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PubMed1963

THE ULTRASTRUCTURE OF FLAGELLAR FIBRILS.

The tips of rat sperm tails were slightly frayed by mechanical agitation, thus exposing the fibrils, which were then studied by electron microscopy after negative staining. Only the fibrils survived this treatment. Each fibril proved to be a cylinder with a hollow core. The walls of the cylinders were made up of 10 longitudinally oriented filaments. The filaments had a markedly beaded appearance, with a repeating period of 88 A. The filament thickness (bead width) was approximately 35 to 40 A. Beads of neighboring filaments were in register with each other so that cross-linking bound the filaments together to complete the wall structure of each fibril. The center-to-center spacing from one filament to the next was 55 to 60 A. The periodicity and the diameters of the filaments make it unlikely that the filaments are related to either actin or myosin. From the way the fibrils kinked, it can be inferred that they possessed considerable mechanical strength. It is consistent with present knowledge that fibrils of the mitotic apparatus may have the same basic structure as the flagellar fibrils. Under some circumstances, pairs of fibrils separated from one another along their length, except at their extreme tips. It was apparent that there was special bridging material to be found there. In other preparations, however, the paired fibrils remained together, indicating a powerful coupling mechanism.

Actin Cytoskeleton↗

PubMed2006

Adenylate kinases 1 and 2 are part of the accessory structures in the mouse sperm flagellum.

Proper sperm function depends on adequate ATP levels. In the mammalian flagellum, ATP is generated in the midpiece by oxidative respiration and in the principal piece by glycolysis. In locations where ATP is rapidly utilized or produced, adenylate kinases (AKs) maintain a constant adenylate energy charge by interconverting stoichiometric amounts of ATP and AMP with two ADP molecules. We previously identified adenylate kinase 1 and 2 (AK1 and AK2) by mass spectrometry as part of a mouse SDS-insoluble flagellar preparation containing the accessory structures (fibrous sheath, outer dense fibers, and mitochondrial sheath). A germ cell-specific cDNA encoding AK1 was characterized and found to contain a truncated 3' UTR and a different 5' UTR compared to the somatic Ak1 mRNA; however, it encoded an identical protein. Ak1 mRNA was upregulated during late spermiogenesis, a time when the flagellum is being assembled. AK1 was first seen in condensing spermatids and was associated with the outer microtubular doublets and outer dense fibers of sperm. This localization would allow the interconversion of ATP and ADP between the fibrous sheath where ATP is produced by glycolysis and the axonemal dynein ATPases where ATP is consumed. Ak2 mRNA was expressed at relatively low levels throughout spermatogenesis, and the protein was localized to the mitochondrial sheath in the sperm midpiece. AK1 and AK2 in the flagellar accessory structures provide a mechanism to buffer the adenylate energy charge for sperm motility.

3' Untranslated Regions↗

PubMed1989

Negative transcriptional regulation in the Caulobacter flagellar hierarchy.

The Caulobacter crescentus flagellum is formed at a specific time in the cell cycle and its assembly requires the ordered expression of a large number of genes. These genes are controlled in a positive trans-acting hierarchy that reflects the order of assembly of the flagellum. Using plasmids carrying transcriptional fusions of either a neo or a lux reporter gene to the promoters of three flagellar genes representing different ranks in the hierarchy (the hook operon, a basal body gene flbN, and the flaO gene), we have measured the level of chimeric gene expression in 13 flagellar mutant backgrounds. Mutants in the hook operon or in basal body genes caused overproduction of both hook operon and basal body gene chimeric mRNAs, suggesting that negative regulation is superimposed on the positive trans-acting control for these early events in the flagellar hierarchy. Mutants in the structural genes and in genes involved in flagellar assembly had no effect on flaO expression, placing the flaO gene near the top of the hierarchy. However, flaO expression appears to be under negative control by two regulatory genes flaS and flaW. Negative control, as a response to the completion of specific steps in the assembly process, may be an important mechanism used by the cell to turn off flagellar gene expression once the gene product is no longer needed.

Bacteria↗

PubMed2006

Disulfide cross-linking indicates that FlgM-bound and free sigma28 adopt similar conformations.

