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Males have finite resources to spend on reproduction. Thus, males rely on a 'time investment strategy' to maximize their reproductive success. For example, male Drosophila melanogaster extends their mating duration when surrounded by conditions enriched with rivals. Here we report a different form of behavioral plasticity whereby male fruit flies exhibit a shortened duration of mating when they are sexually experienced; we refer to this plasticity as 'shorter-mating-duration (SMD)'. SMD is a plastic behavior and requires sexually dimorphic taste neurons. We identified several neurons in the male foreleg and midleg that express specific sugar and pheromone receptors. Using a cost-benefit model and behavioral experiments, we further show that SMD behavior exhibits adaptive behavioral plasticity in male flies. Thus, our study delineates the molecular and cellular basis of the sensory inputs required for SMD; this represents a plastic interval timing behavior that could serve as a model system to study how multisensory inputs converge to modify interval timing behavior for improved adaptation.
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Drosophila melanogaster , Feromonas , Animales , Masculino , Drosophila melanogaster/genética , Gusto , Conducta Sexual Animal/fisiología , Reproducción , DrosophilaRESUMEN
Similar to the human brain, Drosophila glia may well be divided into several subtypes that each carries out specific functions. Glial GPCRs play key roles in crosstalk between neurons and glia. Drosophila Lgr4 (dLgr4) is a human relaxin receptor homolog involved in angiogenesis, cardiovascular regulation, collagen remodeling, and wound healing. A recent study suggests that ilp7 might be the ligand for Lgr4 and regulates escape behavior of Drosophila larvae. Here we demonstrate that Drosophila Lgr4 expression in glial cells, not neurons, is necessary for early development, adult behavior, and lifespan. Reducing the Lgr4 level in glial cells disrupts Drosophila development, while knocking down other LGR family members in glia has no impact. Adult-specific knockdown of Lgr4 in glia but not neurons reduce locomotion, male reproductive success, and animal longevity. The investigation of how glial expression of Lgr4 contributes to this behavioral alteration will increase our understanding of how insulin signaling via glia selectively modulates neuronal activity and behavior.
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Proteínas de Drosophila , Drosophila , Neuroglía , Receptores Acoplados a Proteínas G , Animales , Masculino , Encéfalo , Neuronas , Receptores de Neuropéptido , Receptores Acoplados a Proteínas G/genética , Proteínas de Drosophila/genéticaRESUMEN
The roles of brain asymmetry in Drosophila are diverse, encompassing the regulation of behavior, the creation of memory, neurodevelopment, and evolution. A comprehensive examination of the Drosophila brain has the potential to enhance our understanding of the functional significance of brain asymmetry in cognitive and behavioral processes, as well as its role in evolutionary perspectives. This study explores the influence of brain asymmetry on interval timing behaviors in Drosophila, with a specific focus on the asymmetric body (AB) structure. Despite being bilaterally symmetric, the AB exhibits functional asymmetry and is located within the central complex of the fly brain. Interval timing behaviors, such as rival-induced prolonged mating duration: longer mating duration behavior (LMD) and sexual experience-mediated shorter mating duration behavior (SMD), are essential for Drosophila. We utilize genetic manipulations to selectively activate or inhibit AB neurons and evaluates their impact on LMD and SMD behaviors. The results indicate that specific populations of AB neurons play unique roles in orchestrating these interval timing behaviors. Notably, inhibiting GAL4R38D01-labeled AB neurons disrupts both LMD and SMD, while GAL4R42C09 neuron inhibition affects only LMD. Moreover, hyperexcitation of GAL4R72A10-labeled AB neurons perturbs SMD. Our study identifies NetrinB (NetB) and Abdominal-B (Abd-B) are important genes for AB neurons in LMD and highlights the role of 5-HT1B neurons in generating LMD through peptidergic Pigment-dispersing factor (PDF) signaling. In summary, this study underscores the importance of AB neuron asymmetry in mediating interval timing behaviors and provides insights into the underlying mechanisms of memory formation and function in Drosophila.
