Constituents of Holothuroidea, 15. Isolation of ante-iso type regio-isomer on long chain base moiety of glucocerebroside from the sea cucumber Holothuria leucospilota.
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An ante-iso type regio-isomer on the long chain base moiety of a glucocerebroside, HLC-2-A, has been isolated from its parent glucocerebroside molecular species HLC-2 composed of iso and ante-iso isomers, from the less polar lipid fraction of a chloroform/methanol extract of the sea cucumber Holothuria leucospilota. Reverse-phase HPLC that included a recycling system was effective in separating the regio-isomer from its counterpart, revealing a very close resemblance in structure. Other typical glucocerebroside molecular species HLC-1 and HLC-3 were obtained together with HLC-2. The structures of these glucocerebrosides were determined on the basis of chemical and spectroscopic evidence. (+info)
Constituents of holothuroidea, 16. Determination of Absolute configuration of the branched methyl group in ante-iso type side chain moiety on long chain base of glucocerebroside from the sea cucumber Holothuria leucospilota.
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The absolute configuration of the branched methyl group in ante-iso type side chain moiety on the long chain base of glucocerebroside, HLC-2-A, which was isolated from the sea cucumber Holothuria leucospilota was determined. Oxidation of the glucocerebroside with ozone afforded C13-fragment including the ante-iso moiety. The optically active C13-fragment was synthesized asymmetrically by using the Wittig reaction from chiral synton for comparison with the natural fragment. (+info)
Transdifferentiation in holothurian gut regeneration.
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It has recently been shown that the whole spectrum of cell types constituting a multicellular organism can be generated from stem cells. Our study provides an example of an alternative mechanism of tissue repair. Injection of distilled water into the coelomic cavity of the holothurian Eupentacta fraudatrix results in the loss of the whole digestive tract, except the cloaca. The new gut reforms from two separate rudiments. One rudiment appears at the anterior end of the body and extends posteriorly. The second rudiment grows anteriorly from the cloaca. In the anterior rudiment, the luminal epithelium (normally derived from endoderm) develops de novo through direct transdifferentiation of the coelomic epithelial cells (mesodermal in origin). In the posterior rudiment, the luminal epithelium originates from the lining epithelium of the cloaca. After 27 days, the two rudiments come into contact and fuse to form a continuous digestive tube lined with a fully differentiated luminal epithelium. Thus in this species, the luminal epithelia of the anterior and posterior gut rudiments develop from two different cell sources-i.e., from the mesodermally derived mesothelium and the endodermally derived epithelium of the cloacal lining, respectively. Our data suggest that differentiated cells of echinoderms are capable of transdifferentiation into other cell types. (+info)
Tensilin-like stiffening protein from Holothuria leucospilota does not induce the stiffest state of catch connective tissue.
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The dermis of sea cucumbers is a catch connective tissue or mutable connective tissue that exhibits large changes in mechanical properties. A stiffening protein, tensilin, has been isolated from the sea cucumber Cucumaria frondosa. We purified a similar protein, H-tensilin, from Holothuria leucospilota, which belongs to a different family to C. frondosa. H-tensilin appeared as a single band with an apparent molecular mass of 34 kDa on SDS-PAGE. No sugar chain was detected. Tryptic fragments of the protein had homology to known tensilin. H-tensilin aggregated isolated collagen fibrils in vitro in a buffer containing 0.5 mol l(-1) NaCl with or without 10 mmol l(-1) Ca(2+). The activity of H-tensilin was quantitatively studied by dynamic mechanical tests on the isolated dermis. H-tensilin increased stiffness of the dermis in the soft state, induced by Ca(2+)-free artificial seawater, to a level comparable to that of the standard state, which was the state found in the dermis rested in artificial seawater with normal ionic condition. H-tensilin decreased the energy dissipation ratio of the soft dermis to a level comparable to that of the standard state. When H-tensilin was applied on the dermis in the standard state, it did not alter stiffness nor dissipation ratio. The subsequent application of artificial seawater in which the potassium concentration was raised to 100 mmol l(-1) increased stiffness by one order of magnitude. These findings suggest that H-tensilin is involved in the changes from the soft state to the standard state and that some stiffening factors other than tensilin are necessary for the changes from the standard to the stiff state. (+info)
Constituents of Holothuroidea, 17. Isolation and structure of biologically active monosialo-gangliosides from the sea cucumber Cucumaria echinata.
