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Article ; Online: Diffusional Interactions among Marine Phytoplankton and Bacterioplankton

Naaman M. Omar / Ondřej Prášil / J. Scott P. McCain / Douglas A. Campbell

Microorganisms, Vol 10, Iss 4, p

Modelling H 2 O 2 as a Case Study

2022 Volume 821

Abstract: Marine phytoplankton vary widely in size across taxa, and in cell suspension densities across habitats and growth states. Cell suspension density and total biovolume determine the bulk influence of a phytoplankton community upon its environment. Cell ... ...

Abstract	Marine phytoplankton vary widely in size across taxa, and in cell suspension densities across habitats and growth states. Cell suspension density and total biovolume determine the bulk influence of a phytoplankton community upon its environment. Cell suspension density also determines the intercellular spacings separating phytoplankton cells from each other, or from co-occurring bacterioplankton. Intercellular spacing then determines the mean diffusion paths for exchanges of solutes among co-occurring cells. Marine phytoplankton and bacterioplankton both produce and scavenge reactive oxygen species (ROS), to maintain intracellular ROS homeostasis to support their cellular processes, while limiting damaging reactions. Among ROS, hydrogen peroxide (H 2 O 2 ) has relatively low reactivity, long intracellular and extracellular lifetimes, and readily crosses cell membranes. Our objective was to quantify how cells can influence other cells via diffusional interactions, using H 2 O 2 as a case study. To visualize and constrain potentials for cell-to-cell exchanges of H 2 O 2 , we simulated the decrease of [H 2 O 2 ] outwards from representative phytoplankton taxa maintaining internal [H 2 O 2 ] above representative seawater [H 2 O 2 ]. [H 2 O 2 ] gradients outwards from static cell surfaces were dominated by volumetric dilution, with only a negligible influence from decay. The simulated [H 2 O 2 ] fell to background [H 2 O 2 ] within ~3.1 µm from a Prochlorococcus cell surface, but extended outwards 90 µm from a diatom cell surface. More rapid decays of other, less stable ROS, would lower these threshold distances. Bacterioplankton lowered simulated local [H 2 O 2 ] below background only out to 1. 2 µm from the surface of a static cell, even though bacterioplankton collectively act to influence seawater ROS. These small diffusional spheres around cells mean that direct cell-to-cell exchange of H 2 O 2 is unlikely in oligotrophic habits with widely spaced, small cells; moderate in eutrophic habits with shorter ...
Keywords	diffusional interactions ; hydrogen peroxide ; phytoplankton ; bacterioplankton ; Biology (General) ; QH301-705.5
Subject code	290
Language	English
Publishing date	2022-04-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Author Correction

Takako Masuda / Keisuke Inomura / Naoto Takahata / Takuhei Shiozaki / Yuji Sano / Curtis Deutsch / Ondřej Prášil / Ken Furuya

Communications Biology, Vol 6, Iss 1, Pp 1-

Heterogeneous nitrogen fixation rates confer energetic advantage and expanded ecological niche of unicellular diazotroph populations

2023 Volume 1

Keywords	Biology (General) ; QH301-705.5
Language	English
Publishing date	2023-06-01T00:00:00Z
Publisher	Nature Portfolio
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Life at elevated CO₂ modifies the cell composition of Chromera velia (Chromerida)

Venuleo, Marianna / Ondřej Práŝil / Mario Giordano

European journal of phycology. 2018 Jan. 2, v. 53, no. 1

2018

Abstract: We investigated the response to high CO₂ of Chromera velia, a photosynthetic relative of apicomplexan parasites that is possibly involved in symbiotic associations with scleractinian corals. The inorganic C content in the proximity of the symbiotic algal ...

