RESUMO
Critical periods are windows of heightened plasticity occurring during neurodevelopment. Alterations in neural activity during these periods can cause long-lasting changes in the structure, connectivity, and intrinsic excitability of neurons, which may contribute to the pathology of neurodevelopmental disorders. However, endogenous regulators of critical periods remain poorly defined. Here, we study this issue using a fruit fly (Drosophila) model of an early-onset movement disorder caused by BK potassium channel gain of function (BK GOF). Deploying a genetic method to place robust expression of GOF BK channels under spatiotemporal control, we show that adult-stage neuronal expression of GOF BK channels minimally disrupts fly movement. In contrast, limiting neuronal expression of GOF BK channels to a short window during late neurodevelopment profoundly impairs locomotion and limb kinematics in resulting adult flies. During this critical period, BK GOF perturbs synaptic localization of the active zone protein Bruchpilot and reduces excitatory neurotransmission. Conversely, enhancing neural activity specifically during development rescues motor defects in BK GOF flies. Collectively, our results reveal a critical developmental period for limb control in Drosophila that is influenced by BK channels and suggest that BK GOF causes movement disorders by disrupting activity-dependent aspects of synaptic development.
Assuntos
Proteínas de Drosophila , Drosophila melanogaster , Canais de Potássio Ativados por Cálcio de Condutância Alta , Locomoção , Animais , Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo , Canais de Potássio Ativados por Cálcio de Condutância Alta/genética , Drosophila melanogaster/fisiologia , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Neurônios/metabolismo , Neurônios/fisiologiaRESUMO
Engaging in behaviors that take advantage of one's personal strengths at work can promote employee flourishing in the workplace and mental health. Personal strengths use has thus gained increasing attention within occupational psychology and positive organizational scholarship. In this article, we first integrate work on personal strengths use with the latest developments in the job demands-resources theory (and its extensions) to develop a conceptual model explaining how and why personal strengths use on the job increases work engagement. Specifically, we propose that feelings of inspiration and meaningfulness explain the relationship between personal strengths use and work engagement. Second, we identify two mechanisms through which employees can amplify the benefits associated with personal strengths use at work; that is, we propose that the increased engagement associated with strengths use makes employees more likely to capitalize on the positive aspects of their work by engaging in work-family interpersonal capitalization and positive work reflection. Further, our model predicts that employees' psychological capital moderates the effects of personal strengths use. We tested our theoretical predictions in a sample of 160 full-time employees who provided ratings that comprise a three-level data set (person, week, and day) comprising 943 matched weekly ratings and 2,787 daily ratings. Our hypotheses were largely supported by these data. Implications for theory, practice, and future research are discussed. (PsycInfo Database Record (c) 2024 APA, all rights reserved).
Assuntos
Engajamento no Trabalho , Local de Trabalho , Humanos , Feminino , Masculino , Adulto , Local de Trabalho/psicologia , Pessoa de Meia-Idade , Satisfação no Emprego , Relações Interpessoais , Emprego/psicologiaRESUMO
Conventional research on gratitude has focused on the benefits of expressing or experiencing gratitude for the individual. However, recent theory and research have highlighted that there may too be benefits associated with receiving others' gratitude. Grounded in the Work-Home Resources model, we develop a conceptual model to understand whether, how, and for whom service providers (i.e., healthcare professionals) benefit from receiving service beneficiaries' (i.e., patients) gratitude in their daily work. We hypothesize that perceived gratitude from service beneficiaries enhances service providers' relational energy at work, which spills over to benefit their family lives later in the day. In addition, we hypothesize that the effect of gratitude on relational energy and its subsequent spillover effect to the family are contingent on employees' occupational identity. Two experience sampling studies with data collected from healthcare professionals and their spouses for two consecutive weeks (each) provided support for our hypothesized model. We conclude by discussing the theoretical and practical implications of our work. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
Assuntos
Relações Familiares , Cônjuges , Avaliação Momentânea Ecológica , HumanosRESUMO
The Drosophila model has been invaluable for the study of neurological function and for understanding the molecular and cellular mechanisms that underlie neurodegeneration. While fly techniques for the manipulation and study of neuronal subsets have grown increasingly sophisticated, the richness of the resultant behavioral phenotypes has not been captured at a similar detail. To be able to study subtle fly leg movements for comparison amongst mutants requires the ability to automatically measure and quantify high-speed and rapid leg movements. Hence, we developed a machine-learning algorithm for automated leg claw tracking in freely walking flies, Feature Learning-based Limb segmentation and Tracking (FLLIT). Unlike most deep learning methods, FLLIT is fully automated and generates its own training sets without a need for user annotation, using morphological parameters built into the learning algorithm. This article describes an in depth protocol for carrying out gait analysis using FLLIT. It details the procedures for camera setup, arena construction, video recording, leg segmentation and leg claw tracking. It also gives an overview of the data produced by FLLIT, which includes raw tracked body and leg positions in every video frame, 20 gait parameters, 5 plots and a tracked video. To demonstrate the use of FLLIT, we quantify relevant diseased gait parameters in a fly model of Spinocerebellar ataxia 3.
