BACKGROUND & AIMS: :Water is the major component of all living cells, and efficient regulation of water homeostasis is essential for many biological processes. The mechanism by which water passes through biological membranes was a matter of debate until the discovery of the aquaporin water channels. Aquaporins are intrinsic membrane proteins characterized by six transmembrane helices that selectively allow water or other small uncharged molecules to pass along the osmotic gradient. In addition, recent observations show that some aquaporins also facilitate the transport of volatile substances, such as carbon dioxide (CO2) and ammonia (NH3), across membranes. Aquaporins usually form tetramers, with each monomer defining a single pore. Aquaporin-related proteins are found in all organisms, from archaea to mammals. In both uni- and multicellular organisms, numerous isoforms have been identified that are differentially expressed and modified by post-translational processes, thus allowing fine-tuned tissue-specific osmoregulation. In mammals, aquaporins are involved in multiple physiological processes, including kidney and salivary gland function. They are associated with several clinical disorders, such as kidney dysfunction, loss of vision and brain edema.

背景与目标： : 水是所有活细胞的主要组成部分，有效调节水的稳态对于许多生物过程至关重要。在发现水通道之前，水通过生物膜的机制一直是一个争论的问题。水通道蛋白是固有的膜蛋白，其特征是六个跨膜螺旋，选择性地允许水或其他不带电的小分子沿着渗透梯度通过。此外，最近的观察表明，一些水通道蛋白还促进了挥发性物质 (例如二氧化碳 (CO2) 和氨 (NH3)) 跨膜的运输。水通道蛋白通常形成四聚体，每个单体定义一个孔。在从古细菌到哺乳动物的所有生物中都发现了与水通道蛋白相关的蛋白质。在单细胞和多细胞生物中，已经鉴定出许多同工型，这些同工型通过翻译后过程进行差异表达和修饰，从而可以进行微调的组织特异性渗透调节。在哺乳动物中，水通道蛋白参与多种生理过程，包括肾脏和唾液腺功能。它们与几种临床疾病有关，例如肾功能不全，视力丧失和脑水肿。

BACKGROUND & AIMS: :Interactions of membrane proteins with lipid molecules are central to their stability and function. We have used multiscale molecular dynamics simulations to determine the extent to which interactions with lipids are conserved across the aquaporin (Aqp) family of membrane proteins. Simulation-based assessment of the lipid interactions made by Aqps when embedded within a simple phospholipid bilayer agrees well with the protein-lipid contacts determined by electron diffraction from 2D crystals. Extending this simulation-based analysis to all Aqps of known structure reveals a degree of conservation of such interactions across the Aqp structural proteome. Despite similarities in the binding orientations and interactions of the lipids, there do not appear to be distinct, high-specificity lipid binding sites on the surface of Aqps. Rather Aqps exhibit a more broadly conserved protein/lipid interface, suggestive of interchange between annular and bulk lipids, instead of a fixed annular "shell" of lipids.

背景与目标： : 膜蛋白与脂质分子的相互作用是其稳定性和功能的核心。我们已经使用多尺度分子动力学模拟来确定在整个膜蛋白的水通道蛋白 (Aqp) 家族中与脂质的相互作用的保守程度。当Aqps嵌入简单的磷脂双分子层中时，基于模拟的脂质相互作用评估与通过2D晶体的电子衍射确定的蛋白质-脂质接触非常吻合。将这种基于模拟的分析扩展到所有已知结构的Aqp，揭示了整个Aqp结构蛋白质组之间这种相互作用的守恒程度。尽管脂质的结合方向和相互作用相似，但Aqps表面似乎没有明显的高特异性脂质结合位点。相反，aqp表现出更广泛保守的蛋白质/脂质界面，提示环形脂质和大块脂质之间存在互换，而不是固定的环形脂质 “壳”。

