Visualization of the funis of Giardia lamblia by high-resolution field emission scanning electron microscopy—new insights

Benchimol, Marlene; Piva, Bruno; Campanati, Loraine; Souza, Wanderley de

doi:10.1016/j.jsb.2004.01.017

Cited by 42 publications

(36 citation statements)

References 21 publications

(36 reference statements)

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“…The lack of other cytoskeletal elements in the caudal region of the cell adds additional support for this hypothesis. As discussed earlier, the complex cytoskeleton in the anterior portion of the cell would increase the rigidity, preventing flexion, but only the flexible funis exists in the caudal region (25). The role of the caudal flagella in the rapid swimming of Giardia trophozoites has not been previously observed, despite nearly 250 years of study.…”

Section: Resultsmentioning

confidence: 97%

“…Although the caudal region's role in free swimming was previously unknown, researchers have observed, through digestion studies, that the caudal flagella could induce bending in the caudal region (24,25). This flexion was thought to be involved in active detachment of trophozoites from attached surfaces and serve as a rudder to induce rotation (18,19,24).…”

Section: Resultsmentioning

confidence: 99%

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High-speed microscopic imaging of flagella motility and swimming in Giardia lamblia trophozoites

Lenaghan

Davis

Henson

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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We report, in this paper, several findings about the swimming and attachment mechanisms of Giardia lamblia trophozoites. These data were collected using a combination of a high-contrast CytoViva imaging system and a particle image velocimetry camera, which can capture images at speeds greater than 800 frames/s. Using this system, we discovered that, during rapid swimming of Giardia trophozoites, undulations of the caudal region contributed to forward propulsion combined with the beating of the flagella pairs. It was also discovered, in contrast to previous studies with 10 times slower image sampling technique, that the anterior and posterolateral flagella beat with a clearly defined power stroke and not symmetrical undulations. During the transition from free swimming to attachment, trophozoites modified their swimming behavior from a rapid rotating motion to a more stable planar swimming. While using this planar swimming motion, the trophozoites used the flagella for propulsion and directional control. In addition to examination of the posterolateral and anterior flagella, a model to describe the motion of the ventral flagella was derived, indicating that the ventral flagella beat in an expanding sine wave. In addition, the structure of the ventrocaudal groove creates boundary conditions that determine the form of beating of the ventral flagella. The results from this study indicate that Giardia is able to simultaneously generate both ciliary beating and typical eukaryotic flagellar beating using different pairs of flagella.cell motility | cytoskeleton | swimming microorganism | ciliary and flagellar motion | bio-robotics

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

High-speed microscopic imaging of flagella motility and swimming in Giardia lamblia trophozoites

Lenaghan

Davis

Henson

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…The ER is referred to as a TVN because portions of the complex branching network appear vesicular when seen in cross section while in longitudinal section they appear tubular or linear. No other cellular compartment has such a distinctive appearance (5).…”

Section: Resultsmentioning

confidence: 99%

“…During live cell imaging, the initial Fluosphere signal was observed near the site where flagella exit the cell in the region caudal to the ventral disc (Fig. 2B) (5). This was followed by rapid distribution throughout the labyrinthine TVN with accumulation in the perinuclear region.…”

mentioning

confidence: 95%

“…In Giardia, no morphological equivalent of the classic mammalian-cell Golgi apparatus has been identified, and the transient secretory pathway for cyst wall synthesis is induced only under specific conditions (13,14,34). Giardia does contain two nuclei, a glycogen-rich cytoplasm, acidified peripheral vacuoles (PVs), and a labyrinthine TVN, segments of which are decorated with ribosomes, consistent with rough ER (5,21,22). Giardia also contains a multigene family of cysteine endoproteases that are orthologous to the cathepsin L and cathepsin B found in lysosomes of higher organisms and are therefore useful markers of cell compartments where protein degradation takes place (29,46; Giardia genome project [http://www .giardiadb.org]).…”

mentioning

confidence: 99%

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A Contiguous Compartment Functions as Endoplasmic Reticulum and Endosome/Lysosome in Giardia lamblia

et al. 2009

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The dynamic evolution of organelle compartmentalization in eukaryotes and how strictly compartmentalization is maintained are matters of ongoing debate. While the endoplasmic reticulum (ER) is classically envisioned as the site of protein cotranslational translocation, it has recently been proposed to have pluripotent functions. Using transfected reporter constructs, organelle-specific markers, and functional enzyme assays, we now show that in an early-diverging protozoan, Giardia lamblia, endocytosis and subsequent degradation of exogenous proteins occur in the ER or in an adjacent and communicating compartment. The Giardia endomembrane system is simple compared to those of typical eukaryotes. It lacks peroxisomes, a classical Golgi apparatus, and canonical lysosomes. Giardia orthologues of mammalian lysosomal proteases function within an ER-like tubulovesicular compartment, which itself can dynamically communicate with clathrin-containing vacuoles at the periphery of the cell to receive endocytosed proteins. These primitive characteristics support Giardia's proposed early branching and could serve as a model to study the compartmentalization of endocytic and lysosomal functions into organelles distinct from the ER. This system also may have functional similarity to the retrograde transport of toxins and major histocompatibility complex class I function in the ER of mammals.

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Localization of EB1, IFT polypeptides, and kinesin‐2 in Chlamydomonas flagellar axonemes via immunogold scanning electron microscopy

Sloboda

Howard

2007

Cell Motil. Cytoskeleton

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Intraflagellar transport (IFT) refers to the bi-directional movement of particles and associated cargo along the axonemes of eukaryotic flagella and cilia. To provide a new perspective on the morphology of IFT particles, their association with the axoneme, and their composition, we have used immunogold localization coupled to detection via scanning electron microscopy. Here we co-localize in the Chlamydomonas flagellar axoneme polypeptides labeled with specific antibodies. Chlamydomonas EB1 localizes to the distal tip of the axoneme, as expected from previous immunofluorescent data (Pedersen et al. Curr Biol2003;13(22):1969-1974), thus demonstrating the utility of this approach. Using antibodies to IFT-related polypeptides, particles can be identified associated with the axoneme that fall into one of two classes: The first class is composed of IFT particles labeled with polyclonal antibodies to kinesin-2 and monoclonal antibodies to either IFT139 (an IFT complex A polypeptide) or IFT172 (a complex B polypeptide). The second class is comprised of particles that label with antibodies to IFT139 alone; thus, discrete particles are present associated with the axoneme that are composed only of complex A polypeptides. When IFT particles were purified by sucrose gradient ultracentrifugation, they appeared as more or less spherical aggregates of varying dimensions labeled with antibodies to IFT139 and to the motor protein kinesin-2. By contrast, isolated IFT particles that were labeled with IFT172 antibodies were not labeled with kinesin-2 antibodies. The data are discussed in terms of the total polypeptide composition of an IFT particle and the interaction of the particles with the motors that power IFT.

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Visualization of the funis of Giardia lamblia by high-resolution field emission scanning electron microscopy—new insights

Cited by 42 publications

References 21 publications

High-speed microscopic imaging of flagella motility and swimming in Giardia lamblia trophozoites

High-speed microscopic imaging of flagella motility and swimming in Giardia lamblia trophozoites

A Contiguous Compartment Functions as Endoplasmic Reticulum and Endosome/Lysosome in Giardia lamblia

Localization of EB1, IFT polypeptides, and kinesin‐2 in Chlamydomonas flagellar axonemes via immunogold scanning electron microscopy

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