# Genetic Features of the Scuticociliate Pathogen Philaster sp. Isolate FWC2 That Causes Sea Urchin Mass Mortality

## TL;DR

This paper studies a scuticociliate pathogen causing sea urchin deaths and reports genetic features of the organism.

## Contribution

The study provides new genetic data on a scuticociliate pathogen linked to sea urchin mass mortality.

## Key findings

- The haploid genome size of Philaster sp. isolate FWC2 is estimated at 122–136 Mbp.
- A 41,396 bp mitochondrial genome with 24 protein-coding genes was assembled.
- A β-PKA protein homolog potentially involved in host infection was identified.

## Abstract

A scuticociliate most closely related to Philaster apodigitiformis caused mass mortalities of diadematoid sea urchins and was cultured as Philaster sp. isolate FWC2. We sequenced the metagenomic content of this isolate, which was predicted to represent ≤ 56% of the complete genome. Based on k‐mer counts, the haploid genome size was predicted to be 122–136 Mbp. We assembled and annotated a 4,088 bp nuclear ribosomal operon, a 41,396 bp mitochondrial genome with 19.22% G + C content, 24 protein‐coding genes, 6 tRNA genes, and 2 rRNA genes, and a protein sequence homologous to β‐PKA in Philaster apodigitiformis potentially involved in host infection.