Effects of mild drought stress on the morpho-physiological characteristics of a bambara groundnut segregating population     

Hui Hui Chai  Festo Massawe  Sean Mayes 《Euphytica》2016,207(2):225-243

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Marine-Derived Quorum-Sensing Inhibitory Activities Enhance the Antibacterial Efficacy of Tobramycin against Pseudomonas aeruginosa     

Alessandro Busetti  George Shaw  Julianne Megaw  Sean P. Gorman  Christine A. Maggs  Brendan F. Gilmore 《Marine drugs》2015,13(1):1-28

Bacterial epiphytes isolated from marine eukaryotes were screened for the production of quorum sensing inhibitory compounds (QSIs). Marine isolate KS8, identified as a Pseudoalteromonas sp., was found to display strong quorum sensing inhibitory (QSI) activity against acyl homoserine lactone (AHL)-based reporter strains Chromobacterium violaceum ATCC 12472 and CV026. KS8 supernatant significantly reduced biofilm biomass during biofilm formation (−63%) and in pre-established, mature P. aeruginosa PAO1 biofilms (−33%). KS8 supernatant also caused a 0.97-log reduction (−89%) and a 2-log reduction (−99%) in PAO1 biofilm viable counts in the biofilm formation assay and the biofilm eradication assay respectively. The crude organic extract of KS8 had a minimum inhibitory concentration (MIC) of 2 mg/mL against PAO1 but no minimum bactericidal concentration (MBC) was observed over the concentration range tested (MBC > 16 mg/mL). Sub-MIC concentrations (1 mg/mL) of KS8 crude organic extract significantly reduced the quorum sensing (QS)-dependent production of both pyoverdin and pyocyanin in P. aeruginosa PAO1 without affecting growth. A combinatorial approach using tobramycin and the crude organic extract at 1 mg/mL against planktonic P. aeruginosa PAO1 was found to increase the efficacy of tobramycin ten-fold, decreasing the MIC from 0.75 to 0.075 µg/mL. These data support the validity of approaches combining conventional antibiotic therapy with non-antibiotic compounds to improve the efficacy of current treatments.  相似文献   

Digestible and metabolizable energy concentrations and amino acid digestibility of dried yeast and soybean meal for growing pigs     

Chan Sol Park  Ayodeji Simeon Aderibigbe  Darryl Ragland  Olayiwola Adeola 《Journal of animal science》2021,99(1)

Energy values and amino acid (AA) digestibility of dried yeast (DY) and soybean meal (SBM) were determined in 2 experiments with growing pigs. Experiment 1 was conducted to determine the digestible energy (DE) and metabolizable energy (ME) in DY and SBM. Thirty barrows with a mean initial body weight (BW) of 20.6 kg (SD = 1.04) were assigned to 5 dietary treatments in a randomized complete block design with period and BW as blocking factors. A reference diet was prepared with corn, canola meal, and soybean oil as energy-contributing ingredients. Four additional diets were prepared by adding 5% and 10% DY or SBM at the expense of energy-contributing ingredients in the reference diet. The ratio of corn, canola meal, and soybean oil was kept consistent across the experimental diets. Each experimental period consisted of 5-d adaptation and 5-d quantitative collection of feces and urine. Test ingredient-associated DE or ME intake (kcal/d) was regressed against test ingredient intake [kg dry matter (DM)/d] to estimate the DE or ME in test ingredients as the slope of linear regression model. The DE in DY was estimated at 3,933 kcal/kg DM, which was not different from the estimated DE in SBM at 4,020 kcal/kg DM. Similarly, there was no difference between DY and SBM in the estimated ME (3,431 and 3,756 kcal/kg DM, respectively). Experiment 2 was conducted to determine the standardized ileal digestibility (SID) of AA in DY and SBM. Twenty-one barrows with a mean initial BW of 20.0 kg (SD = 1.31) were surgically fitted with T-cannulas at the distal ileum and assigned to 3 dietary treatments in a randomized complete block design with BW as a blocking factor. Two semi-purified diets containing DY or SBM as the sole nitrogen source and one nitrogen-free diet (NFD) were prepared. The NFD was used to estimate the basal ileal endogenous losses of CP and AA. Pigs were fed the 3 diets for 5 d as adaptation, followed by 2 d of feeding with ileal digesta collection. The SID of AA, except Gly and Pro, in DY was less (P < 0.05) than in SBM. The SID of indispensable AA in DY ranged from 64.1% for Thr to 85.2% for Arg, and those in SBM ranged from 83.9% for Thr to 91.8% for Arg. In conclusion, energy values of DY are not different from those of SBM, whereas AA in DY is less digestible than in SBM. The estimated DE and ME as well as the SID of AA in DY and SBM can be used in diet formulation for growing pigs using these ingredients.  相似文献   

