Effects of long-term dehydration and quick rehydration on the camel kidney: pathological changes and modulation of the expression of solute carrier proteins and aquaporins.

BACKGROUND: Recurrent dehydration causes chronic kidney disease in humans and animal models. The dromedary camel kidney has remarkable capacity to preserve water and solute during long-term dehydration. In this study, we investigated the effects of dehydration and subsequent rehydration in the camel's kidney histology/ultrastructure and changes in aquaporin/solute carrier proteins along with gene expression. RESULTS: In light microscopy, dehydration induced few degenerative and necrotic changes in cells of the cortical tubules with unapparent or little effect on medullary cells. The ultrastructural changes encountered in the cortex were infrequent during dehydration and included nuclear chromatin condensation, cytoplasmic vacuolization, mitochondrial swelling, endoplasmic reticulum/ lysosomal degeneration and sometimes cell death. Some mRNA gene expressions involved in cell stability were upregulated by dehydration. Lesions in endothelial capillaries, glomerular membranes and podocyte tertiary processes in dehydrated camels indicated disruption of glomerular filtration barrier which were mostly corrected by rehydration. The changes in proximal tubules brush borders after dehydration, were accompanied by down regulation of ATP1A1 mRNA involved in Na + /K + pump that were corrected by rehydration. The increased serum Na, osmolality and vasopressin were paralleled by modulation in expression level for corresponding SLC genes with net Na retention in cortex which were corrected by rehydration. Medullary collecting ducts and interstitial connective tissue were mostly unaffected during dehydration. CKD, a chronic nephropathy induced by recurrent dehydration in human and animal models and characterized by interstitial fibrosis and glomerular sclerosis, were not observed in the dehydrated/rehydrated camel kidneys. The initiating factors, endogenous fructose, AVP/AVPR2 and uric acid levels were not much affected. TGF-ß1 protein and TGF-ß1gene expression showed no changes by dehydration in cortex/medulla to mediate fibrosis. KCNN4 gene expression level was hardly detected in the dehydrated camel's kidney; to encode for Ca + + -gated KCa3.1 channel for Ca + + influx to instigate TGF-ß1. Modulation of AQP 1, 2, 3, 4, 9 and SLC protein and/or mRNAs expression levels during dehydration/rehydration was reported. CONCLUSIONS: Long-term dehydration induces reversible or irreversible ultrastructural changes in kidney cortex with minor effects in medulla. Modulation of AQP channels, SLC and their mRNAs expression levels during dehydration/rehydration have a role in water conservation. Cortex and medulla respond differently to dehydration/rehydration.

Whole-body urea kinetics and functional roles of urea transporters and aquaporins in urea secretion into the rumen in sheep fed diets varying in crude protein content and corn grain processing method.

The objectives were to determine the effects of dietary crude protein (CP) content and corn grain processing on whole-body urea kinetics and the functional roles of urea transporter-B (UT-B) and aquaporins (AQP) in serosal-to-mucosal urea flux (Jsm-urea) in ovine ruminal epithelia. Thirty-two Rideau-Arcott ram lambs were blocked by bodyweight into groups of 4 and then randomly allocated within blocks to 1 of 4 diets (n = 8) in a 2 × 2 factorial design. Dietary factors were CP content (11% [LP] vs. 16% [HP]) and corn grain processing (whole-shelled [WSC] vs. steam-flaked [SFC] corn). Whole-body urea kinetics and N balance were determined using 4-d continuous intrajugular infusions of [15N15N]-urea with concurrent collections of urine and feces with four blocks of lambs (n = 4). After 23 d on diets, lambs were killed to collect ruminal epithelia for mounting in Ussing chambers to determine Jsm-urea and the measurement of mRNA abundance of UT-B and AQP. Serosal and mucosal additions of phloretin and NiCl2 were used to inhibit UT-B- and AQP-mediated urea transport, respectively. Lambs fed HP had a greater (P < 0.01) N intake (29.4 vs. 19.1 g/d) than those fed LP; however, retained N (g/d or % of N intake) was not different. As a % of N intake, lambs fed SFC tended (P = 0.09) to have a lower N excretion (72.2 vs. 83.5%) and a greater N retention (27.8 vs. 16.6%) compared to those fed WSC. Endogenous urea-N production (UER) was greater in lambs fed HP compared to those fed LP (29.9 vs. 20.6 g/d; P = 0.02), whereas urea-N secreted into the gut (GER; g/d) and urea-N used for anabolic purposes (UUA; g/d) were similar. Lambs fed LP tended (P = 0.05) to have greater GER:UER (0.78 vs. 0.66) and UUA:GER (0.23 vs. 0.13) ratios, and a greater Jsm-urea (144.7 vs. 116.1 nmol/[cm2 × h]; P = 0.07) compared to those fed HP. Lambs fed SFC tended to have a lower NiCl2-insensitive Jsm-urea (117.4 vs. 178.4 nmol/[cm2 × h]; P = 0.09) and had a lower phloretin-insensitive Jsm-urea (87.1 vs. 143.1 nmol/[cm2 × h]; P = 0.02) compared to those fed WSC. The mRNA abundance of UT-B (0.89 vs. 1.07; P = 0.08) and AQP-3 (0.90 vs. 1.05; P = 0.07) tended to be lower in lambs fed SFC compared to those fed WSC. Overall, reducing CP content tended to increase the GER:UER ratio with no changes in the expression or function of UT-B and AQP. Although corn grain processing had no effects on GER, feeding SFC increased the portion of urea secretion into the rumen that was mediated via UT-B and AQP.

