scholarly journals A Single Genetic Locus, Ckr1, Defines Arabidopsis Mutants in which Root Growth Is Resistant to Low Concentrations of Cytokinin

1992 ◽  
Vol 99 (4) ◽  
pp. 1569-1574 ◽  
Author(s):  
Wenpei Su ◽  
Stephen H. Howell
Keyword(s):  
Root Growth ◽  
Genetic Locus ◽  
Arabidopsis Mutants ◽  
Low Concentrations

scholarly journals Toxicity Studies of Ametryne to Land and Aquatic Organisms

2017 ◽  
Vol 6 (1) ◽  
pp. 8
Author(s):  
Ana Paula Justiniano Régo ◽  
Ederio Dino Bidoia ◽  
Cassiana Maria Reganhan-Coneglian
Keyword(s):  
Seed Germination ◽  
Root Growth ◽  
Test Organism ◽  
Aquatic Organisms ◽  
Terrestrial Ecosystems ◽  
Toxic Effects ◽  
Eruca Sativa ◽  
Daphnia Similis ◽  
Low Concentrations ◽  
Bodies Of Water

The ametryne herbicide is largely used on sugar cane plantation in Brazil. It is persistent in the environment and can be found in bodies of water, impacting the aquatic and terrestrial ecosystems. Generally, in crops are applied mixtures of herbicides in order to obtain a higher success in combating weeds. This study evaluated the toxicity only of ametryne herbicide, without mixture with other herbicides, in order to quantify only the degree of dangerousness. This work evaluated the toxicity of ametryne to one aquatic test organism (Daphnia similis) and two land test organism (Eruca sativa and Lactuca sativa). Immobility of D. similis was evaluated in the presence of ametryne. Influences of ametryne on seed germination and root growth of E. sativa and L. sativa were evaluated. Even at low concentrations (5.00 mg/L), ametryne caused toxic effects on the mobility of D. similis, and 0.25 g/L caused toxic effects on the seeds. Root growth and the percentage of inhibition showed greater sensitivity to ametryne compared with seed germination. Thus, ametryne resulted in toxic effects to the analyzed organisms, which may bring damage to both aquatic and terrestrial ecosystems.

Expression of the high-affinity purine nucleobase transporter in mutant mouse S49 cells does not require a functional wild-type nucleoside-nucleobase transporter

1987 ◽  
Vol 7 (1) ◽  
pp. 97-103
Author(s):  
B Ullman ◽  
J Patrick ◽  
K McCartan
Keyword(s):  
Genetic Locus ◽  
Nucleoside Transport ◽  
Recessive Trait ◽  
Wild Type ◽  
Purine Base ◽  
Purine Bases ◽  
High Affinity ◽  
Low Concentrations ◽  
Guanine And Adenine ◽  
Mutant Cells

A novel type of somatic mutation that causes the expression of a high-affinity purine base permease (B. Aronow, D. Toll, J. Patrick, P. Hollingsworth, K. McCartan, and B. Ullmann, Mol. Cell Biol. 6:2957-2962, 1986) has been inserted into nucleoside transport-deficient S49 cells. Two classes of mutants expressing this nucleobase permease were generated. The first, as exemplified by the AE1HADPAB2 cell line, possessed an augmented capacity to transport low concentrations of the three purine bases, hypoxanthine, guanine, and adenine. The second class of mutants, as typified by the AE1HADPAB5 clone, possessed an augmented capability to translocate low levels of hypoxanthine and guanine, but not adenine. Neither the AE1HADPAB2 nor the AE1HADPAB5 cells could transport nucleosides, suggesting that the expression of the high-affinity base transporter did not reverse the mutation in the nucleoside transport system. The transport of purine bases by both AE1HADPAB2 and AE1HADPAB5 cells was much less sensitive than that by wild-type cells to inhibition by dipyridamole, 4-nitrobenzylthionosine, and N-ethylmaleimide, potent inhibitors of nucleoside and nucleobase transport in wild-type S49 cells. Fusion of the AE1HADPAB2 and AE1HADPAB5 cell lines with wild-type cells indicated that the expression of the high-affinity base transporter behaved in a dominant fashion, while the nucleoside transport deficiency was a recessive trait. These data suggest that the high-affinity purine base transporter of mutant cells and the nucleoside transport function of wild-type cells are products of different genes and that expression of the former probably requires the unmasking or alteration of a specific genetic locus that is silent or different in wild-type cells.

scholarly journals Tropical Wetland Earthworm Vermifluid Promotes Mitotic Activities and Root Growth in Allium cepa at low concentrations

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
Ebenezer Olasunkanmi Dada ◽  
Tirmizhi Abdulganiy ◽  
Stephen Olugbemiga Owa ◽  
Yusuf Olamilekan Balogun ◽  
Emmanuel Olorunleke Oludipe ◽  
...  
Keyword(s):  
Root Growth ◽  
Allium Cepa ◽  
Exposure Period ◽  
Cellular Level ◽  
Microbial Count ◽  
Standard Procedures ◽  
Low Concentrations ◽  
Dividing Cells ◽  
Promote Plant Growth ◽  
Total Fungi

