title: Activation regimens for full-term development of rabbit oocytes injected with round spermatids.
abstract: The present study was designed to investigate the effect of activation regimens on full-term development of rabbit oocytes after round spermatid injection (ROSI). In the first series, rabbit oocytes were treated with 5 microM ionomycin before ROSI, after ROSI, or before and after ROSI. In addition, non-treated oocytes were subjected to intracytoplasmic sperm injection (ICSI) using ejaculated spermatozoa. Cleavage rate of ROSI oocytes activated before and after ROSI (55%) was comparable with that of ICSI oocytes (60%), and significantly higher than those of ROSI oocytes activated either before or after ROSI (29-39%; P < 0.05). No offspring were produced by transfer of the cleaving ROSI oocytes, while 8% of the cleaving ICSI oocytes transferred gave birth to offspring. In the second series, oocytes were exposed to 5, 10, or 20 microM ionomycin, followed by ROSI, 5 microM ionomycin treatment, and incubation with 5 microg/ml cycloheximide (CHX) + 2 mM 6-dimethylaminopurine (DMAP). Significantly higher cleavage rates were derived from oocytes activated with 10 and 20 microM ionomycin before ROSI (91% and 82%, respectively; P < 0.05) compared to those activated with 5 microM ionomycin before ROSI (53%). Live offspring were obtained when the cleaving ROSI oocytes with the initial ionomycin treatment at 5 and 10 microM were transferred (offspring rate 2% and 4%, respectively). These activation regimens, however, were not valid for the ROSI using cryopreserved round spermatids. In conclusion, rabbit ROSI oocytes were capable of developing into full-term when the oocytes were activated with a combined treatment of ionomycin and CHX/DMAP.
authors.affiliation: Section of Mammalian Transgenesis, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Okazaki, Aichi, Japan. mhirarin@nips.ac.jp
authors.forename: Masumi
authors.initials: M
authors.lastname: Hirabayashi
authors.forename: Megumi
authors.initials: M
authors.lastname: Kato
authors.forename: Kensaku
authors.initials: K
authors.lastname: Kitada
authors.forename: Naoko
authors.initials: N
authors.lastname: Ohnami
authors.forename: Masao
authors.initials: M
authors.lastname: Hirao
authors.forename: Shinichi
authors.initials: S
authors.lastname: Hochi
mesh_terms: D000818:Animals; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy; D011817:Rabbits; D020554:Sperm Injections, Intracytoplasmic; D013087:Spermatids / Q000166:cytology* / Q000502:physiology
chemical_list: D007476:Ionophores; D015759:Ionomycin