Shells of the bivalve Astarte moerchi give new evidence of a strong pelagic-benthic coupling shift occurring since the late 1970s in the North Water polynya.

Climate changes in the Arctic may weaken the currently tight pelagic-benthic coupling. In response to decreasing sea ice cover, arctic marine systems are expected to shift from a 'sea-ice algae-benthos' to a 'phytoplankton-zooplankton' dominance. We used mollusc shells as bioarchives and fatty acid trophic markers to estimate the effects of the reduction of sea ice cover on the food exported to the seafloor. Bathyal bivalve Astarte moerchi living at 600 m depth in northern Baffin Bay reveals a clear shift in growth variations and Ba/Ca ratios since the late 1970s, which we relate to a change in food availability. Tissue fatty acid compositions show that this species feeds mainly on microalgae exported from the euphotic zone to the seabed. We, therefore, suggest that changes in pelagic-benthic coupling are likely due either to local changes in sea ice dynamics, mediated through bottom-up regulation exerted by sea ice on phytoplankton production, or to a mismatch between phytoplankton bloom and zooplankton grazing due to phenological change. Both possibilities allow a more regular and increased transfer of food to the seabed. This article is part of the theme issue 'The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.

Shell deformity as a marker for retrospective detection of a pathogenic unicellular alga, Coccomyxa sp., in mytilid mussels: A first case study and research agenda.

An L-shaped shell deformity (LSSD) on the posterior shell edge is known exclusively in wild mytilid mussels infected with photosynthetic Coccomyxa-like algae. LSSD forms due to the appearance of extra shell material; it only occurs if the mussel is heavily infected with the alga. Traditionally, observation of high amount of the green spots (algal colonies) on a large area of host soft tissues (most of the mantle and in adductor muscle) has been used to indicate a high infection rate. We examined 300 Mytilus spp. (100 small, 20-30 mm; 200 large, 40-60 mm) with a high degree of LSSD (parameter "d" > 5 mm) from the Lower St. Lawrence Estuary (Québec, Canada). Green spots were absent in two large mussels, and were only present along the mantle posterior edge in 14 large mussels; other individuals had high infection levels. Our observations suggest that some individuals could be in a state of remission, or, even more optimistically - mussels may be able to resist the pathogen. LSSD is the stable through-time marker for detection of mytilid mussels that are or were infected with Coccomyxa algae, and, thus, may provide information for the study of mussel immunity and control of alga distribution/migration in coastal waters worldwide.

Microlayer source of oxygenated volatile organic compounds in the summertime marine Arctic boundary layer.

Summertime Arctic shipboard observations of oxygenated volatile organic compounds (OVOCs) such as organic acids, key precursors of climatically active secondary organic aerosol (SOA), are consistent with a novel source of OVOCs to the marine boundary layer via chemistry at the sea surface microlayer. Although this source has been studied in a laboratory setting, organic acid emissions from the sea surface microlayer have not previously been observed in ambient marine environments. Correlations between measurements of OVOCs, including high levels of formic acid, in the atmosphere (measured by an online high-resolution time-of-flight mass spectrometer) and dissolved organic matter in the ocean point to a marine source for the measured OVOCs. That this source is photomediated is indicated by correlations between the diurnal cycles of the OVOC measurements and solar radiation. In contrast, the OVOCs do not correlate with levels of isoprene, monoterpenes, or dimethyl sulfide. Results from box model calculations are consistent with heterogeneous chemistry as the source of the measured OVOCs. As sea ice retreats and dissolved organic carbon inputs to the Arctic increase, the impact of this source on the summer Arctic atmosphere is likely to increase. Globally, this source should be assessed in other marine environments to quantify its impact on OVOC and SOA burdens in the atmosphere, and ultimately on climate.

First report of signs of infection by Coccomyxa-like algae in wild blue mussels, Mytilus spp., in the Gulf of Maine (USA, Maine).

In August 2019, visual inspection of intertidal zones of the Gulf of Maine (ME, USA) revealed young and adult wild blue mussels, Mytilus spp., in Alley Bay (Jonesport area) with the distinctive L-shaped shell deformity (LSSD) and green spots (GS) in the mantle and adductor muscle. LSSD is a characteristic sign of current or previous mussel infection by photosynthetic unicellular alga from the group Coccomyxa, while GS are algal colonies. Based on these findings, this study represents the first report of infection signs by pathogenic Coccomyxa-like algae in mussels from the coastal waters of the Northeastern United States, providing a base for future large scale monitoring of the alga in the region.

