Morten Skage

• Strand, Marius André; To, Thu-Hien; Tørresen, Ole Kristian; Fullmer, Sarah; Ferrari, Giada & Skage, Morten [Show all 9 contributors for this article] (2026). The origin of the octoploid cloudberry (Rubus chamaemorus) genome is the result of multiple and complex polyploidization events. Journal of Heredity. ISSN 0022-1503. 117(4), p. 822–833. doi: 10.1093/jhered/esag028. Full text in Research Archive
• Baalsrud, Helle T; Tørresen, Ole K; Danneels, Bram; Ferrari, Giada; Tooming-Klunderud, Ave & Skage, Morten [Show all 12 contributors for this article] (2026). Chromosomal fusions shaped the genome of the greater hornwrack bryozoan (Flustra foliacea) (Linnaeus, 1758). Journal of Heredity. ISSN 0022-1503. 117(4), p. 750–760. doi: https:/academic.oup.com/jhered/article/117/4/750/8497176. Full text in Research Archive Show summary

  The phylum Bryozoa is an understudied, yet commonly occurring, globally distributed bilaterian metazoan organismal group. They have a colonial lifestyle and an evolutionary history that spans at least 480 million years but likely longer. Despite their contentious phylogenetic affinities among metazoans, disproportionately few genomic investigations have been performed thus far. Here, we describe the first chromosome-level genome assembly of an individual Flustra foliacea colony belonging to the order Cheilostomatida, collected in southern Norway. The haplotype-resolved assembly of F. foliacea contains two pseudo-haplotypes spanning 956 megabases and 880 megabases, respectively. Both assemblies are highly complete both in terms of scaffolding (>90% of sequences placed in eight autosomal chromosomal pseudomolecules), and gene content (BUSCO completeness scores >90%). We also present gene and repeat annotations of the two assemblies. A comparison of our newly sequenced F. foliacea with five previously published bryozoan genomes supports the hypothesis that the group has undergone extensive genome rearrangements. This includes multiple chromosomal fusions in F. foliacea since their split with other cheilostome bryozoans. These fusions were enriched with long terminal repeat retrotransposons, highlighting the complex interplay between genome organization and genomic repeats. Our study contributes to a deeper understanding of bryozoan genome evolution and the role of repeats in metazoan genome organization.

• Solbakken, Monica Hongrø; Tørresen, Ole Kristian; Tooming-Klunderud, Ave; Skage, Morten; Bakken, Torkild & Jakobsen, Kjetill Sigurd (2026). Loss of Major Histocompatibility Complex I and II Function in the Genome of Glacier Lanternfish Provides Insight Into Evolution of Vertebrate Immune Systems. Genome Biology and Evolution (GBE). 18(7). doi: 10.1093/gbe/evag154. Full text in Research Archive
• Baalsrud, Helle Tessand; Garmann-Aarhus, Benedicte; Enevoldsen, Emily Louise Gilbert; Krabberød, Anders Kristian; Dominik, Fischer, & Tooming-Klunderud, Ave [Show all 13 contributors for this article] (2026). Centromeric satellite expansion drives genome evolution in the snowy owl. Genome Biology. ISSN 1474-7596. doi: 10.1186/s13059-026-04175-y. Full text in Research Archive Show summary

  Comparative genomic studies in birds have revealed that bird genomes are relatively repeat-poor and stable in terms of karyotype, size, and gene synteny/collinearity compared to other vertebrates. One notable exception is the owls, with cytogenetic studies demonstrating large variations in karyotypes and the evolution of unusual centromeric satellite repeats in some species. However, there has so far not been an investigation into genome architecture and repeat landscape of owls. Here, we present a chromosome-level genome assembly for the snowy owl (Bubo scandiacus). We find that the repeat DNA content in the relatively large snowy owl genome (1.6 Gb) is among the highest reported for any bird genome to date (28.34% compared to an average of ~ 10% in other birds). The bulk of the snowy owl genomic repeat landscape consists of extensive centromeric satellite arrays that form large contiguous blocks across multiple chromosomes. These arrays represent one of the largest centromeric satellite expansions reported in birds and are consistent with rapid turnover and amplification of centromeric repeats. Using gene collinearity analyses we show that the position of the centromeres are not homologous with chicken centromeres, and are located in regions with collinearity breaks to other bird genomes due to chromosomal rearrangements. Our results support rapid satellite turnover at lineage-specific centromeres, which could have played a role in centromeric drive, reproductive isolation and speciation of the snowy owl. The extensive centromeric satellite arrays uncovered in this genome highlight centromere evolution as a potentially important driver of genome evolution in owls.

