RESUMEN
The role of dopamine (DA) is investigated in cuticular hydrocarbon biosynthesis in Drosophila melanogaster with three different approaches: use of DA-deficient mutants (dopa decarboxylase temperature sensitive mutants reared at restrictive temperature, and rescued by dopamine ingestion or by pale mutants partially rescued by a tyrosine hydroxylase construction), pharmacological treatments (tyrosine hydroxylase inhibitors) and topical application on decapitated flies. We report that DA specifically regulates diene hydrocarbon biosynthesis, which is female specific. Our results suggest that DA acts in adult flies within the first hours of imaginal life and that DA production from the brain is crucial for this process. Thus, DA contributes to reproduction in D. melanogaster by acting during a critical period during development of young adults.
Asunto(s)
Dopamina/metabolismo , Drosophila melanogaster/metabolismo , Hidrocarburos/metabolismo , Caracteres Sexuales , Envejecimiento/fisiología , Animales , ADN Complementario/genética , Dopa-Decarboxilasa/genética , Dopa-Decarboxilasa/metabolismo , Dopamina/farmacología , Drosophila melanogaster/efectos de los fármacos , Drosophila melanogaster/genética , Inhibidores Enzimáticos/farmacología , Femenino , Genes Letales/genética , Prueba de Complementación Genética , Hidrocarburos/análisis , Masculino , Mutación/genética , Tirosina 3-Monooxigenasa/antagonistas & inhibidores , Tirosina 3-Monooxigenasa/genética , alfa-Metiltirosina/farmacologíaRESUMEN
D. simulans and D. melanogaster present two types of polymorphism in their cuticular hydrocarbon (HC) composition. Especially both sexes of D. simulans, and D. melanogaster males display 7-tricosene (7T) as the major compound type [7T]s and [7T]m, or 7-pentacosene (7P) [7P]s and [7P]m. D. melanogaster females display 7,11-heptacosadiene (7,11HD) as the major compound: [7,11HD]m, or 5,9-heptacosadiene (5,9HD): [5,9HD]m. The [7P]s, [7P]m and [5,9HD]m are mainly present in central Africa. A significant correlation was found between latitude and the proportion of compounds with 23 and 25 carbon atoms, especially 7T and 7P in both sexes of D. melanogaster. [7P]m type of D. melanogaster, characterized with an excess of C25 compounds, presents a higher resistance against desiccation than [7T]m type, where C23 compounds are more abundant. These differences can be correlated with calculated HC fusion temperatures. Moreover, increasing the breeding temperature from 18 to 29 degrees C induces in D. melanogaster males an increase in 25C compounds and a decrease in 23C compounds, but the opposite effect in D. simulans. A mathematical model of biosynthesis, based on kinetics of elongation and decarboxylation enzymes, suggests that a simple variation of the efficiency of an elongation enzyme may account for the differences observed between the [7T]m and [7P]m types of D. melanogaster and [7T]s and [7P]s types D. simulans. Finally on the basis of the geographical distribution of the HC types of both Drosophila species, an evolutionary dispersal pathway is proposed and discussed in relation to the environment and reproductive behavior.
Asunto(s)
Drosophila melanogaster/genética , Drosophila/genética , Evolución Molecular , Hidrocarburos/metabolismo , Polimorfismo Genético , África , Alquenos/química , Animales , Temperatura Corporal , Cruzamiento , Carbono/química , Deshidratación , Femenino , Variación Genética , Geografía , Cinética , Masculino , Modelos Teóricos , Factores Sexuales , Especificidad de la Especie , TemperaturaRESUMEN
Several lines of evidence indicate an association between mitochondrial DNA (mtDNA) and the functioning of the nervous system. As neuronal development and structure as well as axonal and synaptic activity involve mitochondrial genes, it is not surprising that most mtDNA diseases are associated with brain disorders. Only one study has suggested an association between mtDNA and cognition, however. Here we provide direct evidence of mtDNA involvement in cognitive functioning. Total substitution of mtDNA was achieved by 20 repeated backcrosses in NZB/BlNJ (N) and CBA/H (H) mice with different mtDNA origins. All 13 mitochondrial genes were expressed in the brains of the congenic quartet. In interaction with nuclear DNA (nDNA), mtDNA modified learning, exploration, sensory development and the anatomy of the brain. The effects of mtDNA substitution persisted with age, increasing in magnitude as the mice got older. We observed different effects with input of mtDNA from N versus H mice, varying according to the phenotypes. Exchanges of mtDNA may produce phenotypes outside the range of scores observed in the original mitochondrial and nuclear combinations. These findings show that mitochondrial polymorphisms are not as neutral as was previously believed.