Overexpression of the Zygophyllum xanthoxylum Aquaporin, ZxPIP1;3, Promotes Plant Growth and Stress Tolerance

Drought and salinity can result in cell dehydration and water unbalance in plants, which seriously diminish plant growth and development. Cellular water homeostasis maintained by aquaporin is one of the important strategies for plants to cope with these two stresses. In this study, a stress-induced aquaporin, ZxPIP1;3, belonging to the PIP1 subgroup, was identified from the succulent xerophyte Zygophyllum xanthoxylum. The subcellular localization showed that ZxPIP1;3-GFP was located in the plasma membrane. The overexpression of ZxPIP1;3 in Arabidopsis prompted plant growth under favorable condition. In addition, it also conferred salt and drought tolerance with better water status as well as less ion toxicity and membrane injury, which led to more efficient photosynthesis and improved growth vigor via inducing stress-related responsive genes. This study reveals the molecular mechanisms of xerophytes’ stress tolerance and provides a valuable candidate that could be used in genetic engineering to improve crop growth and stress tolerance.

User guide to the red blood cell model (RCM), a multiplatform JAVA-based model of human red blood cell homeostasis

We introduce here a new multiplatform JAVA-based mathematical-computational model of RBC homeostasis for investigating the dynamics of changes in RBC homeostasis in health and disease. We provide a brief overview on the homeostasis of human RBCs and on the general biophysical principles guiding the modelling design. By way of a detailed tutorial we apply the model to investigate in depth the multiple effects associated with RBC dehydration induced by potassium permeabilization, a necessary preliminary for understanding the pathophysiology of a wide group of inherited haemolytic anaemias, a subject of intense current research and clinical interest. Using the red cell model (RCM), we design and run in silico representations of experimental protocols to study global RBC responses to calcium and potassium permeabilization covering a wide range of experimental, physiological and pathological conditions. Model outputs report the evolution in time of all the homeostatic variables in the system allowing, for the first time, a detailed and comprehensive account of the complex processes shaping global cell responses. Analysis of the results explains the mechanisms by which the entangled operation of all the RBC components link cell dehydration and protein crowding to cell acidification and to the generation of hypertonic, alkaline effluents. Open access to the RCM in a GitHub repository, together with the tutorial primed for a specific investigation pave the way for researchers and clinicians to apply the model on many different aspects of RBC physiology and pathology.

Total Serum Magnesium Levels and Calcium-To-Magnesium Ratio in Sickle Cell Disease

Background and objectives: Imbalance of calcium/magnesium ratio could lead to clinical complications in sickle cell disease (SCD). Low levels of magnesium have been associated with sickling, increased polymerization and vaso-occlusion (VOC) in sickle cell due to cell dehydration. The K-Cl cotransport plays a very important role in sickle cell dehydration and is inhibited by significantly increasing levels of magnesium. The study evaluated total serum magnesium levels and computed calcium/magnesium ratio in SCD patients and “healthy” controls. Materials and methods: The study was a case-control cross-sectional one, involving 120 SCD patients (79 Haemoglobin SS (HbSS)and 41 Haemoglobin SC (HbSC)) at the steady state and 48 “healthy” controls. Sera were prepared from whole blood samples (n = 168) and total magnesium and calcium measured using a Flame Atomic Absorption Spectrometer (Variant 240FS manufactured by VARIAN Australia Pty Ltd., Melbourne, VIC, Australia). Calcium/magnesium ratios were calculated in patients and the controls. Results: The prevalence of hypomagnesemia and hypocalcaemia among the SCD patients was observed to be 39.17% and 52.50% respectively, higher than the controls (4.17% and 22.92%, for hypomagnesemia and hypocalcaemia, respectively). Level of magnesium was significantly lower in the SCD patients compared to their healthy counterparts (p = 0.002). The magnesium level was further reduced in the HbSS patients but not significantly different from the HbSC patients (p = 0.584). calcium/magnesium ratio was significantly higher in the SCD patients (p = 0.031). Although calcium/magnesium ratio was higher in the HbSC patients compared to those with the HbSS genotype, the difference was not significant (p = 0.101). Conclusion: The study shows that magnesium homeostasis are altered in SCD patients, and their levels are lower in HbSS patients. Although calcium/magnesium ratio is significantly higher in SCD patients compared with controls, there is no significant difference between patients with HbSS and HbSC genotypes. Magnesium supplementation may be required in sickle cell patients.

The Role of Water Homeostasis in Muscle Function and Frailty: A Review

Water, the main component of the body, is distributed in the extracellular and intracellular compartments. Water exchange between these compartments is mainly governed by osmotic pressure. Extracellular water osmolarity must remain within very narrow limits to be compatible with life. Older adults lose the thirst sensation and the ability to concentrate urine, and this favours increased extracellular osmolarity (hyperosmotic stress). This situation, in turn, leads to cell dehydration, which has severe consequences for the intracellular protein structure and function and, ultimately, results in cell damage. Moreover, the fact that water determines cell volume may act as a metabolic signal, with cell swelling acting as an anabolic signal and cell shrinkage acting as a catabolic signal. Ageing also leads to a progressive loss in muscle mass and strength. Muscle strength is the main determinant of functional capacity, and, in elderly people, depends more on muscle quality than on muscle quantity (or muscle mass). Intracellular water content in lean mass has been related to muscle strength, functional capacity, and frailty risk, and has been proposed as an indicator of muscle quality and cell hydration. This review aims to assess the role of hyperosmotic stress and cell dehydration on muscle function and frailty.

