The Effect of Ginseng Saponin on Amphetamine Action of Q02 and Na+, K+ Content in Cerebral Cortex Slices of Rat

The effect of Ginseng saponin on respiration, Na" and K+ content of rat cerebral cortex slice was investigated to determine the action of Ginseng saponin on brain cortex at cellular level. There are number of reports on the study of Ginseng concerning central stimulatory or inhibitory action of it's saponin in experimental animals. The following results were obtained in this study concerning the action of Ginseng saponin on the respiration and Na", K+ concentration in the brain cortex slices of the rat. It was observed that the respiration of rat brain slices following Ginseng saponin administration was decreased. QO. also reduced by amphetamine alone but Ginseng saponin stimulated respiration significantly which was depressed by previous amphetamine administration. Non-inulin Na tand K+ contents were reduced by Ginseng saponin together with amphetamine. There was increase in non-inulin Na" concentration by Ginseng saponin but no definite changes were observed in K+ concentration on same subject. It is suggested that the Ginseng saponin acts rather on metabolic process than neural excitatory mechanism in vitro. The possible effects of amphetamine and Ginseng saponin on the tissue respiration, electrolyte and QO. of rat brain slices were discussed

대장균 RNase P의 촉매 소단위체를 코드하는 rnpB 유전자의 전사과정에서 긴축 조절 작용

학위논문(박사) - 한국과학기술원 : 화학과, 1997.2, [ ix, 100 p. ]Escherichia coli RNase P, which catalyzed the processing of the 5``-termini of immature tRNAs, is composed of an RNA subunit (M1 RNA) and a protein subunit (C5 protein). The promoter region of the rnpB gene, which codes for M1 RNA, contains three promoter elements P-1, P-2, and P-3 in increasing distance from 5``-end of M1 RNA. In vivo and in vitro studies have shown that P-1 is the major site of transcription initiation of the rnpB gene. The P-1 promoter shares a consensus sequence with other promoters that can confer transcription repression upon the stringent response. The consensus sequence is located within the region (the discriminator region) between the -10 hexamer sequence and the transcription start site. The stringent response of the rnpB promoters was analyzed by directly observing metabolically unstable transcripts derived from the internally deleted rnpB gene harbored on a multicopy plasmid. Synthesis of the truncated transcripts was inhibited upon stringent condition induced by seryl-tRNA starvation, indicating that transcription of the rnpB gene is under negative stringent control. The inhibition of transcription was relA-dependent, which suggests that ppGpp is involved in the negative stringent response of rnpB transcription. Site-directed mutagenesis was carried out to examine the requirement of the rnpB promoter sequence for the stringent control. Mutant promoters were prepared by GC to AT substitutions at the discriminator region. The stringent response of the mutant promoters was examined both by analyzing synthesis of the truncated M1 RNA transcript upon seryl-tRNA starvation in vivo and by analyzing effects of ppGpp on in vitro transcription. The results showed that the discriminator region was responsible for the stringent control of the rnpB gene and the mutation of bases at different positions in the discriminator region differently affected the stringent response. Especially GC-rich sequences proximal to the transcription start site w...한국과학기술원 : 화학과

온도 감수성 rnpA 돌연변이 대장균에서 플라스미드 RNA 대사의 변화

학위논문(석사) - 한국과학기술원 : 화학과, 1992.2, [ iv, 41 p. ]Escherichia coli RNase P is a processing enzyme which cleaves tRNA precursors at the 5``-end of the tRNA sequence. It is composed of protein component, C5 protein, and RNA component, M1 RNA. M1 RNA synthesized from a ColEl-related plasmid, which harbors the rnpB gene encoding M1 RNA, was accumulated in E. coli strain A49 carrying the thermosensitive mutation in the rnp A gene encoding C5 protein at nonpermissive temperature. This accumulation of M1 RNA accompanied the accumulation of two small RNAs in the A49 cells. They were designated as RNA X and RNA Y in diminishing size. Their nucleotide sequences were determined by the enzymatic method. Analysis of the RNA sequences showed that RNA X and RNA Y are composed of 96 and 67 nucleotides, respectively and related with RNA I, which is the negative controller of ColE1 plasmid replication. Surprisingly RNA X has the same sequences of RNA Y but differs in containing an extra 29 nucleotides at the 5`` end. These results indicate that RNA X and RNA Y are originated from the ColE1-related plasmid, and suggest that a defect in RNase P function by the rnpA49 mutation is responsible for accumulation of these RNAs, implying the possible involvement of RNase P in controlling the replication of ColE1-type plasmids.한국과학기술원 : 화학과