Regulation Of Gas Exchange Research Articles

Review of respiratory anatomy adaptations in whales.

Whales (cetaceans, including dolphins and porpoises) are superbly adapted to life in water, but retain vestiges of their terrestrial ancestry, particularly the need to breathe air. Their respiratory tract exhibits many differences from their closest relatives, the terrestrial artiodactyls (even toed ungulates). In this review, we describe the anatomy of cetacean respiratory adaptions. These include protective features (e.g., preventing water incursions during breathing or swallowing, mitigating effects of pressure changes during diving/ascent) and unique functions (e.g., underwater sound production, regulating gas exchange during the dive cycle).

How Cropping System Influences Robusta Coffee Leaf Gas Exchange Efficiency via Stomatal Regulation

Background: Robusta coffee leaves regulate gas exchange in response to climatic factors like full sun and shaded conditions. To fully understand the reasons behind the variations in photosynthetic rates and water-use efficiency, exploring the underlying mechanisms of stomatal regulation in the maximum photosynthetic efficiency of Robusta coffee trees, especially in a shade condition is necessary. Methods: This study aimed to evaluate how stomatal regulation in Robusta coffee leaves affects gas exchange under different cropping systems. The Robusta coffee trees were grown in four different cropping systems: monoculture (full-sun condition) (S1), intercropped (single row) with rubber trees (S2), intercropped (double spacing) with rubber trees (S3), and intercropped in a mixed orchard (S4). Result: The results revealed that Robusta coffee trees grown between rubber tree rows with closer spacing (S2) exhibited the largest stomata sizes. These stomata sizes had a statistically significant increase in width, length, and area (ranging from 12.04 to 14.74 µm, 19.22 to 25.55 µm, and 202.37 to 296.05 µm², respectively) compared to Robusta coffee grown in S1, S3, and S4 systems. On the other hand, Robusta coffee grown in S1 system displayed the highest stomatal density, ranging from 310 to 540 stomata/mm². Interestingly, coffee trees grown between rubber rows (S3) and in the mixed orchard (S4) exhibited both high rates of photosynthesis (9.18 and 9.35 µmol/m²/s) and photosynthetic water-use efficiency (3.78 and 5.15 mmol/mol). Notably, these values were statistically different from those observed in other planting conditions. Additionally, Robusta coffee grown in S1 system exhibited the highest canopy temperature (ranging from 30.8 to 47.4°C). It also had the lowest Fv/Fm value (ranging from 0.706 to 0.759) compared to other planting conditions. This study indicates that Robusta coffee leaves exhibited varying stomatal responses to changes in light and temperature depending on the cropping system. By understanding how these leaf traits influence adaptation, we could potentially optimize Robusta coffee trees to thrive in full sun and shaded conditions, particularly within intercropping systems.

ОПРЕДЕЛЕНИЕ ИНТЕНСИВНОСТИ ВЕНТИЛЯЦИИ ИНКУБАТОРА ПО ДИНАМИКЕ РАСХОДА ВОДЫ В УВЛАЖНИТЕЛЕ

It is known that the air composition in the incubator chamber is critically important for the development of bird embryos, since the embryo consumes oxygen and produces carbon dioxide during development. High embryonic mortality is observed with insufficient ventilation of the incubator chamber, however, excessive ventilation leads to unreasonable costs of electricity and water in the humidification system. Gas analyzers that allow precise regulation of gas exchange between the incubator chamber and the surrounding air are not used in tabletop incubators, and the problem of determining the optimal ventilation parameters for tabletop incubators remains relevant at present. The possibility of interpreting data on water consumption by humidification systems of tabletop incubators in order to determine the characteristics of oxygen and carbon dioxide gas exchange between the air in the incubator chamber and the environment was studied. Grumbach tabletop incubators, a carbon dioxide detector based on the ZGm053UK IR sensor, and an AT-8100 electrochemical oxygen detector were used. It was established that the dynamics of water consumption of the incubator humidification system correlates with the volume of gas exchange between the incubator and the environment. The danger of stopping the respiratory activity of embryos occurs in sealed incubators, while the marker of the absence of gas exchange is a constant water level in the humidification system. With the rate of water evaporation by the evaporator of at least 3 cm3 / day per 1 chicken egg, the difference in relative humidity in the incubator room and the incubator chamber of at least 10% and the difference in temperatures in the incubator and the incubator room of at least 10 ° C, the gas exchange of the incubator with the room provides a carbon dioxide level of no more than 3000 ppm, and an oxygen level of at least 20.6%. The air composition in the incubator room has a direct effect on the air composition in the incubator, however, the required ventilation level of the incubator room, providing satisfactory air quality, can be determined organoleptically.

