The impact of different operating conditions on membrane fouling and EPS production

The main goal of this research was to investigate how different factors influence membrane fouling. The impact of the different concentrations of activated sludge and the amount of extracellular polymer substances (EPS) were monitored. Two pilot plants with submerged membrane modules (hollow fiber and flat sheet) were operated and the raw wastewater was used.Humic substances were identified as the major components of EPS in the activated sludge (more than 34%) in both pilot plants. As the basic constituent in permeate, humic substances were identified as the most dominant components in the effluent (61%) in both pilot plants. Conversely, proteins were mostly analyzed in permeate and supernatant below the detection limit. The total amount of EPS [mg g⁻¹ (VSS)] was similar for concentrations of activated sludge 6, 10 and 14 g L⁻¹. Carbohydrates were identified as the component of EPS which tends most to clog membranes.     

The comparative kinetic analysis of Acetocell and Lignoboost® lignin pyrolysis: the estimation of the distributed reactivity models

The non-isothermal pyrolysis kinetics of Acetocell (the organosolv) and Lignoboost? (kraft) lignins, in an inert atmosphere, have been studied by thermogravimetric analysis. Using isoconversional analysis, it was concluded that the apparent activation energy for all lignins strongly depends on conversion, showing that the pyrolysis of lignins is not a single chemical process. It was identified that the pyrolysis process of Acetocell and Lignoboost? lignin takes place over three reaction steps, which was confirmed by appearance of the corresponding isokinetic relationships (IKR). It was found that major pyrolysis stage of both lignins is characterized by stilbene pyrolysis reactions, which were subsequently followed by decomposition reactions of products derived from the stilbene pyrolytic process. It was concluded that non-isothermal pyrolysis of Acetocell and Lignoboost? lignins can be best described by n-th (n>1) reaction order kinetics, using the Weibull mixture model (as distributed reactivity model) with alternating shape parameters.     

The evolutionary genetics of emerging plant RNA viruses

Over the years, agriculture across the world has been compromised by a succession of devastating epidemics caused by new viruses that spilled over from reservoir species or by new variants of classic viruses that acquired new virulence factors or changed their epidemiological patterns. Viral emergence is usually associated with ecological change or with agronomical practices bringing together reservoirs and crop species. The complete picture is, however, much more complex, and results from an evolutionary process in which the main players are ecological factors, viruses' genetic plasticity, and host factors required for virus replication, all mixed with a good measure of stochasticity. The present review puts emergence of plant RNA viruses into the framework of evolutionary genetics, stressing that viral emergence begins with a stochastic process that involves the transmission of a preexisting viral strain into a new host species, followed by adaptation to the new host.     

Solid-phase treatment with the fungus Trametes versicolor substantially reduces pharmaceutical concentrations and toxicity from sewage sludge

For safe biosolid-land-applying, sludge should be contaminant-free. However, it may contain important amounts of micropollutants, not removed in the wastewater-treatment-processes. An alternative treatment with the fungus Trametes versicolor was applied in sterile solid-phase systems consisting of sludge and a lignocellulosic substrate. Fungal colonization and activity were demonstrated during the process, according to monitoring of ergosterol, laccase activity and the naproxen-degradation test (ND24). Fourteen out of 43 analyzed pharmaceuticals were found in the raw sludge. After treatment, phenazone, bezafibrate, fenofibrate, cimetidine, clarithromycin, sulfamethazine and atenolol were completely removed, while removals between 42% and 80% were obtained for the remaining pharmaceuticals. Toxicological analyses (Daphnia magna, Vibrio fischeri and seed germination) showed an important reduction in sludge toxicity after treatment. Results suggest that a solid-phase treatment with T. versicolor may reduce the ecotoxicological impact of micropollutants present in sewage sludge. This is the first report of a fungal-approach for elimination of emerging pollutants from biosolids.     

Occurrence and Diversity of Pome Fruit Viruses in Apple and Pear Orchards in Latvia

Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV) and Apple mosaic virus are economically important viruses infecting fruit tree species worldwide. To evaluate the occurrence of these pome fruit viruses in Latvia, a large‐scale survey was carried out in 2007. Collected samples were tested for infection by DAS ELISA and multiplex RT‐PCR. The accuracy of the detection of the viruses in multiplex RT‐PCR was confirmed by sequencing amplified PCR fragments. The results showed a wide occurrence of viruses in apple and pear commercial orchards established from non‐tested planting material. More than 89% of the tested apple trees and more than 60% of pear trees were infected with one or more pome fruit viruses. Analyses showed that the high occurrence of viruses in several apple cultivars is due to the propagation of infected clonal rootstocks and scions from infected mother trees. Sequence analyses targeting the 3′‐terminal region of the tested viruses showed various degrees of genetic diversity within respective virus isolates. This is the first report of the occurrence of ACLSV, ASGV and ASPV in apple and pear trees in Latvia and demonstrates their genetic diversity in different host genotypes.     