Assuntos
Extremidades/fisiologia , Aprendizado de Máquina , Movimento , Gravação em Vídeo , Animais , Automação , Drosophila , Análise da MarchaRESUMO
With the rise of jobs in the health care sector, research on emotional labor has become of increasing importance. In this study, we follow calls for scholars to include authentic emotional displays alongside the more traditionally examined emotional labor strategies (surface and deep acting) when examining the effects of employees' emotional performance at work. We theorize that dispositional empathy is an individual difference variable that influences whether and how employees regulate their emotional displays at work, and examine the indirect relationships between dispositional empathy and employees' self-reported job satisfaction, and objectively measured job performance and sickness absenteeism, through these emotional displays. Additionally, we examine how different types of job stressors (challenge and hindrance stressors) act as boundary conditions for the relationships of empathy with emotional displays and employee outcomes. Results from a study of 156 employees in a public hospital mostly supported our theoretical model. Implications for theory and practice are discussed. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
Assuntos
Regulação Emocional , Empatia , Emprego , Satisfação no Emprego , Modelos Psicológicos , Comportamento Social , Desempenho Profissional , Adulto , Feminino , Humanos , Masculino , Recursos Humanos em HospitalRESUMO
Some neurodegenerative diseases, like Parkinsons Disease (PD) and Spinocerebellar ataxia 3 (SCA3), are associated with distinct, altered gait and tremor movements that are reflective of the underlying disease etiology. Drosophila melanogaster models of neurodegeneration have illuminated our understanding of the molecular mechanisms of disease. However, it is unknown whether specific gait and tremor dysfunctions also occur in fly disease mutants. To answer this question, we developed a machine-learning image-analysis program, Feature Learning-based LImb segmentation and Tracking (FLLIT), that automatically tracks leg claw positions of freely moving flies recorded on high-speed video, producing a series of gait measurements. Notably, unlike other machine-learning methods, FLLIT generates its own training sets and does not require user-annotated images for learning. Using FLLIT, we carried out high-throughput and high-resolution analysis of gait and tremor features in Drosophila neurodegeneration mutants for the first time. We found that fly models of PD and SCA3 exhibited markedly different walking gait and tremor signatures, which recapitulated characteristics of the respective human diseases. Selective expression of mutant SCA3 in dopaminergic neurons led to a gait signature that more closely resembled those of PD flies. This suggests that the behavioral phenotype depends on the neurons affected rather than the specific nature of the mutation. Different mutations produced tremors in distinct leg pairs, indicating that different motor circuits were affected. Using this approach, fly models can be used to dissect the neurogenetic mechanisms that underlie movement disorders.
