• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11a
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• pp.76-100
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• 2000

A brief general discussion of the nature and function of biosensors is presented. While the primary motivator for biosensor development has been the health-care industries, recent research efforts have spread to problems in agriculture and biological production systems. To illustrate some of the research from our laboratory, three example biosensors and their corresponding applications are presented. The first of these is an immunosensor for measurement of the hormone progesterone during milking as a method to improve reproductive management of dairy herds. The second example is an enzyme sensor for measurement of urea in milk as a menas to determine the efficiency of conversion of input protein to milk protein and, thus, improve nutritional management of dairy herds. The third example is a DNA sensor using polymerase chain reaction to detect pathogenic bacteria in the wash water of fresh and minimally processed fruits and vegetables. The potential for application of biosensors in agriculture, agrobiotechnology, food processing, and environmental monitoring has barely been realized.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.9
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• pp.1211-1216
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• 2011

Sexual maturity in poultry is controlled by a complex neural circuit located in the basal forebrain, which integrates the central and peripheral signals to activate hypothalamic gonadotrophin-releasing hormone (GnRH) secretion. This study demonstrated the changes of GnRH-I, POMC and NPY mRNA transcription in hypothalamus and IGF-I and leptin levels in serum of Shaoxing ducks during puberty. Body weight increased progressively from d30 to d120 and at d120 the flock reached 5% of laying rate. A significant upregulation of hypothalamic GnRH-I mRNA expression was observed from d60, reaching the peak at d120. POMC and NPY mRNA expression in hypothalamus showed a similar pattern, which increased from d30 to d60, followed by a significant decrease towards sexual maturity. Serum IGF-I levels exhibited two peaks at d30 and d120, respectively. Serum leptin displayed a single peak at d90. The results indicate that the down-regulation of POMC and NPY genes in hypothalamus coincides with the up-regulation of GnRH-I gene to initiate sexual maturation in ducks. In addition, peripheral IGF-I and leptin may relay the peripheral metabolic status to the central system and contribute to the initiation of the reproductive function in ducks.

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.47-54
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• 2011

Endocrine disruptors bind to hormone receptors on sperm membrane, therefore spermatozoa are potentially a useful model for examining estrogenic activities of endocrine disruptors. The objective of this study was to compare the effects of two xenoestrogenic compounds [genistein (Gen) and 4-tert-octylphenol (OP)] to those of two steroids [estrogen ($E_2$) and progesterone ($P_4$)] on boar sperm % motility and motion kinematics of in vitro. Porcine spermatozoa were incubated with various concentrations ($0.001{\sim}100\;{\mu}M$) of each chemical for 15 or 30 min, and then assessed % motility and sperm motion kinematics using computer assisted sperm analyzer (CASA). Each chemical decreased sperm % motility, and OP decreased VSL and VAP compared with untreated control(p<0.05). $E_2$ stimulated the motion kinematic changes except VCL. Moreover, Gen had effects on VCL and VAP alterations after 30 min incubation. In summary, since all chemicals studied effectively altered sperm % motility and motion kinematics, it was concluded that porcine spermatozoa could be a useful model for in vitro screening of potential endocrine disruptors.

• Toxicological Research
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• v.17 no.2
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• pp.115-121
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• 2001

