Biology subjects

Zeferino, T. G.

Publications and source records attributed to Zeferino, T. G..

5 recordsLinked to original sources

bioRxiv2024

The role of prooxidants and antioxidants in shaping life-history and parasite tolerance in Anopheles mosquitoes

Oxidative homeostasis plays important roles in physiology, for reactive oxygen species not only lead to damaging oxidative stress, but also regulate important physiological processes like immunity and longevity. ROS are therefore expected to be a key factor underlying many host-parasite interactions. We evaluated the role of the hosts oxidative status on the outcome of infection with the mosquito Anopheles gambiae infected by the microsporidian Vavraia culicis. To do so, we manipulated the oxidative status of the mosquitoes by feeding them early (the first four days after emergence) or late (from five days after emergence onwards) either a standard sugar source or one supplemented with a prooxidant (hydrogen peroxide) or antioxidant (vitamin C), and then measured the longevity and fecundity of uninfected and infected mosquitoes and (for infected mosquitoes) the parasite load at a given day (13 days after emergence) or when the mosquitoes died. The prooxidant generally increased longevity, but if consumed early after emergence its impact was lessened by the infection by Vavraia. In contrast the antioxidant increased fecundity, and the impact was not affected by the status of infection or by the timing of consumption. Finally, early consumption of both supplements increased Vavraias spore load at 13 days after emergence and at death. In contrast, late consumption enhanced the parasites growth late in the mosquitos life. Thus, our experiment revealed complex effects of prooxidant and antioxidant consumption, emphasising the critical role of timing and context in shaping their influence on biological traits.

evolutionary biology↗

bioRxiv2024

Mosquitoes self-medicate according to the dynamics of a microsporidian infection

Immune responses protect against infectious diseases but often incur physiological costs, such as oxidative stress. In mosquitoes, these costs may shape behaviours that help regulate oxidative balance, potentially including the consumption of nectar containing bioactive substances like prooxidants and antioxidants. We investigated whether Anopheles gambiae adjust their preferences for diets with such substances when they are infected with the microsporidian parasite Vavraia culicis. Using sugar solutions supplemented with hydrogen peroxide (a prooxidant) or ascorbic acid (an antioxidant), we assessed the feeding preferences of uninfected and infected mosquitoes at different ages and measured the effects of these diets on oxidative homeostasis, parasite load, and lifespan. Infected mosquitoes initially preferred the prooxidant diet, which reduced parasite load and extended lifespan, before shifting their preference towards the antioxidant diet as infection progressed. In contrast, uninfected mosquitoes consistently preferred the unsupplemented sugar, likely to avoid oxidative stress induced by the supplemented diets, which, surprisingly, also increased their lifespan. These results suggest a form of self-medication, despite benefits in uninfected individuals, where mosquitoes dynamically adjust their dietary choices throughout infection. We propose that such dietary strategies may be widespread among mosquitoes, helping them manage oxidative stress, with potential implications for vector-pathogen interactions and the success of biological control programmes.

evolutionary biology↗

bioRxiv2024

Energetic shifts predict the mortality of Anopheles gambiae

Life history theory predicts that resource allocation adapts to ecological and evolutionary pressures. We investigated resource and energy in the malaria vector Anopheles gambiae following exposure to two stressors: blood meals and infection by the microsporidian Vavraia culicis. Our findings reveal the costs of blood feeding and parasitism on longevity, highlighting trade-offs in lifetime protein, carbohydrate, and lipid reserves. Notably, shifts in carbohydrate-to-lipid ratios were associated with survival likelihood, with survivors exhibiting higher resource reserves and uniquely transitioning from carbohydrate to lipid utilization, a pattern absent in non-survivors. This study emphasizes the coevolutionary dynamics between hosts and parasites, highlighting how intrinsic and extrinsic factors shape host physiology. More broadly, our results underscore the importance of integrating host metabolic responses into ecological and epidemiological frameworks to enhance understanding of parasite transmission and survival strategies. HighlightsO_LIHaving a blood meal did not affect mosquito longevity, resource content or V. culicis parasitemia. C_LIO_LIAlive mosquitoes harboured fewer spores than mosquitoes that had just died, independently of the stage of infection, supporting the parasite load upon death hypothesis. C_LIO_LIAlive mosquitoes exhibited a shift in their usage of the energetic reserves (i.e., carbohydrates to lipids) late in life, which mosquitoes at death did not. C_LIO_LIOur findings support the hypothesis that Plasmodium may have coevolved with its vectors dynamics of lipid release, a nutrient essential for its development. C_LI

evolutionary biology↗

bioRxiv2024

Dexrazoxane as a viable microsporidia control agent in Anopheles gambiae

Microsporidia have long been proposed as biological agents for controlling disease vectors and the parasites they transmit. However, their study in vector biology has been constrained due to challenges in manipulating microsporidia within hosts. In this study, we investigated the effect of Dexrazoxane, a candidate drug against microsporidiosis, on the establishment and development of Vavraia culicis infection in its natural host, the mosquito Anopheles gambiae, the main malaria vector. Our findings show that Dexrazoxane significantly reduces spore load, particularly in mosquitoes reared individually, without affecting the overall infection success of the parasite. This result aligns with studies in Caenorhabditis elegans, where Dexrazoxane inhibited new spore production without hindering initial spore integration into the host gut cells. Dexrazoxanes DNA topoisomerase II inhibitor mechanism likely explains its impact on mosquito development, as larvae exposed to the drug failed to emerge as adults. These findings highlight Dexrazoxanes potential as a viable tool for controlling microsporidia in adult mosquitoes and hope to enhance the study of mosquito-microsporidia interactions. Further research is required to explore its broader application in vector-borne disease control, including malaria.

ecology↗

bioRxiv2024

Sublethal insecticide exposure of larvae affects the blood-feeding behaviour of adult mosquitoes

Because of their widespread use for the control of disease vectors and agricultural pests, insecticides have become ubiquitous in the environment, including in water bodies harbouring mosquito larvae. These are therefore continuously exposed to sublethal doses. Since this has long-lasting effects on the mosquitoes physiology and life-history, we expected that it may also affect behaviours that underlie the mosquitoes population dynamics and disease epidemiology, such as egg-laying preference, blood-feeding motivation, and host-seeking behaviour. Using an insecticide-sensitive and a resistant strain of Anopheles gambiae, an important malaria vector, we evaluated the effects of sublethal exposure to permethrin throughout larval development on the resistance to the insecticide in adults, on host-seeking behaviour, on the motivation to blood-feed, and on egg-laying behaviour. Resistance, assessed by rates of knock-down and mortality, were similar between exposed and unexposed mosquitoes. However, exposure to sublethal doses of insecticide caused female mosquitoes to split their egg clutches into two parts and increased the motivation of mosquitoes to seek blood meals through permethrin-treated nets, regardless of their sensitivity to the insecticide. Furthermore, it enhanced the natural preference of resistant strains for permethrin-treated nets and increased their blood-meal size. Our results thus suggest that sublethal insecticide concentrations in larval breeding sites have important epidemiological implications.

evolutionary biology↗