Effect of stabilization on biomass activity

The study aimed to compare aerobic and aerobic/anoxic stabilization processes in terms of organic matter and the biomass removal efficiencies using a municipal sludge sample. The efficiency of stabilization process was assessed monitoring suspended solids (SS), volatile suspended solids (VSS), total and dissolved organic carbon (TOC, DOC), nitrate, nitrite, and phosphate parameters. The oxygen uptake rate (OUR) measurements were conducted to determine active biomass concentration. On the 30th day of the aerobic stabilization, the SS, VSS and TOC removal efficiencies were 22%, 28% and 55%, respectively. Under aerobic/anoxic conditions, removal efficiencies for SS, VSS and TOC were 25%, 27% and 67%. On the 17th day of the stabilization, SS and VSS removal rates were 60 mg SS/L day and 47 mg VSS/L day for aerobic and 102 mg SS/L day and 63 mg VSS/L day for aerobic/anoxic conditions, respectively. These findings reflected the higher stabilization performance of the aerobic/anoxic conditions. Based on respirometric results, the ratios of the active biomass were decreased to 30% and 24% for the 17th and 30th day of the aerobic stabilization, respectively. Such results have significant implications relative to the activity decrease quantification of the biomass as well as its further application potentials after aerobic or aerobic/anoxic sludge stabilization.     

Melatonin ameliorates cardiac remodelling in fructose-induced metabolic syndrome rat model by using genes encoding cardiac potassium ion channels

Molecular Biology Reports - Metabolic syndrome comprises a group of disorders, including cardiac abnormalities. Ventricular arrhythmias observed in metabolic syndrome are due to the impaired...     

The role of aromatic residues in the hydrophobic core of the villin headpiece subdomain

Small autonomously folding proteins are of interest as model systems to study protein folding, as the same molecule can be used for both experimental and computational approaches. The question remains as to how well these minimized peptide model systems represent larger native proteins. For example, is the core of a minimized protein tolerant to mutation like larger proteins are? Also, do minimized proteins use special strategies for specifying and stabilizing their folded structure? Here we examine these questions in the 35‐residue autonomously folding villin headpiece subdomain (VHP subdomain). Specifically, we focus on a cluster of three conserved phenylalanine (F) residues F47, F51, and F58, that form most of the hydrophobic core. These three residues are oriented such that they may provide stabilizing aromatic–aromatic interactions that could be critical for specifying the fold. Circular dichroism and 1D‐NMR spectroscopy show that point mutations that individually replace any of these three residues with leucine were destabilized, but retained the native VHP subdomain fold. In pair‐wise replacements, the double mutant that retains F58 can adopt the native fold, while the two double mutants that lack F58 cannot. The folding of the double mutant that retains F58 demonstrates that aromatic–aromatic interactions within the aromatic cluster are not essential for specifying the VHP subdomain fold. The ability of the VHP subdomain to tolerate mutations within its hydrophobic core indicates that the information specifying the three dimensional structure is distributed throughout the sequence, as observed in larger proteins. Thus, the VHP subdomain is a legitimate model for larger, native proteins.     

Microbial transformation of pentachloronitrobenzene under nitrate reducing conditions

The effect of pentachloronitrobenzene (PCNB) on denitrification was assessed with two denitrifying cultures (PCNB-free control and PCNB-acclimated) developed from a contaminated estuarine sediment. PCNB was transformed to pentachloroaniline (PCA) in the PCNB-acclimated culture repeatedly amended with 0.1 μM PCNB, but further dechlorination or degradation of PCA was not observed for almost 1 year. The effect of PCNB on denitrification was also investigated with the PCNB-free control culture. PCNB at an initial concentration of 13 μM was transformed to PCA simultaneously with nitrate reduction but only after the nitrate concentration was at or below 20 mg N/l. PCNB addition at an initial concentration of 13 μM to the control denitrifying culture developed as PCNB-free culture resulted in a transient accumulation of nitric oxide (NO) and nitrous oxide (N₂O). Similarly to the PCNB-acclimated culture, PCNB transformation to PCA started when the nitrate concentration decreased to about 20 mg N/l. A low degree of nitro group removal resulting in the formation of pentachlorobenzene (PeCB) was also observed in the control culture when amended with 13 μM PCNB. Further transformation or degradation of PCA was not observed in all cultures maintained under active nitrate reducing conditions. Based on the results of this study, the presence of nitrate at low concentrations in anoxic/anaerobic soil and sediments is not expected to negatively affect the biotransformation of PCNB to PCA, but dechlorination or degradation of PCA is not expected under active nitrate reducing conditions.     

