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751.
Lilli Arndt Jan Castonguay Elisabeth Arlt Dorke Meyer Sami Hassan Heike Borth Susanna Zierler Gunther Wennemuth Andreas Breit Martin Biel Christian Wahl-Schott Thomas Gudermann Norbert Klugbauer Ingrid Boekhoff 《Molecular biology of the cell》2014,25(6):948-964
The functional relationship between the formation of hundreds of fusion pores during the acrosome reaction in spermatozoa and the mobilization of calcium from the acrosome has been determined only partially. Hence, the second messenger NAADP, promoting efflux of calcium from lysosome-like compartments and one of its potential molecular targets, the two-pore channel 1 (TPC1), were analyzed for its involvement in triggering the acrosome reaction using a TPCN1 gene–deficient mouse strain. The present study documents that TPC1 and NAADP-binding sites showed a colocalization at the acrosomal region and that treatment of spermatozoa with NAADP resulted in a loss of the acrosomal vesicle that showed typical properties described for TPCs: Registered responses were not detectable for its chemical analogue NADP and were blocked by the NAADP antagonist trans-Ned-19. In addition, two narrow bell-shaped dose-response curves were identified with maxima in either the nanomolar or low micromolar NAADP concentration range, where TPC1 was found to be responsible for activating the low affinity pathway. Our finding that two convergent NAADP-dependent pathways are operative in driving acrosomal exocytosis supports the concept that both NAADP-gated cascades match local NAADP concentrations with the efflux of acrosomal calcium, thereby ensuring complete fusion of the large acrosomal vesicle. 相似文献
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Thomas Arndt 《Journal of Ornithology》2006,147(1):73-86
Prompted by field observations in 2001 in the Utcubamba Valley, Peru, a study was undertaken of 130 specimens in the Aratinga mitrata complex. As a result, the traditional arrangement of Aratinga mitrata (A. m. mitrata Tschudi 1844 and A. m. alticola Chapman 1921) as one species, is replaced with a new classification where Aratinga mitrata is divided into five taxa, A. m. mitrata Tschudi 1844, Aratinga mitrata chlorogenys ssp. nov and Aratinga mitrata tucumana ssp. nov, Aratinga hockingi sp. nov, and A. alticola Chapman 1921. 相似文献
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Muktheshwar Gandesiri Saritha Chakilam Jelena Ivanovska Natalya Benderska Matthias Ocker Pietro Di Fazio Maria Feoktistova Hala Gali-Muhtasib Margret Rave-Fränk Olaf Prante Hans Christiansen Martin Leverkus Arndt Hartmann Regine Schneider-Stock 《Apoptosis : an international journal on programmed cell death》2016,21(5):671-674
760.
Ratni Saini Olga Kataeva Arndt W. Schmidt Yuqin Wang Anna Meljon William J. Griffiths Hans-Joachim Knölker 《Bioorganic & medicinal chemistry》2013,21(18):5794-5798
Using 3β-hydroxychol-5-en-24-oic acid (4) as starting material, the diastereoisomeric allylic alcohols (24E)-26-hydroxydesmosterol (2) and (24Z)-26-hydroxydesmosterol (3) have been synthesised in six steps with 67% and 12% overall yield, respectively. Both of these isomers are found in newborn mouse brain where sterol synthesis is high. Unlike desmosterol (1), neither of these isomers is a ligand to the liver x receptors and thus represents a novel biological deactivation mechanism avoiding cholesterol synthesis. 相似文献