The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Baruch Rinkevich - One of the best experts on this subject based on the ideXlab platform.
-
Epithelial cell cultures from Botryllus schlosseri palleal buds: accomplishments and challenges.
Methods in cell science : an official journal of the Society for In Vitro Biology, 2020Co-Authors: Claudette Rabinowitz, Baruch RinkevichAbstract:This study focuses on recent improvement in epithelial monolayer cultures originating from whole extirpated Botryllus schlosseri (Urochordata) buds. Buds (n = 2,000) were taken at different ('A' to 'D') blastogenic stages. We tested the suitability of 35 combinations of various substrates and media on attachment, cell spread, epithelial growth frequencies and on monolayer lifespans. Under favorable conditions, cultured buds at blastogenic stages 'B' to 'D' (but not stage 'A') started to attach to the substrates following a 3-day transient period that leads to formation of spheres and attached monolayers. Substrate type is important for the attachment and the development of monolayers. Under various culture conditions, some of stages 'B' and 'C' buds develop (3-20 days) one or more large (1 mm diameter) spheres. Stage 'D' buds develop monolayers (up to 20% of buds) without going through a sphere phase. Neither spheres nor attached monolayers of epithelium were observed in stage 'A' bud cultures. Spheres grew at a rate of 60 microm in diameter per day using specific medium types and did not attach unless the appropriate substrate was present. When attached, epithelial monolayers expanded at a rate of 200 microm in diameter per day, for 3-15 days, and subsequently detached and died. Sixteen types of media were tested. Medium and substrate combinations were found to determine epithelial lifespan. These results revealed significant improvements in the culture of epithelial monolayers from Botryllus palleal buds. However, an early senescence of the developed epithelial sheets (up to two weeks from onset of appearance) may indicate an internal ageing clock that should be taken into consideration in future approaches.
-
Cell Communication-mediated Nonself-Recognition and -Intolerance in Representative Species of the Animal Kingdom
Journal of Molecular Evolution, 2020Co-Authors: Werner A. Mueller, Baruch RinkevichAbstract:Why has histo-incompatibility arisen in evolution and can cause self-intolerance? Compatible/incompatible reactions following natural contacts between genetically-different (allogeneic) colonies of marine organisms have inspired the conception that self–nonself discrimination has developed to reduce invasion threats by migratory foreign germ/somatic stem cells, in extreme cases resulting in conquest of the whole body by a foreign genome. Two prominent model species for allogeneic discrimination are the marine invertebrates Hydractinia (Cnidaria) and Botryllus (Ascidiacea). In Hydractinia , self–nonself recognition is based on polymorphic surface markers encoded by two genes ( alr1, alr2 ), with self recognition enabled by homophilic binding of identical ALR molecules. Variable expression patterns of alr alleles presumably account for the first paradigm of autoaggression in an invertebrate. In Botryllus, self–nonself recognition is controlled by a single polymorphic gene locus ( BHF ) with hundreds of codominantly expressed alleles. Fusion occurs when both partners share at least one BHF allele while rejection develops when no allele is shared. Molecules involved in allorecognition frequently contain immunoglobulin or Ig-like motifs, case-by-case supplemented by additional molecules enabling homophilic interaction, while the mechanisms applied to destroy allogeneic grafts or neighbors include taxon-specific tools besides common facilities of natural immunity. The review encompasses comparison with allorecognition in mammals based on MHC-polymorphism in transplantation and following feto-maternal cell trafficking.
-
UV-B radiation bearings on ephemeral soma in the shallow water tunicate Botryllus schlosseri.
