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1.
Int J Infect Dis ; 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-32004690

RESUMO

BACKGROUND: Middle East Respiratory Syndrome Coronavirus (MERS-CoV) emerged in Saudi Arabia in 2012 and caused an epidemic in the Middle East. Public Health England (PHE) Manchester is one of the two PHE centres in the UK that perform testing for MERS-CoV. The results of the PHE Manchester MERS surveillance from 2012 to 2019 are presented in this report. METHODS: Retrospective data were collected for returning travellers from the Middle East fitting the PHE MERS case definition. Respiratory samples were tested for respiratory viruses and MERS-CoV using an in-house RT-PCR assay. RESULTS: Four hundred and twenty-six (426) samples from 264 patients were tested for MERS Co-V and respiratory viruses. No MERS-CoV infections were identified by PCR. Fifty-six percent of samples were PCR positive for viral or bacterial pathogen with Influenza A as the predominant virus (44%). Sixty-two percent of all patients had a pathogen identified with the highest positivity from sputum samples. Patients with multiple samples demonstrated a 100% diagnostic yield. CONCLUSIONS: Although no cases of MERS were identified, the majority of patients had Influenza infection for which oseltamivir treatment was indicated and isolation warranted. Sputum samples were the most useful in diagnosing respiratory viruses with a 100% diagnostic yield from patients with multiple samples.

2.
Water Res ; 173: 115577, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32044597

RESUMO

There are two means by which metals associate with microplastics in the aquatic environment. Firstly, they may be adsorbed to the plastic surface or hydrogenous-biogenic accumulations thereon, and secondly, they may be present in the polymeric matrix as functional additives or as reaction or recyclate residues. In this study, the relative significance of these associations is evaluated with respect to Pb in beached marine microplastics. Thus, adsorbed Pb was determined in <5 mm, neutrally-coloured polyethylene pellets that contained no detectable Pb added during manufacture by digestion in dilute aqua regia, while the bioaccessibility of this association was evaluated using an avian physiologically-based extraction test (PBET). Here, up to about 0.1 µg g-1 of Pb was adsorbed to the plastic and between about 60 and 70% of the metal was accessible. Lead present as additive or residue was determined by x-ray fluorescence analysis of a wider range of beached plastics (polyolefins and polyvinyl chloride), with a selection of positive samples grated to mm-dimensions and subjected to the PBET. Here, total Pb concentrations up to 40,000 µg g-1 and bioaccessibilities up to 16% were observed, with bioaccessible concentrations exceeding equivalent values for adsorbed Pb by several orders of magnitude. Ingestive exposure to Pb, and potentially other toxic metals, is more important through the presence of additives in historical plastics and recyclate residues in contemporary plastics than from adsorption, and it is recommended that future studies focus more on the environmental impacts and fate of metals bound in this form.

3.
Environ Pollut ; 261: 114107, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32058156

RESUMO

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 âˆ¼ 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.

4.
Sci Total Environ ; 713: 136588, 2020 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-31958724

RESUMO

Concentrations of antimony have been determined for paints and enamels that are available to the consumer or accessible to the public by x-ray fluorescence spectrometry. The metalloid was only present in consumer paints of a speciality (e.g. artistic) nature, but was common in old household paints as an anti-chalking agent and in brightly-coloured contemporary exterior paints (on roads, street furniture and playground equipment, for example) as a colour fastener with concentrations ranging from a few hundred to about 25,000 µg g-1. Antimony was also found in contemporary container glass and ceramic products as an additive or opacifier and as a colour fastener in enamels at concentrations up to a few thousand µg g-1. Overall, the yellow pigment, lead antimonate, was only evident in two ceramic products analysed, with Sb concentrations exceeding 62,800 µg g-1. Available data in the literature suggests that, while Sb concentrations up to 30 µg g-1 are bioaccessible in exterior paints and that concentrations of up to 20 mg L-1 are migratable in some ceramicware, no relevant regulations are currently in place. Given our lack of understanding of the health impacts of Sb, more studies on its toxicity and mobility from commonly encountered products are called for.