• Tørresen, Ole K; Tooming-Klunderud, Ave; Skage, Morten; Streitlien, Anne Eline; Strand, Olav & Rolandsen, Christer Moe [Show all 10 contributors for this article] (2025). Chromosome-level genome assembly of Norwegian wild alpine reindeer (Rangifer tarandus tarandus). Journal of Heredity. ISSN 0022-1503. doi: 10.1093/jhered/esaf094. Full text in Research Archive Show summary

  We describe a chromosome-level genome assembly from a wild alpine reindeer individual (Rangifer tarandus tarandus) from the Rondane area in Southern Norway. The assembly is resolved into two pseudo-haplotypes: hap 1 spanning 3,081 Mb and hap 2 spanning 2,633 Mb. Contig N50 and scaffold N50 lengths are in the range of 31 to 41 and 66 to 69 Mb, respectively. A large part of these two haplotypes (83.8% and 90.4%, respectively) are scaffolded into 34 autosomal chromosomal pseudomolecules, and in sex chromosomes X and Y for hap 1. The BUSCO completeness scores are 98.0% and 95.2%, respectively, and gene annotations of the assemblies identified 37,998 and 36,977 protein-coding genes. We also present an updated and improved genome assembly for Svalbard reindeer (Rangifer tarandus platyrhynchus; contig N50 46 to 48 Mb, scaffold N50 67 to 71 Mb, BUSCO 95.4% to 98.0%) and a comparison with previously published genome assemblies of reindeer.

• Solbakken, Monica Hongrø; Tørresen, Ole K.; Tooming-Klunderud, Ave; Skage, Morten; Bakken, Torkild & Jakobsen, Kjetill Sigurd (2025). The genome of the Glacier lanternfish shows loss of MHC I and II function and provides insight into evolution of lanternfish immune systems. bioRxiv - the preprint server for biology. doi: https:/www.biorxiv.org/content/10.1101/2025.08.28.672920v1. Full text in Research Archive Show summary

  Lanternfishes (Myctophidae) are one of the most abundant and species diverse orders inhabiting the mesopelagic zone. Exploitation of marine resources has recently attracted increased interest. It is therefore essential to improve our understanding of the meso- and deep pelagic ecosystems with respect to conservation and management strategies. Genomic resources are paramount to enable in-depth studies of population structuring and understanding the inherent genetic diversity, but also to enable studies of processes such as local adaptation and selection. Here we present a genome assembly of the Glacier lanternfish (Benthosema glaciale) generated with long-read PacBio and Hi-C contact map data. By comparing additional available genomes from the Myctophiformes order we explore their adaptive immune strategies. Our findings reveal that multiple lineages within this order have lost a significant proportion of genes related to adaptive immunity (Electrona, Protomyctophum and Benthosema). We find simultaneous loss of both classical MHC class I and class II function coinciding with reduction in genetic diversity with respect to immunoglobulin and T-cell receptors. In contrast, the sister branch represented by Gymnoscopelus and Nannobrachium appear to have maintained the standard configuration of the jawed vertebrate adaptive immune system apart from large gene expansions in MHC class II. Our results demonstrate that the Benthosema-belonging lineage (Myctophinae) has completely lost the core functions of the adaptive immune system. How, when and why this occurred warrants further investigations.

• Martin, Sarah Louise; Torre, Renato La; Danneels, Bram; Tooming-Klunderud, Ave; Skage, Morten & Kollias, Spyridon [Show all 12 contributors for this article] (2025). Haplotype-resolved chromosome-level genome assemblies of four Diamesa species reveal the genetic basis of cold tolerance and high-altitude adaptations in arctic chironomids. GigaScience. doi: 10.1093/gigascience/giaf160. Full text in Research Archive Show summary

