The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Andrew J Gillis - One of the best experts on this subject based on the ideXlab platform.
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adult chondrogenesis and spontaneous cartilage repair in the skate leucoraja Erinacea
eLife, 2020Co-Authors: Aleksandra Marconi, Andrew J Gillis, Amy HancockronemusAbstract:For our joints to move around freely, they are lubricated with cartilage. In growing mammals, this tissue is continuously made by the body. But, by adulthood, this cartilage will have been almost entirely replaced by bone. It is also difficult for adult bodies to replenish what cartilage does remain – such as that in the joints. When growing new cartilage, the body uses so-called progenitor cells, which have the ability to turn into different cell types. Progenitor cells are recruited to the joints, where they transform into cartilage cells called chondrocytes, which generate new cartilage. But adults lack these progenitor cells, leaving them unfit to heal damaged cartilage after injury or diseases like osteoarthritis. In contrast, certain groups of fishes, such as skates, sharks and rays, produce cartilage throughout their life — indeed their whole skeleton is made of cartilage. So, what is the difference between these cartilaginous fishes and mammals? Why can they generate cartilage throughout their lives, while humans are unable to? And does this mean that these adult fish are better at healing injured cartilage? Marconi et al. used skates (Leucoraja Erinacea) to study how cartilage develops, grows and heals in a cartilaginous fish. Progenitor cells were found in a layer that wraps around the cartilage skeleton (called the perichondrium). These cells were also shown to activate genes that control cartilage development. By labelling these progenitor cells, their presence and movements could be tracked around the fish. Marconi et al. found progenitor cells in adult skates that were able to generate chondrocytes. Skates were also shown to spontaneously repair damaged cartilage in experiments where cartilage was injured. Marconi et al. have identified the skate as a new animal model for studying cartilage growth and repair. Studying the mechanisms that skate progenitor cells use for generating cartilage could lead to improvements in current therapies used for repairing cartilage in the joints.
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adult chondrogenesis and spontaneous cartilage repair in the skate leucoraja Erinacea
bioRxiv, 2019Co-Authors: Aleksandra Marconi, Andrew J Gillis, Amy HancockronemusAbstract:Mammalian articular cartilage is an avascular tissue with poor capacity for spontaneous repair. Here, we show that embryonic development of cartilage in the skate (Leucoraja Erinacea) mirrors that of mammals, with developing chondrocytes co-expressing genes encoding the transcription factors Sox5, Sox6 and Sox9. However, in skate, transcriptional features of developing cartilage persist into adulthood, both in peripheral chondrocytes and in cells of the fibrous perichondrium that ensheaths the skeleton. Using pulse-chase label retention experiments and multiplexed in situ hybridization, we identify a population of cycling Sox5/6/9+ perichondral progenitor cells that generate new cartilage during adult growth, and we show that persistence of chondrogenesis in adult skates correlates with ability to spontaneously repair cartilage injuries. Skates therefore offer a unique model for adult chondrogenesis and cartilage repair and may serve as inspiration for novel cell-based therapies for skeletal pathologies, such as osteoarthritis.
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chondrogenesis and homology of the visceral skeleton in the little skate leucoraja Erinacea chondrichthyes batoidea
Journal of Morphology, 2009Co-Authors: Andrew J Gillis, Randall D Dahn, Neil H ShubinAbstract:Chondrichthyan fishes possess visceral skeletons that differ considerably, morphologically, from those of their sister taxon, the osteichthyans. Here, we use histological techniques and whole-mount skeletal preparations to visualize and describe the sequence of visceral skeletal condensation and chondrogenesis in a chondrichthyan, the little skate (Leucoraja Erinacea). We demonstrate that visceral skeletal condensation begins rostrally, with the mandibular arch, and progresses caudally with the hyoid arch and posterior branchial arches condensing soon after. We provide a detailed account of the condensation and chondrogenesis of all major components of the L. Erinacea visceral skeleton and discuss these data in the context of what is known from classical descriptions of chondrichthyan visceral skeletal development. Significant differences exist between the hypobranchial and basibranchial skeleton of L. Erinacea and other chondrichthyan species, and the possible evolutionary and developmental significance of this is considered. We discuss the homology of the chondrichthyan hyoid arch and, based on patterns of mesenchymal condensation, we propose a model of condensation splitting and diversification that may account for the morphological diversification of gnathostome branchial arch derivatives. Finally, we suggest that the unique presence of certain visceral skeletal elements in chondrichthyans make oviparous chondrichthyans an ideal system for addressing questions of endoskeletal axial patterning during development. J. Morphol., 2009. © 2008 Wiley-Liss, Inc.