It is well established that earthworms and their products promote plant growth and improve crop yield, but more information about their mechanisms of action, especially at cellular level, is required. This study assessed the enzyme and bacterial activities of vermifluid secreted by a tropical wetland earthworm, Alma millsoni. The effects of the vermifluid on the mitotic activities and root growth of Allium cepa (onions) were evaluated. Vermifluid enzyme and bacterial activities were assessed using standard procedures. Mitotic activities were evaluated using the Allium assay squash technique. Root lengths in onions grown in graduated dilutions of vermifluid were measured using a metre rule. Phosphatase had the highest activity (39.00 ± 3.70 units/ml/min) in the vermifluid, followed by urease (4.90 ± 0.18 units/ml/min), protease (3.20 ± 0.28 units/ml/min), amylase (1.40 ± 0.09 units/ml/min) and lipase (0.001 ± 0.00 units/ml/min). The total microbial count (TBC) and total fungi count (TFC) in the vermifluid were 6.0 × 104 CFU/ml and 2.4 × 105 CFU/ml, respectively. Results also indicated that the lower the vermifluid concentrations, the higher the number of dividing cells and mitotic index in onion roots. Onion roots grown in 10% vermifluid had the highest significant (P < 0.05) root growth of 2.65 ± 0.30 cm, 4.01 ± 0.61 cm, and 4.54 ± 0.62 cm, at 12-hour, 24-hour, and 72-hour exposure period, respectively. The inverse relationships between onion mitotic activities, root growth and vermifluid concentrations imply that the growth-promoting enzymes and other products in vermifluid stimulate cellular root growth better in small concentrations. Keywords: Alma millsoni, earthworm fluid, enzymes, microbial activities, mitosis, phosphatase.

scholarly journals Expression of the high-affinity purine nucleobase transporter in mutant mouse S49 cells does not require a functional wild-type nucleoside-nucleobase transporter.

1987 ◽  
Vol 7 (1) ◽  
pp. 97-103 ◽  
Author(s):  
B Ullman ◽  
J Patrick ◽  
K McCartan
Keyword(s):  
Genetic Locus ◽  
Nucleoside Transport ◽  
Recessive Trait ◽  
Wild Type ◽  
Purine Base ◽  
Purine Bases ◽  
High Affinity ◽  
Low Concentrations ◽  
Guanine And Adenine ◽  
Mutant Cells

A novel type of somatic mutation that causes the expression of a high-affinity purine base permease (B. Aronow, D. Toll, J. Patrick, P. Hollingsworth, K. McCartan, and B. Ullmann, Mol. Cell Biol. 6:2957-2962, 1986) has been inserted into nucleoside transport-deficient S49 cells. Two classes of mutants expressing this nucleobase permease were generated. The first, as exemplified by the AE1HADPAB2 cell line, possessed an augmented capacity to transport low concentrations of the three purine bases, hypoxanthine, guanine, and adenine. The second class of mutants, as typified by the AE1HADPAB5 clone, possessed an augmented capability to translocate low levels of hypoxanthine and guanine, but not adenine. Neither the AE1HADPAB2 nor the AE1HADPAB5 cells could transport nucleosides, suggesting that the expression of the high-affinity base transporter did not reverse the mutation in the nucleoside transport system. The transport of purine bases by both AE1HADPAB2 and AE1HADPAB5 cells was much less sensitive than that by wild-type cells to inhibition by dipyridamole, 4-nitrobenzylthionosine, and N-ethylmaleimide, potent inhibitors of nucleoside and nucleobase transport in wild-type S49 cells. Fusion of the AE1HADPAB2 and AE1HADPAB5 cell lines with wild-type cells indicated that the expression of the high-affinity base transporter behaved in a dominant fashion, while the nucleoside transport deficiency was a recessive trait. These data suggest that the high-affinity purine base transporter of mutant cells and the nucleoside transport function of wild-type cells are products of different genes and that expression of the former probably requires the unmasking or alteration of a specific genetic locus that is silent or different in wild-type cells.

