The cell-wall constituents of Apjohnia laetevirens Harvey

1969 ◽  
Vol 20 (2) ◽  
pp. 143 ◽  
Author(s):  
CM Stewart ◽  
CJ Dawes ◽  
BM Dickens ◽  
JWP Nicholls
Keyword(s):  
Cell Wall ◽  
Organic Solvent ◽  
Aqueous Solutions ◽  
Green Alga ◽  
Protein Complex ◽  
Cell Walls ◽  
Room Temperature ◽  
Organic Substances ◽  
Low Degree ◽  
Crystalline Aggregates

Cells of the green alga, Apjohnia laeterivens Harvey, have been ruptured in a Waring blendor in order to remove the majority of the protoplast from the cell-wall substances. The cell walls have been shown to contain, apart from extraneous protoplasmic constituents and some encrusting bryozoa, framework microfibrils of cellulose 1 which seem to be associated with pectin-like materials, arabinogalactan matrix substances and, perhaps, a polysaccharide-protein complex; these components appear to represent about 90% of the organic substances in the original organic-solvent extracted cell walls. Less than 25 % of the initial cellulose 1 was converted to cellulose 11 during treatments of several hours' duration at room temperature with aqueous solutions of 24% KOH and 17.5 % NaOH. The low degree of conversion is attributed to the presence of highly ordered and/or large "crystalline" aggregates of �-1,4'-glucan molecules in the cellulosic micelles of the framework microfibrils of the cell walls.

E.S.R. studies of the solute-solute interactions between copper(II) and nickel(II) thiosemicarbazone chelates in non-aqueous solutions

1976 ◽  
Vol 29 (12) ◽  
pp. 2583 ◽  
Author(s):  
JAD Bolfo ◽  
TD Smith ◽  
JF Boas ◽  
JR Pilbrow
Keyword(s):  
Organic Solvent ◽  
Aqueous Solutions ◽  
Ground State ◽  
Room Temperature ◽  
Profound Change ◽  
Frozen Solution ◽  
X Band ◽  
Show Evidence ◽  
Solute Interactions ◽  
Ligand Addition

The X-band e.s.r. spectra due to the copper(II) chelates of the thiosemicarbazones salicylaldehyde thiosemicarbazone (stsc), salicylaldehyde 4-methyl(thiosemicarbazone) (smtc), salicylaldehyde 4- ethyl-(thiosemicarbazone) (setc), salicylaldehyde 4- phenyl(thiosemicarbazone) (sptc), 2-hydroxyacetophen- one 4- ethyl(thiosemicarbazone) (aetc) and 2-hydroxypropiophenone 4- ethyl(thiosemicarbazone) (petc) dissolved in various organic solvents have been studied at room temperature and down to 77 K. The e.s.r. spectra show evidence of hyperfine structure due to the 14N nucleus of the ligand. Addition of the nickel(II) chelate of the thiosemicarbazone ligands to organic solvent solutions of the corresponding copper(II) chelate brings about a profound change in the e.s.r. spectrum of the copper(II) chelate in frozen solution. These changes are interpreted as arising from a change in the ground state of the copper(II) ion from essentially dx2-y2 to d3z2-r2, which arises as a result of specific solute- solute interactions between the copper(II) and nickel(II) chelates.

Stability of Aflatoxins in Solution

2012 ◽  
Vol 95 (4) ◽  
pp. 1084-1088 ◽  
Author(s):  
Gonzalo J Diaz ◽  
Sandra M Cepeda ◽  
Perry A Martos
Keyword(s):  
Nitric Acid ◽  
Organic Solvent ◽  
Aqueous Solutions ◽  
Chemical Etching ◽  
Room Temperature ◽  
Organic Content ◽  
Significant Loss ◽  
Type I ◽  
The Stability