Ecotoxicology and Environmental Safety, 2020Co-Authors: Andy Qarri, Claudette Rabinowitz, Amalia Rosner, Baruch RinkevichAbstract:Abstract Sedentary shallow water marine organisms acquire numerous protective mechanisms to mitigate the detrimental effects of UV radiation (UV-R). Here we investigated morphological and gene expression outcomes in colonies of the cosmopolitan ascidian Botryllus schlosseri, up to 15-days post UV-B irradiation. Astogeny in Botryllus is characterized by weekly repeating sets of asexual budding, coinciding with apoptotic elimination of functional zooids (blastogenesis). Ten UV-B doses were administered to three clusters: sublethal, enhanced-mortality, lethal (LD50 = 6.048 kJ/m2) which differed in mortality rates, yet reflected similar distorted morphotypes, and arrested blastogenesis, all intensified in the enhanced-mortality/lethal clusters. Even the sub-lethal doses inflicted expression modifications in 8 stress proteins (HSP 90/70 families and NIMA) as well as morphological blastogenesis. The morphological/gene-expression impacts in surviving colonies lasted for 15 days post irradiation (two blastogenic-cycles), where all damaged and arrested zooids/buds were absorbed, after which the colonies returned to their normal blastogenic-cycles and gene expression profiles, and initiated new buds. The above reflects a novel colonial maintenance strategy associated with the disposable-soma tenet, where the ephemeral soma in Botryllus is eliminated without engaging with the costs of repair, whereas other colonial components, primarily the pool of totipotent stem cells, are sustained under yet unknown colonial-level regulatory cues.
-
coupling astogenic aging in the colonial tunicate Botryllus schlosseri with the stress protein mortalin
Developmental Biology, 2018Co-Authors: Claudette Rabinowitz, Amalia Rosner, Matan Oren, Oshrat Benhamo, Baruch RinkevichAbstract:Abstract Botryllus schlosseri, a colonial marine invertebrate, exhibits three generations of short-lived astogenic modules that continuously grow and die throughout the colony's entire lifespan, within week-long repeating budding cycles (blastogenesis), each consisting of four stages (A-D). At stage D, aging is followed by the complete absorption of adult modules (zooids) via a massive apoptotic process. Here we studied in Botryllus the protein mortalin (HSP70s member), a molecule largely known for its association with aging and proliferation. In-situ hybridization and qPCR assays reveal that mortalin follows the cyclic pattern of blastogenesis. Colonies at blastogenic stage D display the highest mortalin levels, and young modules exhibit elevated mortalin levels compared to old modules. Manipulations of mortalin with the specific allosteric inhibitor MKT-077 has led to a decrease in the modules’ growth rate and the development of abnormal somatic/germinal morphologies (primarily in vasculature and in organs such as the endostyle, the stomach and gonads). We therefore propose that mortalin plays a significant role in the astogeny and aging of colonial modules in B. schlosseri, by direct involvement in the regulation of blastogenesis.
-
Botryllus schlosseri and Botrylloides leachii (Chordata, Ascidiacea) have not been recorded in the Red Sea
Marine Biodiversity, 2014Co-Authors: Eitan Reem, Baruch RinkevichAbstract:Two botryllid species, Botryllus schlosseri and Botrylloides leachii are listed in a recent literature review on the ascidian species inventory from the Red Sea (Shenkar, Mar Biodiv 42:459–469, 2012). However, a detailed literature search does not reveal any scientific documentation for the existence of these species in the Red Sea.
Anthony W De Tomaso - One of the best experts on this subject based on the ideXlab platform.
-
the biology of the extracorporeal vasculature of Botryllus schlosseri
Developmental Biology, 2019Co-Authors: Delany Rodriguez, Shane Nourizadeh, Anthony W De TomasoAbstract:Abstract The extracorporeal vasculature of the colonial ascidian Botryllus schlosseri plays a key role in several biological processes: transporting blood, angiogenesis, regeneration, self-nonself recognition, and parabiosis. The vasculature also interconnects all individuals in a colony and is composed of a single layer of ectodermally-derived cells. These cells form a tube with the basal lamina facing the lumen, and the apical side facing an extracellular matrix that consists of cellulose and other proteins, known as the tunic. Vascular tissue is transparent and can cover several square centimeters, which is much larger than any single individual within the colony. It forms a network that ramifies and expands to the perimeter of each colony and terminates into oval-shaped protrusions known as ampullae. Botryllus individuals replace themselves through a weekly budding cycle, and vasculature is added to ensure the interconnection of each new individual, thus there is continuous angiogenesis occurring naturally. The vascular tissue itself is highly regenerative; surgical removal of the ampullae and peripheral vasculature triggers regrowth within 24–48 h, which includes forming new ampullae. When two individuals, whether in the wild or in the lab, come into close contact and their ampullae touch, they can either undergo parabiosis through anastomosing vessels, or reject vascular fusion. The vasculature is easily manipulated by direct means such as microinjections, microsurgeries, and pharmacological reagents. Its transparent nature allows for in vivo analysis by bright field and fluorescence microscopy. Here we review the techniques and approaches developed to study the different biological processes that involve the extracorporeal vasculature.