Ian P. Callard - One of the best experts on this subject based on the ideXlab platform.
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effects of reproductive activity and sex hormones on apoptosis in the epigonal organ of the skate leucoraja Erinacea
General and Comparative Endocrinology, 2007Co-Authors: B V Lutton, Ian P. CallardAbstract:In elasmobranchs, a unique association exists between an immune tissue, the epigonal organ, and the gonads. The intimate morphological relationship between these tissues suggests functional interactions. In this study, we used apoptosis to assess differences between epigonal tissues of reproductively active (RA) and non-reproductively active (NRA) skates (Leucoraja Erinacea). Plasma steroid levels were significantly higher in RA than in NRA animals, and TUNEL analysis showed that epigonal tissue of RA skates had greater DNA fragmentation than NRA skates. Addition of steroids to epigonal leukocytes in vitro demonstrated that progesterone, testosterone, and dexamethasone, but not estrogen, induced apoptosis of epigonal leukocytes as evidenced by DNA laddering and caspase-3 antibody labeling. This study supports recent evidence that cellular homeostasis of epigonal lymphomyeloid tissue may be influenced by gonadal activity and reproductive steroids in a representative of the most basal gnathastome group.
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characterization of progesterone binding moieties in the little skateraja Erinacea
General and Comparative Endocrinology, 1998Co-Authors: M Paolucci, Ian P. CallardAbstract:Abstract In this study we report evidence of a [ 3 H]progesterone-binding moiety in the liver and oviduct of the little skate Raja Erinacea. It is characterized by high affinity, low capacity, and DNA-cellulose-binding activity. Furthermore Western blot analysis revealed that monoclonal antibodies against the chicken progesterone receptor (PR) subunits A and B cross-reacted with a 110-kDa band in the liver and a 80-kDa band in the oviduct. When analyzed by DEAE-Sepharose ion-exchange column chromatography, [ 3 H]progesterone-binding molecules resolved into two peaks, one nonadherent and one adherent to the column. The liver adherent peak eluted in a linear gradient at a NaCl concentration of about 0.07 M and resolved on Western blot as a single band of a 110 kDa. The oviduct adherent peak eluted at about 0.14 M NaCl and resolved on Western blot as a single band of 80 kDa. Competition studies showed that the progesterone-binding moiety in the cytosol was specific for progesterone. On the contrary, the nuclear component is not specific for progesterone; it also binds testosterone and estradiol 17β in the oviduct, and progesterone, testosterone, dihydrotestosterone, estradiol 17β, mibolerone, and R5020 in the liver. The [ 3 H]progesterone-binding activity was monitored in both liver and oviduct of females in different reproductive stages. Females were separated into three groups: laying, nonlaying, and immature. [ 3 H]Progesterone-binding activity levels were higher in the liver of immature than of nonlaying skates, and it was undetectable in laying skates. [ 3 H]Progesterone binding was higher in the oviduct of laying and nonlaying skates than of immature skates. This PR-binding moiety has many characteristics of a true receptor: high affinity, low capacity, binds to DNA, and cross-reacts with antibodies against chicken PR. However, while the cytosolic form of this progesterone-binding component was quite specific for P, nuclear extracted material was nonspecific. If these progesterone-binding components are homologous with the PR A and PR B forms of other vertebrates, as we believe, it is clear that there are species differences that probably relate to phylogenetic level and physiology of the organism.
