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Background: Synthetic algal-fungal and algal-bacterial cultures have been investigated as a means to enhance the technological applications of the algae. This inclusion of other microbes has enhanced growth and improved stress tolerance of the algal culture. The goal of the current study was to investigate natural microbial consortia to gain an understanding of the occurrence and benefits of these associations in nature. The photosynthetic protist Euglena mutabilis is often found in association with other microbes in acidic environments with high heavy metal (HM) concentrations. This may suggest that microbial interactions are essential for the protist's ability to tolerate these extreme environments. Our study assessed the Cd tolerance of a natural fungal-algal-bacterial (FAB) association whereby the algae is E. mutabilis., Results: This study provides the first assessment of antibiotic and antimycotic agents on an E. mutabilis culture. The results indicate that antibiotic and antimycotic applications significantly decreased the viability of E. mutabilis cells when they were also exposed to Cd. Similar antibiotic treatments of E. gracilis cultures had variable or non-significant impacts on Cd tolerance. E. gracilis also recovered better after pre-treatment with antibiotics and Cd than did E. mutabilis. The recoveries were assessed by heterotrophic growth without antibiotics or Cd. In contrast, both Euglena species displayed increased chlorophyll production upon Cd exposure. PacBio full-length amplicon sequencing and targeted Sanger sequencing identified the microbial species present in the E. mutabilis culture to be the fungus Talaromyces sp. and the bacterium Acidiphilium acidophilum., Conclusion: This study uncovers a possible fungal, algal, and bacterial relationship, what we refer to as a FAB consortium. The members of this consortium interact to enhance the response to Cd exposure. This results in a E. mutabilis culture that has a higher tolerance to Cd than the axenic E. gracilis. The description of this interaction provides a basis for explore the benefits of natural interactions. This will provide knowledge and direction for use when creating or maintaining FAB interactions for biotechnological purposes, including bioremediation., (© 2024. The Author(s).)

Heavy metal (HM) pollution threatens human and ecosystem health. Current methods for remediating water contaminated with HMs are expensive and have limited effect. Therefore, bioremediation is being investigated as an environmentally and economically viable alternative. Freshwater protists Euglena gracilis and Euglena mutabilis were investigated for their tolerance to cadmium (Cd). A greater increase in cell numbers under Cd stress was noted for E. mutabilis but only E. gracilis showed an increase in Cd tolerance following pre-treatment with elevated concentrations of S or N. To gain insight regarding the nature of the increased tolerance RNA-sequencing was carried out on E. gracilis. This revealed transcript level changes among pretreated cells, and additional differences among cells exposed to CdCl 2 . Gene ontology (GO) enrichment analysis reflected changes in S and N metabolism, transmembrane transport, stress response, and physiological processes related to metal binding. Identifying these changes enhances our understanding of how these organisms adapt to HM polluted environments and allows us to target development of future pre-treatments to enhance the use of E. gracilis in bioremediation relating to heavy metals., (© 2024. The Author(s).)

Diesel, as a toxic and complex pollutant, is one of the main components in oily wastewater, and poses serious threats to the aquatic environment and the health of organisms. Employing environmentally friendly biostimulants to enhance the metabolic functions of microorganisms is currently the optimal choice to improve the biodegradation of oil-containing wastewater efficiency. This study takes Pseudomonas aeruginosa LNR1 as the target, analyzing the physiological responses and molecular mechanisms of biofilm formation when enhanced by the extracellular metabolites of euglena (EME) for diesel degradation. The results show that EME not only induces auto-aggregation behavior of strain LNR1, forming aerobic suspended granule biofilm, but also promotes the secretion of signaling molecules in the quorum sensing (QS) system. Transcriptomic and proteomic analyses indicate that the stimulatory effect of EME on strain LNR1 mainly manifests in biofilm formation, substance transmembrane transport, signal transduction, and other biological processes, especially the QS system in signal transduction, which plays a significant regulatory role in biofilm formation, chemotaxis, and two-component system (TCS). This study collectively unveils the molecular mechanisms of biostimulant EME inducing strain LNR1 to enhance diesel degradation from different aspects, providing theoretical guidance for the practical application of EME in oily wastewater pollution control., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Herein we describe a new photosynthetic euglenoid species found in Poland - Euglena mazurica. A large population exists in a small, eutrophic body of water located in a pasture near Mikołajki town inside the Masurian Landscape Park (covering a part of the Masurian Lake District in Poland). The unique cell shape (corkscrew-like) discerns it well from other previously described euglenoid species with metabolic cells. The new species possesses two plate-like chloroplasts each with a pyrenoid accompanied by two paramylon caps placed on either side of it (diplopyrenoids). On the phylogenetic tree, the new species is situated within the Euglena clade. Though it is a sister branch to three clades - one representing the similar Euglena agilis, characterized by its fusiform cells and two chloroplasts with diplopyrenoids, the two species are clearly morphologically and molecularly distinct., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier GmbH.)

Euglena gracilis produces ATP in the anaerobic mitochondria with concomitant wax ester formation, and NADH is essential for ATP formation and fatty acid synthesis in the mitochondria. This study demonstrated that mitochondrial cofactor conversion by nicotinamide nucleotide transhydrogenase (NNT), converting NADPH/NAD + to NADP + /NADH, is indispensable for sustaining anaerobic metabolism. Silencing of NNT genes significantly decreased wax ester production and cellular viability during anaerobiosis but had no such marked effects under aerobic conditions. An analogous phenotype was observed in the silencing of the gene encoding a mitochondrial NADP + -dependent malic enzyme. These results suggest that the reducing equivalents produced in glycolysis are shuttled to the mitochondria as malate, where cytosolic NAD + regeneration is coupled with mitochondrial NADPH generation., (© 2021 The Authors. FEBS Letters published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Single-cell metabolite analysis plays an important role in biological study. While mass spectrometry is a powerful tool for identification and quantitation of metabolites, the low absolute analyte amounts in single cell and difficulty in sampling represent significant challenges in single cell analysis. In this study, we developed an effective method with a simple sampling procedure for analyzing single cells. A single cell was driven to a capillary tip through electro-migration, followed by releasing the cell contents through electroporation, into a sealed small volume (∼1.5 pL) to prevent dilution. Subsequent mass spectrometry analysis was performed directly with nanoelectrospray ionization. This method was applied for analyzing a variety of cells and monitoring the metabolic changes in response to perturbed cell culturing conditions. This method opens a new avenue for easy and rapid analysis of single cells with high sensitivity.

