• Asian-Australasian Journal of Animal Sciences
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• v.9 no.5
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• pp.551-556
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• 1996

Selenium (Se) apparent absorption and retention in sheep as influenced by diets differing in protein content through soybean meal supplementation was studied. A $3{\times}3$ Latin square design was used with three Japanese Corriedale wethers (45 kg average body weight), three periods, and three dietary treatments. In each period, 7 d dietary adjustment was followed by 5 d total collection of urine and feces. The three dietary treatments were : Diet 1, without soybean meal supplementation (14% crude protein, CP); Diet 2, with 10% soybean meal supplementation (16.5% CP); and Diet 3, with 20% soybean meal supplementation (19% CP). All the diets had a Se supplementation in the form of sodium selenite at 0.2 mg Se/kg dietary DM. The dietary DM intake of the animals was 2% of their body weight. No significant differences were obtained among the three dietary treatments of the Se balance of the animals. However, as percent of Se intake, only urinary Se concentration of Diet 3 was markedly lower (p < 0.05) than the other diets. Fecal Se as percent of Se intake followed the trend of Diet 3> Diet 2 > Diet 1 resulting a Se absorbed as percent of Se intake of 58.9%, 62.3% and 68.2% for Diets 3, 2 and 1, respectively but their differences among each other were insignificant. No significant differences that were observed either on Se retained as percent of intake (Diet 1, 48.2%; Diet 2, 45.2%; Diet 3, 46.0%) or Se retained as percent of Se absorbed (Diet 1, 70.7%; Diet 2, 72.4%; Diet 3, 77.9%). Significant correlation coefficients among the various measures of Se utilization were also observed. Regression analysis showed the following equation: Y = 93.8 - 1.86X (p <0.05, $r^{2}=0.48$), where Y is the Se absorbed as percent of Se intake (%) and X is the dietary protein content (%). This study concludes that Se requirement in sheep is greater when dietary protein content is high.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.1-13
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• 2006

Response of grain yield and milled-rice protein content to nitrogen topdress (N) timing at panicle initiation stage (PIS) is critical for quantifying real-time N requirement for target grain yield and milled-rice protein content. Two split-split-plot experiments with three replications, one in 2004 and the other in 2005, were conducted in Experimental Farm, Seoul National University, Suwon, Korea. The experiments included three N rates at tillering stage (TS), three N timing treatments at panicle initiation stage (PIS) and two rice cultivars. The N rates at TS, N timing at PIS, and rice cultivars were randomly assigned to main plot, sub plot, and sub-sub plot, respectively. Results showed that the delayed N application at PIS reduced grain yield in 2004 and increased milled-rice protein content in both years significantly at 0.05 probability level. The calculated optimum N timing at PIS from pooled data by N rates and rice cultivars in two years was at 28 days before heading (DBH). However, real-time of N timing at PIS was dependent on plant growth and N status around PIS that in turn was dependent on applied N rates at TS. The optimum N timing at PIS was at 30 DBH for no N treatments at TS while at 27 DBH for 3.6 and 7.2 kg N/10a treatments and at 27 and 29 DBH for Hwaseongbyeo and Daeanbyeo, respectively. In general, earlier applied N at PIS resulted in lower milled-rice protein content but the highest grain yield was expected to be obtained when N topdress at PIS was applied at the time when shoot N concentration started to drop below about 23 mg/g due to dilution effect after transplanting. In conclusion, the results of our experiments imply that the currently recommended N topdress time (24DBH) at PIS in Korea should be reconsidered for the higher grain yield and the better quality of rice.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.10
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• pp.1440-1444
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• 2000

Two feeding trials were conducted to evaluate the effects of inclusion levels of dietary vitamin and trace mineral (VTM) premixes on growth and nutrient digestibility in growing pigs. A total of 112 pigs ($24.82{\pm}3.22kg$) were employed for 49 days (exp. 1), and 168 pigs ($21.64{\pm}1.41kg$) for 40 days (exp. 2) in completely randomized block designs. Treatments were: 1) 100%, 2) 150%, 3) 200% and 4) 250% NRC (1998) requirement of VTM in exp. 1, and the ratio of vitamins to trace minerals at 1) 100:100%, 2) 100:150%, 3) 150:100% and 4) 150:150% of NRC (1998) requirement in exp. 2. Basal diets for feeding trials were formulated to contain 3,310 kcal ME/kg and 18% crude protein, and contained 0.25% chromic oxide as an indigestible marker for digestibility trials. Increasing dietary VTM premix in growing pigs had linear and quadratic effects (p<0.05) on ADG, and feed conversion ratio was also improved (p<0.05) as VTM premix was increased by 150-250% of NRC (1998) requirements in exp. 1. Adding vitamin to trace mineral premixes at 150% NRC (1998) over the control improved (p<0.05) ADG and feed efficiency in growing pigs, but performances were not improved by vitamin nor by trace mineral premixes alone (p>0.15) (exp. 2). There were no differences (p>0.05) in the digestibilities of energy, crude protein and fat among dietary treatments. However, increasing dietary VTM premix in growing pigs had a linear effect (p<0.05) on the digestibilities of calcium and phosphorus. The 200 or 250% fed group showed improved (p<0.05) calcium digestibility, and 250% fed group also showed improved (p<0.05) phosphorus digestibility as compared to 100% or 150% fed group (exp. 1). The digestibilities of Ca and P were higher (p<0.05) in 150% addition of vitamins than in 150% addition of trace minerals in the diet (exp. 2).

