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Immunoelectron microscopic characterization of nucleolus‐associated domains during hibernation
Author(s) -
Malatesta Manuela,
Zancanaro Carlo,
Biggiogera Marco
Publication year - 2011
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.20872
Subject(s) - nucleolus , torpor , fibrillarin , biology , cajal body , microbiology and biotechnology , nucleolin , rna polymerase i , ribosomal rna , heterochromatin , nucleus , rna splicing , rna , genetics , chromatin , gene , rna polymerase , ecology , thermoregulation
Abstract The nucleolus represents a highly dynamic nuclear compartment involved in multiple functions and able to promptly respond to variations of metabolic needs. In the hibernator dormouse, which drastically modifies its metabolic activity during the seasonal cycle, the nucleolus undergoes structural and molecular changes during the torpor bouts; in particular, it shows many nucleoplasmic invaginations containing weakly contrasted areas of unknown nature. To analyze the molecular composition of these nucleolus‐associated domains (NADs) and to understand their functional significance, the fine nucleolar composition has been investigated by means of ultrastructural immunocytochemistry in different tissues of euthermic, hibernating, and arousing hazel dormice ( Muscardinus avellanarius ): in particular, the intranucleolar location of several protein factors involved in the transcription and processing of either pre‐rRNA or pre‐mRNA has been considered. NADs proved to form during hibernation and disappear upon arousal and were found to contain m 3 ‐G‐capped snRNAs, snRNPs, hnRNPs, and the survival motor neuron protein; they were, on the contrary, devoid of the nucleolar factors tested (polymerase I, fibrillarin, nucleolin, and the ribosomal phosphoproteins P 0 , P 1 , and P 2 ). We hypothesize that NADs may represent a transient storage site for those molecules involved in the pre‐mRNA splicing, which usually transit through the nucleolus; upon arousal, this would facilitate the resumption of RNA maturation by promoting the rapid reactivation of the molecular trafficking from the nucleolus. Microsc. Res. Tech. 74:47‐53, 2011. © 2010 Wiley‐Liss, Inc.