scholarly journals Potassium in Root Growth and Development

Plants ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 435 ◽  
Author(s):  
Marek Sustr ◽  
Ales Soukup ◽  
Edita Tylova
Keyword(s):  
Root Growth ◽  
Membrane Trafficking ◽  
Growth Response ◽  
Plant Stress ◽  
Physiological Role ◽  
Mobile Element ◽  
Plant Responses ◽  
Nitrogen And Phosphorus ◽  
Wide Range ◽  
K Transport

Potassium is an essential macronutrient that has been partly overshadowed in root science by nitrogen and phosphorus. The current boom in potassium-related studies coincides with an emerging awareness of its importance in plant growth, metabolic functions, stress tolerance, and efficient agriculture. In this review, we summarized recent progress in understanding the role of K+ in root growth, development of root system architecture, cellular functions, and specific plant responses to K+ shortage. K+ transport is crucial for its physiological role. A wide range of K+ transport proteins has developed during evolution and acquired specific functions in plants. There is evidence linking K+ transport with cell expansion, membrane trafficking, auxin homeostasis, cell signaling, and phloem transport. This places K+ among important general regulatory factors of root growth. K+ is a rather mobile element in soil, so the absence of systemic and localized root growth response has been accepted. However, recent research confirms both systemic and localized growth response in Arabidopsis thaliana and highlights K+ uptake as a crucial mechanism for plant stress response. K+-related regulatory mechanisms, K+ transporters, K+ acquisition efficiency, and phenotyping for selection of K+ efficient plants/cultivars are highlighted in this review.

scholarly journals Short-Term Growth Response to Growth Regulators In Roots of Zea Mays

1968 ◽  
Vol 21 (2) ◽  
pp. 201 ◽  
Author(s):  
DE Bottrill ◽  
JB Hanson
Keyword(s):  
Root Growth ◽  
Growth Response ◽  
Similar Degree ◽  
Dichlorophenoxyacetic Acid ◽  
Short Term ◽  
Irreversible Inhibition ◽  
Wide Range ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Indole 3 Acetic Acid

A study was made of the inhibition of root growth in Z. mays by 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,6-trichlorophenoxyacetic acid (2,4,6�T), and indole-3-acetic acid (IAA) over a wide range of concentrations. IAA and 2,4�D caused identical responses whereas the response to 2,4,6-T was different. Application of 2,4.D or IAA at concentrations of 4�5xl0-4M for 5 min resulted in an immediate reversible inhibition of root growth whereas long-term application gave an irreversible inhibition. The same concentration of 2,4,6-T caused a similar degree of inhibition of root growth, but only after an extended treatment, and the roots could then recover from the inhibition in the presence of the chemical.

Role of phosphorus fertiliser banding and the ratio of nitrate to ammonium on the uptake of phosphorus and wheat growth: a glasshouse study

2002 ◽  
Vol 42 (8) ◽  
pp. 1095 ◽  
Author(s):  
G. R. Valizadeh ◽  
Z. Rengel ◽  
A. W. Rate
Keyword(s):  
Root Growth ◽  
Soil Type ◽  
Growth Response ◽  
Phosphorus Content ◽  
Phosphorus Uptake ◽  
Nitrogen And Phosphorus ◽  
Wheat Growth ◽  
Nitrogen Fertiliser ◽  
Phosphorus Fertiliser

While it is known that nitrogen fertilisers improve phosphorus uptake depending on soil type and pH, the role in phosphorus uptake of the ratio of nitrate to ammonium in nitrogen fertiliser banded with phosphorus fertiliser is unclear. The present glasshouse study investigated the wheat growth response to different rates of application and banding depths (5 and 15 cm) of nitrogen and phosphorus, and mixing of phosphorus fertiliser with soil. The effect of 2 forms of nitrogen (ammonium and nitrate) banded with phosphorus fertiliser was also studied.Both banding depths increased phosphorus uptake and wheat growth more than mixing fertiliser throughout the soil. Banding at the 5 cm depth increased phosphorus uptake efficiency and wheat growth more than banding at the 15 cm depth. The highest shoot and root growth and phosphorus content were found when the nitrate : ammonium ratio was 50 : 50 and 75 : 25, with a slight decline at 100 : 0. The treatments with a large proportion of ammonium suppressed the growth of wheat and, consequently, reduced total phosphorus content. It was concluded that banding nitrate and ammonium at ratios 50 : 50, 75 : 25 and 100 : 0 with phosphorus fertiliser at 5 cm depth was optimal for increasing phosphorus uptake and wheat growth.

