Changes in the both inward current and conductance of membrane by the fertilization were observed using the one microelectrode voltage clamp(or switch clamp) technique. Unfertilized eggs and both 1- and 2-cell stage eggs after fertilization were donated from the superovulated mouse (ICR, more than 6 weeks old) treated with PMSG(pregnant mare serum gonadotropin, Sigma) and HCG(human chorionic gonadotropin, Sigma) and naturally mated ones, respectively in this experiment. Membrane potential was held at -90mV and the voltage step was applied from -80mV to 50mV with interval of 10mV or 20mV for 300ms. since both of amplitudes and time courses in the membrane currents were various according to the states of cells and clamping condition, results were presented by their $averages{\pm}SEM$(standard mean error)and ratios or percentages. Inward currents began to appear in response to the step depolarization from -60mV and reached its maximum at -50mV. However, since the potential was not clamped evenly during the voltage step, current-voltage(I-V) relationship might be positively shifted 10 or 20mV. From the steady-state currents plotted in the I-V curve, outward rectification was markedly observed. Peak inward currents$(i_{in})$ at -50mV were $-0.62{\pm}0.23nA$(n=4),$-0.52{\pm}0.25nA$(n=5) and $-0.37{\pm}0.25nA$(n=6), in the 1-cell stage, 2-cell stage fertilized eggs and in the unfertilized eggs, respectively. Pure inward current (difference between steady-state and peak, $i_{in. pure}$) were $-1.01{\pm}0.23nA$, $-0.69{\pm}0.43nA$ and $-0.68{\pm}0.29nA$, respectively in the 1-cell stage fertilized eggs, unfertilized eggs and 2-cell stage fertilized eggs. These results suggested that the outward current in fertilized eggs of 2-cell stage was more increased than those in the unfertilized eggs. Pure inward currents in the all stages of eggs showed a similar fashion in the I-V relationship from -50mV to 50mV and reversal potential at 50mV. Time constant of inactivation$({\tau})$ in the inward current was decreased as the membrane potential was depolarized in the unfertilized and 2-cell stage eggs but in the 1-cell stage eggs t was not likely to be affected significantly. Slope conductances were 14.2nS, 8.9n5 and 7.7nS in the 1-cell, 2-cell stage fertilized eggs and the unfertilized eggs, respectively. Membranes between two cells within a zona pellucida seem to be electrical-connected in the 2-cell stage eggs from the observation made in the analysis for the electronic spread and decay to the current stimuli. Both of inward current and membrane conductance were increased after fertilization in the mouse eggs. Inward current seems to be carried by the same ion or through the same channels up to the 2-cell stage and ion that carried inward current was thought to play important function after fertilization in the mouse eggs.

The present study was carried out to investigate the effects of dopaminergic drugs and the role of specific dopamine(DA) receptors on the release of TSH, $T_4$ and $T_3$. Serum TSH levels (cold-induced, $4{^{\circ}C}$) were determined using RIA(radioimmunoassay) at 30 min after administration of dopamine agonists and antagonists. Serum $T_4$ and $T_3$ levels were detected after these dopaminergic drugs were administered subcutaneously twice a day for a week. The results of the study are summarized as follows : Apomorphine, a nonspecific DA receptor agonist, produced a dose-depedent decrease in serum TSH, $T_4$ and $T_3$ levels. However, only low doses (0.3, 1.0mg/kg) of SKF38393, a specific $D_1$-receptor agonist, produced a decrease in serum lelvels of TSH. I,Y171555, a specific $D_2$-receptor agonist, produced a dose dependent decrease in serum TSH, $T_4$ and $T_3$ levels. However, SCH23390, a specific $D_1$-receptor antagonist, produced a decrease except in serum T levels which were increased dose dependently. High doses (1.0, 3.0mg/kg) of sulpiride, a specific $D_2$-receptor antagonist, made a increase in the serum levels of TSH and $T_3$. The effects of dopaminergic drugs in serum TSH and $T_4$ levels was potentiated by the pretreatment of apomorphine. The overall results of this study suggest that the regulation of TSH, $T_4$ and $T_3$ secretion were mediated via specific $D_1$ and $D_2$ receptor.

