• Applied Chemistry for Engineering
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• 제25권1호
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• pp.90-95
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• 2014

Nylon66 extrudates as a function of the extrusion number were prepared by a twin screw extruder. Chemical structures, thermal properties, melt index, crystal structures, mechanical properties such as the tensile strength, elongation at break and impact strength, and rheological property were measured by FT-IR, $^1H$-NMR, melt indexer, DSC, TGA, XRD, universal tensile tester, Izod impact tester, and rheometer. FT-IR and $^1H$-NMR characterizations indicated that the number of extrusions did not affect the chemical structure. The decrease in the molecular weight was checked by the melt index of extrudates. There were no effects of the thermal history on the melting and degradation temperature. The tensile and impact strength and modulus were found to be similar, regardless of the number of extrusions, but the elongation decreased significantly. The complex viscosity of extrudates at low frequencies decreased with the extrusion number. No structural changes after extrusion were confirmed from the fact that there was no change in the slope and shape of G'-G" plot.

• Journal of Marine Life Science
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• 제5권2호
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• pp.58-63
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• 2020

The ascidian Halocynthia aurantium (sea peach), which belongs to the phylum Chordata, is thought to be a valuable organism of aquaculture like H. roretzi (sea pineapple), but its biological characteristics such as development and ecology are not well known. In this study, in order to obtain basic data for H. aurantium farming, the development processes of H. aurantium inhabiting the east coast of Gangwon-do were investigated and compared with those of H. roretzi, a related species. As a result, the morphology and developmental stages of the fertilized eggs, embryos and larvae of H. aurantium were very similar to those of H. roretzi. Fertilized eggs of H. aurantium took about 42.1 hours to hatch at 11℃, almost similar to 40.9 hours of H. roretzi. The time required for larvae to metamorphose into juveniles after hatching was very similar between the two species. The hatched larvae of the two species became juveniles with oral and atrial siphons after 23 days at 11℃. Both types of embryos developed slowly in seawater at low temperatures and rapidly developed at high temperatures. Fertilized eggs of H. aurantium hatched in an average of 62.3 hours at 9℃, 42.1 hours at 11℃, and 36.3 hours at 13℃, whereas those of H. roretzi hatched in an average of 60.4 hours, 40.9 hours, and 35.2 hours. Most of H. aurantium embryos did not develop normally above 15℃, so it is thought that attention is needed in the seed production processes.

• Journal of Applied Biological Chemistry
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• 제66권
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• pp.197-203
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• 2023

Callus cultivation is a method for producing a large amount of tissue of a plant in the laboratory, regardless of the environment. Lycoris chejuensis, a plant species native to jeju island, is a member of the Lycoris family has been used as a traditional medicine for the treatment of diverse diseases. In this study, we evaluated anti-inflammatory effect of biorenovated Lycoris chejuensis callus (LCB) in lipopolysaccharide (LPS)-induced RAW264.7 cells. As a result, LCB was less toxic to the cells in the concentration range of 25, 50, and 100 ㎍/mL as shown by the improved viability of LCB treated cells than compared to Lycoris chejuensis callus (LC) treatment. In addition, LCB inhibited the generation of NO and prostaglandin E₂ through the suppression of inducible nitric oxide synthase and cyclooxygenase-2 protein expression. LCB also attenuated the expression of interleukin-1β, interleukin-6 and tumor necrosis factor-α induced by LPS. The results suggest that LCB has anti-inflammatory activity on the LPS-induced inflammatory response and may be suitable for the development of potent functional cosmetic material.

• Korean Journal of Animal Reproduction
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• 제26권1호
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• pp.41-51
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• 2002

The present study was carried out to examine the effect of cysteamine in vitro maturation (IVM) of porcine oocytes and development of porcine IVM/IVF Embryos. The results were summarized as follows : 1. The rates of nuclear maturation, penetrated oocytes, pronuclear formation, polyspermic oocytes and mean numbers of the penetrated sperm were not different in NCSU23 maturation medium with 0, 25, 50 and 100 $\mu$M cysteamine (P〉0.05). 2. The rates of blastocyst formation at day 7 after in vitro fertilization in 0, 25, 50 and 100 $\mu$M cysteamine were 17.9$\pm$6.1, 17.4$\pm$6.3, 24.2$\pm$1.9 and 16.9$\pm$2.0%, respectively. And the total cells were 30.7$\pm$2.4, 34.9$\pm$2.8, 39.6$\pm$2.3 and 36.8$\pm$3.6, respectively. Fifty $\mu$M cystealnine group was significantly higher than those of any other treatment groups (P＜0.05). 3. The ratios of ICM/total cells in 20~40% category were 20.5, 41.6, 19.5 and 31.5%, respectively. Twenty five $\mu$M cysteamine group was higher than those of other groups. 4. The rates of blastocyst formation at day 7 in the NCSU-23 culture medium of porcine IVF-produced embryos with 0, 25, 50, and 100 $\mu$M cysteamine were 16.0$\pm$0.2, 13.6$\pm$1.7, 25.0$\pm$0.8 and 15.7$\pm$4.5%, respectively. And the total cells were 27.0$\pm$3.7, 36.1$\pm$4.8, 34.0$\pm$3.8 and 25.2$\pm$4.4, respectively. Fifty $\mu$M cysteamine group was significantly higher than those of any other treatment groups (P＜0.05). 5. The ratios of ICM/total cells in 20~40% category were 53.8, 30.0, 16.6 and 11.1%, respectively. The addition groups of cysteamine were lower than those of control group. In conclusion, these results suggested that the addition of 50 $\mu$M cysteamine in the IVM medium and 25~50 $\mu$M cysteamine in IVC medium were effective on the blastocyst formation and total cells of blastocysts.

