Maintenance Of pH Research Articles

Real time imaging of single extracellular vesicle pH regulation in a microfluidic cross-flow filtration platform

Extracellular vesicles (EVs) are cell-derived membranous structures carrying transmembrane proteins and luminal cargo. Their complex cargo requires pH stability in EVs while traversing diverse body fluids. We used a filtration-based platform to capture and stabilize EVs based on their size and studied their pH regulation at the single EV level. Dead-end filtration facilitated EV capture in the pores of an ultrathin (100 nm thick) and nanoporous silicon nitride (NPN) membrane within a custom microfluidic device. Immobilized EVs were rapidly exposed to test solution changes driven across the backside of the membrane using tangential flow without exposing the EVs to fluid shear forces. The epithelial sodium-hydrogen exchanger, NHE1, is a ubiquitous plasma membrane protein tasked with the maintenance of cytoplasmic pH at neutrality. We show that NHE1 identified on the membrane of EVs is functional in the maintenance of pH neutrality within single vesicles. This is the first mechanistic description of EV function on the single vesicle level.

Investigating the control of exercise hyperpnoea: A synergy of contributions.

Investigating the control of exercise hyperpnoea: A synergy of contributions.

Comparative proteomic profiling in Chinese shrimp Fenneropenaeus chinensis under low pH stress

Lower pH gives rise to a harmful stress to crustacean. Here, we analyzed the proteomic response of Fenneropenaeus chinensis from control pH (pH value 8.2) and low pH (pH value 6.5) - treated groups by employing absolute quantitation-based quantitative proteomic (iTRAQ) analysis. Among the identified proteins, a total of 76 proteins differed in their abundance levels, including 45 upregulated and 31 downregulated proteins. The up-regulation of proteins like citrate synthase, cytochrome c oxidase, V-type proton ATPase, glyceraldehyde-3-phosphate dehydrogenase and fructose 1,6-bisphosphate-aldolase as well as the enrichment of the DEPs in multiple metabolic processes and pathways illustrated that increased energy and substrates metabolism was essential for F. chinensis to counteract low pH stress. Ion transporting related proteins, such as Na+/K+/2Cl− cotransporter and calmodulin, participated in the homeostatic maintenance of pH in F. chinensis. There were significant downregulation expressions of lectin, lipopolysaccharide- and beta-1,3-glucan binding protein, chitinase, cathepsin L and beta-glucuronidase, which indicating the immune dysfunction of F. chinensis when exposure to low pH condition. These findings can extend our understanding on the defensive mechanisms of the low pH stress and accelerate the breeding process of low pH tolerance in F. chinensis.

Peppermint Essential Oil and Its Major Volatiles as Protective Agents against Soft Rot Caused by Fusarium sambucinum in Cera Pepper (Capsicum pubescens).

Cera pepper (Capsicum pubescens) is an exotic fruit considered as a rich source of nutraceuticals with known benefits for human health and also an economic resource for local producers in Mexico. The present investigation reports on the in vitro and in situ antifungal activity of the essential oil from Mentha piperita and its two major volatiles (menthol and menthone) against Fusarium sambucinum, which is a causal agent of soft rot in cera pepper. The application of these components in pepper fruits previously infected with F. sambucinum caused a significant delay (p<0.05) in the emergence of soft rot symptoms. This effect was reflected in the maintenance of pH and fruit firmness during a period of 10 days. The nutrimental content of the fruits (protein, fiber, fat and other proximate parameters) was conserved in the same period of time. The nutraceutical content of these fruits was estimated by the quantification of seven carotenoids (violaxanthin, cis-violaxanthin, luteoxanthin, antheraxanthin, lutein, zeaxanthin and β-carotene), ascorbic acid and capsaicinoids (capsaicin and dihydrocapsaicin). According to our results, the essential oil from M. Piperita and its major volatiles exerted a preservative effect on these metabolites. Our findings demonstrated that the essential oil of M. Piperita and its major volatiles represent an ecological alternative for the control of fusariosis caused by F. sambucinum in cera peppers under postharvest conditions.

