Stronger regional biosecurity is essential to prevent hundreds of harmful biological invasions

Biological invasions often transcend political boundaries, but the capacity of countries to prevent invasions varies. How this variation in biosecurity affects the invasion risks posed to the countries involved is unclear. We aimed to improve the understanding of how the biosecurity of a country influences that of its neighbours. We developed six scenarios that describe biological invasions in regions with contiguous countries. Using data from alien species databases, socio‐economic and biodiversity data and species distribution models, we determined where 86 of 100 of the world's worst invasive species are likely to invade and have a negative impact in the future. Information on the capacity of countries to prevent invasions was used to determine whether such invasions could be avoided. For the selected species, we predicted 2,523 discrete invasions, most of which would have significant negative impacts and are unlikely to be prevented. Of these invasions, approximately a third were predicted to spread from the country in which the species first establishes to neighbouring countries where they would cause significant negative impacts. Most of these invasions are unlikely to be prevented as the country of first establishment has a low capacity to prevent invasions or has little incentive to do so as there will be no impact in that country. Regional biosecurity is therefore essential to prevent future harmful biological invasions. In consequence, we propose that the need for increased regional co‐operation to combat biological invasions be incorporated in global biodiversity targets.     

Crop rotations differ in soil carbon stabilization efficiency,but the response to quality of structural plant inputs is ambiguous

Plant and Soil - There is a trend of increasing woody biomass in tropical savannas. Here we ask what effect this increase may have on soil carbon pools and fluxes. Using a field experiment we...     

Anti-triatomine saliva immunoassays for the evaluation of impregnated netting trials against Chagas disease transmission

Insecticide-impregnated nets can kill triatomine bugs, but it remains unclear whether they can protect against Chagas disease transmission. In a field trial in Quequeña, Peru, sentinel guinea pigs placed in intervention enclosures covered by deltamethrin-treated nets showed significantly lower antibody responses to saliva of Triatoma infestans compared with animals placed in pre-existing control enclosures. Our results strongly suggest that insecticide-treated nets prevent triatomine bites and can thereby protect against infection with Trypanosoma cruzi. Anti-salivary immunoassays are powerful new tools to evaluate intervention strategies against Chagas disease.     

Small Molecule Inhibition of HIV-1–Induced MHC-I Down-Regulation Identifies a Temporally Regulated Switch in Nef Action

HIV-1 Nef triggers down-regulation of cell-surface MHC-I by assembling a Src family kinase (SFK)-ZAP-70/Syk-PI3K cascade. Here, we report that chemical disruption of the Nef-SFK interaction with the small molecule inhibitor 2c blocks assembly of the multi-kinase complex and represses HIV-1–mediated MHC-I down-regulation in primary CD4⁺ T-cells. 2c did not interfere with the PACS-2–dependent trafficking of Nef required for the Nef-SFK interaction or the AP-1 and PACS-1–dependent sequestering of internalized MHC-I, suggesting the inhibitor specifically interfered with the Nef-SFK interaction required for triggering MHC-I down-regulation. Transport studies revealed Nef directs a highly regulated program to down-regulate MHC-I in primary CD4⁺ T-cells. During the first two days after infection, Nef assembles the 2c-sensitive multi-kinase complex to trigger down-regulation of cell-surface MHC-I. By three days postinfection Nef switches to a stoichiometric mode that prevents surface delivery of newly synthesized MHC-I. Pharmacologic inhibition of the multi-kinase cascade prevents the Nef-dependent block in MHC-I transport, suggesting the signaling and stoichiometric modes are causally linked. Together, these studies resolve the seemingly controversial models that describe Nef-induced MHC-I down-regulation and provide new insights into the mechanism of Nef action.     

Protein Conformational Changes Are Detected and Resolved Site Specifically by Second-Harmonic Generation

We present here a straightforward, broadly applicable technique for real-time detection and measurement of protein conformational changes in solution. This method is based on tethering proteins labeled with a second-harmonic generation (SHG) active dye to supported lipid bilayers. We demonstrate our method by measuring the conformational changes that occur upon ligand binding with three well-characterized proteins labeled at lysine residues: calmodulin (CaM), maltose-binding protein (MBP), and dihydrofolate reductase (DHFR). We also create a single-site cysteine mutant of DHFR engineered within the Met20 catalytic loop region and study the protein’s structural motion at this site. Using published x-ray crystal structures, we show that the changes in the SHG signals upon ligand binding are the result of structural motions that occur at the labeled sites between the apo and ligand-bound forms of the proteins, which are easily distinguished from each other. In addition, we demonstrate that different magnitudes of the SHG signal changes are due to different and specific ligand-induced conformational changes. Taken together, these data illustrate the potential of the SHG approach for detecting and measuring protein conformational changes for a wide range of biological applications.     

Snake modulates constriction in response to prey's heartbeat

Many species of snakes use constriction-the act of applying pressure via loops of their trunk-to subdue and kill their prey. Constriction is costly and snakes must therefore constrict their prey just long enough to ensure death. However, it remains unknown how snakes determine when their prey is dead. Here, we demonstrate that boas (Boa constrictor) have the remarkable ability to detect a heartbeat in their prey and, based on this signal, modify the pressure and duration of constriction accordingly. We monitored pressure generated by snakes as they struck and constricted warm cadaveric rats instrumented with a simulated heart. Snakes responded to the beating heart by constricting longer and with greater total pressure than when constricting rats with no heartbeat. When the heart was stopped midway through the constriction, snakes abandoned constriction shortly after the heartbeat ceased. Furthermore, snakes naive to live prey also responded to the simulated heart, suggesting that this behaviour is at least partly innate. These results are an example of how snakes integrate physiological cues from their prey to modulate a complex and ancient behavioural pattern.