돼지(n=22) 순환혈액내 단핵세포(PB-MNCs)중 T 및 B 림프구를 정량하고자 rosette 형성기법을 적용하였다. T 림프구는 여러 농도의 2-aminoethylisothiouronium bromide(Aet)나 dextran(Dex) 용액 또는 Aet와 Dex로 조합 처리된 면양(SRBC) 및 재래산양(GRBC)의 적혈구를 사용한 E-rosette 법으로, B 림프구는 erythrocyeantibody(EA) 및 erythrocyte-antibody-complement(EAC) rosette 법으로 각각 정량하였다. 한편 rosette 형성세포의 냉장정치시간에 따른 판독결과를 비교하여 적정판독시간대를 구명한 바 아래의 결과를 얻었다. 1. PB-MNCs와 SRBC/GRBC와의 자연 rosette형성을(RFR)은$ 32.9{\pm}7.9%/31.3{\pm}9.4%$인데 비하여 Aet 또는 Dex 처리군에서는 모두 증가되었고 특히 0.15M Aet$(40.2{\pm}4.6%/37.0{\pm}3.3%)$ 및 8% Dex$(71.5{\pm}4.5%/69.9{\pm}5.8%)$ 처리군에서 각각 높게 나타났다. 한편 0.1M Aet처리후 8% Dex 첨가군에서는 $67.8{\pm}7.4%$ 및 $69.8{\pm}8.5%$로 나타나 복잡한 Aet와 Dex를 복합처리하기 보다는 8% Dex 단독처리가 간편함을 알 수 있었다. 2. Rosette 형성세포의 냉장보관중 최적판독시간대는 10~20시간의 범위이었다. 3. EA 및 EAC의 RFR은 SRBC의 경우 $39.1{\pm}10.2%$, $27.6{\pm}7.0%$, GRBC의 경우 $32.6{\pm}6.1%$, $21.0{\pm}3.2%$로 나타났다. 이러한 결과는 돼지 PB-MNCs내의 T 및 B 림프구를 rosette 형성법으로 분리할 수 있으며 rosette assay에서 SRBC 뿐아니라 GRBC의 이용이 가능함을 제시한다.

Two hundred and eighty nine strains of Yersinia enterocolitica isolated from healthy pigs were tested for the presence of 40~50 Megadalton virulence-associated plasmids and plasmidmediated in vitro virulence-associated properties, i.e., congo red uptake, calcium dependency, autoagglutination, CRMOX reaction, crystal violet binding and pyrazinamidase reaction. The correlationships between in vitro virulence-associated properties and the presence of 220 Kdalton outer membrane protein(OMP) were examined in strains with or without virulence-associated plasmids. The correlationships between the presence of plasmids on the production of the OMP and the expression of in vitro virulence-associated properties were studied with $CRMOX^+$ strains and acridine orangecured $CRMOX^-$ mutants. The results were as follows : 1. Of the in vitro virulence-associated tests with 289 strains of Y enterocolitica, 275 strains (95.2%) were positive for pyrazinamidase test, and followed by in order of crystal violet binding test, 226 (79.2% ) ; CRMOX test, 190 (65.7%) ; autoagglutination test, 1.85(64.0%) : calcium dependency test, 86 (29.8%) and congo red uptake test, 47(16.3%). 2. The correlationship between autoagglutination and CRMOX test(r=0.90) was highly significant (p<0.01). 3. In 190 strains(65.7%) bearing the virulence-associated plasmids(MW 40~50 Mdalton), the correlation between the presence of plasmids and their in vitro virulence-associated properties were highest with CRMOX test(r=0.93) and followed by in orders of AAG test(0.81), CV test(0.46), PYZ test(0.37) and CD test(0.18), but no correlationship between the presence of plasmids and CR test(-0.11). 4. The $CRMOX^+$ strains produced the 220 Kdalton OMP when they were cultured at $37^{\circ}C$, but not at $26^{\circ}C$. The presence of 220 Kdalton OMP was correlated significantly with in vitro virulence properties and the presence of virulence-associated plasmid, respectively. 5. In the isogenic $CRMOX^-$ mutant strains, of which plasmid were cured by treatment with acridine orange not only in vitro virulence-associated properties(CR 100%, CD 100%, AAG 82.6%, CV 58.3%) disappeared but also 220 Kdalton OMP(100%) was not produced. These results indicate that the positive CRMOX reaction is plasmid-mediated and the CRMOX test is potential as an in vitro virulence tests with Y enterocolitica.

