Unusual nuclear structures in male meiocytes of wild-type rye as revealed by volume microscopy

July 25, 2023

Sergey Mursalimov (1) (2), Mami Matsumoto (2) (3), Hidetoshi Urakubo (3) (5), Elena Deineko (2), Nobuhiko Ohno (6) (7)
Annals of Botany. (25 July 2023). DOI: https://doi.org/10.1093/aob/mcad107


Meiocyte column, male meiosis, 3D imaging, volume electron microscopy, cytomixis, intercellular channel


Background and Aims: During an analysis of plant male meiocytes coming from destroyed meiocyte columns – united multicellular structures formed by male meiocytes in each anther locule – a considerable amount of information becomes unavailable. Therefore, in this study, intact meiocyte columns were studied by volume microscopy in wild-type rye for the most relevant presentation of 3D structure of rye meiocytes throughout meiosis.Methods: We used two types of volume light microscopy: confocal laser scanning microscopy and non-confocal brightfield scanning microscopy combined with alcohol and aldehyde fixation as well as serial block-face scanning electron microscopy. Key Results: Unusual structures called nuclear protuberances were detected. At certain meiotic stages, nuclei formed protuberances that crossed the cell wall through intercellular channels and extended into the cytoplasm of neighbouring cells, while all other aspects of cell structure appeared to be normal. This phenomenon of intercellular nuclear migration (INM) was detected in most meiocytes at leptotene/zygotene. No cases of micronuclei formation or appearance of binucleated meiocytes were noticed. There were instances of direct contact between two nuclei during INM. No influence of fixation or of mechanical impact on the induction of INM was detected. Conclusions: INM in rye may be a programmed process (a normal part of rye male meiosis) or a tricky artefact that cannot be avoided in any way no matter which approach to meiocyte imaging is used. In both cases, INM seems to be an obligatory phenomenon that has previously been hidden by limitations of common microscopic techniques and by two-dimensional perception of plant male meiocytes. INM cannot be ignored in any studies involving manipulations of rye anthers.

How Our Software Was Used

Image stacks were imported into Dragonfly software for subsequent analysis, segmentation and 3-D modelling.

Author Affiliation

(1) Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
(2) Institute of Postharvest and Food Sciences, Agricultural Research Organization (ARO)-Volcani Institute, Rishon LeZion, Israel
(3) Section of Electron Microscopy, Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki, Japan
(4) Department of Developmental and Regenerative Neurobiology, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
(5) Department of Biomedical Data Science, School of Medicine, Fujita Health University, Toyoake, Japan
(6) Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
(7) Division of Ultrastructural Research, National Institute for Physiological Sciences, Okazaki, Japan