Abstract	We investigated the response to high CO₂ of Chromera velia, a photosynthetic relative of apicomplexan parasites that is possibly involved in symbiotic associations with scleractinian corals. The inorganic C content in the proximity of the symbiotic algal cells within the tissues of scleractinians is disputed. According to some authors, it is very high. A higher C content in the endodermal tissues of scleractinians than in the external environment may have favoured the constitution of symbiosis with organisms such as Symbiodinium and Chromera that have a type II Rubisco, which is intrinsically ill suited to low CO₂ environments. We thus cultured C. velia at the very high inorganic C estimated by some authors and assessed its growth and photosynthetic performance. We also evaluated whether these conditions affected C allocation and elemental stoichiometry in C. velia cells by state-of-the-art Fourier transform infrared spectroscopy and total reflection X-ray fluorescence spectrometry in combination with more traditional biochemical and physiological techniques. Our results demonstrated that C. velia was capable of coping with very high CO₂, which even stimulated biomass production and increased N, P, Mn, Fe and Zn use efficiency. Growth at elevated CO₂ changed the stoichiometric relationships among elements in C. velia cells, but had no effect on the relative abundance of the main organic pools. The high CO₂ in the animal tissue surrounding the photosynthetic cells may therefore facilitate C. velia life in symbiosis.
Keywords	Fourier transform infrared spectroscopy ; Scleractinia ; Symbiodinium ; X-ray fluorescence spectroscopy ; algae ; biomass production ; carbon dioxide ; carbon dioxide enrichment ; iron ; manganese ; nutrient use efficiency ; photosynthesis ; ribulose-bisphosphate carboxylase ; stoichiometry ; symbiosis ; tissues
Language	English
Dates of publication	2018-0102
Size	p. 58-66.
Publishing place	Taylor & Francis
Document type	Article
ZDB-ID	1481147-9
ISSN	1469-4433 ; 0967-0262
ISSN (online)	1469-4433
ISSN	0967-0262
DOI	10.1080/09670262.2017.1376255
Database	NAL-Catalogue (AGRICOLA)

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Article: The phycobilisomes of Synechococcus sp. are constructed to minimize nitrogen use in nitrogen-limited cells and to maximize energy capture in energy-limited cells

Ruan, Zuoxi / Mario Giordano / Ondřej Prášil

Environmental and experimental botany. 2018 June, v. 150

2018

Abstract: Synechococcus sp. UTEX LB2380 is a coastal strain of a cosmopolitan cyanobacterial genus. In coastal waters, N and light availability are highly variable and their interplay may influence C allocation and photosynthetic performance. In this paper, we ... ...

Abstract	Synechococcus sp. UTEX LB2380 is a coastal strain of a cosmopolitan cyanobacterial genus. In coastal waters, N and light availability are highly variable and their interplay may influence C allocation and photosynthetic performance. In this paper, we compared the impact of nitrogen (N) limitation and energy (light, E) limitation on phycobilisome composition and photosynthesis, in the presence of either NO3− or NH4+. Our hypothesis was that the phycobilisome composition would be influenced by the factor limiting growth. Our results show that N-limited cells adjusted their phycobilisome antenna to minimize N utilization, whereas E-limited cells had a phycobilisome composition tailored to alleviate E deficiency. The N-source was relevant for the pigment composition, under both limitations. When N limited growth, excess energy management may become important to decrease the risk of photoinhibition and oxidative stress; when the sink of electrons constituted by NO3− reduction was not present, the cells tended to decrease their phycobiliprotein content, possibly in order to minimize the size of PSII antennas and decrease excitation. When energy was limiting, the energy saved for N assimilation in NH4+-grown cells was invested in antenna pigments to allow for a higher energy input.
Keywords	ammonium ; coastal water ; electrons ; energy ; nitrates ; nitrogen ; oxidative stress ; photoinhibition ; phycobiliprotein ; risk ; Synechococcus
Language	English
Dates of publication	2018-06
Size	p. 152-160.
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	195968-2
ISSN	0098-8472
ISSN	0098-8472
DOI	10.1016/j.envexpbot.2018.01.015
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Impact of Increased Nutrients and Lowered pH on Photosynthesis and Growth of Three Marine Phytoplankton Communities From the Coastal South West Atlantic (Patagonia, Argentina)

Takako Masuda / Ondřej Prášil / Virginia E. Villafañe / Macarena S. Valiñas / Keisuke Inomura / E. Walter Helbling

Frontiers in Marine Science, Vol

2021 Volume 8

Abstract: Effect of global change variables on the structure and photosynthesis of phytoplankton communities was evaluated in three different sites of the Patagonian coast of Argentina: enclosed bay (Puerto Madryn, PM), estuarine (Playa Unión, PU), and open waters ...