Temperature effects on blood gases in embryonic American alligators (Alligator mississippiensis)

Numerous studies report on the influence of temperature on blood gases in ectothermic vertebrates, but there is merely a cursory understanding of these effects in developing animals. Animals that develop in eggs are at the mercy of environmental temperature and are expected to lack the capacity to regulate gas exchange and may regulate blood gases by means of altered conductance for gas exchange. We, therefore, devised a series of studies to characterize the developmental changes in blood gases when embryonic alligators were exposed to 25, 30 and 35 °C. To determine how blood parameters were impacted by changes in embryonic temperature, blood was sampled from the chorioallantoic membrane artery. The blood in the chorioallantoic membrane artery is a mixture of oxygen-poor and oxygen-rich blood, which based on the embryonic vascular anatomy may reflect blood that perfuses the chemoreceptors of the developing animal. Our findings indicate that following a 48 h exposure to 25 °C or 35 °C, there was a positive relationship between CAM artery blood PO2, PCO2 and glucose. However, blood pH suggests embryonic alligators lack an acute regulatory mechanism for adjusting blood pH.

Decoding stomatal characteristics regulating water use efficiency at leaf and plant scales in rice genotypes.

Stomatal traits in rice genotypes affect water use efficiency. Low-frequency small-size stomata correlate with whole plant efficiency, while low-frequency large-size stomata show intrinsic efficiency and responsiveness to vapour pressure deficit. Leaf surface and the patterning of the epidermal layer play a vital role in determining plant growth. While the surface helps in determining radiation interception, epidermal pattern of stomatal factors strongly regulate gas exchange and water use efficiency (WUE). This study focuses on identifying distinct stomatal traits among rice genotypes to comprehend their influence on WUE. Stomatal frequency ranged from 353 to 687 per mm2 and the size varied between 128.31 and 339.01 μm2 among 150 rice germplasm with significant variability in abaxial and adaxial surfaces. The cumulative water transpired and WUE determined at the outdoor phenomics platform, over the entire crop growth period as well as during specific hours of a 24h-day did not correlate with stomatal frequency nor size. However, genotypes with low-frequency and large-size stomata recorded higher intrinsic water use efficiency (67.04μmol CO2 mol-1 H2O) and showed a quicker response to varying vapour pressure deficit that diurnally ranged between 0.03 and 2.17kPa. The study demonstrated the role of stomatal factors in determining physiological subcomponents of WUE both at single leaf and whole plant levels. Differential expression patterns of stomatal regulatory genes among the contrasting groups explained variations in the epidermal patterning. Increased expression of ERECTA, TMM and YODA genes appear to contribute to decreased stomatal frequency in low stomatal frequency genotypes. These findings underscore the significance of stomatal traits in breeding programs and strongly support the importance of these genes that govern variability in stomatal architecture in future crop improvement programs.

Exogenous melatonin strengthens saline-alkali stress tolerance in apple rootstock M9-T337 seedlings by initiating a variety of physiological and biochemical pathways

