SsHKT1;1 is a potassium transporter of the C3 halophyte Suaeda salsa that is involved in salt tolerance

2014 ◽  
Vol 41 (8) ◽  
pp. 790 ◽  
Author(s):  
Qun Shao ◽  
Ning Han ◽  
Tonglou Ding ◽  
Feng Zhou ◽  
Baoshan Wang
Keyword(s):  
Salt Tolerance ◽  
Yeast Strain ◽  
Suaeda Salsa ◽  
K Uptake ◽  
Potassium Transporter ◽  
Cation Homeostasis ◽  
Heterologous Expression Systems ◽  
K Concentration ◽  
Low K

SsHKT1;1, a HKT1 homologue, was isolated from the C3 halophyte Suaeda salsa L. and its ion transport properties were investigated in heterologous systems. The expression of SsHKT1;1 suppressed a K+ transport-defective phenotype of the yeast strain CY162 (Δtrk1Δtrk2), suggesting the enhancement of K+ uptake with SsHKT1;1. However, it did not suppress the salt-sensitive phenotype of the yeast strain G19 (Δena1–4), which lacks a major component of Na+ efflux. Transgenic Arabidopsis thaliana (L.) Heynh. plants overexpressing SsHKT1;1 showed enhanced salt tolerance and increased shoot K+ concentration, whereas no significant changes in shoot Na+ concentration were observed. S. salsa was also used to investigate K+ uptake properties under salinity. The K+ transporters in the roots selectively mediated K+ uptake irrespective of external Na+ and their inhibitor did not affect Na+ uptake at low K+. Thus, both molecular and physiological studies provide strong in vivo evidence that SsHKT1;1 mainly acts as a potassium transporter in heterologous expression systems and S. salsa, and that it is involved in salt tolerance by taking part in the maintenance of cytosolic cation homeostasis, particularly, in the maintenance of K+ nutrition under salinity.

Modest dietary K+ restriction provokes insulin resistance of cellular K+ uptake and phosphorylation of renal outer medulla K+ channel without fall in plasma K+ concentration

2006 ◽  
Vol 290 (5) ◽  
pp. C1355-C1363 ◽  
Author(s):  
Pei Chen ◽  
John P. Guzman ◽  
Patrick K. K. Leong ◽  
Li E. Yang ◽  
Anjana Perianayagam ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Renal Excretion ◽  
No Reduction ◽  
Control Diet ◽  
Diet Group ◽  
K Channel ◽  
K Uptake ◽  
Outer Medulla ◽  
K Concentration

Extracellular K+ concentration ([K+]) is closely regulated by the concerted regulatory responses of kidney and muscle. In this study, we aimed to define the responses activated when dietary K+ was moderately reduced from a control diet (1.0% K+) to a 0.33% K+ diet for 15 days. Although body weight and baseline plasma [K+] (4.0 mM) were not reduced in the 0.33% K+ group, regulatory responses to conserve plasma [K+] were evident in both muscle and kidney. Insulin-stimulated clearance of K+ from the plasma was estimated in vivo in conscious rats with the use of tail venous and arterial cannulas. During infusion of insulin·(50 mU·kg−1·min−1), plasma [K+] level fell to 3.2 ± 0.1 mM in the 1.0% K+ diet group and to only 3.47 ± 0.07 mM in the 0.33% K+ diet group ( P < 0.01) with no reduction in urinary K+ excretion, which is evidence of insulin resistance to cellular K+ uptake. Insulin-stimulated cellular K+ uptake was quantitated by measuring the K+ infusion rate necessary to clamp plasma K+ at baseline (in μmol·kg−1·min−1) during 5 mU of insulin·kg−1·min−1 infusion: 9.7 ± 1.5 in 1% K+ diet was blunted to 5.2 ± 1.7 in the 0.33% K+ diet group ( P < 0.001). Muscle [K+] and Na+-K+-ATPase activity and abundance were unchanged during the 0.33% K+ diet. Renal excretion, which was measured overnight in metabolic cages, was reduced by 80%, from 117.6 ± 10.5 μmol/h/animal (1% K+ diet) to 24.2 ± 1.7 μmol/h/animal (0.33% K+ diet) ( P < 0.001). There was no significant change in total abundance of key renal K+ transporters, but 50% increases in both renal PTK cSrc abundance and ROMK phosphorylation in the 0.33% K+ vs. 1% K+ diet group, previously established to be associated with internalization of ROMK. These results indicate that plasma [K+] can be maintained during modest K+ restriction due to a decrease in insulin-stimulated cellular K+ uptake as well as renal K+ conservation mediated by inactivation of ROMK, both without a detectable change in plasma [K+]. The error signals inciting and maintaining these responses remain to be identified.

