Oxygen consumption and ventilatory reflex responses are influenced by dietary lipids in sturgeon

The effects of one year's feeding with diets enriched either in highly unsaturated fatty acids of the w3 series (w3 HUFA) (fish oil-supplemented diet, FOD) or in saturated fatty acids (SFA) (coconut oil-supplemented diet, COD) on fatty acid composition of tissue lipids, on patterns of resting oxygen consumption and on responses to hypoxia and hypercapnia were investigated in the Adriatic sturgeon (Acipenser naccarii). FOD sturgeon had higher levels of w3 HUFA in liver and muscle lipids than COD fish, which had higher levels of SFA. A frequency distribution of instantaneous oxygen uptake rates (M]O2), as measured every 10 min for 8 h, revealed a different pattern of resting oxygen consumption between the two groups. The FOD sturgeon consumed oxygen in a narrow range of low rates, with a lower mean M]O2 than COD sturgeon, which showed a wide range of more elevated rates. FOD sturgeon had a lower opercular pressure amplitude than COD fish in normoxia. Exposure to three levels of hypoxia PO2s = 10.8±0.2; 6.6±0.2 and 4.6±0.2 kPa) or mild hypercapnia (PCO2 = 1.0±0.2 kPa) did not affect ventilation in FOD fish but elicited hyperventilation in COD animals. Mild hypoxia (PO2 = 10.8±0.2 kPa) and hypercapnia caused less reduction in blood oxygen content in FOD as compared with COD sturgeon. The effects of adding vitamin E supplements to the diets was investigated; groups fed vitamin E supplements had elevated M]O2 and hyperventilated in hypoxia. The data indicate that dietary fatty acid composition influences resting M]O2 in sturgeon and that this influences the regulation of ventilation and blood O2 levels in hypoxia and hypercapnia. The low resting M]O2 of fish fed w3 HUFA supplements (the FOD group) obviated the need for hyperventilation in hypoxia or hypercapnia, thereby making them less sensitive to these stresses than sturgeon fed SFA (COD group) or sturgeon fed either diet supplemented with vitamin E. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of changes in plasma pH,CO2 and ammonia on ventilation in trout

We investigated ventillatory responses to a plasma alkaloids and hypocapnia,a nd the basis for the ventilatory response to sodium bicarbonate (NaHCO₃) infusion in rainbow trout. Plasma alkalosis and hypocapnia created by infusion of sodium hydroxide (NaOH) did not cause hypoventilation, whereas infusion of hydrochloric acid (HCl) caused vigorous hyperventilation, associated with an acidosis, a reduction in blood O₂ content (Ca_{O 2}) and a release of circulating catecholamines. Infusion of NaHCO₃ stimulated ventilation and caused an increase in plasma pH, total carbon dioxide content (Ca_{CO 2}) and catecholamine levels, and a reduction in oxygen tension (Pa_{O 2}). Infusion of ammonium bicarbonate (NH ₄HCO₃) caused hyperventilation and was associated with an increase in Ca_{CO 2} and plasma total ammonia (C_amm) and ammonia gas (NH₃) concentration. Infusion of sodium chloride (NaClI) and Cortland's saline had no effect on ventilation. The results indicate that trout do not exhibit the ventilatory sensitivity to pH seen in terrestrial vertebrates. Ventilatory responses to NaHCO₃ appear to have been a result of reductions in Pa_{O 2}, a release of catecholamines and an increase in Ca_{CO 2} whereas responses to NH₄HCO₃ appear to have been a result of increases in Ca_{CO 2} and C_amm.     

Influence of dietary blends of menhaden oil and canola oil on growth, muscle lipid composition, and thyroidal status of Atlantic salmon (Salmo salar) in sea water

