The influence of nitrate on the induction of nitrate reductase in maize roots

1973 ◽  
Vol 51 (6) ◽  
pp. 1255-1258 ◽  
Author(s):  
D. L. Stevens ◽  
Ann Oaks
Keyword(s):  
Nitrate Reductase ◽  
Maize Root ◽  
Lag Phase ◽  
Root Tips ◽  
Final Level ◽  
Maize Roots ◽  
Mature Root

A concentration of 10 mM NO3 saturates the induction of nitrate reductase in maize root tips whereas concentrations up to 100 mM do not saturate the induction in mature root sections. Increasing concentrations of nitrate from 1 to 25 mM have no effect on either the lag phase, or the phase of rapid increase of the enzyme. They do influence the final level of enzyme obtained at 8 h.

The effect of cycloheximide on amide formation in maize roots

1973 ◽  
Vol 51 (1) ◽  
pp. 91-95 ◽  
Author(s):  
Ann Oaks ◽  
F. J. Johnson
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Root Tip ◽  
Minor Effect ◽  
Root Tips ◽  
Corn Root ◽  
Basic Amino Acids ◽  
Maize Roots ◽  
A Minor ◽  
Mature Root

Cycloheximide inhibits the incorporation of acetate-2-14C into protein and into asparagine in corn root tips. It also causes an accumulation of glutamine and, over a concentration range of 0.4 to 5.0 μg/ml, a transient accumulation of the neutral and basic amino acids. In mature sections, cycloheximide inhibits protein synthesis but causes an increase in the incorporation of radioactivity into both glutamine and asparagine. Azaserine, a glutamine analogue, also inhibits the formation of asparagine in root-tip sections but has only a minor effect on protein synthesis. In mature root sections, there is an accumulation of glutamine but no effect on asparagine formation when azaserine is used. Glutamine additions to root tips or mature root sections affect neither asparagine formation nor protein synthesis. We conclude that cycloheximide is behaving as a glutamine analogue in its effect on asparagine biosynthesis, and that its effect as a glutamine analogue is lost as cells mature.

scholarly journals The relationship of root-cap slimes to proteins

1974 ◽  
Vol 139 (3) ◽  
pp. 525-534 ◽  
Author(s):  
Kenneth Wright ◽  
D. H. Northcote
Keyword(s):  
Chemical Characteristic ◽  
Wheat Root ◽  
Root Cap ◽  
Water Soluble ◽  
Maize Root ◽  
Root Tip ◽  
Root Tips ◽  
Maize Roots ◽  
Neutral Sugars ◽  
Relationship Of

1. The patterns of incorporation of radioactivity from d-[U-14C]glucose into the pectic components of sections of sycamore roots changed so that sections nearer the tip incorporated relatively more label into arabinose and galactose compared with uronic acid. 2. Radioactive maize root-cap slime was prepared and found to contain three water-soluble component polymers which were electrophoretically (i) neutral, (ii) weakly acidic and (iii) strongly acidic at pH6.5. The neutral component was a glucan. The other components, which could be degraded by trans-elimination, consisted of an acidic backbone chain composed of galacturonic acid and glucose, attached to which were different proportions of neutral sugars. Arabinose, galactose and fucose, the main neutral sugars of the weakly and strongly acidic materials, were absent from the neutral fraction. 3. Fucose was a major sugar in maize-root slime and in a slime of similar composition synthesized by a maize callus of shoot origin. Only trace amounts were found in sycamore, pea and wheat root tips, and in pectin prepared from maize roots and coleoptiles. A high proportion of fucose is therefore a chemical characteristic of maize slime, and slime synthesis indicated a state of differentiation of the tissue. 4. The similarity between the slime and pectin is discussed; slime is a form of pectin modified in such a way as to provide a hydrated protective coating around the root tip.

Isolation and characterization of membranes from the cells of maize root tips

1980 ◽  
Vol 45 (1) ◽  
pp. 147-167
Author(s):  
E.A. Baydoun ◽  
D.H. Northcote
Keyword(s):  
Choline Chloride ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sucrose Density Gradient ◽  
Maize Root ◽  
Root Tips ◽  
Isolation And Characterization ◽  
Maize Roots ◽  
Endomembrane Flow ◽  
Polypeptide Chains

A discontinuous sucrose density gradient was used to separate membrane fractions from a homogenate of maize root tips. Endoplasmic reticulum-, Golgi apparatus-, plasma membrane- and mitochondria-rich fractions were identified by their enzymic characteristics and by their appearance under the electron microscope. Maize roots were incubated in vivo with D-[U-14C]glucose, [Me-14C]choline chloride and diazotized [U-3H]sulphanilic acid. The pattern of incorporation of radioactivity into the various membrane fractions was investigated. Analyses of the polypeptide chains of the membrane fractions by SDS-polyacrylamide gel electrophoresis showed that the mitochondria-rich fraction had a different pattern of polypeptides from that of the other membrane fractions. The results are discussed in relation to the hypothesis of endomembrane flow and differentiation.

