RESUMEN
Under xenon lamps, ZnFe2O4 (ZFO) has been shown to be effective in removing uranium through photocatalysis. However, its performance is still inadequate in low-light environments due to low photon utilization and high electron-hole complexation. Herein, S-doped hollow ZnFe2O4 microcubes (Sx-H-ZFO, x = 1, 3, 6, 9) were synthesized using the MOF precursor template method. The hollow morphology improves the utilization of visible light by refracting and reflecting the incident light multiple times within the confined domain. S doping narrows the band gap and shifts the conduction band position negatively, which enhances the separation, migration, and accumulation of photogenerated charges. Additionally, S doping increases the number of adsorption sites, ultimately promoting efficient surface reactions. Consequently, Sx-H-ZFO is capable of removing U(VI) in low-light environments. Under cloudy and rainy weather conditions, the photocatalytic rate of S3-H-ZFO was 100.31 µmol/(g·h), while under LED lamps (5000 Lux) it was 72.70 µmol/(g·h). More interestingly, a systematic mechanistic investigation has revealed that S doping replaces some of the oxygen atoms to enhance electron transfers and adsorption of O2. This process initiates the formation of hydrogen peroxide, which reacts directly with UO22+ to form solid studtite (UO2)O2·2H2O. Additionally, the promising magnetic separation capability of Sx-H-ZFO facilitates the recycling and reusability of the material. This work demonstrates the potential of ZnFe2O4 extraction uranium from nuclear wastewater.
RESUMEN
Colon cancer has become a global public health challenge, and 5-Fluorouracil (5-FU) chemoresistance is a major obstacle in its treatment. Chemoresistance can be mediated by therapy-induced cellular senescence. This study intended to investigate mechanisms of INHBA (inhibin A) in 5-FU resistance mediated by cellular senescence in colon cancer. Bioinformatics analysis of INHBA expression in colon cancer tissues, survival analysis, and correlation analysis of cellular senescence markers were performed. The effects of INHBA on the biological characteristics and 5-FU resistance of colon cancer cells were examined through loss/gain-of-function and molecular assays. Finally, a xenograft mouse model was built to validate the mechanism of INHBA in vivo. INHBA was upregulated in colon cancer and was significantly positively correlated with cellular senescence markers uncoupling protein 2 (UCP-2), matrix metalloproteinase-1 (MMP-1), dense and erect panicle 1 (DEP1), and p21. Cellular senescence in colon cancer mediated 5-FU resistance. Downregulation of INHBA expression enhanced 5-FU sensitivity in colon cancer cells, inhibited cell proliferation, promoted apoptosis, increased the proportion of cells in G0/G1 phase, and it resulted in a lower proportion of senescent cells and lower levels of the cellular senescence markers interleukin 6 (IL-6) and interleukin 8 (IL-8). Analysis of whether to use the pathway inhibitor Verteporfin proved that INHBA facilitated colon cancer cell senescence and enhanced 5-FU chemoresistance via inactivation of Hippo signaling pathway, and consistent results were obtained in vivo. Collectively, INHBA conferred 5-FU chemoresistance mediated by cellular senescence in colon cancer cells through negative regulation of Hippo signaling.
