Effects of sublethal concentrations of lignosulphonates on growth,intestinal flora and some digestive enzymes of rainbow trout (Salmo gairdneri)

Young rainbow trout (Salmo gairdneri) were exposed to lignosulphonates (LS) at concentrations of 0, 40, 80, 160, 320, 640, 1 280 and 1 920 ppm for 35 or 60 days. At concentrations of 160 ppm LS and higher the growth rates were slower. The higher concentrations had the most retarding effect on growth, but a clear general relationship between LS concentration and growth retardation was not observed.The bacterial flora in the digestive tract of the fish was examined. The predominant micro-organisms were flavobacteria, bacilli, streptococci and yeasts (Cryptococcus spp.), which were also isolated from the diet. There were about 10 000 viable aerobic and 1 000 anaerobic bacteria per gramme of intestinal contents. There was no significant difference in quantitative or qualitative composition of the intestinal flora of the different groups.The following groups of digestive enzymes were studied: proteinases, amylases, lipases and deoxyribonucleases. The activities of proteinases and nucleases were significantly impaired in fish exposed to concentrations of 1 280 ppm LS and higher, and those of amylases at concentrations of 320 ppm LS and higher. A possible connection between the reduced growth rates and depressed activities of the digestive enzymes is discussed, but no firm conclusion regarding the mechanism by which LS effects fish growth can be made on the basis of the present study.     

Increased abundance of European eel (Anguilla anguilla) in acidified Norwegian rivers after liming

The prevalence and abundance (density 100 m^?2) of European eel (Anguilla anguilla) were studied by means of electrofishing in 13 acidified rivers in Norway that had been limed to restore acceptable water quality for Atlantic salmon (Salmo salar). Status of Atlantic salmon in these rivers varied prior to liming, from being entirely lost in six highly acidified rivers and in different stages of decline in seven less acidified rivers. Four of the rivers are heavily affected by hydropower development. The abundance and prevalence of European eel increased significantly during the study period. The best model for predicting eel abundance was that with four explanatory variables: time after liming, time after liming squared, status of salmon stocks and hydropower regulation. The eel density was expected to increase by a factor of almost 5 after 10 years of liming. The model also predicts that a river with a formerly reduced Atlantic salmon stock has a 2.8 times higher density of eel than rivers with formerly lost salmon stocks. Before liming, European eel were on average recorded at 15 and 41% of the sampling stations in rivers with formerly lost and reduced Atlantic salmon populations, respectively, increasing to 49 and 68% in individual rivers, respectively, after 10 years of liming. The recovery of European eel in these formerly acidified rivers by means of liming took place during the same period as their abundance declined in other parts of their distribution area in Norway and elsewhere in Europe.     

Effects of dietary marine microalgae,Tetraselmis suecica,on production,gene expression,protein markers and bacterial count of Pacific white shrimp Litopenaeus vannamei

The marine flagellated Chlorophyta Tetraselmis suecica is among the most important live food species in marine aquaculture. In the present study, the effects of dietary supplementation of dried marine microalgae, Tetraselmis suecica, on growth performance; feed utilization; chemical composition; gene expression of superoxide dismutase (SOD), glutathione peroxidase (GPx) and insulin‐like growth factor 2 (IGF‐II) gene of Pacific white shrimp, Litopenaeus vannamei; muscle protein polymorphism; and microbial count were assessed and evaluated. Three hundred and sixty L. vannamei (postlarvae) Pls (0.124 ± 0.002 g) were randomly stocked into 40‐L glass aquaria (30 shrimp/aquarium) and fed three times daily four tested diets: a basal diet (control), diet incorporated with 2.5 g kg^?1 dried T. suecica (T1), 5 g kg^?1 dried T. suecica (T2) and 7.5 g kg^?1 dried T. suecica (T3) in triplicates, for 90 days. At the end of the trial, the survival rate (SR) of L. vannamei fed diets supplemented with different levels of T. suecica was significantly (p < .05) higher than the control diet. The highest weight gain and specific growth rate and the best feed conversion ratio were recorded on L. vannamei fed a diet supplemented with a 7.5 g/kg dried T. suecica. The highest protein, lipid and ash contents were obtained in L. vannamei fed the diet containing 7.5 g/kg T. suecica, when compared with the remaining tested diets. The gene expression of antioxidant genes SOD and GPx was the lowest in the T3 group in comparison with the control group. Meanwhile, expression level of IGF‐II was higher in the T2 group. The total heterotrophic bacterial count was significantly (p < .05) increased with the cumulative T. suecica level, while no significant (p > .05) differences were found in the total Vibrio count among treatments. Overall, the present results have shown that the diet supplemented with the highest inclusion level of dried T. suecica resulted in improved growth and nutrient utilization.     

Risk and economic sustainability of crop farming systems

In economic terms, resilience in farming has to do with the capacity of a farm business to survive various risks and other shocks. Despite its importance, resilience has seldom been directly considered in evaluations of economic sustainability. A whole-farm stochastic simulation model over a 6-year planning horizon was used to analyse organic and conventional cropping systems using a model of a representative farm in Eastern Norway. The relative economic sustainability of alternative systems under changing assumptions about future technology and price regimes was examined in terms of financial survival to the end of the planning period. The same alternatives were also compared in terms of stochastic efficiency. To model the risk of business failure adequately there is a need to deal with the risk of bankruptcy, and a modification of traditional analysis was used for that purpose. The organic farming system was found to be somewhat less economically sustainable than the conventional system, especially if the organic price premiums and the organic area payments were to be phased out. The results illustrate possible conflicts between pursuit of risk efficiency and economic sustainability. The model developed could be used to support farmers’ choices between farming systems as well as to help policy makers develop more sharply targeted policies.     

