Solar-powered sea slugs. Mollusc/algal chloroplast symbiosis

Program in Molecular and Environmental Plant Sciences, Texas A&M University, College Station, Texas 77843-2133, USA.
Plant physiology (Impact Factor: 6.84). 06/2000; 123(1):29-38. DOI: 10.1104/pp.123.1.29
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    • "Among the organisms living in highly photophilic habitats, a group of herbivorous marine opisthobranch gastropods belonging to the family Plakobranchidae (Mollusca: Gastropoda: Sacoglossa) are known as " solar-powered mollusks " (Rudman, 1998; Rumpho et al., 2000). Actually, these animals assimilate chloroplasts from siphonaceous marine algae and maintain the active organelles for several months in their own tissues where they carry out the photosynthesis (Jensen, 1997; Rumpho et al., 2000, 2008; Evertsen et al., 2007). Natural products from plakobranchids include photo-active -pyrone polypropionate-derived compounds that have been suggested to serve as sunscreens to protect the mollusks from damaging UV radiation (Ireland and Scheuer, 1979). "
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    ABSTRACT: The occurrence of (−)-phototridachiahydropyrone (5) in nature has been proven. This compound has been now identified as minor component of the extract of marine sacoglossan mollusk Elysia crispata from which the main (−)-tridachiahydropyrone (4) was previously described. Synthetic (±)-5 was formerly obtained by Moses’ group by biomimetic photochemical conversion of (±)-tridachiahydropyrone (4). The same authors suggested that compound 5 had to be a natural product derived from precursor 4 “yet to be discovered”. Comparison of CD profiles of natural (−)-4 and (−)-5 indicated the same absolute configuration for both compounds. This evidence is in agreement with the concerted mechanism proposed for the photochemical conversion.
    Revista Brasileira de Farmacognosia 10/2015; DOI:10.1016/j.bjp.2015.07.028 · 0.83 Impact Factor
    • "Such kleptoplastidy (i.e., sequestering of chloroplasts) is known in various organisms from protists to metazoans. Sea slugs retain the chloroplasts from consumed green algae and obtain the photosynthetic products (e.g., Green et al. 2000; Maeda et al. 2010; Rumpho et al. 2000). Dinoflagellates also retain cryptomonads as kleptoplasts (e.g., Horiguchi and Pienaar 1992; Larsen 1988); in particular, Dinophysis acuminata retains the ciliate Mesodinium rubrum that first retains chloroplasts from the cryptophyte Geminigera cryophila (Park et al. 2006). "
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    ABSTRACT: The benthic foraminifer Virgulinella fragilis Grindell and Collen 1976 has multiple putative symbioses with both bacterial and kleptoplast endobionts, possibly aiding its survival in environments from dysoxia (5-45 μmol-O2/liter) to microxia (0-5 μmol-O2/liter) and in the dark. To clarify the origin and function of V. fragilis endobionts, we used genetic analyses and transmission electron microscope observations. Virgulinella fragilis retained δ-proteobacteria concentrated at its cell periphery just beneath the cell membranes. Unlike another foraminifer Stainforthia spp., which retain many bacterial species, V. fragilis has a less variable bacterial community. This suggests that V. fragilis maintains specific intracellular bacterial flora. Unlike the endobiotic bacteria, V. fragilis kleptoplasts originated from various diatom species and are found in the interior cytoplasm. We found evidence of both retention and digestion of kleptoplasts, and of fragmentation of the kleptoplastid outer membrane that likely facilitates transport of kleptoplastid products to the host. Accumulations of mitochondria were observed encircling endobiotic bacteria. It is likely that the bacteria use host organic material for carbon oxidation. The mitochondria may use oxygen available around the δ-proteobacteria and synthesize ATP, perhaps for sulfide oxidation.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 07/2015; 62:454–469. DOI:10.1111/jeu.12200 · 3.22 Impact Factor
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    • "Plastid division has not been observed in the animals; this is likely due to the lack of the algal nucleus and requisite replication machinery. Yet, animals collected from the wild and subsequently starved in the laboratory (provided with only light and CO2) can be sustained for up to 10 months with no additional food [2], [3], [5], [6], [10]. Although this kleptoplasty was first described nearly 50 years ago [11], [12], the mechanisms underlying plastid function in the foreign animal cell remain unclear. "
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    ABSTRACT: The establishment of kleptoplasty (retention of "stolen plastids") in the digestive tissue of the sacoglossan Elysia chlorotica Gould was investigated using transmission electron microscopy. Cellular processes occurring during the initial exposure to plastids were observed in laboratory raised animals ranging from 1-14 days post metamorphosis (dpm). These observations revealed an abundance of lipid droplets (LDs) correlating to plastid abundance. Starvation of animals resulted in LD and plastid decay in animals <5 dpm that had not yet achieved permanent kleptoplasty. Animals allowed to feed on algal prey (Vaucheria litorea C. Agardh) for 7 d or greater retained stable plastids resistant to cellular breakdown. Lipid analysis of algal and animal samples supports that these accumulating LDs may be of plastid origin, as the often algal-derived 20∶5 eicosapentaenoic acid was found in high abundance in the animal tissue. Subsequent culturing of animals in dark conditions revealed a reduced ability to establish permanent kleptoplasty in the absence of photosynthetic processes, coupled with increased mortality. Together, these data support an important role of photosynthetic lipid production in establishing and stabilizing this unique animal kleptoplasty.
    PLoS ONE 05/2014; 9(5):e97477. DOI:10.1371/journal.pone.0097477 · 3.23 Impact Factor
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