• Korean Journal of Poultry Science
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• v.26 no.2
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• pp.109-118
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• 1999

Hen's eggs have been regarded as one of the best animal bioreactors to produce biologically active peptides originated from many organisms including human. Despite the last decade's efforts to produce transgenic chicken for any commercial purposes, the results so far reported are very disappointing, indicating that hen's eggs are very difficult to crack for transgenesis. Comparatively large female gamete with enormous amount of yolk may be one of the major obstacles in achieving a similar feat to those of other vertebrate species including mouse, sheep, fish and frog. The delay or less efficiency evidenced may instruct to try an alternative way of gens transfer into chicken egg. Sperm-mediated gene transfer is one of them, and may require a great deal of understanding of mechanisms involved in early fertilization and embryonic development. In other animals where the technique was successful, basic mechanisms have been well studied and established only by painstaking efforts for decades. This paper discusses the accumulated knowledge on early fertilization mechanism in the chicken and how can this information be utilitzed to find the alternative gene transfer in making transgenic chicken.

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.192-192
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• 2004

Embryonic germ (EG) cells are undifferentiated stem cells isolated from cultured primodial germ cells (PGC). These cells share many characteristics with embryonic stem cells including their morphology and pluripotency. Undifferentiated porcine EG cell lines demonstrating capacities of both in vitro and in vivo differentiation have been established. (omitted)

• Reproductive and Developmental Biology
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• v.32 no.1
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• pp.15-20
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• 2008

Pronuclear DNA microinjection has been the most universal method in transgenic animal production but its success rate of transgenesis in mammals are extremely low. To address this long-standing problem, we used retrovirus- and lentivirus-based vectors carrying the enhanced green fluorescent protein (EGFP) gene under the control of ubiquitously active cytomegalovirus (CMV) promoter to deliver transgenes to bovine embryos. The rate of transgenesis was evaluated by counting EGFP positive blastocysts after injection of concentrated virus stock into the perivitelline space of the bovine oocytes in metaphase II. Among two different types of lentivirus vectors derived from FIV (feline immunodeficiency virus) and HIV (human immunodeficiency virus), the former scored the higher gene transfer efficiency; almost 100% of the blastocysts developed from the oocytes infected with FIV-based vector were EGFP positive. As for the vectors derived Com HIV lentivirus, the transgenesis rate of the blastocysts was reduced to 39%.

• Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.43-47
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• 2012

Growth hormone (GH) transgenesis in fish has the potential to improve aquaculture efficiency and capacity. However, many fast-growing transgenic fish have experienced side effects caused by excess GH expression. To overcome this unwanted issue associated with several GH transgenic mud loach Misgurnus mizolepis lines carrying GH construct driven by a strong ${\beta}$-actin regulator ($pml{\beta}$-actGH), we performed an alternative version of GH autotransgenesis using a weaker but more stable regulator, the mud loach lectin promoter. GH transgenesis with a pmlectGH construct consisting of the mud loach GH gene driven by the 2.3-kb lectin promoter exhibited significant growth stimulation. However, the extent of the growth acceleration in pmlectGH transgenics (six times maximum when assessed 2 months post hatching) was much less than that in transgenic individuals carrying the $pml{\beta}$-actGH construct. Additionally, the extraordinary gigantism that was common in $pml{\beta}$-actGH-transgenic mud loaches was diminished in transgenic loaches harboring the pmlectGH construct. Transgenic founders (pmlectGH) successfully transmitted their transgene into the next generation with up to 41% frequency. Growth stimulation also persisted in the transgenic F1 strains, with a seven-fold increase in maximum body weight at 6 months of age.

• Proceedings of the KSAR Conference
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• 2009.06a
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• pp.4-5
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• 2009

• Proceedings of the Korean Aquaculture Society Conference
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• 2002.10a
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• pp.12-12
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• 2002

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1536-1540
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• 2012

Chicken primordial germ cells (cPGCs) are founder germ cells in embryonic stage of development that eventually give rise to sperms or oocytes. Currently cPGCs are only known cells enabling germline transmission in chicken and their cultivation protocols were recently established. Although genome modifications of chickens are now theoretically possible using cPGCs, there are still several hurdles to overcome to practically use cPGCs as mediators for chicken transgenesis. First, efficiency of gene delivery into cPGCs remains low with current methods. Second, there aregene silencing mechanisms against the expression of foreign genes in cPGCs. In this study, we successfully increased the efficiency of gene delivery in cPGCs by taking advantage of the TTAA-specific $piggybac$ transposon system. Moreover, a pipette-type electroporator significantly enhanced transfection efficiency up to 5-fold compared withcuvette-type methods. Taken together, the technological advances in our study will provide practical benefits for the application to fulfill genetic modifications of chicken genome.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.1
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• pp.34-39
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• 2006

Molecular biology and microalgal biotechnology have the potential to play a major role in improving the production efficiency of a vast variety of products including functional foods, industrial chemicals, compounds with therapeutic applications and bioremediation solutions from a virtually untapped source. Microalgae are a source of natural products and have been recently studied for biotechnological applications. Efficient genetic transformation systems in microalgae are necessary to enhance their potential to be used for human health. A microalga such as Chlarella is a eukaryotic organism sharing its metabolic pathways with higher plants. This microalga is capable of expressing, glycosylating, and correctly processing proteins which normally undergo post-translational modification. Moreover, it can be cultured inexpensively because it requires only limited amount of sunlight and carbon dioxide as energy sources. Because of these advantages, Chlarella may be of great potential interest in biotechnology as a good candidate for bioreactor in the production of pharmaceutical and industrial compounds for human functional foods. Here, we briefly discuss recent progress in microalgal transgenesis that has utilized molecular biology to produce functional proteins and bioactive compounds.

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.213-213
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• 2004

Exogeneous DNA can reproducibly be delivered by co-injected spermatozoa and this transgenesis method is very efficient protocol. But, mosaic patterns of transgenic embryos and offspring were shown frequently. Whole blastomere integration is important in transgenic animal economics. (omitted)

• Biomolecules & Therapeutics
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• v.22 no.4
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• pp.267-274
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• 2014

Drug development and preclinical trials are challenging processes and more than 80% to 90% of drug candidates fail to gain approval from the United States Food and Drug Administration. Predictive and efficient tools are required to discover high quality targets and increase the probability of success in the process of new drug development. One such solution to the challenges faced in the development of new drugs and combination therapies is the use of low-cost and experimentally manageable in vivo animal models. Since the 1980's, scientists have been able to genetically modify the mouse genome by removing or replacing a specific gene, which has improved the identification and validation of target genes of interest. Now genetically engineered mouse models (GEMMs) are widely used and have proved to be a powerful tool in drug discovery processes. This review particularly covers recent fascinating technologies for drug discovery and preclinical trials, targeted transgenesis and RNAi mouse, including application and combination of inducible system. Improvements in technologies and the development of new GEMMs are expected to guide future applications of these models to drug discovery and preclinical trials.