The Experts below are selected from a list of 20493 Experts worldwide ranked by ideXlab platform
Valerie Wittamer - One of the best experts on this subject based on the ideXlab platform.
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characterization of the mononuclear phagocyte system in zebrafish
Blood, 2011Co-Authors: Valerie Wittamer, Julien Y Bertrand, Patrick Gutschow, David TraverAbstract:The evolutionarily conserved immune system of the zebrafish (Danio rerio), in combination with its Genetic tractability, position it as an excellent model system in which to elucidate the origin and function of vertebrate immune cells. We recently reported the existence of antigen-presenting mononuclear phagocytes in zebrafish, namely macrophages and dendritic cells (DCs), but have been impaired in further characterizing the biology of these cells by the lack of a specific transgenic reporter line. Using regulatory elements of a class II major Histocompatibility Gene, we Generated a zebrafish reporter line expressing green fluorescent protein (GFP) in all APCs, macrophages, DCs, and B lymphocytes. Examination of mhc2dab:GFP; cd45:DsRed double-transgenic animals demonstrated that kidney mhc2dab:GFP(hi); cd45:DsRed(hi) cells were exclusively mature monocytes/macrophages and DCs, as revealed by morphologic and molecular analyses. Mononuclear phagocytes were found in all hematolymphoid organs, but were most abundant in the intestine and spleen, where they up-regulate the expression of inflammatory cytokines upon bacterial challenge. Finally, mhc2dab:GFP and cd45:DsRed transGenes mark mutually exclusive cell subsets in the lymphoid fraction, enabling the delineation of the major hematopoietic lineages in the adult zebrafish. These findings suggest that mhc2dab:GFP and cd45:DsRed transgenic lines will be instrumental in elucidating the immune response in the zebrafish.
Irving L Weissman - One of the best experts on this subject based on the ideXlab platform.
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Urochordata: Botryllus – Natural Chimerism and Tolerance Induction in a Colonial Chordate
Advances in Comparative Immunology, 2018Co-Authors: Ayelet Voskoboynik, Aaron M Newman, Mark Kowarsky, Irving L WeissmanAbstract:Chimerism is defined as the coexistence of two or more genomes of separate origin within an individual. In placental mammals such as humans, natural chimerism develops during pregnancy between a mother and fetus and has an important role in the induction of fetal tolerance to maternal tissues. Natural chimerism between kin also occurs in colonial ascidians, the closest extant ancestors of chordates. In the ascidian, Botryllus schlosseri, some colonies fuse to create lifelong chimeric entities of two alloGeneic genomes. The decision to fuse in B. schlosseri is governed by a polymorphic Histocompatibility Gene called the Botryllus Histocompatibility factor (BHF). Colonies that share at least one BHF allele fuse upon contact, whereas colonies without any BHF alleles in common ultimately reject. Following vasculature fusion, stem cells from each histocompatible B. schlosseri colony compete to overtake germline or somatic lineages. Stem cell competition may lead to elimination of the other colony’s genome, or it may produce a chimeric colony with mixed genotypes. In this way, chimerism in B. schlosseri represents a nexus between stem cell competition, genome parasitism, and allorecognition. Here we review studies conducted over six decades that led to the discoveries of the nature of the cells that mediate chimerism in colonial ascidians and the Gene that controls it.
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urochordata botryllus natural chimerism and tolerance induction in a colonial chordate
2018Co-Authors: Ayelet Voskoboynik, Aaron M Newman, Mark Kowarsky, Irving L WeissmanAbstract:Chimerism is defined as the coexistence of two or more genomes of separate origin within an individual. In placental mammals such as humans, natural chimerism develops during pregnancy between a mother and fetus and has an important role in the induction of fetal tolerance to maternal tissues. Natural chimerism between kin also occurs in colonial ascidians, the closest extant ancestors of chordates. In the ascidian, Botryllus schlosseri, some colonies fuse to create lifelong chimeric entities of two alloGeneic genomes. The decision to fuse in B. schlosseri is governed by a polymorphic Histocompatibility Gene called the Botryllus Histocompatibility factor (BHF). Colonies that share at least one BHF allele fuse upon contact, whereas colonies without any BHF alleles in common ultimately reject. Following vasculature fusion, stem cells from each histocompatible B. schlosseri colony compete to overtake germline or somatic lineages. Stem cell competition may lead to elimination of the other colony’s genome, or it may produce a chimeric colony with mixed genotypes. In this way, chimerism in B. schlosseri represents a nexus between stem cell competition, genome parasitism, and allorecognition. Here we review studies conducted over six decades that led to the discoveries of the nature of the cells that mediate chimerism in colonial ascidians and the Gene that controls it.
