161 research outputs found
Effect of microplastic on the gills of the Shore Crab Carcinus maenas
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or consequences arising from the use of information contained in these âJust Acceptedâ manuscripts.Microscopic plastic debris (microplastics, <5mm in diameter) is ubiquitous in the marine environment. Previous work has shown that microplastics may be ingested and inhaled by the shore crab Carcinus maenas although the biological consequences are unknown. Here, we show that acute aqueous exposure to polystyrene microspheres (8ÎŒm) with different surface coatings had significant but transient effects on branchial function. Microspheres inhaled into the gill chamber had a small but significant dose dependent effect on oxygen consumption after 1 hour of exposure, returning to normal levels after 16 h. Ion exchange was also affected, with a small but significant decrease in hemolymph sodium ions and an increase in calcium ions after 24 h post exposure. To further asses the effects on osmoregulation, crabs were challenged with reduced salinity after microplastic exposure. Neither microspheres nor natural sediments altered the crabâs response to osmotic stress, regardless of plastic concentration added. Carboxylated (COOH) and aminated (NH2) polystyrene microspheres were distributed differently across the gill surface, although neither had a significant adverse impact on gill function. These results illustrate the extent of the physiological effects of microplastics, compared to the physiological resilience of shore crabs in maintaining osmoregulatory and respiratory function after acute exposure to both anthropogenic plastics and natural particles.W, CL and TG acknowledge funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 308370. The contents of this publication are the responsibility of the CleanSea project and can in no way be taken to reflect the views of the European Union. TG and CL acknowledge additional support from NERC NE/L007010/1
A comparative analysis of the UV/Vis absorption spectra of nitrobenzaldehydes.
In a joint experimental and theoretical study, the UV/Vis absorption spectra of the three isomers (ortho, meta, para) of nitrobenzaldehyde (NBA) were analyzed. Absorption spectra are reported for NBA vapors, cyclohexane and acetonitrile solutions. All spectra are poor in vibronic structure and hardly affected in shape by the surroundings (vapor or solution). Moderate solvatochromic shifts of [similar]â0.2 eV are measured. For all isomers vertical transition energies, oscillator strengths, and excited state dipole moments were computed using the MS-CASPT2/CASSCF and CC2 methods. Based on these calculations the experimental transitions were assigned. The spectra of all isomers are characterized by weak (Δmax â 100 Mâ1 cmâ1) transitions around 350 nm (3.6 eV), arising from nÏ* absorptions starting from the lone pairs of the nitro and aldehyde moieties. The next band of intermediate intensity peaking around 300 nm (4.2 eV, Δmax â 1000 Mâ1 cmâ1) is dominated by ÏÏ* excitations within the arene function. Finally, strong absorptions (Δmax â 10 000 Mâ1 cmâ1) were observed around 250 nm (5.0 eV) which we ascribe to ÏÏ* excitations involving the nitro and benzene groups
Recent ecological change in ancient lakes
Ancient lakes are among the best archivists of past environmental change, having experienced more than one full glacial cycle, a wide range of climatic conditions, tectonic events, and long association with human settlements. These lakes not only record long histories of environmental variation and human activity in their sediments, but also harbor very high levels of biodiversity and endemism. Yet, ancient lakes are faced with a familiar suite of anthropogenic threats, which may degrade the unusual properties that make them especially valuable to science and society. In all ancient lakes for which data exist, significant warming of surface waters has