Tunicates Halocynthia roretzi

Recent electron, X-ray and neutron diffraction work has established the structures for both cellulose and Ip. Microcrystalline samples were obtained by mild acid hydrolysis of the cellulose walls of the freshwater alga Glaucocystis nostochinearum and the tunicate Halocynthia roretzi and were... 

Figure 9 Raman spectra of tunicate (Halocynthia roretzi) and Valonia macrophysa celluloses in the Raman active regions.

Homogeneous D-galactan sulphates have been isolated from the testes of the tunicates Halocynthia roretzi and Styela plicata. The results of optical rotation, i.r.spectroscopy, and acid hydrolysis studies suggest that the polysaccharides have repeating sequences of a-L-galactopyranosyl 4-sulphate and a-L-galactopyranosyl 6(or 3)-sulphate. 

Natural products are a mixture of these two modifications. Cellulose Ip is dominant in plants and wood, and the percentage of cellulose present varies depending on the species and the treatments. For example, the cellulose Ip content of cotton linter and ramie is 77%. Cellulose I transformed into cellulose Ip by a hydrothermal treatment in an alkali solution or by heat treatment at 280 °C in an inert gas. For example, Horii et al. reported that cellulose Ip content increases to 90% by heat treatment at 260°C in 0.1 M NaOH aqueous solution [21]. This indicates that cellulose Ip is thermodynamically more stable than cellulose Almost pure cellulose Ip is obtained from tunicates Halocynthia roretzi). Cellulose h is reported to be the major component of bacterial and algal cellulose. The structural difference between I and Ip is said to be brought about by shear stress during biosynthesis of cellulose microfibrils. 

Nomura and Ogata provided the first evidence that tunicates can produce PGs [17]. Using a rat stomach fundus bioassay, Halocynthia roretzi tissues were shown to possess low levels of PGs. The testes showed higher levels (9 ngg-1 wet tissue) than ovary and muscle tissue. The sea-squirt Styela clava did not show PGs by this method. No structures were determined in this work. Reexamination of the ability of H, roretzi to produce PGs was carried out by Ogata and coworkers [19]. Incubation of selected tissues with 14C-labeled eicosa-8,11,14-trienoic acid and subsequent isolation of PGE and PGF fractions after addition of carrier showed the branchial tissue to have the highest conversion levels. Quantitation was done by LSC. Using a TLC radioscanner, the authors determined that fractions with metabolites similar to PGE and PGF... 

Lumichrome (Figure 10.1), a water-soluble degradation product of riboflavin,157 appears to be the first characterized gregarious (produced by conspecifics) cue for induction of metamorphosis of a marine invertebrate. Lumichrome is exuded into aqueous media from cultures of larvae of the ascidian Halocynthia roretzi, and was also found in the eggs, gonads, and tunic of the adults following extraction in methanol.157 Metamorphosis of larvae was induced by purified lumichrome... 

An analysis of the pH dependence of the Km and Vmax of the reaction catalysed by j8-D-2-acetamido-2-deoxyhexosidase in electrophoretically pure form from Halocynthia roretzi, a tunicate ascidian, gave evidence of two fractionally important ionogenic groups of the enzyme. One of these controls the binding of the substrate, and in the free enzyme, has a pKa of 5.5. The other group (pKa 5.6) is essential for the catalytic step and evidently does not change its pKa value when substrate is added. 

Terpene hydroquinones which are well known as constituents of other marine organisms have been isolated from the ascidian Aplidium constellatum, (750). These compounds demonstrated activity as anticancer agents. In the case of A. constellatum, 2-methyl-2-(4-methylpent-3-enyl)-2/f-chromen-6-ol could be identified. Five new carotenoids have been obtained from tunicates, halocynthiaxanthin (1067) (751) and mytiloxanthinone (1068) (752) from Halocynthia roretzi, sidnyax-anthin (1069) from Sidnyum argus (755) and amarouciaxanthin A (1070) and B (1071) from Amaroucium pliciferum (733a). Halocynthia aurantium furnished two known carotenoids, astaxanthin and diatoxan-... 

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