Ascidians biology

Villa, L. Patricolo, E. Follicle cells of Styela plicata eggs (Ascidiacea), In Sawada, H. Yokosawa, H. Lambert, C. C. (Eds.), The Biology of Ascidians, Springer-Verlag, Tokyo, 2001. 

Donia, M.S., Hathaway, B.J., Sudek, S. et al. (2006) Natural combinatorial peptide libraries in cyanobacterial symbionts of marine ascidians. Nature Chemical Biology, 2, 729. 

The isolation from a marine ascidian and subsequent structure determination of polycitone A (105) (Fig. 6) was first reported [52] by Kashman and coworkers in 1994. In this paper, the penta-O-methyl derivative was reported to inhibit the growth of SV40 transformed fibroblast cells at a concentration of 10 jtg/mL. Loya, Hizi and Kashman published [53] an extensive account of the biological activity of polycitone A in 1999 in which case inhibition of retroviral reverse transcriptases and cellular DNA polymerases was described. The isolation from an ascidian and structure determination of polycitone B (106) (Fig. 4) was subsequently reported [54] by Kashman and coworkers in 2000. Obviously, the presence of extensive bromination in both polycitone A and B make this family of compounds unique among the 3,4-diarylpyrrole natural products. 

The sea squirts or tunicates are fascinating marine creatures, their name being derived from the tunic made of cellulosic material that surrounds the body of the animal. In 1911, Henze discovered vanadium in the blood of Phallusia mammillata C.343 He later found the same with other ascidians (a class of tunicates). In vanadium-accumulating species, most vanadium is located in the vacuoles—vanadophores—of certain types of blood cells—the vanadocytes. The concentration in the vanadophore can be as high as 1M and this value must be compared with concentrations of the order of 2 x 10-8 M for vanadium in sea water.344 Kustin et al. have reviewed the work done to understand the efficient accumulation and the possible biological roles of the metal.345... 

Aminoacids occur in plants and animals, both in the free state and as the basic units of proteins and other metabolites. Aminoacid derivatives have been reported in marine environment, such as from marine sponges of the genus Jaspis sp. [371,372], from Suberea creba, a Coral Sea marine sponge [373], and the marine ascidian Leptoclinides dubius [374], Some of these compounds have been shown to possess interesting biological properties, e g., cytostatic activity exhibited by axinastatin-4, an aminoacid derivative isolated from a marine sponge [375],... 

Verbitski SM, Mayne CL, Davis RA, Concepcion GP, Ireland CM (2002) Isolation, Structure Determination, and Biological Activity of a Novel Alkaloid, Perophoramidine, from the Philippine Ascidian Perophora namei. J Org Chem 67 7124... 

McClintock, J.B., Heine, J., Slattery, M., and Weston, J., Biochemical and energetic composition, population biology, and chemical defense of the antarctic ascidian Cnemidocarpa verrucosa Lesson, J. Exp. Mar. Biol. Ecol., 147, 163, 1991. 

Ueki, T., N. Yamaguchi, and H. Michibata. 2003. Chloride channel in vanadocytes of a vanadium-rich ascidian Ascidia sydneiensis samea. Comp. Biochem. Physiol. B Biochem. Mol. Biolog. 136 91-98. 

Michibata, H., N. Yamaguchi, T. Uyama, and T. Ueki. 2003. Molecular biological approaches to the accumulation and reduction of vanadium by ascidians. Coord. Chem. Rev. 237 41-51. 

The biosynthetic origin of marine natural products is a complex topic that has gained more clarity through application of molecular biological study microbial symbionts may represent the true source in many sponges, ascidians, and bryozoans, even in cases in which localization studies have suggested an invertebrate source for... 

Vanadium occurs in a few biological systems, and particularly in the blood of a group of sea creatures (Ascidians) where it may function as an... 

III trials in Europe) [70]. The biomedical potential of the ascidian metabolites has resulted in these primitive chordates. As part of our ongoing chemical and biological studies on Okinawan marine organisms, we investigated an ascidian Lissoclinum sp. collected off the coast of Hateruma Island. A lipophilic extract of the ascidian showed that it could inhibit the division of fertilized sea urchin eggs. 

Vanadium has long been recognized as a biologically active metal which has an important metabolic role in various marine organisms 53). A vanadium concentration 5 x 105 times that found in natural sea water has been reported in the blood of the ascidian Phallusia mamillata 57). Vanadium is concentrated in form of the blood pigment hemovanadium58). Moreover, vanadium enrichment factors of 4500 in scallops, 2500 in mussels, and 1500 in oysters were observed 59). 

All of the findings in the biological chemistry of vanadium have their history. In order to appreciate and to value the impact of early perceptions and their protagonists, I have analysed a couple of early and original documents on, e.g., vanadium nitrogenase, vanadium in the blood of ascidians and vanadium compounds as a remedy for a plethora of diseases. Snapshots of these historical events have been included. Included, in the first chapter, is also a detailed account on the discovery of vanadium. 

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