OBSERVATIONS ON INTERPHASE AND PROPHASE NUCLEI OF ROOT TIPS OF EINKORN WHEAT AND ONION

1953 ◽  
Vol 31 (5) ◽  
pp. 527-530
Author(s):  
Clayton Person
Keyword(s):  
Mitotic Cycle ◽  
Metaphase Plate ◽  
Root Tips ◽  
Einkorn Wheat ◽  
Onion Root ◽  
Definite Relation

Studies of cells in interphase and prophase show that at all stages of the mitotic cycle in the nuclei of Einkorn wheat and onion root tips the arrangement of the chromosomes bears a definite relation to the axis of the nucleus. The establishment, by the centromeres, of the metaphase plate is described. The observations are compared with those of previous investigators and possible applications in other fields of investigation are suggested.

Glycosyltransferases in plant and animal tissues effects of fixation and lead on enzyme activity.

1978 ◽  
Vol 26 (10) ◽  
pp. 772-781 ◽  
Author(s):  
W D Klohs ◽  
C W Goff ◽  
R J Bernacki
Keyword(s):  
Enzyme Activity ◽  
Lead Nitrate ◽  
Initial Step ◽  
Lead Ions ◽  
Fixation Time ◽  
Animal Tissues ◽  
Root Tips ◽  
Cytochemical Localization ◽  
Onion Root ◽  
L1210 Cells

As the initial step toward the cytochemical localization of glycosyl-transferases in situ, biochemical determinations of these enzyme activities from onion root tips and L1210 cells were performed before and after fixation as well as in the presence of lead ions. Glycosyltransferase activity from roots fixed in buffered formaldehyde or glutaraldehyde before homogenization decreased as the concentration of the fixative or fixation time was increased. Formaldehyde fixation was less inhibitory than glutaraldehyde; 35% of the glycosyltransferase activity was retained after 30 min fixation in 2% formaldehyde while 25% of the enzyme activity remained after a similar fixation in glutaraldehyde. Substantially higher levels of L1210 cell glycosyltransferase activity were retained after a 30 min 2% formaldehyde fixation (60% sialyltransferase; 82% galactosyltransferase), but inhibition by glutaraldehyde was similar to that observed for onion root galactosyltransferase. Glycosyltransferase from formaldehyde-fixed roots was inhbited 35% by lead nitrate, but sialytransferase from formaldehyde-fixed L1210 cells was unaffected by lead ions. These findings are encouraging for further studies aimed at the development of cytochemical technique to localize glycosyltransferase in plant and animal tissues.

scholarly journals Fine Structure and Staining Behaviour of Heterochromatic Segments in Two Plants

1974 ◽  
Vol 14 (3) ◽  
pp. 505-521
Author(s):  
L. F. LACOUR ◽  
B. WELLS
Keyword(s):  
Fine Structure ◽  
Light Microscope ◽  
Mitotic Cycle ◽  
The Other ◽  
Masking Effect ◽  
Root Tips ◽  
Metaphase Chromosomes ◽  
Differential Reactivity ◽  
Scilla Sibirica ◽  
Electron Microscopes

With the use of the light and electron microscopes, the chromosomes of Fritillaria lanceolata and Scilla sibirica are shown to differ in respect of the heterochromatin they contain. In root meristems of the former, the heterochromatic regions (H-segments) were recognizable at all phases of the mitotic cycle by their slighter opacity to electrons than that of euchromatic parts. This was due both to less tight packing of the chromatin fibrils and lower opacity of the fibrils themselves, even though both had the same diameter, about 3 nm. In root tips of the Scilla, the heterochromatin was invariably of similar opacity to euchromatin and thus only recognizable at telophase and interphase as large chromocentres. The opacity to electrons in the heterochromatin of the 2 species, was at all times closely paralleled by the staining behaviour seen with the light microscope in sections (0.07-0.5 µm in thickness) stained with toluidine blue. The disparity in the Fritillaria, as seen in sections with the light microscope, in respect of the stainability of the hetero- and euchromatin, was masked in Feulgen squash preparations of root tips from plants grown at 18-20 °C; at metaphase by the thickness of the chromosomes and at interphase by the density of the chromocentres. When, on the other hand, the plants were grown for 4 days at 2 °C, the masking effect of thickness was circumvented in metaphase chromosomes by differential super-contraction in euchromatin. The implications of these findings in respect to previous interpretations of the differential reactivity of H-segments to low temperature, as well as the phenomenon of enhanced and reduced fluorescence in these segments with fluorochromes are discussed.

