bluuebunny/crossref_metadata_2025_split huggingface dataset:
The mechanics of predator–prey interactions: First principles of physics predict predator–prey size ratios
Authors: Portalier Sébastien M. J. , Fussmann Gregor F. , Loreau Michel , Cherif Mehdi 
Published: November 2018

Abstract

Robust predictions of predator–prey interactions are fundamental for the understanding of food webs, their structure, dynamics, resistance to species loss, response to invasions and ecosystem function. Most current food web models measure parameters at the food web level to predict patterns at the same level. Thus, they are sensitive to the quality of the data and may be ineffective in predicting non‐observed interactions and disturbed food webs. There is a need for mechanistic models that predict the occurrence of a predator–prey interaction based on lower levels of organization (i.e. the traits of organisms) and the properties of their environment.

Here, we present such a model that focuses on the predation act itself. We built a Newtonian, mechanical model for the processes of searching, capturing and handling of a prey item by a predator. Associated with general metabolic laws, we predict the net energy gain from predation for pairs of pelagic or flying predator species and their prey depending on their body sizes.

Predicted interactions match well with data from the most extensive predator–prey database, and overall model accuracy is greater than the allometric niche model.

Our model shows that it is possible to accurately predict the structure of food webs using only a few mechanical traits. It underlines the importance of physical constraints in structuring food webs.

A plain language summary is available for this article.
Functional responses of avian frugivores to variation in fruit resources between natural and fragmented forests
Authors: Quitián Marta , Santillán Vinicio , Bender Irene M. A. , Espinosa Carlos Iván , Homeier Jürgen , Böhning‐Gaese Katrin , Schleuning Matthias , Lena Neuschulz Eike 
Published: November 2018

Abstract

Partner choice in species interaction networks, that is, between frugivorous birds and fruiting plants, is largely determined by matching of functional traits. However, the composition of functional traits in plant communities changes along land‐use gradients. Understanding how flexible consumers react to changes in the trait composition of resources is crucial to project consequences for ecosystem functions, such as seed dispersal.

We investigated the ability of birds to consume fruits with different sets of traits in natural and fragmented tropical montane forests across an elevational gradient. We developed a novel, trait‐based approach to quantify the functional shifts of consumers between resources with different functional traits. We expected the degree of functional shifts to be associated with bird traits related to food choice, such as bill width and degree of frugivory, as well as foraging behaviour, such as wing shape and foraging stratum.

We sampled the plant–frugivore networks at three elevations and two habitat types (natural and fragmented forest) and measured the functional traits for each plant and bird species. We calculated the trait space of the plant community at each elevation and projected the interacting birds into it. Finally, we calculated the functional shift, which is the trait‐based distance between the preferred fruit resources in the two habitat types for each bird species.

We found differences in the functional trait space of the fruiting plant community between natural and fragmented forests across all elevations. Birds' observed functional shifts between habitat types at each elevation were generally larger than the shifts expected by null models. Wing shape was the most important trait related to the functional shifts across the elevational gradient, whereas bill width, degree of frugivory, foraging stratum and phylogeny were not important.

We conclude that birds with pointed wings respond flexibly to changes in the trait composition of fruit resources, probably due to the high mobility of these species. Our results emphasize that linking species interaction networks and functional trait analyses yield new insights into how consumer species respond to changes in biotic factors and can improve projections of how human impacts modify trophic interactions and associated ecosystem functions.

A plain language summary is available for this article.
Population responses of farmland bird species to agri‐environment schemes and land management options in Northeastern Scotland
Authors: Daskalova Gergana N. , Phillimore Albert B. , Bell Matthew , Maggs Hywel E. , Perkins Allan J. 
Published: November 2018

Abstract

The decline of farmland birds across Europe is a well‐documented case of biodiversity loss, and despite land stewardship supported by funding from agri‐environment schemes (AES), the negative trends have not yet been reversed.

To investigate the contribution of AES towards farmland bird conservation, we compared abundance of five farmland bird species across 13 years and 53 farms (158 farm years = AES, 72 farm years = non AES) in Northeastern Scotland (UK), a region with relatively mixed farmland.

