scholarly journals Predicting the unexpected in stomatal gas exchange: not just an open-and-shut case

2020 ◽  
Vol 48 (3) ◽  
pp. 881-889
Author(s):  
Martina Klejchová ◽  
Adrian Hills ◽  
Michael R. Blatt
Keyword(s):  
Carbon Assimilation ◽  
Vacuolar Membrane ◽  
Transport Processes ◽  
Emergent Properties ◽  
Stomatal Behaviour ◽  
Non Linear ◽  
Stomatal Guard Cells ◽  
Modelling Environment ◽  
Use Efficiency

Plant membrane transport, like transport across all eukaryotic membranes, is highly non-linear and leads to interactions with characteristics so complex that they defy intuitive understanding. The physiological behaviour of stomatal guard cells is a case in point in which, for example, mutations expected to influence stomatal closing have profound effects on stomatal opening and manipulating transport across the vacuolar membrane affects the plasma membrane. Quantitative mathematical modelling is an essential tool in these circumstances, both to integrate the knowledge of each transport process and to understand the consequences of their manipulation in vivo. Here, we outline the OnGuard modelling environment and its use as a guide to predicting the emergent properties arising from the interactions between non-linear transport processes. We summarise some of the recent insights arising from OnGuard, demonstrate its utility in interpreting stomatal behaviour, and suggest ways in which the OnGuard environment may facilitate ‘reverse-engineering’ of stomata to improve water use efficiency and carbon assimilation.

scholarly journals Tobacco Mosaic Virus Movement Protein Functions as a Structural Microtubule-Associated Protein

2006 ◽  
Vol 80 (17) ◽  
pp. 8329-8344 ◽  
Author(s):  
Jamie Ashby ◽  
Emmanuel Boutant ◽  
Mark Seemanpillai ◽  
Adrian Sambade ◽  
Christophe Ritzenthaler ◽  
...  
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Movement Protein ◽  
Cell Extract ◽  
Transport Processes ◽  
In Vitro Assays ◽  
Protein Functions ◽  
Intercellular Spread

ABSTRACT The cell-to-cell spread of Tobacco mosaic virus infection depends on virus-encoded movement protein (MP), which is believed to form a ribonucleoprotein complex with viral RNA (vRNA) and to participate in the intercellular spread of infectious particles through plasmodesmata. Previous studies in our laboratory have provided evidence that the vRNA movement process is correlated with the ability of the MP to interact with microtubules, although the exact role of this interaction during infection is not known. Here, we have used a variety of in vivo and in vitro assays to determine that the MP functions as a genuine microtubule-associated protein that binds microtubules directly and modulates microtubule stability. We demonstrate that, unlike MP in whole-cell extract, microtubule-associated MP is not ubiquitinated, which strongly argues against the hypothesis that microtubules target the MP for degradation. In addition, we found that MP interferes with kinesin motor activity in vitro, suggesting that microtubule-associated MP may interfere with kinesin-driven transport processes during infection.

scholarly journals A Mathematical Model for Thermosensitive Liposomal Delivery of Doxorubicin to Solid Tumour

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Wenbo Zhan ◽  
Xiao Yun Xu
Keyword(s):  
Drug Delivery ◽  
Side Effects ◽  
Solid Tumour ◽  
Transport Processes ◽  
Direct Infusion ◽  
Biochemical Processes ◽  
Normal Tissues ◽  
Thermosensitive Liposome ◽  
Anticancer Treatment

The effectiveness of anticancer treatments is often hampered by the serious side effects owing to toxicity of anticancer drugs and their undesirable uptake by healthy cells in vivo. Thermosensitive liposome-mediated drug delivery has been developed as part of research efforts aimed at improving therapeutic efficacy while reducing the associated side effect. Since multiple steps are involved in the transport of drug-loaded liposomes, drug release, and its uptake, mathematical models become an indispensible tool to analyse the transport processes and predict the outcome of anticancer treatment. In this study, a computational model is developed which incorporates the key physical and biochemical processes involved in drug delivery and cellular uptake. The model has been applied to idealized tumour geometry, and comparisons are made between continuous infusion of doxorubicin and thermosensitive liposome-mediated delivery. Results show that thermosensitive liposome-mediated delivery performs better in reducing drug concentration in normal tissues, which may help lower the risk of associated side effects. Compared with direct infusion over a 2-hour period, thermosensitive liposome delivery leads to a much higher peak intracellular concentration of doxorubicin, which may increase cell killing in tumour thereby enhancing the therapeutic effect of the drug.

