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BACKGROUND & AIMS: Schistosomiasis is one of the most prominent parasite-induced infectious diseases, affecting more than 250 million people. Schistosoma mansoni causes metabolic exhaustion and a strong redox imbalance in the liver, causing parenchymal damage, and may predispose for cancer. We investigated whether oxidative stress provokes hepatocellular proliferation upon S. mansoni infection. METHODS: The cell cycle, replication stress response, and proliferation were analyzed on transcriptional and protein levels in the livers of S. mansoni-infected hamsters and by mechanistic gain- and loss-of-function experiments in human hepatoma cells. Major results were validated in human biopsy specimens of S. mansoni-infected patients. RESULTS: S. mansoni infection induced licensing factors of DNA replication and cell-cycle checkpoint cyclins in parallel with a DNA damage response in hamster hepatocytes. Moreover, even unisexual infection without egg effects, as a reflection of a chronic inflammatory process, resulted in a moderate activation of several cell-cycle markers. S. mansoni soluble egg antigens induced proliferation of human hepatoma cells that could be abolished by reduced glutathione. CONCLUSIONS: Our data suggest that hepatocellular proliferation is triggered by S. mansoni egg-induced oxidative stress.
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Esquistossomose mansoni , Cricetinae , Animais , Humanos , Schistosoma mansoni/fisiologia , Esquistossomose mansoni/metabolismo , Estresse Oxidativo , Proliferação de CélulasRESUMO
Schistosomiasis is a parasitic disease affecting more than 250 million people worldwide. The transcription factor c-Jun, which is induced in S. mansoni infection-associated liver disease, can promote hepatocyte survival but can also trigger hepatocellular carcinogenesis. We aimed to analyze the hepatic role of c-Jun following S. mansoni infection. We adopted a hepatocyte-specific c-Jun knockout mouse model (Alb-Cre/c-Jun loxP) and analyzed liver tissue and serum samples by quantitative real-time PCR array, western blotting, immunohistochemistry, hydroxyproline quantification, and functional analyses. Hepatocyte-specific c-Jun knockout (c-JunΔli) was confirmed by immunohistochemistry and western blotting. Infection with S. mansoni induced elevated aminotransferase-serum levels in c-JunΔli mice. Of note, hepatic Cyclin D1 expression was induced in infected c-Junf/f control mice but to a lower extent in c-JunΔli mice. S. mansoni soluble egg antigen-induced proliferation in a human hepatoma cell line was diminished by inhibition of c-Jun signaling. Markers for apoptosis, oxidative stress, ER stress, inflammation, autophagy, DNA-damage, and fibrosis were not altered in S. mansoni infected c-JunΔli mice compared to infected c-Junf/f controls. Enhanced liver damage in c-JunΔli mice suggested a protective role of c-Jun. A reduced Cyclin D1 expression and reduced hepatic regeneration could be the reason. In addition, it seems likely that the trends in pathological changes in c-JunΔli mice cumulatively led to a loss of the protective potential being responsible for the increased hepatocyte damage and loss of regenerative ability.