Melatonin (MT) is an important plant growth regulator that significantly regulates the growth and development of plants. Previous studies confirmed the effectiveness of MT in improving plant stress tolerance. In this study, annual M9-T337 seedlings were selected as subjects, and five treatments were applied: control (CK), in which only half the concentration of Hoagland was applied; Saline-alkaline stress treatment (SA, 100 mmol·L−1 saline-alkaline solution); melatonin treatment (MT, CK + 200 μmol L−1 exogenous MT); Saline-alkaline + melatonin treatment (MS, SA + 200 μmol L−1 exogenous MT); and saline-alkaline stress + melatonin + inhibitor treatment (HS, additional 100 μmol L−1 p-CPA treatment to MS). The results showed that saline-alkaline stress negatively affected the growth of M9-T337 seedlings by reducing photosynthetic capacity, increasing Na+, promoting reactive oxygen species such as H2O2, and changing the osmotic content and antioxidant system. However, the application of exogenous MT effectively alleviated saline-alkaline damage and significantly promoted the growth of M9-T337 seedlings. It significantly increased plant height, diameter, root length, root surface area, volume and activity. Furthermore, MT alleviated osmotic stress by accumulating proline, soluble sugars, soluble proteins and starch. MT improved photosynthetic capacity by delaying chlorophyll degradation and regulating gas exchange parameters as well as fluorescence parameters in leaves. Additionally, MT reduced the Na+/K+ ratio to reduce ion toxicity by upregulating the expression of Na+ transporter genes (MhCAX5, MhCHX15, MhSOS1, and MhALT1) and downregulating the expression of K+ transporter genes (MhSKOR and MhNHX4). In addition, MT can increase antioxidant enzyme activity (superoxide dismutase (SOD), peroxidase(POD), catalase (CAT), ascorbic acid oxidase (AAO), ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDHAR)) in the ASA-GSH cycle and increase ascorbic acid (AsA), reduced glutathione (GSH) and oxidized glutathione (GSSG) levels to counteract the accumulation of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) and Superoxide anion free radicals (O2−), reducing oxidative damage. Exogenous MT promotes M9-T337 seedlings growth under saline-alkaline stress by responding synergistically with auxin (IAA), gibberellin (GA3) and zeatin (ZT) to saline-alkaline stress. Our results confirm that MT has the potential to alleviate Saline-alkaline stress by promoting root growth, increasing biomass accumulation and photosynthetic capacity, strengthening the antioxidant defense system, maintaining ionic balance, the ascorbate–glutathione cycle and the Osmoregulation facilitates and regulates endogenous hormone levels in M9-T337 seedlings.Graphical

Unravelling the neglected role of ultravioletradiation on stomata: A meta-analysis with implications for modelling ecosystem-climate interactions.

Stomata play a pivotal role in regulating gas exchange between plants and the atmosphere controlling water and carbon cycles. Accordingly, we investigated the impact of ultraviolet-B radiation, a neglected environmental factor varying with ongoing global change, on stomatal morphology and function by a Comprehensive Meta-Analysis. The overall UVeffect at the leaf level is to decrease stomatal conductance, stomatal aperture and stomatal size, although stomatal density was increased. The significant decline in stomatal conductance is marked (6% in trees and >10% in grasses and herbs) in short-term experiments, with more modest decreases noted in long-term UV studies. Short-term experiments in growth chambers are not representative of long-term field UV effects on stomatal conductance. Important consequences of altered stomatal function are hypothesized. In the short term, UV-mediated stomatal closure may reduce carbon uptake but also water loss through transpiration, thereby alleviating deleterious effects of drought. However, in the long term, complex changes in stomatal aperture, size, and density may reduce the carbon sequestration capacity of plants and increase vegetation and land surface temperatures, potentially exacerbating negative effects of drought and/or heatwaves. Therefore, the expected future strength of carbon sink capacity in high-UV regions is likely overestimated.

Analysis of Guard Cell Readouts Using Arabidopsis thaliana Isolated Epidermal Peels.

Stomata are pores surrounded by a pair of specialized cells, called guard cells, that play a central role in plant physiology through the regulation of gas exchange between plants and the environment. Guard cells have features like cell-autonomous responses and easily measurable readouts that have turned them into a model system to study signal transduction mechanisms in plants. Here, we provide a detailed protocol to analyze different physiological responses specifically in guard cells. We describe, in detail, the steps and conditions to isolate epidermal peels with tweezers and to analyze i) stomatal aperture in response to different stimuli, ii) cytosolic parameters such as hydrogen peroxide (H2O2), glutathione redox potential (E GSH), and MgATP-2 in vivo dynamics using fluorescent biosensors, and iii) gene expression in guard cell-enriched samples. The importance of this protocol lies in the fact that most living cells on epidermal peels are guard cells, enabling the preparation of guard cell-enriched samples. Key features • Isolation of epidermal peels as a monolayer enriched in guard cells • Measurement of cytosolic guard cell signaling component dynamics in isolated epidermal peels through fluorescent biosensor analysis • Gene expression analysis of guard cell-enriched isolated tissue.

