scholarly journals Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank

2021 ◽  
Vol 8 ◽  
Author(s):  
Kazuhiro Yoshida ◽  
Andreas Seger ◽  
Matthew Corkill ◽  
Petra Heil ◽  
Kristen Karsh ◽  
...  
Keyword(s):  
Sea Ice ◽  
High Light ◽  
Freezing Stress ◽  
Ex Situ ◽  
Ice Algae ◽  
Light Conditions ◽  
Low Light ◽  
Ice Melt ◽  
Sea Ice Algae ◽  
Fragilariopsis Cylindrus

Sea-ice algae play a crucial role in the ecology and biogeochemistry of sea-ice zones. They not only comprise the base of sea-ice ecosystems, but also seed populations of extensive ice-edge blooms during ice melt. Ice algae must rapidly acclimate to dynamic light environments, from the low light under sea ice to high light within open waters. Recently, iron (Fe) deficiency has been reported for diatoms in eastern Antarctic pack ice. Low Fe availability reduces photosynthetic plasticity, leading to reduced ice-algal primary production. We developed a low-Fe ice tank to manipulate Fe availability in sea ice. Over 20 days in the ice tank, the Antarctic ice diatom Fragilariopsis cylindrus was incubated in artificial low-Fe sea ice ([total Fe] = 20 nM) in high light (HL) and low light (LL) conditions. Melted ice was also exposed to intense light to simulate light conditions typical for melting ice in situ. When diatoms were frozen in, the maximum photochemical quantum efficiency of photosystem II (PSII), Fv/Fm, was suppressed by freezing stress. However, the diatoms maintained photosynthetic capability throughout the ice periods with a stable Fv/Fm value and increased photoprotection through non-photochemical quenching (NPQ) via photoprotective xanthophyll cycling (XC) and increased photoprotective carotenoid levels compared to pre-freeze-up. Photoprotection was more pronounced in the HL treatment due to greater light stress. However, the functional absorption cross section of PSII, σPSII, in F. cylindrus consistently increased after freezing, especially in the LL treatment (σPSII > 10 nm2 PSII–1). Our study is the first to report such a large σPSII in ice diatoms at low Fe conditions. When the melted sea ice was exposed to high light, Fv/Fm was suppressed. NPQ and XC were slightly upregulated, but not to values normally observed when Fe is not limiting, which indicates reduced photosynthetic flexibility to adapt to environmental changes during ice melt under low Fe conditions. Although ice algae can optimize their photosynthesis to sea-ice environments, chronic Fe starvation led to less flexibility of photoacclimation, particularly in low light conditions. This may have detrimental consequences for ice algal production and trophic interactions in sea-ice ecosystems if the recent reduction in sea-ice extent continues.

scholarly journals Bioconditioning of Arctic Waters and Stimulation of Arctic Phytoplankton by Sea Ice Algae: Vulnerability to Increased Light

ARCTIC ◽  
2020 ◽  
Vol 73 (1) ◽  
pp. 114-117
Author(s):  
Spencer Apollonio
Keyword(s):  
Sea Ice ◽  
Early Summer ◽  
Arctic Sea Ice ◽  
Phytoplankton Production ◽  
Ice Algae ◽  
Light Conditions ◽  
Low Light ◽  
Sea Ice Algae ◽  
Arctic Sea ◽  
Summer Growth

Arctic sea ice algae produce extracellular organic products, which, as bioconditioners of seawater, may stimulate early summer growth of pelagic, under-sea-ice phytoplankton in low light and low temperature conditions. Sea ice algae are inhibited or decline in numbers if prematurely exposed to high light conditions, thereby reducing their ability to produce bioconditioners. As climate change creates an early reduction or removal of snow and sea ice cover, the result may be a decrease in primary phytoplankton production.

scholarly journals Rapid Manipulation in Irradiance Induces Oxidative Free-Radical Release in a Fast-Ice Algal Community (McMurdo Sound, Antarctica)

