bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seed harvesting is influenced by associational effects in mixed seed neighbourhoods, not just by seed density
Authors: Ostoja Steven M. , Schupp Eugene W. , Durham Susan , Klinger Rob 
Published: April 2013

Summary

Rodents frequently forage in a density‐dependent manner, increasing harvesting in patches with greater seed densities. Although seldom considered, seed harvesting may also depend on the species identities of other individuals in the seed neighbourhood. When the seed harvest of a focal species increases in association with another seed species, the focal species suffers from Associational Susceptibility. In contrast, if seeds of the focal species are harvested less when in association with a second species, the focal species benefits from Associational Resistance.

To evaluate density dependence and associational effects among seeds in mixtures, we conducted seed removal experiments using a completely additive design patterned after a two‐species competition experiment using seeds of either Achnatherum hymenoides (Indian ricegrass), Leymus cinereus (basin wildrye) or Pseudoroegneria spicata (bluebunch wheatgrass), all native perennial grasses, combined with seeds of Bromus tectorum (cheatgrass), a non‐native annual grass. The experiment involved placing five fixed quantities of the native seeds mixed with five fixed quantities of B. tectorum seeds in a factorial design, resulting in 35 seed mixture combinations. The seed‐eating rodent community at our study sites, in order of abundance, is composed of Peromyscus maniculatus (North American deer mouse), Dipodomys ordii (Ord's kangaroo rat) and Perognathus parvus (Great Basin pocket mouse).

Native seed harvesting was density dependent, with a greater proportion of seeds being harvested as density increased. In the mixed density model, the presence of B. tectorum did not affect harvest of any of the native species' seeds when analysed individually. However, when all three native species were analysed together, increasing quantities of B. tectorum resulted in reduced harvest of native seeds, demonstrating weak but significant Associational Resistance. In contrast, harvest of B. tectorum seeds increased when in combination with any of the native seed species individually, indicating relatively strong Associational Susceptibility.

These results demonstrate that seed harvest is determined not just by seed density, but also by the local seed neighbourhood and suggest that associational effects between native seeds and B. tectorum can occur in field conditions. The ecological implications of seed selection and associational effects on plant populations in natural and managed systems are also discussed.
Trophic complexity enhances ecosystem functioning in an aquatic detritus‐based model system
Authors: Jabiol Jérémy , McKie Brendan G. , Bruder Andreas , Bernadet Caroline , Gessner Mark O. , Chauvet Eric 
Published: April 2013

Summary

Understanding the functional significance of species interactions in ecosystems has become a major challenge as biodiversity declines rapidly worldwide. Ecosystem consequences arising from the loss of diversity either within trophic levels (horizontal diversity) or across trophic levels (vertical diversity) are well documented. However, simultaneous losses of species at different trophic levels may also result in interactive effects, with potentially complex outcomes for ecosystem functioning.

Because of logistical constraints, the outcomes of such interactions have been difficult to assess in experiments involving large metazoan species. Here, we take advantage of a detritus–based model system to experimentally assess the consequences of biodiversity change within both horizontal and vertical food‐web components on leaf‐litter decomposition, a fundamental process in a wide range of ecosystems.

Our concurrent manipulation of fungal decomposer diversity (0, 1 or 5 species), detritivore diversity (0, 1 or 3 species), and the presence of predatory fish scent showed that trophic complexity is key to eliciting diversity effects on ecosystem functioning. Specifically, although fungi and detritivores tended to promote decomposition individually, rates were highest in the most complete community where all trophic levels were represented at the highest possible species richness. In part, the effects were trait‐mediated, reflected in the contrasting foraging responses of the detritivore species to predator scent.

Our results thus highlight the importance of interactive effects of simultaneous species loss within multiple trophic levels on ecosystem functioning. If a common phenomenon, this outcome suggests that functional ecosystem impairment resulting from widespread biodiversity loss could be more severe than inferred from previous experiments confined to varying diversity within single trophic levels.
Reconciling resource utilization and resource selection functions
Authors: Hooten Mevin B. , Hanks Ephraim M. , Johnson Devin S. , Alldredge Mat W. 
Published: April 2013

Summary

Analyses based on utilization distributions (UDs) have been ubiquitous in animal space use studies, largely because they are computationally straightforward and relatively easy to employ. Conventional applications of resource utilization functions (RUFs) suggest that estimates of UDs can be used as response variables in a regression involving spatial covariates of interest.

