Metatranscriptomic and metabolite profiling reveals vertical heterogeneity within a <i>Zygnema</i> green algal mat from Svalbard (High Arctic)

Rippin, Martin; Pichrtová, Martina; Arc, Erwann; Kranner, Ilse; Becker, Burkhard; Holzinger, Andreas

doi:10.1111/1462-2920.14788

Cited by 27 publications

(24 citation statements)

References 119 publications

(189 reference statements)

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“…The standard chemical fixation protocol carried out for field samples of Micrasterias is routinely carried out also in other desmids (Stamenkovic et al 2014) collected in remote locations (e.g. Rippin et al 2019) when no access to an HPF device is given. A transfer of field samples to the laboratory for HPF would certainly have more influence on the ultrastructure than chemical fixation on site.…”

Section: Transmission Electron Microscopymentioning

confidence: 99%

Winter survival of the unicellular green alga Micrasterias denticulata: insights from field monitoring and simulation experiments

et al. 2021

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Peat bog pools around Tamsweg (Lungau, Austria) are typical habitats of the unicellular green alga Micrasterias denticulata. By measurement of water temperature and irradiation throughout a 1-year period (2018/2019), it was intended to assess the natural environmental strain in winter. Freezing resistance of Micrasterias cells and their ability to frost harden and become tolerant to ice encasement were determined after natural hardening and exposure to a cold acclimation treatment that simulated the natural temperature decrease in autumn. Transmission electron microscopy (TEM) was performed in laboratory-cultivated cells, after artificial cold acclimation treatment and in cells collected from field. Throughout winter, the peat bog pools inhabited by Micrasterias remained unfrozen. Despite air temperature minima down to −17.3 °C, the water temperature was mostly close to +0.8 °C. The alga was unable to frost harden, and upon ice encasement, the cells showed successive frost damage. Despite an unchanged freezing stress tolerance, significant ultrastructural changes were observed in field-sampled cells and in response to the artificial cold acclimation treatment: organelles such as the endoplasmic reticulum and thylakoids of the chloroplast showed distinct membrane bloating. Still, in the field samples, the Golgi apparatus appeared in an impeccable condition, and multivesicular bodies were less frequently observed suggesting a lower overall stress strain. The observed ultrastructural changes in winter and after cold acclimation are interpreted as cytological adjustments to winter or a resting state but are not related to frost hardening as Micrasterias cells were unable to improve their freezing stress tolerance.

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Section: Transmission Electron Microscopymentioning

confidence: 99%

Winter survival of the unicellular green alga Micrasterias denticulata: insights from field monitoring and simulation experiments

et al. 2021

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“…This species has recently been used for several transcriptomic studies ( Rippin et al, 2017 ; de Vries et al, 2018 ). Different species of Zygnema can be found all over the world, including Arctic and Antarctic areas ( Holzinger et al, 2009 ; Pichrtová et al, 2018 ; Rippin et al, 2019 ), probably because they have evolved genes to tolerate stresses from extreme environments, such as cold and desiccation ( Rippin et al, 2017 ; de Vries et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

Characterization of Two Zygnema Strains (Zygnema circumcarinatum SAG 698-1a and SAG 698-1b) and a Rapid Method to Estimate Nuclear Genome Size of Zygnematophycean Green Algae

