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Sheng Chen

Publications and source records attributed to Sheng Chen.

At least 19 recordsLinked to original sources
PubMed2026

"One Health"-based epidemiological investigation reveals the emergence of carbapenem-resistant Morganella spp. across diverse ecological niches.

OBJECTIVES: To investigate the prevalence, genomic relatedness, and resistance characteristics of carbapenemase-gene-positive Morganella spp. (CRM) across human, animal, fly, and aquatic sources. METHODS: A total of 163 Morganella isolates were collected from humans (n=124), animals (n=5), flies (n=21), aquatic environment (n=13) across 13 provinces or municipalities during 2018-2024. A subset of 71 representative isolates was subjected to antimicrobial susceptibility testing (AST), whole-genome sequencing and conjugation experiments. RESULTS: Among 163 isolates, 18 were carbapenemase-gene-positive: 15 carried blaNDM-1 alone, two carried blaKPC-2 alone, and one carried both genes. They were recovered from humans, flies, and hospital sewage. Five isolates carried blaPER-4; four carbapenemase-negative carriers were resistant to both ceftazidime/avibactam and aztreonam/avibactam. The aac(3)-IV gene was associated with high apramycin MICs and was most frequent in animal- and fly-derived isolates. Phylogenetic analysis showed diverse lineages, with limited low-SNP links between human and urban-river isolates. blaNDM-1 was transferred successfully from 11 of 16 donor isolates. CONCLUSION: CRM occur across multiple One Health niches. The findings highlight environmental and non-human reservoirs as potential contributors to their dissemination and identify blaPER-4 and aac(3)-IV as resistance-associated genes requiring further study.

Animal↗
PubMed2026

Desmodium styracifolium Total Flavone Capsules for Urolithiasis: A Phase 3 Randomized Clinical Trial.

IMPORTANCE: No oral medication is currently approved for the management of urolithiasis. Guang Jing Qian Cao (Desmodium styracifolium total flavone capsules; hereinafter, Guang Jing), a traditional Chinese herbal extract, has shown clinical benefits for urolithiasis, but randomized clinical trials are needed to assess its effectiveness. OBJECTIVE: To evaluate whether Guang Jing improves stone passage rates (SPRs) compared with placebo in adults with urolithiasis. DESIGN, SETTING, AND PARTICIPANTS: This double-blind, placebo-controlled, phase 3 randomized clinical trial was conducted at 34 sites in China from December 2017 to April 2020. Participants included adults (aged 18-70 years) with diagnosed ureteral stones. Data analysis was conducted on November 4, 2020. INTERVENTION: Participants were randomized 3:1 to receive oral Guang Jing (0.6 g) or matching placebo 3 times daily for 28 days, in addition to investigator-prescribed background medication. MAIN OUTCOMES AND MEASURES: The primary outcome was SPR by day 28, confirmed by computed tomography. Secondary outcomes included SPR by day 14, stone migration rate, and stone migration distance. Between-group comparisons were performed using the Cochran-Mantel-Haenszel test for categorical outcomes and t tests for continuous outcomes. RESULTS: A total of 606 participants were randomly assigned to receive Guang Jing (n = 458) or placebo (n = 148). Their mean (SD) age was 43.0 (12.0) years, 474 (78.2%) were male, and the mean (SD) stone size was 0.6 (0.1) cm. The SPR by day 28 was significantly higher for the Guang Jing group compared with the placebo group (204 of 457 [44.6%] vs 50 of 148 [33.8%]; relative risk, 1.32 [95% CI, 1.03-1.69]; P = .03), with an absolute risk difference of 10.9 (95% CI, 2.0-19.7) percentage points. No significant between-group differences in SPR by day 14 (Guang Jing vs placebo: 133 [29.1%] vs 33 [22.3%]; P = .14) or stone migration distance (mean [SD], 29.5 [51.8] mm vs 29.7 [43.8] mm; P = .11) were observed. Adverse event rates were similar for the Guang Jing and placebo groups (88 [19.3%] vs 27 [18.2%]). CONCLUSIONS AND RELEVANCE: In this randomized clinical trial, treatment with Guang Jing significantly increased the expulsion of 5- to 10-mm ureteral stones by day 28, with a favorable safety profile. These findings suggest that Guang Jing may be an additional medical expulsive therapy option for appropriately selected patients. TRIAL REGISTRATION: Chinese Clinical Trial Registry Identifier: ChiCTR-IIR-17013275.