It has been claimed that contemporary implementations of RUFs can yield inference about resource selection, although to our knowledge, an explicit connection has not been described.

We explore the relationships between RUFs and resource selection functions from a hueristic and simulation perspective. We investigate several sources of potential bias in the estimation of resource selection coefficients using RUFs (e.g. the spatial covariance modelling that is often used in RUF analyses).

Our findings illustrate that RUFs can, in fact, serve as approximations to RSFs and are capable of providing inference about resource selection, but only with some modification and under specific circumstances.

Using real telemetry data as an example, we provide guidance on which methods for estimating resource selection may be more appropriate and in which situations. In general, if telemetry data are assumed to arise as a point process, then RSF methods may be preferable to RUFs; however, modified RUFs may provide less biased parameter estimates when the data are subject to location error.
Antimicrobial use in aquaculture re‐examined: its relevance to antimicrobial resistance and to animal and human health
Authors: Cabello Felipe C. , Godfrey Henry P. , Tomova Alexandra , Ivanova Larisa , Dölz Humberto , Millanao Ana , Buschmann Alejandro H. 
Published: April 2013

SummaryThe worldwide growth of aquaculture has been accompanied by a rapid increase in therapeutic and prophylactic usage of antimicrobials including those important in human therapeutics. Approximately 80% of antimicrobials used in aquaculture enter the environment with their activity intact where they select for bacteria whose resistance arises from mutations or more importantly, from mobile genetic elements containing multiple resistance determinants transmissible to other bacteria. Such selection alters biodiversity in aquatic environments and the normal flora of fish and shellfish. The commonality of the mobilome (the total of all mobile genetic elements in a genome) between aquatic and terrestrial bacteria together with the presence of residual antimicrobials, biofilms, and high concentrations of bacteriophages where the aquatic environment may also be contaminated with pathogens of human and animal origin can stimulate exchange of genetic information between aquatic and terrestrial bacteria. Several recently found genetic elements and resistance determinants for quinolones, tetracyclines, and β‐lactamases are shared between aquatic bacteria, fish pathogens, and human pathogens, and appear to have originated in aquatic bacteria. Excessive use of antimicrobials in aquaculture can thus potentially negatively impact animal and human health as well as the aquatic environment and should be better assessed and regulated.
In situ activity of a dominant Prochlorococcus ecotype (eHL‐II) from rRNA content and cell size
Authors: Lin Yajuan , Gazsi Katrina , Lance Veronica P. , Larkin Alyse A. , Chandler Jeremy W. , Zinser Erik R. , Johnson Zackary I. 
Published: April 2013

SummaryIn the open ocean genetically diverse clades of the unicellular cyanobacteria Prochlorococcus are biogeographically structured along environmental gradients, yet little is known about their in situ activity. To address this gap, here we use the numerically dominant Prochlorococcus clade eHL‐II (eMIT9312) as a model organism to develop and apply a method to examine their in situ activity using rRNA content and cell size as metrics of cellular physiology. For two representative isolates (MIT9312 and MIT9215) rRNA cell−1 increases linearly with specific growth rate but is anticorrelated with cell size indicated by flow cytometrically measured (SSC). Although each strain has a unique relationship between cellular rRNA (or cell size) and growth rate, both strains have the same strong positive correlation between rRNA cell−1 SSC−1 and growth rate. We field test this approach and observe distinct patterns of eHL‐II clade specific activity (rRNA cell−1 SSC−1) with depth that are consistent with patterns of photosynthetic rates. This molecular technique provides unique insight into the ecology of Prochlorococcus and could potentially be expanded to include other microbes to unravel the ecological and biogeochemical contributions of genetically distinct marine side scatter microbes.
A DUAL‐SYSTEMS APPROACH FOR UNDERSTANDING DIFFERENTIAL SUSCEPTIBILITY TO PROCESSES OF PEER INFLUENCE
Authors: THOMAS KYLE J. , MARIE MCGLOIN JEAN 
Published: April 2013

