Extreme conditions require extreme actions. And this is what the midge Belgica antarctica has done. The midge lives exclusively in the Antarctic and in order to survive shrinked its genome to the smallest possible size. As of today, this is the smallest insect genome that has been sequenced.
Kelley et. al. now sequenced the genome of Belgica antarctica with the aim to learn more about how insects in general can adapt to the most extreme conditions.
What was sequenced?
Two fourth instar larva (Belgica antarctica) collected near Palmer Station, Antarctica.
Sequencing strategy: Whole genome sequencing & RNA-sequencing
- Libraries & Sequencing: 1 channel 2x 100 bp Illumina HiSeq 2000 (SG library (400 bp insert)) and one SMRT-cell of a 10 kb fragment library on PacBio RSII (P4 DNA Polymerase)
- Data output: 92 M paired-end reads from the shotgun sequencing with Illumina. These resulted in 5,422 contigs. Using the paired-end RNA-Seq data the number of contigs has been reduced to 5,064. Genome coverage with Illumina sequencing ~ 100x.
- Results: The total genome is ~ 99 Mbp.
For the PacBio sequencing a second larvae was used. But due to the low input of genomic DNA the PacBio data yielded only in a modest improvement in assembly. This underlines the need of a long-read sequencing technology with low input DNA material.
The de novo sequencing of the midge Belgica antarctica revealed that the smalll genome size is achieved by a reduction in repeats, TEs and intron size.
Read the complete publication here.
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