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Jean-françois Verbist - One of the best experts on this subject based on the ideXlab platform.
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Dichlorolissoclimide from Lissoclinum voeltzkowi Michaelson (Urochordata): Crystal Structure and Absolute Stereochemistry
Journal of Natural Products, 1996Co-Authors: Loïc Toupet, J.f. Biard, Jean-françois VerbistAbstract:The structures of the cytotoxic lissoclimides isolated from the New Caledonian ascidian Lissoclinum voeltzkowi Michaelson were originally determined on the basis of spectroscopic methods. X-ray analysis has now been performed to determine definitively the absolute stereochemistry of dichlorolissoclimide, and as a result the original assignment of one hydroxyl group must be inverted.
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Bistramides A, B, C, D, and K: a new class of bioactive cyclic polyethers from Lissoclinum bistratum.
Journal of natural products, 1994Co-Authors: Jean-françois Biard, C. Roussakis, Jean-françois Verbist, Jean-michel Kornprobst, Danielle Gouiffes-barbin, Philippe Cotelle, Mark P. Foster, Chris M. Ireland, Cécile DebitusAbstract:The isolation and characterization is described of four novel cyclic polyethers, bistramides B [2], C [3], D [4], and K [5], which are closely related to the previously reported bistramide A [1] from the New Caledonian Urochordata Lissoclinum bistratum. The structures of these metabolites were defined by spectroscopic methods. The four compounds exhibited in vitro cytotoxicity toward six tumor cell lines, including the human non-small cell lung carcinoma (NSCLC-N6) line. Cytofluorimetric analysis with bistramide K showed a complete block of NSCLC-N6 cells in the G1 phase. Bistramide D and particularly bistramide K are less toxic than bistramides A, B, and C and are thereby effective in vivo against NSCLC-N6.
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Bistramide A-induced irreversible arrest of cell proliferation in a non-small-cell bronchopulmonary carcinoma is similar to induction of terminal maturation.
Biology of the cell, 1993Co-Authors: Denis Riou, Jean-françois Biard, Christos Roussakis, Nelly Robillard, Jean-françois VerbistAbstract:Summary Bistramide A, a new toxin isolated from a New Caledonian Urochordata, shows an antiproliferative effect on a non-small-cell lung carcinoma line in vitro and G1-blockade. In this work, the growth arrest induced by bistramide A was shown to be irreversible as assessed by growth kinetics of pretreated cells. Furthermore, the drug caused an underexpression of the nuclear antigen Ki67. These events are similar to a G1-differentiation cell cycle step blockage and a terminal maturation induction.
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Effects in vitro of two marine substances, chlorolissoclimide and dichlorolissoclimide, on a non-small-cell bronchopulmonary carcinoma line (NSCLC-N6).
Anti-cancer drug design, 1992Co-Authors: C. Malochet-grivois, N. Robillard, D Riou, Cécile Debitus, Christos Roussakis, Jean-françois Biard, Jean-françois VerbistAbstract:The antiproliferative activity of two nitrogenous labdane cytotoxic substances from Lissoclinum voeltzkowi Michaelson (Urochordata), dichlorolissoclimide (P2) and chlorolissoclimide (P1), was studied in vitro on a continuous human non-small-cell bronchopulmonary carcinoma line (NSCLC-N6) at the cell cycle level. This antiproliferative effect resulted from a blockade of G1 phase cells. Mortality occurred, regardless of the degree of cell ploidy, with cell transition to an out-of-cycle situation characteristic of a G1D terminal maturation state.
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Effects of bistramide A on a non-small-cell bronchial carcinoma line.
Cancer chemotherapy and pharmacology, 1991Co-Authors: C. Roussakis, N. Robillard, D Riou, J.f. Biard, G. Pradal, P. Piloquet, Cécile Debitus, Jean-françois VerbistAbstract:The antiproliferative effects of bistramide A, a nitrogenous dilactam polyether fromLissoclinum bistratum Sluiter (Urochordata), were studied at the level of the cell cycle in asynchronous cells of the NSCLCN6-L16 line. Bistramide A has a dual mechanism that induces blockade in the G1 phase (compatible with differentiation properties reported elsewhere) and causes polyploidy that is suggestive of inaptitude for cytokinesis. These effects confirm the results of cytomorphology studies in electron microscopy.
G. Salvatore - One of the best experts on this subject based on the ideXlab platform.
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Thyroid hormone biosynthesis in agnatha and protochordata
General and Comparative Endocrinology, 2004Co-Authors: G. SalvatoreAbstract:Abstract In the present review the problem of the evolutionary level at which the biosynthesis of thyroid hormones first appeared in the zoological scale is discussed. Thyroid hormones are certainly present in all Chordata, Urochordata, Cephalocordata, and Vertebrata. However, although concentration and organification of iodine are widespread processes occurring throughout the animal kingdom, the synthesis of thyroid hormones, i.e., iodothyronines, has not been clearly established below the Chordata. The biochemical mechanism leading to hormone synthesis follows the same general pattern from its first appearance in the Protochordata. The coupling of iodotyrosines to yield iodothyronines occurs within the polypeptide chains of specific proteins. In vertebrates, from the cyclostomes up to the mammals, the polymerization of similar, but perhaps not identical, subunits, leads to the formation of a family of thyroid proteins of increasing molecular size, i.e., 12 S, 19 S (thyroglobulin), and 27 S iodoproteins.
