The Experts below are selected from a list of 28494 Experts worldwide ranked by ideXlab platform
Pascal Willis - One of the best experts on this subject based on the ideXlab platform.
-
the international DORIS service contribution to the 2014 realization of the international terrestrial reference frame
Advances in Space Research, 2016Co-Authors: G Moreaux, Pascal Willis, Michiel Otten, F G Lemoine, Hugues Capdeville, Sergey Kuzin, Petr Stěpanek, Pascale FerrageAbstract:Abstract In preparation of the 2014 realization of the International Terrestrial Reference Frame (ITRF2014), the International DORIS Service delivered to the International Earth Rotation and Reference Systems Service a set of 1140 weekly solution files including station coordinates and Earth orientation parameters, covering the time period from 1993.0 to 2015.0. The data come from eleven DORIS satellites: TOPEX/Poseidon, SPOT2, SPOT3, SPOT4, SPOT5, Envisat, Jason-1, Jason-2, Cryosat-2, Saral and HY-2A. In their processing, the six analysis centers which contributed to the DORIS combined solution used the latest time variable gravity models and estimated DORIS ground beacon frequency variations. Furthermore, all the analysis centers but one excepted included in their processing phase center variations for ground antennas. The main objective of this study is to present the combination process and to analyze the impact of the new modeling on the performance of the new combined solution. Comparisons with the IDS contribution to ITRF2008 show that (i) the application of the DORIS ground phase center variations in the data processing shifts the combined scale upward by nearly 7–11 mm and (ii) thanks to estimation of DORIS ground beacon frequency variations, the new combined solution no longer shows any scale discontinuity in early 2002 and does not present unexplained vertical discontinuities in any station position time series. However, analysis of the new series with respect to ITRF2008 exhibits a scale increase late 2011 which is not yet explained. A new DORIS Terrestrial Reference Frame was computed to evaluate the intrinsic quality of the new combined solution. That evaluation shows that the addition of data from the new missions equipped with the latest generation of DORIS receiver (Jason-2, Cryosat-2, HY-2A, Saral), results in an internal position consistency of 10 mm or better after mid-2008.
-
dpod2008 a DORIS oriented terrestrial reference frame for precise orbit determination
2015Co-Authors: Pascal Willis, Laurent Soudarin, John C Ries, Nikita P Zelensky, Luca Cerri, Guilhem Moreaux, Frank G Lemoine, Michiel Otten, Donald F Argus, Michael HeflinAbstract:While accuracy of tracking station coordinates is of key importance for Precise Orbit Determination (POD) for altimeter satellites, reliability and operationality are also of great concern. In particular, while recent ITRF realizations should be the most accurate at the time of their computation, they cannot be directly used by the POD groups for operational consideration for several reasons such as new stations appearing in the network or new discontinuities affecting station coordinates. For POD purposes, we computed a new DORIS terrestrial frame called DPOD2008 derived from ITRF2008 (as previously done by DPOD2005 with regards to ITRF2005). In a first step, we will present the method used to validate the past ITRF2008 using more recent DORIS data and to derive new station positions and velocities, when needed. In particular, discontinuities in DORIS station positions and/or velocities are discussed. To derive new DORIS station coordinates, we used recent DORIS weekly time series of coordinates, recent GPS relevant time series at co-located sites and also dedicated GPS campaigns performed by IGN when installing new DORIS beacons. DPOD2008 also contains additional metadata that are useful when processing DORIS data, for example, periods during which DORIS data should not be used or at least for which data should be downweighted. In several cases, a physical explanation can be found for such temporary antenna instability. We then demonstrate improvements seen when using different reference frames, such as the original ITRF2008 solution, for precise orbit determination of altimeter satellites TOPEX/Poseidon and Jason-2 over selected periods spanning 1993–2013.
