To remove the variant surface protein from the membrane, required for parasite differentiation into the procyclic insect form. Gp63-like molecules have been observed on the cell surface of symbiont-harboring trypanosomatids. Importantly, the symbiont containing A. deanei displays a higher amount of leishmanolysin-like molecules at the surface compared to the aposymbiotic strain, which are unable to colonize insects. As anti-gp63 antibodies decrease protozoan-insect interactions, our results reinforce the idea that the presence of such interactions caused the expansion of this gene family in endosymbiont-bearing organisms. This class of cysteine peptidase is represented by cruzain or cruzipain, major lysosomal proteinases of T. cruzi expressed by parasites found in insect and vertebrate hosts, and encoded by a large gene family. In T. cruzi, these enzymes have important roles in various aspects of the host/parasite relationship and in intracellular digestion as a nutrient source. Conversely, the low copy number of this class of lysosomal peptidase in symbiont-containing trypanosomatids seems to be related to their low nutritional requirements. Amastins constitute a third large gene family in the A. deanei and S. culicis genomes that encodes surface proteins. Initially described in T. cruzi, amastin genes have also been identified in various Leishmania species, in A. deanei and in another related insect parasite, Leptomonas seymouri. In Leishmania, amastins constitute the largest gene family with gene expression that is regulated during the parasite life cycle. As amastin has no sequence similarity to any other known protein, its function remains unknown. In this work, we identified 31 genes with sequences belonging to all four Orbifloxacin sub-families of amastins in the genome of A. deanei and 14 copies of amastin genes in S. culicis. Similar to Leishmania, members of all four amastin subfamilies were identified in symbiont-containing species. The putative proteome of symbiont-bearing trypanosomatids revealed that these microorganisms exhibit unique features when compared to other protozoa of the same family and that they are most closely related to Leishmania species. Most relevant are the differences in the genes related to cytoskeleton, paraflagellar and kinetoplast structures, along with a unique pattern of peptidase gene organization that may be related to the presence of the symbiont and of the monoxenic life style. The symbiotic bacteria of A. deanei and S. culicis are phylogenetically related with a common ancestor, most likely a b-proteobacteria of the Alcaligenaceae family. The genomic content of these symbionts is highly reduced, indicating gene loss and/or transfer to the host cell nucleus. In addition, we confirmed that both bacteria contain genes that encode enzymes that complement several Folinic acid calcium salt pentahydrate metabolic routes of the host trypanosomatids, supporting the fitness of the symbiotic relationship. Aerobic life uses the oxidizing power of O2 for various fundamental biochemical processes including energy generation in form of ATP synthesis realised by a controlled stepwise reduction of molecular oxygen. However, oxygen consumption has severe side effects, since, inevitably, reactive oxygen species are produced as by-products. If not countered or buffered, these ROS attack and disturb biological molecules and cellular structures leading to a state of impaired physiology also known as oxidative stress.