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.
Highlights
Our results demonstrate that Low-voltage scanning electron microscopy (LV–SEM) without osmium fixation and conductive coating allows for the identification of extrachromosomal and chromosome-associated nuclear bodies in the oocyte nuclear content preparations
Based on the results obtained we argue that in spite of similar molecular compositions by surface ultrastructure the oocyte nuclear bodies may differ significantly, similar surface topological characteristics can be exhibited by structures with different molecular composition
Previous high-resolution SEM images of loops with specific morphology on avian and amphibian lampbrush chromosomes were obtained after gold or palladium coating and osmium fixation[29,33]
Summary
Low-voltage scanning electron microscopy (LV–SEM) is one of the techniques for analyzing surface topology of various biological samples with high resolution. Compared to conventional SEM, LV–SEM with the secondary electron detection allows for analysis of the surface topography of uncoated, non-osmicated biological samples. In this work we have aimed to visualize with high resolution the surface of microsurgically isolated nuclear bodies and giant lampbrush chromosomes from avian and amphibian oocytes. Our results demonstrate that LV–SEM without osmium fixation and conductive coating allows for the identification of extrachromosomal and chromosome-associated nuclear bodies in the oocyte nuclear content preparations. We have adapted standard immunogold labelling technique with subsequent secondary electron detection of gold nanoparticles to reveal superficial distribution of certain nuclear antigens namely coilin, small nuclear RNAs (snRNA) and double-stranded DNA (dsDNA) on the oocyte nuclear structures. We discuss how the surface morphology may reflect functional status of a nuclear body
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