The tonoplast-localized OsTIP2;1 is involved in aluminum detoxification in rice.

Aluminum (Al) stress is a significant issue in acidic soils, severely affecting crop growth and yield. Rice is notably resilient to Al toxicity, yet the internal tolerance mechanisms remain inadequately addressed. Here, we examined the role of OsTIP2;1, a tonoplast-bound intrinsic protein (TIP), in rice's internal Al detoxification. Our findings reveal that OsTIP2;1 expression was quickly and explicitly activated by Al ions in roots but not in shoots. The OsTIP2;1-GFP protein localizes to the tonoplast in plant and yeast cells. Non-functional ostip2;1 rice mutants were more vulnerable to Al toxicity. In the roots, the ostip2;1 mutants exhibited considerably lower levels of Al in the cell sap, primarily the vacuolar contents, than in the wild-type plant. Moreover, the ostip2;1 mutants showed reduced Al accumulation in the roots but increased translocation to the shoots. Heterologous expression of tonoplast-localized OsTIP2;1 in yeast led to enhanced Al tolerance, suggesting that OsTIP2;1 facilitates Al sequestration to the vacuole. These findings indicate that OsTIP2;1 mediates internal detoxification by transporting Al into the vacuole in the root and restricting its transport to above-ground tissues, thus contributing to Al resistance in rice.

Role of the Glymphatic System in Alzheimer's Disease and Treatment Approaches: A Narrative Review.

Currently, there is unavailability of disease-modifying medication for Alzheimer's disease (AD), a debilitating neurological disorder. The pathogenesis of AD appears to be complex and could be influenced by the glymphatic system present in the central nervous system (CNS). Amyloid-beta (Aß) and other metabolic wastes are eliminated from the brain interstitium by the glymphatic system, which encompasses perivascular channels and astroglial cells. Dysfunction of the glymphatic system, which could occur due to decreased aquaporin 4 (AQP4) expression, aging-related alterations in the human brain, and sleep disruptions, may contribute to the pathogenesis of AD and also accelerate the development of AD by causing a buildup of harmful proteins like Aß. Promising approaches have been examined for reducing AD pathology, including non-pharmacological therapies that target glymphatic function, like exercise and sleep regulation. In addition, preclinical research has also demonstrated the therapeutic potential of pharmaceutical approaches targeted at augmenting AQP4-mediated glymphatic flow. To identify the precise processes driving glymphatic dysfunction in AD and to find new treatment targets, more research is required. Innovative diagnostic and treatment approaches for AD could be made possible by techniques such as dynamic contrast-enhanced MRI, which promises to evaluate glymphatic function in neurodegenerative diseases. Treatment options for AD and other neurodegenerative diseases may be improved by comprehending and utilizing the glymphatic system's function in preserving brain homeostasis and targeting the mechanisms involved in glymphatic functioning. This review intends to enhance the understanding of the complex link between AD and the glymphatic system and focuses on the function of AQP4 channels in promoting waste clearance and fluid exchange.