The dissociable sigma subunit of bacterial RNA polymerase is required for the promoter-specific initiation of transcription. When bound to RNA polymerase, sigma makes sequence-specific promoter contacts and plays a crucial role in DNA melting. In isolation, however, sigma lacks significant promoter binding activity. In the crystal structure of the flagellar sigma factor, sigma(28), bound to the anti-sigma factor, FlgM, sigma(28) adopts a compact conformation in which the promoter binding surfaces are occluded by interdomain contacts. To test whether sigma(28) adopts this conformation in the absence of FlgM, we engineered a set of double cysteine mutants predicted to form interdomain disulfides in the conformation observed in the FlgM complex. We show that these disulfides form in both the presence and absence of FlgM. For two of the mutants, quantitative measurements of disulfide formation under equilibrium conditions suggest that the major solution conformation favors disulfide formation. The results indicate that the compact conformation of sigma(28) observed in the sigma(28)/FlgM structure is similar to the predominant conformation of free sigma(28) in solution. This finding suggests that autoinhibition of DNA binding in free sigma(28) is accomplished by steric occlusion of the promoter binding surfaces by interdomain interactions within the sigma factor as well as by a suboptimal distance between the promoter -10 and -35 element binding determinants in sigma(2) and sigma(4), respectively.

Amino Acid Substitution↗

PubMed1998

Mechanism of self-association and filament capping by flagellar HAP2.

HAP2 forms a capping structure, which binds very tightly to the distal end of flagellar filaments and still allows insertion of flagellin subunits below the cap by an unknown mechanism. Terminal regions of HAP2 from Salmonella typhimurium were found to be quickly degraded by various proteases, indicating that HAP2 also possesses disordered terminal regions like other axial proteins of bacterial flagellum. Removal of these portions by trypsin results in a fragment of 40 kDa (HP40), which lacks 42 NH2-terminal and 51 COOH-terminal residues. HAP2 in solution readily associates into a decameric structure without any significant population of intermediate oligomeric forms. The HP40 fragments, however, do not form decamers, while they can assemble into pentamers, as revealed by chemical cross-linking and analytical ultracentrifugation. Decameric HAP2 also dissociates into pentamers and smaller oligomers upon a heat induced conformational transition around 36 degreesC. While the highly mobile terminal regions are immobilized in decameric HAP2 complexes, they are still largely disordered in the pentameric state. These results demonstrate that the intersubunit interactions within the pentamers are mainly through the HP40 portions, whereas the terminal regions are responsible for association of pentamers into decameric complexes. Several observations indicate that HAP2 performs its capping function as a pentamer. We suggest that binding of the pentameric HAP2 cap to the filament is mediated by the highly flexible terminal regions. Indeed, HP40 fragments are unable to cap the end of filaments, while removal of about 30 residues from both terminal regions of HAP2 results in a highly reduced capping ability. A model is presented to explain the molecular mechanism of capping, in which conformational entropy in the disordered terminal regions moderates the otherwise too tight HAP2-filament interactions to allow insertion of flagellin subunits below the cap.

Amino Acid Sequence↗

PubMed1988

Formation of flagella during interphase in secondary spermatocytes from Xenopus laevis in vitro.

In cell culture, single motile flagella, 1 micron in length, were observed to grow from secondary spermatocytes of Xenopus laevis within 2-3 hours after telophase I, at 22 degrees C. About 90% of the secondary spermatocytes formed flagella as observed by phase-contrast microscopy. The flagella grew up to 2-6 microns in length during interphase II, which lasted about 18 hours. The presence of the "9 + 2" microtubular structure of the flagellar axonemes of secondary spermatocytes was confirmed by electron microscopy. When chromosomal condensation began (prophase II), the flagella were resorbed into the cells and, after the second meiotic division, a flagellum was formed again by each of the round spermatids. Thus, there appears to be a close relationship between the meiotic division cycle and the formation of flagella. The possible contribution of Sertoli cells to the formation of flagella in secondary spermatocytes was examined by reducing the number of Sertoli cells to less than ten per culture. Under these conditions, flagella formed in secondary spermatocytes with very high efficiency. It is very likely that secondary spermatocytes form flagella in vivo, since the secondary spermatocytes were observed to have flagella immediately after dissociation of the testes.

Animals↗

PubMed2006

Numerical analysis of DNA microarray data of Campylobacter jejuni strains correlated with survival, cytolethal distending toxin and haemolysin analyses.