Microbial desalination cell: Desalination through conserving energy

The increased requirement of potable water led to the development of efficient desalination technologies such as reverse osmosis membranes, which are currently mass-manufactured. However, other approaches are being explored, as emerging countries contribute to the global demand for drinking water. Microbial desalination cells (MDC), in which microbial consortia use chemical energy to remove ions from low-salinity aqueous solutions, have been investigated for some time but the actual relevance of this technology in the overall desalination industry remains unclear. pH maintenance on the cathodic side, internal resistance along with membrane fouling and its longevity are some technical shortcomings related to the practical use of MDCs, which can be partially circumvented by using multiple interconnected configurations. Further research is required to scale up the MDC technology while decreasing its cost and environmental impact. This review summarizes the operative principle of MDCs, the most common MDC cells configurations, and describes the variables that influence their performance in light of full-scale applications. A techno-economic analysis and lifecycle assessment of microbial desalination systems is also included, along with the description of electrode fabrication and genetic manipulation strategies that can improve the MDC cells performance.

Effects of treatment at a subzero temperature on pH, water retention, and metabolites in spotted mackerel (Scomber australasicus) muscle

Studies have shown that storing pre-rigor frozen fish at subzero temperatures before thawing might suppress pH drop after thawing in some migratory fish. Therefore, the mechanisms involved in pH maintenance and the effects on the quality of fish muscle were investigated here. Frozen spotted mackerel (Scomber australasicus) was stored at −10 °C for 1–10 d (hereinafter referred to as “−10 °C treatments”). pH, water retention, and the changes in primary metabolite concentrations were investigated in the frozen and thawed muscles. When the −10 °C treatment lasted for 5 d or longer, the thawed muscle maintained a minimum pH of 6.2, and the water-retention and water-reabsorption capacities of the frozen-thawed spotted mackerel muscle of −10 °C treatment samples increased compared with the control sample. In the −10 °C treatments, nicotinamide adenine dinucleotide (NAD) was consumed and glycolytic intermediate products accumulated in the frozen muscle. This result suggests anaerobic glycolysis was inhibited. The results of this investigation indicate that −10 °C treatments before thawing may increase the meat quality in frozen spotted mackerel.

Bicarbonate and pH Maintenance in a Sorbent Dialysis System

Bicarbonate and pH Maintenance in a Sorbent Dialysis System

A state-of-the-art review on microbial desalination cells

The rapid growth in population has increased the demand for potable water. Available technologies for its generation are the desalination of sea water through reverse osmosis, electrodialysis etc., which are energy and cost intensive. In this context, microbial desalination cell (MDC) presents a low-cost and sustainable option which can simultaneously treat wastewater, desalinate saline water, produce electrical energy and recover nutrients from wastewater. This review paper is focussed on presenting a detailed analysis of MDCs starting from the principle of operation, microbial community analysis, basic architecture, evolution in design, operational challenges, effect of process parameters, scale-up studies, application in multiple arenas and future prospects. After thorough review, it can be inferred that MDCs can be used as a stand-alone option or pre-treatment step for conventional desalination techniques without the application of external energy. MDCs have been used in multiple applications ranging from desalination, remediation of contaminated water, recovery of energy and nutrients from wastewater, softening of hardwater, biohydrogen production to degradation of waste engine oil. Although, MDCs have been used for multiple applications, still a number of operational challenges have been reported viz., interference of co-existing ions during desalination, membrane fouling, pH imbalance and limited potential of exoelectrogens. However, the re-circulation of anolytes with electrodialysis chamber has led to the maintenance of optimal pH for favourable microbial growth leading to improvement in the overall performance of MDCs. In future, genetic engineering may be used for improving the electrogenic activity of microbial community, next generation materials may be used as anode and cathode, varied sources of wastewater may be explored as anolytes, life cycle analysis and exergy analysis may be carried out to study the impact on environment and detailed pilot scale studies have to be carried out for assessing the feasibility of operation at large scale.

The Epidemiology and Global Burden of Atopic Dermatitis: A Narrative Review.

