Gut Mucosal Antibody Responses and Implications for Food Allergy

The gastrointestinal mucosa is a critical environmental interface where plasma cells and B cells are exposed to orally-ingested antigens such as food allergen proteins. It is unclear how the development of B cells and plasma cells in the gastrointestinal mucosa differs between healthy humans and those with food allergy, and how B cells contribute to, or are affected by, the breakdown of oral tolerance. In particular, the antibody gene repertoires associated with symptomatic allergy have only begun to be characterized in full molecular detail. Here, we review literature concerning B cells and plasma cells in the gastrointestinal system in the context of food allergy, with a focus on human studies

Two-XRD-line ferrihydrite and FeSi-Mn oxyhydroxide mineralization from Franklin Seamount

ABSTRACT Large deposits of Fe-Si-Mn oxyhydroxide, intimately associated with active warm springs, cover the flanks and caldera of Franklin Seamount in the western Woodlark Basin, Papua New Guinea The deposits are dominated by poorly crystalline Fe oxyhydroxide, so-called two-XRD-line ferrihydrite Data on hydrothermal samples of ferrihydrite from Franklin Seamount provide new insights into the atomic structure and chemical compositron of this mineral. Electron microscopy supported by X-ray and selected-area electron-diffraction (XRD, SAED) analysis shows that the Franklin Seamount ferrihydrite consists of soft friable agglomerates of randomly stacked colloidal platelets or crystallites. 20-90 A in diameter, which possess shoft-range atomic order in two dimensions and highly variable specific surface-areas. Differential thermal analysis indicates that the fenihydrite is very stable, not transforming to hematite until 570"C. Semiquantitative energy-dispersion spectroscopy (EDS) analysis with a spatial resolution of 35 A indicates that agglomerates of pure ferrihydrite contain important amounts of Si (on average, 7 .5 wt.Vo Si) and a constant Si:Fe ratio (on average, 0.45, atomic proportions) plus minor but variable amounts of sorbed P, S and As. Individual crystallites exhibit very little beam-induced damage during the EDS analysis. We suggest that Si is capable of being incorporated within the structure of the fenihydrite. This suggestion is supported by XRD pattems showing a significant shift in the 1 I (/zt) hump to higher values of d, compared to Si-free ferrihydrite, and by the thermal stability of the mineral. EDS results and results of bulk analyses demonstrate the wide range of compositions of two-XRDline f-enihydrite; nevertheless, an average composition of vl1Fe;2eIV1Si, Fe, Al)r 3(O, OH, H2O)12 is proposed for the samples from Franklin Seamount Keywords: femihydrite, crystal sffucture, sorption, iron, silicon, X-ray powder diffraction, transmission electron microscopy, thermal analysis, Franklin Seamount, Papua New Guinea. Sovrraarnp Des gisements importants d'un oxyhydroxyde de Fe-Si-Mn sont intimement associ6s aux dvents d'eau tidde le long des flancs et de la cald€ra du guyot de Franklin, dans la partie occidentale du bassin de Woodlark, en Papouasie-Nouvelle-Guin6e. Les gisements contiennent suftout un oxyhydroxyde d6sordonn6 de fer que l'on qualifie de fenihydrite d deux raies (en diffraction X). Les donn6es obtenues sur les 6chantillons de ferrihydrite hydrothermale du guyot de Franklin permettent de nouvelles interpr6tations d propos de la structue atomique et la composition chimique de ce min6ral. Les observations en microscopie 6lectronique, dtay6es par des donn6es en diffraction X et diffraction d'6lectrons sur aire restreinte, montrent que la ferrihydrite du guyot de Franklin esifaite d'amas mous, friables et d6sordonn6s de plaquettes ou de cristallites colloidaux entre 20 et 90.& de diambtre, poss6dant un agencement ordonn6 en deux dimensions et des surfaces sp6cifiques trds variables. Une analyse thermique diff6rentielle prouve que la ferrihydrite est trbs stable, sans tendance i se transformer en h6matitejusqu'd un seuil de 570'C. Une analyse semiquantitative en dispersion d'6nergie avec r6solution spatiale de 35 A montre que les agglom6rats de ferihydrite pure contiennent un niveau 61ev6 en Si (1.5Vo Si, poids, en moyenne) et un rappoft Si:Fe constant (045, propotlion atomique, en moyenne), ainsi que des quantit6s moindres mais variables de P, S et As adsorb6es Les cristallites individuels ne semblent pas endommag6s par le faisceau d'6lectrons au cours de l'analyse par dispersion d'6nergie. A notre avis, le Si serait incorpor6 dans la structure de la ferrihydrite. Cette hypothdse repose sur le d6calement impoftant de la raie floue I 1 (ftft) vers une valeur plus 6lev6e de d, par rapport i la ferrihydrite sans Si, et sur la stabilit6 thermique de ce min6ral ainsi substitu6. Les rdsultats de I'analyse en dispersion d'6nergie et de I'analyse globale d6montrent la grande variabilit6 en composition de la ferrihydrite d deux raies; dans la r6gion du guyot de Franklin, la composition moyenne de ce min6ral serait vl(Fe)z gIV(Si, Fe, Al)r :(O, OH, H2O)12. (Traduit par la R6daction) Mots-cl6s: ferrihydrite, structure cristalline, sorption, fer, silicium, diffraction X sur poudre, microscopie 6lectronique par transmission, analyse thermique, guyot de Franklin

