Abstract
Functional kleptoplasty in sacoglossan sea slugs is among the most curious photosynthetic associations known. One member of these marine molluscs, Elysia viridis, is known to incorporate plastids from a variety of different algae food sources, but with apparently different outcomes and differences in the time span of the retention of functional kleptoplasts. While it was previously shown that kleptoplasts that stem from Codium tomentosum are kept functional for several weeks (long-term retention, LtR), those that stem from Bryopsis hypnoides or Cladophora rupestris are thought to be of limited use regarding photosynthetic capacity (short-term retention, StR). This is important, because it touches upon the popular yet controversial question of how important photosynthesis is for the thriving of these slugs. The aim of the present study was to determine to what degree the plastid source determines retention time. We, therefore, compared E. viridis feeding on either Cladophora sp. or B. hypnoides. We show that kleptoplasts of B. hypnoides incorporate 14CO2, but with rapidly declining efficiency throughout the first week of starvation, while the plastids of Cladophora sp. are, surprisingly, not incorporated to begin with. The radulae of the different samples showed adjustment to the food source, and when feeding on Cladophora sp., E. viridis survived under laboratory conditions under both starvation and non-starvation conditions. Our results demonstrate that (i) the ability to incorporate plastids by E. viridis differs between the food sources B. hypnoides and Cladophora sp., and (ii) photosynthetic active kleptoplasts are not an inevitable requirement for survival.
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References
Baker AC (2003) Flexibility and specificity in coral-algal symbiosis: diversity, ecology, and biogeography of Symbiodinium. Annu Rev Ecol Evol Syst 34:661–689. https://doi.org/10.1146/annurev.ecolsys.34.011802.132417
Barnes RSK, Hughes RN (1999) An introduction to marine ecology, 3rd edn. Blackwell Science Ltd., Victoria
Baumgartner FA, Toth GB (2014) Abundance and size distribution of the sacoglossan Elysia viridis on co-occurring algal hosts on the Swedish west coast. PLoS One 9:e92472. https://doi.org/10.1371/journal.pone.0092472
Baumgartner FA, Motti CA, de Nys R, Paul NA (2009) Feeding preferences and host associations of specialist marine herbivores align with quantitative variation in seaweed secondary metabolites. Mar Ecol Prog Ser 396:1–12
Baumgartner FA, Pavia H, Toth GB (2014) Individual specialization to non-optimal hosts in a polyphagous marine invertebrate herbivore. PLoS One 9:e102752. https://doi.org/10.1371/journal.pone.0102752
Baumgartner FA, Pavia H, Toth GB (2015) Acquired phototrophy through retention of functional chloroplasts increases growth efficiency of the sea slug Elysia viridis. PLoS One 10:e0120874. https://doi.org/10.1371/journal.pone.0120874
Bernhard JM, Bowser SS (1999) Benthic foraminifera of dysoxic sediments: chloroplast sequestration and functional morphology. Earth Sci Rev 46(1):149–165. https://doi.org/10.1016/S0012-8252(99)00017-3
Burns JA, Zhang H, Hill E, Kim E, Kerney R (2017) Transcriptome analysis illuminates the nature of the intracellular interaction in a vertebrate-algal symbiosis. eLife Sci 6:e22054. https://doi.org/10.7554/elife.22054
Cartaxana P, Trampe E, Kühl M, Cruz S (2017) Kleptoplast photosynthesis is nutritionally relevant in the sea slug Elysia viridis. Sci Rep 7(1):7714
Casalduero FG, Muniain C (2006) Photosynthetic activity of the solar-powered lagoon mollusc Elysia timida (Risso, 1818) (Opisthobranchia: Sacoglossa). Symbiosis 41:151–158
Christa G, Zimorski V, Woehle C, Tielens AGM, Wägele H, Martin WF, Gould SB (2013a) Plastid-bearing sea slugs fix CO2 in the light but do not require photosynthesis to survive. Proc Biol Sci 281:20132493. https://doi.org/10.1098/rspb.2013.2493
