Grazing protozoa and magnetosome dissolution in magnetotactic bacteria

Martins, Juliana L.; Silveira, Timotheo Souza; Abreu, Fernanda; Silva, Karen T.; Silva‐Neto, Inácio Domingos da; Lins, Ulysses

doi:10.1111/j.1462-2920.2007.01389.x

Cited by 28 publications

(29 citation statements)

References 26 publications

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“…However, particles within host cytoplasm are slightly larger and appear more diffuse than those within intact bacteria. Similarly, ciliates having engulfed magnetotactic bacteria accumulated enlarged magnetosomes in their cytoplasm (Martins et al, 2007), and the size increase was interpreted as showing magnetosome dissolution. Occasionally, host gills contain such dense concentrations of particles that they appear black; such gills stained intensely with prussian blue and were therefore iron-rich.…”

Section: Discussionmentioning

confidence: 99%

Magnetosome-containing bacteria living as symbionts of bivalves

et al. 2014

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Bacteria containing magnetosomes (protein-bound nanoparticles of magnetite or greigite) are common to many sedimentary habitats, but have never been found before to live within another organism. Here, we show that octahedral inclusions in the extracellular symbionts of the marine bivalve Thyasira cf. gouldi contain iron, can exhibit magnetic contrast and are most likely magnetosomes. Based on 16S rRNA sequence analysis, T. cf. gouldi symbionts group with symbiotic and free-living sulfur-oxidizing, chemolithoautotrophic gammaproteobacteria, including the symbionts of other thyasirids. T. cf. gouldi symbionts occur both among the microvilli of gill epithelial cells and in sediments surrounding the bivalves, and are therefore facultative. We propose that free-living T. cf. gouldi symbionts use magnetotaxis as a means of locating the oxic-anoxic interface, an optimal microhabitat for chemolithoautotrophy. T. cf. gouldi could acquire their symbionts from near-burrow sediments (where oxic-anoxic interfaces likely develop due to the host's bioirrigating behavior) using their superextensile feet, which could transfer symbionts to gill surfaces upon retraction into the mantle cavity. Once associated with their host, however, symbionts need not maintain structures for magnetotaxis as the host makes oxygen and reduced sulfur available via bioirrigation and sulfur-mining behaviors. Indeed, we show that within the host, symbionts lose the integrity of their magnetosome chain (and possibly their flagellum). Symbionts are eventually endocytosed and digested in host epithelial cells, and magnetosomes accumulate in host cytoplasm. Both host and symbiont behaviors appear important to symbiosis establishment in thyasirids.

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Section: Discussionmentioning

confidence: 99%

Magnetosome-containing bacteria living as symbionts of bivalves

et al. 2014

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“…M. multicellularis started to engage in ping-pong movements but did not change their magnetic polarity. Therefore, this ping-pong movement could be an alternative escape mechanism for rapid egress from a potentially toxic zone using the geomagnetic field Martins et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Deciphering unusual uncultured magnetotactic multicellular prokaryotes through genomics

et al. 2013

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Candidatus Magnetoglobus multicellularis (Ca. M. multicellularis) is a member of a group of uncultured magnetotactic prokaryotes that possesses a unique multicellular morphology. To better understand this organism's physiology, we used a genomic approach through pyrosequencing. Genomic data analysis corroborates previous structural studies and reveals the proteins that are likely involved in multicellular morphogenesis of this microorganism. Interestingly, some detected protein sequences that might be involved in cell adhesion are homologues to phylogenetically unrelated filamentous multicellular bacteria proteins, suggesting their contribution in the early development of multicellular organization in Bacteria. Genes related to the behavior of Ca. M. multicellularis (chemo-, photo-and magnetotaxis) and its metabolic capabilities were analyzed. On the basis of the genomic-physiologic information, enrichment media were tested. One medium supported chemoorganoheterotrophic growth of Ca. M. multicellularis and allowed the microorganisms to maintain their multicellular morphology and cell cycle, confirming for the first time that the entire life cycle of the MMP occurs in a multicellular form. Because Ca. M. multicellularis has a unique multicellular life style, its cultivation is an important achievement for further studies regarding the multicellular evolution in prokaryotes.

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“…Instead, it seems more likely that this organism biomineralizes and arranges endogenous magnetite crystals in a highly controlled fashion within the cell, where intracellular structural filaments play a significant role in the synthesis of the magnetosome chain, as has been shown for magnetotactic prokaryotes (164,165). Moreover, some magnetotactic protists, including dinoflagellates, biflagellates, and ciliates, contain magnetosomes that are not well organized in the cell and thus probably ingest MTB and contain the bacterial magnetosomes for an undetermined amount of time (162,163,166).…”

Section: Magnetotactic Eukaryotesmentioning

confidence: 99%

Ecology, Diversity, and Evolution of Magnetotactic Bacteria

Lefèvre

Bazylinski

2013

Microbiol Mol Biol Rev

368

388

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SUMMARY Magnetotactic bacteria (MTB) are widespread, motile, diverse prokaryotes that biomineralize a unique organelle called the magnetosome. Magnetosomes consist of a nano-sized crystal of a magnetic iron mineral that is enveloped by a lipid bilayer membrane. In cells of almost all MTB, magnetosomes are organized as a well-ordered chain. The magnetosome chain causes the cell to behave like a motile, miniature compass needle where the cell aligns and swims parallel to magnetic field lines. MTB are found in almost all types of aquatic environments, where they can account for an important part of the bacterial biomass. The genes responsible for magnetosome biomineralization are organized as clusters in the genomes of MTB, in some as a magnetosome genomic island. The functions of a number of magnetosome genes and their associated proteins in magnetosome synthesis and construction of the magnetosome chain have now been elucidated. The origin of magnetotaxis appears to be monophyletic; that is, it developed in a common ancestor to all MTB, although horizontal gene transfer of magnetosome genes also appears to play a role in their distribution. The purpose of this review, based on recent progress in this field, is focused on the diversity and the ecology of the MTB and also the evolution and transfer of the molecular determinants involved in magnetosome formation.

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Grazing protozoa and magnetosome dissolution in magnetotactic bacteria

Cited by 28 publications

References 26 publications

Magnetosome-containing bacteria living as symbionts of bivalves

Magnetosome-containing bacteria living as symbionts of bivalves

Deciphering unusual uncultured magnetotactic multicellular prokaryotes through genomics

Ecology, Diversity, and Evolution of Magnetotactic Bacteria

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