Control of flagellar motion in Chlamydomonas and Euglena by mechanical microinjection of Mg2+ and Ca2+ and by electric current injection

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Abstract
Upon impalement with a microelectrode in a Caa+-free medium containing 5 mM ATP, a Chlamydomonas cell lost its flagellar activity within 45 s, and the injection of either positive or negative direct current did not stimulate the flagella to beat after that time. When 3 mM Mg2+was added to the external medium, the impaled cell exhibited a flagellar frequency of 22 ± 7 Hz. With 5 mM ATP and 3 mM Mg2+ in a Ca2+-free medium, negative direct electric current inhibited flagellar frequency and positive direct electric current enhanced flagellar activity. The flagella recovered to approximately their characteristic frequency (20 ± 6 Hz) upon the cessation of current. Euglena and Chlamydomonas cells were mechanically microinjected with Ca2+ or Mg2+ ions contained in 1·0 M KCl-filled microelectrodes. In both cells, the injection of 0·02 M Ca2+ resulted in a decrease in flagellar frequency dependent on the amount of Ca2+ injected. The frequency decreased to zero Hz upon the injection of 16 × 10−14 1. in Euglena and 3·5× 10−141. in Chlamydomonas. The microinjection of 10 × 10−14 1. of o·2 M Mg2+ into Euglena cells resulted in an approximately 2-fold increase in flagellar frequency. Chlamydomonas flagella, which stop beating upon impalement in a Mg2+-free medium, began to beat when the cell was injected with Mg2+ ions. The flagella exhibited an average frequency of 16 ± 3 Hz when injected with 1·5 × 10−141. of 0·2 M Mg2+. The data indicate that an increase in internal Mg2+stimulates flagellar frequency. The microinjection of Ca2+ inhibits flagellar motility.