RESUMO
Animals continuously detect information via multiple sensory channels, like vision and hearing, and integrate these signals to realise faster and more accurate decisions; a fundamental neural computation known as multisensory integration. A widespread view of this process is that multimodal neurons linearly fuse information across sensory channels. However, does linear fusion generalise beyond the classical tasks used to explore multisensory integration? Here, we develop novel multisensory tasks, which focus on the underlying statistical relationships between channels, and deploy models at three levels of abstraction: from probabilistic ideal observers to artificial and spiking neural networks. Using these models, we demonstrate that when the information provided by different channels is not independent, linear fusion performs sub-optimally and even fails in extreme cases. This leads us to propose a simple nonlinear algorithm for multisensory integration which is compatible with our current knowledge of multimodal circuits, excels in naturalistic settings and is optimal for a wide class of multisensory tasks. Thus, our work emphasises the role of nonlinear fusion in multisensory integration, and provides testable hypotheses for the field to explore at multiple levels: from single neurons to behaviour.
Assuntos
Modelos Neurológicos , Dinâmica não Linear , Animais , Algoritmos , Biologia Computacional/métodos , Neurônios/fisiologia , Humanos , Redes Neurais de ComputaçãoRESUMO
Advancing from gene discovery in autism spectrum disorders (ASDs) to the identification of biologically relevant mechanisms remains a central challenge. Here, we perform parallel in vivo functional analysis of 10 ASD genes at the behavioral, structural, and circuit levels in zebrafish mutants, revealing both unique and overlapping effects of gene loss of function. Whole-brain mapping identifies the forebrain and cerebellum as the most significant contributors to brain size differences, while regions involved in sensory-motor control, particularly dopaminergic regions, are associated with altered baseline brain activity. Finally, we show a global increase in microglia resulting from ASD gene loss of function in select mutants, implicating neuroimmune dysfunction as a key pathway relevant to ASD biology.
Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Animais , Transtorno Autístico/genética , Peixe-Zebra/genética , Encéfalo , Transtorno do Espectro Autista/genética , Mapeamento EncefálicoRESUMO
Hundreds of human genes are associated with neurological diseases, but translation into tractable biological mechanisms is lagging. Larval zebrafish are an attractive model to investigate genetic contributions to neurological diseases. However, current CRISPR-Cas9 methods are difficult to apply to large genetic screens studying behavioural phenotypes. To facilitate rapid genetic screening, we developed a simple sequencing-free tool to validate gRNAs and a highly effective CRISPR-Cas9 method capable of converting >90% of injected embryos directly into F0 biallelic knockouts. We demonstrate that F0 knockouts reliably recapitulate complex mutant phenotypes, such as altered molecular rhythms of the circadian clock, escape responses to irritants, and multi-parameter day-night locomotor behaviours. The technique is sufficiently robust to knockout multiple genes in the same animal, for example to create the transparent triple knockout crystal fish for imaging. Our F0 knockout method cuts the experimental time from gene to behavioural phenotype in zebrafish from months to one week.
Assuntos
Sistemas CRISPR-Cas , Técnicas de Inativação de Genes , Testes Genéticos/métodos , RNA Guia de Cinetoplastídeos/análise , Peixe-Zebra/genética , Animais , Comportamento Animal , Embrião não Mamífero , Fenótipo , Peixe-Zebra/embriologiaRESUMO
Mutations in the SNX14 gene cause spinocerebellar ataxia, autosomal recessive 20 (SCAR20) in both humans and dogs. Studies implicating the phenotypic consequences of SNX14 mutations to be consequences of subcellular disruption to autophagy and lipid metabolism have been limited to in vitro investigation of patient-derived dermal fibroblasts, laboratory engineered cell lines and developmental analysis of zebrafish morphants. SNX14 homologues Snz (Drosophila) and Mdm1 (yeast) have also been conducted, demonstrated an important biochemical role during lipid biogenesis. In this study we report the effect of loss of SNX14 in mice, which resulted in embryonic lethality around mid-gestation due to placental pathology that involves severe disruption to syncytiotrophoblast cell differentiation. In contrast to other vertebrates, zebrafish carrying a homozygous, maternal zygotic snx14 genetic loss-of-function mutation were both viable and anatomically normal. Whilst no obvious behavioural effects were observed, elevated levels of neutral lipids and phospholipids resemble previously reported effects on lipid homeostasis in other species. The biochemical role of SNX14 therefore appears largely conserved through evolution while the consequences of loss of function varies between species. Mouse and zebrafish models therefore provide valuable insights into the functional importance of SNX14 with distinct opportunities for investigating its cellular and metabolic function in vivo.