Assuntos
Schistosoma mansoni , Esquistossomose mansoni , Humanos , Camundongos , Animais , Ciclina D1/metabolismo , Esquistossomose mansoni/parasitologia , Fígado/metabolismo , Hepatócitos/metabolismo , Proliferação de CélulasRESUMO
Background ABP 980 is a biosimilar antibody to reference trastuzumab (RTZ). Aim of the following study is to confirm the similarity of ABP 980 and RTZ in terms of clinical efficacy and safety in patients with HER2-positive early breast cancer (EBC) undergoing neoadjuvant trastuzumab-containing chemotherapy in a clinical real-world situation that also includes patients receiving pertuzumab. Methods Patients with HER2-positive EBC, who were treated from 12/2010 to 03/2020 at the Department of Women's Health at Tuebingen University Hospital, Germany, with at least four cycles of neoadjuvant chemotherapy (+/- pertuzumab) in combination with ABP 980 or RTZ were included in a retrospective analysis. For efficacy analysis patients achieving a pathologic complete remission (pCR = no invasive tumor in breast and lymph nodes) were compared. Safety was evaluated by comparing the number of patients with a decrease in left ventricular function (LVEF) of > 10%. Results 124 patients were included of whom 46 (37.1%) have received ABP 980 and 77 (62.9%) were treated with RTZ. A pCR was found in 77 patients (62.1%). For patients treated with ABP 980 as compared to RTZ, there was no significant difference regarding efficacy (pCR-rates of 60.9% versus 62.8%, p = 0.829) or cardiac safety (LVEF decline in 6.5% versus 2.6%, p = 0.274). Conclusion Similarity of ABP 980 as compared to RTZ was confirmed in a real-world situation, including a large proportion of patients that have also received pertuzumab treatment.
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Guard cells control the opening of stomatal pores in the leaf surface, with the use of a network of protein kinases and phosphatases. Loss of function of the CBL-interacting protein kinase 23 (CIPK23) was previously shown to decrease the stomatal conductance, but the molecular mechanisms underlying this response still need to be clarified. CIPK23 was specifically expressed in Arabidopsis guard cells, using an estrogen-inducible system. Stomatal movements were linked to changes in ion channel activity, determined with double-barreled intracellular electrodes in guard cells and with the two-electrode voltage clamp technique in Xenopus oocytes. Expression of the phosphomimetic variant CIPK23T190D enhanced stomatal opening, while the natural CIPK23 and a kinase-inactive CIPK23K60N variant did not affect stomatal movements. Overexpression of CIPK23T190D repressed the activity of S-type anion channels, while their steady-state activity was unchanged by CIPK23 and CIPK23K60N . We suggest that CIPK23 enhances the stomatal conductance at favorable growth conditions, via the regulation of several ion transport proteins in guard cells. The inhibition of SLAC1-type anion channels is an important facet of this response.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Ácido Abscísico/metabolismo , Ânions/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Membrana/metabolismo , Estômatos de Plantas/fisiologia , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismoRESUMO
Chenopodium quinoa uses epidermal bladder cells (EBCs) to sequester excess salt. Each EBC complex consists of a leaf epidermal cell, a stalk cell, and the bladder. Under salt stress, sodium (Na+ ), chloride (Cl- ), potassium (K+ ) and various metabolites are shuttled from the leaf lamina to the bladders. Stalk cells operate as both a selectivity filter and a flux controller. In line with the nature of a transfer cell, advanced transmission electron tomography, electrophysiology, and fluorescent tracer flux studies revealed the stalk cell's polar organization and bladder-directed solute flow. RNA sequencing and cluster analysis revealed the gene expression profiles of the stalk cells. Among the stalk cell enriched genes, ion channels and carriers as well as sugar transporters were most pronounced. Based on their electrophysiological fingerprint and thermodynamic considerations, a model for stalk cell transcellular transport was derived.
