Effect of oxytetracycline on biogas production and active microbial populations during batch anaerobic digestion of cow manure

The aim of this study was to investigate the effect of a common veterinary antibiotic in biogas plants. 20 mg/kg of oxytetracycline was intramuscularly injected into a cow and its concentration in manure, which was sampled daily during the following 20 days, was measured. A total of 20 % of the injected oxytetracycline was detected in manure. Collected manure samples on days 1, 2, 3, 5, 10, 15, and 20 were digested in triplicate serum bottles at 37 °C for 30 days. Control serum bottles produced 255 ± 13 mL biogas, whereas 50–60 % inhibitions were obtained for the serum bottles operated with samples collected for the 5 days after medication. Multivariate statistics used for the evaluation of FISH results showed that Methanomicrobiales were the main methanogenic group responsible for most of the biogas production. Numbers of active Bacteria and Methanomicrobiales were negatively correlated with the presence of oxytetracycline, whereas Methanosarcinales and Methanobacteriales were less affected.     

The impact of OGG1, MTH1 and MnSOD gene polymorphisms on 8-hydroxy-2′-deoxyguanosine and cellular superoxide dismutase activity in myocardial ischemia–reperfusion

Ischemia–reperfusion (I/R) injury, by inducing oxidative DNA damage, is one of the leading causes of increased patient morbidity and mortality in coronary artery by-pass grafting (CABG) surgery. 8-Hydroxyguanine (8-OHG) is an important oxidative base lesion. The 8-oxoguanine glycosylase (hOGG1) and hMTH1, which have several polymorphisms, remove 8-OHdG from the nucleotide pool. We investigated whether there are any correlations the biomarkers of oxidative stress (superoxide dismutase; SOD and 8-OHdG in serum) with genotype for two DNA repair genes (OGG1 and MTH1) and an antioxidant enzyme gene (manganese superoxide dismutase; MnSOD). Therefore, we measured DNA damage (8-hydroxy-2-deoxyguanosine; 8-OHdG) and endogenous antioxidant activity (SOD) at five different time points (T1, before anesthesia; T2, after anesthesia; T3, after ischemia; T4, after reperfusion and T5, after surgery). and also, MnSOD and MutT homolog 1 (MTH1) genes polymorphisms were genotyped by polymerase chain reaction–restricted fragment length polymorphism (PCR–RFLP) in patients undergoing coronary artery by-pass grafting (CABG) surgery. No statistically significant differences were detected in the levels of 8-OHdG and SOD in serum in terms of OGG1 Ser326Cys, MTH1 Val83Met and MnSOD Ala16Val genetic polymorphisms. Our results suggest that OGG1, MTH1 and MnSOD gene polymorphisms are not genetic risk factors for I/R injury.     

Co-expression of plasmid-mediated quinolone resistance-qnrA1 and blaVEB-1 gene in a Providencia stuartii strain

An extended-spectrum B-lactamase (ESBL)-producing Providencia stuartii isolate was studied. A qnrA1 gene co-expressing blaVEB-1 gene was detected. Both genes were transferred to the recipient strain. The ciprofloxacin MIC of recipient strain increased tenfold. The blaVEB-1 gene persisted in microorganisms in Turkey but it also spread with PMQR genes to other species. The combination of PMQR with multidrug resistant isolates producing ESBLs may compromise the use of valuable antibiotics. Serious efforts are necessary to detect PMQR determinants not only with common B-lactamases in widespread pathogens but also with uncommon forms that are encountered infrequently.     

IGF and GH mRNA levels are suppressed upon exposure to micromolar concentrations of cobalt and zinc in rainbow trout white muscle

The objective of this study was to assess the effects of cobalt and zinc exposure of rainbow trout (Oncorhynchus mykiss) on insulin like growth factors (IGF) and growth hormone (GH). Mature rainbow trouts were exposed to 0.42, 2.1, 4.2, 21 and 42μmol/L Co(2+) (added as CoCl(2)·6H(2)O) and 0.34, 1.7, 3.4, 17 and 34μmol/L Zn(2+) (added as ZnSO(4)i·7H(2)O). After 6, 12, 24 and 48h of treatment, expressions of white muscle IGF-I, IGF-II and GH mRNAs were measured by means of quantitative Real Time PCR. During the exposure experiments, no mortalities occurred. The most effective metal concentrations, which caused significant alterations, were determined to be 42μmol/L Co(2+) (10mg CoCl(2)·6H(2)O/L) and 3.4μmol/L Zn(+2) (1mg ZnSO(4)·7H(2)O/L). The following results were obtained for these concentrations. Expression of IGF-I did not change at 6h in zinc treatment while the decrease (p<0.05) was observed at 12h and 24h, and this decrease became stronger at 48h. Cobalt exposure caused a decrease in IGF-I mRNA level at 6h, 12h, 24h and 48h (p<0.05). Both zinc and cobalt exposure resulted in significant decreases in GH expression at 6h. Exposure of trout to Zn resulted in a decrease in expression of IGF-II starting from 6h whereas the significant decrease started at 6h in cobalt exposure and this decrease elevated at 24h. The results indicate that micromolar cobalt and zinc exposure causes significant attenuation in the expressions of these three genes' time dependently. Our findings show that IGF-I is the most resistant and GH is the most sensitive component against cobalt and zinc exposure. We conclude that IGF/GH axis might be strongly affected by the short term exposure to low micromolar concentrations of zinc and cobalt due to alterations of these genes.     