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allorecognition Histocompatibility in a protochordate species is the relationship to mhc somatic or structural
Immunological Reviews, 1990Co-Authors: Irving L Weissman, Yasunori Saito, Baruch RinkevichAbstract:: Colonial tunicates are complex marine invertebrates (in fact protochordates) that undergo a variety of Histocompatibility reactions in their intraspecific competition for feeding surfaces. By means of these reactions colonies fuse with kin, extend domination over a feeding surface, while isolating unrelated conspecifics. The primary determinant of fusion (with kin) or rejection (of non-kin) is a single, highly polymorphic, Histocompatibility Gene locus (or haplotype), called Fu/HC. Following fusion with nonidentical kin sharing 1 or more Fu/HC allele(s), the fused pair expands both chimeric partners via an asexual budding process, further extending domination over a feeding surface. However, at some later time point an intense set of histoincompatibility reactions occurs between fused kin, resulting in the destruction of all individuals of one of the genotypes, ending the chimeric state. In this review we describe what is known of the Genetics and several biological properties encoded by the Fu/HC, and the several independent Gene loci that control the colony resorption phenomena that return the colony to the province of a single genotypic individual.
David Traver - One of the best experts on this subject based on the ideXlab platform.
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characterization of the mononuclear phagocyte system in zebrafish
Blood, 2011Co-Authors: Valerie Wittamer, Julien Y Bertrand, Patrick Gutschow, David TraverAbstract:The evolutionarily conserved immune system of the zebrafish (Danio rerio), in combination with its Genetic tractability, position it as an excellent model system in which to elucidate the origin and function of vertebrate immune cells. We recently reported the existence of antigen-presenting mononuclear phagocytes in zebrafish, namely macrophages and dendritic cells (DCs), but have been impaired in further characterizing the biology of these cells by the lack of a specific transgenic reporter line. Using regulatory elements of a class II major Histocompatibility Gene, we Generated a zebrafish reporter line expressing green fluorescent protein (GFP) in all APCs, macrophages, DCs, and B lymphocytes. Examination of mhc2dab:GFP; cd45:DsRed double-transgenic animals demonstrated that kidney mhc2dab:GFP(hi); cd45:DsRed(hi) cells were exclusively mature monocytes/macrophages and DCs, as revealed by morphologic and molecular analyses. Mononuclear phagocytes were found in all hematolymphoid organs, but were most abundant in the intestine and spleen, where they up-regulate the expression of inflammatory cytokines upon bacterial challenge. Finally, mhc2dab:GFP and cd45:DsRed transGenes mark mutually exclusive cell subsets in the lymphoid fraction, enabling the delineation of the major hematopoietic lineages in the adult zebrafish. These findings suggest that mhc2dab:GFP and cd45:DsRed transgenic lines will be instrumental in elucidating the immune response in the zebrafish.
Baruch Rinkevich - One of the best experts on this subject based on the ideXlab platform.