Distinct guard cell-specific remodeling of chromatin accessibility during abscisic acid- and CO2-dependent stomatal regulation.

In plants, epidermal guard cells integrate and respond to numerous environmental signals to control stomatal pore apertures, thereby regulating gas exchange. Chromatin structure controls transcription factor (TF) access to the genome, but whether large-scale chromatin remodeling occurs in guard cells during stomatal movements, and in response to the hormone abscisic acid (ABA) in general, remains unknown. Here, we isolate guard cell nuclei from Arabidopsis thaliana plants to examine whether the physiological signals, ABA and CO2 (carbon dioxide), regulate guard cell chromatin during stomatal movements. Our cell type-specific analyses uncover patterns of chromatin accessibility specific to guard cells and define cis-regulatory sequences supporting guard cell-specific gene expression. We find that ABA triggers extensive and dynamic chromatin remodeling in guard cells, roots, and mesophyll cells with clear patterns of cell type specificity. DNA motif analyses uncover binding sites for distinct TFs enriched in ABA-induced and ABA-repressed chromatin. We identify the Abscisic Acid Response Element (ABRE) Binding Factor (ABF) bZIP-type TFs that are required for ABA-triggered chromatin opening in guard cells and roots and implicate the inhibition of a clade of bHLH-type TFs in controlling ABA-repressed chromatin. Moreover, we demonstrate that ABA and CO2 induce distinct programs of chromatin remodeling, whereby elevated atmospheric CO2 had only minimal impact on chromatin dynamics. We provide insight into the control of guard cell chromatin dynamics and propose that ABA-induced chromatin remodeling primes the genome for abiotic stress resistance.

Modulation of sunflower growth via regulation of antioxidants, oil content and gas exchange by arbuscular mycorrhizal fungi and quantum dot biochar under chromium stress

Chromium (Cr) toxicity significantly threatens sunflower growth and productivity by interfering with enzymatic activity and generating reactive oxygen species (ROS). Zinc quantum dot biochar (ZQDB) and arbuscular mycorrhizal fungi (AMF) have become popular to resolve this issue. AMF can facilitate root growth, while biochar tends to minimize Cr mobility in soil. The current study aimed to explore AMF and ZQDB combined effects on sunflower plants in response to Cr toxicity. Four treatments were applied, i.e. NoAMF + NoZQDB, AMF + 0.40%ZQDB, AMF + 0.80%ZQDB, and AMF + 1.20%ZQDB, under different stress levels of Cr, i.e. no Cr (control), 150 and 200 mg Cr/kg soil. Results showed that AMF + 1.20%ZQDB was the treatment that caused the greatest improvement in plant height, stem diameter, head diameter, number of leaves per plant, achenes per head, 1000 achenes weight, achene yield, biological yield, transpiration rate, stomatal conductance, chlorophyll content and oleic acid, relative to the condition NoAMF + No ZQDB at 200 mg Cr/kg soil. A significant decline in peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) while improvement in ascorbate peroxidase (APx), oil content, and protein content further supported the effectiveness of AMF + 1.20%ZQDB against Cr toxicity. Our results suggest that the treatment AMF + 1.20%ZQDB can efficiently alleviate Cr stress in sunflowers.

Endothelial cell clonality, heterogeneity and dysfunction in pulmonary arterial hypertension.