Corrigendum: Expression patterns of maize PIP aquaporins in middle or upper leaves correlate with their different physiological responses to drought and mycorrhiza.

[This corrects the article DOI: 10.3389/fpls.2022.1056992.].

Exploring the potential of water channels for developing genetically encoded reporters and biosensors for diffusion-weighted MRI.

Genetically encoded reporters for magnetic resonance imaging (MRI) offer a valuable technology for making molecular-scale measurements of biological processes within living organisms with high anatomical resolution and whole-organ coverage without relying on ionizing radiation. However, most MRI reporters rely on synthetic contrast agents, typically paramagnetic metals and metal complexes, which often need to be supplemented exogenously to create optimal contrast. To eliminate the need for synthetic contrast agents, we previously introduced aquaporin-1, a mammalian water channel, as a new reporter gene for the fully autonomous detection of genetically labeled cells using diffusion-weighted MRI. In this study, we aimed to expand the toolbox of diffusion-based genetic reporters by modulating aquaporin membrane trafficking and harnessing the evolutionary diversity of water channels across species. We identified a number of new water channels that functioned as diffusion-weighted reporter genes. In addition, we show that loss-of-function variants of yeast and human aquaporins can be leveraged to design first-in-class diffusion-based sensors for detecting the activity of a model protease within living cells.

A mechanohydraulic model supports a role for plasmodesmata in cotton fiber elongation.

Plant cell growth depends on turgor pressure, the cell hydrodynamic pressure, which drives expansion of the extracellular matrix (the cell wall). Turgor pressure regulation depends on several physical, chemical, and biological factors, including vacuolar invertases, which modulate osmotic pressure of the cell, aquaporins, which determine the permeability of the plasma membrane to water, cell wall remodeling factors, which determine cell wall extensibility (inverse of effective viscosity), and plasmodesmata, which are membrane-lined channels that allow free movement of water and solutes between cytoplasms of neighboring cells, like gap junctions in animals. Plasmodesmata permeability varies during plant development and experimental studies have correlated changes in the permeability of plasmodesmal channels to turgor pressure variations. Here, we study the role of plasmodesmal permeability in cotton fiber growth, a type of cell that increases in length by at least three orders of magnitude in a few weeks. We incorporated plasmodesma-dependent movement of water and solutes into a classical model of plant cell expansion. We performed a sensitivity analysis to changes in values of model parameters and found that plasmodesmal permeability is among the most important factors for building up turgor pressure and expanding cotton fibers. Moreover, we found that nonmonotonic behaviors of turgor pressure that have been reported previously in cotton fibers cannot be recovered without accounting for dynamic changes of the parameters used in the model. Altogether, our results suggest an important role for plasmodesmal permeability in the regulation of turgor pressure.

Characterization of human aquaporin ion channels in a yeast expression system as a tool for novel ion channel discovery.

Aquaporin (AQP) channels found in all domains of life are transmembrane proteins which mediate passive transport of water, glycerol, signaling molecules, metabolites, and charged solutes. Discovery of new classes of ion-conducting AQP channels has been slow, likely reflecting time- and labor-intensive methods required for traditional electrophysiology. Work here defines a sensitive mass-throughput system for detecting AQP ion channels, identified by rescue of cell growth in the K+-transport-defective yeast strain CY162 following genetic complementation with heterologously expressed cation-permeable channels, using the well characterized human AQP1 channel for proof of concept. Results showed AQP1 conferred transmembrane permeability to cations which rescued survival in CY162 yeast. Comprehensive testing showed that growth response properties fully recapitulated AQP1 pharmacological agonist and antagonist profiles for activation, inhibition, dose-dependence, and structure-function relationships, demonstrating validity of the yeast screening tool for AQP channel identification and drug discovery efforts. This method also provided new information on divalent cation blockers of AQP1, pH sensitivity of antagonists, and ion permeability of human AQP6. Site-directed mutagenesis of AQP1 channel regulatory domains confirmed that yeast growth rescue was mediated by the introduced channels. Optical monitoring with a lithium-sensitive photoswitchable probe in living cells independently demonstrated monovalent cation permeability of AQP1 channels in yeast plasma membrane. Ion channel properties of AQP1 expressed in yeast were consistent with those of AQP1 expressed in Xenopus laevis oocyte and K+-transport defective Escherichia coli. Outcomes here establish a powerful new approach for efficient screening of phylogenetically diverse AQPs for yet untested functions as cation channels.

