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Banerjee S, Szyszka P, Beck CW. Knockdown of NeuroD2 leads to seizure-like behavior, brain neuronal hyperactivity and a leaky blood-brain barrier in a Xenopus laevis tadpole model of DEE75. Genetics 2024; 227:iyae085. [PMID: 38788202 PMCID: PMC11228833 DOI: 10.1093/genetics/iyae085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 04/18/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
Developmental and Epileptic Encephalopathies (DEE) are a genetically diverse group of severe, early onset seizure disorders. DEE are normally identified clinically in the first six months of life by the presence of frequent, difficult to control seizures and accompanying stalling or regression of development. DEE75 results from de novo mutations of the NEUROD2 gene that result in loss of activity of the encoded transcription factor, and the seizure phenotype was shown to be recapitulated in Xenopus tropicalis tadpoles. We used CRISPR/Cas9 to make a DEE75 model in Xenopus laevis, to further investigate the developmental etiology. NeuroD2.S CRISPR/Cas9 edited tadpoles were more active, swam faster on average, and had more seizures (C-shaped contractions resembling unprovoked C-start escape responses) than their sibling controls. Live imaging of Ca2+ signaling revealed prolongued, strong signals sweeping through the brain, indicative of neuronal hyperactivity. While the resulting tadpole brain appeared grossly normal, the blood-brain barrier (BBB) was found to be leakier than that of controls. Additionally, the TGFβ antagonist Losartan was shown to have a short-term protective effect, reducing neuronal hyperactivity and reducing permeability of the BBB. Treatment of NeuroD2 CRISPant tadpoles with 5 mM Losartan decreased seizure events by more than 4-fold compared to the baseline. Our results support a model of DEE75 resulting from reduced NeuroD2 activity during vertebrate brain development, and indicate that a leaky BBB contributes to epileptogenesis.
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Affiliation(s)
- Sulagna Banerjee
- Department of Zoology, University of Otago, PO Box56, Dunedin 9016, New Zealand
| | - Paul Szyszka
- Department of Zoology, University of Otago, PO Box56, Dunedin 9016, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin 9016, New Zealand
| | - Caroline W Beck
- Department of Zoology, University of Otago, PO Box56, Dunedin 9016, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin 9016, New Zealand
- Genetics Otago Research Centre, University of Otago, Dunedin 9016, New Zealand
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2
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Metruccio F, Battistoni M, Di Renzo F, Bacchetta R, Santo N, Menegola E. Teratogenic and neuro-behavioural toxic effects of bisphenol A (BPA) and B (BPB) on Xenopus laevis development. Reprod Toxicol 2024; 123:108496. [PMID: 37951421 DOI: 10.1016/j.reprotox.2023.108496] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 10/05/2023] [Accepted: 11/02/2023] [Indexed: 11/14/2023]
Abstract
Bisphenol A (BPA) is a plastic additive with endocrine disruptive activity, classified in 2017 by EU ECHA as substance of very high concern. A correlation between environmental exposure to BPA and congenital defects has been described in humans and in experimental species, including the amphibian Xenopus laevis. Among BPA analogues, bisphenol B (BPB) is used as alternative in different not-EU countries, including US, but seems to share with BPA its endocrine disruptor properties. Aim of the present work is the evaluation of the effects of BPB versus BPA exposure in a X. laevis developmental model. A windowed exposure (R-FETAX method) was applied covering the developmental phylotypic period (teratogenicity window), or the late tailbud stages (neuro-behavioural toxicity window, corresponding to the spontaneous swimming acquisition period). Samples were monitored for lethal effects during the full test period. External morphology evaluation and deglutition functional test were applied in any group. Abnormal tadpoles were also processed for cartilage staining. In groups exposed during neuro-behavioural toxicity window the swimming test was also applied. Lethality and malformations were obtained only in samples exposed during the teratogenicity window; these data were modelled using PROAST software and BPB relative potency resulted about 3 times higher than BPA. The day-by-day evaluation revealed that lethality was correlated to embryonic abnormal development of gills and apoptosis in gill primordia. Teratogenicity was never detected in groups exposed during the neuro-behavioural toxicity window, where some significant neuro-behavioural deficits were detected in tadpoles exposed to the highest tested concentrations of BPA and BPB.