Humans↗
PubMed2026

Genome-wide cyclin gene evolution in Arabidopsis and Brassica reveals polyploidization-driven duplication and flowering-time associations.

Cyclin genes are plant cell cycle regulators that play essential roles in growth, development, and reproduction. However, the evolutionary dynamics and genomic organization of cyclin genes across the Brassicaceae family remain poorly understood, particularly in the context of allotetraploid genome evolution. Here, we investigated the diversity, expansion mechanisms, and potential functional diversification of cyclin genes across ten Brassicaceae genomes, including four Arabidopsis and six Brassica species. A total of 1087 cyclin genes representing 23 cyclin types were identified. Comparative genomic analyses revealed that cyclin gene expansion was strongly influenced by polyploidization in Brassica species, with 1845 duplication events involving 1063 genes. Whole-genome duplication was the predominant mechanism driving expansion, while both inter- and intra-genomic duplications contributed to gene retention in tetraploid Brassica species, with the highest duplication frequency observed in Brassica juncea. Across genomes, 120 physical gene clusters were identified, including homogeneous and heterogeneous types. Ortholog analysis between progenitor and allotetraploid species identified 852 orthologous pairs involving 366 genes, indicating extensive conservation following allotetraploid formation. Phylogenetic analysis resolved cyclins into three major clades, while expression-based clustering in Brassica napus grouped genes into four major clusters, suggesting functional diversification. Integration of pan-genomic and flowering-time QTL analyses further identified two cyclin genes, Bna21cycA2 and Bna113cycD4, which contain amino acid polymorphisms and represent putative candidate variations potentially associated with flowering-time variation across multiple genomes. These findings provide new insights into the evolutionary expansion, retention, and potential functional divergence of cyclin genes in Brassicaceae and highlight candidate loci for future functional studies and crop improvement.

Evolution, Molecular↗
PubMed2026

Non-invasive strategy for gastric cancer detection: Integration of cell-free DNA fragmentomics and protein biomarkers.

Gastric cancer (GC) ranks as the fifth most common cancer worldwide, however, accurate and non-invasive diagnostic modalities for GC remain limited. Cell-free DNA (cfDNA) fragmentomics has emerged as a promising tool for cancer cell detection. Here we develop a gastric cancer detection model, named GaFraD model. The GaFraD model uses four cfDNA fragmentomics features, including fragment size ratio (FSR), copy number variation (CNV), 9-bp end motif (Motif), and fragment size at transcription start sites (TF). This model achieves an area under the receiver-operating characteristic curve (AUC) of 0.970 (95% CI: 0.944 - 0.990), a sensitivity of 95.0% and a specificity of 80.9%. By combining the GaFraD model and conventional protein biomarkers CA19-9 and PG-I/PG-II, the CONFIRM model was generated. The CONFIRM model attained an AUC of 0.986 (95% CI: 0.966 - 1.000), a sensitivity of 95.0% and a specificity of 95.6% in detecting GC. Moreover, the CONFIRM model achieved remarkable performance (AUC = 0.983, sensitivity 95.6%, specificity 94.2%) in distinguishing patients with early-stage GC from controls. Our work showed the high discriminatory power in distinguishing GC patients from controls, indicating the clinical potential of using cfDNA fragmentomics combined with protein biomarkers for non-invasive GC detection. The results of the study provide a new avenue for early, accurate, and non-invasive clinical diagnosis of GC.