Uptake and distribution of potassium by grapevine rootstocks and its implication for grape juice pH of scion varieties

1989 ◽  
Vol 29 (5) ◽  
pp. 707 ◽  
Author(s):  
EH Ruhl
Keyword(s):  
Nutrient Solution ◽  
Screening Method ◽  
Grape Juice ◽  
Low Ph ◽  
K Uptake ◽  
Plant Parts ◽  
High K ◽  
K Concentration ◽  
Positive Correlations ◽  
Low K

Differences in petiole K+ concentration of ungrafted grapevine rootstocks grown under field conditions at Merbein, Victoria, were compared with the rootstock effects on grape juice pH of the scion varieties Chardonnay and Ruby Cabernet. Significant positive correlations were obtained between grape juice pH of the scion varieties on various rootstocks and K+ accumulation in the petioles of ungrafted rootstock vines. Rootstock varieties that contributed to high pH in the grape juice of the scion (e.g. Freedom, Dog Ridge, Rupestris du Lot) showed high K+ concentrations in their petioles, while those rootstocks that contributed to low pH in the grape juice of the scion (e.g. 140 Ruggeri, 1202 Couderc, 110 Richter), had low K+ concentrations in their petioles. In 2 water culture experiments in the glasshouse, K+ uptake and distribution in ungrafted rootstock vines was examined at different K+ levels. In the first experiment the rootstocks 140 Ruggeri and Freedom had similar K+ concentrations in the various plant parts when grown in nutrient solution with 0.1 mmol K+/L. With K+ concentrations of 1, 2, and 10 mmol/L in the nutrient solution Freedom had significantly higher K+ contents in leaves and petioles than 140 Ruggeri. When K+ supply was increased from 1 to 2 mmol/L, K+ concentrations in the various plant parts were not significantly increased. However, when the supply was increased to 10 mmol/L, K t concentrations were significantly different. In the second experiment with K+ levels of 1 and 10 mmol/L, higher K+ contents were obtained in the basal and apical leaves of Dog Ridge and Ramsey compared with 140 Ruggeri, Schwarzmann, 1103 Paulsen and Sultana, while in roots, 140 Ruggeri, 110 Richter and Sultana had the highest K+ contents. Dog Ridge and Rarnsey are both known to increase scion grape juice K+ concentration and pH of the scion variety, while 140 Ruggeri and 1103 Paulsen contribute to low grape juice K+ concentration and pH. The results demonstrate that differences between rootstocks in the extent of K+ accumulation in the shoot are a major determinant of the rootstock effects on grape juice pH. The extent of K+ accumulation can best be measured in basal leaves or petioles. This provides a screening method for the evaluation of rootstocks which restrict K+ accumulation and contribute to lower grape juice pH.

scholarly journals Halophytic Hordeum brevisubulatum HbHAK1 Facilitates Potassium Retention and Contributes to Salt Tolerance

2020 ◽  
Vol 21 (15) ◽  
pp. 5292
Author(s):  
Haiwen Zhang ◽  
Wen Xiao ◽  
Wenwen Yu ◽  
Ying Jiang ◽  
Ruifen Li
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Expression Patterns ◽  
High Salt ◽  
Yeast Cells ◽  
K Uptake ◽  
Efficient Uptake ◽  
Potassium Retention ◽  
Low K ◽  
Hordeum Brevisubulatum

