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Eastman KE, Pendleton AL, Shaikh MA, Suttiyut T, Ogas R, Tomko P, Gavelis G, Widhalm JR, Wisecaver JH. A reference genome for the long-term kleptoplast-retaining sea slug Elysia crispata morphotype clarki. G3 (BETHESDA, MD.) 2023; 13:jkad234. [PMID: 37816307 PMCID: PMC10700116 DOI: 10.1093/g3journal/jkad234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/15/2023] [Accepted: 09/22/2023] [Indexed: 10/12/2023]
Abstract
Several species of sacoglossan sea slugs possess the incredible ability to sequester chloroplasts from the algae they consume. These "photosynthetic animals" incorporate stolen chloroplasts, called kleptoplasts, into the epithelial cells of tubules that extend from their digestive tracts throughout their bodies. The mechanism by which these slugs maintain functioning kleptoplasts in the absence of an algal nuclear genome is unknown. Here, we report a draft genome of the sacoglossan slug Elysia crispata morphotype clarki, a morphotype native to the Florida Keys that can retain photosynthetically active kleptoplasts for several months without feeding. We used a combination of Oxford Nanopore Technologies long reads and Illumina short reads to produce a 786-Mb assembly (N50 = 0.459 Mb) containing 68,514 predicted protein-coding genes. A phylogenetic analysis found no evidence of horizontal acquisition of genes from algae. We performed gene family and gene expression analyses to identify E. crispata genes unique to kleptoplast-containing slugs that were more highly expressed in fed versus unfed developmental life stages. Consistent with analyses in other kleptoplastic slugs, our investigation suggests that genes encoding lectin carbohydrate-binding proteins and those involved in regulation of reactive oxygen species and immunity may play a role in kleptoplast retention. Lastly, we identified four polyketide synthase genes that could potentially encode proteins producing UV- and oxidation-blocking compounds in slug cell membranes. The genome of E. crispata is a quality resource that provides potential targets for functional analyses and enables further investigation into the evolution and mechanisms of kleptoplasty in animals.
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Affiliation(s)
- Katharine E Eastman
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Amanda L Pendleton
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Mearaj A Shaikh
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA
| | - Thiti Suttiyut
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA
| | - Raeya Ogas
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Paxton Tomko
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Gregory Gavelis
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Joshua R Widhalm
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA
| | - Jennifer H Wisecaver
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
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A methodological note on using next generation sequencing technology to identify the algal sources of stolen chloroplasts in a single sea slug specimen (Elysia crispata) to provide a comprehensive view of the animal’s kleptoplast population. Symbiosis 2023. [DOI: 10.1007/s13199-023-00895-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Pigment and Fatty Acid Heterogeneity in the Sea Slug Elysia crispata Is Not Shaped by Habitat Depth. Animals (Basel) 2021; 11:ani11113157. [PMID: 34827889 PMCID: PMC8614334 DOI: 10.3390/ani11113157] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/30/2021] [Accepted: 10/30/2021] [Indexed: 01/02/2023] Open
Abstract
Simple Summary Some species of sacoglossan sea slugs are able to steal chloroplasts from the algae they feed on and maintain them functional for several months, a process termed “kleptoplasty”. One of these photosynthetic slugs is Elysia crispata, found in coral reefs of the Gulf of Mexico. This sacoglossan inhabits different depths (0–25 m), being exposed to different food sources and contrasting light conditions. In this work, we characterized the pigment and fatty acid (FA) profiles, and quantified the total lipid, glycolipid and phospholipid contents of E. crispata from shallow (0–4 m) and deeper (8–12 m) waters, after a month of starvation to determine the longest and more stable retention of chloroplasts and its relation to habitat depth. Biochemical analyses allowed the identification of 12 photosynthetic pigments and 27 FAs. Heterogeneity in the composition of pigments confirmed the long-term retention of functional chloroplasts ingested from different algae. However, the differences found in pigment profile, total lipid content, and FA composition on individuals of E. crispata were not related to habitat depth. High amounts of glycolipids, exclusive chloroplast lipids, suggest a good condition of these photosynthetic organelles in animal cells. These results contribute baseline physiological data that may help explain evolutionary associations such as endosymbiosis. Abstract Long-term retention of functional chloroplasts in animal cells occurs only in sacoglossan sea slugs. Analysis of molecules related to the maintenance of these organelles can provide valuable information on this trait (kleptoplasty). The goal of our research was to characterize the pigment and fatty acid (FA) composition of the sea slug Elysia crispata and their associated chloroplasts that are kept functional for a long time, and to quantify total lipid, glycolipid and phospholipid contents, identifying differences between habitats: shallow (0–4 m) and deeper (8–12 m) waters. Specimens were sampled and analyzed after a month of food deprivation, through HPLC, GC-MS and colorimetric methods, to ensure an assessment of long-term kleptoplasty in relation to depth. Pigment signatures indicate that individuals retain chloroplasts from different macroalgal sources. FA classes, phospholipid and glycolipid contents displayed dissimilarities between depths. However, heterogeneities in pigment and FA profiles, as well as total lipid, glycolipid and phospholipid amounts in E. crispata were not related to habitat depth. The high content of chloroplast origin molecules, such as Chl a and glycolipids after a month of starvation, confirms that E. crispata retains chloroplasts in good biochemical condition. This characterization fills a knowledge gap of an animal model commonly employed to study kleptoplasty.
