caa a22 4500 477101623 CHVBK 20180405111543.0 cr unu---uuuuu 170330e19960701xx s 000 0 eng 10.1007/BF00195726 doi (NATIONALLICENCE)springer-10.1007/BF00195726 Calcium-dependent membrane depolarisation activated by phytochrome in the moss Physcomitrella patens [Elektronische Daten] [Elena Ermolayeva, Helmuth Hohmeyer, Eva Johannes, Dale Sanders] In caulonemal filaments of Physcomitrella patens which had been preincubated in the dark for 24 h, irradiation with red light (640 nm, fluence rate 85 μmol · m−2 · s−1) evoked (i) the development of side branch initials and (ii) a rapid, but transient, depolarisation of the plasma membrane by 90 ± 13 mV from a resting potential of -178 ± 13 mV. This was followed by a transient hyperpolarisation to a value 21± 8 mV more negative than the original membrane potential. The refractory period for the transient depolarisation was between 12 and 15 min. The fluence rate of red light required to evoke maximal depolarisation was about 80 μmol · m−2 · s−1 for a 1-min pulse. At this fluence rate, a depolarising response could be recorded for pulse lengths as small as 7 s. The transient depolarisation was insensitive to 3-(3′,4′dichlorophenyl)-1,1-dimethyl urea (DCMU) and was unchanged in plants bleached by growth on norflurazon (SAN 9789). Furthermore, the electrical response could be blocked by simultaneous application of far-red light. These results suggest the involvement of the photoreceptor phytochrome in the response. Removing Ca2+ from the external medium or replacing Ca2+ with Mg2+ blocked the depolarisation. The depolarisation could also be blocked by the K+ channel-blocker tetraethylammonium (10 mM) and the Cl− channel-blocker niflumic acid (1 μM). Conversely, although calcium channel-antagonists such as nifedipine and lanthanides, applied at a concentration of 100 μM, also altered the response, they did not block it. A possible ionic mechanism for the membrane potential transient is advanced, and the physiological significance discussed in the context of early events in the phytochrome signalling pathway. Springer-Verlag, 1996 Membrane depolarisation nationallicence Physcomitrella nationallicence Phytochrome nationallicence [Ca2+]c : cytosolic Ca2+ concentration nationallicence DCMU : 3-(3′,4′-dichlorophenyt)-1,1-dimethylurea nationallicence TEA : tetraethylammonium nationallicence Ermolayeva Elena The Plant Laboratory, University of York, PO Box 373, Y01 5YW, York, UK aut Hohmeyer Helmuth The Plant Laboratory, University of York, PO Box 373, Y01 5YW, York, UK aut Johannes Eva The Plant Laboratory, University of York, PO Box 373, Y01 5YW, York, UK aut Sanders Dale The Plant Laboratory, University of York, PO Box 373, Y01 5YW, York, UK aut Planta Springer-Verlag 199/3(1996-07-01), 352-358 0032-0935 199:3<352 1996 199 425 https://doi.org/10.1007/BF00195726 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00195726 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ermolayeva Elena The Plant Laboratory, University of York, PO Box 373, Y01 5YW, York, UK aut NATIONALLICENCE 700 1- Hohmeyer Helmuth The Plant Laboratory, University of York, PO Box 373, Y01 5YW, York, UK aut NATIONALLICENCE 700 1- Johannes Eva The Plant Laboratory, University of York, PO Box 373, Y01 5YW, York, UK aut NATIONALLICENCE 700 1- Sanders Dale The Plant Laboratory, University of York, PO Box 373, Y01 5YW, York, UK aut NATIONALLICENCE 773 0- Planta Springer-Verlag 199/3(1996-07-01), 352-358 0032-0935 199:3<352 1996 199 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer