Control of one invasive plant species allows exotic grasses to become dominant in northern Great Plains grasslands     

Diane L. Larson  Jennifer L. Larson 《Biological conservation》2010,143(8):1901-1910

Decline of leafy spurge (Euphorbia esula) in the northern Great Plains of the US is generally viewed as a success story for biological control, but quality of the vegetation that survived the infestation is key to recovery of ecosystem function. In addition, effects of other invasive species, notably cool-season exotic grasses, must be taken into account. Objectives of this study were (1) to evaluate direction and significance of changes in biomass of native and exotic grasses, forbs, and leafy spurge and in plant species composition following control of leafy spurge by flea beetles and (2) to evaluate the relative effects of leafy spurge and exotic grasses on biomass of native grasses, biomass of forbs, and richness of native species. We monitored species composition (1998-2003 and 2008) and biomass (2000, 2002, 2003 and 2008) of these groups on spurge-infested and noninfested permanent plots at three sites with unbroken prairie sod in North Dakota, USA. We found little evidence, in terms of species richness or biomass of native grasses or forbs, that leafy spurge was being replaced by desirable native species, although desirable as well as weedy and exotic species were characteristic of 2008 vegetation at all three sites. Structural equation models revealed that leafy spurge had temporally intermittent negative effects on forb biomass and species richness, but no effects on native grasses. In contrast, exotic grass had consistently strong, negative effects on native grass biomass, as well as stronger negative effects than leafy spurge on native species richness. Although substantial native plant diversity remains at these sites, exotic grasses pose an important threat to these crucial building blocks of native prairie ecosystems.  相似文献   

Characterization of the temperature activation of pectin methylesterase in green beans and tomatoes     

Anthon GE  Barrett DM 《Journal of agricultural and food chemistry》2006,54(1):204-211

Low-temperature blanching of vegetables activates the enzyme pectin methylesterase (PME), which demethylates cell wall pectins and improves tissue firmness. This temperature activation of PME has been investigated by measuring the formation of methanol in intact tissue of green beans and tomatoes. Rates of methanol formation at temperatures of 35-65 degrees C were obtained by measuring the release of methanol from thin slices of tomato pericarp or green bean pod material. Activation energies of 112 and 97 kJ mol(-1) were calculated for PME activity in green beans and tomatoes, respectively. These activation energies indicate that the rate of pectin demethylation at 65 degrees C will be nearly 100 times that at 25 degrees C. PME activity was also determined titrimetrically using a solubilized form of the enzyme and purified pectin at temperatures from 30 to 60 degrees C. Under these conditions, much lower activation energies of 37 and 35 kJ mol(-1) were obtained for green beans and tomatoes, respectively. Methanol accumulation during heating of whole intact green beans was also determined and yielded an activation energy similar to that obtained with sliced beans. Whole green beans held at room temperature did not accumulate any methanol, but sliced or homogenized beans did. If whole beans were first heated to 45 degrees C and then cooled, methanol accumulation was observed at room temperature. These results indicate that two factors contribute to the observed high rate of pectin de-esterification during low-temperature blanching: (1) An irreversible change, causing PME to become active, occurs by heating to > or = 45 degrees C. (2) The high activation energy for pectin de-esterification means that the rate of de-esterification increases substantially with increasing temperature.  相似文献   

Amoebic gill disease (AGD)-affected Atlantic salmon, Salmo salar L., are resistant to subsequent AGD challenge     

Vincent BN  Morrison RN  Nowak BF 《Journal of fish diseases》2006,29(9):549-559

There is inconsistent evidence of resistance of Atlantic salmon, Salmo salar L., to amoebic gill disease (AGD). Here, evidence is presented that demonstrates that Atlantic salmon exposed and subsequently challenged with AGD are more resistant than naïve control fish. Seventy‐three per cent of Atlantic salmon previously exposed to AGD survived to day 35 post‐challenge compared with 26% exposed to Neoparamoeba sp. for the first time, yet the gill pathology of surviving naïve control or previously exposed fish was not significantly different. Development of resistance to AGD is associated with anti‐Neoparamoeba sp. antibodies that were detectable in serum of 50% of surviving Atlantic salmon previously exposed to AGD. However, anti‐Neoparamoeba sp. antibodies were not detectable in cutaneous mucus of resistant fish. Increased resistance of Atlantic salmon after secondary Neoparamoeba sp. infection and detection of specific serum antibodies provides support for the development of a vaccine for AGD.  相似文献   

Profile: Thomas Kaplan. From making a killing to saving a species     

Garcia D  Stokstad E 《Science (New York, N.Y.)》2006,313(5791):1226-1227

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Islet recovery and reversal of murine type 1 diabetes in the absence of any infused spleen cell contribution     

Nishio J  Gaglia JL  Turvey SE  Campbell C  Benoist C  Mathis D 《Science (New York, N.Y.)》2006,311(5768):1775-1778

A cure for type 1 diabetes will probably require the provision or elicitation of new pancreatic islet beta cells as well as the reestablishment of immunological tolerance. A 2003 study reported achievement of both advances in the NOD mouse model by coupling injection of Freund's complete adjuvant with infusion of allogeneic spleen cells. It was concluded that the adjuvant eliminated anti-islet autoimmunity and the donor splenocytes differentiated into insulin-producing (presumably beta) cells, culminating in islet regeneration. Here, we provide data indicating that the recovered islets were all of host origin, reflecting that the diabetic NOD mice actually retain substantial beta cell mass, which can be rejuvenated/regenerated to reverse disease upon adjuvant-dependent dampening of autoimmunity.  相似文献   