-
Temporally and spatially dynamic germ cell niches in Botryllus schlosseri revealed by expression of a TGF-beta family ligand and vasa
EvoDevo, 2016Co-Authors: Adam D. Langenbacher, Anthony W De TomasoAbstract:Background Germ cells are specified during early development and are responsible for generating gametes in the adult. After germ cells are specified, they typically migrate to a particular niche in the organism where they reside for the remainder of its lifetime. For some model organisms, the specification and migration of germ cells have been extensively studied, but how these events occur in animals that reproduce both sexually and asexually is not well understood. Results We have identified a novel TGF-β family member in Botryllus schlosseri , tgfβ - f , and found that it is expressed by follicle cell progenitors and the differentiated follicle and support cells surrounding the maturing gametes. Using the expression of tgfβ - f and the germ cell marker vasa , we have found that nearly all germ cells in Botryllus are associated with tgfβ - f -expressing follicle progenitors in clusters consisting solely of those two cell types. These clusters were mostly small, consisting of ten or fewer cells, and generally contained between a 2:1 and 1:1 ratio of follicle progenitors to germ cells. Clusters of germ and follicle progenitor cells were primarily localized to niches in the primary and secondary buds, but could also be found in other locations including the vasculature. We analyzed the location of germ cell clusters throughout the asexual life cycle of Botryllus and found that at the stage when germ cells are first detected in the secondary bud niche, a dramatic change in the size and location of germ/follicle cell clusters also occurred. Conclusions Our findings suggest that germ/follicle cell clusters have predictable migratory patterns during the weekly asexual developmental cycle in Botryllus . An increased number of small clusters and the presence of clusters in the vasculature coinciding with the appearance of clusters in the secondary bud suggest that fragmentation of clusters and the migration of smaller clusters through the vasculature may be an important aspect of Botryllus reproductive biology, ensuring the transmission of the germline to subsequent asexual generations.
-
temporally and spatially dynamic germ cell niches in Botryllus schlosseri revealed by expression of a tgf beta family ligand and vasa
Evodevo, 2016Co-Authors: Adam D. Langenbacher, Anthony W De TomasoAbstract:Germ cells are specified during early development and are responsible for generating gametes in the adult. After germ cells are specified, they typically migrate to a particular niche in the organism where they reside for the remainder of its lifetime. For some model organisms, the specification and migration of germ cells have been extensively studied, but how these events occur in animals that reproduce both sexually and asexually is not well understood. We have identified a novel TGF-β family member in Botryllus schlosseri, tgfβ-f, and found that it is expressed by follicle cell progenitors and the differentiated follicle and support cells surrounding the maturing gametes. Using the expression of tgfβ-f and the germ cell marker vasa, we have found that nearly all germ cells in Botryllus are associated with tgfβ-f-expressing follicle progenitors in clusters consisting solely of those two cell types. These clusters were mostly small, consisting of ten or fewer cells, and generally contained between a 2:1 and 1:1 ratio of follicle progenitors to germ cells. Clusters of germ and follicle progenitor cells were primarily localized to niches in the primary and secondary buds, but could also be found in other locations including the vasculature. We analyzed the location of germ cell clusters throughout the asexual life cycle of Botryllus and found that at the stage when germ cells are first detected in the secondary bud niche, a dramatic change in the size and location of germ/follicle cell clusters also occurred. Our findings suggest that germ/follicle cell clusters have predictable migratory patterns during the weekly asexual developmental cycle in Botryllus. An increased number of small clusters and the presence of clusters in the vasculature coinciding with the appearance of clusters in the secondary bud suggest that fragmentation of clusters and the migration of smaller clusters through the vasculature may be an important aspect of Botryllus reproductive biology, ensuring the transmission of the germline to subsequent asexual generations.