2020 ◽  
Vol 11 ◽  
Author(s):  
Fraser Kennedy ◽  
Andrew Martin ◽  
Katerina Castrisios ◽  
Emiliano Cimoli ◽  
Andrew McMinn ◽  
...  
Keyword(s):  
Free Radicals ◽  
Sea Ice ◽  
Snow Cover ◽  
Electron Flow ◽  
Rapid Change ◽  
High Light ◽  
Algal Community ◽  
Ice Algae ◽  
Sea Ice Algae ◽  
Production Of Hydrogen

Sea ice supports a unique assemblage of microorganisms that underpin Antarctic coastal food-webs, but reduced ice thickness coupled with increased snow cover will modify energy flow and could lead to photodamage in ice-associated microalgae. In this study, microsensors were used to examine the influence of rapid shifts in irradiance on extracellular oxidative free radicals produced by sea-ice algae. Bottom-ice algal communities were exposed to one of three levels of incident light for 10 days: low (0.5 μmol photons m−2 s−1, 30 cm snow cover), mid-range (5 μmol photons m−2 s−1, 10 cm snow), or high light (13 μmol photons m−2 s−1, no snow). After 10 days, the snow cover was reversed (either removed or added), resulting in a rapid change in irradiance at the ice-water interface. In treatments acclimated to low light, the subsequent exposure to high irradiance resulted in a ~400× increase in the production of hydrogen peroxide (H2O2) and a 10× increase in nitric oxide (NO) concentration after 24 h. The observed increase in oxidative free radicals also resulted in significant changes in photosynthetic electron flow, RNA-oxidative damage, and community structural dynamics. In contrast, there was no significant response in sea-ice algae acclimated to high light and then exposed to a significantly lower irradiance at either 24 or 72 h. Our results demonstrate that microsensors can be used to track real-time in-situ stress in sea-ice microbial communities. Extrapolating to ecologically relevant spatiotemporal scales remains a significant challenge, but this approach offers a fundamentally enhanced level of resolution for quantifying the microbial response to global change.

scholarly journals Monitoring abiotic degradation in sinking versus suspended Arctic sea ice algae during a spring ice melt using specific lipid oxidation tracers

2016 ◽  
Vol 98 ◽  
pp. 82-97 ◽  
Author(s):  
Jean-François Rontani ◽  
Simon T. Belt ◽  
Thomas A. Brown ◽  
Rémi Amiraux ◽  
Michel Gosselin ◽  
...  
Keyword(s):  
Sea Ice ◽  
Lipid Oxidation ◽  
Arctic Sea Ice ◽  
Ice Algae ◽  
Ice Melt ◽  
Sea Ice Algae ◽  
Abiotic Degradation ◽  
Arctic Sea ◽  
Specific Lipid

Changes in the Stoichiometry of Photosystem II Components as an Adaptive Response to High-Light and Low-Light Conditions during Growth

1986 ◽  
Vol 41 (5-6) ◽  
pp. 597-603 ◽  
Author(s):  
Aloysius Wild ◽  
Matthias Höpfner ◽  
Wolfgang Rühle ◽  
Michael Richter
Keyword(s):  
Photosystem Ii ◽  
Functional Organization ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Molar Ratio ◽  
Light Conditions ◽  
Low Light ◽  
Pigment System ◽  
Transport Chain ◽  
The One

The effect of different growth light intensities (60 W·m-2, 6 W·m-2) on the performance of the photosynthetic apparatus of mustard plants (Sinapis alba L.) was studied. A distinct decrease in photosystem II content per chlorophyll under low-light conditions compared to high-light conditions was found. For P-680 as well as for Oᴀ and Oв protein the molar ratio between high-light and low-light plants was 1.4 whereas the respective concentrations per chlorophyll showed some variations for P-680 and Oᴀ on the one and Oв protein on the other hand.In addition to the study of photosystem II components, the concentrations of PQ, Cyt f, and P-700 were measured. The light regime during growth had no effect on the amount of P-700 per chlorophyll but there were large differences with respect to PQ and Cyt f. The molar ratio for Cyt f and PQ between high- and low-light leaves was 2.2 and 1.9, respectively.Two models are proposed, showing the functional organization of the pigment system and the electron transport chain in thylakoids of high-light and low-light leaves of mustard plants.