  Background Arctic and alpine insects experience extreme environmental stressors, yet the genomic basis of their adaptation is poorly understood. Diamesa midges (Diptera: Chironomidae) are cold-adapted insects inhabiting glacial and high-altitude freshwater ecosystems, but no chromosome-level genomes have been available to date. Findings We present the first haplotype-resolved, chromosome-level genomes for four Diamesa species (D. hyperborea, D. lindrothi, D. serratosioi and D. tonsa), assembled using PacBio HiFi sequencing and Hi-C scaffolding. The assemblies show high completeness and k-mer representation. Phylogenomic analyses place Diamesinae as sister to other Chironomidae except Podonominae, and comparisons suggest introgression between the distinct species D. hyperborea and D. tonsa. Comparative genomic analyses across 20 Diptera species identified significant gene family contractions in Diamesa related to oxygen transport and metabolism, consistent with adaptation to high-altitude, low-oxygen environments. Expansions were observed in histone-related and Toll-like receptor gene families, suggesting roles in chromatin remodeling and immune regulation under cold stress. A glucose dehydrogenase gene family was significantly expanded across all cold-adapted species studied, implicating it in cryoprotectant synthesis and oxidative stress mitigation. Diamesa exhibited the largest gene family contraction at any phylogenetic node, with limited overlap in expansions with other cold-adapted Diptera, indicating lineage-specific adaptation. Conclusions Our findings support the hypothesis that genome size condensation and selective gene family changes underpin survival in cold environments. These new genome assemblies provide a valuable resource for studying adaptation, speciation, and conservation in cold-specialist insects. Future integration of gene expression and population genomics will further clarify the evolutionary resilience of Diamesa in a warming world.

• Tørresen, Ole Kristian; Garmann-Aarhus, Benedicte; Hoff, Siv Nam Khang; Jentoft, Sissel; Svensson, Mikael & Schartum, Eivind Sandvik [Show all 11 contributors for this article] (2025). Comparison of whole-genome assemblies of European river lamprey (Lampetra fluviatilis) and brook lamprey (Lampetra planeri). Journal of Heredity. ISSN 0022-1503. 117, p. 96–106. doi: 10.1093/jhered/esaf036. Full text in Research Archive
• Strand, Marius André; To, Thu-Hien; Tørresen, Ole Kristian; Fullmer, Sarah; Skage, Morten & Tooming-Klunderud, Ave [Show all 8 contributors for this article] (2025). Chromosome-level assembly of the octoploid cloudberry (Rubus chamaemorus). BioRxiv. ISSN 0362-4331. doi: 10.1101/2025.07.07.663483. Full text in Research Archive
• Baalsrud, Helle Tessand; Garmann-Aarhus, Benedicte; Enevoldsen, Emily Louise Gilbert; Krabberød, Anders Kristian; Fischer, Dominik & Tooming-Klunderud, Ave [Show all 13 contributors for this article] (2024). Evolutionary new centromeres in the snowy owl genome putatively seeded from a transposable element. BioRxiv. ISSN 0362-4331. doi: 10.1101/2024.07.05.602039. Full text in Research Archive
• Cobb, Lauren Louise; Muinck, Eric de; Kollias, Spyridon; Skage, Morten; Gilfillan, Gregor & Sydenham, Markus A. K. [Show all 8 contributors for this article] (2024). High-throughput sequencing of insect specimens with sub-optimal DNA preservation using a practical, plate-based Illumina-compatible Tn5 transposase library preparation method. PLOS ONE. 19(3). doi: 10.1371/journal.pone.0300865. Full text in Research Archive Show summary

  Entomological sampling and storage conditions often prioritise efficiency, practicality and conservation of morphological characteristics, and may therefore be suboptimal for DNA preservation. This practice can impact downstream molecular applications, such as the generation of high-throughput genomic libraries, which often requires substantial DNA input amounts. Here, we use a practical Tn5 transposase tagmentation-based library preparation method optimised for 96-well plates and low yield DNA extracts from insect legs that were stored under sub-optimal conditions for DNA preservation. The samples were kept in field vehicles for extended periods of time, before long-term storage in ethanol in the freezer, or dry at room temperature. By reducing DNA input to 6ng, more samples with sub-optimal DNA yields could be processed. We matched this low DNA input with a 6-fold dilution of a commercially available tagmentation enzyme, significantly reducing library preparation costs. Costs and workload were further suppressed by direct post-amplification pooling of individual libraries. We generated medium coverage (>3-fold) genomes for 88 out of 90 specimens, with an average of approximately 10-fold coverage. While samples stored in ethanol yielded significantly less DNA compared to those which were stored dry, these samples had superior sequencing statistics, with longer sequencing reads and higher rates of endogenous DNA. Furthermore, we find that the efficiency of tagmentation-based library preparation can be improved by a thorough post-amplification bead clean-up which selects against both short and large DNA fragments. By opening opportunities for the use of sub-optimally preserved, low yield DNA extracts, we broaden the scope of whole genome studies of insect specimens. We therefore expect these results and this protocol to be valuable for a range of applications in the field of entomology.