The global epidemiology of atopic dermatitis (AD) in the current decade (2009–2019) has not been extensively reported. Epidemiological studies play an important role in presenting the risk factors of AD, as detailed prevalence and incidence data could demonstrate the burden of disease in the population of adults, adolescents, and children in different geographical regions. Thus, the primary objective of this review was to assess and summarize the epidemiological studies of the prevalence and incidence of AD in different age groups, focusing on data from studies published for 2009 to 2019. After a thorough literature search, six countries were identified from African, Asian, and European regions respectively, who published studies on AD. In contrast, only two studies were identified from Australia and New Zealand, three countries from North America and two from South America published AD studies, respectively. The highest prevalence of AD from included studies was noted among Swedish children with 34%, while the lowest prevalence was in Tunisian children with 0.65%; studies reporting incidence data were far less numerous. A common trend in the prevalence of AD was that children would have a higher prevalence as compared to adolescents and adults. The severity and morbidity of the disease showed variance with age, sex, socioeconomic characteristics, geographical location, and ethnicity. Environmental factors played an important role as causative agents in AD. The risk factors that were proven to cause and induce AD were skin barrier impairments due to FLG mutation, changes in the environment, and diet. FLG mutation may impair the skin barrier function by disruption of pH and hydration maintenance of the skin. Lastly, there were only a few studies on the incidence of AD in the 21st century. Therefore, epidemiological studies on childhood and adulthood AD in different continents are still needed, especially on the incidence of AD during adulthood.

Assessment of Acid-Base Status: Beyond Serum Bicarbonate.

Maintenance of normal blood pH is critical for cellular function. Yet, blood pH is uncommonly measured in the outpatient setting. Instead, serum [total CO2] ([TCO2]) is used to screen for acid-base disturbances, the argument being that both metabolic and respiratory disorders are generally

Multi-Metal Mining from Waste Cell Phone Printed Circuit Boards using Lixiviant Produced by a Consortium of Acidophilic Iron Oxidizers

Recently electronic waste (e-waste) includes the fastest growing waste stream in the world. Nevertheless, it also contains about 40 different elements of the periodic table; hence it is a significant metal source. Generally, e-waste recycling is done by the pyrometallurgy and/or hydrometallurgy method. However, the use of microorganisms in hydrometallurgy called bioleaching is a good alternative for eco-friendly and cost-effective recycling of e-waste and recover metals. Leptospirillum-dominated consortium was used to generate ferric iron lixiviant by oxidizing ferrous iron. The resulting lixiviant was used for bioleaching of metals from waste cell phone printed circuit boards (WPCBs). The pretreatment of pulverized WPCB (p-WPCB) and unpulverized WPCB (up-WPCB) was done using 2 M NaOH to see the effect of pretreatment on metal extraction. Moreover, the effect of maintenance of pH of the system was also checked. The controlling of pH of the system to 2.0 ± 0.1 showed enhancement of Cu, Zn, and Ni solubilization. The highest solubilization of copper was 96.86%, which was achieved with pretreated up-WPCB; zinc was 90.69% with pretreated p-WPCB, whereas nickel was 93.65% with untreated up-WPCB. Ours is the first report for extraction of copper, zinc, and nickel from unpulverized mobile phone WPCBs at high pulp density. The solubilization of metals achieved with 100 g/L pulp density provides a promising indication to scale up the process.

High-cell-density cultivation of the flagellate alga Poterioochromonas malhamensis for biomanufacturing the water-soluble β-1,3-glucan with multiple biological activities

The microalga Poterioochromonas malhamensis was found to be capable of accumulating the storage β-1,3-glucan in soluble form under heterotrophic conditions. In this study, the highest biomass yield of 32.8 g L−1 was achieved by combining the utilization of ammonium chloride as the nitrogen source, simultaneous addition of vitamins B1 and B12 and maintenance of pH at 6.0. Sugar profiling and nuclear magnetic resonance analysis indicated that the P. malhamensis β-1,3-glucan was composed of glucose with the β-(1 → 3) main chain and the β-(1 → 6) side chain. Under the optimal cultivation conditions, the cellular β-1,3-glucan content was up to 55% of the cell dry weight. Moreover, the P. malhamensis β-1,3-glucan could significantly promote the fin regeneration and improve the in vivo antioxidative activity of zebrafish. This study underpins the feasibility of culturing P. malhamensis under heterotrophic conditions for producing the highly water-soluble bioactive β-1,3-glucans for food and pharmaceutical applications.

