Celf1 Is Required for Formation of Endoderm-Derived Organs in Zebrafish

We recently reported that an RNA binding protein called Cugbp Elav-like family member 1 (Celf1) regulates somite symmetry and left-right patterning in zebrafish. In this report, we show additional roles of Celf1 in zebrafish organogenesis. When celf1 is knocked down by using an antisense morpholino oligonucleotides (MO), liver buds fail to form, and pancreas buds do not form a cluster, suggesting earlier defects in endoderm organogenesis. As expected, we found failures in endoderm cell growth and migration during gastrulation in embryos injected with celf1-MOs. RNA immunoprecipitation revealed that Celf1 binds to gata5 and cdc42 mRNAs which are known to be involved in cell growth and migration, respectively. Our results therefore suggest that Celf1 regulates proper organogenesis of endoderm-derived tissues by regulating the expression of such targets.     

Antiviral activity of silver nanoparticle/chitosan composites against H1N1 influenza A virus

Silver nanoparticle (Ag NP)/chitosan (Ch) composites with antiviral activity against H1N1 influenza A virus were prepared. The Ag NP/Ch composites were obtained as yellow or brown floc-like powders following reaction at room temperature in aqueous medium. Ag NPs (3.5, 6.5, and 12.9 nm average diameters) were embedded into the chitosan matrix without aggregation or size alternation. The antiviral activity of the Ag NP/Ch composites was evaluated by comparing the TCID₅₀ ratio of viral suspensions treated with the composites to untreated suspensions. For all sizes of Ag NPs tested, antiviral activity against H1N1 influenza A virus increased as the concentration of Ag NPs increased; chitosan alone exhibited no antiviral activity. Size dependence of the Ag NPs on antiviral activity was also observed: antiviral activity was generally stronger with smaller Ag NPs in the composites. These results indicate that Ag NP/Ch composites interacting with viruses exhibit antiviral activity.     

Electronic properties of calcined materials from a scandium-O-phenylene-O-yttrium-O-phenylene hybrid copolymer

Calcination of a scandium-O-phenylene-O-yttrium-O-phenylene hybrid copolymer under an argon atmosphere at 400–800 °C was performed. The calcined materials were found to be composed of nano-sized Sc₂O₃ and Y₂O₃ particles in the matrix of carbon clusters. ESR spectral examinations of the calcined materials suggest that a two-step electron transfer of Y₂O₃ → carbon clusters → Sc₂O₃ → carbon clusters took place to provide a photo-responsive oxidation–reduction function with an oxidation site at Y₂O₃ particles and a reduction site at carbon clusters.     

Effects of undersized Fe atoms on the stability of interstitials near a dislocation core in V studied by molecular dynamics simulation

It is well-known that the dislocation bias should be responsible for the large swelling. In V-Fe alloys, the extremely large swelling has been observed, which indicates that undersized Fe atoms must play a significant role for the modification of one-dimensional (1D) motion. In the present study, we performed molecular dynamics (MD) simulations with a newly constructed empirical potential based on the Finnis-Sinclair (FS) type embedded atom method (EAM) to investigate the effects of undersized Fe atoms on the static and dynamic properties of the interstitial migration under the strain field of several sizes of interstitial loops and an edge dislocation. The results show that the undersized Fe atoms tend to form a stable mixed-dumbbell configuration and the activation energy of migration towards a dislocation core is much lower than that of SIAs. Moreover, for V-Fe dumbbell the relative probability for intermediate configurations between 〈111〉-crowdion and 〈110〉-dumbbell below an edge dislocation core becomes significantly higher compared to that of V-V dumbbell. These results indicate that it is very likely that the continuous absorption of interstitial Fe atoms by a dislocation core would be possible and enhances the swelling in V-Fe alloys.     