• Tørresen, Ole K.; Kersten, Oliver Sven; Garmann-Aarhus, Benedicte; Helberg, Morten; Tooming-Klunderud, Ave & Skage, Morten [Show all 8 contributors for this article] (2024). A chromosome-level genome assembly of the common eider, Somateria mollissima (Linnaeus, 1758). Journal of Heredity. ISSN 0022-1503. doi: 10.1093/jhered/esae042. Full text in Research Archive Show summary

  The common eider, Somateria mollissima mollissima (Chordata; Aves; Anseriformes; Anatidae), is a large sea duck with a circumpolar distribution. We here describe a chromosome-level genome assembly from an individual female. The haplotype-resolved assembly contains one pseudo-haplotype spanning 1,205 megabases (with both Z and W sex chromosomes) and one pseudo-haplotype spanning 1,080 megabases. Most of these two assemblies (91.13% and 93.18%, respectively) are scaffolded into 32 autosomal chromosomal pseudomolecules plus Z and W for pseudo-haplotype one. The BUSCO completeness scores are 94.0% and 89.9%, respectively, and gene annotations of the assemblies identified 17,479 and 16,315 protein coding genes. Annotation of repetitive sequences classify 17.84% and 14.62% of pseudo-haplotype one and two, respectively, as repeats. The genome of the common eider will be a useful resource for the widely distributed northern species in light of climate change and anthropogenic threats.

• Jentoft, Sissel; Tørresen, Ole K.; Tooming-Klunderud, Ave; Skage, Morten; Kollias, Spyridon & Jakobsen, Kjetill Sigurd (2024). The genome sequence of the Atlantic cod, Gadus morhua (Linnaeus, 1758). Wellcome Open Research. 9. doi: 10.12688/wellcomeopenres.21122.1. Full text in Research Archive Show summary

  We present a genome assembly from an individual male Gadus morhua (the Atlantic cod; Chordata; Actinopteri; Gadiformes; Gadidae). The genome sequence is 669.9 megabases in span. Most of the assembly is scaffolded into 23 chromosomal pseudomolecules. Gene annotation of this assembly on Ensembl identified 23,515 protein coding genes.

• Dussex, Nicolas; Tørresen, Ole Kristian; Valk, Tom van der; Moullec, Mathilde Le; Veiberg, Vebjørn & Tooming-Klunderud, Ave [Show all 17 contributors for this article] (2023). Adaptation to the High-Arctic island environment despite long-term reduced genetic variation in Svalbard reindeer. iScience. 26(10). doi: 10.1016/j.isci.2023.107811. Full text in Research Archive Show summary

  Typically much smaller in number than their mainland counterparts, island populations are ideal systems to investigate genetic threats to small populations. The Svalbard reindeer (Rangifer tarandus platyrhynchus) is an endemic subspecies that colonized the Svalbard archipelago ca. 6,000–8,000 years ago and now shows numerous physiological and morphological adaptations to its arctic habitat. Here, we report a de-novo chromosome-level assembly for Svalbard reindeer and analyze 133 reindeer genomes spanning Svalbard and most of the species’ Holarctic range, to examine the genomic consequences of long-term isolation and small population size in this insular subspecies. Empirical data, demographic reconstructions, and forward simulations show that long-term isolation and high inbreeding levels may have facilitated the reduction of highly deleterious—and to a lesser extent, moderately deleterious—variation. Our study indicates that long-term reduced genetic diversity did not preclude local adaptation to the High Arctic, suggesting that even severely bottlenecked populations can retain evolutionary potential.

• Hoff, Siv Nam Khang; Baalsrud, Helle Tessand; Tooming-Klunderud, Ave; Skage, Morten; Richmond, Todd & Obernosterer, Gregor [Show all 10 contributors for this article] (2018). Long‐read sequence capture of the haemoglobin gene clusters across codfish species. Molecular Ecology Resources. ISSN 1755-098X. 19(1), p. 245–259. doi: 10.1111/1755-0998.12955. Full text in Research Archive
• Tørresen, Ole Kristian; Star, Bastiaan; Jentoft, Sissel; Reinar, William Brynildsen; Grove, Harald & Miller, Jason R. [Show all 16 contributors for this article] (2017). An improved genome assembly uncovers prolific tandem repeats in Atlantic cod. BMC Genomics. 18(1), p. 1–23. doi: 10.1186/s12864-016-3448-x. Full text in Research Archive Show summary

