Intracellular transport of ovalbumin afterin vivo endocytosis in rainbow trout liver

The intracellular handing of a mannose-terminated glycoprotein taken up in rainbow trout liver cells by receptor-mediated endocytosis has been studied. The intracellular transport and degradation of ovalbumin (OA) were studied by means of subcellular fractionation in Nycodenz gradients and by differential centrifugation following intravenous injection of the ligand. By using OA labelled with¹²⁵I-tyramine cellobiose (¹²⁵I-TC), the subcellular distribution of labelled degradation products could be studied, since they are trapped intracellularly in the organelle where the degradation takes place. ¹²⁵I-TC-OA was shortly after injection (45 min) localized in a homogenous population of endosomes. Labelled degradation products firs appeared in an organelle with the same density distribution as the endosomes. In livers homogenized 2h after injection the degradation products appeared in organelles with increasing size and density. After 24h, the degradation products were recovered in at least two populations of lysosomes with a distribution profile which coincided with that of the lysosomal enzyme -acetylglucosaminidase.The heterogeneous distribution of the late degradation products seemed not to be due to uptake of ligand in different liver cell types as only the parenchymal liver cells took up labelled OA after intravenous injection of the ligand.     

Antioxidant and Anti-Inflammatory Activities of Barettin

In this paper, we present novel bioactivity for barettin isolated from the marine sponge Geodia barretti. We found that barettin showed strong antioxidant activity in biochemical assays as well as in a lipid peroxidation cell assay. A de-brominated synthetic analogue of barettin did not show the same activity in the antioxidant cell assay, indicating that bromine is important for cellular activity. Barettin was also able to inhibit the secretion of the inflammatory cytokines IL-1β and TNFα from LPS-stimulated THP-1 cells. This combination of anti-inflammatory and antioxidant activities could indicate that barettin has an atheroprotective effect and may therefore be an interesting product to prevent development of atherosclerosis.     

Ration level for salmonids II. Growth, feed intake, protein digestibility, body composition, and feed conversion in rainbow trout weighing 0.5–1.0 kg

Six groups of rainbow trout (Salmo gairdneri Richardson), raised in fibre-glass tanks, were fed at six different ration levels for two periods of 21 days each. Each tank contained 20 individually tagged fish with a mean initial weight of 415 g. The water temperature averaged 8.4°C and 10.2°C in the two periods. The basic ration level was calculated from an expected maximum growth rate, depending on fish size and water temperature. This level was defined as “level 1.000”. The other experimental levels were 0.125, 0.250, 0.500, 2.000, and 4.000 relative to this, respectively.

No fish died during the experiment. The growth of the fish increased significantly with increasing rations up to the level 2.000. The fish lost weight at the ration level 0.125. The growth rate was near zero at the ration level 0.250. The growth of the fish receiving the highest ration level was 1.72% of their weight per day. The variation in growth of the fish within various weight classes was influenced by the ration level so that the growth distribution of the scantiest fed groups was skewed to the left. There was no skewness in the distribution of the most plentifully fed groups. The ration level had no significant effect on the apparent protein digestibility. Measurements of the feed intake using a radioactive isotope in a 6-h meal showed that the fish ingested all the feed at the ration levels from 0.125 to 1.000. The feed intake recorded was equivalent to the requirements for fish growth at the ration level 2.000, while it was lower at the ration level 4.000. The liver weight percentage increased with increasing ration while the dressed-out carcass percentage decreased. The chemical compostion of the carcass was influenced to a greater extent by the feeding than that of the intestines. The feed conversion efficiency (FCE) and the productive protein value (PPV) of the feed were highest at the ration level 1.000. The values obtained were an FCE of 1.0 kg growth per kg dry feed ingredients and a PPV of 41%.     

Market integration between wild and farmed species in Spain

ABSTRACT

Market integration occurs when prices among different locations or related goods follow similar patterns over time. Current knowledge on market integration between aquaculture and wild-caught fish is based on a small number of species and markets. Most studies show the existence of market integration between wild and farmed conspecifics, with the clear exception of European seabass and gilthead seabream in Southern European countries. In this study, we investigate whether this lack of market integration between wild and farmed conspecifics for European seabass and gilthead seabream in Southern European countries is specific for these species or is representative for the area. Therefore, we investigate the existence of market integration in Spain between wild and farmed conspecifics for a large variety of different species: turbot (Scophthalmus maximus), sole (Solea spp.), blackspot (red) seabream (Pagellus bogaraveo), Atlantic cod (Gadus morhua), and meagre (Argyrosomus regius).     

