RESUMEN
The Sap47 gene of Drosophila melanogaster encodes a highly abundant 47â kDa synaptic vesicle-associated protein. Sap47 null mutants show defects in synaptic plasticity and larval olfactory associative learning but the molecular function of Sap47 at the synapse is unknown. We demonstrate that Sap47 modulates the phosphorylation of another highly abundant conserved presynaptic protein, synapsin. Site-specific phosphorylation of Drosophila synapsin has repeatedly been shown to be important for behavioural plasticity but it was not known where these phospho-synapsin isoforms are localized in the brain. Here, we report the distribution of serine-6-phosphorylated synapsin in the adult brain and show that it is highly enriched in rings of synapses in the ellipsoid body and in large synapses near the lateral triangle. The effects of knockout of Sap47 or synapsin on olfactory associative learning/memory support the hypothesis that both proteins operate in the same molecular pathway. We therefore asked if this might also be true for other aspects of their function. We show that knockout of Sap47 but not synapsin reduces lifespan, whereas knockout of Sap47 and synapsin, either individually or together, affects climbing proficiency, as well as plasticity in circadian rhythms and sleep. Furthermore, electrophysiological assessment of synaptic properties at the larval neuromuscular junction (NMJ) reveals increased spontaneous synaptic vesicle fusion and reduced paired pulse facilitation in Sap47 and synapsin single and double mutants. Our results imply that Sap47 and synapsin cooperate non-uniformly in the control of synaptic properties in different behaviourally relevant neuronal networks of the fruitfly.
Asunto(s)
Conducta Animal/fisiología , Proteínas de Drosophila/genética , Drosophila melanogaster/fisiología , Locomoción/genética , Longevidad/genética , Mutación/genética , Proteínas del Tejido Nervioso/genética , Plasticidad Neuronal/genética , Sinapsinas/metabolismo , Animales , Encéfalo/metabolismo , Ritmo Circadiano/fisiología , Drosophila melanogaster/genética , Larva/metabolismo , Unión Neuromuscular/metabolismo , Fosforilación , Fosfoserina/metabolismo , Isoformas de Proteínas/metabolismo , Sinapsinas/genéticaRESUMEN
Royal jelly is a nutritious secretion produced by nurse honeybees to provision queens and growing larvae. Major proteins of royal jelly are mutually similar, and they all belong to the MRJP/yellow protein family (pfam03022). The mrjp3 loci in four traditional honeybee species (Apis mellifera, Apis cerana,Apis dorsata, and Apis florea) were sequenced and found to share high sequence and structural similarities. PCR analyses confirmed the presence of an extensive repetitive region, which showed size and sequence polymorphisms in all species. The evolutionary history of mrjp genes and their repetitive regions was reconstructed from their nucleotide sequences. The analyses proved that the repeat region appeared early in the evolution of the mrjp gene family and that the extreme elongation of the repeat is mrjp3 specific. In the MRJPs was documented a correlation between nitrogen content and repeat length. Therefore, it is argued that the repeat occurred due to a selection for an increase in nitrogen storage for a more efficient nutrition of queens and larvae.
