본 연구는 동자개 정자의 동결보존을 위해 동결보존제의 최적 농도와 적정 희석액을 구명하여 정자를 최상의 상태로 보존하여 인공종자를 생산하는데 목적이 있다. 실험은 3종의 희석액(Ⅰ: 300 mM glycose, Ⅱ: Kurokura extender, Ⅲ: Li extender), 4종의 동결보존제(dimethyl sulfoxide, ethylene glycol, methanol and glycerol)와 4개의 동결보존제 농도(5, 10, 15, 20%)를 조합하여 대하여 조사하였다. 동결보존한 정자를 해동한 후 정자의 생존율과 정자활성지수로 동결보존 제의 효과를 평가하였다. 희석액 Ⅲ(Li extender)과 10과 15%의 methanol을 조합했을 때 동자 개 정자의 생존율과 정자활성지수는 각각 66.9 ± 8.7, 67.3 ± 13.1%과 2.6 ± 0.4, 2.6 ± 0.5로 다른 희석액과 동결보존제보다 높았다.

멸종위기에 처한 꼬치동자개(Pseudobagrus brevicorpus)의 보전과 복원을 위한 기초 자료를 제공하기 위하여 인공사육 환경에서 사육된 종묘에서 친어까지의 성장과 성성숙 특징들을 조사하였다. 부화 후 698일의 인공사육 기간 동안 전장과 체중은 각각 89.22±10.29mm와 70.93±7.68g로 성장하였고, 전장 (TL)과 체중(BW)의 관계는 BW=5×10-5 TL2.678 (R2=

We used nine decamer primers to generate DNA fragment sizes ranging from 100 bp to 1,600 bp from two bullhead (Pseudobagrus fulvidraco) populations of Dangjin in Korea. 376 fragments were identified in the cultured bullhead population, and 454 in the population of wild bullhead from Dangjin: 287 specific fragments (76.3%) in the cultured bullhead population and 207 (45.6%) in the wild bullhead population. On average, a decamer primer was used to generate 34.2 amplified products in a cultured bullhead. A RAPD primer was used to generate an average of 3.1 amplified bands per sample, ranging between 2.5 and 6.0 fragments in this population. Nine primers also generated 24 polymorphic fragments (24/376 fragment, 6.4%) in the cultured bullhead population, and 24 (24/454 fragments, 5.2%) in the wild bullhead population. The OPA-16 primer, notably, produced which 11 out of 11 bands (100%) were monomorphic in the wild bullhead population. 110 intra-population-specific fragments, with an average of 12.2 per primer, were observed in the cultured bullhead population. 99 fragments, with an average of 11.0 per primer, were identified in the wild bullhead. Especially, 55 inter-population-common fragments, with an average of 6.1 per primer, were observed in the two bullhead populations. The bandsharing value (BS value) of individuals within the wild bullhead population was substantially higher than was determined in the cultured bullhead population. The average bandsharing value was 0.596±0.010 within the cultured bullhead population,. and 0.657±0.010 within the wild bullhead population. The dendrogram obtained with the nine primers indicates two genetic clusters, designated cluster 1(CULTURED 01~CULTURED 11), and cluster 2(WILD 12~WILD 22). Ultimately, the longest genetic distance displaying significant molecular differences was determined to exist between individuals in the two bullhead populations, namely between individuals WILD no. 19 of the wild bullhead population and CULTURED no. 03 of the cultured bullhead population (genetic distance = 0.714). RAPD-PCR allowed us to detect the existence of population discrimination and genetic variation in Korean population of bullhead. This finding indicates that this method constitutes a suitable tool for DNA comparison, both within and between individuals, populations, species, and genera.

This study was conducted to investigate the skeletal development of bullhead torrent catfish, Liobagrus obesus larvae and to utilize them as basic data for the taxonomic study of Liobagrus larvae. Skeletal development was observed by being divided into cranium, visceral skeleton, shoulder girdle bone, pelvic girdle bone and vertebra. On the first day after hatching, the pre‐larvae had an average total length of 7.92 mm, and a line‐shaped parasphenoid ossified in the cranium. In the jaw bone, the dentary supporting the lower jaw and the maxillary supporting the upper jaw were ossified. In the anterior abdominal vertebrae of the vertebra, seven centrums began to ossify and five neural spines ossified simultaneously. On the 3 day after hatching, pre‐larvae had an average total length of 8.95 mm, and the prefrontal ossified in cranium. The number of abdominal vertebrae was increased to 14, and three parapophysis developed from the front side. On the 24th day after hatching, postlarvae had an average total length of 15.2 mm and the epural bone ossified in coccyx. The parhypural bone was ossified, and ossification of coccyx and pelvic girdle bone was completed. On the 30th day after hatching, the average total length of the juvenile was 17.8 mm, and the ossification of cranium and visceral skeleton was all completed while the preorbital and three suborbitals were ossified in the orbital region of the cranium.

