Construction and application of an expression vector from the new plasmid pLAtc1 of Acidithiobacillus caldus.

In this study, a recently sequenced 9.8-kb plasmid, pLAtc1, from Acidithiobacillus caldus strain SM-1 was characterized and developed into an expression vector. The pLAtc1 backbone carried an oriV, three rep genes, five mob genes, a Nic site, and an addiction system. Multilocus sequence analysis indicated that pLAtc1 was phylogenetically more related to the IncQ-like broad host range plasmids than to other IncQ plasmids. pLAtc1 was able to replicate and reside in Gram-negative Escherichia coli, Comamonas testosteroni, but not in Gram-positive Corynebacterium glutamicum. pLAtc1 was mobilized via conjugation into E. coli BL21 and A. caldus SM-1 from E. coli S17-1. Quantitative PCR revealed seven and four copies of plasmid in A. caldus and E. coli cells, respectively. The expression vector pLAtcE was constructed from pLAtc1 by introducing a regulatable promoter (P tetH ), a transcriptional terminator, a multiple cloning site, a kanamycin resistance gene, and a streptomycin resistance gene. The functionality of pLAtcE was demonstrated by expressing a gene encoding enhanced green fluorescence protein in E. coli and in A. caldus. pLAtcE was used to express α-ketoglutarate dehydrogenase (sucAB) and succinate dehydrogenase (sdhA) genes in A. caldus. The newly engineered strain that harbored sucAB and sdhA on a plasmid pLAtcE-sucA-sucB-sdhA grew better than the parent strain SM-1/pLAtcE in tetrathionate and glucose-supplemented medium and produced more acidity and resulted in a more oxidative environment. This study created a useful molecular tool for genetic manipulation of the thermoacidophilic and autotrophic A. caldus.

Parapedobacter pyrenivorans sp. nov., isolated from a pyrene-degrading microbial enrichment, and emended description of the genus Parapedobacter.

A novel pyrene-degrading, Gram-negative bacterium, designated strain P-4(T), was isolated from a polycyclic aromatic hydrocarbon-degrading enrichment of polluted soils from a coking chemical plant. Cells of strain P-4(T) were non-motile rods. Strain P-4(T) grew at 15-45 °C (optimum, 37 °C), pH 6.0-10.0 (optimum, pH 8.5) and 0-4 % (w/v) NaCl. Analysis of the 16S rRNA gene sequence showed that strain P-4(T) was related phylogenetically to members of the genus Parapedobacter, with sequence similarity of 93.7-95.1 %. The cellular fatty acids of strain P-4(T) were iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C17 : 0 3-OH, summed feature 9 (iso-C17 : 1ω9c and/or 10-methyl C16 : 0), anteiso-C15 : 0, iso-C15 : 0 3-OH, C16 : 0, iso-C15 : 1 G, C16 : 0 3-OH and C17 : 0 2-OH. Cells contained menaquinone 7 as the major quinone. The polyamine of strain P-4(T) was homospermidine, and the main polar lipids were phosphatidylethanolamine and a sphingolipid. The G+C content of the DNA was 45.4 mol%. Strain P-4(T) showed a range of phenotypic characteristics that differentiated it from previously recognized Parapedobacter species, particularly its ability to use pyrene as a sole carbon source for growth and its alkaline optimal pH for growth (pH 8.5). On the basis of these results, it is concluded that strain P-4(T) represents a novel species of the genus Parapedobacter, for which the name Parapedobacter pyrenivorans (type strain P-4(T) = NBRC 109113(T) = CGMCC 1.12195(T)) is proposed. An emended description of the genus Parapedobacter is also provided.

Direct generation of all-optical random numbers from optical pulse amplitude chaos.

We propose and theoretically demonstrate an all-optical method for directly generating all-optical random numbers from pulse amplitude chaos produced by a mode-locked fiber ring laser. Under an appropriate pump intensity, the mode-locked laser can experience a quasi-periodic route to chaos. Such a chaos consists of a stream of pulses with a fixed repetition frequency but random intensities. In this method, we do not require sampling procedure and external triggered clocks but directly quantize the chaotic pulses stream into random number sequence via an all-optical flip-flop. Moreover, our simulation results show that the pulse amplitude chaos has no periodicity and possesses a highly symmetric distribution of amplitude. Thus, in theory, the obtained random number sequence without post-processing has a high-quality randomness verified by industry-standard statistical tests.

Unraveling the Acidithiobacillus caldus complete genome and its central metabolisms for carbon assimilation.

