High-resolution reconstruction of late Pleistocene climate based on TOC content in a 54m sediment core drilled from Takano Formation, central Japan

The Takano Formation of late Pleistocene lacustrine sediment is distributed at the southern Nagano City. The TKN-2004 core, 53.88 m long, was taken at the central part or the basin, and is composed mostly or homogenous clayey silt. Age of the sediment was estimated from the relationship between radiometric ages and calibrated depths of DKP,Aso-4,K-Tz,Ata and Aso-2tephras, postulating that the sedimentation rate is constant.Paleoclimate from 169ka to 37ka was reconstructed on the basis of TOC content variation. The long-term TOC fluctuations are concordant with the SPECMAP curve. This result is supported by pollen composition. The short-term variations are similar to stadial-interstadial cycles in the Greenland ice cores, and most of warm peaks can be correlated with IS 9 to 25.長野市南部に分布する更新世後期の湖成層である高野層において,全層ボーリングを行い53.88mの連続したコア試料を得た.コア試料は,黒灰色ではぼ均質な粘土質シルト～シルトの層相を示し,多数のテフラ層を挟んでいる.これらのうち5つの広域指標テフラ(DKP,Aso-4,K-Tz, Ata,Aso-2)の放射年代値と補正深度を用いて年代モデルを作成した.高野層のTOC含有率の経年変動は,本コア試料中の花粉組成変化と同調しており,およそ169ka～37kaにおける数万年周期の長期の気候変動を示している.この変動はMIS 6-3前半における海洋酸素同位体比変動と同調しており,各ステージに対比される長期の温暖期･寒冷期が認識できた.また,数百～数千年周期の短期の寒暖変動も存在しており,これらは亜氷期-亜間氷期サイクルに相当すると考えられる.また,それらの温暖期の多くはIS9～25に対比される可能性がある.ArticleJournal of the Sedimentological Society of Japan. 64:37-41 (2007)journal articl

Electron-phonon renormalization of the absorption edge of the cuprous halides

Compared to most tetrahedral semiconductors, the temperature dependence of the absorption edges of the cuprous halides (CuCl, CuBr, CuI) is very small. CuCl and CuBr show a small increase of the gap $E_0$ with increasing temperature, with a change in the slope of $E_0$ vs. $T$ at around 150 K: above this temperature, the variation of $E_0$ with $T$ becomes even smaller. This unusual behavior has been clarified for CuCl by measurements of the low temperature gap vs. the isotopic masses of both constituents, yielding an anomalous negative shift with increasing copper mass. Here we report the isotope effects of Cu and Br on the gap of CuBr, and that of Cu on the gap of CuI. The measured isotope effects allow us to understand the corresponding temperature dependences, which we also report, to our knowledge for the first time, in the case of CuI. These results enable us to develop a more quantitative understanding of the phenomena mentioned for the three halides, and to interpret other anomalies reported for the temperature dependence of the absorption gap in copper and silver chalcogenides; similarities to the behavior observed for the copper chalcopyrites are also pointed out.Comment: 14 pages, 5 figures, submitted to Phys. Rev.

Common carotid intima media thickness and ankle-brachial pressure index correlate with local but not global atheroma burden:a cross sectional study using whole body magnetic resonance angiography

Common carotid intima media thickness (CIMT) and ankle brachial pressure index (ABPI) are used as surrogate marker of atherosclerosis, and have been shown to correlate with arterial stiffness, however their correlation with global atherosclerotic burden has not been previously assessed. We compare CIMT and ABPI with atheroma burden as measured by whole body magnetic resonance angiography (WB-MRA).50 patients with symptomatic peripheral arterial disease were recruited. CIMT was measured using ultrasound while rest and exercise ABPI were performed. WB-MRA was performed in a 1.5T MRI scanner using 4 volume acquisitions with a divided dose of intravenous gadolinium gadoterate meglumine (Dotarem, Guerbet, FR). The WB-MRA data was divided into 31 anatomical arterial segments with each scored according to degree of luminal narrowing: 0 = normal, 1 = <50%, 2 = 50-70%, 3 = 70-99%, 4 = vessel occlusion. The segment scores were summed and from this a standardized atheroma score was calculated.The atherosclerotic burden was high with a standardised atheroma score of 39.5±11. Common CIMT showed a positive correlation with the whole body atheroma score (β 0.32, p = 0.045), however this was due to its strong correlation with the neck and thoracic segments (β 0.42 p = 0.01) with no correlation with the rest of the body. ABPI correlated with the whole body atheroma score (β -0.39, p = 0.012), which was due to a strong correlation with the ilio-femoral vessels with no correlation with the thoracic or neck vessels. On multiple linear regression, no correlation between CIMT and global atheroma burden was present (β 0.13 p = 0.45), while the correlation between ABPI and atheroma burden persisted (β -0.45 p = 0.005).ABPI but not CIMT correlates with global atheroma burden as measured by whole body contrast enhanced magnetic resonance angiography in a population with symptomatic peripheral arterial disease. However this is primarily due to a strong correlation with ilio-femoral atheroma burden

