DOI: 10.5061/dryad.gxd2547x4
title: Data from: Calcification in sea urchin larvae is associated with low metabolic costs

description: The energetic costs of generating calcium carbonate skeletons and shells
 in marine organisms remain largely speculative because of the scarcity of
 empirical data. However, this information is critical for estimating the
 energetic limitations of marine calcifiers that can explain their
 sensitivity to changes in seawater carbonate chemistry in past, present,
 and future marine systems. Here, the cost of calcification was evaluated
 using larval stages of the purple sea urchin, Strongylocentrotus
 purpuratus. We developed a skeleton re-mineralization assay, in which the
 skeleton was dissolved in live larvae followed by a re-mineralization over
 a few days. During skeleton re-mineralization, energetic costs were
 estimated through the measurement of key metabolic parameters including
 whole-animal metabolic rate, citrate synthase (CS) enzyme activity, and
 mRNA expression as well as mitochondrial density in the calcifying primary
 mesenchyme cells (PMCs). Minor increases in CS activity and a 10–15%
 increase in mitochondrial density in PMCs were observed in re-mineralizing
 larvae as compared with control larvae. Remineralization under three
 different pH conditions (pH 8.1, pH 7.6, and pH 7.1) decreased with
 decreasing pH, accompanied by pronounced increases in CS expression levels
 and increased mitochondrial density in PMCs at pH 7.6. Despite a prominent
 increase in mitochondrial density of primary mesenchyme cells,
 particularly in the calcifying cohort of this cell type, this work
 demonstrated a low overall metabolic response to increased mineralization
 rates at the whole-animal level under both high and low pH conditions. We
 conclude that calcification in sea urchin larvae is compromised under low
 pH conditions, associated with low energetic efforts to fuel compensatory
 processes.
description: Methods include sea urchin larval culturing, de- and
 recalcification of the larval skeleton, quantification of metabolism
 (citrate synthase activity and transcription levels, respiration rate) and
 mitrochondrial density using Mitotracker. For method details see published
 manuscript Hu et al. "Calcification in sea urchin larvae is
 associated with low metabolic costs", Journal of Experimental Biology
 (2024) 227, jeb248145, doi:10.1242/jeb.248145
description: # Data from: Calcification in sea urchin larvae is associated with low
 metabolic costs
 [https://doi.org/10.5061/dryad.gxd2547x4](https://doi.org/10.5061/dryad.gxd2547x4) ## Description of the data and file structure For this dataset, 6 runs of larval experiments either without pH treatment (O1 to O3) or with pH treatments (pH1 to pH3) with 3 to 5 replication flasks (n=3 to 5) were conducted. During each of the experiments, different parameters were measured and samples were collected for 1) measurements of larval morphology (O1 and pH1), 2) metabolic rates (O2 and pH 2), and 3) citrate synthase activity, citrate synthase transcript levels (mRNA) and mitochondrial density (O3 and pH3). ### Files and variables #### File: Dryad\_files.xlsx **Description:** The data are organized concerning the figures depicted in the published manuscript (Hu et al. "Calcification in sea urchin larvae is associated with low metabolic costs", Journal of Experimental Biology (2024) 227, jeb248145. doi:10.1242/jeb.248145 ##### Variables * Figure 2: larval body lengths (µm), growth rates (µm/day) and spicule lengths (µm), calcification rate (µm/day) * Figure 3: metabolic rates (pmol O2/larva/h), CS gene expression (delta-delta Ct), citrate synthase activity (U/mg prot), protein content (ng/larva) * Figure 4: fluorescence intensity (a.u.) * Figure 5: calcification rate (µm/larva/day) * Figure 6: metabolic rates (pmol O2/larva/h), CS gene expression (delta-delta Ct), citrate synthase activity (U/mg prot), protein content (ng/larva) * Figure 7: fluorescence intensity (a.u.) ## Code/Software Microscope software from LSM 900, Zeiss, Image J for image processing of mitrotracker images and images of larval morphology ## Access information Other publicly accessible locations of the data: * none Data was derived from the following sources: * none