Asunto(s)
Senescencia Celular , Neoplasias del Colon , Resistencia a Antineoplásicos , Fluorouracilo , Vía de Señalización Hippo , Proteínas Serina-Treonina Quinasas , Transducción de Señal , Fluorouracilo/farmacología , Humanos , Senescencia Celular/efectos de los fármacos , Neoplasias del Colon/patología , Neoplasias del Colon/metabolismo , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/genética , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Animales , Ratones , Transducción de Señal/efectos de los fármacos , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Ratones Desnudos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Ensayos Antitumor por Modelo de Xenoinjerto , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Ratones Endogámicos BALB C , Apoptosis/efectos de los fármacos , MasculinoRESUMEN
Histospecification and morphogenesis of anthers during development in Arabidopsis (Arabidopsis thaliana) are well understood. However, the regulatory mechanism of microsporocyte generation at the pre-meiotic stage remains unclear, especially how archesporial cells are specified and differentiate into 2 cell lineages with distinct developmental fates. SPOROCYTELESS (SPL) is a key reproductive gene that is activated during early anther development and remains active. In this study, we demonstrated that the EAR motif-containing adaptor protein (ECAP) interacts with the Gro/Tup1 family corepressor LEUNIG (LUG) and the BES1/BZR1 HOMOLOG3 (BEH3) transcription factor to form a transcription activator complex, epigenetically regulating SPL transcription. SPL participates in microsporocyte generation by modulating the specification of archesporial cells and the archesporial cell-derived differentiation of somatic and reproductive cell layers. This study illustrates the regulation of SPL expression by the ECAP-LUG-BEH3 complex, which is essential for the generation of microsporocytes. Moreover, our findings identified ECAP as a key transcription regulator that can combine with different partners to regulate gene expression in distinct ways, thereby facilitating diverse processes in various aspects of plant development.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Regulación de la Expresión Génica de las Plantas , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas Co-Represoras/metabolismo , Proteínas Co-Represoras/genética , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Proteínas Nucleares , Polen/genética , Polen/metabolismo , Polen/crecimiento & desarrollo , Proteínas Represoras/metabolismo , Proteínas Represoras/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genéticaRESUMEN
Piezoelectric-photocatalysis is distinguished by its piezoelectricity as an external force that induces deformation within the catalyst to engender a polarized electric field compared to conventional photocatalysis. Herein, the piezoelectric photocatalyst BiOBr has been expertly synthesized via a plasma process and applied for piezoelectric-photocatalysis removal of uranium(VI) for the first time. The abundant surface oxygen vacancies (OVs) could induce a dipole moment and built-in electric field, which endows BiOBr with excellent separation and transport efficiency of photogenerated charges to actuate more charges to participate in the piezoelectric-photocatalytic reduction process. Consequently, under visible light and ultrasound (150 W and 40 kHz), the removal rate constant of OVs-BiOBr-30 (0.0306 min-1) was 2.4, 30.6, and 6 times higher than those of BiOBr (0.01273 min-1), ultrasound, or photocatalysis, respectively. The piezoelectric-photocatalytic synergy is also universal for BiOX (X = Cl, Br, or I) to accelerate the reduction rate of uranium(VI). This work highlights the role of piezoelectric-photocatalysis in the treatment of uranium-containing wastewater, which is of great significance for resource conservation and environmental remediation.
RESUMEN
Inspired by its large specific surface area, and tunable chemical and physical properties, a hollow carbon-based mater8ial derived from ZIF-8 with phosphate groups (HCM-PO4) was prepared for the elimination of U(VI). The structural and surface features of HCM and HCM-PO4 were thoroughly examined using techniques such as SEM, TEM, and XRD. The resulting carbon material, HCM-PO4, exhibits a higher BET surface area of 571.2 m2·g-1, featuring a hollow structure. The removal procedure of HCM-PO4 for U(VI) aligns with the quasi-secondary kinetic model. Furthermore, the theoretical sorption capacity of HCM-PO4 was found to be 482.30 mg·g-1 at 298.15 K. The results obtained from XPS, FT-IR, and EDS analysis of HCM-PO4 after adsorption revealed the coordination of the phosphate group for U(VI), contributing significantly to the adsorption process. In brief, the HCM-PO4 demonstrates excellent adsorptive ability, positioning it as a hopeful expectant to remove U(VI) from wastewater.