A recombinant-based ELISA evaluating the efficacy of netobimin and albendazole in ruminants with naturally acquired fascioliasis     

María Sol Arias  Jos Luis Surez  G.V. Hillyer  Ivn Francisco  Enrique Calvo  Rita Snchez-Andrade  Pablo Díaz  Rubn Francisco  Pablo Díez-Baos  Patrocinio Morrondo  Adolfo Paz-Silva 《Veterinary journal (London, England : 1997)》2009,182(1):73-78

The therapeutic efficacy of albendazole and netobimin in ruminants with naturally occurring fascioliasis was investigated using a recombinant-based ELISA. The variation in the IgG response against a 2.9-kDa recombinant protein (FhrAPS), termed efficacy index (EI) 1, and the egg-output changes, termed EI 2, were used to evaluate drug efficacy.The values of EI 1 ranged between 0% and 50% in sheep, and between 0% and 30% in cattle after treatment with albendazole and netobimin. Similar EI 2 values were observed in sheep receiving albendazole or netobimin, but the highest values were found in cattle treated with netobimin. The significant reduction in the IgG response to FhrAPS found in this study shows promise in terms of developing alternative methods for evaluating the efficacy of chemotherapy against Fasciola hepatica in grazing ruminants.  相似文献   

Factors affecting adoption of hedgerows and other biodiversity-enhancing features on farms in California, USA     

Sonja Brodt  Karen Klonsky  Louise Jackson  Stephen B. Brush  Sean Smukler 《Agroforestry Systems》2009,76(1):195-206

Although hedgerows, windbreaks, and other biodiversity-enhancing farm edge features offer the potential for ecosystem benefits without occupying much crop space, relatively few farms in California, USA include such features. Our study identified the practices currently used to manage non-cropped edges of fields, ponds, and watercourses in a case study area in California. We also identified social, economic, and agronomic incentives and constraints to installing biodiversity-enhancing edge features. More than one-third of the study farmers had installed native hedgerows, windbreaks, and/or grassed edges. Interviews demonstrated the importance of socially influential farmers working in tandem with public and private agencies to build initial interest in these practices. However, these features occupied less than four percent of all possible edge length. Constraints to increasing adoption included high costs, fear of harbouring weeds and rodents, and lack of certainty about ecosystems benefits, highlighting the need for cost-share programs and more regionally-focused agroecological research.  相似文献   

Alternative modes of governance: organic as civic engagement     

E. Melanie DuPuis  Sean Gillon 《Agriculture and Human Values》2009,26(1-2):43-56

A major strategy in the creation of sustainable economies is the establishment of alternative market institutions, such as fair trade and local market systems. However, the dynamics of these alternative markets are poorly understood. What are the rules of behavior by which these markets function? How do these markets maintain their separate identity as “alternative”: apart from the conventional (“free”) market system? Building on Lyson’s notion of civic agriculture, we argue that alternative markets maintain themselves through civic engagement. However, we argue that the civically-engaged practices of alternative markets are poorly understood. We seek, therefore, to begin a conversation about the everyday forms of civic engagement in alternative practice and to do this we introduce a few useful conceptual tools. Building upon ideas in science studies about the collaboration of scientists (Hess, Alternative pathways in science and industry, 2007) we argue that civic markets have their own “market fields” and “modes of governance” (Bulkeley et al., Environment and Planning A 39:2733–2753, 2007), their own fields of social interaction in which rules of behavior become stabilized and determine how the market works. The creation of a social field also requires the demarcation of boundaries, referred to in the science studies literature as “boundary work” (Gieryn, Cultural boundaries of science: Credibility on the line, 1999). We apply the idea of boundary work to understand how alternative market actors maintain boundaries between alternative and conventional markets. Finally, studies of collaboration in science have often centered on the object created through these interactions, an object that is partially material and partially a product of knowledge, what (Rheinberger, Toward a history of epistemic things: Synthesizing proteins in the test tube, 1997) calls an “epistemic object.” We use this idea to understand that the creation of alternative objects of exchange, such as organic food, are epistemic objects in that they combine both particular materialities and particular ways of knowing. Using these concepts, we will carry out a close analysis of the mode of governance in the national organic market, looking specifically a recent governance crisis in organic agriculture known as the Harvey lawsuit.  相似文献   

