An insight into the sialome of blood-feeding Nematocera

Abstract

Within the Diptera and outside the suborder Brachycera, the blood feeding habit occurred at least twice, producing the present day sand flies, and the Culicomorpha, including the mosquitoes (Culicidae), black flies (Simulidae), biting midges (Ceratopogonidae) and frog feeding flies (Corethrellidae). Alternatives to this scenario are also discussed. Successful blood feeding requires adaptations to antagonize the vertebrate's mechanisms of blood clotting, platelet aggregation, vasoconstriction, pain and itching, which are triggered by tissue destruction and immune reactions to insect products. Saliva of these insects provides a complex pharmacological armamentarium to block these vertebrate reactions. With the advent of transcriptomics, the sialomes (from the Greek word sialo=saliva) of at least two species of each of these families have been studied (except for the frog feeders), allowing an insight into the diverse pathways leading to today's salivary composition within the Culicomorpha, having the sand flies as an outgroup. This review catalogs 1,288 salivary proteins in 10 generic classes comprising over 150 different protein families, most of which we have no functional knowledge. These proteins and many sequence comparisons are displayed in a hyperlinked spreadsheet that hopefully will stimulate and facilitate the task of functional characterization of these proteins, and their possible use as novel pharmacological agents and epidemiological markers of insect vector exposure.

Tick attachment cement – reviewing the mysteries of a biological skin plug system

“…Catechol oxidase activity might be involved in quinone formation, again suggesting a possible role for tanning in cement formation. However, this enzymatic activity might also be associated with blood feeding; a salivary peroxidase of the mosquito Anopheles albimanus Wiedemann, 1820 also shows catechol oxidase activity and is known to cause vasodilation (Ribeiro & Valenzuela, 1999; Ribeiro, Mans & Arca, 2010). Similarly, the observed weak peroxidase activity might arise from a glutathione peroxidase, which is known from tick saliva and probably acts as an anti‐inflammatory substance at the feeding site (Tirloni et al ., 2015).…”

A draft genome sequence of an invasive mosquito: an ItalianAedes albopictus

“…82,83 Salivary genes of blood feeding arthropods, perhaps also as a consequence of the host immune pressure, exhibit an accelerated evolutionary rate and this explains, at least in part, both the elevated diversification observed when comparing the salivary repertoires of anopheline to culicine mosquitoes and the presence of a substantial number of genus-specific salivary genes and gene families. 84,85 A total of 68 putative secreted products, mostly found in adult female saliva or expressed in the salivary glands of both sexes, were identified in a previous A. albopictus sialotranscriptome analysis.…”

Evolution of Vertebrate Hemostatic and Inflammatory Control Mechanisms in Blood-Feeding Arthropods

“…If protein family members have similar functions, no definite orthologous relationships can be inferred using phylogenetic analysis [8,13,72] . Even if closely related lineages possess the same protein families, members in different lineages will not have similar functions.…”