Bismuth compounds are widely used in industrial processes and products. In medicine, bismuth salts have been applied in combination with antibiotics for the treatment of Helicobacter pylori infections, for the prevention of diarrhea, and in radioimmunotherapy. In the environment, bismuth ions can be biotransformed to the volatile bismuth compound trimethylbismuth (Me3Bi) by methanobacteria. Preliminary in-house studies have indicated that bismuth ions are methylated in the human colon by intestinal microflora following ingestion of bismuth-containing salts. Information concerning cyto- and genotoxicity of these biomethylated products is limited. In the present study, we investigated the cellular uptake of an organic bismuth compound [monomethylbismuth (III), MeBi (III)] and two other bismuth compounds [bismuth citrate (Bi-Cit) and bismuth glutathione (Bi-GS)] in human hepatocytes, lymphocytes, and erythrocytes using ICP-MS. We also analyzed the cyto- and genotoxic effects of these compounds to investigate their toxic potential. Our results show that the methylbismuth compound was better taken up by the cells than Bi-Cit and Bi-GS. All intracellularly detected bismuth compounds were located in the cytosol of the cells. MeBi (III) was best taken up by erythrocytes (36%), followed by lymphocytes (17%) and hepatocytes (0.04%). Erythrocytes and hepatocytes were more susceptible to MeBi (III) exposure than lymphocytes. Cytotoxic effects of MeBi (III) were detectable in erythrocytes at concentrations> 4 µM, in hepatocytes at> 130 µM, and in lymphocytes at> 430 µM after 24 h of exposure. Cytotoxic effects for Bi-Cit and Bi-GS were much lower or not detectable in the used cell lines up to a tested concentration of 500 µM. Exposure of lymphocytes to MeBi (III) (250 µM for 1 h and 25 µM / 50 µM for 24 h) resulted in significantly increased frequencies of chromosomal aberrations (CA) and sister chromatid exchanges (SCE), whereas Bi-Cit and Bi- GS induced neither CA nor SCE. Our study also showed an intracellular production of free radicals caused by MeBi (III) in hepatocytes but not in lymphocytes. These data suggest that biomethylation of bismuth ions by the intestinal microflora of the human colon leads to an increase in the toxicity of the primary bismuth salt.
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Antioxidant activity of hydrolyzed protein prepared from alkali-solubilized catfish protein isolates was studied. The isolates were hydrolyzed to 5, 15, and 30% degree of hydrolysis using the protease enzyme, Protamex. Hydrolyzed protein was separated into hydrolysates and soluble supernatants, and both of these fractions were studied for their metal chelating ability, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and their ability to inhibit the formation of thiobarbituric acid reactive substances (TBARS) in washed tilapia muscle containing tilapia hemolysate. Both hydrolysates and supernatants were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results showed that DPPH radical scavenging ability and reducing power of catfish protein hydrolysates decreased, whereas the ORAC value, metal chelating ability, and ability to inhibit TBARS increased, with an increase in the degree of hydrolysis. Hydrolysate samples showed higher DPPH radical scavenging ability and Fe3+ reducing ability, and supernatant samples had higher metal chelating ability. In general, low molecular weight (MW) peptides had high ORAC values and high metal chelating ability, and high MW peptides had a higher reducing power (FRAP) and were more effective in scavenging DPPH radicals. In a washed muscle model system, the ability of catfish protein hydrolysates and their corresponding supernatants to inhibit the formation of TBARS increased with an increase in the degree of hydrolysis.
Monoheme cytochromes of the C-type are involved in a large number of electron transfer processes, which play an essential role in multiple pathways, such as respiratory chains, either aerobic or anaerobic, and the photosynthetic electron transport chains. This study reports the biochemical characterization and the crystallographic structure, at 1.23 Å resolution, of a monoheme cytochrome c from the thermohalophilic bacterium Rhodothermus marinus. In addition to an α-helical core folded around the heme, common for this type of cytochrome, the X-ray structure reveals one unusual α-helix and a unique N-terminal extension, which wraps around the back of the molecule. Based on a thorough structural and amino acid sequence comparison, we propose R. marinus cytochrome c as the first characterized member of a new class of C-type cytochromes.
