Low-voltage scanning electron microscopy study of lampbrush chromosomes and nuclear bodies in avian and amphibian oocytes

Abstract

Nucleus is a highly compartmentalized part of the cell where the key processes of genome functionality are realized through the formation of non-membranous nuclear domains. Physically nuclear domains appear as liquid droplets with different viscosity stably maintained throughout the interphase or during the long diplotene stage of meiosis. Since nuclear body surface represents boundary between two liquid phases, the ultrastructural surface topography of nuclear domains is of an outstanding interest. The aim of this study was to examine ultrathin surface topography of the amphibian and avian oocyte nuclear structures such as lampbrush chromosomes, nucleoli, histone-locus bodies, Cajal body-like bodies, and the interchromatin granule clusters via low-voltage scanning electron microscopy. Our results demonstrate that nuclear bodies with similar molecular composition may differ dramatically in the surface topography and vice versa, nuclear bodies that do not share common molecular components may possess similar topographical characteristics. We also have analyzed surface distribution of particular nuclear antigens (double stranded DNA, coilin and splicing snRNA) using indirect immunogold labeling with subsequent secondary electron detection of gold nanoparticles. We suggest that ultrastructural surface morphology reflects functional status of a nuclear body.

Supercoiling Theory and Model of Chromosomal Structures in Eukaryotic Cells

“…5B) as negatively supercoiled protein-free plasmid DNA 53,54 does. In other words, even though shapes of polynucleosome backbones within structures of insulated neighborhoods have frequently been observed as multiple irregular loops under microscopic examinations [55][56][57] (Fig. 5A), we predict that left-handed toroidal/right-handed plectonimic shapes of polynucleosome backbones in insulated neighborhoods (Fig.…”

Polyvinyl alcohol scaffolds and supplementation support 3D and sphere culturing of human cancer cell lines by reducing apoptosis and promoting cellular proliferation

“…To observe the long‐term growth and the morphology of cancer cell clusters in the PVF scaffold, low‐vacuum scanning electron microscopy (LVSEM) was used since it can maintain humidity within the imaging chamber (Kulikova et al., 2016). Compared to conventional 3D culture scaffolds, PVF resin has a unique configuration (Figure 3c).…”

Lampbrush chromosome studies in the post‐genomic era

“…[ 23 ] Ultrathin surface topography and surface distribution of superficial antigens in lampbrush chromomeres and lateral loops can be examined by indirect immunogold labeling with subsequent secondary electron detection of gold nanoparticles via low‐voltage scanning electron microscopy without conductive coating. [ 25 ] For illustration, dsDNA exposed along the DNP‐axis of looped‐out transcriptionally active regions with growing nascent RNP fibrils was revealed by 18‐nm gold nanoparticles.…”