Search results for "green alga"

Epigenetic and Genetic Contributions to Adaptation in Chlamydomonas

2017

Epigenetic modifications, such as DNA methylation or histone modifications, can be transmitted between cellular or organismal generations. However, there are no experiments measuring their role in adaptation, so here we use experimental evolution to investigate how epigenetic variation can contribute to adaptation. We manipulated DNA methylation and histone acetylation in the unicellular green alga Chlamydomonas reinhardtii both genetically and chemically to change the amount of epigenetic variation generated or transmitted in adapting populations in three different environments (salt stress, phosphate starvation, and high CO2) for two hundred asexual generations. We find that reducing the …

2020

Phytoplankton synthesizes essential ω-3 and ω-6 polyunsaturated fatty acids (PUFA) for consumers in the aquatic food webs. Only certain phytoplankton taxa can synthesize eicosapentaenoic (EPA; 20:5ω3) and docosahexaenoic acid (DHA; 22:6ω3), whereas all phytoplankton taxa can synthesize shorter-chain ω-3 and ω-6 PUFA. Here, we experimentally studied how the proportion, concentration (per DW and cell-specific), and production (µg FA L−1 day−1) of ω-3 and ω-6 PUFA varied among six different phytoplankton main groups (16 freshwater strains) and between exponential and stationary growth phase. EPA and DHA concentrations, as dry weight, were similar among cryptophytes and diatoms. However, Crypto…

Functional rearrangement of the light-harvesting antenna upon state transitions in a green alga

2014

AbstractState transitions in the green alga Chlamydomonas reinhardtii serve to balance excitation energy transfer to photosystem I (PSI) and to photosystem II (PSII) and possibly play a role as a photoprotective mechanism. Thus, light-harvesting complex II (LHCII) can switch between the photosystems consequently transferring more excitation energy to PSII (state 1) or to PSI (state 2) or can end up in LHCII-only domains. In this study, low-temperature (77 K) steady-state and time-resolved fluorescence measured on intact cells of Chlamydomonas reinhardtii shows that independently of the state excitation energy transfer from LHCII to PSI or to PSII occurs on two main timescales of <15 ps and …

AphaMax®, an Aphanizomenon Flos-Aquae Aqueous Extract, Exerts Intestinal Protective Effects in Experimental Colitis in Rats

2020

Background: Aphanizomenon flos-aquae (AFA) is a unicellular cyanobacterium considered to be a &ldquo

The hidden diversity of lichenized Trebouxiophyceae (Chlorophyta).

2018

The class Trebouxiophyceae is comprised of coccoid to ellipsoid unicells, filaments, blades and colony-forming species of green algae occurring in diverse terrestrial and aquatic environments. Some representatives have evolved parasitic heterotrophic lifestyles, others have been investigated for their biotechnological potential and others have evolved as integral components of lichen symbioses. In this review, we provide an overview of the current understanding of diversity, taxonomy and evolutionary context for the important lichen-forming algal class Trebouxiophyceae (Chlorophyta). In particular, we focus on members of the family Trebouxiaceae (Trebouxiales), the best-known, most widespre…

2021

Gammarid amphipods are a crucial link connecting primary producers with secondary consumers, but little is known about their nutritional ecology. Here we asked how starvation and subsequent feeding on different nutritional quality algae influences fatty acid retention, compound-specific isotopic carbon fractionation, and biosynthesis of ω-3 and ω-6 polyunsaturated fatty acids (PUFA) in the relict gammarid amphipod Pallaseopsis quadrispinosa. The fatty acid profiles of P. quadrispinosa closely matched with those of the dietary green algae after only seven days of refeeding, whereas fatty acid patterns of P. quadrispinosa were less consistent with those of the diatom diet. This was mainly due…

Phytoplankton structure in different lake types in central Finland

1986

Phyloplankton structure and its relation to physical and chemical properties of the water was studied in 58 central Finnish lakes. The biomass ranged from 0.2 to 14.2 g m−3 and the number of taxa per sample ranged from 33 to 152. The lakes were grouped into 5 types according to their trophic state: eutrophic, dyseutrophic, mesotrophic, oligotrophic, and acid oligotrophic lakes. The average biomass in eutrophic lakes was 5.57 g m−3, in dyseutrophic 3.54 g m−3, 1.23 g m−3 in mesotrophic, 0.52 g m−3 in oligotrophic and 0.39 g −3 in acid oligotrophic lakes. The average number of taxa per sample in the corresponding lake types were 109. 1, 79.3, 97.9, 90.9 and 43.8, respectively. The phytoplankt…

Solar PAR and UVR modify the community composition and photosynthetic activity of sea ice algae

2015

The effects of increased photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) on species diversity, biomass and photosynthetic activity were studied in fast ice algal communities. The experimental set-up consisted of nine 1.44 m(2) squares with three treatments: untreated with natural snow cover (UNT), snow-free (PAR + UVR) and snow-free ice covered with a UV screen (PAR). The total algal biomass, dominated by diatoms and dinoflagellates, increased in all treatments during the experiment. However, the smaller biomass growth in the top 10-cm layer of the PAR + UVR treatment compared with the PAR treatment indicated the negative effect of UVR. Scrippsiella complex (mainly…

Toxicity of waste gasification bottom ash leachate

2011

Abstract Toxicity of waste gasification bottom ash leachate from landfill lysimeters (112 m3) was studied over three years. The leachate of grate incineration bottom ash from a parallel setup was used as reference material. Three aquatic organisms (bioluminescent bacteria, green algae and water flea) were used to study acute toxicity. In addition, an ethoxyresorufin-O-deethylase (EROD) assay was performed with mouse hepatoma cells to indicate the presence of organic contaminants. Concentrations of 14 elements and 15 PAH compounds were determined to characterise leachate. Gasification ash leachate had a high pH (9.2–12.4) and assays with and without pH adjustment to neutral were used. Gasifi…

Biocoenosis and induration of freshwaterRivulariastromatolites in a temperate climate

1997

Freshwater Rivularia haematites (D.C.) Agardh and Rivularia biasolettiana Menegh‐ini stromatolites were collected from the Plateau de Langres and Lac d'Annecy (France) and investigated experimentally. In addition to cyanobacteria, the community of organisms consists of Desmococcus (green algae) and many bacteria including Agrobacterium tumefaciens and Pseudomonas diminuta for Rivularia haematites, and Achromobacter group B and Pseudomonas acidovorans for Rivularia biasolettiana. Stromatolite induration is not confined to calcification and may locally exhibit apatite or gypsum crystals, with the latter appearing only in cultures exposed to light. The effect of certain microorganisms of the b…