# Comprehensive Analysis of Metabolome and Transcriptome Reveals Physiological Processes Related to Larval Development of Barnacles (Megabalanus volcano)

## TL;DR

This study explores how barnacles develop by analyzing their metabolism and gene activity during key life stages, revealing important biological processes.

## Contribution

The study provides new insights into the metabolic and gene regulatory mechanisms driving barnacle larval development.

## Key findings

- Bile secretion pathway is central to early development stages of barnacles.
- Wnt signaling pathway genes are active in cyprid larvae, while chitin metabolism genes are key in nauplius larvae.
- Transcriptomic analysis identified 7234 differentially expressed genes across developmental stages.

## Abstract

Scientists need to understand how barnacles develop because these small marine organisms are a type of harmful fouling organism; they attach to ships, marine infrastructure, and aquaculture facilities, causing huge economic losses. Barnacles have a complex life cycle, and the transformation from their nauplius larval stage to cyprid larval stage is key, but the biological processes behind this are not well known. This study used two scientific methods—metabolome and transcriptome analysis—to look at three key developmental stages of the barnacle Megabalanus volcano: embryo, nauplius larva, and cyprid larva. The research identified 3683 distinct metabolites and 7234 genes with altered activity across different stages. The bile secretion pathway was central to all early development stages, helping with lipid digestion and mineral absorption for the barnacles’ shape changes. The study also identified gene sets associated with each stage; for instance, genes related to the Wnt signaling pathway are active in cyprids, while chitin metabolism genes play a key role in nauplius. These findings help us understand how barnacles grow and adapt to their environment.

Background: Barnacles are important marine fouling organisms, and their complex life cycle involves key metamorphic nodes from nauplius to cyprid larvae and then to sessile adults. However, the molecular mechanisms underlying their larval development remain poorly understood. Metabolomics and transcriptomics are powerful tools for exploring biological development pathways and regulatory networks. Methods: We employed non-targeted metabolomics and transcriptomics to analyze three key developmental stages of embryonic stage, nauplius stage, and cyprid stage. Differential metabolites were screened using fold change (FC), p-value, and variable importance in projection (VIP) values, while DEGs were identified with adjusted p-value and |log2(fold change)| criteria. WGCNA was used to construct gene co-expression networks, and qRT-PCR validated RNA-seq results. Results: A total of 3683 metabolites were identified, with the bile secretion pathway serving as a core regulatory pathway throughout early development. Transcriptomic analysis identified 7234 DEGs, which were clustered into four modules corresponding to different developmental stages. Key pathways such as chitin metabolism, and linoleic acid metabolism were significantly enriched, and qRT-PCR confirmed the reliability of RNA-seq data. Conclusions: This study reveals the metabolic and molecular regulatory mechanisms underlying the early development of M. volcano, highlighting stage-specific metabolic characteristics and core gene modules. The findings provide a theoretical basis for understanding barnacle developmental adaptation strategies and offer potential targets for the development of novel antifouling agents.