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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

Deletion mutants with defects in salivary gland infection rates are SoMo-positive.A and B. MKK1 and PSSA-2 deletion mutants were cultured with or without glycerol. 4×105 cells from each culture were inoculated onto plates containing 20 mM glycerol. The scale bar is 1 cm. Four days post plating community lifts were incubated with α-EP and α-GPEET antibodies. C. 2×105 cells of the procyclin  mutant (Δproc), obtained by differentiation of bloodstream forms, were inoculated onto a 0.4% agarose plate containing 20 mM glycerol. A photograph was taken 4 days post plating.
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ppat-1004493-g008: Deletion mutants with defects in salivary gland infection rates are SoMo-positive.A and B. MKK1 and PSSA-2 deletion mutants were cultured with or without glycerol. 4×105 cells from each culture were inoculated onto plates containing 20 mM glycerol. The scale bar is 1 cm. Four days post plating community lifts were incubated with α-EP and α-GPEET antibodies. C. 2×105 cells of the procyclin mutant (Δproc), obtained by differentiation of bloodstream forms, were inoculated onto a 0.4% agarose plate containing 20 mM glycerol. A photograph was taken 4 days post plating.

Mentions: Despite the lack of SoMo by late procyclic forms, it is possible that it plays a role in migration of proventricular forms across the cardia to the tsetse salivary glands. To test this hypothesis we used a series of deletion mutants with defects in salivary gland infection. Our previous studies have implicated at least two proteins in the establishment of mature salivary gland infections, mitogen-activated kinase kinase 1 (MKK1; [25]) and the surface protein PSSA-2 [26]. Parasites lacking MKK1 were completely unable to establish salivary gland infections and parasites lacking PSSA-2 showed reductions in the prevalence and intensity of infections. A procyclin mutant, lacking all EP and GPEET genes (Δproc), also showed a defect in colonisation of the salivary glands [6]. ΔMKK1 and ΔPSSA-2 infect the midgut at normal rates and intensities [25], [26], while Δproc establishes heavy infections at about half the rate of its wild-type parent [6]. MKK1 AND PSSA-2 knockouts were plated as early and late procyclic forms; in the case of Δproc only early procyclic forms, derived directly from bloodstream forms, were tested (Figure 8). In all cases, the early procyclic forms were positive for SoMo and were also able to sense and avoid the communities of late procyclic forms on the same plate.


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)

Deletion mutants with defects in salivary gland infection rates are SoMo-positive.A and B. MKK1 and PSSA-2 deletion mutants were cultured with or without glycerol. 4×105 cells from each culture were inoculated onto plates containing 20 mM glycerol. The scale bar is 1 cm. Four days post plating community lifts were incubated with α-EP and α-GPEET antibodies. C. 2×105 cells of the procyclin  mutant (Δproc), obtained by differentiation of bloodstream forms, were inoculated onto a 0.4% agarose plate containing 20 mM glycerol. A photograph was taken 4 days post plating.
© Copyright Policy
Related In: Results  -  Collection

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

ppat-1004493-g008: Deletion mutants with defects in salivary gland infection rates are SoMo-positive.A and B. MKK1 and PSSA-2 deletion mutants were cultured with or without glycerol. 4×105 cells from each culture were inoculated onto plates containing 20 mM glycerol. The scale bar is 1 cm. Four days post plating community lifts were incubated with α-EP and α-GPEET antibodies. C. 2×105 cells of the procyclin mutant (Δproc), obtained by differentiation of bloodstream forms, were inoculated onto a 0.4% agarose plate containing 20 mM glycerol. A photograph was taken 4 days post plating.
Mentions: Despite the lack of SoMo by late procyclic forms, it is possible that it plays a role in migration of proventricular forms across the cardia to the tsetse salivary glands. To test this hypothesis we used a series of deletion mutants with defects in salivary gland infection. Our previous studies have implicated at least two proteins in the establishment of mature salivary gland infections, mitogen-activated kinase kinase 1 (MKK1; [25]) and the surface protein PSSA-2 [26]. Parasites lacking MKK1 were completely unable to establish salivary gland infections and parasites lacking PSSA-2 showed reductions in the prevalence and intensity of infections. A procyclin mutant, lacking all EP and GPEET genes (Δproc), also showed a defect in colonisation of the salivary glands [6]. ΔMKK1 and ΔPSSA-2 infect the midgut at normal rates and intensities [25], [26], while Δproc establishes heavy infections at about half the rate of its wild-type parent [6]. MKK1 AND PSSA-2 knockouts were plated as early and late procyclic forms; in the case of Δproc only early procyclic forms, derived directly from bloodstream forms, were tested (Figure 8). In all cases, the early procyclic forms were positive for SoMo and were also able to sense and avoid the communities of late procyclic forms on the same plate.

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