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Affiliation(s)
- F Metruccio
- ICPS, ASST Fatebenefratelli Sacco, via GB Grassi, 74, 20159 Milan, Italy
| | - M Battistoni
- Department of Environmental Science and Policy, Università degli Studi di Milano, via Celoria, 26, 20133 Milan, Italy
| | - F Di Renzo
- Department of Environmental Science and Policy, Università degli Studi di Milano, via Celoria, 26, 20133 Milan, Italy.
| | - R Bacchetta
- Department of Environmental Science and Policy, Università degli Studi di Milano, via Celoria, 26, 20133 Milan, Italy
| | - N Santo
- Unitech NOLIMITS, Imaging Facility, Università degli Studi di Milano, via Golgi, 19, 20133 Milan, Italy
| | - E Menegola
- Department of Environmental Science and Policy, Università degli Studi di Milano, via Celoria, 26, 20133 Milan, Italy
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3
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Sillar KT, Simmers J, Combes D. From tadpole to adult frog locomotion. Curr Opin Neurobiol 2023; 82:102753. [PMID: 37549591 DOI: 10.1016/j.conb.2023.102753] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/05/2023] [Accepted: 07/05/2023] [Indexed: 08/09/2023]
Abstract
The transition from larval to adult locomotion in the anuran, Xenopus laevis, involves a dramatic switch from axial to appendicular swimming including intermediate stages when the tail and hindlimbs co-exist and contribute to propulsion. Hatchling tadpole swimming is generated by an axial central pattern generator (CPG) which matures rapidly during early larval life. During metamorphosis, the developing limbs are controlled by a de novo appendicular CPG driven initially by the axial system before segregating to allow both systems to operate together or independently. Neuromodulation plays important roles throughout, but key modulators switch their effects from early inhibitory influences to facilitating locomotion. Temperature affects the construction and operation of locomotor networks and global changes in environmental temperature place aquatic poikilotherms, like amphibians, at risk. The locomotor control strategy of anurans differs from other amphibian groups such as salamanders, where evolution has acted upon the thyroid hormone pathway to sculpt different developmental outcomes.
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Affiliation(s)
- Keith T Sillar
- School of Psychology and Neuroscience, University of St Andrews, St Marys Quad., St Andrews, Fife KY16 9AP, Scotland.
| | - John Simmers
- Institut des Neurosciences Cognitives et Intégratives d'Aquitaine, CNRS UMR 5287, Université de Bordeaux, 33706 Bordeaux, France
| | - Denis Combes
- Institut des Neurosciences Cognitives et Intégratives d'Aquitaine, CNRS UMR 5287, Université de Bordeaux, 33706 Bordeaux, France
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Locascio A, Vassalli QA, Castellano I, Palumbo A. Novel Insights on Nitric Oxide Synthase and NO Signaling in Ascidian Metamorphosis. Int J Mol Sci 2022; 23:ijms23073505. [PMID: 35408864 PMCID: PMC8999111 DOI: 10.3390/ijms23073505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/11/2022] [Accepted: 03/20/2022] [Indexed: 02/05/2023] Open
Abstract
Nitric oxide (NO) is a pivotal signaling molecule involved in a wide range of physiological and pathological processes. We investigated NOS/NO localization patterns during the different stages of larval development in the ascidia Ciona robusta and evidenced a specific and temporally controlled pattern. NOS/NO expression starts in the most anterior sensory structures of the early larva and progressively moves towards the caudal portion as larval development and metamorphosis proceeds. We here highlight the pattern of NOS/NO expression in the central and peripheral nervous system of Ciona larvae which precisely follows the progression of neural signals of the central pattern generator necessary for the control of the movements of the larva towards the substrate. This highly dynamic localization profile perfectly matches with the central role played by NO from the first phase of settlement induction to the next control of swimming behavior, adhesion to substrate and progressive tissue resorption and reorganization of metamorphosis itself.