Cell-free DNA↗
PubMed2026

Genetic mutations within tva receptor gene confer resistance to ALV-A and ALV-K infection in chickens.

Avian leukosis virus subgroup A (ALV-A) and the newly emerging subgroup K (ALV-K) are primary causative pathogens of avian leukosis in chickens and continue to pose a persistent threat to poultry industry worldwide. Susceptibility or resistance of chicken cells to ALV-A and ALV-K is determined by the tva receptor gene. Indeed, six ALV-A resistant alleles (tvar1-tvar6) have been identified within the tva gene. However, whether these tva alleles confer resistance to ALV-K infection remains unclear. In this study, we identified five tva resistant alleles, namely tvar2, tvar3, tvar4, tvar5, and tvar6, in Qingyuan partridge chickens (QYPC). In vitro analyses, including flow cytometry and quantitative real-time PCR, we demonstrated that the tvar2 allele confers complete resistance to both ALV-A and ALV-K infection. In contrast, the tvar3, tvar4, tvar5, and tvar6 alleles each significantly reduced susceptibility to ALV-K. Furthermore, these in vitro observations were corroborated by in vivo infection experiments, which confirmed that the tvar2 allele consistently conferred complete resistance to both ALV-A and ALV-K, while tvar3, tvar4, tvar5, and tvar6 alleles each resulted in a significant reduction in ALV-K susceptibility. Additionally, the tvar2-tvar6 alleles were broadly distributed across QYPC lines, with notably high frequencies of resistant genotypes observed in specific QYPC populations. Collectively, these findings not only expand our understanding of tva-mediated resistance to both ALV-A and ALV-K but also provide valuable genetic targets for selective breeding programs aimed at enhancing resistance to ALV-A and ALV-K in chickens.

ALV-A↗
PubMed2026

Molecular surveillance of foodborne bacterial pathogens and resistome in food products from Hong Kong.

Foodborne infections pose an increasing public health challenge worldwide. The problem has been aggravated by the dissemination of antimicrobial resistance genes among zoonotic pathogens, which results in a sharp increase in antibiotic resistance rate recorded among the major foodborne pathogens. To obtain an overview of the extent to which food products purchased in the markets in Hong Kong were contaminated by foodborne pathogens, we collected 95 raw meat samples from wet markets and isolated 236 bacterial strains of various species, with Escherichia coli being the most dominant species (131 strains). Contamination of food products by multiple foodborne pathogens was commonly observed. These include both Gram-positive and Gram-negative bacteria that exhibit various levels of resistance, with some possessing multiple clinically important antibiotic resistance genes. Seventeen bacterial strains of various species isolated from three food samples were comprehensively analysed by the Oxford Nanopore R10.4 technology. Novel conjugative plasmids carrying antimicrobial resistance gene-bearing mobile genetic elements were commonly detectable in the test strains. Some of the plasmids were shown to have originated from other environmental sources or other bacterial species, indicating that raw foods in the local market may serve as a reservoir of resistance-encoding genetic elements from which such elements are disseminated to various microbial pathogens. These findings suggest a need to perform periodic but comprehensive surveillance of multidrug-resistant bacterial pathogens and the major antimicrobial resistance genes in common food products, so as to disrupt the transmission routes of such organisms and the resistance-encoding genetic elements that they harbour.

Hong Kong↗
PubMed2007

Translocation of constitutively expressed heat shock protein Hsc70 to synapse-enriched areas of the cerebral cortex after hyperthermic stress.

Hsp70 is a multi-gene family composed of stress-inducible members (Hsp70) and other members that are constitutively expressed (Hsc70). The heat shock proteins Hsp70 and Hsc70 exhibit similar molecular structure and biochemical functions. Constitutively expressed Hsc70 is enriched in the mammalian nervous system compared with non-neural tissues and present at high levels in neuronal cell bodies. After thermal stress, Hsc70 is translocated to synapse-enriched areas of the cerebral cortex where it associates with Hsp40 to form a complex that can refold denaturated proteins. These results suggest that the heat shock response in the nervous system involves not only the synthesis of stress-inducible Hsps but also the translocation of constitutively expressed Hsc70 to synapse-enriched areas where it could participate in neuroprotective mechanisms that preserved synaptic function during times of stress.