Our understanding of the pathophysiology of pulmonary arterial hypertension (PAH) has evolved over recent years, with the recognition that endothelial cell (EC) dysfunction and inflammation play an integral role in the development of this disease. ECs within the pulmonary vasculature play a unique role in maintaining vascular integrity and barrier function, regulating gas exchange, and contributing to vascular tone. Using single-cell transcriptomics, research has shown that there are multiple, unique EC subpopulations with different phenotypes. In response to injury or certain stressors such as hypoxia, there can be a dysregulated response with aberrant endothelial injury repair involving other pulmonary vascular cells and even immune cells. This aberrant signaling cascade is potentially a primary driver of pulmonary arterial remodeling in PAH. Recent studies have examined the role of EC clonal expansion, immune dysregulation, and genetic mutations in the pathogenesis of PAH. This review summarizes the existing literature on EC subpopulations and the intricate mechanisms through which ECs develop aberrant physiologic phenotypes and contribute to PAH. Our goal is to provide a framework for understanding the unique pulmonary EC biology and pathophysiology that is involved in the development of PAH.

Small Papillae Regulated by SPD25 are Critical for Balancing Photosynthetic CO2 Assimilation and Water Loss in Rice

BackgroundThe leaf epidermis plays an important role in the transmission of light and the regulation of water and gas exchange, which influences the photosynthesis of mesophyll cells. Small papillae (SP) are one of the important structural elements of the leaf epidermis. The mechanism of the effect that small papillae have on rice leaf photosynthetic performance remains unclear.ResultsIn this study, a small papilla deficient 25 (spd25) mutant was isolated from japonica rice Longjin1. Small papillae were absent on the adaxial and abaxial leaf surfaces of the spd25 mutant and the silicon and cuticular wax content in the spd25 mutant leaves decreased. Map-based cloning and functional analysis revealed that SPD25, encoding a guanine nucleotide exchange factor for Rop, is a novel allele of OsRopGEF10. The spd25 mutant showed an increased water loss rate and reduced relative water content. The lower stomatal conductance in the spd25 mutant prevented water loss but decreased the intercellular CO2 concentration and net assimilation rate. The fluorescence parameters showed that the inhibited CO2 assimilation reaction feedback regulated the photochemical electron-transfer reaction, but the performance of Photosystem II was stable. Further analysis indicated that the excess light energy absorbed by the spd25 mutant was dissipated in the form of non-photochemical quenching to avoid photodamage through the optical properties of small papillae.ConclusionsSPD25 regulates the development of small papillae on the surface of rice leaves, which play an important role in balancing photosynthetic gas exchange and water loss. This study deepens our understanding of the physiological mechanisms by which small papillae affect photosynthetic performance.

Synthesis and import of GDP-l-fucose into the Golgi affect plant-water relations.

Land plants evolved multiple adaptations to restrict transpiration. However, the underlying molecular mechanisms are not sufficiently understood. We used an ozone-sensitivity forward genetics approach to identify Arabidopsis thaliana mutants impaired in gas exchange regulation. High water loss from detached leaves and impaired decrease of leaf conductance in response to multiple stomata-closing stimuli were identified in a mutant of MURUS1 (MUR1), an enzyme required for GDP-l-fucose biosynthesis. High water loss observed in mur1 was independent from stomatal movements and instead could be linked to metabolic defects. Plants defective in import of GDP-l-Fuc into the Golgi apparatus phenocopied the high water loss of mur1 mutants, linking this phenotype to Golgi-localized fucosylation events. However, impaired fucosylation of xyloglucan, N-linked glycans, and arabinogalactan proteins did not explain the aberrant water loss of mur1 mutants. Partial reversion of mur1 water loss phenotype by borate supplementation and high water loss observed in boron uptake mutants link mur1 gas exchange phenotypes to pleiotropic consequences of l-fucose and boron deficiency, which in turn affect mechanical and morphological properties of stomatal complexes and whole-plant physiology. Our work emphasizes the impact of fucose metabolism and boron uptake on plant-water relations.

Admixture mapping and selection scans identify genomic regions associated with stomatal patterning and disease resistance in hybrid poplars.

