Pre-production pellets are an abundant form of plastic waste in the marine environment whose principal impacts arise from inadvertent ingestion by various organisms when mistaken for food. Pellets ...also represent a carrier for both organic and metallic contaminants through their adsorption to the modified plastic surface. In the present study, we examine the adsorption of trace metals (Cd, Co, Cr, Cu, Ni, Pb) to both virgin and beached (aged) pellets under estuarine conditions in order to better understand the role of plastic materials on the transport and behaviour of metals from river to ocean. Metals added to river water and sea water adsorbed to both pellet types with isotherms defined by either the Langmuir or Freundlich model. With increasing pH in river water, adsorption of Cd, Co, Ni and Pb increased, adsorption of Cr decreased and adsorption of Cu was relatively invariant. Along a salinity gradient, created by mixing river and sea waters in different proportions, adsorption of Cd, Co and Ni decreased, adsorption of Cr increased and adsorption of Cu and Pb exhibited a minimum towards the fresh water end-member. In all experiments and for all metals, adsorption was considerably greater to beached pellets than to virgin pellets, presumably because of the weathering of and adsorption and attrition of charged minerals by the former. Speciation considerations suggest that adsorption to the pellet surface largely involves metal cations or oxyanions (e.g. HCrO4− and CrO42−), although additional forms of Cu and Pb (e.g. organic complexes) may also be involved. Despite mass-normalised adsorption constants being lower than equivalent values defining the adsorption of metals to sediments, microplastics should be regarded as a component of the suspended load of estuaries whose precise role on contaminant transport requires further study.
•The adsorption of trace metals to plastic pellets has been studied under estuarine conditions.•Cd, Co, Ni and Pb exhibit increasing adsorption with increasing pH and decreasing salinity.•Cr(VI) exhibits decreasing adsorption with increasing pH and decreasing salinity.•Cu adsorption exhibits no clear dependence on these variables.•Metal adsorption is considerably greater to aged pellets than to new, polyethylene pellets.
Plastic production pellets collected from beaches of south west England contain variable concentrations of trace metals (Cr, Co, Ni, Cu, Zn, Cd and Pb) that, in some cases, exceed concentrations ...reported for local estuarine sediments. The rates and mechanisms by which metals associate with virgin and beached polyethylene pellets were studied by adding a cocktail of 5 μg L
−1 of trace metals to 10 g L
−1 pellet suspensions in filtered seawater. Kinetic profiles were modelled using a pseudo-first-order equation and yielded response times of less than about 100 h and equilibrium partition coefficients of up to about 225 ml g
−1 that were consistently higher for beached pellets than virgin pellets. Adsorption isotherms conformed to both the Langmuir and Freundlich equations and adsorption capacities were greater for beached pellets than for virgin pellets. Results suggest that plastics may represent an important vehicle for the transport of metals in the marine environment.
► Beached plastic production pellets contain considerable concentrations of trace metals. ► In laboratory experiments trace metals are shown to adsorb to both virgin and beached pellets. ► Metal adsorption is greater on aged pellets. ► Pellets may represent an important vehicle for metal transport in the marine environment.
Trace metals accumulate on plastic resin pellets in the marine environment through adsorption to the polymer and to chemical and biological attritions thereon.
Developing technologies for efficient and scalable disruption of gene expression will provide powerful tools for studying gene function, developmental pathways, and disease mechanisms. Here, we ...develop clustered regularly interspaced short palindromic repeat interference (CRISPRi) to repress gene expression in human induced pluripotent stem cells (iPSCs). CRISPRi, in which a doxycycline-inducible deactivated Cas9 is fused to a KRAB repression domain, can specifically and reversibly inhibit gene expression in iPSCs and iPSC-derived cardiac progenitors, cardiomyocytes, and T lymphocytes. This gene repression system is tunable and has the potential to silence single alleles. Compared with CRISPR nuclease (CRISPRn), CRISPRi gene repression is more efficient and homogenous across cell populations. The CRISPRi system in iPSCs provides a powerful platform to perform genome-scale screens in a wide range of iPSC-derived cell types, dissect developmental pathways, and model disease.
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•Inducible CRISPRi iPSCs provide a valuable resource for rapid gene knockdown•CRISPRi knockdown is efficient, tunable, and reversible in iPSCs•CRISPRi knockdown is highly specific•CRISPRi enables disease modeling in iPSC-derived cardiomyocytes
In this article, Mandegar and colleagues utilize CRISPR interference for efficient gene knockdown in iPSCs and their differentiated cell derivatives. The CRISPRi tools and cell lines presented in this study are highly versatile and serve as a useful resource for the cell and stem cell biology communities.