Ultrastructural aspects and programmed cell death in the tapetal cells of Lathyrus undulatus Boiss

Programmed cell death (PCD) in the tapetum of Lathyrus undulatus L. was analyzed based on light, fluorescence and electron microscopy to characterize its spatial and temporal occurrence. Development and processes of PCD in secretory tapetal cells of Lathyrus undulatus L. were correlated with the sporogenous cells and pollen grains. At early stages of development the tapetal cells appeared similar to pollen mother cells, structurally. Concurrent with meiosis, tapetum expanded both tangentially and radially as vacuoles increased in size. Tapetal cells most fully developed at young microspore stage. However, tapetum underwent substantial changes in cell organization including nucleus morphology monitored by DAPI. The TUNEL staining confirmed the occurrence of intra-nucleosomal DNA cleavage. In addition to nuclear degeneration which is the first hallmark of PCD other diagnostic features were observed at vacuolated microspore stage intensely; such as chromatin condensation at the periphery of the nucleus, nuclear membrane degeneration, chromatin release to the cytoplasm, vacuole collapse according to tonoplast rupture, shrinkage of the cytoplasm, the increase and enlargement of the endoplasmic reticulum cisternae and disruption of the plasma membrane. After vacuole collapse due to possible release of hydrolytic enzymes the cell components degraded. Tapetal cells completely degenerated at bicellular pollen stage.     

Impact of tannic acid on blood pressure,oxidative stress and urinary parameters in L-NNA-induced hypertensive rats

Hypertension is a major health problem with increasing prevalence around the world. Tannic acid is water-soluble polyphenol that is present in tea, green tea, coffee, red wine, nuts, fruits and many plant foods. It has been reported to serve as an antioxidant or a pro-oxidant depending on the type of cells and its concentration. The purpose of our study was to evaluate the effect of tannic acid on systolic blood pressure, oxidative stress and some urinary parameters in the rat model of essential hypertension. Blood pressures of all rats were measured using the tail-cuff method. The nitric oxide synthase inhibitor N (omega)-nitro-L-arginine was administered orally at a dose of 0.5 g/l/day for 15 days to rats in order to create an animal model of hypertension. Tannic acid was intraperitoneally injected at a dose of 50 mg/kg for 15 days. Superoxide dismutase, catalase activity and the concentration of malondialdehyde (MDA) were determined in blood plasma and homogenates of heart, liver and kidney. In order to evaluate renal functions, urine pH, urine volume, urine creatine, uric acid, and urea nitrogen values were measured. Compared with the hypertension group, a decrease in MDA concentrations of heart tissue (p < 0.01), urea nitrogen values (p < 0.01) and urine volumes (p < 0.001) were established in hypertension + tannic acid group. There was also a decrease in blood pressure values (20th and 30th days) of this group, but there was no a statistical difference according to hypertension group. The findings of our research show the effect of tannic acid in lowering blood pressure in hypertensive rats.     

Evidence for upregulated repair of oxidatively induced DNA damage in human colorectal cancer

Carcinogenesis may involve overproduction of oxygen-derived species including free radicals, which are capable of damaging DNA and other biomolecules in vivo. Increased DNA damage contributes to genetic instability and promote the development of malignancy. We hypothesized that the repair of oxidatively induced DNA base damage may be modulated in colorectal malignant tumors, resulting in lower levels of DNA base lesions than in surrounding pathologically normal tissues. To test this hypothesis, we investigated oxidatively induced DNA damage in cancerous tissues and their surrounding normal tissues of patients with colorectal cancer. The levels of oxidatively induced DNA lesions such as 4,6-diamino-5-formamidopyrimidine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 8-hydroxyguanine and (5'S)-8,5'-cyclo-2'-deoxyadenosine were measured by gas chromatography/isotope-dilution mass spectrometry and liquid chromatography/isotope-dilution tandem mass spectrometry. We found that the levels of these DNA lesions were significantly lower in cancerous colorectal tissues than those in surrounding non-cancerous tissues. In addition, the level of DNA lesions varied between colon and rectum tissues, being lower in the former than in the latter. The results strongly suggest upregulation of DNA repair in malignant colorectal tumors that may contribute to the resistance to therapeutic agents affecting the disease outcome and patient survival. The type of DNA base lesions identified in this work suggests the upregulation of both base excision and nucleotide excision pathways. Development of DNA repair inhibitors targeting both repair pathways may be considered for selective killing of malignant tumors in colorectal cancer.     

Chemotaxis of Pseudomonas stutzeri OX1 and Burkholderia cepacia G4 toward chlorinated ethenes

The chemotactic responses of Pseudomonas putida F1, Burkholderia cepacia G4, and Pseudomonas stutzeri OX1 were investigated toward toluene, trichloroethylene (TCE), tetrachloroethylene (PCE), cis-1,2-dichloroethylene (cis-DCE), trans-1,2-dichloroethylene (trans-DCE), 1,1-dichloroethylene (1,1-DCE), and vinyl chloride (VC). P. stutzeri OX1 and P. putida F1 were chemotactic toward toluene, PCE, TCE, all DCEs, and VC. B. cepacia G4 was chemotactic toward toluene, PCE, TCE, cis-DCE, 1,1-DCE, and VC. Chemotaxis of P. stutzeri OX1 grown on o-xylene vapors was much stronger than when grown on o-cresol vapors toward some chlorinated ethenes. Expression of toluene-o-xylene monooxygenase (ToMO) from touABCDEF appears to be required for positive chemotaxis attraction, and the attraction is stronger with the touR (ToMO regulatory) gene.