Marine fisheries and future ocean conflict          下载免费PDF全文

Jessica Spijkers  Tiffany H Morrison  Robert Blasiak  Graeme S Cumming  Matthew Osborne  James Watson  Henrik Österblom 《Fish and Fisheries》2018,19(5):798-806

Conflict over marine fishery resources is a growing security concern. Experts expect that global changes in our climate, food systems and oceans may spark or exacerbate resource conflicts. An initial scan of 803 relevant papers and subsequent intensive review of 31 fisheries conflict studies, focused on subnational and international conflicts, suggests that four substantial scientific gaps need addressing to improve our understanding of the nature and drivers of fisheries conflict. First, fisheries conflict and levels of conflict intensity are not precisely defined. Second, complex adaptive systems thinking is underutilized but has the potential to produce more realistic causal models of fishery conflict. Third, comparative large‐scale data and suitably integrative methodologies are lacking, underscoring the need for a standardized and comparable database of fisheries conflict cases to aid extrapolation beyond single case‐studies. Fourth, there is room for a more widespread application of higher order concepts and associated terminology. Importantly, the four gaps highlight the homogenized nature of current methodological and theoretical approaches to understanding fishery conflict, which potentially presents us with an oversimplified understanding of these conflicts. A more nuanced understanding of the complex and dynamic nature of fishery conflict and its causes is not only scientifically critical, but increasingly relevant for policymakers and practitioners in this turbulent world.  相似文献   

Electroencephalographic assessment of oral meloxicam,topical anaesthetic cream and cautery iron for mitigating acute pain in pigs (Sus scrofa) undergoing tail docking     

Nikki J. Kells  N.J. Beausoleil  M.A. Sutherland  R.M. Morrison  Craig B. Johnson 《Veterinary anaesthesia and analgesia》2017,44(5):1166-1174

Objective

To evaluate the efficacy of oral meloxicam, topical anaesthetic cream and cautery iron in mitigating acute nociceptive responses of pigs to tail docking.

Study design

A prospective, randomized, controlled experimental study.

Animals

A total of 40 healthy Large White x Landrace pigs aged 21 ± 1 days, weighing 6.1 ± 0.9 kg.

Methods

Pigs were randomly assigned to one of four treatments (n = 10 per treatment): CONTROL: docked using clippers without analgesia; MEL: docked using clippers after administration of oral meloxicam; EMLA: docked using clippers after application of topical anaesthetic cream; and CAUT: docked using a cautery iron without analgesia. Anaesthesia was induced and maintained with halothane in oxygen. Following induction, end-tidal halothane was stabilized at 0.95–1.05% and electroencephalograph (EEG) recording commenced. After 5 minutes of baseline data collection, tail docking was performed and recording continued for a further 10 minutes. The EEG summary variables median frequency (F50), 95% spectral edge frequency (F95) and total power (P_TOT) were calculated for the baseline period and for consecutive 30-second intervals following docking.

Results

Following docking, F50 increased and P_TOT decreased significantly in CONTROL and MEL pigs. EMLA pigs exhibited no change in any variable, whilst CAUT pigs exhibited a reduction in P_TOT but no change in F50. F50 was higher in control pigs than in EMLA pigs 30–60 seconds after docking (p ≤ 0.01). P_TOT was lower in CONTROL than in EMLA pigs 30–90 seconds after docking (p < 0.03) and in CAUT pigs 60 seconds after docking (p = 0.01).

Conclusions and clinical relevance

Prior application of EMLA cream abolished EEG indicators of nociception in pigs docked using clippers. Docking using a cautery iron without analgesia ameliorated EEG indicators of nociception, relative to using clippers without analgesia. Prior administration of EMLA cream or the use of cautery instead of clippers may reduce the acute pain experienced by pigs undergoing tail docking.  相似文献   

A quantitative assay for Amaranthus palmeri identification          下载免费PDF全文

Brent P Murphy  Diane E Plewa  Elizabeth Phillippi  Suzanne M Bissonnette  Patrick J Tranel 《Pest management science》2017,73(11):2221-2224

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Heritability of spotted wilt resistance in a Florida‐EP™ “113”‐derived peanut (Arachis hypogaea) population          下载免费PDF全文

Yu‐Chien Tseng  Barry L. Tillman  Salvador A. Gezan  Jianping Wang  Diane L. Rowland 《Plant Breeding》2018,137(4):614-620

Spotted wilt, caused by tomato spotted wilt virus (TSWV), is a major disease of peanut (Arachis hypogaea ) in the south‐eastern United States. Cultivar resistance is the most important factor in disease control. However, spotted wilt resistance in current cultivars still carries risk in the absence of other practices when disease is severe. In contrast, a newly developed cultivar, Florida‐EP? “113,” has demonstrated excellent resistance even when spotted wilt is severe. Information on heritability of this resistance can help breeders better utilize it in breeding. F₂‐derived populations from the cross Florida‐EP? “113”/Georgia Valencia were developed and tested in field experiments in Florida from 2012 to 2014. Disease symptoms were evaluated visually, and the frequency of TSWV infection was measured by ImmunoStrip^®. Heritability estimated from ImmunoStrip^® was higher (0.66) compared to visual ratings (0.48). Genetic correlations among evaluation methods (r _A = 0.92–0.99) and environments (r _B = 0.86–0.99) were high. These results indicate that resistance in Florida‐EP? “113” is highly heritable and that selection in a high disease risk environment is feasible without significant erosion of genetic gain.  相似文献   

Injuries and Illnesses Occurring on a Recreational Bicycle Tour: The Great Ohio Bicycle Adventure     

Thomas L. Pommering  Diane C. Manos  Bhavna Singichetti  Chelsea R. Brown  Jingzhen Yang 《The Forestry Chronicle》2017,28(4):299-306

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