-
improving DORIS geocenter time series using an empirical rescaling of solar radiation pressure models
Advances in Space Research, 2009Co-Authors: Pascal Willis, John C Ries, Marieline Gobinddass, O De Viron, A Sibthorpe, Nikita P Zelensky, Remi FerlandAbstract:Abstract Even if Satellite Laser Ranging (SLR) remains the fundamental technique for geocenter monitoring, DORIS can also determine this geophysical parameter. Gobinddass et al. (2009) found that part of the systematic errors at 118 days and 1 year can be significantly reduced by rescaling the current solar radiation pressure models using satellite-dependent empirical models. Here we extend this study to all DORIS satellites and propose a complete set of empirical solar radiation parameter coefficients. A specific problem related to SPOT-5 solar panel realignment is also detected and explained. New DORIS geocenter solutions now show a much better agreement in amplitude with independent SLR solutions and with recent geophysical models. Finally, the impact of this refined DORIS data strategy is discussed in terms of Z-geocenter monitoring as well as for other geodetic products (altitude of high latitude station such as Thule in Greenland) and Precise Orbit Determination. After reprocessing the full 1993.0-2008.0 DORIS data set, we confirm that the proposed strategy allows a significant reduction of systematic errors at periods of 118 days and 1 year (up to 20 mm), especially for the most recent data after 2002.5, when more DORIS satellites are available for geodetic purposes.
-
systematic biases in DORIS derived geocenter time series related to solar radiation pressure mis modeling
Journal of Geodesy, 2009Co-Authors: Marieline Gobinddass, Yoaz Barsever, Pascal Willis, John C Ries, O De Viron, A Sibthorpe, Nikita P Zelensky, Remi Ferland, M DiamentAbstract:As any satellite geodesy technique, DORIS can monitor geocenter variations associated to mass changes within the Earth–Atmosphere–Continental hydrosphere–Oceans system. However, especially for the Z-component, corresponding to a translation of the Earth along its rotation axis, the estimated geocenter is usually affected by large systematic errors of unknown cause. By reprocessing old DORIS data, and by analyzing single satellite solutions in the frequency domain, we show that some of these errors are satellite-dependent and related to the current DORIS orbit determination strategy. In particular, a better handling of solar pressure radiation effects on SPOT-2 and TOPEX satellites is proposed which removes a large part of such artifacts. By empirically multiplying the current solar pressure model with a single coefficient (1.03 for TOPEX/Poseidon after 1993.57, and 0.96 before; and 1.08 for SPOT-2) estimated over a long time period, we can improve the measurement noise of the Z-geocenter component from 47.5 to 30.4 mm for the RMS and from 35 to 6 mm for the amplitude of the annual signal. However, the estimated SRP coefficient for SPOT-2 presents greater temporal variability, indicating that a new, dedicated solar radiation pressure model is still needed for precise geodetic applications. In addition, for the TOPEX satellite, a clear discontinuity of unknown cause is also detected on July 27, 1993.
-
DORIS applications for solid earth and atmospheric sciences
Comptes Rendus Geoscience, 2007Co-Authors: Pascal Willis, Laurent Soudarin, Christian Jayles, Lucie RollandAbstract:DORIS is a French precise orbit determination system. However, in the past four years, through the creation of the International DORIS Service, a larger international cooperation was involved. Furthermore, the precision of its scientific applications (geodesy, geophysics) gradually improved and expanded to new fields (atmospheric sciences), leading, for example, to the publication of a special issue of the Journal of Geodesy. The goal of this manuscript is to present and explain these changes and to put them in perspective with current results obtained with other space geodetic techniques, such as GPS or Satellite Laser Ranging.
Dmitri Loukinov - One of the best experts on this subject based on the ideXlab platform.
-
the combined action of ctcf and its testis specific paralog boris is essential for spermatogenesis
Nature Communications, 2021Co-Authors: Samuel Riverohinojosa, Dmitri Loukinov, Elena M Pugacheva, Sungyun Kang, Claudia Fabiola Mendezcatala, Alexander L Kovalchuk, Alexander V Strunnikov, Jeannie T LeeAbstract:CTCF is a key organizer of the 3D genome. Its specialized paralog, BORIS, heterodimerizes with CTCF but is expressed only in male germ cells and in cancer states. Unexpectedly, BORIS-null mice have only minimal germ cell defects. To understand the CTCF-BORIS relationship, mouse models with varied CTCF and BORIS levels were generated. Whereas Ctcf+/+Boris+/+, Ctcf+/-Boris+/+, and Ctcf+/+Boris-/- males are fertile, Ctcf+/-Boris-/- (Compound Mutant; CM) males are sterile. Testes with combined depletion of both CTCF and BORIS show reduced size, defective meiotic recombination, increased apoptosis, and malformed spermatozoa. Although CM germ cells exhibit only 25% of CTCF WT expression, chromatin binding of CTCF is preferentially lost from CTCF-BORIS heterodimeric sites. Furthermore, CM testes lose the expression of a large number of spermatogenesis genes and gain the expression of developmentally inappropriate genes that are "toxic" to fertility. Thus, a combined action of CTCF and BORIS is required to both repress pre-meiotic genes and activate post-meiotic genes for a complete spermatogenesis program.
