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The Beginning of the End: A Chromosomal Assembly of the New World Malaria Mosquito Ends with a Novel Telomere

Chromosome level assemblies are accumulating in various taxonomic groups including mosquitoes. However, even in the few reference-quality mosquito assemblies, a significant portion of the heterochromatic regions including telomeres remain unresolved. Here we produce a de novo assembly of the New Wor...

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Detalles Bibliográficos
Autores principales: Compton, Austin, Liang, Jiangtao, Chen, Chujia, Lukyanchikova, Varvara, Qi, Yumin, Potters, Mark, Settlage, Robert, Miller, Dustin, Deschamps, Stéphane, Mao, Chunhong, Llaca, Victor, Sharakhov, Igor V., Tu, Zhijian
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Genetics Society of America 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534423/
https://www.ncbi.nlm.nih.gov/pubmed/32883756
http://dx.doi.org/10.1534/g3.120.401654
Descripción
Sumario:Chromosome level assemblies are accumulating in various taxonomic groups including mosquitoes. However, even in the few reference-quality mosquito assemblies, a significant portion of the heterochromatic regions including telomeres remain unresolved. Here we produce a de novo assembly of the New World malaria mosquito, Anopheles albimanus by integrating Oxford Nanopore sequencing, Illumina, Hi-C and optical mapping. This 172.6 Mbps female assembly, which we call AalbS3, is obtained by scaffolding polished large contigs (contig N50 = 13.7 Mbps) into three chromosomes. All chromosome arms end with telomeric repeats, which is the first in mosquito assemblies and represents a significant step toward the completion of a genome assembly. These telomeres consist of tandem repeats of a novel 30-32 bp Telomeric Repeat Unit (TRU) and are confirmed by analyzing the termini of long reads and through both chromosomal in situ hybridization and a Bal31 sensitivity assay. The AalbS3 assembly included previously uncharacterized centromeric and rDNA clusters and more than doubled the content of transposable elements and other repetitive sequences. This telomere-to-telomere assembly, although still containing gaps, represents a significant step toward resolving biologically important but previously hidden genomic components. The comparison of different scaffolding methods will also inform future efforts to obtain reference-quality genomes for other mosquito species.