Showing papers on "TEC published in 1998"
TL;DR: In this paper, a technique for retrieving the global distribution of vertical total electron content (TEC) from GPS-based measurements is described, based on interpolating TEC within triangular tiles that tessellate the ionosphere modeled as a thin spherical shell.
Abstract: A worldwide network of receivers tracking the transmissions of Global Positioning System (GPS) satellites represents a new source of ionospheric data that is globally distributed and continuously available. We describe a technique for retrieving the global distribution of vertical total electron content (TEC) from GPS-based measurements. The approach is based on interpolating TEC within triangular tiles that tessellate the ionosphere modeled as a thin spherical shell. The high spatial resolution of pixel-based methods, where widely separated regions can be retrieved independently of each other, is combined with the efficient retrieval of gradients characteristic of polynomial fitting. TEC predictions from climatological models are incorporated as simulated data to bridge significant gaps between measurements. Time sequences of global TEC maps are formed by incrementally updating the most recent retrieval with the newest data as it becomes available. This Kalman filtering approach smooths the maps in time, and provides time-resolved covariance information, useful for mapping the formal error of each global TEC retrieval. Preliminary comparisons with independent vertical TEC data, available from the TOPEX dual-frequency altimeter, suggest that the maps can accurately reproduce spatial and temporal ionospheric variations over latitudes ranging from equatorial to about ±65°.
1,148 citations
TL;DR: It is demonstrated that phosphatidylinositol‐3,4,5‐trisphosphate interacting with the PH domain acts as an upstream activation signal for Tec kinases, resulting in Tec kinase‐dependent phospholipase Cγ tyrosine phosphorylation and inositol trisph phosphate production.
Abstract: Tec family non-receptor tyrosine kinases have been implicated in signal transduction events initiated by cell surface receptors from a broad range of cell types, including an essential role in B-cell development. A unique feature of several Tec members among known tyrosine kinases is the presence of an N-terminal pleckstrin homology (PH) domain. We directly demonstrate that phosphatidylinositol-3,4,5-trisphosphate (PtdIns-3,4,5-P3) interacting with the PH domain acts as an upstream activation signal for Tec kinases, resulting in Tec kinase-dependent phospholipase Cgamma (PLCgamma) tyrosine phosphorylation and inositol trisphosphate production. In addition, we show that this pathway is blocked when an SH2-containing inositol phosphatase (SHIP)-dependent inhibitory receptor is engaged. Together, our results suggest a general mechanism whereby PtdIns-3,4,5-P3 regulates receptor-dependent calcium signals through the function of Tec kinases.
441 citations
TL;DR: The data suggest that cortical TEC development proceeds from a K8(+)K5(+) precursor subset to a K4(-)CD8(-)K5 (+) stage in a differentiation process concomitant with T-cell lineage commitment.
Abstract: Thymocyte and thymic epithelial cell (TEC) development are interdependent processes. Although lineage relationships among progressively maturing thymocyte subsets have been characterized, the developmental relationships among TEC subsets are obscure. Because epithelial cells express distinct keratin (K) species as a function of differentiation stage and proliferative status, we used K expression patterns to identify mouse TEC subsets and determine their lineage relationships. As expected, cortical and medullary TEC subsets express distinct K expression patterns in the normal thymus. However, we detected two distinct cortical TEC subsets, a major K8+K5− subset and a minor K8+K5+ subset, which is highly represented at the cortico-medullary junction. Both cortical TEC subsets are also present in recombination activating gene 1 (RAG-1−/−) and TCRβxδ−/− thymi in which T-cell development is blocked at the CD4−CD8−CD25+CD44− pre-T cell stage. In contrast, K8+K5+ TECs predominate in the thymi of human CD3ɛ transgenic mice in which thymocyte development is blocked at an earlier CD4−CD8−CD25−CD44+ stage. Transplantation of newborn human CD3ɛ transgenic thymi under the kidney capsule of RAG-1−/− mice results in the emergence of K8+K5− TECs concomitant with the appearance of CD25+ thymocytes. Together, the data suggest that cortical TEC development proceeds from a K8+K5+ precursor subset to a K8+K5− stage in a differentiation process concomitant with T-cell lineage commitment.
