Emerging Topics in Life Sciences最新文献

Both the neuropsychiatric syndrome of apathy and major depressive disorder comprise a heterogenous cluster of symptoms which span multiple behavioural domains. Despite this heterogeneity, there is a tendency in the preclinical literature to conclude a MDD or apathy-like phenotype from a single dimensional behavioural task used in isolation, which may lead to inaccurate phenotypic interpretation. This is significant, as apathy and major depressive disorder are clinically distinct with different underlying mechanisms and treatment approaches. At the clinical level, apathy and major depressive disorder can be dissociated in the negative valence (loss) domain of the Research Domain Criteria. Symptoms of MDD in the negative valence (loss) domain can include an exaggerated response to emotionally salient stimuli and low mood, while in contrast apathy is characterised by an emotionally blunted state. In this article, we highlight how using a single dimensional approach can limit psychiatric model interpretation. We discuss how integrating behavioural findings from both the positive and negative (loss) valence domains of the Research Domain Criteria can benefit interpretation of findings. We focus particularly on behaviours relating to the negative valence (loss) domain, which may be used to distinguish between apathy and major depressive disorder at the preclinical level. Finally, we consider how future approaches using home cage monitoring may offer a new opportunity to detect distinct behavioural profiles and benefit the overall translatability of findings.

Models of episodic memory are successfully established using spontaneous object recognition tasks in rodents. In this review, we present behavioral techniques devised to investigate this type of memory, emphasizing methods based on associations of places and temporal order of items explored by rats and mice. We also provide a review on the areas and circuitry of the medial temporal lobe underlying episodic-like memory, considering that a large number of neurobiology data derived from these protocols. Although spontaneous recognition tasks are commonplace in this field, there is need for careful evaluation of factors affecting animal performance. Such as the ongoing development of tools for investigating the neural basis of memory, efforts should be put in the refinement of experimental designs, in order to provide reliable behavioral evidence of this complex mnemonic system.

Microplastics are small (<5 mm) plastic particles of varying shapes and polymer types that are now widespread global contaminants of marine and freshwater ecosystems. Various estimates suggest that several trillions of microplastic particles are present in our global oceanic system, and that these are readily ingested by a wide range of marine and freshwater species across feeding modes and ecological niches. Here, we present some of the key and pressing issues associated with these globally important contaminants from a microbiological perspective. We discuss the potential mechanisms of pathogen attachment to plastic surfaces. We then describe the ability of pathogens (both human and animal) to form biofilms on microplastics, as well as dispersal of these bacteria, which might lead to their uptake into aquatic species ingesting microplastic particles. Finally, we discuss the role of a changing oceanic system on the potential of microplastic-associated pathogens to cause various disease outcomes using numerous case studies. We set out some key and imperative research questions regarding this globally important issue and present a methodological framework to study how and why plastic-associated pathogens should be addressed.

To date, much effort has been placed on quantifying plastic pollution and understanding its negative environmental effects, arguably to the detriment of research and evaluation of potential interventions. This has led to piecemeal progress in interventions to reduce plastic pollution, which do not correspond to the pace of emissions. For substances that are used on a global scale and identified as hazardous, there is a need to act before irreversible damage is done. For example, the history of dichlorodiphenyltrichloethane's (DDT) use has demonstrated that legacy chemicals with properties of persistence can still be found in the environment despite being first prohibited 50 years ago. Despite the growing evidence of harm, evidence to inform actions to abate plastic pollution lag behind. In part, this is because of the multifaceted nature of plastic pollution and understanding the connections between social, economic and environmental dimensions are complex. As such we highlight the utility of integrative systems approaches for addressing such complex issues, which unites a diversity of stakeholders (including policy, industry, academia and society), and provides a framework to identify to develop specific, measurable and time-bound international policies on plastic pollution and meet the ambitious yet necessary goals of the UN Plastic Treaty.

Biodegradable plastics have been proposed as a potential solution to plastic pollution, as they can be biodegraded into their elemental components by microbial action. However, the degradation rate of biodegradable plastics is highly variable across environments, leading to the potential for accumulation of plastic particles, chemical co-contaminants and/or degradation products. This paper reviews the toxicological effects of biodegradable plastics on species and ecosystems, and contextualises these impacts with those previously reported for conventional polymers. While the impacts of biodegradable plastics and their co-contaminants across levels of biological organisation are poorly researched compared with conventional plastics, evidence suggests that individual-level effects could be broadly similar. Where differences in the associated toxicity may arise is due to the chemical structure of biodegradable polymers which should facilitate enzymatic depolymerisation and the utilisation of the polymer carbon by the microbial community. The input of carbon can alter microbial composition, causing an enrichment of carbon-degrading bacteria and fungi, which can have wider implications for carbon and nitrogen dynamics. Furthermore, there is the potential for toxic degradation products to form during biodegradation, however understanding the environmental concentration and effects of degradation products are lacking. As global production of biodegradable polymers continues to increase, further evaluation of their ecotoxicological effects on organisms and ecosystem function are required.

