Naegleria fowleri: Light and electron microscopy study of mitosis

González‐Robles, Arturo; Cristóbal-Ramos, Ana Ruth; González‐Lázaro, Mónica; Omaña‐Molina, Maritza; Martı́nez-Palomo, Adolfo

doi:10.1016/j.exppara.2009.03.016

Cited by 17 publications

(18 citation statements)

References 13 publications

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“…For amoeba and other protozoans, ‘mitotic–meiosis’ of polyploidy similar to total nuclear fragmentation and RNuF, were described as part of their vegetative and sexual reproduction cycles (Heath, 1980; Margulis et al, 1990; Raikov, 1994). Specifically, amoebic endomitosis was described as nuclear internal with no presence of centrosomes (Gonzalez‐Robles et al, 2009), and ‘small’ nuclei first appeared as ‘bulbs’ on a polyploid chromatin mass (Dunnebacke, 2009). These genome reductional ‘mitoses’ are essentially similar to reproductive depolyploidization of mammalian endopolyploidy.…”

Section: Resultsmentioning

confidence: 99%

Mitosis is not the only distributor of mutated cells: Non‐mitotic endopolyploid cells produce reproductive genome‐reduced cells

Walen

2010

Cell Biology International

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Giant endopolyploid nuclei (>16n) can spontaneously fragment by endomitosis (nuclear internal division) into near-diploid cells with reproductive capacity (depolyploidization), and endotetra/octopolyploidy can undergo chromosome-visible meiotic-like genome reductional divisions also to replicative subcells. These unconventional divisions are associated with production of aneuploidy, which led to the question in this study of whether endopolyploidy, in general, can contribute genetic variability to tumorigenic potential. For this purpose, non-proliferative endopolyploid cells (range: 4n-32n) in near-senescence of normal diploid cell strains were analysed for nuclear-morphogenic changes associated with the presence of diploid-sized nuclei in the cytoplasm. A one-by-one nuclear-cutoff process gave rise to reproducing genome-reduced cells. It was concluded that these unconventional cell divisions are, indeed, suspects of originating genetic variability. Details of these irregular mitoses were compared to 'mitotic-meiosis' in primitive organisms, which suggested activation of an ancestral trait in the mammalian cells.

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Section: Resultsmentioning

confidence: 99%

Mitosis is not the only distributor of mutated cells: Non‐mitotic endopolyploid cells produce reproductive genome‐reduced cells

Walen

2010

Cell Biology International

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“…For noncycling cells or organisms that do not use spindle poles to segregate centrioles, the centriole to MTOC conversion would be unnecessary or might not even exist. It will be interesting to explore this prediction in unicellular eukaryotes, such as paramecia and trypanosome, in which centrioles are transmitted through cortical inheritance or cytotaxis during cell division (Sonneborn, 1964; Beisson and Sonneborn, 1965; Ng and Frankel, 1977; Moreira-Leite et al, 2001; Feldman et al, 2007; Beisson, 2008; González-Robles et al, 2009), i.e., in these organisms, the machinery that converts centrioles to centrosomes would be absent (Moreira-Leite et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

The conversion of centrioles to centrosomes: essential coupling of duplication with segregation

Wang

Soni

Uryu

et al. 2011

Journal of Cell Biology

147

204

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“…Although these studies form the basis of most of what we know about Naegleria's cytoskeletal biology, Naegleria usually do not have any microtubules at all. The only microtubules found to date in Naegleria amoebae are found in the mitotic spindle during closed mitosis (Fulton and Dingle, 1971;Gonzalez-Robles et al, 2009;Walsh, 1984). This means that interphase Naegleria amoebae lack microtubules, leading to the assumption that the actin cytoskeleton alone performs all necessary functions for its amoebic lifestyle, particularly cell crawling and phagocytosis.…”

Section: Introductionmentioning

confidence: 99%

Arp2/3 complex-mediated actin assembly drives microtubule-independent motility and phagocytosis in the evolutionarily divergent amoebaNaegleria

Fritz‐Laylin

2020

Preprint

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Much of our current understanding of actin-driven phenotypes in eukaryotes has come from the "yeast to human" opisthokont lineage, as well as the related amoebozoa. Outside of these groups lies the genus Naegleria, which diverged from humans over a billion years ago, and includes the deadly "braineating amoeba." Unlike nearly every other known eukaryotic cell type, Naegleria amoebae are thought to lack cytoplasmic microtubules. The absence of microtubules suggests that these amoebae rapidly crawl and phagocytose bacteria using actin alone. Although this makes Naegleria a powerful system to probe actin-driven functions in the absence of microtubules, surprisingly little is known about Naegleria's actin cytoskeleton. Here, we use microscopy and genomic analysis to show that Naegleria amoebae have an extensive actin cytoskeletal repertoire, complete with nucleators and nucleation promoting factors. Naegleria use this cytoskeletal machinery to generate Arp2/3-dependent lamellar protrusions, which correlate with the capacity to migrate and phagocytose bacteria. Because human cells also use Arp2/3-dependent lamellar protrusions for motility and phagocytosis, this work supports an evolutionarily ancient origin for these actin-driven processes and establishes Naegleria as a natural model system for studying microtubule-independent cytoskeletal phenotypes.

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Naegleria fowleri: Light and electron microscopy study of mitosis

Cited by 17 publications

References 13 publications

Mitosis is not the only distributor of mutated cells: Non‐mitotic endopolyploid cells produce reproductive genome‐reduced cells

Mitosis is not the only distributor of mutated cells: Non‐mitotic endopolyploid cells produce reproductive genome‐reduced cells

The conversion of centrioles to centrosomes: essential coupling of duplication with segregation

Arp2/3 complex-mediated actin assembly drives microtubule-independent motility and phagocytosis in the evolutionarily divergent amoebaNaegleria

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