Abstract
The cysts of Artemia franciscana (A. franciscana) are known to reserve a large quantity of trehalose and exhibit strong tolerance to desiccation and freezing. However, when cysts are hydrated, their resistance is markedly reduced. To investigate the effect of freezing rate on the hatching ratio, various levels of hydrated cysts of A. franciscana were frozen. The hatching rate of hydrated cysts declined shortly at rapid frozen (-5℃/min), but high hatching rates can be consistently observed at slow freezing rates (-0.5℃/min and -0.1℃/min). Improved DSC analysis also showed differential thermograms at two cooling rates, suggesting that ice formation inside hydrated cysts were clearly distinct between them. We hypothesized that freezing damages even from highly hydrated cysts were attenuated significantly at slow freezing rates, due at least in part to a synergistic effect of trehalose.