Asunto(s)
Carbono , Fosfatos , Adsorción , Espectroscopía Infrarroja por Transformada de Fourier , CinéticaRESUMEN
OBJECTIVES: Ovarian cancer is a frequent malignancy among women. Fucoxanthin has been discovered to exert anti-tumor impacts on numerous tumors. Herein, the current work was carried out to identify the biological function of fucoxanthin on the malignant progression of ovarian cancer and to explore the underlying molecular mechanisms. METHODS: In this study, cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU) staining, wound healing, as well as transwell assays were employed to assess the malignant cell phenotypes, including cell proliferation, migration and invasion in ovarian cancer. The expression of related proteins was evaluated using western blot. Additionally, the glucose uptake, intracellular adenosine triphosphate (ATP), extracellular acidifications rates (ECAR) and glycolysis-associated enzymes were measured to evaluate glycolysis level. RESULTS: It was demonstrated that fucoxanthin restrained the proliferative, migratory and invasive capabilities in both A2780 and OVCAR3 cells. Fucoxanthin could inhibit glycolysis and inactivate signal transducers and activators of transcription 3 (STAT3)/c-Myc signaling. In addition, Colivelin, a STAT3 activator, greatly weakened the suppressive effects of fucoxanthin on ovarian cancer cell proliferation, migration, invasion and glycolysis. CONCLUSION: Fucoxanthin exerts anti-tumor activity in ovarian cancer, possibly via inactivation of the STAT3/c-Myc signaling pathway, and thus provides a novel therapeutic strategy for the treatment of ovarian cancer.
RESUMEN
Effective spatial separation and utilization of photogenerated charges are critical for photocatalysis process. Herein, novel Co3O4 @TiO2 @CdS@Au double-shelled nanocage (CTCA) with spatially separated redox centers was synthesized by loading Co3O4 and Au NP cocatalysts on the inner and outer surfaces of Z-scheme heterojunction (TiO2 @CdS). The reduction rate constant of U(VI) by CTCA reached 0.218 min-1 under simulated sunlight irradiation, which was 6.6, 3.2 and 36.3 times than that of monolayer CTCA (0.033 min-1), CTC (0.068 min-1) and CT (0.006 min-1). The full-spectrum light-assisted photothermal catalytic performance can enable CTCA to remove 98.8% of U(VI) and degrade nearly 90% of five organic pollutants simultaneously. Detailed characterizations and theory calculations revealed that the photogenerated holes and electrons in CTCA flow inward and outward. More importantly, Co3O4 acts as a "nano heater" to generate the photothermal effect for further enhancing the charge transfer and accelerating the surface reaction kinetics. Meanwhile, the photogenerated electrons and superoxide radicals play a dominant role in reducing the adsorbed U(VI) to insoluble (UO2)O2·2H2O(s). This work provides valuable input toward a novel double-shelled hollow nanocage reactor with excellent photothermal catalysis ability for efficient recovery U(VI) from uranium mine wastewater to address environmental contamination issues.
RESUMEN
Designing highly efficient photocatalysts with rapid migration of photogenerated charges and surface reaction kinetics for the photocatalytic removal of uranium (U(VI)) from uranium mine wastewater remains a significant challenge. Inspired by natural photosynthesis, a biomimetic photocatalytic system is assembled by designing a novel hollow nanosphere MnOx @TiO2 @CdS@Au (MTCA) with loading MnOx and Au nano particles (Au NPs) cocatalysts on the inner and outer surfaces of the TiO2 @CdS. The spatially separated cocatalysts efficiently drive the photogenerated charges to migrate in opposite directions, while the Z-scheme heterogeneous shell further separates the interfacial charges. Theoretical calculation identifies multiple consecutive forward charge transfers without charge recombination within MTCA. Thus, MTCA could efficiently remove 99.61% of U(VI) after 15 min of simulated sunlight irradiation within 3 mmol L-1 NaHCO3 with 0.231 min-1 of the reduction rate constant, outperforming most previously reported photocatalysts. MTCA further significantly removes 91.83% of U(VI) from the natural uranium mining wastewater under sunlight irradiation. This study provides a novel approach to designing an ideal biomimetic photocatalyst for remediating environmental pollution.