Comparison of aquaporin profile of advanced passage mesenchymal stem cells with early passage mesenchymal stem cells and determination of its effect on adipogenic differentiation efficiency.

OBJECTIVE: Our study aimed to compare aquaporin profiles in advanced and early passage bone marrow-derived mesenchymal stem cells (BM-MSCs) and assess the impact of aquaporin changes after adipogenic differentiation. Aquaporins are crucial for stem cell survival and differentiation during their life cycle. We focused on the role of aquaporins in the cell structures of advanced and early passage stem cells. METHODS: In our study, BM-MSCs were used for our objectives. Characterization of the cells was evaluated via flow cytometry using stem cell surface markers. The characterized BM-MSCs were divided into control and differentiation groups at passages 3 (P3) and 8 (P8). AQP1, AQP3, AQP7, AQP9, and AQP10 expression levels on days 0, 1, 3, 7, 14, and 21 were evaluated using Real Time-PCR, ELISA, and immunofluorescence studies. RESULTS: The cells were characterized by flow cytometry and confirmed to exhibit BM-MSC characteristics. At P3 and P8, differentiation was initiated, and AQP protein expression was observed to initially increase and then decrease on subsequent days. The increase in AQP protein expression at P3 occurred earlier than that at P8. Gene expression analysis demonstrated a statistically significant increase in AQP gene expression on days when AQP protein expression decreased. Moreover, statistical differences were observed between late and early passage AQP profiles. CONCLUSION: Our study examined the composition of AQPs in BM-MSCs in association with cell passage, and found that AQPs play a role in the differentiation process. The connection between the AQP profile and aging might be related to differentiation capacity, which could have implications for slowing down cellular aging and developing new therapeutic approaches.

Meta-QTL and Candidate Gene Analyses of Agronomic Salt Tolerance and Related Traits in an RIL Population Derived from Solanum pimpinellifolium.

Breeding salt-tolerant crops is necessary to reduce food insecurity. Prebreeding populations are fundamental for uncovering tolerance alleles from wild germplasm. To obtain a physiological interpretation of the agronomic salt tolerance and better criteria to identify candidate genes, quantitative trait loci (QTLs) governing productivity-related traits in a population of recombinant inbred lines (RIL) derived from S. pimpinellifolium were reanalyzed using an SNP-saturated linkage map and clustered using QTL meta-analysis to synthesize QTL information. A total of 60 out of 85 QTLs were grouped into 12 productivity MQTLs. Ten of them were found to overlap with other tomato yield QTLs that were found using various mapping populations and cultivation conditions. The MQTL compositions showed that fruit yield was genetically associated with leaf water content. Additionally, leaf Cl- and K+ contents were related to tomato productivity under control and salinity conditions, respectively. More than one functional candidate was frequently found, explaining most productivity MQTLs, indicating that the co-regulation of more than one gene within those MQTLs might explain the clustering of agronomic and physiological QTLs. Moreover, MQTL1.2, MQTL3 and MQTL6 point to the root as the main organ involved in increasing productivity under salinity through the wild allele, suggesting that adequate rootstock/scion combinations could have a clear agronomic advantage under salinity.

Peroxiporins in Triple-Negative Breast Cancer: Biomarker Potential and Therapeutic Perspectives.

Triple-negative breast cancer (TNBC) remains one of the most challenging subtypes since it is initially characterized by the absence of specific biomarkers and corresponding targeted therapies. Advances in methodology, translational informatics, genomics, and proteomics have significantly contributed to the identification of therapeutic targets. The development of innovative treatments, such as antibody-drug conjugates and immune checkpoint inhibitors, alongside chemotherapy, has now become the standard of care. However, the quest for biomarkers defining therapy outcomes is still ongoing. Peroxiporins, which comprise a subgroup of aquaporins, which are membrane pores facilitating the transport of water, glycerol, and hydrogen peroxide, have emerged as potential biomarkers for therapy response. Research on peroxiporins reveals their involvement beyond traditional channeling activities, which is also reflected in their cellular localization and roles in cellular signaling pathways. This research on peroxiporins provides fresh insights into the mechanisms of therapy resistance in tumors, offering potential avenues for predicting treatment outcomes and tailoring successful TNBC therapies.

