[Larval settlement in barnacles].
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Animals↗
Biomedical subjects
N Fusetani
Publications and source records attributed to N Fusetani.
Larval storage protein of the barnacle, Balanus amphitrite: biochemical and immunological similarities to vitellin.
Biochemical and immunological characterization of cyprid major protein (CMP), the principal protein constituent of cypris larvae of the barnacle Balanus amphitrite (Crustacea: Cirripedia), revealed similarities to egg-yolk protein, vitellin, as follows: CMP and vitellin heavy chain both have a molecular weight of 170 kDa by polyacrylamide gel electrophoresis containing sodium dodecylsulfate; CMP was crossreactive with antiserum against vitellin heavy chain in immunoblot analysis. The sequence of 11 amino acids in the amino-terminus of CMP, however, is not perfectly homologous to that of vitellin heavy chain. Thus, it was deduced that CMP was an isoform of vitellin. Concentration of CMP abruptly increased during the latter naupliar stages, reaching a peak just after metamorphosis to the non-feeding cypris stage, and decreased thereafter with aging of cyprids or during the early juvenile period. Specifically, the concentration of CMP in newly metamorphosed juveniles within one day decreased to 20% that of cyprids. CMP, therefore, appears to function as a storage protein during settlement of cyprids as well as metamorphosis to juveniles. Immunohistochemical analysis using antiserum against vitellin heavy chain on sectioned cyprids suggested that CMP is accumulated in the haemocoel.
Animals↗
Identification and partial characterization of vitellin from the barnacle Balanus amphitrite.
The major protein in occytes of the barnacle Balanus amphitrite has been identified as vitellin (Vt) and its biochemical properties partially characterized. SDS-PAGE of protein extracts from different developmental stages of occytes and embryos of B. amphitrite revealed that a 170 kDa polypeptide was abundantly present in fully matured oocytes. Its amount increased with occyte maturation and decreased with embryonic development after fertilization. Antiserum, prepared against 170 kDa polypeptide, was found to recognize only 170 kDa among proteins in ovary extract (OE) by immunoblot analysis. Immunohistochemical study indicated localization of 170 kDa polypeptide in yolk granules of oocytes, oviducts and embryos. Combination of native electrophoresis with agarose gel and SDS-PAGE displayed that the main protein in OE was lipophilic, contained 85 kDa polypeptide in addition of 170 kDa, and was positive in PAS reaction. The main peak eluted from OE contained 170 kDa and 85 kDa polypeptides, and corresponded to 200 kDa when filtrated through superose 6 gel. Conclusively, vitellin of B. amphitrite is a lipophilic glycoprotein consisting of two subunits, a heavy chain with 170 kDa and a light chain with 85 kDa. Two other barnacles, Megabalanus rosa and Tetraclita squamosa japonica, also contained proteins similar to B. amphitrite Vt.
Animals↗
Halicylindramides D and E, antifungal peptides from the marine sponge Halichondria cylindrata.
Halicylindramides D (1) and E (2) have been isolated from the marine sponge Halichondria cylindrata. Halicylindramide D is a tridecapeptide with the N-terminus blocked by a formyl group and the C-terminus lactonized with a threonine residue, while halicylindramide E is a truncated linear peptide with a C-terminal amide. Their structures, including absolute stereochemistry, were determined by a combination of spectral and chemical methods. Halicylindramide D was antifungal against Mortierella ramanniana and cytotoxic against P-388 murine leukemia cells.
Amino Acid Sequence↗
Three new cytotoxic sesterterpenes from the marine sponge Hyrtios cf. erectus.
Three new cytotoxic sesterterpenes, 1-3, have been isolated from the marine sponge Hyrtios cf. erectus. Their structures have been determined by interpretation of NMR data. They exhibited cytotoxicity against P-388 murine leukemia cells with IC50 values of 0.4-2.1 micrograms/mL.
Animals↗
Globostellatic acids A-D, new cytotoxic isomalabaricane triterpenes from the marine sponge Stelletta globostellata.
Four new cytotoxic triterpenes, globostellatic acids A-D (1-4), have been isolated from the marine sponge Stelletta globostellata. Their structures have been determined by interpretation of spectral data. They exhibited cytotoxicity against P-388 murine leukemia cells with IC50 values of 0.1-0.46 microgram/mL.
Animals↗
Montiporic acids A and B, cytotoxic and antimicrobial polyacetylene carboxylic acids from eggs of the scleractinian coral Montipora digitata.
Two new polyacetylene carboxylic acids, montiporic acids A (1) and B (2), have been isolated from the eggs of the scleractinian coral Montipora digitata and their structures elucidated on the basis of spectroscopic data. They exhibited antimicrobial activity against Escherichia coli and cytotoxicity against P-388 murine leukemia cells.
Acetates↗
Novel actin depolymerizing macrolide aplyronine A.
