# Functional and evolutionary diversification of luciferase genes in Metridia lucens Boeck 1865

## TL;DR

This study explores the evolution and diversity of luciferase genes in the copepod Metridia lucens, revealing multiple gene lineages that contribute to bioluminescence.

## Contribution

The study identifies three distinct luciferase gene lineages in Metridia lucens, expanding understanding of marine bioluminescence evolution.

## Key findings

- M. lucens exhibits unexpectedly high luciferase gene diversity within and between specimens.
- Three distinct luciferase gene lineages were identified, each with multiple copies.
- The findings suggest an extended luciferase gene family in the copepod's genome.

## Abstract

Bioluminescent organisms have developed extraordinary adaptations to produce light using a luciferin-luciferase reaction, fulfilling various ecological functions such as predator evasion, prey attraction, and intraspecies communication. Although the earliest record in the marine environment dates back some 540 millions of years, the evolutionary origins of this phenomenon are still largely unknown in most species. In Metridinidae copepods light production capability is facilitated by a luciferase gene duplication. This study focuses on characterizing the luciferase genes of Metridia lucens, a copepod widely distributed throughout global oceans, excluding the high Arctic. Despite being the first described species in this genus, the genomic sequences of its luciferase genes remained unknown prior to this investigation. Here, using an integrated approach combining molecular cloning and high-throughput sequencing, we isolated and characterized M. lucensluciferase genes. Our results revealed an unexpectedly high genetic diversity both within and between specimens, consistent with the presence of an extended gene family in this copepod’s genome. We identified three distinct luciferase gene lineages, each represented by several copies, expanding our knowledge of marine bioluminescence evolution.