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.     

Linking Northeast Pacific recruitment synchrony to environmental variability

We investigated the hypothesis that synchronous recruitment is due to a shared susceptibility to environmental processes using stock–recruitment residuals for 52 marine fish stocks within three Northeast Pacific large marine ecosystems: the Eastern Bering Sea and Aleutian Islands, Gulf of Alaska, and California Current. There was moderate coherence in exceptionally strong and weak year‐classes and correlations across stocks. Based on evidence of synchrony from these analyses, we used Bayesian hierarchical models to relate recruitment to environmental covariates for groups of stocks that may be similarly influenced by environmental processes based on their life histories. There were consistent relationships among stocks to the covariates, especially within the Gulf of Alaska and California Current. The best Gulf of Alaska model included Northeast Pacific sea surface height as a predictor of recruitment, and was particularly strong for stocks dependent on cross‐shelf transport during the larval phase for recruitment. In the California Current the best‐fit model included San Francisco coastal sea level height as a predictor, with higher recruitment for many stocks corresponding to anomalously high sea level the year before spawning and low sea level the year of spawning. The best Eastern Bering Sea and Aleutian Islands model included several environmental variables as covariates and there was some consistent response across stocks to these variables. Future research may be able to utilize these across‐stock environmental influences, in conjunction with an understanding of ecological processes important across early life history stages, to improve identification of environmental drivers of recruitment.     

Management strategy influences landscape patterns of high-severity burn patches in the southwestern United States

Landscape Ecology - Spatial patterns of high-severity wildfire in forests affect vegetation recovery pathways, watershed dynamics, and wildlife habitat across landscapes. Yet, less is known about...     

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.     

The frictional behaviour of wood

Summary The work described was primarily concerned with determining the more important variables affecting friction between wood and steel, but friction between wood and non-ferrous materials including wood itself was also investigated briefly. Deviations from the classical laws of friction were of interest, the most significant being variation of friction coefficient with sliding speed. With an increase in sliding speed up to 4 m/sec the curves for highly polished steel showed undulations, but with unpolished surfaces there was a monotonic reduction, somewhat greater in wet wood than dry. Other important factors, interacting with sliding speed, were steel roughness and wood moisture content. Effects of load, nominal contact area and fibre direction were minor. The results appear to be adequately explained in terms of adhesion and lubrication.A world wide selection of species was tested, and it appears that the nature and amount of extractives in most woods is such that they have similar friction coefficients except on very smooth steel, and only a few greasy species, have significantly lower coefficients. For most air-dry wood in contact with unpolished steel, the coefficient decreases from a static value about 0.65 to a value about 0.4 at 4 m/sec. For wet wood, the corresponding values are about 0.7 and 0.15.Coefficients of friction between wood and wood were similar to those between wood and rough steel, and those between wood and other materials varied in a manner which may be related to strength of adhesion.

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Zusammenfassung Die ursprüngliche Zielsetzung der Arbeit, die Untersuchung der wesentlichen Einflußgrößen auf die Reibung zwischen Holz und Stahl wurde durch Einbeziehung von Nichteisen-Metallen und der Reibung zwischen Holz und Holz erwitert. Als bemerkenswert stellten sich die Abweichungen von den klassischen Reibungsgesetzen heraus, am auffallendsten die Änderung der Reibung mit der Vorschubgeschwindigkeit. Beim Anstieg der Vorschubgeschwindigkeit bis zu 4 m/s zeigten die Kurven für hochglanzpolierten Stahl Unstetigkeiten, während bei unpoliertem Stahl ein gleichförmiger Abfall eintrat, der bei nassem Holz etwas größer war als bei trockenem. Weitere wichtige Einflußgrößen waren Stahlart und Holzfeuchtigkeit. Die Wirkungen von Normaldruck, Kontaktfläche und Faserrichtung waren von untergeordneter Bedeutung. Die erzielten Ergebnisse lassen sich in etwa gleicher Weise durch Begriffe aus den Gebieten der Adhäsion oder der Schmierung beschreiben.Es wurde angestrebt, möglichst alle wichtigen Holzarten der Welt zu erfassen. Man kann sagen, daß die Inhaltsstoffe der meisten Hölzer nach Art und Menge zu ziemlich ähnlichen Reibungskoeffizienten führen, ausgenommen bei sehr glatten Stahlarten. Nur wenige fetthaltige Holzarten weisen deutlich niedrigere Reibungskoeffizienten auf. Für lufttrockenes Holz und unpolierten Stahl fällt der Koeffizient von 0,65 für Haftreibung auf 0,40 für gleitende Reibung bei 4 m/s Vorschubgeschwindigkeit. Bei nassem Holz lauten die entsprechenden Werte 0,70 und 0,15. Die Reibungskoeffizienten zwischen Holz und Holz waren ähnlich denen zwischen Holz und rauhem Stahl; diejenigen zwischen Holz und anderen Materialien variierten so, daß ein Zusammenhang mit den Adhäsionskräften anzunehmen ist.

