Induction of superovulation using inhibin antiserum and competence of embryo development in wild large Japanese field mice (Apodemus speciosus)

Abstract

Seasonally, bred wild mice provide a unique bioresource, with high genetic diversity that differs from wild‐derived mice and laboratory mice. This study aimed to establish an alternative superovulation method using wild large Japanese field mice (Apodemus speciosus) as the model species. Specifically, we investigated how the application of inhibin antiserum and equine chorionic gonadotropin (IASe) during both the reproductive and non‐reproductive seasons impact the ovulation rate and competence of embryo development after in vitro fertilization (IVF) with fresh and cryopreserved sperm. When the wild mice were superovulated by injecting eCG followed by human chorionic gonadotropin (hCG), few oocytes were collected during the reproductive and non‐reproductive seasons. In comparison, the number of ovulated oocytes was dramatically enhanced by the administration of IASe, followed by isolation of ovulated oocytes 24 hr after 30 IU hCG administration. The IVF oocytes that were in vitro cultured (IVC) with medium containing serum further developed to the 2‐ and/or 4‐cell stage using both fresh and frozen‐thawed sperm. In conclusion, we successfully established an alternative protocol for collecting ovulated oocytes from wild large Japanese field mice by administering IASe and hCG during both the reproductive and non‐reproductive seasons. This study is the first to develop IVF–IVC wild large Japanese field mice beyond the 2‐ and/or 4‐cell stage in vitro using fresh and cryopreserved sperm. This approach could be used in other species of wild or endangered mice to reduce the number of animals used for experiments, or in maintaining stocks of germ cells or embryos.

Morphological reproductive characteristics of testes and fertilization capacity of cryopreserved sperm after the Fukushima accident in raccoon (Procyon lotor)

“…Following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, large amounts of radioactive substances, particularly volatile elements, such as radioactive iodine, caesium and tellurium, were released into the environment. The ex‐evacuation zone comprises a 20‐km‐radius area around the FDNPP, from which we have established an archive system of livestock and wild animals (Ariyoshi et al., 2018; Fukuda et al., 2013; Fukuda et al., 2015; Fukuda et al., 2016; Koarai et al., 2016; Koarai et al., 2018; Koarai et al, 2020; Ohdaira et al., 2019; Suzuki et al, 2020; Takahashi et al., 2015; Takino et al., 2017; Urushihara et al., 2016; Meguro et al., 2019; Urushihara et al., 2018; Yamashiro et al., 2013; Yamashiro et al., 2014; Yamashiro et al., 2015).…”

Histological analysis of implantation embryos in large Japanese field mouse (Apodemus speciosus) and estimation of developmental stage

“…Methods of rearing and breeding the A. speciosus were being developed [9], and an atlas of embryonic development of A. speciosus could be created in the future. Furthermore, the whole genome sequence of A. speciosus had already been published [5], and A. speciosus can be established as a novel experimental rodent with the following characteristics; 1. rodents with seasonality in spermatogenesis and reproduction [4,8], 2. with different chromosome numbers within the same species, 3. pioneering developmental engineering [2,6]. This present study will be important as a morphological report of on point in the developmental atlas of A. speciosus.…”

Archiving genetically altered animals: a review of cryopreservation and recovery methods for genome edited animals

“…More recent papers, however, show its effectiveness across a range of strains, and its potential for rescuing difficult models should not be overlooked. 44,45…”