Retrovirus budding may constitute a port of entry for drug carriers

AbstractThis paper investigates the relation between viral infection and cell uptake of liposomes and nanoparticles. A defective virus was used to infect two types of cells: cells allowing virus budding (psi2neo cells) and cells bereft of a virus exit process (NIH 3T3 cells). This study has revealed that cell uptake of pH-sensitive-liposomes is highly dependent on the virus exit process, since it ensued only when virus budding occurred. This preferential uptake of pH-sensitive liposomes by infected cells was not carrier-specific because similar uptake was observed with non-biodegradable fluorescent nanoparticles using confocal microscopy. Also, inhibition of neo gene expression by oligonucleotide pH-sensitive-liposomes was only observed in the cell system (psi2neo) endowed with a virus exit process. Finally, increased membrane fluidity was noted in the infected cells, possibly reflecting membrane perturbation due to virus budding. We suggest that this membrane perturbation may be the key to the uptake of the different colloidal carriers. Infected cells could, thus, constitute a natural target for particulate drug carriers

Vision and Foraging in Cormorants: More like Herons than Hawks?

Background Great cormorants (Phalacrocorax carbo L.) show the highest known foraging yield for a marine predator and they are often perceived to be in conflict with human economic interests. They are generally regarded as visually-guided, pursuit-dive foragers, so it would be expected that cormorants have excellent vision much like aerial predators, such as hawks which detect and pursue prey from a distance. Indeed cormorant eyes appear to show some specific adaptations to the amphibious life style. They are reported to have a highly pliable lens and powerful intraocular muscles which are thought to accommodate for the loss of corneal refractive power that accompanies immersion and ensures a well focussed image on the retina. However, nothing is known of the visual performance of these birds and how this might influence their prey capture technique. Methodology/Principal Findings We measured the aquatic visual acuity of great cormorants under a range of viewing conditions (illuminance, target contrast, viewing distance) and found it to be unexpectedly poor. Cormorant visual acuity under a range of viewing conditions is in fact comparable to unaided humans under water, and very inferior to that of aerial predators. We present a prey detectability model based upon the known acuity of cormorants at different illuminances, target contrasts and viewing distances. This shows that cormorants are able to detect individual prey only at close range (less than 1 m). Conclusions/Significance We conclude that cormorants are not the aquatic equivalent of hawks. Their efficient hunting involves the use of specialised foraging techniques which employ brief short-distance pursuit and/or rapid neck extension to capture prey that is visually detected or flushed only at short range. This technique appears to be driven proximately by the cormorant's limited visual capacities, and is analogous to the foraging techniques employed by herons

Long-Term GPS Tracking of Ocean Sunfish Mola mola Offers a New Direction in Fish Monitoring

Satellite tracking of large pelagic fish provides insights on free-ranging behaviour, distributions and population structuring. Up to now, such fish have been tracked remotely using two principal methods: direct positioning of transmitters by Argos polar-orbiting satellites, and satellite relay of tag-derived light-level data for post hoc track reconstruction. Error fields associated with positions determined by these methods range from hundreds of metres to hundreds of kilometres. However, low spatial accuracy of tracks masks important details, such as foraging patterns. Here we use a fast-acquisition global positioning system (Fastloc GPS) tag with remote data retrieval to track long-term movements, in near real time and position accuracy of <70 m, of the world's largest bony fish, the ocean sunfish Mola mola. Search-like movements occurred over at least three distinct spatial scales. At fine scales, sunfish spent longer in highly localised areas with faster, straighter excursions between them. These ‘stopovers’ during long-distance movement appear consistent with finding and exploiting food patches. This demonstrates the feasibility of GPS tagging to provide tracks of unparalleled accuracy for monitoring movements of large pelagic fish, and with nearly four times as many locations obtained by the GPS tag than by a conventional Argos transmitter. The results signal the potential of GPS-tagged pelagic fish that surface regularly to be detectors of resource ‘hotspots’ in the blue ocean and provides a new capability for understanding large pelagic fish behaviour and habitat use that is relevant to ocean management and species conservation

Towards the integration of animal-borne instruments into global ocean observing systems

