RESUMEN
Whether shellfish mariculture should be included in the blue carbon profile as a strategy to combat climate change has been controversial. It is highly demanding not only to provide calibration quantitation, but also to provide an ecosystem-based mechanism. In this study, we chose mussel farms as a case study to evaluate their contributions to carbon sinks and their responses to sedimentary carbon fixation and sequestration. First, we quantified the air-sea CO2 flux in the mussel aquacultural zone and observed a weak carbon sink (-0.15 ± 0.07 mmol·m-2·d-1) during spring. Next, by analyzing the carbon composition in the sediment, we recorded a noticeable and unexpected increase in the sedimentary recalcitrant carbon (RC) content in the mussel farming case. To address this surprising sedimentary phenomenon, a long-term indoor experimental test was conducted to distinguish the consequences of mussel engagement with sedimentary RC. Our observational data support the idea that mussel engagement promotes accumulation of RC in sediments by 2.5-fold. Furthermore, the relative intensity of carboxylic-rich alicyclic molecule (CRAM)-like compounds (recalcitrant dissolved organic matter (RDOM)) increased by 451.4 % in the mussel-engaged sedimentary dissolved organic matter (DOM) in comparison to the initial state. Mussel engagement had a significantly positive effect on the abundance of sedimentary carbon-fixing genes. Therefore, we definitively conclude that mussel farming is blue carbon positive and propose a new alternative theory that mussel farming areas may have high carbon sequestration potential via an ecologically integrated "3 M" (microalgae-mussel-microbiota) consortium. The "mussel pump" accelerates carbon sequestration and enhances climate-related ecosystem services.
Asunto(s)
Secuestro de Carbono , Mariscos , Animales , Cambio Climático , Monitoreo del Ambiente , Acuicultura , Sedimentos Geológicos/química , Bivalvos/metabolismo , Océanos y Mares , Ecosistema , Carbono/análisisRESUMEN
Histones and their N-terminal or C-terminal derived peptides have been studied in vertebrates and presented as potential antimicrobial agents playing important roles in the innate immune defenses. Although histones and their derived peptides had been reported as components of innate immunity in invertebrates, the knowledge about the histone derived antimicrobial peptides (HDAPs) in invertebrates are still limited. Using a peptidomic technique, a set of peptide fragments derived from the histones was identified in this study from the serum of microbes challenged Mytilus coruscus. Among the 85 identified histone-derived-peptides with high confidence, 5 HDAPs were chemically synthesized and the antimicrobial activities were verified, showing strong growth inhibition against Gram-positive bacteria, Gram-negative bacteria, and fungus. The gene expression level of the precursor histones matched by representative HDAPs were further tested using q-PCR, and the results showed a significant upregulation of the histone gene expression levels in hemocytes, gill, and mantle of the mussel after immune stress. In addition, three identified HDAPs were selected for preparation of specific antibodies, and the corresponding histones and their derived C-terminal fragments were detected by Western blotting in the blood cell and serum of immune challenged mussel, respectively, indicating the existence of HDAPs in M. coruscus. Our findings revealed the immune function of histones in Mytilus, and confirmed the existence of HDAPs in the mussel. The identified Mytilus HDAPs represent a new source of immune effector with antimicrobial function in the innate immune system, and thus provide promising candidates for the treatment of microbial infections in aquaculture and medicine.
Asunto(s)
Péptidos Antimicrobianos , Histonas , Inmunidad Innata , Mytilus , Animales , Mytilus/inmunología , Mytilus/genética , Histonas/inmunología , Histonas/genética , Péptidos Antimicrobianos/farmacología , Péptidos Antimicrobianos/genética , Péptidos Antimicrobianos/química , Inmunidad Innata/genética , Bacterias Gramnegativas/fisiología , Bacterias Gramnegativas/efectos de los fármacosRESUMEN
Mytilus coruscus is an economically important marine bivalve that lives in estuarine sea areas with seasonal coastal acidification and frequently suffers shell injury in the natural environment. However, the molecular responses and biochemical properties of Mytilus under these conditions are not fully understood. In the present study, we employed tandem mass spectrometry combined with isobaric tagging to identify differentially expressed proteins in the mantle tissue of M. coruscus under different short-term treatments, including shell-complete mussels raised in normal seawater (pH 8.1), shell-damaged mussels raised in normal seawater (pH 8.1), and acidified seawater (pH 7.4). A total of 2694 proteins were identified in the mantle, and analysis of their relative abundance from the three different treatments revealed alterations in the proteins involved in immune regulation, oxidation-reduction processes, protein folding and processing, energy provision, and cytoskeleton. The results obtained by quantitative proteomic analysis of the mantle allowed us to delineate the molecular strategies adopted by M. coruscus in the shell repair process in acidified environments, including an increase in proteins involved in oxidation-reduction processes, protein processing, and cell growth at the expense of proteins involved in immune capacity and energy metabolism. SIGNIFICANCE: The impact of global ocean acidification on calcifying organisms has become a major ecological and environmental problem in the world. Mytilus coruscus is an economically important marine bivalve living in estuary sea area with seasonal coastal acidification, and frequently suffering shell injury in natural environment. Molecular responses of M coruscus under the shell damage and acute acidification is still largely unknown. For this reason, iTRAQ based quantitative proteomic and histological analysis of the mantle from M. coruscus under shell damage and acute acidification were performed, for revealing the proteomic response and possible adaptation mechanism of Mytilus under combined shell damage and acidified sea water, and understanding how the mussel mantle implement a shell-repair process under acidified sea water. Our study provides important data for understanding the shell repair process and proteomic response of Mytilus under ocean acidification, and providing insights into potential adaptation of mussels to future global change.
Asunto(s)
Mytilus , Agua de Mar , Animales , Agua de Mar/química , Mytilus/fisiología , Concentración de Iones de Hidrógeno , Proteómica , Metabolismo EnergéticoRESUMEN
Mytilus coruscus is an economically important marine bivalve mollusk found in the Yangtze River estuary, which experiences dramatic pH fluctuations due to seasonal freshwater input and suffer from shell fracture or injury in the natural environment. In this study, we used intact-shell and damaged-shell M. coruscus and performed metabolomic analysis, free amino acids analysis, calcium-positive staining, and intracellular calcium level tests in the mantle to investigate whether the mantle-specific metabolites can be induced by acute sea-water acidification and understand how the mantle responds to acute acidification during the shell repair process. We observed that both shell damage and acute acidification induced alterations in phospholipids, amino acids, nucleotides, organic acids, benzenoids, and their analogs and derivatives. Glycylproline, spicamycin, and 2-aminoheptanoic acid (2-AHA) are explicitly induced by shell damage. Betaine, aspartate, and oxidized glutathione are specifically induced by acute acidification. Our results show different metabolic patterns in the mussel mantle in response to different stressors, which can help elucidate the shell repair process under ocean acidification. furthermore, metabolic processes related to energy supply, cell function, signal transduction, and amino acid synthesis are disturbed by shell damage and/or acute acidification, indicating that both shell damage and acute acidification increased energy consumption, and disturb phospholipid synthesis, osmotic regulation, and redox balance. Free amino acid analysis and enzymatic activity assays partially confirmed our findings, highlighting the adaptation of M. coruscus to dramatic pH fluctuations in the Yangtze River estuary.