Animals↗
PubMed2006

Treatment of pesticide wastewater by moving-bed biofilm reactor combined with Fenton-coagulation pretreatment.

In order to treat pesticide wastewater having high chemical oxygen demand (COD) value and poor biodegradability, Fenton-coagulation process was first used to reduce COD and improve biodegradability and then was followed by biological treatment. Optimal experimental conditions for the Fenton process were determined to be Fe(2+) concentration of 40 mmol/L and H(2)O(2) dose of 97 mmol/L at initial pH 3. The interaction mechanism of organophosphorous pesticide and hydroxyl radicals was suggested to be the breakage of the P=S double bond and formation of sulfate ions and various organic intermediates, followed by formation of phosphate and consequent oxidation of intermediates. For the subsequent biological treatment, 3.2g/L Ca(OH)(2) was added to adjust the pH and further coagulate the pollutants. The COD value could be evidently decreased from 33,700 to 9300 mg/L and the ratio of biological oxygen demand (BOD(5)) to COD of the wastewater was enhanced to over 0.47 by Fenton oxidation and coagulation. The pre-treated wastewater was then subjected to biological oxidation by using moving-bed biofilm reactor (MBBR) inside which tube chip type bio-carriers were fluidized upon air bubbling. Higher than 85% of COD removal efficiency could be achieved when the bio-carrier volume fraction was kept more than 20% by feeding the pretreated wastewater containing 3000 mg/L of inlet COD at one day of hydraulic retention time (HRT), but a noticeable decrease in the COD removal efficiency when the carrier volume was decreased down to 10%, only 72% was observed. With the improvement of biodegradability by using Fenton pretreatment, also due to the high concentration of biomass and high biofilm activity using the fluidizing bio-carriers, high removal efficiency and stable operation could be achieved in the biological process even at a high COD loading of 37.5 gCOD/(m(2)carrierday).

Biofilms↗
PubMed2006

Contribution of target gene mutations and efflux to decreased susceptibility of Salmonella enterica serovar typhimurium to fluoroquinolones and other antimicrobials.

The mechanisms involved in fluoroquinolone resistance in Salmonella enterica include target alterations and overexpression of efflux pumps. The present study evaluated the role of known and putative multidrug resistance efflux pumps and mutations in topoisomerase genes among laboratory-selected and naturally occurring fluoroquinolone-resistant Salmonella enterica serovar Typhimurium strains. Strains with ciprofloxacin MICs of 0.25, 4, 32, and 256 microg/ml were derived in vitro using serovar Typhimurium S21. These mutants also showed decreased susceptibility or resistance to many nonfluoroquinolone antimicrobials, including tetracycline, chloramphenicol, and several beta-lactams. The expression of efflux pump genes acrA, acrB, acrE, acrF, emrB, emrD, and mdlB were substantially increased (>or=2-fold) among the fluoroquinolone-resistant mutants. Increased expression was also observed, but to a lesser extent, with three other putative efflux pumps: mdtB (yegN), mdtC (yegO), and emrA among mutants with ciprofloxacin MICs of >or=32 microg/ml. Deletion of acrAB or tolC in S21 and its fluoroquinolone-resistant mutants resulted in increased susceptibility to fluoroquinolones and other tested antimicrobials. In naturally occurring fluoroquinolone-resistant serovar Typhimurium strains, deletion of acrAB or tolC increased fluoroquinolone susceptibility 4-fold, whereas replacement of gyrA double mutations (S83F D87N) with wild-type gyrA increased susceptibility>500-fold. These results indicate that a combination of topoisomerase gene mutations, as well as enhanced antimicrobial efflux, plays a critical role in the development of fluoroquinolone resistance in both laboratory-derived and naturally occurring quinolone-resistant serovar Typhimurium strains.