Assuntos
Chenopodium quinoa , Tolerância ao Sal , Chenopodium quinoa/genética , Chenopodium quinoa/metabolismo , Transporte de Íons , Íons/metabolismo , Potássio/metabolismo , Salinidade , Tolerância ao Sal/fisiologia , Plantas Tolerantes a Sal/metabolismo , Sódio/metabolismo , Bexiga Urinária/metabolismoRESUMO
Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Inundações , Canais Iônicos , Estresse Fisiológico , Animais , Ânions/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Canais Iônicos/genética , Canais Iônicos/metabolismo , Oócitos , XenopusRESUMO
Date palms are highly economically important species in hot arid regions, which may suffer ozone (O3) pollution equivalently to heat and water stress. However, little is known about date palm sensitivity to O3. Therefore, to identify their resistance mechanisms against elevated O3, physiological parameters (leaf gas exchange, chlorophyll fluorescence and leaf pigments) and biomass growth responses to realistic O3 exposure were tested in an isoprene-emitting date palm (Phoenix dactylifera L. cv. Nabut Saif) by a Free-Air Controlled Exposure (FACE) facility with three levels of O3 (ambient [AA, 45 ppb as 24-h average], 1.5 x AA and 2 x AA). We found a reduction of photosynthesis only at 2 x AA although some foliar traits known as early indicators of O3 stress responded already at 1.5 x AA, such as increased dark respiration, reduced leaf pigment content, reduced maximum quantum yield of PSII, inactivation of the oxygen evolving complex of PSII and reduced performance index PITOT. As a result, O3 did not affect most of the growth parameters although significant declines of root biomass occurred only at 2 x AA. The major mechanism in date palm for reducing the severity of O3 impacts was a restriction of stomatal O3 uptake due to low stomatal conductance and O3-induced stomatal closure. In addition, an increased respiration in elevated O3 may indicate an enhanced capacity of catabolizing metabolites for detoxification and repair. Interestingly, date palm produced low amounts of monoterpenes, whose emission was stimulated in 2 x AA, although isoprene emission declined at both 1.5 and 2 x AA. Our results warrant more research on a biological significance of terpenoids in plant resistance against O3 stress.
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Poluentes Atmosféricos , Ozônio , Phoeniceae , Poluentes Atmosféricos/toxicidade , Ozônio/toxicidade , Fotossíntese , Folhas de PlantaRESUMO
The emergence of antibiotic-resistant clinically relevant facultative pathogenic bacteria in the environment has become one of the most important global health challenges. Antibiotic-resistant bacteria (ARB) have been found in surface waters and wastewater treatment plants. Drinking water guidelines and the EU bathing water directive 2006/7/EC include the surveillance of defined microbiological parameters on species level, while the monitoring of ARB is missing in all existing guidelines. However, standardized methods for the detection of ARB exist for clinical investigations of human materials only. They are based on cultivation on selective agar plates. These methods cannot be used directly for environmental samples, because of the high amount and diversity of bacterial background flora which interferes with the detection of human-relevant ARB. The aim of this study was to introduce a proposal for future normative standard operation procedures, with international relevance, for the culture-based detection of clinically-relevant antibiotic resistant bacteria in aquatic environmental samples like wastewater and surface water: gram-negative bacteria resistant against 3rd generation cephalosporins (ESBL) and against carbapenems (CARBA), gram-positive vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA). The final adaptation of standardized cultivation methods included increasing the standard incubation temperature from 36 °C to 42 °C, which effectively inhibits the environmental background flora on agar plates while the desired target species survive. This enables the detection of target species in suitable sample volumes. Putative target colonies which belong to the remaining background flora had to be excluded by morphological and physiological differentiation. Therefore, a time and cost optimized testing scheme with good performance was developed, which allows an effective exclusion of non-target isolates in samples. Depending on the target species and sample type, sensitivity of up to 100% is achieved, and specificity ranges from 91.1% to 99.7%, while the positive predictive value, negative predicted value and accuracy rate are always >90%.