Christa G, Wescott L, Schäberle TF, König GM, Wägele H (2013b) 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. https://doi.org/10.1007/s00425-012-1788-6
Christa G, de Vries J, Jahns P, Gould SB (2014a) Switching off photosynthesis: the dark side of sacoglossan slugs. Commun Integr Biol 7:e28029. https://doi.org/10.4161/cib.28029
Christa G, Händeler K, Schäberle TF, König GM, Wägele H (2014b) Identification of sequestered chloroplasts in photosynthetic and non-photosynthetic sacoglossan sea slugs (Mollusca, Gastropoda). Front Zool 11(1):15. https://doi.org/10.1186/1742-9994-11-15
Christa G, Händeler K, Kück P, Vleugels M, Franken J, Karmeinski D, Wägele H (2015) Phylogenetic evidence for multiple independent origins of functional kleptoplasty in Sacoglossa (Heterobranchia, Gastropoda). Org Divers Evol 15(1):23–36. https://doi.org/10.1007/s13127-014-0189-z
Cruz S, Calado R, Serôdio J, Cartaxana P (2013) Crawling leaves: photosynthesis in sacoglossan sea slugs. J Exp Bot 64(13):3999–4009. https://doi.org/10.1093/jxb/ert197
Cruz S, Calado R, Serôdio J, Jesus B, Cartaxana P (2014) Pigment profile in the photosynthetic sea slug Elysia viridis (Montagu, 1804). J Mollus Stud 80(5):475–481. https://doi.org/10.1093/mollus/eyu021
Cruz S, Cartaxana P, Newcomer R, Dionisio G, Calado R, Serôdio J, Pelletreau KN, Rumpho ME (2015) Photoprotection in sequestered plastids of sea slugs and respective algal sources. Sci Rep 5:7904. https://doi.org/10.1038/srep07904
Cueto M, D’Croz L, Maté JL, San-Martín A, Darias J (2005) Elysiapyrones from Elysia diomedea. Do such metabolites evidence an enzymatically assisted electrocyclization cascade for the biosynthesis of their bicyclo [4.2. 0] octane core? Org Lett 7(3):415–418. https://doi.org/10.1021/ol0477428
de Vries J, Rauch C, Christa G, Gould SB (2014a) A sea slug’s guide to plastid symbiosis. Acta Soc Bot Pol 83(4):415–421. https://doi.org/10.5586/asbp.2014.042
de Vries J, Christa G, Gould SB (2014b) Plastid survival in the cytosol of animal cells. Trends Plant Sci 19(6):347–350. https://doi.org/10.1016/j.tplants.2014.03.010
de Vries J, Woehle C, Christa G, Wägele H, Tielens AGM, Jahns P, Gould SB (2015) Comparison of sister species identifies factors underpinning plastid compatibility in green sea slugs. Proc Biol Sci 282(1802):20142519. https://doi.org/10.1098/rspb.2014.2519
Díaz-Marrero AR, Cueto M, D’Croz L, Darias J (2008) Validating an endoperoxide as a key intermediate in the biosynthesis of elysiapyrones. Org Lett 10(14):3057–3060. https://doi.org/10.1021/ol8010425
Edmunds PJ, Davies PS (1986) An energy budget for Porites porites (Scleractinia). Mar Biol 92(3):339–347. https://doi.org/10.1007/BF00392674
Evertsen J, Johnsen G (2009) In vivo and in vitro differences in chloroplast functionality in the two north Atlantic sacoglossans (Gastropoda, Opisthobranchia) Placida dendritica and Elysia viridis. Mar Biol 156(5):847–859. https://doi.org/10.1007/s00227-009-1128-y
Evertsen J, Burghardt I, Johnsen G, Wägele H (2007) Retention of functional chloroplasts in some sacoglossans from the Indo-Pacific and Mediterranean. Mar Biol 151(6):2159–2166. https://doi.org/10.1007/s00227-007-0648-6
Graham ER, Fay SA, Davey A, Sanders RW (2013) Intracapsular algae provide fixed carbon to developing embryos of the salamander Ambystoma maculatum. J Exp Biol 216(3):452–459. https://doi.org/10.1242/jeb.076711
Greene RW, Muscatine L (1972) Symbiosis in sacoglossan opisthobranchs: photosynthetic products of animal-chloroplast associations. Mar Biol 14(3):253–259. https://doi.org/10.1007/BF00348288
Guillard RRL (1975) Culture of phytoplankton for feeding marine invertebrates. In: Smith WL, Chanley MH (eds) Culture of marine invertebrate animals. Springer, Boston. https://doi.org/10.1007/978-1-4615-8714-9_3