Molecular epidemiological studies of the enteric pathogen Campylobacter jejuni have suggested that not all animal isolates are equally pathogenic to humans. We examined the use of numerical analysis of whole-genomotype data as a potential tool for evaluating C. jejuni virulence potential. Whole-genome microarray analysis was used to determine the gene-level complementarity of 12 Danish strains to the pathogenic, genome-sequenced strain NCTC 11168. Cytolethal distending toxin (CDT) and haemolysin activities, and survival characteristics under aerobic conditions at room temperature were also determined. Among the strains examined, 439 genes were polymorphic. Numerical analysis of these data by use of the squared Euclidean distance coefficient and Ward's clustering method clearly delineated strains into two clusters. CDT and haemolysin activities of cluster 1 strains were not statistically significantly different from cluster 2 strains. However, viability during aerobic incubation of cluster 1 strains was statistically significantly lower than corresponding estimates of cluster 2 strains. The number of missing or highly divergent genes in cluster 1 strains with respect to NCTC 11168 was also statistically significantly greater compared with those of cluster 2 strains. Sixty-seven genes present in NCTC 11168 were characteristically missing or divergent among cluster 1 strains. Of these, 53 genes were localised within 11 major gene clusters, of which eight were associated with surface structures and included flagellar, lipo-oligosaccharide, and membrane transport proteins. Our data indicate a correlation between C. jejuni genomic content, particularly in surface-coding regions, and its capacity for environmental survival, and may help explain why certain serotypes are more commonly reported in human disease.

Animals↗

PubMed2002

Do sperm cells remember?

Spontaneous alternation behavior (SAB) is the universal tendency of animals, including unicellular organisms, to alternate directional choices at consecutive left/right branchings while traversing a maze. Occurrence of SAB implies short-term memory, as a current decision is statistically dependent on previous ones. We developed a procedure to assess SAB in human spermatozoa. A total of 1302 progressively motile spermatozoa from healthy donors were observed as they entered one of two mazes, both fabricated by eximer laser ablation. The control maze was a simple T-maze (width=depth=20 microm, distance between entrance and free choice T-intersection=600 microm). The experimental maze was identical to the control maze except for a forced right-turn 600 microm before the T-intersection. We recorded individual sperm cells' left/right decisions at the T-intersections in both mazes. Of the 714 spermatozoa entering the control maze, 49.1% turned to the left (not significantly different from the chance expectation of 50.0%). Of the 588 spermatozoa entering the experimental maze, 58.6% turned left after the initial forced right turn (significant SAB; P=0.041, Wilcoxon). The statistical dependency of a directional decision on a previous one suggests a physiological 'memory' in human spermatozoa. Among the possible underlying mechanisms are refractory processes in structures responsible for flagellar beating, a postulation which deserves further scrutiny with video-monitored single-cell testing.

Humans↗

PubMed2004

Spermatid differentiation requires the assembly of a cell polarity complex downstream of junctional adhesion molecule-C.

During spermatogenesis in the mammalian testis, stem cells (spermatogonia) differentiate into spermatocytes, which subsequently undergo two consecutive meiotic divisions to give rise to haploid spermatids. These cells are initially round but progressively elongate, condense their nuclei, acquire flagellar and acrosomal structures, and shed a significant amount of their cytoplasm to form spermatozoa (the sperm cells) in a developmental cascade termed spermiogenesis. Defects in these processes will lead to a lack of mature sperm cells (azoospermia), which is a major cause of male infertility in the human population. Here we report that a cell-surface protein of the immunoglobulin superfamily, junctional adhesion molecule-C (JAM-C), is critically required for the differentiation of round spermatids into spermatozoa in mice. We found that Jam-C is essential for the polarization of round spermatids, a function that we attribute to its role in the assembly of a cell polarity complex.

Animals↗

PubMed1997

Tandem duplication of rab genes followed by sequence divergence and acquisition of distinct functions in Trypanosoma brucei.

