► Tetrahymena thermophila was exposed to TiO2 particles at sub-toxic concentrations. ► Exposure to TiO2 particles resulted in changed cell membrane in fatty acid profile resulting in increased ...membrane rigidity. ► Altered cell membrane composition is not accompanied by lipid peroxidation or ROS elevation. ► Particles were detected in food vacuoles where filling and subsequent release was followed.
We provide experimental evidence that changes in the membrane fatty acid profile of Tetrahymena thermophila incubated with nano- or bulk TiO2 particle are not accompanied by ROS generation or lipid peroxidation. Consequently these changes are interpreted as acclimation to unfavorable conditions and not as toxic effects. T. thermophila cells were exposed to TiO2 particles at different concentrations for 24h at 32°C. Treatment of cultures with nano- and bulk TiO2 particles resulted in changes of membrane fatty acid profile, indicating increased membrane rigidity, but no lipid peroxidation or ROS generation was detected. There were no differences in membrane composition when T. thermophila was exposed to nanosized or bulk-TiO2 particles. We also observed reversible filling of food vacuoles, but this was different in case of nano- or bulk TiO2 exposure. Our results suggest that interactions of particles and cell membranes are independent of oxidative stress.
Key biological functions involved in cell survival have been studied to understand the difference between the impact of exposure to TiO
2
nanoparticles (TiO
2
-NPs) and their bulk counterparts ...(bulk-TiO
2
). By selecting a unicellular eukaryotic model organism and applying proteomic analysis an overview of the possible impact of exposure could be obtained. In this study, we investigated the early response of unicellular eukaryotic protozoan Tetrahymena thermophila exposed to TiO
2
-NPs or bulk-TiO
2
particles at subtoxic concentrations for this organism. The proteomic analysis based on 2DE + nLC-ESI-MS/MS revealed 930 distinct protein spots, among which 77 were differentially expressed and 18 were unambiguously identified. We identified alterations in metabolic pathways, including lipid and fatty acid metabolism, purine metabolism and energetic metabolism, as well as salt stress and protein degradation. This proteomic study is consistent with our previous findings, where the early response of T. thermophila to subtoxic concentrations of TiO
2
particles included alterations in lipid and fatty acid metabolism and ion regulation. The response to the lowest TiO
2
-NPs concentration differed significantly from the response to higher TiO
2
-NPs concentration and both bulk-TiO
2
concentrations. Alterations on the physiological landscape were significant after exposure to both nano- and bulk-TiO
2
; however, no toxic effects were evidenced even at very high exposure concentrations. This study confirms the relevance of the alteration of the lipid profile and lipid metabolism in understanding the early impact of TiO
2
-NPs in eukaryotic cells, for example, phagocytosing cells like macrophages and ciliated cells in the respiratory epithelium.
Every day many people suffer from intestinal diseases. These disorders can result from pathogens like bacteria, fungi, parasites and viruses, but the causes of non-infectious intestinal disorders and ...colorectal cancers remain to be elucidated. Disturbances to the normal gut flora (the microbiota) are central to the development of many, if not all, of these disorders. Disturbed gut microbiota is a prelude to public health issues like traveller's-, antibiotic- and Clostridium difficile-associated diarrhoea, irritable bowel syndrome, inflammatory bowel disease, and colorectal cancers. This book discusses the way intestinal disorders affect the microbiota, how the disturbed microbiotal balance leads to enteric disorders and the ways to prevent these disorders. Further his book explores the potential of probiotics (live microorganisms that when ingested bring a health benefit) in treating enteric disorders by analysing the probiotic genome through proteomics, metabolomics and functional assays. Discussed is how the ingestion of specific microorganisms repairs the disturbed microbiota and subsequently ameliorates enteric disorders. Finally this book addresses how genetic engineering and biotechnology will contribute to the development of effective and safe designer probiotics.
Aim: To evaluate the influence of wheat bran and oat bran on the oxidative stress induced by a high proportion of fat in the diet. Methods: Forty-eight growing pigs were penned individually and after ...an adaptation period divided into four groups. All groups received isocaloric daily rations composed of basal diet which was then supplemented with: starch (controls; CONT), linseed oil (OIL), linseed oil and wheat bran, or linseed oil and oat bran. The experimental period lasted 14-days. The oxidative stress was evaluated by measuring the malondialdehyde (MDA) concentration in blood plasma, the 48-hour urinary MDA excretion, and the degree of leukocyte nuclear DNA damage. Results: In comparison with the CONT group, a significant increase in the MDA concentration in blood plasma and in the MDA excretion in urine was found in the OIL group. The degree of DNA damage in the OIL group was also significantly higher. In comparison with the OIL group, the wheat bran and oat bran supplementation significantly reduced the 24-hour MDA excretion in urine and reduced the degree of DNA damage in leukocytes to the level of the CONT group. Conclusion: The results of the experiments confirmed that a high wheat bran and oat bran intake effectively reduces oxidative stress induced by a high-fat diet.
Reactive oxygen species (ROS) are not only generated in conditions of cellular stress but are also constitutively produced in most cell types by specific metabolic processes. This research focused on ...a potential antioxidant Trolox (model compound for α-tocopherol), with the aim to establish exact mechanisms of Trolox intracellular oxidation prevention on model organism
Saccharomyces cerevisiae. Measuring intracellular oxidation of Trolox-treated yeast cells revealed that Trolox decreased intracellular oxidation during normal metabolism. Trolox treatment decreased cyto- and geno-toxicity of treated yeast cells in MES buffer, lowered intracellular oxidation, decreased intracellular peroxides formation, and increased H
2O
2 degradation and superoxide quenching yeast extract ability.