Urate transport in the proximal tubule: in vivo and vesicle studies

1985 ◽  
Vol 249 (6) ◽  
pp. F789-F798 ◽  
Author(s):  
A. M. Kahn ◽  
E. J. Weinman
Keyword(s):  
Proximal Tubule ◽  
Brush Border ◽  
Anion Exchanger ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Transport Processes ◽  
Basolateral Membrane Vesicles ◽  
Urate Transport ◽  
Rat Proximal Tubule

The transport of urate in the mammalian nephron is largely confined to the proximal tubule. Depending on the species, net reabsorption or net secretion is observed. The rat, like the human and the mongrel dog, demonstrates net reabsorption of urate and has been the most extensively studied species. The unidirectional reabsorption and secretion of urate in the rat proximal tubule occur via a passive and presumably paracellular route and by a mediated transcellular route. The reabsorption of urate, and possibly its secretion, can occur against an electrochemical gradient. A variety of drugs and other compounds affect the reabsorption and secretion of urate. The effects of these agents depend on their site of application (luminal or blood), concentration, and occasionally their participation in transport processes that do not have affinity for urate. Recent studies with renal brush border and basolateral membrane vesicles from the rat and brush border vesicles from the dog have determined the mechanisms for urate transport across the luminal and antiluminal membranes of the proximal tubule cell. Brush border membrane vesicles contain an anion exchanger with affinity for urate, hydroxyl ion, bicarbonate, chloride, lactate, p-aminohippurate (PAH), and a variety of other organic anions. Basolateral membrane vesicles contain an anion exchanger with affinity for urate and chloride but not for PAH. Both membrane vesicle preparations also permit urate translocation by simple diffusion. A model for the transcellular reabsorption and secretion of urate in the rat proximal tubule is proposed. This model is based on the vesicle studies, and it can potentially explain the majority of urate transport data obtained with in vivo techniques.

scholarly journals In vivo non-linear optical (NLO) imaging in live rabbit eyes using the Heidelberg Two-Photon Laser Ophthalmoscope

2010 ◽  
Vol 91 (2) ◽  
pp. 308-314 ◽  
Author(s):  
Ming Hao ◽  
Kevin Flynn ◽  
Chyong Nien-Shy ◽  
Bryan E. Jester ◽  
Moritz Winkler ◽  
...  
Keyword(s):  
Two Photon ◽  
Non Linear ◽  
Linear Optical

scholarly journals Head-to-tail regulation is critical for the in vivo function of myosin V

2015 ◽  
Vol 209 (3) ◽  
pp. 359-365 ◽  
Author(s):  
Kirk W. Donovan ◽  
Anthony Bretscher
Keyword(s):  
Nuclear Orientation ◽  
Secretory Vesicle ◽  
Transport Processes ◽  
Myosin V ◽  
Normal Delivery ◽  
Temporal Regulation ◽  
Primary Means ◽  
Cell Organization ◽  
Cytoskeletal Elements

Cell organization requires regulated cargo transport along cytoskeletal elements. Myosin V motors are among the most conserved organelle motors and have been well characterized in both yeast and mammalian systems. Biochemical data for mammalian myosin V suggest that a head-to-tail autoinhibitory interaction is a primary means of regulation, but the in vivo significance of this interaction has not been studied. Here we generated and characterized mutations in the yeast myosin V Myo2p to reveal that it is regulated by a head-to-tail interaction and that loss of regulation renders the myosin V constitutively active. We show that an unregulated motor is very deleterious for growth, resulting in severe defects in Myo2-mediated transport processes, including secretory vesicle transport, mitochondrial inheritance, and nuclear orientation. All of the defects associated with motor misregulation could be rescued by artificially restoring regulation. Thus, spatial and temporal regulation of myosin V in vivo by a head-to-tail interaction is critical for the normal delivery functions of the motor.

scholarly journals The direct and indirect effects of nitrogen shortage on photosynthesis and transpiration in maize and sunflower.