For carotenogenesis, two biosynthetic pathways from phytoene to lycopene are known. Most bacteria and fungi require only phytoene desaturase (PDS, CrtI), whereas land plants require four enzymes: PDS (CrtP), ζ-carotene desaturase (ZDS, CrtQ), ζ-carotene isomerase (Z-ISO) and cis-carotene isomerase (CrtISO, CrtH). The gene encoding Z-ISO has been functionally identified in only two species, Arabidopsis thaliana and Zea mays, and has been little studied in other organisms. In this study, we found that the deduced amino acid sequences of Arthrospira Z-ISO and Euglena Z-ISO have 58% and 62% identity, respectively, with functional Z-ISO from Arabidopsis. We studied the function of Z-ISO genes from the cyanobacterium Arthrospira platensis and eukaryotic microalga Euglena gracilis. The Z-ISO genes of Arthrospira and Euglena were transformed into Escherichia coli strains that produced mainly 9,15,9'-tri-cis-ζ-carotene in darkness. In the resulting E. coli transformants cultured under darkness, 9,9'-di-cis-ζ-carotene was accumulated predominantly as Z-ISO in Arabidopsis. This indicates that the Z-ISO genes were involved in the isomerization of 9,15,9'-tri-cis-ζ-carotene to 9,9'-di-cis-ζ-carotene in darkness. This is the first functional analysis of Z-ISO as a ζ-carotene isomerase in cyanobacteria and eukaryotic microalgae. Green sulfur bacteria and Chloracidobacterium also use CrtP, CrtQ and CrtH for lycopene synthesis as cyanobacteria, but their genomes did not comprise Z-ISO genes. Consequently, Z-ISO is needed in oxygenic phototrophs, whereas it is not found in anoxygenic species., (© The Author(s) 2019. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

In nature, protozoa play a major role in controlling bacterial populations. This paper proposes a microfluidic device for the study of protozoa behaviors change due to their chemotactic response in the presence of bacterial cells. A three-channel microfluidic device was designed using a nitrocellulose membrane into which channels were cut using a laser cutter. The membrane was sandwiched between two glass slides; a Euglena suspension was then allowed to flow through the central channel. The two side channels were filled with either, 0.1% peptone as a negative control, or a Listeria suspension respectively. The membrane design prevented direct interaction but allowed Euglena cells to detect Listeria cells as secretions diffused through the nitrocellulose membrane. A significant number of Euglena cells migrated toward the chambers near the bacterial cells, indicating a positive chemotactic response of Euglena toward chemical cues released from Listeria cells. Filtrates collected from Listeria suspension with a series of molecular weight cutoffs (3k, 10k and 100k) were examined in Euglena chemotaxis tests. Euglena cells were attracted to all filtrates collected from the membrane filtration with different molecular weight cutoffs, suggesting small molecules from Listeria might be the chemical cues to attract protozoa. Headspace volatile organic compounds (VOC) released from Listeria were collected, spiked to 0.1% peptone and tested as the chemotactic effectors. It was discovered that the Euglena cells responded quickly to Listeria VOCs including decanal, 3,5- dimethylbenzaldehyde, ethyl acetate, indicating bacterial VOCs were used by Euglena to track the location of bacteria., Competing Interests: The authors have declared that no competing interests exist.

Purpose: To test the effects of short-term exposure of aquatic organisms to electric field (EF) with negligible magnetic component., Materials and Methods: We built a plate capacitor that served as a source of EF of strengths that can be found in nature near transmission lines. We exposed two cultured protist species Euglena viridis and Paramecium caudatum to EFs for 24 hours and monitored their abundance, morphology, intracellular superoxide anion (by dihydroethidium [DHE]), hydrogen peroxide by (H 2 DCF) and lipid peroxidation (MDA) contents, catalase (CAT) and superoxide dismutase (SOD) activity., Results: We found that even short-term exposure to low strength EF causes changes in population abundance, morphology and oxidative stress response in both species. As the EF strength increased, abundance of both species decreased. However, at weaker EFs, fission rates were seemingly promoted. We noted a decrease in size in both organisms in directions perpendicular to their fission planes correlated with EF strength. DHE and H 2 DCF fluorescence intensity and SOD activity were higher in organisms exposed to the stronger EFs., Conclusions: We suggest that the electric component of the field, rather than the magnetic, is the main cause of all the noted effects. As a result, aquatic organisms should be given greater importance in studies assessing the effects of EMFs in spite of the attenuating effects of water to EF strengths.

Euglena sanguinea is known to produce the alkaloid toxin euglenophycin and is known to cause fish kills and inhibit mammalian tissue and microalgal culture growth. An analysis of over 30 species of euglenoids for accumulation of euglenophycin identified six additional species producing the toxin; and six of the seven E. sanguinea strains produced the toxin. A phylogenetic assessment of these species confirmed most taxa were in the Euglenaceae, whereas synthesis capability apparently has been lost in the Phacus, Eutreptiella, and Discoplastis branches., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Euglenoids are able to assimilate fatty acids and alcohols with various carbon-chain lengths, and ethanol is known to be one of the best carbon sources to support the growth of Euglena gracilis. Ethanol is first oxidized to acetate by the sequential reactions of alcohol dehydrogenase and acetaldehyde dehydrogenase in the mitochondria, and then converted to acetyl coenzyme A (acetyl-CoA). Acetyl-CoA is metabolized through the glyoxylate cycle which is a modified tricarboxylic acid (TCA) cycle in which isocitrate lyase (ICL) and malate synthase (MS) function to bypass the two decarboxylation steps of the TCA cycle, enabling the net synthesis of carbohydrates from C2 compounds. ICL and MS form a unique bifunctional enzyme localized in Euglena mitochondria, not in glyoxysome as in other eukaryotes. The unique glyoxylate and glycolate metabolism during photorespiration is also discussed in this chapter.