This study suggests that Trolox treatment provides prevention against intracellular ROS formation. Trolox application as therapeutic agent against intracellular ROS formation would be worth considering. Additionally, results indicate that yeasts are good model organisms for studying intracellular oxidation and oxidative stress. The obtained results on yeast cells might be useful to direct further human-related search for the Trolox evaluation as a human supplement used for protecting cells against intracellular free radical formation.
1 Institute of Animal Physiology and Genetics, Czech Academy of Sciences, P átelství 560, 104 00, Prague 10, Uh ín ves, Czech Republic
2 University of Ljubljana, Biotechnical Faculty, Zootechnical ...Dept, Dom ale, Slovenia
3 Hokkaido University, Graduate School of Agriculture, Sapporo 060-8589, Japan
Correspondence Jan Kope n kopecny{at}iapg.cas.cz
Two novel Gram-negative, anaerobic, non-spore-forming, butyrate-producing bacterial species, strains Mz 5 T and JK 615 T , were isolated from the rumen fluid of cow and sheep. Both strains were curved rods that were motile by means of single polar or subpolar flagellum and common in the rumen microbial ecosystem. Strain Mz 5 T produced high xylanase, proteinase, pectin hydrolase and DNase activities; 1,4- -endoglucanase was also detected in the culture medium. The bacterium utilized a wide range of carbohydrates. Glucose was fermented to formate, butyrate, lactate, succinate and ethanol. The DNA G+C content was 42·1 mol%. The complete 16S rDNA sequence was obtained and phylogenetic relationships were determined. Strain Mz 5 T and related isolates were located in clostridial cluster XIVa and were closely related to Pseudobutyrivibrio ruminis , Butyrivibrio crossotus , Roseburia cecicola and Eubacterium rectale . The name proposed for this novel bacterium is Pseudobutyrivibrio xylanivorans ; the type strain is Mz 5 T (=DSM 14809 T =ATCC BAA-455 T ). Strain JK 615 T produced no fibrolytic activity, but utilized a wide range of carbohydrates. Glucose was fermented to formate, acetate, butyrate and ethanol. The DNA G+C content was 44·8 mol%. The complete 16S rDNA sequence was obtained and phylogenetic relationships were determined. Strain JK 615 T was located in clostridial cluster XIVa and was closely related to Clostridium proteoclasticum , Butyrivibrio fibrisolvens and Eubacterium halii . The name proposed for this novel bacterium is Butyrivibrio hungatei ; the type strain is JK 615 T (=DSM 14810 T =ATCC BAA-456 T ).
Published online ahead of print on 9 August 2002 as DOI 10.1099/ijs.0.02345-0.
The EMBL accession numbers for the 16S rDNA sequences of Pseudobutyrivibrio xylanivorans Mz 5 T , Pseudobutyrivibrio ruminis JK 626, Pseudobutyrivibrio xylanivorans JK 23/2, Pseudobutyrivibrio xylanivorans JK 633, Clostridium proteoclasticum UC 142 and Butyrivibrio hungatei JK 615 T are AJ428548AJ428553, respectively.
Pseudobutyrivibrio xylanivorans strain Mz5(T), an anaerobic bacterium (originating from the rumen of a Holstein-Friesian cow), has some attributes that make it a possible probiotic strain (very ...active hydrolases, bacteriocin and conjugated linoleic acid production). For the estimation of its adhesion ability, the adhesion test on Caco-2 cells was introduced and adapted. The adhesion was performed in an anaerobic glove box in standard 24-well plates at neutral pH for 30 min. The best method for separation of the adhered bacteria from Caco-2 cells appeared to be homogenization with an automatic pipette. The number of adhered bacteria was too small to be determined microscopically, so a new approach, i.e. detection of the apparent lag phase in liquid growth medium was tested. Under the selected assay conditions 1.04 bacterial cells from the late exponential phase adhered to one Caco-2 cell, which confirms the adhesion capability of P. xylanivorans Mz5(T). The adapted adhesion test using Caco-2 cells is suitable for estimation of adhesion capability of anaerobic bacteria.
Rumen bacterium Pseudobutyrivibrio xylanivorans Mz5 produces multiple xylanases that account for its high xylanolytic activity. The smallest xylanase (XynT) accounts for the majority of the activity ...in the later growth phases. This enzyme was purified to homogeneity by ammonium sulfate precipitation and hydrophobic interaction chromatography and had a MW of 30 kDa. Electrophoresis under native conditions and isoelectric focusing showed microheterogeneity of XynT, with two pIs: 5.1 and 5.9. This could be due to different posttranslational processing, partial proteolysis or aggregation. Nevertheless, the single N-terminal sequence revealed the relatedness of XynT to xylanases from family 11 of glycosyl hydrolases. XynT is most active in the physiological conditions found in bovine rumen (38 degree C, pH 5.6) and acts as an endoxylanase that releases xylooligosaccharides from xylan. It is inactive towards other polysaccharides. XynT could be used as a feed additive for animals in order to diminish health problems and enhance proliferation of beneficial microflora.
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