• Journal of Life Science
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• 제27권1호
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• pp.100-121
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• 2017

The sexual reproduction of the unicellular green alga Chlamydomonas is reviewed for a comprehensive understanding of the complex processes. The sexual life cycle of C. reinhardtii is distinguished into five main stages: gametogenesis, gamete activation, cell fusion, zygote maturation, and meiosis and germination. Gametogenesis is induced by nitrogen starvation in the environment. C. reinhardtii has two mating types: mating type plus ($mt^+$) and mating type minus ($mt^-$), controlled by a single complex mating type locus ($MT^+$ or $MT^-$) on linkage group VI. In the early gametogenesis agglutinins are synthesized. The $mt^+$ and $mt^-$ agglutinins are encoded by the autosomal genes SAG1 (Sexual AGglutination1) and SAD1 (Sexual ADhesion1), respectively. The agglutinins are responsible for the flagellar adhesion of the two mating type of gametes. The flagellar adhesion initiates a cAMP mediated signal transduction pathways and activates the flagellar tips. In response to the cAMP signal, mating structures between two flagella are activated. The $mt^+$ and $mt^-$ gamete-specific fusion proteins, Fus1 and Hap2/Gcs1, are present on the plasma membrane of the two mating structures. Contact of the two mating structures leads to develop a fertilization tubule forming a cytoplasmic bridge between the two gametes. Upon fusion of nuclei and chloroplasts of $mt^+$ and $mt^-$ cells, the zygotes become zygospores. It is notable that the young zygote shows uniparental inheritance of chloroplast DNA from the $mt^+$ parent and mitochondrial DNA from the $mt^-$ parent. Under the favorable conditions, the zygospores divide meiotically and germinate and then new haploid progenies, vegetative cells, are released.

• Applied Microscopy
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• 제34권3호
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• pp.171-178
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• 2004

Metallothionein (MT) is a family of ubiquitous, low molecular weight (6-7 kDa), cysteine-rich protein with a high affinity to metal ions and has no aromatic amino acids and histidine. Some of the known functions of MT include detoxification of heavy metals and alkylating agents and neutralization of free radicals. Also, this protein may affect a number of cellular processes including gene expression, apoptosis, proliferation and differentiation. But, its actual functions are still not clear. The present study was undertaken to examine immunocytochemically the localization of MT in developing rat liver. On the day 11 of gestation, the fetal rat liver has already been formed and contained numerous oval cells with high nuclear cytoplasmic ratio, which were the progenitors of hepatic parenchymal cells, but no reaction products of MT were detected at this time. And then, positive reactions against MT started to appear predominantly in the parenchymal cells of liver from the 13th day after gestation. Reaction products, immunogold particles or brown coloration, were localized at both the nucleus and the cytoplasm of the parenchymal cells, except mitochondria. The intensity of this reaction gradually increased, and exhibited the strongest at birth. The intensity of MT staining and immunogold labelling diminished with growth, and by the 15th day after birth weak positive reaction was observed in the cells. In brief, positive reactions for MT were observed in the oval cells and the parenchymal cells during fetal stage, meanwhile they were present only in the parenchymal cells after birth. The present results suggest that MT possibly involves parechymal cell proliferation and differentiation through the storage or the supply of various metal ions in the developing rat liver.

• The Korean Journal of Nuclear Medicine
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• 제33권1호
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• pp.84-93
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• 1999

Purpose: We investigated the direct labeling method of antibody with $^{99m}Tc$ and $^{188}Re$ and examined the stability and function of these labeled compounds in in vitro and in vivo. Materials and Methods: Disulfide bond of nonspecific human IgG was reduced to -SH group by 2-mercaptoethanol. Stannous ion was used to reduce $^{99m}Tc$ and $^{188}Re$. The stability of $^{99m}Tc$-IgG and $^{188}Re$-IgG was estimated upto 24 hrs. Biodistribution was evaluated in abscess bearing rats at 4 and 24 hr post-injection of $^{99m}Tc$ or $^{188}Re$ labeled IgG. Results: The number of -SH group per reduced IgG molecule was 2.34. The labeling yield of $^{99m}Tc$-IgG and $^{188}Re$-IgG were 90% and 95%, respectively The stability of $^{99m}Tc$-IgG at 1, 4, 6 and 24 hr was 91%, 83%, 78%, 7% and that of $^{188}Re$-IgG at 1, 4, 16 and 24 hr was 94%, 80%, 47%, 42%, respectively. At 4 hr post-injection of $^{99m}Tc$-IgG, high uptake was found on kidney, blood, stomach and abscess ($9.42{\pm}0.68,\;1.43{\pm}0.24,\;0.86{\pm}0.18,\;0.72{\pm}0.10$ %ID/g, respectively). The uptakes at 24 hr were kidney, abscess,.itomach, and blood in descending order. In case of $^{188}Re$-lgG, high uptake at 4 hr post injection appeared on kidney, blood, abscess and stomach ($3.92{\pm}0.62,\;1.32{\pm}0.08,\;0.88{\pm}0.01,\;0.26{\pm}0.06$, respectively). The uptakes at 24 hr were kidney, abscess, blood and stomach in descending order. The abscess to blood uptake ratio of $^{99m}Tc$-IgG was 0.5 at 4 hr and 2.02 at 24 hr and that of $^{188}Re$-IgG was 0.67 and 1.29. Conclusion: $^{99m}Tc$-IgG and $^{188}Re$-IgG canbe labeled efficiently with direct labeling method. However, $^{99m}Tc$-IgG and $^{188}Re$-IgG, labeled with direct method, was unstable. Further study is needed to enhance the stability of the antibody labeling.