3,211 research outputs found
Community responses to seawater warming are conserved across diverse biological groupings and taxonomic resolutions
Temperature variability is a major driver of ecological pattern, with recent changes in average and extreme temperatures having significant impacts on populations, communities and ecosystems. In the marine realm, very few experiments have manipulated temperature in situ, and current understanding of temperature effects on community dynamics is limited. We developed new technology for precise seawater temperature control to examine warming effects on communities of bacteria, microbial eukaryotes (protists) and metazoans. Despite highly contrasting phylogenies, size spectra and diversity levels, the three community types responded similarly to seawater warming treatments of +3°C and +5°C, highlighting the critical and overarching importance of temperature in structuring communities. Temperature effects were detectable at coarse taxonomic resolutions and many taxa responded positively to warming, leading to increased abundances at the community-level. Novel field-based experimental approaches are essential to improve mechanistic understanding of how ocean warming will alter the structure and functioning of diverse marine communities
The central image of a gravitationally lensed quasar
A galaxy can act as a gravitational lens, producing multiple images of a
background object. Theory predicts there should be an odd number of images but,
paradoxically, almost all observed lenses have 2 or 4 images. The missing image
should be faint and appear near the galaxy's center. These ``central images''
have long been sought as probes of galactic cores too distant to resolve with
ordinary observations. There are five candidates, but in one case the third
image is not necessarily a central image, and in the others, the central
component might be a foreground source rather than a lensed image. Here we
report the most secure identification of a central image, based on radio
observations of PMN J1632-0033, one of the latter candidates. Lens models
incorporating the central image show that the mass of the lens galaxy's central
black hole is less than 2 x 10^8 M_sun, and the galaxy's surface density at the
location of the central image is more than 20,000 M_sun per square parsec, in
agreement with expectations based on observations of galaxies hundreds of times
closer to the Earth.Comment: Nature, in press [7 pp, 2 figs]. Standard media embargo applies
before publicatio
Schistosoma haematobium infection levels determine the effect of praziquantel treatment on anti-schistosome and anti-mite antibodies
Field studies show an association between schistosome infection and atopy, but the effects of anti-helminthic treatment on this association have not yet been investigated in human populations with different schistosome endemicity levels. This study aimed to compare the effects of anti-helminthic treatment on responses directed against the house dust mite Dermatophagoides pteronyssinus (Derp1) and Schistosoma haematobium in Zimbabwean populations living in high and low schistosome infection areas. Derp1- and schistosome-specific IgE and IgG4 antibodies were quantified by ELISA before and 6 weeks after anti-helminthic treatment. Following treatment, there were changes in the immune responses, which varied with place of residence. After allowing for the effects of sex, age and baseline infection intensity, there was no significant treatment effect on the change in anti-schistosome IgE and IgG4 in the high infection area. However, the anti-schistosome IgE/IgG4 ratio increased significantly, while anti-Derp1 IgE responses decreased as a result of treatment. In the low infection area, treatment resulted in a significant increase in anti-worm IgE levels, but there was no significant treatment effect on anti-schistosome or anti-Derp1 IgE/IgG4 ratios. Thus, the study shows that the level of schistosome endemicity affects the host responses to schistosome and mite antigens following anti-helminthic treatment
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PAUSED for thought? Using verbal protocol analysis to understand the situational and temporal cues in the decision-making of residential burglars
Using verbal protocol analysis (VPA) alongside semi-structured interviews, this research aimed to explicate the situational dynamics that inform the decision-making and target selection of residential burglars. Focusing on the VPA method, novel to criminological research, the paper considers the contribution of this empirical approach for studying the decision-making of offenders in situ. The findings reveal a series of cues, encapsulated in the ‘PAUSED’ model, that are drawn upon by residential burglars to assess the suitability of a target; determining whether it is profitable, accessible, uninterruptible, surveillable, escapable and/or dishonourable. The PAUSED model is unpacked to articulate a collection of visual stimuli that serve to disrupt and suspend the otherwise rapid flow of target appraisal. Discussion of the strengths and limitations of the VPA method, and how it can compliment other approaches to understanding the decision-making of residential burglars, is provided
Redox linked flavin sites in extracellular decaheme proteins involved in microbe-mineral electron transfer
Extracellular microbe-mineral electron transfer is a major driving force for the oxidation of organic carbon in many subsurface environments. Extracellular multi-heme cytochromes of the Shewenella genus play a major role in this process but the mechanism of electron exchange at the interface between cytochrome and acceptor is widely debated. The 1.8 Å x-ray crystal structure of the decaheme MtrC revealed a highly conserved CX8C disulfide that, when substituted for AX8A, severely compromised the ability of S. oneidensis to grow under aerobic conditions. Reductive cleavage of the disulfide in the presence of flavin mononucleotide (FMN) resulted in the reversible formation of a stable flavocytochrome. Similar results were also observed with other decaheme cytochromes, OmcA, MtrF and UndA. The data suggest that these decaheme cytochromes can transition between highly reactive flavocytochromes or less reactive cytochromes, and that this transition is controlled by a redox active disulfide that responds to the presence of oxygen
Entomological Surveillance of Behavioural Resilience and Resistance in Residual Malaria Vector Populations.