Using value functions to elicit spatial preference information

Decision making in forest planning often involves situations, where the value of the stand is dependent on its location or the properties of the stands nearby. Often the most intuitive tool to describe spatial objectives and outcomes is a visual map. However, evaluating and comparing different maps may prove a considerable cognitive burden, especially over large areas and in long-term planning. In this study, we investigate the use of value functions for eliciting spatial preference information from maps. Our case study is part of a project investigating the possibilities of increasing broadleaf-tree-dominated habitats in a northern Swedish landscape. The experts involved in the project evaluated maps showing different fragmentation patterns. Different spatial indices were then calculated for the maps, and expert evaluations were used to sketch value functions describing the preferred fragmentation level. The approach was found to be a quick way of translating spatial preferences into numerical values and conceptualizing the relatively abstract concept of fragmentation in the landscape. Furthermore, the results show that the choice of a certain fragmentation index has a crucial effect on the value function.     

Comparison of individual assignment methods and factors affecting assignment success in cattle breeds using microsatellites

Abstract

Comparisons of seven different individual assignment methods based on likelihood and distances were carried out with four different sets of data, which varied both in number of populations and genetic divergence. Based on 27 microsatellites genotyped in eight cattle breeds (Icelandic and seven Norwegian), 28 hybrid populations were simulated. Factors affecting individual assignment success, such as number and divergence of populations, sample size and number of loci, were assessed from actual and simulated data. The Bayesian, frequency and Nei-minimum methods performed more or less similarly. Individual assignment success depended mainly on population number and divergence (F_ST). Higher success was observed at high level of divergence among populations and at low number of source populations considered. With eight pure breeds and 27 loci considered the assignment success rate ranged from 55 to 70%. Generally, assignment success increased with increasing number of loci and/or sample size.     

Environmental control of growth and flowering of Rubus idaeus L. cv. Glen Ample

Environmental control of the annual growth cycle of ‘Glen Ample’ raspberry has been studied in order to facilitate crop manipulation for out-of-season production. Plants propagated from root buds were raised in long days (LD) at 21 °C and then exposed to different temperature and daylength conditions at varying ages. Shoot growth was monitored by weekly measurements and floral initiation by regular sampling and examination of axillary bud #5. Under natural summer daylight conditions at 60°N shoot growth was nearly doubled at 21 °C compared with 15 °C, while at 9 °C one half of the plants ceased growing and formed flower buds at midsummer. Developing shoots have a juvenile phase and could not be induced to flower before the 15-leaf stage. No significant reduction in induction requirements was found in larger plants. Plants exposed to natural light conditions from 10th August, had an immediate growth suppression at 9 and 12 °C with complete cessation after 4 weeks (by September 7). This coincided with the first appearance of floral primordia. At 15 °C both growth cessation and floral initiation occurred 2 weeks later (by September 21), while at 18 °C continuous growth with no floral initiation was maintained until early November when the photoperiod had fallen below 9 h. The critical photoperiod for growth cessation and floral initiation at 15 °C was 15 h. Plants exposed to 10-h photoperiods at 9 °C for 2–4 weeks had a transient growth suppression followed by resumed growth under subsequent high temperature and LD conditions, while exposure for 5 or 6 weeks resulted in complete growth cessation and dormancy induction. The critical induction period for floral initiation was 3 weeks although no transitional changes were visible in the bud before week 4. When exposed to inductive conditions for marginal periods of 3 or 4 weeks, an increasing proportion of the plants (20% and 67%, respectively), behaved as primocane flowering cultivars with recurrent growth and terminal flowering. It is concluded that growth cessation and floral initiation in raspberry are jointly controlled by low temperature and short day conditions and coincide in time as parallel outputs from the same internal induction mechanism.     

Anti-hyperglycemic Effect of the Aqueous Extract of Banana Infructescence Stalks in Streptozotocin-induced Diabetic Rats

Water extract of banana (Musa sapientum) infructescence stalks has been used in folk medicine in the treatment of diabetes mellitus. This work aims at verifying the claimed effect and elucidating its possible mode of action. The extract was given in replacement of drinking water to diabetic rats, and its mechanism of action was studied by investigating its involvement in glucose transport in Caco-2 monolayers, and in rat jejuna using an in situ perfusion technique. Its effect on the Na⁺/K⁺ ATPase was studied by measuring the amount of inorganic phosphate liberated. The extract reduced significantly blood glucose levels in diabetic rats and glucose transport across rat jejuna and Caco-2 monolayers, and induced a 50 % decrease in their Na⁺/K⁺ ATPase activity. The extract did not induce any further decrease in jejunal glucose uptake in the simultaneous presence of phloridzin and phloretin, respective inhibitors of SGLT1 and GLUT2 transporters nor did it induce a change in the protein expression of SGLT1 and GLUT2. It was concluded that the extract acts by reducing the Na⁺/K⁺ ATPase activity of enterocytes and consequently the sodium gradient required for sugar transport by SGLT1, which leads to down-regulation of GLUT2 and contributes to the observed anti-hyperglycemic effect.