5.
Am J Surg ; 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31818425

RESUMO

BACKGROUND: Optimal management for papillary thyroid microcarcinoma (PTMC) remains controversial. The purpose of this study was to explore risk factors predictive of cervical lymph node metastasis in conventional PTMCs. METHODS: Conventional PTMC patients (n = 2,404) undergoing surgery between 2010 and 2017 were grouped and analyzed according to the positivity of cervical lymph node. RESULTS: Central lymph node (CLN) metastases and lateral lymph node (LLN) metastases were observed in 915 (38.1%) and 184 (7.7%) cases, respectively. Multivariate analysis found that male (odds ratio [OR] = 1.974, p < 0.001), younger age (OR = 1.601, p < 0.001), tumor size (OR = 1.935, p < 0.001), extrathyroidal extension (ETE) (OR = 1.647, p < 0.001), multifocality (OR = 1.416, p < 0.001), and intrathyroidal spreading (OR = 3.355, p < 0.001) predicted increased CLN metastasis. In particular, younger age, multifocality, and intrathyroidal spreading were significantly associated with a high number of CLN metastases (n ≥ 5). The presence of CLN metastasis was strongly associated with LLN metastasis (OR = 5.426, p < 0.001). CONCLUSION: Male, younger age, tumor size, ETE, multifocality, and intrathyroidal spreading predict increased CLN metastasis in PTMCs. In patients with suspicious lateral lymphadenopathy, the presence of CLN metastasis is independently associated with LLN metastasis.

6.
Proc Biol Sci ; 286(1917): 20191777, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31847763

RESUMO

The impacts of parasites on hosts and the role that parasites play in ecosystems must be underlain by the load of parasites in individual hosts. To help explain and predict parasite load across a broad range of species, quantitative theory has been developed based on fundamental relationships between organism size, temperature and metabolic rate. Here, we elaborate on an aspect of that 'scaling theory for parasitism', and test a previously unexplored prediction, using new data for total ectoparasite load from 263 wild birds of 42 species. We reveal that, despite the expected substantial variation in parasite load among individual hosts, (i) the theory successfully predicts the distinct increase of ectoparasite load with host body size, indicating the importance of geometric scaling constraints on access to host resources, (ii) ectoparasite load appears ultimately limited by access-not to host space-but to host energy, and (iii) there is a currency-dependent shift in taxonomic dominance of parasite load on larger birds. Hence, these results reveal a seemingly new macroecological pattern, underscore the utility of energy flux as a currency for parasitism and highlight the promise of using scaling theory to provide baseline expectations for parasite load for a diversity of host species.

8.
Sci Total Environ ; 694: 133644, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31756839

RESUMO

Black consumer plastics are often contaminated with hazardous chemicals because of technological constraints on sorting dark plastic during recycling of municipal waste coupled with the convenience of waste electrical and electronic equipment (WEEE) as a secondary source of black plastic. In this study, samples of beached plastic litter (n = 524) from southwest England were categorised according to origin, appearance and colour (black versus non-black) before being analysed by x-ray fluorescence (XRF) spectrometry for elements that are characteristic of EEE. The small number of items of WEEE retrieved (n = 36) were largely restricted to wiring insulation and constructed of lead-stabilised polyvinyl chloride (PVC). Among the remaining samples, Br, Cd, Cr and Pb were commonly detected in all categories of black plastics (n = 264) with maximum concentrations of 43,400 mg kg-1, 2080 mg kg-1, 662 mg kg-1 and 23,800 mg kg-1, respectively. Moreover, concentrations of Br were significantly correlated with concentrations of the flame retardant synergist, Sb (n = 22), and 35 samples were potentially non-compliant with regard to limits defined by the Restriction of Hazardous Substances Directive. For plastics of other colours (n = 224), Br and Pb were detected in fewer samples and Br was co-associated with Sb in only two cases, with occasional high concentrations Cd, Cr and Pb largely attributed to the historical use of cadmium sulphide and lead chromate pigments. An avian physiologically-based extraction test applied to selected samples cut to mm-dimensions revealed bioaccessibilities ranging from <0.1% for Cr in a green fragment to about 2.4% (or about 580 mg kg-1) for Pb in black PVC. The recycling of WEEE into consumer, industrial and marine (e.g. fishing) plastics that are mainly coloured black appears to be an important vehicle for the introduction of hazardous chemicals into the environment and a source of their exposure to wildlife.

