Browsing by Author "Lin, Ching-Ting"

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A Wavelet-based Watermarking Scheme Using Double Wavelet Tree Energy Modulation
(2008)
Tsai, Min-Jen
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Lin, Ching-Ting
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Liu, Jung
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
Wavelet tree based watermarking algorithms are generally using the energy difference among grouped wavelet coefficients for invisible watermark embedding and extraction. According to the cryptanalysis of wavelet tree quantization (WTQ) scheme, its robustness has been proven weak and modified wavelet tree quantization (MWTQ) is developed consequently. However, MWTQ needs the wavelet tree group data as the extra information and MWTQ is not blind for watermark extraction. Therefore, a novel wavelet tree watermarking using double wavelet tree energy modulation is proposed in this study. This study has performed intensive comparison for the proposed scheme with WTQ, WTGM and MWTQ under various signal processing attacks. The experiment results demonstrate that the proposed technique yields better performance with higher degree of robustness than WTQ.
Comparative analysis of two UDP-glucose dehydrogenases in Pseudomonas aeruginosa PAO1
(2007-06-15)
Hung, Ruei-Jiun
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Chien, Han-Sheng
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Lin, Ruei-Zeng
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Lin, Ching-Ting
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Vatsyayan, Jaya
UDP-glucose dehydrogenase (UGDH) catalyzes a two-step NAD(+)-dependent oxidation of UDP-glucose to produce UDPglucuronic acid, which is a common substrate for the biosynthesis of exopolysaccharide. Searching the Pseudomonas aeruginosa PAO1 genome data base for a UGDH has helped identify two open reading frames, PA2022 and PA3559, which may encode a UGDH. To elucidate their enzymatic identity, the two genes were cloned and overexpressed in Escherichia coli, and the recombinant proteins were purified. Both the gene products are active as dimers and are capable of utilizing UDP- glucose as a substrate to generate UDP- glucuronic acid. The Km values of PA2022 and PA3559 for UDP-glucose are similar to 0.1 and 0.4 mM, whereas the K-m values for NAD(+) are 0.5 and 2.0 mM, respectively. Compared with PA3559, PA2022 exhibits broader substrate specificity, utilizing TDP-glucose and UDP-N-acetylglucosamine with one-third the velocity of that with UDP- glucose. The PA2022 mutant and PA2022-PA3559 double mutant, but not the PA3559 mutant, are more susceptible to chloramphenicol, cefotaxime, and ampicillin. The PA3559 mutant, however, shows a reduced resistance to polymyxin B compared with wild type PAO1. Finally, real time PCR analysis indicates that PA3559 is expressed primarily in low concentrations of Mg2+, which contrasts with the constitutive expression of PA2022. Although both the enzymes catalyze the same reaction, their enzymatic properties and gene expression profiles indicate that they play distinct physiological roles in P. aeruginosa, as reflected by different phenotypes displayed by the mutants.
