In situ studies on alginic acid synthesis and other aspects of the metabolism of Laminaria digitata

1972 ◽  
Vol 50 (1) ◽  
pp. 177-184 ◽  
Author(s):  
Johan A. Hellebust ◽  
Arne Haug
Keyword(s):  
Amino Acids ◽  
Time Course ◽  
Alginic Acid ◽  
Acid Synthesis ◽  
Short Term ◽  
Fresh Weight Basis ◽  
Mannuronic Acid ◽  
Guluronic Acid ◽  
Rate Of Photosynthesis

Amino acids, particularly alanine and aspartate, become more strongly labeled than mannitol in short-term 14C-photoassimilation experiments. The amino acids are the most likely sources of carbon for alginic acid synthesis and respiration in the dark, in contrast to mannitol, which appears to be relatively unavailable. Temperature is very important in determining the rate of loss of recent photoassimilate in L. digitata. The rate of photosynthesis, on a fresh weight basis, is much higher for blades than for stipes.The time course for incorporation of photoassimilated carbon into alginate differs for the stipe and blade both in light and dark periods. Very little 14C enters alginate in blades in the dark, while alginate in stipes acquires considerable amounts of activity during dark periods. Alginate in both blade and stipe acquires 14C predominantly in mannuronic acid residues of their alginate during short-term photoassimilation periods, while guluronic acid residues become relatively more rapidly labeled during dark periods.

Photosynthesis, translocation, and alginic acid synthesis in Laminaria digitata and Laminaria hyperborea

1972 ◽  
Vol 50 (1) ◽  
pp. 169-176 ◽  
Author(s):  
Johan A. Hellebust ◽  
Arne Haug
Keyword(s):  
Time Course ◽  
Alginic Acid ◽  
Acid Synthesis ◽  
Laminaria Hyperborea ◽  
Short Term ◽  
Fresh Weight Basis ◽  
Mannuronic Acid ◽  
Guluronic Acid ◽  
Isolated Cortex ◽  
Photosynthetic Capacities

New and old tissues of L. digitata blades have very similar photosynthetic capacities on a fresh weight basis. Very little of the photoassimilate goes into alginic acid, or other macromolecular substances in old blade tissues. Less than 1% of the photoassimilated 14C in the old blade portion of a L. digitata blade was translocated to the new blade tissues in a 5-h experiment. In contrast, there is rapid transport of photoassimilate from bark cells to cells of the underlying tissues of L. digitata and L. hyperborea stipe sections. Isolated cortex and medulla tissues of L. digitata stipes have significant photosynthetic capacities, but are probably so strongly shaded by the darkly pigmented bark cells that little photosynthesis can normally occur in these tissues.A larger proportion of the photoassimilated carbon enters alginate in the cortex and medulla than in the bark of L. digitata and L. hyperborea stipes in short-term experiments. The time course for incorporation of photosynthate into alginate in continuous and pulse-labeling experiments indicates the presence of relatively large pools of alginate precursors. A large proportion of the total 14C incorporated into alginate in short-term experiments is found in the "M–M" (mannuronic acid) and "M–G" (alternating mannuronic and guluronic acid) block components.

scholarly journals The biosynthesis of alginic acid by Azotobacter vinelandii

1975 ◽  
Vol 152 (3) ◽  
pp. 617-622 ◽  
Author(s):  
D F Pindar ◽  
C Bucke
Keyword(s):  
Alginic Acid ◽  
Azotobacter Vinelandii ◽  
Mannuronic Acid ◽  
Guluronic Acid ◽  
Polymeric Substance

The sequence of reactions by which alginic acid is biosynthesized from sucrose in Azotobacter vinelandii was determined both by feeding radioactive individual enzymes involved. Results indicate that the first polymeric substance formed in the synthesis is polymannuronic acid and that mannuronic acid units are epimerized to guluronic acid at the polymer level. Guluronic acid does not appear to be formed at the monomer level, either free or in combination with GDP.

