837 research outputs found
Mass-flowering crops have a greater impact than semi-natural habitat on crop pollinators and pollen deposition
This is the final version. Available from Springer via the DOI in this record. Datasets available in the NERC Environmental Information Data Centre repository https://doi.org/10.5285/6128a4f7-d2ac-43c5-b492-af4c654e89b8.Context: Maximising insect pollination of mass-flowering crops is a widely-discussed approach to sustainable agriculture. Management actions can target landscape-scale semi-natural habitat, cropping patterns or field-scale features, but little is known about their relative effectiveness. Objective: To test how landscape composition (area of mass-flowering crops and semi-natural habitat) and field-scale habitat (margins and hedges) affect pollinator species richness, abundance, and pollen deposition within crop fields. Methods: We surveyed all flower visitors (Diptera, Coleoptera and Hymenoptera) in oilseed rape fields and related them to landscape composition and field features. Flower visitors were classified as bees, non-bee pollinators and brassica specialists. Total pollen deposition by individual taxa was estimated using single visit pollen deposition on stigmas combined with insect abundance. Results: The area of mass-flowering crop had a negative effect on the species richness and abundance of bees in fields, but not other flower visitors. The area of semi-natural habitat in the surrounding landscape had a positive effect on bees, but was not as important as the area of mass-flowering crop. Taxonomic richness and abundance varied significantly between years for non-bee pollinators. Greater cover of mass-flowering crops surrounding fields had a negative effect on pollen deposition, but only when non-bee pollinator numbers were reduced. Conclusions: Management choices that result in landscape homogenisation, such as large areas of mass-flowering crops, may reduce pollination services by reducing the numbers of bees visiting fields. Non-bee insect pollinators may buffer these landscape effects on pollen deposition, and management to support their populations should be considered.Natural Environment Research Counci
IFNβ Protects Neurons from Damage in a Murine Model of HIV-1 Associated Brain Injury.
Infection with human immunodeficiency virus-1 (HIV-1) causes brain injury. Type I interferons (IFNα/β) are critical mediators of any anti-viral immune response and IFNβ has been implicated in the temporary control of lentiviral infection in the brain. Here we show that transgenic mice expressing HIV-1 envelope glycoprotein 120 in their central nervous system (HIVgp120tg) mount a transient IFNβ response and provide evidence that IFNβ confers neuronal protection against HIVgp120 toxicity. In cerebrocortical cell cultures, neuroprotection by IFNβ against gp120 toxicity is dependent on IFNα receptor 1 (IFNAR1) and the β-chemokine CCL4, as IFNAR1 deficiency and neutralizing antibodies against CCL4, respectively, abolish the neuroprotective effects. We find in vivo that IFNβ mRNA is significantly increased in HIVgp120tg brains at 1.5, but not 3 or 6 months of age. However, a four-week intranasal IFNβ treatment of HIVgp120tg mice starting at 3.5 months of age increases expression of CCL4 and concomitantly protects neuronal dendrites and pre-synaptic terminals in cortex and hippocampus from gp120-induced damage. Moreover, in vivo and in vitro data suggests astrocytes are a major source of IFNβ-induced CCL4. Altogether, our results suggest exogenous IFNβ as a neuroprotective factor that has potential to ameliorate in vivo HIVgp120-induced brain injury
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The use of phylogeny to interpret cross-cultural patterns in plant use and guide medicinal plant discovery: an example from Pterocarpus (Leguminosae)
The study of traditional knowledge of medicinal plants has led to discoveries that have helped combat diseases and improve healthcare. However, the development of quantitative measures that can assist our quest for new medicinal plants has not greatly advanced in recent years. Phylogenetic tools have entered many scientific fields in the last two decades to provide explanatory power, but have been overlooked in ethnomedicinal studies. Several studies show that medicinal properties are not randomly distributed in plant phylogenies, suggesting that phylogeny shapes ethnobotanical use. Nevertheless, empirical studies that explicitly combine ethnobotanical and phylogenetic information are scarce.In this study, we borrowed tools from community ecology phylogenetics to quantify significance of