• Journal of Aquaculture
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• v.17 no.1
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• pp.8-11
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• 2004

Milt of the catfish was stripped into immobilizing solution containing 175 mM NaCl and 30 mM Tris at pH 7.8 and was successfully cryopreserved after a stepwise freezing procedure. After stepwise thawing, motility of spermatozoa was slightly lower than that of fresh sperm. Batches of 40-80 eggs were fertilized with cryopreserved spermatozoa, after thawing and activation in solution containing 50 mM NaCl, 20 mM Tris and HCl at pH 7.8; this resulted in 62.2% fertilization success, compared to 70.6 % with fresh sperm.

• Journal of Aquaculture
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• v.13 no.4
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• pp.359-362
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• 2000

Mitotic gynogenesis was induced in the far eastern catfish, Silurus asotus using UV-irradiated heterospecific sperm and cold shock treatment. Eggs were activated with the sperm of mud loach, Misgurnus mizolepis which has been irradiated with UV at dose of 9,000 ergs/$mm^2$. To determine the optimum duration required to prevent the first cleavage, a cold shock at 4$^{\circ}C$ with duration of 20, 30 or 40 min was applied to the eggs 50 min after activation. To induce diploidization of mitogenesis, the most effective protocol was to apply cold shock to 50-min old (after activation) eggs at 4$^{\Circ}C$ for 30min.

• Journal of Aquaculture
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• v.16 no.1
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• pp.51-58
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• 2003

The first Indian transgenic fish was generated in 1991 using borrowed constructs from foreign sources. To construct transformation vectors for the indigenous fishes, growth hormone genes of rohu (r-CH), Labeo rohita and catfish, Heteropneustes fossilis were isolated, cloned and sequenced; their fidelity was confirmed in prokaryotic and eukaryotic systems. A vector was constructed with grass carp b-actin promoter driving the expression of r-GH. Rohu eggs are large. fragile and swell 2~3 times. when fertilized. Hence they were amenable only for electroporated sperm-mediated gene transfer. Accordingly, the sperm electroporation technique was standardized to ensure 25% hatchling survival and 37% Presumptive transgenics without suffering any deformity. Southern analysis confirmed genomic integration in 15% of the tested individuals (Ti) belonging to family lines 2 and 3: another 25% of the Juveniles (Te) were also proved transgenic but with the transgene persisting extrachromosomally for longer than 1 to 2 years. perhaps due to the presence of replicon in the vector. Transgenics belonging to different family lines grew 6~8 times faster than the respective controls. Difference in growth trends of Ti and Te within a family line was not significant. In the Ti family 3 remarkable growth acceleration was sustained for a period longer than 36 weeks but in those of family 2, it gradually decreased. All transgenic fishes including the rohu converted the food at a significantly higher efficiency. Barring the transgenic mudloach, all the other transgenic fishes consumed food at significantly reduced rate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.5
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• pp.480-485
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• 2003

Morphology of the spermatozoa from the testes of the catfish (Pseudobagrus brevicorpus) was studied by transmission and scanning electron microscopy. The spermatozoa of P. brevicorpus are approximately $82.25\pm0.06\;{\mu}m$ in length and relatively simple cells composed of a spherical head, a short midpiece and a tail as in most teleost fish, The nucleus measuring about $2.00\pm0.02\;{\mu}m$ in length is depressed with a deep nuclear fossa of about $1.05\pm0.03\;{\mu}m$ in length three fifths of the nuclear length. The nuclear fossa contains the proximal and distal centrioles. The two centrioles are oriented approximately $150^{\circ}$ to each other. The mitochondria are arranged in two layers and their number is 12 or more. They are separated from the axoneme by the cytoplasmic canal. The axoneme is the 9+2 microtubular pattern and has inner but no outer dynein arms as in other bagrids. The axonemal fins were the closed to axonemal doublet 3 and 8. The axonemal fins and lost outer dynein arm are shared in Bagridae and the deep nuclear fossa is shared in Siluriformes. The axonemal fins observed in Bagridae and Amblycipitidae of Siluriformes might be the apomorphic character in Ostariophysi.