Genetic mapping of natural variation in a shade avoidance response: ELF3 is the candidate gene for a QTL in hypocotyl growth regulation

When plants become shaded by neighbouring plants, they perceive a decrease in the red/far-red (R/FR) ratio of the light environment, which provides an early and unambiguous warning of the presence of competing vegetation. The mechanistic bases of the natural genetic variation in response to shade signals remain largely unknown. This study demonstrates that a wide range of genetic variation for hypocotyl elongation in response to an FR pulse at the end of day (EOD), a light signal that simulates natural shade, exists between Arabidopsis accessions. A quantitative trait locus (QTL) mapping analysis was done in the Bayreuth×Shahdara recombinant inbred line population. EODINDEX1 is the most significant QTL identified in response to EOD. The Shahdara alleles at EODINDEX1 caused a reduced response to shade as a consequence of an impaired hypocotyl inhibition under white light, and an accelerated leaf movement rhythm, which correlated positively with the pattern of circadian expression of clock genes such as PRR7 and PRR9. Genetic and quantitative complementation analyses demonstrated that ELF3 is the most likely candidate gene underlying natural variation at EODINDEX1. In conclusion, ELF3 is proposed as a component of the shade avoidance signalling pathway responsible for the phenotypic differences between Arabidopsis populations in relation to adaptation in a changing light environment

Targeted reprogramming of H3K27me3 resets epigenetic memory in plant paternal chromatin

Epigenetic marks are reprogrammed in the gametes to reset genomic potential in the next generation. In mammals, paternal chromatin is extensively reprogrammed through the global erasure of DNA methylation and the exchange of histones with protamines(1,2). Precisely how the paternal epigenome is reprogrammed in flowering plants has remained unclear since DNA is not demethylated and histones are retained in sperm(3,4). Here, we describe a multi-layered mechanism by which H3K27me3 is globally lost from histone-based sperm chromatin in Arabidopsis. This mechanism involves the silencing of H3K27me3 writers, activity of H3K27me3 erasers and deposition of a sperm-specific histone, H3.10 (ref. (5)), which we show is immune to lysine 27 methylation. The loss of H3K27me3 facilitates the transcription of genes essential for spermatogenesis and pre-configures sperm with a chromatin state that forecasts gene expression in the next generation. Thus, plants have evolved a specific mechanism to simultaneously differentiate male gametes and reprogram the paternal epigenome

Low Doses of Ionizing Radiation Promote Tumor Growth and Metastasis by Enhancing Angiogenesis

Radiotherapy is a widely used treatment option in cancer. However, recent evidence suggests that doses of ionizing radiation (IR) delivered inside the tumor target volume, during fractionated radiotherapy, can promote tumor invasion and metastasis. Furthermore, the tissues that surround the tumor area are also exposed to low doses of IR that are lower than those delivered inside the tumor mass, because external radiotherapy is delivered to the tumor through multiple radiation beams, in order to prevent damage of organs at risk. The biological effects of these low doses of IR on the healthy tissue surrounding the tumor area, and in particular on the vasculature remain largely to be determined. We found that doses of IR lower or equal to 0.8 Gy enhance endothelial cell migration without impinging on cell proliferation or survival. Moreover, we show that low-dose IR induces a rapid phosphorylation of several endothelial cell proteins, including the Vascular Endothelial Growth Factor (VEGF) Receptor-2 and induces VEGF production in hypoxia mimicking conditions. By activating the VEGF Receptor-2, low-dose IR enhances endothelial cell migration and prevents endothelial cell death promoted by an anti-angiogenic drug, bevacizumab. In addition, we observed that low-dose IR accelerates embryonic angiogenic sprouting during zebrafish development and promotes adult angiogenesis during zebrafish fin regeneration and in the murine Matrigel assay. Using murine experimental models of leukemia and orthotopic breast cancer, we show that low-dose IR promotes tumor growth and metastasis and that these effects were prevented by the administration of a VEGF receptor-tyrosine kinase inhibitor immediately before IR exposure. These findings demonstrate a new mechanism to the understanding of the potential pro-metastatic effect of IR and may provide a new rationale basis to the improvement of current radiotherapy protocols

PIF Genes Mediate the Effect of Sucrose on Seedling Growth Dynamics

As photoautotrophs, plants can use both the form and amount of fixed carbon as a measure of the light environment. In this study, we used a variety of approaches to elucidate the role of exogenous sucrose in modifying seedling growth dynamics. In addition to its known effects on germination, high-resolution temporal analysis revealed that sucrose could extend the number of days plants exhibited rapid hypocotyl elongation, leading to dramatic increases in ultimate seedling height. In addition, sucrose changed the timing of daily growth maxima, demonstrating that diel growth dynamics are more plastic than previously suspected. Sucrose-dependent growth promotion required function of multiple phytochrome-interacting factors (PIFs), and overexpression of PIF5 led to growth dynamics similar to plants exposed to sucrose. Consistent with this result, sucrose was found to increase levels of PIF5 protein. PIFs have well-established roles as integrators of response to light levels, time of day and phytohormone signaling. Our findings strongly suggest that carbon availability can modify the known photomorphogenetic signaling network