Determination of monomethylmercury and dimethylmercury in the Arctic marine boundary layer.

Our understanding of the biogeochemical cycling of monomethylmercury (MMHg) in the Arctic is incomplete because atmospheric sources and sinks of MMHg are still unclear. We sampled air in the Canadian Arctic marine boundary layer to quantify, for the first time, atmospheric concentrations of methylated Hg species (both MMHg and dimethylmercury (DMHg)), and, estimate the importance of atmospheric deposition as a source of MMHg to Arctic land- and sea-scapes. Overall atmospheric MMHg and DMHg concentrations (mean ± SD) were 2.9 ± 3.6 and 3.8 ± 3.1 (n = 37) pg m(-3), respectively. Concentrations of methylated Hg species in the marine boundary layer varied significantly among our sites, with a predominance of MMHg over Hudson Bay (HB), and DMHg over Canadian Arctic Archipelago (CAA) waters. We concluded that DMHg is of marine origin and that primary production rate and sea-ice cover are major drivers of its concentration in the Canadian Arctic marine boundary layer. Summer wet deposition rates of atmospheric MMHg, likely to be the product of DMHg degradation in the atmosphere, were estimated at 188 ± 117.5 ng m(-2) and 37 ± 21.7 ng m(-2) for HB and CAA, respectively, sustaining MMHg concentrations available for biomagnification in the pelagic food web.

Free-living stage of the unicellular algae Coccomyxa sp. parasite of the blue mussel (Mytilus edulis): Low-light adaptation, capacity for growth at a very wide salinity range and tolerance to low pH.

Coccomyxa parasitica and similar, unidentified Coccomyxa species infect the soft tissues of many bivalve species, giving them a conspicuous green coloration and leading to mantle and shell deformities. Very little information exists regarding the ecophysiology of parasitic Coccomyxa sp. and this limits our ability to understand how it can achieve its unusual life history. In the present study, the growth of Coccomyxa sp. Metis-sur-mer (KJ372210) in liquid culture was investigated. Coccomyxa sp. maximum growth rate was 0.75day-1 (equivalent to a doubling time of 22h), growth saturated at ∼100µmol quanta m-2s-1 and was still ∼20% of maximum at 13µmol quanta m-2s-1, the lowest photosynthetically available radiation (PAR) intensity tested. Coccomyxa sp. showed a very wide tolerance to salinity, with growth rate practically invariable over the salinity range 15-35. Even in natural spring water enriched with f/2 media, the growth rate was nearly half of maximum. Unlike the closely related acid-tolerant Coccomyxa sp. CPCC 508, Coccomyxa sp. Metis-sur-mer could not grow in acidic waters. Considering the ability of Coccomyxa sp. to achieve a high growth rate at low irradiance and its relative insensitivity to the prevailing salinity, it is somewhat surprising it has not yet infected bivalves at a larger scale worldwide.

Total and methylated mercury in Arctic multiyear sea ice.

Mercury is one of the primary contaminants of concern in the Arctic marine ecosystem. While considerable efforts have been directed toward understanding mercury cycling in the Arctic, little is known about mercury dynamics within Arctic multiyear sea ice, which is being rapidly replaced with first-year ice. Here we report the first study on the distribution and potential methylation of mercury in Arctic multiyear sea ice. Based on three multiyear ice cores taken from the eastern Beaufort Sea and McClure Strait, total mercury concentrations ranged from 0.65 to 60.8 pM in bulk ice, with the highest values occurring in the topmost layer (∼40 cm) which is attributed to the dynamics of particulate matter. Methylated mercury concentrations ranged from below the method detection limit (<0.1 pM) to as high as 2.64 pM. The ratio of methylated to total mercury peaked, up to ∼40%, in the mid to bottom sections of the ice, suggesting the potential occurrence of in situ mercury methylation. The annual fluxes of total and methylated mercury into the Arctic Ocean via melt of multiyear ice are estimated to be 420 and 42 kg yr(-1), respectively, representing an important and changing source of mercury and methylmercury into the Arctic Ocean marine ecosystem.