RESUMEN
The separation of magnetic adsorbents from aqueous solutions is made simple by using an external magnetic field. Herein, magnetic Zr(IV)-ethylenediamine tetramethylene phosphonic acid (EDTMPA) hybrids (MZrOP-x-T, x, and T were the different quality of Fe3O4@C and temperature in the synthesis process, respectively). A study was conducted on the uses of MZrOP-x-T in the capture of U(VI). The influences of pH, adsorption period, initial concentration, and temperature were all investigated. Furthermore, the desorption and reusability of the materials were explored. The optimal values of x and T were 0.2 g and 100 °C, respectively. At 298.15 K, the maximum adsorption capacity of MZrOP-0.2-100 was 330.30 mg·g-1. The current research demonstrates that MZrOP-0.2-100 is a potentially effective material in removing U(VI) from radioactive solution.
RESUMEN
In this work, a ratiometric fluorescence system was designed for the detection of trace UO22+ in water based on the inner filter effect (IFE) between gold nanoparticles (AuNPs) and gold nanoclusters (AuNCs). IFE-induced fluorescence quenching was achieved due to the enhanced complementary overlap between the absorption spectra of AuNPs and the emission spectrum of AuNCs after the addition of UO22+. Blue carbon dots (B-CDs) were added to serve as reference fluorophores to expand the color tonality and make human eye recognition easier. The ratiometric fluorescent sensor demonstrated a unique fluorescence color change from red to blue when different doses of UO22+ were added, with a detection limit of 8.4 nM. Furthermore, the ratiometric fluorescent sensor was effectively used for UO22+ determination in real-world water samples, with acceptable recoveries.
Asunto(s)
Oro , Nanopartículas del Metal , Humanos , Iones , Límite de Detección , Espectrometría de FluorescenciaRESUMEN
OBJECTIVE: The objective of the study was to investigate the effect of multiple clinical parameters (age, weight, blood types, and bleeding types) on FVIII pharmacokinetic parameters (PK parameters) in adult patients with severe hemophilia A (SHA), draw up individualized preventive treatment plans, and observe clinical efficacy. METHODS: Forty SHA patients treated in our hospital from January 2018 to May 2019 were enrolled, with their age, weight, blood types, bleeding types, and PK parameters measured to analyze the effects of clinical parameters on PK parameters. Individualized preventive treatment was developed, and patients were followed up for 1 year. The annual bleeding rate (ABR), annual joint bleeding rate (AJBR), and annual FVIII dosage were observed and compared before and after treatment. RESULTS: Weight, blood types, and bleeding types could affect the PK parameters of FVIII. A prophylaxis plan was formulated under the guidance of FVIII half-life. After 1 year of follow-up, the mean ABR dropped from 36.54 to 4.06, decreased by 88.9%, the mean AJBR dropped from 28.36 to 2.75, decreased by 90%, and annual FVIII dosage increased by 47%. The dosage of FVIII in 8 patients after was less than that before prophylaxis, and the average half-life time of these 8 patients was 13.32 h. CONCLUSIONS: (1) Weight, blood types, and bleeding types of adult SHA patients could affect FVIII half-life. As body mass index increased, FVIII half-life was significantly prolonged. The FVIII half-life of patients with type O blood was significantly shorter than those with other blood types, and the FVIII half-life of knee joint bleeding was conspicuously shorter than those of elbow joint bleeding. (2) Individualized preventive treatment could markedly reduce the number of bleeds. For patients with a long half-life period, the total annual FVIII dosage could be reduced to achieve bleeding prevention.
Asunto(s)
Hemofilia A , Adulto , Factor VIII/uso terapéutico , Semivida , Hemartrosis/etiología , Hemartrosis/prevención & control , Hemofilia A/complicaciones , Hemofilia A/tratamiento farmacológico , Hemorragia/tratamiento farmacológico , Hemorragia/etiología , Hemorragia/prevención & control , HumanosRESUMEN
HKUST-1@CMC (HK@CMC) composites that show good acid and alkali resistance and radiation resistance were successfully synthesized by introducing carboxymethyl cellulose (CMC) onto the surface of HKUST-1 using a foaming strategy. For the first time, the composites were explored as efficient adsorbents for U(VI) trapping from aqueous solution, with encouraging results of large adsorption capacity, fast adsorption kinetics, and desirable selectivity toward U(VI) over a series of competing ions. More importantly, a hybrid derivative film was successfully prepared for the dynamic adsorption of U(VI). The results show that â¼90% U(VI) can be removed when 45 mg L-1 U(VI) was passed through the film one time, and the removal percentage is still more than 80% even after four adsorption-desorption cycles, ranking one of the most practical U(VI) scavengers. This work offers new clues for application of the Metal-organic-framework-based materials in the separation of radionuclides from wastewater.