Nitrate and glutamate sensing by plant roots

2005 ◽  
Vol 33 (1) ◽  
pp. 283-286 ◽  
Author(s):  
S. Filleur ◽  
P. Walch-Liu ◽  
Y. Gan ◽  
B.G. Forde
Keyword(s):  
Root Growth ◽  
Lateral Root ◽  
Lateral Roots ◽  
Primary Root ◽  
Root Tip ◽  
Root Tips ◽  
Environmental Signals ◽  
Specific Effects ◽  
Large Numbers ◽  
Low Concentrations

The architecture of a root system plays a major role in determining how efficiently a plant can capture water and nutrients from the soil. Growth occurs at the root tips and the process of exploring the soil volume depends on the behaviour of large numbers of individual root tips at different orders of branching. Each root tip is equipped with a battery of sensory mechanisms that enable it to respond to a range of environmental signals, including nutrients, water potential, light, gravity and touch. We have previously identified a MADS (MCM1, agamous, deficiens and SRF) box gene (ANR1) in Arabidopsis thaliana that is involved in modulating the rate of lateral root growth in response to changes in the external NO3− supply. Transgenic plants have been generated in which a constitutively expressed ANR1 protein can be post-translationally activated by treatment with dexamethasone (DEX). When roots of these lines are treated with DEX, lateral root growth is markedly stimulated but there is no effect on primary root growth, suggesting that one or more components of the regulatory pathway that operate in conjunction with ANR1 in lateral roots may be absent in the primary root tip. We have recently observed some very specific effects of low concentrations of glutamate on root growth, resulting in significant changes in root architecture. Experimental evidence suggests that this response involves the sensing of extracellular glutamate by root tip cells. We are currently investigating the possible role of plant ionotropic glutamate receptors in this sensory mechanism.

scholarly journals Influence of various sources of nitrogen on the growth of Scots pine seedlings and the IAA content in needles

2014 ◽  
Vol 59 (1-4) ◽  
pp. 65-71
Author(s):  
Barbara Kieliszewska-Rokicka ◽  
Maria Rudawska
Keyword(s):  
Root Growth ◽  
Nitrogen Fertilization ◽  
Shoot Growth ◽  
Nitrate Solution ◽  
Calcium Nitrate ◽  
Ammonium Tartrate ◽  
Pine Seedlings ◽  
Low Concentrations ◽  
Shoot Weight ◽  
One Year

One year old pine seedlings transferred from the nursery and potted in a greenhouse were watered with nitrogen solutions of different form and concentration (urea 0.36 mM and 0.90 mM, ammonium tartrate 0.36 mM and 1.79 mM, calcium nitrate 0.36 mM, 1.79 mM and 3.58 mM). After 10 months the growth and IAA content in needles were compared. Nitrogen fertilization affected shoot growth considerably, but its effects on root growth were less pronounced. The highest shoot weight was obtained after application of ammonium tartrate in 1.79 mM concentration. The lowest concentration of urea (0.36 mM) caused the same effect, as did the most concentrated calcium nitrate solution (3.58 mM). Auxine content increased in the needles after nitrogen fertilization as compared with control. The highest accumulation of IAA was found in seedlings treated with low concentrations of urea.

The effect of trifluralin on the root development of seedling cotton

1966 ◽  
Vol 6 (21) ◽  
pp. 214 ◽  
Author(s):  
BB Fischer
Keyword(s):  
Root Growth ◽  
Root Development ◽  
Sand Culture ◽  
Root Weight ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Soil Culture ◽  
Secondary Root ◽  
Low Concentrations ◽  
Loam Soil

Trifluralin (2, 6 dinitrc-N N-dipropyl-4-trifluoro-methylaniline) severely retarded the secondary root development of seedling cotton at very low concentrations in water, sand, and soil culture in the glass house. Although retarded, the seedlings survived at concentrations of 5.0 p.p.m., the highest rate used. In water culture length of secondary roots was reduced at 0.01 p.p.m. In sand culture a concentration of 0.125 p.p.m. significantly reduced the root weight, but in clay-loam soil a concentration of 0.25 p.p.m. was needed to produce the same degree of reduced secondary root growth. No statistically significant retardation in total root growth was obtained when the cotton roots were able to grow in an untreated layer of sand or clay-loam soil, when the trifluralin treated layer was placed either above or below the untreated layer.

Impact of Multi-Walled Carbon Nanotubes to Rye Seedlings

2015 ◽  
Vol 1085 ◽  
pp. 237-241 ◽  
Author(s):  
Alexander A. Gusev ◽  
Olga N. Zaytseva ◽  
Olga A. Selivanova ◽  
Olga V. Zakharova ◽  
Anna Yu. Godymchuk ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Antioxidant Enzymes ◽  
Root Growth ◽  
Stem Growth ◽  
High Concentration ◽  
Photosynthetic System ◽  
Low Concentrations ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Stimulation Of

Multi-Walled Carbon Nanotubes (MWCNTs) cause suppression of rye seeds viability, however in high concentration (1 g/l) they stimulate increase in roots and stems by 20%. At the same time, in low concentrations of MWCNTs root growth suppression is observed, though stimulation of stem growth remains. MWCNTs affect activity of antioxidant enzymes of rye seedlings, thus the greatest stimulation is observed when low and average concentrations of MWCNTs are used. Activity of photosynthetic system of plants considerably increases only when the lowest of the studied concentrations of MWCNTs (0.1 mg/l) is used. Noted tendencies can be considered in further researches of phytotoxic and phytostimulating MWCNTs properties.

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

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