Isolation and Characterisation of Chemotactic Mutants of Chlamydomonas reinhardtii obtained by Insertional Mutagenesis

Ermilova, Elena; Zalutskaya, Zhanneta; Gromov, B.V.; Häder, Donat-Peter; Purton, Saul

doi:10.1078/1434-4610-00013

Cited by 13 publications

(11 citation statements)

References 31 publications

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“…The degree of the tryptone-induced inhibition of PC in gametes of all seven wild-type strains was smaller than that in gametes of 495 mt+ strain, but the average degree of inhibition in the newly tested mt+ strains was not significantly different from that in the mt-strains (Table 1). Two adf1 deflagellation-deficient mutants (Quarmby and Hartzell 1994) were also included in this analysis, because it has been reported that such mutants lack chemotaxis to sugars (Ermilova et al 2000). The sensitivity of adf1 mutants to tryptone was close to that of the parent strains g1 mt+ and B214 mt-( Table 1).…”

Section: Resultsmentioning

confidence: 98%

Changes in photoreceptor currents and their sensitivity to the chemoeffector tryptone during gamete mating in Chlamydomonas reinhardtii

Govorunova

Voytsekh

Sineshchekov

2006

Planta

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Chlamydomonas reinhardtii Dangeard generates photoreceptor currents (PCs) upon light excitation. These currents play a key role in the signal transduction chain for photomotility responses. We have previously found that inhibition of PCs by tryptone occurs only in gametes that display chemotaxis toward this agent, and is not observed in chemotactically insensitive vegetative cells. Here we show that the sensitivity to tryptone is characteristic of gametes of both mating types, and examine the influence of gamete mating on PCs and their sensitivity to tryptone. The amplitude of PCs increases after cell fusion, but the sensitivity of these currents to tryptone decreases upon flagellar adhesion and/or an increase in the intracellular cAMP concentration. Net chemotaxis toward tryptone is reduced in young zygotes compared to gametes. We conclude that gamete mating leads to rapid inactivation of a gamete-specific chemosensory system.

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Section: Resultsmentioning

confidence: 98%

Changes in photoreceptor currents and their sensitivity to the chemoeffector tryptone during gamete mating in Chlamydomonas reinhardtii

Govorunova

Voytsekh

Sineshchekov

2006

Planta

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“…The allometry of the adaptation time is therefore a key feature for study. It is also of considerable interest to ascertain the dynamics of chemotaxis in Volvox and to determine its relationship to phototaxis, a linkage proposed for Chlamydomonas (36). Whereas larger multicellular organisms like Volvox can rely on an entirely deterministic mechanism for phototaxis, it remains unclear how stochasticity of motion in unicellular organisms like Chlamydomonas, caused by internal biochemical noise (37), affects phototaxis.…”

Section: Resultsmentioning

confidence: 99%

Fidelity of adaptive phototaxis

Drescher

Goldstein

Tuval

2010

Proc. Natl. Acad. Sci. U.S.A.

141

145

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Along the evolutionary path from single cells to multicellular organisms with a central nervous system are species of intermediate complexity that move in ways suggesting high-level coordination, yet have none. Instead, organisms of this type possess many autonomous cells endowed with programs that have evolved to achieve concerted responses to environmental stimuli. Here experiment and theory are used to develop a quantitative understanding of how cells of such organisms coordinate to achieve phototaxis, by using the colonial alga Volvox carteri as a model. It is shown that the surface somatic cells act as individuals but are orchestrated by their relative position in the spherical extracellular matrix and their common photoresponse function to achieve colony-level coordination. Analysis of models that range from the minimal to the biologically faithful shows that, because the flagellar beating displays an adaptive down-regulation in response to light, the colony needs to spin around its swimming direction and that the response kinetics and natural spinning frequency of the colony appear to be mutually tuned to give the maximum photoresponse. These models further predict that the phototactic ability decreases dramatically when the colony does not spin at its natural frequency, a result confirmed by phototaxis assays in which colony rotation was slowed by increasing the fluid viscosity.adaptation | evolution | flagella | fluid dynamics | multicellularity

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“…In C. reinhardtii, vegetative cells, pre-gametes (generated by incubation of vegetative cells without a nitrogen source in the dark) and mature gametes are motile. Chlamydomonas vegetative cells are attracted to some sugars and to the preferred nitrogen source, ammonium (Sjoblad and Frederikse 1981;Ermilova et al 1993Ermilova et al , 1998Ermilova et al , 2000. Mature gametes, however, do not exhibit chemotaxis in response to ammonium.…”

Section: Introductionmentioning

confidence: 97%

Phototropin plays a crucial role in controlling changes in chemotaxis during the initial phase of the sexual life cycle in Chlamydomonas

Ermilova

Zalutskaya

Huang

et al. 2004

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During sexual differentiation, Chlamydomonas reinhardtii changes its chemotactic behavior in response to ammonium. Just like gamete formation, the change in chemotaxis mode is controlled by the sequential action of two environmental cues, removal of ammonium or nitrate from the medium and light. Thus, vegetative cells and mating incompetent pre-gametes, the latter being generated by nitrogen starvation in the dark, exhibit chemotaxis towards ammonium. Irradiation of pre-gametes results in a loss of chemotaxis and the gaining of mating competence. Incubation of these gametes in the dark resulted in their regaining chemotactic activity; re-illumination again resulted in its loss. Blue light was shown to be most effective in switching-off chemotaxis. RNA-interference strains with reduced levels of the blue-light receptor phototropin showed an attenuated inactivation of chemotaxis that could be partially compensated by the application of higher fluence rates, suggesting that these light responses are mediated by phototropin. The sharing of photoreceptor and signal transduction components as well as similar temporal patterns observed for changes in chemotaxis towards ammonium and gametic differentiation suggest an integration of the signaling pathways that control these two responses.

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Isolation and Characterisation of Chemotactic Mutants of Chlamydomonas reinhardtii obtained by Insertional Mutagenesis

Cited by 13 publications

References 31 publications

Changes in photoreceptor currents and their sensitivity to the chemoeffector tryptone during gamete mating in Chlamydomonas reinhardtii

Changes in photoreceptor currents and their sensitivity to the chemoeffector tryptone during gamete mating in Chlamydomonas reinhardtii

Fidelity of adaptive phototaxis

Phototropin plays a crucial role in controlling changes in chemotaxis during the initial phase of the sexual life cycle in Chlamydomonas

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