9.
J AOAC Int ; 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31645237

RESUMO

Background: An ultrahigh-performance LC (UHPLC)-tandem MS (MS/MS) method for determination of paralytic shellfish poisoning toxins and tetrodotoxin (TTX) in bivalve molluscs was developed. To be used for regulatory testing, it needed to be validated through collaborative study. Objective: The aim was to conduct a collaborative study with 21 laboratories, using results to assess method performance. Methods: Study materials incorporated shellfish species mussels, oysters, cockles, scallops, and clams and were assessed to demonstrate stability and homogeneity. Mean concentrations determined by participants for blind duplicate samples were used to assess reproducibility, repeatability, and trueness. Results: Method performance characteristics were excellent following statistical assessment of participant data, with method trueness showing excellent method accuracy against expected values. No significant difference was found in the trueness results determined by different chromatographic column types. Acceptability of the between-laboratory reproducibility for individual analytes was evidenced by >99% of valid Horwitz ratio values being less than the 2.0 limit of acceptability. With excellent linearity and sensitivity fit-for-purpose over a range of mass spectrometer instruments, the UHPLC-MS/MS method compared well against other detection methods. It includes additional paralytic shellfish toxin (PST) analogues as well as TTX, which, to date, have not been incorporated into any other hydrophilic marine toxin official method of analysis. Conclusions: The results from this study demonstrate that the method is suitable for the analysis of PST analogues and TTX in shellfish tissues and is recommended as an official alternative method of analysis for regulatory control. Highlights: A new mass spectrometric method for PST and TTX has been validated successfully through collaborative study.

10.
Euro Surveill ; 24(35)2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31481146

RESUMO

We report on six cases of diarrhetic shellfish poisoning following consumption of mussels harvested in the United Kingdom. Dinophysis spp. in the water column was found to have increased rapidly at the production site resulting in high levels of okadaic acid-group lipophilic toxins in the flesh of consumed mussels. Clinicians and public health professionals should remain aware of algal-derived toxins being a potential cause of illness following seafood consumption.

11.
Sci Total Environ ; 694: 133610, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31398639

RESUMO

Items of marine plastic litter are conventionally classified as primary or secondary, depending on whether they are distinct objects or angular fragments, respectively. "Pyroplastic" is an additional type of plastic litter that is described here, based on observations made on beached samples from south west England. Pyroplastics are derived from the informal or more organised burning of manufactured plastics and may be angular "plastiglomerates", comprising pieces of plastic debris within a matrix, or rounded plastic "pebbles", where agglomerated material has been weathered and smoothed into more brittle and neutrally-coloured geogenic-looking clasts. Beached pyroplastics are usually positively buoyant because of a polyethylene or polypropylene matrix, and exhibit a bimodal mass distribution attributed to the breakage of larger clasts (>20 mm) into smaller fragments (<5 mm). XRF analysis reveals variable quantities of Pb in the matrix (up to 7500 µg g-1), often in the presence of Cr, implying that material in many samples pre-dates restrictions on the use of lead chromate. Low concentrations of Br and Sb relative to pieces of manufactured plastics in the marine environment suggest that pyroplastics are not directly or indirectly derived from electronic plastic. Calcareous worm tubes on the surfaces of pyroplastics dense enough to be temporarily submerged in the circalittoral zone are enriched in Pb, suggesting that constituents within the matrix are partly bioavailable. Evading ready detection due to their striking visual similarity to geogenic material, pyroplastics may contribute to an underestimation of the stock of beached plastics in many cases.