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Affiliation(s)
- Annamaria Locascio
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
- Correspondence: (A.L.); (A.P.)
| | - Quirino Attilio Vassalli
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
| | - Immacolata Castellano
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Via Pansini 5, 80131 Napoli, Italy;
| | - Anna Palumbo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
- Correspondence: (A.L.); (A.P.)
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Sharples SA, Parker J, Vargas A, Milla-Cruz JJ, Lognon AP, Cheng N, Young L, Shonak A, Cymbalyuk GS, Whelan PJ. Contributions of h- and Na+/K+ Pump Currents to the Generation of Episodic and Continuous Rhythmic Activities. Front Cell Neurosci 2022; 15:715427. [PMID: 35185470 PMCID: PMC8855656 DOI: 10.3389/fncel.2021.715427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 12/29/2021] [Indexed: 12/31/2022] Open
Abstract
Developing spinal motor networks produce a diverse array of outputs, including episodic and continuous patterns of rhythmic activity. Variation in excitability state and neuromodulatory tone can facilitate transitions between episodic and continuous rhythms; however, the intrinsic mechanisms that govern these rhythms and their transitions are poorly understood. Here, we tested the capacity of a single central pattern generator (CPG) circuit with tunable properties to generate multiple outputs. To address this, we deployed a computational model composed of an inhibitory half-center oscillator (HCO). Following predictions of our computational model, we tested the contributions of key properties to the generation of an episodic rhythm produced by isolated spinal cords of the newborn mouse. The model recapitulates the diverse state-dependent rhythms evoked by dopamine. In the model, episodic bursting depended predominantly on the endogenous oscillatory properties of neurons, with Na+/K+ ATPase pump (IPump) and hyperpolarization-activated currents (Ih) playing key roles. Modulation of either IPump or Ih produced transitions between episodic and continuous rhythms and silence. As maximal activity of IPump decreased, the interepisode interval and period increased along with a reduction in episode duration. Decreasing maximal conductance of Ih decreased episode duration and increased interepisode interval. Pharmacological manipulations of Ih with ivabradine, and IPump with ouabain or monensin in isolated spinal cords produced findings consistent with the model. Our modeling and experimental results highlight key roles of Ih and IPump in producing episodic rhythms and provide insight into mechanisms that permit a single CPG to produce multiple patterns of rhythmicity.
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Affiliation(s)
- Simon A. Sharples
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Jessica Parker
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Alex Vargas
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Jonathan J. Milla-Cruz
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Adam P. Lognon
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Ning Cheng
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Leanne Young
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Anchita Shonak
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Gennady S. Cymbalyuk
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
- Department of Physics and Astronomy, Georgia State University, Atlanta, GA, United States
- Gennady S. Cymbalyuk,
| | - Patrick J. Whelan
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Neuroscience, University of Calgary, Calgary, AB, Canada
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
- *Correspondence: Patrick J. Whelan,
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Hachoumi L, Rensner R, Richmond C, Picton L, Zhang H, Sillar KT. Bimodal modulation of short-term motor memory via dynamic sodium pumps in a vertebrate spinal cord. Curr Biol 2022; 32:1038-1048.e2. [PMID: 35104440 PMCID: PMC9616794 DOI: 10.1016/j.cub.2022.01.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 11/12/2021] [Accepted: 01/06/2022] [Indexed: 01/10/2023]
Abstract
