Effect of growth hormone on muscle protein synthesis in rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar)

This paper reports on the effect of administration of mammalian growth hormone (GH) on muscle protein synthesis as measured in white muscle using the phenylalanine flooding technique. The effect of exogenous GH was compared with that of insulin and prolactin, and with endogenous GH.The rate of protein synthesis in white muscle of rainbow trout 6 h after the injection of bovine GH or bovine insulin was twice (2.6 and 2.9% d^–1) that of the control saline-injected fish (1.2% d^–1). A metabolic effect of GH, as observed with insulin, is suspected.The rates of change in body weight and body length and the fractional rate of protein synthesis in muscle of rainbow trout were enhanced by mammalian GH administration. The effect of GH on muscle RNA/protein ratios was not significant. An opposite effect of antibodies against salmon GH (Lebailet al. 1989) on growth rate and muscle protein synthesis rate was found in rainbow trout. It is suggested that the effects of exogenous and endogenous GH on capacity and efficiency of muscle protein synthesis were similar.The long-term effects of mammalian GH on presmolt Atlantic salmon was also tested. The same trends were found with ovine prolactin supplementation in Atlantic salmon but not as high as those observed with ovine GH.     

Toxic C17-Sphinganine Analogue Mycotoxin,Contaminating Tunisian Mussels,Causes Flaccid Paralysis in Rodents

Severe toxicity was detected in mussels from Bizerte Lagoon (Northern Tunisia) using routine mouse bioassays for detecting diarrheic and paralytic toxins not associated to classical phytoplankton blooming. The atypical toxicity was characterized by rapid mouse death. The aim of the present work was to understand the basis of such toxicity. Bioassay-guided chromatographic separation and mass spectrometry were used to detect and characterize the fraction responsible for mussels’ toxicity. Only a C17-sphinganine analog mycotoxin (C17-SAMT), with a molecular mass of 287.289 Da, was found in contaminated shellfish. The doses of C17-SAMT that were lethal to 50% of mice were 750 and 150 μg/kg following intraperitoneal and intracerebroventricular injections, respectively, and 900 μg/kg following oral administration. The macroscopic general aspect of cultures and the morphological characteristics of the strains isolated from mussels revealed that the toxicity episodes were associated to the presence of marine microfungi (Fusarium sp., Aspergillus sp. and Trichoderma sp.) in contaminated samples. The major in vivo effect of C17-SAMT on the mouse neuromuscular system was a dose- and time-dependent decrease of compound muscle action potential amplitude and an increased excitability threshold. In vitro, C17-SAMT caused a dose- and time-dependent block of directly- and indirectly-elicited isometric contraction of isolated mouse hemidiaphragms.     

Nutritional value of faba bean (Vicia faba L.) seeds for feed and food

Faba bean (Vicia faba L.) is a protein-rich legume seed well adapted to most climatic areas of Europe and widely used for feed and food. Even if the seed is generally recognized to be of good nutritional value, existing genetic variability for seed composition offers possibilities for improvement of this trait by breeding. Four major quality types must be distinguished according to the presence or absence of tannins in the integuments and of vicine (V) and convicine (C) in the cotyledons. The nutritional value of diets containing varying amounts of different faba bean cultivars characterized by high or low levels of tannins, and high or low levels of vicine + convicine (VC), has been examined in monogastric animals and ruminants. Low-tannin content generally results in higher protein and energy digestibility for monogastric animals and low VC content has a positive effect on laying hen and broiler production performances. V and C, inactive precursors of divicine and isouramil are redox compounds potentially toxic to human carriers of a widespread genetic deficiency of the erythrocyte (red blood cell, RBC) enzyme glucose-6-phosphate dehydrogenase (G6PD). Ingestion of faba beans by these deficient individuals may cause a severe, potentially lethal hemolytic anemia (favism). The mechanism of action of divicine and isouramil in the G6PD-deficient RBC is discussed.     

An investigation to enhance understanding of the stimulation of weed seedling emergence by soil disturbance

Enhanced understanding of soil disturbance effects on weed seedling recruitment will help guide improved management approaches. Field experiments were conducted at 16 site‐years at 10 research farms across Europe and North America to (i) quantify superficial soil disturbance (SSD) effects on Chenopodium album emergence and (ii) clarify adaptive emergence behaviour in frequently disturbed environments. Each site‐year contained factorial combinations of two seed populations (local and common, with the common population studied at all site‐years) and six SSD timings [0, 50, 100, 150, 200 day‐degrees (d°C, base temperature 3°C) after first emergence from undisturbed soil]. Analytical units in this study were emergence flushes. Flush magnitudes (maximum weekly emergence per count flush) and flush frequencies (flushes year^?1) were compared between disturbed and undisturbed seedbanks. One year after burial, SSD promoted seedling emergence relative to undisturbed seedbanks by increasing flush magnitude rather than increasing flush frequency. Two years after burial, SSD promoted emergence through increased flush magnitude and flush frequency. The promotional effects of SSD on emergence were strongest within 500 d°C following SSD; however, low levels of SSD‐induced emergence were detected as late as 3000 d°C following SSD. Accordingly, stale seedbed practices that eliminate weed seedlings should occur within 500 d°C of disturbance, because few seedlings emerge after this time. However, implementation of stale seedbed practices will probably cause slight increases in weed population densities throughout the year. Compared with the common population, local populations exhibited reduced variance in total emergence measured within sites and across SSD treatments, suggesting that C. album adaptation to local pedo‐climatic conditions involves increased consistency in SSD‐induced emergence.     