Potassium retention under saline conditions has emerged as an important determinant for salt tolerance in plants. Halophytic Hordeum brevisubulatum evolves better strategies to retain K+ to improve high-salt tolerance. Hence, uncovering K+-efficient uptake under salt stress is vital for understanding K+ homeostasis. HAK/KUP/KT transporters play important roles in promoting K+ uptake during multiple stresses. Here, we obtained nine salt-induced HAK/KUP/KT members in H. brevisubulatum with different expression patterns compared with H. vulgare through transcriptomic analysis. One member HbHAK1 showed high-affinity K+ transporter activity in athak5 to cope with low-K+ or salt stresses. The expression of HbHAK1 in yeast Cy162 strains exhibited strong activities in K+ uptake under extremely low external K+ conditions and reducing Na+ toxicity to maintain the survival of yeast cells under high-salt-stress. Comparing with the sequence of barley HvHAK1, we found that C170 and R342 in a conserved domain played pivotal roles in K+ selectivity under extremely low-K+ conditions (10 μM) and that A13 was responsible for the salt tolerance. Our findings revealed the mechanism of HbHAK1 for K+ accumulation and the significant natural adaptive sites for HAK1 activity, highlighting the potential value for crops to promote K+-uptake under stresses.

Hair cell changes after cationic stimulation of corti's organ

1989 ◽  
Vol 47 ◽  
pp. 798-799
Author(s):  
Cesar D. Fermin ◽  
Hans-Peter Zenner
Keyword(s):  
Organ Of Corti ◽  
Cross Sectional ◽  
Surface Areas ◽  
High K ◽  
Anatomical Arrangement ◽  
Cell Cytosol ◽  
High Concentrations ◽  
K Concentration ◽  
Cell Changes

Contraction of outer and inner hair cells (OHC&IHC) in the Organ of Corti (OC) of the inner ear is necessary for sound transduction. Getting at HC in vivo preparations is difficult. Thus, isolated HCs have been used to study OHC properties. Even though viability has been shown in isolated (iOHC) preparations by good responses to current and cationic stimulation, the contribution of adjoining cells can not be explained with iOHC preparations. This study was undertaken to examine changes in the OHC after expossure of the OHC to high concentrations of potassium (K) and sodium (Na), by carefully immersing the OC in either artifical endolymph or perilymph. After K and Na exposure, OCs were fixed with 3% glutaraldehyde, post-fixed in osmium, separated into base, middle and apex and embedded in Araldite™. One μm thick sections were prepared for analysis with the light and E.M. Cross sectional areas were measured with Bioquant™ software.Potassium and sodium both cause isolated guinea pig OHC to contract. In vivo high K concentration may cause uncontrolled and sustained contractions that could contribute to Meniere's disease. The behavior of OHC in the vivo setting might be very different from that of iOHC. We show here changes of the cell cytosol and cisterns caused by K and Na to OHC in situs. The table below shows results from cross sectional area measurements of OHC from OC that were exposed to either K or Na. As one would expect, from the anatomical arrangement of the OC, OHC#l that are supported by rigid tissue would probably be displaced (move) less than those OHC located away from the pillar. Surprisingly, cells in the middle turn of the cochlea changed their surface areas more than those at either end of the cochlea. Moreover, changes in surface area do not seem to differ between K and Na treated OCs.

Potassium depletion improves myocardial potassium uptake in vivo

2004 ◽  
Vol 287 (1) ◽  
pp. C135-C141 ◽  
Author(s):  
Henning Bundgaard
Keyword(s):  
Uptake Rate ◽  
High Plasma ◽  
Potassium Depletion ◽  
Uptake Capacity ◽  
K Uptake ◽  
Impulse Generation ◽  
Uptake Rates ◽  
Clinical Interest ◽  
A Minor