-
transcription factor boris brother of the regulator of imprinted sites directly induces expression of a cancer testis antigen tsp50 through regulated binding of boris to the promoter
Journal of Biological Chemistry, 2011Co-Authors: Natsuki Kosakasuzuki, Dmitri Loukinov, Elena M Pugacheva, Alexander A Vostrov, Herbert C Morse, Teruhiko Suzuki, Victor V LobanenkovAbstract:Cancer-testis antigens (CTAs) are normally expressed in testis but are aberrantly expressed in a variety of cancers with varying frequency. More than 100 proteins have been identified as CTA including testes-specific protease 50 (TSP50) and the testis-specific paralogue of CCCTC-binding factor, BORIS (brother of the regulator of imprinted sites). Because many CTAs are considered as excellent targets for tumor immunotherapy, understanding the regulatory mechanisms governing their expression is important. In this study we demonstrate that BORIS is directly responsible for the transcriptional activation of TSP50. We found two BORIS binding sites in the TSP50 promoter that are highly conserved between mouse and human. Mutations of the binding sites resulted in loss of BORIS binding and the ability of BORIS to activate the promoter. However, although expression of BORIS was essential, it was not sufficient for high expression of TSP50 in cancer cells. Further studies showed that binding of BORIS to the target sites was methylation-independent but was diminished by nucleosomal occupancy consistent with the findings that high expression of TSP50 was associated with increased DNase I sensitivity and high BORIS occupancy of the promoter. These findings indicate that BORIS-induced expression of TSP50 is governed by accessibility and binding of BORIS to the promoter. To our knowledge this is the first report of regulated expression of one CTA by another to be validated in a physiological context.
-
the structural complexity of the human boris gene in gametogenesis and cancer
PLOS ONE, 2010Co-Authors: Elena M Pugacheva, Svetlana Pack, Alexander A Vostrov, Herbert C Morse, Natsuki Kosakasuzuki, Teruhiko Suzuki, Alexander V Strunnikov, Jeongheon Yoon, Eugene V Barsov, Dmitri LoukinovAbstract:Background BORIS/CTCFL is a paralogue of CTCF, the major epigenetic regulator of vertebrate genomes. BORIS is normally expressed only in germ cells but is aberrantly activated in numerous cancers. While recent studies demonstrated that BORIS is a transcriptional activator of testis-specific genes, little is generally known about its biological and molecular functions. Methodology/Principal Findings Here we show that BORIS is expressed as 23 isoforms in germline and cancer cells. The isoforms are comprised of alternative N- and C-termini combined with varying numbers of zinc fingers (ZF) in the DNA binding domain. The patterns of BORIS isoform expression are distinct in germ and cancer cells. Isoform expression is activated by downregulation of CTCF, upregulated by reduction in CpG methylation caused by inactivation of DNMT1 or DNMT3b, and repressed by activation of p53. Studies of ectopically expressed isoforms showed that all are translated and localized to the nucleus. Using the testis-specific cerebroside sulfotransferase (CST) promoter and the IGF2/H19 imprinting control region (ICR), it was shown that binding of BORIS isoforms to DNA targets in vitro is methylation-sensitive and depends on the number and specific composition of ZF. The ability to bind target DNA and the presence of a specific long amino terminus (N258) in different isoforms are necessary and sufficient to activate CST transcription. Comparative sequence analyses revealed an evolutionary burst in mammals with strong conservation of BORIS isoproteins among primates. Conclusions The extensive repertoire of spliced BORIS variants in humans that confer distinct DNA binding and transcriptional activation properties, and their differential patterns of expression among germ cells and neoplastic cells suggest that the gene is involved in a range of functionally important aspects of both normal gametogenesis and cancer development. In addition, a burst in isoform diversification may be evolutionarily tied to unique aspects of primate speciation.
