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Recent genome-wide association studies demonstrated that common variants of solute carrier family 30 member 8 gene (SLC30A8) increase susceptibility to type 2 diabetes. SLC30A8 encodes zinc transporter-8 (ZnT8), which delivers [...]

Grb2-associated binder (Gab) family of scaffolding adaptor proteins coordinate signaling cascades downstream of growth factor and cytokine receptors. In the heart, among EGF family members, neuregulin-1[beta] (NRG-1[beta], a paracrine factor [...]

Patients with Omenn syndrome (OS) have hypomorphic RAG mutations and develop varying manifestations of severe combined immunodeficiency. It is not known which symptoms are caused directly by the RAG mutations [...]

Direct lubrication tilting pad journal bearings (DLTPJ bearings) have rarely been applied to large-scale rotating machinery, such as turbines or generators, whose journal diameters are more than 500 mm. In this paper, static and dynamic characteristics of a 580 mm (22.8 in.) diameter DLTPJ bearing were studied experimentally using a full-scale bearing test rig. In the static test, distribution of metal temperature, oil film pressure, and bearing loss were measured in changing oil flow rate, with mean bearing pressure ranging up to 2.9 MPa. The maximum metal temperature of the DLTPJ bearing was compared to that of a conventional flood lubrication bearing, and it was confirmed that the direct lubrication could increase load capacity. In the dynamic test, spring and damping coefficients of oil film were obtained by exciting the bearing casing that was floated by air bellows. These data will be used for analysis and design of steam turbine rotors and their bearing systems. Also, vibration of pads was investigated because metal failure on upper pads due to vibration has been found in some actual machines. In order to generate oil film pressure on the surface of upper pads, a Rayleigh-step was machined there, and it was confirmed that vibration was reduced by the Rayleigh-step. [DOI: 10.1115/1.2114929] Keywords: direct lubrication, tilting pad journal bearing, static characteristics, dynamic characteristics, Rayleigh-step

Labyrinth seals are used in various kinds of turbo machines to reduce internal leakage flow. The working fluid, or the gas passing through the rotor shaft labyrinth seals, often generates driving force components that may increase the unstable vibration of the rotor. It is important to know the accurate rotordynamic force components for predicting the instability of the rotor-bearing-seal system. The major goals of this research were to calculate the rotordynamic force of a labyrinth seals utilizing a commercial CFD program and to further compare those results to an existing bulk flow computer program currently used by major US machinery manufacturers. The labyrinth seals of a steam turbine and a compressor eye seal are taken as objects of analysis. For each case, a 3D model with eccentric rotor was solved to obtain the rotordynamic force components. The leakage flow and rotor dynamics force predicted by CFX TASCFlow are compared with the results of the existing bulk flow analysis program DYNLAB. The results show that the bulk flow program gives a pessimistic prediction of the destabilizing forces for the conditions under investigation. Further research work will be required to fully understand the complex leakage flows in turbo machinery. [DOI: 10.1115/1.1808426]

The aggregation of high affinity IgE receptors (Fc[epsilon] receptor I [Fc[epsilon]RI]) on mast cells is potent stimulus for the release of inflammatory and allergic mediators from cytoplasmic granules. However, the molecular mechanism of degranulation has not yet been established. It is still unclear how Fc[epsilon]RI-mediated signal transduction ultimately regulates the reorganization of the cytoskeleton and how these events lead to degranulation. Here, we show that Fc[epsilon]RI stimulation triggers the formation of microtubules in a manner independent of calcium. Drugs affecting microtubule dynamics effectively suppressed the Fc[epsilon]RI-mediated translocation of granules to the plasma membrane and degranulation. Furthermore, the translocation of granules to the plasma membrane occurred in a calcium-independent manner, but the release of mediators and granule-plasma membrane fusion were completely dependent on calcium. Thus, the degranulation process can be dissected into two events: the calcium-independent microtubule-dependent translocation of granules to the plasma membrane and calcium-dependent membrane fusion and exocytosis. Finally, we show that the Fyn/ Gab2/RhoA (but not Lyn/SLP-76) signaling pathway plays a critical role in the calcium-independent microtubule-dependent pathway.

