Comparative genomic analysis of *Cristatella mucedo* provides insights into Bryozoan evolution and nervous system function

The modular body organization is an enigmatic feature of different animal phyla scattered throughout the phylogenetic tree.

Here we present a high-quality genome assembly of a fascinating freshwater bryozoan, Cristatella mucedo, making it a first sequenced genome of the phylum Bryozoa. Using PacBio, Oxford Nanopore, and Illumina sequencing, we were able to obtain assembly with N50 of 4.1 Mb.

Comparative genome analysis suggests that, despite larger genome size and higher number of genes, C. mucedo possesses a less diverse set of proteins compared to its immediate relatives. Gene family and pathway overrepresentation analysis were used to find candidate targets involved in bryozoan nervous system and locomotion. We used RNA sequencing to identify genes upregulated in various parts of the colony, as well as during the differentiation from frozen statoblasts, and validated several of these targets using in situ hybridization.

Overall, analysis of the first Bryozoan genome allows important insights into the evolution of nervous system and modular body organization.