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At least 19 recordsLinked to original sources

PubMed1976

Separation and properties of the NAD-linked and NADP-linked isozymes of succinic semialdehyde dehydrogenase in Euglena gracilis z.

Euglena gracilis z contained two succinic semialdehyde dehydrogenases (EC 1.2.1.16), one requiring NAD and the other NADP, and these isozymes were separated from each other and partially purified. The NAD-linked isozyme was relatively stable on storage at 5 degrees C whereas the NADP-linked one was extremely unstable unless 30% glycerol or ethyleneglycol was added. The optimum pH was 8.7 and optimum temperature 35-45 degrees C for both isozymes. They were inhibited by Zn2+ and activated, particularly the NAD-linked enzyme, by K+. Sulfhydryl reagents activated both isozymes. The Km values for succinic semialdehyde were 1.66 - 10(-4) M with the NAD-linked isozyme and 1.06 - 10(-3) M with the NADP-linked one. The NADP-linked isozyme was induced by glutamate while the NAD-linked one was not. Probable roles of these isozymes in the physiology of Euglena gracilis are discussed.

Aldehyde Oxidoreductases↗

PubMed1977

A dimer of a single polypeptide chain catalyzes the terminal four reactions of the L-tryptophan pathway in Euglena gracilis.

In Euglena gracilis the terminal four enzyme activities of the tryptophan biosynthetic pathway were found to be associated with a protein with an estimated molecular weight of 325,000 +/- 20,000. The protein was purified approximately 2,000-fold with relatively proportional recoveries of all four enzyme activities. The purified material was homogeneous by the criteria of analytical disc gel electrophoresis and gel isoelectric focusing. Disc gel electrophoresis after denaturation with sodium dodecyl sulfate gave a single protein band with a molecular weight of 155,000 +/- 5,000. Disc gel electrophoresis in 8 M urea also gave rise to a single protein band. We interpret these results as evidence for a single species of subunit. The pathway in Euglena is the only one known to the present in which the terminal enzyme, tryptophan synthase, is not a separate molecular species.

Animals↗

PubMed1979

Base composition heterogeneity of Euglena gracilis chloroplast DNA.

Euglena gracilis chloroplast DNA has an average buoyant density of 1.685 gm/cm3, corresponding to 25 mol% G . C base pairs. To test for base compositional heterogeneity within this 130 kilobase pairs (kbp) genome, previously mapped restriction endonuclease fragments were isolated, and characterized by equilibrium buoyant density centrifugation. The chloroplast DNA can be characterized as containing two major buoyant density components. A segment of 17 kbp, representing 13% of the genome and containing the rRNA genes is 43--44 mol% G . C. The remaining 113 kbp, accounting for 87% of the genome, has an average 20--21 mol% G . C content.

Animals↗

PubMed1978

The fractionation of histones isolated from Euglena gracilis.

1. The histones of Euglena gracilis were separated by gel filtration into five fractions. 2. Each fraction was characterized in terms of its electrophoretic, solubility and compositional properties. 3. Euglena gracilis clearly contains histones corresponding to vertebrate H1, H2B, H3 and H4 fractions, although they all differ in containing more lysine. 4. The remaining Euglena histone is considered to be homologous to vertebrate histone H2A, but it differs in having a much higher ratio of lysine to arginine. 5. The Euglena histone H1 appears to be lacking in aspartic acid. 6. Electrophoresis in the presence of sodium dodecyl sulphate indicates that the molecular weights of the Euglena histones are close to those of the homologous vertebrate histones.

Amino Acids↗

PubMed1978

[Electron microscopic study of the nuclei of Euglena gracilis].

The ultrastructure of the Euglena gracilis nucleus has been studied with electron microscopy and prefential staining of ribonucleoproteins. The interphase nucleus chromatin is mainly concentrated in chromonemata - i.e. elongated threads of condensed chromatin. Part of them is directed to the nuclear envelope, with which they are in contact. The number of these contacts is approximately equal to the chromosome number. The Euglena gracilis nucleoplasm is rich in various RNP-components, which points to the transcriptional activity of chromatin, although the majority of chromatin is condensed.

Cell Nucleus↗

PubMedDate not supplied

[Influence of DCMU on the formation of lipids and fatty acids, and on the ultrastructure of Euglena gracilis (author's transl)].

Euglena gracilis Klebs (strain Z) was grown heterotrophically in the dark for 6 days. Subsequently, the cells were grown photoautotrophically under white fluorescent light with varying amounts of 3-(3,4-dichlorophenyl)-1,1 dimethyl urea (DCMU) (1.7X10(-9)--1.0X10(-5)mol/l) added to the nutrient medium. Under non-photosynthetic conditions (addition of 10(-6)--10(-5)mol DCMU/l), the cells still produced chloroplast structures and a considerable percentage of compounds typical for chloroplasts, such as galactolipids (40-50%), chlorophylls (40%), and polyunsaturated C16 and C18 fatty acids (16:2, 16:3, 16:4, 18:2, 18:3) (65%). The results indicate that under these conditions the above compounds are synthesized from carbon sources outside the chloroplasts.