Between 2003 and 2015, on both AES and control farms, skylark (Alauda arvensis) showed a nonsignificant decline, and tree sparrow (Passer montanus) and yellowhammer (Emberiza citrinella) nonsignificant increases, whereas reed bunting (Emberiza schoeniclus) and linnet (Carduelis cannabina) populations remained relatively stable.

We did not detect a significant association between AES and avian abundance or population trends for any of these species, but there were positive associations with some AES management options.

Possible explanations for the lack of a significant AES‐bird abundance association include poor uptake of the best AES options for farmland birds, suboptimal implementation, spill‐over effects from AES onto control farms, and the relatively good state of farmland habitats outwith AES in Northeastern Scotland.

Synthesis and applications. We documented a weak effect size of participation in agri‐environment schemes on farmland bird abundance. We therefore recommend future monitoring studies be designed after consulting a power analysis. Among different land management options, we found that species‐rich grasslands, water margins, and wetland creation enhanced breeding bird abundance, highlighting the importance of relatively undisturbed herbaceous or grassland vegetation for farmland conservation.
Combining optimization and simulation modelling to measure the cumulative impacts of prescribed fire and wildfire on vegetation species diversity
Authors: Chick Matthew P. , York Alan , Sitters Holly , Di Stefano Julian , Nitschke Craig R. 
Published: November 2018

Abstract

Growth‐stage optimization (GSO) offers a new approach to biodiversity conservation in fire‐prone regions by estimating the optimal distribution of vegetation growth stages that maximize a species diversity index. This optimal growth‐stage structure provides managers an operational goal explicitly linked to a positive conservation outcome but does not define the fire regime needed to achieve it.

We paired GSO with LANDIS II, a landscape succession and disturbance simulation model, to (a) estimate the optimal growth‐stage structure that maximized vegetation diversity in a south‐east Australian heathy woodland, (b) define the fire regime needed to achieve it, and (c) determine the cumulative effects of different fire‐regime scenarios on vegetation diversity over a 60‐year period. Scenarios included 0%, 2%, 5%, and 10% of the landscape burnt per year by prescribed fire only, or in combination with three alternative wildfire regimes. Furthermore, we investigated the differences in the optimal growth‐stage structure relating to above‐ground, soil seedbank, and total (above and soil seedbank) diversity datasets.

The growth‐stage structure that maximized total vegetation diversity comprised approximately even proportions of all stages. In contrast, separately analysed above‐ground and soil seedbank data resulted in a greater proportion of younger and older growth‐stages, respectively.

Scenarios including 5% prescribed burning per year (with and without wildfire) resulted in diversity values within 1.5% of the theoretical maximum value. Scenarios including 2% and 10% prescribed fire resulted in diversity values 8%–12% and 1.5%–5% lower than the maximum, respectively. Scenarios without prescribed fire caused diversity to fall 30%–70%. Trends across the 60 years showed that wildfire depressed diversity and subsequent prescribed fire drove recovery within 15 years. The largest threat to vegetation diversity was the absence of fire.

Synthesis and applications. Combining growth‐stage optimization and simulation modelling is a powerful way of defining a conservation‐based fire management goal and identifying the prescribed fire regime needed to achieve it. We demonstrated that vegetation diversity in heathy woodland was increased by prescribed fire, with and without the cumulative effect of wildfire, and declined sharply when fire was excluded. Our method provides a flexible platform for developing long‐term fire management strategies that seek to balance human safety and biodiversity conservation. Including both plants and animals in GSO will help land managers meet the needs of multiple taxa.
Biogeographical scenarios modulate seagrass resistance to small‐scale perturbations
Authors: Tuya Fernando , Fernández‐Torquemada Yolanda , Zarcero Jesús , del Pilar‐Ruso Yoana , Csenteri Ina , Espino Fernando , Manent Pablo , Curbelo Leticia , Antich Adriá , de la Ossa José A. , Royo Laura , Castejón Inés , Procaccini Gabriele , Terrados Jorge , Tomas Fiona 
Published: November 2018

Abstract

Seagrasses constitute a key coastal habitat world‐wide, but are exposed to multiple perturbations. Understanding elements affecting seagrass resistance to disturbances is critical for conservation. Distinct biogeographical scenarios are intrinsically linked with varying ecological and evolution backgrounds shaped across millennia.

