Phototaxis of the dominant marine pico-eukaryote<i>Micromonas sp</i>.: from population to single cell

Henshaw, Richard J.; Jeanneret, Raphaël; Polin, Marco

doi:10.1101/740571

Cited by 2 publications

(2 citation statements)

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“…Recently, it was shown that aerotaxis (tracking of oxygen gradients) in choanoflagellates relies upon such a stochastic navigation strategy [ 21 ]. A similar mechanism operates during phototaxis in the pico-eukaryote Micromonas [ 22 ]. Many ciliates are capable of multiple gradient sensing strategies which may include a stochastic component, depending on the nature of the stimulus or irritant.…”

Section: Forms Of Excitability In Eukaryotesmentioning

confidence: 99%

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Origins of eukaryotic excitability

Wan

Jékely

2021

Phil. Trans. R. Soc. B

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All living cells interact dynamically with a constantly changing world. Eukaryotes, in particular, evolved radically new ways to sense and react to their environment. These advances enabled new and more complex forms of cellular behaviour in eukaryotes, including directional movement, active feeding, mating, and responses to predation. But what are the key events and innovations during eukaryogenesis that made all of this possible? Here we describe the ancestral repertoire of eukaryotic excitability and discuss five major cellular innovations that enabled its evolutionary origin. The innovations include a vastly expanded repertoire of ion channels, the emergence of cilia and pseudopodia, endomembranes as intracellular capacitors, a flexible plasma membrane and the relocation of chemiosmotic ATP synthesis to mitochondria, which liberated the plasma membrane for more complex electrical signalling involved in sensing and reacting. We conjecture that together with an increase in cell size, these new forms of excitability greatly amplified the degrees of freedom associated with cellular responses, allowing eukaryotes to vastly outperform prokaryotes in terms of both speed and accuracy. This comprehensive new perspective on the evolution of excitability enriches our view of eukaryogenesis and emphasizes behaviour and sensing as major contributors to the success of eukaryotes. This article is part of the theme issue ‘Basal cognition: conceptual tools and the view from the single cell’.

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Section: Forms Of Excitability In Eukaryotesmentioning

confidence: 99%

“…1 µm), and the motile species Micromonas (approx. 2 µm), which swims with an average speed of approximately 20 µm s −1 [ 22 ].…”

Section: Cellular and Biophysical Innovations Underpinning Eukaryoticmentioning

confidence: 99%

Origins of eukaryotic excitability

Wan

Jékely

2021

Phil. Trans. R. Soc. B

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Lateral gene transfer of anion-conducting channelrhodopsins between green algae and giant viruses

Rozenberg

Oppermann

Wietek

et al. 2020

Preprint

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Channelrhodopsins (ChRs) are algal light-gated ion channels widely used as optogenetic tools for manipulating neuronal activity 1,2 . Four ChR families are currently known. Green algal 3-5 and cryptophyte 6 cation-conducting ChRs (CCRs), cryptophyte anion-conducting ChRs (ACRs) 7 , and the MerMAID ChRs 8 . Here, we report the discovery of a new family of phylogenetically distinct ChRs encoded by marine giant viruses and acquired from their unicellular green algal prasinophyte hosts. These previously unknown viral and green algal ChRs act as ACRs when expressed in cultured neuroblastoma-derived cells and are likely involved in behavioral responses to light. MAINChannelrhodopsins (ChRs) are microbial rhodopsins that directly translate absorbed light into ion fluxes along electrochemical gradients across cellular membranes controlling behavioural light responses in motile algae 9 . They are widely used in optogenetics to manipulate cellular activity using light 10 , and therefore a constant demand for new types of ChRs with different functions, be it different absorption spectra 11 , ion selectivity 12 , or kinetics 11 . So far, ChRs have only been reported from cultured representatives of two groups of algae: cryptophytes and green algae 2,13 . Recently, metagenomics proved to be a useful tool to identify novel ChRs, as a new family of anion-conducting ChRs (ACRs) with intensely desensitizing photocurrents were detected in uncultured and yet to be identified marine microorganisms 8 . Channelrhodopsins in metagenomic contigs of putative viral origin.To extend the search for uncharacterized distinct ChRs with potentially new functions, we further screened various metagenomic datasets from Tara Oceans 14-16 . In total, four unique ChR sequences were found in five metagenomic contigs from tropical and temperate waters of the Atlantic and Pacific Oceans. Two of the contigs were long enough (SAMEA2620979_21821, 11 kb and SAMEA2623079_2164382, 20 kb) to provide sufficient genomic context (Fig. 1a). We attempted to search for similar sequences in several metagenomic datasets, and located multiple contigs with synteny to the two longer ChR-containing contigs (Fig. 1a, Suppl. File 1). These two longer contigs recruited two clusters of related fragments (v21821 and v2164382 contig clusters) mostly from marine samples of Tara Oceans. Interestingly, the v21821-cluster contigs came from the same South Atlantic station as SAMEA2620979_21821 itself, except for one contig with lower identity and synteny length from a soda lake metagenome 17 (LFCJ01000229.1, see Fig.

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Phototaxis of the dominant marine pico-eukaryoteMicromonas sp.: from population to single cell

Cited by 2 publications

References 68 publications

Origins of eukaryotic excitability

Origins of eukaryotic excitability

Lateral gene transfer of anion-conducting channelrhodopsins between green algae and giant viruses

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