Aplyronine A is a macrolide isolated from Aplysia kurodai. By monitoring fluorescent intensity of pyrenyl-actin, it was found that aplyronine A inhibited both the velocity and the degree of actin polymerization. Aplyronine A also quickly depolymerized F-actin. The kinetics of depolymerization suggest that aplyronine A severs F-actin. The relationship between the concentration of total actin and F-actin at different concentrations of aplyronine A suggests that aplyronine A forms a 1:1 complex with G-actin. From these results, it is concluded that aplyronine A inhibits actin polymerization and depolymerizes F-actin by nibbling. Comparison of the chemical structure of aplyronine A and another actin-depolymerizing macrolide, mycalolide B, suggests that the side-chain but not the macrolide ring of aplyronine A may account for its actin binding and severing activity.
Actins↗
Visualization of cement exocytosis in the cypris cement gland of the barnacle Megabalanus rosa
Cementation to substrata during permanent attachment concludes the planktonic larval phase in many sessile marine invertebrates, including barnacles. However, the neural control and the mechanism of cement secretion from cement organs are poorly understood. In the present study, using isolated cement glands from cyprids of Megabalanus rosa, we have visualized cement secretion and demonstrated the stimulatory effect of dopamine and noradrenaline on such secretion. The abrupt disappearance of secretory granules and subsequent omega-figure formation indicated that exocytosis was the major mode of cement secretion. Exocytosis was localized at the apical surface of cement-secreting cells and lasted for over 30 min. Dopamine and noradrenaline also activated the directional transport of secretory granules to the sites of exocytosis. Glyoxylic acid staining provided histochemical evidence for catecholaminergic innervation to the cement glands. These results suggest that gradual, localized exocytotic secretion of cement triggered by catecholaminergic neurones is a key mechanism during permanent attachment by barnacle cyprids.
Journal Article↗
Cellular changes of rat embryonic fibroblasts by an actin-polymerization inhibitor, bistheonellide A, from a marine sponge.
Bistheonellide A, an inhibitor of actin polymerization from the marine sponge Theonella sp., was introduced at a concentration of 100 nM into rat fibroblast of 2.4 x 10(4) cells/ml. Within 1 h, it disrupted stress fibers, accompanied by a marked change of the cell morphology, resulting in the formation of processes from the cell surface. Further incubation for 24 h in the presence of 100 nM bistheonellide A led to binucleation in most cells and subsequent inhibition of cell cycle progression. When bistheonellide A was withdrawn from the culture medium, binuclear cells began to grow again within 20 h and reverted to mononuclear morphology. Flow cytometric analysis fluorescence-activated cell sorting showed that 2C diploid DNA content in G1 phase was changed into 4C content of tetraploid for the bistheonellide A treated-cells in G1 phase and into 8C content during G2 and M phase. Therefore, we suggested that the bistheonellide A treatment inhibited cytokinesis, but not mitosis in M phase, and that treated cells were arrested at the early G1 phase. These effects of bistheonellide A on the cell cycle progression of 3Y1 fibroblast were also observed more prominently in cells synchronized in S phase with hydroxyurea. Cells in G0 phase were then activated by the addition of fetal calf serum in the presence of 100 nM bistheonellide A. Cell cycle progression of the bistheonellide A-treated cells was obviously slowed down or completely inhibited during G1 phase. These results reveal that actin filaments are not only essential to cytokinesis but also for promoting the progression of cell cycle G1 to S phase.
Actins↗
Halicylindramides A-C, antifungal and cytotoxic depsipeptides from the marine sponge Halichondria cylindrata.
Halicylindramides A-C (1-3) have been isolated from the Japanese marine sponge Halichondria cylindrata. They are tetradecapeptides with the N-terminus blocked by a formyl group and the C-terminus lactonized with a threonine residue. Their total structures including absolute stereochemistry were determined by a combination of spectral and chemical methods. Halicylindramides A-C were antifungal against Mortierella ramanniana and cytotoxic against P388 murine leukemia cells.
Amino Acid Sequence↗
Three more cyclotheonamides, C, D, and E, potent thrombin inhibitors from the marine sponge Theonella swinhoei.
Three new thrombin and trypsin inhibitors, cyclotheonamides C (3), D (4), and E (8) were isolated from the marine sponge Theonella swinhoei. Their structures were determined by spectral and chemical methods.
Animals↗
Mycalolide B, a novel actin depolymerizing agent.
