Abstract
Simple SummaryThe development of in vitro embryo production (IVP) in wild species, such as Iberian red deer, can become a daunting challenge since prolonged ovary transport times to the laboratory are often unavoidable. This may have detrimental effects on the quality and developmental capacity of oocytes. We evaluated the effect of supplementing the ovary transport medium with the antioxidant melatonin and observed an increased level of oocyte intracellular reduced glutathione content. Moreover, melatonin enhanced cleavage and blastocyst rates and had a positive effect on embryo quality in terms of the expression of essential embryo development-related genes. In conclusion, the addition of melatonin to the ovary storage medium could mitigate the negative impacts that long transport times may have on oocyte developmental competence and quality of the resulting blastocysts in Iberian red deer.A major limiting factor for the development of in vitro embryo production (IVP) in wild species, such as Iberian red deer, compared to livestock animals is the poor availability and limited access to biological material. Thus, the use of post-mortem ovaries from slaughtered animals represent a source of oocytes for the large scale production of embryos needed for research and to improve the efficiency of IVP. However, these oocytes are not as developmentally competent as their in vivo counterparts. Moreover, oocytes are usually obtained from ovaries that have been transported for long distances, which may also affect their quality. In order to overcome the issues associated with prolonged storage times of post-mortem material, in this study we examined the effect of melatonin supplementation to the ovary transport medium on oocyte quality, embryo yield, and blastocyst quality in Iberian red deer. When necessary, sheep was used as an experimental model due to the large number of samples required for analysis of oocyte quality parameters. Oocytes were in vitro matured and assessed for early apoptosis; DNA fragmentation; reactive oxygen species (ROS); reduced glutathione (GSH) content, mitochondrial membrane potential, and distribution; and relative abundance of mRNA transcript levels. After in vitro fertilization, embryo rates and blastocyst quality were also investigated. The results revealed that melatonin treatment significantly increased intracellular level of GSH in sheep oocytes. Moreover, the percentage of cleavage and blastocyst yield in red deer was greater compared to the Control group and there was lower abundance of oxidative stress- and apoptosis-related SHC1, TP53, and AKR1B1 mRNA transcripts in blastocysts for the Melatonin group. In conclusion, the supplementation of melatonin to the ovary storage medium had a positive effect on the developmental competence and quality of resulting blastocysts in Iberian red deer.
Highlights
The Iberian red deer (Cervus elaphus hispanicus) is a wild subspecies of red deer that only inhabits the Iberian Peninsula
The supplementation of melatonin to the ovary storage medium had a positive effect on the developmental competence and blastocyst quality in Iberian red deer
As far as we are concerned, this is the first study to demonstrate a distinctive relationship between ovary preservation media composition and the relative mRNA abundance of several important genes in resulting blastocysts after in vitro embryo production (IVP)
Summary
The Iberian red deer (Cervus elaphus hispanicus) is a wild subspecies of red deer that only inhabits the Iberian Peninsula. The use of assisted reproduction technologies, like in vitro embryo production (IVP), in red deer had been previously acknowledged [1,2] and may play an important role for the purpose of improving individuals for trophy hunting and ensuring genetic advancement and avoidance of inbreeding depression as a result of the genetic isolation of wild populations within fenced game estates [2,3]. In the case of Iberian red deer it is possible to obtain ovaries from animals slaughtered in abattoirs or slaughterhouse-like designated facilities. These places are usually far from laboratories. In vitro embryos have been successfully produced in this deer subspecies from dead animals [2], blastocyst rates remain low compared to other small ruminants like sheep [9]
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