Animals↗

PubMed1979

[Periodic, metabolic and structural phenomena in a protist, Euglena gracilis].

Sychronous divisions of Euglena gracilis strain Z can be obtained by various methods. When the cells are cultivated in a medium containing lactate as the sole carbon source, synchronous divisions are observed, independent of the conditions of illumination. Nevertheless, there exists a relationship between the phase of cell division and ther periods of light and darkness applied to the culture. During the cell cycle, the synthesis of macromolecules is discontinuous--this is true of nuclear and mitochondrial DNA, ribosomal and nonribosomal RNA, and certain proteins (cytochrome c 558). Cyclic variations in the structure of mitochondria and chloroplasts are observed. In the course of the cell cycle, sequential metabolic processes accompany structural modifications of the organelles. Also, at the beginning of the cycle, at the start of phase G1, the cytoplasmic ribosomes are synthesized, and then, in green euglenids, nonribosomal RNAs are formed. These syntheses of RNA precede enlargement of the chondriome and plastids. In mid-G1 phase, a new synthesis of RNA begins, which precedes synthesis of nuclear and mitochondrial DNA. At the end of G1 phase, division of organelles starts, beginning with the chondriome and plastids, arranged in a network.

Animals↗

PubMed1978

Effects of electromagnetic fields on the motion of Euglena gracilis.

The orientation behavior of Euglena gracilis cultures in electromagnetic fields is shown to agree with the predictions of a model involving only a passive mechanism. The increase in Euglena motor activity with increasing field intensity is demonstrated by measuring various motion parameters by the laser scattering technique. The effect of electric field on the speed of Euglenas is compared with that of temperature. We conclude that the electric field warms up the culture, thus inducing an increase in cell motility.

Cell Movement↗

PubMed1977

Cloned ribosomal RNA genes from chloroplasts of Euglena gracilis.

Fragments of Euglena chloroplast DNA generated by endonuclease R-Eco RI were separated by agarose-gel electrophoresis into 24 distinct bands. At least five fragments contain sequences complementary to chloroplast ribosomal RNA, Most of the Eco RI fragments have been cloned in a plasmid of Escherichia coli. Three of the cloned fragments were shown to contain chloroplast ribosomal RNA sequences by DNA-RNA hybridization.

Chloroplasts↗

PubMed1977

Restriction endonuclease map of Euglena gracilis chloroplast DNA.

A physical map of the Euglena gracilis chloroplast genome has been constructed, based on cleavage sites of Euglena gracilis chloroplast DNA treated with bacterial restriction endonucleases. Covalently close, circular chloroplast DNA is cleaved by restriction endonuclease SalI into three fragments and by restriction endonuclease BamHI into six fragments. These nine cleavage sites have been ordered by fragment molecular weight analysis, double digestions, partial digestions, and by digestion studies of isolated DNA fragments. A fragment pattern of the products of EcoRI restriction endonuclease digestion of Euglena chloroplast DNA is also described. One of these fragments has been located on the cleavage site map.

Animals↗

PubMed1979

[Further biochemical investigations on glycosaminoglycans extracted from Euglena gracilis].

Polyanionic glycans extracted from Euglena gracilis have been studied by biochemical, chromatographic and electrophoretic analysis. Our results show the presence of a fraction which precipitate with CPC and another one which not precipitate with CPC. The CPC precipitable material fractionated on CPC-Cellulose column shows the presence of 5 Glycosaminoglycans; the not CPC precipitable material contains uronic acid, galactose, sulfate, galactosamine and cannot be related to Keratan sulfate.

Cetylpyridinium↗

PubMed1978

Culture pH, CO2 tension, and cell division in Euglena gracilis Z.

Growth characteristics of Euglena gracilis Z as functions of culture pH, CO2 tension, temperature, and lighting regime were investigated. The results are consistent with the possibility that cell division is preceded by a lowered intracellular pH. Also consistent with this possibility is the finding that division rhythmicity can be induced by periodic changes in CO2 tension. It is suggested that the rhythmicity is induced by changes in intracellular pH produced by carbonic acid.

Carbon Dioxide↗

PubMed1977

Some biochemical properties of mitochondria isolated from Euglena gracilis.

