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Towards the construction of avian chromosome assemblies

Damas, J, Farré, Marta, Lithgow, Pamela, Romanov, Michael N, Li, C, Griffin, Darren K., Larkin, Denis M (2014) Towards the construction of avian chromosome assemblies. In: 20th International Chromosome Conference, 1-4 September 2014, Canterbury, Kent, UK. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:46701)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided.


The advent of the next generation sequencing (NGS) made sequencing and scaffolding of an entire animal genome a routine procedure. As the result we face a fast increase in the number of animal genomes available due to the activities of large international genome sequencing initiatives e.g., Genome 10K (G10K) or smaller projects. However, the full informative power of a sequenced genome could only be achieved when it is assembled into chromosomes. Usually, a draft or nearly complete animal chromosome assembly is achieved through three steps: (i) constructing contigs based on read overlaps, (ii) merging contigs into scaffolds using pair-end reads, and (iii) mapping scaffolds on chromosomes with the use of physical or genetic maps. As the cost of mapping techniques is still much higher than sequencing, the genetic and physical maps are not available for the majority of the de novo sequenced genomes. To overcome this problem for assemblies that employ long-insert libraries (5 – 40 Kbp) we recently developed the reference-assisted chromosome assembly (RACA) algorithm (Kim et al., 2013). This method relies on both the raw sequencing data (reads) and comparative information; the latter is obtained from alignments between the target (de novo sequenced), a closely related (reference) and more distantly related (outgroup) genomes.

Using RACA followed by the manual FISH or PCR verification steps we are reconstructing the chromosome organisation of 19 bird species sequenced by the G10K community. We use the publically available chicken (Gallus gallus) and zebra finch (Taeniopygia guttata) chromosome assemblies as either reference or outgroup for each reconstruction depending on their phylogenetic relationships with each target species. Initially, we established the optimal RACA parameters for a bird chromosome assembly reconstruction using the duck (Anas platyrhynchos) and budgerigar (Melopsittacus undulatus) super-scaffolds assembled with the support from physical maps. This step allowed us to test the reliability of RACA reconstructions for bird genomes. Due to a higher evolutionary conservation of the bird karyotype compared to the mammalian one, we have achieved ~97% accuracy of scaffold adjacencies in our predicted chromosome fragments compared to the ~93-96% accuracies reported for mammals (Kim et al., 2013). We detected ~4-28% of scaffolds in different target bird genomes that are either chimeric or containing genuine lineage-specific evolutionary breakpoint regions. Some of these scaffolds will be selected for follow up PCR or FISH verifications. All RACA reconstructions will become publicly available from our Evolution Highway comparative chromosome browser and will be further utilised to study connections between the chromosome evolution, adaptation and phenotypic diversity in birds and other vertebrates.

Item Type: Conference or workshop item (Paper)
Uncontrolled keywords: evolutionary and comparative cytogenetics; biochemistry & molecular biology; genetics & heredity
Subjects: Q Science > QH Natural history > QH426 Genetics
Divisions: Divisions > Division of Natural Sciences > Biosciences
Depositing User: Mike Romanov
Date Deposited: 15 Jan 2015 14:14 UTC
Last Modified: 17 Aug 2022 10:58 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

Farré, Marta.

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Lithgow, Pamela.

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Romanov, Michael N.

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Griffin, Darren K..

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