  Background The first Atlantic cod (Gadus morhua) genome assembly published in 2011 was one of the early genome assemblies exclusively based on high-throughput 454 pyrosequencing. Since then, rapid advances in sequencing technologies have led to a multitude of assemblies generated for complex genomes, although many of these are of a fragmented nature with a significant fraction of bases in gaps. The development of long-read sequencing and improved software now enable the generation of more contiguous genome assemblies. Results By combining data from Illumina, 454 and the longer PacBio sequencing technologies, as well as integrating the results of multiple assembly programs, we have created a substantially improved version of the Atlantic cod genome assembly. The sequence contiguity of this assembly is increased fifty-fold and the proportion of gap-bases has been reduced fifteen-fold. Compared to other vertebrates, the assembly contains an unusual high density of tandem repeats (TRs). Indeed, retrospective analyses reveal that gaps in the first genome assembly were largely associated with these TRs. We show that 21% of the TRs across the assembly, 19% in the promoter regions and 12% in the coding sequences are heterozygous in the sequenced individual. Conclusions The inclusion of PacBio reads combined with the use of multiple assembly programs drastically improved the Atlantic cod genome assembly by successfully resolving long TRs. The high frequency of heterozygous TRs within or in the vicinity of genes in the genome indicate a considerable standing genomic variation in Atlantic cod populations, which is likely of evolutionary importance.

• Star, Bastiaan; Hansen, Marianne Helén Selander; Skage, Morten; Bradbury, Ian R.; Godiksen, Jane Amtoft & Kjesbu, Olav Sigurd [Show all 7 contributors for this article] (2016). Preferential amplification of repetitive DNA during whole genome sequencing library creation from historic samples. Science and Technology of Archaeological Research. 2(1), p. 36–45. doi: 10.1080/20548923.2016.1160594. Full text in Research Archive
• Hatteland, Bjørn Arild; Solhøy, Torstein; Schander, Christoffer; Skage, Morten; Proschwitz, Ted von & Noble, Leslie R. (2015). Introgression and differentiation of the invasive slug Arion vulgaris from native A. ater. Malacologia. ISSN 0076-2997. 58(1-2), p. 303–321. doi: 10.4002/040.058.0210. Full text in Research Archive
• Star, Bastiaan; Nederbragt, Alexander Johan; Hansen, Marianne Helén Selander; Skage, Morten; Gilfillan, Gregor Duncan & Bradbury, Ian R. [Show all 10 contributors for this article] (2014). Palindromic sequence artifacts generated during next generation sequencing library preparation from historic and ancient DNA. PLOS ONE. 9(3). doi: 10.1371/journal.pone.0089676. Full text in Research Archive Show summary

  Degradation-specific processes and variation in laboratory protocols can bias the DNA sequence composition from samples of ancient or historic origin. Here, we identify a novel artifact in sequences from historic samples of Atlantic cod (Gadus morhua), which forms interrupted palindromes consisting of reverse complementary sequence at the 5′ and 3′-ends of sequencing reads. The palindromic sequences themselves have specific properties – the bases at the 5′-end align well to the reference genome, whereas extensive misalignments exists among the bases at the terminal 3′-end. The terminal 3′ bases are artificial extensions likely caused by the occurrence of hairpin loops in single stranded DNA (ssDNA), which can be ligated and amplified in particular library creation protocols. We propose that such hairpin loops allow the inclusion of erroneous nucleotides, specifically at the 3′-end of DNA strands, with the 5′-end of the same strand providing the template. We also find these palindromes in previously published ancient DNA (aDNA) datasets, albeit at varying and substantially lower frequencies. This artifact can negatively affect the yield of endogenous DNA in these types of samples and introduces sequence bias.

