Total and extracellular glycerol levels in <i>Symbiodinium</i> cells exposed to an osmotic up-shock.

<p>Control cultures with no additions, stressed cultures with 9% PEG added. Cells were collected after 1 hr treatment. Glycerol concentration given in mg mL⁻¹ in 10⁵ cells. Values are the means ± SD from three independent experiments. Significant probabilities (P) between control and stressed treatments for each cell type in bold (<b><0.05</b>).</p

Expression of genes associated to carbon fixation (Rubisco, <i>rbcA</i>) and synthesis of glycerol (glycerol 3-phosphate dehydrogenase, <i>GPD</i>).

<p>RT-PCR from 1 µg RNA extracted from <i>Symbiodinium</i> type B17 (upper panel) or type A1 cultures (lower panel) exposed to control (left lanes) or osmotic stress conditions (right lanes) for 1 hr. The amplification products were separated in agarose gels photographed, scanned and quantified with the ImageJ program (Rasband, W.S., ImageJ, U. S. National Institutes of Health, Bethesda, Maryland, USA, <a href="http://imagej.nih.gov/ij/" target="_blank">http://imagej.nih.gov/ij/</a>, 1997–2011). Color was inverted in the scans for clearer visualization. Numbers represent relative intensity of bands normalized to transcript levels for <i>GAPDH</i> (glyceraldehyde 3-phosphate dehydrogenase, see methods).</p

Photosynthetic parameters for <i>Symbiodinium</i> cultures exposed to high osmolarity conditions for 7 days.

<p>P_max and respiration (R) values expressed as µmol O₂ min⁻¹ cell⁻⁹ or µmol O₂ mg⁻¹ Chl <i>a</i> min⁻¹ respectively. Chl <i>a</i> values expressed in mg mL⁻¹. Values are the means of 3 independent experiments ± SD. Significant probabilities (P) in bold.</p>‡<p><b> = </b>values×10⁻⁸;</p>‡‡<p><b> = </b>values×10⁻⁶.</p

Photosynthesis <i>vs</i> irradiance (PE) curves normalized to cell density.

<p>Cells cultured for two weeks were incubated for 1 hr in control medium (solid line) or with the addition of 9% PEG (broken line). O₂ evolution was assessed under increasing light intensity, in <i>Symbiodinium</i> type B17 (<b>A</b>) and type A1 (<b>B</b>) cells. Each value represents the mean ± SD (bars) from 3 independent experiments. Data were fitted to a hyperbolic tangent function.</p

Growth of <i>Symbiodinium</i> cells under osmotic stress.

<p>(<b>A</b>) <i>Symbiodinium</i> type B17 and (<b>B</b>) type A1 cultures were inoculated with 1×10⁴ cells mL⁻¹. After 6 days growing under control conditions (solid lines), half of the culture was transferred and stressed by adding 9% PEG (broken lines). Means ± SD from three independent experiments are shown.</p

Photosynthetic parameters normalized to cell number for <i>Symbiodinium</i> cultured under experimental conditions.

<p>P_max and respiration (R) values expressed as µmol O₂ min⁻¹ cell⁻⁹. Samples are from two weeks old cultures after 1 hr incubations under control conditions or with the addition of 9% PEG (stress conditions). Values are means of 3 independent experiments ± SD. Significant probabilities (P) in bold (<b><0.05</b>).</p

Excitation pressure over PSII.

<p><i>Symbiodinium</i> cultures were exposed to high osmolarity conditions for (<b>A</b>) 1 hr or (<b>B</b>) 7 days, analyzed by fluorometry (see methods) and values for excitation pressure over PSII calculated for control conditions (white columns) or 9% PEG (gray columns). <i>Symbiodinium</i> types indicated on the ordinates. Results show the average from 3 independent experiments ± SD (bars).</p

Experimental stimulation of glycerol production in <i>Symbiodinium</i>.

<p>Total glycerol (µg mL⁻¹) produced by cultured <i>Symbiodinium</i> cells after 1 hr exposure to control conditions (white columns, minus symbol) or with 9% PEG up-shock (gray columns, plus symbol). Values adjusted to 1×10⁵ cells mL⁻¹. <i>Symbiodinium</i> types indicated on top. Results show the average from 3 independent experiments ± SD (bars). Significant probabilities (P>0.05) for comparisons between treatments are shown with an asterisk.</p