CRYOPRESERVATION OF LEUKOCYTES OF CHANNEL CATFISH FOR SUBSEQUENT CYTOGENETIC ANALYSIS

Channel catfish leucocytes cryopreserved with glycerol or dimethyl sul phoxide (DMSO) had significantly higher (P<0.05) viability and recover y rates than did cells cryopreserved with methanol. After 7 days of fr ozen storage, a 24 to 27% reduction of viability was observed for cell s cryopreserved with glycerol; a 25 to 43% reduction for cells frozen with DMSO, and a 67 to 100% reduction for cells frozen with methanol. The concentration of cryoprotectants affected the viability of cryopre served cells significantly (P<0.05). The viability reduction was 36% f or cells frozen with 5% of cryoprotectants, 30% for cells frozen with 10% of cryoprotectants, and 49% for cells frozen with 15% of cryoprote ctants. The viability of cells frozen at the slower rate (-2.7 degrees C min(-1)) was significantly higher (P<0.05) than that of cells froze n at the faster rate (-45 degrees C min(-1)). Best results were obtain ed for cells cryopreserved with 10% of glycerol or DMSO and frozen at the slower rate. The chromosomes prepared from cells cryopreserved usi ng this procedure were identical to those prepared from fresh cells, a nd to those reported in the literature for channel catfish. (C) 1995 T he Fisheries Society of the British Isles