12.
Toxins (Basel) ; 11(8)2019 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-31404969

RESUMO

Bivalve molluscs represent an important food source within the Philippines, but the health of seafood consumers is compromised through the accumulation of harmful algal toxins in edible shellfish tissues. In order to assess the dynamics of toxin risk in shellfish, this study investigated the uptake, depuration, assimilation, and analogue changes of paralytic shellfish toxins in Perna viridis. Tank experiments were conducted where mussels were fed with the toxic dinoflagellate Alexandrium minutum. Water and shellfish were sampled over a six day period to determine toxin concentrations in the shellfish meat and water, as well as algal cell densities. The maximum summed toxin concentration determined was 367 µg STX eq./100 g shellfish tissue, more than six times higher than the regulatory action limit in the Philippines. Several uptake and depuration cycles were observed during the study, with the first observed within the first 24 h coinciding with high algal cell densities. Toxin burdens were assessed within different parts of the shellfish tissue, with the highest levels quantified in the mantle during the first 18 h period but shifting towards the gut thereafter. A comparison of toxin profile data evidenced the conversion of GTX1,4 in the source algae to the less potent GTX2,3 in the shellfish tissue. Overall, the study illustrated the temporal variability in Perna viridis toxin concentrations during a modelled algal bloom event, and the accumulation of toxin from the water even after toxic algae were removed.

13.
Sci Adv ; 5(8): eaaw4307, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31457085

RESUMO

For decades, the source of phosphorus incorporated into Earth's first organisms has remained a fundamental, unsolved puzzle. Although contemporary biomolecules incorporate P(+V) in their phosphate moieties, the limited bioavailability of phosphates led to the proposal that more soluble P(+III) compounds served as the initial source of phosphorus. Here, we report via laboratory simulation experiments that the three simplest alkylphosphonic acids, soluble organic phosphorus P(+III) compounds, can be efficiently generated in interstellar, phosphine-doped ices through interaction with galactic cosmic rays. This discovery opens a previously overlooked avenue into the formation of key molecules of astrobiological significance and untangles basic mechanisms of a facile synthesis of phosphorus-containing organics in extraterrestrial ices, which can be incorporated into comets and asteroids before their delivery and detection on Earth such as in the Murchison meteorite.

14.
Mar Pollut Bull ; 146: 940-944, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31426241

RESUMO

Cadmium has had a number of historical applications in plastics but is now highly regulated. In this study, plastics containing pigmented or recycled Cd at concentrations up to 16,300 µg g-1 were processed into microplastic-sized fragments and added to clean estuarine sediment. Plastic-sediment mixtures (mass ratio = 1:100) were subsequently exposed to fluids simulating the digestive conditions encountered in marine deposit-feeding invertebrates prepared from a protein and a bile acid surfactant in seawater and the mobilization of Cd measured as a function of time. Kinetic profiles over a six-hour period were complex, with some fitted using a diffusion model and others exhibiting evidence of Cd interactions between the plastic and sediment surface. The maximum concentration of Cd released from plastic-sediment mixtures was about 0.8 µg g-1 and orders of magnitude greater than Cd mobilization from sediment alone. It is predicted that large communities of deposit-feeders could mobilize significant quantities of Cd from historical microplastics.


Assuntos
Cádmio/química , Cádmio/metabolismo , Sedimentos Geológicos/química , Plásticos/química , Água do Mar/química , Poluentes Químicos da Água/química , Organismos Aquáticos/metabolismo , Cádmio/análise , Cinética , Plásticos/análise , Plásticos/metabolismo , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
15.
Harmful Algae ; 87: 101623, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31349885

RESUMO

As the official control laboratory for marine biotoxins within Great Britain, the Centre for Environment, Fisheries and Aquaculture Science, in conjunction with the Scottish Association for Marine Science, has amassed a decade's worth of data regarding the prevalence of the toxins associated with Amnesic Shellfish Poisoning within British waters. This monitoring involves quantitative HPLC-UV analysis of shellfish domoic acid concentration, the causative toxin for Amnesic Shellfish Poisoning, and water monitoring for Pseudo-nitzschia spp., the phytoplankton genus that produces domoic acid. The data obtained since 2008 indicate that whilst the occurrence of domoic acid in shellfish was generally below the maximum permitted limit of 20 mg/kg, there were a number of toxic episodes that breached this limit. The data showed an increase in the frequency of both domoic acid occurrence and toxic events, although there was considerable annual variability in intensity and geographical location of toxic episodes. A particularly notable increase in domoic acid occurrence in England was observed during 2014. Comparison of Scottish toxin data and Pseudo-nitzschia cell densities during this ten-year period revealed a complex relationship between the two measurements. Whilst the majority of events were associated with blooms, absolute cell densities of Pseudo-nitzschia did not correlate with domoic acid concentrations in shellfish tissue. This is believed to be partly due to the presence of a number of different Pseudo-nitzschia species in the water that can exhibit variable toxin production. These data highlight the requirement for tissue monitoring as part of an effective monitoring programme to protect the consumer, as well as the benefit of more detailed taxonomic discrimination of the Pseudo-nitzschia genus to allow greater accuracy in the prediction of shellfish toxicity.