Guillard RRL, Ryther JH (1962) Studies of marine planktonic diatoms. I. Cyclotella nana Hustedt and Detonula confervacea Cleve. Can J Microbiol 8:229–239. https://doi.org/10.1139/m62-029
Guindon SXP, Gascuel O (2003) A Simple, fast, and accurate algorithm to estimate large phylogenies by maximum likelihood. Syst Biol 52:696–704. https://doi.org/10.1080/10635150390235520
Guindon S, Dufayard JF, Lefort V, Anisimova M, Hordijk W, Gascuel O (2010) New algorithms and methods to estimate maximum-likelihood phylogenies: assessing the performance of PhyML 3.0. Syst Biol 59(3):307–321
Händeler K, Grzymbowski YP, Krug PJ, Wägele H (2009) Functional chloroplasts in metazoan cells—a unique evolutionary strategy in animal life. Front Zool 6(1):28. https://doi.org/10.1186/1742-9994-6-28
Hinde R (1978) The metabolism of photosynthetically fixed carbon by isolated chloroplasts from Codium fragile (Chlorophyta: Siphonales) and by Elysia viridis (Mollusca: Sacoglossa). Biol J Linn Soc 10(3):329–342. https://doi.org/10.1111/j.1095-8312.1978.tb00019.x
Hinde R, Smith DC (1972) Persistence of functional chloroplasts in Elysia viridis (Opisthobranchia, Sacoglossa). Nature 239(88):30–31. https://doi.org/10.1038/newbio239030a0
Hinde R, Smith D (1975) The role of photosynthesis in the nutrition of the mollusc Elysia viridis. Biol J Linn Soc 7(2):161–171. https://doi.org/10.1111/j.1095-8312.1975.tb00738.x
Hirose E (2015) Ascidian photosymbiosis: diversity of cyanobacterial transmission during embryogenesis. Genesis 53:121–131. https://doi.org/10.1002/dvg.22778
Jensen KR (1989) Learning as a factor in diet selection by Elysia viridis (Montagu) (Opisthobranchia). J Molluscan Stud 55(1):79–88. https://doi.org/10.1093/mollus/55.1.79
Jensen KR (1993) Morphological adaptations and plasticity of radular teeth of the Sacoglossa (=Ascoglossa) (Mollusca: Opisthobranchia) in relation to their food plants. Biol J Linn Soc 48(2):135–155. https://doi.org/10.1111/j.1095-8312.1993.tb00883.x
Jensen KR (1997) Evolution of the Sacoglossa (Mollusca, Opisthobranchia) and the ecological associations with their food plants. Evol Ecol 11(3):301–335. https://doi.org/10.1023/A:1018468420368
Jerschabek Laetz EM, Wägele H (2017) Chloroplast digestion and the development of functional kleptoplasty in juvenile Elysia timida (Risso, 1818) as compared to short-term and non-chloroplast-retaining sacoglossan slugs. PLoS One 12(10):e0182910. https://doi.org/10.1371/journal.pone.0182910
Johnson MD (2010) The acquisition of phototrophy: adaptive strategies of hosting endosymbionts and organelles. Photosynth Res 107(1):117–132. https://doi.org/10.1007/s11120-010-9546-8
Johnson MD, Oldach D, Delwiche CF, Stoecker DK (2007) Retention of transcriptionally active cryptophyte nuclei by the ciliate Myrionecta rubra. Nature 445(7126):426–428. https://doi.org/10.1038/nature05496
Karasov WH, Martínez del Rio C (2007) Physiological ecology: how animals process energy, nutrients, and toxins. Princeton University Press, Princeton
Katoh K, Misawa K, Kuma KI, Miyata T (2002) MAFFT: a novel method for rapid multiple sequence alignment based on fast Fourier transform. Nucleic Acids Res 30(14):3059–3066. https://doi.org/10.1093/nar/gkf436
Kerney R, Kim E, Hangarter RP, Heiss AA, Bishop CD, Hall BK (2011) Intracellular invasion of green algae in a salamander host. Proc Natl Acad Sci USA 108(16):6497–6502. https://doi.org/10.1073/pnas.1018259108
Krug PJ, Vendetti JE, Valdes A (2016) Molecular and morphological systematics of Elysia Risso, 1818 (Heterobranchia: Sacoglossa) from the Caribbean region. Zootaxa 4148(1):1–137. https://doi.org/10.11646/zootaxa.4148.1.1
Laetz EMJ, Moris VC, Moritz L, Haubrich AN, Wägele H (2017) Photosynthate accumulation in solar-powered sea slugs—starving slugs survive due to accumulated starch reserves. Front Zool 14:1–9. https://doi.org/10.1186/s12983-016-0186-5
