INDUCTION OF T ETRAPLOIDY IN RAINBOW TROUT (ONCHORHYNCHUS MYKISS) BY HEAT SHOCK

This study has been conducted for determination of optimum time and duration of thermal shock on tetraploidy induction in Rainbow trout. This study was carried out by induction of 28°C thermal shock in different times after fertilization (49.5, 54.0, 58.5, 63.0, 67.5, 72.0, 76.5 and 81,0°C/hour and different duration (8, 10 and 12 min). Nuclear erythrocytes, cellular area and volume measurement were determined among blood smears of fingerling and statistic analysis showed that, induction of tetraploidy was conducted between 0-75% on various treatment, but highest tetraploidy yield (8.4%) was achieved by thermal shock on 28°C within 12 minutes, 74 degree-hour after fertilization. Moreover, tetra ploidy diagnostic was also approved by determination of nucleolus number in fishes. In this respect tetraploid and diploid fishes have 3-4 and 1-2 nucleolus, respectively