Optimal harvesting strategies: Practice versus theory     

Sean Pascoe  Premachandra Wattage  Debananda Naik 《Aquaculture Economics & Management (Blackwell Science)》2013,17(5-6):295-308

Abstract

Over the last decade or so, a number of bioeconomic models have been developed with the expressed objective of identifying the optimal time to harvest farmed fish. The models explicitly incorporate growth rates, prices and costs, but have generally excluded risk except implicitly through the discount rate. Implicit in this is the assumption that risk is continuous, such that the probability of significant changes in key parameters (e.g. prices, mortality rates etc) is independent of time. In reality, these factors can vary over time. In this paper, the optimal harvesting strategies for two farmed species were analysed using a bioeconomic model. The model was based on previous models applied in the literature, with a new feed‐use component applied. The theoretical ‘optimal’ harvest strategy was compared with actual behaviour, and the factors that may affect divergences in the results examined.  相似文献   

Assessing opportunity and relocation costs of marine protected areas using a behavioural model of longline fleet dynamics     

Natalie A Dowling  Chris Wilcox  Marc Mangel  Sean Pascoe 《Fish and Fisheries》2012,13(2):139-157

Increasing use of spatial management tools in fisheries requires an understanding of fleet response, and in particular to where displaced fishing effort is likely to move. We develop a state‐dependent decision‐making model to address the spatial allocation of effort in an Australian tuna longline fishery. We assume that fishers have an economic objective in deciding where to fish, but that decisions in any period are also influenced by the remaining quota held at the time of the decision. Key features of the model include endogenous price dynamics, a moving stock and a competitive pool of different vessel types operating from different port locations. We utilize this model to illustrate fleet responses to marine reserves and limits on fishing effort. The results illustrate that the model framework provides advantages over statistically based models in that decisions made in response to the imposition of a reserve are not consistent with a proportional reallocation of effort. Rather, the stochastic dynamic model yielded an overall profit level of ～4% higher relative to scenarios with no reserve. Incorporating the opportunity cost of a quota into the model resulted in an optimal utilization of effort, in which effort was concentrated in time periods and locations yielding maximized profit. Under a low level of effort relative to the season length, the model indicated an overall profit level 43% greater than the highest obtained when the same level of effort was applied solely within any given quarter of the season.  相似文献   

Effects of nitrogen,phosphorus, and potassium on SPAD-502 and atLEAF sensor readings of Salvia     

Bruce L. Dunn  Hardeep Singh  Mark Payton  Sean Kincheloe 《Journal of plant nutrition》2018,41(13):1674-1683

There are various optical sensors in the market for precision nitrogen (N) management, which estimate leaf N status from chlorophyll content of leaves. However, readings may also be affected by the amounts of other nutrients in the plant leaves like potassium (K) and phosphorus (P), as well as sampling location within a plant or leaf. SPAD-502 and atLEAF optical sensors were used on Salvia ‘Vista Red’ plants grown with 0N-7.9P-0K, 41N-0P-0K, 0N-0P-31.6K, 0N-7.9P-0K + 41N-0P-0K, 0N-7.9P-0K + 0N-0P-31.6K, 41N-0P-0K + 0N-0P-31.6K, or 0N-7.9P-0K + 41N-0P-0K + 0N-0P-31.6K fertilizer plus a control. Both sensors were correlated with leaf N and each other. However, both sensor readings were affected by the presence or absence of P and K in the leaves, and thus these nutrients should be analyzed and reported along with leaf N values. Sensor readings were found to vary within a leaf and within leaf canopy location, so sampling needs to be consistent.  相似文献   

Comparison of cephalic and jugular plasma lactate concentrations in sick cats: a pilot study          下载免费PDF全文

Emily K. J. Sachs DVM  DACVECC  Tracy M. Julius DVM  DACVECC  Sean‐Paul A. Claypool MPH  Monica C. Clare VMD  DACVECC 《Journal of Veterinary Emergency and Critical Care》2017,27(2):193-197

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