Assuntos
Viabilidade Fetal/genética , Metabolismo dos Lipídeos/genética , Placenta/anormalidades , Nexinas de Classificação/genética , Ataxias Espinocerebelares/genética , Animais , Animais Geneticamente Modificados , Diferenciação Celular/genética , Desenvolvimento Embrionário/genética , Feminino , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Fenótipo , Fosfolipídeos/sangue , Gravidez , Trofoblastos/citologia , Peixe-ZebraRESUMO
Animal behavior is dynamic, evolving over multiple timescales from milliseconds to days and even across a lifetime. To understand the mechanisms governing these dynamics, it is necessary to capture multi-timescale structure from behavioral data. Here, we develop computational tools and study the behavior of hundreds of larval zebrafish tracked continuously across multiple 24-h day/night cycles. We extracted millions of movements and pauses, termed bouts, and used unsupervised learning to reduce each larva's behavior to an alternating sequence of active and inactive bout types, termed modules. Through hierarchical compression, we identified recurrent behavioral patterns, termed motifs. Module and motif usage varied across the day/night cycle, revealing structure at sub-second to day-long timescales. We further demonstrate that module and motif analysis can uncover novel pharmacological and genetic mutant phenotypes. Overall, our work reveals the organization of larval zebrafish behavior at multiple timescales and provides tools to identify structure from large-scale behavioral datasets.
Assuntos
Comportamento Animal , Peixe-Zebra , Animais , Larva , FenótipoRESUMO
The lipid transporters of the phosphatidylinositol transfer protein (PITP) family dictate phosphoinositide compartmentalization, and specific phosphoinositides play crucial roles in signaling cascades, membrane traffic, ion channel regulation, and actin dynamics. Although PITPs are enriched in the brain, their physiological functions in neuronal signaling pathways in vivo remain ill defined. We describe a CRISPR/Cas9-generated zebrafish mutant in a brain-specific, conserved class II PITP member, pitpnc1a. Zebrafish pitpnc1a mutants are healthy but display widespread aberrant neuronal activity and increased wakefulness across the day-night cycle. The loss of Pitpnc1a increases insulin-like growth factor (IGF) signaling in the brain, and inhibition of IGF pathways is sufficient to rescue both neuronal and behavioral hyperactivity in pitpnc1a mutants. We propose that Pitpnc1a-expressing neurons alter behavior via modification of neuro-modulatory IGF that acts on downstream wake-promoting circuits.
Assuntos
Fator de Crescimento Insulin-Like I/metabolismo , Proteínas de Membrana Transportadoras/uso terapêutico , Vigília/fisiologia , Animais , Proteínas de Membrana Transportadoras/farmacologia , Transdução de Sinais , Peixe-ZebraRESUMO
Autism spectrum disorders (ASDs) are a group of devastating neurodevelopmental syndromes that affect up to 1 in 68 children. Despite advances in the identification of ASD risk genes, the mechanisms underlying ASDs remain unknown. Homozygous loss-of-function mutations in Contactin Associated Protein-like 2 (CNTNAP2) are strongly linked to ASDs. Here we investigate the function of Cntnap2 and undertake pharmacological screens to identify phenotypic suppressors. We find that zebrafish cntnap2 mutants display GABAergic deficits, particularly in the forebrain, and sensitivity to drug-induced seizures. High-throughput behavioral profiling identifies nighttime hyperactivity in cntnap2 mutants, while pharmacological testing reveals dysregulation of GABAergic and glutamatergic systems. Finally, we find that estrogen receptor agonists elicit a behavioral fingerprint anti-correlative to that of cntnap2 mutants and show that the phytoestrogen biochanin A specifically reverses the mutant behavioral phenotype. These results identify estrogenic compounds as phenotypic suppressors and illuminate novel pharmacological pathways with relevance to autism.
