Asterias rubens

Hetherington, L.H., Livingstone, D.R., and Walker, C.H. (1996). Two and one-electron dependant reductive metabolism of nitroaromatics by Mytilus edulis, Carcinus maenas and Asterias rubens. Comparative Biochemistry and Physiology 113, 231-239. 

Recently, Voogt et al. [91] have reported on the d5-pathway in steroid metabolism of Asterias rubens. These workers established the existence of the d5-pathway (Scheme 20), analogous to the pathway found in mammals this conclusion was based on the observation that radiolabeled cholesterol (1) was converted to pregnenolone (112), 17a-hydroxypregnenolone (141), and androstenediol (142). Labeled pregnenolone was converted additionally to progesterone (129). Androstenediol (142) was the main metabolite of de-hydroepiandrosterone (143), a reaction catalyzed by 17/i-hydroxysteroid dehydrogenase (17/1-HSD). The metabolic conversion of androstenedione (131) to testosterone (132) is also mediated by 17/J-HSD and is related to... 

Egg Starfish, Asterias rubens 326 Irreversible inhibition of fertilization membrane formation in eggs transferred 10 sec. after insemination 46... 

Voogt, P.A., P.J.D. Besten, G.C.M. Kusters, and M.W.J. Messing. 1987. Effects of cadmium and zinc on steroid metabolism and steroid level in the sea star Asterias rubens L. Comp. Biochem. Physiol. 86C 83-89. 

Everaarts, J.M., H.M. Sleiderink, P.J. den Besten, R.S. Halbrook, and L.R. Shugart. 1994. Molecular responses as indicators of marine pollution DNA damage and enzyme induction in Limanda limanda and Asterias rubens. Environ. Health. Perspect. 102, Suppl. 12 37-43. 

Sandworm, Nereis diversicolor, whole British Columbia various locations Polychaete worms, 3 species whole California Echinoderms Starfish, Asterias rubens Gonad... 

Considerable proportions of cerebroside have been detected in the starfish Asterias rubens.9Ail0 It is a glucosylceramide having a-hydroxy fatty acids (from C16 to C26) and dihydroxy bases whose major components are Cl8 and C22 bases, with one, or two, double bonds. 

Figure 5.1.1 Extraction scheme and LC-NMR-MS screening approach for the targeted isolation of new natural products as applied to asterosaponins of Asterias rubens...

Class Asteroidea, sea stars, is one of the most widely recognized groups of marine organisms due to their prevalence upon the shoreline and their characteristic shape. Asteroids are top predators in benthic ecosystems, often preying upon bivalves from the phylum Mollusca. The isoprenoid compound mytiloxanthin, for example, has been isolated from both the sea star Asterias rubens and the bivalve Mytilus edulis,119 The class Concentricycloidea was first identified in 1986 and consists of two species in the genus Xyloplax. Class Ophiuroidea, brittle stars, contains the greatest number... 

A second natural product study reported in 2003 that used the sensitivity of cryogenic probe capabilities and the HSQC-TOCSY experiment to advantage was the report by Preiss et al.25S that detailed the elucidation of the structure of two new asterosaponins from the starfish Asterias rubens. The structure of one of the molecules characterized (110) of which only 0.3 mg was isolated, is shown. 

M. Sandvoss, A. Weltring, A. Preiss, K. Levsen, and G. Wnensch, Combination of matrix solid-phase dispersion extraction and direct on-line liqnid chromatography-nnclear magnetic resonance spectroscopy-tandem mass spectrometry as a new efficient approach for the rapid screening of natural prodncts Application to the total asterosaponin fraction of the starfish Asterias rubens, J. Chromatogr A 917 (2001), 75-86. 

Large amounts of C28 and C29 sterols occur in asteroids and other echinoderms but it seems that they cannot be synthesized from C27 sterols by transmethylation as is the case in plants (but not in other animals). This was confirmed with the starfish Laiaster leechii, which could convert MVA into A -cholesterol but could not alkylate this at C-24 or introduce a A -bond. Similarly the starfish Asterias rubens can only synthesize C27 sterols de novo, but here there is evidencethat a A -bond can be introduced into both cholesterol and A -cholesterol. This starfish can also synthesize A -sterols and there is some indication that cholesterol itself may be synthesized even though it was previously concluded that the family could not perform the final steps in this biosynthesis. This species also rapidly metabolized dietary steroids and such A -sterols could be converted into A -products, but it was considered unlikely that the organism had the ability to dealkylate C28 and C29 sterols. 

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