토끼에서는 수정란 이식과 같은 기본적인 번식공학적 방법의 효율성이 아직 생쥐와 같은 실험동물에 비해 떨어지고 있어 생물공학적인 기술을 응용하는데 큰 어려움이 있다. 특히 유전자 이식에 의한 형질전환 토끼의 생산과 같은 생물공학적인 기술을 실용화하는데 효율이 높은 수정란이식 기술의 개발이 필수적이라고 할 수 있다. 본 연구에서는 토끼에서 수정란 이식 기술의 첫 단계인 과배란 유도를 효율적으로 이용할 수 있는 방법을 정립하기 위해 반복적인 과배란 유도가 배

We obtained the CN(ΔV=0 ΔV=0 ) and C2(ΔV=0,±1 C2(ΔV=0,±1 ) spectra of comet Hale-Bopp(C/1995 O1) at the Kyunghee Observatory and Bohyunsan Astronomical Observatory between March 7 and May 12, 1997 The fluxes for each molecular band were measured and then the production rates and column densities of CN and C2 C2 were calculated using a simple model. The resultantproduction rates of CN and C2 C2 are logQ(CN)=27.4 at r=0.94 AU(preperihelion) and logQ(C2)=27.3 logQ(C2)=27.3 at r=0.94 AU(postperihelion), respectively.

This experiment was carried out to investigate the effect of the mixed rates of endophyte-he and -infected seed on the endophyte fkquency, dry matter yield and forage quality of tall fescue(Festuca arundinacea Schreb.) at the Experimental Field of Grassla

The studies were carried out to investigate the effects of co-culture with cumulus cells and oviduct epithelial cells on the in vitro fertilization and cleavage rate of bovine follicular cocytes and to determine the optimum thawing temperature and equilibration time on in vitro developmental rate of frozen bovine embryos. The ovaries were obtained from slaughtered Korean native cows. The follicular oocytes were cultured in TGM-199 medium containing 10 IU /ml의 PM SG, 10 IU /ml의 hCG, ip g/ml의 -estradiol and 10% FCS for 24~48 hrs in incubator with 5% in air at 38.5. The bovine embryos following dehydration by cryoprotective agents and a various concentration of sucrose were directly plunged into liquld nitrogen and thawed in 3 water. Survival rate was defined as developmental rate on in vitro culture or FDA-test. The results are sunanarized as followes :1. The in vitro fertilization and in vitro developmental rates of bovine oocytes co-cultured with cumulus cells in TCM499 medium were 75.0~76.8% and 17.3~27.6%, respect-ively. And in-vitro fertilization rates of cumulus-enclosed oocytes(55.4%)were significantly(p<0.05) higher than cumulus-denuded oocytes (23.1%). 2. The in vitro fertilization and in vitro developmental rates of bovine oocytes co-cultured with l l04cells /ml, 1 x l06cells /ml, lx l08cells /ml and 1 x l015cells /ml oviduct epithelial cells in TCM-199 medium were 74.5~77.8% and 15.7~21.20 respectively.3. The in-vitro fertilization and in vitro developmental rates of bovine oocytes cocultured in '1CM-199 media containing PMSG, hCG, PMSG+hCG. PMSG+-estradiol, hCG+-estradiol 0 to 40 hrs after insemination were 74.0~77.4% and l8.9~23.l%, re-spectiv ely.4.The survival rates of bovine embryos thawed after rapid freezing in the freezing medium containing a various concentration of sucrose added 1.5M and 2.OM glycerol,DMSO and propanediol were 23.5~31.4% and 20.6~34.l%, respectively. 5. The temperature thawed at 3 after rapid freezing of bovine embryos resulted in a significantly higher embryos survival rate than did at 2 and 35.6. The equilibration time on the survival rates of bovine embryos was attained after short period of time(2.5~5 min.) in the freezing medium higher than long period of time (10~20min.). (Key words : bovine embryos, co-culture, freezing, in vitro development)

