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

Govorunova, Elena G.; Voytsekh, Olga; Sineshchekov, Oleg A.

doi:10.1007/s00425-006-0357-2

Cited by 7 publications

(3 citation statements)

References 40 publications

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“…Peptone and tryptone are products of pancreatic digest of casein and are widely used as supplements to growth media for culti vation of microorganisms, including photosynthesis defi An early study [30] revealed that peptone attracts or repels, depending on the concentration, C. eugametos gametes. Similar data were also obtained for tryptone in C. reinhardtii [31]. Moreover, it has been established that vegetative cells of C. reinhardtii, unlike gametes, are insensitive to tryptone.…”

Section: Chemoreception and Signal Transductionsupporting

confidence: 78%

“…2, c and f). Correlation between the time courses and concentration dependencies of chemotaxis towards tryptone and the suppression of photoreceptor currents by this agent has been found [31]. The data show that gamete specific inhibition of photoreceptor currents by tryptone is due to the activation of the signaling cascade involved in chemotaxis towards this agent, and that initial steps of transduction of photic and chemical stimuli involve common elements (Fig.…”

Section: Chemoreception and Signal Transductionmentioning

confidence: 87%

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Chemotaxis in the Green Flagellate Alga Chlamydomonas

Govorunova

Sineshchekov

2005

Biochemistry (Moscow)

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Behavior of the green flagellate alga Chlamydomonas changes in response to a number of chemical stimuli. Specific sensitivity of the cells to different substances might appear only at certain stages of the life cycle. The heterogamous species C. allensworthii demonstrates chemotaxis of male gametes towards pheromones excreted by female gametes. In C. reinhardtii chemotaxis towards tryptone occurs only in gametes, whereas chemotaxis towards ammonium, on the contrary, only in vegetative cells. Chemotaxis to different chemical stimuli might involve different mechanisms of reception and signal transduction, elucidation of which has only recently begun. Indirect evidences show that the cells likely respond to tryptone with changes in the membrane electrical conductance. The recently completed project of sequencing the whole nuclear genome of C. reinhardtii provides the basis for future identification of molecular elements of the chemosensory cascade in this alga.

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Section: Chemoreception and Signal Transductionsupporting

confidence: 78%

Section: Chemoreception and Signal Transductionmentioning

confidence: 87%

Chemotaxis in the Green Flagellate Alga Chlamydomonas

Govorunova

Sineshchekov

2005

Biochemistry (Moscow)

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“…The light adaptation state of Chlamydomonas is also shifted towards an HL‐adapted state by increasing the cyclic AMP level with IBMX. Among other effects, IBMX induces expression of LHCSR3 , hyperphosphorylation of ChR1 in the dark, reduces the photoreceptor currents evoked by ChRs, and affects the phototactic sign and ciliary activity (Böhm et al, 2019; Boonyareth et al, 2009; Govorunova et al, 2007; Petroutsos et al, 2016; Saegusa & Yoshimura, 2015). The here observed long‐term reduction of the ChR1 starting levels by IBMX differs from its effect on LHCRS3 expression (Petroutsos et al, 2016) as it is not light‐dependent in wild‐type and ΔPHOT strains.…”

Section: Discussionmentioning

confidence: 99%

Multifactorial in vivo regulation of the photoreceptor channelrhodopsin‐1 abundance

Wolfram,

Greif,

Sizova

et al. 2023

Plant Cell & Environment

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Oriented movement (phototaxis) is an efficient way to optimize light‐driven processes and to avoid photodamage for motile algae. In Chlamydomonas the receptors for phototaxis are the channelrhodopsins ChR1 and ChR2. Both are directly light‐gated, plasma membrane‐localized cation channels. To optimally adjust its overall light‐dependent responses, Chlamydomonas must tightly control the ChRs cellular abundance and integrate their activities into its general photoprotective network. How this is achieved is largely unknown. Here we show that the ChR1 protein level decreases upon illumination in a light‐intensity and quality‐dependent manner, whereas it is stable in prolonged darkness. Analysis of knockout strains of six major photoreceptors absorbing in the blue–violet range, which is most effective in evoking ChR1 degradation, revealed that only phototropin (PHOT) is involved. Notably, ChR2 degradation was normal in a ΔPHOT strain. Further, our results indicate that a COP1‐SPA1 E3 ubiquitin ligase, the transcription factor Hy5 as well as changes in the cellular redox poise and cyclic nucleotide levels are additional components involved in this light acclimation response of Chlamydomonas. Our data highlight the presence of an adaptive framework connecting phototaxis with general photoprotective mechanisms via the use of overlapping signaling components already at the level of the primary photoreceptor.

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The green algal eyespot apparatus: a primordial visual system and more?

2008

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Most flagellate green algae exhibiting phototaxis posses a singular specialized light sensitive organelle, the eyespot apparatus (EA). Its design principles are similar in all green algae and produce, in conjunction with the movement pattern of the cell, a highly directional optical device. It enables an oriented movement response with respect to the direction and intensity of light. The functional EA involves local specializations of different compartments (plasma membrane, cytosol, and chloroplast) and utilizes specialized microbial-type rhodopsins, which act as directly light-gated ion channels. Due to their elaborate structures and the presence of retinal-based photoreceptors in some lineages, algal EAs are thought to play an important role in the evolution of photoreception and are thus not only of interest to plant biologists. In green algae considerable progress in the molecular dissection of components of this primordial visual system has been made by genetic and proteomic approaches in recent years. This review summarizes general aspects of the green algal EA as well as recent progress in the identification of proteins related to it. Further, novel data supporting a link between eyespot globules and plastoglobules will be presented and potential additional roles of the EA besides those in photoreception will be discussed.

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

Cited by 7 publications

References 40 publications

Chemotaxis in the Green Flagellate Alga Chlamydomonas

Chemotaxis in the Green Flagellate Alga Chlamydomonas

Multifactorial in vivo regulation of the photoreceptor channelrhodopsin‐1 abundance

The green algal eyespot apparatus: a primordial visual system and more?

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