-
Molecular evolution and in vitro characterization of Botryllus histocompatibility factor
Immunogenetics, 2015Co-Authors: Daryl A Taketa, Marie L. Nydam, Adam D. Langenbacher, Delany Rodriguez, Erin Sanders, Anthony W De TomasoAbstract:Botryllus schlosseri is a colonial ascidian with a natural ability to anastomose with another colony to form a vascular and hematopoietic chimera. In order to fuse, two individuals must share at least one allele at the highly polymorphic fuhc locus. Otherwise, a blood-based inflammatory response will occur resulting in a melanin scar at the sites of interaction. The single-locus genetic control of allorecognition makes B. schlosseri an attractive model to study the underlying molecular mechanisms. Over the past decade, several candidate genes involved in allorecognition have been identified, but how they ultimately contribute to allorecognition outcome remains poorly understood. Here, we report our initial molecular characterization of a recently identified candidate allodeterminant called Botryllus histocompatibility factor ( bhf ). bhf , both on a DNA and protein level, is the least polymorphic protein in the fuhc locus studied so far and, unlike other known allorecognition determinants, does not appear to be under any form of balancing or directional selection. Additionally, we identified a second isoform through mRNA-Seq and an EST assembly library which is missing exon 3, resulting in a C-terminally truncated form. We report via whole-mount fluorescent in situ hybridization that a subset of cells co-express bhf and cfuhc ^ sec . Finally, we observed BHF’s localization in HEK293T at the cytoplasmic side of the plasma membrane in addition to the nucleus via a nuclear localization signal. Given the localization data thus far, we hypothesize that BHF may function as a scaffolding protein in a complex with other Botryllus proteins, rather than functioning as an allorecognition determinant.
-
aging in the colonial chordate Botryllus schlosseri
Invertebrate Reproduction & Development, 2015Co-Authors: Roma Munday, Daryl A Taketa, Adam D. Langenbacher, Delany Rodriguez, Alessandro Di Maio, Susannah H Kassmer, Brian P Braden, Anthony W De TomasoAbstract:What mechanisms underlie aging? One theory, the wear-and-tear model, attributes aging to progressive deterioration in the molecular and cellular machinery which eventually lead to death through the disruption of physiological homeostasis. The second suggests that life span is genetically programmed, and aging may be derived from intrinsic processes which enforce a non-random, terminal time interval for the survivability of the organism. We are studying an organism that demonstrates both properties: the colonial ascidian, Botryllus schlosseri. Botryllus is a member of the Tunicata, the sister group to the vertebrates, and has a number of life history traits which make it an excellent model for studies on aging. First, Botryllus has a colonial life history, and grows by a process of asexual reproduction during which entire bodies, including all somatic and germline lineages, regenerate every week, resulting in a colony of genetically identical individuals. Second, previous studies of lifespan in genetically...
Loriano Ballarin - One of the best experts on this subject based on the ideXlab platform.
-
Immunolocation of phenoloxidase in vacuoles of the compound ascidian Botryllus schlosseri morula cells
Italian Journal of Zoology, 2020Co-Authors: Annalisa Frizzo, Loriano Ballarin, Laura Guidolin, Barbara Baldan, Armando SabbadinAbstract:Abstract Using a polyclonal antibody raised against purified phenoloxidase from the colonial ascidian Botryllus schlossen, we studied its distribution among haemocytes and its intracellular location. The enzyme is present inside granular amoebocytes and morula cells, thus confirming the close relationship between the two cell types, as suggested by previous histochemical and histoenzymatic analysis. Immunocytochemistry in both light and electron microscopy shows that phenoloxidase is located inside the vacuoles of moru‐la cells, known to be the effectors of the rejection reaction.