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the candidate fu hc Gene in botryllus schlosseri urochordata and ascidians historecognition an oxymoron
Developmental and Comparative Immunology, 2012Co-Authors: Baruch Rinkevich, Jacob Douek, Claudette RabinowitzAbstract:Abstract Allorecognition, distinguishing self from non-self alloGeneic tissues is the underlying basis of innate immunity. In the colonial tunicate Botryllus schlosseri this historecognition is governed at a single Genetic locus, Fu/HC (for fusibility/Histocompatibility), with hundreds of co-dominantly expressed alleles. Several years ago, De Tomaso et al. (2005) have revolutionized the discipline of invertebrate allorecognition by describing a novel form of immune recognition in B. schlosseri , a non-vertebrate candidate Histocompatibility Gene (cFu/HC), revealing that allorecognition machinery in urochordates has nothing in common with the vertebrates’ MHC-based Histocompatibility. The authors reported absolute concordance of fusibility and cFu/HC genotype, predicted fusion/rejection outcomes in allorecognition settings from allelic polymorphism at the cFu/HC, also claiming cFu/HC Gene expressions only in tissues directly engaged in Histocompatibility. Here, we raise queries for the validity of the results and conclusions of De Tomaso et al. (2005) publication. Our reservations include discrepancies in the paper’s results, including the perplexing absence of key sequencing material from public domains and above all, our own impugning outcomes. These include cloning efforts, in situ hybridization results, semi quantitative PCR outcomes, and the incongruence emerged between fusion/rejection profiles and cFu/HC segregated polymorphism that separately and cumulatively contradict the original publication. We conclude that Botryllus Histocompatibility properties are not signaled in the claimed cFu/HC and that cFu/HC Gene is unlikely the allodeterminant for Botryllus Histocompatibility locus. Hence, the molecular nature of the Fu/HC locus in botryllid ascidians is still awaiting elucidation.
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The candidate Fu/HC Gene in Botryllus schlosseri (Urochordata) and ascidians’ historecognition – An oxymoron?
Developmental and Comparative Immunology, 2011Co-Authors: Baruch Rinkevich, Jacob Douek, Claudette RabinowitzAbstract:Abstract Allorecognition, distinguishing self from non-self alloGeneic tissues is the underlying basis of innate immunity. In the colonial tunicate Botryllus schlosseri this historecognition is governed at a single Genetic locus, Fu/HC (for fusibility/Histocompatibility), with hundreds of co-dominantly expressed alleles. Several years ago, De Tomaso et al. (2005) have revolutionized the discipline of invertebrate allorecognition by describing a novel form of immune recognition in B. schlosseri , a non-vertebrate candidate Histocompatibility Gene (cFu/HC), revealing that allorecognition machinery in urochordates has nothing in common with the vertebrates’ MHC-based Histocompatibility. The authors reported absolute concordance of fusibility and cFu/HC genotype, predicted fusion/rejection outcomes in allorecognition settings from allelic polymorphism at the cFu/HC, also claiming cFu/HC Gene expressions only in tissues directly engaged in Histocompatibility. Here, we raise queries for the validity of the results and conclusions of De Tomaso et al. (2005) publication. Our reservations include discrepancies in the paper’s results, including the perplexing absence of key sequencing material from public domains and above all, our own impugning outcomes. These include cloning efforts, in situ hybridization results, semi quantitative PCR outcomes, and the incongruence emerged between fusion/rejection profiles and cFu/HC segregated polymorphism that separately and cumulatively contradict the original publication. We conclude that Botryllus Histocompatibility properties are not signaled in the claimed cFu/HC and that cFu/HC Gene is unlikely the allodeterminant for Botryllus Histocompatibility locus. Hence, the molecular nature of the Fu/HC locus in botryllid ascidians is still awaiting elucidation.
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allorecognition Histocompatibility in a protochordate species is the relationship to mhc somatic or structural
Immunological Reviews, 1990Co-Authors: Irving L Weissman, Yasunori Saito, Baruch RinkevichAbstract:: Colonial tunicates are complex marine invertebrates (in fact protochordates) that undergo a variety of Histocompatibility reactions in their intraspecific competition for feeding surfaces. By means of these reactions colonies fuse with kin, extend domination over a feeding surface, while isolating unrelated conspecifics. The primary determinant of fusion (with kin) or rejection (of non-kin) is a single, highly polymorphic, Histocompatibility Gene locus (or haplotype), called Fu/HC. Following fusion with nonidentical kin sharing 1 or more Fu/HC allele(s), the fused pair expands both chimeric partners via an asexual budding process, further extending domination over a feeding surface. However, at some later time point an intense set of histoincompatibility reactions occurs between fused kin, resulting in the destruction of all individuals of one of the genotypes, ending the chimeric state. In this review we describe what is known of the Genetics and several biological properties encoded by the Fu/HC, and the several independent Gene loci that control the colony resorption phenomena that return the colony to the province of a single genotypic individual.