Microplastics are known to be associated with co-contaminants, but little is understood about the mechanisms by which these chemicals are transferred from ingested plastic to organisms. This study ...simulates marine avian gastric conditions in vitro to examine the bioaccessibility of authigenic metals (Fe, Mn) and trace metals (Co, Pb) that have been acquired by polyethylene microplastic pellets from their environment. Specifically, different categories of pellet were collected from beaches in Cornwall, southwest England, and exposed to an acidified saline solution of pepsin (pH ∼ 2.5) at 40 °C over a period of 168 h with extracted metal and residual metal (available to dilute aqua regia) analysed by ICP-MS. For Fe, Mn and Co, kinetic profiles consisted of a relatively rapid initial period of mobilisation followed by a more gradual approach to quasi-equilibrium, with data defined by a diffusion model and median rate constants ranging from about 0.0002 (μg L−1)−1 h−1 for Fe to about 7 (μg L−1)−1 h−1 for Co. Mobilisation of Pb was more complex, with evidence of secondary maxima and re-adsorption of the metal to the progressively modified pellet surface. At the end of the time-courses, maximum total concentrations were 38.9, 0.81, 0.014 and 0.10 μg g−1 for Fe, Mn, Co and Pb, respectively, with maximum respective percentage bioaccessibilities of around 60, 80, 50 and 80. When compared with toxicity reference values for seabirds, the significance of metals acquired by microplastics from the environment and exposed to avian digestive conditions is deemed to be low, but studies of a wider range of plastics and metal associations (e.g. as additives) are required for a more comprehensive risk assessment.
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•Concentrations of Fe, Mn, Co and Pb associated with the surface of marine plastic pellets have been determined.•Different types of pellets have been subjected to PBET to simulate avian plastic ingestion.•Mobilisation kinetics for Fe, Mn and Co conformed to a simple diffusion model.•Bioaccessibilites ranged from about 30% to 80% but the risk to birds is deemed negligible.
Metals on microplastics that have been acquired from their environment are highly bioaccessible to seabirds but concentrations mobilised are not deemed significant.
Phenomics offers technological advances for high-dimensional phenotyping, facilitating rapid, high-throughput assessment of physiological performance and has proven invaluable in global research ...challenges including drug discovery and food security. However, this rapidly growing discipline has remained largely inaccessible to the increasingly urgent challenge of assessing organismal functional sensitivity to global change drivers. Here, we investigate the response of an ecologically important marine invertebrate to multiple environmental drivers using Energy Proxy Traits (EPTs), a new approach for measuring complex phenotypes captured on video as a spectrum of energy levels across different temporal frequencies in fluctuating pixel values. We imaged three developmental stages of the common prawn Palaemon serratus at different salinities and temperatures, and measured EPTs and heart rate, a major proxy of physiological performance in ectotherms present across stages. Significant interactions were detected between temperature, developmental stage and salinity in frequency-specific energy levels. Despite cardiac activity being a significant contributor to the EPT spectra, treatment interactions were different from those observed on EPTs, highlighting additional phenotypic drivers of EPTs. Elevated temperature resulted in a shift of the EPT spectra towards higher frequency signals, indicating a reallocation of resources within the phenome. Using a non-linear dimensionality reduction, we interrogated the responses of EPT spectra in high-dimensional space. We discovered complex developmental-stage specific sensitivities, highlighting both the complexity of phenotypic responses, and the limits of using univariate approaches with pre-selected traits to assess responses to multiple global environmental drivers. EPTs are a high-dimensional, transferrable method of phenotyping, and are therefore highly relevant to addressing the current limitations of traditional methods of phenotyping applied to assessing biological sensitivity to drivers of global change. We predict that EPTs will become an important tool for indiscriminate phenotyping, transferrable between species, developmental stages and experimental designs.
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•Analysis of fluctuating pixel brightness quantifies complex biological responses.•Responses of the common prawn to global change drivers are high-dimensional.•Innovation is urgently needed to more-fully capture whole-organismal responses.•High-dimensional phenomic approaches can be transferrable and scalable.•Such transferrable approaches are urgently needed to assess biological impacts.
Offshore ocean aquaculture is expanding globally to meet the growing demand for sustainable food production. At the United Kingdom's largest longline mussel farm, we assessed the potential for the ...farm to improve the habitat suitability for commercially important crustaceans. Modelled distribution patterns (GAM & GLM) predicted the low complexity seabed beneath the mussel farm was 34–94 % less suitable for European lobster (Homarus gammarus) and brown crab (Cancer pagurus) than nearby rocky reefs. The mussel farm operations, however, contributed large amounts of living mussels and shell material to the seabed. Acoustic telemetry revealed that H.gammarus remained within the farm for between 2 and 283 days using both the farm anchors and areas of seabed dominated by fallen mussels for refuge. In contrast, C. pagurus movements showed no affinity to either the farm infrastructure or benthic habitat under the farm. Stable isotope analysis indicated a high dietary niche overlap in C. pagurus and H. gammarus (67.8 and 84.6 %) between the mussel farm (mixed muddy sediment) and nearby rocky reef. Our mixed-methods suggest that the mussel farm augments structural complexity on the seabed providing refuge and similar feeding opportunities for lobster and crab as their typical habitat on rocky reefs. Longline mussel farms can deliver profound biodiversity-positive effects through biogenic augmentation of degraded habitat for commercial species and potential for co-benefits to local fisheries.