In Euglena cells under anaerobic conditions, paramylon, the storage polysaccharide, is promptly degraded and converted to wax esters. The wax esters synthesized are composed of saturated fatty acids and alcohols with chain lengths of 10-18, and the major constituents are myristic acid and myristyl alcohol. Since the anaerobic cells gain ATP through the conversion of paramylon to wax esters, the phenomenon is named "wax ester fermentation". The wax ester fermentation is quite unique in that the end products, i.e. wax esters, have relatively high molecular weights, are insoluble in water, and accumulate in the cells, in contrast to the common fermentation end products such as lactic acid and ethanol.A unique metabolic pathway involved in the wax ester fermentation is the mitochondrial fatty acid synthetic system. In this system, fatty acid are synthesized by the reversal of β-oxidation with an exception that trans-2-enoyl-CoA reductase functions instead of acyl-CoA dehydrogenase. Therefore, acetyl-CoA is directly used as a C 2 donor in this fatty acid synthesis, and the conversion of acetyl-CoA to malonyl-CoA, which requires ATP, is not necessary. Consequently, the mitochondrial fatty acid synthetic system makes possible the net gain of ATP through the synthesis of wax esters from paramylon. In addition, acetyl-CoA is provided in the anaerobic cells from pyruvate by the action of a unique enzyme, oxygen sensitive pyruvate:NADP + oxidoreductase, instead of the common pyruvate dehydrogenase multienzyme complex.Wax esters produced by anaerobic Euglena are promising biofuels because myristic acid (C 14:0 ) in contrast to other algal produced fatty acids, such as palmitic acid (C 16:0 ) and stearic acid (C 18:0 ), has a low freezing point making it suitable as a drop-in jet fuel. To improve wax ester production, the molecular mechanisms by which wax ester fermentation is regulated in response to aerobic and anaerobic conditions have been gradually elucidated by identifying individual genes related to the wax ester fermentation metabolic pathway and by comprehensive gene/protein expression analysis. In addition, expression of the cyanobacterial Calvin cycle fructose-1,6-bisphosphatase/sedohepturose-1,7-bisphosphatase, in Euglena provided photosynthesis resulting in increased paramylon accumulation enhancing wax ester production. This chapter will discuss the biochemistry of the wax ester fermentation, recent advances in our understanding of the regulation of the wax ester fermentation and genetic engineering approaches to increase production of wax esters for biofuels.

Background: Microalgae have been recognized as a good food source of natural biologically active ingredients. Among them, the green microalga Euglena is a very promising food and nutritional supplements, providing high value-added poly-unsaturated fatty acids, paramylon and proteins. Different culture conditions could affect the chemical composition and food quality of microalgal cells. However, little information is available for distinguishing the different cellular changes especially the active ingredients including poly-saturated fatty acids and other metabolites under different culture conditions, such as light and dark., Results: In this study, together with fatty acid profiling, we applied a gas chromatography-mass spectrometry (GC-MS)-based metabolomics to differentiate hetrotrophic and mixotrophic culture conditions., Conclusions: This study suggests metabolomics can shed light on understanding metabolomic changes under different culture conditions and provides a theoretical basis for industrial applications of microalgae, as food with better high-quality active ingredients.

The daily photosynthetic performance of a natural biofilm of the extreme acidophilic Euglena mutabilis from Río Tinto (SW, Spain) under full solar radiation was analyzed by means of pulse amplitude-modulated (PAM) fluorescence measurements and metatrascriptomic analysis. Natural E. mutabilis biofilms undergo large-scale transcriptomic reprogramming during midday due to a dynamic photoinhibition and solar radiation stress. Photoinhibition is due to UV radiation and not to light intensity, as revealed by PAM fluorometry analysis. In order to minimize the negative effects of solar radiation, our data supports the presence of a circadian rhythm in this euglenophyte that increases their opportunity to survive. Differential gene expression throughout the day (at 12:00, 20:00 and night) was monitored by massive Illumina parallel sequencing of metatranscriptomic libraries. The transcription pattern was altered in genes involved in Photosystem II stability and repair, UV damaged DNA repair, non-photochemical quenching and oxidative stress, supporting the photoinhibition detected by PAM fluorometry at midday., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

Confocal fluorescence microscopy and electron microscopy (EM) are complementary methods for studying the intracellular localization of proteins. Confocal fluorescence microscopy provides a rapid and technically simple method to identify the organelle in which a protein localizes but only EM can identify the suborganellular compartment in which that protein is present. Confocal fluorescence microscopy, however, can provide information not obtainable by EM but required to understand the dynamics and interactions of specific proteins. In addition, confocal fluorescence microscopy of cells transfected with a construct encoding a protein of interest fused to a fluorescent protein tag allows live cell studies of the subcellular localization of that protein and the monitoring in real time of its trafficking. Immunostaining methods for confocal fluorescence microscopy are also faster and less involved than those for EM allowing rapid optimization of the antibody dilution needed and a determination of whether protein antigenicity is maintained under fixation conditions used for EM immunogold labeling. This chapter details a method to determine by confocal fluorescence microscopy the intracellular localization of a protein by transfecting the organism of interest, in this case Giardia lamblia, with the cDNA encoding the protein of interest and then processing these organisms for double label immunofluorescence staining after chemical fixation. Also presented is a method to identify the organelle targeting information in the presequence of a precursor protein, in this case the presequence of the precursor to the Euglena light harvesting chlorophyll a/b binding protein of photosystem II precursor (pLHCPII), using live cell imaging of mammalian COS7 cells transiently transfected with a plasmid encoding a pLHCPII presequence fluorescent protein fusion and stained with organelle-specific fluorescent dyes.

Eukaryotic microalgae are an incredibly diverse group of organisms whose sole unifying feature is their ability to photosynthesize. They are known for producing a range of potent toxins, which can build up during harmful algal blooms causing damage to ecosystems and fisheries. Genome sequencing is lagging behind in these organisms because of their genetic complexity, but transcriptome sequencing is beginning to make up for this deficit. As more sequence data becomes available, it is apparent that eukaryotic microalgae possess a range of complex natural product biosynthesis capabilities. Some of the genes concerned are responsible for the biosynthesis of known toxins, but there are many more for which we do not know the products. Bioinformatic and analytical techniques have been developed for natural product discovery in bacteria and these approaches can be used to extract information about the products synthesized by algae. Recent analyses suggest that eukaryotic microalgae produce many complex natural products that remain to be discovered., (© 2016 Elsevier Inc. All rights reserved.)