The traditional method for bearing and damper analysis usually involves a development of rather complicated numerical calculation programs that may just focus on a simplified and specific physical model. The application of the general CFD codes may make this analysis available and effective where complex flow geometries are involved or when more detailed solutions are needed. In this study, CFX-TASC flow is employed to simulate various fixed geometry fluid-film bearing and damper designs. Some of the capabilities in CFX-TASCflow are applied to simulate the pressure field and calculate the static and dynamic characteristics of hydrodynamic, hydrostatic, and hybrid bearings as well as squeeze film dampers. The comparison between the CFD analysis and current computer programs used in industry has been made. The results show reasonable agreement in general. Some of the possible reasons for the differences are discussed. It leaves room for further investigation and improvement on the methods of computation. [DOI: 10.1115/1.1807415]

Zebrafish signal transducer and activator of transcription 3 (STAT3) controls the cell movements during gastrulation. Here, we show that noncell-autonomous activity of STAT3 signaling in gastrula organizer cells controls the polarity of neighboring cells through Dishevelled-RhoA signaling in the Wnt-planar cell polarity (Wnt-PCP) pathway. In STAT3-depleted embryos, although all the known molecules in the Wnt-PCP pathway were expressed normally, the RhoA activity in lateral mesendodermal cells was down-regulated, resulting in severe cell polarization defects in convergence and extension movements identical to Strabismus-depleted embryos. Cell-autonomous activation of Wnt-PCP signaling by AN-dishevelled rescued the defect in cell elongation, but not the orientation of lateral mesendodermal cells in STAT3-depleted embryos. The defect in the orientation could be rescued by transplantation of shield cells having noncell-autonomous activity of STAT3 signaling. These results suggest that the cells undergoing convergence and extension movement may sense the gradient of signaling molecules, which are expressed in gastrula organizer by STAT3 and noncell-autonomously activate PCP signaling in neighboring cells during zebrafish gastrulation.

Author(s): Susumu Yamashita [1, 2, 4]; Chiemi Miyagi [2, 4]; Toshiyuki Fukada [2, 3]; Naofumi Kagara [2]; Yong-Suk Che [1]; Toshio Hirano (corresponding author) [1, 2, 3] Vertebrate gastrulation is [...]

In epidermis, Ras can influence proliferation and differentiation; however, regulators of epidermal Ras function are not fully characterized, and Ras effects on growth and differentiation are controversial. EGF induced Ras activation in epidermal cells along with phosphorylation of the multisubstrate docking protein Gab1 and its binding to SHP-2. Expression of mutant [Gab1.sup.Y627F] deficient in SHP-2 binding or dominant-negative [SHP-2.sup.C459S] reduced basal levels of active Ras and downstream MAPK proteins and initiated differentiation. Differentiation triggered by both [Gab1.sup.Y627F] and [SHP-2.sup.C459S] could be blocked by coexpression of active Ras, consistent with Gab1 and SHP-2 action upstream of Ras in this process. To study the role of Gab1 and SHP-2 in tissue, we generated human epidermis overexpressing active Gab1 and SHP-2. Both proteins stimulated proliferation. In contrast, [Gab1.sup.Y627F] and [SHP-2.sup.C459S] inhibited epidermal proliferation and enhanced differentiation. Consistent with a role for Gab1 and SHP-2 in sustaining epidermal Ras/MAPK activity, [Gab1.sup.-/-] murine epidermis displayed lower levels of active Ras and MAPK with postnatal [Gab1.sup.-/-] epidermis, demonstrating the hypoplasia and enhanced differentiation seen previously with transgenic epidermal Ras blockade. These data provide support for a Ras role in promoting epidermal proliferation and opposing differentiation and indicate that Gab1 and SHP-2 promote the undifferentiated epidermal cell state by facilitating Ras/MAPK signaling.

