Androgenetic pangasius hypophthalmus produced by uv irradiation of eggs of Clarias gariepinus and temperature shocks
1997
Krit Mongkonpunya | Suppaluk Roomratanapun | Wikrom Rungsin | Chokechai Senawong | Chongko Saetung | Amara Thongpan | Tiersch, Terrence (Kasetsart Univ., Bangkok (Thailand). Faculty of Science. Dept. of General Science)
Clarias gariepinus eggs were fertilized with sperm of Pangasius hypophthalmus (sutchi). Paraffin sections were made at different times after fertilization to determine the timing of the first mitotic division. The UV-irradiated (240 mJ/square m) eggs were also used to produce androgenetic offspring. To induce diploidization the temperature shocks (7 deg C, 15 deg C, 38 deg C and 40 deg C) with different shocking durations (10-25 min for cold shocks or 15-60 sec for heat shocks) were applied at different times post-insemination (20-45 min) The results showed that the highest number (a cluster of 25-30 percent) of fertilized eggs synchronized development 20-30 min after incubation. At this time a high percentage (25-30 percent) of early metaphase and metaphase chromosomes could be observed. Shocking the eggs at 7 deg C or 40 deg C with longer durations resulted in decreased fertilization and 0 percent normal fry (putative androgenetic P. hypophthalmus). Variation in number of normal fry at hatching ranged from 0 to 4 percent in fertilized eggs exposed to 15 deg C or 38 deg C temperature shocks. Ten specimens of normal fry were examined by polymerase chain reaction using primers targeting a portion of the gene encoding the immunoglobulin heavy chain. Eight of these specimens exhibited the specific DNA band (300 bp) of P. hypophthalmus.
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