Enzymatically hydrolyzed fish protein hydrolysates could be used as a source of antioxidant nutraceuticals. In our current work, we have investigated alkali-solubilized tilapia (Oreochromis niloticus) protein hydrolysates for their ability to scavenge reactive oxygen species (ROS) and for their reducing power. Tilapia protein isolate was prepared by an alkaline solubilization technique and used as a substrate for enzyme hydrolysis. Cryotin, protease A 'Amano' 2, protease N 'Amano', Neutrase and Flavourzyme, were used separately to determine their effectiveness in hydrolyzing tilapia protein isolate. ROS scavenging ability was quantified using an isoluminol enhanced chemiluminescent assay in the presence of a) hydrogen peroxide or b) mononuclear cells isolated from human blood. Ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) of the hydrolysates using 2,2′-azinobis- (3-ethylbenzothiazoline-6-sulfonic acid) or 2,2′-azinobis-3-ethylbenzothiazoline-6- sulfonic acid (ABTS), were also investigated. Results showed that, in general, the TEAC, FRAP values and ROS scavenging ability of the hydrolysates increased with an increase in the degree of hydrolysis. Among the different hydrolysates, those prepared using Cryotin were most effective and Amano A2 hydrolysates were least effective in scavenging ABTS ·+ and ROS generated by hydrogen peroxide. However, FRAP assay showed that hydrolysates prepared using Flavourzyme were most effective, and Amano N and Neutrase hydrolysates were least effective in reducing ferric ions. No significant difference was observed among the hydrolysates produced with different enzymes in their ability to scavenge ROS generated by phorbol myristate acetate stimulated mononuclear cells. These results shed light on the in vitro ROS scavenging ability of alkali solubilized tilapia protein hydrolysates, as well as potential nutraceutical use of these hydrolysates.
Eighteen new microsatellite loci consisting of 10 di-, 5 tri-, 2 tetra- and 1 heptanucleotide repeats are introduced for the Atlantic cod (Gadus morhua L.). All loci were co-amplified in two polymerase chain reactions (plus two previously published microsatellites) and all products were clearly typed. The number of alleles per locus ranged from six (PGmo130) to 45 (PGmo76) and the observed heterozygosity ranged from 0.356 (PGmo130) to 0.957 (PGmo95). All loci except one followed Hardy – Weinberg expectations. Genetic linkage disequilibrium analysis between all pairs of loci did not yield any significant values.
Changes in the conformation of catfish (Ictalurus punctatus) myosin due to (i) cations (ii) alkaline pH and (iii) salt addition were determined using circular dichroism, tryptophan fluorescence, differential scanning calorimetry and hydrophobicity studies. The relation between conformation and storage modulus (G′) Of alkali treated myosin was studied. Two types of bases, NaOH and KOH were used for unfolding myosin under three alkaline conditions, pH 11.0, 11.5 and 12.0. Myosin, unfolded under alkali conditions was immediately refolded by adjusting pH back to 7.3. Subjecting myosin to alkaline conditions and subsequent readjustment to pH 7.3 increased the G′ Of thermally treated myosin. G′ Was affected by the presence or absence of salt during alkali treatments. When salt was present during alkali unfolding of myosin, the added salt stabilized the conformation of myosin against alkali unfolding and denaturation. In the absence of salt or when salt was added after refolding, myosin showed significantly higher denaturation and high G′ On heating and cooling. Among the different alkaline pH values, myosin treated at pH 11.0 showed higher G′. The type of anions influenced the conformation of myosin and the strength of gels. Treatment of myosin with KOH resulted in greater denaturation and higher gelling ability (G′) Compared to NaOH.
The antioxidant activities of alkali-treated tilapia protein hydrolysates were determined by their ability to inhibit the formation of lipid hydroperoxides (PV) and thiobarbituric acid reactive substances (TBARS) in a washed muscle model system and by their ability to inhibit DPPH free radicals and chelate ferrous ion in an aqueous solution. Protein isolates were prepared from tilapia white muscle using alkali solubilization at pH 11.0 and reprecipitation at pH 5.5. Protein hydrolysates were prepared by hydrolyzing the isolates using five different enzymes, Cryotin F, Protease A Amano, Protease N Amano, Flavourzyme, and Neutrase, to 7.5, 15, and 25% degrees of hydrolysis (DH). All of the protein hydrolysates significantly (p <0.05) inhibited the development of TBARS and PV. The antioxidant activity of the hydrolysates increased with the DH. Also, the antioxidant activity of the hydrolysates varied significantly (p <0.05) among the different enzymes. The ability of different enzyme-catalyzed protein hydrolysates to scavenge DPPH radicals was not reflected in their ability to inhibit oxidation in a washed tilapia model system. In a washed muscle model system, the hydrolysates prepared using Cryotin F were most effective and the hydrolysates prepared using Flavourzyme and Neutrase were least effective in inhibiting the development of TBARS and PV, whereas in an aqueous solution, hydrolysates prepared using Flavourzyme were most effective in scavenging DPPH radicals and chelating ferrous ions. Enzymatic hydrolysis decreased the size of tilapia protein hydrolysates and, in general, tilapia protein hydrolysates with low molecular weights were better antioxidants than those with high molecular weights.