scholarly journals The A Modules of the Azotobacter vinelandii Mannuronan-C-5-Epimerase AlgE1 Are Sufficient for both Epimerization and Binding of Ca2+

1999 ◽  
Vol 181 (10) ◽  
pp. 3033-3038 ◽  
Author(s):  
Helga Ertesvåg ◽  
Svein Valla
Keyword(s):  
Amino Acids ◽  
Reaction Rate ◽  
Azotobacter Vinelandii ◽  
Binding Studies ◽  
Mannuronic Acid ◽  
Guluronic Acid ◽  
Catalytic Sites ◽  
Direct Binding ◽  
Protein Modules ◽  
Secreted Enzymes

ABSTRACT The industrially important polysaccharide alginate is composed of the two sugar monomers β-d-mannuronic acid (M) and its epimer α-l-guluronic acid (G). In the bacteriumAzotobacter vinelandii, the G residues originate from a polymer-level reaction catalyzed by one periplasmic and at least five secreted mannuronan C-5-epimerases. The secreted enzymes are composed of repeats of two protein modules designated A (385 amino acids) and R (153 amino acids). The modular structure of one of the epimerases, AlgE1, is A1R1R2R3A2R4. This enzyme has two catalytic sites for epimerization, each site introducing a different G distribution pattern, and in this article we report the DNA-level construction of a variety of truncated forms of the enzyme. Analyses of the properties of the corresponding proteins showed that an A module alone is sufficient for epimerization and that A1 catalyzed the formation of contiguous stretches of G residues in the polymer, while A2 introduces single G residues. These differences are predicted to strongly affect the physical and immunological properties of the reaction product. The epimerization reaction is Ca2+ dependent, and direct binding studies showed that both the A and R modules bind this cation. The R modules appeared to reduce the Ca2+ concentration needed for full activity and also stimulated the reaction rate when positioned both N and C terminally.

EXOCELLULAR ALGINIC ACID FROM AZOTOBACTER VINELANDII

1966 ◽  
Vol 44 (9) ◽  
pp. 993-998 ◽  
Author(s):  
P. A. J. Gorin ◽  
J. F. T. Spencer
Keyword(s):  
Sodium Alginate ◽  
Small Proportion ◽  
Alginic Acid ◽  
Azotobacter Vinelandii ◽  
Specific Rotation ◽  
Mannuronic Acid ◽  
Guluronic Acid ◽  
Exocellular Polysaccharide

Azotobactervinelandii produces a partly acetylated exocellular polysaccharide which consists mainly of D-mannuronic acid units and a small proportion of L-guluronic acid units. It resembles alginic acid since it contains 4-O-linked mannuronosyl residues and guluronosyl residues which are 4-O- and (or) 5-O-linked. The specific rotation of bacterial sodium alginate is close to that of its algal counterpart, thus suggesting that the glycosidic configurations are similar.

The Fine Structure of Alginic Acid Components

1968 ◽  
Vol 26 ◽  
pp. 82-83
Author(s):  
S. Inoue ◽  
Y. Tanaka ◽  
S.C. Skoryna
Keyword(s):  
Fine Structure ◽  
Sodium Alginate ◽  
Uronic Acid ◽  
Alginic Acid ◽  
Brown Seaweed ◽  
Uronic Acids ◽  
Laminaria Hyperborea ◽  
Mannuronic Acid ◽  
Guluronic Acid ◽  
Hydrolysis Of

Sodium alginate, a brown seaweed polysaccharide, is capable of preventing intestinal absorption of radioactive strontium and its radiotoxicological importance is now well established. Alginic acid was found to be composed of 1,4-linked poly-L-guluronic acid and poly-D-mannuronic acid chains with some glycosidic linkages between these uronic acids.Polyguluronic and polymannuronic acid were prepared by acid hydrolysis of alginic acid from Laminaria hyperborea followed by fractionation of the partially degraded sodium alginate at pH 2.8. These components consist almost exclusively of a single uronic acid (polyguluronic acid: man/gul = 0.27; polymannuronic acid: man/gul = 10.7). Sodium polyguluronate inhibits absorption of radiostrontium more effectively than sodium polymannuronate.

scholarly journals Galactocerebroside is expressed by non-myelin-forming Schwann cells in situ.