Why are biotic iron pools uniform across high- and low-iron pelagic ecosystems?

Dissolved iron supply is pivotal in setting global phytoplankton productivity and pelagic ecosystem structure. However, most studies of the role of iron have focussed on carbon biogeochemistry within pelagic ecosystems, with less effort to quantify the iron biogeochemical cycle. Here we compare mixed-layer biotic iron inventories from a low-iron (~0.06nmol L-1) subantarctic (FeCycle study) and a seasonally high-iron (~0.6nmol L-1) subtropical (FeCycle II study) site. Both studies were quasi-Lagrangian, and had multi-day occupation, common sampling protocols, and indirect estimates of biotic iron (from a limited range of available published biovolume/carbon/iron quotas). Biotic iron pools were comparable (~100±30pmol L-1) for low- and high-iron waters, despite a tenfold difference in dissolved iron concentrations. Consistency in biotic iron inventories (~80±24pmol L-1, largely estimated using a limited range of available quotas) was also conspicuous for three Southern Ocean polar sites. Insights into the extent to which uniformity in biotic iron inventories was driven by the need to apply common iron quotas obtained from laboratory cultures were provided from FeCycle II. The observed twofold to threefold range of iron quotas during the evolution of FeCycle II subtropical bloom was much less than reported from laboratory monocultures. Furthermore, the iron recycling efficiency varied by fourfold during FeCycle II, increasing as stocks of new iron were depleted, suggesting that quotas and iron recycling efficiencies together set biotic iron pools. Hence, site-specific differences in iron recycling efficiencies (which provide 20-50% and 90% of total iron supply in high- and low-iron waters, respectively) help offset the differences in new iron inputs between low- and high-iron sites. Future parameterization of iron in biogeochemical models must focus on the drivers of biotic iron inventories, including the differing iron requirements of the resident biota, and the subsequent fate (retention/export/recycling) of the biotic iron

Wear of human teeth: a tribological perspective

The four main types of wear in teeth are attrition (enamel-on-enamel contact), abrasion (wear due to abrasive particles in food or toothpaste), abfraction (cracking in enamel and subsequent material loss), and erosion (chemical decomposition of the tooth). They occur as a result of a number of mechanisms including thegosis (sliding of teeth into their lateral position), bruxism (tooth grinding), mastication (chewing), toothbrushing, tooth flexure, and chemical effects. In this paper the current understanding of wear of enamel and dentine in teeth is reviewed in terms of these mechanisms and the major influencing factors are examined. In vitro tooth wear simulation and in vivo wear measurement and ranking are also discussed

Oceanography : plankton in a warmer world

Author Posting. © Nature Publishing Group, 2006. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 444 (2006): 695-696, doi:10.1038/444695a.Satellite data show that phytoplankton biomass and growth generally decline as the oceans’ surface waters warm up. Is this trend, seen over the past decade, a harbinger of the future for marine ecosystems