The Ras superfamily of small G proteins governs unidirectional cellular processes by virtue of GTP hydrolysis and concomitant conformational changes, which are in turn regulated by a number of accessory factors. Members of the Rab subfamily are important for correct targeting and fusion of intra-organellar vesicles loaded with trafficking proteins and lipids. During evolution from a prototype gene, novel functions may be acquired by duplicated daughter genes; for Rab proteins, this can be tested by location, which is specifically related to the function of each Rab. We have found an example of two rab genes in Trypanosoma brucei (trab genes) that clearly arose by tandem duplication, being highly related to each other and remaining juxtaposed in the genome, whose products have dramatically different subcellular locations, indicative of discrete functions. These two trab genes, isolated on a single genomic clone, are separated by a short intervening sequence and are in a head-to-tail orientation. The nucleotide sequences of the open reading frames and intervening sequence were determined and show that the genes are paralogues, probably arising from an ancient tandem duplication. Both genes are most homologous to ypt1 and sec4 in the Saccharomyces cerevisiae genome, while phylogenetic reconstruction indicates that although they have clearly diverged, the proteins are more closely related to each other than to other Rab protein sequences available in the data base. Immunofluorescence microscopy, using antibodies raised against the recombinant Trab proteins, clearly demonstrates that the native Trab proteins have completely distinct subcellular locations in the trypanosome. Trab1p is present in a widespread reticular location similar to BiP, suggesting an endoplasmic reticulum location, while Trab7p is observed in a discrete structure adjacent to the kinetoplast. Most interestingly, the Trab7p-positive compartment also appears to divide at the same time, or just prior to, the kinetoplast, i.e. early in mitosis, suggestive of association with structures in the flagellar pocket region. An estimate of the divergence time indicates that the trab1/trab7 duplication occurred approximately 100 million years ago, and therefore, the persistence of this pair suggests an essential role in the survival of T. brucei.

Algorithms↗

PubMed2006

The flagellar-specific transcription factor, sigma28, is the Type III secretion chaperone for the flagellar-specific anti-sigma28 factor FlgM.

The sigma(28) protein is a member of the bacterial sigma(70)-family of transcription factors that directs RNA polymerase to flagellar late (class 3) promoters. The sigma(28) protein is regulated in response to flagellar assembly by the anti-sigma(28) factor FlgM. FlgM inhibits sigma(28)-dependent transcription of genes whose products are needed late in assembly until the flagellar basal motor structure, the hook-basal body (HBB), is constructed. A second function for the sigma(28) transcription factor has been discovered: sigma(28) facilitates the secretion of FlgM through the HBB, acting as the FlgM Type III secretion chaperone. Transcription-specific mutants in sigma(28) were isolated that remained competent for FlgM-facilitated secretion separating the transcription and secretion-facilitation activities of sigma (28). Conversely, we also describe the isolation of mutants in sigma(28) that are specific for FlgM-facilitated secretion. The data demonstrate that sigma(28) is the Type III secretion chaperone for its own anti-sigma factor FlgM. Thus, a novel role for a sigma(70)-family transcription factor is described.

Bacterial Proteins↗

PubMedDate not supplied

Characterization of the eyespot regions of "blind" Chlamydomonas mutants after restoration of photophobic responses.

Chlamydomonas reinhardtii exhibits photophobic and positive and negative phototactic responses that can be defined for cell populations using computerized cell tracking and motion analysis. Mutants CC-2359 and FN68 are pigment deficient mutants that are blocked in carotenoid synthesis and lack these photo responses. In particular, neither mutant exhibits flash-induced photophobic responses to visible light stimuli to which wild-type gametic cells exhibit a strong response, with several behavioral stages. Upon addition of all-trans retinal to these mutants, the photophobic responses are restored with minor quantitative differences from wild-type populations. Using both light and electron microscopy, we have compared the ultrastructural characteristics of wild-type C. reinhardtii to those of both mutants. As previously described, wild-type cells contain an eyespot consisting of 2-4 layers of pigmented granules encased within thylakoid membranes, located between the distal extremities of the flagellar root. This structure is also visible as an orange-red spot in light microscopy. The photoreceptor is thought to be concentrated in the plasma membrane above the eyespot. The mutant, CC-2359, lacks this eyespot as seen by both light and electron microscopy, even when the photophobic response has been restored. FN68-like mutants studied earlier by Morel-Laurens and Feinlieb and others contain an eyespot which can be seen only by electron microscopy. In FN-68, the eyespot generally has the same dimensions as in wt cells, differing mainly in pigment granule appearance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Distribution of epitopes of Trypanosoma cruzi amastigotes during the intracellular life cycle within mammalian cells.

