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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

Differential expression of early and late procyclic form markers in tsetse flies.A. GPEET and calflagin are co-expressed by early procyclic forms 3 days post infection (DPI), but neither is detectable in late procyclic forms 12 DPI. Trypanosomes were isolated from tsetse fly midguts, fixed with formaldehyde and glutaraldehyde and permeabilised with Triton-×100. Immunofluorescence was performed with anti-GPEET and anti-calflagin antisera. Scale bar: 10 µm. B. Quantitative RT-PCR was performed with RNA isolated from infected tsetse flies 3 and 12 days post infection. Gene designations are the same as for Figure 6. RQ: relative quantification. α-tubulin was used to normalise mRNA levels. Error bars are ΔCt standard errors.
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ppat-1004493-g007: Differential expression of early and late procyclic form markers in tsetse flies.A. GPEET and calflagin are co-expressed by early procyclic forms 3 days post infection (DPI), but neither is detectable in late procyclic forms 12 DPI. Trypanosomes were isolated from tsetse fly midguts, fixed with formaldehyde and glutaraldehyde and permeabilised with Triton-×100. Immunofluorescence was performed with anti-GPEET and anti-calflagin antisera. Scale bar: 10 µm. B. Quantitative RT-PCR was performed with RNA isolated from infected tsetse flies 3 and 12 days post infection. Gene designations are the same as for Figure 6. RQ: relative quantification. α-tubulin was used to normalise mRNA levels. Error bars are ΔCt standard errors.

Mentions: It has been shown previously that expression of the GPEET transcript and protein in the fly mirrors that of cells differentiating from early to late procyclic forms in culture [4], [22], [24]. To test if the new markers that we identified were similarly regulated in vivo, tsetse flies were infected and trypanosomes were harvested 3 and 12 days post infection. Figure 7A shows the co-expression of GPEET and calflagin in early procyclic forms isolated from fly midguts at day 3 and the repression of both proteins by day 12. Quantitative RT-PCR (Figure 7B) showed the same profiles that were observed in culture, with GPEET, AC330 and HK1 being more highly expressed in early procyclic forms and AC320, HK2 and PPT being more highly expressed in late procyclic forms. Taken together, these data convincingly show that early procyclic forms in culture are equivalent to the procyclic forms early in infection and late procyclic forms correspond to those in established infections.


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)

Differential expression of early and late procyclic form markers in tsetse flies.A. GPEET and calflagin are co-expressed by early procyclic forms 3 days post infection (DPI), but neither is detectable in late procyclic forms 12 DPI. Trypanosomes were isolated from tsetse fly midguts, fixed with formaldehyde and glutaraldehyde and permeabilised with Triton-×100. Immunofluorescence was performed with anti-GPEET and anti-calflagin antisera. Scale bar: 10 µm. B. Quantitative RT-PCR was performed with RNA isolated from infected tsetse flies 3 and 12 days post infection. Gene designations are the same as for Figure 6. RQ: relative quantification. α-tubulin was used to normalise mRNA levels. Error bars are ΔCt standard errors.
© Copyright Policy
Related In: Results  -  Collection

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

ppat-1004493-g007: Differential expression of early and late procyclic form markers in tsetse flies.A. GPEET and calflagin are co-expressed by early procyclic forms 3 days post infection (DPI), but neither is detectable in late procyclic forms 12 DPI. Trypanosomes were isolated from tsetse fly midguts, fixed with formaldehyde and glutaraldehyde and permeabilised with Triton-×100. Immunofluorescence was performed with anti-GPEET and anti-calflagin antisera. Scale bar: 10 µm. B. Quantitative RT-PCR was performed with RNA isolated from infected tsetse flies 3 and 12 days post infection. Gene designations are the same as for Figure 6. RQ: relative quantification. α-tubulin was used to normalise mRNA levels. Error bars are ΔCt standard errors.
Mentions: It has been shown previously that expression of the GPEET transcript and protein in the fly mirrors that of cells differentiating from early to late procyclic forms in culture [4], [22], [24]. To test if the new markers that we identified were similarly regulated in vivo, tsetse flies were infected and trypanosomes were harvested 3 and 12 days post infection. Figure 7A shows the co-expression of GPEET and calflagin in early procyclic forms isolated from fly midguts at day 3 and the repression of both proteins by day 12. Quantitative RT-PCR (Figure 7B) showed the same profiles that were observed in culture, with GPEET, AC330 and HK1 being more highly expressed in early procyclic forms and AC320, HK2 and PPT being more highly expressed in late procyclic forms. Taken together, these data convincingly show that early procyclic forms in culture are equivalent to the procyclic forms early in infection and late procyclic forms correspond to those in established infections.

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