A Simple Mechanism for Complex Social Behavior

The evolution of cooperation is a paradox because natural selection should favor exploitative individuals that avoid paying their fair share of any costs. Such conflict between the self-interests of cooperating individuals often results in the evolution of complex, opponent-specific, social strategies and counterstrategies. However, the genetic and biological mechanisms underlying complex social strategies, and therefore the evolution of cooperative behavior, are largely unknown. To address this dearth of empirical data, we combine mathematical modeling, molecular genetic, and developmental approaches to test whether variation in the production of and response to social signals is sufficient to generate the complex partner-specific social success seen in the social amoeba Dictyostelium discoideum. Firstly, we find that the simple model of production of and response to social signals can generate the sort of apparent complex changes in social behavior seen in this system, without the need for partner recognition. Secondly, measurements of signal production and response in a mutant with a change in a single gene that leads to a shift in social behavior provide support for this model. Finally, these simple measurements of social signaling can also explain complex patterns of variation in social behavior generated by the natural genetic diversity found in isolates collected from the wild. Our studies therefore demonstrate a novel and elegantly simple underlying mechanistic basis for natural variation in complex social strategies in D. discoideum. More generally, they suggest that simple rules governing interactions between individuals can be sufficient to generate a diverse array of outcomes that appear complex and unpredictable when those rules are unknown

Uptake, distribution and elimination of palladium-doped polystyrene nanoplastics in rainbow trout (Oncorhynchus mykiss) following dietary exposure.

The ingestion of nanoplastics (NPs) by fish has led to concerns regarding fish health and food chain transfer, but analytical constraints have hindered quantitative data collection on their uptake and depuration. We used palladium-doped polystyrene nanoplastics (PS-Pd NPs, ~200 nm) to track particle fate in rainbow trout (Oncorhynchus mykiss) during a week-long dietary exposure and subsequent 7-day depuration period on a control diet (no added PS-Pd NPs). At Day 3 and 7 of the exposure, and after depuration, the mid intestine, hind intestine, liver, gallbladder, kidney, gill and carcass were sampled. All organs and the carcass were analysed for total Pd content by inductively couple plasma mass spectrometry. After 3 days of exposure, the mid (32.5 ± 8.3 ng g-1) and hind (42.3 ± 8.2 ng g-1) intestine had significantly higher total Pd concentrations compared to the liver and carcass (1.3 ± 0.4 and 3.4 ± 1.1 ng g-1, respectively). At Day 7, there was no time-related difference in any organ (or the carcass) total Pd concentrations compared to Day 3. When the total Pd content was expressed as a body distribution based on mass of tissue, the carcass contained the highest fraction with 72.5 ± 5.2 % at Day 7, which could raise concerns over transfer to higher trophic levels. The total number of particles that entered the fish over the 7 days was 94.5 ± 13.5 × 106 particles, representing 0.07 ± 0.01 % of the Pd the fish had been fed. Following depuration, there was no detectable Pd in any organ or the carcass, indicating clearance from the fish. These data indicate that these NPs are taken into the internal organs and carcass of fish, yet removal of the exposure results in substantial excretion to below the limit of detection

Nonmethane hydrocarbon measurements in the North Atlantic Flight Corridor during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment

Mixing ratios of nonmethane hydrocarbons (NMHCs) were not enhanced in whole air samples collected within the North Atlantic Flight Corridor (NAFC) during the fall of 1997. The investigation was conducted aboard NASA's DC-8 research aircraft, as part of the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX). NMHC enhancements were not detected within the general organized tracking system of the NAFC, nor during two tail chases of the DC-8's own exhaust. Because positive evidence of aircraft emissions was demonstrated by enhancements in both nitrogen oxides and condensation nuclei during SONEX, the NMHC results suggest that the commercial air traffic fleet operating in the North Atlantic region does not contribute at all or contributes negligibly to NMHCs in the NAFC. Copyright 2000 by the American Geophysical Union

Submillimeter Studies of Prestellar Cores and Protostars: Probing the Initial Conditions for Protostellar Collapse

Improving our understanding of the initial conditions and earliest stages of protostellar collapse is crucial to gain insight into the origin of stellar masses, multiple systems, and protoplanetary disks. Observationally, there are two complementary approaches to this problem: (1) studying the structure and kinematics of prestellar cores observed prior to protostar formation, and (2) studying the structure of young (e.g. Class 0) accreting protostars observed soon after point mass formation. We discuss recent advances made in this area thanks to (sub)millimeter mapping observations with large single-dish telescopes and interferometers. In particular, we argue that the beginning of protostellar collapse is much more violent in cluster-forming clouds than in regions of distributed star formation. Major breakthroughs are expected in this field from future large submillimeter instruments such as Herschel and ALMA.Comment: 12 pages, 9 figures, to appear in the proceedings of the conference "Chemistry as a Diagnostic of Star Formation" (C.L. Curry & M. Fich eds.