Abstract	Effect of global change variables on the structure and photosynthesis of phytoplankton communities was evaluated in three different sites of the Patagonian coast of Argentina: enclosed bay (Puerto Madryn, PM), estuarine (Playa Unión, PU), and open waters (Isla Escondida, IE). We exposed samples to two contrasting scenarios: Present (nutrients at in situ levels) vs. Future (with lowered pH and higher nutrients inputs), and determined growth and photosynthetic responses after 2 days of acclimation. Under the Future condition phytoplankton growth was higher in the estuarine site compared to those in PM and IE. This effect was the most pronounced on large diatoms. While the increase of photosynthetic activity was not always observed in the Future scenario, the lower photosynthetic electron requirement for carbon fixation (Φe,C = ETR/PmB) in this scenario compared to the Present, suggests a more effective energy utilization. Long-term experiments were also conducted to assess the responses along a 4 days acclimation period in PU. Diatoms benefited from the Future conditions and had significantly higher growth rates than in the Present. In addition, Φe,C was lower after the acclimation period in the Future scenario, compared to the Present. Our results suggest that the availability, frequency and amount of nutrients play a key role when evaluating the effects of global change on natural phytoplankton communities. The observed changes in diatom growth under the Future scenario in PU and IE and photosynthesis may have implications in the local trophodynamics by bottom up control.
Keywords	global change ; plankton community structure ; carbon incorporation ; oxygen production ; PSII photochemistry ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
Subject code	333
Language	English
Publishing date	2021-02-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: On the origin of the slow M–T chlorophyll a fluorescence decline in cyanobacteria: interplay of short-term light-responses

Bernát, Gábor / Gábor Steinbach / Radek Kaňa / Govindjee / Amarendra N. Misra / Ondřej Prašil

Photosynthesis research. 2018 May, v. 136, no. 2

2018

Abstract: The slow kinetic phases of the chlorophyll a fluorescence transient (induction) are valuable tools in studying dynamic regulation of light harvesting, light energy distribution between photosystems, and heat dissipation in photosynthetic organisms. ... ...

Abstract	The slow kinetic phases of the chlorophyll a fluorescence transient (induction) are valuable tools in studying dynamic regulation of light harvesting, light energy distribution between photosystems, and heat dissipation in photosynthetic organisms. However, the origin of these phases are not yet fully understood. This is especially true in the case of prokaryotic oxygenic photoautotrophs, the cyanobacteria. To understand the origin of the slowest (tens of minutes) kinetic phase, the M–T fluorescence decline, in the context of light acclimation of these globally important microorganisms, we have compared spectrally resolved fluorescence induction data from the wild type Synechocystis sp. PCC 6803 cells, using orange (λ = 593 nm) actinic light, with those of mutants, ΔapcD and ΔOCP, that are unable to perform either state transition or fluorescence quenching by orange carotenoid protein (OCP), respectively. Our results suggest a multiple origin of the M–T decline and reveal a complex interplay of various known regulatory processes in maintaining the redox homeostasis of a cyanobacterial cell. In addition, they lead us to suggest that a new type of regulatory process, operating on the timescale of minutes to hours, is involved in dissipating excess light energy in cyanobacteria.
Keywords	Synechocystis sp. PCC 6803 ; acclimation ; autotrophs ; carotenoids ; chlorophyll ; decline ; energy ; fluorescence ; heat ; homeostasis ; microorganisms ; mutants
Language	English
Dates of publication	2018-05
Size	p. 183-198.
Publishing place	Springer Netherlands
Document type	Article
ZDB-ID	1475688-2
ISSN	1573-5079 ; 0166-8595
ISSN (online)	1573-5079
ISSN	0166-8595
DOI	10.1007/s11120-017-0458-8
Database	NAL-Catalogue (AGRICOLA)

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Article: High light acclimation of Chromera velia points to photoprotective NPQ

Belgio, Erica / Eliška Trsková / Eva Kotabová / Daniela Ewe / Ondřej Prášil / Radek Kaňa

Photosynthesis research. 2018 Mar., v. 135, no. 1-3

2018

Abstract: It has previously been shown that the long-term treatment of Arabidopsis thaliana with the chloroplast inhibitor lincomycin leads to photosynthetic membranes enriched in antennas, strongly reduced in photosystem II reaction centers (PSII) and with ... ...