CRP-Cyclic AMP Regulates the Expression of Type 3 Fimbriae via Cyclic di-GMP in Klebsiella pneumoniae
(2016-09-15)
Lin, Ching-Ting
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Lin, Tien-Huang
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Wu, Chien-Chen
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Wan, Lei
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Huang, Chun-Fa
Klebsiella pneumoniae is the predominant pathogen isolated from liver abscesses of diabetic patients in Asian countries. However, the effects of elevated blood glucose levels on the virulence of this pathogen remain largely unknown. Type 3 fimbriae, encoded by the mrkABCDF genes, are important virulence factors in K. pneumoniae pathogenesis. In this study, the effects of exogenous glucose and the intracellular cyclic AMP (cAMP) signaling pathway on type 3 fimbriae expression regulation were investigated. The production of MrkA, the major subunit of type 3 fimbriae, was increased in glucose-rich medium, whereas cAMP supplementation reversed the effect. MrkA production was markedly increased by cyaA or crp deletion, but slightly decreased by cpdA deletion. In addition, the mRNA levels of mrkABCDF genes and the activity of P-mrkA were increased in Delta crp strain, as well as the mRNA levels of mrkHIJ genes that encode cyclic di-GMP (c-di-GMP)-related regulatory proteins that influence type 3 fimbriae expression. Moreover, the activities of P-mrkHI and P-mrkJ were decreased in Delta lacZ Delta crp strain. These results indicate that CRP-cAMP down-regulates mrkABCDF and mrkHIJ at the transcriptional level. Further deletion of mrkH or mrkI in Delta crp strain diminished the production of MrkA, indicating that MrkH and MrkI are required for the CRP regulation of type 3 fimbriae expression. Furthermore, the high activity of P-mrkHI in the Delta lacZ Delta crp strain was diminished in Delta lacZ Delta crp Delta mrkHI, but increased in the Delta lacZ Delta crp Delta mrkJ strain. Deletion of crp increased the intracellular c-di-GMP concentration and reduced the phosphodiesterase activity. Moreover, we found that the mRNA levels of multiple genes related to c-di-GMP metabolism were altered in Delta crp strain. These indicate that CRP regulates type 3 fimbriae expression indirectly via the c-di-GMP signaling pathway. In conclusion, we found evidence of a coordinated regulation of type 3 fimbriae expression by the CRP-cAMP and c-di-GMP signaling pathways in K. pneumoniae.
Fur regulation of the capsular polysaccharide biosynthesis and iron-acquisition systems in Klebsiella pneumoniae CG43
(2011-02-01)
Lin, Ching-Ting
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Wu, Chien-Chen
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Chen, Yu-Sheng
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Lai, Yi-Chyi
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Chi, Chia
The ferric uptake regulator Fur has been reported to repress the expression of rmpA, a regulatory gene for the mucoid phenotype, leading to decreased capsular polysaccharide (CPS) biosynthesis in Klebsiella pneumoniae CG43. Here, quantitative real-time FOR (qRT-PCR) analyses and electrophoretic mobility shift assays showed that Fur also repressed the expression of the CPS regulatory genes rmpA2 and rcsA. Interestingly, deletion of rmpA or rcsA but not rmpA2 from the Delta fur strain was able to suppress the deletion effect of Fur. The availability of extracellular iron affected the amount of CPS, suggesting that Fur regulates CPS biosynthesis in an Fe(II)-dependent manner. Increased production of siderophores was observed in the Delta fur strain, suggesting that uptake of extracellular iron in K. pneumoniae is regulated by Fur. Fur titration assays and qRT-PCR analyses demonstrated that at least six of the eight putative iron-acquisition systems, identified by a BLAST search in the contig database of K. pneumoniae CG43, were directly repressed by Fur. We conclude that Fur has a dual role in the regulation of CPS biosynthesis and iron acquisition in K. pneumoniae.
Fur-dependent MrkHI regulation of type 3 fimbriae in Klebsiella pneumoniae CG43
(2012-04-01)
Wu, Chien-Chen
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Lin, Ching-Ting
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Cheng, Wei-Yun
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Huang, Ching-Jou
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Wang, Zhe-Chong
Type 3 fimbriae play a crucial role in Klebsiella pneumoniae biofilm formation, but the mechanism of the regulation of the type 3 fimbrial operon is largely unknown. In K. pneumoniae CG43, three regulatory genes, mrkH, mrkI and mrkJ, are located downstream of the type 3 fimbrial genes mrkABCDF. The production of the major pilin MrkA is abolished by the deletion of mrkH or mrkI but slightly increased by the deletion of mrkJ. Additionally, quantitative RT-PCR and a promoter reporter assay of mrkHI verified that the transcription of mrkHI was activated by MrkI, suggesting autoactivation of mrkHI transcription. In addition, sequence analysis of the mrkH promoter region revealed a putative ferric uptake regulator (Fur) box. Deletion of fur decreased the transcription of mrkH, mrkI and mrkA. The expression of type 3 fimbriae and bacterial biofilm formation were also reduced by the deletion of fur. Moreover, a recombinant Fur was found to be able to bind both promoters, with higher affinity for P-mrkH than P-mrkA, implying that Fur controls type 3 fimbriae expression via MrkHI. We also proved that iron availability can influence type 3 fimbriae activity.
