Circadian clock of Aedes aegypti: effects of blood-feeding, insemination and RNA interference

Abstract

Mosquitoes are the culprits of some of the most important vector borne diseases. A species’ potential as a vector is directly dependent on their pattern of behaviour, which is known to change according to the female’s physiological status such as whether the female is virgin/mated and unfed/blood-fed. However, the molecular mechanism triggered by and/or responsible for such modulations in behaviour is poorly understood. Clock genes are known to be responsible for the control of circadian behaviour in several species. Here we investigate the impact mating and blood-feeding have upon the expression of these genes in the mosquito Aedes aegypti . We show that blood intake, but not insemination, is responsible for the down-regulation of clock genes. Using RNA interference, we observe a slight reduction in the evening activity peak in the fourth day after dstim injection. These data suggest that, as in Drosophila , clock gene expression, circadian behaviour and environmental light regimens are interconnected in Ae. aegypti .

Locomotor activity in males of Aedes aegypti can shift in response to females’ presence

“…Our design relied on the use of activity monitors to measure any changes in male locomotor/flight activity when a female is present, in relation to the activity of a solitary male. Activity monitors have been used extensively for the study of circadian rhythm in insects, especially in Drosophila [ 48 , 58 , 59 ], but also in other dipteran species [ 49 , 50 , 55 , 60 – 64 ]. The advantages of using this system include the possibility of monitoring several individuals at the same time, under the same conditions of photoperiod, temperature and humidity, and the fact that all the data are collected on an automated computer system, eliminating the subjectivity of the observer.…”

“…Data generated when individuals were in the DD regime were used to calculate the period length and the power of activity. In order to calculate these parameters, individuals are monitored for at least 10 days in free running condition (constant darkness), recommended as a regular procedure when studying the circadian rhythms of activity in insects [ 25 , 48 – 50 ]. Light/dark cycles are responsible for synchronizing the endogenous clock, which means that in a LD cycle, the peak(s) of activity will happen every day at the same time.…”

Temporal and Spatial Evolution of Dengue Incidence in Brazil, 2001-2012

“…Previous research has indicated that the major risk areas for dengue are: urban areas, areas with high population density, areas with informal settlements and in places where sanitation conditions are not satisfactory. In those areas, the female mosquito finds conditions in which it can feed and reproduce [29, 30]. Further, the Brazilian coast is densely populated since the major Brazilian urban centers are located on the coast or near it (e.g., São Paulo, Rio de Janeiro and Salvador).…”

Sex and rhythms in sandflies and mosquitoes: An appreciation of the work of Alexandre Afranio Peixoto (1963–2013)

“…Blood-feeding had no effect on cyc expression, so the effect of blood feeding appears limited to the negative regulators per and tim in the sandfly. In contrast however, in Aedes aegypti , the vector of dengue and yellow fever, blood feeding led to a dramatic downregulation of both negative ( per/tim ) and positive ( Clk/cyc ) factors in the body, with a gentler reduction in the head ( Gentile et al, 2013 ).…”