Assuntos
Análise da Marcha/métodos , Marcha/fisiologia , Processamento de Imagem Assistida por Computador/métodos , Animais , Modelos Animais de Doenças , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/anatomia & histologia , Drosophila melanogaster/fisiologia , Extremidades , Processamento de Imagem Assistida por Computador/instrumentação , Doença de Machado-Joseph , Aprendizado de Máquina , Movimento/fisiologia , Doenças Neurodegenerativas/genética , Doenças Neurodegenerativas/fisiopatologia , Doença de ParkinsonRESUMO
Glutamate is a ubiquitous neurotransmitter, mediating information flow between neurons. Defects in the regulation of glutamatergic transmission can result in glutamate toxicity, which is associated with neurodegeneration. Interestingly, glutamate receptors are expressed in glia, but little is known about their function, and the effects of their misregulation, in these non-neuronal cells. Here, we report a glio-protective role for Drosophila mir-263a mediated by its regulation of glutamate receptor levels in glia. mir-263a mutants exhibit a pronounced movement defect due to aberrant overexpression of CG5621/Grik, Nmdar1, and Nmdar2. mir-263a mutants exhibit excitotoxic death of a subset of astrocyte-like and ensheathing glia in the CNS. Glial-specific normalization of glutamate receptor levels restores cell numbers and suppresses the movement defect. Therefore, microRNA-mediated regulation of glutamate receptor levels protects glia from excitotoxicity, ensuring CNS health. Chronic low-level glutamate receptor overexpression due to mutations affecting microRNA (miRNA) regulation might contribute to glial dysfunction and CNS impairment.
Assuntos
Drosophila melanogaster/genética , Ácido Glutâmico/toxicidade , MicroRNAs/metabolismo , Neuroglia/metabolismo , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Morte Celular/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Drosophila melanogaster/metabolismo , Feminino , Glutamatos/metabolismo , Potenciais da Membrana/efeitos dos fármacos , MicroRNAs/genética , Movimento , Mutação/genética , Neuroglia/efeitos dos fármacos , Neuroglia/patologia , Fenótipo , Receptores de Glutamato/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
MicroRNAs play important roles in a large variety of biological systems and processes through their regulation of target mRNA expression, and show promise as clinical biomarkers. However, their small size presents challenges for tagging or direct detection. Innovation in techniques to sense and quantify microRNAs may aid research into novel aspects of microRNA biology and contribute to the development of diagnostics. By introducing an additional stem loop into the fluorescent RNA Spinach and altering its 3' and 5' ends, we have generated a new RNA, Pandan, that functions as the basis for a microRNA sensor. Pandan contains two sequence-variable stem loops that encode complementary sequence for a target microRNA of interest. In its sensor form, it requires the binding of a target microRNA in order to reconstitute the RNA scaffold for fluorophore binding and fluorescence. Binding of the target microRNA resulted in large changes in fluorescence intensity. The median fold change in fluorescence observed for the sensors tested was â¼50-fold. Pandan RNA sensors exhibit good signal-to-noise ratios, and can detect their target microRNAs within complex RNA mixtures.
Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , MicroRNAs/análise , Compostos de Benzil/metabolismo , Fluorescência , Corantes Fluorescentes , Imidazolinas/metabolismo , MicroRNAs/química , Conformação de Ácido NucleicoRESUMO
The control of self-renewal and differentiation of neural stem and progenitor cells is a crucial issue in stem cell and cancer biology. Drosophila type II neuroblast lineages are prone to developing impaired neuroblast homeostasis if the limited self-renewing potential of intermediate neural progenitors (INPs) is unrestrained. Here, we demonstrate that Drosophila SWI/SNF chromatin remodeling Brahma (Brm) complex functions cooperatively with another chromatin remodeling factor, Histone deacetylase 3 (HDAC3) to suppress the formation of ectopic type II neuroblasts. We show that multiple components of the Brm complex and HDAC3 physically associate with Earmuff (Erm), a type II-specific transcription factor that prevents dedifferentiation of INPs into neuroblasts. Consistently, the predicted Erm-binding motif is present in most of known binding loci of Brm. Furthermore, brm and hdac3 genetically interact with erm to prevent type II neuroblast overgrowth. Thus, the Brm-HDAC3-Erm repressor complex suppresses dedifferentiation of INPs back into type II neuroblasts. DOI: http://dx.doi.org/10.7554/eLife.01906.001.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Desdiferenciação Celular , Linhagem da Célula , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Histona Desacetilases/metabolismo , Células-Tronco Neurais/metabolismo , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , Animais , Animais Geneticamente Modificados , Sítios de Ligação , Proteínas de Ciclo Celular/genética , Linhagem Celular , Proteínas de Drosophila/genética , Drosophila melanogaster/citologia , Drosophila melanogaster/genética , Regulação da Expressão Gênica , Histona Desacetilases/genética , Complexos Multiproteicos , Ligação Proteica , Interferência de RNA , Transdução de Sinais , Transativadores/genética , Fatores de Transcrição/genética , TransfecçãoRESUMO
Drosophila larval brain neuroblasts divide asymmetrically to balance between self-renewal and differentiation. Here, we demonstrate that the SCF(Slimb) E3 ubiquitin ligase complex, which is composed of Cul1, SkpA, Roc1a and the F-box protein Supernumerary limbs (Slimb), inhibits ectopic neuroblast formation and regulates asymmetric division of neuroblasts. Hyperactivation of Akt leads to similar neuroblast overgrowth and defects in asymmetric division. Slimb associates with Akt in a protein complex, and SCF(S)(limb) acts through SAK and Akt to inhibit neuroblast overgrowth. Moreover, Beta-transducin repeat containing, the human ortholog of Slimb, is frequently deleted in highly aggressive gliomas, suggesting a conserved tumor suppressor-like function.
