Polka-dot grouper, Cromileptes altivelis, can utilize dietary fat efficiently

Polka‐dot grouper, Cromileptes altivelis, a highly‐prized fish in Asian live fish markets, is a slow‐growing species. Long‐chain (LCF) or medium‐chain fatty acids (MCF) were fed to polka‐dot grouper (14 g initial weight) for 8 weeks to see if growth could be stimulated. Five dietary treatments were compared: a control diet with low fat (56 g kg^?1) or diets that contained either moderate (150 g kg^?1) or high (300 g kg^?1) supplements of fat that were added either as olive oil for the LCF or coconut oil for the MCF. Control fish performed well; they grew at 2.2 g week^?1, had a dry matter feed conversion ratio of 1.0 and deposited dietary protein and energy at efficiencies of 25 and 26%. Fish fed LCF at moderate levels performed better than controls but, when fed LCF at high levels or MCF at any level, their performance was inferior to controls. We conclude that dietary supplementation with 150 g kg^?1 of LCF stimulates growth and improves protein retention of polka‐dot grouper whereas higher levels, or the same or higher levels of MCF, depress performance.     

Influence of yohimbine and tolazoline on the cardiovascular, respiratory, and sedative effects of xylazine in the horse

To determine the effects of yohimbine and tolazoline on the cardiovascular, respiratory and sedative effects of xylazine, four horses were sedated with xylazine and treated with either yohimbine, tolazoline or saline. Xylazine was administered as an intravenous (i.v.) bolus (1.0 nig/kg) followed by a continuous infusion at the rate of 12 μg/kg/min. Heart rate, respiratory rate, mean arterial pressure, arterial blood gases, and the chin-to-floor distance were recorded throughout the experiment. After 60 min, either yohimbine or tolazoline was administered i.v. in incremental doses until reversal of sedation (defined as the return of the chin-to-floor distance to baseline values) was achieved. A control group in which a saline bolus was administered instead of an antagonist drug was included for comparison.
The average dose of yohimbine administered was 0.12 ± 0.02 (SEM) mg/kg. While the average dose of tolazoline was 7.5 ± 1.1 mg/kg. Both tolazoline and yohimbine antagonized the ventricular bradycardia and A-V conduction disturbances observed with xylazine administration. No change in mean arterial pressure was observed with xylazine or yohimbine administration, but tolazoline caused persistent mild systemic hypertension. There were no clinically significant changes in respiratory rate or arterial blood gas values with administration of either xylazine, yohimbine or tolazoline. The chin-to-floor distance decreased significantly with xylazine administration and increased significantly with administration of either yohimbine or tolazoline. In conclusion, both yohimbine and tolazoline successfully antagonized the cardiovascular and CNS depression associated with xylazine administration.     

Computer simulation of metal ion—humic and fulvic acid interactions

The humate model, RANDOM, was investigated in combination with the general speciation program, PHREEQE. After an initial investigation of cobalt(II)–humic acid and copper(II)–fulvic acid interactions this coupled code approach was modified to include a sensitivity analysis which identified the ligands which were statistically significant in any one system. Subsequent speciation modelling with these significant ligands is shown to produce a reasonable agreement between experimental and modelled data. The systems chosen to demonstrate the advantages of this approach were uranyl–humate and nickel(II)–humate interactions. Although this technique is not fully developed, it shows great potential for improving the predictive qualities of the RANDOM model.     

Distribution of carbon, nitrogen, phosphorus, sulphur, and acidity in two molecular weight fractions of organic matter in soil chronosequences

Ten different topsoils from three soil chronosequences were pretreated with 0.1 m HCl and 0.1 m HCl: 0.3 m HF, then extracted with neutral 0.1 m Na₄P₂0₇, followed by 0.5 m NaOH. Pretreatments and extracts were purified and fractionated into two nominal molecular weight (MW) fractions (> 50000 and < 50000) using gel filtration. The distribution between the two MW fractions of total carbon (C), nitrogen (N), phosphorus (P), sulphur (S), total acidity, and carboxyl (COOH) acidity and their ratios relative to C were determined. Organic matter in the > 50000 MW fraction contained lower N, P, S and acidity ratios relative to C than those of the < 50000 MW fraction. The chemical nature ofthe > 50000 MW fraction remained unaffected by soil development or vegetation, whereas that of the < 50000 MW fraction changed with soil age and appeared to be influenced by vegetation. The results strongly suggest that two chemically different extractable fractions of organic matter can be isolated from most soils, represented by the active fraction (< 50000 MW) and the relatively large (> 50000 MW) and less active (passive) fraction. A three-phase system of organic matter is proposed comprising the two extractable fractions and the non-extractable component.     

Comparative Earth History and Late Permian Mass Extinction

The repeated association during the late Neoproterozoic Era of large carbon-isotopic excursions, continental glaciation, and stratigraphically anomalous carbonate precipitation provides a framework for interpreting the reprise of these conditions on the Late Permian Earth. A paleoceanographic model that was developed to explain these stratigraphically linked phenomena suggests that the overturn of anoxic deep oceans during the Late Permian introduced high concentrations of carbon dioxide into surficial environments. The predicted physiological and climatic consequences for marine and terrestrial organisms are in good accord with the observed timing and selectivity of Late Permian mass extinction.     

Alcohol and caffeine: effect on inferred visual dreaming

In seven subjects, a large amount of alcohol, taken at bedtime, reduced the total duration of stage 1 electroencephalographic-rapid-eye-movement periods in the first 5 hours of sleep; a moderate amount of caffeine produced no significant change.