1985 ◽  
Vol 101 (3) ◽  
pp. 1135-1143 ◽  
Author(s):  
K R Jessen ◽  
L Morgan ◽  
M Brammer ◽  
R Mirsky
Keyword(s):  
Schwann Cells ◽  
Time Course ◽  
In Utero ◽  
Sympathetic Trunk ◽  
Short Term ◽  
Cultured Schwann Cells ◽  
Cervical Sympathetic ◽  
Time Courses

Interest in the glycosphingolipid galactocerebroside (GC) is based on the consensus that in the nervous system it is expressed only by myelin-forming Schwann cells and oligodendrocytes, and that it has a specific role in the elaboration of myelin sheaths. We have investigated GC distribution in two rat nerves--the sciatic, containing a mixture of myelinated and non-myelinated axons, and the cervical sympathetic trunk, in which greater than 99% of axons are non-myelinated. Immunohistochemical experiments using mono- and polyclonal GC antibodies were carried out on teased nerves and cultured Schwann cells, and GC synthesis was assayed biochemically. Unexpectedly, we found that mature non-myelin-forming Schwann cells in situ and in short-term cultures express unambiguous GC immunoreactivity, comparable in intensity to that of myelinated fibers or myelin-forming cells in short-term cultures. GC synthesis was also detected in both sympathetic trunks and sciatic nerves. In the developing sympathetic trunk, GC was first seen at day 19 in utero, the number of GC-positive cells rising to approximately 95% at postnatal day 10. In contrast, the time course of GC appearance in the sciatic nerve shows two separate phases of increase, between day 18 in utero and postnatal day 1, and between postnatal days 20 and 35, at which stage approximately 94% of the cells express GC. These time courses suggest that Schwann cells, irrespective of subsequent differentiation pathway, start expressing GC at about the same time as cell division stops. We suggest that GC is a ubiquitous component of mature Schwann cell membranes in situ. Therefore, the role of GC needs to be reevaluated, since its function is clearly not restricted to events involved in myelination.

scholarly journals Attenuated Late-PhaseArcTranscription in the Dentate Gyrus of Mice LackingEgr3

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Amanda Maple ◽  
Rachel E. Lackie ◽  
Diana I. Elizalde ◽  
Stephanie L. Grella ◽  
Chelsey C. Damphousse ◽  
...  
Keyword(s):  
Dentate Gyrus ◽  
Time Course ◽  
Wild Type ◽  
Short Term ◽  
Unique Role ◽  
Late Protein ◽  
Dependent Learning

The dentate gyrus (DG) engages in sustainedArctranscription for at least 8 hours following behavioral induction, and this time course may be functionally coupled to the unique role of the DG in hippocampus-dependent learning and memory. The factors that regulate long-term DGArcexpression, however, remain poorly understood. Animals lackingEgr3show lessArcexpression following convulsive stimulation, but the effect ofEgr3ablation on behaviorally inducedArcremains unknown. To address this,Egr3−/−and wild-type (WT) mice explored novel spatial environments and were sacrificed either immediately or after 5, 60, 240, or 480 minutes, andArcexpression was quantified by fluorescence in situ hybridization. Although short-term (i.e., within 60 min)Arcexpression was equivalent across genotypes, DGArcexpression was selectively reduced at 240 and 480 minutes in mice lackingEgr3. These data demonstrate the involvement ofEgr3in regulating the late protein-dependent phase ofArcexpression in the DG.