Cellular Respiration in Onion Root Tips

1959 ◽  
Vol 120 (3) ◽  
pp. 131-137 ◽  
Author(s):  
W. E. Norris, ◽  
E. J. Harber ◽  
J. E. Butler
Keyword(s):  
Cellular Respiration ◽  
Root Tips ◽  
Onion Root

scholarly journals THE USE OF BISMUTH AS AN ELECTRON STAIN FOR NUCLEIC ACIDS

1963 ◽  
Vol 17 (1) ◽  
pp. 93-103 ◽  
Author(s):  
Peter Albersheim ◽  
Ursula Killias
Keyword(s):  
Nucleic Acids ◽  
Inorganic Phosphate ◽  
In Vitro Experiments ◽  
Root Tips ◽  
Onion Root ◽  
Cell Structures ◽  
Dividing Cells ◽  
Chromatin Material

Evidence is presented to show that bismuth combines in vitro with the phosphate of nucleic acids in a manner similar to its reaction with inorganic phosphate. When tested under similar conditions, protein exhibited no attraction for bismuth. The results of the in vitro experiments, which are of interest within themselves, may be indirectly applicable to in vivo staining. Dividing cells of onion root tips were fixed in OsO4, stained with bismuth, and examined in the electron microscope. The electron opacity of cell structures known to contain nucleic acids was enhanced by bismuth, while organelles known to lack appreciable quantities of DNA or RNA showed little, if any, change. Bismuth is particularly effective as a stain for the chromatin material during interphase and for the chromosomes during division.

Cytokinins and nuclear RNA levels in onion root tips

Planta ◽  
1972 ◽  
Vol 108 (4) ◽  
pp. 363-368 ◽  
Author(s):  
Nathalie Chaly ◽  
George Setterfield
Keyword(s):  
Root Tips ◽  
Onion Root ◽  
Nuclear Rna ◽  
Rna Levels

scholarly journals Toxic and mutagenic activities of surface water from the Chumysh River

2017 ◽  
Vol 7 (2) ◽  
pp. 104-109
Author(s):  
L. P. Khlebova ◽  
N. N. Chernysheva ◽  
A. P. Kraynov
Keyword(s):  
River Water ◽  
Chromosomal Abnormalities ◽  
Mutagenic Activity ◽  
Tap Water ◽  
Control Sample ◽  
Test System ◽  
Root Tips ◽  
Allium Test ◽  
Temporal And Spatial Distribution ◽  
Onion Root

<p>The Allium test system is worldwide used for biological monitoring of environmental pollutants. We have studied toxic and mutagenic activity of water from the Chumysh River, which is one of the largest tributaries of the Upper Ob. Water samples were taken near industrial settlement Talmenka (Altai Territory of Russia) during the spring flood and low autumn water level in 2015. Root tips of <em>Allium cepa</em> L. was used as a biological model. There were examined 30 samples. Purified tap water of medium hardness served as a control sample. After the synchronizing the cell divisions, the onion bulbs with roots reaching a length of 2-3 mm were transferred to glass cups containing the selected samples of River water and cultured for several days at a temperature of +24 ± 1°C. After exposure, root tips were rinsed in distilled water and fixed in a cold mixture of ethanol and acetic acid (3:1). Fixed samples were used after 12-24 h or transferred to 70% alcohol and stored in refrigerator at a temperature of +4°C until required. The fixed materials were hydrolyzed in 1N HCl at 60°C for 5-8 min and squashed in aceto-orcein.<strong> </strong>Prepared slides were viewed under the microscope at a magnification of ×90.<strong> </strong>The mitotic index (MI), the phase indices, the frequency of abnormal mitosis, and chromosomal aberrations were determined by the examination of 500 cells per a replicate (100 cells per slide). We established that the decreased or increased levels of mitotic activity and the frequencies of pathological mitoses (up to 7.9%, P &lt; 0.05) in onion root tips revealed the presence of mitotoxic and genotoxic agents in the Chumysh River water. We found that the most number of chromosomal abnormalities occurs at the stages of meta- or anaphase. The main abnormalities are chromosome laggings in meta- and anaphase, chromosome bridges, chromosome fragments and micronuclei. Their number increased in 5.0-10.8 times compared with the control value. It has been discovered the temporal and spatial distribution of compounds with different toxicity and genotoxicity within a stream. The greatest level of mitotic depression and the highest frequency of chromosomal mutations were observed in the tissues of the onion root tips germinated on the samples collected in low autumn water. The mechanisms of plant adaptation to unfavorable environmental factors are discussed.</p>

EFFECT OF CARBON DIOXIDE ON RESPIRATION OF EXCISED ONION ROOT TIPS IN HIGH-OXYGEN ATMOSPHERES

Soil Science ◽  
1959 ◽  
Vol 88 (3) ◽  
pp. 144-149 ◽  
Author(s):  
W. E. NORRIS ◽  
JOHN D. WIEGAND ◽  
LAMAR JOHANSON
Keyword(s):  
Carbon Dioxide ◽  
High Oxygen ◽  
Root Tips ◽  
Onion Root
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