Metabolic Responses of the Estuarine Gastropod Thais Haemastoma to Hypoxia (Energy Charge, Opine Dehydrogenase,survival, Adaptation, Respiration).

The hypoxia tolerance (LC-50) of Thais haemastoma was inversely related to acclimation temperature but was not related to acclimation salinity between 10 and 30(DEGREES)C and 10 and 30(\u27o)/ooS. T. haemastoma is moderately tolerant to anoxia, the LT-50 (time to 50% mortality) being 12-22 days. Oxyregulatory ability varies from poor to good, and varies inversely with temperature. The oxygen consumption rate was lower after 28 days exposure to hypoxic conditions than at full oxygen saturation at all salinities at 20 and 30(DEGREES)C. Oxygen consumption was low at 10(DEGREES)C regardless of ambient PO(,2). Oxyregulatory ability in T. haemastoma did not show acclimation after 28 days exposure to 53 mm O(,2) at 30(DEGREES) and 30(\u27o)/ooS. Likewise, no induction of the activities of the pyruvate oxidoreductase enzymes in foot tissue occurred after 28 days exposure to 10, 33, and 67% of oxygen saturation. The ratio of mean activities of alanopine dehydrogenase:lactate dehydrogenase:strombine dehydrogenase:octopine dehydrogenase was 3.8:1.2:1.0:0. Alanopine dehydrogenase activity nearly doubled on the first day but had returned to the control level by day 2, and no change occurred in strombine dehydrogenase and lactate dehydrogenase activity over 6 days exposure to anoxia. The total concentration of cellular adenylates remained constant, but the adenylate energy charge, ( ATP + .5 ADP )/( ATP + ADP + AMP ), was reduced at low PO(,2)\u27s. Arginine phosphate concentrations were lower in snails exposed to 10 and 33% oxygen saturation than in those at 67 and 100% of oxygen saturation. Energy charge declined from 0.79 to 0.58 after one day of anoxia at 30(DEGREES)C and 30(\u27o)/ooS while the arginine phosphate concentration declined by 95%. There was no further decrease in either variable with longer exposure to anoxia. Hypoxia tolerance of T. haemastoma is due to a reduction in metabolic demand, especially at low temperature, with ATP production maintained at the expense of arginine phosphate while metabolism switches to anaerobic pathways. The opine pathway is probably only used as a transitional mode before use of long-term anaerobic pathways is initiated

New directional archeomagnetic data of burned cave sediments from Switzerland and geomagnetic field variations in Central Europe

This paper presents new directional archeomagnetic data from nine Meso-/Neolithic fireplaces, sampled in a cave shelter, at Arconciel, in western Switzerland. Rock magnetic measurements indicate a homogenous magnetic mineralogy in all fireplaces, with magnetite as the main magnetic carrier. The remanent magnetization is stable and generally shows one characteristic directional component. Nine new directions, which were obtained from Arconciel, are combined with 356 other archeomagnetic data from a circular area with a radius of 700km around this site, to obtain a penalized least square spline fit for the past 9000yr. We found in general good agreement with other local compilations, such as the Balkan curve, the regional SCHA.DIF.8k model and with lake sediments from UK, Fennoscandia and Switzerland. Nevertheless, a time lag of several centuries is observed for a declination maximum between the archeomagnetic spline fit and the other European data records around 5900BC. This time lag is also observed in the Swiss lake sediment record; therefore we interpret this shift as a local feature of the Earth's magnetic fiel

Epsilon iron oxide: origin of the high coercivity stable low Curie temperature magnetic phase found in heated archeological materials

The identification of epsilon iron oxide (ɛ-Fe2O3) as the low Curie temperature high coercivity stable phase (HCSLT) carrying the remanence in heated archeological samples has been achieved in samples from two archeological sites that exhibited the clearest evidence of the presence of the HCSLT. This uncommon iron oxide has been detected by Confocal Raman Spectroscopy (CRS) and characterized by rock magnetic measurements. Large numbers of ɛ-Fe2O3 microaggregates (in CO) or isolated clusters (in HEL) could be recognized, distributed over the whole sample, and embedded within the ceramic matrix, along with hematite and pseudobrookite and with minor amounts of anatase, rutile, and maghemite. Curie temperature estimates of around 170°C for CO and 190°C for HEL are lower than for pure, synthetic ɛ-Fe2O3 (227°C). This, together with structural differences between the Raman spectra of the archeologically derived and synthetic samples, is likely due to Ti substitution in the ɛ-Fe2O3 crystal lattice. The γ-Fe2O3-ɛ-Fe2O3-α-Fe2O3 transformation series has been recognized in heated archeological samples, which may have implications in terms of their thermal history and in the factors that govern the formation of ɛ-Fe2O3

Extravasation of leukocytes in comparison to tumor cells

The multi-step process of the emigration of cells from the blood stream through the vascular endothelium into the tissue has been termed extravasation. The extravasation of leukocytes is fairly well characterized down to the molecular level, and has been reviewed in several aspects. Comparatively little is known about the extravasation of tumor cells, which is part of the hematogenic metastasis formation. Although the steps of the process are basically the same in leukocytes and tumor cells, i.e. rolling, adhesion, transmigration (diapedesis), the molecules that are involved are different. A further important difference is that leukocyte interaction with the endothelium changes the endothelial integrity only temporarily, whereas tumor cell interaction leads to an irreversible damage of the endothelial architecture. Moreover, tumor cells utilize leukocytes for their extravasation as linkers to the endothelium. Thus, metastasis formation is indirectly susceptible to localization signals that are literally specific for the immune system. We herein compare the extravasation of leukocytes and tumor cells with regard to the involved receptors and the localization signals that direct the cells to certain organs and sites of the body

Genomic investigations of unexplained acute hepatitis in children

Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

Groen, Blauw & Goud: alle landschapselementen in beeld

Nieuwe methodiek voor kartering cultuurhistorische landschapselementen; de zogenaamde MKLE+, die gebruikt wordt om groene en blauwe landschapselementen te inventariseren en te monitoren. Methodiek ontwikkeld door landschapsbeheer Nederland en Alterra. Het gaat hierbij om bosjes, houtwallen, poelen en rietlandjes. Als pilot diende het cultuurlandschap van Middag-Humsterlan