Maeda T, Kajita T, Maruyama T, Hirano Y (2010) Molecular phylogeny of the Sacoglossa, with a discussion of gain and loss of kleptoplasty in the evolution of the group. Biol Bul 219(1):17–26. https://doi.org/10.1086/BBLv219n1p17
Marín A, Ros JD (1992) Dynamics of a peculiar plant-herbivore relationship: the photosynthetic ascoglossan Elysia timida and the chlorophycean Acetabularia acetabulum. Mar Biol 112(4):677–682. https://doi.org/10.1007/BF00346186
Middlebrooks ML, Bell SS, Curtis NE, Pierce SK (2014) Atypical plant–herbivore association of algal food and a kleptoplastic sea slug (Elysia clarki) revealed by DNA barcoding and field surveys. Mar Biol 161(6):1429–1440. https://doi.org/10.1007/s00227-014-2431-9
Minnhagen S, Carvalho WF, Salomon PS, Janson S (2008) Chloroplast DNA content in Dinophysis (Dinophyceae) from different cell cycle stages is consistent with kleptoplasty. Environ Microbiol 10(9):2411–2417. https://doi.org/10.1111/j.1462-2920.2008.01666.x
Muscatine L, McCloskey L, Marian R (1981) Estimating the daily contribution of carbon from zooxanthellae to coral animal respiration. Limnol Oceanogr 26(4):601–611. https://doi.org/10.4319/lo.1981.26.4.0601
Pelletreau KN, Worful JM, Sarver KE, Rumpho ME (2012) Laboratory culturing of Elysia chlorotica reveals a shift from transient to permanent kleptoplasty. Symbiosis 58(1–3):221–232. https://doi.org/10.1007/s13199-012-0192-0
Petherick A (2010) A solar salamander. Nature. https://doi.org/10.1038/news.2010.384
Pierce SK, Curtis NE, Middlebrooks ML (2015) Sacoglossan sea slugs make routine use of photosynthesis by a variety of species—specific adaptations. Invertebr Biol 134(2):103–115. https://doi.org/10.1111/ivb.12082
Pinder A, Friet S (1994) Oxygen transport in egg masses of the amphibians Rana sylvatica and Ambystoma maculatum: convection, diffusion and oxygen production by algae. J Exp Biol 197(1):17–30
Rauch C, Christa G, de Vries J, Woehle C, Gould SB (2017a) Mitochondrial genome assemblies of Elysia timida and Elysia cornigera and the response of mitochondrion associated metabolism during starvation. Genome Biol Evol. https://doi.org/10.1093/gbe/evx129
Rauch C, Jahns P, Tielens AGM, Gould SB, Martin WF (2017b) On being the right size as an animal with plastids. Front Plant Sci 8:1402. https://doi.org/10.3389/fpls.2017.01402d
Raven JA, Walker DI, Jensen KR, Handley LL, Scrimgeour CM, McInroy SG (2001) What fraction of the organic carbon in sacoglossans is obtained from photosynthesis by kleptoplastids? An investigation using the natural abundance of stable carbon isotopes. Mar Biol 138(3):537–545. https://doi.org/10.1007/s002270000488
Riesgo A, Farrar N, Windsor PJ, Giribet G, Leys SP (2014) The analysis of eight transcriptomes from all poriferan classes reveals surprising genetic complexity in sponges. Mol Biol Evol 31(5):1102–1120. https://doi.org/10.1093/molbev/msu057oi
Rumpho ME, Pelletreau KN, Moustafa A, Bhattacharya D (2011) The making of a photosynthetic animal. J Exp Biol 214(2):303–311. https://doi.org/10.1242/jeb.046540
Schwartz JA, Curtis NE, Pierce SK (2010) Using algal transcriptome sequences to identify transferred genes in the sea slug, Elysia chlorotica. J Evol Biol 37(1):29–37. https://doi.org/10.1007/s11692-010-9079-2
Serôdio J, Pereira S, Furtado J, Silva R, Coelho H, Calado R (2010) In vivo quantification of kleptoplastic chlorophyll a content in the “solar-powered” sea slug Elysia viridis using optical methods: spectral reflectance analysis and PAM fluorometry. Photochem Photobiol Sci 9(1):68–77. https://doi.org/10.1039/B9PP00058E
Serôdio J, Silva R, Ezequiel J, Calado R (2011) Photobiology of the symbiotic acoel flatworm Symsagittifera roscoffensis: algal symbiont photoacclimation and host photobehaviour. J Mar Biol Assoc UK 91:163–171. https://doi.org/10.1017/S0025315410001001