Dynamic neuronal Na+/K+ pumps normally only respond to intense action potential firing owing to their low affinity for intracellular Na+. Recruitment of these Na+ pumps produces a post-activity ultraslow afterhyperpolarization (usAHP) up to ∼10 mV in amplitude and ∼60 s in duration, which influences neuronal properties and future network output. In spinal motor networks, the usAHP underlies short-term motor memory (STMM), reducing the intensity and duration of locomotor network output in a manner dependent on the interval between locomotor bouts. In contrast to tonically active Na+ pumps that help set and maintain the resting membrane potential, dynamic Na+ pumps are selectively antagonized by low concentrations of ouabain, which, we show, blocks both the usAHP and STMM. We examined whether dynamic Na+ pumps and STMM can be influenced by neuromodulators, focusing on 5-HT and nitric oxide. Bath-applied 5-HT alone had no significant effect on the usAHP or STMM. However, this is due to the simultaneous activation of two distinct 5-HT receptor subtypes (5-HT7 and 5-HT2a) that have opposing facilitatory and suppressive influences, respectively, on these two features of the locomotor system. Nitric oxide modulation exerts a potent inhibitory effect that can completely block the usAHP and erase STMM. Using selective blockers of 5-HT7 and 5-HT2a receptors and a nitric oxide scavenger, PTIO, we further provide evidence that the two modulators constitute an endogenous control system that determines how the spinal network self-regulates the intensity of locomotor output in light of recent past experience. Short-term memory in a spinal locomotor network is controlled by dynamic Na+ pumps Na+ pumps mediate an underlying ultraslow AHP modulated by 5-HT receptors and NO 5-HT7Rs increase and 5-HT2aRs and NO decrease the usAHP and short-term motor memory Endogenous 5-HT and NO regulate the usAHP and short-term motor memory
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7
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Battistoni M, Bacchetta R, Di Renzo F, Metruccio F, Moretto A, Menegola E. Modified Xenopus laevis approach (R-FETAX) as an alternative test for the evaluation of foetal valproate spectrum disorder. Reprod Toxicol 2021; 107:140-149. [PMID: 34923091 DOI: 10.1016/j.reprotox.2021.12.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 11/25/2021] [Accepted: 12/09/2021] [Indexed: 10/19/2022]
Abstract
In compliance to animal welfare 3Rs principle there is a great demand for refined tests alternative to classical mammal teratogenicity tests. We propose a refined alternative amphibian method (R-FETAX) to evaluate chemical induced embryotoxicity. The human foetal valproate spectrum disorder (FVSD) characteristics are morphological defects (including cranio-facial, neural tube defects) and behavioural alterations due to valproate (VPA) exposure in pregnancy. Vertebrate assays to evaluate FVSD include classical and alternative mammal (implying adult sacrifice), and non-mammal developmental models (zebrafish, amphibians, chick). Among these latter only zebrafish assays report in the same test both morphological and behavioural examinations. Compared to zebrafish, the amphibian Xenopus laevis excels having a more comparable organ development and morphology to mammalian systems. We used X. laevis embryos exposed during developmental specific windows to VPA therapeutic concentrations. Different VPA effects were observed depending on the exposure window: concentration-related embryo-lethal and teratogenic effects (neural tube, facial, tail defects) were observed in groups exposed at the organogenetic phylotypic stages. Neurobehavioral deficits were described using a functional swimming test at the highest VPA concentration exposure during the phylotypic stages and at any concentration during neurocognitive competent stages. Malformations were compared to those obtained in a mammalian assay (the rat post-implantation whole embryo culture method, WEC), that we used in the past to evaluate VPA teratogenicity. R-FETAX and WEC data were modelled and their relative sensitivity was calculated. We suggest the amphibian R-FETAX as a refined windowed alternative test for the evaluation of chemicals inducing both morphological and behavioural anomalies, including VPA.
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Affiliation(s)
- Maria Battistoni
- Università Degli Studi di Milano, Department of Physics Aldo Pontremoli, via Celoria, 16-20133, Milan, Italy; Università Degli Studi di Milano, Department of Environmental Science and Policy, via Celoria, 26-20133, Milan, Italy.
| | - Renato Bacchetta
- Università Degli Studi di Milano, Department of Environmental Science and Policy, via Celoria, 26-20133, Milan, Italy.
| | - Francesca Di Renzo
- Università Degli Studi di Milano, Department of Environmental Science and Policy, via Celoria, 26-20133, Milan, Italy.
| | | | - Angelo Moretto
- Università Degli Studi di Milano, Department of Biomedical and Clinical Sciences "L. Sacco", via GB Grassi, 74- 20159, Milan, Italy.
| | - Elena Menegola
- Università Degli Studi di Milano, Department of Environmental Science and Policy, via Celoria, 26-20133, Milan, Italy.
