Melatonin promotes the development of sheep transgenic cloned embryos by protecting donor and recipient cells

Melatonin as a multifunctional modulator: emerging insights into its role in health, reproductive efficiency, and productive performance in livestock

Melatonin, a pleiotropic hormone plays a vital role in enhancing livestock performance not only by regulating circadian rhythms but also by exhibiting antioxidant, immunomodulatory, and metabolic regulatory effects that collectively improve resilience, fertility, and productivity. Melatonin's synthesis is predominantly influenced by light exposure, with increased production in darkness; however, factors such as diet and health status further modulate its levels. By helping animals adapt to environmental stressors, melatonin boosts immune responses, mitigates chronic illnesses, and optimizes production efficiency. Its regulatory influence extends to the hypothalamic-pituitary-gonadal (HPG) axis, enhancing hormone secretion, synchronizing estrous cycles, and improving embryo viability. This results in improved reproductive outcomes through the protection of gametes, increased sperm motility, and enhanced oocyte quality, all of which benefit the fertilization process. Additionally, melatonin positively impacts productive performance, promoting muscle growth, development, and optimizing milk yield and composition through its interaction with metabolic and endocrine systems. As ongoing research continues to uncover its broader physiological effects, melatonin supplementation emerges as a promising approach to improving livestock welfare, productivity, and sustainability in modern animal husbandry.

iSCNT embryo culture system for restoration of Cervus nippon hortulorum, presumed to be sika deer in the Korean Peninsula

Sika deer inhabiting South Korea became extinct when the last individual was captured on Jeju Island in Korea in 1920 owing to the Japanese seawater relief business, but it is believed that the same subspecies (Cervus nippon hortulorum) inhabits North Korea and the Russian Primorskaya state. In our study, mt-DNA was used to analyze the genetic resources of sika deer in the vicinity of the Korean Peninsula to restore the extinct species of continental deer on the Korean Peninsula. In addition, iSCNT was performed using cells to analyze the potential for restoration of extinct species. The somatic cells of sika deer came from tissues of individuals presumed to be Korean Peninsula sika deer inhabiting the neighboring areas of the Primorskaya state and North Korea. After sequencing 5 deer samples through mt-DNA isolation and PCR, BLAST analysis showed high matching rates for Cervus nippon hortulorum. This shows that the sika deer found near the Russian Primorsky Territory, inhabiting the region adjacent to the Korean Peninsula, can be classified as a subspecies of Cervus nippon hortulorum. The method for producing cloned embryos for species restoration confirmed that iSCNT-embryos developed smoothly when using porcine oocytes. In addition, the stimulation of endometrial cells and progesterone in the IVC system expanded the blastocyst cavity and enabled stable development of energy metabolism and morphological changes in the blastocyst. Our results confirmed that the individual presumed to be a continental deer in the Korean Peninsula had the same genotype as Cervus nippon hortulorum, and securing the individual's cell-line could restore the species through replication and produce a stable iSCNT embryo.

Role of Melatonin in Bovine Reproductive Biotechnology

Melatonin has profound antioxidant activity and numerous functions in humans as well as in livestock and poultry. Additionally, melatonin plays an important role in regulating the biological rhythms of animals. Combining melatonin with scientific breeding management has considerable potential for optimizing animal physiological functions, but this idea still faces significant challenges. In this review, we summarized the beneficial effects of melatonin supplementation on physiology and reproductive processes in cattle, including granulosa cells, oocytes, circadian rhythm, stress, inflammation, testicular function, spermatogenesis, and semen cryopreservation. There is much emerging evidence that melatonin can profoundly affect cattle. In the future, we hope that melatonin can not only be applied to cattle, but can also be used to safely and effectively improve the efficiency of animal husbandry.