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Feliciano K, Malaquias MAE, Stout C, Brenzinger B, Gosliner TM, Valdés Á. Molecular and morphological analyses reveal pseudocryptic diversity in Micromelo undatus (Bruguière, 1792) (Gastropoda: Heterobranchia: Aplustridae). SYST BIODIVERS 2021. [DOI: 10.1080/14772000.2021.1939458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Kendall Feliciano
- Department of Biological Sciences, California State Polytechnic University, 3801 West Temple Avenue, Pomona, California 91768, USA
| | - Manuel António E. Malaquias
- Department of Natural History, University Museum of Bergen, University of Bergen, PB7800, Bergen, N-5020, Norway
| | - Carla Stout
- Department of Biological Sciences, California State Polytechnic University, 3801 West Temple Avenue, Pomona, California 91768, USA
| | - Bastian Brenzinger
- SNSB-Bavarian State Collection of Zoology, Münchhausenstraße 21, München, 81247, Germany
| | - Terrence M. Gosliner
- Department of Invertebrate Zoology and Geology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, California 94118, USA
| | - Ángel Valdés
- Department of Biological Sciences, California State Polytechnic University, 3801 West Temple Avenue, Pomona, California 91768, USA
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Mahadevan P, Middlebrooks ML. Bacterial diversity in the clarki ecotype of the photosynthetic sacoglossan, Elysia crispata. Microbiologyopen 2020; 9:e1098. [PMID: 32602643 PMCID: PMC7520991 DOI: 10.1002/mbo3.1098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/25/2020] [Accepted: 05/30/2020] [Indexed: 01/04/2023] Open
Abstract
Few studies have examined the bacterial communities associated with photosynthetic sacoglossan sea slugs. In this study, we determined the bacterial diversity in the clarki ecotype, Elysia crispata using 16S rRNA sequencing. Computational analysis using QIIME2 revealed variability between individual samples, with the Spirochaetes and Bacteroidetes phyla dominating most samples. Tenericutes and Proteobacteria were also found, among other phyla. Computational metabolic profiling of the bacteria revealed a variety of metabolic pathways involving carbohydrate metabolism, lipid metabolism, nucleotide metabolism, and amino acid metabolism. Although associated bacteria may be involved in mutually beneficial metabolic pathways, there was a high degree of variation in the bacterial community of individual slugs. This suggests that many of these relationships are likely opportunistic rather than obligate and that many of these bacteria may live commensally providing no major benefit to the slugs.
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Donohoo SA, Wade RM, Sherwood AR. Finding the Sweet Spot: Sub-Ambient Light Increases Fitness and Kleptoplast Survival in the Sea Slug Plakobranchus cf. ianthobaptus Gould, 1852. THE BIOLOGICAL BULLETIN 2020; 238:154-166. [PMID: 32597715 DOI: 10.1086/709371] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Sacoglossans, or "sap-sucking" sea slugs, are primarily algivorous, with many taxa exhibiting kleptoplasty, the feeding and retaining of photosynthetically active chloroplasts from algae. The Plakobranchus species complex exhibits some of the longest kleptoplast retention and survival times under starvation conditions, but the contributions of these kleptoplasts to their survival and overall fitness have been widely debated. In this study we assessed the effects of starvation and light on the fitness of Plakobranchus cf. ianthobaptus and its kleptoplasts by placing starved individuals in eight daily average light treatments, ranging from near dark (2 µmol photon m-2 s-1) to ambient light (470 µmol photon m-2 s-1). Slug weight was used as a metric of fitness, and kleptoplast photosynthetic activity was determined via maximum quantum yield (Fv/Fm) by pulse-amplitude modulated fluorometry as a proxy for kleptoplast health. Plakobranchus individuals in near-dark and high light treatments (>160 µmol photon m-2 s-1) experienced significantly greater weight loss than those in low light (65 µmol photon m-2 s-1) and moderate light treatments (95-135 µmol photon m-2 s-1). Additionally, individuals in high light treatments experienced a rapid decline in kleptoplast photosynthetic activity, while all other treatments experienced minimal decline. This relationship between kleptoplast degradation and weight loss suggests an important link between fitness and kleptoplasty. Given the significant negative effects of ambient conditions, regular refreshment and replenishment of kleptoplasts or physiological or behavioral adjustments are likely employed for the benefits of kleptoplasty to be maintained.
