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Rapid spatiotemporal patterning of cytosolic Ca 2+ underlies flagellar excision in Chlamydomonas reinhardtii
Author(s) -
Wheeler Glen L.,
Joint Ian,
Brownlee Colin
Publication year - 2008
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2007.03349.x
Subject(s) - chlamydomonas reinhardtii , chlamydomonas , cytosol , flagellum , microbiology and biotechnology , mutant , biology , cell , calcium , biophysics , chemistry , biochemistry , gene , organic chemistry , enzyme
Summary Ca 2+ ‐dependent signalling processes are implicated in many aspects of flagella function in the green alga, Chlamydomonas. In this study, we examine the spatiotemporal dynamics of cytosolic Ca 2+ ([Ca 2+ ] cyt ) in single Chlamydomonas cells during the process of flagellar excision, using biolistically loaded calcium‐responsive dyes. Acid‐induced deflagellation occurred in parallel with a single transient elevation in whole‐cell [Ca 2+ ] cyt , which was absent in the acid deflagellation‐deficient adf1 mutant. Deflagellation could also be induced by elevated external Ca 2+ ([Ca 2+ ] ext ), which promoted very rapid spiking of [Ca 2+ ] cyt across the whole cell and in the flagella. We also detected very rapid apically localised Ca 2+ signalling events with an approximate duration of 500 msec. Ninety‐seven per cent of deflagellation events coincided with a rapid elevation in [Ca 2+ ] cyt in the apical region of the cell, either in the form of a whole cell or an apically localised increase, indicating that [Ca 2+ ] cyt elevations in the apical region play an underlying role in deflagellation. Our data indicate that elevated [Ca 2+ ] ext acts to disrupt Ca 2+ homeostasis which induces deflagellation by both Adf1‐dependent and Adf1‐independent mechanisms. Elevated [Ca 2+ ] ext also results in further [Ca 2+ ] cyt elevations after the main period of whole cell spiking which are very strongly associated with deflagellation, exhibit a high degree of apical localisation and are largely absent in the adf1 mutant. We propose that these later elevations may act as specific signals for deflagellation.