304 citations
TL;DR: Two-dimensional total electron content (TEC) perturbations over Japan are mapped with the Geographical Survey Institute (GSI) GPS network, GEONET (GPS Earth Observation Network) as mentioned in this paper.
Abstract: Two-dimensional total electron content (TEC) perturbations over Japan are mapped with the Geographical Survey Institute (GSI) GPS network, GEONET (GPS Earth Observation Network). Its spatial resolution is 0.15° latitude × 0.15° longitude and temporal resolution is 30 seconds. Two-dimensional TEC observations with these high resolutions revealed spatial structures and temporal evolutions of traveling ionospheric disturbances (TIDs) in the nighttime mid-latitude ionosphere on July 03, 1997. A preliminary result of the TEC perturbation mapping indicates that it would be a strong tool to investigate the ionospheric structures in detail. Coordinated observations with other ionospheric observation techniques, such as incoherent scatter (IS) radars, airglow imagers, and ionosondes, are needed to clarify the vertical structure of the ionosphere.
289 citations
TL;DR: The evidence indicates that Tec kinases are involved in Gα12/13‐induced, Rho‐mediated activation of SRF, which is sensitive to C3, suggesting the involvement of Rho.
Abstract: A transient transfection system was used to identify regulators and effectors for Tec and Bmx, members of the Tec non-receptor tyrosine kinase family. We found that Tec and Bmx activate serum response factor (SRF), in synergy with constitutively active alpha subunits of the G12 family of GTP-binding proteins, in transiently transfected NIH 3T3 cells. The SRF activation is sensitive to C3, suggesting the involvement of Rho. The kinase and Tec homology (TH) domains of the kinases are required for SRF activation. In addition, kinase-deficient mutants of Bmx are able to inhibit Galpha13- and Galpha12-induced SRF activation, and to suppress thrombin-induced SRF activation in cells lacking Galphaq/11, where thrombin's effect is mediated by G12/13 proteins. Moreover, expression of Galpha12 and Galpha13 stimulates autophosphorylation and transphosphorylation activities of Tec. Thus, the evidence indicates that Tec kinases are involved in Galpha12/13-induced, Rho-mediated activation of SRF. Furthermore, Src, which was previously shown to activate kinase activities of Tec kinases, activates SRF predominantly in Rho-independent pathways in 3T3 cells, as shown by the fact that C3 did not block Src-mediated SRF activation. However, the Rho-dependent pathway becomes significant when Tec is overexpressed.
101 citations
TL;DR: The global evolution of two major ionospheric storms, occurring on November 4, 1993 and November 26, 1994, respectively, were studied using measurements of total electron content (TEC) obtained from a worldwide network of ground-based GPS receivers as mentioned in this paper.
Abstract: The global evolution of two major ionospheric storms, occurring on November 4, 1993, and November 26, 1994, respectively, is studied using measurements of total electron content (TEC) obtained from a worldwide network of ground-based GPS receivers. The time-dependent features of ionospheric storms are identified using TEC difference maps based on the percent change of TEC during storm time relative to quiet time. The onset of each ionospheric storm is indicated by the appearance of auroral/subauroral TEC enhancements which occur within 1 hour of the beginning of the geomagnetic storm main phase. Significant TEC enhancements (> 100%) are observed in the winter northern hemisphere. The rate at which TEC enhancements appear is found to correlate with gradients in the Dst index. The large scale ionospheric structures identified during the storms are (1) nightside auroral/subauroral enhancements which surround the auroral oval, (2) dayside (around noon) high-latitude and middle-latitude enhancements associated with traveling ionospheric disturbances, and (3) conjugate latitudinal enhancements. For the November 1993 storm, a short positive phase (about 15 hours) is followed by a long negative phase (∼60 hours). In the November 1994 storm, we have identified the clear signature of a traveling ionospheric disturbance (TID) which propagated at a speed of ∼460 m/s from ∼60° N to ∼40° N. The motion of this disturbance appears to conserve angular momentum.
85 citations
TL;DR: The results provide a molecular basis for an autocrine/paracrine mode of action of GH in the human thymus and show that GH receptors are predominantly expressed by immature thymocytes.
Abstract: GH has been shown to modulate various functions of the thymus. We now demonstrate the production of human GH (hGH) by human thymic cells, and the expression of GH receptors in thymic epithelial cells (TEC) and in thymocytes at different stages of differentiation. The presence of hGH messenger RNA was shown by RT-PCR in both human thymocytes and in primary cultures of TEC. Moreover, immunoreactive hGH material was detected in culture media of thymocytes and TEC with the use of a sensitive immunoradiometric assay. GH receptor gene expression was shown in TEC in primary cultures and in fetal and postnatal TEC lines as well as in thymocytes. By immunocytochemistry, the presence of GH receptors in the various TEC preparations was confirmed. In cytofluorometric studies with the use of a biotinylated anti-GH receptor monoclonal antibody, we could show that GH receptors are predominantly expressed by immature thymocytes: over 90% of CD3− CD4− CD8− CD19− CD34+ CD2+ cells (a phenotype characterizing the most immatu...
82 citations
TL;DR: In this article, the authors presented data from first measurements of total electron content (TEC) and its gradient during the solar eclipse of March 9, 1997, obtained with the GPS-radio interferometer at Irkutsk.
Abstract: This paper presents data from first measurements of total electron content (TEC) and its gradient during the solar eclipse of March 9, 1997, obtained with the GPS-radio interferometer at Irkutsk. The interferometer consists of three receivers (one Turbo-Rogue SNR-8000, and two Ashtech Z-12) located at the vertices of a triangle and spaced by about 3–5 km. The measured TEC variations are indicative of profound changes in the ion production process in the ionosphere attendant on the solar eclipse, simultaneously in a large volume of space with a radius of at height 300 km at 300 km altitude. The delay of a minimum value of TEC with respect to the maximum phase of eclipse at 300 km altitude was about 10 min, and the depression depth of TEC growth varies from l÷3×1016m−2. By analyzing the data on TEC gradient variations, one is led to conclude that the depression of TEC growth during the eclipse is essentially independent of the longitude and of the latitude (within the observation ranges 52±6° N and 104±11° E).
82 citations
TL;DR: It is concluded that Tec is expressed and can be stimulated throughout human B-cell differentiation, implying that this tyrosine kinase plays a role in B- cell development and activation.
76 citations
TL;DR: In this paper, an artificial neural network method is applied to the development of an ionospheric forecasting technique for one hour ahead, and the results show that the proposed technique is suitable for the prediction of the critical frequency of the F2 layer, foF2, and total electron content (TEC).
Abstract: An artificial neural network method is applied to the development of an ionospheric forecasting technique for one hour ahead. Comparisons between the observed and predicted values of the critical frequency of the F2 layer, foF2, and the total electron content (TEC) are presented to show the appropriateness of the proposed technique.
68 citations
TL;DR: In this paper, the authors used a modified version of the International Reference Ionosphere 1995 (IRI-95) model and augmented with a plasmaspheric electron content model to produce hourly global total electron content (TEC) maps from Global Positioning System (GPS) data.
TL;DR: In this article, the ionospheric response to the major geomagnetic storm of October 18-19, 1995, using the NCAR TIE-GCM simulations and the global ionosphere maps (GIM) of total electron content (TEC) observations from the worldwide network of Global Positioning System (GPS) receivers, was studied.