The studies were carried out to investigate the effects of bisection method and with and without-zona pellucida of embryos on in vitro developmental rate bisected embryos by micromanipulator, micropipette and pipetting. The ovaries were obtained from slaughtered Korean native cows. The follicular oocytes were cultured in TCM-199 mediurn containing 10 IU /ml의 PMSG(Sigma, USA), 10 IU /ml의 hCG, 1g /ml의 -estradiol(Sigma, USA) and 10% FCS for 24~48 hrs in incubator with 5% in air at 38.5 and then, matured oocytes were again cultured for 12~ 18 hrs with motile capacitated sperm by preincubation of heparin. Bisected embryos cultured for 1~5 days in 20% FCS + TCM-199 medium. Survival rate was defined as developmental rate on in vitro culture or FDA-test. The results are summarized as follows :1. The survival rates of bisected bovine embryos by micromanipulator and micropipett were 29.2% and 19.1%, respectively. The rates of non-bisection embryos(46.7%) were significantly higher than those of bisection embryos. 2. The in vitro developmental rates of bisected bovine embryos by micromanipulator, micropipett and pipetting method were 32.4%, 19.4% and 25.6%, respectively.3. The in vitro developmental rates of with and without-zona pellucida of bisected bovine embryos by raicromanipulator were 30.8% and 25.0%, respectively. The rates of nonbisection embryos(53.1%) were significantly higher than those of bisection embryos.

This study was carried out to investigate the effect of equilibration time, sucrose concentration and age of embryo on survival and developmental rates of bovine IVF expanding blastocysts frozen-thawed by direct transfer method. The bovine oocytes were collected from 2~5mm follicles, matured for 20~24hrs in 5% incubator and then fertilized with frozen-thawed semen. Expanding blastocysts at day 7, 8, 9, 10 and 11 after IVF were frozen in 1.8M ethylene glycol(EG). Survival and hatching rates of frozen-thawed IVF embryos were examined. The results were as follow ; Survival and hatching rate of TVF expanding blastocysts after 10, 20, 3Omin exposure in 1.8M EG were 100,0,90.9, 47.1, 85.0, 75.0 and 62.5% respectively. Survival rates of IVF expanding blastocysts frozen with 1.8M EG and various concentration(0, 0.25, 0.5, 1M) of sucrose were 73.3, 25. 0, 16.7, 9.1% respectively. Survival and hatching rates of IVF expanding blastocysts frozen-thawed according to age of embryo(Day 7, 8, 9,10, 11) were 86.1, 84.8, 79.3, 61.4, 51.3, 74.2, 76.9, 71.7, 63.0 and 65.0% respectively. In conclusion, the age of the embryo(Day 7, 8) is very important for the successful freezing of IVF bovine embryos and 1.8M ethylene glycol not containing sucrose may be effective cryoprotectant for direct transfer method.

To use effectively the solar energy in greenhouse heating, a high performance solar collector should be developed. And then the size of the solar collector and thermal storage tank should be determined through the calculation of heating load. The solar collector must be set in the optimum tilt angle and direction to take daily solar radiation maximally, and the flow rate of heat transfer fluid through the solar collector should be kept in the optimum range. In this research, the performance tests of a capillary tube solar collector were performed to determine the optimum water flow rate and the results summarized as follows. 1. The regressive equations for efficiency estimations of the capillary tube solar collector in the open loop were modeled in the water flow rate of 700-l,000 l/hr. 2. The optimum water flow rate of the solar collector was estimated by the second order polynomial regression and the maximum efficiency was 80% at the water flow rate of 850 l/hr. 3. The solar thermal storage system consisted of a capillary tube solar collector and a water storage tank was tested at the water flow rate of 850 l/hr in the closed loop, and obtained the solar thermal storage efficiency of 55.2%. 4. As the capillary tube solar collector engaged in this experiment was made of non-corrosive polyolefin tubes, its weight was as light as 1/30 of the flat plate solar collector made of copper tubes. Therefore it was considered to be suitable for the greenhouse heating system.

