Rediscovery of the nucleolinus, a dynamic RNA-rich organelle associated with the nucleolus, spindle, and centrosomes
Alliegro, Mary Anne
Henry, Jonathan J.
Alliegro, Mark C.
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The nucleolinus is an RNA-rich compartment, closely apposed to or embedded within the nucleolus. Discovered over 150 years ago, fewer than two dozen articles have been published on the nucleolinus, probably because complex histochemical stains are required for its visualization in the great majority of cells. The nucleolinus has been reported in invertebrate oocytes, mammalian and amphibian epithelial cells, neurons, and several transformed cell lines. A prominent nucleolinus, clearly visible with transmitted light microscopes at 10x magnification, is present in each oocyte of the surf clam, Spisula solidissima. We observed a consistent relationship between the nucleolinus and the developing meiotic apparatus following Spisula oocyte activation. Through sonication and sucrose gradient fractionation of purified oocyte nuclei, we isolated nucleolini, extracted their RNA, and prepared an in situ riboprobe (NLi-1) that is associated specifically with the nucleolinus, confirming its unique composition. Other in situ observations revealed a NLi-1 and nucleolinar association with the developing spindle and centrosomes. Laser microsurgery that targeted the nucleolinus resulted in failed meiotic cell division in parthenogenetically activated oocytes and failed mitosis in fertilized oocytes. Although the nucleolinus may be a forgotten organelle, its demonstrated role in spindle formation suggests it deserves renewed attention.
Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 107 (2010): 13718-13723, doi:10.1073/pnas.1008469107.
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Composition and dynamics of the nucleolinus, a link between the nucleolus and cell division apparatus in surf clam (Spisula) oocytes Alliegro, Mark C.; Hartson, Steven; Alliegro, Mary Anne (2011-12-26)The nucleolinus is a little-known cellular structure, discovered over 150 years ago (1) and thought by some investigators in the late 19th to mid-20th century to function in the formation of the centrosomes or spindle. ...
Alliegro, Mark C. (2011-01-03)The presence of nucleic acids in centrosomes and the spindle have been proposed, observed, and reported since the 1950s. Why did the subject remain, perhaps even until today, such a controversial issue? The explanation ...
Chapman, Michael; Alliegro, Mark C. (University of Chicago Press, 2012-12)The problem of eukaryogenesis—the evolutionary mechanism whereby eukaryotic cells evolved from prokaryotes—remains one of the great unsolved mysteries of cell biology, possibly due to the reductionist tendency of most ...