Kinetics of rubidium absorption &amp; translocation by barley

Fried, Maurice; Oberländer, H. E.; Noggle, J. C.

doi:10.1104/pp.36.2.183

Cited by 20 publications

(9 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Lundegardh (14) considers the efflux of ions from vacuoles to be an important component of ion transfer across the root, but this is admittedly a controversial point. Some investigations indicate that accumulation is essentially an irreversible process except under conditions of nutrient stress (4,5), whereas other studies do indicate that ions may be first accumulated and there redistributed in plants (6,17,24,29). Results reported in the subsequent paper ( 11 ) do show that a recycling of chloride occurs between vacuoles and cytoplasm.…”

supporting

confidence: 47%

Uptake and Transport of Radiochloride and Tritiated Water by Various Zones of Onion Roots of Different Chloride Status

Hodges

Vaadia

1964

Plant Physiol.

View full text Add to dashboard Cite

The effect of salt status on ion uptake and transport in plants was recently reviewed by Russell and Barber (23). The rate of ion absorption by excised submerged roots is less in high salt roots than in low salt roots (1, 7). However, the effect of plant salt status on the rate of ion transport to the cut surface of topped plants or to shoots of intact plants is more complex. Some studies show that low salt plants transport ions to the exudation or transpiration stream at a greater rate than do high salt plants (6,19,20,27). Other experiments show just the reverse (6,8,19,21,22) Roots pretreated only with CaSO4 will be referred to as low chloride roots; those pretreated with CaSO4 plus KCI, as high chloride roots. The roots xere cut from the bulbs the night before each experiment and placed in specially constructed lucite boxes and held in the (lark at 25 ± 20. The boxes contained the pretreatment solution and aeration was provided.The lucite boxes (21 X 9 X 5 cm) contained 3 chambers, each 3 cm in length, so that different root zones could be exposed to different solutions. The various zones or chambers will be referred to as A, B, and C for the root tip zone, the middle zone, and the basal zone, respectively. Each chamber held 60 ml of solution. After the roots had been secured (via removable partitions with layers of Scotch Calk and vaseline next to the roots) they were recut so that approximately 1 cm protruded into a large empty chamber (12 cm long). Small glass tubes, supported by a wooden block in the large chamber, were then slipped over the roots in order to collect the exudate. Seven boxes, each containing 15 roots, were used in most experiments. The time required for securing the roots in the boxes was about one hour.The experimental period was initiated l)y (Iraining the pretreatment solution and placing a 2.0 mi:\t KC136 solution (pH 6.6)

show abstract

supporting

confidence: 47%

Uptake and Transport of Radiochloride and Tritiated Water by Various Zones of Onion Roots of Different Chloride Status

Hodges

Vaadia

1964

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…Other investigators (7,8,9,10,16,19) have interpreted similar data for other ions to mean that two separate carrier sites are involved in the active transport of a single ion species. This interpretation appears to be questionable since C/Co values are less than 1 when high external concentrations are used (table I, fig 3).…”

Section: Discussionmentioning

confidence: 85%

“…Fried et al ( 10) and others (7,8,9,11,12,16,17,19) have employed the treatment of enzyme kinetics used by Eadie (5) andl Hofstee (15) for treating ion It = Vmax -Km (Z' TI) I where v, = the velocity of ion absorption, Vmaxthe velocity of ion absorption when the carrier substance is saturated, Kin -Mlichaelis-Menton constant, and M = the external ion concentration.…”

mentioning

confidence: 99%

“…When a range of external ion concentrations are used, a plot of v vs. v/M for ion accumulation frequently yields a curve (7,8,9,10,11,12,16,19 Hyperbolic curves were obtained for both chloride accumulation and chloride transport to the exudation stream when these wxere plotted according to equation I. The data suggest, however, that passive nmovement of chloridle at high external concentrations could account for the curvilinear relationship.…”

mentioning

confidence: 99%

See 1 more Smart Citation

The Kinetics of Chloride Accumulation and Transport in Exuding Roots

Hodges

Vaadia

1964

Plant Physiol.

