We investigated the changes in plasma sex steroid hormones, testosterone (T), estradiol-17β (E2), 17,20 β-dihydroxy-4-pregnen-3-one (17α20βOHP), 11-ketotestosterone (11KT) and cortisol levels from ribbed gunnel, Dictyosoma burgeri in associated with annual reproductive cycle. The fish were collected at the coastal waters of Dadaepo, Busan, Korea from August 2002 to March 2003. Body weight, liver weight and gonad weight were measured for calculation of hepatosomatic index (HSI) and gonadosomatic index (GSI). Plasma steroid and cortisol levels were measured by radioimmunoassay and data were analyzed using the Kruskal-Wallis test and the Spearman rank correlation. The GSI of females increased from November, peaked in February (13.21±2.27) and decreased rapidly from March (1.05±0.23). The GSI of males also increased from November, peaked in December (0.36±0.12) and remained high to February. In females, E2 levels increased and remained high from December to February (19.81±7.46～22.85±6.18 ng/ ㎖). The levels of T showed a similar tendency and correlated (rs=0.813, p=0.0001) significantly with E2 levels. The levels of 17α20βOHP increased rapidly in February (4.78±1.01 ng/㎖) and peaked in July (5.08±0.65 ng/㎖). Cortisol level was peaked in March (2081.07±1140.02 ng/㎖) and correlated significantly with 17α20βOHP levels (rs=0.790, p=0.0001). In males, the levels of T was peaked in January (2.43±0.17 ng/㎖) and then decreased rapidly. The levels of 11KT were remained high from October to January (3.27±1.55～4.28±1.53 ng/㎖) and correlated significantly with T levels (rs=0.513, p=0.002). On the other hand, the levels of 17α20βOHP fluctuated during reproductive cycle and the variation pattern of cortisol levels were similar to females. These results suggest that plasma sex steroids in ribbed gunnels have annual periodicity, and that cortisol may involve in maturation of females.

Shinnamjag is a round, smooth, white-skinned, and fleshed potato cultivar with erect plant shape and early maturity. It has excellent table quality. Its yields are high, especially with prominent marketable yield compared to Superior, a leading potato cul

The optimized in vitro culture system was investigated for improvement of regeneration efficiencies by observing the responses of scutella-derived callus of Korean rice (Oryza sativa L.). Large variations of callus induction (43.9-93.9%) and shoot regeneration (0-88.7%) were observed among the rice cultivars depending on medium. However, shoot regeneration was significantly improved by selected utilization of basal medium, growth regulators, and carbon sources. N6 basal medium was more efficient for embryogenic callus induction than MS or LS basal medium, while MS was superior to N6 for shoot regeneration. The calli of highly regenerative cultivars grew faster and showed higher rates of green tissue formation (GT) and shoot regeneration (SR) and lower rate of callus browning (CB) than those of recalcitrant cultivars. Although a higher level of kinetin stimulated the GT and SR in highly regenerative cultivars, 10~textrmmgL-1 kinetin generally suppressed the GT and SR, while CB was accelerated compared to 2~textrmmgL-1 kinetin. Additional benefits of sorbitol combined with maltose (or sucrose) under 5~textrmmgL-1 kinetin were certainly confirmed on regeneration efficiencies compared to sucrose alone as carbon source and osmotic regulator. This combination showed high rate of GT and SR with multiple shoots while low rate of CB. With MSRK5SM-Pr medium (5~textrmmgL-1 kinetin, 3% sorbitol, 2% maltose, 500~textrmmgL-1 proline), the regeneration efficiencies of total 17 out of 24 cultivars were practically improved 160% on average compared to MSRK2S (2~textrmmgL-1 kinetin, 3% sucrose) control medium. Especially, the medium was most effective to the cultivars showing a medium level of regenerability such as Daesanbyeo and Dongjinbyeo and Suwon477, enhancing efficiencies more than 300-600% compared to MSRK2S medium.

Most of recommended potato varieties in Korea are white skin colored. Purple skinned potatoes have been recognized as being effective in the prevention of gastric disease. A new variety “Jaseo” has dark purple skin and white flesh colors, and attractive r

‘Jowon’ is a new early-maturing potato variety for table use. It has spreading growth habit with narrow oval leaves. Its tubers are attractively round with white skin and light yellow flesh color. The yielding ability of Jowon is similar to Superior. Jowo

다량의 대기오염물(SO2, HF)이 배출되고 있는 공업단지 주변에서 재배되고 있는 수도의 생육에 이들 대기오염물이 미치는 영향을 구명하기 위하여 수도의 각종 형질, 수량, 대기중의 오염물 농도, 엽내유황 및 불소함량과 엽피해율을 조사하여 시험한 결과는 다음과 같다. 1. 엽내유황함량과 대기중 아황산가스 농도간에는 높은 정의 상관이 인정되었다. 2. 엽피해율 조사치는 대기오염에 의한 수량감소의 가장 중요한 지표로 이용 할 수 있다. 3. 본 조사지역에서는 아황산가스보다 불화수소의 배출량이 적지만 엽피해의 발생에는 불소의 관련성이 아황산가스보다 높았다. 4 수량형질의 수량에 대한 기여정도는 주당수수가 제일 컸으며, 주당수수는 엽내 불소함량과 깊은 관련성이 인정되었다. 5. 엽내 유황함량은 수량 및 수량형질과 상관성이 인정되지 않았다.