Depolarization increases cellular light transmission

Application of optical methods to human brain tissue in vivo, e.g., measuring oxyhemoglobin and deoxyhemoglobin concentration changes with near-infrared spectroscopy (NIRS), requires the a priori assumption that background optical properties remain unchanged during measurements1,2. However, fundamental knowledge about light scattering by brain cells per se remains sparse; many factors influence light transmission changes through living brain tissue, bringing into question what is being measured. We have observed slow wave-ring spreads of light transmission changes on the rat cerebral cortex during potassium-induced cortical spreading depression (CSD) and ascribed them to squeezing-out of blood from capillaries by swollen brain cells3,4. However, in rat hippocampal slices, where no blood components were involved, similar light transmission changes were observed during K+-induced CSD and ascribed to cell swelling and dendritic beading5,6,7. Here we show that two-dimensional light scattering changes occur through suspensions of osmotically swollen (depolarized) red blood cells, apparently arising from light scattering changes at the less curved, swollen surface of the steep electrochemical gradient coupled with water activity difference across the plasmic membrane. These optical property changes are likely to be relevant to interpretation of photometry or spectroscopy findings of brain tissue in vivo, where neurons are polarizing and depolarizing during brain function

行政データに基づいた野生動物の個体群動態のモデリングと管理への応用

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 宮下 直, 東京大学教授 岸野 洋久, 東京大学准教授 瀧本 岳, 東京大学准教授 吉田 丈人, 東京大学准教授 鈴木 牧University of Tokyo(東京大学

Genome-Wide Maps of Mononucleosomes and Dinucleosomes Containing Hyperacetylated Histones of Aspergillus fumigatus

It is suggested that histone modifications and/or histone variants influence the nucleosomal DNA length. We sequenced both ends of mononucleosomal and dinucleosomal DNA fragments of the filamentous fungus Aspergillus fumigatus, after treatment with the histone deacetylase inhibitor trichostatin A (TSA). After mapping the DNA fragments to the genome, we identified >7 million mononucleosome positions and >7 million dinucleosome positions. We showed that the distributions of the lengths of the mononucleosomal DNA fragments after 15-min and 30-min treatments with micrococcal nuclease (MNase) showed a single peak at 168 nt and 160 nt, respectively. The distributions of the lengths of the dinucleosomal DNA fragments after 15-min- and 30-min-treatment with MNase showed a single peak at 321 nt and 306 nt, respectively. The nucleosomal DNA fragments obtained from the TSA-treated cells were significantly longer than those obtained from the untreated cells. On the other hand, most of the genes did not undergo any change after treatment. Between the TSA-treated and untreated cells, only 77 genes had ≥2-fold change in expression levels. In addition, our results showed that the locations where mononucleosomes were frequently detected were conserved between the TSA-treated cells and untreated cells in the gene promoters (lower density of the nucleosomes). However, these locations were less conserved in the bodies (higher density of the nucleosomes) of genes with ≥2-fold changes. Our findings indicate that TSA influences the nucleosome positions, especially of the regions with high density of the nucleosomes by elongation of the nucleosomal DNA. However, most of the nucleosome positions are conserved in the gene promoters, even after treatment with TSA, because of the low density of nucleosomes in the gene promoters

安定同位体比データをもちいた補食-被食ネットワークのモデル化

要旨あり生態学における統計モデリング研究詳

Utility of Nd isotope ratio as a tracer of marine animals : regional variation in coastal seas and causal factors