scholarly journals Effects of alkalinity and salinity at low and high light intensity on hydrogen isotope fractionation of long-chain alkenones produced by <i>Emiliania huxleyi</i>

2017 ◽  
Vol 14 (24) ◽  
pp. 5693-5704 ◽  
Author(s):  
Gabriella M. Weiss ◽  
Eva Y. Pfannerstill ◽  
Stefan Schouten ◽  
Jaap S. Sinninghe Damsté ◽  
Marcel T. J. van der Meer
Keyword(s):  
Light Intensity ◽  
Environmental Conditions ◽  
Hydrogen Isotope ◽  
Isotope Fractionation ◽  
Emiliania Huxleyi ◽  
High Light Intensity ◽  
High Light ◽  
Light Conditions ◽  
Low Light ◽  
Long Chain

Abstract. Over the last decade, hydrogen isotopes of long-chain alkenones have been shown to be a promising proxy for reconstructing paleo sea surface salinity due to a strong hydrogen isotope fractionation response to salinity across different environmental conditions. However, to date, the decoupling of the effects of alkalinity and salinity, parameters that co-vary in the surface ocean, on hydrogen isotope fractionation of alkenones has not been assessed. Furthermore, as the alkenone-producing haptophyte, Emiliania huxleyi, is known to grow in large blooms under high light intensities, the effect of salinity on hydrogen isotope fractionation under these high irradiances is important to constrain before using δDC37 to reconstruct paleosalinity. Batch cultures of the marine haptophyte E. huxleyi strain CCMP 1516 were grown to investigate the hydrogen isotope fractionation response to salinity at high light intensity and independently assess the effects of salinity and alkalinity under low-light conditions. Our results suggest that alkalinity does not significantly influence hydrogen isotope fractionation of alkenones, but salinity does have a strong effect. Additionally, no significant difference was observed between the fractionation responses to salinity recorded in alkenones grown under both high- and low-light conditions. Comparison with previous studies suggests that the fractionation response to salinity in culture is similar under different environmental conditions, strengthening the use of hydrogen isotope fractionation as a paleosalinity proxy.

scholarly journals Seasonal and latitudinal variations in sea ice algae deposition in the Northern Bering and Chukchi Seas determined by algal biomarkers

PLoS ONE ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. e0231178 ◽  
Author(s):  
Chelsea Wegner Koch ◽  
Lee W. Cooper ◽  
Catherine Lalande ◽  
Thomas A. Brown ◽  
Karen E. Frey ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ice Algae ◽  
Sea Ice Algae ◽  
Latitudinal Variations

scholarly journals The Response Regulator RpaB Binds to the Upstream Element of Photosystem I Genes To Work for Positive Regulation under Low-Light Conditions in Synechocystis sp. Strain PCC 6803

2008 ◽  
Vol 191 (5) ◽  
pp. 1581-1586 ◽  
Author(s):  
Yurie Seino ◽  
Tomoko Takahashi ◽  
Yukako Hihara
Keyword(s):  
Photosystem I ◽  
Promoter Activity ◽  
Response Regulator ◽  
Core Promoter ◽  
High Light ◽  
Light Conditions ◽  
Low Light ◽  
Positive Regulation ◽  
Upstream Element ◽  
Pcc 6803