High risk of unprecedented UK rainfall in the current climate

This is the final version. Available on open access from Springer Nature via the DOI in this recordIn winter 2013/14 a succession of storms hit the UK leading to record rainfall and flooding in many regions including south east England. In the Thames river valley there was widespread flooding, with clean-up costs of over £1 billion. There was no observational precedent for this level of rainfall. Here we present analysis of a large ensemble of high-resolution initialised climate simulations to show that this event could have been anticipated, and that in the current climate there remains a high chance of exceeding the observed record monthly rainfall totals in many regions of the UK. In south east England there is a 7% chance of exceeding the current rainfall record in at least one month in any given winter. Expanding our analysis to some other regions of England and Wales the risk increases to a 34% chance of breaking a regional record somewhere each winter.A succession of storms during the 2013-2014 winter led to record flooding in the UK. Here, the authors use high-resolution climate simulations to show that this event could have been anticipated and that there remains a high chance of exceeding observed record monthly rainfall totals in many parts of the UK.Development of the Met Office Hadley Centre’s decadal climate predictions, the innovative scientific research that contributed to the NFRR, has been resourced through the MOHCCP, the NCIC, the Newton Fund, and SPECS. Development of the methodology was supported by the Newton Fund

Cell-permeable lanthanide-platinum(iv) anti-cancer prodrugs

Platinum compounds are a vital part of our anti-cancer arsenal, and determining the location and speciation of platinum compounds is crucial. We have synthesised a lanthanide complex bearing a salicylic group (Ln = Gd, Eu) which demonstrates excellent cellular accumulation and minimal cytotoxicity. Derivatisation enabled access to bimetallic lanthanide–platinum(II) and lanthanide–platinum(IV) complexes. Luminescence from the europium–platinum(IV) system was quenched, and reduction to platinum(II) with ascorbic acid resulted in a “switch-on” luminescence enhancement. We used diffusion-based 1H NMR spectroscopic methods to quantify cellular accumulation. The gadolinium–platinum(II) and gadolinium–platinum(IV) complexes demonstrated appreciable cytotoxicity. A longer delay following incubation before cytotoxicity was observed for the gadolinium–platinum(IV) compared to the gadolinium–platinum(II) complex. Functionalisation with octanoate ligands resulted in enhanced cellular accumulation and an even greater latency in cytotoxicity

Uptake and transport of novel amphiphilic polyelectrolyte-insulin nanocomplexes by caco-2 cells - towards oral insulin

“The original publication is available at www.springerlink.com”. Copyright SpringerPurpose: The influence of polymer architecture on cellular uptake and transport across Caco-2 cells of novel amphiphilic polyelectrolyte-insulin nanocomplexes was investigated. Method: Polyallylamine (PAA) (15 kDa) was grafted with palmitoyl chains (Pa) and subsequently modified with quaternary ammonium moieties (QPa). These two amphiphilic polyelectrolytes (APs) were tagged with rhodamine and their uptake by Caco-2 cells or their polyelectrolyte complexes (PECs) with fluorescein isothiocyanate-insulin (FITC-insulin) uptake were investigated using fluorescence microscopy. The integrity of the monolayer was determined by measurement of transepithelial electrical resistance (TEER). Insulin transport through Caco-2 monolayers was determined during TEER experiments. Result: Pa and insulin were co-localised in the cell membranes while QPa complexes were found within the cytoplasm. QPa complex uptake was not affected by calcium, cytochalasin D or nocodazole. Uptake was reduced by co-incubation with sodium azide, an active transport inhibitor. Both polymers opened tight junctions reversibly where the TEER values fell by up to 35 % within 30 minutes incubation with Caco-2 cells. Insulin transport through monolayers increased when QPa was used (0.27 ngmL-1 of insulin in basal compartment) compared to Pa (0.14 ngmL-1 of insulin in basal compartment) after 2 hours. Conclusion: These APs have been shown to be taken up by Caco-2 cells and reversibly open tight cell junctions. Further work is required to optimise these formulations with a view to maximising their potential to facilitate oral delivery of insulin.Peer reviewe

Language and social/emotional problems identified at a universal developmental assessment at 30 months

Non peer reviewedPublisher PD