16.
Harmful Algae ; 87: 101629, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31349886

RESUMO

Cefas has been responsible for the delivery of official control biotoxin testing of bivalve molluscs from Great Britain for just over a decade. Liquid chromatography tandem mass spectrometric (LC-MS/MS) methodology has been used for the quantitation of lipophilic toxins (LTs) since 2011. The temporal and spatial distribution of okadaic acid group toxins and profiles in bivalves between 2011 and 2016 have been recently reported. Here we present data on the two other groups of regulated lipophilic toxins, azaspiracids (AZAs) and yessotoxins (YTXs), over the same period. The latter group has also been investigated for a potential link with Protoceratium reticulatum and Lingulodinium polyedra, both previously recognised as YTXs producing phytoplankton. On average, AZAs were quantified in 3.2% of all tested samples but notable inter-annual variation in abundance was observed. The majority of all AZA contaminated samples were found between July 2011 and August 2013 in Scotland, while only two, three-month long, AZA events were observed in 2015 and 2016 in the south-west of England. Maximum concentrations were generally reached in late summer or early autumn. Reasons for AZAs persistence during the 2011/2012 and 2012/2013 winters are discussed. Only one toxin profile was identified, represented by both AZA1 and AZA2 toxins at an approximate ratio of 2 : 1, suggesting a single microalgal species was the source of AZAs in British bivalves. Although AZA1 was always the most dominant toxin, its proportion varied between mussels, Pacific oysters and surf clams. The YTXs were the least represented group among regulated LTs. YTXs were found almost exclusively on the south-west coast of Scotland, with the exception of 2013, when the majority of contaminated samples originated from the Shetland Islands. The highest levels were recorded in the summer months and followed a spike in Protoceratium reticulatum cell densities. YTX was the most dominant toxin in shellfish, further strengthening the link to P. reticulatum as the YTX source. Neither homo-YTX, nor 45-OH homo-YTX were detected throughout the monitored period. 45-OH YTX, thought to be a shellfish metabolite associated with YTX elimination, contributed on average 26% in mussels. Although the correlation between 45-OH YTX abundance and the speed of YTX depuration could not be confirmed, we noted the half-life of YTX was more than two-times longer in queen scallops, which contained 100% YTX, than in mussels. No other bivalve species were affected by YTXs. This is the first detailed evaluation of AZAs and YTXs occurrences and their profiles in shellfish from Great Britain over a period of multiple years.

17.
Environ Sci Technol ; 53(14): 8398-8404, 2019 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-31185163

RESUMO

The glass and enameled decorations of bottles of alcoholic beverages sourced from retailers in the U.K. were analyzed by X-ray fluorescence spectrometry for various heavy metals. In the glass substrate, lead, cadmium, and chromium were present at concentrations up to about 1100, 1100, and 3000 µg g-1, respectively, but their environmental and health risks are deemed to be low significance. Of more concern from an environmental and, potentially, occupational exposure perspective are the concentrations and mobilities of Pb and Cd in the enamels of many bottles. Thus, Pb concentrations up to about 100000 µg g-1 were found on the décor of various wine bottles and a beer bottle, and Cd concentrations of up to 20000 µg g-1 were measured in the decorated regions on a range of spirits, beer, and wine bottles. Moreover, maximum concentrations that leached from enameled glass fragments according to a standard test that simulates water and other liquids percolating through a landfill were about 1200 and 3200 µg L-1 for Pb and Cd, respectively, with several fragments exceeding the U.S. Model Toxins in Packaging Legislation and, therefore, defined as "hazardous". Given that safer decorative alternatives are available and that a precautionary principle should be adopted for toxic heavy metals, the pervasive use of Pb and Cd in the enamels of consumer bottles is brought into question.


