DNA methylation and mRNA expression profiles in bovine oocytes derived from prepubertal and adult donors.
The developmental capacity of oocytes from prepubertal cattle is reduced compared with their adult counterparts, and epigenetic mechanisms are thought to be involved herein. Here, we analyzed DNA methylation in three developmentally important, nonimprinted genes (SLC2A1, PRDX1, ZAR1) and two satellite sequences, i.e. 'bovine testis satellite I' (BTS) and 'Bos taurus alpha satellite I' (BTαS). In parallel, mRNA expression of the genes was determined by quantitative real-time PCR. Oocytes were retrieved from prepubertal calves and adult cows twice per week over a 3-week period by ultrasound-guided follicular aspiration after treatment with FSH and/or IGF1. Both immature and in vitro matured prepubertal and adult oocytes showed a distinct hypomethylation profile of the three genes without differences between the two types of donors. The methylation status of the BTS sequence changed according to the age and treatment while the methylation status of BTαS sequence remained largely unchanged across the different age and treatment groups. Relative transcript abundance of the selected genes was significantly different in immature and in vitro matured oocytes; only minor changes related to origin and treatment were observed. In conclusion, methylation levels of the investigated satellite sequences were high (>50%) in all groups and showed significant variation depending on the age, treatment, or in vitro maturation. To what extent this is involved in the acquisition of developmental competence of bovine oocytes needs further study.
Institute of Farm Animal Genetics, 31535 Mariensee, Neustadt, Germany.
Mike
M
Diederich
Tamara
T
Hansmann
Julia
J
Heinzmann
Brigitte
B
Barg-Kues
Doris
D
Herrmann
Patrick
P
Aldag
Ulrich
U
Baulain
Richard
R
Reinhard
Wilfried
W
Kues
Christian
C
Weissgerber
Thomas
T
Haaf
Heiner
H
Niemann
D000375:Aging; D000818:Animals; D002417:Cattle; D019175:DNA Methylation / Q000235:genetics*; D004276:DNA, Satellite / Q000737:chemistry; D004527:Egg Proteins / Q000235:genetics; D044127:Epigenesis, Genetic; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage; D051272:Glucose Transporter Type 1 / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage; D008297:Male; D009865:Oocytes / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*; D054464:Peroxiredoxins / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis*; D012741:Sexual Maturation; D059467:Transcriptome
D004276:DNA, Satellite; D004527:Egg Proteins; D051272:Glucose Transporter Type 1; D012333:RNA, Messenger; C471631:Zar1 protein, human; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone; D054464:Peroxiredoxins