The Dose Makes the Poison: Nutritional Overload Determines the Life Traits of Blood-Feeding Arthropods

STERKEL, MARCOS; OLIVEIRA, JOSÉ HENRIQUE M.; BOTTINO-ROJAS, VANESSA; PAIVA-SILVA, GABRIELA O; OLIVEIRA, PEDRO L.

TRENDS IN PARASITOLOGY

ELSEVIER SCI LTD

Año: 2017

1471-4922

Vertebrate blood composition is heavily biased towards proteins, and hemoglobin, which is a hemeprotein, is by far the most abundant protein. Typically, hematophagous insects ingest blood volumes several times their weight before the blood meal. This barbarian feast offers an abundance of nutrients, but the degradation of blood proteins generates toxic concentrations of amino acids and heme, along with unparalleled microbiota growth. Despite this challenge, hematophagous arthropods have successfully developed mechanisms that bypass the toxicity of these molecules. While these adaptations allow hematophagous arthropods to tolerate their diet, they also constitute a unique mode of operation for cell signaling, immunity, and metabolism, the study of which may offer insights into the biology of disease vectors and may lead to novel vector-specific control methods. Excess amino acids are detoxified by oxidative pathways that generate a broad spectrum of metabolic intermediates. Interference with the functioning of these pathways results in severe, frequently lethal phenotypes which can be explored in the development of vector-control strategies.Heme overload is counteracted mainly by preventive antioxidant mechanisms that work to avoid oxidative insult such as heme detoxification and downregulation of metabolic ROS production, which are complemented by the action of antioxidant mechanisms that work through suppression of ROS after they are produced, including antioxidant enzymes such as catalase or SOD.Together with incoming nutrients from the blood meal, intense microbial growth occurs. In spite of a highly variable composition of intestinal microbiota, metagenomic studies have revealed the prevalence of a few bacterial phyla and the common presence of a selected group of genera. Studies on the role of specific components of the microbiota in the gut physiology are emerging.