phylogenetic signal in medicinal properties in plants and identify nodes on phylogenies with high bioscreening potential. To do this, we produced an ethnomedicinal review from extensive literature research and a multi-locus phylogenetic hypothesis for the pantropical genus Pterocarpus (Leguminosae: Papilionoideae). We demonstrate that species used to treat a certain conditions, such as malaria, are significantly phylogenetically clumped and we highlight nodes in the phylogeny that are significantly overabundant in species used to treat certain conditions. These cross-cultural patterns in ethnomedicinal usage in Pterocarpus are interpreted in the light of phylogenetic relationships.This study provides techniques that enable the application of phylogenies in bioscreening, but also sheds light on the processes that shape cross-cultural ethnomedicinal patterns. This community phylogenetic approach demonstrates that similar ethnobotanical uses can arise in parallel in different areas where related plants are available. With a vast amount of ethnomedicinal and phylogenetic information available, we predict that this field, after further refinement of the techniques, will expand into similar research areas, such as pest management or the search for bioactive plant-based compounds
Multiple ITS Copies Reveal Extensive Hybridization within Rheum (Polygonaceae), a Genus That Has Undergone Rapid Radiation
During adaptive radiation events, characters can arise multiple times due to parallel evolution, but transfer of traits through hybridization provides an alternative explanation for the same character appearing in apparently non-sister lineages. The signature of hybridization can be detected in incongruence between phylogenies derived from different markers, or from the presence of two divergent versions of a nuclear marker such as ITS within one individual.In this study, we cloned and sequenced ITS regions for 30 species of the genus Rheum, and compared them with a cpDNA phylogeny. Seven species contained two divergent copies of ITS that resolved in different clades from one another in each case, indicating hybridization events too recent for concerted evolution to have homogenised the ITS sequences. Hybridization was also indicated in at least two further species via incongruence in their position between ITS and cpDNA phylogenies. None of the ITS sequences present in these nine species matched those detected in any other species, which provides tentative evidence against recent introgression as an explanation. Rheum globulosum, previously indicated by cpDNA to represent an independent origin of decumbent habit, is indicated by ITS to be part of clade of decumbent species, which acquired cpDNA of another clade via hybridization. However decumbent and glasshouse morphology are confirmed to have arisen three and two times, respectively.These findings suggested that hybridization among QTP species of Rheum has been extensive, and that a role of hybridization in diversification of Rheum requires investigation
Evolutionary factors affecting Lactate dehydrogenase A and B variation in the Daphnia pulex species complex
Background: Evidence for historical, demographic and selective factors affecting enzyme evolution can be
obtained by examining nucleotide sequence variation in candidate genes such as Lactate dehydrogenase (Ldh). Two
closely related Daphnia species can be distinguished by their electrophoretic Ldh genotype and habitat. Daphnia
pulex populations are fixed for the S allele and inhabit temporary ponds, while D. pulicaria populations are fixed for
the F allele and inhabit large stratified lakes. One locus is detected in most allozyme surveys, but genome
sequencing has revealed two genes, LdhA and LdhB.
Results: We sequenced both Ldh genes from 70 isolates of these two species from North America to determine if
the association between Ldh genotype and habitat shows evidence for selection, and to elucidate the evolutionary
history of the two genes. We found that alleles in the pond-dwelling D. pulex and in the lake-dwelling D. pulicaria
form distinct groups at both loci, and the substitution of Glutamine (S) for Glutamic acid (F) at amino acid 229
likely causes the electrophoretic mobility shift in the LDHA protein. Nucleotide diversity in both Ldh genes is much
lower in D. pulicaria than in D. pulex. Moreover, the lack of spatial structuring of the variation in both genes over a
wide geographic area is consistent with a recent demographic expansion of lake populations. Neutrality tests
indicate that both genes are under purifying selection, but the intensity is much stronger on LdhA.
