基于膨胀显微技术的甲藻染色体观察OA

Dinoflagellates are pivotal unicellular eukaryotes characterized by chromosomes that lack histones and canon-ical nucleosome architecture.Throughout the cell cycle,their DNA remains persistently condensed,posing a formidable challenge for detailed morphological observation via conventional optical microscopy.To address this limitation,this study established,for the first time,an expansion microscopy(ExM)experimental system suitable for dinoflagellate cells.By optimizing the gel formulations and anchoring time,gel formulation 3(containing monomer sodium acrylate and acrylamide at concentrations of 188 and 100 g/L,respectively)and a 2-hour anchoring time were determined to be the optimal parameters,achieving a 4.8-fold expansion of Akashiwo sanguinea cells.Expansion experiments across multiple dinoflagellate species revealed that athecate dinoflagellates exhibited a substantially superior expansion efficiency(4–5-fold)than thecate dinoflagellates(~3-fold),suggesting that the thecal plates have a certain inhibitory effect on the expansion of dinoflagellate cells.DAPI staining of expanded dinoflagellate cells allowed the clear resolution of chromo-somes under a 40×objective lens,whereas nonexpanded cells failed to yield distinguishable chromosomal morphologies.Quantitative analyses demonstrated that combining the ExM system with optical microscopy enhanced the imaging reso-lution to 40–70 nm,thereby facilitating the visualization of fine chromosomal morphologies in dinoflagellates using op-tical microscopy.Altogether,the dinoflagellate ExM system established in this study provides a convenient and econom-ical approach for observing the morphology of dinoflagellate chromosomes.When combined with techniques such as multicolor labeling and three-dimensional reconstruction,this system holds promise for supporting the dissection of complex karyotypes in dinoflagellate cells and the chromosomal mapping of specific genes.