Abstract The stability of aflatoxins B1, B2, G1, and G2 was studied in solutions containing different concentrations of water, acetonitrile, and/or methanol, and in autosampler vials treated with nitric acid or silanized. When stored at room temperature (20°C) for 24 h, aflatoxins G1 and G2 were stable only in solutions containing 100% organic solvent, whereas aflatoxins B1 and B2 were stable in solutions of methanol–water and acetonitrile–water at greater than 60 and 40% organic content, respectively. At 5°C, aflatoxins G1 and G2 showed a significant decrease in concentration only when kept in less than 20% aqueous organic solvent. Significant loss of aflatoxins was realized in standard, commercially available amber type I borosilicate autosampler vials, but chemical etching of the vials with nitric acid or with silanization prevented aflatoxin degradation. These results indicate that aflatoxins are unstable in aqueous solutions and that this instability can be counteracted by the presence of at least 20% organic solvent and keeping the solutions at 5°C or by the use of treated vials.

Alkali effects on agricultural wastes and their cell wall fraction

1978 ◽  
Vol 18 (91) ◽  
pp. 231
Author(s):  
WR McManus
Keyword(s):  
Cell Wall ◽  
Reaction Time ◽  
Cell Walls ◽  
Dry Matter ◽  
Room Temperature ◽  
Chelating Agent ◽  
Agricultural Wastes ◽  
Waste Materials ◽  
Cell Wall Fraction ◽  
Organic Fraction

Five experiments are reported which examine the effect of alkalis (NaOH, 0-1 4 g/100 g DM ; NH,OH, 0-2.9 g/l00 g DM), reaction time and temperature upon dry matter (DM) digestibility and related properties of mature forage waste materials. Digestion was assessed by microdigestion of test samples in the rumens of fistulated sheep fed lucerne base diets. Digestion of the DM of brewer's grains was increased from 50.2 per cent to 58.5 per cent by application of 2.9 per cent NaOH or NH4OH at room temperature for 24 hours, and to 81.9 per cent when heated to 80�C for 24 hours. Heating at 150�C for 1 hour produced no improvement over heating at 80�C for 24 hours. Average DM digestion of a range of mature grasses was improved by 6.9 per cent by applying 1.5 g NH4OH/100 g DM at room temperature for 17 hours and by 13.7 per cent when heated to 80�C for the same period. The DM digestion of mature legumes did not increase due to these treatments, but when heated with 1.5 g NH4OH/100 g DM to 130�C for 4 hours increased DM digestibility by 16.6 per cent. The digestion of unashed cell wall (CW) and acid detergent (AD) residues in mature grasses was increased by a prior extraction with neutral detergent and acid detergent. In mature legumes these pretreatments had no effect upon digestibility. The unashed (KmnO4 extracted) cellulose residues of grasses and legumes were incompletely digested compared with pure cotton. Both NaOH and the chelating agent EDTA eventually remove the CW-ash fraction and this is associated with increases in CW digestion with increasing level of their application. These chemicals also initially increase and then decrease the organic fraction of the mature forage CW, its ADF and lignin. The digestibility of cell walls of lucerne hay is increased from 24.3 per cent to 43.3 per cent by application of NaOH (9 g /100 g DM) for 2 hours at room temperatures; the corresponding increase for cell walls of wheaten chaff is from 33.9 per cent to 72.3 per cent. It is shown that alkalis induce increases in DM digestion by degrading cell walls and that the cell walls of mature grasses are more easily degraded than are the cell walls of mature legumes.

Occurrence of silica in brown and green algae

1969 ◽  
Vol 47 (4) ◽  
pp. 537-540 ◽  
Author(s):  
Bruce C. Parker
Keyword(s):  
Cell Wall ◽  
Green Algae ◽  
Phylogenetic Relationships ◽  
Brown Algae ◽  
Cell Walls ◽  
Organic Substances

Small but significant amounts of silica occur in all brown algae and green Hydrodictyaceae examined. At least in the hydrodictyaceous Pediastrum and Tetraëdron, the silica predominates in the cell wall. This silica is largely isotropic, non-crystalline opal with a small amount of α-quartz. Occurrence of silica in brown algae constitutes yet another feature suggesting phylogenetic relationships with the Chrysophycophyta, and the siliceous cell walls of the Hydrodictyaceae facilitate an understanding of both the nature of organic substances present and the process of zoosporogenesis.