Conclusions: Although lake-dwelling D. pulicaria hybridizes with the other lineages in the pulex species complex,
it remains distinct ecologically and genetically. This ecological divergence, coupled with the intensity of purifying
selection on LdhA and the strong association between its genotype and habitat, suggests that experimental
studies would be useful to determine if variation in molecular function provides evidence that LDHA variants are
adaptive
Production of electrospun fast-dissolving drug delivery systems with therapeutic eutectic systems encapsulated in gelatin
Fast-dissolving delivery systems (FDDS) have received increasing attention in
the last years. Oral drug delivery is still the preferred route for the administration of
pharmaceutical ingredients. Nevertheless, some patients, e.g. children or elderly people, have
difficulties in swallowing solid tablets. In this work, gelatin membranes were produced by
electrospinning, containing an encapsulated therapeutic deep-eutectic solvent (THEDES)
composed by choline chloride/mandelic acid, in a 1:2 molar ratio. A gelatin solution (30% w/
v) with 2% (v/v) of THEDES was used to produce electrospun fibers and the experimental
parameters were optimized. Due to the high surface area of polymer fibers, this type of
construct has wide applicability. With no cytotoxicity effect, and showing a fast-dissolving
release profile in PBS, the gelatin fibers with encapsulated THEDES seem to have promising
applications in the development of new drug delivery systems.The research leading to these results has received
funding from Fundação para a Ciência e a Tecnologia
(FCT) through the projects ENIGMA - PTDC/EQU-EPR/
121491/2010 and UID/CTM/50025/2013, LAQVREQUIMTE:
UID/QUI/50006/2013, UCIBIO-REQUIMTE:
UID/Multi/04378/2013 (co-financed by the ERDF under the
PT2020 Partnership Agreement [POCI-01-0145-FEDER-
007728]) and by FEDER through the COMPETE 2020
Programme. Marta Martins is grateful for financial support
from FCT through the grant BIM/PTDC/EQUEPR/121491/
2010/ENIGMA. This research has also received funding from
the European Union Seventh Framework Programme (FP7/
2007-2013) under grant agreement number REGPOTCT2012-316331-POLARIS and from the project BNovel
smart and biomimetic materials for innovative regenerative medicine approaches^ RL1 - ABMR - NORTE-01-0124- FEDER-000016) co-financed by North Portugal Regional
Operational Programme (ON.2 – O Novo Norte), under the
National Strategic Reference Framework (NSRF), through
the European Regional Development Fund (ERDF).info:eu-repo/semantics/publishedVersio
Transition from Persistent to Anti-Persistent Correlations in Postural Sway Indicates Velocity-Based Control
The displacement of the center-of-pressure (COP) during quiet stance has often been accounted for by the control of COP position dynamics. In this paper, we discuss the conclusions drawn from previous analyses of COP dynamics using fractal-related methods. On the basis of some methodological clarification and the analysis of experimental data using stabilogram diffusion analysis, detrended fluctuation analysis, and an improved version of spectral analysis, we show that COP velocity is typically bounded between upper and lower limits. We argue that the hypothesis of an intermittent velocity-based control of posture is more relevant than position-based control. A simple model for COP velocity dynamics, based on a bounded correlated random walk, reproduces the main statistical signatures evidenced in the experimental series. The implications of these results are discussed
The dependence of dijet production on photon virtuality in ep collisions at HERA
The dependence of dijet production on the virtuality of the exchanged photon,
Q^2, has been studied by measuring dijet cross sections in the range 0 < Q^2 <
2000 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of
38.6 pb^-1.
Dijet cross sections were measured for jets with transverse energy E_T^jet >
7.5 and 6.5 GeV and pseudorapidities in the photon-proton centre-of-mass frame
in the range -3 < eta^jet <0. The variable xg^obs, a measure of the photon
momentum entering the hard process, was used to enhance the sensitivity of the
measurement to the photon structure. The Q^2 dependence of the ratio of low- to
high-xg^obs events was measured.
Next-to-leading-order QCD predictions were found to generally underestimate
the low-xg^obs contribution relative to that at high xg^obs. Monte Carlo models
based on leading-logarithmic parton-showers, using a partonic structure for the
photon which falls smoothly with increasing Q^2, provide a qualitative
description of the data.Comment: 35 pages, 6 eps figures, submitted to Eur.Phys.J.
Beauty photoproduction measured using decays into muons in dijet events in ep collisions at =318 GeV
The photoproduction of beauty quarks in events with two jets and a muon has
been measured with the ZEUS detector at HERA using an integrated luminosity of
110 pb. The fraction of jets containing b quarks was extracted from the
transverse momentum distribution of the muon relative to the closest jet.
Differential cross sections for beauty production as a function of the
transverse momentum and pseudorapidity of the muon, of the associated jet and
of , the fraction of the photon's momentum participating in
the hard process, are compared with MC models and QCD predictions made at
next-to-leading order. The latter give a good description of the data.Comment: 32 pages, 6 tables, 7 figures Table 6 and Figure 7 revised September
200
Search for a narrow charmed baryonic state decaying to D^*+/- p^-/+ in ep collisions at HERA
A resonance search has been made in the D^*+/- p^-/+ invariant-mass spectrum
with the ZEUS detector at HERA using an integrated luminosity of 126 pb^-1. The
decay channels D^*+ -> D^0 pi^+_s -> (K^- pi^+) pi^+_s and D^*+ -> D^0 pi^+_s
-> (K^- pi^+ pi^+ pi^-) pi^+_s (and the corresponding antiparticle decays) were
used to identify D^*+/- mesons. No resonance structure was observed in the
D^*+/- p^-/+ mass spectrum from more than 60000 reconstructed D^*+/- mesons.
The results are not compatible with a report of the H1 Collaboration of a
charmed pentaquark, Theta^0_c.Comment: 22 pages, 7 figures, 1 table; minor text revisions; 2 references
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