Isolation and Characterization of Salt-Tolerant Bacterial Strains in Salt-Affected Soils of Erzurum,Turkey

In the current study, 18 salt-tolerant bacteria were isolated from salt-affected soil of Erzurum, Turkey. Forty-five bacterial isolates were identified and characterized by conventional and molecular techniques. These 45 sequenced isolates were identified as 16 different genus including Bacillus (19 isolates), Staphylococcus (3 isolates), Halobacillus (4 isolates), Zhihengliuella (2 isolates), Oceanobacillus (2 isolates), Halomonas (1 isolate), Nesterenkonia (2 isolates), Promicromonospora (2 isolates), Jeotgalibacillus (2 isolates), Planococcus (2 isolates), Virgibacillus (1 isolate), Terribacillus (1 isolate), Thalassobacillus (1 isolate), Marinibacillus (1 isolate), Gracilibacillus (1 isolate) and Microbacterium (1 isolate). According to the results obtained, investigated bacterial strains have high salt tolerance and significant enzyme activities that can improve soil nutrient cycling and soil fertility. The current article provides the evaluation and diversity of the potential halotolerant and halophilic bacterial strains in salt-affected soils of Erzurum, Turkey.     

Time-Dependent Variations in Serum Nitrite, 6-Keto-Prostaglandin F1α and Thromboxane B2 Levels Induced by Lipopolysaccharide in Mice

Clinical features of certain immuno-inflammatory disorders exhibit time-dependent fluctuations, which could be related to circadian rhythmicity of proinflammatory mediator production. Many biologically active substances including nitric oxide (NO) and eicosanoids are released into the circulation in sepsis. Increased NO and eicosanoid levels have been reported to be responsible from death in septic shock. The aim of this study was to investigate the variations in the NO and eicosanoid production and mortality induced by bacterial endotoxin, lipopolysaccharide (LPS) injected either in the morning or in the evening. Experiments were performed on mice synchronised to 12 h light and 12 h dark (lights on at 09:00 h). Animals were injected intraperitoneally with LPS (10 mg/kg) at 09:00 (morning) and 21:00 h (evening) alone or in combination with aminoguanidine (NO synthase (NOS) inhibitor) (100 mg/kg) or indomethacin (cyclooxygenase (COX) inhibitor) (100 mg/kg). The serum was separated from blood samples obtained at nine different time points. Nitrite (stable product of NO), 6-keto-prostaglandin F_1α (6-keto-PGF_1α, stable product of prostacyclin) and thromboxane B₂ (TxB₂, stable product of thromboxane) concentrations in serum samples were measured. Serum nitrite levels showed a 24 h circadian rhythmicity depending on LPS injection time. Morning injection caused a peak after 15 h, while evening injection had two peaks after 9 and 18 h. The peak values obtained from morning and evening injections were significantly decreased by aminoguanidine and indomethacin. When LPS injected to mice in the morning and in the evening, it gradually increased the mortality rate within 24 h which could be abolished by aminoguanidine, but not indomethacin. Indomethacin-induced inhibition on LPS-induced nitrite levels was higher in the morning than in the evening. 6-keto-PGF_1α and TxB₂ levels were decreased by indomethacin when injected with LPS at both injection times, but not aminoguanidine. These results showed that there is an interaction between NO and eicosanoids, and LPS may produce different effects on NOS activity, but not eicosanoid production and mortality, depending on injection time in the experimental septic shock model in mice. Chronopharmacological manipulations of NOS and COX pathways and interactions between them could lead to novel therapeutic approaches for the treatment of septic shock.     

