Noble Gases in the Chelyabinsk Meteorites

The Chelyabinsk meteorite fell in Russia on February 15, 2013 and was classified as LL5 chondrite. The diameter before it entered the atmosphere has been estimated to be about 20 m [1]. Up to now, numerous fragments weighing much greater than 100 kg in total have been collected. In this study, all noble gases were measured for 13 fragments to investigate the exposure history of the Chelyabinsk meteorite and the thermal history of its parent asteroid

Multiple roles of PPAR alpha in brown adipose tissue under constitutive and cold conditions

Peroxisome proliferator-activated receptor alpha (PPAR alpha) is a member of the nuclear receptor family, regulating fatty acid degradation in many organs. Two-dimensional SDS-PAGE of brown adipose tissue (BAT) from PPAR alpha-null mice produced a higher-density spot. Proteomic analysis indicated that the protein was pyruvate dehydrogenase beta (PDH beta). To observe PDH beta regulation in BAT, the organ was stimulated by long-term cold exposure, and the activities of associated enzymes were investigated. Histological and biochemical analyses of BAT showed a significant decrease in the triglyceride content in wild-type mice and some degree of decrease in PPAR alpha-null mice on cold exposure. Analyses of molecules related to glucose metabolism showed that the expression of PDH beta is under PPAR alpha-specific regulation, and that glucose degradation ability may decrease on cold exposure. In contrast, analyses of molecules related to fatty acid metabolism showed that numerous PPAR alpha/gamma target molecules are induced on cold exposure, and that fatty acid degradation ability in wild-type mice is markedly enhanced and also increases to same degree in PPAR alpha-null mice on cold exposure. Thus, this study proposes novel and multiple roles of PPAR alpha in BAT.ArticleGENES TO CELLS. 15(2):91-100 (2010)journal articl

The double-stranded break-forming activity of plant SPO11s and a novel rice SPO11 revealed by a Drosophila bioassay

<p>Abstract</p> <p>Background</p> <p>SPO11 is a key protein for promoting meiotic recombination, by generating chromatin locus- and timing-specific DNA double-strand breaks (DSBs). The DSB activity of SPO11 was shown by genetic analyses, but whether SPO11 exerts DSB-forming activity by itself is still an unanswered question. DSB formation by SPO11 has not been detected by biochemical means, probably because of a lack of proper protein-folding, posttranslational modifications, and/or specific SPO11-interacting proteins required for this activity. In addition, plants have multiple SPO11-homologues.</p> <p>Results</p> <p>To determine whether SPO11 can cleave DNA by itself, and to identify which plant SPO11 homologue cleaves DNA, we developed a <it>Drosophila </it>bioassay system that detects the DSB signals generated by a plant SPO11 homologue expressed ectopically. We cytologically and genetically demonstrated the DSB activities of <it>Arabidopsis </it>AtSPO11-1 and AtSPO11-2, which are required for meiosis, in the absence of other plant proteins. Using this bioassay, we further found that a novel SPO11-homologue, OsSPO11D, which has no counterpart in <it>Arabidopsis</it>, displays prominent DSB-forming activity. Quantitative analyses of the rice SPO11 transcripts revealed the specific increase in OsSPO11D mRNA in the anthers containing meiotic pollen mother cells.</p> <p>Conclusions</p> <p>The <it>Drosophila </it>bioassay system successfully demonstrated that some plant SPO11 orthologues have intrinsic DSB activities. Furthermore, we identified a novel SPO11 homologue, OsSPO11D, with robust DSB activity and a possible meiotic function.</p

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A model relating transpiration for Japanese cedar and cypress plantations with stand structure

Previous studies have revealed that changes in forest structure due to management (e.g., thinning, aging, and clearcutting) could affect the forest water balance. However, there are unexplained variability in changes in the annual water balance with changing structure among different sites. This is the case even when analyzing data for specific species/regions. For a more advanced and process-based understanding of changes in the water balance with changing forest structure, we examined transpiration (E) observed using the sap-flux method for 14 Japanese cedar and cypress plantations with various structure (e.g., stem density and diameter) in Japan and surrounding areas and developed a model relating E with structural parameters. We expressed E using the simplified Penman–Monteith equation and modeled canopy conductance (G[c]) as a product of reference G[c] (G[cref]) when vapor pressure deficit is 1.0 kPa and functions expressing the responses of G[c] to meteorological factors. We determined G[cref] and parameters of the functions for the sites separately. E observed for the 14 sites was not reproduced well by the model when using mean values of G[cref] and the parameters among the sites. However, E observed for the sites was reproduced well when using G[cref] determined for each site and mean values of the parameters of the functions among the sites, similar to the case when using G[cref] and the parameters of the functions determined for each site. These results suggest that considering variations in G[cref] among the sites was important to reproduce variations in E, but considering variations in the parameters of the functions was not. Our analysis revealed that G[cref] linearly related with the sapwood area on a stand scale (A) and that Alinearly related with stem density (N) and powers of the mean stem diameter (d[m]). Thus, we proposed a model relating E with A (or N and d[m]), where G[cref] was calculated from A (or N and d[m]) and the parameters of the functions were assumed to be the mean values among the sites. This model estimates changes in Ewith changing structure from commonly available data (N and d[m]), and therefore helps improve our understanding of the underlying processes of the changes in the water balance for Japanese cedar and cypress plantations