Abstract: This paper studies the ionospheric response to the major geomagnetic storm of October 18–19, 1995, using the NCAR TIE-GCM simulations and the global ionospheric maps (GIM) of total electron content (TEC) observations from the worldwide network of Global Positioning System (GPS) receivers. The TIE-GCM results show a good agreement with the GPS-GIM in terms of simulating storm-time TEC disturbances over the polar regions. The model indicates that the increase of electron density in the high-latitude E and lower F regions below 200 km is directly related to the magnetospheric energy input through auroral precipitation to the ionosphere, while the decrease of TEC is mainly due to the increase in O2 and N2 densities in the upper F region above 200 km. During the recovery phase, both the TIE-GCM and GPS-GIM reveal a distinct hemispheric asymmetry in the TEC integrated above |50°| magnetic latitude, with a 20% decrease in the southern (summer-like) hemisphere and a 30% increase in the northern (winter-like) hemisphere.
TL;DR: In this paper, the authors present an experimental investigation of the electron density variations before earthquakes when the low-altitude satellite TOPEX-POSEIDON is above active seismic regions, and the corresponding number of TEC perturbations correlated in space and in time (up to 48 h before these earthquakes) is 238, i.e., 34% of the cases.
TL;DR: It is presented here that Tec PTK is tyrosine-phosphorylated and activated by granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulation in a human GM- CSF–dependent cell line and that Tec and Jak2 can “cross-talk” in a complexed way to mediate cytokine-driven c- fos activation.
TL;DR: The first significant response of the inonospheric TEC to the geomagnetic storm was at 0300 UT as an auroral/subauroral enhancement around the Alaskan evening sector.
Abstract: The ionospheric storm evolution process was monitored during the January 10, 1997 magnetic cloud event, through measurements of the inonospheric total electron content (TEC) from 150 GPS stations. The first significant response of the inonospheric TEC to the geomagnetic storm was at 0300 UT as an auroral/subauroral enhancement around the Alaskan evening sector.
TL;DR: GPS-derived TEC data are compared with IRI95 and the European TEC model NTCM2 as discussed by the authors, and the results show that the latter does not include the plasmaspheric content.
TL;DR: In this article, the authors reported initial measurements of ionospheric propagation parameters, particularly the total electron content (TEC), using the recently launched FORTE satellite, which contains a set of wideband radio receivers whose output is digitally recorded.
Abstract: We report initial measurements of ionospheric propagation parameters, particularly the total electron content (TEC), using the recently launched FORTE satellite. FORTE, which orbits the Earth at an altitude of 800 km and an inclination of 70{degree}, contains a set of wideband radio receivers whose output is digitally recorded. A specialized triggering circuit identifies transient, broadband radio events, which include radiation from lightning, transionospheric pulse pairs, and man-made sources. Event data are transmitted to the ground station for analysis. In this paper we examine signals transmitted from an electromagnetic pulse generator operated at Los Alamos. The transmitter produces nearly impulsive signals in the VHF range. The received signal is dispersed by the ionosphere, and the received signal can be analyzed to deduce the total electron content along the path. By comparing the slant TEC thus measured with results from a ray-tracing code, we can deduce the vertical TEC to 800 km. Data from eight passes are presented. These types of data (in larger quantities) are of interest to operators of radar altimeters, who need data to corroborate their corrections for the ionospheric TEC. The combination of FORTE TEC data to 800 km and TEC measurements to 20,000 km (the Global Positioningmore » System orbital altitude) can provide useful information for assessing the validity of models of plasmaspheric electron density. Initial estimates of the plasmaspheric density, on two daytime passes, are about 6 TECU. The signal received by FORTE, which is linearly polarized at the transmitter, is split into two magnetoionic modes by the ionosphere. The receiving antenna is also linearly polarized and therefore receives both modes. By measuring the beat frequency between the two modes, we can deduce the product of the geomagnetic field and the cosine of the angle between the field and the propagation vector. The possibility of using the measured slant TEC and the beat frequency to geolocate impulsive signals is discussed. {copyright} 1998 American Geophysical Union« less
Patent•
14 Sep 1998TL;DR: In this article, a thermistor senses the temperature of the laser and through a first control loop causes current to be passed through the TEC so as to adjust the laser temperature.