BACKGROUND & AIMS: :Aquaporin 0 (AQP0) and AQP1 are expressed in the lens, each in a different cell type, and their functional roles are not thoroughly understood. Our previous study showed that these two AQPs function as water transporters. In order to further understand the functional significance of these two different aquaporins in the lens, we investigated their initiation and continued expression. AQP0 transcript and protein were first detected at embryonic stage (E) 11.25 in the differentiating primary fiber cells of the developing lens; its synthesis continued through the adult stage in the secondary fiber cells. Low levels of AQP1 expression were first seen in lens anterior epithelial cells at E17.5; following postnatal day (P) 6.5, the expression gradually progressed towards the equatorial epithelial cells. In the postnatal lens, the increase in membrane water permeability of epithelial cells and lens transparency coincides with the increase in AQP1 expression. AQP1 expression reaches its peak at P30 and continues through the adult stage both in the anterior and equatorial epithelial cells. The enhancement in AQP1 expression concomitant with the increase in the size of the lens suggests the progression in the establishment of the lens microcirculatory system. In vitro and in vivo studies show that both aquaporins share at least one important function, which is water transport in the lens microcirculatory system. However, the temporal expression of these two AQPs suggests an apparently unique role/s in lens development and transparency. To our knowledge, this is the first report on the expression patterns of AQP0 and AQP1 during lens development and differentiation and their relation to lens transparency.

背景与目标： : 水通道蛋白0 (AQP0) 和AQP1在晶状体中表达，每种细胞类型不同，其功能作用尚未完全了解。我们先前的研究表明，这两种aqp充当水转运蛋白。为了进一步了解这两种不同水通道蛋白在晶状体中的功能意义，我们研究了它们的起始和持续表达。首先在胚胎期 (E) 11.25在发育中的晶状体的分化原代纤维细胞中检测到AQP0转录物和蛋白质; 其合成在次级纤维细胞中持续到成年阶段。在E17.5时，首先在晶状体前上皮细胞中观察到低水平的AQP1表达; 出生后第 (P) 6.5天，表达逐渐向赤道上皮细胞发展。在产后晶状体中，上皮细胞的膜水通透性和晶状体透明度的增加与AQP1表达的增加相吻合。AQP1的表达在P30达到峰值，并在前上皮细胞和赤道上皮细胞中持续到成年阶段。AQP1表达的增强伴随着晶状体大小的增加，表明建立晶状体微循环系统的过程。体外和体内研究表明，两种水通道蛋白至少具有一个重要功能，即晶状体微循环系统中的水运输。但是，这两个aqp的时间表达表明在晶状体发育和透明度中显然具有独特的作用。据我们所知，这是有关AQP0和AQP1在晶状体发育和分化过程中的表达模式及其与晶状体透明度的关系的第一份报告。

BACKGROUND & AIMS: :Using primers against highly conserved regions of mammalian and bird aquaporins in RT-PCR experiments, we amplified products derived from duck (Anas platyrhynchos) nasal gland RNA that were identified as homologues of mammalian and chicken aquaporin 1 and aquaporin 5 cDNAs by sequencing. Using digoxigenin-labelled probes derived from these PCR products in northern blot analyses of mRNA isolated from nasal glands of untreated (naïve) or osmotically stressed ducklings (replacement of drinking water with a 1% NaCl solution), we observed a decrease in aquaporin 1 (AQP1) and aquaporin 5 (AQP5) mRNA abundance (by approximately 40%) during saline adaptation in the animals. Western blot analysis of AQP1 and AQP5 expression in the glands revealed that protein abundance decreased in a similar fashion. Immunohistochemical analysis of AQP1 distribution in cryosections of nasal gland indicated that AQP1 is mainly expressed in endothelial cells of the capillaries, but definitely not in the secretory or ductal cells of the gland. AQP5 distribution in the gland, however, seems to be different, since staining was exclusively observed in apical and basolateral plasma membranes of individual epithelial cells of the primary and central ducts, which collect fluid from the secretory tubules. The observations are consistent with the hypothesis that strongly hyperosmotic fluid is produced by the secretory cells at very low (unstimulated gland) or high (activated gland) rates. In the unstimulated gland, secretions may be diluted by aquaporin-mediated transcellular water flux while passing through the ductal system flushing the glandular ducts, thereby potentially preventing ascending infections. In the activated gland, however, downregulation of aquaporins in capillaries and duct cells may prevent dilution of the initially secreted fluid, enabling the animals to excrete large volumes of a highly concentrated salt solution.