Application of host-specific genetic markers for microbial source tracking of faecal water contamination in an agricultural catchment

Elevated nutrient concentrations in streams in the Norwegian agricultural landscape may occur due to faecal contamination. Escherichia coli (E. coli) has been used conventionally as an indicator of this contamination; however, it does not indicate the source of faecal origin. This work describes a study undertaken for the first time in Norway on an application of specific host-associated markers for faecal source tracking of water contamination. Real-time quantitative polymerase chain reaction (qPCR) on Bacteroidales host-specific markers was employed for microbial source tracking (MST) to determine the origin(s) of faecal water contamination. Four genetic markers were used: the universal AllBac (Bacteroidales) and the individual specific markers BacH (humans), BacR (ruminants) and Hor-Bac (horses). In addition, a pathogenicity test was carried out to detect the top seven Shiga toxin-producing E. coli (STEC) serogroups. The ratio between each individual marker and the universal one was used to: (1) normalise the markers to the level of AllBac in faeces, (2) determine the relative abundance of each specific marker, (3) develop a contribution profile for faecal water contamination and (4) elucidate the sources of contamination by highlighting the dominant origin(s). The results of the qPCR MST analyses indicated the actual contributions of humans and animals to faecal water contamination. The pathogenicity test revealed that water samples were STEC positive at a low level, which was in proportion to the concentration of the ruminant marker. The outcomes were verified statistically by coupling the findings of major contamination sources with observations in the field regarding local land use (residential or agricultural). Furthermore, clear correlations between the human marker and E. coli counts as well as the ruminant marker and STEC quantity in faecally contaminated water were observed. The results of this study have the potential to help identify sources of pollution for targeted mitigation of nutrient losses.     

Atlantic meridional overturning circulation during the Last Glacial Maximum

The circulation of the deep Atlantic Ocean during the height of the last ice age appears to have been quite different from today. We review observations implying that Atlantic meridional overturning circulation during the Last Glacial Maximum was neither extremely sluggish nor an enhanced version of present-day circulation. The distribution of the decay products of uranium in sediments is consistent with a residence time for deep waters in the Atlantic only slightly greater than today. However, evidence from multiple water-mass tracers supports a different distribution of deep-water properties, including density, which is dynamically linked to circulation.     

Influence of mechanical weeding and fertilisation on perennial weeds,fungal diseases,soil structure and crop yield in organic spring cereals

ABSTRACT

There is a need both in organic farming and on farms using integrated pest management for non-chemical measures that control the perennial weed flora. The effect of mechanical weeding and fertilisation on perennial weeds, fungal diseases and soil structure were evaluated in two different experiments in spring cereals. Experiment I included six strategies. The first strategy was (1) without specific measures against perennial weeds. The other strategies encompassed one or two seasonal control measures; (2) rhizome/root cutting with minimal soil disturbance in autumn, (3) hoeing with 24?cm row spacing, (4) combined hoeing and disc harrowing in autumn, (5) ‘KvikUp’ harrowing in spring, and (6) ‘KvikUp’ harrowing in spring and autumn. Experiment II included factor (i) inter-row hoeing and (ii) fertilisation level. This experiment included the comparison between normal row spacing (12?cm) with weed harrowing versus double row spacing (=24?cm) in combination with inter-row hoeing and 4 fertilisation levels (50–200?kg N ha^?1). In experiment I the strategies consisting of no or one direct weed control measure (1, 2, 3 and 5) clearly did not control the perennial weeds. The two seasonal control measures (4 and 6) gave a satisfactory weed control and highest crop yield. The combination of best weed control and no measured harmful effects on soil structure or increase of fungal diseases may explain the highest yields for these strategies. In Experiment II, hoeing and 24?cm spacing gave less perennial biomass compared to 12?cm spacing. Grain yields increased linearly with increasing nitrogen input. The study shows that both inter-row hoeing and weed harrows, are important elements in integrated pest management practice and organic farming. In addition, our results indicate that efficient mechanical weeding is possible without harmful effects in crop rotation consisting of various spring cereals as regards soil structure and plant health.     