Canopy Architecture and Sun Exposure Influence Berry Cluster-Water Relations in the Grapevine Variety Muscat of Alexandria.

Climate-change-related increases in the frequency and intensity of heatwaves affect viticulture, leading to losses in yield and grape quality. We assessed whether canopy-architecture manipulation mitigates the effects of summer stress in a Mediterranean vineyard. The Vitis vinifera L variety Muscat of Alexandria plants were monitored during 2019-2020. Two canopy shoot-positioning treatments were applied: vertical shoot positioning (VSP) and modulated shoot positioning (MSP). In MSP, the west-side upper foliage was released to promote partial shoot leaning, shading the clusters. Clusters were sampled at pea size (PS), veraison (VER), and full maturation (FM). Measurements included rachis anatomy and hydraulic conductance (Kh) and aquaporins (AQP) and stress-related genes expression in cluster tissues. The results show significant seasonal and interannual differences in Kh and vascular anatomy. At VER, the Kh of the rachis and rachis+pedicel and the xylem diameter decreased but were unaffected by treatments. The phloem-xylem ratio was either increased (2019) or reduced (2020) in MSP compared to VSP. Most AQPs were down-regulated at FM in pedicels and up-regulated at VER in pulp. A potential maturation shift in MSP was observed and confirmed by the up-regulation of several stress-related genes in all tissues. The study pinpoints the role of canopy architecture in berry-water relations and stress response during ripening.

Mechanism of the Pulvinus-Driven Leaf Movement: An Overview.

Leaf movement is a manifestation of plant response to the changing internal and external environment, aiming to optimize plant growth and development. Leaf movement is usually driven by a specialized motor organ, the pulvinus, and this movement is associated with different changes in volume and expansion on the two sides of the pulvinus. Blue light, auxin, GA, H+-ATPase, K+, Cl-, Ca2+, actin, and aquaporin collectively influence the changes in water flux in the tissue of the extensor and flexor of the pulvinus to establish a turgor pressure difference, thereby controlling leaf movement. However, how these factors regulate the multicellular motility of the pulvinus tissues in a species remains obscure. In addition, model plants such as Medicago truncatula, Mimosa pudica, and Samanea saman have been used to study pulvinus-driven leaf movement, showing a similarity in their pulvinus movement mechanisms. In this review, we summarize past research findings from the three model plants, and using Medicago truncatula as an example, suggest that genes regulating pulvinus movement are also involved in regulating plant growth and development. We also propose a model in which the variation of ion flux and water flux are critical steps to pulvinus movement and highlight questions for future research.

Aquaporins in colorectal cancer: exploring their role in tumorigenesis, metastasis, and drug response.

Aquaporins (AQPs) are small, integral proteins facilitating water transport across plasma cell membranes in response to osmotic gradients. This family has 13 unique members (AQP0-12), which can also transport glycerol, urea, gases, and other salute small molecules. AQPs play a crucial role in the regulation of different cellular processes, including metabolism, migration, immunity, barrier function, and angiogenesis. These proteins are found to aberrantly overexpress in various cancers, including colorectal cancer (CRC). Growing evidence has explored AQPs as a potential diagnostic biomarker and therapeutic target in different cancers. However, there is no comprehensive review compiling the available information on the crucial role of AQPs in the context of colorectal cancer. This review highlights the significance of AQPs as the biomarker and regulator of tumor cells metabolism. In addition, the proliferation, angiogenesis, and metastasis of tumor cells related to AQPs expression as well as function are discussed. Understanding the AQPs prominent role in chemotherapy resistance is of great importance clinically.

Silicon derived benefits to combat biotic and abiotic stresses in fruit crops: Current research and future challenges.