In Vitro-Produced Equine Blastocysts Exhibit Greater Dispersal and Intermingling of Inner Cell Mass Cells than In Vivo Embryos

In vitro production (IVP) of equine embryos is increasingly popular in clinical practice but suffers from higher incidences of early embryonic loss and monozygotic twin development than transfer of in vivo derived (IVD) embryos. Early embryo development is classically characterized by two cell fate decisions: (1) first, trophectoderm (TE) cells differentiate from inner cell mass (ICM); (2) second, the ICM segregates into epiblast (EPI) and primitive endoderm (PE). This study examined the influence of embryo type (IVD versus IVP), developmental stage or speed, and culture environment (in vitro versus in vivo) on the expression of the cell lineage markers, CDX-2 (TE), SOX-2 (EPI) and GATA-6 (PE). The numbers and distribution of cells expressing the three lineage markers were evaluated in day 7 IVD early blastocysts (n = 3) and blastocysts (n = 3), and in IVP embryos first identified as blastocysts after 7 (fast development, n = 5) or 9 (slow development, n = 9) days. Furthermore, day 7 IVP blastocysts were examined after additional culture for 2 days either in vitro (n = 5) or in vivo (after transfer into recipient mares, n = 3). In IVD early blastocysts, SOX-2 positive cells were encircled by GATA-6 positive cells in the ICM, with SOX-2 co-expression in some presumed PE cells. In IVD blastocysts, SOX-2 expression was exclusive to the compacted presumptive EPI, while GATA-6 and CDX-2 expression were consistent with PE and TE specification, respectively. In IVP blastocysts, SOX-2 and GATA-6 positive cells were intermingled and relatively dispersed, and co-expression of SOX-2 or GATA-6 was evident in some CDX-2 positive TE cells. IVP blastocysts had lower TE and total cell numbers than IVD blastocysts and displayed larger mean inter-EPI cell distances; these features were more pronounced in slower-developing IVP blastocysts. Transferring IVP blastocysts into recipient mares led to the compaction of SOX-2 positive cells into a presumptive EPI, whereas extended in vitro culture did not. In conclusion, IVP equine embryos have a poorly compacted ICM with intermingled EPI and PE cells; features accentuated in slowly developing embryos but remedied by transfer to a recipient mare.

Molecular Mechanism and Application of Somatic Cell Cloning in Mammals-Past, Present and Future

Thus far, nearly 25 mammalian species have been cloned by intra- or interspecies somatic cell nuclear transfer (SCNT) [...].

Exogenous Melatonin in the Culture Medium Does Not Affect the Development of In Vivo-Derived Pig Embryos but Substantially Improves the Quality of In Vitro-Produced Embryos

Cloned and transgenic pigs are relevant human disease models and serve as potential donors for regenerative medicine and xenotransplantation. These technologies demand oocytes and embryos of good quality. However, the current protocols for in vitro production (IVP) of pig embryos give reduced blastocyst efficiency and embryo quality compared to in vivo controls. This is likely due to culture conditions jeopardizing embryonic homeostasis including the effect of reactive oxygen species (ROS) influence. In this study, the antioxidant melatonin (1 nM) in the maturation medium, fertilization medium, or both media was ineffective in enhancing fertilization or embryonic development parameters of in vitro fertilized oocytes. Supplementation of melatonin in the fertilization medium also had no effect on sperm function. In contrast, the addition of melatonin to the embryo culture medium accelerated the timing of embryonic development and increased the percentages of cleaved embryos and presumed zygotes that developed to the blastocyst stage. Furthermore, it increased the number of inner mass cells and the inner mass cell/total cell number ratio per blastocyst while increasing intracellular glutathione and reducing ROS and DNA damage levels in embryos. Contrarily, the addition of melatonin to the embryo culture medium had no evident effect on in vivo-derived embryos, including the developmental capacity and the quality of in vivo-derived 4-cell embryos or the percentage of genome-edited in vivo-derived zygotes achieving the blastocyst stage. In conclusion, exogenous melatonin in the embryo culture medium enhances the development and quality of in vitro-derived embryos but not in in vivo-derived embryos. Exogenous melatonin is thus recommended during embryo culture of oocytes matured and fertilized in vitro for improving porcine IVP efficiency.