-
expression of the ctcf paralogous cancer testis gene brother of the regulator of imprinted sites boris is regulated by three alternative promoters modulated by cpg methylation and by ctcf and p53 transcription factors
Nucleic Acids Research, 2007Co-Authors: Stephanie Renaud, Dmitri Loukinov, Elena M Pugacheva, Ziedulla Abdullaev, Dolores M Delgado, Richard Braunschweig, Jean Benhattar, Victor V LobanenkovAbstract:BORIS, like other members of the ‘cancer/testis antigen’ family, is normally expressed in testicular germ cells and repressed in somatic cells, but is aberrantly activated in cancers. To understand regulatory mechanisms governing human BORIS expression, we characterized its 5’-flanking region. Using 5’ RACE, we identified three promoters, designated A, B and C, corresponding to transcription start sites at � 1447, � 899 and � 658bp upstream of the first ATG. Alternative promoter usage generated at least five alternatively spliced BORIS mRNAs with different half-lives determined by varying 5’-UTRs. In normal testis, BORIS is transcribed from all three promoters, but 84% of the 30 cancer cell lines tested used only promoter(s) A and/or C while the others utilized primarily promoters B and C. The differences in promoter usage between normal and cancer cells suggested that they were subject to differential regulation. We found that DNA methylation and functional p53 contributes to the negative regulation of each promoter. Moreover, reduction of CTCF in normally BORIS-negative human fibroblasts resulted in derepression of BORIS promoters. These results provide a mechanistic basis for understanding cancer-related associations between haploinsufficiency of CTCF and BORIS derepression, and between the lack of functional p53 and aberrant activation of BORIS.
-
elicitation of t cell responses to histologically unrelated tumors by immunization with the novel cancer testis antigen brother of the regulator of imprinted sites
Journal of Immunology, 2007Co-Authors: Anahit Ghochikyan, Dmitri Loukinov, Svetlana Pack, Mikayel Mkrtichyan, Gregory Mamikonyan, Nina Movsesyan, Thomas E Ichim, David H Cribbs, Victor V Lobanenkov, Michael G AgadjanyanAbstract:Brother of the regulator of imprinted sites (BORIS) was previously described as a transcription factor for epigenetic reprogramming the expression of which is strictly confined to germ cells of adult testes but is aberrantly activated in the vast majority of neoplastic cells. Considering the critical role of BORIS in cancerogenesis and the fact that its expression pattern may preclude thymic tolerance, we generated DNA- and protein-based mouse BORIS antitumor vaccines using a non-DNA-binding version of the BORIS molecule. Clinical use of BORIS as a vaccine Ag would require that certain safety concerns be met. Specifically, administration of the functional BORIS protein would hypothetically pose a risk of BORIS accelerating the progression of cancer. To alleviate such safety concerns, we have developed vaccines based on the BORIS molecule lacking the DNA-binding zinc fingers domain. To enhance anti-BORIS cellular immune responses, we used a standard molecular adjuvant approach. It consisted of plasmids encoding murine IL-12 and IL-18 for a DNA-based vaccine and conventional Th1 type adjuvant, Quil A, for a protein-based vaccine. Both DNA- and protein-based vaccines induced Ag-specific CD4+ T cell proliferation with Th1 and Th2 cytokine profiles, respectively. Protein-based, but not DNA-based, BORIS vaccine induced a significant level of Ab production in immunized animals. Importantly, potent anticancer CD8+-cytotoxic lymphocytes were generated after immunization with the DNA-based, but not protein-based, BORIS vaccine. These cytolytic responses were observed across a wide range of different mouse cancers including mammary adenocarcinoma, glioma, leukemia, and mastocytoma.
Victor V Lobanenkov - One of the best experts on this subject based on the ideXlab platform.
-
transcription factor boris brother of the regulator of imprinted sites directly induces expression of a cancer testis antigen tsp50 through regulated binding of boris to the promoter
Journal of Biological Chemistry, 2011Co-Authors: Natsuki Kosakasuzuki, Dmitri Loukinov, Elena M Pugacheva, Alexander A Vostrov, Herbert C Morse, Teruhiko Suzuki, Victor V LobanenkovAbstract:Cancer-testis antigens (CTAs) are normally expressed in testis but are aberrantly expressed in a variety of cancers with varying frequency. More than 100 proteins have been identified as CTA including testes-specific protease 50 (TSP50) and the testis-specific paralogue of CCCTC-binding factor, BORIS (brother of the regulator of imprinted sites). Because many CTAs are considered as excellent targets for tumor immunotherapy, understanding the regulatory mechanisms governing their expression is important. In this study we demonstrate that BORIS is directly responsible for the transcriptional activation of TSP50. We found two BORIS binding sites in the TSP50 promoter that are highly conserved between mouse and human. Mutations of the binding sites resulted in loss of BORIS binding and the ability of BORIS to activate the promoter. However, although expression of BORIS was essential, it was not sufficient for high expression of TSP50 in cancer cells. Further studies showed that binding of BORIS to the target sites was methylation-independent but was diminished by nucleosomal occupancy consistent with the findings that high expression of TSP50 was associated with increased DNase I sensitivity and high BORIS occupancy of the promoter. These findings indicate that BORIS-induced expression of TSP50 is governed by accessibility and binding of BORIS to the promoter. To our knowledge this is the first report of regulated expression of one CTA by another to be validated in a physiological context.
