Project description:Triatoma infestans is the most relevant vector of Chagas disease in the southern cone of South America. Since its genome has not yet been studied, sequencing of Expressed Sequence Tags (ESTs) is one of the most powerful tools for efficiently identifying large numbers of expressed genes in this insect vector.In this work, we generated 826 ESTs, resulting in an increase of 47% in the number of ESTs available for T. infestans. These ESTs were assembled in 471 unique sequences, 151 of which represent 136 new genes for the Reduviidae family.Among the putative new genes for the Reduviidae family, we identified and described an interesting subset of genes involved in development and reproduction, which constitute potential targets for insecticide development.
Project description:We found that assassin bugs from the earliest-diverging subfamily of higher Reduviidae (Peiratinae), as well as a subfamily closely related to Triatominae (Stenopodainae) have venom that is highly similar in composition to that produced by previously examined reduviids from Harpactorinae and Reduviinae. This finding suggests that venom composition has been largely stable due to purifying selection among the higher Reduviidae, which is consistent with the ancient origin of venom in the ancestors of Heteroptera 250–300 million years ago (Sunagar and Moran 2015; Walker et al. 2018a). This near homogeneity of venom composition is perhaps surprising considering that reduviid predators have evolved numerous instances of prey specialization and specialized hunting strategies that might be expected to co-evolve with venom. Possibly, further studies focussing on species with more specialized hunting strategies, or different kinds of venom bioactivities, will uncover more nuanced venom adaptations. Alternatively, it is possible that the protease-rich venoms of predatory reduviids are simply well-suited to myriad different hunting strategies. These data are consistent with other examples where venoms are surprisingly similar despite great differences in biology, for example between solitary and eusocial bees. A more detailed picture of venom evolution in Reduviidae would examine venom produced by the early-diverging Phymatine complex as well as venoms of non-reduviid cimicomorphs, prey specialists such as the arachnophagous Emesinae and the myrmecophagous Holoptilinae, and some of the many groups that employ hunting specializations, such as the use of plant resins to catch prey (Hwang and Weirauch 2012). Within Triatominae, examination of saliva produced by additional species from multiple lineages (especially those that switched to blood-feeding independently, if the subfamily is shown to be polyphyletic) and including generalists and specialists on different host taxa and species associated especially with nests and burrows will be informative. The venoms of predatory reduviids such as Zelurus spp. and Opisthacidius spp. that are most closely related to Triatominae, and share some behaviours such as habitation of bird nests by Opisthacidius spp. may also provide more information about the evolution of triatomine saliva.
Project description:Apyrase activity is present in the saliva of haematophagous arthropods. It is related to blood-feeding because of the apyrase ability to hydrolyse ADP, a key component of platelet aggregation. Five apyrases with apparent molecular masses of 88, 82, 79, 68 and 67 kDa were identified in the saliva of the vector of Chagas disease, Triatoma infestans. The large size observed during purification of these enzymes suggested oligomerization. In the present study, we confirmed, using gel-filtration and analytical ultracentrifugation, the presence of apyrase oligomers with molecular masses of 200 kDa in the saliva. Electrophoretic analyses showed that disulphide bonds were involved in homo-oligomerization. In addition, heterogeneity in disulphide bonds and in pI was detected, with the pI ranging from 4.9 to 5.4. The present study gives the first insights into the quaternary structure of soluble apyrases.