occurred, with a broad range of consequences. Eutrophication threatens both native species assemblages and regional economies reliant on clean surface water, fisheries, and tourism. Where sewage contributes nutrients and heavy metals, one can anticipate the occurrence of less understood emerging contaminants, such as pharmaceuticals, personal care products, and microplastics that negatively affect lake biota and water quality. Human populations continue to increase in most of the ancient lakes' watersheds, which will exacerbate these concerns. Further, human alterations of hydrology, including those produced through climate change, have altered lake levels. Co-occurring with these impacts have been intentional and unintentional species introductions, altering biodiversity. Given that the distinctive character of each ancient lake is strongly linked to age, there may be few options to remediate losses of species or other ecosystem damage associated with modern ecological change, heightening the imperative for understanding these systems
Zebrafish Numb and Numblike Are Involved in Primitive Erythrocyte Differentiation
BACKGROUND:Notch signaling is an evolutionarily conserved regulatory circuitry implicated in cell fate determination in various developmental processes including hematopoietic stem cell self-renewal and differentiation of blood lineages. Known endogenous inhibitors of Notch activity are Numb-Nb and Numblike-Nbl, which play partially redundant functions in specifying and maintaining neuronal differentiation. Nb and Nbl are expressed in most tissues including embryonic and adult hematopoietic tissues in mice and humans, suggesting possible roles for these proteins in hematopoiesis. METHODOLOGY AND PRINCIPAL FINDINGS:We employed zebrafish to investigate the possible functional role of Numb and Numblike during hematopoiesis, as this system allows a detailed analysis even in embryos with severe defects that would be lethal in other organisms. Here we describe that nb/nbl knockdown results in severe reduction or absence of embryonic erythrocytes in zebrafish. Interestingly, nb/nbl knocked-down embryos present severe downregulation of the erythroid transcription factor gata1. This results in erythroblasts which fail to mature and undergo apoptosis. Our results indicate that Notch activity is increased in embryos injected with nb/nbl morpholino, and we show that inhibition of Notch activation can partially rescue the hematopoietic phenotype. CONCLUSIONS AND SIGNIFICANCE:Our results provide the first in vivo evidence of an involvement of Numb and Numblike in zebrafish erythroid differentiation during primitive hematopoiesis. Furthermore, we found that, at least in part, the nb/nbl morphant phenotype is due to enhanced Notch activation within hematopoietic districts, which in turn results in primitive erythroid differentiation defects
The same but different: Understanding entrepreneurial behaviour in disadvantaged communities
While entrepreneurship is widely viewed as being equally accessible in all contexts, it could be questioned if potential or nascent entrepreneurs from minority and disadvantaged communities experience entrepreneurship in a similar manner to the mainstream population. This chapter examines immigrant, people with disability, youth, gay and unemployed communities to explore how their entrepreneurial behaviour might differ from the practices of mainstream entrepreneurs. What emerges is that marginalised communities can frequently find it difficult to divorce business from social living. This can have both positive and negative connotations for an entrepreneur, plus they face additional and distinctive challenges that mainstream entrepreneurs do not experience. The chapter concludes by proposing a novel âfunnel approachâ that policymakers might adopt when seeking to introduce initiatives targeted at these disadvantaged communities
A Complete Pathway Model for Lipid A Biosynthesis in Escherichia coli.
