Dinochromosome Heterotermini with Telosomal Anchorages

Area of Science:

• Cell Biology
• Genetics
• Molecular Biology

Background:

• Dinoflagellate chromosomes (BfCs) have large genomes but lack typical nucleosomal protection.
• BfCs interact with extranuclear microtubules at the intact nuclear envelope (NE) throughout the cell cycle.

Purpose of the Study:

• Investigate the structure and function of dinoflagellate chromosome ends.
• Determine the role of histones and nucleosomes in BfC organization and NE anchorage.

Main Methods:

• Utilized ultrastructural studies, polarized light and fluorescence microscopy.
• Employed micrococcal nuclease-resistant profiles (MNRPs) and 2D gel electrophoresis.
• Conducted histone H3K9me3 inhibition and sirtinol treatment experiments.

Main Results:

• NE-associated chromosome ends were observed to persist post-mitosis.
• Histone H3K9me3 inhibition caused S-G2 cell cycle delay.
• Telomeric nucleosomes (TNs) were identified as the primary histone structures, enriched at the NE.

Conclusions:

• Telomeric repeats form the major octameric MNRPs responsible for chromosomal anchorage at the NE.
• Telomeric nucleosomes play a key role in dinoflagellate chromosome organization and nuclear envelope interaction.