View full text Add to dashboard Cite

“…It has been suggested that a membranebound ATPase participates in the process (8,9,18,20,22,25) and that the uptake of K+ involves the combination of a hypothetical carrier with the ion in such a way that the intermediate ion-carrier complex that is formed on the outer part of the membrane breaks down irreversibly on the internal side of the membrane releasing the ion inside the cell (3,6,10,11 tinuously aerated distilled H20, and rinsed again 3 times with distilled H20. Seedlings were grown essentially as described by Epstein (4).…”

mentioning

confidence: 99%

Alkylguanidines as Inhibitors of K⁺ Transport in Isolated Barley Roots

Lepe¹,

Avila²

1975

Plant Physiol.

View full text Add to dashboard Cite

It has beeii shown that plants can accunmulate K+ through an energy-dependent process. The effect of alkylguanidines, in particular octylguanidine on the uptake of 86Rb+ by excised barley roots (Hordeum vulgare var. Apizaco LV-72), has been studied. s6Rb+ was used as tracer of K+. The uptake of 86Rb+ which is linear with time and shows saturation kinetics is inhibited by octylguanidine. Half-maximal (5,6,14,15).Little is known with respect to the molecular events that occur during K+ translocation. It has been suggested that a membranebound ATPase participates in the process (8,9,18,20,22,25) and that the uptake of K+ involves the combination of a hypothetical carrier with the ion in such a way that the intermediate ion-carrier complex that is formed on the outer part of the membrane breaks down irreversibly on the internal side of the membrane releasing the ion inside the cell (3,6,10,11). In this work, a possible action of various alkylguanidines on the absorption of K+ by excised barley roots has been explored. The effect of alkylguanidines on K+ uptake in plants was studied because these lipophilic cations (their pKa is around 12) have been shown to inhibit numerous metal ion-dependent systems (1,2,12,13,16,23,24,(27)(28)(29) tinuously aerated distilled H20, and rinsed again 3 times with distilled H20. Seedlings were grown essentially as described by Epstein (4). The seeds were placed on a plastic screen covered with cheesecloth which was supported by a 7-liter plastic tank containing 5 liters of 0.5 mm CaSO4; the corners of the cheesecloth were dipped into the solution. The tank was placed in the dark and covered with a plastic cover. The temperature was 24 C + 3 and vigorous aeration was provided.Roots from 6-day-old seedlings were used for the absorption experiments. The roots were cut in 2-cm segments (the 3-cm basal portions and 5-cm apical portions of the roots were discarded) and washed 3 times with ice-cold distilled H20. The tissue prepared in this form is a highly homogeneous material. Batches of 16 segments were maintained in distilled H20 until the experiment was initiated. The uptake experiments were carried out by incubating barley roots in 4 ml of a mixture that contained 20 mm maleic buffer (pH 6), 0.05 mm CaSO4, and different concentrations of the indicated alkylguanidines and RbCl according to the experiment. Experiments on the ion absorption by excised tissues of higher plants have shown that potassium and rubidium behave virtually as isotopes of the same element (21). Therefore, l6Rb+ was used as a radioactive analog of K+. The incubation medium was maintained at 30 C and continuously shaken in a Dubnoff incubator. The solution was equilibrated for a 10-min period prior to the addition of the roots. At the times indicated in the respective figures (see under "Results"), the solution was decanted, and the roots were rinsed for 30 sec with a mixture of 30 ml of ice-cold 0.5 mm CaSO4 and 5 mm RbCl to eliminate adsorbed lGRb+. Subsequently the roots were washed for 30 min in 15 ml...

show abstract

Kinetics of rubidium absorption & translocation by barley

Cited by 20 publications

References 22 publications

Uptake and Transport of Radiochloride and Tritiated Water by Various Zones of Onion Roots of Different Chloride Status

Uptake and Transport of Radiochloride and Tritiated Water by Various Zones of Onion Roots of Different Chloride Status

The Kinetics of Chloride Accumulation and Transport in Exuding Roots

Alkylguanidines as Inhibitors of K⁺ Transport in Isolated Barley Roots

Contact Info

Product

Resources

About

Kinetics of rubidium absorption & translocation by barley

Cited by 20 publications

References 22 publications

Uptake and Transport of Radiochloride and Tritiated Water by Various Zones of Onion Roots of Different Chloride Status

Uptake and Transport of Radiochloride and Tritiated Water by Various Zones of Onion Roots of Different Chloride Status

The Kinetics of Chloride Accumulation and Transport in Exuding Roots

Alkylguanidines as Inhibitors of K+ Transport in Isolated Barley Roots

Contact Info

Product

Resources

About

Alkylguanidines as Inhibitors of K⁺ Transport in Isolated Barley Roots