Lipid A is a highly conserved component of lipopolysaccharide (LPS), itself a major component of the outer membrane of Gram-negative bacteria. Lipid A is essential to cells and elicits a strong immune response from humans and other animals. We developed a quantitative model of the nine enzyme-catalyzed steps of Escherichia coli lipid A biosynthesis, drawing parameters from the experimental literature. This model accounts for biosynthesis regulation, which occurs through regulated degradation of the LpxC and WaaA (also called KdtA) enzymes. The LpxC degradation signal appears to arise from the lipid A disaccharide concentration, which we deduced from prior results, model results, and new LpxK overexpression results. The model agrees reasonably well with many experimental findings, including the lipid A production rate, the behaviors of mutants with defective LpxA enzymes, correlations between LpxC half-lives and cell generation times, and the effects of LpxK overexpression on LpxC concentrations. Its predictions also differ from some experimental results, which suggest modifications to the current understanding of the lipid A pathway, such as the possibility that LpxD can replace LpxA and that there may be metabolic channeling between LpxH and LpxB. The model shows that WaaA regulation may serve to regulate the lipid A production rate when the 3-deoxy-D-manno-oct-2-ulosonic acid (KDO) concentration is low and/or to control the number of KDO residues that get attached to lipid A. Computation of flux control coefficients showed that LpxC is the rate-limiting enzyme if pathway regulation is ignored, but that LpxK is the rate-limiting enzyme if pathway regulation is present, as it is in real cells. Control also shifts to other enzymes if the pathway substrate concentrations are not in excess. Based on these results, we suggest that LpxK may be a much better drug target than LpxC, which has been pursued most often
âASMRâ autobiographies and the (life-)writing of digital subjectivity
For years now, a growing online subculture has been exchanging videos designed to induce âautonomous sensory meridian responseâ (ASMR), a mysterious, blissfully relaxing tingling sensation held to alleviate anxiety, pain, insomnia and depression. Emerging from online health forums, ASMR culture today centres on YouTube, where âASMRtistsâ have used the feedback mechanisms built into social media platforms to refine a repertoire of âtriggerâ techniques. Exemplifying a wider trend for using âambient mediaâ as mood modulators and task facilitators (Roquet, 2016 Ambient Media: Japanese Atmospheres of Self. London: University of Minnesota Press.), ASMR cultureâs use of the word âtriggerâ is telling, gesturing towards what Halberstam ((2014) You Are Triggering Me! The Neo-Liberal Rhetoric of Harm, Danger and Trauma. Bully Bloggers. Available at: https://bullybloggers.wordpress.com/2014/07/05/you-are-triggering-me-the-neo-liberal-rhetoric-of-harm-danger-and-trauma/ (accessed 8 August 2018)) sees as a shift away from the Freudian notion of âmemory as a palimpsestâ towards one of memory as âa live wire sitting in the psyche waiting for a sparkâ, whereby digital subjects become black-boxed nodes in a cybernetic circuit. This shift has serious implications for the humanities and is particularly resonant for scholars of life-writing. As McNeill ((2012) There is no âIâ in network: Social networks sites and posthuman auto/biography. Biography 35(1): 65â82.) argues, digital technologies âcomplicate[] definitions of the self and its boundaries, both dismantling and sustaining the humanist subject in practices of personal narrativeâ (p. 65). The resulting friction is highlighted in âASMR autobiographiesâ: texts narrating the authorâs experiences of ASMR and their discovery of online ASMR communities. Echoing familiar auto/biographical forms, from medical case histories and coming out narratives to tales of religious conversion, these texts show that the models of subjectivity we have inherited from Enlightenment philosophy, religion, psychology and Romantic literature retain some cultural purchase. But they also suggest digital media are fostering new understandings of personhood informed by cybernetics, evolutionary psychology, behaviourism and neuroscience. Focusing on works by Andrew MacMuiris, Andrea Seigel and Jon Kersey while also addressing a range of other texts, this article asks what ASMR autobiographies can tell us about digital subjectivity
Metabolic Rift or Metabolic Shift? Dialectics, Nature, and the World-Historical Method
Abstract In the flowering of Red-Green Thought over the past two decades, metabolic rift thinking is surely one of its most colorful varieties. The metabolic rift has captured the imagination of critical environmental scholars, becoming a shorthand for capitalismâs troubled relations in the web of life. This article pursues an entwined critique and reconstruction: of metabolic rift thinking and the possibilities for a post-Cartesian perspective on historical change, the world-ecology conversation. Far from dismissing metabolic rift thinking, my intention is to affirm its dialectical core. At stake is not merely the mode of explanation within environmental sociology. The impasse of metabolic rift thinking is suggestive of wider problems across the environmental social sciences, now confronted by a double challenge. One of course is the widespreadâand reasonableâsense of urgency to evolve modes of thought appropriate to an era of deepening biospheric instability. The second is the widely recognizedâbut inadequately internalizedâunderstanding that humans are part of nature
Isolation, identification and characterization of Paenibacillus polymyxa CR1 with potentials for biopesticide, biofertilization, biomass degradation and biofuel production
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