Enantioselective Phytotoxicity of the Herbicide Imazethapyr on the Response of the Antioxidant System and Starch Metabolism in Arabidopsis thaliana

Background: The enantiomers of a chiral compound possess different biological activities, and one of the enantiomers usually shows a higher level of toxicity. Therefore, the exploration of the causative mechanism of enantioselective toxicity is regarded as one of primary goals of biological chemistry. Imazethapyr (IM) is an acetolactate synthase (ALS)-inhibiting chiral herbicide that has been widely used in recent years with racemate. We investigated the enantioselectivity between R- and S-IM to form reactive oxygen species (ROS) and to regulate antioxidant gene transcription and enzyme activity. Results: Dramatic differences between the enantiomers were observed: the enantiomer of R-IM powerfully induced ROS formation, yet drastically reduced antioxidant gene transcription and enzyme activity, which led to an oxidative stress. The mechanism by which IM affects carbohydrate metabolism in chloroplasts has long remained a mystery. Here we report evidence that enantioselectivity also exists in starch metabolism. The enantiomer of R-IM resulted in the accumulation of glucose, maltose and sucrose in the cytoplasm or the chloroplast and disturbed carbohydrates utilization. Conclusion: The study suggests that R-IM more strongly retarded plant growth than S-IM not only by acting on ALS, but also by causing an imbalance in the antioxidant system and the disturbance of carbohydrate metabolism wit

REVEILLE8 and PSEUDO-REPONSE REGULATOR5 Form a Negative Feedback Loop within the Arabidopsis Circadian Clock

Circadian rhythms provide organisms with an adaptive advantage, allowing them to regulate physiological and developmental events so that they occur at the most appropriate time of day. In plants, as in other eukaryotes, multiple transcriptional feedback loops are central to clock function. In one such feedback loop, the Myb-like transcription factors CCA1 and LHY directly repress expression of the pseudoresponse regulator TOC1 by binding to an evening element (EE) in the TOC1 promoter. Another key regulatory circuit involves CCA1 and LHY and the TOC1 homologs PRR5, PRR7, and PRR9. Purification of EE–binding proteins from plant extracts followed by mass spectrometry led to the identification of RVE8, a homolog of CCA1 and LHY. Similar to these well-known clock genes, expression of RVE8 is circadian-regulated with a dawn phase of expression, and RVE8 binds specifically to the EE. However, whereas cca1 and lhy mutants have short period phenotypes and overexpression of either gene causes arrhythmia, rve8 mutants have long-period and RVE8-OX plants have short-period phenotypes. Light input to the clock is normal in rve8, but temperature compensation (a hallmark of circadian rhythms) is perturbed. RVE8 binds to the promoters of both TOC1 and PRR5 in the subjective afternoon, but surprisingly only PRR5 expression is perturbed by overexpression of RVE8. Together, our data indicate that RVE8 promotes expression of a subset of EE–containing clock genes towards the end of the subjective day and forms a negative feedback loop with PRR5. Thus RVE8 and its homologs CCA1 and LHY function close to the circadian oscillator but act via distinct molecular mechanisms

Reference values of whole-blood fatty acids by age and sex from European children aged 3-8 years

OBJECTIVES: To establish reference values for fatty acids (FA) especially for n-3 and n-6 long-chain polyunsaturated FAs (LC PUFA) in whole-blood samples from apparently healthy 3-8-year-old European children. The whole-blood FA composition was analysed and the age-and sex-specific distribution of FA was determined. DESIGN AND SUBJECTS: Blood samples for FA analysis were taken from 2661 children of the IDEFICS (identification and prevention of dietary-and lifestyle-induced health effects in children and infants) study cohort. Children with obesity (n = 454) and other diseases that are known to alter the FA composition (n = 450) were excluded leaving 1653 participants in the reference population. MEASUREMENTS: The FA composition of whole blood was analysed from blood drops by a rapid, validated gas chromatographic method. RESULTS: Pearson correlation coefficients showed an age-dependent increase of C18:2n-6 and a decrease of C18:1n-9 in a subsample of normal weight boys and girls. Other significant correlations with age were weak and only seen either in boys or in girls, whereas most of the FA did not show any age dependence. For age-dependent n-3 and n-6 PUFA as well as for other FA that are correlated with age (16:0, C18:0 and C18:1n-9) percentiles analysed with the general additive model for location scale and shape are presented. A higher median in boys than in girls was observed for C20:3n-6, C20:4n-6 and C22:4n-6. CONCLUSIONS: Given the reported associations between FA status and health-related outcome, the provision of FA reference ranges may be useful for the interpretation of the FA status of children in epidemiological and clinical studies