Mitochondrial-related consequences of heat stress exposure during bovine oocyte maturation persist in early embryo development

摘要

Hyperthermia during estrus has direct consequences on the maturing oocyte that carries over to the resultant embryo to compromise its ability to continue in development. Because early embryonic development is reliant upon maternal transcripts and other ooplasmic components, we examined impact of heat stress on bovine oocyte transcripts using microarray. Oocytes were matured at 38.5oC for 24 h or 41.0oC for the first 12 h of in vitro maturation; 38.5oC thereafter. Transcriptome profile was performed on total (adenylated + deadenylated) RNA and polyadenylated mRNA populations. Heat stress exposure altered the abundance of several transcripts important for mitochondrial function. The extent to which transcript differences are coincident with functional changes was evaluated by examining reactive oxygen species, ATP content, and glutathione levels. Mitochondrial reactive oxygen species levels were increased by 6 h exposure to 41.0oC while cytoplasmic levels were reduced compared to controls (P 0.05). Collectively, results indicate that direct exposure of maturing oocytes to heat stress may alter oocyte mitochondrial processes/function, which is inherited by the early embryo after fertilization.