背景与目标： : 在rt-pcr实验中，使用针对哺乳动物和鸟类水通道蛋白高度保守的区域的引物，我们扩增了源自鸭 (Anas platyrhynchos) 鼻腺RNA的产物，这些产物被鉴定为哺乳动物和鸡水通道蛋白1和水通道蛋白5 cdna的同源物。在northern印迹分析中使用源自这些PCR产物的洋地黄毒苷标记的探针，对从未经处理 (幼稚) 或渗透胁迫的小鸭 (用1% NaCl溶液代替饮用水) 的鼻腺中分离的mRNA进行分析，我们观察到在动物的生理盐水适应过程中水通道蛋白1 (AQP1) 和水通道蛋白5 (AQP5) mRNA丰度降低 (约40%)。腺体中AQP1和AQP5表达的蛋白质印迹分析显示，蛋白质丰度以类似的方式降低。对AQP1在鼻腺冷冻切片中分布的免疫组织化学分析表明，AQP1主要在毛细血管的内皮细胞中表达，但绝对不在腺体的分泌或导管细胞中表达。然而，腺体中的AQP5分布似乎有所不同，因为仅在初级和中央导管的单个上皮细胞的顶端和基底外侧质膜中观察到染色，这些上皮细胞从分泌小管中收集液体。观察结果与以下假设一致: 分泌细胞以非常低 (未刺激的腺体) 或高 (激活的腺体) 速率产生强烈的高渗液。在未刺激的腺体中，分泌物可以通过水通道蛋白介导的跨细胞水通量稀释，同时通过冲洗腺管的导管系统，从而有可能防止上升的感染。然而，在活化的腺体中，毛细血管和导管细胞中水通道蛋白的下调可能会阻止最初分泌的液体的稀释，从而使动物能够排泄大量高浓度的盐溶液。

BACKGROUND & AIMS: :Inflammation is a universal response mechanism existing as inter-communicator of biological systems. Uncontrolled or dysregulated inflammation addresses chronic low-grade effects eventually resulting in multimorbidity. Active solute transport across the membrane establishes varying osmotic gradients. Aquaporins (AQPs) are a class of critical ubiquitously expressed transmembrane proteins that aid in fluid and small solute transport via facilitated diffusion over established osmotic gradients. Numerous significant data features the biological functions of AQPs rendering them as an appropriate biomarker of health and diseases. Besides their physiological role in well-balanced inflammatory responses, it is worth noting the dysregulation of AQPs during any undesirable inflammatory event. Most literature to date clearly sets out AQPs as potential drug targets instigating AQP-based therapies. In light of this conception, the current review provides a compendious overview on the propitious and portentous out-turns of AQPs under inflammation.

背景与目标： : 炎症是一种普遍的反应机制，作为生物系统的相互交流者而存在。不受控制或失调的炎症可解决慢性低度效应，最终导致多发病。跨膜的主动溶质转运建立了不同的渗透梯度。水通道蛋白 (AQPs) 是一类关键的普遍表达的跨膜蛋白，可通过在已建立的渗透梯度上促进扩散来帮助流体和小溶质转运。大量重要数据具有AQPs的生物学功能，使其成为健康和疾病的适当生物标志物。除了它们在平衡良好的炎症反应中的生理作用外，值得注意的是在任何不良炎症事件中AQPs的失调。迄今为止，大多数文献都清楚地将AQPs列为潜在的药物靶标，以促进基于AQP的疗法。鉴于这一概念，本综述对炎症下aqp的有利和有利的结果进行了简要概述。

BACKGROUND & AIMS: :AQY1 and AQY2 were sequenced from five commercial and five native wine yeasts. Of these, two AQY1 alleles from UCD 522 and UCD 932 were identified that encoded three or four amino-acid changes, respectively, compared with the Sigma1278b sequence. Oocytes expressing these AQY1 alleles individually exhibited increased water permeability vs. water-injected oocytes, whereas oocytes expressing the AQY2 allele from UCD 932 did not show an increase, as expected, owing to an 11 bp deletion. Wine strains lacking Aqy1p did not show a decrease in spore fitness or enological aptitude under stressful conditions, limited nitrogen, or increased temperature. The exact role of aquaporins in wine yeasts remains unclear.

