Responses of Atlantic cod <Emphasis Type="Italic">Gadus morhua</Emphasis> head kidney leukocytes to phytase produced by gastrointestinal-derived bacteria

This study identified phytase-producing bacteria that were previously isolated from the gastrointestinal tract of Atlantic cod, Gadus morhua and determined its effect on head kidney leukocytes. Out of the 216 bacterial strains tested, the two phytase producers were identified as Pseudomonas sp. and Psychrobacter sp. based on their 16S rDNA sequence. Crude phytase from these two bacterial strains was produced employing the shake flask method. Even though the total protein of the crude phytase was not significantly different for the two bacteria, the phytase activity of the crude enzyme produced by Pseudomonas sp. (97.1 ± 16.7 U) was significantly higher than that of the enzyme from Psychrobacter sp. (75.9 ± 2.4 U). When cod head kidney leukocytes were incubated with the crude phytase (50 μg ml⁻¹), it resulted in enhanced cell proliferation, higher myeloperoxidase, and acid phosphatase activities. Extracellular responses—respiratory burst activity and hydrogen peroxide production were not enhanced by the crude enzyme. As a consequence, the growth of two pathogenic bacteria Aeromonas salmonicida and Vibrio anguillarum was not suppressed by the supernatants obtained from head kidney leukocytes incubated with the crude bacterial phytase. Thus, the enzyme from phytase-producing intestinal bacteria of Atlantic cod can stimulate intracellular head kidney leukocyte activities but not the production of extracellular substances that are involved in antibacterial response. These have implications on the potential use of bacterial phytase as feed supplement to boost cellular immune response of the fish and could be employed as a health management strategy in culture systems.     

Fine-scale movement patterns, site fidelity, and habitat selection of ocean whitefish (Caulolatilus princeps)

The fishery for California groundfishes is managed using broad species complexes, although some non-groundfish species are managed similarly due to the perception of shared behavioral characteristics. This study integrates acoustic telemetry and a GIS to quantify movement patterns of one such species, the ocean whitefish (Caulolatilus princeps) in a marine protected area. Seventeen ocean whitefish were tagged and actively tracked over multiple 24-h periods to measure fine-scale movement patterns. Home ranges based on 95% kernel utilization distributions averaged 20,439 ± 28,492 (±S.D.) m². Fish were active during the day, foraging over sand habitat at depths averaging 21 ± 8 m, but were inactive at night, taking refuge near rocky reefs at depths averaging 15 ± 7 m. Seventeen additional fish were tagged with coded acoustic transmitters and passively tracked using automated underwater acoustic receivers for up to 1 year. Approximately 75% of these fish exhibited long-term (1 year) fidelity to home ranges in the study area. Results suggest that MPAs can be an effective means of protecting populations of ocean whitefish and based on their habitat associations, ocean whitefish can be managed separately from other reef associated groundfishes.     

A Review of Factors Influencing Maturation of Atlantic Salmon,Salmo salar,with Focus on Water Recirculation Aquaculture System Environments

Sexual maturation of Atlantic salmon, Salmo salar, is a complex process, with many variables having the capacity to influence the timing and prevalence of maturation and acting as promoters and/or inhibitors of sexual development. Precocious maturation has the capacity to seriously impact production in commercial aquaculture settings, and in response there has been a significant amount of research devoted to understanding this issue in order to develop remedial strategies. Very little research has been conducted specifically examining salmon maturation in land‐based, closed containment water recirculation aquaculture systems, which have recently received attention as an alternative technology for the sustainable production of market‐size Atlantic salmon. Unfortunately, the nascent closed containment salmon industry has thus far experienced high levels of precocious maturation, for reasons that are presently unclear. Given the economic challenges facing the closed containment industry's expansion, it is imperative that best management practices be developed to reduce economic losses from early maturation, in order to assist the sustainable growth of farmed Atlantic salmon production. This review provides a brief summary of published research on factors associated with early salmonid maturation, as well as information from research examining maturation and growout performance of Atlantic salmon in closed containment aquaculture systems.     

Reproductive ecology of the threatened and endemic freshwater mussel Lampsilis bracteata

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Trade‐offs in triple‐bottom‐line outcomes when recovering fisheries

Almost all environmental management comes at an economic cost that may not be borne equitably by all stakeholders. Here, we investigate how heterogeneity in catch and profits among fishers influences the trade‐off among the triple‐bottom‐line objectives of recovering a fish population, maximizing its economic value and distributing restrictions equitably across fishers. As a case‐study, we examine management reform of an ecologically and economically important coral reef fishery operating within the Great Barrier Reef Marine Park. Using a simulation model, we find that total profitability of the fishing industry is 40% lower if recovery plans are equitable when compared to the most economically efficient plan. However, efficient recovery plans were typically highly inequitable because they required some fishers to cease fishing. Equity was defined according to different norms, and the efficiency loss was greatest when catch losses were shared equally across fishers rather than in proportion to their historical catch. We then varied key social, economic and biological parameters to identify cases when equity and efficient recovery would trade‐off most strongly. Recovery plans could be both efficient and equitable when heterogeneity in fisher's catches and individual catch efficiencies was lower. If fishers were homogenous then equitable plans could have maximal economic efficiency. These results emphasize the importance of considering heterogeneity in individual fishers when designing recovery plans. Recovery plans that are inequitable may often fail to gain stakeholder support, so in fisheries with high heterogeneity we should temper our expectations for marked increases in profits.     

