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Induced triploidy by cold shock in Puntius gonionotus (Bleeker)
315 At 5 min postfertilization, ova of red sea bream were shocked in iced sea water at 3°C for 20 min and at 1.5 aC for 5 min to induce triploidy. Eggs treated at 3 oC were placed in cold water of 12.5”C before moving to ambient water at 19°C. Total mortality of all embryos occurred before gastrulation in this experimental group. Cold shock at 1.5”C for 5 min resulted in 17% triploid fish and 28Ohmosaics as determined by chromosome preparation from tissue taken at hatching. Thus, additional work is required on inducing triploidy by cold shocking at l-3°C lasting between 5 and 20 min, 5 min postfertilization, to perfect the conditions for triploidization in this fish species.
Induced triploidy by cold shock in Puntius gonionotus (Bleeker) U. Na-Nakom and Emmanuelle Legrand Department ofAquaculture, Faculty ofFisheries, Kasestsart University,Bangkok 10903, Thailand
The experiment to induce triploidy through cold shock with Puntius gonionotus was done by using freshly stripped eggs from two females fertilized with sperm from different males. Fertilized eggs were dipped in cold water ( 15’ C) at 0 and 5 min after fertilization with shock durations of 15 and 30 min. Results revealed that only cold-shock at 0 min after fertilization with shock duration of either 15 or 30 min produced triploid fry; the rates were 95.4% and 90.4%, respectively. Average hatching rate was low (28.5Oh and 23.2%) as was survival (31.2% and 10.8%) for shock durations of 15 and 30 min, respectively. At maturity the gonads of triploid fish were tremendously reduced in size compared to their diploid counterparts. Histological study revealed a few vitellogenic oocytes and spermatids in the ovaries and testes, respectively.
Induction of polyploid nauplii in Penaeus indicus AQUACOP, C. Ledu and A. Diter IFREMER-COP, B.P. 7004, Tawaro, Tahiti, French Polynesia
Polyploidy induction was attempted by heat shocking newly spawned eggs with treatments applied from 6 to 46 min (at 2 min intervals) after spawning. Heat shocking temperatures were from 30 to 44°C and shocks lasted for 1 to 7 min. Ploidy level was assessed by means of chromosome counts of metaphase cells from 24-h-old nauplii. Percent ploidy induction was variable depending on the spawn. Nevertheless, the optimal treatment parameters were determined and produced 47% triploid and 93% tetraploid live nauplii. Survival reached 19% and 0.3% of the control in the tripioid and tetraploid batches respectively, at the nauplius stage.
Induced triploidy by cold shock in Puntius gonionotus (Bleeker) U. Na-Nakom and Emmanuelle Legrand Department ofAquaculture, Faculty ofFisheries, Kasestsart University,Bangkok 10903, Thailand
The experiment to induce triploidy through cold shock with Puntius gonionotus was done by using freshly stripped eggs from two females fertilized with sperm from different males. Fertilized eggs were dipped in cold water ( 15’ C) at 0 and 5 min after fertilization with shock durations of 15 and 30 min. Results revealed that only cold-shock at 0 min after fertilization with shock duration of either 15 or 30 min produced triploid fry; the rates were 95.4% and 90.4%, respectively. Average hatching rate was low (28.5Oh and 23.2%) as was survival (31.2% and 10.8%) for shock durations of 15 and 30 min, respectively. At maturity the gonads of triploid fish were tremendously reduced in size compared to their diploid counterparts. Histological study revealed a few vitellogenic oocytes and spermatids in the ovaries and testes, respectively.
Induction of polyploid nauplii in Penaeus indicus AQUACOP, C. Ledu and A. Diter IFREMER-COP, B.P. 7004, Tawaro, Tahiti, French Polynesia
Polyploidy induction was attempted by heat shocking newly spawned eggs with treatments applied from 6 to 46 min (at 2 min intervals) after spawning. Heat shocking temperatures were from 30 to 44°C and shocks lasted for 1 to 7 min. Ploidy level was assessed by means of chromosome counts of metaphase cells from 24-h-old nauplii. Percent ploidy induction was variable depending on the spawn. Nevertheless, the optimal treatment parameters were determined and produced 47% triploid and 93% tetraploid live nauplii. Survival reached 19% and 0.3% of the control in the tripioid and tetraploid batches respectively, at the nauplius stage.