• Animal cells and systems
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• v.2 no.1
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• pp.87-91
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• 1998

The present study investigated the involvement of the phospholipase C (PLC) and protein kinase C (PKC) signaling pathways during progesteroneinduced meiotic maturation in amphibian (Rana dybowskii) oocytes. Prosesterone-induced germinal vesicle breakdown (GVBD) of oocytes was significantly inhibited by a PKC inhibitor, staurosporine and a PLC inhibitor, U73122, in a dose-dependent manner. In contrast, U73343, an inactive analogue of U73122, was ineffective in suppressing GVBD. PKC activity in oocytes reached a maximum level at 30 min after progesterone stimulation and this elevated PKC activity was effectively suppressed by U73122 or staurosporine, suggesting that the activation of PKC enzyme is closely linked to PLC signaling during oocyte maturation. In addition, these inhib itors blocked the maturation promoting factor (MPF) activity which appeared in oocytes in response to progesterone, suggesting that PKC activation is an important signal for MPF activity. Therefore, this study demonstrates that the activation of PKC via PLC signaling is directly linked to an intracellular protein kinase cascade related to the appearance of MPF activity during meiotic maturation in amphibian (Rana dybowskii) oocytes.

• Biomolecules & Therapeutics
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• v.21 no.2
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• pp.97-106
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• 2013

Chronic hepatitis C virus (HCV) infection is responsible for the development of liver cirrhosis and hepatocellular carcinoma. HCV core protein plays not only a structural role in the virion morphogenesis by encapsidating a virus RNA genome but also a non-structural role in HCV-induced pathogenesis by blocking innate immunity. Especially, it has been shown to regulate JAK-STAT signaling pathway through its direct interaction with Janus kinase (JAK) via its proline-rich JAK-binding motif ($^{79}{\underline{P}}GY{\underline{P}}WP^{84}$). However, little is known about the physiological significance of this HCV core-JAK association in the context of the virus life cycle. In order to gain an insight, a mutant HCV genome (J6/JFH1-79A82A) was constructed to express the mutant core with a defective JAK-binding motif ($^{79}{\underline{A}}GY{\underline{A}}WP^{84}$) using an HCV genotype 2a infectious clone (J6/JFH1). When this mutant HCV genome was introduced into hepatocarcinoma cells, it was found to be severely impaired in its ability to produce infectious viruses in spite of its robust RNA genome replication. Taken together, all these results suggest an essential requirement of HCV core-JAK protein interaction for efficient production of infectious viruses and the potential of using core-JAK blockers as a new anti-HCV therapy.

• BMB Reports
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• v.34 no.2
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• pp.102-108
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• 2001

A time-dependent folding process was used to determine whether or not protein disulfide isomerase (PDI) plays an important role in the maturation of nascent lactoferrin polypeptides. Interaction between lactoferrin and PDI was analyzed according to the co-immunoprecipitation of the two proteins. The results indicate that lactoferrin folding requires a significant interaction with PDI and its binding is relatively brief compared to other nascent polypeptides. The amount of lactoferrin interacting with PDI increases up to half a minute and sharply decreases beyond this time point. During the refolding process that follows reduction by DTT, lactoferrin polypeptides heavily interact with PDI and the interaction period was extended compared to the normal folding process. In terms of the temperature effect on PDI-lactoferrin interaction, PDI binds to lactoferrin polypeptides longer at a lower temperature (here, $25^{\circ}C$) than $37^{\circ}C$. The lactoferrin-PDI interaction was also studied in vitro. According to the in vitro experiment data, PDI was still functional in cell lysates assisting lactoferrin folding into the mature form. PDI interacts with lactoferrin polypeptides for an extended period during the folding in vitro. During the refolding process in vitro, intermolecular aggregates and refolding oligomers matured into a functional form after PDI binds to the lactoferrin. These results suggest that PDI provides a prolonged chaperoning activity in the refolding processes and that there appears to be a greater requirement for PDI chaperone activity in the refolding of lactoferrin polypeptides.

