It is the largest individual mollusc in terms of live weight and one of the highest in terms of total ecological biomass. It has a circumpolar distribution and is highly abundant. elliptica in particular has strong support as a sentinel species. The predictions of the effect of these thermal changes on Antarctic marine biodiversity are complex and further complicated by reductions in ocean pH.Īntarctic species, in general, have been proposed as excellent candidates for the development of climate change molecular biomarkers, whilst L. However, regional differences are apparent and climate change along the Antarctic Peninsula has been particularly rapid with a temperature increase in the surface layers of the Bellingshausen Sea of 1☌ in 50 years. This thermal response is viewed against predictions that globally oceanic sea surface temperatures are predicted to rise on average by 2☌ over the next 100 years. These animals suffer significant mortalities at 4-5☌, but lose essential biological functions, such as the ability to bury in sediment, much earlier, at only 1-2☌ over current summer maximum sea water temperatures. elliptica is one of the more sensitive species. Īntarctic marine invertebrates are stenothermal and L. It has also been the subject of significant investigation of its thermal tolerance and the expected impact of climate change. However more recent research has focused on the longevity of this species in relation to reactive oxygen species production, antioxidant defences and cellular ageing, as this species often lives 25 years or more. Studies initially focused on its ecology, and general physiology: reproduction, development, growth and seasonal energetics. This clam has been studied for a number of years and is one of the best characterised Antarctic marine invertebrates. In spite of a widespread latitudinal distribution ranging from the tropics, through temperate Australasia to Antarctica, research on this genus is dominated by work on the Antarctic species ( Laternula elliptica). Laternulids are infaunal bivalve molluscs, which morphologically resemble the soft-shelled clam Mya arenaria, the major ingredient of clam chowder. A number of promising candidate genes were identified for functional analyses, which will be the subject of further investigation in this species and also used in model-hopping experiments in more tractable and economically important model aquaculture species, such as Crassostrea gigas and Mytilus edulis. Sequencing of mantle tissue from this non-model species has considerably increased resources for the investigation of the processes of shell deposition and repair in molluscs in a changing environment. This is the first 454 data from an Antarctic marine invertebrate. The sequence data contained 46,235 microsatellites and 13,084 Single Nucleotide Polymorphisms(SNPs/INDELS), providing a resource for population and also gene function studies. A membrane transport protein (SEC61) was also characterised and this demonstrated the utility of the clam sequence data as a resource for examining cold adapted amino acid substitutions. Putative identifications were made for a number of classical shell deposition genes, such as tyrosinase, carbonic anhydrase and metalloprotease 1, along with novel members of the family 2 G-Protein Coupled Receptors (GPCRs). All transcripts were screened against an in-house database of genes shown to be involved in extracellular matrix formation and calcium homeostasis in metazoans. These results indicated that the mantle is a transcriptionally active tissue which is actively proliferating. BLAST sequence similarity searching assigned putative function to 17% of the data set, with a significant proportion of these transcripts being involved in binding and potentially of a secretory nature, as defined by GO molecular function and biological process classifications. elliptica mantle tissue generated 18,290 contigs with an average size of 535 bp (ranging between 142 bp-5.591 kb). Hence, this species presents as an ideal candidate for studies into the processes of calcium regulation and shell deposition in our changing ocean environments. The Southern Ocean has amongst the lowest present-day CaCO 3 saturation rate of any ocean region, and is predicted to be among the first to become undersaturated under current ocean acidification scenarios. Previous studies have shown that this mollusc displays a high level of plasticity with regard to shell deposition and damage repair against a background of genetic homogeneity. It plays a significant role in bentho-pelagic coupling and hence has been proposed as a sentinel species for climate change monitoring. The Antarctic clam, Laternula elliptica, is an infaunal stenothermal bivalve mollusc with a circumpolar distribution.
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