Mouse in vitro fertilization and embryo culture were performed in media prepared with five different water preparations. The results of the experiments improved with the frequency of distillation. Each water preparation was analyzed by the measurement of the electrical conductivities and inorganic ion concentrations and by high-performance liquid chromatography to examine the mutual relation between water quality and the method of water purification. The best results were obtained with Milli-Q water, which had the lowest concentration of inorganic ions and organic compounds. On the contrary, unexpected contamination by organic compounds and zinc ions occurred after multiple distillation, possibly leached from the glassware and silicon tube. The hatching rate seemed to be an appropriate indicator to assess the biological qualities of media for the development of embryos cultured in vitro.

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In this study, the magnetically oriented microcrystal suspension (MOMS) method is combined with the shutterless continuous rotation method. In the MOMS method, the suspension has to be rotated to maintain the three‐dimensional orientation of microcrystals. This means that it is compatible with the continuous rotation method, which also utilizes sample rotation. The time constants of the two methods should match to allow their successful combination. The conditions required for the MOMS method for combination with the continuous rotation method are investigated. Experiments are performed with a complementary metal–oxide semiconductor (CMOS) detector and the restriction imposed on the time constant for the MOMS method by the continuous rotation method is examined. The combination of these two methods is a promising approach for realizing the structure analyses of biomolecules from their microcrystalline powders.

Microcrystals of lysozyme (5-10 mm) suspended in an ultraviolet-light-curable resin were aligned three dimensionally under a non-uniformly rotating magnetic field, and then the resin was consolidated by photopolymerization to obtain a composite in which microcrystals were three-dimensionally aligned. The obtained composite (MOMA: magnetically oriented microcrystal array) was analysed using a synchrotron X-ray source. A resolution of 1.8 Å was obtained, which is in marked contrast to the resolution of 3 Å previously reported for these composites, obtained by using an in-house X-ray diffractometer. These results show that a combination of MOMAs with conventional synchrotron beamlines may have valuable potential for crystal analyses of protein crystals that do not grow to larger sizes.

To investigate the mechanism of the blocking effect of sperm immobilizing antibodies on human fertilization, an in vitro zona penetration test was carried out using media containing the IgG fraction extracted from sperm immobilizing antibody-negative or -positive serum. The sperm penetration rate of the test was 100% (6/6) when spermatozoa were treated with the IgG fraction derived from sperm immobilizing antibody-negative serum, whereas it was only 17% (1/6) when spermatozoa were treated with the IgG fraction derived from sperm immobilizing antibody-positive serum. Electron microscopic observation of the sperm immobilizing antibody-negative and -positive serum-treated spermatozoa showed that the number of acrosome-reacted spermatozoa was significantly greater in the sperm immobilizing antibody-negative serum than in the antibody-positive serum. Therefore, it appears that one of the blocking mechanisms of the spermatozoal penetration of the zona pellucida by sperm immobilizing antibodies may be due to inhibition of the acrosome reaction in the spermatozoa.

Protein microcrystals magnetically aligned in D2O hydrogels were subjected to neutron diffraction measurements, and reflections were observed for the first time to a resolution of 3.4 Å from lysozyme microcrystals (∼10 × 10 × 50 µm). This result demonstrated the possibility that magnetically oriented microcrystals consolidated in D2O gels may provide a promising means to obtain single-crystal neutron diffraction from proteins that do not crystallize at the sizes required for neutron diffraction structure determination. In addition, lysozyme microcrystals aligned in H2O hydrogels allowed structure determination at a resolution of 1.76 Å at room temperature by X-ray diffraction. The use of gels has advantages since the microcrystals are measured under hydrated conditions.

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