Background and Aims: In photosynthetic organisms exposure to high light induces the production of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), which in part is prevented by non-photochemical quenching (NPQ). As one of the most stable and longest-lived ROS, H2O2 is involved in key signalling pathways in development and stress responses, although in excess it can induce damage. A ubiquitous response to high light is the induction of the xanthophyll cycle, but its role in algae is unclear as it is not always associated with NPQ induction. The aim of this study was to reveal how diurnal changes in the level of H2O2 are regulated in a freshwater algal community., Methods: A natural freshwater community of algae in a temporary rainwater pool was studied, comprising photosynthetic Euglena species, benthic Navicula diatoms, Chlamydomonas and Chlorella species. Diurnal measurements were made of photosynthetic performance, concentrations of photosynthetic pigments and H2O2. The frequently studied model organisms Chlamydomonas and Chlorella species were isolated to study photosynthesis-related H2O2 responses to high light., Key Results: NPQ was shown to prevent H2O2 release in Chlamydomonas and Chlorella species under high light; in addition, dissolved organic carbon excited by UV-B radiation was probably responsible for a part of the H2O2 produced in the water column. Concentrations of H2O2 peaked at 2 µm at midday and algae rapidly scavenged H2O2 rather than releasing it. A vertical H2O2 gradient was observed that was lowest next to diatom-rich benthic algal mats. The diurnal changes in photosynthetic pigments included the violaxanthin and diadinoxanthin cycles; the former was induced prior to the latter, but neither was strictly correlated with NPQ., Conclusions: The diurnal cycling of H2O2 was apparently modulated by the organisms in this freshwater algal community. Although the community showed flexibility in its levels of NPQ, the diurnal changes in xanthophylls correlated with H2O2 concentrations. Alternative NPQ mechanisms in algae involving proteins of the light-harvesting complex type and antioxidant protection of the thylakoid membrane by de-epoxidized carotenoids are discussed., (© The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Arsenic is a toxic metalloid known to cause multiple and severe cellular damages, including lipid peroxidation, protein misfolding, mutagenesis and double and single-stranded DNA breaks. Thus, exposure to this compound is lethal for most organisms but some species such as the photosynthetic protist Euglena mutabilis are able to cope with very high concentrations of this metalloid. Our comparative transcriptomic approaches performed on both an arsenic hypertolerant protist, i.e. E. mutabilis, and a more sensitive one, i.e. E. gracilis, revealed multiple mechanisms involved in arsenic tolerance. Indeed, E. mutabilis prevents efficiently the accumulation of arsenic in the cell through the expression of several transporters. More surprisingly, this protist induced the expression of active DNA reparation and protein turnover mechanisms, which allow E. mutabilis to maintain functional integrity of the cell under challenging conditions. Our observations suggest that this protist has acquired specific functions regarding arsenic and has developed an original metabolism to cope with acid mine drainages-related stresses., (© 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.)

Euglenoid flagellates are mainly fresh water protists growing in highly diverse environments making them well-suited for a multiplicity of biotechnology applications. Phototrophic euglenids possesses complex chloroplasts of green algal origin bounded by three membranes. Euglena nuclear and plastid genome organization, gene structure and gene expression are distinctly different from other organisms. Our observations on the model organism Euglena gracilis indicate that transcription of both the plastid and nuclear genome is insensitive to environmental changes and that gene expression is regulated mainly at the post-transcriptional level. Euglena plastids have been proposed as a site for the production of proteins and value added metabolites of biotechnological interest. Euglena has been shown to be a suitable protist species to be used for production of several compounds that are used in the production of cosmeceuticals and nutraceuticals, such as α-tocopherol, wax esters, polyunsaturated fatty acids, biotin and tyrosine. The storage polysaccharide, paramylon, has immunostimulatory properties and has shown a promise for biomaterials production. Euglena biomass can be used as a nutritional supplement in aquaculture and in animal feed. Diverse applications of Euglena in environmental biotechnology include ecotoxicological risk assessment, heavy metal bioremediation, bioremediation of industrial wastewater and contaminated water., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Extracellular and intracellular biosynthesis of silver nanoparticles (AgNPs) by Euglena gracilis (EG) strain and Euglena intermedia (EI) strain are reported in this study. The obtained nanoparticles showed an absorption peak approximates 420 nm in the UV-visible spectrum, corresponding to the plasmon resonance of AgNPs. According to the result of inductively coupled plasma-atomic emission spectrometer, the intakes of silver ions by EI and EG are roughly equal. The transmission electron microscope (TEM) analysis of the successful in vivo and in vitro synthesised AgNPs indicated the sizes, ranging from 6 to 24 nm and 15 to 60 nm in diameter, respectively, and a spherical-shaped polydispersal of the particles. The successful formation of AgNPs has been confirmed by energy dispersive X-ray analysis connected to the TEM. The Fourier transform infrared spectroscopy measurements reveal the presence of bioactive functional groups such as amines are found to be the capping and stabilising agents of nanoparticles. To our knowledge, this is the first report where two kinds of Euglena microalga were used as the potential source for in vivo and in vitro biosynthesis of AgNPs.

Euglena gracilis is a microalgae used as a model organism. Recently, mass cultivation of this species has been achieved for industrial applications. The genus Euglena includes more than 200 species that share common useful features, but the potential industrial applications of other Euglena species have not been evaluated. Thus, we conducted a pilot screening study to identify other species that proliferate at a sufficiently rapid rate to be used for mass cultivation; we found that Euglena anabaena var. minor had a rapid growth rate. In addition, its cells accumulated more than 40% weight of carbohydrate, most of which is considered to be a euglenoid specific type of beta-1-3-glucan, paramylon. Carbohydrate is stored in E. anabaena var. minor cells during normal culture, whereas E. gracilis requires nitrogen limitation to facilitate paramylon accumulation. These results suggest the potential industrial application of E. anabaena var. minor.