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Encéfalo , Proteínas de Drosophila , Drosophila melanogaster , Neuronas , Conducta Sexual Animal , Animales , Drosophila melanogaster/fisiología , Drosophila melanogaster/genética , Conducta Sexual Animal/fisiología , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Neuronas/metabolismo , Neuronas/fisiología , Masculino , Encéfalo/fisiología , Encéfalo/metabolismo , FemeninoRESUMEN
INTRODUCTION: Accurate implant positioning, tailored to the phenotype and unique biomechanics of each patient is the single most important objective in achieving stability in THA and maximise range of motion. The spine-pelvis-hip construct functions as a single unit adapting to postural changes. It is widely accepted in the literature that no universaltarget exists and variations in spinopelvic mobility mandate adjustments to the surgical plan; thus bringing to the fore the concept of personalised, functional component positioning. METHODS: This manuscript aims to outline the challenges posed by spinopelvic imbalance and present a reproducible, stepwise approach to achieve functional-component positioning. We also present the one-year functional outcomes and Patient Reported Outcome Measures of a prospective cohort operated with this technique. RESULTS AND CONCLUSION: Robotic-arm assisted Total Hip Arthroplasty has facilitated enhanced planning based on the patient's phenotype and evidence suggests it results in more reproducible and accurate implant positioning. Preservation of offset, avoiding leg-length discrepancy, accurate restoration of the centre of rotation and accomplishing the combinedversion target are very important parameters in Total Hip Arthroplasty that affect post-operative implant longevity, patient satisfaction and clinical outcomes.
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Artroplastia de Reemplazo de Cadera , Procedimientos Quirúrgicos Robotizados , Artroplastia de Reemplazo de Cadera/efectos adversos , Artroplastia de Reemplazo de Cadera/métodos , Procedimientos Quirúrgicos Robotizados/efectos adversos , Procedimientos Quirúrgicos Robotizados/métodos , Estudios Prospectivos , Satisfacción del Paciente , PelvisRESUMEN
Robotic-arm-assisted total hip arthroplasty (RoTHA) offers the opportunity to improve the implant positioning and restoration of native hip mechanics. The concept of individualised, functional implant positioning and how it relates to spinopelvic imbalance is an important yet rather novel consideration in THA. There is mounting evidence that a significant percentage of dislocations occur within the perceived "safe zones"; hence, in the challenging subset of patients with a stiff spinopelvic construct, it is imperative to employ individualised component positioning based on the patients' phenotype. Restoring the native centre of rotation, preserving offset, achieving the desired combined anteversion and avoiding leg length inequality are all very important surgeon-controlled variables that have been shown to be associated with postoperative outcomes. The latest version of the software has a feature of virtual range of motion (VROM), which preoperatively identifies potential dynamic causes of impingement that can cause instability. This review presents the workflow of RoTHA, especially focusing on pragmatic solutions to tackle the challenge of spinopelvic imbalance. Furthermore, it presents an overview of the existing evidence concerning RoTHA and touches upon future direction.
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Artroplastia de Reemplazo de Cadera , Procedimientos Quirúrgicos Robotizados , Flujo de Trabajo , Brazo , Rango del Movimiento ArticularRESUMEN
Background and Objectives: The current options for acute pain control of vertebral compression fracture include hard brace, vertebroplasty, early surgery, and analgesic injection. We hypothesize that the gray ramus communicans nerve block (GRNB) controls the acute pain experienced during vertebral compression fractures. This study assessed the time course of pain control after injection and evaluated the risk factors affecting pain control failure. Materials and methods: Sixty-three patients (24 male, 66.19 ± 15.17 y) with a thoracolumbar vertebral fracture at the T10-L5 spine, who presented to our hospital from November 2018 to October 2019, were included in this retrospective cohort study. GRNB was performed within 1 week of the trauma. The patients were followed up on days 3, 14, 30, 90, and 180 and assessed with the serial visual analog scale (VAS, resting and motion), Oswestry Low Back Disability (ODI) questionnaire, and Roland-Morris Disability Questionnaire (RDQ). The failure group was defined by the need for an additional block or cement injection after a single GRNB. The failure group's risk factors, such as body mass index, initial thoracolumbar injury classification and severity score, Kummel's disease, age, bone marrow density (BMD), and underlying disease, were analyzed. Results: The motion VAS score improved from preoperative to three months post-procedure, but the resting VAS was affected by the procedure for only three days. The quality of life index improved at postoperative six months. A lower BMD was the only risk that affected treatment failure in the logistic regression analysis (p = 0.0038). Conclusion: The effect of GRNB was maintained even at three months after trauma based on motion VAS results. The only risk factor identified for GRNB failure was lower BMD.