Molecular diversity of methanogens in fecal samples from Bactrian camels (Camelus bactrianus) at two zoos

Animals are dependent on mutualistic microbial communities that reside in their gastrointestinal track for essential physiological functions such as nutrition and pathogen resistance. The composition of microbial communities in an animal is influenced by various factors, including species, diet and geographical location. In this preliminary study, the population structure of fecal methanogens in Bactrian camels (Camelus bactrianus) from two zoos was studied using separate 16S rRNA gene libraries for each zoo. While methanogen sequences belonging to the genus Methanobrevibacter were dominant in both libraries, they showed significant differences in diversity (p=0.05) and structure (p<0.0001). Population structure analysis revealed that only two operational taxonomic units (OTUs) were shared between libraries, while two OTUs were unique to the Southwick Zoo library and seven OTUs were unique to the Potter Park Zoo library. These preliminary results highlight how methanogen population structures can vary greatly between animals of the same species maintained in captivity at different locations.     

Improving Performance of Treatment Wetlands: Evaluation of Supplemental Aeration,Varying Flow Direction,and Phosphorus Removing Filters

Pollutant removal was compared among subsurface flow constructed wetland (CW) mesocosms used for dairy farm wastewater treatment. Supplemental aeration, flow direction, and the use of phosphorus-reducing filters (PRFs) were varied among the CWs. The following were compared: (1) vertical flow CWs with and without supplemental aeration, (2) aerated CWs with horizontal and vertical flow directions, (3) single-cell and two-cell treatment systems, and (4) wetland-wetland systems (two CWs in series) and wetland-PRF systems (a CW followed by a PRF). The results from this investigation showed that, first, nearly all treatment strategies, either singly or in pairs, substantially reduced almost all the contaminants we tested. Second, supplemental aeration resulted in higher ammonium-nitrogen (NH₄-N) removal efficiencies in aerated vertical flow CWs, compared to unaerated CWs. However, it caused no further improvement in dissolved reactive phosphorus (DRP), total suspended solids (TSS), E. coli, or BOD₅ removal. Third, there was no difference between aerated horizontal and aerated vertical flow CWs in removal of any of the tested contaminants. Fourth, adding a second stage of treatment significantly improved DRP, TSS, E. coli, and NH₄-N removal, but not BOD₅. Finally, treatment systems with PRFs showed superior performance in DRP and E. coli removal.     

Lipid deposition patterns among different sizes of three commercial fish species

This study was conducted to compare lipid deposition pattern of three fish species among fish size, Large yellow croaker (Larmichthys crocea), Japanese seabass (Lateolabrax japonicus) and Turbot (Scophthalmus maximus L.), Using magnetic resonance imaging technology for adult fish, results showed that lipid of large yellow croaker mainly deposits in abdominal cavity wall, while for Japanese seabass mainly deposit in visceral adipose tissue and for turbot lipid mainly distribute subcutaneous tissue. Three sizes for each species were selected: S1 (small size), S2 (intermediate size) and S3 (big size), to examine chemical analysis. Results of chemical analysis indicated that whole body lipid content of large yellow croaker significantly increased with the increase in body weight, but Japanese seabass and turbot significantly decreased (p < .05). Lipid content of muscle and intestinal tract in large yellow croaker significantly increased with the increase in body weight (p < .05), but lipid content of adipose tissue, kidney, heart and skin in S2 group were higher than S1 and S3 groups (p < .05). Lipid content of liver, eye, kidney and brain in Japanese seabass significantly increased with the increase in body weight (p < .05), but lipid content of stomach and heart showed an opposite trend. Lipid content of liver, adipose tissue, skin and eye in turbot significantly decreased (p < .05), but lipid content of brain significantly increased with the increase in body weight (p < .05). The results indicated that lipid content of different tissues in fish presented different trends, which was species‐dependent.     

Sorption and desorption of non-ionic herbicides onto particulate organic matter from surface soils under different land uses

In vegetative filter strips used to intercept pesticides present in run‐off, particulate organic matter derived from the vegetation plays an important function in pesticide sorption processes, because it accumulates at the soil surface and quickly responds to changes in land use. Two herbicides with contrasted properties: isoproturon, moderately hydrophobic (log K_ow= 2.5), diflufenican, strongly hydrophobic (log K_ow= 4.9), and isopropylaniline, a metabolite of isoproturon, were used to characterize the sorption and desorption properties of POM originating from soils under three different land uses: a cropped plot under conventional wheat/maize rotation, an adjacent 10‐year‐old grassed strip and a nearby 80‐year‐old oak/chestnut forest. Chemical structural composition information obtained from solid‐state ¹³C CPMAS NMR and estimation of hydrophobicity from contact angle measurements were used to explain the different sorption capacities of POM according to their size and origins. Sorption of isoproturon and diflufenican increased with hydrophobicity of POM, which was greater in the forest soil. Aromaticity of POM was positively correlated to sorption coefficients (K_oc). Desorption of the more hydrophobic compounds, diflufenican and isopropylaniline was weak for all POM fractions, regardless of their origin and size. On the other hand, desorption of isoproturon depended on land use and POM characteristics. The sorption capacities of POM were not only controlled by their chemical composition, but also by their size, due to a greater number of sorptive sites related to a greater surface area with decreasing particle‐size.