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Social motility of African trypanosomes is a property of a distinct life-cycle stage that occurs early in tsetse fly transmission.

Imhof S, Knüsel S, Gunasekera K, Vu XL, Roditi I - PLoS Pathog. (2014)

Bottom Line: These findings link the phenomenon of SoMo in vitro to the parasite forms found during the first 4-7 days of a midgut infection.Moreover, the process can be uncoupled from colonisation of the salivary glands.Although they are the major surface proteins of procyclic forms, EP and GPEET are not essential for SoMo, nor, as shown previously, are they required for near normal colonisation of the fly midgut.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cell Biology, University of Bern, Bern, Switzerland; Graduate School of Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.

ABSTRACT
The protozoan pathogen Trypanosoma brucei is transmitted between mammals by tsetse flies. The first compartment colonised by trypanosomes after a blood meal is the fly midgut lumen. Trypanosomes present in the lumen-designated as early procyclic forms-express the stage-specific surface glycoproteins EP and GPEET procyclin. When the trypanosomes establish a mature infection and colonise the ectoperitrophic space, GPEET is down-regulated, and EP becomes the major surface protein of late procyclic forms. A few years ago, it was discovered that procyclic form trypanosomes exhibit social motility (SoMo) when inoculated on a semi-solid surface. We demonstrate that SoMo is a feature of early procyclic forms, and that late procyclic forms are invariably SoMo-negative. In addition, we show that, apart from GPEET, other markers are differentially expressed in these two life-cycle stages, both in culture and in tsetse flies, indicating that they have different biological properties and should be considered distinct stages of the life cycle. Differentially expressed genes include two closely related adenylate cyclases, both hexokinases and calflagins. These findings link the phenomenon of SoMo in vitro to the parasite forms found during the first 4-7 days of a midgut infection. We postulate that ordered group movement on plates reflects the migration of parasites from the midgut lumen into the ectoperitrophic space within the tsetse fly. Moreover, the process can be uncoupled from colonisation of the salivary glands. Although they are the major surface proteins of procyclic forms, EP and GPEET are not essential for SoMo, nor, as shown previously, are they required for near normal colonisation of the fly midgut.

No MeSH data available.


Related in: MedlinePlus

The time-point of migration is density dependent.Different numbers of early procyclic forms of AnTat 1.1 were resuspended in 5 µl and pipetted onto 0.4% agarose plates. Photographs of the plates were taken every 24 h. The scale bar is 1 cm.
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ppat-1004493-g001: The time-point of migration is density dependent.Different numbers of early procyclic forms of AnTat 1.1 were resuspended in 5 µl and pipetted onto 0.4% agarose plates. Photographs of the plates were taken every 24 h. The scale bar is 1 cm.

Mentions: As a first step we optimised the plating protocol for the fly-transmissible strain AnTat 1.1. The main differences from the previously published protocol [20] are that we used SDM79 rather than SM as the medium and cells were not preincubated with ethanol before plating. In addition, low melting temperature agarose was replaced by normal agarose, rendering the plates more robust. While establishing the SoMo assay we observed that the time-point when radial protrusions formed differed between experiments. To test if the cell density influenced the assay, different numbers of cells were pipetted onto the plates (Figure 1). When 8×105 cells were plated in a volume of 5 µl, fingers were already visible after 24 hours. Cells plated at a density of 4×105 or 2×105 cells in 5 µl showed SoMo after 48 or 72 hours, respectively. It was reported previously that the doubling time of trypanosomes on plates is 24 h [20]. This suggests that the cells reach a threshold number of approximately 1.6×106 before migration starts. We observed that when communities were plated on their own, the radial projections always grew in a clockwise direction (Figure 1, 72 h). This directionality was overridden, however, when cells sensed and avoided neighbouring communities (Figure 2).


Social motility of African trypanosomes is a property of a distinct life-cycle stage that occurs early in tsetse fly transmission.

Imhof S, Knüsel S, Gunasekera K, Vu XL, Roditi I - PLoS Pathog. (2014)

The time-point of migration is density dependent.Different numbers of early procyclic forms of AnTat 1.1 were resuspended in 5 µl and pipetted onto 0.4% agarose plates. Photographs of the plates were taken every 24 h. The scale bar is 1 cm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4214818&req=5

ppat-1004493-g001: The time-point of migration is density dependent.Different numbers of early procyclic forms of AnTat 1.1 were resuspended in 5 µl and pipetted onto 0.4% agarose plates. Photographs of the plates were taken every 24 h. The scale bar is 1 cm.
Mentions: As a first step we optimised the plating protocol for the fly-transmissible strain AnTat 1.1. The main differences from the previously published protocol [20] are that we used SDM79 rather than SM as the medium and cells were not preincubated with ethanol before plating. In addition, low melting temperature agarose was replaced by normal agarose, rendering the plates more robust. While establishing the SoMo assay we observed that the time-point when radial protrusions formed differed between experiments. To test if the cell density influenced the assay, different numbers of cells were pipetted onto the plates (Figure 1). When 8×105 cells were plated in a volume of 5 µl, fingers were already visible after 24 hours. Cells plated at a density of 4×105 or 2×105 cells in 5 µl showed SoMo after 48 or 72 hours, respectively. It was reported previously that the doubling time of trypanosomes on plates is 24 h [20]. This suggests that the cells reach a threshold number of approximately 1.6×106 before migration starts. We observed that when communities were plated on their own, the radial projections always grew in a clockwise direction (Figure 1, 72 h). This directionality was overridden, however, when cells sensed and avoided neighbouring communities (Figure 2).

Bottom Line: These findings link the phenomenon of SoMo in vitro to the parasite forms found during the first 4-7 days of a midgut infection.Moreover, the process can be uncoupled from colonisation of the salivary glands.Although they are the major surface proteins of procyclic forms, EP and GPEET are not essential for SoMo, nor, as shown previously, are they required for near normal colonisation of the fly midgut.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cell Biology, University of Bern, Bern, Switzerland; Graduate School of Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.

ABSTRACT
The protozoan pathogen Trypanosoma brucei is transmitted between mammals by tsetse flies. The first compartment colonised by trypanosomes after a blood meal is the fly midgut lumen. Trypanosomes present in the lumen-designated as early procyclic forms-express the stage-specific surface glycoproteins EP and GPEET procyclin. When the trypanosomes establish a mature infection and colonise the ectoperitrophic space, GPEET is down-regulated, and EP becomes the major surface protein of late procyclic forms. A few years ago, it was discovered that procyclic form trypanosomes exhibit social motility (SoMo) when inoculated on a semi-solid surface. We demonstrate that SoMo is a feature of early procyclic forms, and that late procyclic forms are invariably SoMo-negative. In addition, we show that, apart from GPEET, other markers are differentially expressed in these two life-cycle stages, both in culture and in tsetse flies, indicating that they have different biological properties and should be considered distinct stages of the life cycle. Differentially expressed genes include two closely related adenylate cyclases, both hexokinases and calflagins. These findings link the phenomenon of SoMo in vitro to the parasite forms found during the first 4-7 days of a midgut infection. We postulate that ordered group movement on plates reflects the migration of parasites from the midgut lumen into the ectoperitrophic space within the tsetse fly. Moreover, the process can be uncoupled from colonisation of the salivary glands. Although they are the major surface proteins of procyclic forms, EP and GPEET are not essential for SoMo, nor, as shown previously, are they required for near normal colonisation of the fly midgut.

No MeSH data available.


Related in: MedlinePlus