In this study we have examined the distribution of epitopes defined by monoclonal antibodies raised against Trypanosoma cruzi amastigotes during the intracellular life cycle of the parasite. We have raised monoclonal antibodies towards amastigote forms and performed preliminary immunochemical characterization of their reactivities. MAB 1D9, 3G8, 2B7, 3B9, and 4B9 react with carbohydrate epitopes of the parasite major surface glycoprotein--Ssp-4 defined by MAB 2C2 [5]; MAB 4B5 reacts with a noncarbohydrate epitope in all developmental stages of the parasite, and MAB 3B2 also detects a noncarbohydrate epitope preferentially in T. cruzi flagellated forms. Vero cells infected with tissue culture-derived trypomastigotes of clone D11 (G strain) were fixed at different times during the intracellular proliferation of parasites, and processed for immuno-electron microscopy and confocal immunofluorescence with the different monoclonal antibodies. We observed that while the surface distribution of MAB 2C2 and 4B9 epitopes was uniform throughout the cycle, MAB 1D9, 3G8, and 2B7 reacted with cytoplasmic membrane-bound compartments of the amastigotes. MAB 3B9 displayed a unique surface dentate pattern in some amastigotes. MAB 4B5 recognized a curved-shaped structure at the flagellar pocket region in some intracellular amastigotes and localized to the membrane in dividing forms. In intracellular trypomastigotes, MAB 4B5 also displayed a punctate pattern near the flagellar pocket.

Animals↗

PubMed1999

Ultrastructural characterization of Anaerobiospirillum succiniciproducens and its differentiation from Campylobacter species.

The anaerobic spiral-shaped bacterium Anaerobiospirillum succiniciproducens was isolated from the blood of an AIDS patient for the first time in Europe. Electron-microscopical methods, especially negative staining, allowed rapid morphological classification and differentiation from Campylobacter species. While A. succiniciproducens revealed lophotriche flagellation all the investigated Campylobacter species showed monotriche flagellation. The cell diameter of A. succiniciproducens was at least double that of the investigated Campylobacter species. Other ultrastructural features, such as a ring-like structure underneath the flagellar area and fibrils arranged parallel along the axis, were also specific to A. succiniciproducens.

AIDS-Related Opportunistic Infections↗

PubMed2006

A bacterial flagellin, Vibrio vulnificus FlaB, has a strong mucosal adjuvant activity to induce protective immunity.

Flagellin, the structural component of flagellar filament in various locomotive bacteria, is the ligand for Toll-like receptor 5 (TLR5) of host cells. TLR stimulation by various pathogen-associated molecular patterns leads to activation of innate and subsequent adaptive immune responses. Therefore, TLR ligands are considered attractive adjuvant candidates in vaccine development. In this study, we show the highly potent mucosal adjuvant activity of a Vibrio vulnificus major flagellin (FlaB). Using an intranasal immunization mouse model, we observed that coadministration of the flagellin with tetanus toxoid (TT) induced significantly enhanced TT-specific immunoglobulin A (IgA) responses in both mucosal and systemic compartments and IgG responses in the systemic compartment. The mice immunized with TT plus FlaB were completely protected from systemic challenge with a 200x minimum lethal dose of tetanus toxin. Radiolabeled FlaB administered into the nasal cavity readily reached the cervical lymph nodes and systemic circulation. FlaB bound directly to human TLR5 expressed on cultured epithelial cells and consequently induced NF-kappaB and interleukin-8 activation. Intranasally administered FlaB colocalized with CD11c as patches in putative dendritic cells and caused an increase in the number of TLR5-expressing cells in cervical lymph nodes. These results indicate that flagellin would serve as an efficacious mucosal adjuvant inducing protective immune responses through TLR5 activation.

Adjuvants, Immunologic↗

PubMed1984

[Sperm flagella and cilia with pathologic motility and ultrastructure].

