scholarly journals Lichen-like association of Chlamydomonas reinhardtii and Aspergillus nidulans protects algal cells from bacteria

2020 ◽  
Vol 14 (11) ◽  
pp. 2794-2805 ◽  
Author(s):  
Mario K. C. Krespach ◽  
María García-Altares ◽  
Michal Flak ◽  
Hanno Schoeler ◽  
Kirstin Scherlach ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Aspergillus Nidulans ◽  
Membrane Lipids ◽  
Algal Growth ◽  
Microbial Consortia ◽  
Bacterial Toxin ◽  
Fungal Mycelium ◽  
Algicidal Bacterium ◽  
Maldi Ims ◽  
Algicidal Compound

Abstract Organismal interactions within microbial consortia and their responses to harmful intruders remain largely understudied. An important step toward the goal of understanding functional ecological interactions and their evolutionary selection is the study of increasingly complex microbial interaction systems. Here, we discovered a tripartite biosystem consisting of the fungus Aspergillus nidulans, the unicellular green alga Chlamydomonas reinhardtii, and the algicidal bacterium Streptomyces iranensis. Genetic analyses and MALDI-IMS demonstrate that the bacterium secretes the algicidal compound azalomycin F upon contact with C. reinhardtii. In co-culture, A. nidulans attracts the motile alga C. reinhardtii, which becomes embedded and surrounded by fungal mycelium and is shielded from the algicide. The filamentous fungus Sordaria macrospora was susceptible to azalomycin F and failed to protect C. reinhardtii despite chemotactically attracting the alga. Because S. macrospora was susceptible to azalomycin F, this data imply that for protection the fungus needs to be resistant. Formation of the lichen-like association between C. reinhardtii and A. nidulans increased algal growth. The protection depends on the increased amounts of membrane lipids provided by resistant fungi, thereby generating a protective shelter against the bacterial toxin. Our findings reveal a strategy whereby algae survive lethal environmental algicides through cooperation with fungi.

scholarly journals Impact of Membrane Lipids on UapA and AzgA Transporter Subcellular Localization and Activity in Aspergillus nidulans

2021 ◽  
Vol 7 (7) ◽  
pp. 514
Author(s):  
Mariangela Dionysopoulou ◽  
George Diallinas
Keyword(s):  
Plasma Membrane ◽  
Subcellular Localization ◽  
Aspergillus Nidulans ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Lipid Biosynthesis ◽  
Transport Kinetics ◽  
Negative Effect ◽  
And Function

Recent biochemical and biophysical evidence have established that membrane lipids, namely phospholipids, sphingolipids and sterols, are critical for the function of eukaryotic plasma membrane transporters. Here, we study the effect of selected membrane lipid biosynthesis mutations and of the ergosterol-related antifungal itraconazole on the subcellular localization, stability and transport kinetics of two well-studied purine transporters, UapA and AzgA, in Aspergillus nidulans. We show that genetic reduction in biosynthesis of ergosterol, sphingolipids or phosphoinositides arrest A. nidulans growth after germling formation, but solely blocks in early steps of ergosterol (Erg11) or sphingolipid (BasA) synthesis have a negative effect on plasma membrane (PM) localization and stability of transporters before growth arrest. Surprisingly, the fraction of UapA or AzgA that reaches the PM in lipid biosynthesis mutants is shown to conserve normal apparent transport kinetics. We further show that turnover of UapA, which is the transporter mostly sensitive to membrane lipid content modification, occurs during its trafficking and by enhanced endocytosis, and is partly dependent on autophagy and Hect-type HulARsp5 ubiquitination. Our results point out that the role of specific membrane lipids on transporter biogenesis and function in vivo is complex, combinatorial and transporter-dependent.