Abstract: A thermoelectric cooler (TEC) is used to maintain an electronic component, for example, a laser diode, at a set temperature. A thermistor senses the temperature of the laser and through a first control loop causes current to be passed through the TEC so as to adjust the laser temperature. As the temperature of the hot side of the TEC increases above the temperature of the cold side of the TEC, the TEC's cooling efficiency gradually decreases. This is compensated for by adding a second control loop which senses the TEC current and provides an additional gain proportional to the TEC current in the cooling sense. This additional gain is added to the gain provided by the first control loop. The result is a stable, highly responsive temperature controller at all points of the TEC operating range.
TL;DR: In this paper, the authors used faraday electron content measurements obtained during a high solar activity year at Tucuman station in Argentina, located near the southern peak of the equatorial anomaly in the American sector, to check the validity of IRI-95 in predicting the total electron content (TEC) at this region.
TL;DR: In this paper, different artificial neural networks have been used to model and predict the temporal and spatial variations of ionospheric critical frequency, f0F2 and total electron content (TEC).
Abstract: The ionosphere of Earth exhibits considerable spatial changes and has large temporal variability of various timescales related to the mechanisms of creation, decay and transport of space ionospheric plasma. Many techniques for modelling electron density profiles through entire ionosphere have been developed in order to solve the "age-old problem" of ionospheric physics which has not yet been fully solved. A new way to address this problem is by applying artificial intelligence methodologies to current large amounts of solar-terrestrial and ionospheric data. It is the aim of this paper to show by the most recent examples that modern development of numerical models for ionospheric monthly median long-term prediction and daily hourly short-term forecasting may proceed successfully applying the artificial neural networks. The performance of these techniques is illustrated with different artificial neural networks developed to model and predict the temporal and spatial variations of ionospheric critical frequency, f0F2 and Total Electron Content (TEC). Comparisons between results obtained by the proposed approaches and measured f0F2 and TEC data provide prospects for future applications of the artificial neural networks in ionospheric studies.
TL;DR: It is proposed that integrin clustering occurring during TEC-thymocyte contacts modulates in TEC the gene expression of a cytokine involved in thymocyte growth and functional differentiation.
TL;DR: In this article, the authors proposed a method to correct the ionospheric range delay by measuring the difference in this dispersive effect on both frequencies of a single-and dual-frequency GPS receiver.
Abstract: he next maximum in the approximate 11-year cycle of solar ultraviolet (UV) activity is expected to occur near 2000. Two major ionospheric effects on GPS signals are closely related to long-term solar UV activity, and also will maximize at that time. These are ionospheric range delays and amplitude fading and phase scintillation effects. Dual-frequency GPS receivers automatically correct for the ionospheric range delay by measuring the difference in this dispersive effect on both frequencies. Civilian users of singlefrequency LI GPS receivers must either rely on the ionospheric correction algorithm sent as part of the user message, designed to correct for only 50% rms of the range delay, or they must use a nearby, in time and space, actual measurement of the ionospheric range delay to provide a correction for the ionospheric range error. Ionospheric range delays are directly proportional to the total electron content (TEC), encountered along the path from each GPS satellite to the user. The TEC increases with increasing solar cycle activity. As the absolute values of range delay increase with the solar cycle, the need for improved corrections also will increase. Irregularities in the ionosphere that produce amplitude fading and phase scintillation effects on GPS frequencies can become significant as the solar cycle
TL;DR: In this paper, the authors used the CORS network of GPS receivers to record ionospheric TEC changes in the continental United States caused by the well observed geomagnetic disturbance of January 10, 1997.