Some of endocrine disruptors with sexual hormone-like effects have been increasingly reported to be immunotoxic in many species in recent several years. Phthalate esters have possible effects on the endocrine system. Prenatal exposure to di(n-butyl) phthalate (DBP) has been reported to impair the androgen-dependent development of the male reproductive tract in rat. Therefore, the immunomodulatory effect of DBP was investigated in the developing immune system of fetal and neonatal Sprague-Dawley rats. Timed-bred pregnant SD rats were given to the doses of 0, 250, 500, and 750 mg DBP/kg$\cdot$ body weight /day by gavage once a day from gestational day (GD) 5 to 18. On GD19 or GD22/postnatal day one (PD1), the dams were euthanized, and the changes in organ weights and thymus phenotypes were examined for their offsprings. At 750 mg DBP/kg$\cdot$b.w./day in maternal exposure group, GD19 fetuses showed decreases in body weight. The spleen/body weight ratios were reduced in GD 19 fetuses from the dams exposed to 500 and 750 mg DBP/kg$\cdot$b.w./day. There were no significant changes in thymus and spleen cellularities though these cellularities showed a tendency to decrease in a dose dependent way. In the DBP-exsposed GD22/PD1 offsprings, the body weights, the relative organ weights and the cellularities did not exhibit alteration. Additionally, the percentages of CD3$^{+}$(CD4$^{+}$CD8$^{+}$, CD4$^{+}$CD8$^{-}$, CD4$^{-}$CD8$^{+}$, and CD4$^{-}$CD8$^{-}$) and CD3$^{-}$(CD4$^{+}$CD8$^{+}$, CD4$^{+}$CD8$^{-}$, CD4$^{-}$CD8$^{+}$, and CD4$^{-}$CD8$^{-}$) thymocyte subsets were not changed in any DBP-treated group. The proliferative responses of splenic T cells to Con A and B cells to LPS were decreased in all DBP-exposed GD22/PD1 offsprings.

• Reproductive and Developmental Biology
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• v.28 no.3
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• pp.197-202
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• 2004

Human PTH (parathyroid hormone) is known to be efficacious for curing osteoporesis. In this study, we attempted to construct genetically modified porcine cell lines that can ultimately be used for donor cells in nuclear transfer-mediated transgenesis. By using retrovirus vectors carrying tetracycline-regulatory expression system and WPRE (woodchuck hepatitis virus posttranscriptional regulatory element) sequence, we could control PTH expression with tetracycline and boost the promoter activity. Considering that low or constitutive expression of the transgene has been one of major problems that needs to be solved in transgenic animal studies, our results could be helpful in successful production of transgenic pigs as bioreactors.

• Reproductive and Developmental Biology
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• v.35 no.3
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• pp.355-361
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• 2011

Ski protein is implicated in proliferation/differentiation in a variety of cells. We had previously reported that Ski protein is present in granulosa cells of atretic follicles, but not in preovulatory follicles, suggesting that Ski has a role in apoptosis of granulosa cells. The alternative fate of granulosa cells other than apoptosis is to differentiate to luteal cells, however, it is unknown whether Ski is expressed and has a role in granulosa cells undergoing luteinization. Thus, the aim of the present study was to locate Ski protein in the rat ovary during luteinization to predict the possible role of Ski. In order to examine the expression pattern of Ski protein along with the progress of luteinization, follicular growth was induced by administration of equine chorionic gonadotropin to immature female rat, and luteinization was induced by human chorionic gonadotropin treatment to mimic luteinizing hormone (LH) surge. While no Ski-positive granulosa cells were present in preovulatory follicle, Ski protein expression was induced in response to LH surge, and was maintained after the formation of corpus luteum (CL). Though Ski protein is absent in granulosa cells of preovulatory follicle, its mRNA (c-ski) was expressed and the level was unchanged even after LH surge. Taken together, these results demonstrated that Ski protein expression is induced in granulosa cells upon luteinization, and suggested that its expression is regulated post-transcriptionally.

• Reproductive and Developmental Biology
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• v.38 no.3
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• pp.99-105
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• 2014

In this study, to further understand the mechanism of animal growth and to develop a miniature transgenic animal model, we constructed and tested tetracycline-inducible RNAi system using shRNA targeting the mRNA of mouse insulin-like growth factor (mIGF-1) or mouse growth hormone receptor (mGHR) gene. Quantitative real-time PCR analysis of mouse liver cell (Hepa1c1c7) cells transfected with these vectors showed 85% or 90% of expression inhibition effect of IGF-1 or GHR, respectively. In ELISA analysis, the protein level of IGF-1 in the cells expressing the shRNA targeting IGF-1 mRNA was reduced to 26% of non-transformed control cells. Unexpectedly, in case of using shRNA targeting GHR, the IGF-1 protein level was decreased to 75% of control cells. Further experiments are needed to explain the lower interference effect of GHR shRNA in IGF-1 protein. Accumulated knowledge of this approach could be applicable to a variety of related biological area including gene function study, gene therapy, development of miniature animals, etc.