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The complete disappearance of a long standing sacoglossan sea slug population following Hurricane Irma, despite recovery of the local algal community. Symbiosis 2020. [DOI: 10.1007/s13199-020-00670-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Middlebrooks ML, Curtis NE, Pierce SK. Algal Sources of Sequestered Chloroplasts in the Sacoglossan Sea Slug Elysia crispata Vary by Location and Ecotype. THE BIOLOGICAL BULLETIN 2019; 236:88-96. [PMID: 30933641 DOI: 10.1086/701732] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Sacoglossan sea slugs feed by suctorially consuming siphonaceous green algae. Most sacoglossan species are feeding specialists, but the Caribbean coral reef-dwelling Elysia crispata is polyphagous and sequesters chloroplasts from multiple algal species into cells lining its digestive diverticulum for use in photosynthesis. We have used sequences of the chloroplast-encoded rbcL gene to compare the chloroplast donor algae in five populations of E. crispata from various Caribbean locations. We found that E. crispata utilizes more algal species than was previously known, including some algae previously not reported as present in the region. In addition, slugs from each location had unique chloroplast arrays with little overlap, except that all locations had slugs feeding on algae within the genus Bryopsis. This variation in diet between locations suggests that the slugs may be exhibiting local adaptation in their dietary choices, and it highlights ecological differences between the Caribbean-wide reef-dwelling ecotypes and the mangrove lagoon ecotypes found in the Florida Keys.
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Christa G, Pütz L, Sickinger C, Melo Clavijo J, Laetz EMJ, Greve C, Serôdio J. Photoprotective Non-photochemical Quenching Does Not Prevent Kleptoplasts From Net Photoinactivation. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00121] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Kleptoplastic sacoglossan species have very different capacities for plastid maintenance despite utilizing the same algal donors. Symbiosis 2015. [DOI: 10.1007/s13199-015-0317-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Serôdio J, Cruz S, Cartaxana P, Calado R. Photophysiology of kleptoplasts: photosynthetic use of light by chloroplasts living in animal cells. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130242. [PMID: 24591722 DOI: 10.1098/rstb.2013.0242] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Kleptoplasty is a remarkable type of photosynthetic association, resulting from the maintenance of functional chloroplasts--the 'kleptoplasts'--in the tissues of a non-photosynthetic host. It represents a biologically unique condition for chloroplast and photosynthesis functioning, occurring in different phylogenetic lineages, namely dinoflagellates, ciliates, foraminiferans and, most interestingly, a single taxon of metazoans, the sacoglossan sea slugs. In the case of sea slugs, chloroplasts from macroalgae are often maintained as intracellular organelles in cells of these marine gastropods, structurally intact and photosynthetically competent for extended periods of time. Kleptoplasty has long attracted interest owing to the longevity of functional kleptoplasts in the absence of the original algal nucleus and the limited number of proteins encoded by the chloroplast genome. This review updates the state-of-the-art on kleptoplast photophysiology, focusing on the comparative analysis of the responses to light of the chloroplasts when in their original, macroalgal cells, and when sequestered in animal cells and functioning as kleptoplasts. It covers fundamental but ecologically relevant aspects of kleptoplast light responses, such as the occurrence of photoacclimation in hospite, operation of photoprotective processes and susceptibility to photoinhibition. Emphasis is given to host-mediated processes unique to kleptoplastic associations, reviewing current hypotheses on behavioural photoprotection and host-mediated enhancement of photosynthetic performance, and identifying current gaps in sacoglossan kleptoplast photophysiology research.
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Affiliation(s)
- João Serôdio
- Departamento de Biologia and CESAM, Universidade de Aveiro, , Campus Universitário de Santiago, Aveiro 3810-193, Portugal
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