Table 1.
Set of forward and reverse primers used for gene expression analysis.
Fig 1.
Picture of calcein marking (green fluorescent line) on a pearl cut in half and observed under an epifluorescence microscope (×400).
The red arrow indicates the growth direction of nacre.
Fig 2.
Mean relative expression of genes encoding proteins involved in the formation of the nacreous layer (Pearlin, Pif177 and MSI60), prismatic layer (Aspein) and both (Nacrein) in pearl sacs following a one-month experiment at different microalgal or water temperature conditions.
(A) Different microalgal concentrations: 7,000 cell mL-1 (light grey) and 28,000 cell mL-1 (dark grey); and (B) different water temperatures: 22°C (light grey) and 30°C (dark grey). Fold changes were calculated from 20 individuals per condition. Y-axes are in the logarithmic scale. Error bars indicate standard deviations (SD); statistical analyses used Student’s t-tests (A: Pearlin, Pif177, MSI60 and Aspein; B: Pearlin, Pif177 and Nacrein) or Mann-Whitney tests (A: Nacrein; B: MSI60 and Aspein). Statistical significance is indicated by asterisks as follows: * p < 0.05.
Fig 3.
Mean shell and pearl deposition rate (SDR and PDR, μm day-1) in the pearl oyster Pinctada margaritifera after one month at different (A and B) microalgal concentrations and (C and D) water temperatures.
Each plot includes mean (“+” cross in the box-plot), median (solid bar in the box-plot), 25th to 75th percentile represented in the rectangular box, 1.5×interquartile range (non-outlier range of the box whiskers), minimum and maximum values (extreme dots) and outlier values (outside box whiskers). Statistical analysis is based on the Student’s t-test. Statistical significance is indicated by asterisks as follows: *p < 0.05, **p < 0.01. (A: n = 88 and n = 87 for pearl oysters fed at 7000 cell mL-1 and 28,000 cell mL-1, respectively; C: n = 46 and n = 50 for pearl oysters subjected to 22°C and 30°C, respectively; and D: n = 9 per condition).
Fig 4.
Pearl nacre tablet thickness and number of tablets deposited per day in pearl oyster Pinctada margaritifera after one month at different (A and B) microalgal concentrations and (C and D) water temperatures.
Each plot includes: mean (“+” cross in the box-plot), median (solid bar in the box-plot), 25th to 75th percentiles represented in the rectangular box, 1.5×interquartile range (non-outlier range of the box whiskers), minimum and maximum values (extreme dots) and outlier values (outside box whiskers). Statistical analysis is based on the Mann-Whitney test for pearl nacre tablet thickness and on the Student’s t-test for number of tablets deposited per day. Statistical significance is indicated by asterisks as follows: *p < 0.05, ***p < 0.001. (A and C: n = 270 per condition; B and D: n = 9 per condition).
Table 2.
Correlation between relative gene expression and pearl deposition rate and nacre tablet thickness for microalgal concentration experiment.
Table 3.
Correlation between relative gene expression and pearl deposition rate and nacre tablet thickness for water temperature experiment.
Fig 5.
Proportion of harvested pearls in different pearl quality categories 12 months postgrafting following one month at different microalgal concentrations and water temperatures.
Effect of pearl oyster fed at 7,000 or 28,000 cells mL-1 (n = 71 and n = 73, respectively) on (A) the number of defects, (B) color, (C) darkness and (D) luster. Effect of pearl oyster subjected to 22 or 30°C (n = 34 and n = 48, respectively) on (E) the number of defects, (F) color, (G) darkness and (H) luster. > indicates a significantly higher number and < a significantly lower number than expected by chance (F-test, p < 0.05).