The Effects of Live Transport on Metabolism and Stress Responses of Abalone (Haliotis iris)

Contaminants of Concern and Spatiotemporal Metabolomic Changes in Quagga Mussels (Dreissena bugensis rostriformis) from the Milwaukee Estuary (Wisconsin, USA)

Environmental metabolomics has emerged as a promising technique in the field of biomonitoring and as an indicator of aquatic ecosystem health. In the Milwaukee Estuary (Wisconsin, USA), previous studies have used a nontargeted metabolomic approach to distinguish between zebra mussels (Dreissena polymorpha) collected from sites of varying contamination. To further elucidate the potential effects of contaminants on bivalve health in the Milwaukee Estuary, the present study adopted a caging approach to study the metabolome of quagga mussels (Dreissena bugensis rostriformis) deployed in six sites of varying contamination for 2, 5, or 55 days. Caged mussels were co-deployed with two types of passive sampler (polar organic chemical integrative samplers and semipermeable membrane devices) and data loggers. In conjunction, in situ quagga mussels were collected from the four sites studied previously and analyzed for residues of contaminants and metabolomics using a targeted approach. For the caging study, temporal differences in the metabolomic response were observed with few significant changes observed after 2 and 5 days, but larger differences (up to 97 significantly different metabolites) to the metabolome in all sites after 55 days. A suite of metabolic pathways were altered, including biosynthesis and metabolism of amino acids, and upmodulation of phospholipids at all sites, suggesting a potential biological influence such as gametogenesis. In the caging study, average temperatures appeared to have a greater effect on the metabolome than contaminants, despite a large concentration gradient in polycyclic aromatic hydrocarbons residues measured in passive samplers and mussel tissue. Conversely, significant differences between the metabolome of mussels collected in situ from all three contaminated sites and the offshore reference site were observed. Overall, these findings highlight the importance of contextualizing the effects of environmental conditions and reproductive processes on the metabolome of model organisms to facilitate the wider use of this technique for biomonitoring and environmental health assessments. Environ Toxicol Chem 2024;43:307-323. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Metabolic adaptation of the clam Ruditapes philippinarum during air exposure and the positive effects of sodium nitroprusside pretreatment

The Manila clam (Ruditapes philippinarum), as one of the shellfish living in the intertidal zone, is known for its strong ability to withstand air exposure. Sodium nitroprusside (SNP), a donor of nitric oxide (NO), has been shown to be useful for antioxidant and immune regulation in aquatic animals. In this study, an untargeted metabolomics (LC-MS/MS) technique was employed for the first time in Manila clam to analyze the metabolic and histological impacts after air exposure and the positive effects of SNP pretreatment. During air exposure, a significant increase in taurine, L-glutamate, and several polyunsaturated fatty acids in clams was detected, which indicates that clams may experience inflammatory reactions, oxidative stress, and an increase in blood ammonia content. When clams were exposed to SNP for 6 h, arginine, spermine, L-glutamic acid, and glutathione content were all upregulated, indicating that the SNP exposure induced NO production and improved antioxidant capacity in clams. When the clams were exposed to air after SNP pretreatment, there were no significant differences in the levels of taurine, L-glutamate, or aliphatic acids between the experimental and control groups. Gill tissue was more severely damaged in clams directly exposed to air than in those that experienced air exposure after SNP pretreatment, especially in clams exposed to air for a long time (72 h). Both metabolomics and tissue section structure indicated that SNP pretreatment decreased the stress responses caused by air exposure in R. philippinarum. These findings provided fresh insights and a theoretical foundation for understanding the tolerance to air exposure and physiological functions of SNP (or NO) in R. philippinarum.

Gilthead Seabream Liver Integrative Proteomics and Metabolomics Analysis Reveals Regulation by Different Prosurvival Pathways in the Metabolic Adaptation to Stress

The study of the molecular mechanisms of stress appraisal on farmed fish is paramount to ensuring a sustainable aquaculture. Stress exposure can either culminate in the organism's adaptation or aggravate into a metabolic shutdown, characterized by irreversible cellular damage and deleterious effects on fish performance, welfare, and survival. Multiomics can improve our understanding of the complex stressed phenotype in fish and the molecular mediators that regulate the underlying processes of the molecular stress response. We profiled the stress proteome and metabolome of Sparus aurata responding to different challenges common to aquaculture production, characterizing the disturbed pathways in the fish liver, i.e., the central organ in mounting the stress response. Label-free shotgun proteomics and untargeted metabolomics analyses identified 1738 proteins and 120 metabolites, separately. Mass spectrometry data have been made fully accessible via ProteomeXchange, with the identifier PXD036392, and via MetaboLights, with the identifier MTBLS5940. Integrative multivariate statistical analysis, performed with data integration analysis for biomarker discovery using latent components (DIABLO), depicted the 10 most-relevant features. Functional analysis of these selected features revealed an intricate network of regulatory components, modulating different signaling pathways related to cellular stress, e.g., the mTORC1 pathway, the unfolded protein response, endocytosis, and autophagy to different extents according to the stress nature. These results shed light on the dynamics and extent of this species' metabolic reprogramming under chronic stress, supporting future studies on stress markers' discovery and fish welfare research.

