RESUMEN
Body size often shows adaptive clines in many ectotherms across altitude and latitude, but little is known about the genetic basis of these adaptive clines. Here we identify a polymorphism in the Dca (Drosophila cold acclimation) gene in Drosophila melanogaster that influences wing size, affects wing:thorax allometry and also controls a substantial proportion of the clinal wing-size variation. A polymorphism in the promoter region of Dca had two common alleles showing strong reciprocal clinal variation in frequency with latitude along the east coast of Australia. The Dca-237 allele increased towards the tropics where wing size is smaller. A within-population association study highlighted that an increase in the frequency of this allele decreased wing size but did not influence thorax size. A manipulated increase in the level of expression of Dca achieved through UAS-GAL4 was associated with a decrease in wing size but had no effect on thorax size. This was consistent with higher Dca expression levels in family lines with higher frequency of the Dca-237 allele. Genetic variation in the promoter region of the Dca gene appears to influence adaptive size variation in the eastern Australian cline of Drosophila melanogaster and accounts for more than 10% of the genetic variation in size within and between populations.
Asunto(s)
Adaptación Fisiológica/genética , Drosophila melanogaster/genética , Genética de Población , Polimorfismo Genético , Alas de Animales , Alelos , Animales , Australia , Secuencia de Bases , Tamaño Corporal , Proteínas de Drosophila/genética , Femenino , Frecuencia de los Genes , Genes de Insecto , Estudios de Asociación Genética , Genotipo , Masculino , Datos de Secuencia Molecular , Regiones Promotoras GenéticasRESUMEN
A cDNA-amplified fragment length polymorphisms approach was undertaken to screen for candidate genes associated with fenvalerate resistance in the AN02 strain of Helicoverpa armigera. Larvae and adults of this strain manifest approximately 50-fold resistance, which is suppressible by piperonyl butoxide and controlled by the semidominant gene RFen1 previously mapped to AFLP Linkage Group 13. Two cytochrome P450s (CYP337B1 and CYP4S1), one carboxylesterase-like protein and one glutathione transferase were found to be constitutively upregulated in resistant insects. Mapping of these potential detoxification genes showed that one of them, the novel P450 CYP337B1, was tightly linked to the resistance locus. This suggests that the RFen1(R) allele has a cis-acting effect on CYP337B1 expression, and possible trans-acting effects on expression of other genes.
Asunto(s)
ADN Complementario/genética , Genes de Insecto , Resistencia a los Insecticidas/genética , Mariposas Nocturnas/efectos de los fármacos , Mariposas Nocturnas/genética , Nitrilos/farmacología , Piretrinas/farmacología , Secuencia de Aminoácidos , Análisis del Polimorfismo de Longitud de Fragmentos Amplificados , Animales , Regulación hacia Abajo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica/fisiología , Ligamiento Genético , Marcadores Genéticos , Genotipo , Proteínas de Insectos/genética , Proteínas de Insectos/metabolismo , Insecticidas/farmacología , Datos de Secuencia Molecular , Regulación hacia ArribaRESUMEN
Microarrays have been used to examine changes in gene expression underlying responses to selection for increased stress resistance in Drosophila melanogaster, but changes in expression patterns associated with increased resistance to cold stress have not been previously reported. Here we describe such changes in basal expression levels in replicate lines following selection for increased resistance to chill coma stress. We found significant up- or down-regulation of expression in 94 genes on the Affymetrix Genome 2.0 array. Quantitative RT-PCR was used to confirm changes in expression of six genes. Some of the identified genes had previously been associated with stress resistance but no previously identified candidate genes for cold resistance showed altered patterns of expression. Seven differentially expressed genes that form a tight chromosomal cluster and an unlinked gene AnnX may be potentially important for cold adaptation in natural populations. Artificial selection for chill coma resistance therefore altered basal patterns of gene expression, but we failed to link these changes to plastic changes in expression under cold stress or to previously identified candidate genes for components of cold resistance.