Does the Clam Mya truncata Regenerate Its Siphon after Predation by Walrus? An Experimental Approach

Walrus (Odobenus rosmarus) prey extensively on the bivalve Mya truncata, removing the siphons. We performed a simple experiment whereby the siphons from 27 M. truncata were removed, 33 controls were left intact, and the clams left on the sea bottom for a year. All the damaged Mya died; all but 2 controls lived. We conclude that M. truncata whose siphons have been grazed by walrus die, leaving over half the clam to predators or scavengers.

The Role of Adult Fiddler Crab Environmental Acoustic Cues and Chemical Cues in Stimulating Molting of Field-Caught Megalopae

In mid-Atlantic estuaries, three fiddler crab species, Uca pugilator, Uca pugnax and Uca minax co-occur, with their adults occupying different habitat types distinguished by salinity and sediment size. Some evidence exists that selective settlement is responsible for this separation but the mechanism is largely unknown. We tested the hypothesis that field-caught megalopae would accelerate metamorphosis in the presence of adult species-specific environmental acoustic cues and conspecific chemical cues. We placed megalopae in seawater with and without adult chemical cues, exposed them to one of three sound treatments for 8 days, and recorded the time each megalopa took to metamorphose. In the absence of adult chemical cues, very few megalopae molted regardless of sound treatment. Molting in the presence of habitat sound and chemical cues varied by species. Many U. pugilator molted in all sound and odor combinations, including no odor/sound. U. pugnax was stimulated to molt by chemical cues from either U. pugilator or U. pugnax, but molting was similar across sound treatments. Our results do not support the hypothesis that sound stimulates molting by fiddler crab megalopae, but support the role of chemical odors from adults as molting cues

Energy Flow through the Marine Ecosystem of the Lancaster Sound Region, Arctic Canada

This paper synthesizes the trophic dynamics of a Canadian arctic marine ecosystem in so far as it is known, using new data on primary production, zooplankton, the bivalve Mya truncata, and arctic cod (Boreogadus saida), as well as literature values for marine mammals and seabirds. The 98,000 sq km region has a high rate of primary production relative to other parts of arctic Canada. About 60 g C/sq. m are fixed annually, of which approximately 90% is contributed by phytoplankton, 10% by ice algae, and 1% by kelp. Phytoplankton production is twofold higher along the south coast of Cornwallis Island than elsewhere in Barrow Strait. Four copepod species, of which Pseudocalanus acuspes is the most important energetically, graze about one-third of the phytoplankton production. Bivalves maintain high biomass but low energy flow, acting as sedimenting agents. Arctic cod is a major component, with 125,000 tonnes being consumed by marine mammals and 23,000 tonnes by seabirds annually. Our hydro-acoustic estimate for mean arctic cod density, 0.0022 fish/sq. m, is probably too low, partly because we have been unable to quantify dense aggregations of schooling fish. The ecological efficiency of ringed seal is near maximum, with 5% of ringed seal ingestion going to bears and man as seal flesh. The data on total kill and prey consumption in whales and birds is incomplete because they migrate out of the Lancaster Sound region in winter. The food chain is very long, with bears occupying the fifth trophic level; this is reflected by high biomagnification factors for persistent lipophilic pollutants such as PCBs. There are major data gaps for some zooplankton and most of the benthos, as well as for winter populations and energetics. This trophic analysis is therefore incomplete and efficiencies for entire trophic levels cannot be calculated.Key words: seals, whales, seabirds, benthos, zooplankton, phytoplankton, primary production, secondary production, harvest, yieldRÉSUMÉ. Cet article résume la dynamique trophique de l’écosystème marin dans le Canada arctique dans la mesure où il est connu, en utilisant de nouvelles données sur la production primaire, le zooplancton, le bivalve Mya truncata, et la morue polaire (Boreogadus saida), ainsi que les valeurs trouvées dans la documentation sur les mammifères et les oiseaux marins. Cette région d’une superficie de 98 000 km2 possède un taux élevé de production primaire par rapport à d’autres parties du Canada arctique. Environ 60 g C.m-2 sont fixés annuellement, dont environ 90 p. cent par le phytoplancton, 10 p. cent par les algues glaciaires et 1 p. cent par les laminaires. La production de phytoplancton est deux fois plus élevée le long de la côte méridionale de l’île Cornwallis qu’ailleurs dans le détroit de Barrow. Quatre espèces de copépodes, dont la Pseudocalanus acuspes est la plus importante du point de vue énergitique, utilisent environ un tiers de la production de phytoplancton pour se nourir. Les bivalves contribuent de façonimportante à la biomasse mais peu au flux énergétique, étant des agents de sédimentation. La morue arctique est une composante importante, étant consommée au taux annuel de 1250 00 tonnes par les mammifères marins et de 23 000 tonnes par les oiseaux marins. Notre estimation hydroacoustique pour la densité moyenne de la morue arctique, 0,002 poissons.m-2, est probablement trop faible, en partie parce que nous avons été incapables de quantifier les regroupements denses des poissons se rassemblant en bancs. L’efficacité écologique du phoque annelé est proche de son maximum, 5 p. cent de l’ingestion de cet animal allant à l’ours et à l’homme sous forme de chair de phoque. Les données sur le nombre d’animaux tués et sur laconsommation de proies chez les baleines et les oiseaux sont incomplètes en raison de leur migration hivernal à  l'extérieur du détroit de Lancaster. La chaine alimentaire est très longue, les ours occupant le cinquième niveau trophique; cela se traduit par des facteurs de bioamplification élevés en ce qui concerne les polluants lipophiles persistants tels que les BPC. Il existe des lacunes dans les données pour certains éléments du zooplancton et pour la plupart du benthos, ainsi que pour les populations et l’énergétique hivernales. Cette analyse trophique est donc incomplète et il n'est pas possible de calculer l’efficacité pour l’ensemble des niveaux trophiques.Mots clés: phoques, baleines, oiseaux marins, benthos, zooplancton, phytoplancton, production primaire, production secondaire, prélèvement, rendemen