Assuntos
Metais Pesados , Cádmio , Cromo , Monitoramento Ambiental , Vidro , Intoxicação por Metais Pesados , Humanos
18.
Perspect Biol Med ; 62(1): 41-71, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31031297

RESUMO

Originating within astronomy as a technical term in the first half of the 18th century, the term "personal equation" spread into a litany of other fields including medicine, where it was used widely and variously from the late 19th century to the middle of the 20th century. We explore the personal equation in the medical literatures of the United States and Britain through a systematic analysis of over 700 articles in four prominent medical journals in conjunction with additional relevant source materials. After tracing the term's dispersion from astronomy into medically allied fields, we examine its striking polysemy while using its rich usage as a lens to examine prevailing tensions within contemporary American and British medicine. Stretching from patient and clinician variability to observer variability and error, the personal equation's various meanings reflect debates about the art and science of medical care that persist into the present day.


Assuntos
História da Medicina , Terminologia como Assunto , Astronomia , Inglaterra , História do Século XIX , História do Século XX , Humanos , Médicos , Estados Unidos
19.
Front Physiol ; 10: 373, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31019470

RESUMO

Research on the effects of climate change in the marine environment continues to accelerate, yet we know little about the effects of multiple climate drivers in more complex, ecologically relevant settings - especially in sub-tropical and tropical systems. In marine ecosystems, climate change (warming and freshening from land run-off) will increase water column stratification which is favorable for toxin producing dinoflagellates. This can increase the prevalence of toxic microalgal species, leading to bioaccumulation of toxins by filter feeders, such as bivalves, with resultant negative impacts on physiological performance. In this study we manipulated multiple climate drivers (warming, freshening, and acidification), and the availability of toxic microalgae, to determine their impact on the physiological health, and toxin load of the tropical filter-feeding clam, Meretrix meretrix. Using a structural equation modeling (SEM) approach, we found that exposure to projected marine climates resulted in direct negative effects on metabolic and immunological function and, that these effects were often more pronounced in clams exposed to multiple, rather than single climate drivers. Furthermore, our study showed that these physiological responses were modified by indirect effects mediated through the food chain. Specifically, we found that when bivalves were fed with a toxin-producing dinoflagellate (Alexandrium minutum) the physiological responses, and toxin load changed differently and in a non-predictable way compared to clams exposed to projected marine climates only. Specifically, oxygen consumption data revealed that these clams did not respond physiologically to climate warming or the combined effects of warming, freshening and acidification. Our results highlight the importance of quantifying both direct and, indirect food chain effects of climate drivers on a key tropical food species, and have important implications for shellfish production and food safety in tropical regions.

20.
Nat Chem Biol ; 15(5): 463-471, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30936502

RESUMO

Cell wall glycopolymers on the surface of Gram-positive bacteria are fundamental to bacterial physiology and infection biology. Here we identify gacH, a gene in the Streptococcus pyogenes group A carbohydrate (GAC) biosynthetic cluster, in two independent transposon library screens for its ability to confer resistance to zinc and susceptibility to the bactericidal enzyme human group IIA-secreted phospholipase A2. Subsequent structural and phylogenetic analysis of the GacH extracellular domain revealed that GacH represents an alternative class of glycerol phosphate transferase. We detected the presence of glycerol phosphate in the GAC, as well as the serotype c carbohydrate from Streptococcus mutans, which depended on the presence of the respective gacH homologs. Finally, nuclear magnetic resonance analysis of GAC confirmed that glycerol phosphate is attached to approximately 25% of the GAC N-acetylglucosamine side-chains at the C6 hydroxyl group. This previously unrecognized structural modification impacts host-pathogen interaction and has implications for vaccine design.


Assuntos
Glicerol/metabolismo , Fosfatos/metabolismo , Polissacarídeos Bacterianos/metabolismo , Streptococcus/metabolismo , Glicerol/química , Fosfatos/química , Polissacarídeos Bacterianos/química , Streptococcus/química
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