1979 ◽  
Vol 27 (3) ◽  
pp. 227-234
Author(s):  
J. Goudriaan ◽  
H. van Keulen
Keyword(s):  
Indirect Effects ◽  
Leaf Tissue ◽  
Co2 Assimilation ◽  
Direct And Indirect Effects ◽  
Stomatal Behaviour ◽  
Net Co2 Assimilation ◽  
Similar Relation ◽  
Use Efficiency ◽  
Different Levels ◽  
N Status

Experiments with maize and sunflower in sol. culture were carried out to investigate the effect of N shortage in the leaf tissue on stomatal behaviour. In maize a linear relation existed between the rate of net CO2 assimilation and the conductance of water vapour, independently of the N status of the tissue. In sunflower a similar relation existed although the evidence was less conclusive. It was concluded that stomatal behaviour cannot explain differences in water-use efficiency between plants growing at different levels of N. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Genetic variation in haemoglobin alters breathing in high-altitude deer mice

2021 ◽  
Author(s):  
Catherine M. Ivy ◽  
Oliver H. Wearing ◽  
Chandrasekhar Natarajan ◽  
Rena M. Schweizer ◽  
Natalia Gutiérrez-Pinto ◽  
...  
Keyword(s):  
Genetic Variation ◽  
High Altitude ◽  
Globin Gene ◽  
Respiratory Physiology ◽  
Deer Mice ◽  
Emergent Properties ◽  
Mixed Genetic Background ◽  
Hypoxia Adaptation ◽  
Globin Gene Expression

ABSTRACTPhysiological systems often have emergent properties but the effects of genetic variation on physiology are often unknown, which presents a major challenge to understanding the mechanisms of phenotypic evolution. We investigated the in vivo effects on respiratory physiology of genetic variants in haemoglobin (Hb) that contribute to hypoxia adaptation in high-altitude deer mice (Peromyscus maniculatus). We created F2 inter-population hybrids of highland and lowland deer mice to test the phenotypic effects of α- and β-globin variants on a mixed genetic background. High-altitude genotypes were associated with breathing phenotypes that enhance O2 uptake in hypoxia, including a deeper more effective breathing pattern and an augmented hypoxic ventilatory response. These effects could not be explained by erythrocyte Hb-O2 affinity or globin gene expression in the brainstem. Therefore, adaptive variation in haemoglobin can have unexpected effects on physiology that are distinct from the canonical function of this protein in circulatory O2 transport.

scholarly journals Artificial Mitochondria Transfer: Current Challenges, Advances, and Future Applications

2017 ◽  
Vol 2017 ◽  
pp. 1-23 ◽  
Author(s):  
Andrés Caicedo ◽  
Pedro M. Aponte ◽  
Francisco Cabrera ◽  
Carmen Hidalgo ◽  
Maroun Khoury
Keyword(s):  
Power Plants ◽  
Ethical Issues ◽  
Transport Processes ◽  
Optimum Quantity ◽  
Cell Tissue ◽  
Mitochondrial Transfer ◽  
Mitochondria Transfer ◽  
Key Questions

The objective of this review is to outline existing artificial mitochondria transfer techniques and to describe the future steps necessary to develop new therapeutic applications in medicine. Inspired by the symbiotic origin of mitochondria and by the cell’s capacity to transfer these organelles to damaged neighbors, many researchers have developed procedures to artificially transfer mitochondria from one cell to another. The techniques currently in use today range from simple coincubations of isolated mitochondria and recipient cells to the use of physical approaches to induce integration. These methods mimic natural mitochondria transfer. In order to use mitochondrial transfer in medicine, we must answer key questions about how to replicate aspects of natural transport processes to improve current artificial transfer methods. Another priority is to determine the optimum quantity and cell/tissue source of the mitochondria in order to induce cell reprogramming or tissue repair, in both in vitro and in vivo applications. Additionally, it is important that the field explores how artificial mitochondria transfer techniques can be used to treat different diseases and how to navigate the ethical issues in such procedures. Without a doubt, mitochondria are more than mere cell power plants, as we continue to discover their potential to be used in medicine.

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