RESUMEN
In this work, hexadecyltrimethylammonium-bromide (HTAB)-modified polythiophene (PTh)/TiO2 nanocomposite (HTAB/PTh/TiO2) was applied to remove uranyl ions (UO22+). FT-IR, XRD, ζ potential, TGA, SEM, and XPS were utilized to obtain the chemical and physical properties of HTAB/PTh/TiO2. The effects of HTAB content, preparation temperature, and adsorption conditions on UO22+ removal were investigated comprehensively. And the UO22+ adsorption process on HTAB/PTh/TiO2 was fitted to the Sips model with a saturated adsorption capacity of 234.74 mg/g, which was 6 times over TiO2. The results suggested that the surfactant of HTAB can significantly improve the adsorption ability of TiO2 for UO22+ ions. This work provides a strategy of surfactant modification for enhancing the separation and recovery ability of adsorbent toward UO22+ in the radioactive wastewater.
Asunto(s)
Nanocompuestos , Tensoactivos , Adsorción , Iones , Polímeros , Espectroscopía Infrarroja por Transformada de Fourier , Tiofenos , TitanioRESUMEN
In this work, nitrogen and phosphorus co-doped magnetic carbon spheres encapsulating well-dispersed active Fe nanocrystals (Fe/P-CN) were fabricated via a simple copolymer pyrolysis strategy. Benefiting from heteroatoms doping, Fe/P-CN could primarily adsorb soluble U(vi) ions through abundant functional groups, and subsequently, the adsorbed U(vi) could be reduced to insoluble U(iv) by Fe nanocrystals. Fe/P-CN pyrolyzed at 800 °C (Fe/P-CN-800) exhibited excellent U(vi) removal capacity of 306.76 mg g-1, surpassing nitrogen and phosphorus co-doped carbon spheres and nano zero-valent iron. In addition, the magnetic separation and thermal reactivation properties endow Fe/P-CN-800 with excellent reusability. This research, especially, provides a promising synergistic adsorption and reduction strategy to effectively remove U(vi) using heteroatom-doped composites.
RESUMEN
Cell-wall deposition of cellulose microfibrils is essential for plant growth and development. In plant cells, cellulose synthesis is accomplished by cellulose synthase complexes located in the plasma membrane. Trafficking of the complex between endomembrane compartments and the plasma membrane is vital for cellulose biosynthesis; however, the mechanism for this process is not well understood. We here report that, in Arabidopsis thaliana, Rab-H1b, a Golgi-localized small GTPase, participates in the trafficking of CELLULOSE SYNTHASE 6 (CESA6) to the plasma membrane. Loss of Rab-H1b function resulted in altered distribution and motility of CESA6 in the plasma membrane and reduced cellulose content. Seedlings with this defect exhibited short, fragile etiolated hypocotyls. Exocytosis of CESA6 was impaired in rab-h1b cells, and endocytosis in mutant cells was significantly reduced as well. We further observed accumulation of vesicles around an abnormal Golgi apparatus having an increased number of cisternae in rab-h1b cells, suggesting a defect in cisternal homeostasis caused by Rab-H1b loss function. Our findings link Rab GTPases to cellulose biosynthesis, during hypocotyl growth, and suggest Rab-H1b is crucial for modulating the trafficking of cellulose synthase complexes between endomembrane compartments and the plasma membrane and for maintaining Golgi organization and morphology.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Glucosiltransferasas/metabolismo , Hipocótilo/metabolismo , Proteínas de Unión al GTP rab/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Exocitosis/genética , Exocitosis/fisiología , Glucosiltransferasas/genética , Aparato de Golgi/genética , Aparato de Golgi/metabolismo , Hipocótilo/genética , Transporte de Proteínas/fisiología , Proteínas de Unión al GTP rab/genéticaRESUMEN
