Physicochemical and structural characterization of biosurfactant produced by <Emphasis Type="Italic">Pleurotus djamor</Emphasis> in solid-state fermentation

Biosurfactants are amphiphilic compounds produced by several microorganisms that reduce the surface tension. Low toxicity, optimal activity in extreme conditions, biodegradability and production from several wastes are main advantages of biosurfactants as compared to synthetic surfactants. Production of biosurfactant by a white rot fungus Pleurotus djamor on sunflower seed shell in solid-state fermentation was determined by emulsification indexes, oil spreading activity and surface tension (28.82 ± 0.3mN/m) measurement. The critical micelle concentration was detected as 0.964 ± 0.09 mg/mL. Also, the chemical and physicochemical properties of the biosurfactant produced were investigated. Considering the results of the chemical contents analysis, HPLC, FT-IR and ¹H-NMR, it can be concluded that the produced biosurfactant has a complex structure. Besides, resistance of its activity to environmental factors such as temperature, pH and salt concentration, as well as its thermal stability, were investigated. Additionally, the produced biosurfactant formed stabile emulsions with different hydrocarbons. Lastly, the performance of removing waste frying oil from contaminated sand of produced biosurfactant was detected as 76.57 ± 6%. Owing to its high emulsification capacity, low surface tension and critical micelle concentration, the biosurfactant, shows great potential for use in hydrocarbon removal applications.     

p53 functions as a cell cycle control protein in osteosarcomas.

Mutations in the p53 gene have been associated with a wide range of human tumors, including osteosarcomas. Although it has been shown that wild-type p53 can block the ability of E1a and ras to cotransform primary rodent cells, it is poorly understood why inactivation of the p53 gene is important for tumor formation. We show that overexpression of the gene encoding wild-type p53 blocks the growth of osteosarcoma cells. The growth arrest was determined to be due to an inability of the transfected cells to progress into S phase. This suggests that the role of the p53 gene as an antioncogene may be in controlling the cell cycle in a fashion analogous to the check-point control genes in Saccharomyces cerevisiae.     

Examination of serum and bovine serum albumin as shear protective agents in agitated cultures of hybridoma cells.

A murine hybridoma cell line (167.4G5.3) was cultured in batch mode using IMDM containing different serum concentrations and bovine serum albumin (BSA). Cell growth and death, metabolism and antibody production were studied in these cultures. The cells were more susceptible to shear in the stationary and in the decline phase of growth as evidenced by higher death rates. Cell growth was best at high serum concentrations with high specific growth and low specific death rates. When BSA was used instead of serum in IMDM, no protective effect was observed. Cell metabolism and monoclonal antibody production rates were not influenced by the level of serum or by BSA. The use of serum in commercial serum-free media (OPTI-MEM) also resulted in no change in both growth and death rates.     

Methionine metabolism and ultrastructural changes with D-galactosamine in isolated rat hepatocytes

The biochemical and morphological effects of 2, 10 and 100 mM of D-galactosamine (GalN) were studied in isolated rat hepatocytes during 2 h of incubation. Lactate dehydrogenase (LDH), alanine aminotransferase (ALAT) and cell viability did not change, whatever the concentration used. The variations observed, which were dose dependent, included a large drop in ATP levels and inhibition of RNA and protein synthesis. A very high concentration of GalN was necessary, however, to induce a significant decline in methionine adenosyltransferase activity compared to control cells.The use of L-[methyl-¹⁴C]methionine during cell incubation with GalN demonstrated a decrease of S-adenosyl-L-methionine (SAMe) and an accumulation of L-methionine content related to the GalN concentration. These results suggested that an hepatotoxic agent such as GalN was able to induce disturbances of methionine metabolism.Some of the ultrastructural changes observed were different from those previously found in vivo, in rats given GalN intraperitoneally, underlining the marked difference between in vivo and in vitro intoxication.     

Promising anticancer activity of a lichen,Parmelia sulcata Taylor,against breast cancer cell lines and genotoxic effect on human lymphocytes

Plants are still to be explored for new anti-cancer compounds because overall success in cancer treatment is still not satisfactory. As a new possible source for such compounds, the lichens are recently taking a great attention. We, therefore, explored both the genotoxic and anti-growth properties of lichen species Parmelia sulcata Taylor. The chemical composition of P. sulcata was analyzed with comprehensive gas chromatography–time of flight mass spectrometry. Anti-growth effect was tested in human breast cancer cell lines (MCF-7 and MDA-MB-231) by the MTT and ATP viability assays, while the genotoxic activity was studied by assays for micronucleus, chromosomal aberration and DNA fragmentation in human lymphocytes culture. Cell death modes (apoptosis/necrosis) were morphologically assessed. P. sulcata inhibited the growth in a dose-dependent manner up to a dose of 100 μg/ml and induced caspase-independent apoptosis. It also showed genotoxic activity at doses (>125 μg/ml) higher than that required for apoptosis. These results suggest that P. sulcata may induce caspase-independent apoptotic cell death at lower doses, while it may be genotoxic at relatively higher doses.     