John H. Postlethwait - One of the best experts on this subject based on the ideXlab platform.
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Development of the central nervous system in the larvacean Oikopleura dioica and the evolution of the chordate brain.
Developmental biology, 2005Co-Authors: Cristian Cañestro, Susan Bassham, John H. PostlethwaitAbstract:Abstract In non-vertebrate chordates, central nervous system (CNS) development has been studied in only two taxa, the Cephalochordata and a single Class (Ascidiacea) of the morphologically diverse Urochordata. To understand development and molecular regionalization of the brain in a different deeply diverging chordate clade, we isolated and determined the expression patterns of orthologs of vertebrate CNS markers ( otxa , otxb , otxc , pax6 , pax2/5/8a , pax2/5/8b , engrailed , and hox1 ) in Oikopleura dioica (Subphylum Urochordata, Class Larvacea). The three Oikopleura otx genes are expressed similarly to vertebrate Otx paralogs, demonstrating that trans-homologs converged on similar evolutionary outcomes by independent neo- or subfunctionalization processes during the evolution of the two taxa. This work revealed that the Oikopleura CNS possesses homologs of the vertebrate forebrain, hindbrain, and spinal cord, but not the midbrain. Comparing larvacean gene expression patterns to published results in ascidians disclosed important developmental differences and similarities that suggest mechanisms of development likely present in their last common ancestor. In contrast to ascidians, the lack of a radical reorganization of the CNS as larvaceans become adults allows us to relate embryonic gene expression patterns to three subdivisions of the adult anterior brain. Our study of the Oikopleura brain provides new insights into chordate CNS evolution: first, the absence of midbrain is a urochordate synapomorphy and not a peculiarity of ascidians, perhaps resulting from their drastic CNS metamorphosis; second, there is no convincing evidence for a homolog of a midbrain–hindbrain boundary (MHB) organizer in urochordates; and third, the expression pattern of “MHB-genes” in the urochordate hindbrain suggests that they function in the development of specific neurons rather than in an MHB organizer.
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Brachyury (T) expression in embryos of a larvacean urochordate, Oikopleura dioica, and the ancestral role of T.
Developmental Biology, 2000Co-Authors: Susan Bassham, John H. PostlethwaitAbstract:The Brachyury, or T, gene is required for notochord development in animals occupying all three chordate subphyla and probably also had this role in the last common ancestor of the chordate lineages. In two chordate subphyla (vertebrates and cephalochordates), T is also expressed during gastrulation in involuting endodermal and mesodermal cells, and in vertebrates at least, this expression domain is required for proper development. In the basally diverging chordate subphylum Urochordata, animals in the class Ascidiacea do not employ T during gastrulation in endodermal or nonaxial mesodermal cells, and it has been suggested that nonnotochordal roles for T were acquired in the cephalochordate–vertebrate lineage after it split with Urochordata. To test this hypothesis, we cloned T from Oikopleura dioica, a member of the urochordate class Appendicularia (or Larvacea), which diverged basally in the subphylum. Investigation of the expression pattern in developing Oikopleura embryos showed early expression in presumptive notochord precursor cells, in the notochord, and in parts of the developing gut and cells of the endodermal strand. We conclude that the ancestral role of T likely included expression in the developing gut and became necessary in chordates for construction of the notochord.
Cécile Debitus - One of the best experts on this subject based on the ideXlab platform.
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Bistramides A, B, C, D, and K: a new class of bioactive cyclic polyethers from Lissoclinum bistratum.
Journal of natural products, 1994Co-Authors: Jean-françois Biard, C. Roussakis, Jean-françois Verbist, Jean-michel Kornprobst, Danielle Gouiffes-barbin, Philippe Cotelle, Mark P. Foster, Chris M. Ireland, Cécile DebitusAbstract:The isolation and characterization is described of four novel cyclic polyethers, bistramides B [2], C [3], D [4], and K [5], which are closely related to the previously reported bistramide A [1] from the New Caledonian Urochordata Lissoclinum bistratum. The structures of these metabolites were defined by spectroscopic methods. The four compounds exhibited in vitro cytotoxicity toward six tumor cell lines, including the human non-small cell lung carcinoma (NSCLC-N6) line. Cytofluorimetric analysis with bistramide K showed a complete block of NSCLC-N6 cells in the G1 phase. Bistramide D and particularly bistramide K are less toxic than bistramides A, B, and C and are thereby effective in vivo against NSCLC-N6.
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Effects in vitro of two marine substances, chlorolissoclimide and dichlorolissoclimide, on a non-small-cell bronchopulmonary carcinoma line (NSCLC-N6).