Functional Polymorphisms in IL13 Are Protective against High Schistosoma mansoni Infection Intensity in a Brazilian Population

IL-13 is a signature cytokine of the helper T cell type 2 (TH2) pathway which underlies host defense to helminthic infection and activates production of IgE in both parasitized populations and in urban settings after allergen exposure.Two functional polymorphisms in IL13, rs1800925 (or c.1-1111C>T) and rs20541 (or R130Q) were previously found to be associated with Schistosoma hematobium infection intensity. They have not been thoroughly explored in S. mansoni-endemic populations, however, and were selected along with 5 tagging SNPs for genotyping in 812 individuals in 318 nuclear families from a schistosomiasis-endemic area of Conde, Bahia, in Brazil. Regression models using GEE to account for family membership and family-based quantitative transmission disequilibrium tests (QTDT) were used to evaluate associations with total serum IgE (tIgE) levels and S. mansoni fecal egg counts adjusted for non-genetic covariates. We identified a protective effect for the T allele at rs20541 (P = 0.005) against high S. mansoni egg counts, corroborated by QTDT (P = 0.014). Our findings also suggested evidence for protective effects for the T allele at rs1800925 and A allele at rs2066960 after GEE analysis only (P = 0.050, 0.0002).The two functional variants in IL13 are protective against high S. mansoni egg counts. These markers showed no evidence of association with tIgE levels, unlike tIgE levels previously studied in non-parasitized or atopic study populations

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Cyclic Vomiting Syndrome in 41 adults: the illness, the patients, and problems of management

BACKGROUND: Cyclic Vomiting Syndrome (CVS) is a disorder characterized by recurrent, stereotypic episodes of incapacitating nausea, vomiting and other symptoms, separated by intervals of comparative wellness. This report describes the clinical features, co-morbidities and problems encountered in management of 41 adult patients who met the diagnostic criteria for CVS. METHODS: This is a retrospective study of adults with CVS seen between 1994 and 2003. Follow-up data were obtained by mailed questionnaires. RESULTS: Age of onset ranged from 2 to 49 years. The duration of CVS at the time of consultation ranged from less than 1 year to 49 years. CVS episodes were stereotypic in respect of their hours of onset, symptomatology and length. Ninety-three percent of patients had recognizable prodromes. Half of the patients experienced a constellation of symptoms consisting of CVS episodes, migraine diathesis, inter-episodic dyspeptic nausea and a history of panic attacks. Deterioration in the course of CVS is indicated by coalescence of episodes in time. The prognosis of CVS is favorable in the majority of patients. CONCLUSION: CVS is a disabling disorder affecting adults as well as children. Because its occurrence in adults is little known, patients experience delayed or mis-diagnosis and ineffectual, sometimes inappropriately invasive management