Effect of Putrescine on Low-Temperature Acclimation in <i>Chlamydomonas reinhardtii</i>

Putrescine is reported to be necessary for cold acclimation under low-temperature stress. In this study, the effect of low-temperature on some physiological and biochemical parameters has been investigated using the green algae Chlamydomonas reinhardtii. The lipid peroxidation rate, amount of Rubisco protein, activities of antioxidant enzymes and gene expression of polyamine biosynthesis (odc2, and spd1), heat shock proteins (hsp70c, hsp90a, and hsp90c), and PSII repair mechanisms (psba, rep27, and tba1) were determined to understand the low-temperature response. Exogenous putrescine application significantly increased Rubisco protein concentration and catalase enzyme activities under low-temperature stress. Moreover, real-time RT-PCR results and gene expression analysis showed that polyamine metabolism induced gene expression at low-temperatures in the first 24 h. In the same way, the gene expression of heat shock proteins (hsp70c, hsp90a, and hsp90c) decreased under low-temperature treatment for 72 h; however, application of putrescine enhanced the gene expression in the first 24 h. The results obtained indicated that molecular response in the first 24 h could be important for cold acclimation. The psba and tba1 expressions were reduced under low-temperatures depending on the exposure time. In contrast, the exogenous putrescine enhanced the expression level of the psba response to low-temperature at 24 and 72 h. The results obtained in this study indicate that putrescine could play a role in the PS II repair mechanisms under low-temperature stress.     

A fluorescent biosensor based on acetylcholinesterase and 5-oxazolone derivative immobilized in polyvinylchloride (PVC) matrix

A new 2-phenyl-4-[4-(1,4,7,10-tetraoxa-13-azacyclopentadecyl)benzylidene]-5-oxazolone (CPO) derivative was utilized to develop an optical acetylcholinesterase (AChE) biosensor in which the azlactone derivative was embedded in plasticized polyvinylchloride (PVC) matrix. The sensor system was calibrated for the detection of acetylcholine (ACh) and donepezil which is a competitive cholinesterase (ChE) inhibitor. Two different biosensing systems were developed by using AChE enzyme in solution and immobilized together with the fluorescent derivative (CPO) doped in transparent PVC membrane. The enzymatic hydrolysis of ACh was monitored by following changes in the pH induced fluorescence intensity. When AChE enzyme was immobilized in PVC matrix together with CPO, the sensitivity of the measuring system has increased approximately three times for ACh, in comparison to the sensing system where AChE enzyme was in solution phase.

The photophysical parameters of CPO were also examined in solvents of tetrahydrofuran (THF), acetonitrile (ACN) and dichloromethane (DCM) and in solid matrix of PVC. The azlactone derivative exhibits excellent photostability in PVC matrix.     

Chemical composition and in vitro antibacterial activity of Seseli libanotis

Summary The antibacterial efficacy of the methanol extract of the aerial parts of Seseli libanotis by using disc diffusion assay against 107 strains from 52 bacterial species and the chemical composition of the essential oil using GC/MS analysis were studied for the first time. The minimum inhibitory concentrations (MIC) of single compounds were determined by the microbroth dilution method. Gas chromatography–mass spectrophotometry analyses allowed 13 compounds to be determined; the main constituents of the essential oil of aerial parts of Seseli libanotis were trans-caryophyllene (20.39%), spathulenol (11.89%), (−)-caryophyllene oxide (11.47%), euasarone (10.66%) and delta-cadinene (9.16%). The methanol extract of Seseli libanotis had a broad-spectrum antibacterial activity (>14 mm inhibition zone in diameter) in particular against Bacillus cereus, Bacillus dipsauri, Bacillus lentimorbus, Bacillus sphaericus, Bacillus subtilis, Corynebacterium ammoniagenes, Kocuria rosea, Neisseria subflava and Micrococcus lylae. These inhibitory effects are interesting in relation to the prevention of microbial contamination in foods.