Potassium depletion (KD) is a very common clinical entity often associated with adverse cardiac effects. KD is generally considered to reduce muscular Na-K-ATPase density and secondarily reduce K uptake capacity. In KD rats we evaluated myocardial Na-K-ATPase density, ion content, and myocardial K reuptake. KD for 2 wk reduced plasma K to 1.8 ± 0.1 vs. 3.5 ± 0.2 mM in controls ( P < 0.01, n = 7), myocardial K to 80 ± 1 vs. 86 ± 1 μmol/g wet wt ( P < 0.05, n = 7), increased Mg, and induced a tendency to increased Na. Myocardial Na-K-ATPase α2-subunit abundance was reduced by ∼30%, whereas increases in α1- and K-dependent pNPPase activity of 24% ( n = 6) and 13% ( n = 6), respectively, were seen. This indicates an overall upregulation of the myocardial Na-K pump pool. KD rats tolerated a higher intravenous KCl dose. KCl infusion until animals died increased myocardial K by 34% in KD rats and 18% in controls ( P < 0.05, n = 6 for both) but did not induce different net K uptake rates between groups. However, clamping plasma K at ∼5.5 mM by KCl infusion caused a higher net K uptake rate in KD rats (0.22 ± 0.04 vs. 0.10 ± 0.03 μmol·g wet wt−1·min−1; P < 0.05, n = 8). In conclusion, a minor KD-induced decrease in myocardial K increased Na-K pump density and in vivo increased K tolerance and net myocardial K uptake rate during K repletion. Thus the heart is protected from major K losses and accumulates considerable amounts of K during exposure to high plasma K. This is of clinical interest, because a therapeutically induced rise in myocardial K may affect contractility and impulse generation-propagation and may attenuate increased myocardial Na, the hallmark of heart failure.

Electrogenic Na+ Transport in a Crustacean Coxal Receptor

1979 ◽  
Vol 78 (1) ◽  
pp. 29-45
Author(s):  
MAURIZIO MIROLLI
Keyword(s):  
Steady State ◽  
Membrane Potential ◽  
Input Resistance ◽  
Scylla Serrata ◽  
Partial Action ◽  
State Response ◽  
Electrogenic Na Pump ◽  
K Concentration ◽  
Low K ◽  
In Cells

1. The response of the coxal receptors of the crab Scylla serrata to step stretches consisted of a partial action potential, Vα, followed by a steady-state depolarization, V8. The input resistance of the fibre was reduced during V8. 2. In the absence of stimulation, the dendrites of the receptors depolarized when external Na+ was substituted with choline or Li+, and when the external K+ concentration was increased or decreased. The dendrites also depolarized when ouabain was added to the saline. 3. The amplitude of both Vα and V8 was dependent on external Na+. In cells which were depolarized by ouabain, the amplitude of V8 increased when the K+ concentration of the saline was reduced. 4. V8 was followed by a small, but long-lasting, after-potential which was depolarizing when the membrane potential was between −70 and −60 mV. In cells depolarized by ouabain or by low K+ saline, the after-potential became hyperpolarizing. 5. When trains of brief stretches (each 5 ms in duration) were used as stimuli, the cells responded with trains of Vα responses. During this tetanic stimulation the cells hyperpolarized; cessation of the stimulus train was followed by a long-lasting hyperpolarization (PTH). 6. PTH was abolished in Li+ saline, in low K+ saline, and in the presence of ouabain. In control or in low K+ saline, PTH was not accompanied by a decrease in the input resistance of the fibres. 7. It is concluded that an electrogenic Na+ pump (or equivalent process) contributes a substantial fraction of the membrane potential of the unstimulated coxal receptors. Pump activity could be increased by Na+-loading the distal part of the cells with trains of Vα responses. By contrast, during the steady-state response to stretch, the pump was not activated.

scholarly journals Further Observations on the Regulation of KCl ABSORPTION ACROSS LOCUST RECTUM

1985 ◽  
Vol 116 (1) ◽  
pp. 153-167
Author(s):  
J. W. HANRAHAN ◽  
J. E. PHILLIPS
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Membrane Conductance ◽  
Short Circuit Current ◽  
Membrane Resistance ◽  
Open Circuit ◽  
High K ◽  
K Concentration ◽  
K Permeability