Variation in fitness components can be linked in some cases to variation in key traits. Metric traits that lie at the intersection of development, defense, and ecological interactions may be expected to experience environmental selection, informing our understanding of evolutionary and ecological processes. Here, we use quantitative genetic and population genomic methods to investigate disease dynamics in hybrid and non-hybrid populations. We focus our investigation on morphological and ecophysiological traits which inform our understanding of physiology, growth, and defense against a pathogen. In particular, we investigate stomata, microscopic pores on the surface of a leaf that regulate gas exchange during photosynthesis and are sites of entry for various plant pathogens. Stomatal patterning traits were highly predictive of disease risk. Admixture mapping identified a polygenic basis of disease resistance. Candidate genes for stomatal and disease resistance map to the same genomic regions and experienced positive selection. Genes with functions to guard cell homeostasis, the plant immune system, components of constitutive defenses, and growth-related transcription factors were identified. Our results indicate positive selection acted on candidate genes for stomatal patterning and disease resistance, potentially acting in concert to structure their variation in naturally formed backcrossing hybrid populations.

Reduced Invasiveness of Cardiopulmonary Bypass: The Mini-Circuit and the Micro-Cardioplegia.

The aim of cardiopulmonary bypass is the maintenance of a sufficient whole body perfusion and gas exchange during open or closed heart surgery procedure (coronary artery bypass grafting, valve repair and replacement, surgical intervention on the ascending aorta and/or aortic arch, repair of congenital malformations, and finally implantation of ventricular assist devices or cardiac transplantation). The main components of cardiopulmonary bypass are the pump that supplies the circulation and the oxygenator that regulates gas exchange. However, even though this technology has been extensively developed and improved over the last decades, one of the major drawbacks-which is the fact that blood has to flow through tubing systems with foreign surfaces-persists so far. Nevertheless, interesting innovations have been made more recently in order to better control the side-effects that culminate into a major activation of the coagulation and inflammatory systems: among them, miniaturization of the circuits, together with reduction of the priming volume and a simplified cardioplegia concept. All of these lead to a significant decrease of hemodilution and thereby a significant reduction of volume overload during surgery. In this brief review we will present some of these most interesting topics around minimized circuits and the simplified low-volume cardioplegia and discuss their potential benefits on the clinical outcome.

Identification and improvement of isothiocyanate-based inhibitors on stomatal opening to act as drought tolerance-conferring agrochemicals

Stomatal pores in the plant epidermis open and close to regulate gas exchange between leaves and the atmosphere. Upon light stimulation, the plasma membrane (PM) H+-ATPase is phosphorylated and activated via an intracellular signal transduction pathway in stomatal guard cells, providing a primary driving force for the opening movement. To uncover and manipulate this stomatal opening pathway, we screened a chemical library and identified benzyl isothiocyanate (BITC), a Brassicales-specific metabolite, as a potent stomatal-opening inhibitor that suppresses PM H+-ATPase phosphorylation. We further developed BITC derivatives with multiple isothiocyanate groups (multi-ITCs), which demonstrate inhibitory activity on stomatal opening up to 66 times stronger, as well as a longer duration of the effect and negligible toxicity. The multi-ITC treatment inhibits plant leaf wilting in both short (1.5 h) and long-term (24 h) periods. Our research elucidates the biological function of BITC and its use as an agrochemical that confers drought tolerance on plants by suppressing stomatal opening.

Lightweight olefin block copolymers foams with shrinkable and recoverable performance via supercritical CO2 foaming

Thermoplastic elastomer foams with gas-rich structures occupy a high specific surface/volume ratio, which will take up lots of space for storage and transportation. Herein, micro-crosslinked olefin block copolymers (OBC) foams with shrinkable and recoverable functions were prepared via supercritical CO2 foaming to subtly solve the storage problem, and the shrinkage and recovery mechanisms were studied. The storage volume of OBC foams could shrink up to ∼78.5 % and maintain low volume condition for a long time through vacuum sealing technology. Meanwhile, the shrunk OBC foams could also be quickly and fully recovered by N2-assisted post-processing because of the regulation of gas exchange. And OBC foams with a density of 0.028 g/cm3 were prepared successfully. The compressive properties of OBC foams were investigated. Related design strategies can significantly reduce the transportation costs and energy consumption of OBC foams and are expected to be applied to other thermoplastic elastomers.