Isotopic compositions of animal tissue are an intrinsic marker commonly used to trace animal origins and migrations; however, few isotopes are effective for this purpose in marine environments, especially on a local scale. The isotope ratio of the lanthanoid element neodymium (Nd) is a promising tracer for coastal animal migrations. Neodymium derives from the same geologic materials as strontium, well known as an isotopic tracer (87Sr/86Sr) for terrestrial and anadromous animals. The advantage of the Nd isotope ratio (143Nd/144Nd, expressed as εNd) is that it varies greatly in the ocean according to the geology of the neighboring continents, whereas oceanic 87Sr/86Sr is highly uniform. This study explored the utility of the Nd isotope ratio as a marine tracer by investigating the variation of εNd preserved in tissues of coastal species, and the causes of that variation, in a region of northeastern Japan where the bedrock geology is highly variable. We measured εNd and 87Sr/86Sr in seawater, river water, and soft tissues of sedentary suspension feeders: the mussels Mytilus galloprovincialis and Mytilus coruscus and the oyster Crassostrea gigas. We also measured concentrations of three lanthanoids (La, Ce, and Pr) in shellfish bodies to determine whether the Nd in shellfish tissue was derived from solution in seawater or from suspended particulates. The εNd values in shellfish tissue varied regionally (−6 to +1), matching the ambient seawater, whereas all 87Sr/86Sr values were homogeneous and typical of seawater (0.7091–0.7092). The seawater εNd values were in turn correlated with those in the adjacent rivers, linking shellfish εNd to the geology of river catchments. The depletion of Ce compared to La and Pr (negative Ce anomaly) suggested that the Nd in shellfish was derived from the dissolved phase in seawater. Our results indicate that the distinct Nd isotope ratio derived from local geology is imprinted, through seawater, on the soft tissues of shellfish. This result underscores the potential of εNd as a tracer of coastal marine animals

Global diurnal and nocturnal parameters of stomatal conductance in woody plants and major crops

Altres ajuts: LIFE+ project FO3REST, Grant/Award Number: LIFE10 ENV/FR/208; LIFE+ project MOTTLES, Grant/Award Number: LIFE15 ENV/IT/000183Aim: stomata regulate CO₂ uptake, water-vapour loss and uptake of gaseous pollutants. Jarvis-type models that apply multiple-constraint functions are commonly used to estimate stomatal conductance (gs), but most parameters for plant functional types (PFTs) have been estimated using limited information. We refined the data set of key components of the gs response to environmental factors in global PFTs. - Location: global. - Time period: data published in 1973-2015. - Major taxa studied: woody plants and major crops (rice, wheat and maize). - Methods: we reviewed 235 publications of field-observed gs for the parameterization of Jarvis-type models in global PFTs. The relationships between stomatal parameters and climatic factors [mean annual air temperature (MAT) and mean annual precipitation (MAP)] were assessed. - Results: we found that maximal stomatal conductance (gmax) in global woody plants was correlated with MAP rather than with MAT. The gmax of woody plants on average increased from 0.18 to 0.26 mol/m²/s with an increase in MAP from 0 to 2,000 mm. Models, however, can use a single gmax across major crops (0.44 mol/m²/s). We propose similar stomatal responses to light for C₃ crops and woody plants, but C₄ crops should use a higher light saturation point of gs. Stomatal sensitivity to vapour-pressure deficit (VPD) was similar across forest PFTs and crops, although desert shrubs had a relatively low sensitivity of stomata to VPD. The optimal temperature for gs increased by 1 °C for every 3.0 °C of MAT. Stomatal sensitivity to predawn water potential was reduced in hot and dry climate. The fraction of nighttime conductance to gmax (0.14 for forest trees, 0.28 for desert shrubs and 0.13 for crops) should be incorporated into the models. - Main conclusions: this analysis of global gs data provides a new summary of gs responses and will contribute to modelling studies for plant-atmosphere gas exchange and land-surface energy partitioning

Collection of Macaca fascicularis cDNAs derived from bone marrow, kidney, liver, pancreas, spleen, and thymus

<p>Abstract</p> <p>Background</p> <p>Consolidating transcriptome data of non-human primates is essential to annotate primate genome sequences, and will facilitate research using non-human primates in the genomic era. <it>Macaca fascicularis </it>is a macaque monkey that is commonly used for biomedical and ecological research.</p> <p>Findings</p> <p>We constructed cDNA libraries of <it>Macaca fascicularis</it>, derived from tissues obtained from bone marrow, liver, pancreas, spleen, and thymus of a young male, and kidney of a young female. In total, 5'-end sequences of 56,856 clones were determined. Including the previously established cDNA libraries from brain and testis, we have isolated 112,587 cDNAs of <it>Macaca fascicularis</it>, which correspond to 56% of the curated human reference genes.</p> <p>Conclusion</p> <p>These sequences were deposited in the public sequence database as well as in-house macaque genome database <url>http://genebank.nibio.go.jp/qfbase/</url>. These data will become valuable resources for identifying functional parts of the genome of macaque monkeys in future studies.</p