Paternal influence on S-phase in the first cell cycle of the bovine embryo.
The objective of this study was to determine whether the initiation and length of the zygotic S-phase differs for embryos sired by bulls demonstrating high versus low fertility in vivo. Bovine oocytes were matured in vitro for 24-27 h and fertilized with frozen-thawed bovine semen. Six bulls that differed in fertility level were used in the study. The bulls were classified into two groups: those demonstrating high fertility in vivo (in vivo high-fertility bulls; n = 3), with a group mean +/- SEM lifetime nonreturn rate of 78 +/- 2%, and those demonstrating low fertility in vivo (low-fertility bulls; n = 3), with a group mean +/- SEM nonreturn rate of 69 +/- 1%. The S-phase in zygotes was identified by means of an immunocytochemical technique after pronuclear-stage zygotes were labeled with 5'bromo-2'deoxyuridine (BrdU). To visualize all pronuclei, presumptive zygotes were also stained with propidium iodide. In the first experiment, zygotes were labeled with BrdU at 2-h intervals from 8 to 20 h after sperm addition. There were no differences between bull fertility groups in the time course of pronuclear formation (p > 0.05). The beginning of S-phase was earlier in zygotes sired by high- compared to low-fertility bulls (p < 0.05). The end of S-phase was not affected by sire fertility group (p > 0.05). In the second experiment, zygotes were labeled with BrdU continuously from 8 to 20 h after sperm addition.(ABSTRACT TRUNCATED AT 250 WORDS)
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Department of Meat and Animal Science, University of Wisconsin-Madison 53706.
Lorton
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Parrish
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D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D002417:Cattle / Q000196:embryology*; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D004247:DNA / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology* / Q000378:metabolism; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D005298:Fertility / Q000502:physiology; D005307:Fertilization in Vitro; D008297:Male; D009865:Oocytes / Q000502:physiology; D016196:S Phase / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology*; D015053:Zygote / Q000166:cytology / Q000378:metabolism
D004247:DNA; D001973:Bromodeoxyuridine