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A cell-body groove housing the new flagellum tip suggests an adaptation of cellular morphogenesis for parasitism in the bloodstream form of Trypanosoma brucei.

Hughes L, Towers K, Starborg T, Gull K, Vaughan S - J. Cell. Sci. (2013)

Bottom Line: We suggest that the groove has a similar function to the flagella connector.The groove is a mobile junction located alongside the microtubule quartet (MtQ) and occurred within a gap in the subpellicular microtubule corset, causing significant modification of microtubules during elongation of the new flagellum.It appears likely that this novel form of morphogenetic structure has evolved to withstand the hostile immune response in the mammalian blood.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Medical Sciences, Faculty of Health and Life Science, Oxford Brookes University, Oxford OX3 0BP, UK.

ABSTRACT
Flagella are highly conserved organelles present in a wide variety of species. In Trypanosoma brucei the single flagellum is necessary for morphogenesis, cell motility and pathogenesis, and is attached along the cell body. A new flagellum is formed alongside the old during the cell division cycle. In the (insect) procyclic form, the flagella connector (FC) attaches the tip of the new flagellum to the side of the old flagellum, ensuring faithful replication of cell architecture. The FC is not present in the bloodstream form of the parasite. We show here, using new imaging techniques including serial block-face scanning electron microscopy (SBF-SEM), that the distal tip of the new flagellum in the bloodstream form is embedded within an invagination in the cell body plasma membrane, named the groove. We suggest that the groove has a similar function to the flagella connector. The groove is a mobile junction located alongside the microtubule quartet (MtQ) and occurred within a gap in the subpellicular microtubule corset, causing significant modification of microtubules during elongation of the new flagellum. It appears likely that this novel form of morphogenetic structure has evolved to withstand the hostile immune response in the mammalian blood.

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Related in: MedlinePlus

The subpellicular microtubule cytoskeleton is remodeled during new flagellum growth. (A,B) Surface renderings of segmented data and selected tomogram slices of two serial section tomograms illustrate the remodeling of subellicular microtubules that surround the groove and the close association of the old MtQ with the groove. (A) Remodeling of subpellicular microtubles anterior to the groove. The subpellicular microtubule array (green), old FAZ (blue), old MtQ (light green), new flagellum (NF) and old flagellum (OF) are shown. A punctuate electron density underlies the cytoplasmic face of the groove (orange). Asterisks mark the subpellicular microtubules that terminate within the tomogram. The triangle illustrates modification of spacing between subpellicular microtubules anterior to the groove. (Ai, Aii) z-slices from the tomogram that was used to produce the model shown in A, each slice is ∼6 nm thick. The groove is highlighted (arrowheads). (B) Remodeling of subpellicular microtubules posterior to the groove illustrating terminating subpellicular microtubules (asterisks) and the new FAZ posterior to the groove. The groove is located immediately to the right of the old MtQ. (Bi, Bii) z-slices from the tomogram that was used to produce the model shown in A; each slice is ∼6 nm thick. The FAZ associated with the new flagellum and the groove are indicated on the tomogram data. Scale bars: ∼250 nm.
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f02: The subpellicular microtubule cytoskeleton is remodeled during new flagellum growth. (A,B) Surface renderings of segmented data and selected tomogram slices of two serial section tomograms illustrate the remodeling of subellicular microtubules that surround the groove and the close association of the old MtQ with the groove. (A) Remodeling of subpellicular microtubles anterior to the groove. The subpellicular microtubule array (green), old FAZ (blue), old MtQ (light green), new flagellum (NF) and old flagellum (OF) are shown. A punctuate electron density underlies the cytoplasmic face of the groove (orange). Asterisks mark the subpellicular microtubules that terminate within the tomogram. The triangle illustrates modification of spacing between subpellicular microtubules anterior to the groove. (Ai, Aii) z-slices from the tomogram that was used to produce the model shown in A, each slice is ∼6 nm thick. The groove is highlighted (arrowheads). (B) Remodeling of subpellicular microtubules posterior to the groove illustrating terminating subpellicular microtubules (asterisks) and the new FAZ posterior to the groove. The groove is located immediately to the right of the old MtQ. (Bi, Bii) z-slices from the tomogram that was used to produce the model shown in A; each slice is ∼6 nm thick. The FAZ associated with the new flagellum and the groove are indicated on the tomogram data. Scale bars: ∼250 nm.

Mentions: The distal tip of the bloodstream form new flagellum was investigated by cellular electron tomography. Surface rendering of segmented data from serial tomograms (containing three to five adjacent serial 200-nm sections, encompassing 0.6–1 µm) illustrated the major cytoskeletal features both posterior to and surrounding the area of the groove (Fig. 2).