Microplastics (MPs, <5 mm in size) are a grave environmental concern. They are a ubiquitous persistent pollutant group that has reached into all parts of the environment - from the highest mountain tops to the depths of the ocean. During their production, plastics have added to them numerous chemicals in the form of plasticizers, colorants, fillers and stabilizers, some of which have known toxicity to biota. When released into the environments, MPs are also likely to encounter chemical contaminants, including hydrophobic organic contaminants, trace metals and pharmaceuticals, which can sorb to plastic surfaces. Additionally, MPs have been shown to be ingested by a wide range of organisms and it is this combination of ingestion and chemical association that gives weight to the notion that MPs may impact the bioavailability and toxicity of both endogenous and exogenous co-contaminants. In this mini-review, we set the recent literature within what has been previously published about MPs as chemical carriers to biota, with particular focus on aquatic invertebrates and fish. We then present a critical viewpoint on the validity of laboratory-to-field extrapolations in this area. Lastly, we highlight the expanding 'microplastic universe' with the addition of anthropogenic particles that have gained recent attention, namely, tire wear particles, nanoplastics and, bio-based or biodegradable MPs, and highlight the need for future research in their potential roles as vehicles of co-contaminant transfer.

Plastics are incredibly versatile materials that can bring diverse societal and environmental benefit, yet current practices of production, use and disposal have negative effects on wildlife, the environment and human health leading to growing concern across public, policy makers and industry. This Special Issue in Emerging Topics in Life Sciences describes recent advances in our understanding of the consequences of plastic pollution. In particular, it examines their potential to act as vectors for chemicals and pathogens in the environment; evaluates the effects of plastic pollution on biogeochemical cycling, ecosystem functioning and highlights the potential for enhanced effects in environments that are already subject to substantive changes in their climate. The impacts plastics pose to terrestrial ecosystems including soil communities are described and evaluated, along with evidence of potential issues for human health. With an increase in the production of plastics labelled as 'biodegradable' their context and ecological impacts are reviewed. Finally, we discuss the need to take an integrative, system approach when developing and evaluating solutions to plastic pollution, to achieve the ambitious yet necessary aims of the UN Plastics Treaty.

Micro and nanosize plastic polymers degrading from large plastic compounds are accumulating in the natural environment and expose potential biological threats to human health. These particles are largely persistent and consequently accumulate in the exposed individuals. The presence of microplastics has already been demonstrated in various human organs including the lung, the gastrointestinal system and the blood raising concerns about their possible harmful effects. The chemical composition, size and shape of microplastics as well as their weathering status represent important factors influencing the potential impact of microplastics on tissues. In addition, microplastics can function as vectors for adsorbed chemical compounds and may harbour and deliver live microbial pathogens or their ligands. In vitro and in vivo animal studies demonstrated that microplastics are taken up to cells in a size and cell type dependent manner. Once inside the targeted cell they activate oxidative processes, mitochondrial dysfunction and ER-stress. These molecular processes result in the activation or repression of cell type specific functions and potentially in the induction of cytotoxicity. The microplastic elicited events may result in inflammation, organ damage and fibrosis of the targeted organs as well as in systemic immunological and metabolic conditions. In addition, microplastics may impact on the gut microbiota which may exert further gastrointestinal and systemic metabolic and immunological effects. In this minireview, we evaluate the factors and mechanisms that influence potential microplastic induced cellular and organ pathologies in humans and discuss limitations of current understanding regarding microplastic elicited conditions as well as future perspectives for research.

There is mounting evidence that plastic and microplastic contamination of soils can affect physico-chemical processes and soil fauna, as has been excellently summarised in many recently published meta-analyses and systematic reviews elsewhere. It has become clear that impacts are highly context dependent on, e.g. polymer type, shape, dose and the soil itself. Most published studies are based on experimental approaches using (semi-)controlled laboratory conditions. They typically focus on one or several representative animal species and their behaviour and/or physiological response - for example, earthworms, but rarely on whole communities of animals. Nevertheless, soil animals are rarely found in isolation and form part of intricate foodwebs. Soil faunal biodiversity is complex, and species diversity and interactions within the soil are very challenging to unravel, which may explain why there is still a dearth of information on this. Research needs to focus on soil animals from a holistic viewpoint, moving away from studies on animals in isolation and consider different trophic levels including their interactions. Furthermore, as evidence obtained from laboratory studies is complemented by relatively few studies done in field conditions, more research is needed to fully understand the mechanisms by which plastic pollution affects soil animals under realistic field conditions. However, field-based studies are typically more challenging logistically, requiring relatively large research teams, ideally of an interdisciplinary nature to maintain long-term field experiments. Lastly, with more alternative, (bio)degradable and/or compostable plastics being developed and used, their effects on soil animals will need to be further researched.

Plastic pollution can both chemically and physically impede marine biota. But it can also provide novel substrates for colonization, and its leachate might stimulate phytoplankton growth. Plastic contains carbon, which is released into the environment upon breakdown. All of these mechanisms have been proposed to contribute global impacts on open ocean carbon cycling and climate from ubiquitous plastic pollution. Laboratory studies produce compelling data showing both stimulation and inhibition of primary producers and disruption of predatory lifecycles at individual scale, but global carbon cycle impacts remain mostly unquantified. Preliminary modelling estimates ecosystem alterations and direct carbon release due to plastic pollution will remain vastly less disruptive to global carbon cycling than the direct damage wrought by fossil fuel carbon emissions. But when considered by mass, carbon in the form of bulky, persistent plastic particles may be disproportionally more influential on biogeochemical cycling than carbon as a gas in the atmosphere or as a dissolved component of seawater. Thus, future research should pay particular attention to the optical and other physical effects of marine plastic pollution on Earth system and ecological function, and resulting impacts on oxygen and nutrient cycling. Improved understanding of the breakdown of plastics in the marine environment should also be considered high-priority, as any potential perturbation of biological carbon cycling by plastic pollution is climate-relevant on centennial timescales and longer.