-
data on four apoptosis related genes in the colonial tunicate Botryllus schlosseri
Data in Brief, 2016Co-Authors: Nicola Franchi, Lucia Manni, Filippo Schiavon, Francesca Ballin, Loriano BallarinAbstract:The data described are related to the article entitled “Recurrent phagocytosis-induced apoptosis in the cyclical generation change of the compound ascidian Botryllus schlosseri” (Franchi et al., 2016) [1]. Four apoptosis-related genes, showing high similarity with mammalian Bax (a member of the Bcl-2 protein family), AIF1 (apoptosis-inducing factor-1), PARP1 (poly ADP ribose polymerase-1) and IAP7 (inhibitor of apoptosis-7) were identified from the analysis of the trascriptome of B. schlosseri. They were named BsBax, BsAIF1, BsPARP1 and BsIAP7. Here, their deduced amino acid sequence were compared with known sequences of orthologous genes from other deuterostome species together with a study of their identity/similarity.
-
looking for putative phenoloxidases of compound ascidians haemocyanin like proteins in polyandrocarpa misakiensis and Botryllus schlosseri
Developmental and Comparative Immunology, 2012Co-Authors: Loriano Ballarin, Filippo Schiavon, Nicola Franchi, Silvio C E Tosatto, Ivan Micetic, Kazuo KawamuraAbstract:Phenoloxidases (POs) and haemocyanins constitute a family of copper-containing proteins widely distributed among invertebrates. Both of them are able, under appropriate conditions, to convert polyphenols to quinones and induce cytotoxicity through the production of reactive oxygen species, a fundamental event in many immune responses. In ascidians, PO activity has been described and studied in both solitary and colonial species and the enzyme is involved in inflammatory and cytotoxic reactions against foreign cells or molecules, and in the formation of the cytotoxic foci which characterise the nonfusion reaction of botryllids. Expressed genes for two putative POs (CiPO1 and CiPO2) have been recently identified in C. intestinalis. In the present study, we determined the cDNA sequences of two haemocyanin-like proteins from two colonial ascidians: Botryllus schlosseri from the Mediterranean Sea and Polyandrocarpa misakiensis from Japan. Multiple sequence alignments evidenced the similarity between the above sequences and crustacean proPOs whereas the analysis of the three-dimensional structure reveals high similarity with arthropod haemocyanins which share common precursors with arthropod proPOs. Botryllus HLP grouped in the same cluster with Ciona POs, whereas Polyandrocarpa HLP clustered with arthropod haemocyanins; all of them share the full conservation of the six histidines at the two copper-binding sites as well as of other motifs, also found in arthropod haemocyanin subunits, involved in the regulation of enzyme activity. In situ hybridisation indicated that the genes are transcribed inside morula cells, a characteristic haemocyte type in ascidians where PO activity is located, at the beginning of their differentiation. These results represent a first attempt to identify candidate molecules responsible of the PO activity in compound ascidians.
-
hovering between death and life natural apoptosis and phagocytes in the blastogenetic cycle of the colonial ascidian Botryllus schlosseri
Developmental and Comparative Immunology, 2010Co-Authors: Francesca Cima, Lucia Manni, Giuseppe Basso, Elena Fortunato, Benedetta Accordi, Filippo Schiavon, Loriano BallarinAbstract:Colonies of the compound ascidian Botryllus schlosseri undergo recurrent generation changes during which massive, natural apoptosis occurs in zooid tissues: for this reason the species is emerging as an interesting model of invertebrate chordate, phylogenetically related to vertebrates, for studies of apoptosis during development. In the present work, we carried out a series of morphological, cytofluorimetrical and biochemical analyses, useful for a better characterization of Botryllus apoptosis. Results are consistent with the following viewpoints: (i) both intrinsic and extrinsic pathways, probably connected by the BH3-only protein Bid, are involved in cell death induction; (ii) phagocytes, once loaded with senescent cells, frequently undergo apoptosis, probably as a consequence of oxidative stress caused by prolonged respiratory burst, and (iii) senescent phagocytes are easily recognized and ingested by other phagocytes, responsible for their clearance. In addition, results suggest the conservation of apoptosis induction mechanisms throughout chordate evolution.
