Publicação
Chloroplasts across kingdoms: movement in siphonous green algae and functional retention in photosynthetic sacoglossan sea slugs
| Resumo: | This dissertation investigates the mechanisms and functional significance of chloroplast movement in siphonous green algae, with Acetabularia acetabulum and Bryopsis sp. as the study organisms. This study used a quantitative RGB based analysis as a proxy for light-induced chloroplast motility in A. acetabulum, demonstrating that these movements are rapid, dynamic, and dependent on cytoskeletal integrity, particularly actin filaments. This finding is supported by complementary fluorescence-based photophysiological assays, and experiments involving pharmacological disruption of cytoskeletal filaments, which together demonstrate that chloroplast movements function as an adaptive response to environmental stressors such as high light and mechanical injury. Interestingly, chloroplast streaming was observed not only in the injured strand but also in adjacent, uninjured strands, indicating a systemic physiological response, possibly implicating intracellular signalling. Such systemic responses suggest a possible defence mechanism against sea slug herbivory, as they were also triggered by grazing activity of Elysia timida and E. crispata. These sacoglossan sea slugs have the remarkable capacity to acquire and maintain functional intracellular algal chloroplasts from the algae they feed upon - kleptoplasty. These chloroplasts, now termed kleptoplasts, can remain photosynthetically active within the animal for extended periods, contributing to the host’s nutrition. To investigate the precise mechanisms underlying this contribution, this study employs dual isotopic labelling experiments (EA-IRMS) to trace the metabolic incorporation of isotopic carbon and nitrogen. The results demonstrate clear, light-dependent assimilation of 13C and 15N over a 12-hour incubation period, with pronounced differences in efficiency between host-alga pairings, highlighting distinct metabolic contributions from both animal-derived and kleptoplast-derived pathways. |
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| Autores principais: | Lopes, Pedro Francisco Valente |
| Assunto: | Chloroplast movement Siphonous green algae Acetabularia acetabulum Bryopsis sp. Elysia timida Elysia crispata Kleptoplasty Wound response Live microscopy |
| Ano: | 2026 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | This dissertation investigates the mechanisms and functional significance of chloroplast movement in siphonous green algae, with Acetabularia acetabulum and Bryopsis sp. as the study organisms. This study used a quantitative RGB based analysis as a proxy for light-induced chloroplast motility in A. acetabulum, demonstrating that these movements are rapid, dynamic, and dependent on cytoskeletal integrity, particularly actin filaments. This finding is supported by complementary fluorescence-based photophysiological assays, and experiments involving pharmacological disruption of cytoskeletal filaments, which together demonstrate that chloroplast movements function as an adaptive response to environmental stressors such as high light and mechanical injury. Interestingly, chloroplast streaming was observed not only in the injured strand but also in adjacent, uninjured strands, indicating a systemic physiological response, possibly implicating intracellular signalling. Such systemic responses suggest a possible defence mechanism against sea slug herbivory, as they were also triggered by grazing activity of Elysia timida and E. crispata. These sacoglossan sea slugs have the remarkable capacity to acquire and maintain functional intracellular algal chloroplasts from the algae they feed upon - kleptoplasty. These chloroplasts, now termed kleptoplasts, can remain photosynthetically active within the animal for extended periods, contributing to the host’s nutrition. To investigate the precise mechanisms underlying this contribution, this study employs dual isotopic labelling experiments (EA-IRMS) to trace the metabolic incorporation of isotopic carbon and nitrogen. The results demonstrate clear, light-dependent assimilation of 13C and 15N over a 12-hour incubation period, with pronounced differences in efficiency between host-alga pairings, highlighting distinct metabolic contributions from both animal-derived and kleptoplast-derived pathways. |
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