• Asian-Australasian Journal of Animal Sciences
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• v.7 no.4
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• pp.493-498
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• 1994

The response of crossbred Holstein milking cows to the neutralized urea-treated rice straw feeding was investigated. Rice straw was treated with 6% urea for at least 21 days and further with sulfuric acid for overnight to complete the neutralization. The neutralized straw was then sun-dried and its feeding value was compared with that of the dried non-neutralized urea-treated straw. They were fed to the cows with concentrates either by the ration formulation based on the nutrient requirements for milk production recommended by NRC or by the traditional way in which straw was fed ad libitum and concentrates at 1 kg/2 kg of milk production. The results showed that milk production as well as milk composition of cows were not different between neutralized and non-neutralized straw. The feeding of the neutralized straw could significantly reduce the supply of protein-rich feed such as soybean oil meal, and it was demonstrated that ammonium sulfate in the neutralized straw could be utilized as effective as the plant origin protein. The results also suggested that if the traditional feeding method is applied to the dairy cattle, protein content of the supplementing concentrates should be increased to meet the requirement.

• BMB Reports
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• v.31 no.5
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• pp.468-474
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• 1998

Membrane depolarization in PC12 cells induces calcium influx via an L-type voltage-sensitive calcium channel (L-VSCC) and increases intracellular free calcium, which leads to tyrosine phosphorylation of epidermal growth factor (EGF) receptor and the associated adaptor protein, She. This activated EGF receptor complex then can activate mitogen-activated protein (MAP) kinase, as in nerve growth factor (NGF) receptor activation. In the present study, we investigated the role of EGF receptor in the signaling pathway initiated by membrane depolarization of PC12 cells. Prolonged membrane depolarization induced phosphorylation of extracellular signal-regulated kinase (ERK) within 1 min in undifferentiated PC12 cells. Pretreatment of PC12 cells with the calcium chelator EGTA abolished depolarization-stimulated ERK phosphorylation, but NGF-induced phosphorylation of ERK was not affected. The chronic treatment of phorbol ester, which down-regulated the activity of protein kinase C (PKC), did not affect the phosphorylation of ERK upon depolarization. In the presence of an inhibitor of EGF receptor, neither depolarization nor calcium ionophore increased the level of ERK phosphorylation. These data imply that the EGF receptor is functionally necessary to activate ERK and neurite outgrowth in response to the prolonged depolarization in PC12 cells, and also that PKC is apparently not involved in this signaling pathway.

• BMB Reports
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• v.48 no.8
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• pp.445-453
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• 2015

Endoplasmic Reticulum (ER) is an organelle where most secretory and membrane proteins are synthesized, folded, and undergo further maturation. As numerous conditions can perturb such ER function, eukaryotic cells are equipped with responsive signaling pathways, widely referred to as the Unfolded Protein Response (UPR). Chronic conditions of ER stress that cannot be fully resolved by UPR, or conditions that impair UPR signaling itself, are associated with many metabolic and degenerative diseases. In recent years, Drosophila has been actively employed to study such connections between UPR and disease. Notably, the UPR pathways are largely conserved between Drosophila and humans, and the mediating genes are essential for development in both organisms, indicating their requirement to resolve inherent stress. By now, many Drosophila mutations are known to impose stress in the ER, and a number of these appear similar to those that underlie human diseases. In addition, studies have employed the strategy of overexpressing human mutations in Drosophila tissues to perform genetic modifier screens. The fact that the basic UPR pathways are conserved, together with the availability of many human disease models in this organism, makes Drosophila a powerful tool for studying human disease mechanisms. [BMB Reports 2015; 48(8): 445-453]

• Journal of Microbiology
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• v.34 no.1
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• pp.30-36
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• 1996

We have exmained the re-establishment of HIMRE mediated silencing function on the transcriptional activity of yeast heast shock gene HSP82. To test whether the onset of SIR repression can occur in growing cells in the rpesence of a potent inhibitor of DNA replication, HMRa/HSP82 strains with SIR4- and SIR4S$^{+}$ genetic backgrounds were arrested in S phase by incubation of a culture in 200 mM hydroxyurea for 120 min. It was clear that following a 20 minute heat shock, silencing of the HMRa/HSP82 allele in cells pretreated with hydroxyurea does occur in a SIR4-dependen fashion, even though the kinetics of repression appears to be substantially delayed. We also have tested whether re- establishement of silencing at the HMR/hsp82 locus can occur in G1-arrested cells. Cell cycle arrest at G1 phase was achieved by treatment of early log a cell cultures with .alpha.-factor mating pheromone, which induces G1 arrest. The result suggests that passage through S phase (and therefore DNA replication) is nor required for re-establishing silencer-mediated repression at the HMNRa/HSP82 locus. Finally, to test whether de nono protein synthesis is required for re-establishment of silencer-mediated repression, cells were pretreated with cycloheximide (500 /.mu.g/ml) 120 min. It was apparent that inhibiting protein synthesis delays, but does not prevent, re-establishment of silencer-mediated repression. Altogether, these results indicate that re-establishment of silencer-mediated repression is not dependent on the DNA replication and has no requirement for protein synthesis.s.