The scientists sequenced the genome of Strigamia maritima, a northern European centipede, as part of a study published in the journal PLOS Biology. This study improves knowledge of the evolution and diversification of the mandibulate arthropods. 

Fifty-two research institutions around the world, led by the experts Ariel D. Chipman, David E.K. Ferrier and Michael Akam, as part of a consortium with Roderic Guigó, professor of genetics at the Department of Experimental and Health Sciences (CEXS), Marco Mariotti, a member of the Bioinformatics research team at the Centre for Genomic Regulation (CRG), a UPF-affiliated centre, as well as researchers at the University of Barcelona. 

An unusual species as a model for the study

S. maritima is the first myriapod for which the genome has been sequenced. It is part of one of the five arthropod subphyla, with Hexapods (including insects), crustaceans, and the quelicerats and trilobites (which are extinct). This particular organism is an unusual species, as it has no eyes and hatches with a full set of adult segments.

S. maritima is the model species of the miriápodos in studies about developmental biology and ecology because its genome has a reduced size (290 megabases) and they can be captured easily in nature and are easy to maintain in a laboratory.

The international team of experts identified about 15,000 genes - a similar number to the known genome of many insects. However, 30% of the genes are specific to S. maritima and have evolved due to various gene duplication processes since the common ancestor that separates this species from other arthropod species with sequenced genomes .  

No trace of the genetic structures that capture light

The 15,000 genes identified - humans have 20,000 - are distributed across one pair of large chromosomes and seven pairs of smaller ones (including the X and Y sex chromosomes). According to the results, the arrangement of genes is relatively well preserved, as it is very similar to the genomes in other animal phyla, and is much less altered than in other arthropods in model organisms such as flies.

One of the most surprising findings is that these centipedes appear to have lost the genes encoding all the known light receptors used by animals, as well as the genes controlling the circadian rhythms or body clock.

Reference:

Akam, M.; Almeida, F. C.; Chipman, A. D.; Ferrier, D. E. K.; Rozas, J.; Sánchez Gracia, A., et al.  «The first myriapod genome sequence reveals conservative arthropod gene content and genome organisation in the centipede  Strigamia maritima».  PLOS Biology, novembre de 2014. DOI: 10.1371/journal.pbio.100200