Abstract: We have used the CORS network of GPS receivers to record ionospheric TEC changes in the continental United States caused by the well observed geomagnetic disturbance of January 10, 1997. This event produced numerous worldwide consequences. Although the initial arrival of this disturbance was before sunrise in the U.S. the TEC levels were most significantly altered later during the daylight hours. We display temporal and spatial changes through time series at selected sites and maps of the entire network. The usual sequence of diurnal changes was not greatly altered, but most of the TEC values were increased by about a factor of one and a half to two. Stations in the northeast and upper north central were exceptions and showed a small decrease in TEC. We interpret the TEC changes as consequences of changes in neutral chemical composition resulting from storm heating.
TL;DR: In this article, a 1-day fit of 20-second-averaged NRA ionospheric correction data versus GPS tomographic TEC data has a bias of 3.4 TECU.
Abstract: We compare TEC measurements from the NASA Radar Altimeter and DORIS instrument on board TOPEX/POSEIDON with GPS TEC estimates, and evaluate different GPS data analysis strategies. We verify that global tomographic GPS analysis using a voxel grid is well suited for ionospheric calibration of altimeters. We show that a 1-day fit of 20-second-averaged NRA ionospheric correction data versus GPS tomographic TEC data has a bias of 3.4 TECU and a root mean square deviation of 3.2 TECU. Tomographic inversion using simulated data from the Parametrized Ionospheric Model highlights the strong correlation between GPS bias constants, electronic densities at the highest layer, and unmodeled protonospheric TEC. This suggests that GPS TEC estimates at the TOPEX/POSEIDON altitude are more accurate if the bias constants are estimated and if a layer above TOPEX/POSEIDON is added to the grid.
01 Jan 1998
TL;DR: Based on the analysis of GPS-derived TEC maps computed at DLR/DFD Neustrelitz for the European area on a routine base with a time resolution of 10 min, the authors demonstrates the power of this new tool to detect and to study the dynamics of large scale horizontal structures in the perturbed ionosphere.
Abstract: The world-wide use of GPS satellites for navigation and positioning offers the unique chance for permanent monitoring the total electron content (TEC) of the ionosphere on global scale. Based on the analysis of GPS-derived TEC maps computed at DLR/DFD Neustrelitz for the European area on a routine base with a time resolution of 10 min the paper demonstrates the power of this new tool to detect and to study the dynamics of large scale horizontal structures in the perturbed ionosphere. Ionospheric storm phenomena are shown to be closely related with Space Weather characterising parameters such as solar radio flux index, solar wind speed and geomagnetic activity indices. Mid-term variations of solar wind speed and related geomagnetic parameters are anticorrelated with GPS-derived TEC data obtained in the first half of 1996, thus showing the potential of TEC maps for studying of upper atmosphere dynamics. It is expected that GPS radio occultation measurements onboard future satellite missions such as SAC-C, CHAMP and METOP will essentially contribute to monitor the global electron density distribution in near real time.
TL;DR: In this article, the seasonal, diurnal, and latitudinal variations of total electron content (TEC) were determined using Global Positioning System (GPS) satellite signals over approximately 5 days per month during almost half a sunspot cycle (July 1991 to June 1995) at Salisbury (latitude 34.77°S, longitude 138.63°E), South Australia.
Abstract: The seasonal, diurnal, and latitudinal variations of total electron content (TEC) were determined using Global Positioning System (GPS) satellite signals over approximately 5 days per month during almost half a sunspot cycle (July 1991 to June 1995) at Salisbury (latitude 34.77°S, longitude 138.63°E), South Australia. These are the only such extensive southern hemisphere data till 1995 that have been recorded and analyzed. A selection of the data is presented, discussed, and compared with other workers' observations. Examples of Australian Surveying and Land Information Group (AUSLlG) data in the Australian region are presented. Some model predictions for northern hemisphere ionospheric TEC are compared with the GPS southern hemisphere observations of the combined TEC of the ionosphere and protonosphere. (The two models employed are the international reference ionosphere (IRI-90) and the paramaterized ionospheric model (PIM)(version 1.4, February 1996)). They are considered to be global models, even though the IRJ model is based primarily, but not exclusively, on northern hemisphere TEC data, and PIM is based on a theoretical model and is thus not directly based on TEC data.