We addressed whether the resistance (change in shoot abundances) and performance (change in leaf morphology and growth) of the seagrass Cymodocea nodosa to a local stressor, light reduction, varied across three regions (Southeast Iberia, the Balearic Sea, and the Canaries) within the temperate northern Atlantic realm. We hypothesized that distinct biogeographical scenarios, in terms of distinct ecological/environmental conditions and genetic diversity of meadows, would affect seagrass resistance and performance, with flow‐on effects on associated epifauna. The same experiments, in terms of shading intensities, timing and duration, were replicated at three seagrass meadows within each region.

Results demonstrated inter‐regional variation in the resistance and performance of C. nodosa. Under moderate and high shading, shoot abundance was abruptly decreased, relative to controls, in the Canaries with concurrent, but less accentuated, changes in leaf morphology and no changes in growth. In the other two regions, however, moderate and high shading had a negligible effect on shoot abundance, leaf morphology, and growth. Shading had no overall effect over the total abundance and assemblage structure of epifauna; these faunal attributes, however, varied between regions. Low seagrass resistance at the Canaries is linked with the peripheral distribution of the species there, favouring isolation and decreased genetic diversity.

Synthesis. Different biogeographical scenarios shape seagrass resistance to local perturbations. From a conservation perspective, if resistance differs among biogeographical scenarios, universal conservation rules for seagrasses are challenging.
Compound fire‐drought regimes promote ecosystem transitions in Mediterranean ecosystems
Authors: Batllori Enric , De Cáceres Miquel , Brotons Lluís , Ackerly David D. , Moritz Max A. , Lloret Francisco 
Published: November 2018

Abstract

Understanding ecosystem responses to compound disturbance regimes and the influence of specific sequences of events in determining ecosystem shifts remains a challenge.

We use a modelling framework for Mediterranean‐type ecosystems to assess the effects of fire–drought interactions on long‐term vegetation dynamics and to identify disturbance‐driven changes in trait composition (tree seeder vs. tree resprouter prevalence) and ecosystem state (forest vs. non‐forest).

Changes in tree seeder and the tree resprouter dominance show nonlinear, threshold‐type trends over gradients of increasing compound disturbance frequency. Vegetation composition thresholds mostly occur in a narrow range of the compound fire–drought disturbance space. Additionally, trait compositional switches and the likelihood of sudden changes in ecosystem state are promoted by fire‐drought interactions.

Distinct sequences of disturbance events cause vegetation transitions, disrupting ecosystem resilience, even under moderate recurrence of individual disturbances. An extreme drought year followed by one or two large fire events promotes shifts from resprouter‐ to seeder dominance. Contrastingly, a large crown fire followed by an extreme drought promotes changes from seeder to resprouter dominance. This disturbance sequence is also a mechanism strong enough to trigger sudden shifts in ecosystem state (from forest to non‐forest).

Synthesis. Thresholds of change in vegetation composition occur over a narrow range of the modelled gradients of compound fire‐drought recurrence, and the loss of ecosystem resilience is contingent on particular sequences of disturbance events. Overall, our findings highlight that disturbance interactions define the relative location of tipping points in ecosystem state, and that effects and feedbacks of compound disturbance regimes increase the long‐term likelihood of sudden ecosystem shifts and, therefore, uncertainty in predicting vegetation state.
Trimebutine maleate relaxes the isolated rat thoracic aorta: The role of nitric oxide and L‐type calcium channels
Authors: Kadioglu Mine , Kaya Yasar Yesim , Barut Elif Nur , Engin Seckin 
Published: November 2018