The PsbP and PsbQ proteins are extrinsic subunits of the photosystem II in eukaryotic photosynthetic organisms including higher plants, green algae and euglena. It has been suggested that PsbP and PsbQ have evolved from their cyanobacterial homologs, while considerable genetic and functional modifications have occurred to generate the eukaryote-type proteins. In addition, number of PsbP and PsbQ homologs exist in the thylakoid lumen of chloroplasts. These homologs are nuclear-encoded and likely diverged by gene duplication, and recent studies have elucidated their various functions in the photosynthetic machinery. In this short review, recent findings and new idea about these components will be discussed., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

The microalga Euglena was selected as a bioindicator for determining genotoxicity potencies of organic pollutants in Meiliang Bay of Taihu Lake, Jiangsu, China among seasons in 2008. Several methods, including the comet assay to determine breaks in DNA and quantification of antioxidant enzymes were applied to characterize genotoxic effects of organic extracts of water from Taihu Lake on the flagellated, microalga Euglena gracilis. Contents of photosynthetic pigments, including Chl a, Chl b and carotenoid pigments were inversely proportion to concentrations of organic extracts to which E. gracilis was exposed. Organic extracts of Taihu Lake water also affected activities of superoxide dismutase (SOD) and peroxidase (POD) of E. gracilis. There were no statistically significant differences in SOD activities among seasons except in June but significant differences in POD activities were observed among all seasons. The metrics of DNA fragmentation in the alkaline unwinding assay (Comet assay), olive tail moment (OTM) and tail moment (TM), used as measurement endpoints during the genotoxicity assay were both greater when E. gracilis was exposed to organic of water collected from Taihu Lake among four seasons. It is indicated that the comet assay was useful for determining effects of constituents of organic extracts of water on E. gracilis and this assay was effective as an early warning to organic pollutants.

Euglena mutabilis is a photosynthetic protist found in acidic aquatic environments such as peat bogs, volcanic lakes and acid mine drainages (AMDs). Through its photosynthetic metabolism, this protist is supposed to have an important role in primary production in such oligotrophic ecosystems. Nevertheless, the exact contribution of E. mutabilis in organic matter synthesis remains unclear and no evidence of metabolite secretion by this protist has been established so far. Here we combined in situ proteo-metabolomic approaches to determine the nature of the metabolites accumulated by this protist or potentially secreted into an AMD. Our results revealed that the secreted metabolites are represented by a large number of amino acids, polyamine compounds, urea and some sugars but no fatty acids, suggesting a selective organic matter contribution in this ecosystem. Such a production may have a crucial impact on the bacterial community present on the study site, as it has been suggested previously that prokaryotes transport and recycle in situ most of the metabolites secreted by E. mutabilis. Consequently, this protist may have an indirect but important role in AMD ecosystems but also in other ecological niches often described as nitrogen-limited.

The relationship between protozoan biomass concentration and phosphate and nitrate removal was investigated in mixed liquor using three different carbon sources as supplements. The study was carried out using three respective initial biomass concentrations in a shaking flask environment. Samples were taken every 24 h to determine phosphate, nitrate, dissolved oxygen and chemical oxygen demand. The results revealed a direct relationship between decreases in nutrient concentrations and increases in cell densities of the isolates. Between 24 and 96 h, the increases in the protozoan density corresponded to a phosphate decreases from initial ranges of 55.42-57.36 mg/L, 50.27-51.17 mg/L and 50.01-50.83 mg/L to final ranges of 2.46-11.90 mg/L, 0.61-11.80 mg/L and 1.29-13.89 mg/L, in the presence of Aspidisca, Trachelophyllum and Peranema, respectively. Nitrate concentrations were observed to decrease from initial ranges of 23.84-25.90 mg/L, 23.94-25.84 mg/L and 26.12-26.54 mg/L to final ranges of 0.11-6.32 mg/L, 0.16-5.60 mg/L and 0.24-9.04 mg/L, respectively. The study had revealed that an increase in cell density of the test isolates produces a corresponding increase in phosphate and nitrate removal.

To observe and control cultivation processes, optical sensors are used increasingly. Important variables for controlling such processes are cell count, cell size distribution and the morphology of cells. Among turbidity measurement methods, imaging procedures are applied for determining these process values. A disadvantage of most previously developed imaging procedures is that they are only available offline, which requires sampling. On the other hand, available imaging inline probes can only deliver a limited number of process values so far. This contribution gives an overview of optical procedures for the inline determination of cell count, cell size distribution and other variables. In particular, by in situ microscopy, an imaging procedure will be described, which allows the determination of direct and non-direct cell variables in real time without sampling.

Motile microorganisms react to a host of external stimuli, including light, gravity, the magnetic field of the Earth as well as thermal and chemical gradients, in their habitat in order to select a niche suitable for survival and reproduction. Several forms of light-induced behavior have been described in microorganisms including phototaxis, photophobic responses, and photokinesis. Other functions of photoreceptors are regulation of development and entrainment of circadian rhythms. Basically five types of photoreceptor molecules have been identified in microorganisms: BLUF proteins, cryptochromes, phototropins, phytochromes, and rhodopsins. The photoreceptors can control light-activated ion channels or activated enzymes. The responses to the different stimuli in their habitat can be connected in a complex network of signal transduction chains.

Euglena gracilis possesses a simple but sophisticated light detecting system, consisting of an eyespot formed by carotenoids globules and a photoreceptor. The photoreceptor of Euglena is characterized by optical bistability, with two stable states. In order to provide important and discriminating information on the series of structural changes that Euglena photoreceptive protein(s) undergoes inside the photoreceptor in response to light, we measured the in vivo absorption spectra of the two stable states A and B of photoreceptor photocycle. Data were collected using two different devices, i.e. a microspectrophotometer and a digital microscope. Our results show that the photocycle and the absorption spectra of the photoreceptor possess strong spectroscopic similarities with a rhodopsin-like protein. Moreover, the analysis of the absorption spectra of the two stable states of the photoreceptor and the absorption spectrum of the eyespot suggests an intriguing hypothesis for the orientation of microalgae toward light.

In this paper, optimization of biological decolorization of synthetic dye solution containing Malachite Green was investigated. The effect of temperature, initial pH of the solution, type of algae, dye concentration and time of the reaction was studied and optimized using Taguchi method. Sixteen experiments were required to study the effect of parameters on biodegradation of the dye. Each of experiments was repeated three times to calculate signal/noise (S/N). Our results showed that initial pH of the solution was the most effective parameter in comparison with others and the basic pH was favorable. In this study, we also optimized the experimental parameters and chose the best condition by determination effective factors. Based on the S/N ratio, the optimized conditions for dye removal were temperature 25 degrees C, initial pH 10, dye concentration 5 ppm, algae type Chlorella and time 2.5h. The stability and efficiency of Chlorella sp. in long-term repetitive operations were also examined.