TL;DR: Antibodies identifying stage‐specific antigens will provide useful markers to characterise early embryonic cells, monitor normal embryonic development in vitro, and identify cell surface structures having a function in cell‐cell interactions during embryogenesis and differentiation.
Abstract: The preimplantation developmental period is associated with constant changes within the embryo, and some of these changes are apparent on the embryo cell surface. For example, during transition from maternal to embryonic genome control and the compaction and differentiation of embryonic cells, the cell surface undergoes morphologic alterations that reflect changes in gene control. In order to gain insight into the events occurring during embryonic development and cellular differentiation, monoclonal antibodies specific for cell surface antigens (TEC antigens) of embryonic cells have been generated previously and shown to recognise either the carbohydrate moiety of embryoglycan or a developmentally regulated protein epitope. The TEC antigens have been identified on mouse preimplantation embryos, and their expression is specific to particular developmental stages. To determine whether these antigens are conserved in higher mammals, we examined the expression of four TEC antigens (TEC-1 to TEC-4) on in vitro-derived bovine and murine embryos during the preimplantation stage of development. It was found that bovine oocytes and embryos derived from in vitro maturation (IVM) and in vitro fertilisation (IVF) showed stage-specific expression of each of the TEC antigens investigated, with the pattern of expression overlapping but not identical to that seen in the mouse. Immunoprecipitation together with Western blot analysis showed that the TEC monoclonal antibodies recognised a single glycoprotein band with an apparent molecular weight of 70 kDa. Confocal microscopy of immunofluorescence staining of the bovine cells showed this protein to be located on the cell surface. The apparent negative expression of these TEC antigens by immunohistochemistry and immunoprecipitation at particular stages of development appears to be due to the epitopes being inaccessible to the TEC antibodies, since Western blotting revealed the TEC antigens to be present at all stages of development examined. Antibodies identifying stage-specific antigens will provide useful markers to characterise early embryonic cells, monitor normal embryonic development in vitro, and identify cell surface structures having a function in cell-cell interactions during embryogenesis and differentiation.
TL;DR: This report describes a new Tec-family non-receptor tyrosine kinase that has been isolated from a zebrafish kidney cDNA library andPrimers based on a kinase region exon of mammalian Tec- family kinases were used to amplify zebra fish genomic DNA.
Abstract: Tec-family tyrosine kinases comprise a family of cytoplasmic kinases that are related to, but are structurally distinct from the Src family of kinases. The Tec-family genes: Btk, Itk, Tec, Txk, and Bmx (Desiderio and Siliciano 1994; Rawlings and Witte 1995) are expressed primarily in hematopoietic lineages. Tec-family kinases contain a pleckstrin homology, a tec homology, SH3, SH2, and kinase domains; only Txk lacks the amino terminal pleckstrin homology domain (Haire et al. 1994). The genomic structures of several Tec-family kinases have been resolved (Ohta et al. 1994, 1996). Btk, the most extensively studied Tec-family kinase, is the affected gene in X-linked agammaglobulinemia in human and Xid in mouse. This report describes a new Tec-family non-receptor tyrosine kinase that has been isolated from a zebrafish kidney cDNA library. Primers based on a kinase region exon of mammalian Tec-family kinases, corresponding to exon 15 in Btk, were used to amplify zebrafish genomic DNA. The structures of the primers are: 59-TTCTGCAGGTGCA(GA)(TC)T(TG)TATGG-39 (Pst I-linkered) and 59-CCAAGCTTACCA(AG)(AG)TC(TC)C-39 (Hin dIII linkered). As predicted, the polymerase chain reaction generated a 210 base pair product that was used as a probe to screen a zebrafish kidney cDNA library cloned in ZAP Express (Stratagene, La Jolla, Calif.). Twenty-four hybridizing plaques were isolated and eight were sequenced on a LICOR 4000L