Explaining spatial variability in stream habitats using both natural and management‐influenced landscape predictors

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Effect of urea and low temperature on the expression and activity of flavin-containing monooxygenase in the liver and gill of rainbow trout (Oncorhynchus mykiss)

Little is known about the physiological role of flavin containing monooxygenases (FMOs) in teleost fish. Recent studies have indicated induction during saltwater adaptation in several telost species including rainbow trout. A physiological product of FMOs, trimethylamine N-oxide (TMAO) and urea have also been shown to increase in rainbow trout muscle during saltwater adapatation. TMAO counteracts the denaturing effects of urea. In order to evaluate urea as a possible inducer of FMO expression and activity, adult rainbow trout were infused for 48 h with urea/saline solutions at a loading rate of 8 mmol urea/kg/day. To determine whether low temperature had any effect on FMO expression and activity, one group of animals was infused with urea and exposed to low temperature (2–3 °C) for 48 h. Gill FMO-catalyzed thiourea oxygenase activity was significantly induced by low temperature, with twice the activity observed at low temperature (1.116±0.356 nmol/min/mg) compared to urea infusion at 10 °C (0.585±0.282 nmol/min/mg). Low temperature without urea treatment caused a 50% increase in gill FMO activity. In the liver, urea infusion caused an increase in liver FMO activity (from 0.144±0.053 nmol/min/mg to 0.464±0.237 nmol/min/mg), but was unaffected by co-exposure to low temperature (0.523±219 nmol/min/mg). FMO expression and activity correlated with elevated tissue urea levels, but TMAO concentrations were not related. The interactions between urea, temperature and the tissue-specific induction of FMOs indicate FMOs may contribute to other physiological and cellular processes besides osmoregulation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Colchicine alters the nerve birefringence response

The internal perfusion of squid axons with colchicine reversibly and selectively reduces the transient sodium current and the birefringence response to a brief depolarizing voltage pulse.     

Protein quality and digestible energy of selected foods determined in balance trials with rats

Chemical analyses and balance trials with rats of 17 foods showed marked differences in protein quality. According to anin vitro procedure true protein digestibility was high (around 90%). The same was also the case for thein vivo values with the exception of two legumes, beans and chick peas, which were digested to a markedly lower degree when compared to thein vitro values. The assumed reason for this is discussed. Due to extensive differences in the amino acid composition of the 17 samples BV varied considerably with the lowest value (45.5) of rice-wheat gluten breakfast cereal. Energy digestibility was generally high. Amino acid digestibility determinedin vivo followed the pattern of the corresponding protein digestibility, although marked differences occurred from one amino acid to another in the same food.     

Production of bioactive secondary metabolites by marine vibrionaceae

Bacteria belonging to the Vibrionaceae family are widespread in the marine environment. Today, 128 species of vibrios are known. Several of them are infamous for their pathogenicity or symbiotic relationships. Despite their ability to interact with eukaryotes, the vibrios are greatly underexplored for their ability to produce bioactive secondary metabolites and studies have been limited to only a few species. Most of the compounds isolated from vibrios so far are non-ribosomal peptides or hybrids thereof, with examples of N-containing compounds produced independent of nonribosomal peptide synthetases (NRPS). Though covering a limited chemical space, vibrios produce compounds with attractive biological activities, including antibacterial, anticancer, and antivirulence activities. This review highlights some of the most interesting structures from this group of bacteria. Many compounds found in vibrios have also been isolated from other distantly related bacteria. This cosmopolitan occurrence of metabolites indicates a high incidence of horizontal gene transfer, which raises interesting questions concerning the ecological function of some of these molecules. This account underlines the pending potential for exploring new bacterial sources of bioactive compounds and the challenges related to their investigation.     

Proton nuclear magnetic resonance spectroscopy based investigation on propylene glycol toxicosis in a Holstein cow

Background

It is unknown which metabolites are responsible for propylene glycol (PG)-induced toxicosis, and a better understanding of the underlying mechanisms explaining incidences of abnormal behaviour of dairy cows fed PG is therefore needed.

Methods

The study included three cows of which one developed PG toxicosis. In order to investigate how the metabolism of PG differed in the cow developing toxicosis, proton nuclear magnetic resonance (NMR) spectroscopy was applied on ruminal fluids and blood plasma samples obtained before and after feeding with PG.

Results

PG toxicosis was characterized by dyspnea and ruminal atony upon intake of concentrate containing PG. The oxygen saturation of arterial blood haemoglobin and the oxygen pressure in arterial blood decreased along with the appearance of the clinical symptoms. NMR revealed differences in plasma and ruminal content of several metabolites between the cow responding abnormally to PG and the two control cows.

Conclusion

It is concluded that PG-toxicosis is likely caused by pulmonary vasoconstriction, but no unusual metabolites directly related to induction of this condition could be detected in the plasma or the ruminal fluid.     

Experiences with Duddingtonia flagrans administration to parasitized small ruminants

The aim of this study was to investigate the effect of the nematophagous fungus Duddingtonia flagrans applied orally to small ruminants in a field study in Germany.     

Vibrio anguillarum: prevalence of typical and atypical strains in marine recipients with special reference to carbohydrate pollution

Primary isolates of Vibrio anguillarum-like organisms could be separated into typical V. anguillarum (VA) and atypical V. anguillarum (AVA) by biochemical tests. The prevalence of the fish pathogenic V. anguillarum was highly influenced by carbohydrate pollution as compared to the AVA. Water an sediment counts of VA generally increased at the polluted sites during April-May and persisted at a level of approx. 100/ml water and 1,000/g sediment until October-November. A further increase in VA counts could be registered locally at the time when the sugar beet processing season started (September-October). At the control site VA counts increased during June-July to a level of 10/ml persisting until August, while the only increase in sediment counts occurred in September (100/g). The maximum counts in water and sediment were at the control site 10/ml and 100/g and the polluted sites 100,000/ml and 50,000/g, respectively.