Sites of Herbicidal Action on Photosynthesis: A Fluorescence Assay Study

Weed Science ◽  
1981 ◽  
Vol 29 (4) ◽  
pp. 371-375 ◽  
Author(s):  
H. Böhme ◽  
K. J. Kunert ◽  
P. Böger
Keyword(s):  
Chlorophyll Fluorescence ◽  
Membrane Lipids ◽  
Diphenyl Ether ◽  
Algal Growth ◽  
Fluorescence Induction ◽  
Rapid Screening ◽  
Diphenyl Ethers ◽  
Total Fluorescence ◽  
Transport Inhibitors ◽  
Weak Electron

The effect of the bleaching and non-bleaching phenylpyridazinones, norflurazon [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone] and BAS 29095 [4,5-dimethoxy-2-phenyl-3(2H)-pyridazinone], on chlorophyll fluorescence of the green alga,Scenedesmus acutus, was investigated and compared to other bleaching herbicides, difunon3[EMD-IT 5914, 5(dimethylamino-methylene)-2-oxo-4-phenyl-2,5-dihydrofuranecarbonitrile-(3)] and the diphenyl ether, oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene]. Following chlorophyll fluorescence during short-term cultivation in the presence of herbicides and comparing it to physiological parameters such as chlorophyll content and packed cell volume allowed for rapid screening to detect different primary herbicidal modes of action. Two primary bleaching effects caused by either inhibition of carotene biosynthesis (certain substituted pyridazinones and difunon) or peroxidative degradation of membrane lipids (certain diphenyl ethers) led to completely different fluorescence signals. Growth of algae in the presence of a carotene biosynthesis inhibitor resulted in a rapid rise to maximum fluorescence, followed by a single decay phase, whereas bleaching diphenyl ethers led to a rapid loss of total fluorescence. Non-bleaching phenylpyridazinones, which act as weak electron transport inhibitors, inhibited variable fluorescence. Detoxication during algal growth became evident by recovery of the fluorescence induction.

scholarly journals THE A water-soluble [60]fullerene-derivative stimulates chlorophyll accumulation and has no toxic effect on Chlamydomonas reinhardtii

2019 ◽  
Author(s):  
Jakub Lang ◽  
Mariia Melnykova ◽  
Michele Catania ◽  
Alicja Inglot ◽  
Aleksandra Zyss ◽  
...  
Keyword(s):  
Growth Rate ◽  
Chlamydomonas Reinhardtii ◽  
Algal Growth ◽  
Water Soluble ◽  
Fullerene Derivative ◽  
Industrial Biotechnology ◽  
Photosynthetic Parameters ◽  
Suitable Model ◽  
Chlorophyll Accumulation ◽  
Surface Modified

Chlamydomonas reinhardtii (WT 2137) P. A. Dang. (Volvocales, Chlorophyceae) is a green microalgae serving as a suitable model in scientific research and a promising industrial biotechnology platform for production of biofuel, hydrogen and recombinant proteins. Fullerenes (C60) are allotropic carbon nanoparticles discovered in 1985 and used in biomedical studies since the early 1990s, when water solubilization methodologies were developed. Recently, surface-modified hydroxylated derivatives of fullerenes were proven to enhance algal growth and drought tolerance in plants. Here, a novel type of water-soluble [60]fullerene derivative with 12 glycine residues (GF) has been synthesized and tested for acute toxicity (up to 50 µg/ml) and as a potential biostimulant of algal growth. The effects of GF on pigment composition and growth rate of Chlamydomonas reinhardtii were systematically investigated. Our results suggest that GF was not toxic, and no negative change in the pigment content and no stress symptoms were observed. No changes in the photosynthetic parameters based on the fluorescence of chlorophyll a in Photosystem II (NPQ, Fv/Fm, Fv/F0, PI and RC/ABS) were observed. The GF had no effect on cell size and growth rate. At a concentration of 20 µg/ml, GF stimulated chlorophyll accumulation in 3-day-old cultures.

scholarly journals The bacterial toxin ExoU requires a host trafficking chaperone for transportation and to induce necrosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Vincent Deruelle ◽  
Stéphanie Bouillot ◽  
Viviana Job ◽  
Emmanuel Taillebourg ◽  
Marie-Odile Fauvarque ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Secretory Pathway ◽  
Membrane Lipids ◽  
Neuronal Ceroid Lipofuscinosis ◽  
Bacterial Toxin ◽  
Membrane Rupture ◽  
Host Cytoplasm ◽  
Genome Wide ◽  
A Genome ◽  
Dependent Cell