Adiponectin inhibits spontaneous and catecholamine-induced lipolysis in human adipocytes of non-obese subjects through AMPK-dependent mechanisms

Adiponectin is an adipokine increasing glucose and fatty acid metabolism and improving insulin sensitivity. The aim of this study was to investigate the role of adiponectin in the regulation of adipocyte lipolysis. Human adipocytes isolated from biopsies obtained during surgical operations from 16 non-obese and 17 obese subjects were incubated with 1) human adiponectin (20 microg/ml) or 2) 0.5 mM AICAR - activator of AMPK (adenosine monophosphate activated protein kinase). Following these incubations, isoprenaline was added (10(-6) M) to investigate the influence of adiponectin and AICAR on catecholamine-induced lipolysis. Glycerol concentration was measured as lipolysis marker. We observed that adiponectin suppressed spontaneous lipolysis by 21 % and isoprenaline-induced lipolysis by 14 % in non-obese subjects. These effects were not detectable in obese individuals, but statistically significant differences in the effect of adiponectin between obese and non-obese were not revealed by two way ANOVA test. The inhibitory effect of AICAR and adiponectin on lipolysis was reversed by Compound C. Our results suggest, that adiponectin in physiological concentrations inhibits spontaneous as well as catecholamine-induced lipolysis. This effect might be lower in obese individuals and this regulation seems to involve AMPK.     

Developmental changes in gut microbiota and enzyme activity predict obesity risk in rats arising from reduced nests

The aim of the study was to assess the impact of preweaning overnutrition upon the ontogeny of intestinal microbiota, alkaline phosphatase activity (AP) and parameters of growth and obesity in male Sprague-Dawley rats. We tested whether intestinal characteristics acquired in suckling pups could programme the development of enhanced fat deposition during normalized nutrition beyond weaning. Postnatal nutrition was manipulated by adjusting the number of pups in the nest to 4 (small litters--SL) and 10 (normal litters--NL). In the postweaning period both groups were fed with a standard diet. The jejunal and colonic Lactobacillus/Enterococcus (LAB) and the Bacteroides/Prevotella (BAC) were determined using the FISH technique, and the jejunal AP activity was assayed histochemically. At 15 and 20 days of age the SL pups became heavier, displayed increased adiposity accompanied by significantly higher LAB and lower numbers of BAC and with higher AP activity in comparison with rats nursed in NL nests. These differences persisted to day 40 and withdrawal of the previous causal dietary influence did not prevent the post-weaning fat accretion. These results reveal the significance of early nutritional imprint upon the gut microbial/functional development and allow better understanding of their involvement in the control of obesity.     

A polymorphism in the cyclooxygenase 2 gene in type 1 diabetic patients with nephropathy

Diabetic nephropathy (DN), the most serious complication of Type 1 diabetes (DM1), has a strong genetic component. Cyclooxygenase-2 (COX-2), an inducible enzyme by a number of stimuli, has been implicated in pathophysiology of cardiovascular and renal disease, including DN. The allele -765C, of the -765G > C polymorphism (rs20417) in the COX-2 promoter has lower promoter activity compared with the -765G allele and protective effects in cardiovascular disease. This polymorphism was not investigated in patients with DM1 and nephropathy. The study was conducted in 779 Caucasian patients with DM1 and compared to a representative sample of healthy Czech population. The patients demonstrated lower frequencies of the CC genotype (P = 0.005). From the DM1 cohort, 153 patients met the criteria for low risk of the development of DN (LRDN, duration of DM1 > 10 years, normoalbuminuria, normotension) and 139 patients had manifest DN. There were no differences in -765G > C polymorphisms between LRDN and DN patients. Moreover, the C/G allele frequencies did not also differ between the groups. In conclusion, patients with DM1 display lower freqencies of the protective CC genotype as compared to healthy subjects. However, the study did not reveal associations of -765G > C polymorphism with the risk of DN.     

Inhibitory effect of metformin on oxidation of NADH-dependent substrates in rat liver homogenate

Metformin is widely used in the treatment of Type 2 diabetes, however, mechanisms of its antihyperglycemic effect were not yet fully elucidated. Complex I of mitochondrial respiration chain is considered as one of the possible targets of metformin action. In this paper, we present data indicating that the inhibitory effect of metformin can be tested also in liver homogenate. Contrary to previous findings on hepatocytes or mitochondria under our experimental conditions, lower metformin concentrations and shorter time of preincubation give significant inhibitory effects. These conditions enable to study the mechanism of the inhibitory effect of metformin in small samples of biological material (50-100 mg wet weight) and compare more experimental groups of animals because isolation of mitochonria is unnecessary.