scholarly journals The Endosomal Recycling Pathway—At the Crossroads of the Cell

2020 ◽  
Vol 21 (17) ◽  
pp. 6074
Author(s):  
Mary J. O’Sullivan ◽  
Andrew J. Lindsay
Keyword(s):  
Membrane Trafficking ◽  
Molecular Mechanisms ◽  
Physiological Role ◽  
Human Pathogens ◽  
Transport Pathways ◽  
Endosomal Recycling ◽  
Wide Range ◽  
Secretory Transport ◽  
Recycling Pathway

The endosomal recycling pathway lies at the heart of the membrane trafficking machinery in the cell. It plays a central role in determining the composition of the plasma membrane and is thus critical for normal cellular homeostasis. However, defective endosomal recycling has been linked to a wide range of diseases, including cancer and some of the most common neurological disorders. It is also frequently subverted by many diverse human pathogens in order to successfully infect cells. Despite its importance, endosomal recycling remains relatively understudied in comparison to the endocytic and secretory transport pathways. A greater understanding of the molecular mechanisms that support transport through the endosomal recycling pathway will provide deeper insights into the pathophysiology of disease and will likely identify new approaches for their detection and treatment. This review will provide an overview of the normal physiological role of the endosomal recycling pathway, describe the consequences when it malfunctions, and discuss potential strategies for modulating its activity.

Deinking sludge influences biomass, nitrogen and phosphorus status of several grass and legume species

1997 ◽  
Vol 77 (4) ◽  
pp. 693-702 ◽  
Author(s):  
A. Fierro ◽  
J. Norrie ◽  
A. Gosselin ◽  
C. J. Beauchamp
Keyword(s):  
Soil Amendment ◽  
Mineral Soil ◽  
Nitrogen And Phosphorus ◽  
Agropyron Elongatum ◽  
Festuca Ovina ◽  
Melilotus Officinalis ◽  
Medicago Lupulina ◽  
Wide Range ◽  
Galega Orientalis ◽  
Four Levels

In a greenhouse study, deinking sludge was evaluated as a soil amendment supplemented with four nitrogen (N) fertilization levels for the growth of the grasses Agropyron elongatum (Host.) Beauv. (tall wheatgrass), Alopecurus pratensis L. (meadow foxtail), Festuca ovina var. duriuscula (L). Koch (hard fescue), and four levels of phosphorus (P) for the growth of the legumes Galega orientalis Lam. (galega), Medicago lupulina L. (black medic), Melilotus officinalis (L.) Lam (yellow sweet clover). Fertilizers were applied on the basis of sludge level to maintain uniform carbon (C)/N or C/P ratios across sludge treatments. In one experiment, sand was mixed with 0, 10, 20 or 30% sludge while, in a second experiment, mineral soil was mixed with 0, 27, 53 or 80% sludge (vol/vol). In sand mixtures of 30 and 20% sludge, grasses had similar or greater growth than in unamended mineral soil when N was added at about 6.5 and 8.4 g kg−1 deinking sludge, respectively. For all legumes but Medicago lupulina, P at about 0.8 g kg−1 sludge was required for these sand mixtures. In soil mixtures of 53 and 27% sludge, grasses grew well when supplemental N was about 5.3 and 6.9 g kg−1 sludge, respectively. Legumes required P at 0.5 and 1.2 g kg−1 sludge, respectively. In general, growth was closely related to total amount of added N or P in spite of the wide range of C/N or C/P ratios. When growing in media amended with sludge, grasses needed higher tissue N concentration for an equivalent growth than in control soil; legumes had similar tissue P concentration. The grasses Agropyron elongatum and Alopecurus pratensis as well as the legumes Melilotus officinalis and Galega orientalis are promising species for field testing, based on dry matter production. Deinking sludge can be used as soil amendment when adequate N and P supplements are provided. Key words: Soil amendment, papermill sludge, Agropyron elongatum, Alopecurus pratensis, Festuca ovina, Medicago lupulina, Galega orientalis, Melilotus officinalis

scholarly journals Lipase Immobilization in Mesoporous Silica Nanoparticles for Biofuel Production

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 629
Author(s):  
Aniello Costantini ◽  
Valeria Califano
Keyword(s):  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Mechanical Stability ◽  
Mesoporous Silica Nanoparticles ◽  
Physiological Role ◽  
Biodiesel Production ◽  
Biofuel Production ◽  
Hydroxyl Groups ◽  
Lipase Immobilization ◽  
Wide Range

