# Draft genome of the endemic alpine ground beetle Carabus (Platycarabus) depressus (Coleoptera: Carabidae) from long-read sequencing of a frozen archived specimen

## TL;DR

Researchers successfully sequenced the genome of an alpine beetle using a frozen archived specimen, showing that such preserved samples can be used for high-quality genomic studies.

## Contribution

Demonstrates the feasibility of using frozen archived specimens for long-read genome sequencing in nonmodel organisms.

## Key findings

- Produced a genome with 98% completeness using a frozen archived beetle specimen.
- Achieved a moderate N50 of 945 kb despite DNA fragmentation from preservation.
- This is the second genome for the genus Carabus, expanding genomic resources for the group.

## Abstract

The rapid advancement of genomic technologies has enabled the production of highly contiguous reference genomes for nonmodel organisms. However, these methods often require exceptionally fresh material containing unfragmented high-molecular-weight nucleic acids. Researchers who preserve field-collected specimens in ethanol at ambient temperatures, prior to transferring them to long-term frozen archives, face challenges in applying advanced genomic approaches due to DNA and RNA fragmentation under suboptimal preservation conditions. To explore the potential of such preserved specimens as sources of reference genomes, we utilized Nanopore MinION technology to generate genomic data from a frozen archived specimen of the endemic alpine ground beetle Carabus (Platycarabus) depressus. Using a rapid in-house protocol for high-molecular-weight DNA extraction, followed by sequencing on a single flow cell, we produced 8.75 million raw reads with an N50 of 2.8 kb. The resulting assembly achieved remarkable completeness, recovering up to 98% of Benchmarking Universal Single-Copy Orthologs genes, despite a moderate N50 of 945 kb. This genome is only the second available for the taxonomically diverse genus Carabus, demonstrating the feasibility of using short-to-long-read sequencing on frozen archived specimens commonly housed in natural history collections. These findings open new avenues for advancing nonmodel organism genomics and its downstream applications.