The distinct peer‐based perspectives of deviant normative influence and unstructured/unsupervised socializing with friends contend that adolescents rely on different information when deciding to offend, with the former positing that individuals offend after considering the longer term consequences of behavior, and the latter positing that decisions to offend derive from situational stimuli. We argue that these processes can be organized under a dual‐systems framework of decision making, which leads to the hypothesis that individuals at the edges of impulsivity should be differentially vulnerable to these peer influence processes because of their tendency to rely on only one system of decision making. We use two large data sets to test this hypothesis: a nationally representative sample of adolescents from the AddHealth study (N = ∼9,000) and a pooled panel data set of adolescents from the Gang Resistance Education and Training (G.R.E.A.T.) evaluation (N = 1,172). The results of longitudinal negative binomial analyses indicate that normative influence by deviant peers has a stronger effect on delinquency for adolescents with low impulsivity than it does for individuals with high impulsivity. Differences in the informal socializing with peers coefficients are less clear and offer minimal support for our predictions.
Inulin and Erythritol As Sucrose Replacers in Short‐dough Cookies: Sensory, Fracture, and Acoustic Properties
Authors: Laguna Laura , Primo‐Martín Cristina , Salvador Ana , Sanz Teresa 
Published: April 2013

Abstract The effect of sucrose replacement by erythritol and inulin was studied in short‐dough cookies using instrumental and sensory analysis. Two levels of replacement were used (25% and 50% of total sucrose content). Descriptive sensory analysis showed that the sucrose replacement affects visual and texture cookies characteristics, being the differences perceived by mouth greater than by hand. In general, sucrose substitutes produced a less crispy cookie and lower consumer acceptability, with the exception of 25% sucrose replacement by inulin. Matrix aeration attributes such as open and crumbly obtained by trained panel were important properties, and correlated positively with consumer acceptance and negatively with maximum force at break (hardness). Inulin cookies sensory properties were more similar to the control than the erythritol cookies. Also, consumer overall acceptance decreased significantly with sucrose replacement by erythritol. The analysis of texture and sound revealed that inulin cookies were softer whereas erythritol cookies were harder in comparison with control cookies; despite this difference, inulin cookies had similar sound characteristics to erythritol cookies.Practical Application Erythritol and inulin were evaluated as partial sucrose replacer in cookies. Changes in sensory and instrumental data were observed but a replacement of 25% sucrose was achieved without having a detrimental effect on consumer perception.
Impaired liver regeneration by β‐glucosylceramide is associated with decreased fat accumulation
Authors: Ben Ya'acov Ami , Lalazar Gadi , Zolotaryova Lydia , Steinhardt Yair , Lichtentein Yoav , Ilan Yaron , Shteyer Eyal 
Published: April 2013

ObjectiveTo investigate the effect of β‐glucosylceramide (GC), a natural glycolipid, on hepatic fat accumulation and regenerative response after partial hepatectomy (PH).MethodsMale C57Bl/6 mice were assigned to either 70% PH or sham surgery after receiving daily intraperitoneal injection of GC or vehicle for 3 days. Hepatic fat accumulation, cytokines, cell cycle proteins and adipogenic genes expression were assessed at various time points after PH.ResultsThe administration of GC delayed hepatic triglyceride accumulation during hepatic regeneration. This observation was closely correlated with alterations in the expression of four major adipogenic genes during the course of liver regeneration, with reduced expression 3 h after PH and increased expression 48 h post‐surgery. GC significantly reduced hepatocellular proliferation 48 h after PH. In GC‐treated mice, both tumor necrosis factor‐α and interleukin‐6 levels were lower 3, 48 and 72 h after PH compared with the control group.ConclusionsAdministration of GC delayed hepatic triglyceride accumulation and suppressed early adipogenic gene expression during the hepatic regenerative response. These changes are closely associated with early inhibition of liver regeneration and temporal alteration of cytokine secretion.
Role of NF‐κβ and Oxidative Pathways in Atherosclerosis: Cross‐Talk Between Dyslipidemia and Candesartan
Authors: Hadi Najah R. , Yousif Nasser Ghaly , Abdulzahra Mohammed S. , Mohammad Bassim I. , al‐amran Fadhil G. , Majeed Murooge L. , Yousif Maitham G. 
Published: April 2013