In this study, three simple methods were described to synthesize covalently functionalized graphene nanoplatelets (GNPs) with poly(styrene-co-maleic anhydride) (SMA) via ester linkages. Furthermore, the dispersibility of modified GNPs in aqueous solution was characterized by several techniques. Anchoring of SMA long-chains on GNPs via chemical bonds was confirmed by Fourier transform infrared spectroscopy. Furthermore, field emission scanning electron microscopy analysis indicated that the SMA unevenly covered the surface and edges of the GNPs. Solubility measurements showed that the modified GNPs prepared by the designed method had excellent dispersibility in aqueous solution, and the grafting rate of modified GNPs showed an obvious positive correlation with the concentration in aqueous solution as revealed by ultraviolet absorbency and thermogravimetric analysis results. Markedly, the modified GNPs during ultrasonic treatment exhibited better dispersibility and grafting rate compared to others. Moreover, the experimental results confirmed that GNP concentration reached up to 0.32 mg mL-1 in aqueous solution and the grafting rate was 18.02%. The content of SMA had little effect on grafting rate; however, the ultrasonic duration significantly affected the process.
RESUMEN
1. Henagliflozin is a novel sodium-glucose transporter 2 inhibitor and presents a complementary therapy to metformin for patients with T2DM due to its insulin-independent mechanism of action. This study evaluated the potential pharmacokinetic drug-drug interaction between henagliflozin and metformin in healthy Chinese male subjects. 2. In open-label, single-center, single-arm, two-period, three-treatment self-control study, 12 subjects received 25 mg henagliflozin, 1000 mg metformin or the combination. Lack of PK interaction was defined as the ratio of geometric means and 90% confidence interval (CI) for combination: monotherapy being within the range of 0.80-1.25. 3. Co-administration of henagliflozin with metformin had no effect on henagliflozin area under the plasma concentration-time curve (AUC0-24) (GRM: 1.08; CI: 1.05, 1.10) and peak plasma concentration (Cmax) (GRM: 0.99; CI: 0.92, 1.07). Reciprocally, co-administration of metformin with henagliflozin had no clinically significant on metformin AUC0-24 (GRM: 1.09, CI: 1.02, 1.16) although there was an 11% increase in metformin Cmax (GRM 1.12; CI 1.02, 1.23). All monotherapies and combination therapy were well tolerated. 4. Henagliflozin can be co-administered with metformin without dose adjustment of either drug.
Asunto(s)
Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Interacciones Farmacológicas , Metformina/farmacología , Inhibidores del Cotransportador de Sodio-Glucosa 2 , Adulto , Pueblo Asiatico , China , Humanos , Masculino , Transportador 2 de Sodio-Glucosa/metabolismo , Adulto JovenRESUMEN
Cell wall biosynthesis is indispensable for pollen tube growth. Despite its importance to sexual reproduction, the molecular mechanisms of pollen tube wall biosynthesis remain poorly understood. Here, we report functional characterization of two putative Arabidopsis galacturonosyltransferase genes, GAUT13 and GAUT14, which are essential for pollen tube growth. GAUT13 and GAUT14 encode the proteins that share a high amino acid sequence identity and are located in the Golgi apparatus. The T-DNA insertion mutants, gaut13 and gaut14, did not exhibit any observable defects, but the gaut13 gaut14 double mutants were defective in pollen tube growth; 35.2-37.3% pollen tubes in the heterozygous double mutants were swollen and defective in elongation. The outer layer of the cell wall did not appear distinctly fibrillar in the double mutant pollen tubes. Furthermore, distribution of homogalacturonan labeled with JIM5 and JIM7 in the double mutant pollen tube wall was significantly altered compared to wild-type. Our results suggest that GAUT13 and GAUT14 function redundantly in pollen tube growth, possibly through participation in pectin biosynthesis of the pollen tube wall.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimología , Arabidopsis/crecimiento & desarrollo , Glucuronosiltransferasa/metabolismo , Tubo Polínico/crecimiento & desarrollo , Arabidopsis/citología , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas , Glucuronosiltransferasa/genética , Aparato de Golgi/metabolismo , Mutación , Pectinas/biosíntesis , Fenotipo , Transporte de ProteínasRESUMEN
