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An electroresistivity probe was used to determine point properties of an air-fluidized bed of conducting coke particles. The effects of air volume and types of distributor on the bubble freqency distributions were observed at various radial positions(R) along the axial directon (H) of the column. Interruptions of electric current between the electrodes of a probe and a large wall electrode were analyzed with the aid of Brush Recorder (Model RD-2321-00) to yield the informations about bubble frequency as functions of various positions in bed. The results were as follows; 1. The bubble distributions in the column which attached a A-type distributor (described at Fig.3) were shown steady state above the positions of H=0.3. 2. The maximum bubble frequency when a B-type distributor was used in the column was observed at the position of R=0.8 and H=0.3. 3. Bubble frequencies at the various positions in the column showed a normal distribution below the flow velocity of 14.13㎤/sec. A theoretical model to predict the bubble frequency at a given position in the bubble column was proposed.
Many therapeutic glycoproteins have been successfully generated in plants. Plants have advantages regarding practical and economic concerns, and safety of protein production over other existing systems. However, plants are not ideal expression systems for the production of biopharmaceutical proteins, due to the fact that they are incapable of the authentic human N-glycosylation process. The majority of therapeutic proteins are glycoproteins which harbor N-glycans, which are often essential for their stability, folding, and biological activity. Thus, several glyco-engineering strategies have emerged for the tailor-making of N-glycosylation in plants, including glycoprotein subcellular targeting, the inhibition of plant specific glycosyltranferases, or the addition of human specific glycosyltransferases. This article focuses on plant N-glycosylation structure, glycosylation variation in plant cell, plant expression system of glycoproteins, and impact of glycosylation on immunological function. Furthermore, plant glycoengineering techniques currently being developed to overcome the limitations of plant expression systems in the production of therapeutic glycoproteins will be discussed in this review.
Pollen germination viability is an essential factor to produce seeds from pollination and fertilization, which are required to maintain plant generation. In this study, we tried to identify the effect of boric acid on pollen germination and tube growth in non-transgenic and transgenic plants expressing monoclonal antibodies (anti-colorectal cancer mAb CO17-1A, anti-breast cancer mAb BR55, and anti-rabies virus mAb57). The pollen of non-transgenic plant was treated with different concentration of boric acid (0, 5, 10, 15, 20, 40 μg/mL) in germination buffer to investigate its effect on in vitro pollen germination. At 20 μg/mL of boric acid, the pollen germination rate was the highest (49.5%) compared to other concentrations. In general, the germination rate significantly increased 3-10 folds in boric acid (20 μg/mL) treated group in non-transgenic and transgenic plants. Also, the pollen tube length increased in boric acid (20 μg/mL) treated groups. In the treated group, the pollen tube length increased until 3 h boric acid treatment and decreased after the 3 h, indicating that the 3 h is the most appropriate incubation time period. Western blot analysis showed that the mAb transgene expression was more stable in leaf than pollen in transgenic plants. This study suggested that 20 μg/mL of boric acid is ideal concentration to induce in vitro pollen germination of transgenic plants expressing therapeutic monoclonal antibodies, indicating stable pollination and fertilization in transgenic plants.
Activation of the unfolded protein response (UPR) in mammalian cells leads to cell cycle arrest at the G1 phase (Thomas et al., J Biol Chem 288:7606–7617, 2013). However, how UPR signaling affects cell cycle arrest remains largely unknown in plants. Here, we examined UPR and endoreduplication in Col-0, wee1, and ER stress sensing-deficient ire1a&b plants during DNA replication and ER stress conditions. We found that WEE1, an essential negative regulator of the cell cycle, is involved in the maintenance of ER homeostasis during genotoxic stress and the ER stress hypersensitivity of ire1a&b is alleviated by loss-of-function mutation in WEE1. WEE1-mediated cell cycle arrest was required for IRE1–bZIP60 pathway activation during ER stress. In contrast, loss-of-function mutation in WEE1 caused increased expression of UPR-related genes during DNA replication stress. WEE1 and IRE1 were required for endoreduplication during DNA replication stress and ER stress, respectively. Taken together, these findings suggest that cell cycle regulation is associated with UPR activation in different manners during ER stress and DNA replication stress in Arabidopsis.
Gangliosides, which are glycosphingolipids containing sialic acid, play important regulatory roles in cell proliferation and adhesion, survival and immunosuppressive activity. In this study, we investigated whether gangliosides can affect cell viability in the porcine kidney (PK) cell line, PK15, when stimulated with lipopolysaccharide (LPS). As the amount of LPS that PK15 cells were treated with was increased, the cell proliferation decreased, whereas nitric oxide (NO) production increased. High-performance thin-layer chromatography (HPTLC) and immunofluorescence analyses showed that GM3 and GM2 ganglioside expression significantly decreased in LPS-stimulated PK15 compared to unstimulated PK15. UDP-glucose ceramide glucosyltransferase (Ugcg), which catalyzes the initial step in the glycosphingolipid biosynthesis pathway, was knocked-down in PK15 by using short hairpin RNA (shRNA). Western blot and HPTLC analyses showed that the Ugcg protein expression decreased and the ganglioside expression decreased in the Ugcg-knockdown (UKD) PK15. There was a greater decrease in cell proliferation in LPS-stimulated UKD PK15 cells than in LPS-stimulated PK15 cells without the UKD. However, the increase in NO release was greater in LPS-stimulated UKD PK15 cells than in LPS-stimulated PK15 cells without the UKD. These findings suggest that gangliosides may interact with components of the inflammatory response pathway and, thus, are relevant for the design of future therapeutic strategies intended to prolong xenotransplantation.
This study aimed to clarify the role of zinc in human prostate epithelial cell defense against bacterial infection. To explore the effect of zinc on lipopolysaccharide (LPS)-mediated induction of human β- defensin-2 (HBD-2), the normal human prostate epithelial cell lines (RWPE-1) were co-treated with zinc/LPS and HBD-2 mRNA expression was quantitated by the reverse transcription polymerase chain reaction (RT-PCR). We also conducted a Western blot analysis to determine whether zinc stimulates p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase-1 and -2 (ERK1/2) signaling pathways. To investigate the involvement of the p38MAPK and ERK1/2 signaling pathways in zinc-mediated upregulation of HBD-2, quantitative real-time PCR and immunocytochemical staining were then used to quantify HBD-2 mRNA expression and protein production, respectively, which was treated with either U0126 (ERK1/2 inhibitor) or SB203580 (p38MAPK inhibitor) prior to each analysis of HBD-2. Cotreatment of RWPE-1 cells with zinc/LPS-upregulated HBD-2 expression to an even greater extent than either LPS alone or zinc alone. Moreover, the treatment of RWPE-1 cells with zinc significantly increased both the total and phosphorylated forms of ERK1/2 and p38MAPK. ERK1/2 and p38MAPK signaling via the inhibitors U0126 and SB203580 pharmacologically inhibited zinc-mediated upregulation of HBD- 2. These results strongly suggest that zinc plays an important role in the immune response of the prostate. Furthermore, we demonstrate that zinc-mediated upregulation of HBD-2 expression upon bacterial infection of prostate epithelial cells involves the ERK1/2 and p38MAPK signaling pathways.