In A. aspera, symbiont density and volume of algal
Alisertib were determined by performing 8 replicate counts of each coral sample on a haemocytometer using a compound microscope (Olympus CX21) (magnification of 100 ×) and measuring the cell diameter of 20 random algal cells using a stage micrometre (magnification of 200 ×). Chlorophyll a (Chl a) content was quantified by extracting filtered coral subsamples in 90% acetone at − 20 °C overnight in dark conditions. Thawed acetone extracts were sonicated and centrifuged for 15 min and the absorbance was measured by spectrophotometry (GBC UV/VIS 916 spectrophotometer) at 664, 665 and 750 nm wavelengths before and after adding 0.1 M HCl using a standard method ( APHA, 199
cool . As described above, fresh weights of U. intestinalis and U. lactuca were estimated at the start of the sample preparation. The concentration estimates of Chl a in Ulva sp. per gramme of fresh weight of macroalgal tissue
hypotonic was determined in Beer and Israel (1986) were used to convert the U. intestinalis and U. lactuca fresh weight estimates to Chl a values for normalisation of DMSP and DMSO content.
