Proteomic analysis of the early larval development of a New Zealand sea urchin in near-future levels of ocean acidity

Abstract

Increasing levels of carbon dioxide in the atmosphere are directly contributing to the decreasing pH of our oceans; this phenomenon is known as ocean acidification (OA). Previous research demonstrates OA has a detrimental effect on the larval development of animals that use calcium carbonate to form shells and skeletal structures. Evechinus chloroticus, a sea urchin endemic to New Zealand, is a suitable candidate for examining the impacts of OA on larval development as it is an ecologically and economically important coastal species. This study examined the protein contents (proteome) of larvae exposed to differing levels of water acidity. A control and two predicted levels of near-future ocean acidity (380 ppm, 1000 ppm, and 1800 ppm CO2 respectively) were used. The study also focused on a post-translational modification, phosphorylation, which is known to change the function of proteins in response to stress (Dineshram et al. 2013). Phosphorylated proteins were selected for identification, and processed using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and these proteins were matched to the genome of E. chloroticus based off the sequenced transcriptome. Several proteins implicated in physiological pathways activated by OA in studies on other larvae were present in the phosphorylated proteins identified in this study. These majority of the proteins identified are involved in the cellular metabolic processes, while the rest perform structural or chaperone and protein-folding roles. The results of this study align with other research on the response of larvae to environmental stress, and provide insight into the role of phosphorylation in E. chloroticus’ response to OA.