The effects of various dietary blends of menhaden oil (MO) with canola oil (CO) on the growth performance, whole body proximate composition, flesh quality (muscle proximate and lipid composition) and thyroidal status of immature Atlantic salmon in sea water were studied.Atlantic salmon (initial weight, 145.2–181.3 g), held on a natural photoperiod and in 1100 L fibreglass tanks that were supplied with running, aerated (D.O., 9–10.5 p.p.m.), ambient temperature (8–10.5 °C) sea water (salinity, 28–30), were fed twice daily to satiation one of four isonitrogenous (36% digestible protein) and isoenergetic (18.8 MJ of digestible energy kg^-1) extruded high-energy diets for 112 days. All diets contained omega –3 (n-3) fatty acids in excess of requirements and differed only with respect to the source of the supplemental lipid which was either, 25% MO; 20.75% MO and 4.25% CO; 16.5% MO and 8.5% CO; or 12.25% MO and 12.75% CO. Thus, CO comprised, respectively, 0, 15.5, 31.2, or 47.0% of the total dietary lipid content (28% on an air-dry basis).Dissimilar percentages of saturated fatty acids in the dietary lipids were not found to be consistently related to the apparent gross energy digestibility coefficients of the diets. Atlantic salmon growth, dry feed intake, feed and protein utilization, percent survival, thyroidal status, and whole body and muscle proximate compositions were generally not influenced by the different sources of supplemental lipid. Therefore, our results suggest that canola oil may comprise as much as 47% of the lipid in high-energy grower diets for Atlantic salmon without compromising performance.The muscle lipid compositions generally mirrored those of the dietary lipids which, in turn, were influenced strongly by the concentrations and compositions of the CO and MO in the diet. Hence, as the dietary CO level was increased there were attendant increases in percentages of oleic acid (18:1(n-9)), linoleic acid (18:2(n-6)), total omega-6 (n-6) fatty acid content, and ratios of (n-6) to (n-3) and decreases of eicosapentaenoic acid (EPA; 20:5(n-3)), docosahexaenoic acid (DHA; 22:6(n-3)) and n-3 HUFAs (EPA & DHA) in the flesh lipids. The ranges for percentages of saturated and unsaturated fatty acids in the flesh lipids were, however, much less than those noted respectively in the dietary lipids probably because of selective metabolism of many of the former acids and some of the 18 carbon unsaturates for energy purposes.     

Rheological Properties of Full-Formula Doughs Derived from Near-Isogenic 1BL/1RS Translocation Lines

Four pairs of near-isogenic wheat lines, with and without the 1BL/1RS translocation, and differing at the Glu-1 loci (coding for high molecular weight [HMW] glutenin subunits) were evaluated for their dough mixing properties, dough stickiness, and baking performance. In all 1BL/1RS translocation lines, weakening of the dough consistency occurred within 2 min past peak time. The full-formula dough from every 1BL/1RS translocation line exhibited poor dough mixing characteristics and increased stickiness compared to the corresponding wheat control. The HMW glutenin subunits coded by the Glu-A1 locus had no apparent effect on mixing properties, but did have a slight effect on the dough stickiness at two of the four stages of dough mixing. Glu-B1 and Glu-D1 loci encoded glutenin subunits produced significant changes in dough mixing properties and dough stickiness, respectively. With respect to baking performance, there was no significant difference between loaf volumes of 1BL/1RS versus control wheats for three of four near-isogenic pairs. Within the 1RS-group, the translocation lines containing HMW glutenin subunits 5+10 produced bread with greater loaf volumes than the pairs containing its allelic counterpart 2+12. Loaf volume was not influenced by the subunits associated with the Glu-B1 loci. In general, the breads baked from 1BL/1RS translocation lines had a relatively poor crumb and crust quality and contained larger gas cells than the wheat controls. In comparing isogenic pairs, the magnitude of the difference in loaf volume between the control wheat and the corresponding 1BL/1RS translocation line was greater in the pair unique for HMW subunits 5+10; the difference was primarily due to the stronger mixing properties of the wheat control.     

Resilience of microorganisms and aggregation of a sandy calcareous soil to amendment with organic and synthetic fertilizer

Marginal coastal soils are dependent on appropriate land management to prevent soil erosion, as a result of low soil stability combined with exposure to strong winds. An example of such an area is the machair, a fixed dune system utilized for agriculture in the northwest of Scotland, UK. The separate and combined effects of synthetic NPK fertilizer and a traditional soil conditioner (kelp, a seaweed) on soil structure formation, stabilization and biological parameters were studied on a cropped field on the machair. Soil physical properties examined included water retention at 10 kPa matric suction, water stable aggregates (WSA) >1 mm, aggregate stability, and biological properties including ester-linked fatty acid (ELFA) analysis and β-glucosidase activity for microbial biomass and activity, respectively. Significant treatment effects were few and inconsistent between sampling times, but included kelp and/or NPK fertilizer reducing aggregation, water retention, microbial biomass and activity relative to the unamended control treatment. Furthermore, seasonal variation, which could be attributed to changes in soil water content, was stronger than variation in response to fertilizer treatments. Principal components analysis of the ELFA data showed that ploughing promoted fungal biomass relative to bacteria, and confirmed both the absence of consistent synthetic and organic fertilizer effects and the sensitivity of microbial biomass to season. Overall, the study demonstrated the resilience of a calcareous sandy soil to amendment with fertilizer.     

Selecting representative reserve systems in remote areas: A case study in the Nullarbor region, Australia

We present a procedure for the selection of a network of reserves representing the biological diversity of a large and biologically poorly known region. The quantitative analysis gives equal weighting to a wide array of different species: mobile and sessile, long-lived and ephemeral, heterothermic and homeothermic, etc.

