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Tissue and stage-specific distribution of Wolbachia in Brugia malayi.

Fischer K, Beatty WL, Jiang D, Weil GJ, Fischer PU - PLoS Negl Trop Dis (2011)

Bottom Line: In inseminated females (8 weeks p.i.) Wolbachia were observed in the ovaries, embryos and in decreasing numbers in the lateral chords.Immunohistology and in situ hybridization show distinct tissue and stage specific distribution patterns for Wolbachia in B. malayi.Extensive multiplication of Wolbachia occurs in the lateral chords of L4 and young adults adjacent to germline cells.

View Article: PubMed Central - PubMed

Affiliation: Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.

ABSTRACT

Background: Most filarial parasite species contain Wolbachia, obligatory bacterial endosymbionts that are crucial for filarial development and reproduction. They are targets for alternative chemotherapy, but their role in the biology of filarial nematodes is not well understood. Light microscopy provides important information on morphology, localization and potential function of these bacteria. Surprisingly, immunohistology and in situ hybridization techniques have not been widely used to monitor Wolbachia distribution during the filarial life cycle.

Methods/principal findings: A monoclonal antibody directed against Wolbachia surface protein and in situ hybridization targeting Wolbachia 16S rRNA were used to monitor Wolbachia during the life cycle of B. malayi. In microfilariae and vector stage larvae only a few cells contain Wolbachia. In contrast, large numbers of Wolbachia were detected in the lateral chords of L4 larvae, but no endobacteria were detected in the genital primordium. In young adult worms (5 weeks p.i.), a massive expansion of Wolbachia was observed in the lateral chords adjacent to ovaries or testis, but no endobacteria were detected in the growth zone of the ovaries, uterus, the growth zone of the testis or the vas deferens. Confocal laser scanning and transmission electron microscopy showed that numerous Wolbachia are aligned towards the developing ovaries and single endobacteria were detected in the germline. In inseminated females (8 weeks p.i.) Wolbachia were observed in the ovaries, embryos and in decreasing numbers in the lateral chords. In young males Wolbachia were found in distinct zones of the testis and in large numbers in the lateral chords in the vicinity of testicular tissue but never in mature spermatids or spermatozoa.

Conclusions: Immunohistology and in situ hybridization show distinct tissue and stage specific distribution patterns for Wolbachia in B. malayi. Extensive multiplication of Wolbachia occurs in the lateral chords of L4 and young adults adjacent to germline cells.

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Transmission electron microscopy of young adult male B. malayi 5 weeks p.i.A Numerous Wolbachia (arrows) are observed in the lateral chords close to the testis. Single dark Wolbachia (arrow head) are found in the testis close to the membrane. Mitochondria (asterisk) are found in the periphery of the lateral chord. B Wolbachia (arrow) in the inner testis epithelium in the vicinity of a spermatid. Large amounts of membranous material (arrow heads) can be observed in the testis lumen in the vicinity of the testis epithelium. C Magnification of B showing intracellular Wolbachia (arrow). D Another sample showing Wolbachia (arrows) in the inner testis epithelium. E–G Pleomorphic Wolbachia (arrows) in vacuolized testis tissue. Membranous material (arrow head) can be seen in extracellular spaces. Ps, pseudocoelomic cavity; lc, lateral chord; sp, spermatide; mo, membranous organelle; nu, nucleus; bl, basal, lamina; te, testis. Scale bar 0.5 µm.
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pntd-0001174-g009: Transmission electron microscopy of young adult male B. malayi 5 weeks p.i.A Numerous Wolbachia (arrows) are observed in the lateral chords close to the testis. Single dark Wolbachia (arrow head) are found in the testis close to the membrane. Mitochondria (asterisk) are found in the periphery of the lateral chord. B Wolbachia (arrow) in the inner testis epithelium in the vicinity of a spermatid. Large amounts of membranous material (arrow heads) can be observed in the testis lumen in the vicinity of the testis epithelium. C Magnification of B showing intracellular Wolbachia (arrow). D Another sample showing Wolbachia (arrows) in the inner testis epithelium. E–G Pleomorphic Wolbachia (arrows) in vacuolized testis tissue. Membranous material (arrow head) can be seen in extracellular spaces. Ps, pseudocoelomic cavity; lc, lateral chord; sp, spermatide; mo, membranous organelle; nu, nucleus; bl, basal, lamina; te, testis. Scale bar 0.5 µm.

Mentions: In 5 week old male worms large clusters of large, rod-shaped or spherical Wolbachia were observed in the lateral chords in the vicinity of the testis (Fig. 9A). Small, bacillary Wolbachia forms were sometimes observed in the testis tissue. At the caudal end of the testis, close to the transition to the vas deferens, Wolbachia were observed in the inner tissue, sometimes in the vicinity of peripheral spermatids (Fig. 9B,C, D). These spermatids can be easily identified and differentiated from mature spermatozoa by their compact membranous organelles and the absence of major sperm protein complexes. Large amounts of membranous material were observed in the lumen between the spermatids and the inner testis epithelium. This material resembles degenerating Wolbachia (Fig. 9B, E–G) as they have been described previously [16]. Wolbachia were unambiguously identified in the reproductive tissue of young male worms, but not in the spermatids or spermatozoa.