Genetic changes from improving female's reproductive rate through in vitro fertilization of large number of oocytes were studied. The breeding scheme employed was multiple ovulation and embryo transfer of juveniles and adults. Both balanced and unbalanced matings were examined for the four closed progeny population sizes, 10, 10, 105, 106. In balanced matings, all selected sires and dams were mated to each other(cross-classified mating) while unbalanced matings allowed selected dams and sires mated partially, eg. unbalanced matings allowed averages of .5 and .25 progeny per each mating. Various numbers of selected sires and dams were also examined in both balanced and unbalanced matings. In all mating schemes, selection of males and females was restricted to he one from each fullsib family to reduce the rate of inbreeding. The model calculations were deterministic and accounted for the effects of selection and inbreeding on loss of the genetic variation in succeeding generations. Balanced rectangular mating schemes, where more donors were selected than sires, resulted in larger selection responses than balanced square mating schemes, where equal numbers of sires and donors were selected, and unbalanced rectangular mating. The first round selection responses from the balanced rectangular matings of juvenile MOET, eg. number of progeny per mating equals 2 with 10 sires selected, were 1.192, 1.406, 1.580 and 1.735 times larger than the first round selection responses from the balanced square mating schemes for the given four progeny population sizes, 10, 10, 105 and 106, respectively. Similar results were obtained in adult MOET breeding schemes. However, balanced square matings gave greater selection responses than the unbalanced rectangular matings.

Tlis experiment was to study the effects of application rates of mineral N and cattle slurry on the dry matter yield and botanical compositions of Orchardgrass sward grown in 4 cuttings in a year. Annual rates of mineral N of O(), 120kg((), 240kg(() and 3

The study was conducted to determine the optimal hormone and glucose levels during the in vitro culture of bovine oocytes matured and fertilized in vitro for blastocyst development. Oocytes matured in TCM 199 + 10% FCS + hormones and glucose were fertilized in vitro in a TALP medium with swim up separated and heparin-treated epididymal cauda spermatozoa. Oocytes were cultured for 2~5 days in synthetic oviduct fluid medium (SOFM) supplemented with 10% FGS and with different hormone and glucose levels, and further cultured 5 days same medium in SOFM. The results are summarized as follows : The in vitro maturation and penetration rates of porcine oocytes cultured in TCM 199 media containing PMSG, hCG, PMSG + hCG, hCG + estradiol, PMSG + estradiol 0 to20 hours after insemination were 88.0% and 81.8%, 82.6% and 68.4%, 80.0% and 75.0%, 80.0% and 65.0%, 77.3% and 64.7%, respectively. The in vitro maturation and penetration rates of porcine oocytes cultured in TCM 199 media containing PMSG, hCG, PMSG + hCG, hCG + estradiol, PMSG + estradiol 20 to 40 hours after insemination were 92.0% and 87.0%, 92.0% and 82.6%, 91.3% and 81.0%, 85.2% and 73.9%, 87.5% and 81.0%, respectively. The cleavage and in vitro developmental rates to blastocyst of porcine oocytes cultured in TCM 199 media containing 0.05 mM, 0.10 mM, 0.30 mM, 0.50 mM, 1.00 mM, and 3.00 mM glucose lelvels 0~3 days after insemination were 31.5~48.1% and 10.0~16.7%, respectively. The cleavage and in vitro developmental rates to blastocyst of porcine oocytes cultured in TCM 199 media containing 0.05 mM, 0.10 mM, 0.30 mM, 0.50 mM, 1.00 mM, and 3.00 mM glucose levels 4~8 days after insemination were 30.0~53.8% and 8.7~19.2%, respectively. The cleavage and in vitro developmental rates to blastocyst were higher in TCM 199 media containing various glucose levels 0~3 days after insemination than 4~8 days.