Proteins are delivered to Euglena chloroplasts using the secretory pathway. We describe analytical methods to study the intracellular trafficking of Euglena chloroplast proteins and a method to isolate preparative amounts of intact import competent chloroplasts for biochemical studies. Cells are pulse labeled with 35S-sulfate and chased with unlabeled sulfate allowing the trafficking and posttranslational processing of the labeled protein to be followed. Sucrose gradients are used to separate a 35S-labeled cell lysate into cytoplasmic, endoplasmic reticuum (ER), Golgi apparatus, chloroplast and mitochondrial fractions. Immunoprecipitation of each gradient fraction allows identification of the intracellular compartment containing a specific 35S-labeled protein at different times after synthesis delineating the trafficking pathway. Because sucrose gradients cannot be used to isolate preparative amounts of highly purified chloroplasts for biochemical characterization, a preparative high-yield procedure using Percoll gradients to isolate highly purified import competent chloroplasts is also presented.

Eukaryotic cells are characterized by the presence of a number of membrane-bound organelles which have differing degrees of internal structure. After synthesis in the cytoplasm, proteins must be targeted to the appropriate organelle and localized to the correct suborganellular compartment. We describe a method for immunoelectron microscopy that can be used to localize a protein not only to the correct organelle but to the appropriate suborganellular compartment. Cells are fixed to preserve subcellular structures and ultrathin sections are labeled with a monospecific antibody to the protein of interest. Protein-A gold is used to visualize the antigen-antibody complex by transmission electron microscopy allowing the intracellular location of the antigen to be determined. The methodology described was developed to study protein localization in Euglena but it is applicable to most organisms.

To assess the expression and physiological role of the mitochondrial NAD(+)-independent lactate dehydrogenase (iLDH) in Euglena gracilis, cells were grown with different carbon sources, and the d- and l-iLDH activities and several key metabolic intermediates were examined. iLDH activity was significant throughout the growth period, increasing by three- to fourfold from latency to the stationary phase. Intracellular levels of D- and L-lactate were high (5-40 mm) from the start of the culture and increased (20-80 mm) when the stationary phase was entered. All external carbon sources were actively consumed, reaching a minimum upon entering the stationary phase, when degradation of paramylon started. The level of ATP was essentially unchanged under all experimental conditions. Oxalate, an inhibitor of iLDH, strongly inhibited oligomycin-sensitive respiration and growth, whereas rotenone, an inhibitor of respiratory complex I, only slightly affected these parameters in lactate-grown cells. Isolated mitochondria exhibited external NADH-supported respiration, which was sensitive to rotenone and flavone, and an inability to oxidize pyruvate. Addition of cytosol, NADH and pyruvate to mitochondria incubated with rotenone and flavone prompted significant O2 uptake, which was blocked by oxalate. The data suggested that iLDH expression in Euglena is independent of substrate availability and that iLDHs play a key role in the transfer of reducing equivalents from the cytosol to the respiratory chain (lactate shuttle).

Previous studies using the nuclear SSU rDNA have indicated that the photosynthetic euglenoids are a monophyletic group; however, some of the genera within the photosynthetic lineage are not monophyletic. To test these results further, evolutionary relationships among the photosynthetic genera were investigated by obtaining partial LSU nuclear rDNA sequences. Taxa from each of the external clades of the SSU rDNA-based phylogeny were chosen to create a combined dataset and to compare the individual LSU and SSU rDNA datasets. Conserved areas of the aligned sequences for both the LSU and SSU rDNA were used to generate parsimony, log-det, maximum-likelihood and Bayesian trees. The SSU and LSU rDNA consistently generated the same seven terminal clades; however, the relationship among those clades varied depending on the type of analysis and the dataset used. The combined dataset generated a more robust phylogeny, but the relationships among clades still varied. The addition of the LSU rDNA dataset to the euglenophyte phylogeny supports the view that the genera Euglena, Lepocinclis and Phacus are not monophyletic and substantiates the existence of several well-supported clades. A secondary structural model for the D2 region of the LSU rDNA was proposed on the basis of compensatory base changes found in the alignment.

The psbO gene encoding the extrinsic 33 kDa protein of oxygen-evolving photosystem II (PSII) complex was cloned and sequenced from a red alga, Cyanidium caldarium. The gene encodes a polypeptide of 333 residues, of which the first 76 residues served as transit peptides for transfer across the chloroplast envelope and thylakoid membrane. The mature protein consists of 257 amino acids with a calculated molecular mass of 28,290 Da. The sequence homology of the mature 33 kDa protein was 42.9-50.8% between the red alga and cyanobacteria, and 44.7-48.6% between the red alga and higher plants. The cloned gene was expressed in Escherichia coli, and the recombinant protein was purified, subjected to protease-treatments. The cleavage sites of the 33 kDa protein by chymotrypsin or V8 protease were determined and compared among a cyanobacterium (Synechococcus elongatus), a euglena (Euglena gracilis), a green alga (Chlamydomonas reinhardtii) and two higher plants (Spinacia oleracea and Oryza sativa). The cleavage sites by chymotrypsin were at 156F and 190F for the cyanobacterium, 159M, 160F and 192L for red alga, 11Y and 151F for euglena, 10Yand 150F for green alga, and 16Y for spinach, respectively. The cleavage sites by V8 protease were at 181E (cyanobacterium), 182E and 195E (red alga), 13E, 67E, 69E, 153D and 181E (euglena), 176E and 180E (green alga), and 18E or 19E (higher plants). Since most of the residues at these cleavage sites were conserved among the six organisms, the results indicate that the structure of the 33 kDa protein, at least the structure based on the accessibility by proteases, is different among these organisms. In terms of the cleavage sites, the structure of the 33 kDa protein can be divided into three major groups: cyanobacterial and red algal-type has cleavage sites at residues around 156-195, higher plant-type at residues 16-19, and euglena and green algal-type at residues of both cyanobacterial and higher plant-types.