Halotolerant plant growth-promoting bacteria, Bacillus pumilus, modulates water status, chlorophyll fluorescence kinetics and antioxidant balance in salt and/or arsenic-exposed wheat

Seed priming is an effective and novel technique and the use of eco-friendly biological agents improves the physiological functioning in the vegetative stage of plants. This procedure ensures productivity and acquired stress resilience in plants against adverse conditions without contaminating the environment. Though the mechanisms of bio-priming-triggered alterations have been widely explained under induvial stress conditions, the interaction of combined stress conditions on the defense system and the functionality of photosynthetic apparatus in the vegetative stage after the inoculation to seeds has not been fully elucidated. After Bacillus pumilus inoculation to wheat seeds (Triticum aestivum), three-week-old plants were hydroponically exposed to the alone and combination of salt (100 mM NaCl) and 200 μM sodium arsenate (Na2HAsO4·7H2O, As) for 72 h. Salinity and As pollutant resulted in a decline in growth, water content, gas exchange parameters, fluorescence kinetics and performance of photosystem II (PSII). On the other hand, the seed inoculation against stress provided the alleviation of relative growth rate (RGR), relative water content (RWC) and chlorophyll fluorescence. Since there was no effective antioxidant capacity, As and/or salinity caused the induction of H2O2 accumulation and thiobarbituric acid reactive substances content (TBARS) in wheat . The inoculated seedlings had a high activity of superoxide dismutase (SOD) under stress. B. pumilis decreased the NaCl-induced toxic H2O2 levels by increasing peroxidase (POX) and enzymes/non-enzymes related to ascorbate-glutathione (AsA-GSH) cycle. In the presence of As exposure, the inoculated plants exhibited an induction in CAT activity. On the other hand, for H2O2 scavenging, the improvement in the AsA-GSH cycle was observed in bacterium priming plants plus the combined stress treatment. Since B. pumilus inoculation reduced H2O2 levels against all stress treatments, lipid peroxidation subsequently decreased in wheat leaves. The findings obtained from our study explained that the seed inoculation with B. pumilus provided an activation in the defense system and protection in growth, water status, and gas exchange regulation in wheat plants against the combination of salt and As.

Estimation of Pulmonary Gas Exchange in the Human Respiratory System Under Normal and Abnormal Conditions

ABSTRACT: The human respiratory system is a collection of organs and tissues that regulate gas exchange in the body. There are millions of alveoli in the lungs surrounded by tiny blood capillaries. By breathing, the body inhales oxygen which moves from the alveoli to the blood capillary, and then exhales carbon dioxide in the air that diffuses across the pulmonary membrane of the blood capillary to the alveoli. We aim to develop a mathematical model of respiratory gas exchange that can handle various situations. A Model should be capable of finding the diffusion rate of oxygen that enters into the capillary from the lungs and dissolves into a different level of hemoglobin. It is also able to give the relationship between oxygen and carbon dioxide concentration with time. Numerical simulation helps us to predict the responses of the cardiorespiratory system during a heavy workout, usual activity, and inactive situations. It also considered the various factors that affect the gas exchange relation between partial pressure and saturation.

Enhancing Wheat Growth and Yield through Salicylic Acid-Mediated Regulation of Gas Exchange, Antioxidant Defense, and Osmoprotection under Salt Stress

Salinity is a major challenge for agricultural productivity, adversely affecting crop growth and yield. In recent years, various techniques have been developed to increase crop tolerance to salinity, including seed priming. This study was carried out to assess the effects of salicylic acid (SA) priming (0-, 10- and 20-mM) in comparison with hydropriming on growth, physio-biochemical activities, and yield of two wheat varieties (AARI-11 and Ujala-15) under 0- and 170-mM sodium chloride (NaCl) toxicity. The exposure of wheat plants to NaCl led to a significant reduction in various growth factors, including fresh weight (40%), total chlorophyll (39%), stomatal conductance (42%), shoot Ca2+ (39%), and 1000-grain weight (34%). In contrast, salt stress triggered the activities of POD, SOD, CAT, glycine-betaine, phenolics, and proline. The application of 20 mM SA through seed priming was found to greatly improve the fresh root weight, chlorophyll b, POD activities, shoot Ca2+, and overall yield (up to 71, 66, 35, 57, and 44%, respectively) under salt stress. While hydropriming also enhanced wheat tolerance to salinity.