The main research interest of our lab is to elucidate the underlying molecular and cellular mechanisms of genetic psychiatric disorders such as psychomotor retardation, Fragile X syndrome (FXS), and sleep disturbances.
To understand these brain deficiencies, we combine the use of genetic manipulations, real-time 2-photon imaging of single organelles, synapses and neurons, and video-tracking of behavior in live zebrafish. The zebrafish is a simple transparent vertebrate with conserved organization of the central nervous system. Furthermore, it is ideally suited for genetic manipulation and high-resolution imaging of the entire brain in a live animal.
We develop zebrafish models for human brain disorders. The function of genes and neuronal circuits is determined using loss-of-function (CRISPR-mediated genome editing as well as genetic silencing and ablation of a specific neuronal population) and gain-of-function (transposon-mediated transgenesis) experiments.
Our general goal is to link gene function with the development and plasticity of neuronal circuits that regulate specific behavior.
Sleep and sleep disorders
Sleep is an evolutionarily conserved process that is vital for animal survival. Sleep disturbances affect approximately 20% of the general population and represent a major health burden. Although sleep clearly improves brain performance, the function of sleep is still debated and includes macromolecule biosynthesis, energy conservation, metabolite clearance, memory consolidation, and synaptic plasticity. We have characterized sleep, cloned sleep genes, and visualized sleep circuits, and established the zebrafish as an attractive model to study the sleep/wake cycle in a high throughput approach.
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Why do we sleep?
Live imaging of the cellular mechanisms of sleep.
Prolonged sleep deprivation can be lethal, and sleep disturbances are associated with various deficiencies in brain performance. However, it is unclear what effects sleep has at a cellular level. This is because sleep has previously been defined by behavioural criteria and EEG, as it has not been possible to study sleep-dependent cellular processes under the microscope. We developed a new method for time-lapse imaging of single molecules in individual neurons of live zebrafish. Using this approach, we show that sleep increases the movement of chromosomes (chromosome dynamics), which alters their structure to enable reduction of DNA damage, while neuronal activity has the opposite effect. In addition, chromosome dynamics could be a potential marker to define individual sleeping neurons. Thus, sleep increases chromosome dynamics that clear out DNA damage accumulated during waking hours. The current research focus on nuclear and cellular mechanisms of sleep.
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Mental and psychomotor retardation are characterized by cognitive, social, and motor deficits. The cause for these disorders is often genetic mutations that typically lead to alteration in neurogenesis, myelination, synaptic plasticity, and the activity of neuronal circuits. In order to understand psychomotor retardation, a critical challenge is to identify and visualize functional circuits in the brain, which contains an incomprehensible dense population of neurons and their processes. We established several zebrafish models for psychomotor retardation and study the mechanism and treatment of these disorders. Remarkably, gene-specific mutations that cause psychomotor retardation in human are also linked to genetic and neuronal alterations in zebrafish. These similarities between the two vertebrate species enable rescue assays in the zebrafish model, which help to understand the mechanism and targets of specific genetic and drug treatments.
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Sleep disorders and the hypocretin/orexin (Hcrt) neuronal networks
The hypothalamus regulates fundamental brain functions, such as metabolism and sleep. Understanding the function of hypothalamic neuronal circuits is critical because of its association with neurodegenerative, genetic, sleep, and metabolic disorders. The hypothalamic Hcrt neurons are regulators of feeding, emotions, reward, sleep and wake, and Hcrt neuron deficiency results in the sleep disorder narcolepsy in humans and animal models. We established a transgenic zebrafish model, enabling inducible ablation of Hcrt neurons, as a model for narcolepsy. Using combination of system-biology, genetics, live-imaging, and behavioral experiments, we identify and characterize novel Hcrt-neuron-specific genes in zebrafish. In addition, we study structural and functional connection between several neuropeptide-producing hypothalamic neuronal networks such as Hcrt, and neurotensin (Nts).
Sleep and synaptic plasticity
Sleep is conserved in evolution, and similar circadian and homeostatic factors regulate sleep in animals as distantly related as worms, flies, fish, and humans. Accumulating evidence shows that sleep is important for synaptic plasticity, memory, and learning. Using time-lapse two-photon imaging of excitatory and inhibitory pre- and post-synaptic markers, we study circadian and homeostatic control of rhythmic synaptic plasticity in the brain of live zebrafish.
Fragile X syndrome
Fragile-X syndrome (FXS) is the most common single-gene inherited neurodevelopmental disorder causing mental retardation. It is caused by mutations in the fragile X mental retardation 1 (fmr1) gene and the absence of the fragile X mental retardation protein (FMRP). The RNA-binding protein FMRP represses protein translation in synapses, and interacts with the adenosine deaminase acting on the RNA (ADAR) enzyme, which converts adenosine-to-inosine (A-to-I) and modifies the sequence of RNA transcripts. Utilizing the fmr1 zebrafish mutant (fmr1-/-), we study the link between ADAR-mediated RNA editing, neuronal circuit formation, and behavior in FXS.
Thyroid hormones and psychomotor retardation
Thyroid hormones (TH) are key regulators of embryonic development, metabolism, and neurogenesis in all vertebrates. The X-linked psychomotor retardation Allan-Herndon-Dudley syndrome (AHDS) is associated with mutations in the TH monocarboxylate transporter 8 (mct8). AHDS is characterized by severe intellectual deficiency, neuromuscular impairment, and high serum TH levels. We utilize mutant and transgenic zebrafish to elucidate the neurological mechanism and find potential genetic and pharmacological treatments to AHDS and other TH-related disorders.
Dr. Tali Levitas-Djerbi
Dr. Adi Shamay
Alumna Phd. Student
Alumna MSc. Student
Dr. Einat Blitz
Alumna Postdoctoral Fellow Email: firstname.lastname@example.org
Dr. Adi Tovin
Alumna Postdoctoral Fellow Email: email@example.com
Behavioral and Neural Genetics of Zebrafish
Curr Opin Neurobiol
Mol Cell Endocrinol
Curr Topics Behav Neuroscience
Disease Models & Mechanisms
J Comp Neurol
Frontiers in Neural Circuits
J Biol Chem
The Journal of Neuroscience
Trends in Neurosciences
Proceedings of the National Academy of Sciences U S A
Journal of Neuroendocrinology
Journal of Biological Chemistry
Molecular and Cellular Endocrinology
Journal of Molecular Endocrinology
Journal of Biological Chemistry
The Faculty of Life Sciences and The Multidisciplinary Brain Research Center
The Nanotechnology Building (206), Room B-938
Bar Ilan University, Ramat Gan 5290002