# Genome Assembly of Arctica islandica, the Longest-Lived Non-Colonial Animal Species

## TL;DR

Scientists sequenced the genome of the ocean quahog, a clam that can live over 500 years, to study the genetic basis of extreme longevity.

## Contribution

This is the first high-quality genome assembly of Arctica islandica, the longest-lived non-colonial animal species.

## Key findings

- The genome is 1781.15 Mbps in size with high completeness and accuracy.
- The gene set includes 39,509 genes, most of which are annotated and include various non-coding RNAs.
- The genome assembly provides a foundation for studying the molecular basis of extreme longevity in bivalve species.

## Abstract

Only a few dozen of the animal species on Earth can live for more than 100 years. The longest-lived animal is the ocean quahog, also known as the mahogany clam, which can live for more than 500 years. We determined the DNA sequence of the ocean quahog genome. Knowing the sequence of the longest-lived animal will allow for the comparison of its genome against long- and short-lived animals to identify the genes and pathways associated with a long life span.

We report the first high-quality genome-wide assembly for Arctica islandica, the longest-lived non-colonial species, with a reported maximum life span of 507 years. The genome was assembled using short- and long-read DNA sequencing and RNA sequencing of four tissues. All assessment approaches indicated that the assembled genome is complete, contiguous, and accurate. The genome size is estimated at 1781.15 million base pairs (Mbps) with a coverage of 247.8×. The heterozygous rate was 1.15% and the repeat content 67.66%. Genome completeness evaluated by complete BUSCOs was 92.7%. The non-redundant gene set consisted of 39,509 genes with an average transcript length of 15,429 bp. More than 98% of the genes could be annotated across databases. Predicted non-coding RNAs included 801 miRNAs, 11,114 tRNAs, 909 rRNAs, and 349 snRNAs. The Arctica islandica genome, along with the assembly of genomes from other clam species, sets the stage for elucidating the molecular basis for the convergence of extreme longevity across these bivalve species.