An experimental study of dynamic characteristics of labyrinth seal

The fluid force due to labyrinth seal sometimes makes the turbomachineries unstable under higher rotating speed, higher pressure and higher power. Therefore, it is important to predict the magnitude and the direction of the fluid force and to evaluate the stability of the rotor system in design process. This paper shows the experimental results of the fluid force induced by a straight labyrinth seal and the rotordynamic coefficients calculated from the fluid force. Influences of the number of fins under the rotating speed, whirling speed, inlet pressure, and inlet tangential velocity are mainly investigated on a stability of the rotor system. The results show that increase of the number of fins makes the fluid force small and the rotor system stable, an increase of inlet pressure makes the fluid forces large and an increase of inlet tangential velocity makes the rotor system unstable

Exhaustion of nucleus pulposus progenitor cells with ageing and degeneration of the intervertebral disc.

Despite the high prevalence of intervertebral disc disease, little is known about changes in intervertebral disc cells and their regenerative potential with ageing and intervertebral disc degeneration. Here we identify populations of progenitor cells that are Tie2 positive (Tie2+) and disialoganglioside 2 positive (GD2+), in the nucleus pulposus from mice and humans. These cells form spheroid colonies that express type II collagen and aggrecan. They are clonally multipotent and differentiated into mesenchymal lineages and induced reorganization of nucleus pulposus tissue when transplanted into non-obese diabetic/severe combined immunodeficient mice. The frequency of Tie2+ cells in tissues from patients decreases markedly with age and degeneration of the intervertebral disc, suggesting exhaustion of their capacity for regeneration. However, progenitor cells (Tie2+GD2+) can be induced from their precursor cells (Tie2+GD2-) under simple culture conditions. Moreover, angiopoietin-1, a ligand of Tie2, is crucial for the survival of nucleus pulposus cells. Our results offer insights for regenerative therapy and a new diagnostic standard

Insulin-Deficient Diabetic Condition Upregulates the Insulin-Secreting Capacity of Human Induced Pluripotent Stem Cell-Derived Pancreatic Endocrine Progenitor Cells After Implantation in Mice

The host environment is a crucial factor for considering the transplant of stem cell–derived immature pancreatic cells in patients with type 1 diabetes. Here, we investigated the effect of insulin (INS)-deficient diabetes on the fate of immature pancreatic endocrine cell grafts and the underlying mechanisms. Human induced pluripotent stem cell–derived pancreatic endocrine progenitor cells (EPCs), which contained a high proportion of chromogranin A⁺ NK6 homeobox 1⁺ cells and very few INS⁺ cells, were used. When the EPCs were implanted under the kidney capsule in immunodeficient mice, INS-deficient diabetes accelerated increase in plasma human C-peptide, a marker of graft-derived INS secretion. The acceleration was suppressed by INS infusion but not affected by partial attenuation of hyperglycemia by dapagliflozin, an INS-independent glucose-lowering agent. Immunohistochemical analyses indicated that the grafts from diabetic mice contained more endocrine cells including proliferative INS-producing cells compared with that from nondiabetic mice, despite no difference in whole graft mass between the two groups. These data suggest that INS-deficient diabetes upregulates the INS-secreting capacity of EPC grafts by increasing the number of endocrine cells including INS-producing cells without changing the graft mass. These findings provide useful insights into postoperative diabetic care for cell therapy using stem cell–derived pancreatic cells

Complementary Genes That Cause Black Ripening Hulls in F1 Plants of Crosses between Indica and Japonica Rice Cultivars

The F1 plants of crosses between indica and japonica rice cultivars often have black hulls during ripening, even though both of the parental cultivars have yellow hulls. Complementary genes are suggested to be necessary for the black hull phenotype, and one of them is predicted to be Phr1, which encodes polyphenol oxidase. On the other hand, Bh4, which encodes a tyrosine transporter, is known to cause the black hull phenotype in wild rice species, Oryza rufipogon. However, the relationship between Bh4 and Phr1 in the black hull phenotype has not been elucidated. In this study, a genotype analysis of the segregating populations from the cross between an indica cultivar, Habataki, and a japonica cultivar, Arroz da Terra, indicated that only those plants that had both functional genes, Bh4 and Phr1, showed the black hull phenotype, suggesting that a complementarity of Bh4 and Phr1 was necessary for the black hull phenotype

Characterization and reduction of non-endocrine cells accompanying islet-like endocrine cells differentiated from human iPSC