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Superior predatory ability and abundance predicts potential ecological impact towards early-stage anurans by invasive 'Killer Shrimp' (Dikerogammarus villosus). Sci Rep 2021; 11:4570. [PMID: 33633148 PMCID: PMC7907340 DOI: 10.1038/s41598-021-82630-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 12/16/2020] [Indexed: 11/09/2022] Open
Abstract
Invasive alien species negatively impact upon biodiversity and generate significant economic costs worldwide. Globally, amphibians have suffered considerable losses, with a key driver being predation by large invasive invertebrate and vertebrate predators. However, there is no research regarding the potential ecological impact of small invertebrate invaders. The invasive freshwater amphipod Dikerogammarus villosus can act as a top predator capable of displacing native amphipods and preying heavily upon a range of native species. Listed as one of Europe's top 100 worst invaders, D. villosus has significantly restructured freshwater communities across western Europe and is expected to invade North America in the near future. Here we explore the ecological impact of invasive D. villosus upon UK native and invasive amphibians (Rana temporaria and Xenopus laevis respectively) using the "Relative Impact Potential" (RIP) metric. By combining estimations of per capita effects (i.e. functional response; FR) and relative field abundances, we apply the RIP metric to quantify the potential ecological impact of invasive D. villosus upon embryonic and larval amphibian prey, compared to the native amphipod Gammarus pulex. Both native and invasive amphipods consumed early-stage amphibians and exhibited potentially destabilising Type II FRs. However, larger body size in invasive D. villosus translated into a superior FR through significantly lower handling times and subsequently higher maximum feeding rates-up to seven times greater than native G. pulex. Higher invader abundance also drove elevated RIP scores for invasive D. villosus, with potential impact scores predicted up to 15.4 times greater than native G. pulex. Overall, D. villosus is predicted to have a greater predatory impact upon amphibian populations than G. pulex, due primarily to its larger body size and superior field abundance, potentially reducing amphibian recruitment within invaded regions.
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Dur AH, Tang T, Viviano S, Sekuri A, Willsey HR, Tagare HD, Kahle KT, Deniz E. In Xenopus ependymal cilia drive embryonic CSF circulation and brain development independently of cardiac pulsatile forces. Fluids Barriers CNS 2020; 17:72. [PMID: 33308296 PMCID: PMC7731788 DOI: 10.1186/s12987-020-00234-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/28/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Hydrocephalus, the pathological expansion of the cerebrospinal fluid (CSF)-filled cerebral ventricles, is a common, deadly disease. In the adult, cardiac and respiratory forces are the main drivers of CSF flow within the brain ventricular system to remove waste and deliver nutrients. In contrast, the mechanics and functions of CSF circulation in the embryonic brain are poorly understood. This is primarily due to the lack of model systems and imaging technology to study these early time points. Here, we studied embryos of the vertebrate Xenopus with optical coherence tomography (OCT) imaging to investigate in vivo ventricular and neural development during the onset of CSF circulation. METHODS Optical coherence tomography (OCT), a cross-sectional imaging modality, was used to study developing Xenopus tadpole brains and to dynamically detect in vivo ventricular morphology and CSF circulation in real-time, at micrometer resolution. The effects of immobilizing cilia and cardiac ablation were investigated. RESULTS In Xenopus, using OCT imaging, we demonstrated that ventriculogenesis can be tracked throughout development until the beginning of metamorphosis. We found that during Xenopus embryogenesis, initially, CSF fills the primitive ventricular space and remains static, followed by the initiation of the cilia driven CSF circulation where ependymal cilia create a polarized CSF flow. No pulsatile flow was detected throughout these tailbud and early tadpole stages. As development progressed, despite the emergence of the choroid plexus in Xenopus, cardiac forces did not contribute to the CSF circulation, and ciliary flow remained the driver of the intercompartmental bidirectional flow as well as the near-wall flow. We finally showed that cilia driven flow is crucial for proper rostral development and regulated the spatial neural cell organization. CONCLUSIONS Our data support a paradigm in which Xenopus embryonic ventriculogenesis and rostral brain development are critically dependent on ependymal cilia-driven CSF flow currents that are generated independently of cardiac pulsatile forces. Our work suggests that the Xenopus ventricular system forms a complex cilia-driven CSF flow network which regulates neural cell organization. This work will redirect efforts to understand the molecular regulators of embryonic CSF flow by focusing attention on motile cilia rather than other forces relevant only to the adult.