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Dolor Agudo , Fracturas por Compresión , Bloqueo Nervioso , Fracturas Osteoporóticas , Fracturas de la Columna Vertebral , Fracturas por Compresión/complicaciones , Fracturas por Compresión/cirugía , Humanos , Masculino , Fracturas Osteoporóticas/cirugía , Calidad de Vida , Estudios Retrospectivos , Fracturas de la Columna Vertebral/complicaciones , Fracturas de la Columna Vertebral/cirugía , Resultado del TratamientoRESUMEN
WTX encodes a tumor suppressor, frequently inactivated in Wilms tumor, with both plasma membrane and nuclear localization. WTX has been implicated in ß-catenin turnover, but its effect on nuclear proteins is unknown. We report an interaction between WTX and p53, derived from the unexpected observation of WTX, p53, and E1B 55K colocalization within the characteristic cytoplasmic body of adenovirus-transformed kidney cells. In other cells without adenovirus expression, the C-terminal domain of WTX binds to the DNA-binding domain of p53, enhances its binding to CBP, and increases CBP/p300-mediated acetylation of p53 at Lys 373/382. WTX knockdown accelerates CBP/p300 protein turnover and attenuates this modification of p53. In p53-reconstitution experiments, cell-cycle arrest, apoptosis, and p53 target-gene expression are suppressed by depletion of WTX. Together, these results suggest that WTX modulates p53 function, in part through regulation of its activator CBP/p300.
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Proteínas Adaptadoras Transductoras de Señales/fisiología , Proteína p53 Supresora de Tumor/metabolismo , Proteínas Supresoras de Tumor/fisiología , Factores de Transcripción p300-CBP/metabolismo , Acetilación , Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Células HEK293 , Humanos , Estabilidad Proteica , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismoRESUMEN
Colloidal InP quantum dots (QDs) have attracted a surge of interest as environmentally friendly light-emitters in downconversion liquid crystal displays and light-emitting diodes (LEDs). A ZnS shell on InP-based core QDs has helped achieve high photoluminescence (PL) quantum yield (QY) and stability. Yet, due to the difficulty in the growth of a thick ZnS shell without crystalline defects, InP-based core/shell QDs show inferior stability against QY drop compared to Cd chalcogenide precedents, e.g., CdSe/CdS core/thick-shell QDs. In this work, we demonstrate the synthesis of InP-based core/shell QDs coated with an Al-doped ZnS outer shell. QDs with an Al-doped shell exhibit remarkable improvement in thermal and air stability even when the shell thickness is below 2 nm, while the absorption and PL spectra, size, and crystal structure are nearly the same as the case of QDs with a pristine ZnS shell. X-ray photoelectron spectroscopy reveals that Al3+ in Al-doped QDs forms an Al-oxide layer at elevated temperature under ambient atmosphere. The as-formed Al-oxide layer blocks the access of external oxidative species penetrating into QDs and prevents QDs from oxidative degradation. We also trace the chemical pathway of the incorporation of Al3+ into ZnS lattice during the shell growth. Furthermore, we fabricate QD-LEDs using Al-doped and undoped QDs and compare the optoelectronic characteristics and stability.
