The mating reaction of Chlamydomonas reinhardtii entails a rapid series of cell-cell interactions leading to cell fusion. We have demonstrated (Pasquale, S. M., and U. Goodenough. 1987. J. Cell Biol. 105:2279-2293) that cAMP plays a key role in this process: gametic flagellar adhesion elicits a sharp increase in intracellular cAMP, and presentation of dibutyryl-cAMP to unmated gametes elicits all known mating responses. The present study evaluates the role of Ca2+ in this system. We document that the mating-induced increase in cAMP, and hence the mating responses themselves, are blocked by a variety of drugs known to interfere with Ca(2+)-sensitive processes. These data suggest that Ca(2+)-mediated events may couple adhesion to the generation of cAMP. Such events, however, appear to be localized to the flagellar membrane; we find no evidence for the mating-related increase in cytosolic free Ca2+ that has been postulated by others. Indeed, by monitoring the length of the Ca(2+)-sensitive centrin-containing nucleus-basal body connector, we show that cytosolic free Ca2+ levels, if anything, decrease in response to cAMP signaling. We confirm a previous report that Ca2+ levels increase in the mating medium, but document that this represents a response to augmented cAMP levels and not a prelude. Finally, we show that IP3 levels remain constant throughout the mating reaction. These results are discussed in terms of the various signal transduction systems that have now been identified in Chlamydomonas.
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April 15 1993
The role of calcium in the Chlamydomonas reinhardtii mating reaction.
U W Goodenough
,
U W Goodenough
Department of Biology, Washington University, St. Louis, Missouri 63130.
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B Shames
,
B Shames
Department of Biology, Washington University, St. Louis, Missouri 63130.
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L Small
,
L Small
Department of Biology, Washington University, St. Louis, Missouri 63130.
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T Saito
,
T Saito
Department of Biology, Washington University, St. Louis, Missouri 63130.
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R C Crain
,
R C Crain
Department of Biology, Washington University, St. Louis, Missouri 63130.
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M A Sanders
,
M A Sanders
Department of Biology, Washington University, St. Louis, Missouri 63130.
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J L Salisbury
J L Salisbury
Department of Biology, Washington University, St. Louis, Missouri 63130.
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U W Goodenough
Department of Biology, Washington University, St. Louis, Missouri 63130.
B Shames
Department of Biology, Washington University, St. Louis, Missouri 63130.
L Small
Department of Biology, Washington University, St. Louis, Missouri 63130.
T Saito
Department of Biology, Washington University, St. Louis, Missouri 63130.
R C Crain
Department of Biology, Washington University, St. Louis, Missouri 63130.
M A Sanders
Department of Biology, Washington University, St. Louis, Missouri 63130.
J L Salisbury
Department of Biology, Washington University, St. Louis, Missouri 63130.
Online Issn: 1540-8140
Print Issn: 0021-9525
J Cell Biol (1993) 121 (2): 365–374.
Citation
U W Goodenough, B Shames, L Small, T Saito, R C Crain, M A Sanders, J L Salisbury; The role of calcium in the Chlamydomonas reinhardtii mating reaction.. J Cell Biol 15 April 1993; 121 (2): 365–374. doi: https://doi.org/10.1083/jcb.121.2.365
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