Assuntos
Divisão Celular Assimétrica , Proteínas de Ciclo Celular/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Células-Tronco Neurais/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Drosophila/crescimento & desenvolvimento , Proteínas de Drosophila/genética , Células-Tronco Neurais/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transducina/metabolismo , Ubiquitina-Proteína Ligases/genéticaRESUMO
Aging is a key risk factor in neurodegenerative disease; however, little is known about cellular pathways that mediate age-associated degeneration of the brain. The Bonini lab has identified a conserved microRNA, miR-34, that plays a neuroprotective role in the aging Drosophila brain and suggests that it functions in temporal control of gene expression.
Assuntos
Envelhecimento , Encéfalo/patologia , Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , MicroRNAs/metabolismo , Doenças Neurodegenerativas/metabolismo , Animais , Comportamento Animal/fisiologia , Encéfalo/metabolismo , Senescência Celular , Drosophila/genética , Proteínas de Drosophila/genética , MicroRNAs/genética , Doenças Neurodegenerativas/genética , Fatores de Risco , Fatores de Tempo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Uncovering the molecular mechanisms of eye development is crucial for understanding the embryonic morphogenesis of complex structures, as well as for the establishment of novel biomedical approaches to address birth defects and injuries of the visual system. Here, we characterize change in transmembrane voltage potential (V(mem)) as a novel biophysical signal for eye induction in Xenopus laevis. During normal embryogenesis, a striking hyperpolarization demarcates a specific cluster of cells in the anterior neural field. Depolarizing the dorsal lineages in which these cells reside results in malformed eyes. Manipulating V(mem) of non-eye cells induces well-formed ectopic eyes that are morphologically and histologically similar to endogenous eyes. Remarkably, such ectopic eyes can be induced far outside the anterior neural field. A Ca(2+) channel-dependent pathway transduces the V(mem) signal and regulates patterning of eye field transcription factors. These data reveal a new, instructive role for membrane voltage during embryogenesis and demonstrate that V(mem) is a crucial upstream signal in eye development. Learning to control bioelectric initiators of organogenesis offers significant insight into birth defects that affect the eye and might have significant implications for regenerative approaches to ocular diseases.
Assuntos
Indução Embrionária/fisiologia , Olho/embriologia , Potenciais da Membrana/fisiologia , Xenopus laevis/embriologia , Animais , Canais de Cálcio/metabolismo , Cumarínicos , Etanolaminas , Hibridização In Situ , Microscopia de Fluorescência , Fatores de Transcrição/metabolismoRESUMO
Consistent left-right asymmetry requires specific ion currents. We characterize a novel laterality determinant in Xenopus laevis: the ATP-sensitive K(+)-channel (K(ATP)). Expression of specific dominant-negative mutants of the Xenopus Kir6.1 pore subunit of the K(ATP) channel induced randomization of asymmetric organ positioning. Spatio-temporally controlled loss-of-function experiments revealed that the K(ATP) channel functions asymmetrically in LR patterning during very early cleavage stages, and also symmetrically during the early blastula stages, a period when heretofore largely unknown events transmit LR patterning cues. Blocking K(ATP) channel activity randomizes the expression of the left-sided transcription of Nodal. Immunofluorescence analysis revealed that XKir6.1 is localized to basal membranes on the blastocoel roof and cell-cell junctions. A tight junction integrity assay showed that K(ATP) channels are required for proper tight junction function in early Xenopus embryos. We also present evidence that this function may be conserved to the chick, as inhibition of K(ATP) in the primitive streak of chick embryos randomizes the expression of the left-sided gene Sonic hedgehog. We propose a model by which K(ATP) channels control LR patterning via regulation of tight junctions.