Size matters: the value of small populations for wintering waterbirds

Protecting systematically selected areas of land is a major step towards biodiversity conservation worldwide. Indeed, the identification and designation of protected areas more often than not forms a core component of both national and international conservation policies. In this paper we provide an overview of those Special Protection Areas and Ramsar Sites that have been classified in Great Britain as of 1998/99 for a selection of wintering waterbird species, using bird count data from the Wetland Bird Survey. The performance of this network of sites is remarkable, particularly in comparison with published analyses of networks elsewhere in the world. Nevertheless, the current site-based approach, whilst having the great benefit of simplicity, is deliberately biased towards aggregating species at the expense of the more dispersed distribution species. To ensure that the network continues successfully to protect nationally and internationally important waterbird populations, efforts now need to concentrate on the derivation of species-specific representation targets and, in particular, the ways in which these can be incorporated into the site selection process. Although these analyses concern the performance of protected areas for waterbirds in Great Britain, the results have wide-ranging importance for conservation planning in general and the design of protected area networks

GRB 060313: A New Paradigm for Short-Hard Bursts?

We report the simultaneous observations of the prompt emission in the gamma-ray and hard X-ray bands by the Swift-BAT and the KONUS-Wind instruments of the short-hard burst, GRB 060313. The observations reveal multiple peaks in both the gamma-ray and hard X-ray bands suggesting a highly variable outflow from the central explosion. We also describe the early-time observations of the X-ray and UV/Optical afterglows by the Swift XRT and UVOT instruments. The combination of the X-ray and UV/Optical observations provide the most comprehensive lightcurves to date of a short-hard burst at such an early epoch. The afterglows exhibit complex structure with different decay indices and flaring. This behavior can be explained by the combination of a structured jet, radiative loss of energy, and decreasing microphysics parameters occurring in a circum-burst medium with densities varying by a factor of approximately two on a length scale of 10^17 cm. These density variations are normally associated with the environment of a massive star and inhomogeneities in its windy medium. However, the mean density of the observed medium (n approximately 10^−4 cm^3) is much less than that expected for a massive star. Although the collapse of a massive star as the origin of GRB 060313 is unlikely, the merger of a compact binary also poses problems for explaining the behavior of this burst. Two possible suggestions for explaining this scenario are: some short bursts may arise from a mechanism that does not invoke the conventional compact binary model, or soft late-time central engine activity is producing UV/optical but no X-ray flaring.Comment: 28 pages, 6 figures. Accepted for publication in ApJ. Clarifications made and typos correcte

Minor differences in body condition and immune status between avian influenza virus-infected and noninfected mallards: a sign of coevolution?

Wildlife pathogens can alter host fitness. Low pathogenic avian influenza virus (LPAIV) infection is thought to have negligible impacts on wild birds; however, effects of infection in free-living birds are largely unstudied. We investigated the extent to which LPAIV infection and shedding were associated with body condition and immune status in free-living mallards (Anas platyrhynchos), a partially migratory key LPAIV host species. We sampled mallards throughout the species\u27 annual autumn LPAIV infection peak, and we classified individuals according to age, sex, and migratory strategy (based on stable hydrogen isotope analysis) when analyzing data on body mass and five indices of immune status. Body mass was similar for LPAIV-infected and noninfected birds. The degree of virus shedding from the cloaca and oropharynx was not associated with body mass. LPAIV infection and shedding were not associated with natural antibody (NAbs) and complement titers (first lines of defense against infections), concentrations of the acute phase protein haptoglobin (Hp), ratios of heterophils to lymphocytes (H:L ratio), and avian influenza virus (AIV)-specific antibody concentrations. NAbs titers were higher in LPAIV-infected males and local (i.e., short distance) migrants than in infected females and distant (i.e., long distance) migrants. Hp concentrations were higher in LPAIV-infected juveniles and females compared to infected adults and males. NAbs, complement, and Hp levels were lower in LPAIV-infected mallards in early autumn. Our study demonstrates weak associations between infection with and shedding of LPAIV and the body condition and immune status of free-living mallards. These results may support the role of mallards as asymptomatic carriers of LPAIV and raise questions about possible coevolution between virus and host