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1.
Eur J Neurosci ; 20(3): 611-22, 2004 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-15255973

RESUMEN

Vertebrate synapsins are abundant synaptic vesicle phosphoproteins that have been proposed to fine-regulate neurotransmitter release by phosphorylation-dependent control of synaptic vesicle motility. However, the consequences of a total lack of all synapsin isoforms due to a knock-out of all three mouse synapsin genes have not yet been investigated. In Drosophila a single synapsin gene encodes several isoforms and is expressed in most synaptic terminals. Thus the targeted deletion of the synapsin gene of Drosophila eliminates the possibility of functional knock-out complementation by other isoforms. Unexpectedly, synapsin null mutant flies show no obvious defects in brain morphology, and no striking qualitative changes in behaviour are observed. Ultrastructural analysis of an identified 'model' synapse of the larval nerve muscle preparation revealed no difference between wild-type and mutant, and spontaneous or evoked excitatory junction potentials at this synapse were normal up to a stimulus frequency of 5 Hz. However, when several behavioural responses were analysed quantitatively, specific differences between mutant and wild-type flies are noted. Adult locomotor activity, optomotor responses at high pattern velocities, wing beat frequency, and visual pattern preference are modified. Synapsin mutant flies show faster habituation of an olfactory jump response, enhanced ethanol tolerance, and significant defects in learning and memory as measured using three different paradigms. Larval behavioural defects are described in a separate paper. We conclude that Drosophila synapsins play a significant role in nervous system function, which is subtle at the cellular level but manifests itself in complex behaviour.


Asunto(s)
Conducta Animal/fisiología , Drosophila/fisiología , Sinapsinas/deficiencia , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/genética , Potenciales de Acción/fisiología , Animales , Animales Modificados Genéticamente , Conducta Animal/efectos de los fármacos , Western Blotting/métodos , Depresores del Sistema Nervioso Central/farmacología , Clonación Molecular/métodos , Condicionamiento Operante/fisiología , Análisis Mutacional de ADN , Drosophila/genética , Estimulación Eléctrica/métodos , Etanol/farmacología , Potenciales Postsinápticos Excitadores/genética , Inmunohistoquímica/métodos , Técnicas de Inmunoadsorción , Potenciales de la Membrana/genética , Potenciales de la Membrana/fisiología , Microscopía Electrónica , Actividad Motora/efectos de los fármacos , Actividad Motora/fisiología , Mutagénesis/fisiología , Unión Neuromuscular/genética , Unión Neuromuscular/metabolismo , Unión Neuromuscular/fisiología , Desempeño Psicomotor/fisiología , Conducta Sexual/efectos de los fármacos , Conducta Sexual/fisiología , Sinapsis/metabolismo , Sinapsis/ultraestructura , Sinapsinas/genética , Sinapsinas/fisiología , Vesículas Sinápticas/genética , Vesículas Sinápticas/metabolismo , Vesículas Sinápticas/ultraestructura , Factores de Tiempo , Distribución Tisular , Percepción Visual/genética , Percepción Visual/fisiología , Caminata/fisiología , Alas de Animales/fisiología
2.
EMBO J ; 22(3): 459-68, 2003 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-12554647

RESUMEN

Heterotrimeric G-proteins relay signals between membrane-bound receptors and downstream effectors. Little is known, however, about the regulation of Galpha subunit localization within the natural endogenous environment of a specialized signaling cell. Here we show, using live Drosophila flies, that light causes massive and reversible translocation of the visual Gqalpha to the cytosol, associated with marked architectural changes in the signaling compartment. Molecular genetic dissection together with detailed kinetic analysis enabled us to characterize the translocation cycle and to unravel how signaling molecules that interact with Gqalpha affect these processes. Epistatic analysis showed that Gqalpha is necessary but not sufficient to bring about the morphological changes in the signaling organelle. Furthermore, mutant analysis indicated that Gqbeta is essential for targeting of Gqalpha to the membrane and suggested that Gqbeta is also needed for efficient activation of Gqalpha by rhodopsin. Our results support the 'two-signal model' hypothesis for membrane targeting in a living organism and characterize the regulation of both the activity-dependent Gq localization and the cellular architectural changes in Drosophila photoreceptors.


Asunto(s)
Drosophila melanogaster/metabolismo , Proteínas de Unión al GTP Heterotriméricas/metabolismo , Luz , Células Fotorreceptoras de Invertebrados/ultraestructura , Subunidades de Proteína/metabolismo , Transporte de Proteínas/fisiología , Actinas/metabolismo , Animales , Citoplasma/química , Citoplasma/metabolismo , Adaptación a la Oscuridad , Drosophila melanogaster/ultraestructura , Subunidades alfa de la Proteína de Unión al GTP Gq-G11 , Proteínas de Unión al GTP Heterotriméricas/química , Proteínas de Microfilamentos/genética , Proteínas de Microfilamentos/metabolismo , Modelos Moleculares , Organismos Modificados Genéticamente , Células Fotorreceptoras de Invertebrados/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Rodopsina/metabolismo , Transducción de Señal/fisiología
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