Integrated transcriptomic and functional immunological approach for assessing the invasiveness of bivalve alien species

A Romero,R Aranguren,B Novoa,A Figueras,R Moreira

doi:10.1016/j.fsi.2019.04.274

Abstract

Biological invasions started when humans moved species beyond their normal geographic limits. Bivalves are the most notoriously invasive species in subtidal aquatic environments. Next-generation sequencing technologies are applied to understand the molecular mechanisms involved in the invasion. The ecological immunology focuses on the role of immunity in invasion, and its magnitude could help to predict the invasiveness of alien species. A remarkable case of invasion has been reported in the Ria de Vigo (Spain) by the black pygmy mussel Xenostrobus securis. In Galicia, the Mediterranean mussel Mytilus galloprovincialis is the predominant cultured bivalve species. Can we predict the invasiveness of alien bivalve species by analyzing their immune response? Can X. securis represent a risk for the autochthonous mussel? We evaluated the suitability of the immune-related hypotheses in our model by using an integrated transcriptomic and functional immunological approach. Our analysis suggests lower immune capabilities in X. securis compared to M. galloprovincialis, probably due to the relocation of energetic resources from the immune response to vital physiological processes to cope with salinity stress. This multidisciplinary approach will help us understand how the immune response can be influenced by the adaptive process and how this immune response can influence the invasion process.

Highlights

Biological invasions started when humans moved species beyond their normal geographic limits
The RNA sequencing of mantle generated 123,478 million reads for X. securis, and 111,322 million reads were used for M. galloprovincialis
The transcriptome of X. securis was significantly enriched in 134 processes, and 75% of the 40 most significant processes were involved in 3 main physiological functions: osmoregulation, metabolism, and regulation of the cell cycle (e.g., G1 phase, S phase, prophase, prometaphase and anaphase)

Summary

Introduction

Biological invasions started when humans moved species beyond their normal geographic limits. The “evolution of increased competitive ability (EICA) hypothesis” postulates that the invaders, in the absence of natural enemies, reallocate energetic resources from unnecessary defense mechanisms into fitness and growth[9] This may lead the invasive species to be more vulnerable to re-infections and novel parasites[10]. Next-generation sequencing (NGS) technologies are being applied to understand the molecular mechanisms involved in the invasion process and to monitor and manage biological invasions[12,13] Those studies resulted in the identification of several pathways responsible for the adaptation of the alien species to a broad range of physiological and biotic challenges when colonizing novel environments. The Mediterranean mussel M. galloprovincialis is the predominant autochthonous bivalve species in Galicia, and its culture is a very important economic resource in the area. Because of the high production of M. galloprovincialis in Galicia, the true potential of the alien X. securis to colonize areas where Mediterranean mussel is established is an important issue that must be analyzed in detail

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