It is currently thought that chloroplasts of higher plants were derived from endosymbiont oxygenic photosynthetic bacteria (primary endosymbiosis), while Euglena, a photosynthetic protista, gained chloroplasts by secondary endosymbiosis (i.e., incorporation of a photosynthetic eukaryote into heterotrophic eukaryotic host). To examine if the protein transport inside chloroplasts is similar between these organisms, we carried out heterologous protein import experiments with Euglena precursor proteins and spinach chloroplasts. The precursor of a 30-kDa subunit of the oxygen-evolving complex (OEC30) from the thylakoid lumen of Euglena chloroplasts contained the N-terminal signal, stroma targeting, and thylakoid transfer domains. Truncated preOEC30s lacking the N-terminal domain were post-translationally imported into spinach chloroplasts, transported into the thylakoid lumen, and processed to a mature protein. These results showed that protein translocations within chloroplasts in Euglena and higher plants are similar and supported the hypothesis that Euglena chloroplasts are derived from the ancestral Chlorophyta., (Copyright 2000 Academic Press.)

The effect of antimycin, myxothiazol, 2-heptyl-4-hydroxyquinoline-N-oxide, stigmatellin and cyanide on respiration, ATP synthesis, cytochrome c reductase, and membrane potential in mitochondria isolated from dark-grown Euglena cells was determined. With L-lactate as substrate, ATP synthesis was partially inhibited by antimycin, but the other four inhibitors completely abolished the process. Cyanide also inhibited the antimycin-resistant ATP synthesis. Membrane potential was collapsed (<60 mV) by cyanide and stigmatellin. However, in the presence of antimycin, a H(+)60 mV) that sufficed to drive ATP synthesis remained. Cytochrome c reductase, with L-lactate as donor, was diminished by antimycin and myxothiazol. Cytochrome bc(1) complex activity was fully inhibited by antimycin, but it was resistant to myxothiazol. Stigmatellin inhibited both L-lactate-dependent cytochrome c reductase and cytochrome bc(1) complex activities. Respiration was partially inhibited by the five inhibitors. The cyanide-resistant respiration was strongly inhibited by diphenylamine, n-propyl-gallate, salicylhydroxamic acid and disulfiram. Based on these results, a model of the respiratory chain of Euglena mitochondria is proposed, in which a quinol-cytochrome c oxidoreductase resistant to antimycin, and a quinol oxidase resistant to antimycin and cyanide are included.

The effects of ultraviolet radiation (UV-A, 315-400 nm plus UV-B, 280-315 nm) on photosynthesis and 'light-enhanced dark respiration' (LEDR) in Euglena gracilis have been investigated by using light pulses (80 s) with increasing photon fluence rates of 59, 163, 600, 1180, 2080 and 3340 micromol m(-2) s(-1) and dark periods between the light pulses. LEDR is estimated as the maximum rate of oxygen consumption after a period of light minus the rate of oxygen consumption 30 s after the maximum rate. Without any exposure to UV radiation, the photosynthetic rate and LEDR increase with increasing photon fluence rate. After 20 and 40 min exposures to UV radiation, the photosynthetic rate and LEDR as functions of photon fluence rate are reduced. After a 20 min UV treatment respiration is greater than photosynthesis after the first light pulse of 59 micromol m(-2) s(-1) radiation, and especially at higher photon fluence rates photosynthesis is lower than the control values. The inhibitory effects of UV radiation on photosynthetic rate and LEDR are greater after a 40 min UV exposure than after a 20 min exposure. Only at 600 micromol m(-2) s(-1) is the rate of oxygen evolution greater than that of oxygen consumption after a 40 min UV treatment. Both photosynthetic rate and LEDR are inhibited by the photosynthetic inhibitor DCMU (10(-5) M) in a similar way, which indicates close regulatory interactions between photosynthesis and LEDR. Potassium cyanide (KCN) inhibits dark respiration more than it inhibits LEDR. Dark respiration is not affected to the same degree by UV radiation as are photosynthesis and LEDR.

Euglena chloroplast protein precursors are transported as integral membrane proteins from the endoplasmic reticulum (ER) to the Golgi apparatus prior to chloroplast localization. All Euglena chloroplast protein precursors have functionally similar bipartite presequences composed of an N-terminal signal peptide domain and a stromal targeting domain containing a hydrophobic region approximately 60 amino acids from the predicted signal peptidase cleavage site. Asparagine-linked glycosylation reporters and presequence deletion constructs of the precursor to the Euglena light-harvesting chlorophyll a/b-binding protein of photosystem II (pLHCPII) were used to identify presequence regions translocated into the ER lumen and stop transfer membrane anchor domains. An asparagine-linked glycosylation site present at amino acid 148 of pLHCPII near the N terminus of mature LHCPII was not glycosylated in vitro by canine microsomes while an asparagine-linked glycosylation site inserted at amino acid 40 was. The asparagine at amino acid 148 was glycosylated upon deletion of amino acids 46-146, which contain the stromal targeting domain, indicating that the hydrophobic region within this domain functions as a stop transfer membrane anchor sequence. Protease protection assays indicated that for all constructs, mature LHCPII was not translocated across the microsomal membrane. Taken together with the structural similarity of all Euglena presequences, these results demonstrate that chloroplast precursors are anchored within ER and Golgi transport vesicles by the stromal targeting domain hydrophobic region oriented with the presequence N terminus formed by signal peptidase cleavage in the vesicle lumen and the mature protein in the cytoplasm.

We found a Gs protein coupled to adenylyl cyclase in a free-living protist, Euglena gracilis. This Gs protein of approximately 42 kDa is substrate for cholera toxin and is recognized by an antibody against the C-terminal decapeptide of Gs. Furthermore, this protein is coupled to adenylyl cyclase, as shown by: (a) the activation of the enzyme by GTP-analogues and (b) the effect of cholera toxin on cAMP accumulation in intact cells and the continuous activation of adenylyl cyclase activity in membranes. These data indicate that the Gs-adenylyl cyclase-coupled system is already apparent in the protist kingdom.

Group II introns are found in eubacteria and eubacterial-derived, organellar genomes. They have ribozymic activities, by which they direct and catalyze the splicing of the exons flanking them. This chapter reviews the secondary structure and known tertiary interactions of the ribozymic component of group II introns in relation to the problems of specifying splice sites and building a catalytic core. We pay special attention to the relationship between the transesterification and hydrolytic modes of initiating splicing and the stereospecificities of these reactions. A number of group II introns encode proteins of the reverse transcriptase family; the activity of these proteins enables the host introns to change genomic locations by mechanisms that are only beginning to be deciphered. Finally, we briefly discuss multipartite and post-transcriptionally edited group II introns, together with the intron microcosm of Euglena gracilis chloroplasts and the possible relationships between group II and spliceosome-catalyzed splicing processes.

