Daily variations in the expression of genes related to dispersion and insecticide resistance in Triatoma infestans

GONZALO M. VARELA; BEATRIZ A. GARCIA; MARÍA M. STROPPA

Buenos Aires

Jornada; XX Jornadas Anuales de la Sociedad Argentina de Biología, XVII Jornadas de la Sociedad Uruguaya de Biociencias, Segundas Jornadas Rioplatenses de Biología; 2018

Sociedad Argentina de Biología y Sociedad Uruguaya de Biociencias

A variety of daily rhythms in behavioral, physiological, and metabolic processes have been observed in Triatoma infestans, the main vector of Chagas disease in the Southern Cone of Latin America. Pyrethroid insecticides have been the major means to control the vector populations and the massive use of chemical insecticides has lead to resistance. The flight dispersal and pyrethroid resistance are important factors for population recovery after insecticide spraying. In T. infestans flight muscles have two glycerol-3-phosphate dehydrogenase (GPDH) isoforms with an essential role in the flight metabolism. Isoforms exhibit a temporal expression patterns, sex-differentiated, and changes in relation to temperature and intake. On the other hand, one of the major mechanisms involved in the insecticide resistance is associated with an increase in the expression or activity of oxidative metabolism of the insecticide by cytochromes P450. Previous analyzes of cytochromes P450 and the NADPH cytochrome P450 reductase (CPR) genes expression, in resistant and susceptible populations to deltamethrin, revealed that P450 genes would be involved in the development of resistance to insecticides in T. infestans. In order to investigate the presence of rhythms in the expression of genes related with flight metabolism and insecticide resistance, we explored the daily expression profile of GPDH isoforms in flight muscles and the expression profile of the CPR gene and a P450 gene (CYP4EM7) in fat body from adults of T. infestans restrained under light/dark cycle (LD), constant light (LL), and constant dark (DD) conditions. In DD, GPDH-1 flight muscles of T. infestans showed a rhythmic pattern of transcription synchronous with a rhythmic profile of activity suggesting regulation by the endogenous circadian clock. Otherwise, the GPDH-2 expression analysis showed no regulation by the endogenous clock, but showed that an external factor, such as the dark/light period, was necessary for synchronization of GPDH-2 transcription and activity. In LD condition, the CPR gene expression profile of females showed two significant peaks, conserved in DD and lost in LL. These results suggest that CPR gene expression is under endogenous clock regulation. In males was not observed a rhythmic profile in the expression of the CPR gene. In LD, the expression of CYP4EM7 gene in males and females showed daily significant variations. The expression in females presented a peak at dawn and in males showed two significant peaks, one at dawn and other at sunset. This study would provide potentially useful information to analyze the temporal regulation of important biological processes, such dispersal and insecticide resistance.