Assuntos
Staphylococcus aureus Resistente à Meticilina , Enterococos Resistentes à Vancomicina , Antagonistas de Receptores de Angiotensina , Inibidores da Enzima Conversora de Angiotensina , Antibacterianos , Humanos , Testes de Sensibilidade MicrobianaRESUMO
Multidrug-resistant bacteria cause difficult-to-treat infections and pose a risk for modern medicine. Sources of multidrug-resistant bacteria include hospital, municipal and slaughterhouse wastewaters. In this study, bacteria with resistance to 3rd generation cephalosporins were isolated from all three wastewater biotopes, including a maximum care hospital, municipal wastewaters collected separately from a city and small rural towns and the wastewaters of two pig and two poultry slaughterhouses. The resistance profiles of all isolates against clinically relevant antibiotics (including ß-lactams like carbapenems, the quinolone ciprofloxacin, colistin, and trimethoprim/sulfamethoxazole) were determined at the same laboratory. The bacteria were classified according to their risk to human health using clinical criteria, with an emphasis on producers of carbapenemases, since carbapenems are prescribed for hospitalized patients with infections with multi-drug resistant bacteria. The results showed that bacteria that pose the highest risk, i. e., bacteria resistant to all ß-lactams including carbapenems and ciprofloxacin, were mainly disseminated by hospitals and were present only in low amounts in municipal wastewater. The isolates from hospital wastewater also showed the highest rates of resistance against antibiotics used for treatment of carbapenemase producers and some isolates were susceptible to only one antibiotic substance. In accordance with these results, qPCR of resistance genes showed that 90% of the daily load of carbapenemase genes entering the municipal wastewater treatment plant was supplied by the clinically influenced wastewater, which constituted approximately 6% of the wastewater at this sampling point. Likewise, the signature of the clinical wastewater was still visible in the resistance profiles of the bacteria isolated at the entry into the wastewater treatment plant. Carbapenemase producers were not detected in slaughterhouse wastewater, but strains harboring the colistin resistance gene mcr-1 could be isolated. Resistances against orally available antibiotics like ciprofloxacin and trimethoprim/sulfamethoxazole were widespread in strains from all three wastewaters.
Assuntos
Matadouros , Águas Residuárias , Animais , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Bactérias/genética , Carbapenêmicos , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Hospitais Municipais , Humanos , Testes de Sensibilidade Microbiana , Suínos , beta-Lactamases/genéticaRESUMO
Soil salinity is destroying arable land and is considered to be one of the major threats to global food security in the 21st century. Therefore, the ability of naturally salt-tolerant halophyte plants to sequester large quantities of salt in external structures, such as epidermal bladder cells (EBCs), is of great interest. Using Chenopodium quinoa, a pseudo-cereal halophyte of great economic potential, we have shown previously that, upon removal of salt bladders, quinoa becomes salt sensitive. In this work, we analyzed the molecular mechanism underlying the unique salt dumping capabilities of bladder cells in quinoa. The transporters differentially expressed in the EBC transcriptome and functional electrophysiological testing of key EBC transporters in Xenopus oocytes revealed that loading of Na+ and Cl- into EBCs is mediated by a set of tailored plasma and vacuole membrane-based sodium-selective channel and chloride-permeable transporter.
Assuntos
Chenopodium quinoa/metabolismo , Plantas Tolerantes a Sal/metabolismo , Vacúolos/metabolismo , Células Epidérmicas/metabolismo , Células Epidérmicas/fisiologia , Proteínas de Membrana Transportadoras , Proteínas de Plantas/metabolismo , Salinidade , Tolerância ao Sal/fisiologia , Sódio/metabolismo , Canais de Sódio/metabolismo , Solo/química , Estresse Fisiológico , TranscriptomaRESUMO
Carbapenem antibiotics constitute the mainstay therapy of nosocomial infections with extended spectrum beta-lactamase producing Gram-negative bacteria; however, resistance against these compounds is increasing. This study was designed to demonstrate that carbapenemase-producing bacteria are disseminated from hospitals into the environment. To this end, resistant bacteria were isolated from a clinical/urban and from a rural catchment system in Germany in 2016/17. The study followed the dissemination of resistant bacteria from the wastewater through the wastewater treatment plant (WWTP) into the receiving surface waters. The bacteria were cultivated on selective agar and characterized by antibiotic testing, real-time PCR targeting carbapenemase genes and typing. Bacteria with resistance to third generation cephalosporins were isolated from all sample sites. 134 isolates harboring carbapenemase genes encoding VIM, NDM and OXA-48 and 26 XDR (extensively drug-resistant) strains with susceptibility to only one or two antibiotics were isolated from the clinical/urban system. The rural system yielded eight carbapenemase producers and no XDR strains. In conclusion, clinical wastewaters were charged with a high proportion of multidrug resistant bacteria. Although most of these bacteria were eliminated during wastewater treatment, dissemination into surface waters is possible as single carbapenemase producers were still present in the effluent of the WWTP.