First record of the green microalgae Coccomyxa sp. in blue mussel Mytilus edulis (L.) from the Lower St. Lawrence Estuary (Québec, Canada).

During autumn 2012 and spring 2013, blue mussels Mytilus edulis (L.) with strongly deformed (L-shaped) posterior shell margins and green spots in soft tissue (microalgae) were collected from intertidal zone along the south shore of the Lower St. Lawrence Estuary near Rimouski (Québec, Canada). Identification of algal cells infesting mussels as Coccomyxa sp. was confirmed by rRNA sequencing and HPLC pigment analysis. Flow cytometric analysis revealed the presence of algal cells in the hemolymph and extrapallial fluid in mussels with deformed and non-deformed shells; concentrations of algal cells were ranged from about 200mL(-1) in mussels with actually non-deformed shells to concentrations reaching up to 3.8×10(7)mL(-1) in mussels with heavily deformed ones. Chemical analyses of soft tissues led us to conclude that butyltin compounds and trace metals cannot be considered among factors responsible for the shell deformity observed. Using scanning electron microscopy, the biogenic nature of the erosion on the external shell surface and aragonitic lenses of prisms in the curvature zone of deformed shells (in sections) were recorded. The sequence of the green algae from M. edulis of the Lower St. Lawrence Estuary was closely related to Coccomyxa sp. infecting M. edulis from the Flensburg Fjord (North Sea) and Modiolus modiolus (L.) from the Vityaz Bay (Sea of Japan).

Pre-exposure to Cu2+ and CuO NPs leads to infection of caged blue mussels, Mytilus edulis L., by pathogenic microalga: Pilot study in the Lower St. Lawrence Estuary (Québec, Canada).

As evidenced from literature, exposure to non-lethal concentrations of dissolved copper (Cu2+) and copper nanoparticles (CuO NPs) promotes blue mussels susceptibility to various bacterial infections. We study whether pre-exposure (3.5 h) with CuSO4 (100 µg Cu L-1) and CuO NPs (1000 µg Cu L-1) will result in infection of M. edulis L. with pathogenic microalga Coccomyxa sp. under field conditions. In May - September 2019, cages were installed in the site Metis-sur-Mer, St. Lawrence Estuary (QC, Canada) where the native mussel population is known to be infected with the pathogen. Untreated and pre-exposed mussels were grown for up to 130 days. Only the mussels pre-exposed to copper were infected by Coccomyxa. This finding allows proposing that occurrences of Coccomyxa-infected mussels worldwide might have an association with water pollution with xenobiotics. Pre-exposure of caged mussels to copper, as a protocol monitoring for other infectious agents, can be recommended to test.

Antimicrobial stewardship in acute care centres: A survey of 68 hospitals in Quebec.

BACKGROUND: Antimicrobial stewardship programs (ASPs) and quantitative monitoring of antimicrobial use are required to ensure that antimicrobials are used appropriately in the acute care setting, and have the potential to reduce costs and limit the spread of antimicrobial-resistant organisms and Clostridium difficile. Currently, it is not known what proportion of Quebec hospitals have an ASP and/or monitor antimicrobial use. OBJECTIVES: To determine what proportion of Quebec hospitals have an ASP, and what is the nature of such a program. METHODS: A detailed questionnaire was sent to the pharmacy directors of all acute care hospitals in the province of Quebec. Information was collected on antimicrobial surveillance; antimicrobial stewardship and resource allocation to these areas were assessed. RESULTS: Questionnaires were completed for 68 of 81 (84%) hospitals contacted. ASPs were identified at 50 (74%) hospitals, but only 20 (29%) of hospitals had a quantitative antimicrobial surveillance program (QASP) in 2006. Academic centres (P=0.03) and hospitals with over 200 beds (P=0.02) were more likely to have a QASP. Even among hospitals with an ASP, 18% had less than one full-time pharmacist for a QASP. CONCLUSIONS: Over one-quarter of Quebec hospitals do not have an ASP, and few hospitals in Quebec are currently evaluating their use of antimicrobials on a quantitative basis. In some cases, the lack of a QASP may be due to the allocation of insufficient pharmaceutical resources to antimicrobial stewardship (ie, less than one full-time pharmacist).