Lipases are ubiquitous enzymes whose physiological role is the hydrolysis of triacylglycerol into fatty acids. They are the most studied and industrially interesting enzymes, thanks to their versatility to promote a plethora of reactions on a wide range of substrates. In fact, depending on the reaction conditions, they can also catalyze synthesis reactions, such as esterification, acidolysis and transesterification. The latter is particularly important for biodiesel production. Biodiesel can be produced from animal fats or vegetable oils and is considered as a biodegradable, non-toxic and renewable energy source. The use of lipases as industrial catalysts is subordinated to their immobilization on insoluble supports, to allow multiple uses and use in continuous processes, but also to stabilize the enzyme, intrinsically prone to denaturation with consequent loss of activity. Among the materials that can be used for lipase immobilization, mesoporous silica nanoparticles represent a good choice due to the combination of thermal and mechanical stability with controlled textural characteristics. Moreover, the presence of abundant surface hydroxyl groups allows for easy chemical surface functionalization. This latter aspect has the main importance since lipases have a high affinity with hydrophobic supports. The objective of this work is to provide an overview of the recent progress of lipase immobilization in mesoporous silica nanoparticles with a focus on biodiesel production.

scholarly journals Ozone damage, detoxification and the role of isoprenoids – new impetus for integrated models

2016 ◽  
Vol 43 (4) ◽  
pp. 324 ◽  
Author(s):  
Supriya Tiwari ◽  
Rüdiger Grote ◽  
Galina Churkina ◽  
Tim Butler
Keyword(s):  
Stomatal Conductance ◽  
Environmental Conditions ◽  
Economic Losses ◽  
Plant Responses ◽  
Damage Scenarios ◽  
Biochemical Processes ◽  
Wide Range ◽  
Defence Responses ◽  
High Concentrations ◽  
The Impact

High concentrations of ozone (O3) can have significant impacts on the health and productivity of agricultural and forest ecosystems, leading to significant economic losses. In order to estimate this impact under a wide range of environmental conditions, the mechanisms of O3 impacts on physiological and biochemical processes have been intensively investigated. This includes the impact on stomatal conductance, the formation of reactive oxygen species and their effects on enzymes and membranes, as well as several induced and constitutive defence responses. This review summarises these processes, discusses their importance for O3 damage scenarios and assesses to which degree this knowledge is currently used in ecosystem models which are applied for impact analyses. We found that even in highly sophisticated models, feedbacks affecting regulation, detoxification capacity and vulnerability are generally not considered. This implies that O3 inflicted alterations in carbon and water balances cannot be sufficiently well described to cover immediate plant responses under changing environmental conditions. Therefore, we suggest conceptual models that link the depicted feedbacks to available process-based descriptions of stomatal conductance, photosynthesis and isoprenoid formation, particularly the linkage to isoprenoid models opens up new options for describing biosphere-atmosphere interactions.

Growth responses in red deer hinds from 16-24 months of age when fed two energy levels during their second winter

1998 ◽  
Vol 1998 ◽  
pp. 141-141
Author(s):  
M H Davies ◽  
D W Deakin
Keyword(s):  
Growth Response ◽  
Red Deer ◽  
Energy Levels ◽  
Growth Restriction ◽  
Growth Responses ◽  
Wide Range ◽  
Feeding Regimes ◽  
Cost Of Production ◽  
Red Meats

It is important that venison competes with other red meats in efficiency and cost of production. The growth responses of farmed red deer during the first 15-18 months of life have been well defined under a wide range of feeding and daylength regimes (Davies, 1995). However there is a need to examine less intensive systems of production which aim to maximise growth from grazed grass, following various growth-restriction feeding regimes during winter. The objective of this experiment was to quantify the growth response in 16-24 month old hinds fed two contrasting feeding regimes during their second winter, followed by a period at pasture.

scholarly journals NAD(P)H quinone oxidoreductase (NQO1): an enzyme which needs just enough mobility, in just the right places

2019 ◽  
Vol 39 (1) ◽  
Author(s):  
Angel L. Pey ◽  
Clare F. Megarity ◽  
David J. Timson
Keyword(s):  
Active Sites ◽  
Physiological Role ◽  
Polymorphic Form ◽  
Normal Function ◽  
Enzyme Mechanism ◽  
Quinone Oxidoreductase ◽  
Lower Stability ◽  
Increased Risk ◽  
Wide Range ◽  
The Right

AbstractNAD(P)H quinone oxidoreductase 1 (NQO1) catalyses the two electron reduction of quinones and a wide range of other organic compounds. Its physiological role is believed to be partly the reduction of free radical load in cells and the detoxification of xenobiotics. It also has non-enzymatic functions stabilising a number of cellular regulators including p53. Functionally, NQO1 is a homodimer with two active sites formed from residues from both polypeptide chains. Catalysis proceeds via a substituted enzyme mechanism involving a tightly bound FAD cofactor. Dicoumarol and some structurally related compounds act as competitive inhibitors of NQO1. There is some evidence for negative cooperativity in quinine oxidoreductases which is most likely to be mediated at least in part by alterations to the mobility of the protein. Human NQO1 is implicated in cancer. It is often over-expressed in cancer cells and as such is considered as a possible drug target. Interestingly, a common polymorphic form of human NQO1, p.P187S, is associated with an increased risk of several forms of cancer. This variant has much lower activity than the wild-type, primarily due to its substantially reduced affinity for FAD which results from lower stability. This lower stability results from inappropriate mobility of key parts of the protein. Thus, NQO1 relies on correct mobility for normal function, but inappropriate mobility results in dysfunction and may cause disease.