-
expression of the ctcf paralogous cancer testis gene brother of the regulator of imprinted sites boris is regulated by three alternative promoters modulated by cpg methylation and by ctcf and p53 transcription factors
Nucleic Acids Research, 2007Co-Authors: Stephanie Renaud, Dmitri Loukinov, Elena M Pugacheva, Ziedulla Abdullaev, Dolores M Delgado, Richard Braunschweig, Jean Benhattar, Victor V LobanenkovAbstract:BORIS, like other members of the ‘cancer/testis antigen’ family, is normally expressed in testicular germ cells and repressed in somatic cells, but is aberrantly activated in cancers. To understand regulatory mechanisms governing human BORIS expression, we characterized its 5’-flanking region. Using 5’ RACE, we identified three promoters, designated A, B and C, corresponding to transcription start sites at � 1447, � 899 and � 658bp upstream of the first ATG. Alternative promoter usage generated at least five alternatively spliced BORIS mRNAs with different half-lives determined by varying 5’-UTRs. In normal testis, BORIS is transcribed from all three promoters, but 84% of the 30 cancer cell lines tested used only promoter(s) A and/or C while the others utilized primarily promoters B and C. The differences in promoter usage between normal and cancer cells suggested that they were subject to differential regulation. We found that DNA methylation and functional p53 contributes to the negative regulation of each promoter. Moreover, reduction of CTCF in normally BORIS-negative human fibroblasts resulted in derepression of BORIS promoters. These results provide a mechanistic basis for understanding cancer-related associations between haploinsufficiency of CTCF and BORIS derepression, and between the lack of functional p53 and aberrant activation of BORIS.
-
elicitation of t cell responses to histologically unrelated tumors by immunization with the novel cancer testis antigen brother of the regulator of imprinted sites
Journal of Immunology, 2007Co-Authors: Anahit Ghochikyan, Dmitri Loukinov, Svetlana Pack, Mikayel Mkrtichyan, Gregory Mamikonyan, Nina Movsesyan, Thomas E Ichim, David H Cribbs, Victor V Lobanenkov, Michael G AgadjanyanAbstract:Brother of the regulator of imprinted sites (BORIS) was previously described as a transcription factor for epigenetic reprogramming the expression of which is strictly confined to germ cells of adult testes but is aberrantly activated in the vast majority of neoplastic cells. Considering the critical role of BORIS in cancerogenesis and the fact that its expression pattern may preclude thymic tolerance, we generated DNA- and protein-based mouse BORIS antitumor vaccines using a non-DNA-binding version of the BORIS molecule. Clinical use of BORIS as a vaccine Ag would require that certain safety concerns be met. Specifically, administration of the functional BORIS protein would hypothetically pose a risk of BORIS accelerating the progression of cancer. To alleviate such safety concerns, we have developed vaccines based on the BORIS molecule lacking the DNA-binding zinc fingers domain. To enhance anti-BORIS cellular immune responses, we used a standard molecular adjuvant approach. It consisted of plasmids encoding murine IL-12 and IL-18 for a DNA-based vaccine and conventional Th1 type adjuvant, Quil A, for a protein-based vaccine. Both DNA- and protein-based vaccines induced Ag-specific CD4+ T cell proliferation with Th1 and Th2 cytokine profiles, respectively. Protein-based, but not DNA-based, BORIS vaccine induced a significant level of Ab production in immunized animals. Importantly, potent anticancer CD8+-cytotoxic lymphocytes were generated after immunization with the DNA-based, but not protein-based, BORIS vaccine. These cytolytic responses were observed across a wide range of different mouse cancers including mammary adenocarcinoma, glioma, leukemia, and mastocytoma.
