Oxidation of thiol groups in membrane proteins inhibits the fertilization ability and motility of sperm by suppressing calcium influx.

The redox state of thiol groups derived from cysteine residues in proteins regulates cellular functions. Changes in the redox state of thiol groups in the epididymis are involved in sperm maturation. Furthermore, the redox state of thiol groups in proteins changes during the process of sperm capacitation.

In vivo fertilization improved the cryotolerance and developmental ability of vitrified-warmed rat fertilized oocytes.

The cryopreservation of rat embryos is useful for efficiently archiving rat resources in bioresource repositories. The cryopreserved fertilized oocytes can be quickly reanimated to rats with homozygous mutations using embryo transfer. In addition, cryopreserved rat fertilized oocytes are easier to transport than live animals.

Efficient breeding system of infertile Niemann-Pick disease type C model mice by in vitro fertilization and embryo transfer.

Niemann-Pick disease type C (NPC) is a lethal genetic disease with mutations in or gene. -deficient () mice have been used as a model for NPC pathogenesis to develop novel therapies for NPC. However, mice are infertile; thus, securing sufficient numbers for translational research is difficult.

High-concentration bovine serum albumin enhances fertilization ability of cold-stored rat sperm.

Cold transport of the cauda epididymides is a useful technique for shipping laboratory rat sperm. Cold transport of rat sperm avoids potential risks of microbiological infection, animal escape or death, and animal welfare issues. Previously, we reported that a cold-storage solution containing dimethyl sulfoxide and quercetin maintained the fertility of cold-stored rat sperm.

Time elapsed between ovulation and insemination determines the quality of fertilized rat oocytes.

Genetically modified rats are valuable models in human disease research. We recently developed an improved system for rat sperm cryopreservation and in vitro fertilization (IVF) that facilitates the efficient production and preservation of genetically modified rats. In the IVF procedure performed using frozen-thawed rat sperm, the IVF schedule is fixed to ensure timely hormone administration and oocyte collection.

Synchronization of the ovulation and copulation timings increased the number of in vivo fertilized oocytes in superovulated female mice.

The number of sperm that reaches the oocytes in mammalian species is limited. In mice, 8-10 oocytes are ovulated, a similar number of sperm reaches the oocytes, and nearly all oocytes are fertilized via natural mating. Meanwhile, our improved superovulation technique (ultrasuperovulation: administration of inhibin antiserum and equine chorionic gonadotropin [IASe]) produced 100 oocytes from a single female C57BL/6 mouse but resulted in only approximately 20 fertilized oocytes via mating.

Dimethyl-α-cyclodextrin induces capacitation by removing phospholipids from the plasma membrane of mouse sperm†.

Capacitation is an important event in the completion of fertilization by mammalian sperm. Cholesterol efflux is a trigger of capacitation. In general, cholesterol acceptors of albumin and β-cyclodextrins are used to induce capacitation during in vitro fertilization.

Observation of the in vitro fertilization process in living oocytes using frozen-thawed sperm in rats.

Previous studies have observed the fertilization process in rats using whole-mount preparation at different time-points after insemination. However, very few reports have described the various events during the fertilization process using an inverted microscope without whole-mount. Moreover, to the best of our knowledge, no reports have described the observation of changes in sperm motility associated with sperm penetration into oocytes.

Optimized protocols for sperm cryopreservation and in vitro fertilization in the rat.

Laboratory rats have been used in biomedical research for over 170 years. Recently, genome editing technology has facilitated the generation of genetically modified rats worldwide. This development has increased the demand for efficient preservation and production of rat resources.

Quercetin-treated rat sperm enables refrigerated transport with motility and fertility for five days.

Shipment of laboratory rats between animal facilities is frequently performed using special containers. However, the shipment of live animals is associated with potential risks of infectious diseases, escape and death during shipment and animal welfare issues. The transport of cold-stored sperm avoids such risks; however, there have been no reports on cold storage of rat sperm.

Cryopreservation of mouse resources.

The cryopreservation of sperm and embryos is useful to efficiently archive valuable resources of genetically engineered mice. Till date, more than 60,000 strains of genetically engineered mice have been archived in mouse banks worldwide. Researchers can request for the archived mouse strains for their research projects.

Simple transport and cryopreservation of cold-stored mouse embryos.

The cold storage of two-cell embryos is a useful technique for transporting genetically engineered mice without the shipment of live animals. However, the developmental ability of cold-stored embryos decreases with prolonged storage periods. Therefore, the transported embryos must be readily transferred to recipient mice upon arrival.

Author Correction: Establishment of sperm cryopreservation and in vitro fertilisation protocols for rats.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Establishment of sperm cryopreservation and in vitro fertilisation protocols for rats.

Recently, genome-editing tools have come into common use in the field of rat research, and consequently, many genetically modified rat strains have been preserved and archived as frozen embryos. Although there have been many reports published on the topic of rat sperm cryopreservation, no report has yet provided satisfactory and acceptable protocols for the cryopreservation of rat sperm. In this study, we developed methods for both the cryopreservation of transgenic rat sperm and in vitro fertilisation using frozen sperm, which yielded high fertilisation rates.

Prolonged exposure to hyaluronidase decreases the fertilization and development rates of fresh and cryopreserved mouse oocytes.

Hyaluronidase is generally used to remove cumulus cells from mouse oocytes before oocyte cryopreservation, intracytoplasmic sperm injection or DNA injection. In general, use of cumulus-free mouse oocytes decreases in vitro fertilizing ability compared with cumulus-surrounded oocytes. The effect of hyaluronidase exposure on the quality of mouse oocytes is not fully understood.

Establishment of a transport system for mouse epididymal sperm at refrigerated temperatures.

The exchange of genetically engineered mouse strains between research facilities requires transporting fresh mouse sperm under refrigerated temperatures. Although sperm generally maintains fertility for 48 h at cold temperatures, in vitro fertilization rates of C57BL/6 mouse sperm are low after 48-h cold storage. Furthermore, 48 h is often not sufficient for the specimens to reach their destinations.