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Salmon lice
Photo: Sussie Dalvin
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The salmon louse genome has been sequenced

Work on sequencing the sea louse genome has reached astage where it will be possible to use the results in the beginning of 2011. By then the genome is fully sequenced and partially analyzed, making it possible to utilise it in the work towards developing vaccines and new medications against salmon lice. As the salmon louse has developed resistance against most chemicals used for delousing at fish farms, this is an important step towards developing alternative approaches.

The genome of the salmon louse consists of hundreds of millions of nucleic acids. In order to map the genome, it is necessary to determine the order of these nucleic acids by sequencing them. This is done by splitting the genome into millions of pieces, which are then individually sequenced. Once this has been done, it is then necessary to reconstruct the genome by putting the bits together in what could be described as a giant jigsaw puzzle. When the puzzle is completed, the genome is mapped. By the end of 2010 the genome of the salmon louse has been fully sequenced, and the puzzling of the puzzle  has begun.

Good results

Natural genetic variation can make it difficult to put together a genome. Often you end up with many short sequences that cannot be united into longer pieces. However, preliminary results of the sequencing of the sea louse genome indicate that the sequence pieces will be relatively long, making it easier to reconstruct the genome.
- The reason that we are achieving such good results in this project in comparison with other comparable projects is probably that we have sequenced an inbred line of lice with highly reduced genetic variation, explains Rasmus Skern-Mauritzen, the researcher managing the sequencing project.

A useful resource for researchers and businesses

Once the genome has been mapped, it will be used to develop vaccines and chemical delousing agents. A genome database will save researchers valuable time when developing new delousing methods. The good sequencing and initial analysis results mean that we can start using the sequencing data in research even before the genome has been fully mapped. Therefore, after a quality control that will be completed shortly, the results will be made available to researchers and industry working on finding solutions to problems with salmon lice.

About the project

The salmon licee genome is being mapped by researchers from The Institute of Marine Research, the University of Bergen and Max Planck Institute for Molecular Genetics. The project has been funded by The Institute of Marine Research, Marine Harvest and The Fishery and Aquaculture Industry Research Fund.

Facts about sea lice

Latin name: Lepeophtheirus salmonis
Distribution: occur naturally in Norwegian waters. Their numbers have risen significantly in parallel with the growth of the aquaculture industry.
Biology: sea lice are parasites with eight life stages, three of which are free-swimming, two of which are stationary and three of which are mobile. They attach themselves to salmon in the third life stage.
Size: adult female: 12 mm (approx. 29 mm including egg strings); adult male: 6 mm.
Diet: the skin and blood of salmonids. The lice only start feeding when they have attached themselves to a host fish (stationary and mobile stages).
Reproduction: all year round, but reproduce increasingly quickly as temperatures rise in spring.
Dispersal: free-swimming stages spread on currents in fjords and coastal waters.
Treatment: biological methods (wrasse) or chemicals (medication).

Sea lice

Contact

Rasmus Skern
400 69 007