Appearance of Antiferromagnetic Dipole Order in Ce0.5La0.5B6 with Pr Ion Doping

We have performed a neutron diffraction experiment on Pr-doped Ce0.5Pr0.1La0.4B6, in which an antiferromagnetic octupole order with q = ( 1/2, 1/2, 1/2 ) could be anticipated by analogy with Ce0.7La0.3B6. Contrary to this natural expectation, we detected an unambiguous magnetic peak at q = ( 1/4, 1/4, 1/2 ), which is the same q-vector frequently realized in the magnetic ordered phases of RB6 (R=rare earth) compounds. No significant signal was observed at q = (1/2, 1/2, 1/2 ) at zero magnetic field. This result shows that the normal antiferromagnetic dipole moment is also one of the competing multipole order parameters in the CexLa1－xB6 system. The relevant order parameters are close in energy and can be tuned by a weak perturbation.This work was supported by Grants-in-Aid for Scientific Research (Nos. 21204456, 21102515, and 2430087) from JSPS and MEXT

On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective

Presented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned from the C-type asteroid Ryugu by the Hayabusa2 mission. On average Ryugu particles consist of 50% phyllosilicate matrix, 41% porosity and 9% minor phases, including organic matter. The abundances of 70 elements from the particles are in close agreement with those of CI chondrites. Bulk Ryugu particles show higher δ18O, Δ17O, and ε54Cr values than CI chondrites. As such, Ryugu sampled the most primitive and least-thermally processed protosolar nebula reservoirs. Such a finding is consistent with multi-scale H-C-N isotopic compositions that are compatible with an origin for Ryugu organic matter within both the protosolar nebula and the interstellar medium. The analytical data obtained here, suggests that complex soluble organic matter formed during aqueous alteration on the Ryugu progenitor planetesimal (several 10’s of km), <2.6 Myr after CAI formation. Subsequently, the Ryugu progenitor planetesimal was fragmented and evolved into the current asteroid Ryugu through sublimation

A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample

Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition

A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss

Analysis of mutants that suppressed oil degradation under dark conditions

For biofuel production by micoralgae, it is important to improve the algae to high biomass or oil contents strain. In this study, we focused on alkenones, as biofuel candidate, that are very-long-alkyl ketones and are only known in five haptophyte species. We selected one of the alkenone-producing haptophytes, Tisochrysis lutea, to mutate by heavy ion beam irradiation that is known as a good method to obtain useful mutants. In addition, the mutants obtained by this method can be applicable in open system as non-GMO. So far, we have selected high oil-producing strains from fluorescence intensity of lipids by lipid staining with Nile red regent. It is considered that these high oil-producing strains will have features such as, high photosynthetic activity, high growth rate, high ratio to lipid in intracellular carbon or suppression of lipid degradation. Here, we screened and analyzed the strains which are suppressed alkenone degradation.Alkenone is known to degrade as energy source like polysaccharides under dark condition. Therefore, we stained intracellular neutral lipids with Nile red regent and monitored fluorescence intensity of stained lipids under dark condition by using microplate reader. First, we cultured selected high oil-producing strains with 96-well plate for 2 weeks and then put them in dark condition for 1 week. When we compared fluorescence intensity of lipids before and after 1 week dark condition, we observed little decrease in fluorescence intensity from 72 strains. Second, we cultured selected 31 of 72 strains with plastic flask for the analysis of alkenone amounts by GC-FID. From the results, we obtained 4 candidate strains as which are suppressed alkenone degradation under dark condition. Finally, we checked time course of several component, such as polysaccharides, protein, polar and non-polar lipids under dark condition. After dark condition, polysaccharides were immediately degraded and over 80% were degraded within 1 week. Degradation of alkenone was started 2 days after dark condition in wild-type but 7 days or later after dark condition in candidate strains. It is suggested the possibility that not only alkenone degrading enzyme but also dark-acclimation to lipid metabolism are changed in these strains.Marine Biotechnology Conference 201

Premature Termination of Reprogramming In Vivo Leads to Cancer Development through Altered Epigenetic Regulation

SummaryCancer is believed to arise primarily through accumulation of genetic mutations. Although induced pluripotent stem cell (iPSC) generation does not require changes in genomic sequence, iPSCs acquire unlimited growth potential, a characteristic shared with cancer cells. Here, we describe a murine system in which reprogramming factor expression in vivo can be controlled temporally with doxycycline (Dox). Notably, transient expression of reprogramming factors in vivo results in tumor development in various tissues consisting of undifferentiated dysplastic cells exhibiting global changes in DNA methylation patterns. The Dox-withdrawn tumors arising in the kidney share a number of characteristics with Wilms tumor, a common pediatric kidney cancer. We also demonstrate that iPSCs derived from Dox-withdrawn kidney tumor cells give rise to nonneoplastic kidney cells in mice, proving that they have not undergone irreversible genetic transformation. These findings suggest that epigenetic regulation associated with iPSC derivation may drive development of particular types of cancer