Assuntos
Transtorno Autístico/tratamento farmacológico , Estrogênios/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Proteínas de Membrana/genética , Mutação/genética , Proteínas do Tecido Nervoso/genética , Animais , Animais Geneticamente Modificados , Transtorno Autístico/genética , Modelos Animais de Doenças , Estrogênios/uso terapêutico , Genisteína/farmacologia , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Larva , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Atividade Motora/efeitos dos fármacos , Atividade Motora/genética , Fenótipo , Fitoestrógenos/farmacologia , Psicotrópicos/farmacologia , Psicotrópicos/uso terapêutico , Convulsões/tratamento farmacológico , Convulsões/genética , Transtornos da Transição Sono-Vigília/tratamento farmacológico , Transtornos da Transição Sono-Vigília/genética , Proteína Vesicular 2 de Transporte de Glutamato/genética , Proteína Vesicular 2 de Transporte de Glutamato/metabolismo , Peixe-ZebraRESUMO
OBJECTIVES: The differential diagnosis between iron deficiency anaemia (IDA) and anaemia of chronic disease (ACD) with or without associated iron deficiency can be challenging. We assessed the use of different parameters, both classical like ferritin, transferrin saturation and stainable bone marrow iron stores, and novel markers such as low haemoglobin density (LHD) and hepcidin to help discriminate between the three entities. This would allow the detection of patients with ACD with associated iron deficiency, which could benefit from iron supplementation that would have otherwise remained undetected. MATERIALS AND METHODS: Prospective and observational cohort study from 2012 to 2013 where 200 anaemic cardiac surgical patients were recruited and 165 were studied. Detailed blood and bone marrow analyses were performed to establish the aetiology of anaemia. RESULTS: Seventy-four patients (44.8%) had ACD and 29 (39%) of these had an elevated LHD indicating concomitant iron deficiency. Hepcidin was inappropriately normal or increased in the IDA and ACD group. Mean hepcidin was however lower in the group with IDA (4.8 ng/mL) than in the ACD group (15.0 ng/mL; p=0.002). Median hepcidin was lower in patients with ACD and iron restriction as indicated by LHD >4% (17.5 ng/mL) than on those with no iron restriction (25.9 ng/mL; p=0.045). In patients with ACD there was no concordance between Perl's stain and LHD. CONCLUSIONS: LHD was superior to hepcidin and bone marrow iron stores in identifying patients with ACD and associated iron deficiency, which would potentially benefit from parenteral iron therapy.
Assuntos
Anemia/diagnóstico , Biomarcadores/análise , Idoso , Algoritmos , Anemia/etiologia , Medula Óssea/patologia , Procedimentos Cirúrgicos Cardíacos , Estudos de Coortes , Diagnóstico Diferencial , Feminino , Cardiopatias/sangue , Cardiopatias/complicações , Hemoglobinas/análise , Humanos , Masculino , Estudos Prospectivos , Coloração e Rotulagem , Transferrina/análiseRESUMO
OBJECTIVES: Preoperative anaemia is associated with increased morbidity and mortality. We sought to determine the relative frequencies of the different causes of anaemia including absolute and functional iron deficiency, and the association of different haematological parameters, including plasma hepcidin, a key protein responsible for iron regulation, with outcomes after cardiac surgery. METHODS: Prospective observational study between January 2012 and 2013; 200 anaemic cardiac surgical patients were recruited and 165 were studied. Detailed blood and bone marrow analysis was performed. Primary outcome was days alive and out of hospital. RESULTS: Mean (SD) haemoglobin (Hb) was 102 (8) g/L for women and 112 (11) g/L for men. Regarding outcomes, 137 (83%) patients were transfused at least one unit of red blood cells; 30-day mortality was 1.8% (three patients). Functional iron deficiency was diagnosed in 78 patients (47%). Plasma hepcidin concentration was the only haematological variable associated with outcome, with mean days alive and out of hospital 2.7 (95% CI 0.4 to 5.1) days less if hepcidin ≥20â ng/mL compared with <20â ng/mL (p=0.024). Multivariable analysis showed that the association between hepcidin and outcome was independent of risk (European System for Cardiac Operative Risk Evaluation), transfusion and Hb. CONCLUSIONS: Functional iron deficiency was the most common cause of anaemia but was not associated with outcome. The only haematological parameter that was associated with outcome was hepcidin concentration, which is a novel finding and introduces further complexity into our understanding of the role of iron and its regulation by hepcidin. We propose that future research should target patients with elevated hepcidin.