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The roundworm, Caenorhabditis elegans , is known to carry homologues of clock genes such as per (= period ) and tim (= timeless ), which constitute the core of the circadian clock in Drosophila and mammals: lin - 42 and tim - 1 . Analyses using WormBase ( C. elegans gene database) have identified with relatively high identity analogous of the clock genes recognized in Drosophila and mammals, with the notable exception of cry (= cryptochrome ), which is lacking in C. elegans. All of these C. elegans cognates of the clock genes appear to belong to members of the PAS-superfamily and to participate in development or responsiveness to the environment but apparently are not involved in the C. elegans circadian clock. Nevertheless, C. elegans exhibits convincing circadian rhythms in locomotor behavior in the adult stage and in resistance to hyperosmotic stress in starved larvae (L1) after hatching, indicating that it has a circadian clock with a core design entirely different from that of Drosophila and mammals. Here two possibilities are considered. First, the core of the C. elegans circadian clock includes transcriptional/translational feedback loops between genes and their protein products that are entirely different from those of Drosophila and mammals. Second, a more basic principle such as homeostasis governs the circadian cellular physiology, and was established primarily to minimize the accumulation of DNA damage in response to an environment cycling at 24 h intervals. [ABSTRACT FROM AUTHOR]

A novel glycosphingolipid, tucosyltetrahexosylceramide, has been isolated from the plerocercoids of a tapeworm. Spirometra erinacei, and characterized by permethylation analysis, sequential degradation with exoglycosidases, fast atom bombardment MS and lH-NMR. The chemical structure was determined to be as follows [this equation can not be changed in character ] This glycosphingolipid was tentatively designated as GaISEGLx, in which the carbohydrate structure is characterized by an additional galactose molecule attached to the reducing and galactose of SEGLx [Ga1β-4(Fucα-3)Glcβ-3GaI/βCer], which was previously determined by us [Kawakami, Y., Nakamura, K., Kojima, H.. Suzuki, M.. Inagaki. F, Suzuki. A., Sonoki, S.. Uchida, A., Murata, Y. & Tamai, Y. (1993) J. Biochem, 114, 677-683]. through a β1 -6 linkage. The ceramide contained sphinganine and 4D-hydroxysphinganine in an about equimolar ratio, and a non-hydroxy fatty acid with carbon atoms ranging from 16 to 28, 26:0, 28 .0 and 28: 1 being major components. Based on tile finding that a novel carbohydrate structure, Galβ-4G1cβ-3GaL was commonly found in glycosphingohpids from the parasite, S. erinacei, we here propose the terms, spirometosenes, for this core structure series, and spirometosides for glycocphingohpids having this carbohydrate structure. [ABSTRACT FROM AUTHOR]

The occurrence of glycosphingolipids with unique carbohydrate structures in different species of cestode, Platyhelminth, which had been shown, previously, prompted us to study the molecular species of the monohexosylceramides (cerebrosides) in the pseudophyllidean cestode, Spirometra erinacei. The purpose of the study was to obtain a basis for future investigations of the physiological role of glycolipids in parasitism. Cerebrosides were isolated from s. erinacei at two growth stages, i.e., from the larval form (plerocercoid) and from the adult tapeworms (intestinal form). The cerebrosides were separated into four subfractions by silica gel column chromatography, and their constituents were analyzed by gasliquid chromatography, gas chromatography/mass spectrometry, and high-performance liquid chromatography/mass spectrometry. The hexoses of the cerebrosides consisted primarily of galactose in both growth stages, while only a small amount of glucose was detected. The ceramides were composed of sphinganine (d18∶0) and phytosphingosine (t18∶0) as sphingoid bases, and of nonhydroxy fatty acids ranging from C to C and hydroxy stearic acid (18h∶0). The cerebrosides of adult tapeworms contained more 18h∶0 than those of plerocercoids. The combination of hexoses and ceramides in the cerebroside molecules was slightly different in the two growth stages: the glucocerebrosides of plerocercoids contained only d18∶0-nonhydroxy fatty acids in their ceramide moieties, whereas those of adult tapeworms contained varying ceramide moieties. Our data indicate that the molecular species of glycolipids present were essentially homeostatic throughout growth in spite of the entirely different environmental conditions, although there were slight differences in the hexose distribution in the two growth stages. [ABSTRACT FROM AUTHOR]