Nuclear incorporation of iron during the eukaryotic cell cycle

Abstract

Scanning X-ray fluorescence microscopy has been used to probe the distribution of S, P and Fe within cell nuclei. Nuclei, which may have originated at different phases of the cell cycle, are found to show very different levels of Fe present with a strongly inhomogeneous distribution. P and S signals, presumably from DNA and associated nucleosomes, are high and relatively uniform across all the nuclei; these agree with X-ray phase contrast projection microscopy images of the same samples. Possible reasons for the Fe incorporation are discussed.

On the epigenetic role of guanosine oxidation

“…X-ray fluorescence was used to detect iron pools in the nucleolus of pea plant cells [37]. Recently, Cloetens and colleagues described that iron within the nucleus of lymphocytes is mainly associated with the nuclear envelope rather than with the chromatin [38]. In addition, X-ray analysis on liver biopsies revealed a markedly lower iron abundance inside the nucleus as compared to other intracellular compartments [39].…”

X-ray Ptychography Imaging of Human Chromosomes After Low-dose Irradiation

“…The strength of X-ray penetration directly leads to the choice of X-ray wavelength used for high-resolution imaging of biological samples (Larabell & Nugent, 2010). Detailed information can be obtained from atomic to molecular level without any sample processing such as fixing, staining or sectioning (Robinson et al, 2016). X-ray microscopy is sensitive to matter because a photon from an X-ray source interacts with the inner shell of each atom of the specimen through direct absorption or refraction and change of phase (Howells et al, 2006).…”

“…In addition, a frozen hydrated yeast cell was resolved at a resolution of~25 nm using soft X-ray coherent diffraction imaging by Huang et al (2009). Scanning X-ray fluorescence microscopy has been used to map the signal of iron (Fe), phosphorus (P) and sulphur (S) in human nuclei, in which P and S are presumed to be associated with the DNA and protein components of the nuclei (Robinson et al, 2016). The first ever attempt to image micron-sized details of highorder structure of chromosome by Robinson et al, (2015) made use of the SACLA X-ray Free Electron Laser, where 400,000 diffraction patterns were collected.…”

Nano-imaging trace elements at organelle levels in substantia nigra overexpressing α-synuclein to model Parkinson’s disease

“…The nucleolar compartment of nigral neurons, even in non-diseased conditions, displayed clear evidence for the abundant presence of P, S, Ca, but also of Zn and Fe. The presence of Fe in the nucleoli has so far been imaged by XRF in plants 47 and mammalian cells 48 , and by other techniques in aged or diseased brains 49 , 50 . Fe levels in nucleoli of dopaminergic neurons were quantified in the present work (see Table 1 ).…”