Need for focus on microbial species following ice melt and changing freshwater regimes in a Janus Arctic Gateway.

Oceanic gateways are sensitive to climate driven processes. By connecting oceans, they have a global influence on marine biological production and biogeochemical cycles. The furthest north of these gateways is Nares Strait at the top of the North Water between Greenland and Ellesmere Island (Canada). This gateway is globally beneficial, first by supporting high local mammal and bird populations and second with the outflow of phosphate-rich Arctic waters fueling the North Atlantic spring bloom. Both sides of the North Water are hydrologically distinct with counter currents that make this Arctic portal a Janus gateway, after Janus, the Roman god of duality. We examined oceanographic properties and differences in phytoplankton and other protist communities from the eastern and western sides of the North Water (latitude 76.5°N) and found that species differed markedly due to salinity stratification regimes and local hydrography. Typical Arctic communities were associated with south flowing currents along the Canadian side, while potentially noxious Pseudo-nitzschia spp. were dominant on the Greenland side and associated with greater surface freshening from ice melt. This susceptibility of the Greenland side to Pseudo-nitzschia spp. blooms suggest that monitoring species responses to climate mediated changes is needed.

UV effects on marine planktonic food webs: A synthesis of results from mesocosm studies.

UV irradiance has a broad range of effects on marine planktonic organisms. Direct and indirect effects on individual organisms have complex impacts on food-web structure and dynamics, with implications for carbon and nutrient cycling. Mesocosm experiments are well suited for the study of such complex interrelationships. Mesocosms offer the possibility to conduct well-controlled experiments with intact planktonic communities in physical, chemical and light conditions mimicking those of the natural environment. In allowing the manipulation of UV intensities and light spectral composition, the experimental mesocosm approach has proven to be especially useful in assessing the impacts at the community level. This review of mesocosm studies shows that, although a UV increase even well above natural intensities often has subtle effects on bulk biomass (carbon and chlorophyll), it can significantly impact the food-web structure because of different sensitivity to UV among planktonic organisms. Given the complexity of UV impacts, as evidenced by results of mesocosm studies, interactions between UV and changing environmental conditions (e.g. eutrophication and climate change) are likely to have significant effects on the function of marine ecosystems.

Accuracy of preoperative imaging methods in a retrospective series of 14 patients with operated intraductal papillary mucinous tumors of the pancreas.

UNLABELLED: Accuracy of preoperative imaging methods for the diagnosis of intraductal papillary mucinous tumor of the pancreas (IPMT) is not well known. AIMS: To compare diagnostic accuracy of various preoperative imaging methods with pathology data following surgical resection. PATIENTS AND METHODS: Fourteen consecutive patients underwent pancreatic surgical resection for IPMT between January 1988 and May 2002. Imaging methods included endoscopic retrograde cholangiopancreatography and/or magnetic resonance cholangiopancreatography and/or endoscopic ultrasonography. Results of preoperative morphological examinations were compared with histopathological findings from surgical specimens. RESULTS: IPMT was located to the pancreatic head or body in 72% of patients and involved the main pancreatic duct (MPD) in 79% of cases Carcinoma was diagnosed in 35% of the cases. Sensitivity of imaging methods varied from 64 to 80% to accurately locate the tumor and from 73 to 80% in distinguishing between types involving the MPD or the accessory ducts. Planned surgical resection based on preoperative imagery correlated with final surgery in 57% of the patients. Histological study of whole pancreas specimens revealed lesions in undilated ducts, and also dilated ducts without histological lesions. CONCLUSION: The sensitivity of preoperative imaging methods is moderate in defining intraductal extension of IPMT. Duct dilatation is not predictive of histological involvement by tumors and ducts may be pathological without dilatation.

NOD2/CARD15 gene polymorphisms in Crohn's disease: a genotype- phenotype analysis.