scholarly journals Biological nitrification inhibition in maize—isolation and identification of hydrophobic inhibitors from root exudates

2021 ◽  
Author(s):  
Junnosuke Otaka ◽  
Guntur Venkata Subbarao ◽  
Hiroshi Ono ◽  
Tadashi Yoshihashi
Keyword(s):  
Root Exudation ◽  
Root Systems ◽  
Root Surface ◽  
Maize Root ◽  
Nitrification Inhibition ◽  
Isolation And Identification ◽  
N Losses ◽  
Chemical Structures ◽  
Maize Roots ◽  
Biological Nitrification

AbstractTo control agronomic N losses and reduce environmental pollution, biological nitrification inhibition (BNI) is a promising strategy. BNI is an ecological phenomenon by which certain plants release bioactive compounds that can suppress nitrifying soil microbes. Herein, we report on two hydrophobic BNI compounds released from maize root exudation (1 and 2), together with two BNI compounds inside maize roots (3 and 4). On the basis of a bioassay-guided fractionation method using a recombinant nitrifying bacterium Nitrosomonas europaea, 2,7-dimethoxy-1,4-naphthoquinone (1, ED50 = 2 μM) was identified for the first time from dichloromethane (DCM) wash concentrate of maize root surface and named “zeanone.” The benzoxazinoid 2-hydroxy-4,7-dimethoxy-2H-1,4-benzoxazin-3(4H)-one (HDMBOA, 2, ED50 = 13 μM) was isolated from DCM extract of maize roots, and two analogs of compound 2, 2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (HMBOA, 3, ED50 = 91 μM) and HDMBOA-β-glucoside (4, ED50 = 94 μM), were isolated from methanol extract of maize roots. Their chemical structures (1–4) were determined by extensive spectroscopic methods. The contributions of these four isolated BNI compounds (1–4) to the hydrophobic BNI activity in maize roots were 19%, 20%, 2%, and 4%, respectively. A possible biosynthetic pathway for zeanone (1) is proposed. These results provide insights into the strength of hydrophobic BNI activity released from maize root systems, the chemical identities of the isolated BNIs, and their relative contribution to the BNI activity from maize root systems.

scholarly journals The Endoplasmic Reticulum and the Golgi Structures in Maize Root Cells

1959 ◽  
Vol 5 (3) ◽  
pp. 501-506 ◽  
Author(s):  
W. Gordon Whaley ◽  
Hilton H. Mollenhauer ◽  
Joyce E. Kephart
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Epoxy Resin ◽  
Maize Root ◽  
Root Tips ◽  
Animal Cells ◽  
Root Cells ◽  
Vesicular Structure

Maize root tips were fixed in potassium permanganate, embedded in epoxy resin, sectioned to show silver interference color, and studied with the electron microscope. All the cells were seen to contain an endoplasmic reticulum and apparently independent Golgi structures. The endoplasmic reticulum is demonstrated as a membrane-bounded, vesicular structure comparable in many aspects to that of several types of animal cells. With the treatment used here the membranes appear smooth surfaced. The endoplasmic reticulum is continuous with the nuclear envelope and, by contact at least, with structures passing through the cell wall. The nuclear envelope is characterized by discontinuities, as previously reported for animal cells. The reticula of adjacent cells seem to be in contact at or through the plasmodesmata. Because of these contacts the endoplasmic reticulum of a given cell appears to be part of an intercellular system. The Golgi structures appear as stacks of platelet-vesicles which apparently may, under certain conditions, produce small vesicles around their edges. Their form changes markedly with development of the cell.

Metabolism of proline in maize root tips

1970 ◽  
Vol 48 (6) ◽  
pp. 1155-1158 ◽  
Author(s):  
Ruth A. Barnard ◽  
Ann Oaks
Keyword(s):  
Incubation Period ◽  
Maize Root ◽  
Root Tips ◽  
Intact Roots

During an initial 3-h incubation period, maize root tips loose 62% of their soluble proline. When intact roots are presented with proline-UL-14C for 30 min and subsequently excised, 80% of that proline is used in 3 h. Sixty-six percent of the convertible proline is oxidized to glutamic, malic, succinic, and citric acids, 34% is incorporated into protein as proline during the initial 30-min pulse.

scholarly journals Transcriptome analysis of rice mature root tissue and root tips in early development by massive parallel sequencing

2012 ◽  
Vol 63 (5) ◽  
pp. 2141-2157 ◽  
Author(s):  
T. Kyndt ◽  
S. Denil ◽  
A. Haegeman ◽  
G. Trooskens ◽  
T. De Meyer ◽  
...  
Keyword(s):  
Early Development ◽  
Transcriptome Analysis ◽  
Root Tissue ◽  
Massive Parallel Sequencing ◽  
Root Tips ◽  
Parallel Sequencing ◽  
Mature Root
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