SummaryPurposeThe objective of this study is to assess the effect of the candesartan on the progression of atherosclerosis through the downregulation of NF‐κβ and interference with oxidative pathway.MethodsTwenty‐four rabbits were assigned to three groups: control group fed normal diet; induced untreated group fed 1% cholesterol diet; and treated candesartan group also fed 1% cholesterol diet. Plasma lipid profiles were measured, and ELISA for plasma cytokines and chemokine was performed. Analyses of NF‐κβ and VCAM‐1 were performed using Western blotting with RT‐PCR for NF‐κB activity at mRNA. Doppler ultrasound was used to evaluate aortic intima‐media thickness, and atheroma was detected by H&E staining. Immunofluorescent staining was performed to confirm accumulation of monocytes and PMNs.ResultsCandesartan markedly reduced the levels of the plasma lipid profile including total cholesterol [TC], triglycerides [TG], and LDL‐C, while significantly elevating levels in the plasma HDL‐C, in addition to reducing cytokine (TNF‐α, IL‐6, IL‐1β) and chemokine levels (MCP‐1). Also, it decreased the aortic malondialdehyde (MDA) concentration and elevated the aortic glutathione (GSH) level compared with untreated animals (P < 0.05). The triplex Doppler ultrasound study confirmed that the candesartan attenuated intima‐media thickness at 6 months of study. All candesartan‐treated rabbits showed significantly attenuated atherosclerosis lesions with reduced accumulation of monocytes and had significantly reduced VCAM‐1 expression and NF‐κβ activity.ConclusionCandesartan retards the progression of atherosclerosis via interference with NF‐κβ and oxidative pathways.
Congruence between mcy based genetic type and microcystin composition within the populations of toxic Microcystis in a plateau lake, China
Authors: Jiang Yongguang , Yu Gongliang , Chai Wenbo , Song Gaofei , Li Renhui 
Published: April 2013

SummaryGenetic diversity and differential microcystin contributions within the populations of toxic Microcystis in freshwater ecosystems have not been fully discussed. To illustrate this issue, we sequenced clone libraries of the first adenylation domain of mcyB (mcyBA1) from Microcystis populations in a plateau lake. Phylogenetic analysis revealed two divergent groups of McyBA1 with two closely related subgroups within Group I. While neutral evolution was indicated on the whole McyBA1 domain, 1–5 recombination breakpoints and several codons under positive or negative selections were found. Significant seasonal changes of McyBA1 diversity were observed. Group I composed the major proportion of the McyBA1 pool throughout the growing season in the whole lake. Group IA and Group II denominated Microcystis strains isolated from this lake were characterized by preference production of microcystin‐RR (62–85%) and microcystin‐LR (> 98%) respectively. We detected the intracellular microcystins in lake water and microcystin‐RR was a main variant (mostly > 50%). In summary, McyBA1 subgroups were dominant within the population of toxic Microcystis and contributed the predominance of microcystin‐RR in the lake. The differences of substrate preference in microcystin biosynthesis among groups were caused by neutral evolution and homologous recombination.
Microbial community composition and endolith colonization at an Arctic thermal spring are driven by calcite precipitation
Authors: Starke Verena , Kirshtein Julie , Fogel Marilyn L. , Steele Andrew 
Published: April 2013