A cell-body groove housing the new flagellum tip suggests an adaptation of cellular morphogenesis for parasitism in the bloodstream form of Trypanosoma brucei.

Hughes L, Towers K, Starborg T, Gull K, Vaughan S - J. Cell. Sci. (2013)

The subpellicular microtubule cytoskeleton is remodeled during new flagellum growth. (A,B) Surface renderings of segmented data and selected tomogram slices of two serial section tomograms illustrate the remodeling of subellicular microtubules that surround the groove and the close association of the old MtQ with the groove. (A) Remodeling of subpellicular microtubles anterior to the groove. The subpellicular microtubule array (green), old FAZ (blue), old MtQ (light green), new flagellum (NF) and old flagellum (OF) are shown. A punctuate electron density underlies the cytoplasmic face of the groove (orange). Asterisks mark the subpellicular microtubules that terminate within the tomogram. The triangle illustrates modification of spacing between subpellicular microtubules anterior to the groove. (Ai, Aii) z-slices from the tomogram that was used to produce the model shown in A, each slice is ∼6 nm thick. The groove is highlighted (arrowheads). (B) Remodeling of subpellicular microtubules posterior to the groove illustrating terminating subpellicular microtubules (asterisks) and the new FAZ posterior to the groove. The groove is located immediately to the right of the old MtQ. (Bi, Bii) z-slices from the tomogram that was used to produce the model shown in A; each slice is ∼6 nm thick. The FAZ associated with the new flagellum and the groove are indicated on the tomogram data. Scale bars: ∼250 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3860315&req=5

f02: The subpellicular microtubule cytoskeleton is remodeled during new flagellum growth. (A,B) Surface renderings of segmented data and selected tomogram slices of two serial section tomograms illustrate the remodeling of subellicular microtubules that surround the groove and the close association of the old MtQ with the groove. (A) Remodeling of subpellicular microtubles anterior to the groove. The subpellicular microtubule array (green), old FAZ (blue), old MtQ (light green), new flagellum (NF) and old flagellum (OF) are shown. A punctuate electron density underlies the cytoplasmic face of the groove (orange). Asterisks mark the subpellicular microtubules that terminate within the tomogram. The triangle illustrates modification of spacing between subpellicular microtubules anterior to the groove. (Ai, Aii) z-slices from the tomogram that was used to produce the model shown in A, each slice is ∼6 nm thick. The groove is highlighted (arrowheads). (B) Remodeling of subpellicular microtubules posterior to the groove illustrating terminating subpellicular microtubules (asterisks) and the new FAZ posterior to the groove. The groove is located immediately to the right of the old MtQ. (Bi, Bii) z-slices from the tomogram that was used to produce the model shown in A; each slice is ∼6 nm thick. The FAZ associated with the new flagellum and the groove are indicated on the tomogram data. Scale bars: ∼250 nm.
Mentions: The distal tip of the bloodstream form new flagellum was investigated by cellular electron tomography. Surface rendering of segmented data from serial tomograms (containing three to five adjacent serial 200-nm sections, encompassing 0.6–1 µm) illustrated the major cytoskeletal features both posterior to and surrounding the area of the groove (Fig. 2).

Bottom Line: We suggest that the groove has a similar function to the flagella connector.The groove is a mobile junction located alongside the microtubule quartet (MtQ) and occurred within a gap in the subpellicular microtubule corset, causing significant modification of microtubules during elongation of the new flagellum.It appears likely that this novel form of morphogenetic structure has evolved to withstand the hostile immune response in the mammalian blood.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Medical Sciences, Faculty of Health and Life Science, Oxford Brookes University, Oxford OX3 0BP, UK.

ABSTRACT
Flagella are highly conserved organelles present in a wide variety of species. In Trypanosoma brucei the single flagellum is necessary for morphogenesis, cell motility and pathogenesis, and is attached along the cell body. A new flagellum is formed alongside the old during the cell division cycle. In the (insect) procyclic form, the flagella connector (FC) attaches the tip of the new flagellum to the side of the old flagellum, ensuring faithful replication of cell architecture. The FC is not present in the bloodstream form of the parasite. We show here, using new imaging techniques including serial block-face scanning electron microscopy (SBF-SEM), that the distal tip of the new flagellum in the bloodstream form is embedded within an invagination in the cell body plasma membrane, named the groove. We suggest that the groove has a similar function to the flagella connector. The groove is a mobile junction located alongside the microtubule quartet (MtQ) and occurred within a gap in the subpellicular microtubule corset, causing significant modification of microtubules during elongation of the new flagellum. It appears likely that this novel form of morphogenetic structure has evolved to withstand the hostile immune response in the mammalian blood.

Show MeSH
Related in: MedlinePlus