et al. 2021

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Zygnematophyceae green algae (ZGA) have been shown to be the closest relatives of land plants. Three nuclear genomes (Spirogloea muscicola, Mesotaenium endlicherianum, and Penium margaritaceum) of ZGA have been recently published, and more genomes are underway. Here we analyzed two Zygnema circumcarinatum strains SAG 698-1a (mating +) and SAG 698-1b (mating −) and found distinct cell sizes and other morphological differences. The molecular identities of the two strains were further investigated by sequencing their 18S rRNA, psaA and rbcL genes. These marker genes of SAG 698-1a were surprisingly much more similar to Z. cylindricum (SAG 698-2) than to SAG 698-1b. Phylogenies of these marker genes also showed that SAG 698-1a and SAG 698-1b were well separated into two different Zygnema clades, where SAG 698-1a was clustered with Z. cylindricum, while SAG 698-1b was clustered with Z. tunetanum. Additionally, physiological parameters like ETRmax values differed between SAG 698-1a and SAG 698-1b after 2 months of cultivation. The de-epoxidation state (DEPS) of the xanthophyll cycle pigments also showed significant differences. Surprisingly, the two strains could not conjugate, and significantly differed in the thickness of the mucilage layer. Additionally, ZGA cell walls are highly enriched with sticky and acidic polysaccharides, and therefore the widely used plant nuclear extraction protocols do not work well in ZGA. Here, we also report a fast and simple method, by mechanical chopping, for efficient nuclear extraction in the two SAG strains. More importantly, the extracted nuclei were further used for nuclear genome size estimation of the two SAG strains by flow cytometry (FC). To confirm the FC result, we have also used other experimental methods for nuclear genome size estimation of the two strains. Interestingly, the two strains were found to have very distinct nuclear genome sizes (313.2 ± 2.0 Mb in SAG 698-1a vs. 63.5 ± 0.5 Mb in SAG 698-1b). Our multiple lines of evidence strongly indicate that SAG 698-1a possibly had been confused with SAG 698-2 prior to 2005, and most likely represents Z. cylindricum or a closely related species.

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“…minus mats had probably a short time, several months, for development of such a complex structure, while the cyanobacterial mats can persist for many years (Hawes et al 2013). Nevertheless, even morphologically undifferentiated mats may express vertical heterogeneity (Rippin et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Annual Cycle of Mat‐Forming Filamentous Alga Tribonema cf. minus (Stramenopiles, Xanthophyceae) in Hydro‐Terrestrial Habitats in the High Arctic Revealed By Multiparameter Fluorescent Staining

Jimel

Kvíderová

Elster

2021

Journal of Phycology

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The filamentous microalga Tribonema sp. (Stramenopiles, Xanthophyceae) plays an important role in shallow water polar (streams and seepages) and seasonally cold habitats in temperate regions (ponds). In these habitats, freezing and desiccation, and thus freeze–thawing and drying–rewetting cycles, are frequent. These regions produce visible biomass and are important components of low temperature‐adapted communities. We characterized the annual cycles of a Tribonema cf. minus population in two habitats (seepage and stream) in the High Arctic, Svalbard. Seasonality, locality, and their combination (particularly changing environmental conditions) together with cultivation conditions of strains significantly affected their morphological characteristics. Morphological changes following hardening processes related to preparation for the winter period (transition from vegetative cells to akinete and/or pre‐akinete) were recorded. Over the year, positive water temperatures (warmest 13.3°C) occurred for 5 months while negative (lowest temperature was –17.4°C) lasted for 7 months. In winter, there were two melt periods. Vitality staining protocol showed a high number of viable (77.4% and 53.8%) and dormant cells (1.7% and 4.1%; capable of growth and reproduction once suitable conditions return) in the winter seepage and stream, respectively. NPQ and OJIP chlorophyll fluorescence parameters revealed several hours recovery of photosynthesis (both field and control samples). During recovery, only minor or mild stress on photosynthesis was detected. FV/FM values (the photosynthetic efficiency of photosystem II in a dark‐adapted state) in all field and control samples varied around 0.4. Tribonema cf. minus is capable of surviving winter Arctic conditions (perennial strategy).

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Metatranscriptomic and metabolite profiling reveals vertical heterogeneity within a Zygnema green algal mat from Svalbard (High Arctic)

Cited by 27 publications

References 119 publications

Winter survival of the unicellular green alga Micrasterias denticulata: insights from field monitoring and simulation experiments

Winter survival of the unicellular green alga Micrasterias denticulata: insights from field monitoring and simulation experiments

Characterization of Two Zygnema Strains (Zygnema circumcarinatum SAG 698-1a and SAG 698-1b) and a Rapid Method to Estimate Nuclear Genome Size of Zygnematophycean Green Algae

Annual Cycle of Mat‐Forming Filamentous Alga Tribonema cf. minus (Stramenopiles, Xanthophyceae) in Hydro‐Terrestrial Habitats in the High Arctic Revealed By Multiparameter Fluorescent Staining

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