Assuntos
Bactérias/efeitos dos fármacos , Bactérias/isolamento & purificação , Farmacorresistência Bacteriana Múltipla , Águas Residuárias/microbiologia , Antibacterianos/farmacologia , Bactérias/classificação , Bactérias/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Alemanha , Bactérias Gram-Negativas/genética , Humanos , Testes de Sensibilidade Microbiana , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
Auxin is a key regulator of plant growth and development, but the causal relationship between hormone transport and root responses remains unresolved. Here we describe auxin uptake, together with early steps in signaling, in Arabidopsis root hairs. Using intracellular microelectrodes we show membrane depolarization, in response to IAA in a concentration- and pH-dependent manner. This depolarization is strongly impaired in aux1 mutants, indicating that AUX1 is the major transporter for auxin uptake in root hairs. Local intracellular auxin application triggers Ca2+ signals that propagate as long-distance waves between root cells and modulate their auxin responses. AUX1-mediated IAA transport, as well as IAA- triggered calcium signals, are blocked by treatment with the SCFTIR1/AFB - inhibitor auxinole. Further, they are strongly reduced in the tir1afb2afb3 and the cngc14 mutant. Our study reveals that the AUX1 transporter, the SCFTIR1/AFB receptor and the CNGC14 Ca2+ channel, mediate fast auxin signaling in roots.
Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/metabolismo , Sinalização do Cálcio/genética , Proteínas F-Box/genética , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos/metabolismo , Raízes de Plantas/metabolismo , Receptores de Superfície Celular/genética , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Cálcio/metabolismo , Cátions Bivalentes , Canais de Cátion Regulados por Nucleotídeos Cíclicos/genética , Canais de Cátion Regulados por Nucleotídeos Cíclicos/metabolismo , Proteínas F-Box/metabolismo , Concentração de Íons de Hidrogênio , Ácidos Indolacéticos/farmacologia , Microeletrodos , Mutação , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Raízes de Plantas/efeitos dos fármacos , Plantas Geneticamente Modificadas , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-kit/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-kit/genética , Proteínas Proto-Oncogênicas c-kit/metabolismo , Receptores de Superfície Celular/metabolismoRESUMO
Chenopodium quinoa is a halophytic pseudocereal crop that is being cultivated in an ever-growing number of countries. Because quinoa is highly resistant to multiple abiotic stresses and its seed has a better nutritional value than any other major cereals, it is regarded as a future crop to ensure global food security. We generated a high-quality genome draft using an inbred line of the quinoa cultivar Real. The quinoa genome experienced one recent genome duplication about 4.3 million years ago, likely reflecting the genome fusion of two Chenopodium parents, in addition to the γ paleohexaploidization reported for most eudicots. The genome is highly repetitive (64.5% repeat content) and contains 54 438 protein-coding genes and 192 microRNA genes, with more than 99.3% having orthologous genes from glycophylic species. Stress tolerance in quinoa is associated with the expansion of genes involved in ion and nutrient transport, ABA homeostasis and signaling, and enhanced basal-level ABA responses. Epidermal salt bladder cells exhibit similar characteristics as trichomes, with a significantly higher expression of genes related to energy import and ABA biosynthesis compared with the leaf lamina. The quinoa genome sequence provides insights into its exceptional nutritional value and the evolution of halophytes, enabling the identification of genes involved in salinity tolerance, and providing the basis for molecular breeding in quinoa.
