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Summary.Cattle follicular oocytes were collected from the ovarian follicles and cultured for 28 h in m-KRB solution in a CO2incubator (5% CO2in air at 37°C, 95% humidity). After further culture for 15–18 h with spermatozoa, 78·6% of the oocytes had matured to the second metaphase. The highest fertilization rates (36–58%) were obtained when spermatozoa were collected 1 day before insemination, kept for 14–18 h at 20°C in a test tube (10 × 108/ml), preincubated in m-KRB solution (1–1·2 × 108/ml) in a CO2incubator for 0–12 h, and then inseminated at a concentration of 1·5–2·0 × 106/ml. The optimum period of preincubation in the CO2incubator was 8 h: 6/15 denuded oocytes (40%) were fertilized with spermatozoa preincubated for 8 h. No polyspermic fertilization was observed in any of the 139 penetrated oocytes. When spermatozoa were preincubated in the uteri of oestrous cows and gilts for 4–4.5 h instead of the m-KRB solution, the fertilization rates were 80 and 86%, respectively. However, in this system, 13 and 24% of the penetrated oocytes were polyspermic. These results indicate that ejaculated bull spermatozoa can be capacitated in a chemically defined isotonic medium, and about half of the oocytes matured in culture are normally fertilized in vitro.

Lysine-2,3-aminomutase purified from Clostridium subterminale SB4 is reported to exhibit an apparent subunit Mr of 48,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the undenatured enzyme exhibits an apparent Mr of 285,000, as determined by electrophoretic mobility and gel permeation chromatography (Chirpich, T. P., Zappia, V., Costilow, R. N., and Barker, H. A. (1970) J. Biol. Chem. 245, 1778-1789). The diffusion coefficient of the enzyme is 3.36 x 10(-7) cm2/s, as determined by quasielastic light scattering. The overall Mr calculated from the diffusion coefficient and the published sedimentation coefficient is 259,000. Cross-linking experiments using glutaraldehyde and dithiobis(succinimidylpropionate) as cross-linking reagents indicate that the enzyme has a hexameric quaternary structure. The number of major cyanogen bromide peptides, compared with the methionine content of the enzyme, is consistent with the subunits being identical, and isoelectric focusing also is consistent with identical subunits. The circular dichroism of the enzyme indicates that it is a highly ordered structure, which is estimated to consist of 26% alpha-helix and 48% beta-sheet. The enzyme contains approximately six molecules of pyridoxal 5‘-phosphate per hexamer, as determined by the phenyl-hydrazine method. The amino acid analysis of the enzyme, after performic acid oxidation, indicates that it contains approximately 13 cysteine residues per subunit. Six sulfhydryl groups per hexamer react readily with 5,5‘-dithiobis-2-nitrobenzoate, indicating that one sulfhydryl group is accessible per subunit.

The synthesis and crystal structures of binuclear silver(I) and mercury(II) metallocyclophanes with N-heterocyclic carbene linkages by the π−π stacking interaction are described.

The transfer free energies of amino acid side chains from water to N-methylacetamide have been determined and compared with those obtained from other model systems. Although the process of transfer from water to N-methylacetamide represents transfer from a lower dielectric phase to a higher dielectric phase, the transfer free energies of most of the amino acid side chains are nearly the same as those obtained from the water to ethanol system. Among the apolar side chains studied, only the transfer free energies of methionine and the aromatic side chains are apparently influenced to some extent by the polarity of the organic solvent phase. The transfer free energies of the neutral polar side chains also exhibit significant dependence on solvent polarity. The van't Hoff plots for most of the apolar side chains exhibit nonlinear curves, indicating that the enthalpy of transfer from water to N-methylacetamide is temperature-dependent. It is suggested that to assess the contribution of the hydrophobic free energy to the stability of globular proteins, it is probably not necessary to account for variation in the internal environment of the protein.

Kuter: Daiichi Sankyo: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Merck Sharp Dohme: Consultancy, Honoraria; Up-to-Date: Consultancy, Honoraria, Patents & Royalties: 3 Up-to-Date chapters; Caremark: Consultancy, Honoraria; Bristol Myers Squibb (BMS): Consultancy, Honoraria, Research Funding; Platelet Disorder Support Association: Consultancy, Honoraria; Alnylam: Consultancy, Honoraria, Research Funding; Zafgen: Consultancy, Honoraria; UCB: Consultancy, Honoraria; Genzyme: Consultancy, Honoraria; Kezar: Research Funding; Principia: Consultancy, Honoraria, Research Funding; Shire: Consultancy, Honoraria; Takeda (Bioverativ): Consultancy, Honoraria, Research Funding; Kyowa-Kirin: Consultancy, Honoraria; Momenta: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Argenx: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria, Research Funding; Actelion (Syntimmune): Consultancy, Honoraria, Research Funding; Dova: Consultancy, Honoraria; Protalix: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Protalex: Consultancy, Honoraria, Research Funding; Shinogi: Consultancy, Honoraria; Rigel: Consultancy, Honoraria, Research Funding. Al-Samkari:Agios: Consultancy, Research Funding; Dova: Consultancy, Research Funding; Moderna: Consultancy.

The effects of accelerated continuous cooling and isothermal heat treatment process on the microstructure and mechanical properties of medium carbon bainitic steels was investigated to find an alternative process of the conventional austempering treatment process. Two kinds of medium carbon steel billets melted by Vacuum Induction Melting (VIM) were hot rolled to the thickness of 6[?]12mm plates and accelerated-cooled to predetermined temperatures and then isothermal heat treatment was conducted immediately. For quantitative analysis of microstructures, the fraction of constituent phases such as retained austenite, martensite, and bainite was measured by XRD and dilatometry. A series of hardness, tensile, and impact tests was conducted to evaluate the mechanical properties of the plates. As the finish cooling temperature increased, the fraction of retained austenite increased and the fraction of martensite and bainite decreased due to the differences in carbon diffusion and transformation kinetics during isothermal heat treatment process. Microstructural observation results showed that the lath/block thickness and fraction of bainite and martensite were mainly dependent on austempering temperature and time. The thickness of bainite and the fraction of martensite were found to be the major factors influencing mechanical properties of the present medium-carbon nanostructured bainitic steels.

Co(II), Mn(II), Cu(II) and Cr(III) salen type complexes were synthesized in situ in Y zeolite by the reaction of ion-exchanged metal ions with the flexible ligand molecules that had diffused into the cavities. Data of characterization indicates the formation of metal salen complexes in the pores without affecting the zeolite framework structure, the absence of any extraneous species and the geometry of encapsulated complexes. The catalytic activity results show that Cosalcyen Y exhibited higher catalytic activity in the water phase selective oxidation of benzyl alcohol, which could be attributed to their geometry and the steric environment of the metal actives sites.

The characteristics of diffraction efficiency and spectral bandwidth of dichromated gelatin reflection holograms formed by a modified processing method are presented.

We are concerned with new simplified procedures for obtaining sufficient initial bias hardness of dichromated gelatin film by inserting the dehydration process before exposure.

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