Grain Size and Plasma Doping Effects on CVD-based 2D Transition Metal Dichalcogenide
(2016)
Lin, Chih-Pin
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Lin, Ching-Ting
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Liu, Pang-Shivan
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Yu, Ming-Hue
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Hou, Tuo-Hung
Transition metal dichalcogenide (TMD)-based field effect transistors are currently being actively researched as a post-silicon solution for integrated circuits. This paper discusses two of the major challenges: grain size in polycrystalline TMD monolayer films and chemical doping to improve TMD/metal contacts. The characterization techniques and the correlation with device electrical characteristics are investigated.
Grain Size Effect of Monolayer MoS2 Transistors Characterized by Second Harmonic Generation Mapping
(2015)
Lin, Chih-Pin
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Lyu, Li-Syuan
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Lin, Ching-Ting
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Liu, Pang-Shiuan
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Chang, Wen-Hao
We investigated different CVD-synthesized MoS2 films, aiming to correlate the device characteristics with the grain size. The grain size of MoS2 can be precisely characterized through nondestructive second harmonic generation mapping based on the degree of inversion symmetry. The devices with larger grains at the channel region show improved on/off current ratio, which can be explained by the less carrier scattering caused by the grain boundaries.
Homologous response regulators KvgA, KvbA and KvhR regulate the synthesis of capsular polysaccharide in Klebsiella pneumoniae CG43 in a coordinated manner
(2006-09-01)
Lin, Ching-Ting
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Huang, Teng-Yi
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Liang, Wan-Chun
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Peng, Hwei-Ling
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生物科技學系
On the basis of phenotypic analysis, the Klebsiella pneumoniae CG43 derived mutants with deletions of the gene encoding respectively the response regulators KvgA, KvhA, and KvhR were classified into two groups. Group I bacteria carrying either kvgA(-) or kvhR(-) exhibited less mucoidy, lower level of capsular polysaccharide (CPS) synthesis and higher LD50 than the parental strain. No apparent change of the group II, including kvhA(-) and hvhA(-)kvhR(-) mutants, was observed. However, the mucoidy of kvhA(-)kvhR(-) mutant was found to be diminished after introducing into a kvhA(-) expressing plasmid. Via promoter-lacZ fusion analysis, kvhA deletion was found to reduce kvhR expression. A regulatory role of KvhA for the expression of kvhR was supported further by EMSA showing a specific binding of KvhA to the putative promoter of kvhR. The promoter activity measurement and EMSA also revealed that KvgA acted as an autoregulator and an activator for the expression of kvhAS and kvhR. In addition, deletion of kvgA suppressed slightly the promoter activity of the cps-orf16-17, and the expression of all three cps transcripts orf1-2, orf3-15, and orf16-17 were reduced in the kvhR(-) mutant. These suggest that the three homologous response regulators interact to control, in coordination, the bacterial cps expression.
Internal current amplification induced by dielectric hole trapping in monolayer MoS2 transistor
(2017-11-24)
Liu, Pang-Shiuan
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Lin, Ching-Ting
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Hudec, Boris
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Hou, Tuo-Hung
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電子工程學系及電子研究所
Carrier transport in layered transition-metal dichalcogenides is highly sensitive to surrounding charges because of the atomically thin thickness. By exploiting this property, we report a new internal current amplification mechanism through positive feedback induced by dielectric hole trapping in a MoS2 back-gate transistor on a tantalum oxide substrate. The device exhibits an extremely steep subthreshold slope of 17 mV/decade, which is strongly dependent on the substrate material and drain bias. The steep subthreshold slope is attributed to the internal current amplification arising from the positive feedback between hole generation in MoS2 triggered by large lateral electric field and Schottky barrier narrowing induced by localized hole trapping in tantalum oxide near the source contact.
