Leptomonas wallacei Shows Distinct Morphology and Surface Carbohydrates Composition Along the Intestinal Tract of Its Host Oncopeltus fasciatus (Hemiptera: Lygaeidae) and in Axenic Culture

Abstract

Leptomonas wallacei is a monoxenic trypanosomatid that colonizes the digestive tract of the phytophagous hemipteran Oncopeltus fasciatus. This infection was specific and took place exclusively in midgut intestinal ventricles V3 and V4, and in the hindgut. Abundances of parasites in the hindgut were 54% less than those in the hindgut. Parasites in the hindgut were more slender and had a longer flagellum than those from the hindgut, which were rounded, with a shorter flagellum. Moreover, hindgut forms expressed sugar residues on the cell surface, recognized by the lectins from Griffonia simplicifolia-I (alpha-galactose, alpha-N-acetyl-galactosamine) and Helix pomatia (N-acetyl-galactosamine); those sugar residues were not present in protozoa from the midgut. In culture, parasites were morphologically similar to midgut forms, but differed from them because they did not express sugar residues that bind to lectin (beta-galactose(1-3) N-acetyl-galactosamine) from Arachis hypogaea.

Transovum Transmission of Trypanosomatid Cysts in the Milkweed Bug, Oncopeltus fasciatus

“…Nevertheless, there are very few reports on the life cycles of insect trypanosomatids [5]. Oncopeltus fasciatus is a natural host of Leptomonas wallacei , which is a gut-restricted insect trypanosomatid [6]–[8]. L. wallacei develops free-swimming promastigotes, mainly in the midgut, and promastigotes attached to the intestine wall, mostly in the hindgut [6]–[8].…”

“…Oncopeltus fasciatus is a natural host of Leptomonas wallacei , which is a gut-restricted insect trypanosomatid [6]–[8]. L. wallacei develops free-swimming promastigotes, mainly in the midgut, and promastigotes attached to the intestine wall, mostly in the hindgut [6]–[8]. Promastigotes often display encysting stages (straphangers) adhered to the flagellum; these cystic resistant forms are frequently found in clusters of two to four.…”

“…Promastigotes often display encysting stages (straphangers) adhered to the flagellum; these cystic resistant forms are frequently found in clusters of two to four. Free, mature cysts can also be found in the lumen of the intestinal tract, especially in the hindgut [6]–[8].…”

“…More recently, O. fasciatus has become a laboratory model for reports on molecular development of insects [12], [13], transcriptomes [14], [15], as well as several aspects of the interaction of these insects with their natural [7], [8] or experimental trypanosomatid parasites [16]–[19].…”

Kinetics of pyrophosphate-driven proton uptake by acidocalcisomes of Leptomonas wallacei

“…The trypanosomatidae family comprises unicellular eukaryotes that are able to infect a broad range of organisms such as mammalians, fishes, plants, and insects causing a wide spectrum of diseases of social, economical, and medical importance. Leptomonas wallacei is a trypanosomatid parasite that was first isolated by Romeiro et al [1] from the intestinal tract of the phytophagous hemipteran Oncopeltus fasciatus and since then has been used as a model for studies of the interaction between trypanosomatids and the midgut of the insect vector [2,3]. A remarkable characteristic of these parasites is their ability to form cysts.…”