背景与目标： : AQY1和AQY2是从五个商业和五个本地葡萄酒酵母中测序的。其中，与Sigma1278b序列相比，鉴定了来自UCD 522和UCD 932的两个AQY1等位基因，它们分别编码三个或四个氨基酸变化。与水注射的卵母细胞相比，表达这些AQY1等位基因的卵母细胞单独表现出增加的水渗透性，而表达来自UCD 932的AQY2等位基因的卵母细胞没有如预期的那样显示出增加，这是由于11 bp缺失。缺乏Aqy1p的葡萄酒菌株在压力条件，有限的氮或温度升高的条件下，孢子适应性或生理能力并未降低。水通道蛋白在葡萄酒酵母中的确切作用仍不清楚。

BACKGROUND & AIMS: :Gastric cancer (GC) is a common disease with few effective treatment choices and poor prognosis, and has the second-highest mortality rates among all cancers worldwide. Dysregulation and/or malfunction of ion channels or aquaporins (AQPs) are common in various human cancers. Furthermore, ion channels are involved in numerous important aspects of the tumor aggressive phonotype, such as proliferation, cell cycle, apoptosis, motility, migration, and invasion. Indeed, by localizing in the plasma membrane, ion channels or AQPs can sense and respond to extracellular environment changes; thus, they play a crucial role in cell signaling and cancer progression. These findings have expanded a new area of pharmaceutical exploration for various types of cancer, including GC. The involvement of multiple ion channels, such as voltage-gated potassium and sodium channels, intracellular chloride channels, 'transient receptor potential' channels, and AQPs, which have been shown to facilitate the pathogenesis of other tumors, also plays a role in GC. In this review, an overview of ion channel and aquaporin expression and function in carcinogenesis of GC is presented. Studies of ion channels or AQPs will advance our understanding of the molecular genesis of GC and may identify novel and effective targets for the clinical application of GC.

背景与目标： 胃癌 (GC) 是一种常见疾病，有效的治疗选择少，预后差，在全球所有癌症中死亡率第二高。离子通道或水通道蛋白 (aqp) 的失调和/或故障在各种人类癌症中很常见。此外，离子通道参与肿瘤侵袭性声子类型的许多重要方面，例如增殖，细胞周期，凋亡，运动，迁移和侵袭。实际上，通过定位在质膜中，离子通道或aqp可以感知并响应细胞外环境的变化; 因此，它们在细胞信号传导和癌症进展中起着至关重要的作用。这些发现为包括GC在内的各种类型的癌症拓展了一个新的药物探索领域。多种离子通道的参与，例如电压门控钾和钠通道，细胞内氯离子通道，“瞬时受体电位” 通道和AQPs，已被证明可以促进其他肿瘤的发病，也在GC中起作用。本文综述了离子通道、水通道蛋白在GC癌变中的表达和功能。离子通道或AQPs的研究将促进我们对GC分子成因的理解，并可能为GC的临床应用确定新的有效靶标。

BACKGROUND & AIMS: :Aquaporins, major intrinsic proteins (MIPs) present in the plasma and intracellular membranes, facilitate the transport of small neutral molecules across cell membranes in higher plants. Recently, progress has been made in understanding the mechanisms of aquaporin subcellular localization, transport selectivity, and gating properties. Although the role of aquaporins in maintaining the plant water status has been addressed, the interactions between plant aquaporins and mineral nutrients remain largely unknown. This review highlights the roles of various aquaporin orthologues in mineral nutrient uptake and transport, as well as the regulatory effects of mineral nutrients on aquaporin expression and activity, and an integrated link between aquaporins and mineral nutrient metabolism was identified.

背景与目标： 水通道蛋白，存在于血浆和细胞内膜中的主要内在蛋白 (MIPs)，促进高等植物中小中性分子跨细胞膜的运输。最近，在了解水通道蛋白亚细胞定位，转运选择性和门控特性的机制方面取得了进展。尽管已经解决了水通道蛋白在维持植物水分状态中的作用，但植物水通道蛋白与矿物质营养素之间的相互作用仍然未知。本文重点介绍了各种水通道蛋白直系同源物在矿物质营养吸收和运输中的作用，以及矿物质营养对水通道蛋白表达和活性的调节作用，并确定了水通道蛋白与矿物质营养代谢之间的综合联系。

