Assessment of Telomere Length During Post-Natal Period in Offspring Produced by a Bull and Its Fibroblast Derived Clone

Objective: To investigate the telomere length in bovine offspring produced by a cloned and control bull, and the telomerase activity in embryos produced with the same technology. Methods: Five daughters of a control and five daughters of a bull cloned using a fibroblast of the control were produced by IVF using sperm of the two bulls. Blood samples of the offspring were collected at 2, 6, and 12 months of age and the relative telomere length (RTL) was assessed by flow cytometry. At same time the body growth, hematological profile, and clinical biochemistry of the same progeny was extensively surveyed, and results have been reported in a previous work. Thereafter, the telomerase activity was assessed using a real time PCR quantitative assay in groups of embryos produced with the same technology. Results: The offspring of the clone exhibited a modest, but significant (P<0.05), shortening of the telomeres (21.36%, 20.56% and 20.56%) compared to that of the control (23.78%, 23.53% and 22.43%) as mean values determined at 2, 6 and 12 months, respectively. Shortening of telomeres in respect to the age was not significant. No statistical difference was reported between telomerase activity assessed in 144 cloned (3.4−03 ± 2.4−03 amoles/μL) and 80 control (2.1−03 ± 1.8−03 amoles/μL) embryos. Conclusions: The results have revealed a moderate shortening of telomeres in the offspring of the clone with respect to control. However, this study did not evidence differences in the two progenies that suggest welfare problems during the first year of life.