• Journal of Embryo Transfer
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• v.28 no.2
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• pp.87-93
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• 2013

The efficiency of artificial insemination (AI) for horses remains unsatisfactory. It is mainly because each process of AI causes a detrimental effect on semen quality. To sustain quality of semen properly, several factors including libido of stallions and sperm damage during sperm processing and preservation should be considered. Stallions with decent libido produce a high ratio of sperm to seminal plasma in their ejaculates, which is the ideal semen composition for maintaining sperm quality. Thus, to maximize the fertility rate upon AI, stallions should be appropriately managed to enhance their libido. Seminal plasma should have a positive effect on horse fertility in the case of natural breeding, whereas the effects of seminal plasma on both sperm viability and quality in the context of AI remain controversial. Centrifugation of semen is performed during semen processing to remove seminal plasma and to isolate fine quality sperm from semen. However, the centrifugation process can also result in sperm loss and damage. To solve this problem, several different centrifugation techniques such as Cushion Fluid along with dual and single Androcoll-E$^{TM}$ were developed to minimize loss of sperm and to damage at the bottom of the pellet. Most recently, a new technique without centrifugation was developed with the purpose of separating sperm from semen. AI techniques have been advanced to deliver sperm to optimal region of female reproductive tract at perfect timing. Recombinant equine luteinizing hormone (reLH) and low dose insemination techniques have been developed to maximize both fertility rate and the efficiency of AI. Horse breeders should consider that the entire AI procedure should be optimized for each stallion due to variation in individual horses for a uniformed AI protocol.

• Reproductive and Developmental Biology
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• v.33 no.2
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• pp.77-83
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• 2009

Erythropoietin (EPO), a glycoprotein hormone produced from primarily cells of the peritubular capillary endothelium of the kidney, is responsible for the regulation of red blood cell production. We have been investigating the roles of glycosylation site added in the biosynthesis and function of recombinant protein. We constructed three EPO mutants ($\Delta$69, $\Delta$105 and $\Delta$69,105), containing an additional oligosaccharide chains. EPOWT and EPO$\Delta$69 were effectively expressed in transient and stably transfected CHO-K1 cell lines. But, it wasn't detected any protein in the culture medium of EPO$\Delta$105 and EPO$\Delta$69,105 mutants. The growth and differentiation of EPO-dependent human leukemic cell line (F36E) were used to measure the cytokine dependency and in vitro bioactivity of rec-hEPO. MTT assay values were increased by survival of F36E cells at 24h. To analysis biological activity in vivo, two groups of ICR-mice (7 weeks old) were injected subcutaneously with 10 IU per mice of rec-hEPO molecules on days 0 and 2. Red blood cell and hematocrit values were measured on 6 days after the first injection. The hematocrit values were remarkably increased in all treatment groups. The pharmacokinetic analysis was also affected in the mice injected with rec-hEPO molecules 2.5 IU by tail intravenous. Protein samples were detected by Western blotting. An EPO$\Delta$69 protein migrated as a broad band with an average apparent molecular and detected slightly high band. Enzymatic N-deglycosylation resulted in narrow band and was the same molecular size. The biological activity of EPO$\Delta$69 was enhanced to compare with wt-hEPO. The half-life was longer than wt-hEPO. The results suggest that hyperglycosyalted recombinant human erythropoietin (EPO$\Delta$69) may have important biological and therapeutic good points.

• Korean Journal of Psychosomatic Medicine
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• v.7 no.2
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• pp.149-157
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• 1999

Food intake and body weight are determined by a complex interaction of regulatory pathways. Leptin, the product of the ob gene, is a recently discovered hormone secreted by adipocytes, that signals the amount of adipose tissue energy stores to the brain and exerts major effects on energy homeostasis and neuroendocrine function. In addition, leptin has recently been shown to affect reproductive function in rodents and humans. The study of leptin and its effectors in the hypothalamus may provide important insights with respect to the interplay of several hypothalamic neuropeptides in regulating feeding as well as the interaction of genetics and environment in the regulation of energy homeostasis. In this review we summarise the action of leptin in the regulation of food intake and highlight a working model of the effects of environmental factors on the leptin system.