بهينه سازي شوك حرارتي جهت القاء تتراپلوييدي در ماهي قزل آلاي رنگين كمان Oncorhynchus mykiss

چكيده انگليسي :

Optimization of Thermal Shock for Tetraploidy Induction in Rainbow trout Oncorhynchus mykiss Amir Vafaei Saadi Amirvsty 1335@gmail com Date of Submission 2011 04 13 Department of Natural Resources Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Dr S Dorafshan sdorafshan@cc iut ac irAbstract Tetraploid lines are important for the mass production of strile tripliods as well as other kinds of polyploidssuch as penta hexa hepta and octaploids The effective usage of tetraploid fish such as rainbow trout Oncorhynchus mykiss is compeletley depended on teteraploid induction and the ability of fish to surviveand produce viable gametes The first and most important factors affect tetraploid production is shockoptimization for different fish stocks In this study the effectiveness of different heat shock temperatures 28 30 and 32 C shock durations 1 5 and 10 minutes as well as starting times 45 55 65 75 and 85 degree hours after fertilization on two egg diameter classes upper and lower 5 mm were investigated Two controlgroups intact and physical shock group for each egg diameter batch were used in three replicates so totally276 experimental groups were used to find the optimum treatment of tetraploidy induction in rainbow troutegg Survival rates up to eyed hatching and swim up stages were compared between and within treatedgroups Tetraploid fish were detected based on red blood cell dimensions as well as NORs analysis of fish atswim up stage The results showed significant differences in survival rates from fertilization to eyed stagesand from hatching to swim up stages between as well as within groups p 0 05 but in both egg diameterclasses survivals from eyed stages to hatching were the same p 0 05 Based on red blood cell dimansionsas well as NORs analysis the range of tetraploid individuals were 0 67 and 0 75 percent in two different eggdiameters groups upper and lower than 5 mm respectively The highest percentage of tetraploids wereachieved in groups of eggs which had diameters higher than 5 mm at 28 C 65 degree hour for 10 minutes 67 and 5 minutes 60 While in groups which included lower egg size the highest rate of tetraploids 75 was measured at 28 C 65 degree hour for 5 minutes Comparsion of tetraploid yields betweendifferent groups showed that the thermal shock at 28 C starting at 65 degree hour and lasting for 10 minuteswas the most effective shocks to produce tetraploid individuals for egg diameters upper than 5 mm and couldincrease the tetraploidy yields up to 12 p 0 05 While sevsral treatments could resulted suitable rates oftetrapolidy in the smaller egg sizes lower than 5 mm in diameter including 28 C 75 degree hour for 1minutes 7 32 C 65 degree hour for 1 minutes 6 3 as well as 32 C 45 degree hour for 1 minutes 6 2 p 0 05 It could be concluded that tetraploidy induction in rainbow trout are compeletly depend onstarting time and duration of heat shocks There is a negative correlation between temperature and survivalrates by increasing the temprature up to 32 C the survival rates decrease dramatically While changing instarting time of shock depending on egg sensivity e g diameter can increase or decrease survival rates Theresults also confirmed that based on egg diameters different thermal shocks should be applied Key words Tetraploid Rainbow trout Oncorhynchus mykiss Optimal thermal shock Eggdiameter

وفائي سعدي، امير

بهينه سازي شوك حرارتي جهت القاء تتراپلوييدي در ماهي قزل آلاي رنگين كمان Oncorhynchus mykiss

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