Publicação
Effect of simulated microgravity on the cell cycle in cultured cells of Arabidopsis thaliana
| Resumo: | Life as we know it on planet Earth always evolved in the presence of the constant gravitational force, both in magnitude and direction. This physical force is responsible for giving the weight to all masses. Altering weight changes many processes in a living being, such fluid regulation, as well as ecological processes on Earth, such rain fall. Thus, it is reasonable to say that gravity shapes life. With this study we pretended to investigate how the gravity modulates cell cycle using the in vitro cellular system of Arabidopsis thaliana cell suspension line MM2d, characterized to be undifferentiated and highly proliferative. In this system cell growth is strictly correlated with the rate of ribosome biogenesis and protein synthesis by the accurate regulation of cell cycle progression. Such coordination is essential for an optimal production of biomass as well as for the viability of daughter cells after division. We investigated the effects of simulated microgravity on cellular functions by growing MM2d cell line suspensions in a 2D clinostat, a device generating simulated microgravity, for a long-term exposure of 24 hours. In order to study this cellular system, the immobilization of cells was optimized by the use of alginate gelling agent, a crucial step for exposure of cell suspension to 2D clinorotation. Under these conditions, the cell proliferation rate showed significant alterations, accompanied by reduction of cell growth. Analysis of cell cycle by flow cytometry showed increase in the proportion of cells in S phase and a decrease in G1 phase, indicating an increase in progression rate of the cell cycle. With respect to cell growth, the rate of ribosome biogenesis was reduced under simulated microgravity, as shown by variations in the abundance of nucleolar proteins nucleolin and fibrillarin, using immunofluorescence microscopy. These results are in agreement with previous observations in root meristems that have shown a decoupling of the meristematic competence, characterized by a strict coordination between cell growth and cell proliferation. Furthermore, it was shown that undifferentiated plant cells also have the ability to respond to changes in the gravity, independently from their integration into plant tissues and organs. |
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| Autores principais: | Dias, Ana Isabel Oliveira da Silva |
| Assunto: | Simulated microgravity Arabidopsis thaliana Cell growth Cell proliferation Cultured cells Nucleolin Fibrillarin Microgravidade simulada Arabidopsis thaliana Crescimento celular Proliferação celular Culturas celulares Nucleolina Fibrilarina |
| Ano: | 2018 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Life as we know it on planet Earth always evolved in the presence of the constant gravitational force, both in magnitude and direction. This physical force is responsible for giving the weight to all masses. Altering weight changes many processes in a living being, such fluid regulation, as well as ecological processes on Earth, such rain fall. Thus, it is reasonable to say that gravity shapes life. With this study we pretended to investigate how the gravity modulates cell cycle using the in vitro cellular system of Arabidopsis thaliana cell suspension line MM2d, characterized to be undifferentiated and highly proliferative. In this system cell growth is strictly correlated with the rate of ribosome biogenesis and protein synthesis by the accurate regulation of cell cycle progression. Such coordination is essential for an optimal production of biomass as well as for the viability of daughter cells after division. We investigated the effects of simulated microgravity on cellular functions by growing MM2d cell line suspensions in a 2D clinostat, a device generating simulated microgravity, for a long-term exposure of 24 hours. In order to study this cellular system, the immobilization of cells was optimized by the use of alginate gelling agent, a crucial step for exposure of cell suspension to 2D clinorotation. Under these conditions, the cell proliferation rate showed significant alterations, accompanied by reduction of cell growth. Analysis of cell cycle by flow cytometry showed increase in the proportion of cells in S phase and a decrease in G1 phase, indicating an increase in progression rate of the cell cycle. With respect to cell growth, the rate of ribosome biogenesis was reduced under simulated microgravity, as shown by variations in the abundance of nucleolar proteins nucleolin and fibrillarin, using immunofluorescence microscopy. These results are in agreement with previous observations in root meristems that have shown a decoupling of the meristematic competence, characterized by a strict coordination between cell growth and cell proliferation. Furthermore, it was shown that undifferentiated plant cells also have the ability to respond to changes in the gravity, independently from their integration into plant tissues and organs. |
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