Abstract	It has previously been shown that the long-term treatment of Arabidopsis thaliana with the chloroplast inhibitor lincomycin leads to photosynthetic membranes enriched in antennas, strongly reduced in photosystem II reaction centers (PSII) and with enhanced nonphotochemical quenching (NPQ) (Belgio et al. Biophys J 102:2761–2771, 2012). Here, a similar physiological response was found in the microalga Chromera velia grown under high light (HL). In comparison to cells acclimated to low light, HL cells displayed a severe re-organization of the photosynthetic membrane characterized by (1) a reduction of PSII but similar antenna content; (2) partial uncoupling of antennas from PSII; (3) enhanced NPQ. The decrease in the number of PSII represents a rather unusual acclimation response compared to other phototrophs, where a smaller PSII antenna size is more commonly found under high light. Despite the diminished PSII content, no net damage could be detected on the basis of the Photosynthesis versus irradiance curve and electron transport rates pointing at the excess capacity of PSII. We therefore concluded that the photoinhibition is minimized under high light by a lower PSII content and that cells are protected by NPQ in the antennas.
Keywords	Arabidopsis thaliana ; acclimation ; autotrophs ; chloroplasts ; electron transfer ; light harvesting complex ; light intensity ; lincomycin ; microalgae ; photoinhibition ; photosystem II ; physiological response
Language	English
Dates of publication	2018-03
Size	p. 263-274.
Publishing place	Springer Netherlands
Document type	Article
ZDB-ID	1475688-2
ISSN	1573-5079 ; 0166-8595
ISSN (online)	1573-5079
ISSN	0166-8595
DOI	10.1007/s11120-017-0385-8
Database	NAL-Catalogue (AGRICOLA)

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Article: Effect of CO2 enrichment on phytoplankton photosynthesis in the North Atlantic sub-tropical gyre

Tilstone, Gavin / Barbora Šedivá / Glen Tarran / Ondřej Prášil / Radek Kaňa

Progress in oceanography. 2017 Nov., v. 158

2017

Abstract: The effects of changes in CO2 concentration in seawater on phytoplankton community structure and photosynthesis were studied in the North Atlantic sub-tropical gyre. Three shipboard incubations were conducted for 48h at ∼760ppm CO2 and control (360ppm ... ...

Abstract	The effects of changes in CO2 concentration in seawater on phytoplankton community structure and photosynthesis were studied in the North Atlantic sub-tropical gyre. Three shipboard incubations were conducted for 48h at ∼760ppm CO2 and control (360ppm CO2) from 49°N to 7°N during October and November 2010. Elevated CO2 caused a decrease in pH to ∼7.94 compared to ∼8.27 in the control. During one experiment, the biomass of nano- and picoeukaryotes increased under CO2 enrichment, but primary production decreased relative to the control. In two of the experiments the biomass was dominated by dinoflagellates, and there was a significant increase in the maximum photosynthetic rate (PmB) and light-limited slope of photosynthesis (αB) at CO2 concentrations of 760ppm relative to the controls. 77K emission spectroscopy showed that the higher photosynthetic rates measured under CO2 enrichment increased the connection of reversible photosystem antennae, which resulted in an increase in light harvesting efficiency and carbon fixation.
Keywords	biomass ; carbon dioxide ; carbon dioxide enrichment ; carbon dioxide fixation ; community structure ; Miozoa ; pH ; photosynthesis ; phytoplankton ; primary productivity ; seawater ; spectroscopy
Language	English
Dates of publication	2017-11
Size	p. 76-89.
Publishing place	Elsevier Ltd
Document type	Article
ISSN	0079-6611
DOI	10.1016/j.pocean.2016.12.005
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Non-photochemical quenching in cryptophyte alga Rhodomonas salina is located in chlorophyll a/c antennae.