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With the advent of the era of consumer-oriented displays and mobile devices, the importance of barrier film coatings for securing devices from oxygen or moisture penetration has become more salient. Recently developed approaches to generate gas barrier films in a combination of polyelectrolyte multilayer matrices and incorporated inorganic nanosheets have shown great potential in outperforming conventional gas barrier films. However, these films have the intrinsic drawback of vulnerability to brittleness and inability to stretch for flexible device applications. To overcome this issue, we present a method in which we prepare multilayered films of complementarily charged polyurethane and graphene oxide platelets using spin-assisted, layer-by-layer self-assembly to obtain well-stacked film structures. As a result, the multilayered, thin films deposited on a poly(ethylene terephthalate) (PET) substrate can exhibit significantly reduced oxygen penetration properties (â¼30 cc m-2 day-1 for the oxygen transmission rate) while still demonstrating large bending or stretching deformations. Therefore, the proposed approach in this study is anticipated to be extensively utilized for surface coating and protection of flexible and stretchable devices under various operating conditions.
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WTX encodes a tumor suppressor implicated in the pediatric kidney cancer Wilms tumor and in mesenchymal differentiation with potentially distinct functions in the cytoplasm, at the plasma membrane, and in the nucleus. Although modulating components of the WNT signaling pathway is a proposed function for cytoplasmic and membrane-bound WTX, its nuclear properties are not well understood. Here we report that the transcriptional corepressor TRIM28 is the major binding partner for nuclear WTX. WTX interacted with the coiled coil domain of TRIM28 required for its binding to Krüppel-associated box domains of transcription factors and for its chromatin recruitment through its own coiled coil and proline-rich domains. Knockdown of endogenous WTX reduced the recruitment of TRIM28 to a chromatinized reporter sequence and its ability to repress a target transcript. In mouse embryonic stem cells where TRIM28 plays a major role in repressing endogenous retroviruses and long interspersed elements, knockdown of either TRIM28 or WTX combined with single molecule RNA sequencing revealed a highly significant shared set of differentially regulated transcripts, including derepression of non-coding repetitive sequences and their neighboring protein encoding genes (p < 1e-20). In mesenchymal precursor cells, depletion of WTX and TRIM28 resulted in analogous ß-catenin-independent defects in adipogenic and osteogenic differentiation, and knockdown of WTX reduced TRIM28 binding to Pparγ promoter. Together, the physical and functional interaction between WTX and TRIM28 suggests that the nuclear fraction of WTX plays a role in epigenetic silencing, an effect that may contribute to its function as a regulator of cellular differentiation and tumorigenesis.
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Células Madre Embrionarias/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Represoras/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Adipogénesis , Animales , Línea Celular , Cromatina/genética , Cromatina/metabolismo , Células Madre Embrionarias/citología , Regulación de la Expresión Génica , Técnicas de Silenciamiento del Gen , Humanos , Neoplasias Renales/genética , Neoplasias Renales/metabolismo , Ratones , Proteínas Nucleares/genética , Mapas de Interacción de Proteínas , Proteínas Represoras/genética , Activación Transcripcional , Proteína 28 que Contiene Motivos Tripartito , Proteínas Supresoras de Tumor/genética , Tumor de Wilms/genética , Tumor de Wilms/metabolismoRESUMEN
In this work, we demonstrate that Ar gas flow can be optically detected using mechanical vibration of a semiconducting single-walled carbon nanotube (SWCNT) bundle as a platform. A change in the photoluminescence (PL) intensity was induced by out-of-focusing of the SWCNT bundle of interest due to vibration caused by the introduced gas stream, for which a gas flow control system was installed in an optical microscope. The PL intensity was found to change systemically with the Ar flow rates in a range of relatively large flow rate intervals [0.70 to 3.0 standard cubic liters per minute (SLM) with 0.1-0.5 SLM intervals] with a noticeable hysteresis. It was, however, difficult to obtain a detectable PL change in a range of very small flow rate intervals (0.67 to 0.70 SLM with a 0.01 SLM interval). The detailed results and underlying mechanism are discussed in detail.