ABSTRACT The coordinated high-light response of genes encoding subunits of photosystem I (PSI) is achieved by the AT-rich region located just upstream of the core promoter in Synechocystis sp. strain PCC 6803. The upstream element enhances the basal promoter activity under low-light conditions, whereas this positive regulation is lost immediately after the shift to high-light conditions. In this study, we focused on a high-light regulatory 1 (HLR1) sequence included in the upstream element of every PSI gene examined. A gel mobility shift assay revealed that a response regulator RpaB binds to the HLR1 sequence in PSI promoters. Base substitution in the HLR1 sequence or decrease in copy number of the rpaB gene resulted in decrease in the promoter activity of PSI genes under low-light conditions. These observations suggest that RpaB acts as a transcriptional activator for PSI genes. It is likely that RpaB binds to the HLR1 sequence under low-light conditions and works for positive regulation of PSI genes and for negative regulation of high-light-inducible genes depending on the location of the HLR1 sequence within target promoters.

Interactions entre mitochondries et chloroplastes dans la cellule. II. Action du DBMIB, de l'antimycine A et du FCCP sur la spore de Funaria hygrometrica

1977 ◽  
Vol 55 (12) ◽  
pp. 1650-1659 ◽  
Author(s):  
D. Chevallier ◽  
R. Douce ◽  
F. Nurit
Keyword(s):  
Cytochrome Oxidase ◽  
Dark Respiration ◽  
High Light ◽  
Light Conditions ◽  
Oxygen Production ◽  
Low Light ◽  
Funaria Hygrometrica ◽  
Light Intensities

The effect of DBMIB, antimycine A, and FCCP on respiration and photosynthesis of intact chlorophyllic moss (Funaria hygrometrica) spore was investigated.Antimycine A (1 μM) strongly inhibited dark respiration, was without effect on photosynthesis at high light intensities (above the saturation plateau values), and stimulated photosynthesis at low light intensities (below the saturation plateau values).DBMIB (3 μM) inhibited photosynthesis and was without effect, even under light conditions, on the dark respiration. Low amount of FCCP (3 μM) partially inhibited oxygen production at high light intensities. In this case, the inhibition observed was partially relieved by 1 μM antimycine A or 30 μM of KCN; higher concentration of FCCP totally inhibited the oxygen production.It seems likely, therefore, that in the chlorophyllic moss spore the cytochrome oxidase pathway is not functioning under high light intensities and that this inhibition of respiration is attributable to the low cytoplasmic ADP:ATP ratio.

scholarly journals Coordinated High-Light Response of Genes Encoding Subunits of Photosystem I Is Achieved by AT-Rich Upstream Sequences in the Cyanobacterium Synechocystis sp. Strain PCC 6803

2007 ◽  
Vol 189 (7) ◽  
pp. 2750-2758 ◽  
Author(s):  
Masayuki Muramatsu ◽  
Yukako Hihara
Keyword(s):  
Photosystem I ◽  
Promoter Region ◽  
Promoter Activity ◽  
Light Response ◽  
High Light ◽  
Light Conditions ◽  
Low Light ◽  
Genes Encoding ◽  
Responsive Element ◽  
Pcc 6803

ABSTRACT Genes encoding subunits of photosystem I (PSI genes) in the cyanobacterium Synechocystis sp. strain PCC 6803 are actively transcribed under low-light conditions, whereas their transcription is coordinately and rapidly down-regulated upon the shift to high-light conditions. In order to identify the molecular mechanism of the coordinated high-light response, we searched for common light-responsive elements in the promoter region of PSI genes. First, the precise architecture of the psaD promoter was determined and compared with the previously identified structure of the psaAB promoter. One of two promoters of the psaAB genes (P1) and of the psaD gene (P2) possessed an AT-rich light-responsive element located just upstream of the basal promoter region. These sequences enhanced the basal promoter activity under low-light conditions, and their activity was transiently suppressed upon the shift to high-light conditions. Subsequent analysis of psaC, psaE, psaK1, and psaLI promoters revealed that their light response was also achieved by AT-rich sequences located at the −70 to −46 region. These results clearly show that AT-rich upstream elements are responsible for the coordinated high-light response of PSI genes dispersed throughout Synechocystis genome.

Sign in / Sign up

Export Citation Format

Share Document