BACKGROUND & AIMS: PURPOSE/AIM:The development of retinal edema is the main reason of impaired vision in non-proliferative diabetic retinopathy. Water transport through aquaporins (AQPs) has been suggested to facilitate the development of ischemic edema in the retina. Here, we investigated whether experimental diabetic retinopathy in rats results in alterations of the AQP expression in the neural retina and retinal pigment epithelium (RPE). MATERIALS AND METHODS:Experimental diabetes in rats was induced by a single intravenous injection of streptozotocin (65 mg/kg body weight). The gene expression of AQPs in tissues from control and diabetic rats was examined by real-time RT-PCR. Retinal cryosections were immunostained against AQP5, 6, and 9. RESULTS:The total RNAs extracted from the neural retina and RPE contained gene transcripts for AQP0, 1, 3, 4, 5, 6, 8, 9, 11, and 12. Experimental diabetes was associated with an upregulation of AQP1 in the neural retina, and of AQP5, 9, 11, and 12 in the RPE. Furthermore, diabetes was associated with a downregulation of AQP6 and AQP11 in the neural retina, and of AQP0 in the RPE. AQP5 and AQP9 immunolabelings of the RPE were increased, and AQP6 labeling of the outer plexiform layer was decreased in retinal slices from diabetic rats in comparison to slices from control rats. CONCLUSIONS:The data suggest that experimental diabetic retinopathy is associated with a complex pattern of alteration in the retinal AQP expression. These alterations might be involved in the adaptation of retinal cells to hyperglycemic conditions and the development and/or resolution of retinal edema.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:To study the expression pattern, localisation and potential clinical significance of aquaporin water channels (AQP) both in prostate cancer (PC) cell lines and in benign and malignant human prostate tissue. METHODS:The AQP transcript and protein expression of HPrEC, LNCaP, DU-145 and PC3 cell lines was investigated using reverse transcriptase polymerase chain reaction (RT-PCR) and immunofluorescence (IF) microscopy labelling. Immunohistochemistry (IHC) was performed to assess AQP protein expression in surgical specimens of benign prostatic hyperplasia as well as in PC. Tissue mRNA expression of AQPs was quantified by single-step reverse transcriptase quantitative polymerase chain reaction (qPCR). Relative gene expression was determined using the 40-ΔCT method and correlated to clinicopathological parameters. RESULTS:Transcripts of AQP 1, 3, 4, 7, 8, 10 and 11 were expressed in all four cell lines, while AQP 9 transcripts were not detected in malignant cell lines. IF microscopy confirmed AQP 3, 4, 5, 7 and 9 protein expression. IHC revealed highly heterogeneous AQP 3 protein expression in PC specimens, with a marked decrease in expression in tumours of increasing malignancy. Loss of AQP 9 was shown in PC specimens. mRNA expression of AQP3 was found to be negatively correlated to PSA levels (ρ = - 0.354; p = 0.013), D'Amico risk stratification (ρ = - 0.336; p = 0.012), ISUP grade (ρ = - 0.321; p = 0.017) and Gleason score (ρ = - 0.342; p = 0.011). CONCLUSIONS:This is the first study to systematically characterize human prostate cell lines, benign prostatic hyperplasia and PC in relation to all 13 members of the AQP family. Our results indicate the differential expression of several AQPs in benign and malignant prostate tissue. A significant correlation was observed between AQP 3 expression and tumour grade, with progressive loss in more malignant tumours. Taken together, AQPs may play a role in the progression of PC and AQP expression patterns may serve as a prognostic marker.

背景与目标：

BACKGROUND & AIMS: :This article reviews bone adaptation to microgravity, during manned space missions, in humans undergoing Head Down Tilt (HDT) and in Hind-Limb-Suspended Rats. Under microgravity conditions, bone loss occurs in association with hypercalciuria, which in turn modulates Aquaporin 2 (AQP2) excretion in urine, thus avoiding stone forming in space. This report discloses the need to prevent bone loss in order to prepare for long stays at lunar bases or voyages to Mars.