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identification of vitellogenin in the little skate rajah Erinacea
Comparative Biochemistry and Physiology B, 1992Co-Authors: Lorelei E Perez, Ian P. CallardAbstract:Abstract 1. 1. Vitellogenin was isolated from mature female skates by selective precipitation with MgCl2/EDTA followed by chromatography on DEAE-cellulose columns. 2. 2. A single monomer of approximately 205 kDa was identified on 6.0% SDS-PAGE gels. 3. 3. In addition, isolation of yolk proteins with ammonnium sulfate yielded proteins of 94 and 38 kDa (putative phosvitins) and putative lipovitellins of ca 105, 91 and 67 kDa. 4. 4. In vivo phosphate incorporation in female and male skates implanted with estradiol indicated that vitellogenin was phosphorylated. 5. 5. Total protein phosphate incorporation was significantly higher in females than male skates. 6. 6. In male skates treated with estradiol, phosphate incorporation increased from 2 days after implantation to a maximum at approximately 11 days after implantation. 7. 7. Determination of the rate of disappearance of 32P-labeled protein suggests a half-life of ca 200 hr in normal female skate plasma.
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Regulation of Ovarian Steroidogenesis in the Little Skate (Raja Erinacea)
Signaling Mechanisms and Gene Expression in the Ovary, 1991Co-Authors: Lisa A. Fileti, Ian P. CallardAbstract:Ovarian regulation in the most primitive jawed vertebrates, the elasmobranchs, is poorly understood (1). Most recently, we have investigated the little skate, Raja Erinacea, and the spiny dogfish, Squalus acanthias, and have characterized endocrine aspects of the ovarian cycle (2, 3). These studies suggest pituitary regulation of the ovary.
James B Mcclintock - One of the best experts on this subject based on the ideXlab platform.
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structure and bioactivity of erebusinone a pigment from the antarctic sponge isodictya Erinacea
Tetrahedron, 2000Co-Authors: Byoungho Moon, James B Mcclintock, Young Chul Park, Bill J BakerAbstract:Abstract We have investigated the Antarctic sponge Isodictya Erinacea as part of our ongoing study of Antarctic chemical ecology. I. Erinacea was found to produce a tryptophan catabolite as its yellow pigment. The pigment, erebusinone, causes significantly reduced molting and proportionally increased mortality at ecologically relevant concentrations when fed to sympatric predatory amphipods. This appears to be the first example of molt inhibition as a mechanism of chemical defense.
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purine and nucleoside metabolites from the antarctic sponge isodictya Erinacea
Journal of Natural Products, 1998Co-Authors: Byoungho Moon, Bill J Baker, James B McclintockAbstract:The bright yellow sponge Isodictya Erinacea is one of several chemically defended sponges found on the benthos of McMurdo Sound, Antarctica. An investigation of the metabolites from this sponge has resulted in the isolation of purine and nucleoside metabolites, including the previously unreported Erinacean (1) and p-hydroxybenzaldehyde. The latter metabolite has been demonstrated to cause a feeding deterrence behavior in Perknaster fuscus, the major predator of antarctic sponges.
Bill J Baker - One of the best experts on this subject based on the ideXlab platform.
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structure and bioactivity of erebusinone a pigment from the antarctic sponge isodictya Erinacea
Tetrahedron, 2000Co-Authors: Byoungho Moon, James B Mcclintock, Young Chul Park, Bill J BakerAbstract:Abstract We have investigated the Antarctic sponge Isodictya Erinacea as part of our ongoing study of Antarctic chemical ecology. I. Erinacea was found to produce a tryptophan catabolite as its yellow pigment. The pigment, erebusinone, causes significantly reduced molting and proportionally increased mortality at ecologically relevant concentrations when fed to sympatric predatory amphipods. This appears to be the first example of molt inhibition as a mechanism of chemical defense.