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•As a result of industrial fishing practices seabed habitats have fundamentally changed over prolonged time periods•Aquaculture infrastructure helps to restore the seabed by creating habitat and preventing damage from bottom-towed fishing.•Longline mussel farming can create seabed habitats which will be exploited by commercially important marine species.•Longline mussel farms can therefore support sustainable development goals and commercial fisheries.
Pluripotency defines the unlimited potential of individual cells of vertebrate embryos, from which all adult somatic cells and germ cells are derived. Understanding how the programming of ...pluripotency evolved has been obscured in part by a lack of data from lower vertebrates; in model systems such as frogs and zebrafish, the function of the pluripotency genes NANOG and POU5F1 have diverged. Here, we investigated how the axolotl ortholog of NANOG programs pluripotency during development. Axolotl NANOG is absolutely required for gastrulation and germ-layer commitment. We show that in axolotl primitive ectoderm (animal caps; ACs) NANOG and NODAL activity, as well as the epigenetic modifying enzyme DPY30, are required for the mass deposition of H3K4me3 in pluripotent chromatin. We also demonstrate that all 3 protein activities are required for ACs to establish the competency to differentiate toward mesoderm. Our results suggest the ancient function of NANOG may be establishing the competence for lineage differentiation in early cells. These observations provide insights into embryonic development in the tetrapod ancestor from which terrestrial vertebrates evolved.
Abstract
This decade represents a critical period to profoundly rethink human–nature interactions in order to address the interwoven climate and biodiversity crises. Marine Protected Areas (MPAs) ...demonstrate promise for increasing ecosystem resilience and reversing habitat and population declines, but outcomes vary considerably from context to context. Partially protected areas offer a compromise between ecological recovery and the social needs of local communities, but their success is contingent on an array of factors. This in-depth review summarizes 15 years of marine conservation research and impact in Lyme Bay (southwest UK), to serve as a model for the future adoption of partially protected MPAs. The findings from the UK’s longest integrated socioecological monitoring MPA study are presented and supplemented by an evaluation of the whole-site management approach as a core element of Lyme Bay’s achievements. The journey from research to improved monitoring and ambitious policy is illustrated within and interspersed with stories of novel discoveries, ongoing challenges, and method developments. What started as a dedicated group of community members has grown into an immense collaboration between fishers, scientists, NGOs, and regulators, and their combined efforts have sent ripple effects of positive change across the globe.
Multi-use marine protected areas (MPAs) are increasingly designated towards achieving global conservation targets. To develop effective management, the impact of permitted activities must be ...understood. Potting for shellfish occurs on temperate rocky reefs globally with impact not fully quantified. This UK-based study used underwater video to quantify (a) benthic condition of rocky reefs, (b) mechanisms of potting interaction and (c) true footprint of potting. Assemblages in static gear areas were more indicative of a healthy reef than those in mixed gear areas. Damage was recorded during pot hauling, but the area of damage was not the entire pot haul path. 25–30% of individuals were damaged (commonly through tissue abrasion) or removed. Notably, damage occurred to some long-lived, slow growing taxa raising concerns over impacts. Potting is more destructive than previously thought and managers must balance ecology with social and economic considerations to determine what level of impact is acceptable.
•Impacts of potting on UK temperate rocky reefs quantified using underwater video.•Novel method using GoPro cameras to observe direct potting impacts.•Areas fished with pots characterised by species indicative of a healthy reef system.•Damage to long lived, slow growing taxa of potential concern.•Managers must decide what level of impact is ‘acceptable’.
The spread of multidrug-resistance in Gram-negative bacterial pathogens presents a major clinical challenge, and new approaches are required to combat these organisms. Nitric oxide (NO) is a ...well-known antimicrobial that is produced by the immune system in response to infection, and numerous studies have demonstrated that NO is a respiratory inhibitor with both bacteriostatic and bactericidal properties. However, given that loss of aerobic respiratory complexes is known to diminish antibiotic efficacy, it was hypothesised that the potent respiratory inhibitor NO would elicit similar effects. Indeed, the current work demonstrates that pre-exposure to NO-releasers elicits a > tenfold increase in IC
50
for gentamicin against pathogenic
E. coli
(i.e. a huge decrease in lethality). It was therefore hypothesised that hyper-sensitivity to NO may have arisen in bacterial pathogens and that this trait could promote the acquisition of antibiotic-resistance mechanisms through enabling cells to persist in the presence of toxic levels of antibiotic. To test this hypothesis, genomics and microbiological approaches were used to screen a collection of
E. coli
clinical isolates for antibiotic susceptibility and NO tolerance, although the data did not support a correlation between increased carriage of antibiotic resistance genes and NO tolerance. However, the current work has important implications for how antibiotic susceptibility might be measured in future (i.e. ± NO) and underlines the evolutionary advantage for bacterial pathogens to maintain tolerance to toxic levels of NO.
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