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Affiliation(s)
- A H Dur
- Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
- Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Turkey
| | - T Tang
- Department of Radiology and Biomedical Imaging, Yale University, 300 Cedar St, New Haven, CT, 06510, USA
| | - S Viviano
- Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
| | - A Sekuri
- Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Turkey
| | - H R Willsey
- Department of Psychiatry and Behavioral Sciences, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - H D Tagare
- Department of Radiology and Biomedical Imaging, Yale University, 300 Cedar St, New Haven, CT, 06510, USA
| | - K T Kahle
- Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
- Department of Neurosurgery and Cellular & Molecular Physiology, and Centers for Mendelian Genomics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
| | - E Deniz
- Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA.
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA.
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Hachoumi L, Sillar KT. Developmental stage-dependent switching in the neuromodulation of vertebrate locomotor central pattern generator networks. Dev Neurobiol 2019; 80:42-57. [PMID: 31705739 DOI: 10.1002/dneu.22725] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/24/2019] [Accepted: 11/05/2019] [Indexed: 12/27/2022]
Abstract
Neuromodulation plays important and stage-dependent roles in regulating locomotor central pattern (CPG) outputs during vertebrate motor system development. Dopamine, serotonin and nitric oxide are three neuromodulators that potently influence CPG outputs in the development of Xenopus frog tadpole locomotion. However, their roles switch from predominantly inhibitory early in development to mainly excitatory at later stages. In this review, we compare the stage-dependent switching in neuromodulation in Xenopus with other vertebrate systems, notably the mouse and the zebrafish, and highlight features that appear to be phylogenetically conserved.
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Affiliation(s)
- Lamia Hachoumi
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
| | - Keith T Sillar
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
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11
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Automated behavioural analysis reveals the basic behavioural repertoire of the urochordate Ciona intestinalis. Sci Rep 2019; 9:2416. [PMID: 30787329 PMCID: PMC6382837 DOI: 10.1038/s41598-019-38791-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/09/2019] [Indexed: 12/17/2022] Open
Abstract
Quantitative analysis of animal behaviour in model organisms is becoming an increasingly essential approach for tackling the great challenge of understanding how activity in the brain gives rise to behaviour. Here we used automated image-based tracking to extract behavioural features from an organism of great importance in understanding the evolution of chordates, the free-swimming larval form of the tunicate Ciona intestinalis, which has a compact and fully mapped nervous system composed of only 231 neurons. We analysed hundreds of videos of larvae and we extracted basic geometric and physical descriptors of larval behaviour. Importantly, we used machine learning methods to create an objective ontology of behaviours for C. intestinalis larvae. We identified eleven behavioural modes using agglomerative clustering. Using our pipeline for quantitative behavioural analysis, we demonstrate that C. intestinalis larvae exhibit sensory arousal and thigmotaxis. Notably, the anxiotropic drug modafinil modulates thigmotactic behaviour. Furthermore, we tested the robustness of the larval behavioural repertoire by comparing different rearing conditions, ages and group sizes. This study shows that C. intestinalis larval behaviour can be broken down to a set of stereotyped behaviours that are used to different extents in a context-dependent manner.
