Changes in Envelope Structure and Cell–Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium <i>Trichormus variabilis</i> ATCC 29413
Planktonic freshwater filamentous cyanobacterium <i>Trichormus variabilis</i> ATCC 29413 (previously known as <i>Anabaena variabilis</i>) can differentiate heterocysts and akinetes to survive under different stress conditions. Whilst heterocysts enable diazotrophic growth, ak...
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MDPI AG
2022-03-01
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| author | Ritu Garg Manja Luckner Jürgen Berger Katharina Hipp Gerhard Wanner Karl Forchhammer Iris Maldener |
| author_facet | Ritu Garg Manja Luckner Jürgen Berger Katharina Hipp Gerhard Wanner Karl Forchhammer Iris Maldener |
| author_sort | Ritu Garg |
| collection | DOAJ |
| description | Planktonic freshwater filamentous cyanobacterium <i>Trichormus variabilis</i> ATCC 29413 (previously known as <i>Anabaena variabilis</i>) can differentiate heterocysts and akinetes to survive under different stress conditions. Whilst heterocysts enable diazotrophic growth, akinetes are spore-like resting cells that make the survival of the species possible under adverse growth conditions. Under suitable environmental conditions, they germinate to produce new vegetative filaments. Several morphological and physiological changes occur during akinete formation and germination. Here, using scanning electron microscopy (SEM), we found that the mature akinetes had a wrinkled envelope, and the surface of the envelope smoothened as the cell size increased during germination. Thereupon, the akinete envelope ruptured to release the short emerging filament. Focused ion beam–scanning electron microscopy (FIB/SEM) tomography of immature akinetes revealed the presence of cytoplasmic granules, presumably consisting of cyanophycin or glycogen. In addition, the akinete envelope architecture of different layers, the exopolysaccharide and glycolipid layers, could be visualized. We found that this multilayered envelope helped to withstand osmotic stress and to maintain the structural integrity. Furthermore, by fluorescence recovery after photobleaching (FRAP) measurements, using the fluorescent tracer calcein, we found that intercellular communication decreased during akinete formation as compared with the vegetative cells. In contrast, freshly germinating filaments restored cell communication. |
| first_indexed | 2024-03-09T13:34:11Z |
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| id | doaj.art-53a76f30a1d14bc3a2cd0e4bfea0f5dd |
| institution | Directory Open Access Journal |
| issn | 2075-1729 |
| language | English |
| last_indexed | 2024-03-09T13:34:11Z |
| publishDate | 2022-03-01 |
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| series | Life |
| spelling | doaj.art-53a76f30a1d14bc3a2cd0e4bfea0f5dd2023-11-30T21:14:35ZengMDPI AGLife2075-17292022-03-0112342910.3390/life12030429Changes in Envelope Structure and Cell–Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium <i>Trichormus variabilis</i> ATCC 29413Ritu Garg0Manja Luckner1Jürgen Berger2Katharina Hipp3Gerhard Wanner4Karl Forchhammer5Iris Maldener6Institute of Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, 72076 Tübingen, GermanyDepartment of Biology I, Ludwig-Maximilians-University, 82152 Munich, GermanyMax-Planck Institute for Developmental Biology, Electron Microscopy, 72076 Tübingen, GermanyMax-Planck Institute for Developmental Biology, Electron Microscopy, 72076 Tübingen, GermanyDepartment of Biology I, Ludwig-Maximilians-University, 82152 Munich, GermanyInstitute of Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, 72076 Tübingen, GermanyInstitute of Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, 72076 Tübingen, GermanyPlanktonic freshwater filamentous cyanobacterium <i>Trichormus variabilis</i> ATCC 29413 (previously known as <i>Anabaena variabilis</i>) can differentiate heterocysts and akinetes to survive under different stress conditions. Whilst heterocysts enable diazotrophic growth, akinetes are spore-like resting cells that make the survival of the species possible under adverse growth conditions. Under suitable environmental conditions, they germinate to produce new vegetative filaments. Several morphological and physiological changes occur during akinete formation and germination. Here, using scanning electron microscopy (SEM), we found that the mature akinetes had a wrinkled envelope, and the surface of the envelope smoothened as the cell size increased during germination. Thereupon, the akinete envelope ruptured to release the short emerging filament. Focused ion beam–scanning electron microscopy (FIB/SEM) tomography of immature akinetes revealed the presence of cytoplasmic granules, presumably consisting of cyanophycin or glycogen. In addition, the akinete envelope architecture of different layers, the exopolysaccharide and glycolipid layers, could be visualized. We found that this multilayered envelope helped to withstand osmotic stress and to maintain the structural integrity. Furthermore, by fluorescence recovery after photobleaching (FRAP) measurements, using the fluorescent tracer calcein, we found that intercellular communication decreased during akinete formation as compared with the vegetative cells. In contrast, freshly germinating filaments restored cell communication.https://www.mdpi.com/2075-1729/12/3/429cyanobacteria<i>Trichormus variabilis</i>akinetesFIB/SEM tomographycell-cell communicationFRAP |
| spellingShingle | Ritu Garg Manja Luckner Jürgen Berger Katharina Hipp Gerhard Wanner Karl Forchhammer Iris Maldener Changes in Envelope Structure and Cell–Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium <i>Trichormus variabilis</i> ATCC 29413 Life cyanobacteria <i>Trichormus variabilis</i> akinetes FIB/SEM tomography cell-cell communication FRAP |
| title | Changes in Envelope Structure and Cell–Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium <i>Trichormus variabilis</i> ATCC 29413 |
| title_full | Changes in Envelope Structure and Cell–Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium <i>Trichormus variabilis</i> ATCC 29413 |
| title_fullStr | Changes in Envelope Structure and Cell–Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium <i>Trichormus variabilis</i> ATCC 29413 |
| title_full_unstemmed | Changes in Envelope Structure and Cell–Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium <i>Trichormus variabilis</i> ATCC 29413 |
| title_short | Changes in Envelope Structure and Cell–Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium <i>Trichormus variabilis</i> ATCC 29413 |
| title_sort | changes in envelope structure and cell cell communication during akinete differentiation and germination in filamentous cyanobacterium i trichormus variabilis i atcc 29413 |
| topic | cyanobacteria <i>Trichormus variabilis</i> akinetes FIB/SEM tomography cell-cell communication FRAP |
| url | https://www.mdpi.com/2075-1729/12/3/429 |
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