ABSTRACT We present distributions of two molecular clouds having velocities of 2 and 14 km s−1 toward RCW 38, the youngest super star cluster in the Milky Way, in the 12CO J = 1-0 and 3-2 and 13CO J ...= 1-0 transitions. The two clouds are likely physically associated with the cluster as verified by the high intensity ratio of the J = 3-2 emission to the J = 1-0 emission, the bridging feature connecting the two clouds in velocity, and their morphological correspondence with the infrared dust emission. The velocity difference is too large for the clouds to be gravitationally bound. We frame a hypothesis that the two clouds are colliding with each other by chance to trigger formation of the ∼20 O stars that are localized within ∼0.5 pc of the cluster center in the 2 km s−1 cloud. We suggest that the collision is currently continuing toward part of the 2 km s−1 cloud where the bridging feature is localized. This is the third super star cluster alongside Westerlund 2 and NGC 3603 where cloud-cloud collision has triggered the cluster formation. RCW 38 is the youngest super star cluster in the Milky Way, holding a possible sign of on-going O star formation, and is a promising site where we may be able to witness the moment of O star formation.
In mouse mammary epithelial cells, cytoplasmic polyadenylation element binding protein 1 (CPEB1) mediates the apical localization of ZO-1 mRNA, which encodes a critical tight junction component. In ...mice lacking CPEB1 and in cultured cells from which CPEB has been depleted, randomly distributed ZO-1 mRNA leads to the loss of cell polarity. We have investigated whether this diminution of polarity results in an epithelial-to-mesenchyme (EMT) transition and possible increased metastatic potential. Here, we show that CPEB1-depleted mammary epithelial cells alter their gene expression profile in a manner consistent with an EMT and also become motile, which are made particularly robust when cells are treated with transforming growth factor-β, an enhancer of EMT. CPEB1-depleted mammary cells become metastatic to the lung following injection into mouse fat pads while ectopically expressed CPEB1 prevents metastasis. Surprisingly, CPEB1 depletion causes some EMT/metastasis-related mRNAs to have shorter poly(A) tails while other mRNAs to have longer poly(A) tails. Matrix metalloproteinase 9 (MMP9) mRNA, which encodes a metastasis-promoting factor, undergoes poly(A) lengthening and enhanced translation upon CPEB reduction. Moreover, in human breast cancer cells that become progressively more metastatic, CPEB1 is reduced while MMP9 becomes more abundant. These data suggest that at least in part, CPEB1 regulation of MMP9 mRNA expression mediates metastasis of breast cancer cells.
Diabetes is associated with an increased risk of fracture, although type 2 diabetes is often characterized by normal bone mineral density (BMD). Enzymatic and glycation-induced non-enzymatic ...cross-links play important roles in the expression of bone strength. The serum vitamin B6 concentration is lower in patients with diabetes than in healthy controls. The aim our study was to see if spontaneously diabetic WBN/Kob rats in the pre- and post-onset of diabetes would serve as a suitable model for studying the pathogenesis of the susceptibility to fracture in diabetes without the reduction of bone mineral density. Seventy male WBN/Kob rats were obtained at the ages of 1 to 18 months.
Seventy normal male Wistar rats were used as the non-diabetic, age-matched control. The contents of enzymatic cross-links (dihydroxylysinonorleucine, hydroxylysinonorleucine, lysinonorleucine, pyridinoline and deoxypyridinoline) and non-enzymatic cross-links (pentosidine) were determined in femoral bone. We also analyzed the serum concentration of vitamin B6 (pyridoxal and pyridoxamine), femoral BMD and a three-point bending test of the femur.
A low level of serum vitamin B6 was associated with a decrease in enzymatic crosslinking in bone during the subclinical diabetes stage. After the onset of diabetes, there was a steady decrease in enzymatic cross-links and a steep increase in pentosidine. Furthermore, impaired bone mechanical properties in the WBN/Kob rats despite the lack of reduction in BMD coincided with impaired enzymatic cross-link formation and increases in glycation-induced pentosidine.
These results indicate that the alteration of enzymatic and non-enzymatic crosslinking in bone could be important for explaining the variation of fracture susceptibility in diabetes.
