Abstract
BackgroundReproductive biotechnologies in dromedary camel (Camelus dromedarius) are less developed than in other livestock species. The in vitro maturation (IVM) technology is a fundamental step for in vitro embryo production (IVP), and its optimization could represent a way to increase the success rate of IVP. The aim of the present study was to investigate the bioenergy/oxidative status of dromedary camel oocytes before and after IVM by confocal microscopy 3D imaging.MethodsOocytes were retrieved by slicing ovaries collected at local slaughterhouses. Recovered oocytes were examined before and after IVM culture for nuclear chromatin configuration and bioenergy/oxidative status, expressed as mitochondria (mt) distribution and activity, intracellular Reactive Oxygen Species (ROS) levels and distribution and mt/ROS colocalization.ResultsThe mean recovery rate was 6 oocytes/ovary. After IVM, 61% of oocytes resumed meiosis and 36% reached the Metaphase II stage (MII). Oocyte bioenergy/redox confocal characterization revealed changes upon meiosis progression. Immature oocytes at the germinal vesicle (GV) stage were characterised by prevailing homogeneous mt distribution in small aggregates while MI and MII oocytes showed significantly higher rates of pericortical mt distribution organized in tubular networks (P < 0.05). Increased mt activity in MI (P < 0.001) and MII (P < 0.01) oocytes compared to GV stage oocytes was also observed. At any meiotic stage, homogeneous distribution of intracellular ROS was observed. Intracellular ROS levels also increased in MI (P < 0.01) and MII (P < 0.05) oocytes compared to GV stage oocytes. The mt/ROS colocalization signal increased in MI oocytes (P < 0.05).ConclusionsThis study provides indications that qualitative and quantitative indicators of bioenergy and oxidative status in dromedary camel oocytes are modified in relation with oocyte meiotic stage. These data may increase the knowledge of camel oocyte physiology, in order to enhance the efficiency of IVP procedures.
Highlights
Reproductive biotechnologies in dromedary camel (Camelus dromedarius) are less developed than in other livestock species
After in vitro maturation (IVM), 41 oocytes were at the metaphase I (MI) stage (25%) and 59 oocytes reached the Metaphase II stage (MII) stage (36%)
Remaining oocytes, which were found at the germinal vesicle (GV) stage (n = 34, 20%) or showing degenerated chromatin configurations (n = 31, 19%) after IVM culture, were excluded from confocal analysis
Summary
Reproductive biotechnologies in dromedary camel (Camelus dromedarius) are less developed than in other livestock species. The dromedary camel (Camelus dromedarius) is a seasonal polyestrous breeder and reproductive activity is limited to the coolest month of the year [1]. Local environmental factors such as rainfall, external temperature, and nutrition, rather than photoperiod, are supposed to. In order to optimize breeding programs in this species, monitoring and increasing efficiency plans of the reproductive activity are desirable To this end, application of assisted reproductive technologies (ARTs), such as artificial insemination, oocyte in vitro maturation (IVM) and fertilization, oocyte and embryo cryopreservation, embryo transfer and cloning could provide a substantial opportunity to improve reproductive efficiency and genetic performance and to better understand factors regulating reproductive activity in this species.
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