Animals↗
PubMed2006

Are heat shock proteins therapeutic target for Parkinson's disease?

Heat shock proteins (HSPs), known as molecular chaperone to assist protein folding, have recently become a research focus in Parkinson's disease (PD) because the pathogenesis of this disease is highlighted by the intracellular protein misfolding and inclusion body formation. The present review will focus on the functions of different HSPs and their protective roles in PD. It is postulated that HSPs may serve as protein folding machinery and work together with ubiquitin-proteasome system (UPS) to assist in decomposing aberrant proteins. Failure of UPS is thought to play a key role in the pathogenesis of PD. In addition, HSPs may possess anti-apoptotic effects and keep the homeostasis of dopaminergic neurons against stress conditions. The critical role of HSPs and recent discovery of some novel HSPs inducers suggest that HSPs may be potential therapeutic targets for PD and other neurodegenerative disorders.

Heat-Shock Proteins↗
PubMed2006

Neuroprotective effects of (-)-epigallocatechin-3-gallate in a transgenic mouse model of amyotrophic lateral sclerosis.

The purpose of this study is to evaluate neuroprotective effects of (-)-Epigallocatechin-3-gallate (EGCG) in a transgenic mouse model of Amyotrophic lateral sclerosis (ALS). SOD1-G93A transgenic mice and wild-type mice were randomly divided into EGCG-treated groups (10 mg/kg, p.o) and vehicle-treated control groups. Rotarod measurement was performed to assess the motor function of mice starting at the age of 70 days. Nissl staining to examine the number of motor neurons and CD11b immunohistochemical staining to evaluate activation of microglia in the lumbar spinal cords were conducted at the age of 120 days. In addition, for further observation of regulation of cell signaling pathways by EGCG, we used immunohistochemical analysis for nuclear factor kappa B (NF-kappaB) and cleaved caspase-3 as well as western blot analysis to determine the expression of nitric oxide synthase (iNOS) and NF-kappaB in the spinal cord. This study demonstrated that oral administration of EGCG beginning from a pre-symptomatic stage significantly delayed the onset of disease, and extended life span. Furthermore, EGCG-treated transgenic mice showed increased number of motor neurons, diminished microglial activation, reduced immunohistochemical reaction of NF-kappaB and cleaved caspase-3 as well as reduced protein level of iNOS and NF-kappaB in the spinal cords. In conclusion, this study provides further evidences that EGCG has multifunctional therapeutic effects in the mouse model of ALS.

Amyotrophic Lateral Sclerosis↗
PubMed2006

Light chain of botulinum neurotoxin serotype A: structural resolution of a catalytic intermediate.

Botulinum neurotoxin serotype A (BoNT/A, 1296 residues) is a zinc metalloprotease that cleaves SNAP25 to inhibit the fusion of neurotransmitter-carrying vesicles to the plasma membrane of peripheral neurons. BoNT/A is a disulfide-linked di-chain protein composed of an N-terminal, thermolysin-like metalloprotease light chain domain (LC/A, 448 residues) and a C-terminal heavy chain domain (848 residues) that can be divided into two subdomains, a translocation subdomain and a receptor binding subdomain. LC/A cleaves SNAP25 between residues Gln197-Arg198 and, unlike thermolysin, recognizes an extended region of SNAP25 for cleavage. The structure of a recombinant LC/A (1-425) treated with EDTA (No-Zn LC/A) was determined. The overall structure of No-Zn LC/A is similar to that reported for the holotoxin, except that it lacks the Zn ion, indicating that the role of Zn is catalytic not structural. In addition, structures of a noncatalytic mutant LC/A (Arg362Ala/Tyr365Phe) complexed with and without an inhibitor, ArgHX, were determined. The overall structure and the active site conformation for the mutant are the same as wild type. When the inhibitor binds to the active site, the carbonyl and N-hydroxyl groups form a bidentate ligand to the Zn ion and the arginine moiety binds to Asp369, suggesting that the inhibitor-bound structure mimics a catalytic intermediate with the Arg moiety binding at the P1' site. Consistent with this model, mutation of Asp369 to Ala decreases the catalytic activity of LC/A by approximately 600-fold, and the residual activity is not inhibited by ArgHX. These results provide new information on the reaction mechanism and insight into the development of strategies for small molecule inhibitors of BoNTs.