Effects of eucalyptus and coniferous plantations on soil properties in Gambo District,southern Ethiopia

Abstract

Plantation establishment using exotic species on disturbed cultivated and undisturbed primary forest soils is common in Gambo district, southern Ethiopia, but their effects on soil properties are not fully known. This study investigated the effects of plantation species on major soil physical and chemical properties and further evaluated the soil quality under different land uses. Soil samples in triplicates, collected under different plantations, were analysed for their physical and chemical properties. Based on these soil properties, an integrated soil quality index was determined. The soil bulk density (BD) varied from 0.72 to 0.80 cm^?3 in plantations established on primary forest land and natural forest and from 0.86 to 1.14 g cm^?3 in those plantations established on cultivated soils. Also significantly lower pore volume and infiltration rate were observed under plantations established on cultivated lands than those on primary forest soils. Higher water volume (% at ?1500 kPa matric potential) was obtained in soils under Juniperus procera and natural forest compared with that under the rest of the plantations investigated. The concentration of soil organic carbon (SOC) varied from 3.4 to 10.2%, N from 0.3 to 1.0% and Av.P from 1.5 to 7.0% in soils under plantations and natural forest. Exchangeable cations generally showed a decreasing trend with depth in all land use types with minor exceptions. The concentrations of exchangeable Ca⁺² varied from 6.5 to 22.7 cmol kg^?1 and were significantly higher under Juniperus procera than under Eucalyptus species. The soil under plantations on previously cultivated lands showed soil quality index below 0.5 (the baseline value), while those established on undisturbed forest soil were generally above that value. The study results suggest that selecting species such as Juniperus procera and prolonging the harvesting period would improve and maintain the quality of soil properties.     

Effects of temperature and dietary n-3 and n-6 fatty acids on endocytic processes in isolated rainbow trout (Oncorhynchus mykiss,Walbaum) hepatocytes

Effects of different incubation temperatures (2, 8, 14 and 20°C) and hepatocyte membrane fatty acid composition on the rate of internalization and lysosomal degradation of the ligand, mannosylated albumin, that is taken up by receptor-mediated endocytosis, were investigated in rainbow trout (Oncorhynchus mykiss, Walbaum). The fish were kept at a water temperature ranging from 9 to 14°C and fed pelleted diets coated with either capelin oil (control), EPA/DHA-concentrate (rich in n-3 polyunsaturated fatty acids) or soybean oil (rich in n-6 unsaturated fatty acids) for at least 3 months prior to sampling. The endocytic uptake mediated by the mannose receptor was very efficient at all temperatures studied. Lysosomal degradation, on the other hand, came to a halt below 8°C. The activation energies for uptake and degradation were 54.6 and 164.2 kJ/mol respectively. No negative effects of increased amounts of either n-3 or n-6 fatty acids were observed on the endocytic parameters studied. On the contrary, multivariate analysis indicated a positive relationship between high levels of n-6 fatty acids and low unsaturation index in the phosphatidylcholine (PC) fraction of the hepatocytes and the internalization rate of 2°C, meaning that the rate of receptor-mediated endocytosis may be affected by membrane fatty acid composition.     

Interaction of low density lipoproteins with liver cells in rainbow trout

Liver is the main catabolic tissue for low density lipoprotein in rainbow trout (Gjøen and Berg 1992). We have investigated the interaction of LDL with isolated trout liver cells and liver membranes. ¹²⁵I-TC labelled trout LDL bound to isolated trout liver cells in a time dependent and saturable manner with an apparant K_d of 20.1 g/ml, suggesting the existence of a specific binding site on the surface of these cells. The binding was Ca²⁺ dependent assessed by the 50% reduction obtained by 5 mM EDTA. Saturable binding to isolated trout liver membranes could also be demonstrated, but with lower affinity as compared to intact cells. Degradation of ¹²⁵I-TC-LDL in hepatocytes was also saturable as degradation could be inhibited about 60% by a 100 fold surplus of unlabelled LDL. The rate of degradation increased with temperature up to 20°C. Both cell association (binding + uptake) and degradation were reduced down to 20% of control in the presence of microtubular and lysosomal inhibitors. Hepatic catabolism of trout LDL therefore seems to depend on receptormediated endocytosis, followed by lysosomal degradation.Abbreviations TC tyramine cellobiose - LDL low density lipoproteins - MeLDL methylated low density lipoproteins - VLDL very low density lipoproteins - HDL high density lipoproteins - VTG vitellogenin - EDTA ethylenediamine tetraacetic acid - PBS phospate buffered saline - SDS-PAGE sodium dodecyl sulphatepolyacrylamide gel electrophoresis - DMPC L--phosphatidylcholine-dimyristoyl