1. Electrophysiological and tracer flux techniques were used to studyregulation of KC1 reabsorption across locust recta. Physiologically high K+levels (100 mmolI−1) on the lumen side stimulated net 36Cl flux and reduced the theoretical energy cost of anion transport under open-circuit conductions. 2. The stimulation of short-circuit current (Ibc i.e. active C− absorption) by crude corpora cardiaca extracts (CC) was not dependent on exogenous Ca2+. Stimulations of Ibc were greatly enhanced in the presence of theophylline, indicating that the rate of synthesis of cAMP is increased by CC extracts. High CC levels lowered transepithelial resistance (Rt), suggesting that chloride transport stimulating hormone (CTSH) regulates both active Cl− absorption and counter-ion (K+) permeability. 3. High mucosal osmolarity or K+ concentration decreased Ibc and caused a disproportionately large increase in Rt, consistent with a decrease in theshunt (K+) conductance. Measurements of relative mucosal-to-serosal membrane resistance confirmed that high mucosal K+ levels reduced apical membrane conductance. Lowering mucosal pH to values observed in vivo atthe end of resorptive cycles also inhibited Ibc, apparently without affecting K+ permeability.

scholarly journals Aspects of potassium and magnesium uptake by oats.

1974 ◽  
Vol 22 (4) ◽  
pp. 237-244
Author(s):  
A.C. Schuffelen
Keyword(s):  
Direct Relationship ◽  
Common Mechanism ◽  
Specific Mechanism ◽  
K Uptake ◽  
Uptake Mechanism ◽  
Water Culture ◽  
Mg Deficiency ◽  
Magnesium Uptake ◽  
Low K ◽  
Solution Acidity

Data from a range of experiments with oats in water culture indicated that the occurrence of Mg deficiency had only a slight direct relationship with solution acidity. It was calculated that about 3% of the total mechanism for the uptake of K and Mg consisted of a specific mechanism for Mg uptake, 30% of a specific mechanism for K uptake, and 67% of a common mechanism. It was not clear whether one or more systems were involved. At very low K concentrations the specific K uptake mechanism could also take up Na. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals ZMK1 Is Involved in K+ Uptake and Regulated by Protein Kinase ZmCIPK23 in Zea mays

2021 ◽  
Vol 12 ◽  
Author(s):  
Wu Han ◽  
Yun Ji ◽  
Wei Wu ◽  
Jin-Kui Cheng ◽  
Han-Qian Feng ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Growth And Development ◽  
Mineral Elements ◽  
Plant Roots ◽  
Plant Growth And Development ◽  
K Uptake ◽  
Uptake Mechanism ◽  
Uptake Activity ◽  
Electrophysiological Characterization ◽  
Low K

Potassium (K+) is one of essential mineral elements for plant growth and development. K+ channels, especially AKT1-like channels, play crucial roles in K+ uptake in plant roots. Maize is one of important crops; however, the K+ uptake mechanism in maize is little known. Here, we report the physiological functions of K+ channel ZMK1 in K+ uptake and homeostasis in maize. ZMK1 is a homolog of Arabidopsis AKT1 channel in maize, and mainly expressed in maize root. Yeast complementation experiments and electrophysiological characterization in Xenopus oocytes indicated that ZMK1 could mediate K+ uptake. ZMK1 rescued the low-K+-sensitive phenotype of akt1 mutant and enhanced K+ uptake in Arabidopsis. Overexpression of ZMK1 also significantly increased K+ uptake activity in maize, but led to an oversensitive phenotype. Similar to AKT1 regulation, the protein kinase ZmCIPK23 interacted with ZMK1 and phosphorylated the cytosolic region of ZMK1, activating ZMK1-mediated K+ uptake. ZmCIPK23 could also complement the low-K+-sensitive phenotype of Arabidopsis cipk23/lks1 mutant. These findings demonstrate that ZMK1 together with ZmCIPK23 plays important roles in K+ uptake and homeostasis in maize.

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