AbstractPseudomonas aeruginosa can cause nosocomial infections, especially in ventilated or cystic fibrosis patients. Highly pathogenic isolates express the phospholipase ExoU, an effector of the type III secretion system that acts on plasma membrane lipids, causing membrane rupture and host cell necrosis. Here, we use a genome-wide screen to discover that ExoU requires DNAJC5, a host chaperone, for its necrotic activity. DNAJC5 is known to participate in an unconventional secretory pathway for misfolded proteins involving anterograde vesicular trafficking. We show that DNAJC5-deficient human cells, or Drosophila flies knocked-down for the DNAJC5 orthologue, are largely resistant to ExoU-dependent virulence. ExoU colocalizes with DNAJC5-positive vesicles in the host cytoplasm. DNAJC5 mutations preventing vesicle trafficking (previously identified in adult neuronal ceroid lipofuscinosis, a human congenital disease) inhibit ExoU-dependent cell lysis. Our results suggest that, once injected into the host cytoplasm, ExoU docks to DNAJC5-positive secretory vesicles to reach the plasma membrane, where it can exert its phospholipase activity

Membrane lipid and osmolyte readjustment in the alkaliphilic micromycete Sodiomyces tronii under cold, heat and osmotic shocks

Microbiology ◽  
2021 ◽  
Vol 167 (11) ◽  
Author(s):  
Elena A. Ianutsevich ◽  
Olga A. Danilova ◽  
Sofiya A. Bondarenko ◽  
Vera M. Tereshina
Keyword(s):  
Membrane Lipids ◽  
Membrane Lipid ◽  
Fungal Mycelium ◽  
Storage Lipids ◽  
Degree Of Unsaturation ◽  
Phosphatidic Acids ◽  
Alkaline Conditions ◽  
First Time ◽  
And Storage ◽  
Alkaliphilic Fungi

Previously, we showed for the first time that alkaliphilic fungi, in contrast to alkalitolerant fungi, accumulated trehalose under extremely alkaline conditions, and we have proposed its key role in alkaliphilia. We propose that high levels of trehalose in the mycelium of alkaliphiles may promote adaptation not only to alkaline conditions, but also to other stressors. Therefore, we studied changes in the composition of osmolytes, and storage and membrane lipids under the action of cold (CS), heat (HS) and osmotic (OS) shocks in the obligate alkaliphilic micromycete Sodiomyces tronii. During adaptation to CS, an increase in the degree of unsaturation of phospholipids was observed while the composition of osmolytes, membrane and storage lipids remained the same. Under HS conditions, a twofold increase in the level of trehalose and an increase in the proportion of phosphatidylethanolamines were observed against the background of a decrease in the proportion of phosphatidic acids. OS was accompanied by a decrease in the amount of membrane lipids, while their ratio remained unchanged, and an increase in the level of polyols (arabitol and mannitol) in the fungal mycelium, which suggests their role for adaptation to OS. Thus, the observed consistency of the composition of membrane lipids suggests that trehalose can participate in adaptation not only to extremely alkaline conditions, but also to other stressors – HS, CS and OS. Taken together, the data obtained indicate the adaptability of the fungus to the action of various stressors, which can point to polyextremotolerance.

Membrane lipid metabolism in Chlamydomonas reinhardtii 137+ and Y-1: I. Biochemical localization and characterization of acyltransferase activities

1982 ◽  
Vol 58 (1) ◽  
pp. 469-488
Author(s):  
C.L. Jelsema ◽  
A.S. Michaels ◽  
D.R. Janero ◽  
R.J. Barrnett
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Enzyme Activities ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Light Induction ◽  
Wild Type ◽  
Ph Optimum ◽  
Acyltransferase Activity ◽  
Photosynthetic Membranes ◽  
Chloroplast Membrane