-
immunomodulatory molecules in the compound ascidian Botryllus schlosseri evidence from conditioned media
Journal of Invertebrate Pathology, 2008Co-Authors: A Menin, Loriano BallarinAbstract:The supernatant from cultures of haemocytes of the compound ascidian Botryllus schlosseri incubated with zymosan (conditioned medium; CM) can enhance yeast phagocytosis by Botryllus blood cells. It contains molecules recognised by antibodies raised against the mammalian pro-inflammatory cytokines IL1-a and TNF-a which appear as a single band of 60 kDa in immunoblot analysis. The effects on phagocytosis are abolished by the presence of sugars, such as galactose and rhamnose, sharing the same hydroxyl group configuration at C2 and C4. The same sugars also inhibit the haemagglutinating activity of the CM, suggesting the presence of lectins with opsonic activity. With immunoblot analysis, we confirmed the presence, in CM, of B. schlosseri rhamnose-binding lectins (BsRBLs), recently identified and characterised by our team, as a single electrophoretic band of 37 kDa. We had already demonstrated that these molecules are synthesised and secreted by activated phagocytes. Since previous studies have demonstrated that cytotoxic morula cells, and not phagocytes, are the haemocytes responsible for the release of molecules recognised by anti-cytokine antibodies, we propose a new scenario in which morula cells act as sentinels, able to sense foreign molecules and release immunomodulatory factors which induce phagocytes to secrete lectins able to enhance phagocytosis by acting as bridges between foreign particles and phagocyte surfaces.
Irving L Weissman - One of the best experts on this subject based on the ideXlab platform.
-
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.
-
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.
-
fester a candidate allorecognition receptor from a primitive chordate
Immunity, 2006Co-Authors: Spencer V Nyholm, Ayelet Voskoboynik, Irving L Weissman, Emmanuelle Passegue, William B Ludington, Katrina Mitchel, Anthony W De TomasoAbstract:Summary Histocompatibility in the primitive chordate, Botryllus schlosseri , is controlled by a single, highly polymorphic locus, the FuHC . By taking a forward genetic approach, we have identified a locus encoded near the FuHC , called fester , which is polymorphic, polygenic, and inherited in distinct haplotypes. Somatic diversification occurs through extensive alternative splicing, with each individual expressing a unique repertoire of splice forms, both membrane bound and potentially secreted, all expressed in tissues intimately associated with histocompatibility. Functional studies, via both siRNA-mediated knockdown and direct blocking by monoclonal antibodies raised against fester , were able to disrupt predicted histocompatibility outcomes. The genetic and somatic diversity, coupled to the expression and functional data, suggests that fester is a receptor involved in histocompatibility.
-
identification of a novel gene involved in asexual organogenesis in the budding ascidian Botryllus schlosseri
Developmental Dynamics, 2005Co-Authors: Diana J Laird, Irving L Weissman, Wenteh Chang, Robert J LauzonAbstract:Development via regeneration or budding shares some known genetic pathways with embryogenesis, but no concerted effort has been made to identify genes unique to asexual development. We have identified a novel gene that plays a role in cyclical bud formation and asexual organogenesis in the colonial ascidian Botryllus schlosseri. Athena mRNA is transcribed at high levels during the 24- to 36-hr interval of programmed cell death and new bud initiation at the conclusion of the budding cycle (takeover). Knockdown of Athena by RNAi and antisense morpholinos induced defects in the development of new buds ranging from retardation in growth and abnormal organogenesis to hollow buds lacking organs. As genetic intervention in this organism has not been possible, this study establishes the use of RNAi and morpholinos in Botryllus as well as describing the knockdown phenotype of a new gene. Developmental Dynamics 234:997–1005, 2005. © 2005 Wiley-Liss, Inc.