Motility of sperm flagella as well as of cilia is mechanically based on the principle of 9 + 2-tubules. It functions essentially by coordinated action between microtubules and the adenosine-triphosphatase dynein and was already present at the beginning of the evolution of the eucaryotes. Experimentally induced mutations in algae have resulted in numerous variations of the flagellar 9 + 2-structure. A mutation of this kind is also found in man, as immotile cilia syndrome (ICS) where anomalies in spermatozoa and in cilia (e.g. of the respiratory tract) are observed. Clinical manifestations of the syndrome have long been known (chronic bronchitis, bronchiectasis, sinusitis and male sterility). In addition, half of the patients exhibit situs inversus viscerum, known as Kartagener's syndrome, a subgroup of ICS. Electron microscopy was used to investigate sperm flagella with reduced motility from 9 patients (one with ICS) with primary infertility. Cilia of the respiratory tract from 7 patients (several with ICS) with chronic bronchial problems were analyzed for motility (using video techniques) and ultrastructure. Reduced motility or immotility of spermatozoa and immotile or dyskinetic cilia were always accompanied by ultrastructural anomalies. In spermatozoa, lack of dynein arms, 9 + 0-configuration and extratubuli were most frequently observed. The fibrous sheath was always asymmetrical. Structural ciliary defects resulted in non-parallel arrangements, electron dense matrix substance, extratubuli and lack of radial spokes. In one case, ciliary microtubuli were found in microvilli. In two patients, cilia as well as spermatozoa were analyzed. In the first, immotile spermatozoa without dynein arms and structurally normal cilia were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Characterization of antibodies as probes for structural and biochemical studies of tektins from ciliary and flagellar microtubules.

Rabbit antibodies raised and purified against three tektins, proteins of flagellar doublet microtubules from sea-urchin sperm (Lytechinus pictus and Strongylocentrotus purpuratus), were used to study tektin biochemistry and their structural localization. Doublet microtubules were fractionated into tektin filaments and separated by SDS-PAGE into three major tektin polypeptide bands (Mr = 47, 51 and 55 (X 10(3)), which were used to immunize rabbits. Antibodies against each tektin (anti-tektins) were affinity-purified and then characterized by two-dimensional isoelectric focusing/SDS-PAGE immunoblotting and by immunofluorescence microscopy. In two-dimensional immunoblots of 0.5% Sarkosyl-resistant fractions of flagellar microtubules, the antibody against the 55 X 10(3) Mr tektin (anti-55) stained one major polypeptide of 55 X 10(3) Mr and pI 6.9, anti-51 stained two polypeptides of 51 X 10(3) Mr and pI approximately 6.15, and anti-47 stained one major polypeptide of 47 X 10(3) Mr and pI 6.15. The anti-tektins also stained several minor neighbouring polypeptides, which may be isoelectric variants, novel tektins or unrelated proteins. Furthermore, anti-47 crossreacted with the major 55 X 10(3) Mr polypeptide. By immunofluorescence microscopy all three anti-tektins stained methanol-fixed echinoderm sperm flagella and embryonic cilia. In addition, anti-47 and anti-55 stained unfixed, demembranated axonemes. Besides staining axonemes, all anti-tektins labelled the basal body region, and anti-51 labelled the sperm head envelope. These results indicate that the tektins are a complex family of proteins that are components of axonemal microtubules and possibly other cytoplasmic and nuclear structures.

Animals↗

PubMed1991

Monoclonal antibodies to Leishmania mexicana promastigote antigens. II. Cellular localization of antigens in promastigotes and infected macrophages.

In the accompanying paper by Ilg et al., it was shown that Leishmania mexicana promastigotes covalently modify a secreted acid phosphatase and other proteins by carbohydrate epitopes characteristic for lipophosphoglycan (LPG). In this study, the reaction of the anti-LPG monoclonal antibodies (mAbs AP3 and L7.25) and of mAb L3.13, an antibody directed against an epitope present on the secreted acid phosphatase but not on LPG, with promastigotes and infected peritoneal macrophages is studied by immunofluorescence and immunoelectron microscopy. AP3 labels the surface, the flagellar pocket and intracellular structures in promastigotes, while L3.13 reacts predominantly with an antigen located in the flagellar pocket. Early after infection with promastigotes, but not amastigotes, AP3 or L7.25 transiently label epitopes at the surface of live macrophages. No L3.13-reactive material is detected at the surface of infected macrophages. In permeabilized, infected macrophages, AP3 heavily labels the surface of amastigotes and the lumen of the parasitophorous vacuole, while L3.13 reveals antigen in the flagellar pocket, intracellular vesicles of amastigotes, and components in the lumen of the parasitophorous vacuole. Possible mechanistic implications for Leishmania-macrophage interaction raised by these findings are discussed.

Animals↗