Abstract
Abstract: The objective of this work was to evaluate the efficiency of roscovitine on reversibly inhibiting oocytes from prepubertal sheep at the germinal vesicle (GV) stage, and to investigate the kinetics of meiosis progression after inhibitor removal. Cumulus-oocyte complexes, recovered from Sarda breed lambs aged 30-40 days, were cultured for 6 hours in a maturation medium (control) containing 75 μmol L-1 roscovitine (Rosco) at 38.5°C and 5% CO2. Then, the complexes were subjected to in vitro maturation (IVM) for 18 or 23 hours, in an inhibitor-free medium supplemented with gonadotropins. The evaluation of nuclear configuration by Hoescht staining, under a fluorescence-inverted microscope, showed that 88.7% of the lamb oocytes treated with roscovitine remained at the GV stage, as observed for the immature ones (97.3%) stained after collection. The inhibitory action was reversible; however, the proportion of oocytes (83.3%) at the metaphase-II stage, after 23 hours of IVM, was significantly higher than that observed after 18 hours (29.5%), in which meiosis was still in progression with 34.2% oocytes at metaphase-I, 11.6% oocytes at anaphase-I, and 18.5% oocytes at telophase-I. Roscovitine is efficient to arrest the nuclear maturation in oocytes from prepubertal sheep; however, despite the reversibility, meiosis progression is delayed, requiring more time to be completed.
Highlights
In vitro embryo production (IVP) from oocytes of prepubertal female sheep (Ovis aries) is a promising tool for the agribusiness, since it allows of reproductive life anticipation of the oocyte donor, shortening the generation interval, increasing genetic gains, and providing higher economic returns (Paramio & Izquierdo, 2016)
Evidences indicated that the cyclic guanosine monophosphate, produced by granulosa cells, maintain high levels of cyclic adenosine monophosphate in the oocyte, preventing the activation of the maturation-promoting factor (MPF)
In gilts, more than 90% oocytes were at germinal vesicle (GV), after culture for 22 hours in 25 μmol L-1 roscovitine (Marchal et al, 2001), and 48 hours in 50 μmol L-1 roscovitine (Romar & Funahashi, 2006), a low proportion of oocytes from prepubertal goats remained arrested at this stage (
Summary
In vitro embryo production (IVP) from oocytes of prepubertal female sheep (Ovis aries) is a promising tool for the agribusiness, since it allows of reproductive life anticipation of the oocyte donor, shortening the generation interval, increasing genetic gains, and providing higher economic returns (Paramio & Izquierdo, 2016). The in vitro developmental competence of prepubertal oocytes in sheep is still lower than that of adult ones (Reader et al, 2014). This fact can be attributed to ultrastructural and functional deficiencies related to incomplete cytoplasmic maturation (Salamone et al, 2001; Jimenez-Macedo et al, 2006), such as a reduced synthetic activity (Ledda et al, 2001), lower-mRNAs storage (Leoni et al, 2007), microtubules disorganization (Velilla et al, 2005), and altered organelles distribution (Velilla et al, 2006). Oocytes remain blocked at the germinal vesicle (GV) (Jaffe & Egbert, 2017)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