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Three new monosialo-gangliosides, CEG-3 (3), CEG-4 (4), and CEG-5 (5), were obtained, together with two known gangliosides, SJG-1 (1) and CG-1 (2), from the lipid fraction of the chloroform/methanol extract of the sea cucumber Cucumaria echinata. The structures of the new gangliosides were determined on the basis of chemical and spectroscopic evidence to be 1-O-[4-O-acetyl-alpha-L-fucopyranosyl-(1-->11)-(N-glycolyl-alpha-D-neuraminosyl)- (2-->6)-beta-D-glucopyranosyl]-ceramide (3) and 1-O-[alpha-L-fucopyranosyl-(1-->11)-(N-glycolyl-alpha-D-neuraminosyl)-(2-->6)-bet a-D-glucopyranosyl]-ceramide (4, 5). The ceramide moieties of each compound were composed of heterogeneous sphingosine or phytosphingosine bases, and 2-hydroxy or nonhydroxylated fatty acid units. These gangliosides showed neuritogenic activity toward the rat pheochromocytoma cell line PC-12 in the presence of nerve growth factor. (+info)
Constituents of Holothuroidea, 18. Isolation and structure of biologically active disialo- and trisialo-gangliosides from the sea cucumber Cucumaria echinata.
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Three new disialo- and trisialo-gangliosides, CEG-6 (6), CEG-8 (8), and CEG-9 (9), were obtained, together with one known ganglioside, HLG-3 (7), from the lipid fraction of the chloroform/methanol extract of the sea cucumber Cucumaria echinata. The structures of the new gangliosides were determined on the basis of chemical and spectroscopic evidence to be 1-O-[alpha-L-fucopyranosyl-(1-->11)-(N-glycolyl-alpha-D-neuraminosyl)-(2-->4)-(N- acetyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (6) and 1-O-[(N-glycolyl-D-neuraminosyl)-(2-->11)-(N-glycolyl-D-neuraminosyl)-(2-->4)-(N- acetyl-D-neuraminosyl)-(2-->6)-D-glucopyranosyl]-ceramide (8, 9). The ceramide moieties of each compound were composed of an homogeneous sphingosine or phytosphingosine base and heterogeneous 2-hydroxy or nonhydroxylated fatty acid units. These gangliosides showed neuritogenic activity toward the rat pheochromocytoma cell line PC-12 in the presence of nerve growth factor. (+info)
Spherulocytes in the echinoderm Holothuria glaberrima and their involvement in intestinal regeneration.
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The holothuroid echinoderm Holothuria glaberrima can regenerate its intestine after a process of evisceration. Spherule-containing cells, the spherulocytes, appear to be associated with intestinal regeneration. We have used histochemistry and immunocytochemistry to characterize these cells and their role in the regeneration process. Spherulocytes are 10-20 microm in diameter with an acrocentric nucleus and spherule-like structures within their cytoplasm. They are found in the connective tissue of the intestine and mesentery of noneviscerated and regenerating animals. During the second week of regeneration, the number of spherulocytes in the regenerating intestine increases and a dramatic change in their morphology occurs. Together with the morphological change, the immunohistochemical labeling of the cells also changes; the antibodies not only recognize the spherule structures but also label the cellular cytoplasm in a more homogeneous pattern. Moreover, immunohistochemical labeling also appears to be dispersed within the extracellular matrix, suggesting that the cells are liberating their vesicular contents. Spherulocytes are found in other tissues of H. glaberrima, always associated with the connective tissue component. Our data strongly suggest that spherulocytes are involved in intestinal regeneration but their specific role remains undetermined. In summary, our data expand our knowledge of the cellular events associated with regeneration processes in echinoderms and provide for comparisons with similar processes in vertebrates. (+info)
Distinct profiles of expressed sequence tags during intestinal regeneration in the sea cucumber Holothuria glaberrima.
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Repair and regeneration are key processes for tissue maintenance, and their disruption may lead to disease states. Little is known about the molecular mechanisms that underline the repair and regeneration of the digestive tract. The sea cucumber Holothuria glaberrima represents an excellent model to dissect and characterize the molecular events during intestinal regeneration. To study the gene expression profile, cDNA libraries were constructed from normal, 3-day, and 7-day regenerating intestines of H. glaberrima. Clones were randomly sequenced and queried against the nonredundant protein database at the National Center for Biotechnology Information. RT-PCR analyses were made of several genes to determine their expression profile during intestinal regeneration. A total of 5,173 sequences from three cDNA libraries were obtained. About 46.2, 35.6, and 26.2% of the sequences for the normal, 3-days, and 7-days cDNA libraries, respectively, shared significant similarity with known sequences in the protein database of GenBank but only present 10% of similarity among them. Analysis of the libraries in terms of functional processes, protein domains, and most common sequences suggests that a differential expression profile is taking place during the regeneration process. Further examination of the expressed sequence tag dataset revealed that 12 putative genes are differentially expressed at significant level (R > 6). Experimental validation by RT-PCR analysis reveals that at least three genes (unknown C-4677-1, melanotransferrin, and centaurin) present a differential expression during regeneration. These findings strongly suggest that the gene expression profile varies among regeneration stages and provide evidence for the existence of differential gene expression. (+info)