Proteomics of hyposaline stress in blue mussel congeners (genusMytilus): implications for biogeographic range limits in response to climate change

Abstract

SUMMARYClimate change is affecting speciesʼ physiology, pushing environmental tolerance limits and shifting distribution ranges. In addition to temperature and ocean acidification, increasing levels of hyposaline stress due to extreme precipitation events and freshwater runoff may be driving some of the reported recent range shifts in marine organisms. Using two-dimensional gel electrophoresis and tandem mass spectrometry, we characterized the proteomic responses of the cold-adapted blue mussel Mytilus trossulus, a native to the Pacific coast of North America, and the warm-adapted M. galloprovincialis, a Mediterranean invader that has replaced the native from the southern part of its range, but may be limited from expanding north due to hyposaline stress. After exposing laboratory-acclimated mussels for 4h to two different experimental treatments of hyposaline conditions and one control treatment (24.5, 29.8 and 35.0psu, respectively) followed by a 0 and 24h recovery at ambient salinity (35psu), we detected changes in the abundance of molecular chaperones of the endoplasmic reticulum (ER), indicating protein unfolding, during stress exposure. Other common responses included changes in small GTPases of the Ras superfamily during recovery, which suggests a role for vesicle transport, and cytoskeletal adjustments associated with cell volume, as indicated by cytoskeletal elements such as actin, tubulin, intermediate filaments and several actin-binding regulatory proteins. Changes of proteins involved in energy metabolism and scavenging of reactive oxygen species suggest a reduction in overall energy metabolism during recovery. Principal component analyses of protein abundances suggest that M. trossulus is able to respond to a greater hyposaline challenge (24.5psu) than M. galloprovincialis (29.8psu), as shown by changing abundances of proteins involved in protein chaperoning, vesicle transport, cytoskeletal adjustments by actin-regulatory proteins, energy metabolism and oxidative stress. While proteins involved in energy metabolism were lower in M. trossulus during recovery from hyposaline stress, M. galloprovincialis showed higher abundances of those proteins at 29.8psu, suggesting an energetic constraint in the invader but not the native congener. Both species showed lower levels of oxidative stress proteins during recovery. In addition, oxidative stress proteins associated with protein synthesis and folding in the ER showed lower levels during recovery in M. galloprovincialis, in parallel with ER chaperones, indicating a reduction in protein synthesis. These differences may enable the native M. trossulus to cope with greater hyposaline stress in the northern part of its range, as well as to outcompete M. galloprovincialis in the southern part of M. trossulusʼ range, thereby preventing M. galloprovincialis from expanding further north. Supplementary material available online at

Proteomic responses to environmentally induced oxidative stress

“…A number of recent proteomic studies indeed showed changes in the abundance of either NADH dehydrogenase or cytochrome c reductase isoforms, or both, in gill of several marine invertebrate species in response to acute and chronic temperature and hyposalinity stress (Dilly et al, 2012;Fields et al, 2012b;Tomanek and Zuzow, 2010;Tomanek et al, 2012), suggesting that decreasing abundance, composition or PTM of both complex I and III of the ETS are potential sites for regulation.…”

Mild osmotic stress in intertidal gastropods Littorina saxatilis and Littorina obtusata (Mollusca: Caenogastropoda): a proteomic analysis

“…Together with revealed regulation of several cytoskeletal proteins, controlling cell-shape, it implies the possible tissue remodeling under salinity stress, also inferred earlier. Up-and down-regulation of genes, coding for proteins of cytoskeleton, cell adhesion and extracellular matrix, was also shown to be part of the response to salinity stress in oysters C. gigas and other marine invertebrates (Tomanek et al, 2012;Zhao et al, 2012).…”

“…The participation of heat shock proteins in salinity adaptation has been demonstrated many times in different taxa: protists Amoeba proteus and Paramecium jenningsi (Plekhanov et al, 2006); sponges Tetilla mutabilis (Kültz et al, 2007); corals Seriatopora caliendrum (Seveso et al, 2013); sea cucumbers Apostichopus japonicas (Meng et al, 2011); oysters Crassostrea gigas (Zhao et al, 2012); and mussels Mytilus galloprovincialis, M. trossulus (Tomanek et al, 2012) and M. edulis (Podlipaeva et al, 2012(Podlipaeva et al, , 2016. In our study, heat shock proteins were the only protein group which we revealed as important for low salinity adaptation in both stress types and in both species studied.…”

“…Osmotic stress deeply affects various physiological processes, including those in nervous, immune and other systems (Stucchi-Zucchi and Salomao, 1998;Cheng et al, 2004;Bussell et al, 2008;Jauzein et al, 2013;Honorato et al, 2017). Considerable progress has been made in recent years in our understanding of the molecular background of salinity adaptation (An and Choi, 2010;Hoy et al, 2012;Lockwood and Somero, 2011;Zhao et al, 2012;Tomanek et al, 2012;Meng et al, 2013;Seveso et al, 2013;Carregosa et al, 2014;Muraeva et al, 2016;Gharbi et al, 2016;Yang et al, 2016;Yan et al, 2017). Nevertheless, greater knowledge about the physiological mechanisms of adaptation to salinity variation is still needed, especially in regard to intertidal invertebrates, which deal with osmotic stress throughout their lives.…”

Proteomic identification of germline proteins inCaenorhabditis elegans

“…The peptides were analyzed with a MALDI-TOF/TOF mass spectrometer (Ultraflex II; Bruker Daltonics) as in refs. 33,34 . Peptide mass fingerprints (PMFs) were acquired using with FlexControl software (Bruker Daltonics) and externally calibrated; trypsin peaks were used to calibrate spectra internally.…”