Anti-cancer drug design, 1992Co-Authors: C. Malochet-grivois, N. Robillard, D Riou, Cécile Debitus, Christos Roussakis, Jean-françois Biard, Jean-françois VerbistAbstract:The antiproliferative activity of two nitrogenous labdane cytotoxic substances from Lissoclinum voeltzkowi Michaelson (Urochordata), dichlorolissoclimide (P2) and chlorolissoclimide (P1), was studied in vitro on a continuous human non-small-cell bronchopulmonary carcinoma line (NSCLC-N6) at the cell cycle level. This antiproliferative effect resulted from a blockade of G1 phase cells. Mortality occurred, regardless of the degree of cell ploidy, with cell transition to an out-of-cycle situation characteristic of a G1D terminal maturation state.
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Effects of bistramide A on a non-small-cell bronchial carcinoma line.
Cancer chemotherapy and pharmacology, 1991Co-Authors: C. Roussakis, N. Robillard, D Riou, J.f. Biard, G. Pradal, P. Piloquet, Cécile Debitus, Jean-françois VerbistAbstract:The antiproliferative effects of bistramide A, a nitrogenous dilactam polyether fromLissoclinum bistratum Sluiter (Urochordata), were studied at the level of the cell cycle in asynchronous cells of the NSCLCN6-L16 line. Bistramide A has a dual mechanism that induces blockade in the G1 phase (compatible with differentiation properties reported elsewhere) and causes polyploidy that is suggestive of inaptitude for cytokinesis. These effects confirm the results of cytomorphology studies in electron microscopy.
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Dichlorolissoclimide, a new cytotoxic labdane derivative from Lissoclinum voeltzkowi Michaelson (Urochordata)
Tetrahedron Letters, 1991Co-Authors: C. Malochet-grivois, C. Roussakis, Jean-pierre Hénichart, J.f. Biard, Cécile Debitus, Philippe Cotelle, Jean-françois VerbistAbstract:Spectral methods were used to determine the siruciure o/ a new cytotoxic compound, dichlorolissoclimide I, isolatedfrom the New Caledonia ascidian Lissoclinum voeltzkowi Michaelson. It is known that ascidians usually contain original nitrogenous compounds192. We isolated a new nitrogenous labdane cytotoxic substance, dichlorolissoclimide 1 (0.004%), from the EtOH extract of Lissoclinum voeltzkowi Michaelson (Urochordata, Didemnidae) gathered in 1988 on Platier du Mont Dore, New Caledonia. Isolation was performed by 1iquidAiquid purification and HPLC and monitored by cytotoxic bioassay using SESAME mathematical analysis3. The molecular formula of compound 1, C20H2gC12N04, = -20, was determined by analysis of its spectral mass and NMR data(Tab1e 1). The 13C spectra revealed 20 carbons attached to a total of 26 hydrogen atoms. The highest FAB mass peaks at m/z 418,420 and 422 (C~OH~OCI~NO~+) were thus attributed to the (M H+) ion. FAI3 mass spectra revealed other peaks at m/z 400, 402 and 404 (C~OH~~CI~NO~+) attributable to (M H+-H2O) fragmentation. The highest mass peak at m/z 399.1367 (C20H27N0335C12) in the EIHRMS confirmed the loss of a molecule of H20 (The 400/402/404 (loo%, 87%, 37%) ratio is consistent with two chlorine atoms). The deshielded 13C NMR resonances of s 184.8 (C) and 182.6 (C) indicated the presence of
Atsuo Nishino - One of the best experts on this subject based on the ideXlab platform.
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Is there intracellular cellulose in the appendicularian tail epidermis? A tale of the adult tail of an invertebrate chordate.
Communicative & integrative biology, 2011Co-Authors: Euichi Hirose, Keisuke Nakashima, Atsuo NishinoAbstract:All tunicates produce a cellulosic extracellular matrix external to the epidermis; this is the most remarkable character of the subphylum (Tunicata = Urochordata). In Ascidiacea and Thaliacea, two of the three classes of Tunicata, cellulose is the main component of the tunic matrix that covers the whole body. In Appendicularia, however, the animals do not possess a tunic, and instead secrete a feeding apparatus called a "house" that is composed of cellulose. In the appendicularian Oikopleura dioica, we found a unique intracellular matrix in the apical cytoplasm of the adult tail epidermis that appears to form a tough shell supporting the tail. Although some experimental data suggest that this matrix may contain cellulose, the composition is still unknown. The significance of the tunicate capacity for cellulose synthesis is briefly discussed.
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Rapid Oocyte Growth and Artificial Fertilization of the Larvaceans Oikopleura dioica and Oikopleura longicauda
Zoological Science, 1998Co-Authors: Atsuo Nishino, Masaaki MorisawaAbstract:Abstract We describe here rapid gamete growth and artificial fertilization method of species of the larvaceans (appendicularians), Oikopleura dioica and O. longicauda (Family Oikopleuridae: Class Appendicularia: Subphylum Urochordata). In these species, oocytes grew very rapidly from about 40 μm in diameter to about 75 μm (O. dioica) and 110 μm (O. longicauda), respectively within a few hr. Moreover, cutting off the gonads at the last phase of the growth stage yielded matured gametes. The eggs and sperm obtained by the dissection of gonads could be fertilized when they were mixed together.