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Argón/análisis , Nanotubos de Carbono , Semiconductores , Luminiscencia , Microscopía ElectrónicaRESUMEN
Male-male social interactions exert a substantial impact on the transcriptional regulation of genes associated with aggression and mating behavior in male Drosophila melanogaster. Throughout our comprehensive genetic screening of aggression-related genes, we identified that the majority of mutants for these genes are associated with rival-induced and visually-oriented mating behavior, longer-mating-duration (LMD). The majority of mutants with upregulated genes in single-housed males significantly altered LMD behavior but not copulation latency, suggesting a primary regulation of mating duration. Single-cell RNA sequencing revealed that LMD-related genes are predominantly co-expressed with male-specific genes like dsx and Cyp6a20 in specific cell populations, especially in cone cells. Functional validation confirmed the roles of these genes in mediating LMD. Expression of LMD genes like Cyp6a20, Cyp4d21, and CrzR was enriched in cone cells, with disruptions in cone cell-specific expression of CrzR and Cyp4d21 leading to disrupted LMD. We also identified a novel gene, CG10026/Macewindu, that reversed LMD when overexpressed in cone cells. These findings underscore the critical role of cone cells as a pivotal site for the expression of genes involved in the regulation of LMD behavior. This study provides valuable insights into the intricate mechanisms underlying complex sexual behaviors in Drosophila.
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The Drosophila melanogaster brain is a complex organ with various cell types, orchestrating the development, physiology, and behaviors of the fly. While each cell type in Drosophila brain is known to express a unique gene set, their complete genetic profile is still unknown. Advances in the RNA sequencing techniques at single-cell resolution facilitate identifying novel cell type markers and/or re-examining the specificity of the available ones. In this study, exploiting a single-cell RNA sequencing data of Drosophila optic lobe, we categorized the cells based on their expression pattern for known markers, then the genes with enriched expression in astrocytes were identified. CG11000 was identified as a gene with a comparable expression profile to the Eaat1 gene, an astrocyte marker, in every individual cell inside the Drosophila optic lobe and midbrain, as well as in the entire Drosophila brain throughout its development. Consistent with our bioinformatics data, immunostaining of the brains dissected from transgenic adult flies showed co-expression of CG11000 with Eaat1 in a set of single cells corresponding to the astrocytes in the Drosophila brain. Physiologically, inhibiting CG11000 through RNA interference disrupted the normal development of male D. melanogaster, while having no impact on females. Expression suppression of CG11000 in adult flies led to decreased locomotion activity and also shortened lifespan specifically in astrocytes, indicating the gene's significance in astrocytes. We designated this gene as 'deathstar' due to its crucial role in maintaining the star-like shape of glial cells, astrocytes, throughout their development into adult stage.
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Astrocitos , Proteínas de Drosophila , Drosophila melanogaster , Locomoción , Longevidad , Animales , Femenino , Masculino , Astrocitos/metabolismo , Astrocitos/citología , Encéfalo/metabolismo , Encéfalo/citología , Encéfalo/crecimiento & desarrollo , Drosophila melanogaster/genética , Drosophila melanogaster/crecimiento & desarrollo , Drosophila melanogaster/metabolismo , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Transportador 1 de Aminoácidos Excitadores/metabolismo , Transportador 1 de Aminoácidos Excitadores/genética , Longevidad/genéticaRESUMEN
This study investigated the effect of temperature on the aspect-ratio etching of SiO2 in CF4/H2/Ar plasma using patterned samples of a 200 nm trench in a low-temperature reactive-ion etching system. Lower temperatures resulted in higher etch rates and aspect ratios for SiO2. However, the plasma property was constant with the chuck temperature, indicated by the line intensity ratio from optical emission spectroscopy monitoring of the plasma. The variables obtained from the characterization of the etched profile for the 200 nm trench after etching were analyzed as a function of temperature. A reduction in the necking ratio affected the etch rate and aspect ratio of SiO2. The etching mechanism of the aspect ratio etching of SiO2 was discussed based on the results of the surface composition at necking via energy-dispersive X-ray spectroscopy with temperature. The results suggested that the neutral species reaching the etch front of SiO2 had a low sticking coefficient. The bowing ratio decreased with lowering temperature, indicating the presence of directional ions during etching. Therefore, a lower temperature for the aspect ratio etching of SiO2 could achieve a faster etch rate and a higher aspect ratio of SiO2 via the reduction of necking than higher temperatures.