• Hatteland, Bjørn Arild; Symondson, William O. C.; King, R. A.; Skage, Morten; Schander, Christoffer & Solhøy, Torstein (2011). Molecular analysis of predation by carabid beetles (Carabidae) on the invasive Iberian slug Arion lusitanicus. Bulletin of entomological research. ISSN 0007-4853. 101(6), p. 675–686. doi: 10.1017/S0007485311000034. Full text in Research Archive
• Star, Bastiaan; Nederbragt, Alexander Johan; Jentoft, Sissel; Grimholt, Unni; Malmstrøm, Martin & Gregers, Tone Fredsvik [Show all 42 contributors for this article] (2011). The genome sequence of Atlantic cod reveals a unique immune system. Nature. ISSN 0028-0836. 477(7363), p. 207–210. doi: 10.1038/nature10342. Full text in Research Archive Show summary

  Atlantic cod (Gadus morhua) is a large, cold-adapted teleost that sustains long-standing commercial fisheries and incipient aquaculture. Here we present the genome sequence of Atlantic cod, showing evidence for complex thermal adaptations in its haemoglobin gene cluster and an unusual immune architecture compared to other sequenced vertebrates. The genome assembly was obtained exclusively by 454 sequencing of shotgun and paired-end libraries, and automated annotation identified 22,154 genes. The major histocompatibility complex (MHC) II is a conserved feature of the adaptive immune system of jawed vertebrates, but we show that Atlantic cod has lost the genes for MHC II, CD4 and invariant chain (Ii) that are essential for the function of this pathway. Nevertheless, Atlantic cod is not exceptionally susceptible to disease under natural conditions5. We find a highly expanded number of MHC I genes and a unique composition of its Toll-like receptor (TLR) families. This indicates how the Atlantic cod immune system has evolved compensatory mechanisms in both adaptive and innate immunity in the absence of MHC II. These observations affect fundamental assumptions about the evolution of the adaptive immune system and its components in vertebrates.

• Lattman, H; Lättman, Håkan; Lindblom, Louise; Mattsson, Jan-Eric; Milberg, Per & Skage, Morten [Show all 7 contributors for this article] (2009). Estimating the dispersal capacity of the rare lichen Cliostomum corrugatum. Biological Conservation. ISSN 0006-3207. 142(8), p. 1870–1878. doi: 10.1016/j.biocon.2009.03.026. Full text in Research Archive
• Petrusek, Adam; Hobæk, Anders; Nilssen, Jens Petter; Skage, Morten; Cerný, Martin & Brede, Nora [Show all 7 contributors for this article] (2008). A taxonomic reappraisal of the European Daphnia longispina complex (Crustacea, Cladocera, Anomopoda). Zoologica Scripta. ISSN 0300-3256. 37(5), p. 507–519. doi: 10.1111/j.1463-6409.2008.00336.x. Full text in Research Archive Show summary

  Jens Petter Nilssen har angitt Niels Henrik Abel Centre, N-4980 Gjerstad, Norway i artikkelen/aa

• Skage, Morten; Hobek, Anders; Ruthova, Štĕpánka; Keller, Barbara; Petrusek, Adam & Sed'a, Jaromír R [Show all 7 contributors for this article] (2007). Intra-specific rDNA-ITS restriction site variation and an improved protocol to distinguish species and hybrids in the Daphnia longispina complex. Hydrobiologia. ISSN 0018-8158. 594, p. 19–32. doi: 10.1007/s10750-007-9090-5. Full text in Research Archive
• Nilssen, JP; Hobæk, Anders; Petrusek, Adam & Skage, Morten (2007). Restoring Daphnia lacustris GO Sars, 1862 (Crustacea, Anomopoda): A cryptic species in the Daphnia longispina group. Hydrobiologia. ISSN 0018-8158. 594(1), p. 5–17. doi: 10.1007/s10750-007-9076-3. Full text in Research Archive
• Skage, Morten & Schander, Christoffer (2007). DNA from formalin-fixed tissue: extraction or repair? That is the question. Marine Biology Research. ISSN 1745-1000. 3(5), p. 289–295. doi: 10.1080/17451000701473942. Full text in Research Archive Show summary

  Establishing effective DNA-based protocols for use on archival material fixed in formaldehyde (formalin) is a particularly challenging task. Formalin fixation induces cross-linking with nucleic acids and proteins, thereby reducing the amount and quality of the extracted DNA. Previous attempts have primarily focused on optimizing DNA extraction protocols. Here we focus on the use of enzymes capable of in vitro repair of DNA extracts prior to amplification of the nucleic acids by the polymerase chain reaction (PCR). The amplification success of mitochondrial DNA was greater using the repair enzyme assay (56%) than with the regular PCR assay (20%), and even more convincing results were obtained with the amplified nuclear ribosomal region (91% versus 21%). These results indicate that in vitro repair of DNA damage (depurinated sites, strand nicks and base modifications) increases the number of samples that amplify, amplify to a greater extent and amplify fewer ancillary bands and that DNA repair has been overlooked as a way of improving the efficiency of molecular methods used on formalin-fixed samples. Fidelity has not been specifically investigated, but preliminary results indicate that misincorporation is not a major problem.