-
the novel boris ctcf gene family is uniquely involved in the epigenetics of normal biology and cancer
Seminars in Cancer Biology, 2002Co-Authors: Elena Klenova, Herbert C Morse, Rolf Ohlsson, Victor V LobanenkovAbstract:CTCF is a ubiquitous 11 zinc finger (ZF) protein with highly versatile functions: in addition to transcriptional silencing or activating in a context-dependent fashion, it organizes epigenetically controlled chromatin insulators that regulate imprinted genes in soma. Recently, we have identified a CTCF paralogue, termed BORIS for Brother of the Regulator of Imprinted Sites, that is expressed only in the testis. BORIS has the same exons encoding the 11 ZF domain as mammalian CTCF genes, and hence interacts with similar cis elements, but encodes amino and carboxy termini distinct from those in CTCF. Normally, CTCF and BORIS are expressed in a mutually exclusive pattern that correlates with re-setting of methylation marks during male germ cell differentiation. The antagonistic features of these two gene siblings are underscored by showing that while CTCF overexpression blocks cell proliferation, expression of BORIS in normally BORIS-negative cells promotes cell growth which can lead to transformation. The suggestion that BORIS directs epigenetic reprogramming at CTCF target sites impinges on the observations that human BORIS is not only abnormally activated in a wide range of human cancers, but also maps to the cancer-associated amplification region at 20q13. The sibling rivalry occasioned by aberrant expression of BORIS in cancer may interfere with normal functions of CTCF including growth suppression, and contribute to epigenetic dysregulation which is a common feature in human cancer.
Hirotoshi Hasegawa - One of the best experts on this subject based on the ideXlab platform.
-
cancer testis antigen boris is a novel prognostic marker for patients with esophageal cancer
Cancer Science, 2012Co-Authors: Koji Okabayashi, Junichiro Miyazaki, Tsutomu Okada, Shinobu Noji, Nobuo Tsukamoto, Tomonobu Fujita, Naoki Goshima, Takashi Iwata, Nobumaru Hirao, Hirotoshi HasegawaAbstract:Esophageal squamous cell cancer (ESCC) is one of the most common lethal tumors in the world, and development of new diagnostic and therapeutic methods is needed. In this study, cancer-testis antigen, BORIS, was isolated by functional cDNA expression cloning using screening technique with serum IgG Abs from ESCC patients. BORIS was previously reported to show cancer-testis antigen like expression, but its immunogenicity has remained unclear in cancer patients. BORIS was considered to be an immunogenic antigen capable of inducing IgG Abs in patients with various cancers, including four of 11 ESCC patients. Immunohistochemical study showed that the BORIS protein was expressed in 28 of 50 (56%) ESCC tissues. The BORIS expression was significantly associated with lymph node metastasis in ESCC patients with pT1 disease (P = 0.036). Furthermore, the patients with BORIS-positive tumors had a poor overall survival (5-year survival rate: BORIS-negative 70.0% vs BORIS-positive 29.9%, log-rank P = 0.028) in Kaplan–Meier survival analysis and log-rank test. Multivariate Cox proportional hazard model demonstrated that BORIS expression was an independent poor prognostic factor (hazard ratio = 4.158 [95% confidence interval 1.494–11.57], P = 0.006). Downregulation of BORIS with specific siRNAs resulted in decreased cell proliferation and invasion ability of ESCC cell lines. BORIS may be a useful biomarker for prognostic diagnosis of ESCC patients and a potential target for treatment including by BORIS-specific immunotherapy and molecular target therapy.
L. Soudarin - One of the best experts on this subject based on the ideXlab platform.
-
On-line Resources Supporting the Data, Products, and Information Infrastructure for the International DORIS Service
Journal of Geodesy, 2006Co-Authors: C. Noll, L. SoudarinAbstract:The International DORIS Service (IDS) was formed under the direction of the International Association of Geodesy (IAG) in 2003 to support geodetic research utilizing DORIS data and products. The IDS is organized into a hierarchy of components: network of Tracking Stations, Satellite Segment, Data Centers, Analysis Centers, Central Bureau, and Governing Board. The DORIS infrastructure consists of a globally distributed network of over 50 ground beacons and a constellation of five satellites equipped with receivers that relay range rate measurements through a central collection facility to the IDS archives. The Data Centers and Central Bureau supporting the IDS are the primary means of distributing DORIS data, products, and general information to the user community. These facilities utilize Web and ftp servers, as well as an email service, to support the users of DORIS data and products. The current status and recent developments of these components are discussed, as well as a review of available information, data, and geodetic product types.