Cold-worked 316 stainless steel specimens irradiated to 74 dpa in a pressurized water reactor (PWR) were analyzed by atom probe tomography (APT) to extend knowledge of solute clusters and segregation ...at higher doses. The analyses confirmed that those clusters mainly enriched in Ni–Si or Ni–Si–Mn were formed at high number density. The clusters were divided into three types based on their size and Mn content; small Ni–Si clusters (3–4 nm in diameter), and large Ni–Si and Ni–Si–Mn clusters (8–10 nm in diameter). The total cluster number density was 7.7 × 1023 m−3. The fraction of large clusters was almost 1/10 of the total density. The average composition (in at%) for small clusters was: Fe, 54; Cr, 12; Mn, 1; Ni, 22; Si, 11; Mo, 1, and for large clusters it was: Fe, 44; Cr, 9; Mn, 2; Ni, 29; Si, 14; Mo,1. It was likely that some of the Ni–Si clusters correspond to γ′ phase precipitates while the Ni–Si–Mn clusters were precursors of G phase precipitates. The APT analyses at grain boundaries confirmed enrichment of Ni, Si, P and Cu and depletion of Fe, Cr, Mo and Mn. The segregation behavior was consistent with previous knowledge of radiation induced segregation.
Although numerous genetic studies have been conducted for bipolar disorder (BD), its genetic architecture remains elusive. Here we perform, to the best of our knowledge, the first trio-based exome ...sequencing study for BD to investigate potential roles of de novo mutations in the disease etiology. We identified 71 de novo point mutations and one de novo copy-number mutation in 79 BD probands. Among the genes hit by de novo loss-of-function (LOF; nonsense, splice site or frameshift) or protein-altering (LOF, missense and inframe indel) mutations, we found significant enrichment of genes highly intolerant (first percentile of intolerant genes assessed by Residual Variation Intolerance Score) to protein-altering variants in general population, an observation that is also reported in autism and schizophrenia. When we performed a joint analysis using the data of schizoaffective disorder in published studies, we found global enrichment of de novo LOF and protein-altering mutations in the combined group of bipolar I and schizoaffective disorders. Considering relationship between de novo mutations and clinical phenotypes, we observed significantly earlier disease onset among the BD probands with de novo protein-altering mutations when compared with non-carriers. Gene ontology enrichment analysis of genes hit by de novo protein-altering mutations in bipolar I and schizoaffective disorders did not identify any significant enrichment. These results of exploratory analyses collectively point to the roles of de novo LOF and protein-altering mutations in the etiology of bipolar disorder and warrant further large-scale studies.
Microstructural observation with atom probe tomography, transmission electron microscopy, and mechanical examination with a nano-indenter were performed on stainless steel model alloy that had been ...irradiated with Fe ions and subjected to post-irradiation annealing treatment (PIA). Significant irradiation hardening occurred in the as-irradiated specimen and irradiation hardening recovery occurred at 400 °C of cumulative PIA, Tiny black dots, Frank loops and Ni-Si clusters formed in the as-irradiated specimen and their recovery was observed with the cumulative PIA.
A classic dispersed-barrier hardening model was used to evaluate irradiation hardening connected to microstructural information by applying the density and size of defect variants. Ni-Si clusters and Frank loops contributed substantially to the increase of irradiation hardening, whereas the black dots contributed little for the stainless steel model alloy. The barrier strength factor of Ni-Si clusters, αSC, was obtained as 0.029 and 0.015 for two different obstacle strength model, which suggests that an individual Ni-Si cluster is a weak barrier obstacle to mobile dislocation on the dispersed-barrier hardening model, but that the dense formation of Ni-Si clusters controls irradiation hardening behavior. A quantitative analysis was performed of the increase in strength from the Ni-Si clusters that was caused by coherency strains, and an irradiation hardening mechanism for the stainless steel, including the solute atom clusters, is discussed.
Duplex stainless steel specimens embrittled by temperature-accelerated thermal aging at 400°C for 40,000h were irradiated at 300°C to 1dpa with 6.4MeV Fe3+ ions to study the effects of radiation on ...spinodal decomposition of ferrite. The microstructural change was examined by atom probe tomography, and the hardness change was measured with an ultra-micro hardness tester. Hardening of the ferrite in thermal aged specimens was reduced by irradiation, whereas the ferrite of the unaged specimen was hardened by it. The spinodal decomposition of the ferrite into Fe-rich α phase and Cr-rich α′ phase, and G-phase precipitation occurred after the thermal aging. Fluctuation of the Cr concentration based on the formation of Cr-rich α′ phase decrease by irradiation. This suggested that irradiation caused the disappearance of spinodal decomposition. The decrease in spinodal decomposition correlated with a decrease in hardness.
The isotope effect on energy confinement time and thermal transport has been investigated for plasmas confined by a stellarator-heliotron magnetic field. This is the first detailed assessment of an ...isotope effect in a stellarator heliotron. Hydrogen and deuterium plasmas heated by neutral beam injection on the Large Helical Device have exhibited no significant dependence on the isotope mass in thermal energy confinement time, which is not consistent with the simple gyro-Bohm model. A comparison of thermal diffusivity for dimensionally similar hydrogen and deuterium plasmas in terms of the gyroradius, collisionality, and thermal pressure has clearly shown robust confinement improvement in deuterium to compensate for the unfavorable mass dependence predicted by the gyro-Bohm model.
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