• Coyer, James A.; Hoarau, Galice; Skage, Morten; Stam, Wytze T. & Olsen, Jeanine L. (2006). Origin of Fucus serratus (Heterokontophyta; Fucaceae) populations in Iceland and the Faroes: a microsatellite-based assessment. European journal of phycology. ISSN 0967-0262. 41(2), p. 235–246. doi: 10.1080/09670260600652820. Full text in Research Archive
• Skage, Morten; Gabrielsen, Tove M & Rueness, Jan (2005). A molecular approach to investigate the phylogenetic basis of three widely used species groups in the red algal genus Ceramium (Ceramiales, Rhodophyta). Phycologia. ISSN 0031-8884. 44(4), p. 353–360. Full text in Research Archive
• Skage, Morten; Gabrielsen, Tove M. & Rueness, Jan (2005). A molecular approach to investigate the phylogenetic basis of three widely used species groups in the red algal genus Ceramium (Ceramiales, Rhodophyta). Phycologia. ISSN 0031-8884. 44(4), p. 353–360. Full text in Research Archive
• Skage, Morten (2004). Daphnia Galeata × D. Longispina Hybrids in Western Norway. Hydrobiologia. ISSN 0018-8158. 526(1), p. 55–62. Full text in Research Archive

View all works in NVA

• Martin, Sarah Louise; Torre, Renato La; Danneels, Bram; Tooming-Klunderud, Ave; Skage, Morten & Kollias, Spyridon [Show all 12 contributors for this article] (2025). Genome assemblies of four Diamesa species reveal the genetic basis of cold tolerance adaptations and species boundaries. Full text in Research Archive
• Baalsrud, Helle Tessand; Arnyasi, Mariann; To, Thu-Hien; Shapaval, Volha; Byrtusova, Dana & Andersstuen, Terese [Show all 13 contributors for this article] (2025). Chromosomal Chaos: Exploring a Dramatic Shift in the Evolution of Genome Organization in Mucoromycota. Full text in Research Archive
• Baalsrud, Helle Tessand; Arnyasi, Mariann; To, Thu-Hien; Shapaval, Volha; Byrtusova, Dana & Andersstuen, Terese [Show all 13 contributors for this article] (2024). Different modes of chromosomal evolution in fungi revealed by long-read sequencing. Full text in Research Archive
• Star, Bastiaan; Jentoft, Sissel; Matschiner, Michael; Nederbragt, Alexander Johan; Kjesbu, Olav Sigurd & Berg, Paul Ragnar [Show all 12 contributors for this article] (2015). Does historic DNA provide genomic evidence for recent selection in Atlantic cod? Full text in Research Archive
• Tørresen, Ole Kristian; Jentoft, Sissel; Star, Bastiaan; Sandve, Geir Kjetil F.; Skage, Morten & Hansen, Marianne Helén Selander [Show all 9 contributors for this article] (2014). A new, high quality reference genome assembly for Atlantic cod. Full text in Research Archive
• Tørresen, Ole Kristian; Walenz, Brian; Grove, Harald; Lien, Sigbjørn; Knight, James & Star, Bastiaan [Show all 15 contributors for this article] (2014). A new, high quality reference genome assembly for Atlantic cod. Full text in Research Archive
• Matschiner, Michael; Star, Bastiaan; Berg, Paul Ragnar; Tørresen, Ole Kristian; Nederbragt, Alexander Johan & Hansen, Marianne Helén Selander [Show all 11 contributors for this article] (2014). Population differentiation and local adaptation in Atlantic cod. Full text in Research Archive
• Nederbragt, Alexander Johan; Tørresen, Ole Kristian; Skage, Morten; Tooming-Klunderud, Ave; Hansen, Marianne Helén Selander & Jentoft, Sissel [Show all 9 contributors for this article] (2012). The long jump: Long distance mate pairs and long PacBio reads for the Salmon Genome Project. Full text in Research Archive
• Star, Bastiaan; Nederbragt, Alexander Johan; Jentoft, Sissel; Grimholt, Unni; Malmstrøm, Martin & Gregers, Tone Fredsvik [Show all 18 contributors for this article] (2011). The genome of Atlantic cod reveals a unique immune system. Full text in Research Archive
• Grimholt, Unni; Malmstrøm, Martin; Nederbragt, Alexander Johan; Rounge, Trine Ballestad; Jentoft, Sissel & Tooming-Klunderud, Ave [Show all 10 contributors for this article] (2009). The lack of cod MHC class II. Full text in Research Archive
• Grimholt, Unni; Nederbragt, Alexander Johan; Rounge, Trine Ballestad; Malmstrøm, Martin; Star, Bastiaan & Tooming-Klunderud, Ave [Show all 12 contributors for this article] (2009). The cod genome project. Full text in Research Archive
• Skage, Morten; Mikkelsen, Nina Therese & Sjøtun, Inga Kjersti (2009). GENETIC SEPARATION OF DIFFERENT ENTITIES OF MASTOCARPUS STELLATUS (STACKHOUSE) GUIRY. Phycologia. ISSN 0031-8884. 48(4), p. 121–122. Full text in Research Archive
• Tooming-Klunderud, Ave; Nederbragt, Alexander Johan; Skage, Morten & Jakobsen, Kjetill Sigurd (2009). The Ultra-high Throughput Sequencing Platform at the University of Oslo. Full text in Research Archive
• Hatteland, Bjørn Arild; Noble, Leslie R; Schander, Christoffer; Skage, Morten; Solhøy, Torstein & Symondson, W. O. C. (2007). Differentiation between the invasive Arion lusitanicus and the native Arion ater in western Norway combining morphology and genetics. Full text in Research Archive
• Schander, Christoffer & Skage, Morten (2006). DNA from formalinized tissue - Extraction or PCR that's the question. Full text in Research Archive
• Skage, Morten & Schander, Christoffer (2006). How to preserve genetic material – the formalin problem. Full text in Research Archive
• Lättman, Håkan; Ekman, Stefan; Lindblom, Louise; Mattsson, Jan-Eric; Milberg, Per & Skage, Morten (2006). Regional occurrence of Cliostomum corrugatum is limited by habitat availability. Full text in Research Archive
• Olseng, Christine; Aarø, Lars; Erga, Svein Rune; Samdal, IA; Skage, Morten & Naustvoll, L..J. [Show all 8 contributors for this article] (2005). Vertical migration, growth, genetics and toxicity among different strains of Norwegian Protoceratium reticulatum (Dinophyceae). Full text in Research Archive
• Skage, Morten; Barth, Julia Maria Isis; Jentoft, Sissel; Øverli, Øyvind & Jakobsen, Kjetill Sigurd (2017). Genetisk bakgrunn hos ulv (Canis lupus) i Norge og Skandinavia. Universitetet i Oslo. Full text in Research Archive Show summary