SummaryTrimebutine maleate (TMB), a widely prescribed drug for functional gastrointestinal disorders, has been reported to regulate smooth muscle contractility by modulating multiple ion channel activities in the gastrointestinal tract. However, its action on isolated aorta has not yet been reported. The aim of the present study was to evaluate in vitro vasorelaxant properties and the underlying pharmacological mechanisms of TMB in isolated rat thoracic aortic rings. Vascular activity experiments were performed on thoracic aorta isolated from Sprague‐Dawley rats in vitro, including endothelium‐intact and endothelium‐denuded aortic rings. TMB (10−10‐10−5 mol/L) induced relaxation in endothelium‐intact aortic rings precontracted by phenylephrine with a potency similar to that of carbachol. TMB‐induced relaxation was not altered by glibenclamide and atropine in endothelium‐intact aortic rings. However, L‐NAME and endothelium denudation significantly reduced but not completely reversed the vasorelaxant effect of TMB. Also, TMB‐induced relaxation wasn't affected by diclofenac in endothelium‐intact aortic rings. TMB at 10−5 mol/L significantly reduced the CaCl2‐induced contractions in endothelium‐intact aortic rings stimulated with KCl, but not stimulated with phenylephrine under Ca2+free conditions. Moreover, TMB at 10−5 mol/L effectively attenuated Bay‐K8644‐induced contractions in aortic rings. These results suggest that TMB‐induced relaxation was mediated by both endothelium‐dependent and endothelium‐independent manner in isolated rat thoracic aorta. The mechanism of TMB‐induced relaxation at low concentrations is partially related to NO‐ and endothelium‐dependent but unrelated to prostanoids formation. However, inhibition of Ca2+ influx through voltage‐operated calcium channels and L‐type Ca2+channel blocking effect appears to be involved in the mechanism of vasorelaxant effect of TMB at high concentrations.
First‐dose effect of the SGLT2 inhibitor ipragliflozin on cardiovascular activity in spontaneously diabetic Torii fatty rats
Authors: Takakura Shoji , Takasu Toshiyuki 
Published: November 2018

SummaryThe first dose of a sodium‐dependent glucose cotransporter 2 (SGLT2) inhibitor induces osmotic diuresis and can thereby affect cardiovascular activity in hyperglycemic patients. We aimed to determine whether the first dose of the selective SGLT2 inhibitor ipragliflozin affects cardiovascular activity in non‐diabetic Sprague‐Dawley (SD) rats and Spontaneously Diabetic Torii (SDT) fatty rats in two studies, a urine collection study and a telemetry study. In the former study, urine was collected for 24 hours after a single oral dose of ipragliflozin. In the latter study, systolic blood pressure (SBP) and heart rate (HR) were continuously monitored for 24 hours under conscious and unrestrained conditions from immediately before the administration of ipragliflozin. The telemetry study was conducted in a crossover design at successive 1 week intervals. Cardiovascular autonomic nerve activity was calculated from the SBP and HR. SDT fatty rats exhibited polyuria, glucosuria and hyperglycemia. In addition, the mean and standard deviation of SBP were higher, while the coefficient of variance of HR was lower than the respective parameters in SD rats. Ipragliflozin increased both urine output and urinary glucose excretion, and the increases were more pronounced in SDT fatty rats than in SD rats. In contrast, ipragliflozin had no effect on SBP, the standard deviation of SBP, HR, and the coefficient of variance of HR, or on autonomic nerve activity in either rat strain. These results suggest that the first dose of the SGLT2 inhibitor ipragliflozin has little impact on cardiovascular activity despite causing glucosuria with osmotic diuresis.
Chemically mediated interactions between Microcystis and Planktothrix: impact on their growth, morphology and metabolic profiles
Authors: Briand Enora , Reubrecht Sébastien , Mondeguer Florence , Sibat Manoëlla , Hess Philipp , Amzil Zouher , Bormans Myriam 
Published: November 2018