Fruit crops are frequently subjected to biotic and abiotic stresses that can significantly reduce the absorption and translocation of essential elements, ultimately leading to a decrease in crop yield. It is imperative to grow fruits and vegetables in areas prone to drought, salinity, and extreme high, and low temperatures to meet the world's minimum nutrient demand. The use of integrated approaches, including supplementation of beneficial elements like silicon (Si), can enhance plant resilience under various stresses. Silicon is the second most abundant element on the earth crust, following oxygen, which plays a significant role in development and promote plant growth. Extensive efforts have been made to explore the advantages of Si supplementation in fruit crops. The application of Si to plants reinforces the cell wall, providing additional support through enhancing a mechanical and biochemical processes, thereby improving the stress tolerance capacity of crops. In this review, the molecular and physiological mechanisms that explain the beneficial effects of Si supplementation in horticultural crop species have been discussed. The review describes the role of Si and its transporters in mitigation of abiotic stress conditions in horticultural plants.

Aquaporins alteration revealed kidney damages in cerebral ischemia/reperfusion rats.

Background: Restoration of blood supply is a desired goal for the treatment of acute ischemic stroke. However, the restoration often leads to cerebral ischemia-reperfusion injury (CIR/I), which greatly increases the risk of non-neural organ damage. In particular, the acute kidney injury might be one of the most common complications. Aims: The study aimed to understand the damage occurred and the potential molecular mechanisms. Methods: The study was explored on the CIR/I rats generated by performing middle cerebral artery occlusion/reperfusion (MCAO/Reperfusion). The rats were evaluated with injury on the brains, followed by the non-neural organs including kidneys, livers, colons and stomachs. They were examined further with histopathological changes, and gene expression alterations by using RT-qPCR of ten aquaporins (Aqps) subtypes including Aqp1～Aqp9 and Aqp11. Furthermore, the Aqps expression profiles were constructed for each organ and analyzed by performing Principle Component Analysis. In addition, immunohistochemistry was explored to look at the protein expression of Aqp1, Aqp2, Aqp3 and Aqp4 in the rat kidneys. Results: There was a prominent down-regulation profile in the MCAO/Reperfusion rat kidneys. The protein expression of Aqp1, Aqp2, Aqp3 and Aqp4 was decreased in the kidneys of the MCAO/Reperfusion rats. We suggested that the kidney was in the highest risk to be damaged following the CIR/I. Down-regulation of Aqp2, Aqp3 and Aqp4 was involved in the acute kidney injury induced by the CIR/I.

Water channels in the brain and spinal cord-overview of the role of aquaporins in traumatic brain injury and traumatic spinal cord injury.

Knowledge about the mechanisms underlying the fluid flow in the brain and spinal cord is essential for discovering the mechanisms implicated in the pathophysiology of central nervous system diseases. During recent years, research has highlighted the complexity of the fluid flow movement in the brain through a glymphatic system and a lymphatic network. Less is known about these pathways in the spinal cord. An important aspect of fluid flow movement through the glymphatic pathway is the role of water channels, especially aquaporin 1 and 4. This review provides an overview of the role of these aquaporins in brain and spinal cord, and give a short introduction to the fluid flow in brain and spinal cord during in the healthy brain and spinal cord as well as during traumatic brain and spinal cord injury. Finally, this review gives an overview of the current knowledge about the role of aquaporins in traumatic brain and spinal cord injury, highlighting some of the complexities and knowledge gaps in the field.

Study on regulating AQP1, AQP3, AQP4, 5-HT, NOS1 in slow transit constipation rats by Liqi Tongbian mixture.