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WNT signaling is fundamental in development and homeostasis, but how the Frizzled receptors (FZDs) propagate signaling remains enigmatic. Here, we present the cryo-EM structure of FZD4 engaged with the DEP domain of Dishevelled 2 (DVL2), a key WNT transducer. We uncover a distinct binding mode where the DEP finger-loop inserts into the FZD4 cavity to form a hydrophobic interface. FZD4 intracellular loop 2 (ICL2) additionally anchors the complex through polar contacts. Mutagenesis validates the structural observations. The DEP interface is highly conserved in FZDs, indicating a universal mechanism by which FZDs engage with DVLs. We further reveal that DEP mimics G-protein/ß-arrestin/GRK to recognize an active conformation of receptor, expanding current GPCR engagement models. Finally, we identify a distinct FZD4 dimerization interface. Our findings delineate the molecular determinants governing FZD/DVL assembly and propagation of WNT signaling, providing long-sought answers underlying WNT signal transduction.
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Proteínas Dishevelled , Receptores Frizzled , Vía de Señalización Wnt , Receptores Frizzled/metabolismo , Receptores Frizzled/química , Receptores Frizzled/genética , Proteínas Dishevelled/metabolismo , Proteínas Dishevelled/genética , Proteínas Dishevelled/química , Humanos , Células HEK293 , Unión Proteica , Microscopía por Crioelectrón , Modelos Moleculares , Dominios ProteicosRESUMEN
Vertebral osteomyelitis is a condition that predominantly affects older men with chronic comorbidities, such as diabetes, renal and hepatic failure, or immunosuppression. Symptoms develop insidiously and a high index of suspicion is required to diagnose the condition; this is achieved through serological testing and imaging. The mainstay of treatment is long-term antibiotic therapy, lasting a minimum of 6 weeks; however, surgical debridement with stabilisation is required when conservative treatment is proving ineffective and infection progresses. It is critically important that sufficient treatment is provided for those experiencing vertebral osteomyelitis, as not doing so could lead to severe neurological compromise and death.
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Discitis , Osteomielitis , Masculino , Humanos , Adulto , Anciano , Antibacterianos/uso terapéutico , Osteomielitis/diagnóstico , Osteomielitis/terapiaRESUMEN
The western honeybee Apis mellifera L., a vital crop pollinator and producer of honey and royal jelly, faces numerous threats including diseases, chemicals, and mite infestations, causing widespread concern. While extensive research has explored the link between gut microbiota and their hosts. However, the impact of Varroa destructor infestation remains understudied. In this study, we employed massive parallel amplicon sequencing assays to examine the diversity and structure of gut microbial communities in adult bee groups, comparing healthy (NG) and Varroa-infested (VG) samples. Additionally, we analyzed Varroa-infested hives to assess the whole body of larvae. Our results indicated a notable prevalence of the genus Bombella in larvae and the genera Gillamella, unidentified Lactobacillaceae, and Snodgrassella in adult bees. However, no statistically significant difference was observed between NG and VG. Furthermore, our PICRUSt analysis demonstrated distinct KEGG classification patterns between larval and adult bee groups, with larvae displaying a higher abundance of genes involved in cofactor and vitamin production. Notably, despite the complex nature of the honeybee bacterial community, methanogens were found to be present in low abundance in the honeybee microbiota.