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purine and nucleoside metabolites from the antarctic sponge isodictya Erinacea
Journal of Natural Products, 1998Co-Authors: Byoungho Moon, Bill J Baker, James B McclintockAbstract:The bright yellow sponge Isodictya Erinacea is one of several chemically defended sponges found on the benthos of McMurdo Sound, Antarctica. An investigation of the metabolites from this sponge has resulted in the isolation of purine and nucleoside metabolites, including the previously unreported Erinacean (1) and p-hydroxybenzaldehyde. The latter metabolite has been demonstrated to cause a feeding deterrence behavior in Perknaster fuscus, the major predator of antarctic sponges.
Amy Hancockronemus - One of the best experts on this subject based on the ideXlab platform.
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adult chondrogenesis and spontaneous cartilage repair in the skate leucoraja Erinacea
eLife, 2020Co-Authors: Aleksandra Marconi, Andrew J Gillis, Amy HancockronemusAbstract:For our joints to move around freely, they are lubricated with cartilage. In growing mammals, this tissue is continuously made by the body. But, by adulthood, this cartilage will have been almost entirely replaced by bone. It is also difficult for adult bodies to replenish what cartilage does remain – such as that in the joints. When growing new cartilage, the body uses so-called progenitor cells, which have the ability to turn into different cell types. Progenitor cells are recruited to the joints, where they transform into cartilage cells called chondrocytes, which generate new cartilage. But adults lack these progenitor cells, leaving them unfit to heal damaged cartilage after injury or diseases like osteoarthritis. In contrast, certain groups of fishes, such as skates, sharks and rays, produce cartilage throughout their life — indeed their whole skeleton is made of cartilage. So, what is the difference between these cartilaginous fishes and mammals? Why can they generate cartilage throughout their lives, while humans are unable to? And does this mean that these adult fish are better at healing injured cartilage? Marconi et al. used skates (Leucoraja Erinacea) to study how cartilage develops, grows and heals in a cartilaginous fish. Progenitor cells were found in a layer that wraps around the cartilage skeleton (called the perichondrium). These cells were also shown to activate genes that control cartilage development. By labelling these progenitor cells, their presence and movements could be tracked around the fish. Marconi et al. found progenitor cells in adult skates that were able to generate chondrocytes. Skates were also shown to spontaneously repair damaged cartilage in experiments where cartilage was injured. Marconi et al. have identified the skate as a new animal model for studying cartilage growth and repair. Studying the mechanisms that skate progenitor cells use for generating cartilage could lead to improvements in current therapies used for repairing cartilage in the joints.
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adult chondrogenesis and spontaneous cartilage repair in the skate leucoraja Erinacea
bioRxiv, 2019Co-Authors: Aleksandra Marconi, Andrew J Gillis, Amy HancockronemusAbstract:Mammalian articular cartilage is an avascular tissue with poor capacity for spontaneous repair. Here, we show that embryonic development of cartilage in the skate (Leucoraja Erinacea) mirrors that of mammals, with developing chondrocytes co-expressing genes encoding the transcription factors Sox5, Sox6 and Sox9. However, in skate, transcriptional features of developing cartilage persist into adulthood, both in peripheral chondrocytes and in cells of the fibrous perichondrium that ensheaths the skeleton. Using pulse-chase label retention experiments and multiplexed in situ hybridization, we identify a population of cycling Sox5/6/9+ perichondral progenitor cells that generate new cartilage during adult growth, and we show that persistence of chondrogenesis in adult skates correlates with ability to spontaneously repair cartilage injuries. Skates therefore offer a unique model for adult chondrogenesis and cartilage repair and may serve as inspiration for novel cell-based therapies for skeletal pathologies, such as osteoarthritis.