CELL DIFFERENTIATION IN <i>NAEGLERIA GRUBERI</i>

Fulton, Chandler

doi:10.1146/annurev.mi.31.100177.003121

Cited by 95 publications

(87 citation statements)

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“…Both the timing and the coordination of their accumulation and loss are highly reproducible, differing by less than 5 min in differentiations done as much as 6 months apart (30). This is presumably a reflection of the highly reproducible nature of the N. gruberi differentiation, which is illustrated by the fact that under the usual conditions 50% of the cells will have visible flagella at 68 ± 2 min after initiation (8,10,11). The temporal relationship between changes in the rate of flagellar gene transcription, the accumulation of the DS RNAs, and the appearance of flagellates is illustrated in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Transcriptional regulation of coordinate changes in flagellar mRNAs during differentiation of Naegleria gruberi amebae into flagellates.

Lee

Walsh

1988

Mol. Cell. Biol.

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The nuclear run-on technique was used to measure the rate of transcription of flagellar genes during the differentiation of Naegleria gruberi amebae into flagellates. Synthesis of mRNAs for the axonemal proteins aand l-tubulin and flagellar calmodulin, as wel as a coordinately regulated poly(A)+ RNA that codes for an unidentified protein, showed transient increases averaging 22-fold. The rate of synthesis of two poly(A)+ RNAs common to amebae and flagellates was low until the transcription of the flagellar genes began to decline, at which time synthesis of the RNAs found in amebae increased 3-to 10-fold. The observed changes in the rate of transcription can account quantitatively for the 20-fold increase in flagellar mRNA concentration during the differentiation. The data for the flageilar calmodulin gene demonstrate transcriptional regulation for a nontubulin axonemal protein. The data also demonstrate at least two programs of transcriptional regulation during the differentiation and raise the intriguing possibility that some significant fraction of the nearly 200 different proteins of the flagellar axoneme is transcriptionally regulated during the 1 h it takes N. grubeni amebae to form visible flagella.Axonemes of eucaryotic flagella are composed of nearly 200 different proteins (28). Thus, neglecting proteins associated with basal bodies and the various rootlet structures found in most cells, the formation of cilia or flagella requires the synthesis and assembly of a minimum of 200 gene products. This complexity is particularly notable because some cells can assemble flagella quite rapidly.The best-studied example of flagellum formation is the biflagellated green alga Chlamydomonas reinhardtii. Most studies of flagellum formation in C. reinhardtii have taken advantage of the fact that the cells are readily deflagellated to examine the regeneration of flagella (e.g., see references 27, 32, 33, and 39). Regeneration involves both the assembly of preexisting flagellar proteins, which can produce about 50% of the original flagellar length, and the synthesis of new protein (33). Transient increases in a number of mRNAs coding for flagellar proteins have been documented during C. reinhardi flagellar regeneration (34), but changes in only two of these RNAs have been studied at the transcriptional level. Changes in the level of mRNAs for the a and ,B subunits of tubulin were found to be due, in part, to changes in the rate of their synthesis and, in part, to changes in tubulin mRNA stability (2,19). No data are available to suggest how proteins that are exclusively flagellar are regulated (C. reinhardtii contains only one form of ,-tubulin which presumably must be used in cytoplasmic and mitotic microtubules as well as flagella) (40). It is also of interest to ask whether the regulatory mechanisms governing regeneration of flagella in a normally flagellated cell would apply to a cell forming flagella de novo.The amebo-flagellate Naegleria gruberi provides an opportunity to examine this question. In contrast to C. rei...

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Section: Resultsmentioning

confidence: 99%

“…In contrast to C. reinhardtii, N. gruberi amebae have no morphological trace of basal bodies (14), flagellar axonemes (9), or other parts of the flagellar apparatus (24,25,36), yet they can differentiate into swimming flagellates in 2 h (10,11,13). Under carefully * Corresponding author.…”

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confidence: 99%

Transcriptional regulation of coordinate changes in flagellar mRNAs during differentiation of Naegleria gruberi amebae into flagellates.

Lee

Walsh

1988

Mol. Cell. Biol.

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“…Switching between flagella-based swimming motility and actin-based gliding motility might be an ancient strategy for adapting to different environments. For instance, the excavate Naegleria gruberii can interconvert between a flagellate and an amoeba depending on whether it is placed in a liquid environment or associated with a solid substrate [64,[69][70][71][72]. In Naegleria flagellates, the two centrioles anchor microtubule roots that contribute to cell morphology in association with a rigid cortex of actomyosin.…”

Section: (A) the Amorphean Ancestormentioning

confidence: 99%

Exploring the evolutionary history of centrosomes

Azimzadeh

2014

Phil. Trans. R. Soc. B

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The centrosome is the main organizer of the microtubule cytoskeleton in animals, higher fungi and several other eukaryotic lineages. Centrosomes are usually located at the centre of cell in tight association with the nuclear envelope and duplicate at each cell cycle. Despite a great structural diversity between the different types of centrosomes, they are functionally equivalent and share at least some of their molecular components. In this paper, we explore the evolutionary origin of the different centrosomes, in an attempt to understand whether they are derived from an ancestral centrosome or evolved independently from the motile apparatus of distinct flagellated ancestors. We then discuss the evolution of centrosome structure and function within the animal lineage.

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“…It was reported that the flagellate of N. gruberi plays a crucial role in shuttling from the benthos to the water surface (Preston & King, 2003). Interestingly, the whole microtubule cytoskeleton of the flagellate, including flagella and their basal bodies, is formed de novo during the transformation from the amoeba (Fulton, 1977;Fulton & Dingle, 1971;Lee, 2010). The transformation is incredibly fast being completed within ca.…”

Section: Life Cycles Of Heteroloboseamentioning

confidence: 99%