Cytochemical studies on the mitotic spindle and the phragmoplast of plant cells

Shimamura, Tamaki; Ôta, T.

doi:10.1016/0014-4827(56)90111-2

Cited by 34 publications

(14 citation statements)

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“…Isolation of a specific basal body RNA has been reported (8), and recent electron microscopic studies have revealed specific RNase-sensitive structures in these organelles (9). In addition, the presence of RNA in kinetochores (lo), and in the pericentriolar material of spindle microtubule organizing centers (MTOCs) (1,(11)(12)(13) has been suggested.…”

Section: Introductionmentioning

confidence: 97%

Effects of RNase and RNA on in vitro aster assembly

1976

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RNase alters the in vitro assembly of spindle asters in homogenates of meiotically dividing surf clam (Spisula solidissima) oocytes. Some effects of RNase, such as reduced astral fiber length, appear nonenzymatic and probably result from RNase binding to tubulin. However, RNase-induced changes in the microtubule organizing center are also observed. Since other polycations can mimic RNase effects, the existence of an RNA component of the spindle organizing center remains uncertain. Effects of RNase and other polycations on astral fiber length can be prevented and reversed by the RNase inhibitor, polyguanylic acid. Polyguanylic acid can also augment astral fiber length in the absence of added RNase or other polycations. Augmentation by polyguanylic acid is favored by high ionic strength, and can be duplicated by polyuridylic acid and, with less efficiency, by polyadenylic acid. Polycytidylic acid and unfractionated yeast RNA, however, are unable to augment aster assembly. Polyguanylic acid can also augment the length of astral fibers on complete spindles isolated under polymerizing conditions. These results demonstrate that specific polyribonucleotides can alter spindle assembly in vitro. The presence of an inhibitor of microtubule assembly in Spisula oocytes, which can be inactivated by specific RNAs, is suggested.

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Section: Introductionmentioning

confidence: 97%

Effects of RNase and RNA on in vitro aster assembly

1976

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“…The question of whether centrosomes or centrioles contain nucleic acids has remained unresolved since biochemical studies of the mitotic apparatus in the 1950s revealed ''pentosenucleic acid'' in the polar regions (4)(5)(6)(7)(8). The consensus, expressed in the most recent review on the subject, concludes that evidence for DNA in centrosomes is lacking and that significant evidence exists to the contrary (9).…”

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confidence: 99%

Centrosome-associated RNA in surf clam oocytes

Alliegro

Alliegro²,

Palazzo³

2006

Proc. Natl. Acad. Sci. U.S.A.

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Centrosomes are the major microtubule-organizing center in animal cells. They are composed of a pair of [9(3) ؉ 0] centrioles surrounded by a relatively ill-defined pericentriolar matrix, provide the ciliary centriole-kinetosome (basal body) progenitor, and organize the assembly of microtubules into the mitotic spindle during cell division. Despite >100 years of microscopic observation and their obvious significance, our understanding of centrosome composition, dynamic organization, and mechanism of action is limited when compared with that of other cellular organelles. Centrosomes duplicate only once per cell cycle to ensure development of a normal bipolar spindle. The initial event in centrosome duplication is centriole replication, which is generative, semiconservative, and independent of the nucleus. Such observations led to the proposal that centrosomes contain their own complement of nucleic acids, possibly representative of an organellar genome comparable with those described for mitochondria and chloroplasts. The consensus in the field is that centrosomes lack DNA but may contain RNA. We isolated centrosomes from oocytes of the surf clam, Spisula solidissima, and purified from them a unique set of RNAs. We show here by biochemical means and subcellular in situ hybridization that the first transcript we analyzed is intimately associated with centrosomes. Sequence analysis reveals that this centrosome-associated RNA encodes a conserved RNA-directed polymerase domain. The hypothesis that centrosomes contain an intrinsic complement of specific RNAs suggests new opportunities to address the century-old problem of centrosome function, heredity, and evolution.centriole ͉ centrosomal RNA ͉ microtubule-organizing center T he process of centrosome duplication is tightly regulated and under the control of both cytoplasmic and intrinsic factors (1, 2) to ensure that a normal bipolar spindle is formed during mitosis and that the genome is divided equally between daughter cells. The first observable event in centrosome duplication is centriole replication. Like mitochondria and chloroplasts, centriole replication in embryos is independent of the nucleus, but unlike the former two classes of organelles, centrioles replicate not by fission but in a semiconservative, generative manner. These and other observations have led some investigators to propose that the centrosome (or more specifically, the centriole) is of endosymbiotic evolutionary origin and, like mitochondria and chloroplasts, may contain its own genome (3).The question of whether centrosomes or centrioles contain nucleic acids has remained unresolved since biochemical studies of the mitotic apparatus in the 1950s revealed ''pentosenucleic acid'' in the polar regions (4-8). The consensus, expressed in the most recent review on the subject, concludes that evidence for DNA in centrosomes is lacking and that significant evidence exists to the contrary (9). The existence of RNA in these organelles, however, remains an open question, although much of the historica...

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“…A report by Groismann et al 22 echoed the earlier studies of Mazia 23 and others, [24][25][26][27] indicating the presence of RNA in the mitotic spindle and spindle pole. This newer study, however, had at its disposal the molecular techniques to permit identification of the specific transcripts involved.…”

Section: Point Of Viewmentioning

confidence: 68%

The implications of centrosomal RNA

Alliegro

2008

RNA Biology

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Cytochemical studies on the mitotic spindle and the phragmoplast of plant cells

Cited by 34 publications

References 6 publications

Effects of RNase and RNA on in vitro aster assembly

Effects of RNase and RNA on in vitro aster assembly

Centrosome-associated RNA in surf clam oocytes

The implications of centrosomal RNA

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