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Microbioma Gastrointestinal , Microbiota , Infestaciones por Ácaros , Varroidae , Animales , Abejas , Infestaciones por Ácaros/epidemiología , Larva , Microbiota/genética , Microbioma Gastrointestinal/genéticaRESUMEN
WTX encodes a tumor suppressor gene inactivated in Wilms tumor and recently implicated in WNT signaling through enhancement of cytoplasmic beta-catenin (CTNNB1) degradation. Here, we report that WTX translocates to the nucleus, a property that is modified by an endogenous splicing variant and is modulated by a nuclear export inhibitor. WTX is present in distinct subnuclear structures and co-localizes with the paraspeckle marker p54NRB/NONO, suggesting a role in transcriptional regulation. Notably, WTX binds WT1, another Wilms tumor suppressor and stem cell marker that encodes a zinc-finger transcription factor, and enhances WT1-mediated transcription of Amphiregulin, an endogenous target gene. Together, these observations suggest a role for WTX in nuclear pathways implicated in the transcriptional regulation of cellular differentiation programs.
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Transporte Activo de Núcleo Celular , Proteínas Supresoras de Tumor/metabolismo , Proteínas WT1/metabolismo , Proteínas Adaptadoras Transductoras de Señales , Anfirregulina , Línea Celular , Familia de Proteínas EGF , Regulación de la Expresión Génica , Glicoproteínas/genética , Humanos , Péptidos y Proteínas de Señalización Intercelular/genética , Unión Proteica , Isoformas de Proteínas , Factores de Transcripción , Transcripción Genética , Transfección , Proteínas Supresoras de Tumor/genética , Proteínas WT1/análisisRESUMEN
Carbon nanotubes (CNTs), having either metallic or semiconducting properties depending on their chirality, are advanced materials that can be used for different devices and materials (e.g., fuel cells, transistors, solar cells, reinforced materials, and medical materials) due to their excellent electrical conductivity, mechanical strength, and thermal conductivity. Single-walled CNTs (SWNTs) have received special attention due to their outstanding electrical and optical properties; however, the inability to selectively synthesize specific types of CNTs has been a major obstacle for their commercialization. Therefore, researchers have studied different methods for the separation of SWNTs based on their electrical and optical properties. Gel chromatography methods enable the large-scale separation of metallic/semiconducting (m/s) SWNTs and single-chirality SWNTs with specific bandgaps. The core principle of gel chromatography-based SWNT separation is the interaction between the SWNTs and gels, which depends on the unique electrical properties of the former. Controlled pore glass, silica gel, agarose-based gel, and allyl dextran-based gel have been exploited as mediums for gel chromatography. In this paper, the interaction between SWNTs and gels and the different gel chromatography-based SWNT separation technologies are introduced. This paper can serve as a reference for researchers who plan to separate SWNTs with gel chromatography.
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A laboratory-scale experiment was conducted to reproduce plasma with properties similar to re-entry plasma and measure the plasma density using a microwave reflectometer system. To reproduce a similar re-entry plasma, a high-temperature refractory anode vacuum arc plasma method was used among arc plasma discharge methods, and arc plasma having high temperature, high speed, and high-density plasma characteristics was discharged inside a vacuum chamber. A hot refractory anode made of tungsten was used to show high-temperature plasma characteristics, and high-density plasma characteristics were demonstrated using re-evaporation around the anode. In addition, high-speed plasma characteristics were exhibited using a brass cathode. This kind of arc plasma discharge has a high temperature and is characterized by high fluctuation. It was determined that a microwave reflectometer system with good spatial resolution and non-invasiveness would be suitable to measure plasma with these characteristics. The reflection coefficient was measured using a reflector system by comparing the voltage between the traveling wave applied to the plasma and the reflected wave reflected by the plasma, and the technique of analyzing the plasma density using the difference between these reflection coefficients was used. In this study, the plasma density according to the pressure change was typically measured as 1012-1013 cm-3, which showed a similar tendency to the result of measuring the actual re-entry plasma density.