The acyltransferases involved in the synthesis of the chloroplast membrane glycerolipids were analysed biochemically in dark-grown and greening Chlamydomonas reinhardtii y-1 as well as in the synchronous wild-type algae (strain 137+) and wild-type membranes. Using oleoyl-CoA as a substrate, three acyltransferase enzyme activities were detected. Glycerol-3-phosphate (glycerol-3-P) acyltransferase exhibited a pH optimum of 8.0 and was inhibited by addition of N-ethylmaleimide (MalNEt). Lysophosphatidate (PtdLys) acyltransferase exhibited a pH optimum of 7.0 and was not affected by the addition of MalNEt. From preliminary analyses, the activity at pH 5.5 appeared to be associated with dihydroxyacetone phosphate acyltransferase activity. Both glycerol-3-P and PtdLys acyltransferases were analysed further and found to be present in dark-grown and light-induced y-1 cells as well as in synchronous 137+ cells and their photosynthetic membranes. Both enzyme activities were enriched at least 10-fold in the photosynthetic membranes of 137+ chloroplasts relative to the activities present in the whole cells. This enrichment is indicative of their intrinsic localization in the thylakoids, suggesting that the photosynthetic membranes exhibit a greater degree of autonomy with respect to the synthesis of their membrane lipids than previously reported. A role for glycerol-3-P and PtdLys acyltransferases in the synthesis of the chloroplast membrane lipids is suggested further by the increases in both enzyme activities coincident with and preceding thylakoid biogenesis following light induction of dark-grown y-1 cells. Increased acyltransferase activity preceded the increase in the chlorophyll content of greening y-1 cells, which is a generally accepted marker for thylakoid synthesis. The increase in the PtdLys acyltransferase activity upon light-induction of the y-1 cells was both more immediate and more dramatic than the increase in glycerol-3-P acyltransferase activity. PtdLys acyltransferase activity was negligible in dark-grown cells and the dramatic increase upon light induction may be important in the subsequent initiation of chloroplast membrane lipid synthesis. On the basis of the localization of acyltransferase enzyme activities to the photosynthetic membranes of 137+ cells and the increase in acyltransferase activity both preceding and occurring in concert with thylakoid synthesis, we propose a direct role for the photosynthetic membranes in the synthesis of their membrane lipid components.

scholarly journals Triacylglyceride Production and Autophagous Responses in Chlamydomonas reinhardtii Depend on Resource Allocation and Carbon Source

2014 ◽  
Vol 13 (3) ◽  
pp. 392-400 ◽  
Author(s):  
Matthew P. Davey ◽  
Irmtraud Horst ◽  
Giang-Huong Duong ◽  
Eleanor V. Tomsett ◽  
Alexander C. P. Litvinenko ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Membrane Lipids ◽  
N Availability ◽  
Wild Type ◽  
Metabolic Switch ◽  
Content Type ◽  
Carbon Supply ◽  
Microalgal Biodiesel ◽  
In The Wild ◽  
Mutant Cells

ABSTRACT To improve the economic viability of microalgal biodiesel, it will be essential to optimize the productivity of fuel molecules such as triacylglyceride (TAG) within the microalgal cell. To understand some of the triggers required for the metabolic switch to TAG production, we studied the effect of the carbon supply (acetate or CO 2 ) in Chlamydomonas reinhardtii (wild type and the starchless sta6 mutant) grown under low N availability. As expected, initial rates of TAG production were much higher when acetate was present than under strictly photosynthetic conditions, particularly for the sta6 mutant, which cannot allocate resources to starch. However, in both strains, TAG production plateaued after a few days in mixotrophic cultures, whereas under autotrophic conditions, TAG levels continued to rise. Moreover, the reduced growth of the sta6 mutant meant that the greatest productivity (measured as mg TAG liter −1 day −1 ) was found in the wild type growing autotrophically. Wild-type cells responded to low N by autophagy, as shown by degradation of polar (membrane) lipids and loss of photosynthetic pigments, and this was less in cells supplied with acetate. In contrast, little or no autophagy was observed in sta6 mutant cells, regardless of the carbon supply. Instead, very high levels of free fatty acids were observed in the sta6 mutant, suggesting considerable alteration in metabolism. These measurements show the importance of carbon supply and strain selection for lipid productivity. Our findings will be of use for industrial cultivation, where it will be preferable to use fast-growing wild-type strains supplied with gaseous CO 2 under autotrophic conditions rather than require an exogenous supply of organic carbon.