背景与目标： : 本文回顾了载人航天任务期间，经历头朝下倾斜 (HDT) 的人类和后肢悬吊大鼠的骨骼对微重力的适应。在微重力条件下，骨质流失与高钙尿症相关，从而调节尿液中水通道蛋白2 (AQP2) 的排泄，从而避免在太空中形成结石。该报告披露了防止骨质流失的必要性，以便为长期停留在月球基地或前往火星的航行做准备。

BACKGROUND & AIMS: :The membrane phosphoproteome in plant seed changes dynamically during embryo development. We examined the patterns of Phaseolus vulgaris (common bean) seed membrane protein phosphorylation from the mid-maturation stage until two days after germination. Serine and threonine phosphorylation declined during seed maturation while tyrosine phosphorylation remained relatively constant. We discovered that the aquaporin PvTIP3;1 is the primary seed membrane phosphoprotein, and PvTIP3;2 shows a very low level of expression. The level of phosphorylated Ser7 in PvTIP3;1 increased four-fold after seed maturation. Since phosphorylation increases water channel activity, we infer that water transport by PvTIP3;1 is highest in dry and germinating seeds, which would be optimal for seed imbibition. By the use of isoform-specific, polyclonal peptide antibodies, we found that PvTIP3;2 is expressed in a developmental pattern similar to PvTIP3;1. Unexpectedly, PvTIP3;2 is tyrosine phosphorylated following seed maturation, which may suggest a mechanism for the regulation of PvTIP3;2 following seed germination. Analysis of protein secondary structure by circular dichroism spectroscopy indicated that the amino-terminal domain of PvTIP3;1 is generally unstructured, and phosphorylation increases polyproline II (PPII) helical structure. The carboxy-terminal domain also gains PPII character, but in a pH-dependent manner. These structural changes are a first step to understand TIP3 aquaporin regulation.

背景与目标： : 植物种子中的膜磷酸蛋白质组在胚胎发育过程中动态变化。我们检查了从成熟中期到发芽后两天的菜豆 (普通豆) 种子膜蛋白磷酸化的模式。种子成熟过程中丝氨酸和苏氨酸磷酸化下降，而酪氨酸磷酸化保持相对恒定。我们发现水通道蛋白PvTIP3;1是主要的种子膜磷蛋白，而PvTIP3;2显示出非常低的表达水平。PvTIP3中磷酸化Ser7的水平; 1在种子成熟后增加了四倍。由于磷酸化增加了水通道的活性，因此我们推断PvTIP3;1在干燥和发芽的种子中最高，这对于种子吸收是最佳的。通过使用同工型特异性的多克隆肽抗体，我们发现PvTIP3;2以类似于PvTIP3的发育模式表达; 1。出乎意料的是，PvTIP3;2在种子成熟后被酪氨酸磷酸化，这可能暗示了调节PvTIP3的机制; 2在种子发芽后。通过圆二色光谱对蛋白质二级结构的分析表明，PvTIP3;1的氨基末端结构域通常是非结构化的，并且磷酸化会增加polyproline II (PPII) 螺旋结构。羧基末端结构域也具有PPII特性，但具有pH依赖性。这些结构变化是了解TIP3水通道蛋白调控的第一步。

BACKGROUND & AIMS: PURPOSE/AIM:To determine the transcriptional regulation of retinal aquaporins (AQPs) in rat models of transient and permanent retinal ischemia, and to prove the effects of chemical hypoxia, oxidative stress, glucose, and osmotic alterations on the expression of AQP9 in cultured human retinal pigment epithelium (RPE) cells. MATERIALS AND METHODS:Transient retinal ischemia-reperfusion in rats was induced by elevation of the intraocular pressure for 1 hour. Permanent retinal ischemia was induced by argon laser-induced retinal vein occlusion. The mRNA levels were determined one day after ischemia. RESULTS:Transient and permanent ischemia of the rat retina resulted in downregulation of AQPs 1, 3, 4, 5, 6, 8, and 11 in the RPE and/or neural retina. Pressure-induced transient retinal ischemia-induced upregulation of AQP9 in the neuroretina and RPE, and of AQ12 in the neuroretina. Retinal vein occlusion induced upregulation of AQP0 in the neuroretina and RPE, and of AQP9 and AQP12 in the neuroretina. In cultured human RPE cells, transcriptional expression of AQP9 was stimulated by chemical hypoxia, oxidative stress, VEGF, and high glucose. CONCLUSIONS:The data may suggest that the expression of retinal AQP9 is regulated by metabolic and oxidative stress. Upregulation of AQP9 in RPE cells may prevent lactic acidosis and subretinal edema under ischemic and oxidative stress conditions.