scholarly journals Absorption of leucine, alanine and lysine from the rumen

2001 ◽  
Vol 49 (1) ◽  
pp. 81-86 ◽  
Author(s):  
T. Veresegyházy ◽  
Hedvig Fébel ◽  
Ágnes Rimanóczy
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Concentration ◽  
Experimental Period ◽  
Amino Acid Concentration ◽  
Short Term ◽  
Rate Of Absorption

The absorption of three amino acids (leucine, alanine and lysine) from the washed, closed rumen was studied in a short-term (75 min) experiment in situ. The concentration of leucine and alanine did not change in the rumen during the experiment, while that of lysine continuously decreased, and 40% of the total lysine placed in the rumen was absorbed during the experimental period. The rate of absorption decreased in proportion to the fall of amino acid concentration.

scholarly journals Biochemical Properties and Substrate Specificities of a Recombinantly Produced Azotobacter vinelandiiAlginate Lyase

1998 ◽  
Vol 180 (15) ◽  
pp. 3779-3784 ◽  
Author(s):  
Helga Ertesvåg ◽  
Frode Erlien ◽  
Gudmund Skjåk-Bræk ◽  
Bernd H. A. Rehm ◽  
Svein Valla
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Azotobacter Vinelandii ◽  
Divalent Cations ◽  
Alginate Lyase ◽  
Biochemical Properties ◽  
Mature Protein ◽  
Substrate Specificities ◽  
Mannuronic Acid ◽  
Guluronic Acid

ABSTRACT Alginate is a polysaccharide composed of β-d-mannuronic acid (M) and α-l-guluronic acid (G). An Azotobacter vinelandii alginate lyase gene,algL, was cloned, sequenced, and expressed inEscherichia coli. The deduced molecular mass of the corresponding protein is 41.4 kDa, but a signal peptide is cleaved off, leaving a mature protein of 39 kDa. Sixty-three percent of the amino acids in this mature protein are identical to those in AlgL fromPseudomonas aeruginosa. AlgL was partially purified, and the activity was found to be optimal at a pH of 8.1 to 8.4 and at 0.35 M NaCl. Divalent cations are not necessary for activity. The pI of the enzyme is 5.1. When an alginate rich in mannuronic acid was used as the substrate, the Km was found to be 4.6 × 10−4 M (sugar residues). AlgL was found to cleave M-M and M-G bonds but not G-M or G-G bonds. Bonds involving acetylated residues were also cleaved, but this activity may be sensitive to the extent of acetylation.

Acidic Biopolymers as Dispersants for Ceramic Processing

1990 ◽  
Vol 218 ◽  
Author(s):  
N. Pellerin ◽  
J. T. Staley ◽  
T. Ren ◽  
G. L. Graff ◽  
D. R. Treadwell ◽  
...  
Keyword(s):  
Azotobacter Vinelandii ◽  
Ceramic Materials ◽  
Low Molecular Weight ◽  
Ceramic Processing ◽  
Molecular Configuration ◽  
Partial Acid Hydrolysis ◽  
Mannuronic Acid ◽  
Guluronic Acid ◽  
Alumina Particles

AbstractSome acidic biopolymers serve as dispersants for colloidal processing of ceramics. One biopolymer we tested was alginate, a heteropolysaccharide containing two carboxylic sugar acids, D-mannuronic and D-guluronic. Kelp alginate was a suitable dispersant, provided that its viscosity was reduced by partial acid hydrolysis. Low molecular weight polymers rich in guluronic acid proved to be better dispersants than those rich in mannuronic acid, perhaps due to their greater charge density caused by their buckled molecular configuration. In situ processing of ceramic materials was tested by growing the alginate-producing bacterium, Azotobacter vinelandii, in the presence of alumina particles. Growth occurred at 15 vol% alumina in medium. Alumina particles which were exposed to such treatment showed a high packing density comparable to that with purified polymer. We also tested polypeptide polymers of the dicarboxylic amino acids, glutamate and aspartate, which also served as excellent dispersants for small alumina particles.

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