Assuntos
Chenopodium quinoa/genética , Genoma de Planta , Salinidade , Ácido Abscísico/biossíntese , Ácido Abscísico/metabolismo , Chenopodium quinoa/química , Chenopodium quinoa/classificação , Chenopodium quinoa/metabolismo , Evolução Molecular , Genômica , Lisina/análise , Anotação de Sequência Molecular , Filogenia , Epiderme Vegetal/citologia , Epiderme Vegetal/metabolismo , Transdução de Sinais , TranscriptomaRESUMO
Date palm Phoenix dactylifera is a desert crop well adapted to survive and produce fruits under extreme drought and heat. How are palms under such harsh environmental conditions able to limit transpirational water loss? Here, we analysed the cuticular waxes, stomata structure and function, and molecular biology of guard cells from P. dactylifera. To understand the stomatal response to the water stress phytohormone of the desert plant, we cloned the major elements necessary for guard cell fast abscisic acid (ABA) signalling and reconstituted this ABA signalosome in Xenopus oocytes. The PhoenixSLAC1-type anion channel is regulated by ABA kinase PdOST1. Energy-dispersive X-ray analysis (EDXA) demonstrated that date palm guard cells release chloride during stomatal closure. However, in Cl- medium, PdOST1 did not activate the desert plant anion channel PdSLAC1 per se. Only when nitrate was present at the extracellular face of the anion channel did the OST1-gated PdSLAC1 open, thus enabling chloride release. In the presence of nitrate, ABA enhanced and accelerated stomatal closure. Our findings indicate that, in date palm, the guard cell osmotic motor driving stomatal closure uses nitrate as the signal to open the major anion channel SLAC1. This initiates guard cell depolarization and the release of anions together with potassium.
Assuntos
Ânions/metabolismo , Clima Desértico , Nitratos/farmacologia , Phoeniceae/fisiologia , Proteínas de Plantas/metabolismo , Estômatos de Plantas/fisiologia , Ácido Abscísico/metabolismo , Cloretos/metabolismo , Secas , Luz , Osmose , Phoeniceae/efeitos dos fármacos , Phoeniceae/efeitos da radiação , Phoeniceae/ultraestrutura , Estômatos de Plantas/citologia , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/ultraestrutura , RNA de Plantas/metabolismo , Frações Subcelulares/metabolismo , Ceras/metabolismoRESUMO
Water limitation of plants causes stomatal closure to prevent water loss by transpiration. For this purpose, progressing soil water deficit is communicated from roots to shoots. Abscisic acid (ABA) is the key signal in stress-induced stomatal closure, but ABA as an early xylem-delivered signal is still a matter of debate. In this study, poplar plants (Populus × canescens) were exposed to water stress to investigate xylem sap sulfate and ABA, stomatal conductance, and sulfate transporter (SULTR) expression. In addition, stomatal behavior and expression of ABA receptors, drought-responsive genes, transcription factors, and NCED3 were studied after feeding sulfate and ABA to detached poplar leaves and epidermal peels of Arabidopsis (Arabidopsis thaliana). The results show that increased xylem sap sulfate is achieved upon drought by reduced xylem unloading by PtaSULTR3;3a and PtaSULTR1;1, and by enhanced loading from parenchyma cells into the xylem via PtaALMT3b. Sulfate application caused stomatal closure in excised leaves and peeled epidermis. In the loss of sulfate-channel function mutant, Atalmt12, sulfate-triggered stomatal closure was impaired. The QUAC1/ALMT12 anion channel heterologous expressed in oocytes was gated open by extracellular sulfate. Sulfate up-regulated the expression of NCED3, a key step of ABA synthesis, in guard cells. In conclusion, xylem-derived sulfate seems to be a chemical signal of drought that induces stomatal closure via QUAC1/ALMT12 and/or guard cell ABA synthesis.
