The centrosome and spindle as a ribonucleoprotein complex

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Chromosome Research 19 (2011): 367-376, doi:10.1007/s10577-011-9186-7.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 is manifold, and includes legitimate concern over contamination from other cellular compartments in biochemical preparations. With a typically high background of cytoplasmic ribosomes, even microscopic images of stained intact cells could be difficult to interpret. Also, evidence for RNA and DNA in centrosomes accumulated for approximately 40 years but was interspersed with contradictory studies, primarily regarding the presence of DNA (reviewed in Johnson and Rosenbaum, 1991; Marshall and Rosenbaum, 2000). Perhaps less tangible but still a likely cause for lingering controversy is that the presence of nucleic acids in the spindle or centrosomes will require us to look differently at these structures from a functional, and more to the point, evolutionary standpoint.This work was supported by grants from the NIH (GM088503) and NSF (MCB0843092) to MCA

Mikroskopische Untersuchungen einiger Lebensvorgänge des Blutes

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The Nucleolinus: A disappearing, forgotten and (maybe) misnamed organelle

It is common knowledge that many of the cell components we study today were discovered more than a century ago. Some have been renamed due to a newer understanding of their physiology or composition, and in some cases the old terminology is abandoned. However, it is unusual to find a structure that has not been renamed but simply forgotten. This appears to be the case for the nucleolinus, discovered at least 150 years ago and studied by Agassiz, Haekel, Montgomery and others until it virtually dropped from the literature in the early 1970s. The nucleolinus was thought to have a role in cell division, but with little knowledge of its composition and no molecular markers (until recently) available for its study, we do not know if the nucleolinus is a ubiquitous structure or an antiquated descriptor. This brief article relates most of what we know about the nucleolinus and where to find more information. Our growing knowledge concerning the role of the closely allied nucleolus in cell cycle regulation suggests that renewed study of the nucleolinus will yield important information about the biogenesis and evolution of the cell division apparatus