Tissue and stage-specific distribution of Wolbachia in Brugia malayi.

Fischer K, Beatty WL, Jiang D, Weil GJ, Fischer PU - PLoS Negl Trop Dis (2011)

Transmission electron microscopy of young adult male B. malayi 5 weeks p.i.A Numerous Wolbachia (arrows) are observed in the lateral chords close to the testis. Single dark Wolbachia (arrow head) are found in the testis close to the membrane. Mitochondria (asterisk) are found in the periphery of the lateral chord. B Wolbachia (arrow) in the inner testis epithelium in the vicinity of a spermatid. Large amounts of membranous material (arrow heads) can be observed in the testis lumen in the vicinity of the testis epithelium. C Magnification of B showing intracellular Wolbachia (arrow). D Another sample showing Wolbachia (arrows) in the inner testis epithelium. E–G Pleomorphic Wolbachia (arrows) in vacuolized testis tissue. Membranous material (arrow head) can be seen in extracellular spaces. Ps, pseudocoelomic cavity; lc, lateral chord; sp, spermatide; mo, membranous organelle; nu, nucleus; bl, basal, lamina; te, testis. Scale bar 0.5 µm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3101188&req=5

pntd-0001174-g009: Transmission electron microscopy of young adult male B. malayi 5 weeks p.i.A Numerous Wolbachia (arrows) are observed in the lateral chords close to the testis. Single dark Wolbachia (arrow head) are found in the testis close to the membrane. Mitochondria (asterisk) are found in the periphery of the lateral chord. B Wolbachia (arrow) in the inner testis epithelium in the vicinity of a spermatid. Large amounts of membranous material (arrow heads) can be observed in the testis lumen in the vicinity of the testis epithelium. C Magnification of B showing intracellular Wolbachia (arrow). D Another sample showing Wolbachia (arrows) in the inner testis epithelium. E–G Pleomorphic Wolbachia (arrows) in vacuolized testis tissue. Membranous material (arrow head) can be seen in extracellular spaces. Ps, pseudocoelomic cavity; lc, lateral chord; sp, spermatide; mo, membranous organelle; nu, nucleus; bl, basal, lamina; te, testis. Scale bar 0.5 µm.
Mentions: In 5 week old male worms large clusters of large, rod-shaped or spherical Wolbachia were observed in the lateral chords in the vicinity of the testis (Fig. 9A). Small, bacillary Wolbachia forms were sometimes observed in the testis tissue. At the caudal end of the testis, close to the transition to the vas deferens, Wolbachia were observed in the inner tissue, sometimes in the vicinity of peripheral spermatids (Fig. 9B,C, D). These spermatids can be easily identified and differentiated from mature spermatozoa by their compact membranous organelles and the absence of major sperm protein complexes. Large amounts of membranous material were observed in the lumen between the spermatids and the inner testis epithelium. This material resembles degenerating Wolbachia (Fig. 9B, E–G) as they have been described previously [16]. Wolbachia were unambiguously identified in the reproductive tissue of young male worms, but not in the spermatids or spermatozoa.

Bottom Line: In inseminated females (8 weeks p.i.) Wolbachia were observed in the ovaries, embryos and in decreasing numbers in the lateral chords.Immunohistology and in situ hybridization show distinct tissue and stage specific distribution patterns for Wolbachia in B. malayi.Extensive multiplication of Wolbachia occurs in the lateral chords of L4 and young adults adjacent to germline cells.

View Article: PubMed Central - PubMed

Affiliation: Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.

ABSTRACT

Background: Most filarial parasite species contain Wolbachia, obligatory bacterial endosymbionts that are crucial for filarial development and reproduction. They are targets for alternative chemotherapy, but their role in the biology of filarial nematodes is not well understood. Light microscopy provides important information on morphology, localization and potential function of these bacteria. Surprisingly, immunohistology and in situ hybridization techniques have not been widely used to monitor Wolbachia distribution during the filarial life cycle.

Methods/principal findings: A monoclonal antibody directed against Wolbachia surface protein and in situ hybridization targeting Wolbachia 16S rRNA were used to monitor Wolbachia during the life cycle of B. malayi. In microfilariae and vector stage larvae only a few cells contain Wolbachia. In contrast, large numbers of Wolbachia were detected in the lateral chords of L4 larvae, but no endobacteria were detected in the genital primordium. In young adult worms (5 weeks p.i.), a massive expansion of Wolbachia was observed in the lateral chords adjacent to ovaries or testis, but no endobacteria were detected in the growth zone of the ovaries, uterus, the growth zone of the testis or the vas deferens. Confocal laser scanning and transmission electron microscopy showed that numerous Wolbachia are aligned towards the developing ovaries and single endobacteria were detected in the germline. In inseminated females (8 weeks p.i.) Wolbachia were observed in the ovaries, embryos and in decreasing numbers in the lateral chords. In young males Wolbachia were found in distinct zones of the testis and in large numbers in the lateral chords in the vicinity of testicular tissue but never in mature spermatids or spermatozoa.

Conclusions: Immunohistology and in situ hybridization show distinct tissue and stage specific distribution patterns for Wolbachia in B. malayi. Extensive multiplication of Wolbachia occurs in the lateral chords of L4 and young adults adjacent to germline cells.

Show MeSH
Related in: MedlinePlus