The first genome size estimates for six species of krill (Malacostraca, Euphausiidae): large genomes at the north and south poles
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Krill (family Euphausiidae) represent some of the most abundant organisms in the both northern and southern oceanic environments and provide food for various animals including humans. Despite their importance, little is known about krill from a genomic standpoint, even with regard to basic properties such as total genome size. This study provides genome size estimates for six species of krill from both the North Atlantic and Southern Oceans which are the first such estimates for any species of euphausiid. Genome size estimates were obtained using both flow cytometry and Feulgen image analysis densitometry with chicken and trout blood as internal standards. Haploid genome sizes ranged from 12.77 to 48.53 pg, providing roughly fourfold variation within these six species alone. With such large estimates, sequencing of a krill genome will currently be costly and laborious, but further studies should be conducted to determine the composition of these exceptionally large genomes.
KeywordsKrill Crustacean Genome size Feulgen image analysis densitometry Flow cytometry
This study was supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant to Dr. Ryan Gregory and an NSERC Postgraduate Scholarship to Nicholas Jeffery. Thanks to the British Antarctic Survey (BAS) and the French Polar Institute (IPEV) for providing all specimens for this study. Angus Atkinson of the BAS Ecosystems programme provided E. superba, while E. frigida¸ E. triacantha, and Thysanoessa sp. were provided by Gabriele Stowasser from the DISCOVERY2010 programme at the BAS. Dr. Geraint Tarling provided M. norvegica. Dr Melody Clark (BAS) collated the samples for this study and arranged dispatch to Canada. Thanks also to Dr. Jean-Yves Toullec for providing specimens of E. crystallorophias and to the crew of the Astrolabe for specimen collection. Thanks to Dr. Ryan Gregory, Dr. Melody Clark, and Tyler Elliott for providing useful comments on early drafts of the manuscript.
- Bennett MD, Leitch IJ (2010) Plant DNA C-values Database. Kew Royal Botanical Gardens. http://data.kew.org/cvalues/
- Dorward HM, Wyngaard GA (1997) Variability and pattern of chromatin diminution in the freshwater Cyclopidae (Crustacea: Copepoda). Arch Hydrobiol 107:447–465Google Scholar
- Gregory TR (2011) Animal genome size database. http://www.genomesize.com
- Martin JW, Davis GE (2001) An updated classification of the recent Crustacea. Science Series (Los Angeles) 39. Natural History Museum of Los Angeles County: Los Angeles. VII, 123 ppGoogle Scholar