Comparison of Diguanosine Polyphosphate Levels in Various Populations of Artemia Cysts
Thirteen populations of encysted embryos of Artemia obtained from the Artemia Reference Centre in Belgium were analyzed for their guanosine nucleotide content using high Performance liguid chromatography of neutralized perchloric acid extracts of the cysts. Results showed that the guanosine nucleotide content of Artemia cysts varied from 44 pmol/cyst (Thailand) to 125 pmol/cyst (Yugoslavia), while the diguanosine tetraphosphate content varied between 27 pmol/cyst (Thailand) and 78 pmol/cyst (Yugoslavia). These differences were found to reflect mainly the size of the cysts; cysts from Yugoslavia were the heaviest (5.95 ± 0.56 μg/cyst) while those from Thailand were the lightest (2.46 ± 0.14 μg/cyst). Cyst viability may also be an important factor. We also determined the energy charge of each population of cysts based on their guanosine and diguanosine nucleotide content which collectively represent about 90% of the total nucleotide pool in Artemia. The guanylate-based energy charge (ECg) was found to vary from 0.803 (Canada) to 1.192 (Philippines). Comparison between ECg and population viability using regression analysis showed a small linear correlation (r = 0.5) between these two parameters. However, no linear correlation was found between ECg and cyst mass (r = -0.2).