ヒトiPS細胞から作製した膵島様細胞に混入する目的外細胞の特性評価にもとづく除去. 京都大学プレスリリース. 2022-04-07.Elimination of non-target cells mixed into islet-like cells generated from human iPS cells based on characterization. 京都大学プレスリリース. 2022-04-15.The differentiation of pancreatic endocrine cells from human pluripotent stem cells has been thoroughly investigated for their application in cell therapy against diabetes. Although non-endocrine cells are inevitable contaminating by-products of the differentiation process, a comprehensive profile of such cells is lacking. Therefore, we characterized non-endocrine cells in iPSC-derived pancreatic islet cells (iPIC) using single-cell transcriptomic analysis. We found that non-endocrine cells consist of (1) heterogeneous proliferating cells, and (2) cells with not only pancreatic traits but also liver or intestinal traits marked by FGB or AGR2. Non-endocrine cells specifically expressed FGFR2, PLK1, and LDHB. We demonstrated that inhibition of pathways involving these genes selectively reduced the number of non-endocrine cells in the differentiation process. These findings provide useful insights into cell purification approaches and contribute to the improvement of the mass production of endocrine cells for stem cell-derived cell therapy for diabetes

Effect of Introducing Nematode-Resistant Sweet Potato Cultivars on Crop Productivity and Nematode Density in Sweet Potato-Radish Double-Cropping Systems

The root-knot nematode (RKN) is a significant pest in upland farming. We studied the effects of introducing nematode-resistant sweet potato cultivars on crop yield, crop quality, and RKN population dynamics in sweet potato-radish double-cropping systems. Three cropping systems with and without nematicide treatment (6 systems in total) were arranged for a 4-yr field experiment from 2003 to 2006. In two nematode-suppressive cropping systems, highly nematode-resistant J-red, (J) or Sunny red (S) and moderately nematode-resistant Kyushu No. 139 (K139) or Murasakimasari (M) sweet potato cultivars were cropped in alternate years beginning with the former and the latter, and in the non-nematode-suppressive cropping system, nematode-susceptible Kokei No. 14 (K14) and M were cropped in alternate years beginning with the former, from 2003 to 2005. In all cropping systems, K14 was cropped in 2006 to estimate the nematode-suppressive effect of the preceding 3-yr cropping. Introduction of J and S to the cropping system decreased the number of RKNs. In 2006, the extent of injury of K14 was decreased in nematode-suppressive cropping systems. The RKN population density, however, recovered during the cropping of K14 even after cropping of J or S or after nematicide treatment. This suggests that the effects of these measures last for only 1 yr. Nematode injury in radish decreased after nematicide treatment and after cropping of highly nematode-resistant J or S. These results indicate that the introduction of nematode-resistant sweet potato cultivars in cropping systems is effective for reduction of agrochemical use for sustainable agriculture

Detection of Chromosomal Regions Affecting Iron Concentration in Rice Shoots Subjected to Excess Ferrous Iron Using Chromosomal Segment Substitution Lines betweenJaponica and Indica

Excess ferrous iron in lowland soil is known to inhibit the growth of rice. A quantitative trait locus (QTL) analysis for susceptibility to ferrous iron was performed using chromosomal segments substitution lines (CSSLs). Kasalath, an indica rice cultivar, is known to be susceptible to ferrous iron and accumulate excess iron in shoots. The shoot iron concentration was examined in 39 CSSLs carrying Kasalath chromosomal segments in a background of Koshihikari, a japonica cultivar. Kasalath grown in a hydroponic culture solution containing excess ferrous iron, had a higher shoot iron concentration than Koshihikari. Of the CSSLs, SL208, which carries the Kasalath chromosomal segment on chromosome 3, had a significantly higher shoot iron concentration than Koshihikari, and none of the CSSLs had a shoot iron concentration significantly lower than Koshihikari. This finding suggests that the putative QTL affecting the shoot iron concentration is between the markers R663 and S1571 on chromosome 3

QTLs for Seedling Growth of Direct Seeded Rice under Submerged and Low Temperature Conditions

Quantitative trait loci (QTL) affecting the germination rate, coleoptile length, and shoot dry weight were analyzed under submerged and low temperature conditions using inbred lines derived from crossing the rice cultivars Ouu 365 and Arroz da Terra. The QTLs that increased the germination rate and shoot dry weight by Arroz da Terra allele were detected on the same region of chromosome 3, where the low temperature germinability gene, qLTG3-1, localized, suggesting that greater germinability might lead to increased shoot growth in paddy fields. The QTLs that increased the coleoptile length by Ouu 365 and Arroz da Terra alleles were detected on chromosome 8 and 11, respectively. The analysis of the known germinability genes suggested that functional allele of qLTG3-1 increased germination rates of the inbred lines. However, Rc which induced red pigmentation in pericarp declined the germination rates of the lines with functional qLTG3-1