RcsB regulation of the YfdX-mediated acid stress response in Klebsiella pneumoniae CG43S3
(2019-02-28)
Liu, Chia-Jui
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Lin, Ching-Ting
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Chiang, Jo-Di
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Lin, Chen-Yi
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Tay, Yen-Xi
In Klebsiella pneumoniae CG43S3, deletion of the response regulator gene rcsB reduced the capsular polysaccharide amount and survival on exposure to acid stress. A comparison of the pH 4.4-induced proteomes between CG43S3 and CG43S3.rcsB revealed numerous differentially expressed proteins and one of them, YfdX, which has recently been reported as a periplasmic protein, was absent in CG43S3.rcsB. Acid survival analysis was then conducted to determine its role in the acid stress response. Deletion of yfdX increased the sensitivity of K. pneumoniae CG43S3 to a pH of 2.5, and transforming the mutant with a plasmid carrying yfdX restored the acid resistance (AR) levels. In addition, the effect of yfdX deletion was cross-complemented by the expression of the periplasmic chaperone HdeA. Furthermore, the purified recombinant protein YfdX reduced the acid-induced protein aggregation, suggesting that YfdX as well as HdeA functions as a chaperone. The following promoter activity measurement revealed that rcsB deletion reduced the expression of yfdX after the bacteria were subjected to pH 4.4 adaptation. Western blot analysis also revealed that YfdX production was inhibited by rcsB deletion and only the plasmid expressing RcsB or the nonphosphorylated form of RcsB, RcsBD56A, could restore the YfdX production, and the RcsB-mediated complementation was no longer observed when the sensor kinase RcsD gene was deleted. In conclusion, this is the first study demonstrating that YfdX may be involved in the acid stress response as a periplasmic chaperone and that RcsB positively regulates the acid stress response partly through activation of yfdX expression. Moreover, the phosphorylation status of RcsB may affect the YfdX expression under acidic conditions.
Regulation of the homologous two-component systems KvgAS and KvhAS in Klebsiella pneumoniae CG43
(2006-11-01)
Lin, Ching-Ting
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Peng, Hwei-Ling
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生物科技學系
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Department of Biological Science and Technology
In Klebsiella pneumoniae CG43, deletion of the sensor gene kvgS reduced the kvgAS expression in M9 medium with 0.2 mM paraquat, 0.2 mM 2,2-dihydropyridyl, or 300 mM NaCl. This result shows an autoregulatory role of KvgS and a stress-responsive expression of the two-component system (2CS). The kvgS deletion also appeared to decrease the expression of kvhAS, paralogous genes of kvgAS. Additionally, measurements of the promoter activity in kvgA(-) mutant revealed that KvgA is probably an activator for the expression of kvgAS and kvhAS. The subsequent electrophoretic mobility shift assay, indicating a specific binding of the recombinant KvgA to the putative promoters P-kvgAS and P-kvhAs, also supported an interacting regulation between the 2CSs. In P-kvgAs and P-kvhAS, the presence of RpoS binding elements suggested an RpoS-dependent regulation. Nevertheless, the rpoS deletion reduced the expression of kvgAS but increased that of kvhAS. Moreover, the kvgA deletion reduced the expression of katG and sodC. The overexpression of KvhA altered the susceptibility to fosfomycin and an increasing activity of UDP-N-acetylglucosamine enolpyruvyl transferase, the target protein of fosfomycin, which suggesting a regulation by KvhA. Taken together, these indicated that the two 2CSs probably belong to different regulatory circuits of the RpoS regulon.