Funding: BBVA Foundation (“Ayudas Fundación BBVA a Equipos de Investigación Científica 2016”) and the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 794938; Spanish Government (grant “Juan de la Cierva-Formación” FJCI-2014-20064, grant “José Castillejo” CAS17/00193) (D.M.).Marine animals are increasingly instrumented with environmental sensors that provide large volumes of oceanographic data. Here, we conduct an innovative and comprehensive global analysis to determine the potential contribution of animal‐borne instruments (ABI) into ocean observing systems (OOSs) and provide a foundation to establish future integrated ocean monitoring programmes. We analyse the current gaps of the long‐term Argo observing system (>1.5 million profiles) and assess its spatial overlap with the distribution of marine animals across eight major species groups (tuna and billfishes, sharks and rays, marine turtles, pinnipeds, cetaceans, sirenians, flying seabirds and penguins). We combine distribution ranges of 183 species and satellite tracking observations from >3,000 animals. Our analyses identify potential areas where ABI could complement OOS. Specifically, ABI have the potential to fill gaps in marginal seas, upwelling areas, the upper 10 m of the water column, shelf regions and polewards of 60° latitude. Our approach provides the global baseline required to plan the integration of ABI into global and regional OOS while integrating conservation and ocean monitoring priorities.Publisher PDFPeer reviewe

COVID-19 lockdown allows researchers to quantify the effects of human activity on wildlife

Funding: Manuscript preparation was supported through: a Radcliffe Fellowship at the Radcliffe Institute for Advanced Study, Harvard University (to C.R.); the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 798091 (to M.-C.L.); and Autonomous Province of Trento ordinary funds to Fondazione Edmund Mach (to F.C.).Reduced human mobility during the pandemic will reveal critical aspects of our impact on animals, providing important guidance on how best to share space on this crowded planet.PostprintPeer reviewe

A vision for incorporating human mobility in the study of human-wildlife interactions

As human activities increasingly shape land- and seascapes, understanding human-wildlife interactions is imperative for preserving biodiversity. Habitats are impacted not only by static modifications, such as roads, buildings and other infrastructure, but also by the dynamic movement of people and their vehicles occurring over shorter time scales. While there is increasing realization that both components of human activity significantly affect wildlife, capturing more dynamic processes in ecological studies has proved challenging. Here, we propose a novel conceptual framework for developing a ‘Dynamic Human Footprint’ that explicitly incorporates human mobility, providing a key link between anthropogenic stressors and ecological impacts across spatiotemporal scales. Specifically, the Dynamic Human Footprint integrates a range of metrics to fully acknowledge the time-varying nature of human activities and to enable scale-appropriate assessments of their impacts on wildlife behavior, demography, and distributions. We review existing terrestrial and marine human mobility data products and provide a roadmap for how these could be integrated and extended to enable more comprehensive analyses of human impacts on biodiversity in the Anthropocene

Quantifying prey availability using the foraging plasticity of a marine predator, the little penguin

Detecting changes in marine food webs is challenging, but top predators can provide information on lower trophic levels. However, many commonly measured predator responses can be decoupled from prey availability by plasticity in predator foraging effort. This can be overcome by directly measuring foraging effort and success and integrating these into a measure of foraging efficiency analogous to the catch per unit effort (CPUE) index employed by fisheries. We extended existing CPUE methods so that they would be applicable to the study of generalist foragers, which introduce another layer of complexity through dietary plasticity. Using this method, we inferred species‐specific patterns in prey availability and estimated taxon‐specific biomass consumption. We recorded foraging trip duration and body mass change of breeding little penguins Eudyptula minor and combined these with diet composition identified via non‐invasive faecal DNA metabarcoding to derive CPUE indices for individual prey taxa. We captured weekly patterns of availability of key fish prey in the penguins’ diet and identified a major prey shift from sardine Sardinops sagax to red cod Pseudophycis bachus between years. In each year, predation on a dominant fish species (~150 g/day) was replaced by greater diversity of fish in the diet as the breeding season progressed. We estimated that the colony extracted ~1,300 tonnes of biomass from their coastal ecosystem over two breeding seasons, including 219 tonnes of the commercially important sardine and 215 tonnes of red cod. This enhanced pCPUE is applicable to most central‐placed foragers and offers a valuable alternative to existing metrics. Informed prey‐species biomass estimates extracted by apex and meso predators will be a useful input for mass‐balance ecosystem models and for informing ecosystem‐based management. A free Plain Language Summary can be found within the Supporting Information of this article