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- Bourlat, Sarah, et al.
(författare)
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Feeding ecology of Xenoturbella bocki (phylum Xenoturbellida) revealed by genetic barcoding
- 2008
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Ingår i: Molecular Ecology Resources. - 1755-098X. ; 8, s. 18-22
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Tidskriftsartikel (refereegranskat)abstract
- The benthic marine worm Xenoturbella is frequently contaminated with molluscan DNA, which had earlier caused confusion resulting in a suggested bivalve relationship. In order to find the source of the contaminant, we have used molluscan sequences derived from Xenoturbella and compared them to barcodes obtained from several individuals of the nonmicroscopic molluscs sharing the same environment as Xenoturbella. Using cytochrome oxidase 1, we found the contaminating sequences to be 98% similar to the bivalve Ennucula tenuis. Using the highly variable D1-D2 region of the large ribosomal subunit in Xenoturbella, we found three distinct species of contaminating molluscs, one of which is 99% similar to the bivalve Abra nitida, one of the most abundant bivalves in the Gullmarsfjord where Xenoturbella was found, and another 99% similar to the bivalve Nucula sulcata. These data clearly show that Xenoturbella only contains molluscan DNA originating from bivalves living in the same environment, refuting former hypotheses of a bivalve relationship. In addition, these data suggest that Xenoturbella feeds specifically on bivalve prey from multiple species, possibly in the form of eggs and larvae.
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- Larsson, Kim P, et al.
(författare)
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Orexin-A-induced Ca2+ entry : evidence for involvement of trpc channels and protein kinase C regulation.
- 2005
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Ingår i: J Biol Chem. - 0021-9258. ; 280:3, s. 1771-81
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Tidskriftsartikel (refereegranskat)abstract
- The orexins are peptide transmitters/hormones, which exert stimulatory actions in many types of cells via the G-protein-coupled OX(1) and OX(2) receptors. Our previous results have suggested that low (subnanomolar) concentrations of orexin-A activate Ca(2+) entry, whereas higher concentrations activate phospholipase C, Ca(2+) release, and capacitative Ca(2+) entry. As shown here, the Ca(2+) response to subnanomolar orexin-A concentrations was blocked by activation of protein kinase C by using different approaches (12-O-tetradecanoylphorbol acetate, dioctanoylglycerol, and diacylglycerol kinase inhibition) and protein phosphatase inhibition by calyculin A. The Ca(2+) response to subnanomolar orexin-A concentrations was also blocked by Mg(2+), dextromethorphan, and tetraethylammonium. These treatments neither affected the response to high concentrations of orexin-A nor the thapsigargin-stimulated capacitative entry. The capacitative entry was instead strongly suppressed by SKF96365. An inward membrane current activated by subnanomolar concentrations of orexin-A and the currents activated upon transient expression of trpc3 channels were also sensitive to Mg(2+), dextromethorphan, and tetraethylammonium. Responses to subnanomolar concentrations of orexin-A (Ca(2+) elevation, inward current, and membrane depolarization) were voltage-dependent with a loss of the response around -15 mV. By using reverse transcription-PCR, mRNA for the trpc1-4 channel isoforms were detected in the CHO-hOX1-C1 cells. The expression of truncated TRPC channel isoforms, in particular trpc1 and trpc3, reduced the response to subnanomolar concentrations of orexin-A but did not affect the response to higher concentrations of orexin-A. The results suggest that activation of the OX(1) receptor leads to opening of a Ca(2+)-permeable channel, involving trpc1 and -3, which is controlled by protein kinase C.
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