The Inheritance of Histone Modifications Depends upon the Location in the Chromosome in Saccharomyces cerevisiae

Histone modifications are important epigenetic features of chromatin that must be replicated faithfully. However, the molecular mechanisms required to duplicate and maintain histone modification patterns in chromatin remain to be determined. Here, we show that the introduction of histone modifications into newly deposited nucleosomes depends upon their location in the chromosome. In Saccharomyces cerevisiae, newly deposited nucleosomes consisting of newly synthesized histone H3-H4 tetramers are distributed throughout the entire chromosome. Methylation of lysine 4 on histone H3 (H3-K4), a hallmark of euchromatin, is introduced into these newly deposited nucleosomes, regardless of whether the neighboring preexisting nucleosomes harbor the K4 mutation in histone H3. Furthermore, if the heterochromatin-binding protein Sir3 is unavailable during DNA replication, histone H3-K4 methylation is introduced onto newly deposited nucleosomes in telomeric heterochromatin. Thus, a conservative distribution model most accurately explains the inheritance of histone modifications because the location of histones within euchromatin or heterochromatin determines which histone modifications are introduced

Large-scale sampling and radioactivity analysis of agricultural soil and food during nuclear emergencies in Japan : Variations over time in foodstuffs inspection and sampling

The measurement of radioactivity in food and agricultural ecosystems is an essential task for keeping the population safe after a nuclear emergency. Prior to the Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in 2011, the probability of such an accident, combining complex effects of natural and technical factors, was not reflected in detail in national emergency preparedness guidelines. The lack of such guidelines resulted in a limited efficiency response to the Fukushima accident in agriculture. This outcome showed a need for the preparation of such guidelines as a part of emergency preparedness for nuclear and radiological emergences. This paper provides information and generic, non-country-specific guidance on approaches to sampling food. The paper is intended for scientists, policy makers and decision makers involved in nuclear emergency preparedness and responses, particularly on large scales and at different stages of nuclear emergency based on lessons learned from the FDNPP accident

Dynamics of suspended and dissolved radiocaesium in a small irrigation pond based on vertical water quality profiles

Following the Fukushima Daiichi Nuclear Power Plant accident, extensive research has been conducted on the dynamic distribution of radiocaesium in large reservoirs. However, studies on small ponds, particularly those used for rice cultivation, are limited. This study analyzed the vertical water quality profiles, including the bioavailable Caesium-137 (137Cs) in an irrigation small pond classified as discontinuous cold polymictic based on water mixing type, and subjected to a high (2.0 MBq m−2) deposition of 137Cs and evaluated their potential risk associated with agricultural use. During 2014–2015, the suspended and dissolved concentrations of 137Cs in the pond water ranged from 0.10 to 7.7 Bq L−1 and 0.03–0.88 Bq L−1, respectively. The elution of dissolved 137Cs from the bottom sediment occurred only during the summer when the water temperature exceeded 15 °C, NH4+ increased, and dissolved oxygen decreased. Except during flood inflow mixing events, the activity concentration of dissolved 137Cs in the bottom layer did not increase in the surface layer at depths ≤ 1.0 m. In a 3 m shallow pond without a well-defined thermocline, a gradual density stratification primarily occurred in the lower layer during summer, limiting the transport of dissolved 137Cs from the bottom to the surface layer. About 5 % of 137Cs in the suspended solids and bottom sediment are exchangeable, indicating the mica-rich soils and geological conditions with a high fixation capacity of 137Cs reduce the risk of 137Cs elution. Even after three to four years of considerable depositions, the risk of radiocaesium absorption by paddy rice and subsequent increase in radiocaesium concentration in brown rice was negligible as long as the surface water of the pond was used for agriculture

A Reduction in Age-Enhanced Gluconeogenesis Extends Lifespan

The regulation of energy metabolism, such as calorie restriction (CR), is a major determinant of cellular longevity. Although augmented gluconeogenesis is known to occur in aged yeast cells, the role of enhanced gluconeogenesis in aged cells remains undefined. Here, we show that age-enhanced gluconeogenesis is suppressed by the deletion of the tdh2 gene, which encodes glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a protein that is involved in both glycolysis and gluconeogenesis in yeast cells. The deletion of TDH2 restores the chronological lifespan of cells with deletions of both the HST3 and HST4 genes, which encode yeast sirtuins, and represses the activation of gluconeogenesis. Furthermore, the tdh2 gene deletion can extend the replicative lifespan in a CR pathway-dependent manner. These findings demonstrate that the repression of enhanced gluconeogenesis effectively extends the cellular lifespan