Amino Acid Sequence↗
PubMed2006

[Effects of perioperative enteral immunonutrition on nutritional status, immunity and inflammatory response of elderly patients].

OBJECTIVE: To evaluate the effects of perioperative enteral immunonutrition on the nutritional status, immunity, and inflammatory response of the elderly patients. METHODS: Eighty malnourished patients aged over 60 with malignant gastrointestinal tumors undergoing radical surgery were randomly divided into 2 groups: experimental group (immunonutrition group, n = 37), and control group (n = 43). In the experimental group Supportan and glutamine, with the calorific value of 125.4 kJ.kg(-1).d(-1), were given orally or by nasointestinal tube for 5 days before operation, through jejunostomy or nasointestinal tube during operation, and then through nasointestinal tube since the day 2 to day 9 after post-operationally. In the control group Nutrition with the same amount of calorific value was given in the same manner as mentioned above. Peripheral blood samples were collected 5 and 1 days pre-operationally, and 1 and 9 days post-operatively to examine the serum albumin (ALB), prealbumin (PA), transferrin (TFN), CD3, CD4, CD8, CD4/CD8, immunoglobulin (Ig) G, IgA, IgM, and C-reactive protein (CRP). RESULTS: Nine days after operation, the serum TFN was 2.18 g/L +/- 0.29 g/L, PA was 0.23 g/L +/- 0.09 g/L, CD4 was 33.8% +/- 5.4%, CD4/CD8 was 1.17 +/- 0.12, and IgG was 13.2 g/L +/- 1.8 g/L. all significantly higher than those of the control group (1.95 g/L +/- 0.28 g/L, 0.19 g/L +/- 0.03 g/L, 31.1% +/- 5.2%, 1.05 +/- 0.10, and 12.11 g/L +/- 1.53 g/L respectively, all P < 0.05). CONCLUSION: Perioperative enteral immunonutrition improves the nutritional status and immune function, und reduces the acute inflammatory response of elderly patients.

Adult↗
PubMed2006

Unique substrate recognition by botulinum neurotoxins serotypes A and E.

Botulinum neurotoxins (BoNTs) are zinc proteases that cleave SNARE proteins to elicit flaccid paralysis by inhibiting the fusion of neurotransmitter-carrying vesicles to the plasma membrane of peripheral neurons. There are seven serotypes of BoNT, termed A-G. BoNT serotype A and serotype E cleave SNAP25 at residues 197-198 and 180-181, respectively. Unlike other zinc proteases, the BoNTs recognize extended regions of SNAP25 for cleavage. The basis for this extended substrate recognition and specificity is unclear. Saturation mutagenesis and deletion mapping identified residues 156-202 of SNAP25 as the optimal cleavage domain for BoNT/A, whereas the optimal cleavage domain for BoNT/E was shorter, comprising residues 167-186 of SNAP25. Two sub-sites were resolved within each optimal cleavage domain, which included a recognition or active site (AS) domain that contained the site of cleavage and a binding (B) domain, which contributed to substrate affinity. Within the AS domains, the P1', P3, and P5 sites of SNAP25 contributed to scissile bond cleavage by LC/A, whereas the P1' and P2 sites of SNAP25 contributed to scissile bond cleavage by LC/E. These studies provide insight into the development of strategies for small molecule inhibitors of the BoNTs.