Sensorless control of SRM based on a simple expression of magnetization characteristics

Switched reluctance motors (SRM) have a simpler and more rugged construction than conventional ac motors, and hence are suitable for low‐cost variable‐speed drives in many industrial applications. However, the need to use a traditional position sensor for their control is one of the disadvantages of SRM from the standpoints of cost, size, and reliability. For practical use, there is a need for sensorless drive of SRM. This paper describes position‐sensorless control of SRM based on a simple expression of their nonlinear magnetization characteristics. Successful experiments using a 1.5‐kW, 5400‐rpm SRM with a 6/4 pole configuration have verified the practicability of the proposed sensorless control scheme. © 2001 Scripta Technica, Electr Eng Jpn, 137(2): 52–60, 2001     

Activation-induced apoptosis of mature T cells is dependent upon the level of surface TCR but not on the presence of the CD3 zeta ITAM

Activation-induced cell death (AICD) occurs primarily in recently activated T cells after a second TCR triggering. Since a threshold in the activation status may be critical for AICD, it is likely that the CD3 ITAM, docking sites for tyrosine kinases, regulate AICD. A 'threshold model' for AICD was tested by using two targeted mutant mouse strains lacking either the zeta chain (CD3zeta-/-) or the ITAM of the zeta chain (CD3zeta-/-:Tgzetadelta67-150). Although the T cells from the CD3zeta-/- mice express extremely low levels of surface TCR, a subpopulation (approximately 18%) of activated T cells could be induced to express TCR/FcepsilonRI gamma by using a powerful polyclonal activation protocol. These activated TCR/FcRI gamma T cells were capable of undergoing AICD, but its induction required 10 times as much anti-CD3epsilon mAb as that required for AICD of wild-type T cells. Thus, the intensity of AICD correlated with the level of CD3 expression and was less efficient with activated, CD3zeta(-/-)-derived T cells. By contrast, AICD of T cells from the CD3zeta-/-:Tgzetadelta67-150 mice could be induced with low doses of anti-CD3epsilon mAb and the extent of AICD was comparable to T cells from wild-type mice. The AICD induced in T cells from CD3-/-, CD3zeta-/-:Tgzetadelta67-150 and normal controls was specifically inhibited by Fas-Ig fusion proteins. Our data support the 'threshold model' of AICD by demonstrating that AICD is controlled by the strength of T cell activation.     

Evidence for linkage between the development of asthma in childhood and the T-cell receptor beta chain gene in Japanese

GTPase-activating proteins (GAPs) stimulate the hydrolysis of GTP bound to small G-proteins and regulate the signal transduction pathway. Changes in the expression of p21-Ras p120-GAP induced by growth factor treatment were examined in cultured Chinese hamster ovary (CHO) and human choriocarcinoma (BeWo) cells. Expression of p120-GAP and GAP activity were measured. Fetal bovine serum induced a significant increased level of GAP in CHO cells, but did not increase GAP in BeWo cells. The results suggest that growth factors affect Ras GAP expression in CHO cells, while they do not in other cells such as BeWo cells.     

Effect of starting material on normal-pressure synthesis of 124 superconductor Y1-xCaxBa2Cu4O8

Successful synthesis of the 124 high-Tc superconductor Y1-xCaxBa2Cu4O8 at ambient oxygen pressure is reported. A solid-state reaction technique using Cu(I)I instead of the conventional Cu(II)O in starting materials has been found to be effective for the normal oxygen-pressure synthesis of YBa2Cu4O8 as well as calcium-substituted Y1-xCaxBa2Cu4O8. It was found that careful attention must be paid in preparing high-quality Y1-xCaxBa2Cu4O8. The chemical state of the initial calcium compound was a critical factor in the successful synthesis of Y1-xCaxBa2Cu4O8 at ambient oxygen pressure. © 1998 Chapman & Hall.     

Identification of a putative target for Rho as the serine-threonine kinase protein kinase N

Rho, a Ras-like small guanosine triphosphatase, has been implicated in cytoskeletal responses to extracellular signals such as lysophosphatidic acid (LPA) to form stress fibers and focal contacts. The form of RhoA bound to guanosine triphosphate directly bound to and activated a serine-threonine kinase, protein kinase N (PKN). Activated RhoA formed a complex with PKN and activated it in COS-7 cells. PKN was phosphorylated in Swiss 3T3 cells stimulated with LPA, and this phosphorylation was blocked by treatment of cells with botulinum C3 exoenzyme. Activation of Rho may be linked directly to a serine-threonine kinase pathway.