scholarly journals The structure of the cell wall in some species of the filamentous green alga Cladophora

1940 ◽  
Vol 129 (854) ◽  
pp. 54-76 ◽  
Keyword(s):  
Cell Wall ◽  
Green Alga ◽  
Cell Elongation ◽  
Cell Walls ◽  
Opposite Sign ◽  
Periodic Change ◽  
X Ray Diffraction ◽  
X Ray ◽  
Filamentous Green Alga ◽  
Flat Spiral

With a view to extending the work on Valonia , the cell walls of several species of Cladophora have been examined in detail by means of X-ray diffraction photographs and the microscope. The walls are found to consist of layers in which the cellulose chains in any one layer are inclined to those in the preceding and subsequent layers at an angle whose average is less than 90°. The two sets of striations on the layers of the wall correspond closely to the directions of the cellulose chains. Each set of chains forms a spiral round the cell, and the spirals are of opposite sign. One tends to be flat and th e other steep. On the whole, th e steep spiral tends to become steeper on passing from the base of the filament to the tip, and the flat spiral flatter. In any one cell of the filament, the steep spiral is steepest at the end nearer the filament tip and the flat spiral flattest. Wherever such changes in inclination occur, the angle between the chains tends to remain constant. It is suggested that cell elongation is the factor causing the inclination of the steeper spiral to vary, and that the behaviour of the flatter spiral is best explained by the assumption of a protoplasmic mechanism causing a periodic change in the direction of cellulose chains through a constant angle. The development of a branch cell is reviewed and is found to proceed as the above suggestions would indicate.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

Silicification of wood-cell walls

1994 ◽  
Vol 52 ◽  
pp. 428-429
Author(s):  
S. E. Keckler ◽  
D. M. Dabbs ◽  
N. Yao ◽  
I. A. Aksay
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Cell Walls ◽  
Lignin Content ◽  
Resin Composite ◽  
Middle Lamella ◽  
Cellulose Fibers ◽  
Complex Structures ◽  
Rich Region ◽  
Inorganic Precursors

Cellular organic structures such as wood can be used as scaffolds for the synthesis of complex structures of organic/ceramic nanocomposites. The wood cell is a fiber-reinforced resin composite of cellulose fibers in a lignin matrix. A single cell wall, containing several layers of different fiber orientations and lignin content, is separated from its neighboring wall by the middle lamella, a lignin-rich region. In order to achieve total mineralization, deposition on and in the cell wall must be achieved. Geological fossilization of wood occurs as permineralization (filling the void spaces with mineral) and petrifaction (mineralizing the cell wall as the organic component decays) through infiltration of wood with inorganics after growth. Conversely, living plants can incorporate inorganics into their cells and in some cases into the cell walls during growth. In a recent study, we mimicked geological fossilization by infiltrating inorganic precursors into wood cells in order to enhance the properties of wood. In the current work, we use electron microscopy to examine the structure of silica formed in the cell walls after infiltration of tetraethoxysilane (TEOS).

Histological aspects of the cryopreservation of potato

2008 ◽  
Vol 56 (3) ◽  
pp. 341-348
Author(s):  
P. Pepó ◽  
A. Kovács
Keyword(s):  
Cell Wall ◽  
Low Temperatures ◽  
Cell Walls ◽  
Cellular Level ◽  
Adaptive Mechanism ◽  
Epidermal Layer ◽  
Freezing And Thawing ◽  
Meristematic Cells ◽  
Suitable Solution ◽  
Vacuolated Cells

Cryopreservation appears to be a suitable solution for the maintenance of potato germplasms. The protocol described in this paper can be applied for the vitrification and preservation of meristems. During histo-cytological studies it is possible to observe modifications at the cellular level and to understand the adaptive mechanism to low temperatures. Control potato meristem tissue contained a number of meristematic cells with a gradient of differentiation. After freezing there were a large number of vacuolated cells, some of which exhibited broken cell walls and plasmolysis. The thickening of the cell wall, giving them a sinuous appearance, was observed after freezing and thawing the meristems, with ruptures of the cuticle and epidermal layer.

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