Optimizing Nitrogen Fixation and Recycling for Food Production in Regenerative Life Support Systems

Nitrogen (N) recycling is essential for efficient food production in regenerative life support systems. Crew members with a high workload need 90–100 g of protein per person per day, which is about 14 g of N, or 1 mole of N, per person per day. Most of this N is excreted through urine with 85% as urea. Plants take up N predominantly as nitrate and ammonium, but direct uptake as urea is possible in small amounts. Efficient N recycling requires maintenance of pH of waste streams below about 7 to minimize the volatilization of N to ammonia. In aerobic reactors, continuous aerobic conditions are needed to minimize production and volatilization of nitrous oxide. N is not well recycled on Earth. The energy intensive Haber–Bosh process supplies most of the N for crop production in terrestrial agriculture. Bacterial fixation of dinitrogen to ammonium is also energy intensive. Recycling of N from plant and human waste streams is necessary to minimize the need for N fixation. Here we review approaches and potential for N fixation and recycling in regenerative life support systems. Initial estimates indicate that nearly all the N from human and plant waste streams can be recovered in forms usable for plants.

Optimization of Biogas Production by Co-Digestion of Organic Waste (Cow Dung and Water Hyacinth)

The objective of this work is to determine the co-digestion ratio of water hyacinth and cow dung for the optimization of biogas production at Sô Ava, a lake city of Southern Benin. To achieve these ratios, we suppose that the water hyacinth has a high gas yield and cow dung ensures stability in the biodigester because it brings fresh bacteria and has a strong buffering capacity (maintenance of a stable pH). For 45 days, we have introduced a mixture of water hyacinth and cow dung in 5 mini-biodigesters of 10 liters each: digester no1 (100% of cow dung); digester no2 (100% of the water hyacinth); digester n° 3 (50% of the water hyacinth and 50% of the cow dung); digester no4 (75% of cow dung and 25% of water hyacinth); digester no5 (75% of the water hyacinth and 25% of the cow dung). The measurements of the pH, temperature and the proportion of gas (CH4, CO2, O2 and H2S) in the mini-biodigesters was done. The measurements show that the digester n° 5 produces the highest capacity of 15.24L of biogas with 70% of methane while the digester n °2 has the lowest capacity 5.47L of biogas with 58% methane. These results show that the yield of biogas produced is greater when using the mixture of the substrate with the ratio of 75% of water hyacinth and 25% of cow dung. This result encourages the energy recovery from water hyacinth, once considered as a seasonal plague which hinders navigation of local boat in the lake.

Short communication: Effects of acute copper exposure on ionic regulation of the freshwater crab Aegla castro

Aeglids are unique freshwater decapods whose habitats are being impacted by metallic compounds, such as copper (Cu). Thus, we investigated the effects of acute Cu exposure on ionic regulation of Aegla castro. For this, male specimens in intermolt were collected from a reference stream and acclimated for 5 days in laboratory. After which, crabs were exposed to 11 μg L−1 Cu (Cu11) or only to water (CTR) for 24 h. Hemolymph samples were withdrawn for the determination of Na+, K+, Ca2+, and Mg2+ concentrations and the posterior gills removed for the analysis of Na+/K+-ATPase, Ca2+-ATPase, H+-ATPase, and carbonic anhydrase (CA) activities. Increased Ca2+ and Mg2+ hemolymph concentrations were observed in animals from Cu11, when compared with CTR group. In addition, decreased activity of CA was observed in animals exposed to Cu. In the current study, alterations in Ca2+ and Mg2+concentrations probably indicate that animals activated exoskeleton reabsorption mechanisms, characteristic of the premolt. Therefore, increased Ca2+ and Mg2+ concentrations in hemolymph may indicate that a biochemical signal associated with the molting cycle was triggered by Cu exposure. Despite the known harmful effects of Cu on osmoregulatory enzymes, here we observed decreased activity only in CA. However, decreased activity of CA could trigger both acid-base imbalance and ionic disruption, since CA provides H+ and HCO3− for intracellular pH maintenance, and underpins Na+ and Cl− for ionic regulation. Therefore, understanding how aeglids respond to metal contamination in laboratory conditions is crucial to assess their potential as an alternative biological model for aquatic ecotoxicology.