Positional Cloning of “Lisch-like”, a Candidate Modifier of Susceptibility to Type 2 Diabetes in Mice

In 404 Lepob/ob F2 progeny of a C57BL/6J (B6) x DBA/2J (DBA) intercross, we mapped a DBA-related quantitative trait locus (QTL) to distal Chr1 at 169.6 Mb, centered about D1Mit110, for diabetes-related phenotypes that included blood glucose, HbA1c, and pancreatic islet histology. The interval was refined to 1.8 Mb in a series of B6.DBA congenic/subcongenic lines also segregating for Lepob. The phenotypes of B6.DBA congenic mice include reduced β-cell replication rates accompanied by reduced β-cell mass, reduced insulin/glucose ratio in blood, reduced glucose tolerance, and persistent mild hypoinsulinemic hyperglycemia. Nucleotide sequence and expression analysis of 14 genes in this interval identified a predicted gene that we have designated “Lisch-like” (Ll) as the most likely candidate. The gene spans 62.7 kb on Chr1qH2.3, encoding a 10-exon, 646–amino acid polypeptide, homologous to Lsr on Chr7qB1 and to Ildr1 on Chr16qB3. The largest isoform of Ll is predicted to be a transmembrane molecule with an immunoglobulin-like extracellular domain and a serine/threonine-rich intracellular domain that contains a 14-3-3 binding domain. Morpholino knockdown of the zebrafish paralog of Ll resulted in a generalized delay in endodermal development in the gut region and dispersion of insulin-positive cells. Mice segregating for an ENU-induced null allele of Ll have phenotypes comparable to the B.D congenic lines. The human ortholog, C1orf32, is in the middle of a 30-Mb region of Chr1q23-25 that has been repeatedly associated with type 2 diabetes

Association of the PHACTR1/EDN1 genetic locus with spontaneous coronary artery dissection

Background: Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute coronary syndromes (ACS) afflicting predominantly younger to middle-aged women. Observational studies have reported a high prevalence of extracoronary vascular anomalies, especially fibromuscular dysplasia (FMD) and a low prevalence of coincidental cases of atherosclerosis. PHACTR1/EDN1 is a genetic risk locus for several vascular diseases, including FMD and coronary artery disease, with the putative causal noncoding variant at the rs9349379 locus acting as a potential enhancer for the endothelin-1 (EDN1) gene. Objectives: This study sought to test the association between the rs9349379 genotype and SCAD. Methods: Results from case control studies from France, United Kingdom, United States, and Australia were analyzed to test the association with SCAD risk, including age at first event, pregnancy-associated SCAD (P-SCAD), and recurrent SCAD. Results: The previously reported risk allele for FMD (rs9349379-A) was associated with a higher risk of SCAD in all studies. In a meta-analysis of 1,055 SCAD patients and 7,190 controls, the odds ratio (OR) was 1.67 (95% confidence interval [CI]: 1.50 to 1.86) per copy of rs9349379-A. In a subset of 491 SCAD patients, the OR estimate was found to be higher for the association with SCAD in patients without FMD (OR: 1.89; 95% CI: 1.53 to 2.33) than in SCAD cases with FMD (OR: 1.60; 95% CI: 1.28 to 1.99). There was no effect of genotype on age at first event, P-SCAD, or recurrence. Conclusions: The first genetic risk factor for SCAD was identified in the largest study conducted to date for this condition. This genetic link may contribute to the clinical overlap between SCAD and FMD

The genetic architecture of type 2 diabetes

The genetic architecture of common traits, including the number, frequency, and effect sizes of inherited variants that contribute to individual risk, has been long debated. Genome-wide association studies have identified scores of common variants associated with type 2 diabetes, but in aggregate, these explain only a fraction of heritability. To test the hypothesis that lower-frequency variants explain much of the remainder, the GoT2D and T2D-GENES consortia performed whole genome sequencing in 2,657 Europeans with and without diabetes, and exome sequencing in a total of 12,940 subjects from five ancestral groups. To increase statistical power, we expanded sample size via genotyping and imputation in a further 111,548 subjects. Variants associated with type 2 diabetes after sequencing were overwhelmingly common and most fell within regions previously identified by genome-wide association studies. Comprehensive enumeration of sequence variation is necessary to identify functional alleles that provide important clues to disease pathophysiology, but large-scale sequencing does not support a major role for lower-frequency variants in predisposition to type 2 diabetes