-
telomerase maintained in self renewing tissues during serial regeneration of the urochordate Botryllus schlosseri
Developmental Biology, 2004Co-Authors: Diana J Laird, Irving L WeissmanAbstract:Telomerase is critical for the protection of germ line and stem cell chromosomes from fatal shortening during replication. In most organisms, telomerase activity is suppressed in progressively committed cells and falls to basal rates in terminally differentiated lineages. The colonial ascidian Botryllus schlosseri propagates asexually and sexually, presumably from pools of stem cells that self-renew throughout the 2- to 5-year colony life span. Asexual budding takes place continuously from the parental body wall. When the colony reaches a critical size, sexual reproduction commences with the generation of gonads. Here, we establish the existence of 6–15 kb telomeres on the ends of Botryllus chromosomes. We develop a real-time quantitative PCR telomeric repeat amplification protocol (TRAP) assay that reliably detects 0.2–100 TPG units in cells and tissues. We find highest levels of enzymatic activity in the gonads, developing embryos, and tissues containing the earliest asexual buds. Telomerase activity appears to be suppressed in later buds during organogenesis and falls to basal rates in mature zooids. We postulate that this pattern reflects maximum telomere restoration in somatic stem cells of early buds and suppression of telomerase activity in progenitors and terminally differentiated cells, indicative of an alternate role for stem cells as repeated body regenerators in colonial life histories.
Adam D. Langenbacher - One of the best experts on this subject based on the ideXlab platform.
-
Temporally and spatially dynamic germ cell niches in Botryllus schlosseri revealed by expression of a TGF-beta family ligand and vasa
EvoDevo, 2016Co-Authors: Adam D. Langenbacher, Anthony W De TomasoAbstract:Background Germ cells are specified during early development and are responsible for generating gametes in the adult. After germ cells are specified, they typically migrate to a particular niche in the organism where they reside for the remainder of its lifetime. For some model organisms, the specification and migration of germ cells have been extensively studied, but how these events occur in animals that reproduce both sexually and asexually is not well understood. Results We have identified a novel TGF-β family member in Botryllus schlosseri , tgfβ - f , and found that it is expressed by follicle cell progenitors and the differentiated follicle and support cells surrounding the maturing gametes. Using the expression of tgfβ - f and the germ cell marker vasa , we have found that nearly all germ cells in Botryllus are associated with tgfβ - f -expressing follicle progenitors in clusters consisting solely of those two cell types. These clusters were mostly small, consisting of ten or fewer cells, and generally contained between a 2:1 and 1:1 ratio of follicle progenitors to germ cells. Clusters of germ and follicle progenitor cells were primarily localized to niches in the primary and secondary buds, but could also be found in other locations including the vasculature. We analyzed the location of germ cell clusters throughout the asexual life cycle of Botryllus and found that at the stage when germ cells are first detected in the secondary bud niche, a dramatic change in the size and location of germ/follicle cell clusters also occurred. Conclusions Our findings suggest that germ/follicle cell clusters have predictable migratory patterns during the weekly asexual developmental cycle in Botryllus . An increased number of small clusters and the presence of clusters in the vasculature coinciding with the appearance of clusters in the secondary bud suggest that fragmentation of clusters and the migration of smaller clusters through the vasculature may be an important aspect of Botryllus reproductive biology, ensuring the transmission of the germline to subsequent asexual generations.
-
temporally and spatially dynamic germ cell niches in Botryllus schlosseri revealed by expression of a tgf beta family ligand and vasa
Evodevo, 2016Co-Authors: Adam D. Langenbacher, Anthony W De TomasoAbstract:Germ cells are specified during early development and are responsible for generating gametes in the adult. After germ cells are specified, they typically migrate to a particular niche in the organism where they reside for the remainder of its lifetime. For some model organisms, the specification and migration of germ cells have been extensively studied, but how these events occur in animals that reproduce both sexually and asexually is not well understood. We have identified a novel TGF-β family member in Botryllus schlosseri, tgfβ-f, and found that it is expressed by follicle cell progenitors and the differentiated follicle and support cells surrounding the maturing gametes. Using the expression of tgfβ-f and the germ cell marker vasa, we have found that nearly all germ cells in Botryllus are associated with tgfβ-f-expressing follicle progenitors in clusters consisting solely of those two cell types. These clusters were mostly small, consisting of ten or fewer cells, and generally contained between a 2:1 and 1:1 ratio of follicle progenitors to germ cells. Clusters of germ and follicle progenitor cells were primarily localized to niches in the primary and secondary buds, but could also be found in other locations including the vasculature. We analyzed the location of germ cell clusters throughout the asexual life cycle of Botryllus and found that at the stage when germ cells are first detected in the secondary bud niche, a dramatic change in the size and location of germ/follicle cell clusters also occurred. Our findings suggest that germ/follicle cell clusters have predictable migratory patterns during the weekly asexual developmental cycle in Botryllus. An increased number of small clusters and the presence of clusters in the vasculature coinciding with the appearance of clusters in the secondary bud suggest that fragmentation of clusters and the migration of smaller clusters through the vasculature may be an important aspect of Botryllus reproductive biology, ensuring the transmission of the germline to subsequent asexual generations.
