Q2. What are the three operations required for producing gynogenetic individuals and polyploid?
Retention of the second polar body is systematically induced by treating eggs with short heat shocks soon after insemination, resulting in ah-triploid progenies if functional sperm are used, and in high yields of heterozygous ~nogenetics after in-113TABLE IAuthors having induced sperm inactivation, retention of the second polar body and the suppression of first cleavage in fish.
Q3. How did the authors achieve suppression of first cleavage?
In order to induce retention of the second polar body and suppression of first cleavage, the authors tested early pressure shocks (EP shocks) applied in the first hour of development, and late pressure shocks (LP shocks) applied between 4 and 8 h after inse~ation.
Q4. how many embryos were induced by psi shocks?
5. Metaphases obtained on embryos produced by EP shocks (a: triploid) and by LP shocks (b: tetraploid; c: allotetraploid “female rainbow trout x male brown trout”; d: homozygous diploid gynogenetic individuals with residues of paternal chromatin - arrows).
Q5. How did the authors induce suppression of first cleavage?
Each latent consisted in placing 250 to 500 eggs in a stainless steel cylinder full of water at 9.4 “C and closed by a piston; the pressure level was raised with an external hydraulic press and reached 6000 or 7000 psi after 3 s; decompression was instantaneous at the end of the treatment which lasted 2 to 12 mm; the machine used here belongs to the Laboratory of Animal Biology of Toulouse University and had already been used in the induction of second115polar body retention in the newt Pleurodeles waltlii (Jaylet and Ferrier, 1978; Ferrier and Jaylet, 1978).
Q6. What was the effect of the shocks on hatching rates?
~erti~~ation with i~diated sperm Initial experiments showed that 6000 psi EP shocks lasting 3 min resulted in high hatching rates, whereas all the embryos died in the control (irradiated sperm; no pressure shock).
Q7. What is the average number of fragments in a given embryo?
For a given irradiation dose, it is evident that cells of homozygous embryos contained on average many more fragments (about twice as many) than did cells of heterozygous and haploid embryos.
Q8. What did the karyological investigations of progeny reveal?
Karyological investigations of progenies revealed only diploid complements, whereas all the analysed embryos of the control proved to be haploid.
Q9. What was the survival rate of the eggs after LP shocks?
8. Survival at the tail bud stage and after hatching (percentage of treated eggs) after 7000 psi LP shocks lasting 3 min and applied 4 h 60 min, 6 h 20 min and 5 h SO min after insemination with irradiated sperm.
Q10. how many embryos were treated after a gynogenesis?
most of the embryos from the 4-min treatment were abnormal and died without hatching, whereas most of117TABLE IIPercentages of treated eggs giving viable hatched fry (H) and feeding fry (F) for six females subjected to gynogenesis with retention of the second polar body (7000 psi shocks lasting 4 min applied 40 min after insemination with irradiated sperm)
Q11. how many embryos survived after 6000 EP shocks?
3. Survival at tail bud stage (day 20) and after hatching (day 60) following 6000 EP shocks applied 10 min after fertilization with normal sperm (percentage of treatedeggs).