PT  - JOURNAL ARTICLE
AU  - Zhe Qu
AU  - Wenyan Nong
AU  - Wai Lok So
AU  - Tom Barton-Owen
AU  - Yiqian Li
AU  - Chade Li
AU  - Thomas C.N. Leung
AU  - Tobias Baril
AU  - Annette Y.P. Wong
AU  - Thomas Swale
AU  - Ting-Fung Chan
AU  - Alexander Hayward
AU  - Sai-Ming Ngai
AU  - Jerome H.L. Hui
TI  - Millipede genomes reveal unique adaptation of genes and microRNAs during myriapod evolution
AID  - 10.1101/2020.01.09.900019
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.01.09.900019
4099  - http://biorxiv.org/content/early/2020/01/09/2020.01.09.900019.short
4100  - http://biorxiv.org/content/early/2020/01/09/2020.01.09.900019.full
AB  - The Myriapoda including millipedes and centipedes is of major importance in terrestrial ecology and nutrient recycling. Here, we sequenced and assembled two chromosomal-scale genomes of millipedes Helicorthomorpha holstii (182 Mb, N50 18.11 Mb mainly on 8 pseudomolecules) and Trigoniulus corallinus (449 Mb, N50 26.78 Mb mainly on 15 pseudomolecules). Unique defense systems, genomic features, and patterns of gene regulation in millipedes, not observed in other arthropods, are revealed. Millipedes possesses a unique ozadene defensive gland unlike the venomous forcipules in centipedes. Sets of genes associated with anti-microbial activity are identified with proteomics, suggesting that the ozadene gland is not primarily an antipredator adaptation (at least in T. corallinus). Macro-synteny analyses revealed highly conserved genomic blocks between centipede and the two millipedes. Tight Hox and the first loose ecdysozoan ParaHox homeobox clusters are identified, and a myriapod-specific genomic rearrangement including Hox3 is also observed. The Argonaute proteins for loading small RNAs are duplicated in both millipedes, but unlike insects, an argonaute duplicate has become a pseudogene. Evidence of post-transcriptional modification in small RNAs, including species-specific microRNA arm switching that provide differential gene regulation is also obtained. Millipede genomes reveal a series of unique genomic adaptations and microRNA regulation mechanisms have occurred in this major lineage of arthropod diversity. Collectively, the two millipede genomes shed new light on this fascinating but poorly understood branch of life, with a highly unusual body plan and novel adaptations to their environment.