Complete loss of TF activity results in early lethality due to hemorrhage.

(A) Fish from a double heterozygous (Aa/Bb) f3 incross were genotyped at 8 weeks of age and found to have normal Mendelian ratios (n = 135, AA/BB = 10, AA/Bb = 17, AA/bb = 7, Aa/BB = 15, Aa/Bb = 36, Aa/bb = 20, aa/BB = 10, aa/Bb = 13, aa/bb = 9). Survival curves show that by 9 weeks, there was statistically significant loss of aa/bb offspring. By 400 days, there was a relatively even reduction of the remaining genotypes which is common in wild-type fish, and confirms that a single copy of f3a or f3b is sufficient for survival. (B) A repeat cohort was left undisturbed until genotyping at 6 months of age. The statistically significant loss of aa/bb confirms the early lethality of TF loss independent of genotyping stress. (C) A group of 7 double homozygous mutants were identified at 1 month of age and observed over the following 3 months. 6/7 were lost by 2 months with the single survivor passing at 112 days. (D) Early lethality was due to gross hemorrhage. Examples include the pericardial space (left) and head (right) (red arrows).