Identification of neurons controlling orientation behavior in the Drosophila melanogaster larva
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Document Version
Author
Director
Louis, Matthieu
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Publication Date
Pages
142 p.
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Citation
Riedl, J. Identification of neurons controlling orientation behavior in the Drosophila melanogaster larva. Universitat Pompeu Fabra; 2013. handle: http://hdl.handle.net/10803/283473
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Doctoral program
Programa de doctorat en Biomedicina
Abstract
En este estudio hemos aprovechado la simplicidad numérica del sistema nervioso de la larva de la Drosophila melanogaster para identificar las neuronas responsables que dirigen sus movimientos de acuerdo a ciertas sustancias químicas (quimiotaxis). Con este propósito, hemos realizado un amplio rastreo conductual utilizando el sistema Gal4/UAS para expresar en subpoblaciones de neuronas genéticamente definidas una toxina silenciadora de la sinapsis. Hemos identificado una línea Gal4 (NP4820) perteneciente al subgrupo de neuronas del ganglio subesofágico (GSO) del cerebro de la larva involucrada en la organización de modalidades conductuales específicas subyacentes al comportamiento orientativo. Las larvas desprovistas de neuronas marcadas-NP4820 funcionales se vieron afectadas en cuanto a la correcta transición de una trayectoria recta a un movimiento de rastreo/giro respecto a su experiencia sensorial. Activar las neuronas remotamente fue suficiente para iniciar la maniobra de rastreo/giro. Este efecto puede generalizarse a otras modalidades sensoriales a parte del olfato, sugiriendo así el GSO como una región del cerebro esencial para seleccionar y ejecutar acciones. Utilizando la misma estrategia buscamos neuronas responsables de la orientación en campos electrostáticos. Hemos demostrado que las larvas de Drosophila migran hacia el cátodo, basándose en maniobras de rastreo/giro para alinearse al campo eléctrico. Además, hemos identificado neuronas eletrosensoriales localizadas en el órgano terminal de la larva. Analysis funcionale ha demostrado que su actividad neuronal depende de la orientación y amplitud del campo, sustentando así la habilidad de la larva para alinearse al campo eléctrico local. Hemos revelado la existencia de una nueva modalidad sensorial en la Drosophila melanogaster y evidencia que el campo eléctrico representa un estímulo biológicamente relevante.
Detecting sensory stimuli and converting them into behavioral output is the essential function of nervous systems. In this study we took advantage of the numerical simplicity of the nervous system of the Drosophila melanogaster larva to find neurons underlying orientation behavior to chemical cues (chemotaxis). To this aim we performed a behavioral screen using the Gal4/UAS system to express a synaptic silencing toxin in genetically defined subpopulations of neurons. We identified a Gal4 line (NP4820) covering a subgroup of neurons in the suboesophageal ganglion of the larval brain to be involved in the organization of the specific behavioral modes underlying orientation behaviors. Larvae devoid of functional NP4820-labeled neurons were impaired in the correct transition from run- to casts/turn- mode. Remotely activating the neurons was sufficient to initiate a cast/turn maneuver. The effect could be generalized to other sensory modalities than olfaction, suggesting the SOG as a brain region generally essential for action selection and execution. Using the same approach we searched for neurons underlying orientation in a static electric field. We found that Drosophila larvae robustly migrate to the cathode, making use of cast/turn maneuvers to align to the field. Moreover, our behavioral screen revealed electrosensory neurons located in the larval terminal organ. Functional imaging showed that their neural activity is tuned to the orientation and amplitude of the field, underlying the ability of the larva to align with the local electric field. Our findings revealed the existence of a novel sensory modality in Drosophila melanogaster and evidence that electric fields represent a biologically relevant stimulus.
Detecting sensory stimuli and converting them into behavioral output is the essential function of nervous systems. In this study we took advantage of the numerical simplicity of the nervous system of the Drosophila melanogaster larva to find neurons underlying orientation behavior to chemical cues (chemotaxis). To this aim we performed a behavioral screen using the Gal4/UAS system to express a synaptic silencing toxin in genetically defined subpopulations of neurons. We identified a Gal4 line (NP4820) covering a subgroup of neurons in the suboesophageal ganglion of the larval brain to be involved in the organization of the specific behavioral modes underlying orientation behaviors. Larvae devoid of functional NP4820-labeled neurons were impaired in the correct transition from run- to casts/turn- mode. Remotely activating the neurons was sufficient to initiate a cast/turn maneuver. The effect could be generalized to other sensory modalities than olfaction, suggesting the SOG as a brain region generally essential for action selection and execution. Using the same approach we searched for neurons underlying orientation in a static electric field. We found that Drosophila larvae robustly migrate to the cathode, making use of cast/turn maneuvers to align to the field. Moreover, our behavioral screen revealed electrosensory neurons located in the larval terminal organ. Functional imaging showed that their neural activity is tuned to the orientation and amplitude of the field, underlying the ability of the larva to align with the local electric field. Our findings revealed the existence of a novel sensory modality in Drosophila melanogaster and evidence that electric fields represent a biologically relevant stimulus.
Keywords
Drosophila melanogaster larva, Comportamiento orientativo, Ganglio subesofágico, Transicion conductual, Electrotaxis, Neuronas sensoriales, Orientation behavior, Suboesophageal ganglion, Behavior organization, Sensory neurons
Subjects
59 - Zoology
Publisher
Universitat Pompeu Fabra