The most potent malaria vectors rely heavily upon human blood so they are vulnerable to attack with insecticide-treated nets (ITNs) and indoor residual spraying (IRS) within houses. Mosquito taxa that can avoid feeding or resting indoors, or by obtaining blood from animals, mediate a growing proportion of the dwindling transmission that persists as ITNs and IRS are scaled up. Increasing frequency of behavioural evasion traits within persisting residual vector systems usually reflect the successful suppression of the most potent and vulnerable vector taxa by IRS or ITNs, rather than their failure. Many of the commonly observed changes in mosquito behavioural patterns following intervention scale-up may well be explained by modified taxonomic composition and expression of phenotypically plastic behavioural preferences, rather than altered innate preferences of individuals or populations. Detailed review of the contemporary evidence base does not yet provide any clear-cut example of true behavioural resistance and is, therefore, consistent with the hypothesis presented. Caution should be exercised before over-interpreting most existing reports of increased frequency of behavioural traits which enable mosquitoes to evade fatal contact with insecticides: this may simply be the result of suppressing the most behaviourally vulnerable of the vector taxa that constituted the original transmission system. Mosquito taxa which have always exhibited such evasive traits may be more accurately described as behaviourally resilient, rather than resistant. Ongoing national or regional entomological monitoring surveys of physiological susceptibility to insecticides should be supplemented with biologically and epidemiologically meaningfully estimates of malaria vector population dynamics and the behavioural phenotypes that determine intervention impact, in order to design, select, evaluate and optimize the implementation of vector control measures
Entangled-State Cycles of Atomic Collective-Spin States
We study quantum trajectories of collective atomic spin states of
effective two-level atoms driven with laser and cavity fields. We show that
interesting ``entangled-state cycles'' arise probabilistically when the (Raman)
transition rates between the two atomic levels are set equal. For odd (even)
, there are () possible cycles. During each cycle the
-qubit state switches, with each cavity photon emission, between the states
, where is a Dicke state in a rotated
collective basis. The quantum number (), which distinguishes the
particular cycle, is determined by the photon counting record and varies
randomly from one trajectory to the next. For even it is also possible,
under the same conditions, to prepare probabilistically (but in steady state)
the Dicke state , i.e., an -qubit state with excitations,
which is of particular interest in the context of multipartite entanglement.Comment: 10 pages, 9 figure
Regulation of immune responses in primary biliary cholangitis: a transcriptomic analysis of peripheral immune cells
BACKGROUND AIMS: In patients with primary biliary cholangitis (PBC), the serum liver biochemistry measured during treatment with ursodeoxycholic acid-the UDCA response-accurately predicts long-term outcome. Molecular characterization of patients stratified by UDCA response can improve biological understanding of the high-risk disease, thereby helping to identify alternative approaches to disease-modifying therapy. In this study, we sought to characterize the immunobiology of the UDCA response using transcriptional profiling of peripheral blood mononuclear cell subsets. METHODS: We performed bulk RNA-sequencing of monocytes and TH1, TH17, TREG, and B cells isolated from the peripheral blood of 15 PBC patients with adequate UDCA response ("responders"), 16 PBC patients with inadequate UDCA response ("nonresponders"), and 15 matched controls. We used the Weighted Gene Co-expression Network Analysis to identify networks of co-expressed genes ("modules") associated with response status and the most highly connected genes ("hub genes") within them. Finally, we performed a Multi-Omics Factor Analysis of the Weighted Gene Co-expression Network Analysis modules to identify the principal axes of biological variation ("latent factors") across all peripheral blood mononuclear cell subsets. RESULTS: Using the Weighted Gene Co-expression Network Analysis, we identified modules associated with response and/or disease status (q<0.05) in each peripheral blood mononuclear cell subset. Hub genes and functional annotations suggested that monocytes are proinflammatory in nonresponders, but antiinflammatory in responders; TH1 and TH17 cells are activated in all PBC cases but better regulated in responders; and TREG cells are activated-but also kept in check-in responders. Using the Multi-Omics Factor Analysis, we found that antiinflammatory activity in monocytes, regulation of TH1 cells, and activation of TREG cells are interrelated and more prominent in responders. CONCLUSIONS: We provide evidence that adaptive immune responses are better regulated in patients with PBC with adequate UDCA response
The fitness of African malaria vectors in the presence and limitation of host behaviour
<p>Background
Host responses are important sources of selection upon the host species range of ectoparasites and phytophagous insects. However little is known about the role of host responses in defining the host species range of malaria vectors. This study aimed to estimate the relative importance of host behaviour to the feeding success and fitness of African malaria vectors, and assess its ability to predict their known host species preferences in nature.</p>
<p>Methods
Paired evaluations of the feeding success and fitness of African vectors Anopheles arabiensis and Anopheles gambiae s.s in the presence and limitation of host behaviour were conducted in a semi-field system (SFS) at Ifakara Health Institute, Tanzania. In one set of trials, mosquitoes were released within the SFS and allowed to forage overnight on a host that was free to exhibit natural behaviour in response to insect biting. In the other, mosquitoes were allowed to feed directly on from the skin surface of immobile hosts. The feeding success and subsequent fitness of vectors under these conditions were investigated on 6 host types (humans, calves, chickens, cows, dogs and goats) to assess whether physical movements of preferred host species (cattle for An. arabiensis, humans for An. gambiae s.s.) were less effective at preventing mosquito bites than those of common alternatives.</p>
<p>Results
Anopheles arabiensis generally had greater feeding success when applied directly to host skin than when foraging on unrestricted hosts (in five of six host species). However, An. gambiae s.s obtained blood meals from free and restrained hosts with similar success from most host types (four out of six). Overall, the blood meal size, oviposition rate, fecundity and post-feeding survival of mosquito vectors were significantly higher after feeding on hosts free to exhibit behaviour, than those who were immobilized during feeding trials.</p>
<p>Conclusions
Allowing hosts to move freely during exposure to mosquitoes was associated with moderate reductions in mosquito feeding success, but no detrimental impact to the subsequent fitness of mosquitoes that were able to feed upon them. This suggests that physical defensive behaviours exhibited by common host species including humans do not impose substantial fitness costs on African malaria vectors.</p>
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