Acclimatory gene expression of primed clams enhances robustness to elevated pCO.

Sublethal exposure to environmental challenges may enhance ability to cope with chronic or repeated change, a process known as priming. In a previous study, pre-exposure to seawater enriched with pCO improved growth and reduced antioxidant capacity of juvenile Pacific geoduck Panopea generosa clams, suggesting that transcriptional shifts may drive phenotypic modifications post-priming. To this end, juvenile clams were sampled and TagSeq gene expression data were analysed after (i) a 110-day acclimation under ambient (921 μatm, naïve) and moderately elevated pCO (2870 μatm, pre-exposed); then following (ii) a second 7-day exposure to three pCO treatments (ambient: 754 μatm; moderately elevated: 2750 μatm; severely elevated: 4940 μatm), a 7-day return to ambient pCO and a third 7-day exposure to two pCO treatments (ambient: 967 μatm; moderately elevated: 3030 μatm).

Invertebrate methylomes provide insight into mechanisms of environmental tolerance and reveal methodological biases.

There is a growing focus on the role of DNA methylation in the ability of marine invertebrates to rapidly respond to changing environmental factors and anthropogenic impacts. However, genome-wide DNA methylation studies in nonmodel organisms are currently hampered by a limited understanding of methodological biases. Here, we compare three methods for quantifying DNA methylation at single base-pair resolution-whole genome bisulfite sequencing (WGBS), reduced representation bisulfite sequencing (RRBS), and methyl-CpG binding domain bisulfite sequencing (MBDBS)-using multiple individuals from two reef-building coral species with contrasting environmental sensitivity.