(A) Intercrossing of TERTΔ8/+ heterozygous (het) fish to generate generation 1 (G1) TERTΔ8/Δ8 fish. G1 TERTΔ8/Δ8 fish are observed at the expected Mendelian ratios (no difference between expected and observed frequencies, p = 0.8809, χ2 test).
(B) G1 TERTΔ8/Δ8 embryos (left panels) and adults (right panels) are outwardly normal.
(C) Schematic for the Telomere Repeat Amplification Protocol (TRAP). Telomerase enzymatic activity in liver is evaluated by the ability of tissue extract to add telomeric repeats to radio-labeled artificial telomeres in vitro.
(D) Telomerase enzymatic activity as measured by the TRAP assay in TERT+/+ and G1 TERTΔ8/Δ8 fish liver samples. IC: TRAP internal control product. Representative of 3 independent experiments.
(E) Experimental design to assess male fertility. TERTΔ8/+ (control) and G1 TERTΔ8/Δ8 (mutant) males, at two different age groups (2 and 4 months), were mated with young (2 months) wild-type (WT) females. Fertilized eggs (gray) were counted after 1 week.
(F) Ratio of fertilized eggs per week of egg-lay in TERTΔ8/+ (control) and G1 TERTΔ8/Δ8 (mutant). Mean±SD of >70 eggs, generated from 4–5 crosses per age group. Wilcoxon signed-rank test, *p<0.05, **p<0.01. For the comparison between age groups, standardized values to age-matched controls were used.
(G) Histological sections of testis from TERT+/+ (control) and G1 TERTΔ8/Δ8 fish at 4–5 months (4m, full size image) and 2 months (2m, insert). Sz: spermatozoa (mature sperm); St: spermatids. Scale bar: 50μm. Representative of n≥6 individuals from each genotype (4–5 months) and n=2 individuals from each genotype (2 months).