Gorgonian coral (Junceella juncea and Junceella fragilis) oocyte chilling sensitivity in the context of adenosine triphosphate response (ATP).

Gorgonian corals are suffering continued decline in population and reproductive ability because of environmental changes. Cryopreservation can play an important role in ex situ conservation for these corals. In the present study, oocyte chilling sensitivity in the context of adenosine triphosphate (ATP) response in two gorgonian species (Junceella juncea and Junceella fragilis) and the effectiveness of cryoprotectants in protecting coral oocytes from chilling injury were studied in an attempt to develop protocols for their cryopreservation. Oocytes of two gorgonian corals were exposed to methanol (1 M, 2 M) and EG (1 M) at 5, 0 and -5 degree C for up to 216 hours, and ATP levels in oocytes were then determined. ATP levels decreased gradually with exposure time and 1M methanol was more effective in protecting oocytes from chilling injury than other cryoprotectant treatments tested. J. juncea oocytes were less sensitive to chilling than J. fragilis oocytes. This study provided useful information for development of cryopreservtion protocols for the two gorgonian coral oocytes.

Use of an adenosine triphosphate assay, and simultaneous staining with fluorescein diacetate and propidium iodide, to evaluate the effects of cryoprotectants on hard coral (Echinopora spp.) oocytes.

The objective was to examine the effects of cryoprotectants on oocytes of hard corals (Echinopora spp.) to obtain basic knowledge for cryopreservation procedures. Oocytes were exposed to various concentrations of cryoprotectants (0.25 to 5.0M) for 20 min at room temperature (25 degrees C). Two tests were used to assess ovarian follicle viability: fluorescein diacetate (FDA)+propidium iodide (PI) staining, and adenosine triphosphate (ATP) assay. Both FDA+PI staining and ATP assay indicated that cryoprotectant toxicity to oocytes increased in the order methanol, dimethyl sulfoxide (DMSO), propylene glycol (PG), and ethylene glycol (EG). The no observed effect concentrations for Echinopora spp. oocytes were 1.0, 0.5, 0.25, and 0.25 M for methanol, DMSO, PG, and EG, respectively, when assessed with FDA+PI. The ATP assay was more sensitive than FDA+PI staining (P<0.05). Oocyte viability after 1.0M methanol, DMSO, EG, or PG treatment for 20 min at room temperature assessed with FDA+PI tests and ATP assay were 88.9+/-3.1% and 72.2+/-4.4%, 66.2+/-5.0% and 23.2+/-4.9%, 58.9+/-5.4% and 1.1+/-0.7%, and 49.1+/-5.1% and 0.9+/-0.5%, respectively. We inferred that the ATP assay was a valuable measure of cellular injury after cryoprotectant incubation. The results of this study provided a basis for development of protocols to cryopreserve coral oocytes.