Changes in metabolic profiling of whiteleg shrimp (Penaeus vannamei) under hypoxic stress

Hypoxia is a common concern in shrimp aquaculture, affecting growth and survival. Although recent studies have revealed important insights into hypoxia in shrimp and crustaceans, knowledge gaps remain regarding this stressor at the molecular level. In the present study, a gas chromatography-mass spectrometry (GC-MS)-based metabolomics approach was employed to characterize the metabolic signatures and pathways underlying responses of Pacific white shrimp (Penaeus vannamei) to hypoxia and to identify associated candidate biomarkers. We compared metabolite profiles of shrimp haemolymph before (0 h) and after exposure to hypoxia (1 & 2 h). Dissolved oxygen levels were maintained above 85 % saturation in the control and before hypoxia, and 15 % saturation in the hypoxic stress treatment. Results showed 44 metabolites in shrimp haemolymph that were significantly different between before and after hypoxia exposure. These metabolites were energy-related metabolites (e.g., intermediates of citric acid cycle, lactic acid, alanine), fatty acids and amino acids. Pathway analysis revealed 17 pathways that were significantly affected by hypoxia. The changes in metabolites and pathways indicate a shift from aerobic to anaerobic metabolism, disturbance in amino acid metabolism, osmoregulation, oxidative damage and Warburg effect-like response caused by hypoxic stress. Among the altered metabolites, lactic acid was most different between before and after hypoxia exposure and had the highest accurate value for biomarker identification. Future investigations may validate this molecule as a stress biomarker in aquaculture. This study contributes to a better understanding of hypoxia in shrimp and crustaceans at the metabolic level and provides a base for future metabolomics investigations on hypoxia.

Metabolite profiling of abalone (Haliotis iris) energy metabolism: a Chatham Islands case study

INTRODUCTION

The Chatham Islands has some of the most prized black-footed abalone (Haliotis iris) beds in New Zealand. This well-managed fishery includes restrictions on catch and size limits, selective fishing methods, and shellfish management. However, recent declines in biomass and growth parameters have prompted omics research to characterise the biological responses of abalone, potentially contributing towards animal management strategies.

OBJECTIVES

The aim of this study was to characterise the metabolite profiles of slow and fast growing, juvenile and adult abalone, relating to metabolites supporting energy metabolism.

METHODS

A gas chromatography-mass spectrometry metabolite profiling, applying methyl chloroformate alkylation, was performed on juvenile and adult abalone samples collected from Point Durham and Wharekauri sites, Chatham Islands, New Zealand.

RESULTS

The results obtained from haemolymph and muscle samples indicated that abalone from the fast-growing area, Wharekauri, fuelled metabolic functions via carbohydrate sources, providing energy for fatty acid and amino acid synthesis. Conversely, higher amino acid levels were largely utilised to promote growth in this population. The metabolism of juvenile abalone favoured anabolism, where metabolites were diverted from glycolysis and the tricarboxylic acid cycle, and used for the production of nucleotides, amino acids and fatty acids.

CONCLUSIONS

This research provides unique physiological insights towards abalone populations supporting the use of metabolomics as a tool to investigate metabolic processes related to growth. This work sets the stage for future work aimed at developing biomarkers for growth and health monitoring to support a growing and more sustainably abalone fishery.

Investigating the biochemical effects of heat stress and sample quenching approach on the metabolic profiling of abalone (Haliotis iris)

INTRODUCTION

Ocean temperatures have been consistently increasing due to climate change, and the frequency of heatwave events on shellfish quality is a growing concern worldwide. Typically, shellfish growing areas are in remote or difficult to access locations which makes in-field sampling and sample preservation of shellfish heat stress difficult. As such, there is a need to investigate in-field sampling approaches that facilitate the study of heat stress in shellfish.

OBJECTIVES

This study aims to apply a gas chromatography-mass spectrometry (GC-MS) based metabolomics approach to examine molecular mechanisms of heat stress responses in shellfish using abalone as a model, and compare the effects of different quenching protocols on abalone metabolic profiles.

METHODS

Twenty adult Haliotis iris abalone were exposed to two temperatures (14 °C and 24 °C) for 24 h. Then, haemolymph and muscle tissues of each animal were sampled and quenched with 4 different protocols (liquid nitrogen, dry ice, cold methanol solution and normal ice) which were analyzed via GC-MS for central carbon metabolites.

RESULTS

The effects of different quenching protocols were only observed in muscle tissues in which the cold methanol solution and normal ice caused some changes in the observed metabolic profiles, compared to dry ice and liquid nitrogen. Abalone muscle tissues were less affected by thermal stress than haemolymph. There were 10 and 46 compounds significantly influenced by thermal stress in muscle and haemolymph, respectively. The changes of these metabolite signatures indicate oxidative damage, disturbance of amino acid and fatty acid metabolism, and a shift from aerobic metabolism to anaerobic pathways.

CONCLUSIONS

The study provided insights into the heat response of abalone, which could be useful for understanding the effects of marine heatwaves and summer mortality events on abalone. Dry ice appeared to be a suitable protocol, and safer in-field alternative to liquid nitrogen, for quenching of abalone tissues.