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    Öğe
    Production of androgenetic Nile tilapia, Oreochromis niloticus L.
    (Lab Research Fish Diseases, 2002) Karayücel, S; Karayücel, I; Penman, D; McAndrew, B
    Diploid androgenetic Nile tilapia, Oreochromis niloticus, were produced using 5 min UV irradiation at 150 muW/cm and heat shock at 42.5degreesC for 3:30 min applied 25 min after fertilization. The survival rates to morula, pigmentation, hatching and yolk sac resorption stages were 42.84+/-4.73%, 10.69+/-9.24%, 2.03+/-0.60% and 0.07+/-0.07% (relative to controls), respectively. A significant female, but not male, effect on the survival was confirmed. Multilocus DNA fingerprinting produced by hypervariable 33.15 DNA probe verified the all-paternal inheritance in the androgens. The sex ratio of the androgenetic tilapia was not significantly different from the expected ratio of 1:0 (male:female), indicating that O. niloticus has a monofactorial sex-determining mechanism with female homogamety and male heterogamety. This study confirmed that the YY genotype is viable and. fertile in O. niloticus.
  • [ X ]
    Öğe
    Thermal and hormonal feminization of all male YY Nile tilapia, Oreochromis niloticus L.
    (Israeli Journal Of Aquaculture-Bamidgeh, 2003) Karayücel, I; Penman, D; Karayücel, S; McAndrew, B
    Hormonal and thermal sex reversal of YY male Oreochromis niloticus were compared. While similar percentages of females (34% and 32%, respectively) were produced, a significantly higher percent of intersex individuals (18.5%) was produced in the heat (36 degreesC) treatment than in the group treated with diethylstilbestrol (DES; 1.6%). The heat-treated groups had 62.6% survival, compared to 97.0% and 97.3% in the control and DES-treated groups, respectively. Our results demonstrate that a high temperature treatment can be an alternative to hormonal sex-reversal treatments for YY male O. niloticus. Although the low survival and high occurrence of intersex individuals may limit its use, it can be used to produce large numbers of YY male broodstock in countries where hormone use is illegal and/or consumer reaction to hormonally-treated fish is negative.