We investigated the effects of a novel marine toxin, mycalolide B, on actin polymerization and actin-activated myosin Mg(2+)-ATPase activity using purified actin and myosin from rabbit skeletal muscle. The results were compared with cytochalasin D which inhibits actin polymerization by binding to the barbed end of F-actin. By monitoring fluorescent intensity of pyrenyl-actin, mycalolide B did not accelerate actin polymerization but quickly depolymerized F-actin, whereas cytochalasin D accelerated actin nucleation and depolymerized F-actin at slower rate. The kinetics of depolymerization suggest that mycalolide B severs F-actin. The relationship between the concentration of total actin and F-actin at different concentration of mycalolide B suggests that mycalolide B forms 1:1 complex with G-actin. Viscometry and electron microscopic observation further suggest that actin filament was depolymerized by mycalolide B. Unlike cytochalasin D, furthermore, mycalolide B suppressed actin-activated myosin Mg(2+)-ATPase activity. We concluded that mycalolide B severs F-actin and sequesters G-actin and may serve as a novel pharmacological tool for analyzing actin-mediated cell functions.
Actins↗
Corticatic acids A-C, antifungal acetylenic acids from the marine sponge, Petrosia corticata.
Three new acetylenic acids, corticatic acids A-C [1-3] have been isolated from the marine sponge, Petrosia corticata. Their structures were determined by spectroscopic methods, and 1-3 exhibited antifungal activity against Mortieralla ramanniana.
Animals↗
Antibacterial and antifungal sulfated alkane and alkenes from the hepatopancreas of the ascidian Halocynthia roretzi.
Four new antibacterial and antifungal sulfates, 2,6-dimethylheptyl sulfate [1], (4Z,7Z)-4,7-decadienyl sulfate [2], (4Z,7E)-4,7-decadienyl sulfate [3], and (3Z,6Z)-3,6,9-decatrienyl sulfate [4], have been isolated from the hepatopancreas of the ascidian Halocynthia roretzi. The structures were determined by spectral analysis.
Alkanes↗
Mycalolide-B, a novel and specific inhibitor of actomyosin ATPase isolated from marine sponge.
A toxin isolated from marine sponge, mycalolide-B, inhibited smooth muscle contractions without changing cytosolic Ca2+ levels. It also inhibited Ca(2+)-induced contraction in permeabilized smooth muscles. In native actomyosin prepared from chicken gizzard, mycalolide-B inhibited superprecipitation and Mg(2+)-ATPase activity stimulated by Ca2+ without changing myosin light chain phosphorylation. In the permeabilized muscle and native actomyosin preparation thiophosphorylated with ATP gamma S, mycalolide-B inhibited ATP-induced contraction and Mg(2+)-ATPase activity, respectively, in the absence of Ca2+. Mycalolide-B also inhibited Mg(2+)-ATPase activity of skeletal muscle native actomyosin. Mycalolide-B had no effect on calmodulin-stimulated (Ca(2+)-Mg2+)-ATPase activity of erythrocyte membranes. These results suggest that mycalolide-B selectively inhibits actin-myosin interaction.
Actins↗
Inhibition of thrombin and other trypsin-like serine proteinases by cyclotheonamide A.
Cyclotheonamide A (CA), a cyclic peptide isolated from the marine sponge of the genus Theonella was shown to be a slow-binding inhibitor of several trypsin-like serine proteinases. Values of 4.6 x 10(4), 4.8 x 10(4), 9.3 x 10(3), 2.1 x 10(3) and 2.7 x 10(2) M-1 s-1 were determined for the second-order rate constants for formation of CA complexes with thrombin, trypsin, plasmin, 2-chain t-PA and factor Xa, respectively. The equilibrium constant (Ki) was measured for dissociation of CA from the CA complex with human thrombin (Ki = 1.0 nM), bovine trypsin (Ki = 0.2 nM), human plasmin (Ki = 12 nM), human factor Xa (Ki = 50 nM) and human 2-chain tissue plasminogen activator (t-PA) (Ki = 40 nM). CA produces dose dependent increases in clotting time assays. The clotting time in the thrombin time, activated partial thromboplastin time and prothrombin time assays, were doubled by 1.5, 0.9 and 48 microM CA, respectively. A model for the binding of CA to the active site of thrombin is proposed.
Binding Sites↗
Calyculin A induces contractile ring-like apparatus formation and condensation of chromosomes in unfertilized sea urchin eggs.
Calyculin A, a protein phosphatase inhibitor, induced cleavage-like morphological change in unfertilized sea urchin eggs. A contractile ring-like apparatus containing both filamentous actin and myosin was formed in the cleavage furrow. Wheat germ agglutinin receptors were also found in the same region. The eggs did not develop further after constriction of the ring. No aster-like microtubular structure was found in the calyculin A-treated eggs. The cleavage was not inhibited by the antimicrotubule drug griseofulvin. Calyculin A also increased histone H1 kinase activity and induced chromosome condensation. These changes also occurred in the presence of emetine (an inhibitor of protein synthesis) and aphidicolin (an inhibitor of DNA synthesis). It is suggested that calyculin A induced these changes in the sea urchin eggs by inhibiting the activity of protein phosphatase 1.
Actin Cytoskeleton↗