We identified a zebrafish homologue of Dickkopf-1 (Dkk1), which was previously identified in Xenopus as a Wnt inhibitor with potent head-inducing activity. Zebrafish dkk1 is expressed in the dorsal marginal blastoderm and also in the dorsal yolk syncytial layer after mid-blastula transition. At later blastula stages, the expression expands to the entire blastoderm margin. During gastrulation, dkk1-expressing cells are confined to the embryonic shield and later to the anterior axial mesendoderm, prospective prechordal plate. Embryos, in which dkk1 was ectopically expressed, exhibited enlarged forebrain, eyes, and axial rnesendoderm such as prechordal plate and notochord, dkk1 expression in the dorso.anterior mesendoderm during gastrulation was prominently reduced in zebrafish mutants bozozok (boz), squint (sqt), and one-eyed pinhead (oep), which all display abnormalities in the formation and function of the Spemann organizer and axial mesendoderm, dkk1 expression was normal in these embryos during the blastula period, indicating that zygotic functions of these genes are required for maintenance but not establishment of dkk1 expression. Overexpression of dkk1 suppressed defects in the development of forebrain, eyes, and notochord in boz mutants. Overexpression of dkk1 promoted anterior neuroectoderm development in the embryos injected with antivin RNA, which lack most of the mesoderm and endoderm, suggesting that Dkk1 can affect regionalization of neuroectoderm independently of dorso-anterior mesendoderm. These data indicate that Dkk1, expressed in dorsal mesendoderm, functions in the formation of both the anterior nervous system and the axial mesendoderm in zebrafish.

Formation of Spemann organizer is a very significant stage in dorsoventral axis determination of vertebrate development. A novel zebrafish homeobox gene, dharma, has been isolated. It can induce the organizer ectopically. For the first time a zygotic gene implicated in formation of an organizer-inducing center has been identified.

Cell lineages during ascidian embryogenesis are invariant. In a previous study, the developmental fate of each blastomere during embryogenesis of the ascidian Halocynthia roretzi was analyzed in detail by intracellular injection of a tracer molecule, horseradish peroxidase (Nishida, H., Dev. Biol. 121, 526-541, 1987). In the present study, the developmental fates of various larval mesodermal tissues after metamorphosis in H. roretzi were traced by labeling each precursor blastomere of larval tissues. Mesenchyme cells of larvae gave rise to tunic cells of juveniles. Trunk ventral cells gave rise to body-wall (atrial siphon and latitudinal mantle) muscle, heart, and pericardium of juvenile. Trunk lateral cells gave rise to blood (coelomic) cells as well as body-wall (oral siphon and longitudinal mantle) muscle. Larval muscle and notochord cells did not contribute to juvenile tissues. It was revealed that it is predictable to which juvenile tissue a blastomere of the 110-cell embryo will give rise. Therefore, in ascidian development, developmental fates after metamorphosis were almost invariant with regard to cell type of descendants. Key Words: cell lineages; ascidian development; metamorphosis; HRP injection; mesoderm differentiation.

Molecular cloning of a stromal cell line-derived glycosyl phosphatidylinositol-attacked molecule BST-1, that helps in Pre-B-cell growth, explains stromal cell modulation of B lymphopoiesis. BST-1 shows improved expression in bone marrow stromal cell lines obtained from rheumatoid arthritis patients. BST-1 indicates an improved ability to help the growth of a pre-B-cell line.

Involvement of interleukin-6 (IL-6) in generation of plasmacytomas in IL-6transgenic mice was investigated. Introduction of human IL-6 cDNA into IL-6 transgenic mice of C57BL/6 origin induced major plasmacytosis without trace of plasmacytomas. Production of monoclonal transplantable plasmacytomas with the chromosomal translocation t(12;15) was observed in IL-6 transgenic mice with a BALB/c genetic background. Overexpression of IL-6 was noted to be sufficient to induce polyclonal plasmacytosis in the subject mice of B6 origin and indicated IL-6 involvement in plasmacytomagenesis.

The zebrafish homeobox gene dharma/bozozok (boz) is required for the formation and/or function of the Nieuwkoop center and the subsequent induction of the Spemann organizer, dharma is expressed soon after the midblastula transition in the dorsal blastomeres and the dorsal yolk syncytial layer (YSL). We found that the expression of dharma was upregulated or ectopically induced by misexpression of a Wnt protein and cytoplasmic components of the Wnt signaling pathway and downregulated by the expression of dominant-negative Tcf3. A 1.4-kbp fragment of the dharma promoter region contains consensus sequences for Tcf/Lef binding sites. This promoter region recapitulated the Wnt-dependent and dorsal dharma expression pattern when it was fused to luciferase or GFP. Deletion and point mutant analyses revealed that the Tcf/Lef binding sites were required to drive this expression pattern. These data established that dharma/boz functions between the dorsal determinants-mediated Wnt signals and the formation of the Nieuwkoop center. [C] 2001 Academic Press Key Words: dharma; bozozok; Wnt signal; Nieuwkoop center; [Beta]-catenin; Tcf; Lef.