• Applied Microscopy
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• v.28 no.1
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• pp.39-48
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• 1998

The spermatozoa of bagrid catfish, Pseudobagrus fulvidraco are approximately $76{\mu}m$ in length, and a relatively simple and elongated cell composed of a spherical head, a short middle piece and a tail. The ultrastructure of spermatozoa of P. fulvidraco is characterized by the following features. The acrosome is absent as in most teleost. The round nucleus measuring about $1.67{\mu}m$ in length and diameter is depressed with a deep nuclear fossa. The nuclear fossa, the length of which is about three-fifths of the nuclear diameter, contains the proximal and distal contrioles. The two centrioles are oriented approximately $160^{\circ}$ to each other. The filamentous materials give rise to satellite appendages arranged tangentially from the triplets of the distal centriole and the doublets of the anterior end of the axoneme toward the nuclear envelope. The mitochondria are not fused and their number is 20 or more. They are arranged in two or three layers and two rings within the cytoplasmic collar and surround the axoneme. They are separated from the axoneme by the cytoplasmic canal. The axoneme is of the 9+2 microtubular pattern and has inner but no outer dynein arms. The two lateral fins are in the same plane with the two central microtubules, the doublets 3 and 8, which are ultrastructural characteristics of the sperm tail unlike other siluroids lacking the lateral fins.

• Development and Reproduction
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• v.6 no.2
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• pp.71-76
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• 2002

Present study was aimed to summary the recent reports of chromosomal technology such like a polyploidv, sex differentiation, gynogenesis, transgenic fish and gene manipulation. Triploid cells for rainbow trout and channel catfish were induced through thermal shocks of varying temperature levels and produced as a industrial use. A monosex fish with homogametic females of 15 species of high valued fish were produced by exposing to irradiation. It seemed that different irradiation was suitable to inactivate the sperm and block the formation in producing the gynogenetic diploids. Since 1985, transgenic fish have been successfully produced by microinjecting or electroporating desired foreign DNA into unfertilized or newly fertilized eggs using about 40 fish species. More recently, transgenic fish have also been produced by infecting newly fertilized eggs with pantropic, defective retroviral vectors carrying desired foreign DNA. These transgenic fish can serve as excellent experimental models for basic scientific investigations as well as in marine biotechnological applications.

• Development and Reproduction
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• v.2 no.1
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• pp.75-80
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• 1998

메기 정자는 그 길이가 약 62.5 \mu m이며 구형의 핵, 짧은 중편 및 꼬리를 ㄱ진 일반적인 메기류 정자의 미세구조적 특징을 나타내었다. 정자는 대부분의 경골어류의 정자에서와 같이 첨체를 가지고 있지 않았으며 염색질은 완전치 농축되어 있었다. 핵와(nuclear fossa)는 약 0.6 \mu m 함입되어 있었고 그 속에 기부 중심립과 말단 중심립의 일부가 포함되어 있었다. 두 중심립은 140 \circ C의 각도로 배열되어 있었으며 말단 중심립에서 9개의 부수체가 언형질막을 향하여 배열되어 있었다. 미토콘드리아는 중편 세포질에서 2층 또는 3층으로 배열되어 있었으며 핵의 후반부와 꼬리의 기부를 둘러싸고 있었다. 꼬리는 축사만으로 구성되어 있었으며 lateral fins는 관찰되지 않았다. 메기 정자의 가장 큰 구조적 특징은 중편 세포질에 구성되어 있는 관구조(tubular structure)이었다. 대부분의 경골어류의 정자는 중편 세포질에 미토콘드리아만을 포함하고 있으나, 메기 정자에서는 중편 세포질의 전반부에 미토콘드리아가 포함되어 있고, 후반부에는 소관이 모여 망상구조를 형성하는 관구조가 잘 발달되어 있었다. 이와 같은 관구조는 현재까지 Characiformes의 정자 이외의 다른 경골어류에서는 보고된 바 없으며 이러한 구조는Characiformes과 메기류의 계통학적 관계를 연구하는데 매우 중요한 형질로 여겨진다. ^u The spermatozoa of Silurus asotus are appoximately 62.5 \mu m in length and relatively simple cells composed of spherical head, a short midpiece and a tail as in most Siluriformes. The ultrastructure of the spermatozoa of S. asotus is characterized by the following features. The nucleus measuring about 1.5 \mu m in length is depressed with a deep nuclear fossa of about 0.6 \mu m in length, two fifth of the nuclear diameter. The fossa contains the proximal centriole and the half of the distal centriole. Two centrioles form an angle of approximately 140 \circ to each other. the nine satellite rays radiate from the outer surface of the distal centriole. the mitochondrea surround the basal nucleus and the axoneme, and are arranged in two or three layers in the postnuclear cytoplasm. The lateral fins are lost in the sperm tail. The most significant feature is manifested in the midpiece. The midpece comprises two parts, the mitochondria and the tubular structure unlike other teleost fishes containing only the mitochondria. The tubular structure was reported only in the spermatozoa of Citharinus belonging to the characiformes of teleost fishes. Thus it is considered to be a good characteristics for the study of phylogenetic link between Siluriformes and Characiformes.