Amino Acid Sequence↗
PubMed2006

Epidermal inclusion cyst of phalanx: a case report and review of the literature.

Epidermal cyst within a toe phalanx is an extremely rare condition. It is important to differentiate this benign lesion, which can be easily treated by curettage, from other benign and malignant lesions of the bone with a similar clinical presentation, and which may require amputation of the toe. This report describes one such lesion in the mid-phalanx of the fourth toe in a 48-year-old woman, and which was successfully identified by intra-operative frozen diagnosis and treated by curettage.

Bone Diseases↗
PubMed2005

Continuous wave-based multiphoton excitation fluorescence for capillary electrophoresis.

It was reported that a novel detection method, continuous wave (CW)-based multiphoton excitation (MPE) fluorescence detection with diode laser (DL), has been firstly proposed for capillary electrophoresis (CE). Special design of end-column detection configuration proved to be superior to on-column type, considering the detection sensitivity. Three different kinds of fluorescent tags that were widely used as molecular label in bio-analysis, such as small-molecule dye, fluorescent protein and nano particle or also referred to as quantum dot (QD), have been evaluated as samples for the constructed detection scheme. Quantitative analyses were also performed using rhodamine species as tests, which revealed dynamic linear range over two orders of magnitude, with detection limit down to zeptomole-level. Simultaneous detection of fluorescent dyestuffs with divergent excitation and emission wavelengths in a broad range showed advantage of this scheme over conventional laser-induced fluorescence (LIF) detection. Further investigations on CW-MPE fluorescence detection with diode laser for capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) separations of fluorescein isothiocyanate (FITC) labeled amino acids indicated good prospect of this detection approach in various micro or nano-column liquid phase separation technologies.

Electrophoresis, Capillary↗
PubMed2005

Early effects of salinity on water transport in Arabidopsis roots. Molecular and cellular features of aquaporin expression.

Aquaporins facilitate the uptake of soil water and mediate the regulation of root hydraulic conductivity (Lp(r)) in response to a large variety of environmental stresses. Here, we use Arabidopsis (Arabidopsis thaliana) plants to dissect the effects of salt on both Lp(r) and aquaporin expression and investigate possible molecular and cellular mechanisms of aquaporin regulation in plant roots under stress. Treatment of plants by 100 mm NaCl was perceived as an osmotic stimulus and induced a rapid (half-time, 45 min) and significant (70%) decrease in Lp(r), which was maintained for at least 24 h. Macroarray experiments with gene-specific tags were performed to investigate the expression of all 35 genes of the Arabidopsis aquaporin family. Transcripts from 20 individual aquaporin genes, most of which encoded members of the plasma membrane intrinsic protein (PIP) and tonoplast intrinsic protein (TIP) subfamilies, were detected in nontreated roots. All PIP and TIP aquaporin transcripts with a strong expression signal showed a 60% to 75% decrease in their abundance between 2 and 4 h following exposure to salt. The use of antipeptide antibodies that cross-reacted with isoforms of specific aquaporin subclasses revealed that the abundance of PIP1s decreased by 40% as early as 30 min after salt exposure, whereas PIP2 and TIP1 homologs showed a 20% to 40% decrease in abundance after 6 h of treatment. Expression in transgenic plants of aquaporins fused to the green fluorescent protein revealed that the subcellular localization of TIP2;1 and PIP1 and PIP2 homologs was unchanged after 45 min of exposure to salt, whereas a TIP1;1-green fluorescent protein fusion was relocalized into intracellular spherical structures tentatively identified as intravacuolar invaginations. The appearance of intracellular structures containing PIP1 and PIP2 homologs was occasionally observed after 2 h of salt treatment. In conclusion, this work shows that exposure of roots to salt induces changes in aquaporin expression at multiple levels. These changes include a coordinated transcriptional down-regulation and subcellular relocalization of both PIPs and TIPs. These mechanisms may act in concert to regulate root water transport, mostly in the long term (> or =6 h).

Aquaporins↗