BACKGROUND: Liqi Tongbian is a traditional Chinese medicine (TCM) preparation that contains herbs that may treat slow transit constipation (STC). Atractylodes macrocephala, Astragalus membranaceus, Fructus aurantii, radish seed, uncooked Polygonum multiflorum, and Agastache rugosa were included in the formula for their unique qualities. The control of water transfer in the colon is greatly influenced by aquaporin 3 (AQP3). OBJECTIVES: Based on this, the Liqi Tongbian mixture was used to detect the concentrations of aquaporins (AQPs), 5-HT and nitrix oxide synthase 1 (NOS1) in STC rats, and explore its effect, in order to provide a theoretical basis for the remedy of STC with TCM. MATERIAL AND METHODS: Zhejiang University of Traditional Chinese Medicine provided 32 three-week-old Sprague Dawley rats of SPF-grade. The pairs licensed under SYXK (Zhejiang) 2021-0012 were kept at 20-25°C and humidity of 50-65%. The compound diphenoxylate caused constipation in the control, model, Liqi laxative (LQTB), and mosapride groups. The Liqi laxative rats were administered a mixture of traditional Chinese herbs after modeling, while mosapride was given to the other group. The levels of 5-HT, NOS1 and AQPs were tested in the feces and intestinal tissues. RESULTS: Comparing the condition of rat feces, it was found that the model group had significantly lower overall bulk, score and particles within 24 h compared to the control group. In comparison to mosapride, LQTB performed better. The model group had higher levels of 5-HT and NOS1 in intestinal tissue, while the LQTB and mosapride groups had decreased levels of these AQPs. LQTB had lower levels of AQP1, AQP3 and AQP4 than mosapride, while the model group had higher levels of these AQPs. CONCLUSIONS: Liqi Tongbian mixture works better than mosapride in improving constipation symptoms in rats with STC, and its mechanism is related to regulating the level of intestinal AQPs and neurotransmitters.

Tobacco aquaporin NtAQP1 and human aquaporin hAQP1 contribute to single cell photosynthesis in Synechococcus.

BACKGROUND INFORMATION: Aquaporins are H2O-permeable membrane protein pores. However, some aquaporins are also permeable to other substances such as CO2. In higher plants, overexpression of such aquaporins has already led to an enhanced photosynthetic performance due to improved CO2 mesophyll conductance. In this work, we investigated the effects of such aquaporins on unicellular photosynthetically active organisms, specifically cyanobacteria. RESULTS: Overexpression of aquaporins NtAQP1 or hAQP1 that might have a function to improve CO2 membrane permeability lead to increased photosynthesis rates in the cyanobacterium Synechococcus sp. PCC7002 as concluded by the rate of evolved O2. A shift in the Plastoquinone pool state of the cells supports our findings. Water permeable aquaporins without CO2 permeability, such as NtPIP2;1, do not have this effect. CONCLUSIONS AND SIGNIFICANCE: We conclude that also in single cell organisms like cyanobacteria, membrane CO2 conductivity could be rate limiting and CO2-porins reduce the respective membrane resistance. We could show that besides the tobacco aquaporin NtAQP1 also the human hAQP1 most likely functions as CO2 diffusion facilitator in the photosynthesis assay.

Overexpression of OsTIP1;2 confers arsenite tolerance in rice and reduces root-to-shoot translocation of arsenic.

Tonoplast Intrinsic Proteins (TIPs) are vital in transporting water and solutes across vacuolar membrane. The role of TIPs in the arsenic stress response is largely undefined. Rice shows sensitivity to the arsenite [As[III]] stress and its accumulation at high concentrations in grains poses severe health hazards. In this study, functional characterization of OsTIP1;2 from Oryza sativa indica cultivar Pusa Basmati-1 (PB-1) was done under the As[III] stress. Overexpression of OsTIP1;2 in PB-1 rice conferred tolerance to As[III] treatment measured in terms of enhanced shoot growth, biomass, and shoot/root ratio of overexpression (OE) lines compared to the wild-type (WT) plants. Moreover, seed priming with the IRW100 yeast cells (deficient in vacuolar membrane As[III] transporter YCF1) expressing OsTIP1;2 further increased As[III] stress tolerance of both WT and OE plants. The dithizone assay showed that WT plants accumulated high arsenic in shoots, while OE lines accumulated more arsenic in roots than shoots thereby limiting the translocation of arsenic to shoot. The activity of enzymatic and non-enzymatic antioxidants also increased in the OE lines on exposure to As[III]. The tissue-specific localization showed OsTIP1;2 promoter activity in root and root hairs, indicating its possible root-specific function. After As[III] treatment in hydroponic medium, the arsenic translocation factor (TF) for WT was around 0.8, while that of OE lines was around 0.2. Moreover, the arsenic content in the grains of OE lines reduced significantly compared to WT plants.