Density imaging of heterochromatin in live cells using orientation-independent-DIC microscopy

• DOI: 10.1091/mbc.e17-06-0359
• Publication Date: 2017-08-23T21:00:31Z
• Authors: Ryosuke Imai; Tadasu Nozaki; Tomomi Tani; Kazunari Kaizu; Kayo Hibino; Satoru Ide; Sachiko Tamura; Koichi Takahashi; Michael Shribak; Kazuhiro Maeshima
• Keywords: Euchromatin; Constitutive heterochromatin; Heterochromatin protein 1

In eukaryotic cells, highly condensed inactive/silenced chromatin has long been called "heterochromatin." However, recent research suggests that such regions are in fact not fully transcriptionally silent and there exists only a moderate access barrier to heterochromatin. To further investigate this issue, it is critical elucidate the physical properties of heterochromatin as its total density live cells. Here, using orientation-independent differential interference contrast (OI-DIC) microscopy, which capable mapping optical path differences, we investigated materials pericentric foci, representative model, mouse NIH3T3 We demonstrated (208 mg/ml) was 1.53-fold higher than surrounding euchromatic (136 while DNA 5.5- 7.5-fold higher. observed similar minor differences typical facultative heterochromatin, inactive human X chromosomes. This surprisingly small difference may be due nonnucleosomal (proteins/RNAs) (∼120 dominant both regions. Monte Carlo simulation suggested contribute creating allowing minimal protein functional Our OI-DIC imaging offers new insight into cellular environments.