Convidamos a todos para a Defesa da Qualificação de Doutorado da discente do nosso programa, Amanda Oliveira Moura.

A defesa pública ocorrerá no dia 03 de julho de 2026 às 14h:00, presencial na sala 1C216 – Campus Glória

Abstract: Somatic cell nuclear transfer (SCNT) efficiency remains low, mainly due to18
incomplete epigenetic reprogramming of donor cells by the enucleated oocyte19
during early embryonic development. In this study, we investigated DNA20
methylation patterns in candidate genomic regions using bovine skin fibroblasts21
with high or low cloning efficiency, defined by the ability to generate offspring that22
survived for at least three months after birth. Repetitive elements, including α-23
Satellite and Satellite I DNA, did not show significant differences between groups.24
Likewise, no significant methylation differences were observed in METTL1425
region. In XIST DMR1, methylation patterns were highly variable among animals,26
particularly due to the aberrant profile observed in animal 2 from the low-27
efficiency group, highlighting individual epigenetic variation among donor cells.28
Oct4 showed higher methylation levels in the high-efficiency group. The29
imprinting control region (ICR) of H19/IGF2 exhibited the expected allele-specific30
methylation pattern, consistent with proper imprint maintenance. In contrast,31
IGF2R/AIRN ICR showed distinct methylation profiles between groups, with32
higher methylation levels in the high-efficiency group. Since IGF2R/AIRN is not33
imprinted in fibroblasts, this pattern may represent an additional challenge for34
oocyte-mediated nuclear reprogramming. These results suggest that this locus35
may represent a candidate epigenetic marker associated with SCNT efficiency36
and support the notion that donor cells possess epigenetic features capable of37
persisting after nuclear transfer, reinforcing the influence of donor cell origin on38
SCNT success. Understanding how different genomic regions respond to39
reprogramming may help clarify the molecular basis underlying the low efficiency40
of SCNT.41

Keywords: DNA methylation; SCNT; bovine fibroblasts; epigenetic42
reprogramming; genomic imprinting; IGF2R; XIST