Performance analysis of composite carp culture policies in drought prone district Purulia in West Bengal, India

The development of composite culture of carps in Purulia, an economically underdeveloped district of India, is confronted with several socio-economic, topographic, and climatic challenges. West Bengal Accelerated Development of Minor Irrigation Project (WBADMIP), an innovative integrated program of irrigation, agriculture, horticulture, and fisheries interventions through community institutions, was implemented in Purulia by the Government of West Bengal and was supported by the World Bank. Performances of the composite culture of carps in 172 water bodies by fisheries interest groups under the initiatives of WBADMIP were evaluated based on 18 different parameters using the k-mean algorithm. The results indicated that the water bodies could be categorized into three Clusters, based on inputs, expenditure, production, and income. Cluster 1, consisting of 85 water bodies, exhibited moderate performance with an average production of 2351 kg/ha, followed by Cluster 2 of 49 water bodies exhibiting poor performance with an average production of 1463 kg/ha, and Cluster 3 of 38 water bodies exhibiting best performance with an average production of 2488 kg/ha. Euclidean distance between Cluster centers 1 and 2 was 4.511 as compared to 3.737 and 5.102 between the Cluster centers 1 and 3 and 2 and 3, respectively. The water bodies with higher productivity were primarily associated with the WBADMIP policy that mobilized trained farmers who could adequately manage the application of feed, lime, inorganic fertilizers, and organic fertilizers. Using decision tree analysis, we predicted that the maintenance of water pH above 6.9 is crucial in obtaining optimum carps production from these water bodies. In contrast, the use of lime, inorganic fertilizers, organic fertilizers, and an adequate amount of feed need to be adjusted to maintain an economically viable production system. It is concluded that the farmers' motivation and professional training along with project support can substantially improve the productivity of the water bodies, support the nutrition of the farmers' community, and boost the local economy.

Revealing the salt tolerance mechanism of Tamarix hispida by large-scale identification of genes conferring salt tolerance.

The identification of genes conferring salt tolerance is important to reveal plant salt tolerance mechanisms. Here, we employed yeast expression system combined with high-throughput sequencing to identify genes conferring salt tolerance from Tamarix hispida Willd. A total of 1224 potential genes conferring salt tolerance were identified. Twenty-one genes were randomly selected for functional characterization using transient transformation in T. hispida and stable transformation in Arabidopsis thaliana (L.) Heynh. More than 90% of studied genes are found to confer tolerance to salt stress, indicating that the identified genes are reliable. More than 75% of the identified genes were highly expressed in roots rather than in leaves, suggesting roots play an important role in salt tolerance. The genes belonging to 'response to stimulus' were highly accumulated , and these accounted for 32% of the total identified genes. In addition, the processes of 'protein translation', 'osmotic adjustment', 'scavenging of free radicals', 'photosynthesis, detoxification of cells', 'protection of cellular macromolecules' and 'maintenance of cellular pH' play important roles in salt tolerance. This study provides useful information on the salt tolerance mechanism of T. hispida and offers a valuable resource for exploring genes used in salt tolerance breeding.