Erythrocyte ion content and dehydration modulate maximal Gardos channel activity in KCNN4 V282M/+ hereditary xerocytosis red cells

Hereditary xerocytosis (HX) is caused by missense mutations in either the mechanosensitive cation channel PIEZO1 or the Ca2+-activated K+channel KCNN4. All HX-associated KCNN4 mutants studied to date have revealed increased current magnitude and red cell dehydration. Baseline KCNN4 activity was increased in HX red cells heterozygous for KCNN4 mutant V282M. However, HX red cells maximally stimulated by Ca2+ionophore A23187 or by PMCA Ca2+-ATPase inhibitor orthovanadate displayed paradoxically reduced KCNN4 activity. This reduced Ca2+-stimulated mutant KCNN4 activity in HX red cells was associated with unchanged sensitivity to KCNN4 inhibitor senicapoc and KCNN4 activator Ca2+, with slightly elevated Ca2+uptake and reduced PMCA activity, and with decreased KCNN4 activation by calpain inhibitor PD150606. The altered intracellular monovalent cation content of HX red cells prompted experimental nystatin manipulation of red cell Na and K contents. Nystatin-mediated reduction of intracellular K+with corresponding increase in intracellular Na+in wild-type cells to mimic conditions of HX greatly suppressed vanadate-stimulated and A23187 -stimulated KCNN4 activity in those wild-type cells. However, conferral of wild-type cation contents on HX red cells failed to restore wild-type-stimulated KCNN4 activity to those HX cells. The phenotype of reduced, maximally stimulated KCNN4 activity was shared by HX erythrocytes expressing heterozygous PIEZO1 mutants R2488Q and V598M, but not by HX erythrocytes expressing heterozygous KCNN4 mutant R352H or PIEZO1 mutant R2456H. Our data suggest that chronic KCNN4-driven red cell dehydration and intracellular cation imbalance can lead to reduced KCNN4 activity in HX and wild-type red cells.

Markers of melanoma progression in the blood serum structure.

e21035 Background: Lack of prognostic markers of melanoma to assess its progression, metastasis (MTS), and treatment effectiveness, determines the feasibility of studying biophysical aspects of the transmission of events from cellular to extracellular environment. Receipt and circulation of pathological proteins of melanoma (M) in the blood carries important information, and its trap is the phase transition of biofluids into a solid state. The purpose of the study was to determine markers of melanoma at the supramolecular level in solid-state samples of the blood serum (BS). Methods: 240 samples of BS obtained prior to the surgery from 60 patients with M were studied. The preparations were prepared by the Shatokhina-Shabalin method by creating a closed "analytic cell": dehydration of a BS drop (10 mcL) under a cover glass at 20–240С, humidity 65–70%, for 72 hours. The folding of M proteins was assessed by a polarized light microscopy (Leica DM LS2 microscope, x400-640) using photo and video control and the Morphotest program. Results: The initial stages of M development were characterized by the early appearance of single combined melanoform crystals — anisotropic microspherolites (Mi) embedded in the center of a large anisomorphone (lAM). As M progressed, Mi aggregation with basic lAMs was enhanced. Anisotropy of Mi increased, revealing clear sectors filled with melanin. In the later stages of M growth, melanoform aggregations dominated with point, filamentous, and chained melanin structures. The manifestation of MTS was accompanied by the destruction of the aggregations and the filling of the analytic cell space with numerous Mi. Conclusions: Correspondence of crystallogenesis of M melanomorphic markers in BS in tumor progression allows using the studied supramolecular factors to predict the development of melanoma.

NEW THERAPEUTIC OPTIONS FOR THE TREATMENT OF SICKLE CELL DISEASE

Sickle cell disease (SCD; ORPHA232; OMIM # 603903) is a chronic and invalidating disorder distributed worldwide, with high morbidity and mortality. Given the disease complexity and the multiplicity of pathophysiological targets, development of new therapeutic options is critical, despite the positive effects of hydroxyurea (HU), for many years the only approved drug for SCD. New therapeutic strategies might be divided into (1) pathophysiology-related novel therapies and (2) innovations in curative therapeutic options such as hematopoietic stem cell transplantation and gene therapy. The pathophysiology related novel therapies are: a) Agents which reduce sickling or prevent sickle red cell dehydration; b) Agents targeting SCD vasculopathy and sickle cell-endothelial adhesive events; c) Anti-oxidant agents. This review highlights new therapeutic strategies in SCD and discusses future developments, research implications, and possible innovative clinical trials.