Transcriptomics,Genomics

Dataset Information

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Transcriptomic responses to heat-stress in invasive and native blue mussels (genus Mytilus)


ABSTRACT: [original Title] Transcriptomic responses to heat-stress in invasive and native blue mussels (genus Mytilus): molecular correlates of invasive success. Invasive species are increasingly prevalent in marine ecosystems worldwide. Although many studies have examined the ecological effects of invasives, little is known about physiological mechanisms that might contribute to invasive success. The mussel Mytilus galloprovincialis, a native of the Mediterranean Sea, is a successful invader on the central and southern coasts of California, where it has largely displaced the native congener, Mytilus trossulus. It has been previously shown that thermal responses of several physiological traits may underlie the capacity of M. galloprovincialis to out-compete M. trossulus in warm habitats. To elucidate possible differences in stress-induced gene expression between these congeners, we developed an oligonucleotide microarray with 8,874 probes representing 4,488 different genes that recognized mRNAs of both species. In acute heat-stress experiments, 1,531 of these genes showed temperature-dependent changes in gene expression that were highly similar in the two congeners. In contrast, 96 genes showed species-specific responses to heat-stress, functionally characterized by their involvement in oxidative stress, proteolysis, energy metabolism, ion transport, cell signaling, and cytoskeletal reorganization. The gene that showed the biggest difference between the species was the gene for the molecular chaperone small heat shock protein 24, which was highly induced in M. galloprovincialis and showed only a small change in M. trossulus. These different responses to acute heat-stress may help to explain—and predict—the invasive success of M. galloprovincialis in a warming world. Overall design: Two species (Mytilus galloprovincialis, Mytilus trossulus), heat ramp with three treatment groups (24, 28, 32 degrees-C), three control groups sampled at the same time as treatment groups (13 degrees-C), one control group sampled at the beginning (13 degrees-C). Biological replicates: 6 in each treatment group, 6 in each control group. Heterologous and homologous hybridization to microarray constructed from Mytilus californianus and Mytilus galloprovincialis sequences. To accurately compare the transcriptomes of Mytilus galloprovincialis and M. trossulus, we chose to develop a common microarray format that could be used for both species. This microarray design consisted of probe sequences generated from the out-group species, M. californianus. M. trossulus and M. galloprovincialis are approximately 7.6 million years diverged from M. californianus, yet only 3.5 million years divergent from each other (Seed, 1992). Therefore, heterologous hybridization to the microarray allowed us to compare transcriptional responses of M. galloprovincialis and M. trossulus without the inherent sequence biases that would result from a microarray that was designed from sequences of either M. galloprovincialis or M. trossulus. A limited number of sequences (556) from ESTs from M. galloprovincialis that matched M. californianus ESTs were included on the microarray to test for the effects of sequence mismatches. To further control for sequence biases only probes that performed well for both M. galloprovincialis and M. trossulus were used in our analyses. In order to determine significant changes in expression, we conducted a two-way ANOVA, in which temperature and species were modeled as fixed effects, and focused on genes that were significant for the temperature effect or the species x temperature interaction. We ignored the species term from the ANOVA as this effect could have highlighted genes that differentially bound to probes on the microarray due to differences in sequence homology, thus not reflecting true differences in gene expression. In accordance with statistical convention, all genes with a significant species x temperature interaction were deemed not to have significant temperature effects, even if the temperature term from the ANOVA had a low P-value. All genes with FDR-corrected (Benjamini and Hochberg, 1995) P-values less than 0.01 were considered significant. Analyses were conducted in the R statistical programming environment (R Development Core Team, 2009).

INSTRUMENT(S): HMS/SomeroLab-Mytilus-105K array-v1.0

SUBMITTER: Brent L Lockwood  

PROVIDER: GSE19031 | GEO | 2010-10-11

SECONDARY ACCESSION(S): PRJNA120631

REPOSITORIES: GEO

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Publications

Transcriptomic responses to heat stress in invasive and native blue mussels (genus Mytilus): molecular correlates of invasive success.

Lockwood Brent L BL   Sanders Jon G JG   Somero George N GN  

The Journal of experimental biology 20101001 Pt 20


Invasive species are increasingly prevalent in marine ecosystems worldwide. Although many studies have examined the ecological effects of invasives, little is known about the physiological mechanisms that might contribute to invasive success. The mussel Mytilus galloprovincialis, a native of the Mediterranean Sea, is a successful invader on the central and southern coasts of California, where it has largely displaced the native congener, Mytilus trossulus. It has been previously shown that therm  ...[more]

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