Planta

, Volume 231, Issue 5, pp 1229–1236 | Cite as

Molecular characterization of a calmodulin involved in the signal transduction chain of gravitaxis in Euglena gracilis

  • Viktor Daiker
  • Michael Lebert
  • Peter Richter
  • Donat-Peter Häder
Original Article

Abstract

The unicellular flagellate Euglena gracilis shows a negative gravitactic behavior. This is based on physiological mechanisms which in the past have been indirectly assessed. Meanwhile, it was possible to isolate genes involved in the signal transduction chain of gravitaxis. The DNA sequences of five calmodulins were found in Euglena, one of which was only known in its protein structure (CaM.1); the other four are new. The biosynthesis of the corresponding proteins of CaM.1–CaM.5 was inhibited by means of RNA interference to determine their involvement in the gravitactic signal transduction chain. RNAi of CaM.1 inhibits free swimming of the cells and pronounced cell-form aberrations. The division of cells was also hampered. After recovery from RNAi the cell showed precise negative gravitaxis again. Blockage of CaM.3 to CaM. 5 did not impair gravitaxis. In contrast, the blockage of CaM.2 has only a transient and not pronounced influence on motility and cell form, but leads to a total loss of gravitactic orientation for more than 30 days. This indicates that CaM.2 is an element in the signal transduction chain of gravitaxis in E. gracilis. The results are discussed with regard to the current working model of gravitaxis in E. gracilis.

Keywords

Calmodulin Euglena Gravitaxis RNA interference 

Abbreviations

CaM

Calmodulin (identified in the course of this study)

RACE

Rapid amplification of cDNA ends

RNAi

RNA interference

Notes

Acknowledgments

This work was financially supported by DLR (50 WB 0154). The skilful support of Jenifer Tebart and Roland Richter is gratefully acknowledged.

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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Viktor Daiker
    • 1
  • Michael Lebert
    • 1
  • Peter Richter
    • 1
  • Donat-Peter Häder
    • 1
  1. 1.Department of Biology, Plant EcophysiologyFriedrich-Alexander UniversityErlangenGermany

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