Lucinidae

Lucinidae
Temporal range: Silurian - recent
Divaricella huttoniana
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Heterodonta
Order: Veneroida
Superfamily: Lucinoidea
Family: Lucinidae
Fleming, 1828
Genera

See text

Lucinidae is a family of saltwater clams, marine bivalve molluscs.

These bivalves are remarkable for their endosymbiosis with sulphide-oxidizing bacteria.[1]

Characteristics

The members of this family are found in muddy sand or gravel at or below low tide mark. They have characteristically rounded shells with forward-facing projections. The valves are flattened and etched with concentric rings. Each valve bears two cardinal and two plate-like lateral teeth. These molluscs do not have siphons but the extremely long foot makes a channel which is then lined with slime and serves for the intake and expulsion of water.[2]

Symbiosis

Lucinids host their sulfur-oxidizing symbionts in specialized gill cells called bacteriocytes.[3] Lucinids are burrowing bivalves that live in environments with sulfide-rich sediments.[4] The bivalve will pump sulfide-rich water over its gills from the inhalant siphon in order to provide symbionts with sulfur and oxygen.[4] The endosymbionts then use these substrates to fix carbon into organic compounds, which are then transferred to the host as nutrients.[5] During periods of starvation, lucinids may harvest and digest their symbionts as food.[5]

Symbionts are acquired via phagocytosis of bacteria by bacterioctyes.[6] Symbiont transmission occurs horizontally, where juvenile lucinids are aposymbiotic and acquire their symbionts from the environment in each generation.[7] Lucinids maintain their symbiont population by reaquiring sulfur-oxidizing bacteria throughout their lifetime.[8] Although process of symbiont acquisition is not entirely characterized, it likely involves the use of the binding protein, Codakine, isolated from the lucinid bivalve, Codaki orbicularis.[9] It is also known that symbionts do not replicate within bacteriocytes because of inhibition by the host. However, this mechanism is not well understood.[8]

Lucinid bivalves originated in the Silurian, however, they did not diversify until the late Cretaceous along with the evolution of seagrass meadows and mangrove swamps.[10] Lucinids were able to colonize these sulfide rich sediments because they already maintained a population of sulfide-oxidizing symbionts. In modern environments, seagrass, lucinid bivalves, and the sulfur-oxidizing symbionts constitute a three-way symbiosis. Because of the lack of oxygen in coastal marine sediments, dense seagrass meadows produce sulfide-rich sediments by trapping organic matter that is later decomposed by sulfate-reducing bacteria.[11] The lucinid-symbiont holobiont removes toxic sulfide from the sediment, and the seagrass roots provide oxygen to the bivalve-symbiont system.[11]

Genera and species

The species and genera include:

References

  1. ↑ Taylor, J. D.; Glover, E. A. (2006-11-24). "Lucinidae (Bivalvia) - the most diverse group of chemosymbiotic molluscs". Zoological Journal of the Linnean Society 148 (3): 421–438. doi:10.1111/j.1096-3642.2006.00261.x. ISSN 0024-4082.
  2. ↑ Barrett, J. H. and C. M. Yonge, 1958. Collins Pocket Guide to the Sea Shore. P. 161. Collins, London
  3. ↑ Roeselers, Guus; Newton, Irene L. G. (2012-02-22). "On the evolutionary ecology of symbioses between chemosynthetic bacteria and bivalves". Applied Microbiology and Biotechnology 94 (1): 1–10. doi:10.1007/s00253-011-3819-9. ISSN 0175-7598. PMC 3304057. PMID 22354364.
  4. 1 2 Seilacher, Adolf (1990-01-01). "Aberrations in bivalve evolution related to photo‐ and chemosymbiosis". Historical Biology 3 (4): 289–311. doi:10.1080/08912969009386528. ISSN 0891-2963.
  5. 1 2 König, Sten; Le Guyader, Hervé; Gros, Olivier (2015-02-01). "Thioautotrophic bacterial endosymbionts are degraded by enzymatic digestion during starvation: Case study of two lucinids Codakia orbicularis and C. orbiculata". Microscopy Research and Technique 78 (2): 173–179. doi:10.1002/jemt.22458. ISSN 1097-0029.
  6. ↑ Elisabeth, Nathalie H.; Gustave, Sylvie D.D.; Gros, Olivier (2012-08-01). "Cell proliferation and apoptosis in gill filaments of the lucinid Codakia orbiculata (Montagu, 1808) (Mollusca: Bivalvia) during bacterial decolonization and recolonization". Microscopy Research and Technique 75 (8): 1136–1146. doi:10.1002/jemt.22041. ISSN 1097-0029.
  7. ↑ Bright, Monika; Bulgheresi, Silvia (2010-03-01). "A complex journey: transmission of microbial symbionts". Nature Reviews Microbiology 8 (3): 218–230. doi:10.1038/nrmicro2262. ISSN 1740-1526. PMC 2967712. PMID 20157340.
  8. 1 2 Gros, Olivier; Elisabeth, Nathalie H.; Gustave, Sylvie D. D.; Caro, Audrey; Dubilier, Nicole (2012-06-01). "Plasticity of symbiont acquisition throughout the life cycle of the shallow-water tropical lucinid Codakia orbiculata (Mollusca: Bivalvia)". Environmental Microbiology 14 (6): 1584–1595. doi:10.1111/j.1462-2920.2012.02748.x. ISSN 1462-2920.
  9. ↑ Gourdine, Jean-Philippe; Smith-Ravin, Emilie Juliette (2007-05-01). "Analysis of a cDNA-derived sequence of a novel mannose-binding lectin, codakine, from the tropical clam Codakia orbicularis". Fish & Shellfish Immunology 22 (5): 498–509. doi:10.1016/j.fsi.2006.06.013.
  10. ↑ Stanley, S. M. "Evolutionary radiation of shallow-water Lucinidae (Bivalvia with endosymbionts) as a result of the rise of seagrasses and mangroves". Geology 42 (9): 803–806. doi:10.1130/g35942.1.
  11. 1 2 Heide, Tjisse van der; Govers, Laura L.; Fouw, Jimmy de; Olff, Han; Geest, Matthijs van der; Katwijk, Marieke M. van; Piersma, Theunis; Koppel, Johan van de; Silliman, Brian R. (2012-06-15). "A Three-Stage Symbiosis Forms the Foundation of Seagrass Ecosystems". Science 336 (6087): 1432–1434. doi:10.1126/science.1219973. ISSN 0036-8075. PMID 22700927.
  12. ↑ Olsson, Axel; Harbison, Anne (1953). Pliocene Mollusca of Southern Florida with special reference to those from North Saint Petersburg. Philadelphia: Academy of Natural Sciences.
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