The sexual maturation occurred by the changes of steroid hormones was known to sex-dependently and/or agedependently regulate the lipid metabolism in various animal species. Our current study demonstrates that lipid and its functional fatty acids can be changed depending on the status of sexual maturation. Of the functional fatty acids, γ- linolenic acid (GLA; 18:3n-6) is an important factor for maintaining human health. The purpose of our study was to investigate the level of GLA in mice with different stages of sexual maturation. To this end, the longissimus muscle (LM) of immature (3-week-old) and mature (7-week-old) female mice was analysed for the fatty acid composition by gas chromatography. Furthermore, both gene and protein level of Δ6 desaturase (FADS2) which is involved in GLA metabolism by real time PCR and Western blotting, respectively. Mature females showed greater (P<0.05) serum 17β -estradiol (E2) level and LM GLA contents than immature group. The mRNA and protein levels of FADS2, which converts precursor linoleic acid into GLA, were higher (P<0.05) in mature female mice than in immature mice. In conclusion, these results show that sexual maturation of female mice induces GLA and FADS2 contents in LM.

Cloned calves derived from somatic cell nuclear transfer (SCNT) have been frequently lost by sudden death at 1 to 3 month following healthy birth. To address whether placental anomalies are responsible for the sudden death of cloned calves, we compared protein patterns of 2 placentae derived from SCNT of Korean Native calves died suddenly at two months after birth and those of 2 normal placentae obtained from AI fetuses. Placental proteins were separated using 2-Dimensional gel electrophoresis. Approximately 800 spots were detected in placental 2-D gel stained with coomassie-blue. Then, image analysis of Malanie III (Swiss Institute for Bioinformatics) was performed to detect variations in protein spots between normal and SCNT placentae. In the comparison of normal and SCNT samples, 8 spots were identified to be up-regulated proteins and 24 spots to be down-regulated proteins in SCNT placentae, among which proteins were high mobility group protein HMG1, apolipoprotein A-1 precursor, bactenecin 1, tropomyosin beta chain, H+-transporting ATPase, carbonic anhydrase II, peroxiredoxin 2, tyrosine-rich acidic matrix protein, serum albumin precursor and cathepsin D. These results suggested that the sudden death of cloned calves might be related to abnormal protein expression in placenta.

Making use of our extended version of ¨ O p i k ′ s convection theory, we have calculated magnetic cycle periods of the sun and late type stars by using Parker's dynamo theory, where we have included the non-linear effect. We presented a relationship between the computed cycle period and spectral type to analyze observed magnetic activities of the late type stars and long-term luminosity variations. It is found that (1) the stellar magentic-cycle period increases towards the later spectral type, (2) the rapid rotation facilitates the activity-related luminosity variation of stars later than about K5, (3) differential rotation plays a critical role in determining the magnetic activity-cycle period, and (4) the non-local effect should be taken into account in order to understand the observed long-term luminosity variations.