scholarly journals Annexin A4 Reduces Water and Proton Permeability of Model Membranes but Does Not Alter Aquaporin 2–mediated Water Transport in Isolated Endosomes

2003 ◽  
Vol 121 (5) ◽  
pp. 413-425 ◽  
Author(s):  
Warren G. Hill ◽  
Marcia A. Kaetzel ◽  
Bellamkonda K. Kishore ◽  
John R. Dedman ◽  
Mark L. Zeidel
Keyword(s):  
Membrane Permeability ◽  
Water Permeability ◽  
Membrane Trafficking ◽  
Collecting Duct ◽  
Water Flux ◽  
Physiological Role ◽  
Apical Region ◽  
Proton Permeability ◽  
Aquaporin 2 ◽  
Annexin A4

Annexin A4 (Anx4) belongs to a ubiquitous family of Ca2+-dependent membrane-binding proteins thought to be involved in membrane trafficking and membrane organization within cells. Anx4 localizes to the apical region in epithelia; however, its physiological role is unclear. We show that Anx4 exhibited binding to liposomes (phosphatidylcholine:phosphatidylserine, 1:1) in the presence of Ca2+ and binding was reversible with EDTA. Anx4 binding resulted in liposome aggregation and a reduction in membrane water permeability of 29% (P < 0.001) at 25°C. These effects were not seen in the presence of Ca2+ or Anx4 alone and were reversible with EDTA. Measurements of membrane fluidity made by monitoring fluorescence anisotropy of 2-(12-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dodecanoyl-1-hexadecanoyl-sn-glycero-3-phosphocholine (NBD-HPC) demonstrated that Anx4 binding rigidified the outer leaflet of the bilayer (P < 0.001), thus providing a molecular explanation for the inhibition of water flux. To determine whether Anx4 would produce similar effects on physiological membranes we constructed liposomes which recapitulated the lipid composition of the inner leaflet of the MDCK apical membrane. These membranes exhibited reductions to water permeability upon Anx4 binding (19.5% at 25°C, 31% at 37°C; P < 0.01 and P < 0.001, respectively) and to proton permeability (15% at 25°C, 19.5% at 37°C; P < 0.05). Since our in vitro experiments indicated an effect on membrane permeability, we examined localization of Anx4 in the kidney collecting duct, a region of the nephron responsible for concentrating urine through water reabsorbtion. Anx4 was shown to colocalize apically with aquaporin 2 (AQP2) in collecting duct epithelia. To test for the existence of a functional interaction between Anx4 and AQP2 we isolated AQP2-containing endosomes and exposed them to Anx4/Ca2+. Water flux rates were unchanged, indicating Anx4 does not directly regulate AQP2. We conclude that Anx4 can alter the physical properties of membranes by associating with them and regulate passive membrane permeability to water and protons. These properties represent important new functions for Anx4.

scholarly journals Optimization of nitrogen and phosphorus removal from pig slaughterhouse and packing plant wastewater through electrocoagulation in a batch reactor

2018 ◽  
Vol 13 (5) ◽  
pp. 1
Author(s):  
Fábio Orssatto ◽  
Maria Hermínia Ferreira Tavares ◽  
Flávia Manente da Silva ◽  
Eduardo Eyng ◽  
Leandro Fleck
Keyword(s):  
Total Phosphorus ◽  
Retention Time ◽  
Batch Reactor ◽  
Maximum Efficiency ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Treatment Conditions ◽  
Surface Graph ◽  
Wide Range ◽  
Kjeldahl Nitrogen

This work evaluated the removal of total Kjeldahl nitrogen (TKN) and total phosphorus (P) through electrocoagulation and used aluminum electrodes to optimize the potential differential (pd) and hydraulic retention time (HRT) variables in a batch reactor. The experimental design used was Rotatable Central Composite Design (RCCD). The application of the electrocoagulation in the treatment of effluents from pig slaughterhouses and packing plants proved to be efficient in relation to the removal of TKN and total phosphorus, obtaining maximum efficiency equal to 67.15% and 99%, respectively. The maximum TKN removal value was found in Test 12, where treatment conditions were 30 minutes for HRT and 20 volts for pd, which corresponds to 0.86 A of electric current and a current density of 17.2 mA cm-2. For P, the only test that removed below 99% was the first. Through statistical analyses, it was only possible to obtain a mathematical model for TKN removal. While the response surface graph did not present a defined range of the best conditions for the independent variables, it was possible to observe the tendency for better removal, a wide range of pd and values over 30 minutes for retention time.

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