Assuntos
Padronização Corporal , Embrião de Galinha/crescimento & desenvolvimento , Canais KATP/fisiologia , Xenopus laevis/embriologia , Animais , Blastômeros/metabolismo , Potássio/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/fisiologia , Junções Íntimas/fisiologiaRESUMO
Consistent left-right (LR) patterning is a clinically important embryonic process. However, key questions remain about the origin of asymmetry and its amplification across cell fields. Planar cell polarity (PCP) solves a similar morphogenetic problem, and although core PCP proteins have yet to be implicated in embryonic LR asymmetry, studies of mutations affecting planar polarity, together with exciting new data in cell and developmental biology, provide a new perspective on LR patterning. Here we propose testable models for the hypothesis that LR asymmetry propagates as a type of PCP that imposes coherent orientation onto cell fields, and that the cue that orients this polarization is a chiral intracellular structure.
Assuntos
Padronização Corporal/fisiologia , Polaridade Celular/fisiologia , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Modelos Biológicos , Animais , Drosophila/embriologia , Drosophila/fisiologia , Transdução de Sinais/fisiologia , Xenopus/embriologia , Xenopus/fisiologiaRESUMO
Left-right patterning is a fascinating problem of morphogenesis, linking evolutionary and cellular signaling mechanisms across many levels of organization. In the past 15 years, enormous progress has been made in elucidating the molecular details of this process in embryos of several model species. While many outside the field seem to believe that the fundamental aspects of this pathway are now solved, workers on asymmetry are faced with considerable uncertainties over the details of specific mechanisms, a lack of conceptual unity of mechanisms across phyla, and important questions that are not being pursued in any of the popular model systems. Here, we suggest that data from clinical syndromes, cryptic asymmetries, and bilateral gynandromorphs, while not figuring prominently in the mainstream work on LR asymmetry, point to crucial and fundamental gaps of knowledge about asymmetry. We identify 12 big questions that provide exciting opportunities for fundamental new advances in this field.
Assuntos
Padronização Corporal , Animais , Embrião de Mamíferos/embriologia , Embrião de Mamíferos/metabolismo , Embrião não Mamífero/embriologia , Embrião não Mamífero/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Mutação/genéticaRESUMO
Consistent laterality is a fascinating problem, and study of the Xenopus embryo has led to molecular characterization of extremely early steps in left-right patterning: bioelectrical signals produced by ion pumps functioning upstream of asymmetric gene expression. Here, we reveal a number of novel aspects of the H+/K+-ATPase module in chick and frog embryos. Maternal H+/K+-ATPase subunits are asymmetrically localized along the left-right, dorso-ventral, and animal-vegetal axes during the first cleavage stages, in a process dependent on cytoskeletal organization. Using a reporter domain fused to molecular motors, we show that the cytoskeleton of the early frog embryo can provide asymmetric, directional information for subcellular transport along all three axes. Moreover, we show that the Kir4.1 potassium channel, while symmetrically expressed in a dynamic fashion during early cleavages, is required for normal LR asymmetry of frog embryos. Thus, Kir4.1 is an ideal candidate for the K+ ion exit path needed to allow the electroneutral H+/K+-ATPase to generate voltage gradients. In the chick embryo, we show that H+/K+-ATPase and Kir4.1 are expressed in the primitive streak, and that the known requirement for H+/K+-ATPase function in chick asymmetry does not function through effects on the circumferential expression pattern of Connexin43. These data provide details crucial for the mechanistic modeling of the physiological events linking subcellular processes to large-scale patterning and suggest a model where the early cytoskeleton sets up asymmetric ion flux along the left-right axis as a system of planar polarity functioning orthogonal to the apical-basal polarity of the early blastomeres.