The H2S 22,0 - 21,1 line emission is observed to be strongly localized toward Sgr B2(M), and emissions from other positions in the more extended SgrB2 region are almost negligible. H2S is thought to form effectively by the passage of the C-type shocks but to be quickly transformed to SO2 or other sulfur species (Pineau des Forets et al. 1993). Such a shock may have enhanced the H2S abundance in Sgr B2(M), where massive star formation is taking place. But the negligible emission of H2S from other observed positions may indicate that these positions have not been affected by shocks enough to produce H2S, or if they have experienced shocks, H2S may have transformed already to other sulfur-containing species. The SO2 222,20 - 221,21 line was also observed to be detectable only toward the (M) position. The line intensity ratios of these two molecules appear to be very similar at Sgr B2(M) and IRAS 16239-2422, where the latter is a region of low-mass star formation. This may suggest that the shock environment in these two star-forming regions is similar and that the shock chemistry also proceeds in a similar fashion in these two different regions, if we accept shock formation of these two species.

This study was carried out to investigate the general characteristics and viability of sperm after freezing and thawing and the pregnancy rates after artificial insemination with thawed semen. The rates of viable sperm after slow and rapid freezing were 87.4±3.85% and 70.8±4.45%, respectively which were significantly lower than that of fresh semen control (91.7±3.45%). The mean concentration of epididymal sperm after dilution in 1.0 ml saline and. 3.0 ml extender in a various concentrations of cryoprotectants was 124.5±48.3 x 10/sup 6/ (range of 45 x 10/sup 6/ to 280 X 10/sup 6/ /ml). There was a significant difference not in the percentage of acrosome-reacted sperm, but in the percentage of capacitated sperm, between fresh and frozen-thawed epididymal semen. When frozen-thawed after diluting with tris-buffer extender containing glycerol, DMSO and ethylene glycol with concentration of 2 to 6%, the rates of epididymal sperm exposed to different cryoprotectants ranged from 14.4±4.7% to 20.7±5.8%, 17.8±5.2% to 36.5±4.9%, and 14.4±4.6% to 18.5±5.3%, respectively which were lower compare to fresh semen control. The pregnancy rate after artificial insemination with frozen semen was 70.6%, whereas that with fresh semen was 90.0% in dogs with naturally induced estrus.

본 연구는 착상전 이배체 단위발생 돼지난자를 체외 배양시 우태아혈청 (FBS), 우혈청 알부민 (BSA) 및 상피세포성장인자 (EGF)를 배양액에 첨가하였을 때 배반포, 총 세포수, 세포사멸 및 세포사멸에 관여하는 유전자의 발현을 조사하고자 수행하였다. 0.4% BSA를 배양액에 첨가하였을 때 2세포기 단위발생 난자의 배반포까지의 발달율이 증가되었다(P<0.01). FBS는 배반포의 총세포수를 감소시 켰고 세포사멸을 증가하였다(P<0.01). 그리고 EGF는 BSA가 존재하는 조건하에서 배반포의 총세포수를 증가하였는데 EGF와 BSA가 각각 단독으로 존재할 때는 이런 작용이 없었다. 세포사멸도 이와 이슷한 경향을 보였는데 EGF와 BSA가 각각 존재할 때에는 비처리군과 차이가 없었지만 함께 존재할 때에는 세포사멸을 감소시켰다. RT-PCR의 결과에 의하면 EGF는 BSA가 존재하는 배양액에서 Bcl-xL 유전자의 상대적 발현량을 증가시키고 Bak 유전자의 상대적 발현량에는 영향을 주지 않는 과정을 통하여 세포사멸을 감소시키는것 같다. 반면에 FBS는 Bcl-xL의 발현량을 감소시키고 Bak 유전자의 상대적 발현량을 증가시킨다. 이러한 결과는 세포사멸에 관여하는 유전자의 발현은 배양액의 첨가물에 따라 유의적으로 영향을 받으며, 체외배양시 배아의 초기발달에 관여함을 시사한다.

1. The oxidation resistance of containing Ni-base alloy is superior to that of the alloy without . 2. The appearance of oxides of Ni-20Cr-20Fe-5Nb- alloy is similar to that of oxides in commercial PM1000 and MA754 alloy. 3. The oxides in ODS alloy are grown mainly at particle boundaries.