• Animal cells and systems
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• v.4 no.2
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• pp.141-144
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• 2000

Effects of deamido-$\textrm{NAD}^{+}$on self-splicing of primary transcripts of the phage T4 thymidylate synthase gene (td) was investigated. The self-splicing was not affected by deamido-$\textrm{NAD}^{+}$- at concentrations up to 2 mM. However, it began to decrease at 5 mM and the formation of splicing products such as the linear intron, intron-exon 2 and exon 1-exon 2, was slightly reduced. At 20 mM the self-splicing activity was almost completely abolished. This analog of the coenzyme $\textrm{NAD}^{+}$- inhibits the self-splicing of td intron RNA although it does not possess a guanidine group in its structure. The analysis of inhibitory concentrations and structural examination suggests that the key structural features of deamido-$\textrm{NAD}^{+}$ responsible for the inhibition of splicing may be the ADP-ribose moiety.

• Korean Journal of Microbiology
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• v.35 no.4
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• pp.253-257
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• 1999

Effects of polyamines such as cadaverine, putrescine, spermidine and spermine on the self-splicig inhibition of the T4 phage thymidylate synthase(td) intron by spectinomycin have been investrigated. Without polyamine 7mM spectinomycin caused 40% reduction of the splicing rate. Cadaverine reduced the splicing rate over the concentrations of 0.1 to 5 mM. Putrescine at 0.5 mM increased the splicing rate by 13%. Spermidine at 0.5 mM enhanced the splicing rate by 11% while spermine at 0.01 mM enhanced the splicing rate by 16%. Of the all polyamines tested, spermine exhibited the maximum activation effect to counteract the splicing inhibition by spectinomycin. This effect appears to be due to the role of polyamine in stabilizing the conformation of td intron ribozyme essential for the catalytic function.

• Journal of Microbiology
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• v.40 no.2
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• pp.134-139
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• 2002

Effects of GTP on the inhibition of self-splicing of primary transcripts of the phage T4 thymidylate synthase gene (td) by thiamine pyrophosphate and its analogs have been investigated. The order of the inhibitory efficiency for compounds tested was as follows: thiamine pyrophosphate > thiamine monophosphate > thiamine. of all compounds examined, thiamine pyrophosphate was the most potent inhibitor, Increasing GTP concentration in splicing reaction tended to overcome the suppressive effects of self-splicing by thiamine pyrophosphate and its analogs. The inhibition by thiamine pyrophosphate was most sensitized to a higher concentration of GTP, It has been speculated that the key structural features in thiamine pyrophosphate and its analogs responsible for the inhibition of splicing may be a thiamine moiety in which the phosphorylation of 2-hydroxylethyl group on 5-position of thiazolium ring rendered further stimulation of inhibition in self-splicing reaction..

• Journal of Microbiology
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• v.37 no.4
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• pp.243-247
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• 1999

Effects of divalent cations on self-splicing inhibition by the antibiotic spectinomycin of the phage T4 thymidylate synthase intron (td) have been investigated. $Ca^{2+}$ ion at 1mM concentration suppressed splicing inhibition of spectinomycin by 10% and 50 ${\mu}M\;Co^{2+}$ ion also suppressed splicing inhibition of specinomycin by 10%. $Mg^{2+}$ ion at 6 mM concentration decreased splicing inhibition of spectinomycin by 42% while $Mn^{2+}$ ion decreased the splicing inhibition by 10%. $Zn^{2+}$ ion at 10 uM concentration lowered the splicing inhibition by spectinomycin of 15%. Of all divalent cations tested, $Mg^{2+}$ ion was the most effective in suppressing splicing inhibition by specinomycin whereas $Ca^{2+}$ ion was the least effective. The results suggest that spectinomycin may interact with specific and functional $Mg^{2+}$-binding sites within intron RNA that lead to a displacement of $Mg^{2+}$ essential for catalytic activity.