     

Root reductant release as a measure of sorghum cultivar iron efficiency

Measurement of root reductant levels developed during plant Fe stress was tested as a possible assay for sorghum cultivar Fe‐efficiency screening. Iron‐stressed sorghum was shown to release reductants into CaCO₃ buffered nutrient solution; however, considerably more plants could be tested by extracting reductants from excised roots of Fe‐stressed sorghum in 35 ml of pH 3 nutrient solution and 1 mM glucose. An Fe‐efficient cultivar, RT×2536, and an Fe‐inefficient cultivar, BT×378, could be separated by measurement of reductants released into CaCO₃ buffered nutrient solution and by an excised root extraction method; however, neither method was as effective as visual rating methods.     

Biofortification of tomato (Solanum lycopersicum) fruit with the anticancer compound methylselenocysteine using a selenocysteine methyltransferase from a selenium hyperaccumulator

Methylselenocysteine (MeSeCys) is an amino acid derivative that possesses potent anticancer activity in animals. Plants that can tolerate growth on soils with high Se content, known as Se hyperaccumulators, do so by converting inorganic Se to MeSeCys by the enzyme selenocysteine methyltransferase (SMT). A cDNA encoding the SMT from a Se hyperaccumulator was overexpressed in tomato (Solanum lycopersicum). Transgenic plants were provided with selenite or selenate to the roots during fruit development, and liquid chromatography-mass spectrometry was used to show that MeSeCys accumulated in the fruit but not in the leaves. Depending on the transgenic line and Se treatment, up to 16% of the total Se in the fruit was present as MeSeCys. MeSeCys was produced more effectively from selenite on a percentage conversion basis, but greater accumulation of MeSeCys could be achieved from selenate due to its better translocation from the roots. MeSeCys was heat stable and survived processing of the fruit to tomato juice.     

No place to nest or bask: Effects of human disturbance on the nesting and basking habits of yellow-blotched map turtles (Graptemys flavimaculata)

Considerable recent attention has focused on how human disturbance alters the behaviour of imperiled taxa. Data on such impacts are common for waterfowl, marine mammals, and some large game animals. However, little is known about how human disturbances affect reptiles, perhaps because most reptiles are secretive and are not commonly seen by the public. We studied the impact of human disturbances on the nesting and basking behaviour of the yellow-blotched map turtle (Graptemys flavimaculata) on the Pascagoula River in southeastern Mississippi, USA. We found that both nesting and basking behaviour of map turtles were altered by human recreational activities. Turtles attempting to nest commonly abandoned their attempts upon the approach of a boat and, prior to nesting, numerous individuals waited several hours near the beach without emerging. Basking turtles frequently dove into the water upon the approach of a boat and some did not return to bask. Anglers in small boats that remained in the vicinity of basking sites caused the most disturbances, whereas personal water crafts (jet skis) caused fewer disturbances. Our data suggest that interruption of nesting activities may have an especially severe impact on the viability of this population through changes in numbers of clutches females are able to lay and altering the microhabitat females select for their nests.