Assuntos
Ácido Abscísico/biossíntese , Proteínas de Arabidopsis/metabolismo , Transportadores de Ânions Orgânicos/metabolismo , Estômatos de Plantas/fisiologia , Sulfatos/metabolismo , Xilema/metabolismo , Ácido Abscísico/metabolismo , Animais , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Secas , Feminino , Regulação da Expressão Gênica de Plantas , Mutação , Oócitos/metabolismo , Transportadores de Ânions Orgânicos/genética , Células Vegetais/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Populus/fisiologia , Transdução de Sinais , Xenopus laevis , Xilema/químicaRESUMO
Higher plants take up nutrients via the roots and load them into xylem vessels for translocation to the shoot. After uptake, anions have to be channeled toward the root xylem vessels. Thereby, xylem parenchyma and pericycle cells control the anion composition of the root-shoot xylem sap [1-6]. The fact that salt-tolerant genotypes possess lower xylem-sap Cl(-) contents compared to salt-sensitive genotypes [7-10] indicates that membrane transport proteins at the sites of xylem loading contribute to plant salinity tolerance via selective chloride exclusion. However, the molecular mechanism of xylem loading that lies behind the balance between NO3(-) and Cl(-) loading remains largely unknown. Here we identify two root anion channels in Arabidopsis, SLAH1 and SLAH3, that control the shoot NO3(-)/Cl(-) ratio. The AtSLAH1 gene is expressed in the root xylem-pole pericycle, where it co-localizes with AtSLAH3. Under high soil salinity, AtSLAH1 expression markedly declined and the chloride content of the xylem sap in AtSLAH1 loss-of-function mutants was half of the wild-type level only. SLAH3 anion channels are not active per se but require extracellular nitrate and phosphorylation by calcium-dependent kinases (CPKs) [11-13]. When co-expressed in Xenopus oocytes, however, the electrically silent SLAH1 subunit gates SLAH3 open even in the absence of nitrate- and calcium-dependent kinases. Apparently, SLAH1/SLAH3 heteromerization facilitates SLAH3-mediated chloride efflux from pericycle cells into the root xylem vessels. Our results indicate that under salt stress, plants adjust the distribution of NO3(-) and Cl(-) between root and shoot via differential expression and assembly of SLAH1/SLAH3 anion channel subunits.
Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Canais Iônicos/genética , Ânions/metabolismo , Proteínas de Arabidopsis/metabolismo , Canais Iônicos/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Tolerância ao SalRESUMO
Extrafloral nectaries secrete a sweet sugar cocktail that lures predator insects for protection from foraging herbivores. Apart from sugars and amino acids, the nectar contains the anions chloride and nitrate. Recent studies with Populus have identified a type of nectary covered by apical bipolar epidermal cells, reminiscent of the secretory brush border epithelium in animals. Border epithelia operate transepithelial anion transport, which is required for membrane potential and/or osmotic adjustment of the secretory cells. In search of anion transporters expressed in extrafloral nectaries, we identified PttSLAH3 (Populus tremula × Populus tremuloides SLAC1 Homologue3), an anion channel of the SLAC/SLAH family. When expressed in Xenopus oocytes, PttSLAH3 displayed the features of a voltage-dependent anion channel, permeable to both nitrate and chloride. In contrast to the Arabidopsis SLAC/SLAH family members, the poplar isoform PttSLAH3 is independent of phosphorylation activation by protein kinases. To understand the basis for the autonomous activity of the poplar SLAH3, we generated and expressed chimera between kinase-independent PttSLAH3 and kinase-dependent Arabidopsis AtSLAH3. We identified the N-terminal tail and, to a lesser extent, the C-terminal tail as responsible for PttSLAH3 kinase-(in)dependent action. This feature of PttSLAH3 may provide the secretory cell with a channel probably controlling long-term nectar secretion.