Serôdio J, Cruz S, Cartaxana P, Calado R (2014) Photophysiology of kleptoplasts: photosynthetic use of light by chloroplasts living in animal cells. Philos Trans R Soc Lond B Biol Sci 369(1640):20130242
Teugels B, Bouillon S, Veuger B, Middelburg JJ, Koedam N (2008) Kleptoplasts mediate nitrogen acquisition in the sea slug Elysia viridis. Aquat Biol 4(1):15–21. https://doi.org/10.3354/ab00092
Trench RK, Gooday GW (1973) Incorporation of [3H]-Leucine into protein by animal tissues and by endosymbiotic chloroplasts in Elysia viridis Montagu. Comp Biochem Physiol A Physiol 44(2):321–330. https://doi.org/10.1016/0300-9629(73)90485-4
Trench ME, Trench RK, Muscatine L (1970) Utilization of photosynthetic products of symbiotic chloroplasts in mucus synthesis by Placobranchus ianthobapsus (Gould), Opisthobranchia, Sacoglossa. Comp Biochem Physiol 37(1):113–117. https://doi.org/10.1016/0010-406X(70)90964-3
Trench R, Boyle JE, Smith D (1973) The association between chloroplasts of Codium fragile and the mollusc Elysia viridis. II. Chloroplast ultrastructure and photosynthetic carbon fixation in E. viridis. Proc R Soc Lond B Biol Sci 184(1074):63–81. https://doi.org/10.1098/rspb.1973.0031
Trench RK, Boyle JE, Smith DC (1974) The Association between chloroplasts of Codium fragile and the mollusc Elysia viridis. III. Movement of photosynthetically fixed formula C in tissues of intact living E. viridis and in Tridachia crispata. Proc Biol Sci 185:453–464
Trowbridge CD (1998) Diet specialization limits herbivorous sea slug’s capacity to switch among food sources. Ecology 72(5):1880–1888. https://doi.org/10.2307/1940985
Trowbridge CD, Todd CD (2001) Host-plant change in marine specialist herbivores: ascoglossan sea slugs on introduced macroalgae. Ecol Monogr 71(2):219–243. https://doi.org/10.1890/0012-9615(2001)071[0219:HPCIMS]2.0.CO;2
Venn AA, Loram JE, Douglas AE (2008) Photosynthetic symbioses in animals. J Exp Bot 59(5):1069–1080. https://doi.org/10.1093/jxb/erm328
Vieira S, Calado R, Coelho H, Serôdio J (2009) Effects of light exposure on the retention of kleptoplastic photosynthetic activity in the sacoglossan mollusc Elysia viridis. Mar Biol 156(5):1007–1020. https://doi.org/10.1007/s00227-009-1144-y
Wägele H, Martin WF (2013) Endosymbioses in sacoglossan sea slugs: plastid-bearing animals that keep photosynthetic organelles without borrowing genes. In: Löffelhardt W (ed) Endosymbiosis. Springer, Vienna, pp 291–324. https://doi.org/10.1007/978-3-7091-1303-5_14
Acknowledgements
Funding through the DAAD (P.R.I.M.E.) and FCT to GC (SFRH/BPD/109892/2015), DFG to S.B.G. (GO1825/4-1), and through the ERC to Prof. William F. Martin (ERC 666053) is gratefully acknowledged. For financial support, thanks are due to Centre for Environmental and Marine Studies (UID/AMB/50017), FCT/Ministry of Science and Education through national funds, and the co-funding by European Fund For Regional Development, within the PT2020 Partnership Agreement and Compete 2020.
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CR, SBG, JS and GC planned the experiments, which were conducted by CR, AGMT and GC. CR, SBG and GC wrote the manuscript, whose final version was approved by all authors. We thank Steffen Köhler (CAi, HHU) for imaging of the slugs and for his help with SEM imaging, and Marion Nissen (CAi, HHU) for her help with the TEM.
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Rauch, C., Tielens, A.G.M., Serôdio, J. et al. The ability to incorporate functional plastids by the sea slug Elysia viridis is governed by its food source. Mar Biol 165, 82 (2018). https://doi.org/10.1007/s00227-018-3329-8
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DOI: https://doi.org/10.1007/s00227-018-3329-8