6Bb did not require the helper lipid DOPE to produce high-efficiency transfection of human cells while displaying minimal cytotoxicity. This suggests that these newly described aminoglycerol-based lipids should be very promising in liposome-mediated gene delivery and illustrate the potential of solid phase synthesis method for non-viral vector discovery.     

The performance of vetivers (Chrysopogon zizaniodes and Chrysopogon nemoralis) on heavy metals phytoremediation: laboratory investigation

Abstract

Phytoremediation with vetiver was investigated in relation to heavy metal contaminated soil in Thailand. The work compared the performance of two species of vetiver named Songkhla 3 (Chrysopogon zizaniodes) and Prachuap Khiri Khan (Chrysopogon nemoralis) in absorbing lead, zinc, and cadmium in contaminated soils. Toxicity Characteristic Leaching Procedure (TCLP), and Allium tests were conducted to determine toxicity of treated soil. Ethylenediaminetetraacetic acid (EDTA) was also used to increase heavy metals concentration in solution in soil, which led to an increase in translocation and bioaccumulation factors. In general, results showed that concentration of heavy metals decreased in soil and increased in both the shoots and roots of vetivers during a 4-month treatment period. TCLP results indicated that the concentration of zinc and cadmium in contaminated soil was reduced over treatment time, and significantly increased after EDTA was applied. To confirm vetiver performance in phytoremediation, Allium testing showed that remained heavy metals in treated soils had no effect on nucleus aberration. Songkhla 3 and Prachuap Khiri Khan showed similar trends in their ability to remediate lead, zinc, and cadmium from contaminated soil. Both species could accumulate higher concentrations of heavy metals in their shoots and roots over time, and with EDTA application.     

Targeted deletion of Atg5 reveals differential roles of autophagy in keratin K5-expressing epithelia

Autophagy contributes to the homeostasis of many tissues, yet its role in epithelia is incompletely understood. A recent report proposed that Atg5-dependent autophagy in thymic epithelial cells is essential for their function in the negative selection of self-reactive T-cells and, thus, for the suppression of tissue inflammation. Here we crossed mice carrying floxed alleles of the Atg5 gene with mice expressing the Cre recombinase under the control of the keratin K5 promoter to suppress autophagy in all K5-positive epithelia. The efficiency of autophagy abrogation was confirmed by immunoanalyses of LC3, which was converted to the autophagy-associated LC3-II form in normal but not Atg5-deficient cells, and of p62, which accumulated in Atg5-deficient cells. Mice carrying the epithelium-specific deletion of Atg5 showed normal weight gain, absence of tissue inflammation, and a normal morphology of the thymic epithelium. By contrast, autophagy-deficient epithelial cells of the preputial gland showed aberrant eosinophilic staining in histology and premature degradation of nuclear DNA during terminal differentiation. Taken together, the results of this study suggest that autophagy is dispensable for the suppression of autoimmunity by thymic epithelial cells but essential for normal differentiation of the preputial gland in mice.     

Aureobasidium pullulans as a source of liamocins (heavy oils) with anticancer activity

Liamocins are structurally unique, heavier-than-water “oils” produced by certain strains of Aureobasidium pullulans. The aim of the current study is to identify new sources of liamocins and evaluate their potential as anticancer agents. Nine strains of A. pullulans from phylogenetic clades 8, 9, and 11 were examined for the first time for production of liamocins. Strains in these clades have only been isolated from tropical environments, and all strains tested here were from various locations in Thailand. Strains RSU 9, RSU 21, and RSU 29, all from clade 11, produced from 7.0 to 8.6 g liamocins/l from medium containing 5 % sucrose. These are the highest yields of liamocins that we have found thus far. These strains also produced from 9.4 to 17 g pullulan/l. The structural identity of liamocins was confirmed by matrix-assisted laser desorption/ionization mass spectrometry; differential spectra were obtained in which the dominant ion was either at about m/z 805.5 or m/z 949.6, consistent with the structure of liamocins. Liamocins from A. pullulans strains RSU 9 and RSU 21 inhibited two human breast cancer cell lines and a human cervical cancer cell line (IC₅₀ values of 32.2 ± 1.4 to 63.1 ± 2.4 μg liamocins/ml) but were not toxic to a normal cell line. Liamocins weakly inhibited a strain of Enterococcus faecalis, but did not inhibit strains of Lactobacillus fermentum, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Thus, A. pullulans phylogenetic clade 11 is a promising source of liamocins, and these compounds merit further examination as potential anticancer agents.