Towards cryopreservation of Greenshell mussel (Perna canaliculus) oocytes.
Cryopreservation is a powerful tool for selective breeding in aquaculture as it enables genetic material from selected stock to be stored and crossed at will. The aim of this study was to develop a method for cryopreserving oocytes of the Greenshelltrade mark mussel (Perna canaliculus), New Zealand's main aquaculture species. The ability of oocytes to be fertilized post-thawing was used as the criterion for success in initial experiments and then subsequently, the ability of frozen oocytes to develop further to D-stage larvae was assessed. Ethylene glycol, propylene glycol, dimethyl sulphoxide and glycerol were evaluated at a range of concentrations with and without the addition of 0.2M trehalose using post-thaw fertilization as the endpoint. Ethylene glycol was most effective, particularly when used in combination with trehalose. A more detailed investigation revealed that ethylene glycol at 9% or 10% in the presence of 0.2-0.4M trehalose afforded the best protection. In experiments varying sperm to egg ratio and egg density in post-thaw fertilization procedures, D-larval yield averaged less than 1%. Following these results, a detailed experiment was conducted to determine the damaging steps in the cryopreservation process. Fertilization losses occurred at each step whereas D-larval yield approximately halved following CPA addition and was almost zero following cooling to -10 degrees C. Cryomicroscopy studies and fertilization results suggest that the inability of oocytes to develop to D-larvae stage after cooling to -10 degrees C and beyond are most likely related to some form of chilling injury rather than extracellular ice triggering intracellular ice formation. Further research is needed to determine the causes of this injury and to reduce CPA toxicity and/or osmotic effects.
Adams
Serean L
SL
Cawthron Institute, Private Bag 2, 98 Halifax Street East, Nelson, New Zealand. Electronic address: serean.adams@cawthron.org.nz.
Tervit
H Robin
HR
Cawthron Institute, Private Bag 2, 98 Halifax Street East, Nelson, New Zealand; AgResearch, Private Bag 3123, Hamilton, New Zealand.
McGowan
Lindsay T
LT
AgResearch, Private Bag 3123, Hamilton, New Zealand.
Smith
John F
JF
Cawthron Institute, Private Bag 2, 98 Halifax Street East, Nelson, New Zealand; AgResearch, Private Bag 3123, Hamilton, New Zealand.
Roberts
Rodney D
RD
Cawthron Institute, Private Bag 2, 98 Halifax Street East, Nelson, New Zealand.
Salinas-Flores
Liliana
L
Department of Food Science, University of Otago, P.O. Box 56, Dunedin, New Zealand.
Gale
Samantha L
SL
Cawthron Institute, Private Bag 2, 98 Halifax Street East, Nelson, New Zealand.
Webb
Stephen C
SC
Cawthron Institute, Private Bag 2, 98 Halifax Street East, Nelson, New Zealand.
Mullen
Steven F
SF
Comparative Medicine Center, University of Missouri, 1600 East Rollins Street, Columbia, MO 65211, USA.
Critser
John K
JK
Comparative Medicine Center, University of Missouri, 1600 East Rollins Street, Columbia, MO 65211, USA.
D000818:Animals; D017756:Aquaculture / Q000379:methods; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents; D005260:Female; D005306:Fertilization; D007814:Larva / Q000166:cytology; D009520:New Zealand; D009865:Oocytes / Q000166:cytology*; D049883:Perna / Q000166:cytology*
D003451:Cryoprotective Agents