Degradation of oxytetracycline and its impacts on biogas-producing microbial community structure

The effect of veterinary antibiotics in anaerobic digesters is a concern where methane production efficiency is highly dependent on microbial community structure. In this study, both anaerobic degradation of a common veterinary antibiotic, oxytetracycline (OTC), and its effects on an anaerobic digester microbial community were investigated. Qualitative and quantitative molecular tools were used to monitor changes in microbial community structure during a 60-day batch incubation period of cow manure with the addition of different concentrations of the antibiotic. Molecular data were interpreted by a further redundancy analysis as a multivariate statistics approach. At the end of the experiment, approximately 48, 33, and 17 % of the initially added 50, 100, and 200 mg l^?1 of OTC was still present in the serum bottles which reduced the biogas production via accumulation of some of the volatile fatty acids (VFAs). Biogas production was highly correlated with Methanobacteriales and Methanosarcinales gene copy numbers, and those parameters were negatively affected with oxytetracycline and VFA concentrations.     

Repeated LPS Injection Induces Distinct Changes in the Kynurenine Pathway in Mice

The immune system has been recognized as a potential contributor to psychiatric disorders. In animals, lipopolysaccharide (LPS) is used to induce inflammation and behaviors analogous to some of the symptoms in these disorders. Recent data indicate that the kynurenine pathway contributes to LPS-induced aberrant behaviors. However, data are inconclusive regarding optimal LPS dose and treatment strategy. Here, we therefore aimed to evaluate the effects of single versus repeated administration of LPS on the kynurenine pathway. Adult C57BL6 mice were given 0.83 mg/kg LPS as a single or a repeated injection (LPS + LPS) and sacrificed after 24, 48, 72, or 120 h. Mice receiving LPS + LPS had significantly elevated brain kynurenine levels at 24 and 48 h, and elevated serum kynurenine at 24, 48 and 72 h. Brain kynurenic acid and quinolinic acid were significantly increased at 24 and 48 h in mice receiving LPS + LPS, whereas serum kynurenic acid levels were significantly decreased at 24 h. The increase of brain kynurenic acid by LPS + LPS was likely unrelated to the higher total dose as a separate group of mice receiving 1.66 mg/kg LPS as single injection 24 h prior to sacrifice did not show increased brain kynurenic acid. Serum quinolinic acid levels were not affected by LPS + LPS compared to vehicle. Animals given repeated injections of LPS showed a more robust induction of the kynurenine pathway in contrast to animals receiving a single injection. These results may be valuable in light of data showing the importance of the kynurenine pathway in psychiatric disorders.     

The protective effect of fish n-3 fatty acids on cerebral ischemia in rat hippocampus

Reactive oxygen species (ROS) have been implicated in the pathogenesis of cerebral injury after ischemia-reperfusion (I/R). Fish n-3 essential fatty acids (EFA), contain eicosapentaenoic acids (EPA) and docosahexoenoic acids (DHA), exhibit antioxidant properties. DHA is an important component of brain membrane phospholipids and is necessary for the continuity of neuronal functions. EPA prevents platelet aggregation and inhibits the conversion of arachidonic acid into thromboxane A(2) and prostaglandins. They have been suggested to be protective agents against neurological and neuropsychiatric disorders. In this study, the neuroprotective effects of fish n-3 EFA on oxidant-antioxidant systems and number of apoptotic neurons of the hippocampal formation (HF) subjected to cerebral I/R injury was investigated in Sprague-Dawley rats. Six rats were used as control (Group I). Cerebral ischemia was produced by occlusion of both the common carotid arteries combined with hypotension for 45 min, followed by reperfusion for 30 min, in rats either on a standard diet (Group II) or a standard diet plus fish n-3 EFA (Marincap((R)), 0.4 g/kg/day, by gavage) for 14 days (Group III). At the end of procedures, the rats were sacrificed and their brains were removed immediately. The levels of malonedialdehyde (MDA) and nitric oxide (NO) and activities of superoxide dismutase (SOD) and catalase (CAT) were measured in left HF. In addition, the number of apoptotic neurons was counted by terminal transferase dUTP nick end labelling (TUNEL) assay in histological samples of the right HF. We found that SOD activities and MDA levels increased in Group III rats compared with Group II rats. On the other hand, CAT activities and NO levels were found to be decreased in Group III rats compared with Group II rats. Additionally, the number of apoptotic neurons was lower in Group III in comparison with Group II rats. The present findings suggest that fish n-3 EFA could decrease the oxidative status and apoptotic changes in ischemic rat hippocampal formation. Dietary supplementation of n-3 EFA may be beneficial to preserve or ameliorate ischemic cerebral vascular disease.