Abstract
Due to its extraordinary longevity and wide distribution, the ocean quahog Arctica islandica has become an important species model in both aging and environmental change research. Notwithstanding that, most genetic studies on ocean quahogs have been focused on fishery related, phylogeographic and phylogenetic aspects but nothing is known about their chromosomes. In this work, the chromosomes of the ocean quahog Arctica islandica were analysed by means of 4′,6-diamidino-2-phenylindole (DAPI)/propidium iodide (PI) staining and fluorescent in situ hybridization (FISH) with rDNA, histone gene and telomeric probes. Whilst both 5S rDNA and 45S rDNA were clustered at single subcentromeric locations on the long arms of chromosome pairs 2 and 12, respectively, histone gene clusters located on the short arms of chromosome pairs 7, 10 and 17. As happens with most bivalves, the location of the vertebrate type telomeric sequence clusters was restricted to chromosome ends. The knowledge of the karyotype can facilitate the anchoring of genomic sequences to specific chromosome pairs in this species.
Highlights
The ocean quahog Arctica islandica (Linnaeus, 1767), the longest lived non-colonial animal, is the sole extant species of the family Arcticidae (Bivalvia) and inhabits continental shelves of the NorthAtlantic [1,2]
Molecular analysis of telomere dynamics [11] demonstrated that both telomerase activity and telomere lengths were independent of age and habitat in ocean quahogs, suggesting that stable telomere maintenance might contribute to their longevity
Mitotic metaphase plate stained with diamidino-2-phenylindole (DAPI) (a) and DAPI/
Summary
Atlantic [1,2] As this species has been commercially harvested for decades in North America and Iceland, the better studied aspects of its biology are those more directly related to fisheries and sustainable harvest [3]. The extraordinary longevity of ocean quahogs [1,4] together with its wide distribution have converted A. islandica in an important species model in both aging [5,6] and environmental change research [7]. Transcriptome libraries were generated in this species in order to study changes in the expression of oxidative stress related genes [10]. Molecular analysis of telomere dynamics [11] demonstrated that both telomerase activity and telomere lengths were independent of age and habitat in ocean quahogs, suggesting that stable telomere maintenance might contribute to their longevity
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