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The mammalian circadian clock lying in the suprachiasmatic nucleus (SCN) controls daily rhythms and synchronizes the organism to its environment. In all organisms studied, circadian timekeeping is cell-autonomous, and rhythmicity is thought to be generated by a feedback loop involving clock proteins that inhibit transcription of their own genes. In the(More)
The suprachiasmatic nucleus (SCN) is the principal circadian pacemaker in mammals. A salient feature of the SCN is that cells of a particular phenotype are topographically organized; this organization defines functionally distinct subregions that interact to generate coherent rhythmicity. In Syrian hamsters (Mesocricetus auratus), a dense population of(More)
A circadian clock located in the suprachiasmatic nucleus (SCN) regulates the period of physiological and behavioural rhythms to approximately 24 h. Lithium can lengthen the period of circadian rhythms in most organisms although little is known about the underlying mechanism. In the present study, we examined Drosophila shaggy ortholog glycogen synthase(More)
Polytheonamide B (pTB), a highly cytotoxic polypeptide, is one of the most unusual nonribosomal peptides of sponge origin. pTB is a linear 48-residue peptide with alternating D- and L-amino acids and contains a total of eight types of nonproteinogenic amino acids. To investigate the mechanisms underlying its cytotoxic activity, we determined the(More)
In mammals, the suprachiasmatic nuclei (SCN) of the hypothalamus control endogenous circadian rhythms and entrainment to the environment. A core SCN region of calbindin (CalB)-containing cells is retinorecipient and the cells therein lack rhythmic expression of clock genes and electrical activity. The core is surrounded by a 'shell' of rhythmic oscillator(More)
It is well known that light resets the circadian clock only at specific times of day. The mechanisms mediating such gating of environmental input to the CNS are not well understood. We show that calbindinD28K (CalB)-containing cells of the suprachiasmatic nucleus (SCN), which are directly retinorecipient, gate photic entrainment of cellular circadian(More)
Ascidians belonging to the suborder Phlebobranchia are known to accumulate high levels of a transition metal, vanadium, in their blood cells, called vanadocytes, although the mechanism for this biological phenomenon remains unclear. Recently, we identified vanadium(IV)-binding proteins, designated as Vanabins, from vanadium-accumulating ascidians. Here, we(More)
Several species of ascidians, the so-called tunicates, accumulate extremely high levels of vanadium ions in their blood cells. We previously identified a family of vanadium-binding proteins, named Vanabins, from blood cells and blood plasma of a vanadium-rich ascidian, Ascidia sydneiensis samea. The 3-dimensional structure of Vanabin2, the predominant(More)
Two new bisalkaloids, dipiperamides D and E, were isolated as inhibitors of a drug metabolizing enzyme cytochrome P450 (CYP) 3A4 from the white pepper, Piper nigrum. Their structures were elucidated by spectroscopic methods. Dipiperamides D and E showed potent CYP3A4 inhibition with IC(50) values of 0.79 and 0.12 microM, respectively, and other metabolites(More)
Axinelloside A was isolated from the lipophilic extract of the Japanese marine sponge Axinella infundibula as a strong human telomerase inhibitor (IC(50) 2.0 microg/mL). It has the molecular weight of 4780.4 as the monoisotopic mass of the 19 sodium salt. The chemical structure was elucidated mainly by spectroscopic methods (2D NMR and MS). Axinelloside A(More)