• Korean Journal of Microbiology
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• v.38 no.1
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• pp.13-18
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• 2002

Effects of divalent cations such as $Mg^{2+}$, $Mn^{2+}$ and $Zn^{2+}$ on the self-splicing inhibition of the T4 phage thymidylate synthase (td) intron by the coenzyme thiamine pyrophosphate have been investigated. The splicing activity increased in proportion to the concentration of $Mg^{2+}$ up to 30 mM. Without $Mg^{2+}$in the splicing reaction the $Zn^{2+}$ ion tested in the range of 0.1-6 mM concentration only produced the splicing activity about 20% that of the normal splicing rate. A majority of the splicing products were I-E2 and E2 but El-E2 ligation product, Cl and Ll were not detected. Similar patterns of splicing products were also observed with $Mn^{2+}$. At 6 mM $Zn^{2+}$the intron RNA was hydrolyzed. $Mn^{2+}$produced a little higher splicing activity than that of $Zn^{2+}$over the range of concentrations used and at 8 mM about 28% splicing activity was observed. In contrast, $Mn^{2+}\;and\;Zn^{2+}$ ions promoted the splicing activity about 35-40% on an average in the presence of 10 mM $Mg^{2+}$. Of all divalent cations tested, $Mg^{2+}$exhibited the maximum activation effect to counteract the splicing inhibition by thiamine pyrophosphate. This appears to be due to the stabilizing effect of td intron ribozyme structure essential for the catalytic function by $Mg^{2+}$.

• Genomics & Informatics
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• v.2 no.1
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• pp.45-52
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• 2004

The self-splicing group I intron from Tetrahymena thermophila has been demonstrated to perform splicing reaction with its substrate RNA in the trans configuration. In this study, we explored the potential use of the trans-splicing group I ribozymes to replace a specific RNA with a new RNA that exerts any new function we want to introduce. We have chosen thymidine phosphorylase (TP) RNA as a target RNA that is known as a valid cancer prognostic factor. Cancer-specific expression of TP RNA was first evaluated with RT-PCR analysis of RNA from patients with gastric cancer. We determined next which regions of the TP RNA are accessible to ribozymes by employing an RNA mapping strategy, and found that the leader sequences upstream of the AUG start codon appeared to be particularly accessible. A specific ribozyme recognizing the most accessible sequence in the TP RNA with firefly luciferase transcript as a 3' exon was then developed. The specific trans-splicing ribozyme transferred an intended 3' exon tag sequence onto the targeted TP transcripts, resulting in a more than two fold induction of the reporter activity in the presence of TP RNA in mammalian cells, compared to the absence of the target RNA. These results suggest that the Tetrahymena ribozyme can be a potent anti-cancer agent to modify TP RNAs in tumors with a new RNA harboring anti-cancer activity.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.140-147
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• 2002

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.680-685
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• 1998

Prestressed concrete I-girders were used in the bridge applications in the early 1950s. During the last four decades, the most widely used girder length of bridges have been below 30meters. The main objective of this study is to develope the alternative section for long span bridge which exceed 40 meters. The developed Bulb-Tee girder has a wide bottom flange to enhance the compressive strength and to allow placement of a large number of strands in the bottom flange. New bulb-tee shaped PSC girder sections are proposed in this paper. Splicing the technique for long span bridge girder to reduce the self weight is also proposed.

• Structural Engineering and Mechanics
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• v.17 no.6
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• pp.879-898
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• 2004

A method of making simply supported girders continuous is described for bridges with spans of 30-45 m. The splicing method takes advantage of an induced secondary moment to transform the self-weight stresses in the precast simply supported girders into values representative of a continuous girder. The secondary moment results from prestressing of continuity tendons and detensioning of temporary tendons in the girders. Preliminary sections are selected for spliced U-girder bridges with a range of span lengths. Use of the proposed technique results in girder depth reductions of 500-800 mm when compared to standard simply supported I-girder bridges. The flexural behavior of an example bridge with 40-m spans is examined to illustrate the necessary considerations for determining the optimum sequence of splicing operations.

• Computers and Concrete
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• v.32 no.3
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• pp.339-349
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• 2023

Fast-built construction is a key feature for successful applications of precast concrete (PC) moment frame system in recent construction practices. To this end, by introducing some unique splicing details in precast connections, especially between PC columns including panel zones, use of temporary supports and bracings can be minimized based on their self-sustaining nature. In addition, precast wide beams are commonly adopted for better economic feasibility. In this study, three self-sustaining precast concrete (PC) wide beam-column connection specimens were fabricated and tested under reversed cyclic loadings, and their seismic performances were quantitatively evaluated in terms of strength, ductility, failure modes, energy dissipation and stiffness degradation. Test results were compared with ASCE 41-17 nonlinear modeling curves and its corresponding acceptance criteria. On this basis, an improved macro modeling method was explored for a more accurate simulation. It appeared that all the test specimens fully satisfy the acceptance criteria, but the implicit joint model recommended in ASCE 41-17 tends to underestimate the joint shear stiffness of PC wide beam-column connection. While, the explicit joint model along with concentrated plastic hinge modeling technique is able to present better accuracy in simulating the cyclic responses of PC wide beam-column connections.