Influence of diet on growth,reproduction and lipid and fatty acid composition in the sea cucumber Cucumaria frondosa

The suspension‐feeding sea cucumber Cucumaria frondosa is widely distributed in cold waters and is commercially exploited in the North Atlantic. While the species is considered to have potential for aquaculture, its feeding and reproductive biology differs markedly from that of currently cultivated sea cucumbers. Here, for the first time, the influence of food sources on the condition of C. frondosa was experimentally tested. Individuals were fed with either diatoms or fish eggs for 3 months. Specific growth rate (SGR), organ indices, fecundity, gonad maturity and profiles of lipids and fatty acids (FA) in tissues were compared among treatments and with sea cucumbers collected from the field. Individuals fed with fish eggs showed higher SGR and organ indices than all other treatments. The highest proportion of large oocytes was also found in gonad tubules of females from the fish egg treatment, although individuals fed with diatoms were the only ones in which spontaneous spawning occurred. Moreover, gonad and muscle tissues of sea cucumbers from the fish egg treatment presented the highest levels of lipids and essential FA. In contrast, non‐fed sea cucumbers showed negative SGR, relatively low female fecundity and low concentrations of lipids and FA in tissues. While the fish egg diet presented several obvious benefits, phytoplankton remains an important source of carotenoids, which are vital for vitellogenesis in echinoderms. This indicates that mixed diets rich in lipids, essential FA and carotenoids can be further investigated to optimize growth and reproductive output of this species in captivity.     

Aquaculture potential of the basket cockle (Clinocardium nuttallii). Part 1: effects of stocking density on first year grow‐out performance in intertidal and off‐bottom suspended culture

The basket cockle (Clinocardium nuttallii) is a candidate species for aquaculture in the northeast Pacific. The aim of the current research was to assess the feasibility of C. nuttallii grow‐out, with an emphasis on growth performance and qualities affecting product marketability. In this article, we investigated the combined effects of culture mode (intertidal and off‐bottom suspended culture) and initial stocking density (1500, 3000, 10 500 and 21 000 ind m^?2) on C. nuttallii survival and growth during the first year of grow‐out (May through October). In intertidal culture, cockles exhibited low survival and poor growth rates. In suspended culture, survival was consistently high (>96%) at all stocking densities tested; growth and condition parameters had the highest values at 1500 and 3000 ind m^?2. The edible portion (meat yield) exceeded 40% of the whole wet weight at all stocking densities, occurrences of fouled and deformed cockles were <1% and no commensal species were observed. Depending on the minimum harvestable size and stocking density chosen, harvestable proportions constituted from 1.1% to 15.2% by October of the first grow‐out year in the suspended system. The effects of stocking density and depth on second year grow‐out performance of C. nuttallii are reported in a companion paper (Dunham et al. in this issue).     

Physiological and reproductive response to varying quantitative lipid inclusion in diets for Gulf killifish Fundulus grandis Baird and Girard

Successful culture of Gulf killifish Fundulus grandis as a live marine baitfish in the south‐eastern United States has experienced low fecundity as a primary restriction. Hence, the ability to optimize reproduction in captive populations may increase the potential for viable large‐scale production. Broodfish nutrition is an expanding field of aquaculture, and improved nutritional status has been shown to increase reproductive output in some cultured fish. This study examined changes in quantitative inclusion of lipid as fish oil in complete diets fed to actively spawning Gulf killifish and its effects on physiological and reproductive parameters and subsequent larval morphometrics. An increase in dietary lipid levels across a gradient from 4.0 to 13.8% did not affect periodic fecundity, egg size, embryo viability rate, sperm motility, hepatosomatic index or liver total lipid content. Intraperitoneal fat increased significantly in fish fed higher lipid levels, while gonadosomatic index was significantly higher in the lowest lipid content group. Larvae produced by fish fed higher lipid levels had significantly increased endogenous nutritional resources at hatch while standard length was unaffected. No strong reproductive benefits of increased lipid inclusion were found in Gulf killifish.     

The Two Cultures of Science： Implications for University-Industry Relationships in the U.S. Agriculture Biotechnology

Partnerships between U.S. universities and industries have existed for several decades and in recent years have become generally more varied, wider in scope, more aggressive and experimental and higher in public visibility. In addition, in the last few decades, public and private interests have advocated for government policies and laws to globally promote the commercialization of university science. This paper examines the persistence or convergence of the two cultures of science and the implications of this commercialization for university-industry relationships in agriculture biotechnology. The perceptions and values of over 200 U.S. university and industry scientists, managers and administrators who participate in or oversee research collaborations in agricultural biotechnology were analyzed. The findings revealed that the participants in these research relationships continue to perceive very distinct cultures of science and identify a wide range of concerns and disadvantages of these partnerships. Several actions were discussed to ensure that the two cultures serve complementary roles and that they maximize the public benefits from these increasing collaborations.     

Rocket launcher mechanism of collaborative actin assembly defined by single-molecule imaging

Interacting sets of actin assembly factors work together in cells, but the underlying mechanisms have remained obscure. We used triple-color single-molecule fluorescence microscopy to image the tumor suppressor adenomatous polyposis coli (APC) and the formin mDia1 during filament assembly. Complexes consisting of APC, mDia1, and actin monomers initiated actin filament formation, overcoming inhibition by capping protein and profilin. Upon filament polymerization, the complexes separated, with mDia1 moving processively on growing barbed ends while APC remained at the site of nucleation. Thus, the two assembly factors directly interact to initiate filament assembly and then separate but retain independent associations with either end of the growing filament.