Assuntos
Ânions/metabolismo , Epitélio/metabolismo , Canais Iônicos/metabolismo , Proteínas de Plantas/metabolismo , Populus/metabolismo , Proteínas Quinases/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/metabolismo , Epitélio/efeitos dos fármacos , Flores/efeitos dos fármacos , Flores/metabolismo , Ativação do Canal Iônico/efeitos dos fármacos , Nitratos/farmacologia , Néctar de Plantas , Proteínas de Plantas/química , Populus/efeitos dos fármacos , Proteínas Recombinantes de Fusão/metabolismo , Relação Estrutura-AtividadeRESUMO
Tourette syndrome (TS) is a neuropsychiatric disorder with a strong genetic component. However, the genetic architecture of TS remains uncertain. Copy number variation (CNV) has been shown to contribute to the genetic make-up of several neurodevelopmental conditions, including schizophrenia and autism. Here we describe CNV calls using SNP chip genotype data from an initial sample of 210 TS cases and 285 controls ascertained in two Latin American populations. After extensive quality control, we found that cases (Nâ=â179) have a significant excess (Pâ=â0.006) of large CNV (>500 kb) calls compared to controls (Nâ=â234). Amongst 24 large CNVs seen only in the cases, we observed four duplications of the COL8A1 gene region. We also found two cases with â¼400 kb deletions involving NRXN1, a gene previously implicated in neurodevelopmental disorders, including TS. Follow-up using multiplex ligation-dependent probe amplification (and including 53 more TS cases) validated the CNV calls and identified additional patients with rearrangements in COL8A1 and NRXN1, but none in controls. Examination of available parents indicates that two out of three NRXN1 deletions detected in the TS cases are de-novo mutations. Our results are consistent with the proposal that rare CNVs play a role in TS aetiology and suggest a possible role for rearrangements in the COL8A1 and NRXN1 gene regions.
Assuntos
Moléculas de Adesão Celular Neuronais/genética , Colágeno Tipo IX/genética , Variações do Número de Cópias de DNA/genética , Proteínas do Tecido Nervoso/genética , Síndrome de Tourette/genética , Adolescente , Proteínas de Ligação ao Cálcio , Criança , Feminino , Predisposição Genética para Doença/genética , Genótipo , Humanos , Masculino , Moléculas de Adesão de Célula Nervosa , Polimorfismo de Nucleotídeo Único/genética , Síndrome de Tourette/etiologiaRESUMO
BACKGROUND: Interstitial pneumonias (IP) cover a broad spectrum of diseases. Open lung biopsies reveal histological patterns and suggest possible diagnoses. Complete clinical records are necessary for final diagnoses. Especially idiopathic interstitial pneumonias (IIP) according to the ATS/ERS classification can only be diagnosed under these predictions. The aim of this study was to compare the results of histological evaluations with the final diagnosis after interdisciplinary case evaluation. PATIENTS AND METHODS: 88 patients with interstitial pneumonia that underwent open lung biopsies were investigated. Histology and clinical records were available for review. Diagnosis was made in three steps: first on the sole basis of histology, second with clinical information given initially and third, on the basis of an interdisciplinary case evaluation. RESULTS: 63 patients (72%) were diagnosed as idiopathic interstitial pneumonias according to ATS/ERS criteria. Further 10 (11%) cases of hypersensitivity pneumonitis, 7 (8%) Langerhans cell histiocytosis and 8 (9%) interstitial pneumonias of other known causes or associations were detected. Histological patterns alone agreed with the final diagnosis in 67%. In 82% histology and clinical information given to the pathologist could provide correct diagnosis. In the rest of cases, especially in non idiopathic interstitial pneumonias, an interdisciplinary case evaluation was needed. CONCLUSIONS: Diagnosis of interstitial pneumonias by open lung biopsies needs sufficient clinical information. Because of the overlap of histological patterns, an interdisciplinary case evaluation that includes at least one clinical expert and one pathologist with excellent expertise and the follow-up of the patients is necessary to find correct diagnosis in all cases. VIRTUAL SLIDES: The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5031706258025129.