Only iron-limited cells of the cyanobacterium Anabaena flos-aquae inhibit growth of the green alga Chlamydomonas reinhardtii

2004 ◽  
Vol 82 (4) ◽  
pp. 436-442 ◽  
Author(s):  
Carlyn J Matz ◽  
Michael R Christensen ◽  
Auralee D Bone ◽  
Courtney D Gress ◽  
Scott B Widenmaier ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Green Alga ◽  
Activated Charcoal ◽  
Algal Growth ◽  
Inhibitory Effect ◽  
The Other ◽  
Iron Limitation ◽  
Green Algal ◽  
Cyanobacterium Anabaena ◽  
Cobalt Copper

Cocultivation of iron-limited cells of the cyanobacterium Anabaena flos-aquae (Lyng.) Brèb. and the green alga Chlamydomonas reinhardtii Dangeard resulted in growth of Anabaena but not Chlamydomonas, even in the presence of excess exogenous iron. This effect was also observed during the cultivation of Chlamydomonas in a medium in which iron-limited Anabaena cells had been growing, but were removed prior to culture of Chlamydomonas. Conversely, iron-limited Chlamydomonas cells grew very well in medium from iron (nutrient)-sufficient, phosphate-limited, and nitrogen-limited Anabaena cultures. Iron-limited Anabaena cultures produced siderophores, while the other types of Anabaena cultures did not. Treatment of Anabaena iron-limited medium with activated charcoal completely removed the inhibitory effect on Chlamydomonas growth, and boiling the medium removed most of the inhibitory effect. Both the charcoal and the boiling treatments also removed siderophores from the medium. Partially purified Anabaena siderophore preparations were also inhibitory to Chlamydomonas growth. The inhibitory effect of iron-limited Anabaena medium could be partially overcome by addition of excess micronutrients (especially cobalt copper) but not by addition of iron. We suggest that Anabaena-derived siderophores, present only in iron-limited Anabaena medium, inhibit the growth of Chlamydomonas cells via a previously uncharacterized toxicity. This effect is different from previously described experiments in which cyanobacterial siderophores suppressed green algal growth via competition for limiting amounts of iron.Key words: Anabaena, Chlamydomonas, cocultivation, iron limitation, micronutrients; siderophores.

scholarly journals A new glance at the chemosphere of macroalgal–bacterial interactions: In situ profiling of metabolites in symbiosis by mass spectrometry

2021 ◽  
Vol 17 ◽  
pp. 1313-1322
Author(s):  
Marine Vallet ◽  
Filip Kaftan ◽  
Veit Grabe ◽  
Fatemeh Ghaderiardakani ◽  
Simona Fenizia ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Laser Scanning ◽  
High Resolution Mass Spectrometry ◽  
Imaging Techniques ◽  
Algal Growth ◽  
Laser Scanning Microscopy ◽  
Microbial Consortia ◽  
Confocal Laser ◽  
Metabolic Marker

Symbiosis is a dominant form of life that has been observed numerous times in marine ecosystems. For example, macroalgae coexist with bacteria that produce factors that promote algal growth and morphogenesis. The green macroalga Ulva mutabilis (Chlorophyta) develops into a callus-like phenotype in the absence of its essential bacterial symbionts Roseovarius sp. MS2 and Maribacter sp. MS6. Spatially resolved studies are required to understand symbiont interactions at the microscale level. Therefore, we used mass spectrometry profiling and imaging techniques with high spatial resolution and sensitivity to gain a new perspective on the mutualistic interactions between bacteria and macroalgae. Using atmospheric pressure scanning microprobe matrix-assisted laser desorption/ionisation high-resolution mass spectrometry (AP-SMALDI-HRMS), low-molecular-weight polar compounds were identified by comparative metabolomics in the chemosphere of Ulva. Choline (2-hydroxy-N,N,N-trimethylethan-1-aminium) was only determined in the alga grown under axenic conditions, whereas ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) was found in bacterial presence. Ectoine was used as a metabolic marker for localisation studies of Roseovarius sp. within the tripartite community because it was produced exclusively by these bacteria. By combining confocal laser scanning microscopy (cLSM) and AP-SMALDI-HRMS, we proved that Roseovarius sp. MS2 settled mainly in the rhizoidal zone (holdfast) of U. mutabilis. Our findings provide the fundament to decipher bacterial symbioses with multicellular hosts in aquatic ecosystems in an ecologically relevant context. As a versatile tool for microbiome research, the combined AP-SMALDI and cLSM imaging analysis with a resolution to level of a single bacterial cell can be easily applied to other microbial consortia and their hosts. The novelty of this contribution is the use of an in situ setup designed to avoid all types of external contamination and interferences while resolving spatial distributions of metabolites and identifying specific symbiotic bacteria.

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