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12
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Currie SP, Sillar KT. Developmental changes in spinal neuronal properties, motor network configuration, and neuromodulation at free-swimming stages of Xenopus tadpoles. J Neurophysiol 2017; 119:786-795. [PMID: 29142093 DOI: 10.1152/jn.00219.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We describe a novel preparation of the isolated brain stem and spinal cord from prometamorphic tadpole stages of the South African clawed frog ( Xenopus laevis) that permits whole cell patch-clamp recordings from neurons in the ventral spinal cord. Previous research on earlier stages of the same species has provided one of the most detailed understandings of the design and operation of a central pattern generator circuit. Here we have addressed how development sculpts complexity from this more basic circuit. The preparation generates bouts of fictive swimming activity either spontaneously or in response to electrical stimulation of the optic tectum, allowing an investigation into how the neuronal properties, activity patterns, and neuromodulation of locomotor rhythm generation change during development. We describe an increased repertoire of cellular responses compared with younger larval stages and investigate the cellular-level effects of nitrergic neuromodulation as well as the development of a sodium pump-mediated ultraslow afterhyperpolarization (usAHP) in these free-swimming larval animals. NEW & NOTEWORTHY A novel in vitro brain stem-spinal cord preparation is described that enables whole cell patch-clamp recordings from spinal neurons in prometamorphic Xenopus tadpoles. Compared with the well-characterized earlier stages of development, spinal neurons display a wider range of firing properties during swimming and have developed novel cellular properties. This preparation now makes it feasible to investigate in detail spinal central pattern generator maturation during the dramatic switch between undulatory and limb-based locomotion strategies during amphibian metamorphosis.
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Affiliation(s)
- Stephen P Currie
- School of Psychology and Neuroscience, University of St. Andrews , St. Andrews , United Kingdom
| | - Keith T Sillar
- School of Psychology and Neuroscience, University of St. Andrews , St. Andrews , United Kingdom
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13
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Branoner F, Chagnaud BP, Straka H. Ontogenetic Development of Vestibulo-Ocular Reflexes in Amphibians. Front Neural Circuits 2016; 10:91. [PMID: 27877114 PMCID: PMC5099239 DOI: 10.3389/fncir.2016.00091] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 10/24/2016] [Indexed: 12/23/2022] Open
Abstract
Vestibulo-ocular reflexes (VOR) ensure gaze stability during locomotion and passively induced head/body movements. In precocial vertebrates such as amphibians, vestibular reflexes are required very early at the onset of locomotor activity. While the formation of inner ears and the assembly of sensory-motor pathways is largely completed soon after hatching, angular and translational/tilt VOR display differential functional onsets and mature with different time courses. Otolith-derived eye movements appear immediately after hatching, whereas the appearance and progressive amelioration of semicircular canal-evoked eye movements is delayed and dependent on the acquisition of sufficiently large semicircular canal diameters. Moreover, semicircular canal functionality is also required to tune the initially omnidirectional otolith-derived VOR. The tuning is due to a reinforcement of those vestibulo-ocular connections that are co-activated by semicircular canal and otolith inputs during natural head/body motion. This suggests that molecular mechanisms initially guide the basic ontogenetic wiring, whereas semicircular canal-dependent activity is required to establish the spatio-temporal specificity of the reflex. While a robust VOR is activated during passive head/body movements, locomotor efference copies provide the major source for compensatory eye movements during tail- and limb-based swimming of larval and adult frogs. The integration of active/passive motion-related signals for gaze stabilization occurs in central vestibular neurons that are arranged as segmentally iterated functional groups along rhombomere 1–8. However, at variance with the topographic maps of most other sensory systems, the sensory-motor transformation of motion-related signals occurs in segmentally specific neuronal groups defined by the extraocular motor output targets.