背景与目标：

BACKGROUND & AIMS: :The arbuscular mycorrhizal (AM) symbiosis has been shown to modulate the same physiological processes as the phytohormone abscisic acid (ABA) and to improve plant tolerance to water deficit. The aim of the present research was to evaluate the combined influence of AM symbiosis and exogenous ABA application on plant root hydraulic properties and on plasma-membrane intrinsic proteins (PIP) aquaporin gene expression and protein accumulation after both a drought and a recovery period. Results obtained showed that the application of exogenous ABA enhanced osmotic root hydraulic conductivity (L) in all plants, regardless of water conditions, and that AM plants showed lower L values than nonAM plants, a difference that was especially accentuated when plants were supplied with exogenous ABA. This effect was clearly correlated with the accumulation pattern of the different PIPs analyzed, since most showed reduced expression and protein levels in AM plants fed with ABA as compared to their nonAM counterparts. The possible involvement of plant PIP aquaporins in the differential regulation of L by ABA in AM and nonAM plants is further discussed.

背景与目标： : 丛枝菌根 (AM) 共生已被证明可以调节与植物激素脱落酸 (ABA) 相同的生理过程，并提高植物对缺水的耐受性。本研究的目的是评估干旱和恢复期后AM共生和外源ABA施用对植物根系水力特性以及质膜内在蛋白 (PIP) 水通道蛋白基因表达和蛋白质积累的综合影响。获得的结果表明，无论水分条件如何，外源ABA的施用均提高了所有植物的渗透根水力传导率 (L)，并且AM植物的L值低于nonAM植物，当向植物供应外源ABA时，这种差异尤其突出。这种效果与所分析的不同pip的积累模式明显相关，因为与nonAM对应物相比，大多数在饲喂ABA的AM植物中显示出降低的表达和蛋白质水平。进一步讨论了植物PIP水通道蛋白可能参与AM和nonAM植物中ABA对L的差异调节。

BACKGROUND & AIMS: :We compared the diffusion conductance to CO2 from the intercellular air space to the chloroplasts (internal conductance (g i)) between tobacco leaves acclimated to long-term drought (drought-acclimated (DA)) and those grown under sufficient irrigation (well-watered (WW)), and analysed the changes in g i in relation to the leaf anatomical characteristics and a possible CO2 transporter, aquaporin. The g i, which was estimated by combined analyses of CO2 gas exchange with chlorophyll fluorescence, in the DA plants was approximately half of that in the WW plants. The mesophyll and chloroplast surface areas exposing the intercellular air space, which potentially affect g i, were not significantly different between the WW and DA plants. The amounts of plasma membrane aquaporins (PIP), immunochemically determined using radish PIP antibodies, were unrelated to g i. After treatment with HgCl2, an aquaporin inhibitor, the water permeability of the leaf tissues (measured as the weight loss of fully-turgid leaf disks without the abaxial epidermis in 1 m sorbitol) in WW plants decreased with an increase in HgCl2 concentration. The g i in the WW plants decreased to similar levels to the DA plants when the detached leaflets were fed with 0.5 mm HgCl2. In contrast, both water permeability and g i were insensitive to HgCl2 treatments in DA plants. These results suggest that deactivation of aquaporins is responsible for the significant reduction in g i observed in plants growing under long-term drought.

背景与目标： : 我们比较了适应长期干旱 (干旱适应 (DA)) 的烟叶与在充足灌溉下生长的烟叶之间从细胞间空气空间到叶绿体 (内部电导 (g i)) 的CO2扩散电导 (WW))，并分析了g i与叶片解剖特征和可能的CO2转运蛋白水通道蛋白的关系。通过对DA植物中的CO2气体交换与叶绿素荧光的结合分析估算的g i大约是WW植物中的一半。暴露于细胞间空气空间的叶肉和叶绿体表面积可能会影响g i，在WW和DA植物之间没有显着差异。使用萝卜PIP抗体免疫化学测定的质膜水通道蛋白 (PIP) 的量与g i无关。用水通道蛋白抑制剂HgCl2处理后，随着HgCl2浓度的增加，WW植物叶片组织的透水性 (以1  m山梨糖醇中没有背面表皮的完全膨化的叶盘的重量损失来衡量) 降低。当分离的小叶饲喂0.5  mm hgcl2时，WW植物中的g i降低到与DA植物相似的水平。相反，透水性和g i对DA植物中的HgCl2处理均不敏感。这些结果表明，在长期干旱下生长的植物中，水通道蛋白的失活是导致g i显着降低的原因。