The soluble antigen profiles and antigenic specificities of Leptospira interrogans serovars icterhaemorrhagiae, canicola, pomona and hardjo were examined by SDS-polyacrylamide gel electrophoresis, crossed immunoeletrophoresis and immunoblotting. The profiles of protein, glycoprotein and fraction containing N-acetylglucosamine of 4 serovars were compared. The protein profiles of 4 serovars were very similar except the range of 14,400 to 30,000 daltons. Molecular weight of glycoprotein of L, pomona was lower than other serovars. L canicola showed extra N-acetylglucosamine bands having molecular weight of 82,000 and 90,000 daltons. In crossed immunoelectrophoresis, a close antigenic relationship was found between L icterohaemorrhagiae and L canicola. In immunoblottings conducted with soluble antigens and rabbit antisera of 4 serovars, Leptospira interrogans serovars possessed cross-reactive antigens and serovar-specific antigens. The molecular weights of serovar-specific antigens were 45,000, 82,000 and 90,000, 31,000 and 24,000 daltons in L icterohaemorrhagiae, L canicola, L pomona, and L hardjo, respectively.

Enterovirus감염 돼지의 감염초기 virus의 동태를 규명하고자 초유를 섭취하지 않는 1~2일령의 돼지에 돼지 enterovirus 3형을 경구감염시킨후 간조직을 전자현미경으로 관찰하였던 바 다음과 같은 결과를 얻었다. 감염후 3일째 부검한 돼지의 간에서 간세포의 심한 공포변성이 인정되었고 간 동양혈관 내피세포 및 Kupffer세포에서 picornavirus의 특징적인 virus결정이 출현하였으며 확장된 ER은 virus 결정과 밀접하게 관련되어 있었다. 또한 동양혈관 세포와 간세포에서는 미숙한 virus모양의 입자들로 구성된 세포질내 봉입체가 관찰되기도 하였다. 이상의 소견으로 보아 돼지 enterovirus 3형은 신경친화성 뿐만 아니라 감염초기 간에 친화성이 큰 것으로 생각된다.

Fecal examination for survey of natural prevalence of Balantidium coli was performed on 1080 healthy bred pigs in Korea, and the positive rate was 56.2%. In order to observe if Balantidium coli might be a secondary invader after certain initiation of the intestinal lesions, the piglet groups preinfected with the protozoa experimentally were treated with Salmonella cholerasuis, Trichuris. cold stress, HCI, and immunosuppressive drug respectively, but no relation was found between them. Also the protozoa were not detected from the intestinal lesions spontaneously formed of 107 pigs which were checked in the slaughter house. According to the above results, Balantidium coli is not directly associated with the formation of any lesions in the pig's large intestine.

Five puppies, 14 days old in the same litter showed acute symptoms such as painful crying, anorexia, abdominal pain and depression with fatal terminations. Necropsy of a puppy revealed hemorrhagic and necrotic foci in the lungs and kidney. The histological lesions were characterized with fibro-necrotizing foci in the lungs, nonsuppurative encephalitis and intranuclear inclusions of liver cells. A cytopathogenic agent was isolated from the thoracic fluid of a dead puppy by cell culture with primary dog kidney cells. The puppies inoculated with the field isolate showed the same clinical signs and lesions as those of the spontaneous cases. Viral particles were observed in suspension of the isolated agent by electron microscopy. The primary dog kidney cells infected with the field isolate showed fluorescent foci against anti-CHV monoclonal antibody after FA stain. On these findings of the disease it was diagnosed as CHV infection. The report signifies the first description of an epizootic of CHV infection in Korea.