This study was examined the ovogenesis of Ussurian bullhead, Leiocassis ussuriensis and the morphological development of its larvae and juveniles and to use the results as basic information for the preservation of species and resource enhancement. For artificial egg collection, human chorionic gonadotropin (HCG) was injected at a rate of 10 IU per gram of fish weight. During breeding period, water temperature maintained at 24.5~26.5℃ (mean 25.0±0.05℃). The process of ovogenesis reached the two-cell stage in 50 minutes after fertilization. In 73 hours of fertilization the movement of the embryoid body became active state and the larvae began to hatch from the tail through the oolemma. Length of prelarvae were 6.33~6.50 mm long (mean 6.40±0.06 mm) just after hatching having yolk with their mouth not opened. After thirty eight days of hatching, juveniles were 30.6∼32.5 mm long (mean 31.5±0.65 mm). The color was dark yellowish brown throughout the entire body, and the number of caudal fin rays developed to thirty six perfectly.

The histological changes in the Ussurian bullhead, Leiocassis ussuriensis, and the Korean bullhead, Pseudobagrus fulvidraco, were observed during the early period of growth. The retinas size of both species increased in the 9 days post-hatching (DPH) (P<0.05). In the just-hatched Ussurian bullhead, the retina already consisted of six layers: the epithelial layer, ganglion cell layer, inner nuclear layer, inner plexiform layer, outer limiting membrane layer, and rod and cone layer. The Korean bullhead had the same components. At 50 DPH, the thickness of the retina was 538.0±7.19 μm in the Ussurian bullhead and 558.9±9.44 μm in the Korean bullhead. The relative thickness of each layer of the retina did not differ significantly in the two species. Although the growth of the Korean bullhead’s retina was faster, the relative thickness of each layer in the retina did not change during early development. After hatching, some parts of the tissue gradually became denser. Immediately after hatching, the kidney and midgut epithelium of the Ussurian bullhead and Korean bullhead were already formed and grew gradually thereafter. From 0 DPH to 30 DPH, the nuclear height in the midgut epithelium did not differ significantly between the two species, but at 50 DPH, it was 11.4±2.45 μm in the Korean bullhead and 9.9±2.13 μm in the Ussurian bullhead. During the experimental period, the major axes, minor axes, surface areas, and volumes of the proximal tubule cells in the kidney did not differ significantly between the two species. Thus, the early histological development of the Ussurian bullhead is similar to that of the Korean bullhead.

The histological changes in the Ussurian bullhead, Leiocassis ussuriensis, and the Korean bullhead, Pseudobagrus fulvidraco, were observed during the early period of growth. The retinas size of both species increased in the 9 days post-hatching (DPH) (p<0.05). In the just-hatched Ussurian bullhead, the retina already consisted of six layers: the epithelial layer, ganglion cell layer, inner nuclear layer, inner plexiform layer, outer limiting membrane layer, and rod and cone layer. The Korean bullhead had the same components. At 50 DPH, the thickness of the retina was 538.0±7.19 μm in the Ussurian bullhead and 558.9±9.44 μm in the Korean bullhead. The relative thickness of each layer of the retina did not differ significantly in the two species. Although the growth of the Korean bullhead’s retina was faster, the relative thickness of each layer in the retina did not change during early development. After hatching, some parts of the tissue gradually became denser. Immediately after hatching, the kidney and midgut epithelium of the Ussurian bullhead and Korean bullhead were already formed and grew gradually thereafter. From 0 DPH to 30 DPH, the nuclear height in the midgut epithelium did not differ significantly between the two species, but at 50 DPH, it was 11.4±2.45 μm in the Korean bullhead and 9.9± 2.13 μm in the Ussurian bullhead. During the experimental period, the major axes, minor axes, surface areas, and volumes of the proximal tubule cells in the kidney did not differ significantly between the two species. Thus, the early histological development of the Ussurian bullhead is similar to that of the Korean bullhead.

Morphometric changes in the Ussurian bullhead, Leiocassis ussuriensis, and the Korean bullhead, Pseudobagrus fulvidraco, were observed during the early period of growth. Yolk length, yolk height, and yolk volume in the two species decreased within 9 days post-hatching (DPH) (p<0.05). The body lengths and body heights of both species increased gradually to 150 and 130 DPH, respectively (p<0.05). The horizontal distance between the anteriormost extension of the head and the anterior insertion of the pectoral fin, the anteriormost extension of the head × the verticality position of the anterior insertion of the primary dorsal fin rays, and the anterior insertion of the primary dorsal fin × the anterior insertion of the pectoral fin were greater in the Korean bullhead than in the Ussurian bullhead (p<0.05). However, the relative sizes of the head region, pectoral fin, ventral fin, and anal fin were greater in the Ussurian bullhead than in the Korean bullhead (p<0.05), and relative body depth and the size of the outer-mandible barbel were greater in the Korean bullhead than in the Ussurian bullhead (p<0.05). The growth curves of the morphometric characteristics of both species were divided into three types.

