Analyses of group III secreted phospholipase A2 transgenic mice reveal potential participation of this enzyme in plasma lipoprotein modification, macrophage foam cell formation, and atherosclerosis

Among the many mammalian secreted phospholipase A2 (sPLA2) enzymes, PLA2G3 (group III secreted phospholipase A2) is unique in that it possesses unusual N- and C-terminal domains and in that its central sPLA2 domain is homologous to bee venom PLA2 rather than to other mammalian sPLA2s. To elucidate the in vivo actions of this atypical sPLA2, we generated transgenic (Tg) mice overexpressing human PLA2G3. Despite marked increases in PLA2 activity and mature 18-kDa PLA2G3 protein in the circulation and tissues, PLA2G3 Tg mice displayed no apparent abnormality up to 9 months of age. However, alterations in plasma lipoproteins were observed in PLA2G3 Tg mice compared with control mice. In vitro incubation of low density (LDL) and high density (HDL) lipoproteins with several sPLA2s showed that phosphatidylcholine was efficiently converted to lysophosphatidylcholine by PLA2G3 as well as by PLA2G5 and PLA2G10, to a lesser extent by PLA2G2F, and only minimally by PLA2G2A and PLA2G2E. PLA2G3-modified LDL, like PLA2G5- or PLA2G10-treated LDL, facilitated the formation of foam cells from macrophages ex vivo. Accumulation of PLA2G3 was detected in the atherosclerotic lesions of humans and apoE-deficient mice. Furthermore, following an atherogenic diet, aortic atherosclerotic lesions were more severe in PLA2G3 Tg mice than in control mice on the apoE-null background, in combination with elevated plasma lysophosphatidylcholine and thromboxane A2 levels. These results collectively suggest a potential functional link between PLA2G3 and atherosclerosis, as has recently been proposed for PLA2G5 and PLA2G10.     

Microbiome mediating methane and nitrogen transformations in a subterranean estuary

Subterranean estuaries (STEs) are important coastal biogeochemical reactors facilitating unique niches for microbial communities. A common approach in determining STE greenhouse gas and nutrient fluxes is to use terrestrial endmembers, not accounting for microbially mediated transformations throughout the STE. As such, the microbial ecology and spatial distribution of specialists that cycle compounds in STEs remain largely underexplored. In this study, we applied 16S rRNA amplicon sequencing with paired biogeochemical characterisations to spatially evaluate microbial communities transforming greenhouse gases and nutrients in an STE. We show that methanogens are most prevalent at the terrestrial end (up to 2.81% relative abundance) concomitant to the highest porewater methane, carbon dioxide and dissolved organic carbon concentrations (0.41 ± 0.02 μM, 273.31 ± 6.05 μM and 0.51 ± 0.02 mM, respectively). Lower ammonium concentrations corresponded with abundant nitrifying and ammonia-oxidising prokaryotes in the mixing zone (up to 11.65% relative abundance). Methane, ammonium and dissolved organic carbon concentrations all decreased by >50% from the terrestrial to the oceanic end of the 15 m transect. This study highlights the STE's hidden microbiome zonation, as well as the importance of accounting for microbial transformations mitigating nutrient and greenhouse gas fluxes to the coastal ecosystems.     

Population dynamics of the Smith's red-backed vole in highlands of Shikoku

Population dynamics of theSmith 's red-backed vole predominantly common through uplands of Shikoku have been in some degree disclosed by the use of my own and Government Forest Station's samples collected since 1955 onward. It has proved that the upper-range population reaches its density peak possibly in late summer or early fall, but the lower-range one does probably in October–November as the seasonal trend in usual years. The upper one produced a peak three times at 3–4 year intervals, the first peak being an outbreak followed by a crash, during the last decade. It seems likely that all the populations through the range have, in the gross, fluctuated in phase after 1959 at least. The cyclic fluctuation may readily be explained by the theory of intrinsic mechanism, because no external factors are considered to have exerted a conclusive effect. Except what was concerned in the outbreak, the role of the social stress could be set at naught. The regulation of fecundiy by density was expressed more markedly in litter size and less in active reproductivity rate and incidence of pregnancy. The mean litter size at term as small as 2.00 is contrary to our expectation in view of the supposed prolific potential, nevertheless the observed frequency of litter poduction and intra-uterine survival rate has proved not to be so high as to make up for the small litter size. The problem in the postnatal mortality has remained to be solved.     

Studies on the Foaming Property of the Chicken Egg White

The egg white was treated under various whipping conditions, and its foaminess measured. At the same time, the amounts of the coagulated proteins formed from each egg white and their constituent hexose were measured. From these results, discussions were made about the relation between the foaminess of the egg white and the amount of the coagulated proteins under various whipping conditions.     