Sampling was based on quadrats that were positioned through the region using a stratified random strategy. This provided a presence-absence matrix of the species composition at each quadrat. Numerical pattern analysis was used to identify 14 species assemblages and to re-order the sites and species in the data matrix. The geographic pattern of each assemblage throughout the region was described by contouring assemblage richness, the isolines being the proportion of the number of species in each assemblage. The data matrix was re-examined. Some assemblages exhibit several gradients in species composition. For example, a 0·1 isoline in the east may represent a different 10% of species than a 0·1 isoline in the west. Other assemblages exhibit only a single gradient in species composition.

The results were used to select the optimum positions of reserves needed to represent the compositional diversity of each of the 14 species assemblages.

Limited field checking confirmed the predicted isolines in assemblage compositional richness to a satisfactory extent.     

Nutritional and physiological responses of young growing rats to diets containing raw cowpea seed meal,protein isolate (globulins), or starch

The nutritional and physiological effects of raw cowpea (Vigna unguiculata (L) Walp.) seed meal, protein isolate (globulins), or starch on the metabolism of young growing rats have been evaluated in 14-day trials. Wet and dry weight gain, feed conversion efficiency, and lipid and protein accretion were significantly reduced as a result of inclusion of seed meal, globulins, or starch in the diet, with growth retardation being most marked with the seed meal. The proportional weights of the small intestine and pancreas were increased by meal diets, and serum cholesterol levels were slightly reduced. The globulins and raw starch also increased relative small intestine weights but had no effect on the pancreas or serum constituents. The effects of cowpeas on rats appeared to be due primarily to the combined actions of globulins, resistant starches, protease inhibitors, and possibly fiber and non-starch polysaccharides on intestinal and systemic metabolism.     

Amelioration of a hardsetting Alfisol through deep mouldboard ploughing, gypsum application and double cropping. III. Crop production and profitability

Deep mouldoard ploughing to 0.45 m, gypsum application (5 t ha⁻¹), and double cropping were evaluated, alone and combined, as ameliorants for a hardsetting red-brown earth (Alfisol). The double cropped treatment consisted of winter wheat (Triticum aestivum) and a summer forage crop consisting of sudax (Sorghum sudanese) intersown with cowpea (Vigna unguiculata). This paper describes the effect of these treatments on crop development, yield, crop-water relations and economic returns. Crop emergence was not affected by any treatment. Mouldboard ploughing significantly increased wheat grain yield from 1.86 to 2.15 t ha⁻¹, in 1984, but not in 1985. Yield was also increased from 5.18 to 5.68 t ha⁻¹ as a result of gypsum addition in 1985—after no significant difference in 1984. Double cropping significantly increased yield (by 0.6 t ha⁻¹) in 1985. Greater increases were obtained with the summer cropping phase where higher evaporative demand during the summer would have aggravated soil structural problems associated with hardsetting. Sudax-cowpea dry matter yields were increased from 13.6 to 17 t ha⁻¹ and from 13.0 to 17.5 t ha⁻¹ during summer 1984–1985 by gypsum and mouldboard ploughing, respectively. The higher yields are attributed to increased water storage and depletion, and reduced soil strength for the mouldboard ploughed and gypsum main treatments. No interactions were found between the main treatments, except at the end of the 1985 winter cropping phase when there was a negative interaction between mouldboard ploughing and gypsum application for dry matter, equivalent root length and yield. The yield increases associated with mouldboard ploughing did not persist beyond the second year of the experiment. Double cropping combined with mouldboard ploughing (Mb+DC) was the most profitable treatment, whereas mouldboard ploughing with gypsum (Mb+G) was the least profitable for the crops grown in this experiment.     

Inhibition of the complement cascade by the major secretory protein of vaccinia virus

The complement system contributes to host defenses against invasion by infectious agents. A 35-kilodalton protein, encoded by vaccinia virus and secreted from infected cells, has sequence similarities to members of a gene family that includes complement control proteins. Biochemical and genetic studies showed that the viral protein binds to derivatives of the fourth component of complement and inhibits the classical complement cascade, suggesting that it serves as a defense molecule to help the virus evade the consequences of complement activation.     

Venus volcanism: initial analysis from magellan data

Magellan images confirm that volcanism is widespread and has been fimdamentally important in the formation and evolution of the crust of Venus. High-resolution imaging data reveal evidence for intrusion (dike formation and cryptodomes) and extrusion (a wide range of lava flows). Also observed are thousands of small shield volcanoes, larger edifices up to several hundred kilometers in diameter, massive outpourings of lavas, and local pyroclastic deposits. Although most features are consistent with basaltic compositions, a number of large pancake-like domes are morphologically similar to rhyolite-dacite domes on Earth. Flows and sinuous channels with lengths of many hundreds of kilometers suggest that extremely high effusion rates or very fluid magmas (perhaps komatiites) may be present. Volcanism is evident in various tectonic settings (coronae, linear extensional and compressional zones, mountain belts, upland rises, highland plateaus, and tesserae). Volcanic resurfacing rates appear to be low (less than 2 Km(3)/yr) but the significance of dike formation and intrusions, and the mode of crustal formation and loss remain to be established.