OBJECTIVES: Three recently identified NOD2/CARD15 mutations have been described associated with an increased susceptibility Crohn's disease (CD). Our aim was to examine the potential association of these NOD2 mutations with CD and different subsets of CD phenotypes in our population. METHODS: Two hundred and five well-defined CD patients from north-western France and 95 ethnically matched healthy controls were genotyped for mutations R702W, G908R and Leu1007insC by DNA sequencing. Allele and genotype frequencies of NOD2 variants were examined in the whole series of CD and in different subgroups of CD phenotypes defined by the clinical characteristics of the Vienna classification (age at diagnosis, location and behaviour) or by histological features (granuloma). RESULTS: Carriers of at least one NOD2/CARD15 variant were significantly more frequent in CD than in controls (38.0% versus 20.0%, P < 0.002), and the R702W allele was the most significant contributor to this NOD2 association with CD. Homozygotes and compound heterozygotes combined had a higher risk of CD (odds ratio = 12.0, P < 0.0026) than simple heterozygotes for any variant (odds ratio = 2.2, P < 0.013) compared with subjects with no variant. Univariate analysis revealed that carriage of at least one NOD2 mutation was significantly associated with ileal involvement (P < 0.03), and stricturing evolution (P < 0.0015). Granuloma was associated with an excess of the R702W allele (16.1% versus 8.0%, Pc < 0.035), and was correlated with a young age at diagnosis, whatever the NOD2/CARD15 genotype. Multivariate analysis demonstrated that carriage of NOD2/CARD15 mutants, especially R702W, was primarily and independently associated both with stricturing evolution of CD and the presence of granuloma. CONCLUSIONS: In our population, all NOD2/CARD15 mutant genotypes, especially compound heterozygosity, were found to increase the risk of CD, but R702W was the sole allele showing a significant association with CD. In addition, we confirm the positive and independent association of the R702W mutation with stricturing behaviour and describe a second one with the presence of granuloma.

INFLUENCE OF UV-B RADIATION ON NITROGEN UTILIZATION BY A NATURAL ASSEMBLAGE OF PHYTOPLANKTON.

A 7-day mesocosm experiment was conducted in July 1996 to investigate the effects of ambient UV-B radiation (UVBR) exclusion and two UVBR enhancements above ambient levels on NO3- , NH4+ and urea utilization in a natural plankton community (<240 µm) from the Lower St. Lawrence Estuary. The phytoplankton community was dominated by diatoms during the first 3 days and, afterward, by flagellates and dinoflagellates. The results of 4-h incubations just below the water surface show that, compared with ambient UVBR conditions, UVBR exclusion generally increased NO3- , NH4+ , and urea uptakes. During the last 4 days of the experiment, the percent increase in the specific uptake rate of urea under excluded UVBR conditions varied between 17% and 130% and was a linear function of the ambient UVBR dose removed. During the first 3 days, the phytoplankton community dominated by diatoms was able to withstand UVBR enhancements without any perceptible effect on nitrogen uptake. However, during the post-diatom bloom period, UVBR enhancements resulted in decreases in NO3- , NH4+ , and urea uptake compared with ambient UVBR conditions. The reduction of urea uptake under UVBR enhancements during the last 3 days varied between 23% and 64% and was linearly related to the enhanced UVBR dose. However, the different UVBR treatments did not affect the internal organic nitrogen composition (internal urea, free amino acids, and proteins) of the phytoplankton community experiencing vertical mixing in the mesocosms. The discrepancy between short-term uptake measurements at the surface and long-term effects in the mesocosms emphasizes the importance of vertical mixing on UVBR effects in natural ecosystems. This suggests that an increase in ambient UVBR would have a minimal effect on nitrogen utilization by natural phytoplankton assemblages if these are vertically mixed.

Prospective evaluation of a new rapid urease test (Pronto Dry) for the diagnosis of Helicobacter pylori infection.

AIM: Rapid urease tests are commonly used to establish the diagnosis of Helicobacter pylori infection during upper endoscopy. The aim of this study was to evaluate the performance of a new rapid urease test (Pronto Dry) compared with histology as the gold standard. METHODS: Six gastric biopsies (three in the antrum and three in the fundus) were performed in 113 consecutive patients. Eighteen patients were later excluded from analysis because they did not fulfil the inclusion criteria. Four biopsies were examined by two experienced pathologists blinded to the rapid urease tests. Two biopsies (one from antrum and one from the fundus) were pooled for the rapid urease test which was read by the endoscopist 5 and 30 minutes later using the color scale (yellow, pink, orange, dark pink, fuchsia) provided by the manufacturer. RESULTS: According to the histology findings 32 of the 95 patients retained for analysis (33.7%) were positive for Helicobacter pylori. Considering that a positive test was indicated by the dark pink or fuchsia colors, sensitivity and specificity of Pronto Dry were 62.5% and 98.4% at 5 minutes and 84.4% and 98.4% at 30 minutes respectively. Twenty-one of the 28 positive rapid urease tests (75%) were already positive at 5 minutes. CONCLUSION: Considering positive tests are indicated solely by the two darkest colors on the color scale, the performance of Pronto Dry is similar to that of other rapid urease tests. The rapid results provided by Pronto Dry in routine practice would seem to provide obvious advantages.