Radek Kaňa / Eva Kotabová / Roman Sobotka / Ondřej Prášil

PLoS ONE, Vol 7, Iss 1, p e

2012 Volume 29700

Abstract: Photosynthesis uses light as a source of energy but its excess can result in production of harmful oxygen radicals. To avoid any resulting damage, phototrophic organisms can employ a process known as non-photochemical quenching (NPQ), where excess light ... ...

Abstract	Photosynthesis uses light as a source of energy but its excess can result in production of harmful oxygen radicals. To avoid any resulting damage, phototrophic organisms can employ a process known as non-photochemical quenching (NPQ), where excess light energy is safely dissipated as heat. The mechanism(s) of NPQ vary among different phototrophs. Here, we describe a new type of NPQ in the organism Rhodomonas salina, an alga belonging to the cryptophytes, part of the chromalveolate supergroup. Cryptophytes are exceptional among photosynthetic chromalveolates as they use both chlorophyll a/c proteins and phycobiliproteins for light harvesting. All our data demonstrates that NPQ in cryptophytes differs significantly from other chromalveolates - e.g. diatoms and it is also unique in comparison to NPQ in green algae and in higher plants: (1) there is no light induced xanthophyll cycle; (2) NPQ resembles the fast and flexible energetic quenching (qE) of higher plants, including its fast recovery; (3) a direct antennae protonation is involved in NPQ, similar to that found in higher plants. Further, fluorescence spectroscopy and biochemical characterization of isolated photosynthetic complexes suggest that NPQ in R. salina occurs in the chlorophyll a/c antennae but not in phycobiliproteins. All these results demonstrate that NPQ in cryptophytes represents a novel class of effective and flexible non-photochemical quenching.
Keywords	Medicine ; R ; Science ; Q
Subject code	580
Language	English
Publishing date	2012-01-01T00:00:00Z
Publisher	Public Library of Science (PLoS)
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Fast reactivation of photosynthesis in arctic phytoplankton during the polar night1

Kvernvik, Ane Cecilie / Clara Jule Marie Hoppe / Eva Leu / Evelyn Lawrenz / Józef Maria Wiktor / Michael Greenacre / Ondřej Prášil

Journal of phycology. 2018 Aug., v. 54, no. 4

2018

Abstract: Arctic microalgae experience long periods of continuous darkness during the polar night, when they are unable to photosynthesize. Despite numerous studies on overwintering strategies, such as utilization of stored energy products, formation of resting ... ...

Abstract	Arctic microalgae experience long periods of continuous darkness during the polar night, when they are unable to photosynthesize. Despite numerous studies on overwintering strategies, such as utilization of stored energy products, formation of resting stages, reduction of metabolic rates and heterotrophic lifestyles, there have been few attempts to assess the in situ physiological state and restoration of the photosynthetic apparatus upon re‐illumination. In this study, we found diverse and active marine phytoplankton communities during the polar night at 78°N. Furthermore, we observed rapid changes (≤20 min) in the efficiency of photosynthetic electron transport upon re‐illumination. High photosynthetic capacity and net primary production were established after 24 h of re‐illumination. Our results suggest that some Arctic autotrophs maintain fully functional photosystem II and downstream electron acceptors during the polar night even though the low in situ net primary production levels measured in January prove that light was not sufficient to support any measurable primary production. Due to low temperatures resulting in low respiratory rates as well as the absence of photodamage during the polar night, maintenance of basic photosynthetic machinery may actually pose relatively low metabolic costs for algal cells. This could allow Arctic microalgae to endure the polar night without the formation of dormant stages, enabling them to recover and take advantage of light immediately upon the suns return during the winter–spring transition.
Keywords	autotrophs ; energy ; heterotrophs ; microalgae ; net primary productivity ; overwintering ; photosynthetic electron transport ; photosystem II ; physiological state ; phytoplankton ; respiratory rate ; temperature ; Arctic region
Language	English
Dates of publication	2018-08
Size	p. 461-470.
Publishing place	John Wiley & Sons, Ltd
Document type	Article
Note	JOURNAL ARTICLE
ZDB-ID	281226-5
ISSN	1529-8817 ; 0022-3646
ISSN (online)	1529-8817
ISSN	0022-3646
DOI	10.1111/jpy.12750
Database	NAL-Catalogue (AGRICOLA)

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