SummaryFreshwater cyanobacteria are known for their ability to produce bioactive compounds, some of which have been described as allelochemicals. Using a combined approach of co‐cultures and analyses of metabolic profiles, we investigated chemically mediated interactions between two cyanobacterial strains, Microcystis aeruginosa PCC 7806 and Planktothrix agardhii PCC 7805. More precisely, we evaluated changes in growth, morphology and metabolite production and release by both interacting species. Co‐culture of Microcystis with Planktothrix resulted in a reduction of the growth of Planktothrix together with a decrease of its trichome size and alterations in the morphology of its cells. The production of intracellular compounds by Planktothrix showed a slight decrease between monoculture and co‐culture conditions. Concerning Microcystis, the number of intracellular compounds was higher under co‐culture condition than under monoculture. Overall, Microcystis produced a lower number of intracellular compounds under monoculture than Planktothrix, and a higher number of intracellular compounds than Planktothrix under co‐culture condition. Our investigation did not allow us to identify specifically the compounds causing the observed physiological and morphological changes of Planktothrix cells. However, altogether, these results suggest that co‐culture induces specific compounds as a response by Microcystis to the presence of Planktothrix. Further studies should be undertaken for identification of such potential allelochemicals.
Improved protein production and codon optimization analyses in Escherichia coli by bicistronic design
Authors: Nieuwkoop Thijs , Claassens Nico J. , van der Oost John 
Published: November 2018

SummaryDifferent codon optimization algorithms are available that aim at improving protein production by optimizing translation elongation. In these algorithms, it is generally not considered how the altered protein coding sequence will affect the secondary structure of the corresponding RNA transcript, particularly not the effect on the 5′‐UTR structure and related ribosome binding site availability. This is a serious drawback, because the influence of codon usage on mRNA secondary structures, especially near the start of a gene, may strongly influence translation initiation. In this study, we aim to reduce the effect of codon usage on translation initiation by applying a bicistronic design (BCD) element. Protein production of several codon‐optimized gene variants is tested in parallel for a BCD and a standard monocistronic design (MCD). We demonstrate that these distinct architectures can drastically change the relative performance of different codon optimization algorithms. We conclude that a BCD is indispensable in future studies that aim to reveal the impact of codon optimization and codon usage correlations. Furthermore, irrespective of the algorithm used, using a BCD does improve protein production compared with an MCD. The overall highest expression from BCDs for both GFP and RFP is at least twofold higher than the highest levels found for the MCDs, while for codon variants having very low expression from the MCD, even 10‐fold to 100‐fold increases in expression were achieved by the BCD. This shows the great potential of the BCD element for recombinant protein production.
Characteristics of gout patients according to the laterality of nephrolithiasis: A cross‐sectional study using helical computed tomography
Authors: Shimizu Toru , Hori Hiroshi , Umeyama Masanori , Shimizu Kentaro 
Published: November 2018

AbstractObjectiveTo clarify the clinical and laboratory characteristics of nephrolithiasis in gout by computed tomography (CT).MethodsIn 350 gout patients, unenhanced CT was performed at the 1st visit to hospital. Calculus density spots exceeding 1 mm in diameter with a CT value >120 Hounsfield units in the kidneys were defined as kidney stones. The association between laterality and the number of stones was investigated in each stone carrier. The 350 patients were classified into three groups (bilateral, unilateral and non‐stone carriers). Then serum urate (Sua), renal function, uric acid metabolism, and the prevalence of metabolic syndrome (Mets) were compared among these groups by the Tukey‐Kramer test or Fisher's exact test.ResultsKidney stone(s) were detected in 108 (31%) of the 350 patients (bilateral in 58 and unilateral in 50). In 64 of the 108 patients (59%), there was no history of urolithiasis. Sua, serum creatinine and uric acid clearance were significantly higher (P = 0.001, P < 0.001, P = 0.043, respectively), while the estimated glomerular filtration rate was significantly lower (P = 0.039) in bilateral stone carriers than in non‐stone carriers. No significant differences of uric acid metabolism or the prevalence of Mets were noted among the three groups.ConclusionsApproximately one‐third of gout patients had kidney stones and more than half of the patients with stones were bilateral and multiple stone carriers. Elevation of Sua might increase the stone burden in gout, leading to more severe renal dysfunction. An association between nephrolithiasis and Mets was not demonstrated in gout patients.