Mitochondria were isolated from Euglena gracilis strain Z by pressure-breakage of the cells and sucrose-cushion centrifugation. Multiple peaks (2-4) were observed in the rate of phosphorylation with Mg-ADP-phosphate concentration curves. The phosphorylative and oxidative activities were highest with NADH as the substrate, moderate with succinate, and lowest with glutamate. Inhibition of phosphorylation with 2,4-dinitrophenol and carbonyl cyanide, m-chlorophenylhydrazone gave sigmoidal concentration curves, with the extent of inhibition by DNP depending on the substrate used. Inhibition of phosphorylation by valinomycin, atractyloside, or carboxyatractyloside was only approximately 60%. Oligomycin inhibited phosphorylation in 2 phases at low and high concentrations; it inhibited Mg-ATPase in a sigmoidal fashion. Both phosphorylation and oxidation had discontinuities in Arrhenius plots at 34 C and 18 C. The relative Mg2+-dependent nucleoside triphosphatase activity was: 1 for ATP and GTP, 0.6 for ITP, 0.15 for CTP and UTP; with Ca2+ in place pf Mg2+ this activity was 0.35. Both DNP and CCCP stimulated the Mg-ATPase 50-200%. The optimal pH for the stimulation was approximately 7 regardless of the uncoupler used, and approximately 8 without the uncouplers. The few differences observed between mitochodria from Euglena and those from other sources are probably due to the fragmentation of the reticular mitochondrial structure during isolation and not to unique characteristics of these mitochondria.

Adenosine Triphosphatases↗

PubMed1978

The ultrastructure of cell division in Euglena gracilis.

The ultrastructure of mitosis in Euglena gracilis was investigated. At preprophase the nucleus migrates anteriorly and associates with the basal bodies. Flagella and basal bodies replicate at preprophase. Cells retain motility throughout division. The reservoir and the prophase nucleus elongate perpendicular to the incipient cleavage furrow. One basal body pair surrounded by a ribosome-free zone is found at each of the nuclear poles. The spindle forms within the intact nuclear envelope- Polar fenestrae are absent. At metaphase, the endosome is elongated from pole to pole, and chromosomes are loosely arranged in the equatorial region. Distinct, trilayered kinetochores are present. Spindle elongates as chromosomes migrate to the poles forming a dumb-bell shaped nucleus by telophase. Daughter nuclei are formed by constriction of the nuclear envelope. Cytokinesis is accomplished by furrowing. Cell division in Euglena is compared with that of certain other algae.

Animals↗

PubMed1975

Induction potential for glyoxylate cycle enzymes during the cell cycle of Euglena gracilis.

In light/dark synchronized cultures of Euglena gracilis Klebs Z the enzymes malate synthase, isocitrate lyase and acetate thiokinase were induced upon addition of acetate at all stages of the cell cycle. Cycloheximide and p-fluorophenylalanine inhibited the development of enzyme activity, showing that induction was dependent on protein synthesis. The maximum rate of induction for all three enzymes was constant for much of the cell cycle but doubles in a single step during the period of DNA replication. Although these data indicate that enzyme potential was regulated by gene dosage and that the structural gene for each enzyme was continuously available for transcription during the cell-cycle it was not possible by using inhibitors of RNA synthesis, to demonstrate concurrent transcription during enzyme induction.

Acetate-CoA Ligase↗

PubMed1978

The effect of polychlorobiphenyls (Aroclor 1242) on bicarbonate-C14 uptake by Euglena gracilis.

Aroclor 1242 is inhibitory to long-term batch growth of Euglena gracilis at 10 ppm. Exposure to PCB's, subsequent to an initial drop of 50% in the first 30 minutes, does not appear to inhibit photosynthesis on a per cell basis over the time span of four hours. Consequently our experimental findings suggest that inhibition of population growth does not lie directly in the photosynthetic pathway despite the initial inhibition by Aroclor 1242 on Euglena gracilis in "light". "Dark" absorption of bicarbonate appears to decrease with increased PCB exposure. This decrease may be causally related to the population growth inhibition observed.

Animals↗

PubMed1979

Synchronization of division in vitamin B12-starved Euglena gracilis.

Vitamin B12 deficiency arrests cell division in Euglena gracilis. B12 starvation for short periods made it possible to induce synchronous growth by addition of the vitamin. Culture conditions were established to optimize replenishment synchrony. The DNA content of E. gracilis in steady state culture and vitamin B12 deficiency culture was measured by flow cytofluorometry and was consistent with colorimetric determinations. The cell volume and DNA distributions of E. gracilis in synchronous culture were analyzed and the sequential changes during the division cycle were computed. Synchronous culture permits more definitive studies of shifts in cell volume and DNA distributions, in which the biochemical events required for cell division are presumably synchronized.

Animals↗

PubMed1977

Growth and cell volume of Euglena gracilis in different media.

It is necessary to propagate Euglena gracilis cells for several days after transfer from one medium to another to establish the steady state of balanced growth. Steady-state growth was established in minimal and in complex medium. Specific growth rates and cell volume distributions were computed for each culture medium. Mean cell volume of E. gracilis is not uniquely correlated with the specific growth rate.

Culture Media↗