Role of the cAMP-Dependent Carbon Catabolite Repression in Capsular Polysaccharide Biosynthesis in Klebsiella pneumoniae
(2013-02-11)
Lin, Ching-Ting
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Chen, Yu-Ching
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Jinn, Tzyy-Rong
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Wu, Chien-Chen
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Hong, Yi-Ming
K. pneumoniae is the predominant pathogen isolated from liver abscesses of diabetic patients in Asian countries. Although elevated blood glucose levels cause various immune problems, its effects on K. pneumoniae virulence are unknown. This study investigated the regulation of capsular polysaccharide (CPS) biosynthesis, a major determinant for K. pneumoniae virulence, in response to exogenous glucose. We found that K. pneumoniae produce more CPS in glucose-rich medium via reduction in cyclic AMP (cAMP) levels. Individual deletion of cyaA or crp, which respectively encode adenylate cyclase and cAMP receptor protein in K. pneumoniae, markedly increased CPS production, while deletion of cpdA, which encodes cAMP phosphodiesterase, decreased CPS production. These results indicate that K. pneumoniae CPS biosynthesis is controlled by the cAMP-dependent carbon catabolite repression (CCR). To investigate the underlying mechanism, quantitative real-time PCR and promoter-reporter assays were used to verify that the transcription of CPS biosynthesis genes, which are organized into 3 transcription units (orf1-2, orf3-15, and orf16-17), were activated by the deletion of crp. Sequence analysis revealed putative CRP binding sites located on Porf3-15 and Porf16-17, suggesting direct CRP-cAMP regulation on the promoters. These results were then confirmed by electrophoretic mobility shift assay. In addition, we found putative CRP binding sites located in the promoter region of rcsA, which encodes a cps transcriptional activator, demonstrating a direct repression of CRP-cAMP and P-rcsA. The deletion of rcsA in mutation of crp partially reduced CPS biosynthesis and the transcription of orf1-2 but not of orf3-15 or orf16-17. These results suggest that RcsA participates in the CRP-cAMP regulation of orf1-2 transcription and influences CPS biosynthesis. Finally, the effect of glucose and CCR proteins on CPS biosynthesis also reflects bacterial resistance to serum killing. We here provide evidence that K. pneumoniae increases CPS biosynthesis for successful infection in response to exogenous glucose via cAMP-dependent CCR.
Role of the small RNA RyhB in the Fur regulon in mediating the capsular polysaccharide biosynthesis and iron acquisition systems in Klebsiella pneumoniae
(1970-01-01)
Huang, Su-Hua
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Wang, Chien-Kuo
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Peng, Hwei-Ling
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Wu, Chien-Chen
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Chen, Ying-Tsong
"Background: The capsular polysaccharide (CPS) and iron acquisition systems are important determinants of Klebsiella pneumoniae infections, and we have previously reported that the ferric uptake repressor (Fur) can play dual role in iron acquisition and CPS biosynthesis. In many bacteria, Fur negatively controls the transcription of the small non-coding RNA RyhB to modulate cellular functions and virulence. However, in K. pneumoniae, the role played by RyhB in the Fur regulon has not been characterised. This study investigated Fur regulation of ryhB transcription and the functional role of RyhB in K. pneumoniae. Results: Deletion of fur from K. pneumoniae increased the transcription of ryhB; the electric mobility shift assay and the Fur-titration assay revealed that Fur could bind to the promoter region of ryhB, suggesting that Fur directly represses ryhB transcription. Additionally, in a Delta fur strain with elevated CPS production, deletion of ryhB obviously reduced CPS production. The following promoter-reporter assay and quantitative real-time PCR of cps genes verified that RyhB activated orf1 and orf16 transcription to elevate CPS production. However, deletion of ryhB did not affect the mRNA levels of rcsA, rmpA, or rmpA2. These results imply that Fur represses the transcription of ryhB to mediate the biosynthesis of CPS, which is independent of RcsA, RmpA, and RmpA2. In addition, the Delta fur strain's high level of serum resistance was attenuated by the deletion of ryhB, indicating that RyhB plays a positive role in protecting the bacterium from serum killing. Finally, deletion of ryhB in Delta fur reduced the expression of several genes corresponding to 3 iron acquisition systems in K. pneumoniae, and resulted in reduced siderophore production. Conclusions: The regulation and functional role of RyhB in K. pneumoniae is characterized in this study. RyhB participates in Fur regulon to modulate the bacterial CPS biosynthesis and iron acquisition systems in K. pneumoniae."