Claudette Rabinowitz - One of the best experts on this subject based on the ideXlab platform.
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the candidate fu hc Gene in botryllus schlosseri urochordata and ascidians historecognition an oxymoron
Developmental and Comparative Immunology, 2012Co-Authors: Baruch Rinkevich, Jacob Douek, Claudette RabinowitzAbstract:Abstract Allorecognition, distinguishing self from non-self alloGeneic tissues is the underlying basis of innate immunity. In the colonial tunicate Botryllus schlosseri this historecognition is governed at a single Genetic locus, Fu/HC (for fusibility/Histocompatibility), with hundreds of co-dominantly expressed alleles. Several years ago, De Tomaso et al. (2005) have revolutionized the discipline of invertebrate allorecognition by describing a novel form of immune recognition in B. schlosseri , a non-vertebrate candidate Histocompatibility Gene (cFu/HC), revealing that allorecognition machinery in urochordates has nothing in common with the vertebrates’ MHC-based Histocompatibility. The authors reported absolute concordance of fusibility and cFu/HC genotype, predicted fusion/rejection outcomes in allorecognition settings from allelic polymorphism at the cFu/HC, also claiming cFu/HC Gene expressions only in tissues directly engaged in Histocompatibility. Here, we raise queries for the validity of the results and conclusions of De Tomaso et al. (2005) publication. Our reservations include discrepancies in the paper’s results, including the perplexing absence of key sequencing material from public domains and above all, our own impugning outcomes. These include cloning efforts, in situ hybridization results, semi quantitative PCR outcomes, and the incongruence emerged between fusion/rejection profiles and cFu/HC segregated polymorphism that separately and cumulatively contradict the original publication. We conclude that Botryllus Histocompatibility properties are not signaled in the claimed cFu/HC and that cFu/HC Gene is unlikely the allodeterminant for Botryllus Histocompatibility locus. Hence, the molecular nature of the Fu/HC locus in botryllid ascidians is still awaiting elucidation.
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The candidate Fu/HC Gene in Botryllus schlosseri (Urochordata) and ascidians’ historecognition – An oxymoron?
Developmental and Comparative Immunology, 2011Co-Authors: Baruch Rinkevich, Jacob Douek, Claudette RabinowitzAbstract:Abstract Allorecognition, distinguishing self from non-self alloGeneic tissues is the underlying basis of innate immunity. In the colonial tunicate Botryllus schlosseri this historecognition is governed at a single Genetic locus, Fu/HC (for fusibility/Histocompatibility), with hundreds of co-dominantly expressed alleles. Several years ago, De Tomaso et al. (2005) have revolutionized the discipline of invertebrate allorecognition by describing a novel form of immune recognition in B. schlosseri , a non-vertebrate candidate Histocompatibility Gene (cFu/HC), revealing that allorecognition machinery in urochordates has nothing in common with the vertebrates’ MHC-based Histocompatibility. The authors reported absolute concordance of fusibility and cFu/HC genotype, predicted fusion/rejection outcomes in allorecognition settings from allelic polymorphism at the cFu/HC, also claiming cFu/HC Gene expressions only in tissues directly engaged in Histocompatibility. Here, we raise queries for the validity of the results and conclusions of De Tomaso et al. (2005) publication. Our reservations include discrepancies in the paper’s results, including the perplexing absence of key sequencing material from public domains and above all, our own impugning outcomes. These include cloning efforts, in situ hybridization results, semi quantitative PCR outcomes, and the incongruence emerged between fusion/rejection profiles and cFu/HC segregated polymorphism that separately and cumulatively contradict the original publication. We conclude that Botryllus Histocompatibility properties are not signaled in the claimed cFu/HC and that cFu/HC Gene is unlikely the allodeterminant for Botryllus Histocompatibility locus. Hence, the molecular nature of the Fu/HC locus in botryllid ascidians is still awaiting elucidation.