title: Plant cell nucleolus as a hot spot for iron.
abstract: Many central metabolic processes require iron as a cofactor and take place in specific subcellular compartments such as the mitochondrion or the chloroplast. Proper iron allocation in the different organelles is thus critical to maintain cell function and integrity. To study the dynamics of iron distribution in plant cells, we have sought to identify the different intracellular iron pools by combining three complementary imaging approaches, histochemistry, micro particle-induced x-ray emission, and synchrotron radiation micro X-ray fluorescence. Pea (Pisum sativum) embryo was used as a model in this study because of its large cell size and high iron content. Histochemical staining with ferrocyanide and diaminobenzidine (Perls/diaminobenzidine) strongly labeled a unique structure in each cell, which co-labeled with the DNA fluorescent stain DAPI, thus corresponding to the nucleus. The unexpected presence of iron in the nucleus was confirmed by elemental imaging using micro particle-induced x-ray emission. X-ray fluorescence on cryo-sectioned embryos further established that, quantitatively, the iron concentration found in the nucleus was higher than in the expected iron-rich organelles such as plastids or vacuoles. Moreover, within the nucleus, iron was particularly accumulated in a subcompartment that was identified as the nucleolus as it was shown to transiently disassemble during cell division. Taken together, our data uncover an as yet unidentified although abundant iron pool in the cell, which is located in the nuclei of healthy, actively dividing plant tissues. This result paves the way for the discovery of a novel cellular function for iron related to nucleus/nucleolus-associated processes.
authors: Laboratoire de Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Centre National de la Recherche Scientifique, UMR5004, Institut National de la Recherche Agronomique, Ecole Nationale Supérieure d'Agronomie, Université Montpellier II, F-34060 Montpellier Cedex 2.
authors: Hannetz
authors: H
authors: Roschzttardtz
authors: Louis
authors: L
authors: Grillet
authors: Marie-Pierre
authors: MP
authors: Isaure
authors: Geneviève
authors: G
authors: Conéjéro
authors: Richard
authors: R
authors: Ortega
authors: Catherine
authors: C
authors: Curie
authors: Stéphane
authors: S
authors: Mari
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D002466:Cell Nucleolus / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000378:metabolism*; D018532:Pisum sativum / Q000378:metabolism*; D012639:Seeds / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission
chemical_list: D007501:Iron