Elucidating the Role of the Skin Barrier Protein Filaggrin in the Adaptive Immune Response to Commensals

Atopic dermatitis (AD), commonly known as eczema, is a chronic inflammatory skin disease that affects millions of Americans. While there are both genetic and environmental components, one of the key factors is disruption of skin barrier physiology. In particular, mutations in the filaggrin are found in up to 40% of patients and predispose them to severe, early onset AD and later progression along the atopic march. Filaggrin is expressed in the upper layers of the skin epithelium and contributes to maintenance of skin pH and moisturization, critical for maintaining the structural function of the epidermis. The skin barrier is also important for regulating the response to bacteria. In AD, disease flares are also associated with an altered skin microbiome, with increases in Staphylococcus epidermidis (S. epi), a skin commensal, and Staphylococcus aureus, a pathobiont. There are many open questions about what role impaired skin epithelial barrier function plays in the adaptive immune response to commensals like S. epi, and how this may contribute to disease. I hypothesize that early life deficiency of skin barrier function alters the quality of the commensal-specific T cell response, which contributes to later pro-inflammatory responses to these bacteria. Antigen specific T cell responses are difficult to study due to the rarity of individual T cell clones, so our lab uses a novel system allowing tracking of CD4+ T cells specific for S. epi. I have found that mice lacking filaggrin (flg-/-) differ from wildtype (wt) controls in their immune response to this commensal. Our lab has previously shown that wt mice colonized early in life develop immune tolerance to S. epi via enrichment of antigen-specific regulatory T cells (Tregs), an immune cell population that controls inflammation. This new work shows that in several models of S. epi colonization, flg-/- mice elicit reduced frequencies of commensal antigen-specific Tregs compared to wt counterparts. This project also focuses on elucidating the mechanistic basis of this key finding and determining its contribution towards propensity for skin and systemic type-2 inflammation. In summary, our work suggests that skin barrier physiology significantly impacts the quality of the commensal-specific CD4+ response early in life, which may have enduring consequences for skin immune homeostasis.

Transport Mechanism Insights from Newly Identified Substrate Binding Sites in Two SLC4 Transporters

The secondary transporters from the SLC4 family are involved in transmembrane transport of HCO3−, CO32−, Na+, Cl− and H+ ions necessary for pH maintenance, blood pressure, and ion homeostasis in the organism. Two outward facing structures of members of the SLC4 family, the human anion exchanger 1 (SLC4A1, hAE1) and the human electrogenic sodium bicarbonate cotransporter 1 (SLC4A4, hNBCe1) have been resolved previously with X-Ray and Cryo-EM spectroscopy and reveal a common 3D fold with a large ion and water permeation cavity, lined with basic and acidic residues. The exact position and composition of the binding sites within the cavity are as of yet unknown, since the available structures did not resolve bound ions. Several residues of transport significance have been identified from previous functional mutagenesis studies. Here we make use of multiple molecular dynamics simulations and functional mutagenesis measurements to identify putative binding sites in hAE1 and hNBCe1. We hypothesize that the surprisingly different transport modes of hAE1 and hNBCe1 (exchanger vs symporter, respectively) are governed by a small number of residues in the ion binding pocket. Our computational and experimental results provide evidence for the existence of two binding sites (entry and central) in the outward facing cavity of hAE1 and hNBCe1. The newly identified binding sites feature charged, polar and hydrophobic residues with potential specific roles in ion selectivity, pH sensing, substrate coordination, and gating and provide basis for distinction between the transport modes of hAE1 and hNBCe1.

From Prokaryotes to Eukaryotes: Insights Into the Molecular Structure of Glycogen Particles.

Glycogen is a highly-branched polysaccharide that is widely distributed across the three life domains. It has versatile functions in physiological activities such as energy reserve, osmotic regulation, blood glucose homeostasis, and pH maintenance. Recent research also confirms that glycogen plays important roles in longevity and cognition. Intrinsically, glycogen function is determined by its structure that has been intensively studied for many years. The recent association of glycogen α-particle fragility with diabetic conditions further strengthens the importance of glycogen structure in its function. By using improved glycogen extraction procedures and a series of advanced analytical techniques, the fine molecular structure of glycogen particles in human beings and several model organisms such as Escherichia coli, Caenorhabditis elegans, Mus musculus, and Rat rattus have been characterized. However, there are still many unknowns about the assembly mechanisms of glycogen particles, the dynamic changes of glycogen structures, and the composition of glycogen associated proteins (glycogen proteome). In this review, we explored the recent progresses in glycogen studies with a focus on the structure of glycogen particles, which may not only provide insights into glycogen functions, but also facilitate the discovery of novel drug targets for the treatment of diabetes mellitus.