-
Molecular evolution and in vitro characterization of Botryllus histocompatibility factor
Immunogenetics, 2015Co-Authors: Daryl A Taketa, Marie L. Nydam, Adam D. Langenbacher, Delany Rodriguez, Erin Sanders, Anthony W De TomasoAbstract:Botryllus schlosseri is a colonial ascidian with a natural ability to anastomose with another colony to form a vascular and hematopoietic chimera. In order to fuse, two individuals must share at least one allele at the highly polymorphic fuhc locus. Otherwise, a blood-based inflammatory response will occur resulting in a melanin scar at the sites of interaction. The single-locus genetic control of allorecognition makes B. schlosseri an attractive model to study the underlying molecular mechanisms. Over the past decade, several candidate genes involved in allorecognition have been identified, but how they ultimately contribute to allorecognition outcome remains poorly understood. Here, we report our initial molecular characterization of a recently identified candidate allodeterminant called Botryllus histocompatibility factor ( bhf ). bhf , both on a DNA and protein level, is the least polymorphic protein in the fuhc locus studied so far and, unlike other known allorecognition determinants, does not appear to be under any form of balancing or directional selection. Additionally, we identified a second isoform through mRNA-Seq and an EST assembly library which is missing exon 3, resulting in a C-terminally truncated form. We report via whole-mount fluorescent in situ hybridization that a subset of cells co-express bhf and cfuhc ^ sec . Finally, we observed BHF’s localization in HEK293T at the cytoplasmic side of the plasma membrane in addition to the nucleus via a nuclear localization signal. Given the localization data thus far, we hypothesize that BHF may function as a scaffolding protein in a complex with other Botryllus proteins, rather than functioning as an allorecognition determinant.
-
aging in the colonial chordate Botryllus schlosseri
Invertebrate Reproduction & Development, 2015Co-Authors: Roma Munday, Daryl A Taketa, Adam D. Langenbacher, Delany Rodriguez, Alessandro Di Maio, Susannah H Kassmer, Brian P Braden, Anthony W De TomasoAbstract:What mechanisms underlie aging? One theory, the wear-and-tear model, attributes aging to progressive deterioration in the molecular and cellular machinery which eventually lead to death through the disruption of physiological homeostasis. The second suggests that life span is genetically programmed, and aging may be derived from intrinsic processes which enforce a non-random, terminal time interval for the survivability of the organism. We are studying an organism that demonstrates both properties: the colonial ascidian, Botryllus schlosseri. Botryllus is a member of the Tunicata, the sister group to the vertebrates, and has a number of life history traits which make it an excellent model for studies on aging. First, Botryllus has a colonial life history, and grows by a process of asexual reproduction during which entire bodies, including all somatic and germline lineages, regenerate every week, resulting in a colony of genetically identical individuals. Second, previous studies of lifespan in genetically...
-
analysis of the basal chordate Botryllus schlosseri reveals a set of genes associated with fertility
BMC Genomics, 2014Co-Authors: Delany Rodriguez, Daryl A Taketa, Adam D. Langenbacher, Erin Sanders, Kelsea Farell, Michelle Rae Hopper, Morgan Kennedy, Andrew Y Gracey, Anthony W De TomasoAbstract:Background Gonad differentiation is an essential function for all sexually reproducing species, and many aspects of these developmental processes are highly conserved among the metazoa. The colonial ascidian, Botryllus schlosseri is a chordate model organism which offers two unique traits that can be utilized to characterize the genes underlying germline development: a colonial life history and variable fertility. These properties allow individual genotypes to be isolated at different stages of fertility and gene expression can be characterized comprehensively.
