Examining the retention of functional kleptoplasts and digestive activity in sacoglossan sea slugs
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Solar-powered sea slugs (Sacoglossa: Gastropoda) have long captured the attention of laymen and scientists alike due to their remarkable ability to steal functional chloroplasts from their algal food, enslaving them to withstand long starvation periods. Recently, a wealth of data has shed insight into this remarkable relationship; however, the cellular mechanisms governing this process are still completely unknown. This study explores these mechanisms, providing insight into the chloroplast retention and delayed digestion, occurring within the slug’s digestive gland. We examine the relationships between functional chloroplast and lysosome abundances during starvation, in live material, for the long-term retaining species Elysia timida, the ambiguous long/short-term retaining Elysia viridis, and the short-term retaining Thuridilla hopei, to elucidate digestive differences that contribute to the development of functional kleptoplasty. Functional chloroplast and lysosome abundance are measured using chlorophyll a autofluorescence and the pH-dependent stain acridine orange. In each species, the number of chloroplasts and lysosomes is indirectly proportional, with the plastid density decreasing when starvation begins. We also present a new FIJI/Image J Plugin, the 3D—Accounting and Measuring Plugin, 3D-AMP, which enables the reliable analysis of large image sets.
KeywordsSacoglossa Kleptoplast Lysosomes Intracellular digestion Acridine orange FIJI Plugin
We would like to thank Claudia Müller, Jörn van Döhren, Ekin Tilic, Daria Krämer, Albert Haas, Gregor Christa, Cessa Rauch, Jan de Vries, and Sven Gould and Ulf Bickmeyer for their expertise and help in this project. We also appreciate the feedback we received from our two anonymous reviewers.
This study was funded by the Deutsche Forschungsgemeinschaft project Wa 618/17, the Alexander Koenig Gesellschaft, and a personal grant to EMJL from the University of Bonn, Germany.
EMJL and HW devised the project concept and EMJL conducted the lab work. PTR and EMJL designed 3D-AMP and PTR wrote this software. AP and TB help troubleshoot staining and all authors contributed to the analysis and manuscript.
Compliance with ethical standards
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.
- Christa, G. (2014). Functional kleptoplasty in a limapontiodean genus: phylogeny, food preferences, and photosynthesis in costasiella with a focus on C. ocellifera (Gastropoda: Sacoglossa). Journal of Molluscan Studies.Google Scholar
- Christa, G., Wescott, L., Schäberle, T. F., König, G. M., & Wägele, H. (2013a). What remains after 2 months of starvation? Analysis of sequestered algae in a photosynthetic slug, Plakobranchus ocellatus (Sacoglossa, Opisthobranchia), by barcoding. Planta, 237(2), 559–572. doi: 10.1007/s00425-012-1788-6.CrossRefPubMedGoogle Scholar
- Christa, G., Zimorski, V., Woehle, C., Tielens, A. G. M., Wägele, H., Martin, W. F., & Gould, S. B. (2013b). Plastid-bearing sea slugs fix CO2 in the light but do not require photosynthesis to survive. Proceedings. Biological sciences / The Royal Society, 281(1774), 20132493. http://www.ncbi.nlm.nih.gov/pubmed/24258718.
- Christa, G., Händeler, K., Schäberle, T. F., König, G. M., & Wägele, H. (2014b). Identification of sequestered chloroplasts in photosynthetic and non-photosynthetic sacoglossan sea slugs (Mollusca, Gastropoda). Frontiers in Zoology, 11(5).Google Scholar
- De Duve, C. (1963). The lysosome concept. In Ciba Foundation Symposium-Lysosomes (pp. 1–35). Wiley Online Library.Google Scholar
- de Vries, J., Christa, G., Gould, SB. (2014). Plastid survival in the cytosol of animal cells. Trends in Plant Science 19(6):347–50. doi: 10.1016/j.tplants.2014.03.010.
- de Vries, J., Woehle, C., Christa, G., Wägele, H., Tielens, A. G. M., Jahns, P., & Gould, S. B. (2015). Comparison of sister species identifies factors underpinning plastid compatibility in green sea slugs. Proceedings of the Royal Society of London B: Biological Sciences, 282(1802). http://rspb.royalsocietypublishing.org/content/282/1802/20142519.abstract.
- Kusuzaki, K., Matsubara, T., Satonaka, H., Matsumine, A., Nakamura, T., Sudo, A., et al. (2014). Intraoperative Photodynamic Surgery (iPDS) with acridine orange for musculoskeletal sarcomas. Cureus, 6(9).Google Scholar
- Lindholm, T., & Mork, A.-C. (1989). Symbiotic algae and plastids in planktonic ciliates. Memoranda Societatis pro Fauna et Flora Fennica, 65(1), 17–22.Google Scholar
- Moriyama, Y., Takano, T., & Ohkuma, S. (1982). Acridine orange as a fluorescent probe for lysosomal proton pump. Journal of Biochemistry, 92(4), 1333–1336. http://jb.oxfordjournals.org/content/92/4/1333.abstract.
- Schmitt, V. (2011). Behavioral adaptations in relation to long-term retention of endosymbiotic chloroplasts in the Sea Slug Elysia timida. Thalassas, 27(2), 225–238.Google Scholar
- Schmitt, V., Händeler, K., Gunkel, S., Escande, M.-L., Menzel, D., Gould, S. B., et al. (2014). Chloroplast incorporation and long-term photosynthetic performance through the life cycle in laboratory cultures of Elysia timida (Sacoglossa, Heterobranchia). Frontiers in Zoology, 11(1), 5. doi: 10.1186/1742-9994-11-5.CrossRefPubMedPubMedCentralGoogle Scholar
- Stoecker, D. K., Johnson, M. D., de Vargas, C., & Not, F. (2009). Acquired phototrophy in aquatic protists.Google Scholar
- Wägele, H., & Johnsen, G. (2001). Observations on the histology and photosynthetic performance of “solar-powered” opisthobranchs (Mollusca, Gastropoda, Opisthobranchia) containing symbiotic chloroplasts or zooxanthellae. Organisms Diversity & Evolution, 1(3), 193–210. doi: 10.1078/1439-6092-00016.CrossRefGoogle Scholar
- Wägele, H., Deusch, O., Händeler, K., Martin, R., Schmitt, V., Christa, G., et al. (2011). Transcriptomic evidence that longevity of acquired plastids in the photosynthetic slugs Elysia timida and Plakobranchus ocellatus does not entail lateral transfer of algal nuclear genes. Molecular Biology and Evolution, 28(1), 699–706. doi: 10.1093/molbev/msq239.CrossRefPubMedGoogle Scholar