BACKGROUND: Color of muscle foods plays a major role in consumer perception of meat quality. Carbon monoxide (CO) has been successfully used for improving the color of packaged meat and fish products. In this study, we wanted to investigate pre-mortem treatment of live tilapia using 100% CO for its ability to improve the color of frozen whole tilapia. We compared untreated and CO-treated whole, gutted tilapia, frozen for 2 and 4 months at - 20 ° C. Frozen tilapia samples were thawed overnight at 4 ° C, filleted and analyzed for their color, heme peak wavelength and CO concentration.
RESULTS: Euthanasia using CO significantly increased redness (a* value) and lightness (L* value) of tilapia white and red muscle. Frozen storage significantly (P <0.05) Decreased redness of both CO-treated and untreated tilapia. However, even after 4 months of frozen storage, a* -value of CO-treated tilapia was similar to fresh untreated tilapia fillets. Heme peak wavelengths of CO-euthanized tilapia were higher than in untreated tilapia and there was no significant (P > 0.05) decrease in heme peak wavelengths of CO-treated tilapia white and red muscle during frozen storage. The CO content of frozen euthanized tilapia fillets was significantly (P > 0.05) higher than in untreated fillets. In general, red muscle tissue of euthanized tilapia had a higher concentration of CO than white muscle.
CONCLUSION: Color stability of tilapia fillets was significantly improved by pre-mortem CO treatment. The color of CO-treated fillets was retained during frozen storage compared to untreated fillets. Hence, pre-mortem CO treatment could be used as a new method for improving color of tilapia. Copyright © 2008 Society of Chemical Industry
Carbon monoxide (CO) has been used for improving the color of muscle foods. In the current study, we compared the postmortem treatment of tilapia fillets with 100% CO and euthanasia of live tilapia with CO for their ability to stabilize the color of white and red muscle of tilapia fillets. Both postmortem CO treatment and CO euthanasia were effective in increasing the redness (a* value) and lightness (L* value) of tilapia white and red muscle. Fillets obtained from CO-euthanized tilapia showed significantly higher a* and L* values during 1 mo of frozen storage at –20 ° C and subsequent thawing and storage at 4 ° C for 18 d. The amount of CO present in the red and white muscles decreased during the 18 d of storage at 4 ° C. There was no significant difference in the pH, drip, or thaw loss of CO-treated tilapia fillets compared to the untreated fillets.
Green, nonsulfur-like bacteria (GNSLB) and cyanobacteria form major components of microbial mats in both sulfidic and non-sulfidic hot springs and have been mainly studied in hot springs of Yellowstone National Park (YNP). These organisms synthesize specific lipid biomarkers such as wax esters and long chain polyunsaturated alkenes (GNSLB) and heptadecane (cyanobacteria). We analyzed the lipid distribution and their stable carbon isotopic composition in sulfidic Icelandic hot spring microbial mats known to contain GNSLB and cyanobacteria. Based on the lipid distribution, it seems that the GNSLB in these mats are closely related to Chloroflexus aurantiacus. The stable carbon isotopic composition of the bulk biomass and wax esters suggests mainly autotrophic growth by GNSLB in this sulfidic hot spring. However, the stable carbon isotopic composition of hentriacontatriene in the two GNSLB mats suggests an alternative carbon source for the C31:3 alkene producing GNSLB from that in YNP. The isotopic composition of cyanobacterial biomarkers in the mat most distant from the source of the hot spring seems to suggest inorganic carbon limitation for cyanobacteria, possibly because they grow underneath the GNSLB in these sulfidic hot spring inverted microbial mats.