Changes in the Shape and Surface Hydrophobicity of Ovalbumin during Its Transformation to S-Ovalbumin

Intrinsic viscosity, Stokes radius and the hydrophobic coefficient of Keshavarz and Nakai [Biochim. Biophys. Acta, 576, 269 (1979)] were measured to compare the shape and surface hydrophobicity of ovalbumin and s-ovalbumin. Both the intrinsic viscosity and Stokes radius of s- ovalbumin were smaller than those of ovalbumin, which suggests that the configuration of s- ovalbumin became more compact during the ovalbumin-s-ovalbumin transformation. The hydrophobic coefficient of s-ovalbumin was larger than that of ovalbumin, which suggests that the surface hydrophobicity of s-ovalbumin was larger than that of ovalbumin. Further, these properties were measured for ovalbumin samples obtained at various stages of ovalbumin-s-ovalbumin transformation. Changes in the shape and surface hydrophobicity of ovalbumin were not found in the first stage of ovalbumin-s-ovalbumin transformation. They changed rapidly in the last stage of the ovalbumin-s-ovalbumin transformation.     

Inhibitory effects of monovalent cations on the Ca2+-induced aggregation of porcine intestinal brush border membranes

The Ca2+-induced aggregation of porcine intestinal brush border membranes could be inhibited by addition of monovalent cations to the medium or by increasing the ionic strength of the medium, as measured by the change in optical density of the membrane suspension. The relative effectiveness of monovalent cations at 100 mM in the inhibition was in the order, (Na+ approximately equal to NH4+) greater than (K+ approximately equal to Rb+ approximately equal to Li+) greater than choline+. The Ca2+ concentration dependence profile of the membrane aggregation showed that the Ca2+ threshold at which the aggregation began was distinctly shifted to a higher concentration by the addition of KCl. In addition, the results of fluorometric studies with 1-anilino-8-naphthalene sulfonate suggested that the inhibition of the membrane aggregation by extravesicular KCl is due to a decrease of the binding affinity of Ca2+ for the membranes as a result of neutralization of the surface charges. On the other hand, measurements of the incorporation of 1,6-diphenyl-1, 3,5-hexatriene (DPH) into the membrane vesicles and of the anisotropy of DPH-labeled membranes suggested that the imposition of a salt gradient across the membrane vesicles (out greater than in) causes an increase of lipid fluidity of the membranes. Based on these results, a possible contribution of membrane surface charges and/or membrane fluidity to the Ca2+-induced aggregation of the membranes is discussed.     

Lagrangian tracking measurements revealed the temporal dynamics of nitrogen and phosphorus spiralling in a large Japanese river

Limnology - The in-stream processing of nutrients plays an important role in the fluvial nutrient transport from lands to the ocean, but few empirical studies have addressed the temporal dynamics...     

A Geometry-Based Multiple Testing Correction for Contingency Tables by Truncated Normal Distribution

Statistics in Biosciences - Inference procedure is a critical step of experimental researches to draw scientific conclusions especially in multiple testing. The false positive rate increases unless...     

Basic pH-induced modification of excitation-energy dynamics in fucoxanthin chlorophyll a/c-binding proteins isolated from a pinguiophyte,Glossomastix chrysoplasta

Photosynthetic organisms have diversified light-harvesting complexes (LHCs) to collect solar energy efficiently, leading to an acquisition of their ecological niches. Herein we report on biochemical and spectroscopic characterizations of fucoxanthin chlorophyll a/c-binding protein (FCP) complexes isolated from a marine pinguiophyte Glossomastix chrysoplasta. The pinguiophyte FCP showed one subunit band in SDS-PAGE and one protein-complex band with a molecular weight at around 66 kDa in clear-native PAGE. By HPLC analysis, the FCP possesses chlorophylls a and c, fucoxanthin, and violaxanthin. To clarify excitation-energy-relaxation processes in the FCP, we measured time-resolved fluorescence spectra at 77 K of the FCP adapted to pH 5.0, 6.5, and 8.0. Fluorescence curves measured at pH 5.0 and 8.0 showed shorter lifetime components compared with those at pH 6.5. The rapid decay components at pH 5.0 and 8.0 are unveiled by fluorescence decay-associated (FDA) spectra; fluorescence decays occur in the 270 and 160-ps FDA spectra only at pH 5.0 and 8.0, respectively. In addition, energy-transfer pathways with time constants of tens of picoseconds are altered under the basic pH condition but not the acidic pH condition. These findings provide novel insights into pH-dependent energy-transfer and energy-quenching machinery in not only FCP family but also photosynthetic LHCs.