Vegetative cell enlargement of diatoms as a way to restore morphological features during long-term cultivation
Creators: name: Petrova, Darya
name: Bedoshvili, Yekaterina
name: Marchenkov, Artyom
name: Zakharova, Yulia
Publisher: name: Taylor & Francis
Year: 2025
Subjects: subject: Cell Biology
subject: Ecology
subject: FOS: Biological sciences
subject: Biological Sciences not elsewhere classified
subject: Developmental Biology
subject: Inorganic Chemistry
subject: FOS: Chemical sciences
subject: Plant Biology

description: Identification of diatom species is based on morphological analysis of the siliceous frustules covering the cell. Frustules change due to natural processes in the cell size reduction cycle and may also be subject to teratological changes when exposed to environmental factors. The abnormal structure of valves may serve as an environmental pollution indicator, but an understanding of the morphogenesis mechanisms of different types of teratological changes is required. In this work, we evaluate the range of morphological changes in a monoclonal strain of <i>Fragilaria sublanceolata-baikali</i> that occurred during long-term cultivation. Cell ultrastructure and location of nucleus and chloroplasts during valve morphogenesis and interphase were investigated. It is known that diatom species with small cells have a reduced number of organelles, closely pressed against each other. Despite the reduction of <i>F. sublanceolata-baikali</i> cells to 4.5 μm, the arrangement and size of organelles remain characteristic of a species with larger cells. For the first time, a complete change in all morphological features, including the reduction of apical fields and rimoportula, is shown. Specific deviations observed include a change of the valve shape from lanceolate to round, the changing of the central field position and displacement of areolar rows to one of the apical fields. We hypothesize that the formation of these teratologies could result from microtubule dysfunction or changes in gene expression potentially involved in valve morphogenesis. However, these dysfunctions are not related to mutagenesis and can be compensated for by Vegetative Cell Enlargement (VCE). Our results show the limits of morphological variability of the studied species and can be used to assess the effect of toxic substances in natural and experimental conditions. Teratological changes resulting from external influences on the diatom cell can lead to a complete change in species features.The formation of teratological disorders in the pennate diatom <i>Fragilaria sublanceolata-baikali</i> occurred after the development of the sternum and during the formation of the rimoportula and apical pores.The diatom phenotype recovered during long-term cultivation as a result of Vegetative Cell Enlargement. Teratological changes resulting from external influences on the diatom cell can lead to a complete change in species features. The formation of teratological disorders in the pennate diatom <i>Fragilaria sublanceolata-baikali</i> occurred after the development of the sternum and during the formation of the rimoportula and apical pores. The diatom phenotype recovered during long-term cultivation as a result of Vegetative Cell Enlargement.