Korean bullhead (Pseudobagrus fulvidraco) was collected from the Kum River areas of Kangkyung-eup, Nonsan city, Chungcheongnam-do, Korea, from April to June, 2012 and was fertilized in order to observe egg development and temperature-related cleavage rates and mitotic intervals (). The fertilized eggs were separative, demersal and light yellowish with in diameter, and did not contain oil globules. The first cleavage stages were 90 min, 80 min, 60 min and 50 min at , , and , respectively. At higher temperatures, eggs developed faster and underwent further identical development. For Korean bullhead, were min at , min at , min at and min at . There were strong negative correlations between the and water temperatures at all points studied (Y=-1.13X+58.15, =0.98, n=30, where Y is and X is temperature). The results obtained in this work will be helpful for chromosome manipulation by use of cleavage frequency data and data in Korean bullhead.

The effects of ovulation induction in ussurian bullhead, Leiocassis ussuriensis, were investigated by treating ussurian bullhead with hCG, LHRHa, GnRHa, ovaprim, and pimozide. hCG was injected to ussurian bullhead at 0.75% NaCl, 5,000, 10,000, 20,000, and 30,000 IU, respectively. The ovulation inducement rates were 100% in 20,000 and 30,000 IU. Fertilization rates were 82.7% and 79.8%. Hatching rates were 59.4% and 57.2%. Ovulation time was between 16-19 hr The concentrations of LHRHa injected were 0.75 NaCl, 50, 100, 200, 300, and . The ovulation inducement rates were 100% in 300 and . Fertilization and hatching rates were 84.9% and 68.4% at . The times to ovulation were between 23 hr and 34 hr. Ovaprim of 0.75% NaCl, 1.0, 1.5, 2.0, 2.5 and 3.0 ml/kg were injected to the abdominal cavity. The ovulation inducement rate was highest at 2.0 and 3.0 ml/kg to 92% and ovulation time was between 27-38 hr. LHRHa concentrations of 0.75% NaCl, 50, 100, 200, 300 and were injected with pimozide (). Ovulation inducement rate was 100% from 200 to 400 IU with pimozide. Ovulation time was 22-36 h. Fertilization and hatching rates were 88.9% and 70.4% in with pimozide.

본 연구에서는 각각의 호르몬 처리에 따른 배란유도 효과를 알아보고자 하였다. LHRHa 호르몬을 종어 암컷에 2회 투여 시 50과 100 농도에서 100%의 배란율을 보여 가장 높았으며, LHRHa를 1차 처리한 후, 인간 태반성 성선자극호르몬인 HCG를 2차 처리하였을 때, 500 IU에서는 배란이 이루어지지 않았으며, 2,000 IU를 주사한 암컷에서 72%의 높은 배란율을 보였다. HCG만 처리했을 시 500~25,000 IU까지 각각 10, 17

눈동자개, Pseudobagrus koreanus의 성분화 과정을 밝히기 위해 부화 직후부터 250일령까지 생식소의 분화 및 발달을 조사하였다. 원시생식세포는 부화 후 1일(전장: 6.63～6.95 ㎜)에 나타났으며, 부화 후 5일(7.50～9.36 ㎜)에 생식융기를 형성하는 원시생식소 구조를 나타내었다. 부화 후 25일(11.58～13.21 ㎜)에서는 생식소 후단부 한쪽 끝에서 신장된 체세포 돌기가 생식소와 융합되어 작은 난소강이 형성되었다. 부화 후 30일(12.19～13.72 ㎜)에는 생식소 하단부에 정소관 원기가 출현하여 정소의 분화가 시작되었다. 부화 후 50일째 자어(16.28～17.06 ㎜)의 난소내에서는 주변인기 난모세포로 채워지기 시작하였으며, 정소내에서는 정원세포(spermatogonia, SG)의 활발한 증식을 관찰할 수 있었다. 부화 후 250일째 자어(35.49～51.12 ㎜)에서는 난소의 크기가 더욱 커지고 난모세포들로 가득 채워져 있었고, 정원세포의 수가 증가하기 시작하였다. 이상의 결과 눈동자개의 성분화 양상은 자웅이체형 중 분화형이었다.