Protein Localization of Epidermal Growth Factor in Sheep Ovaries and Improvement of Follicle Survival and Antrum Formation In Vitro

The aims of this study were to characterize EGF protein expression in ovine ovaries and to verify the effect of EGF on the in vitro development of isolated pre‐antral follicles. After collection, ovarian tissue was fixed for immunohistochemical analysis. Additional pairs of ovaries were collected, and secondary follicles were cultured for 18 days in α‐MEM⁺ (control) alone or supplemented with EGF (1, 10 or 50 ng/ml). The immunostaining for EGF was observed in oocytes from pre‐antral and antral follicles, in granulosa cells of primary and secondary follicles, as well as in cumulus and mural cells of antral follicles. After 18 days, the results showed that treatment with 50 ng/ml EGF significantly increased the percentage of morphologically normal follicles compared with the control group (α‐MEM⁺) and significantly reduced the precocious extrusion of oocytes and increased the percentage of antral follicles compared with the control and 1 ng/ml EGF. All the treatments induced a progressive and significant increase of the follicular diameter throughout the period of culture. However, there were no significant differences in follicular diameter or in the daily growth rate among treatments. In conclusion, this study demonstrated the presence of EGF in ovine ovaries. Moreover, 50 ng/ml EGF increased the percentage of normal follicles and improved antrum formation in isolated ovine follicles after 18 days of in vitro culture.     

Expression of CYP26b1 and Related Retinoic Acid Signalling Molecules in Young,Peripubertal and Adult Dog Testis

The objective of the study was to elucidate mRNA expression of CYP26b1 (cytochrome P450, family 26, subfamily B, polypeptide 1) and signalling molecules ALDH1 (aldehyde dehydrogenase 1), CRABPII (cellular retinoic acid‐binding protein II), RARα (retinoic acid receptor alpha) and STRA8 (stimulated by retinoic acid gene 8) in dog testis from different post‐natal developmental ages. Testicular tissue samples were collected from medium‐sized mixed breed dogs at different ages such as young (<4 months; N = 4), peripubertal (4–8 months; N = 3) and adult (>8 months; N = 4) were used to evaluate relative mRNA expression. Genes of RA‐degrading enzyme CYP26b1, ALDH1 involved in RA synthesis and genes of carrier protein CRABPII involved in RA metabolism were turned on during the post‐natal testicular development in dogs. Their expression pattern differs at different developmental ages (p < 0.05), and the levels of mRNA expression were compensated towards a normal developmental response for the sexual maturity and continuous spermatogenesis. The mRNA expression of RARα, one of the RA receptors participates in RA signalling in connection to spermatogenesis, was recorded in young and adult stages at varying degree. STRA8 is one of the responsive genes with regard to meiosis, and this functional gene product was expressed in all ages with the changing level (p < 0.01). In summary, the expression pattern of RA signalling molecules differed from young to adult ages, and it is expected that these changes are to compensate towards a normal developmental response for the sexual maturity and continuous spermatogenesis.     

Electronic States of KxC60: Insulating, Metallic, and Superconducting Character

The recent report of electrical conductivity in the alkali metal fullerides and the discovery of superconductivity at 18 K for KxC(60) has raised fundamental questions about the electronic states on either side of the Fermi level, their occupancy with K intercalation, and the mechanism of superconductivity. Direct photoemission evidence is presented of filling of bands derived from the lowest unoccupied molecular orbital as a function of K incorporation for the metallic and insulating phases. This filling is not rigid band-like, and it reflects disorder in the K sites. Theoretical analysis indicates that KxC(60) is a strong coupling superconductor, and we suggest that the enhanced electron-phonon interaction is related to the unique hybridization of the C sp-derived states.