[Endoscopic and pathological aspect of small bowel and colonic involvement in Whipple's disease: a case report]. / Aspect endoscopique et pathologique de l'atteinte intestinale et colique de la maladie de Whipple. A propos d'un cas.

We describe a case of Whipple's disease confirmed by clinical, histological, bacteriological and molecular criteria. The duodenal involvement was associated with the presence of an endoscopic and histological enterocolitis. Final diagnosis of small bowel and colonic involvement by Whipple's disease was confirmed by histology and molecular biology. We review the literature on extra duodenal involvement. We underline the fact that enterocolitis in Whipple's disease is non-specific. We also discuss the other causes of intestinal mucosal infiltration by macrophages.

[Selective COX-2 inhibitor-associated colitis: two case reports]. / Colite aux anti-inflammatoires non stéroïdiens inhibiteurs préférentiels de la cyclo-oxygénase de type 2. A propos de 2 cas.

Non-steroidal anti-inflammatory drugs (NSAIDs) reduce prostaglandin synthesis by inhibiting cyclo-oxygenase 1 (COX-1) and/or cyclo-oxygenase 2 (COX-2). Different groups of NSAIDs, defined by their action on either COX-1 or COX-2, have been developed. Whether intestinal toxicity of preferential or selective COX-2 inhibitors is reduced compared with that of standard NSAIDs is controversial. We report the cases of two patients with self-limited colitis induced by preferential COX-2. We discuss the mechanisms of intestinal toxic effects of COX-2 preferential inhibitors from endoscopic and histological features of colitis.

[Paroxysmal nocturnal hemoglobinuria associated with intestinal ischemia leading to small bowel perforation]. / Hémoglobinurie paroxystique nocturne avec ischémie digestive compliquée de perforation de l'intestin grêle.

Paroxysmal nocturnal hemoglobinuria is rarely associated with intestinal complications. We report a case of paroxysmal nocturnal hemoglobinuria with small bowel ischemia leading to ileal perforation. In the literature, an ulcerative jejuno-ileitis has been reported in 6 cases of intestinal ischemia, due to thrombosis of mucosal small vessels. This disease is usually revealed by abdominal pain. Based on published cases and our observation of intestinal ischemia leading to small bowel perforation, surgery should be considered as the first-line treatment, especially when small bowel lesions are limited.

Protists in Arctic drift and land-fast sea ice.

Global climate change is having profound impacts on polar ice with changes in the duration and extent of both land-fast ice and drift ice, which is part of the polar ice pack. Sea ice is a distinct habitat and the morphologically identifiable sympagic community living within sea ice can be readily distinguished from pelagic species. Sympagic metazoa and diatoms have been studied extensively since they can be identified using microscopy techniques. However, non-diatom eukaryotic cells living in ice have received much less attention despite taxa such as the dinoflagellate Polarella and the cercozoan Cryothecomonas being isolated from sea ice. Other small flagellates have also been reported, suggesting complex microbial food webs. Since smaller flagellates are fragile, often poorly preserved, and are difficult for non-experts to identify, we applied high throughput tag sequencing of the V4 region of the 18S rRNA gene to investigate the eukaryotic microbiome within the ice. The sea ice communities were diverse (190 taxa) and included many heterotrophic and mixotrophic species. Dinoflagellates (43 taxa), diatoms (29 taxa) and cercozoans (12 taxa) accounted for ~80% of the sequences. The sympagic communities living within drift ice and land-fast ice harbored taxonomically distinct communities and we highlight specific taxa of dinoflagellates and diatoms that may be indicators of land-fast and drift ice.