  Formålet med denne undersøkelsen var å identifisere mulige krysninger mellom hund og ulv i dagens skandinaviske ulvebestand. I tillegg ønsket vi å finne ut i hvor stor grad det er mulig å gjenkjenne innblanding av hund i ulvens arvemateriale (hybridisering og tilbake-krysninger). Metodene som vi har anvendt i undersøkelsen er dyrere og mer tidkrevende enn det dagens forvaltningsmetodikk legger opp til (mikrosatelittanalyse), men gir bedre oppløsning over hele arvemassen og muliggjør deteksjon av svake hybridsignaler. Analysene er basert på data fra hel-genomsekvensering av ulv (dagens skandinaviske bestand og andre ulv), historisk ulv (Nordreisa 1962, Dyrøy 1963, Målselv 1963, og Stor Elvdal 1964), ulvehund (tsjekkisk ulvehund), primitive hunderaser (dingo, basenji, tibetansk mastiff) og moderne hunderaser (boxer etc), alle med ulik geografisk opprinnelse. De norske individene som er sekvensert i denne undersøkelsen kommer alle fra svenske føderevir, men har lagt ut på vandring og blitt avlivet i Norge (Stange, Nord-Odal, Sykkylven, Elverum og Trysil), og inngikk i det som betraktes som en felles skandinavisk bestand. Våre analyser viser: ● Den skandinaviske bestanden grupperer sammen med andre europeiske ulver, og ulver fra Asia, kalt «old world gruppen» i PCA (bilag1) ● Nylig hybridisering mellom ulv og hund ble ikke påvist. ● Genetiske analyser indikerer historisk innblanding av hund i alle analyserte ulver, også i skandinavisk bestand, men det er ikke mer innslag av hund i skandinavisk bestand enn hva som er funnet i andre populasjoner.

View all works in NVA