Out of twenty rabbits which died of rabbit hemorrhagic disease spontaneously occurring in Korea, five animals had a concurrent infection with Encephalitozoon cuniculi in the cerebrum. The lesions were composed of granulomas, leptomeningitis and perivascular cuffing with mononuclear cells. The granulomas consisted of a central necrotic focus surrounded by an infiltration with plasma cells, lymphocytes and macrophages. Gliosis was associated with the granulomas. Gram-positive organisms were detected in the cerebrum from two rabbits. They were oval to rod-shaped with blunt round ends. The distribution of the pathogens was investigated by the direct avidin-biotin peroxidase complex method. They were present in pseudocysts and macrophages. Pseudocysts were found in the granulomas as well as the neuropil without cellular reactions. Some organisms were present within reticulo-endothelial cells of blood capillaries and macrophages in the subarachnoid spaces. These organisms had ultrastructural characteristics consistent with Encephalitozoon cuniculi.

The diseased Chuckar partridges that were raised at the wild bird-raising farms located in Ockchun, Chungbuk province, were submitted for diagnosis in the laboratory in July. 1990. The diseased partridges aged 3~4 weeks old were shown clinical signs such as anorexia, depression, white-colored or transparent-watery diarrhea and dropping of the head and wings. At necropsy, major gross lesions were found in the livers, ceca and lungs. Histopathologically, numerous histomonads were observed in the necrotic tissues of the livers and ceca. In the cecal specimens, it was found that the ameboid histomonads have flagellum and the size of 10~20 micrometer. The case was confirmed as histomoniasis due to the infection of Histomonas meleagridis.

In the present experiment, the blue-green algae, the principal food of the vector snail of Fasciola hepatica were cultured. Mud from good natural habitats was sterilized, made slopes, inoculated with algae from the habitats and maintained in a saturated atmosphere. Under the fluorescent-mercury lamp(100W) at about $20^{\circ}C$ the algal growth was optimal, taking 8 days to fully grow and to be ready for feeding the snails. The algae collected from the habitats and cultured in the laboratory were mainly green.

This study was performed to demonstrate the presence of large granular lymphocyte(LGL) in Sprague-Dawley(SD) rats and morphologically observe NK cell and also establish the method of isolation of natural killer cell in SD rats. By percoll discontinuous density gradients centrifugation, highly enriched LGL population were shown to fraction 2(border line between 44.2% and 50.8%). LGL were shown to bind selectively to YAC1 mouse lymphoma cell. This fraction expressed very high NK cell cytolysis. Therefore, we thought that LGL have NK activity in SD rats. The Morphology of rat LGL is very similar to that of human LGL. These cells have an eccentric kidney-shaped nucleus. Their most distinctive feature was their cytoplasmic azurophilic granules. Another distinguishing feature of rat LGL was their high cytoplasmic : nuclear ratio. It was concluded that LGL played a role part in mediating natural killer activity in this species.

Stable plurilamellar vesicle(SPLV) 제작법을 이용한 liposomal cephalexin으로 젖소의 Staphylococcus aureus성 유방염에 대해 건유기 치료를 시도하였다. SPLV의 모양과 크기를 transmission electron microscopy로 관찰하였으며 SPLV의 포획율 및 안정성은 high performance liquid chromatography 및 liquid scintillation counting으로 조사한 바 SPLV의 크기는 대개 직경 $0.1{\sim}4.0{\mu}m$였고, cephalexin 포획율은 $25.8{\pm}3.1$ $(mean{\pm}SE)$였으며 $4^{\circ}C$ 보관시 0, 24, 48, 72 및 96 시간후의 유리농도백분율은 각각 1.1, 3.9, 6.5, 7.5 및 8.4%였다. S aureus에 감염된 45분방에 대하여 15분방씩 3군으로 나누어 각 분방당 250mg의 liposomal cephalexin(LC군), 250mg free cephalexin(FC)군 및 blank liposome을 첨가한 250mg cephalexin(BLC)군을 건유시 분방내 주입한 후 분만당일에 균분리 및 동정을 실시한 바 LC군, FC군 및 BLC군에서 각각 1, 8 및 7분방에서 상기와 동일한 균이 분리되어 LC군이 타군에 비해 유의한 치료효과를 나타내었다.