REPRESSOR OF SILENCING 1 (ROS1) encodes a DNA demethylase that actively removes DNA methylation. Mutation in ROS1 leads to transcriptional gene silencing of a T-DNA locus that contains two genes, RD29A-LUC and 35S-NPTII, originally expressed in the C24 wild type. These units have different silencing regulation mechanisms: the former mechanism is dependent on small interfering RNA (siRNA)-directed DNA methylation, but the latter is not. We studied the latter gene silencing mechanism by screening the suppressors of the ros1 mutant using the silenced 35S-NPTII as a selection marker gene. The polalpha/incurvata2 (icu2) gene was isolated as one ros1 suppressor because its mutation leads to the reactivation of the silenced 35S-NPTII gene. POLalpha/ICU2 encodes a catalytic subunit of DNA polymerase alpha. Mutation of POLalpha/ICU2 did not affect DNA methylation, but reduced histone H3 Lys9 dimethylation (H3K9me2) modification in the 35S promoter. The polalpha mutation also influences the development of the shoot apical meristem, and delays the G2/M phase with high expression of a G2/M marker gene CycB1;1:GUS. Furthermore, the frequency of homologous recombination is greater in the polalpha/icu2 mutant than in the C24 wild type. Our results suggest that DNA polymerase alpha is involved in mediating epigenetic states and in DNA homologous recombination in Arabidopsis.
Asunto(s)
Proteínas de Arabidopsis/fisiología , Arabidopsis/metabolismo , ADN Polimerasa I/fisiología , Recombinación Genética/genética , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Northern Blotting , Southern Blotting , Western Blotting , Dominio Catalítico/genética , Dominio Catalítico/fisiología , Ciclo Celular/genética , Ciclo Celular/fisiología , Inmunoprecipitación de Cromatina , Metilación de ADN , ADN Polimerasa I/genética , ADN Polimerasa I/metabolismo , Regulación de la Expresión Génica de las Plantas/genética , Regulación de la Expresión Génica de las Plantas/fisiología , Mutación , Proteínas Nucleares/genética , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/crecimiento & desarrollo , Plantas Modificadas Genéticamente/metabolismo , Regiones Promotoras Genéticas/genética , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Many biological processes require the co-operative involvement of both microtubules and microfilaments; however, only a few proteins mediating the interaction between microtubules and microfilaments have been identified from plants. In the present study, a cotton kinesin GhKCH2, which contains a CH (calponin homology) domain at the N-terminus, was analysed in vitro and in vivo in order to understand its interaction with the two cytoskeletal elements. A specific antibody against GhKCH2 was prepared and used for immunolabelling experiments. Some GhKCH2 spots appeared along a few microtubules and microfilaments in developing cotton fibres. The His-tagged N-terminus of GhKCH2 (termed GhKCH2-N) could co-precipitate with microfilaments and strongly bind to actin filaments at a ratio of monomeric actin/GhKCH2-N of 1:0.6. The full-length GhKCH2 recombinant protein was shown to bind to and cross-link microtubules and microfilaments in vitro. A GFP-fusion protein GFP-GhKCH2 transiently overexpressed in Arabidopsis protoplasts decorated both microtubules and microfilaments, confirming the binding ability and specificities of GhKCH2 on microtubules and microfilaments in living plant cells. The results of the present study demonstrate that GhKCH2, a plant-specific microtubule-dependent motor protein, not only interacts with microtubules, but also strongly binds to microfilaments. The cytoskeletal dual-binding and cross-linking ability of GhKCH2 may be involved in the interaction between microtubules and microfilaments and the biological processes they co-ordinate together in cotton cells.