Acidithiobacillus caldus is one of the dominant sulfur-oxidizing bacteria in bioleaching reactors. It plays the essential role in maintaining the high acidity and oxidation of reduced inorganic sulfur compounds during bioleaching process. In this report, the complete genome sequence of A. caldus SM-1 is presented. The genome is composed of one chromosome (2,932,225 bp) and four plasmids (pLAtc1, pLAtc2, pLAtc3, pLAtcm) and it is rich in repetitive sequences (accounting for 11% of the total genome), which are often associated with transposable genetic elements. In particular, twelve copies of ISAtfe and thirty-seven copies of ISAtc1 have been identified, suggesting that they are active transposons in the genome. A. caldus SM-1 encodes all enzymes for the central metabolism and the assimilation of carbon compounds, among which 29 proteins/enzymes were identifiable with proteomic tools. The SM-1 fixes CO(2)via the classical Calvin-Bassham-Benson (CBB) cycle, and can operate complete Embden-Meyerhof pathway (EMP), pentose phosphate pathway (PPP), and gluconeogenesis. It has an incomplete tricarboxylic acid cycle (TCA). Four putative transporters involved in carbohydrate uptake were identified. Taken together, the results suggested that SM-1 was able to assimilate carbohydrates and this was subsequently confirmed experimentally because addition of 1% glucose or sucrose in basic salt medium significantly increased the growth of SM-1. It was concluded that the complete genome of SM-1 provided fundamental data for further investigation of its physiology and genetics, in addition to the carbon metabolism revealed in this study.

Photonic ultrawideband signal generator using an optically injected chaotic semiconductor laser.

We propose and demonstrate a method to generate ultrawideband (UWB) signals in the optical domain based on the chaotic dynamics of an optically injected semiconductor laser with optical feedback. The chaotic-UWB pulses with a fractional bandwidth of 116% and central frequency of 6.88 GHz are experimentally generated by controlling the injection strength and frequency detuning of the chaotic laser. The spectrum of the UWB signals is in full compliance with the Federal Communications Commission spectral mask, and the experimental results are qualitatively consistent with the simulated results.

Photonic generation of ultrawideband pulse using semiconductor laser with optical feedback.

We propose and demonstrate an approach to the generation of an ultrawideband (UWB) pulse utilizing the nonlinear dynamics of a semiconductor laser (SL). The output UWB chaotic optical pulses generated by the SL with optical feedback can be controlled when the feedback strength and driving current of the SL are tuned. Our experiment proves that the spectrum characteristics of the UWB pulses satisfy Federal Communications Commission regulations, and the experimental results are consistent with the simulated results based on the laser's rate equations.

Clinical study of Photofrin photodynamic therapy for the treatment of relapse nasopharyngeal carcinoma.

OBJECTIVES: To evaluate the clinical response and adverse effects of Photofrin photodynamic therapy (PDT) in patients with relapse nasal pharyngeal cancer. METHODS: Thirty patients with relapse nasal pharyngeal cancer were randomly divided into PDT group and chemotherapy group. In PDT group, patients received intravenous administration of Photofrin (2mg/kg b.w.) and 48h later light (200-300J/cm) was delivered by a 630nm diode laser through a cylinder diffuser under endoscopic assistance. Two days after PDT the necrotic tissues were removed and newly identified sites were subject to another round of light irradiation. In chemotherapy group, the routine cisplatin and 5-fluorouracil (DDP/5-FU) remedy was used. Endoscopic and radiological examinations were performed during 6 months follow-up. The Karnofsy Score was used to evaluate the quality of life. RESULTS: The local response and nasal cavity obstruction remission rate in PDT group were better than that in chemotherapy group. The Karnofsy Score was also improved in PDT group. CONCLUSION: This pilot study suggests that Photofrin PDT is effective and safe in treatment of advanced nasal pharyngeal cancer and management of nasal obstruction.

[Clinical study of Photofrin photodynamic therapy for advanced cancers].

OBJECTIVE: To evaluate the clinical efficacy and adverse effects of Photofrin photodynamic therapy (PDT) in patients with advanced cancers. METHODS: Forty patients with advanced cancers in stage IV with lumen obstruction, who failed to respond positively to other treatment regimens, received intravenous administration of Photofrin as the photosensitizer at the dose of 2 mg/kg.b.w. 48 h before PDT by 630 nm light (DIOMED) delivered through cylinder diffusing tip quartz fibers that passed through the biopsy channel of a flexible endoscope. PDT endoscopy was repeated, the necrotic tissue removed and, if necessary, the primary sites and other newly identified sites were subjected to a second exposure 8 h later. Two days after the second exposure, endoscopy was again performed and the necrotic tissue removed. Endoscopy was repeated one month after PDT and periodically thereafter as needed to treat symptomatic residual tumor. RESULTS: The total rate of response to the treatment was 74% in these patients, and the rate of lumen obstruction due to the tumors decreased from 90% to 10% after PDT, with significantly improved Karnofsky performance score. CONCLUSION: Photofrin PDT is effective and safe in the treatment of advanced cancer, which may relieve lumen obstruction and improve patient quality of life.

[Investigation of short-term therapy results for radiofrequency ablation by positron emission tomography].

OBJECTIVE: To explore the possibility of evaluating the short-term therapeulic effect of radiofrequency ablation (RFA) in cancer treatment by positron emission tomography. METHODS: The radioactivity intensity of the tumor was detected by PET before and after RFA. RESULTS: Radioactivity blank was observed in all 33 cases with 54 lesions, indicating the elimination of the tumor was destroyed. CONCLUSION: PET is of great significance in evaluating the short-term effect of RFA.