Kheper is a novel member of the ZFH (zinc-finger and homeodomain protein)/[Delta]EF1 family in zebrafish. kheper transcripts are first detected in the epiblast of the dorsal blastoderm margin at the early gastrula stage and kheper is expressed in nearly all the neuroectoderm at later stages, kheper expression was expanded in noggin RNA-injected embryos and also in swirl mutant embryos and was reduced in bmp4 RNA-injected embryos and chordino mutant embryos, suggesting that kheper acts downstream of the neural inducers Noggin and Chordino. Overexpression of Kheper elicited ectopic expansion of the neuroectoderm-specific genes fkd3, hoxa-1, and eng3, and the ectopic expression of hoxa-1 was not inhibited by BMP4 overexpression. Kheper interacted with the transcriptional corepressors CtBP1 and CtBP2. Overexpression of a Kheper mutant lacking the homeodomain or of a VP16-Kheper fusion protein disturbed the development of the neuroectoderm and head structures. These data underscore the role of Kheper in the development of the neuroectoderm and indicate that Kheper acts as a transcriptional repressor. [C] 2000 Academic Press Key Words: zebrafish; ZFH; [Delta]EF1; zinc-finger; homeodomain; transcription factor; ectoderm; mesoderm; CtBP; repressor.

HuC encodes an RNA binding protein homologous to Drosophila elav that serves as an excellent early marker for differentiating neurons. We have characterized the promoter of the zebrafish HuC gene by examining the ability of 5'-upstream fragments to drive expression of green fluorescent protein (GFP) in live embryos. We determined that 9.8 kb of the 5'-flanking sequence is sufficient to restrict GFP gene expression to neurons. The core promoter spans 251 base pairs and contains a CCAAT box and one SP1 sequence but no TATA box is present near the transcription start site. A putative MyT1 binding site and at least 17 E-box sequences are necessary to maintain the neuronal specificity of HuC expression. Interestingly, sequential removal of the putative MyT1 binding site and 14 distal E boxes does not appear to abolish neuronal expression; rather, it leads to a progressive expansion of GFP expression into muscle cells. Further removal of the three proximal E boxes eliminates neuronal and muscle specificity of GFP expression and leads to ubiquitous expression of GFP in the whole body. Identification of key components of the HuC promoter has led to the establishment of a stable zebrafish transgenic line (HuC-GFP) in which GFP is expressed specifically in neurons. We crossed mind bomb (mib) fish with this line to visualize their neurogenic phenotype in live [mib.sup.-/-] mutant embryos. This cross illustrates how HuC-GFP fish could be used in the future to identify and analyze zebrafish mutants with an aberrant pattern of early neurons. [C] 2000 Academic Press Key Words: HuC; elav; zebrafish; neuron; promoter; Myt1; E box; transgenic; mind bomb.

Cleavage is one of the initial steps of embryogenesis, and is characterized by a series of symmetric and synchronous cell divisions. We showed that p38 MAP kinase (p38) is asymmetrically activated on one side of the blastodisc during the early cleavage period in zebrafish (Danio rerio) embryos. When a dominant negative (DN) form of p38 was uniformly expressed, blastomere cleavage was impaired on one side of the blastodisc, resulting in the formation of blastomeres with a large mass of cytoplasm and an enlarged nucleus on the affected side. The area affected by the DN-p38 expression did not correlate with the initial cleavage plane, but coincided with the side where dharma/bozozok, a dorsal-specific zygotic gene, was expressed (Yamanaka et al., 1998). Furthermore, UV irradiation and removal of the vegetal yolk mass before the first cleavage, both of which inhibit the initiation of the dorsalizing signals, abolished the asymmetric p38 activation. Our findings suggest that asymmetric p38 activation is required for symmetric and synchronous cleavage, and may be regulated by the same machinery that controls the initiation of dorsalizing signals. Key words: zebrafish * p38 * asymmetry * cleavage * microtubules

Cloning and Expression of the Human Interleukin-6 (BSF-2/IFNβ 2) Receptor B CELL STIMULATORY FACTOR-2 (BSF-2) was originally identified as a T cell-derived factor that causes the terminal maturation of activated [...]