A study was conducted to improve the reproductive performance of Korean native goats. The length of estrous cycle and plasma progesterone concentrations during each cycles were determined by both radioimmunoassay and estrus behaviours, and the results were used in the early pregnancy diagnosis. The estrous cycles were classified into the short(l8 days or shorter, average 16.7 days), normal(19 to 22 days, average 20.9 days) and long(23 days and longer, average 23.8 days)cycle. The average length of the 19 estrous cycles was 20.8 days. Plasma progesterone concentrations in 12 normal cycles were the lowest(0.10 ng/ml) at estrus, remained high from 6 to 16 days(range : 4.43~7.93 ng/ml) and drastically decreased thereafter to reach minimal concentrations at the next estrus. Plasma progesterone concentrations were measured for early pregnancy diagnosis at 0, 10 and 20 days after mating in the 12 Korean native goats. Plasma progesterone concentrations in the pregnant goats at 20 days after mating were significantly higher than in the non-pregnant goats(p<0.001). Of the 12 goats, 10 were confirmed pregnancy by both progesterone concentrations and kidding. The accuracy of the pregnancy diagnosis based on plasma progesterone concentrations was 100% for positive as well as for negative.

The purpose of present study was to investigate the progesterone concentrations throughout gestation and peripartum period, and the return to the first estrus postpartum for improvement of reproductive efficiency in Korean native goats. The average length of gestation was 148 days(range : 144~154 days) and the average number of live births was 2 kids(range : 1~5 kids) in 12 Korean native goats. Progesterone concentrations were measured in blood samples taken from 12 goats every 5 days during gestation period. Plasma progesterone concentrations were 0.10 ng/ml at Day 0 of pregnancy and increased gradually until Day 20(6.58 ng/ml). Then they decreased slightly from Day 30 to 40(range : 4.32~4.82 ng/ml), increased again after Day 40 and remained thereafter until Day 140(range : 4.32~10.36 ng/ml). The progesterone levels declined sharply to basal levels at parturitum. Plasma progesterone concentrations during the pestpartum were 6.98 ng/ml at 10 days, 4.86 ng/ml at 6 days 3.18 ng/ml at 2 days before parturition, and 0.10 ng/ml at parturition, respectively. The basal levels were maintained until the first estrus postpartum. The mean intervals from parturition to the first estrus postpartum on the basis of progesterone determination and estrus detection were $100{\pm}64(mean{\pm}S.D.)$ days in 7 Korean native goats.

To investigate the age at puberty and the seasonal breeding in Korean native goats, progesterone concentrations were measured in blood. Blood samples were collected from 8 goats at 10 day intervals from 2 months of age until the first estrus after birth, and then every 5 days for a further estrous cycle and the seasonal breeding. The mean age and weight at puberty were $195{\pm}57$ days($mean{\pm}S.D.$, range : 107~260 days) and $11.1{\pm}0.9kg$(range : 9.8~12.0kg), respectively. The mean age at first pregnancy after birth was $241{\pm}109$ days(range : 107~273 days). The estrus was observed 47.6% from October to December, and was highest in fall(38.1%) and lowest in spring and summer(14.3%). However, the estrus was observed every season. About 67% of total conception occurred form October to January. The parturition occurred 41.7% in spring, 25.0% in summer and winter, and 8.3% in fall, respectively. These results suggest that Korean native goats do not have a breeding season, but the reproductive activity is influenced by the season.