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1.  New insights in the interactions between African trypanosomes and tsetse flies 
doi:10.3389/fcimb.2013.00063
PMCID: PMC3797390  PMID: 24137569
Trypanosoma; African trypanosomes; parasite cycle; tsetse fly; vector; infection; interaction
2.  An insight into the sialome of Glossina morsitans morsitans 
BMC Genomics  2010;11:213.
Background
Blood feeding evolved independently in worms, arthropods and mammals. Among the adaptations to this peculiar diet, these animals developed an armament of salivary molecules that disarm their host's anti-bleeding defenses (hemostasis), inflammatory and immune reactions. Recent sialotranscriptome analyses (from the Greek sialo = saliva) of blood feeding insects and ticks have revealed that the saliva contains hundreds of polypeptides, many unique to their genus or family. Adult tsetse flies feed exclusively on vertebrate blood and are important vectors of human and animal diseases. Thus far, only limited information exists regarding the Glossina sialome, or any other fly belonging to the Hippoboscidae.
Results
As part of the effort to sequence the genome of Glossina morsitans morsitans, several organ specific, high quality normalized cDNA libraries have been constructed, from which over 20,000 ESTs from an adult salivary gland library were sequenced. These ESTs have been assembled using previously described ESTs from the fat body and midgut libraries of the same fly, thus totaling 62,251 ESTs, which have been assembled into 16,743 clusters (8,506 of which had one or more EST from the salivary gland library). Coding sequences were obtained for 2,509 novel proteins, 1,792 of which had at least one EST expressed in the salivary glands. Despite library normalization, 59 transcripts were overrepresented in the salivary library indicating high levels of expression. This work presents a detailed analysis of the salivary protein families identified. Protein expression was confirmed by 2D gel electrophoresis, enzymatic digestion and mass spectrometry. Concurrently, an initial attempt to determine the immunogenic properties of selected salivary proteins was undertaken.
Conclusions
The sialome of G. m. morsitans contains over 250 proteins that are possibly associated with blood feeding. This set includes alleles of previously described gene products, reveals new evidence that several salivary proteins are multigenic and identifies at least seven new polypeptide families unique to Glossina. Most of these proteins have no known function and thus, provide a discovery platform for the identification of novel pharmacologically active compounds, innovative vector-based vaccine targets, and immunological markers of vector exposure.
doi:10.1186/1471-2164-11-213
PMCID: PMC2853526  PMID: 20353571
3.  Expression of Procyclin mRNAs during Cyclical Transmission of Trypanosoma brucei 
PLoS Pathogens  2005;1(3):e22.
Trypanosoma brucei, the parasite causing human sleeping sickness, relies on the tsetse fly for its transmission. In the insect, EP and GPEET procyclins are the major surface glycoproteins of procyclic (midgut) forms of the parasite, with GPEET predominating in the early procyclic form and two isoforms of EP in the late procyclic form. EP procyclins were previously detected on salivary gland trypanosomes, presumably epimastigotes, by immunoelectron microscopy. However, no procyclins could be detected by mass spectrometry when parasites were isolated from infected glands. We have used qualitative and quantitative RT-PCR to analyse the procyclin mRNAs expressed by trypanosomes in the tsetse midgut and salivary glands at different time points after infection. The coding regions of the three EP isoforms (EP1, EP2 and EP3) are extremely similar, but their 3′ untranslated regions contain unique sequences that make it possible to assign the cDNAs amplified by this technique. With the exception of EP2, we found that the spectrum of procyclin mRNAs expressed in the midgut mirrors the protein repertoire of early and established procyclic forms. Surprisingly, procyclin mRNAs, including that of GPEET, are present at relatively high levels in salivary gland trypanosomes, although the proteins are rarely detected by immunofluorescence. Additional experiments using transgenic trypanosomes expressing reporter genes or mutant forms of procyclin point to a mechanism of translational or post-translational control, involving the procyclin coding regions, in salivary gland trypanosomes. It is widely accepted that T. brucei always has a coat of either variant surface glycoprotein or procyclin. It has been known for many years that the epimastigote form does not have a variant surface glycoprotein coat. The finding that this life cycle stage is usually negative for procyclin as well is new, and means that the paradigm will need to be revised.
Synopsis
The tropical parasite Trypanosoma brucei relies on the tsetse fly for its transmission between mammals. The parasite first establishes an infection in the fly midgut then migrates and colonizes the salivary glands. A paradigm in trypanosome biology is that parasites in contact with the mammalian host are covered by variant surface glycoproteins, enabling them to evade the immune system, while all other life cycle stages are covered by repetitive glycoproteins known as procyclins.
In this publication the authors investigated the expression pattern of procyclins in all life cycle stages in infected tsetse flies, including epimastigote and metacyclic forms in the salivary glands. These stages are usually neglected as, in contrast to trypanosomes from the midgut, they cannot be cultured. The researchers showed that the vast majority of trypanosomes in the salivary glands have no procyclin coat although the levels of procyclin messenger RNAs are comparatively high. Experiments with reporter genes indicated that procyclin expression in the glands is regulated by the coding region. The lack of procyclins on salivary gland trypanosomes leads to the prediction that the epimastigote form possesses a novel surface coat that may be responsible for the tight binding of the parasite to gland tissue.
doi:10.1371/journal.ppat.0010022
PMCID: PMC1277927  PMID: 16276404

Results 1-3 (3)