SummaryEnvironmental conditions shape community composition. Arctic thermal springs provide an opportunity to study how environmental gradients can impose strong selective pressures on microbial communities and provide a continuum of niche opportunities. We use microscopic and molecular methods to conduct a survey of microbial community composition at Troll Springs on Svalbard, Norway, in the high Arctic. Microorganisms there exist under a wide range of environmental conditions: in warm water as periphyton, in moist granular materials, and in cold, dry rock as endoliths. Troll Springs has two distinct ecosystems, aquatic and terrestrial, together in close proximity, with different underlying environmental factors shaping each microbial community. Periphyton are entrapped during precipitation of calcium carbonate from the spring's waters, providing microbial populations that serve as precursors for the development of endolithic communities. This process differs from most endolith colonization, in which the rock predates the communities that colonize it. Community composition is modulated as environmental conditions change within the springs. At Troll, the aquatic environments show a small number of dominant operational taxonomic units (OTUs) that are specific to each sample. The terrestrial environments show a more even distribution of OTUs common to multiple samples.
Low hydrogen peroxide production in mitochondria of the long‐lived Arctica islandica: underlying mechanisms for slow aging
Authors: Munro Daniel , Pichaud Nicolas , Paquin Frédérique , Kemeid Vincent , Blier Pierre U. 
Published: April 2013

SummaryThe observation of an inverse relationship between lifespan and mitochondrial H2O2 production rate would represent strong evidence for the disputed oxidative stress theory of aging. Studies on this subject using invertebrates are surprisingly lacking, despite their significance in both taxonomic richness and biomass. Bivalve mollusks represent an interesting taxonomic group to challenge this relationship. They are exposed to environmental constraints such as microbial H2S, anoxia/reoxygenation, and temperature variations known to elicit oxidative stress. Their mitochondrial electron transport system is also connected to an alternative oxidase that might improve their ability to modulate reactive oxygen species (ROS) yield. Here, we compared H2O2 production rates in isolated mantle mitochondria between the longest‐living metazoan—the bivalve Arctica islandica—and two taxonomically related species of comparable size. In an attempt to test mechanisms previously proposed to account for a reduction of ROS production in long‐lived species, we compared oxygen consumption of isolated mitochondria and enzymatic activity of different complexes of the electron transport system in the two species with the greatest difference in longevity. We found that A. islandica mitochondria produced significantly less H2O2 than those of the two short‐lived species in nearly all conditions of mitochondrial respiration tested, including forward, reverse, and convergent electron flow. Alternative oxidase activity does not seem to explain these differences. However, our data suggest that reduced complex I and III activity can contribute to the lower ROS production of A. islandica mitochondria, in accordance with previous studies. We further propose that a lower complex II activity could also be involved.
Periorbital allergic contact dermatitis resulting from topical retinoic acid use
Authors: Anderson Austen , Gebauer Kurt 
Published: April 2013

AbstractContact dermatitis to topical tretinoin or retinoic acid is rarely described. We outline the case of a 20‐year‐old woman presenting with bilateral periorbital dermatitis against the background of longstanding use of retinoic acid for the ocular complications of toxic epidermal necrolysis. Patch testing confirmed a contact allergy to retinoic acid and the symptoms of the dermatitis resolved after the cessation of retinoic acid.
Decellularized Porcine Saphenous Artery for Small‐Diameter Tissue‐Engineered Conduit Graft
Authors: Xiong Yun , Chan Wing Yue , Chua Alvin W.C. , Feng Jiajun , Gopal Pamela , Ong Yee Siang , Song Colin 
Published: April 2013

AbstractDecellularized xenografts have been identified as potential scaffolds for small‐diameter vascular substitutes. This study aimed to develop and investigate a biomechanically functional and biocompatible acellular conduit using decellularized porcine saphenous arteries (DPSAs), through a modified decellularization process using Triton X‐100/NH4OH solution and serum‐containing medium. Histological and biochemical analysis indicated a high degree of cellular removal and preservation of the extracellular matrix. Bursting pressure tests showed that the DPSAs could withstand a pressure of 1854 ± 164 mm Hg. Assessment of in vitro cell adhesion and biocompatibility showed that porcine pulmonary artery endothelial cells were able to adhere and proliferate on DPSAs in static and rotational culture. After interposition into rabbit carotid arteries in vivo, DPSAs showed patency rates of 60% at 1 month and 50% at 3 months. No aneurysm and intimal hyperplasia were observed in any DPSAs. All patent grafts showed regeneration of vascular elements, and thrombotic occlusion was found to be the main cause of graft failure, probably due to remaining xenoantigens. In conclusion, this study showed the development and evaluation of a decellularization process with the potential to be used as small‐diameter grafts.