Telomerase activity and telomere detection during early bovine development

Area of Science:

• Genetics and Genomics
• Developmental Biology
• Molecular Biology

Background:

• Mammalian chromosome ends feature TTAGGG repeats called telomeres.
• Telomerase synthesizes telomeric DNA, counteracting replication-induced shortening.
• Critical telomere shortening and reduced telomerase activity are linked to cellular aging and senescence.

Purpose of the Study:

• Confirm TTAGGG repeats on bovine embryo chromosomes via in situ hybridization.
• Assess relative telomerase activity during oocyte maturation and early bovine embryo development using TRAP assay.

Main Methods:

• In situ hybridization with a telomere DNA probe on bovine blastocysts and fibroblasts.
• Telomeric Repeat Amplification Protocol (TRAP) assay on oocytes and embryos at various developmental stages (zygote to blastocyst).

Main Results:

• Telomeres, identified as TTAGGG repeats, were located on the terminal ends of bovine chromosomes.
• Telomerase activity was present across all examined developmental stages.
• Relative telomerase activity decreased during oocyte maturation and up to the 8-cell stage, then increased ~40-fold in morulae and blastocysts.

Conclusions:

• Bovine telomeres are composed of TTAGGG repeats.
• Telomerase activity is significantly upregulated in bovine morulae and blastocysts, suggesting a critical role in these later embryonic stages.