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Affiliation(s)
- Francisco Branoner
- Department Biology II, Ludwig-Maximilians-University Munich Munich, Germany
| | - Boris P Chagnaud
- Department Biology II, Ludwig-Maximilians-University Munich Munich, Germany
| | - Hans Straka
- Department Biology II, Ludwig-Maximilians-University Munich Munich, Germany
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14
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Hänzi S, Straka H. Developmental changes in head movement kinematics during swimming in Xenopus laevis tadpoles. ACTA ACUST UNITED AC 2016; 220:227-236. [PMID: 27811303 DOI: 10.1242/jeb.146449] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/23/2016] [Indexed: 01/15/2023]
Abstract
During the post-embryonic developmental growth of animals, a number of physiological parameters such as locomotor performance, dynamics and behavioural repertoire are adjusted to match the requirements determined by changes in body size, proportions and shape. Moreover, changes in movement parameters also cause changes in the dynamics of self-generated sensory stimuli, to which motion-detecting sensory systems have to adapt. Here, we examined head movements and swimming kinematics of Xenopus laevis tadpoles with a body length of 10-45 mm (developmental stage 46-54) and compared these parameters with fictive swimming, recorded as ventral root activity in semi-intact in vitro preparations. Head movement kinematics was extracted from high-speed video recordings of freely swimming tadpoles. Analysis of these locomotor episodes indicated that the swimming frequency decreased with development, along with the angular velocity and acceleration of the head, which represent self-generated vestibular stimuli. In contrast, neither head oscillation amplitude nor forward velocity changed with development despite the ∼3-fold increase in body size. The comparison between free and fictive locomotor dynamics revealed very similar swimming frequencies for similarly sized animals, including a comparable developmental decrease of the swimming frequency. Body morphology and the motor output rhythm of the spinal central pattern generator therefore develop concurrently. This study thus describes development-specific naturalistic head motion profiles, which form the basis for more natural stimuli in future studies probing the vestibular system.
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Affiliation(s)
- Sara Hänzi
- Department of Biology II, Ludwig-Maximilians-University Munich, Großhaderner Strasse 2, Planegg 82152, Germany .,Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Großhaderner Strasse 2, Planegg 82152, Germany
| | - Hans Straka
- Department of Biology II, Ludwig-Maximilians-University Munich, Großhaderner Strasse 2, Planegg 82152, Germany
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Picton LD, Sillar KT. Mechanisms underlying the endogenous dopaminergic inhibition of spinal locomotor circuit function in Xenopus tadpoles. Sci Rep 2016; 6:35749. [PMID: 27760989 PMCID: PMC5071771 DOI: 10.1038/srep35749] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 09/30/2016] [Indexed: 01/08/2023] Open
Abstract
Dopamine plays important roles in the development and modulation of motor control circuits. Here we show that dopamine exerts potent effects on the central pattern generator circuit controlling locomotory swimming in post-embryonic Xenopus tadpoles. Dopamine (0.5–100 μM) reduced fictive swim bout occurrence and caused both spontaneous and evoked episodes to become shorter, slower and weaker. The D2-like receptor agonist quinpirole mimicked this repertoire of inhibitory effects on swimming, whilst the D4 receptor antagonist, L745,870, had the opposite effects. The dopamine reuptake inhibitor bupropion potently inhibited fictive swimming, demonstrating that dopamine constitutes an endogenous modulatory system. Both dopamine and quinpirole also inhibited swimming in spinalised preparations, suggesting spinally located dopamine receptors. Dopamine and quinpirole hyperpolarised identified rhythmically active spinal neurons, increased rheobase and reduced spike probability both during swimming and in response to current injection. The hyperpolarisation was TTX-resistant and was accompanied by decreased input resistance, suggesting that dopamine opens a K+ channel. The K+ channel blocker barium chloride (but not TEA, glybenclamide or tertiapin-Q) significantly occluded the hyperpolarisation. Overall, we show that endogenously released dopamine acts upon spinally located D2-like receptors, leading to a rapid inhibitory modulation of swimming via the opening of a K+ channel.
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Affiliation(s)
- Laurence D Picton
- School of Psychology and Neuroscience, University of St Andrews, St Andrews KY16 9JP, United Kingdom
| | - Keith T Sillar
- School of Psychology and Neuroscience, University of St Andrews, St Andrews KY16 9JP, United Kingdom
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