The precursor to the Euglena light-harvesting chlorophyll a/b-binding protein of photosystem II (pLHCPII) is unique; it is a polyprotein, synthesized on membrane-bound ribosomes and transported to the Golgi apparatus prior to chloroplast localization. A cDNA corresponding to the 5' end of LHCPII mRNA has been isolated and sequenced. The deduced amino acid sequence of this cDNA indicates that Euglena pLHCPII contains a 141-amino acid N-terminal extension. The N-terminal extension contains three hydrophobic domains and a potential signal peptidase cleavage site at amino acid 35. Cotranslational processing by canine microsomes removed approximately 35 amino acids from an in vitro synthesized 33-kDa pLHCPII composed of a 141-amino acid N-terminal extension and a 180-amino acid partial LHCPII unit truncated at the beginning of the third membrane-spanning hydrophobic domain. Processed pLHCPII was degraded by exogenous protease, indicating that it had not been translocated to the microsomal lumen. Extraction with 0.1 M Na2CO3, pH 11.5, did not remove the processed pLHCPII from the microsomal membrane. A stop-transfer membrane anchor sequence appears to anchor the nascent protein within the membrane, preventing translocation into the lumen. Taken together, these results provide biochemical evidence for a functional cleaved signal sequence within the N-terminal extension of a Euglena cytoplasmically synthesized chloroplast-localized protein.

A system has been developed for the import in vitro of precursor proteins into Euglena chloroplasts, which have three envelope membranes. Preparation of functional chloroplasts with intact envelope membranes has been optimized. Import of the precursor (50 kDa) for the tetrapyrrole biosynthesis enzyme porphobilinogen deaminase (PBGD), and processing to the mature size (40 kDa), occurred at 25 degrees C in the light and the presence of ATP, with an estimated efficiency of 62%. Pretreatment of the chloroplasts with proteases abolished this import, suggesting the involvement of specific protein receptors. The presequence of PBGD was found to be cleaved by Escherichia coli leader peptidase to an intermediate form (46 kDa). A construct in which the first 30 residues of the presequence (presumed to be the region removed by leader peptidase) had been deleted was no longer imported. Neither prePBGD nor the truncated precursor were imported into pea chloroplasts, although both bound to the pea chloroplast envelope. Conversely, a chimeric construct, in which the mature PBGD protein was fused downstream of the transit peptide for pea ferredoxin-NADP reductase, was efficiently imported into pea chloroplasts and processed to the mature size. However, this was not imported into Euglena chloroplasts, although again it bound to them. These results provide preliminary evidence for the possibility of two functional domains within the Euglena PBGD presequence. The implications of these findings with respect to the evolution of Euglena chloroplasts are discussed.

In the nucleoli of vitamin B12-deprived Euglena cells there is a 10-fold amplification of rDNA which correlates with increased numbers of fibrillar centers in the hypertrophic nucleoli. This rDNA amplification was demonstrated by means of molecular hybridization using a specific cytoplasmic rRNA probe. Most of the amplified sequences appear as extrachromosomal copies which were observed without digestion of total cellular or nuclear Euglena DNA. Five different hybridizing sequences, three of high molecular weight and two of 19.0 and 11.5 kb, were identified. The rDNA repeat unit which contains the 11.5-kb transcriptible sequence is 19.0 kb in length and was always more abundant in the undigested total cellular DNA. The possible mechanisms involved in the induction of rDNA amplification in vitamin B12-deficient cells are discussed.

The Order Euglenida comprises many species and perhaps 40 genera, but almost all biochemical and genetic studies have been limited to a single species. Euglena gracilis, because of its ease of growth in the laboratory. Sequence studies of chloroplast and mitochondrial proteins from E. gracilis show that they have diverged widely from other eukaryotic lines. In the present paper we report the sequences of three proteins from another euglenoid, Euglena viridis, using material isolated from a natural bloom. The mitochondrial cytochrome c shows more than 90% sequence identity with that from E. gracilis, and contains the same characteristic features. The chloroplast cytochrome c6 has diverged to a greater extent and shows only 77% identity. The chloroplast ferredoxin from E. viridis is similar in sequence to those of cyanobacteria and algal chloroplasts, with sequence identities of up to 75%. Details of the purification, analysis and sequence determination experiments on the peptides have been deposited as Supplementary Publication SUP 50163 (32 pages) at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1991) 273, 5.

We have localized LHCP II apoprotein in the Golgi and thylakoids of Euglena gracilis Klebs var. bacillaris Cori and strain Z Pringsheim by electron microscopy using a specific antibody and protein A-gold. Using synchronized cells (light, 14 h:dark, 10 h) we show that thylakoids are always immunoreactive. There is no reaction in the Golgi at 0 h (the beginning of the light period) but immunoreaction appears in the Golgi soon thereafter, rises to a peak at 8 h and declines to zero by 16 h (2 h into the dark period). The peak in immunoreaction in the Golgi immediately precedes the peak in cellular 14C-labeling of thylakoid LHCP II apoprotein seen by Brandt and von Kessel (Plant Physiol. (1983) 72, 616), supporting our suggestion that processing in the Golgi precedes deposition of LHCP apoprotein in the thylakoids. Substitution of preimmune serum for antiserum eliminates the immunoreaction in the Golgi, and thylakoids of synchronized cells of mutant Gr1BSL which lacks LHCP II apoprotein show no immunoreaction in the Golgi or thylakoids at any stage. Random observations indicate that the compartmentalized osmiophilic structure (COS) shows an immunoreaction with anti-LHCP II apoprotein antibody at 1 h into the light period (when the Golgi is not immunoreactive) and at 10 h into the light period (when the Golgi is fully reactive), suggesting that the COS remains immunoreactive throughout the cell cycle.

In comparison to the lipid composition of Euglena cells fed with lactate, a first exposure of the cells to ethanol favors the production of neutral lipids containing mainly unsaturated fatty acids. The ethanol diminishes drastically the proportion of PC and weakly that of PE. In contrast, it increases slightly the proportion of DPG. The ethanol induces important changes in the fatty acid distributions of each lipid class, suggesting modifications of the elongation-desaturation system. On the one hand the proportion of unsaturated fatty acids is increased and, on the other hand, the last double bond is predominantly situated in the delta 6 position in place of delta 3. The addition of the complex citrulline-malate corrects most of these changes.