Role of hydrogen sulfide-microRNA crosstalk in health and disease.

The mutual regulation between hydrogen sulfide (H2S) and microRNA (miRNA) is involved in the development of many diseases, including cancer, cardiovascular disease, inflammatory disease, and high-risk pregnancy. Abnormal expressions of endogenous H2S-producing enzyme and miRNA in tissues and cells often indicate the occurrence of diseases, so the maintenance of their normal levels in the body can mitigate damages caused by various factors. Many studies have found that H2S can promote the migration, invasion, and proliferation of cancer cells by regulating the expression of miRNA, while many H2S donors can inhibit cancer progression by interfering with the proliferation, apoptosis, cell cycle, metastasis, and angiogenesis of cancer cells. Furthermore, the mutual regulation between H2S and miRNA can also prevent cell injury in cardiovascular disease and inflammatory disease through anti-inflammation, anti-oxidation, anti-apoptosis, and pro-autophagy. In addition, H2S can promote angiogenesis and relieve vasoconstriction by regulating the expression of miRNA, thereby improving fetal growth in high-risk pregnancy. In this review, we discuss the mechanism of mutual regulation between H2S and miRNA in various diseases, which may provide reliable therapeutic targets for these diseases.

Sofosbuvir-velpatasvir in children 3-17 years old with hepatitis C virus infection.

BACKGROUND: The safety and efficacy of sofosbuvir-velpatasvir in children aged 3-17 years with chronic hepatitis C virus (HCV) infection of any genotype were evaluated. METHODS: In this Phase 2, multicenter, open-label study, patients received once daily for 12 weeks either sofosbuvir-velpatasvir 400/100 mg tablet (12-17 years), 200/50 mg low dose tablet or oral granules (3-11 years and ≥17 kg), or 150/37.5 mg oral granules (3-5 years and <17 kg). The efficacy endpoint was sustained virologic response 12 weeks after therapy (SVR12). Dose appropriateness was confirmed by intensive pharmacokinetics in each age group. FINDINGS: Among 216 patients treated, 76% had HCV genotype 1% and 12% had genotype 3. Rates of SVR12 were 83% (34/41) among 3-5-year-olds, 93% (68/73) among 6-11-year-olds, and 95% (97/102) among 12-17-year-olds. Only two patients experienced virologic failure. The most common adverse events were headache, fatigue, and nausea in 12-17-year-olds; vomiting, cough, and headache in 6-11-year-olds; and vomiting in 3-5-year-olds. Three patients discontinued treatment because of adverse events. Four patients had serious adverse events; all except auditory hallucination (n = 1) were considered unrelated to study drug. Exposures of sofosbuvir, its metabolite GS-331007, and velpatasvir were comparable to those in adults in prior Phase 2/3 studies. Population pharmacokinetic simulations supported weight-based dosing for children in this age range. INTERPRETATION: The pangenotypic regimen of sofosbuvir-velpatasvir is highly effective and safe in treating children 3-17 years with chronic HCV infection.

First report of Neophysopella vitis causing leaf rust on Parthenocissus semicordata in Guangdong Province, China.

In April 2022, leaf rust disease of Parthenocissus semicordata was discovered in the urban greenbelt in Guangzhou city, China (23.06°N, 113.16°E). The disease incidence was 70% and disease severity was 75%. Chlorotic spots and red-brown necrotic flecks were present on the upper surface of infected leaves, and orange uredinia were distributed on the lower surface (Fig. 1 a-c). Two representative disease plants were collected as voucher specimens and dried, then deposited in Mycological Herbarium of the Zhongkai University of Agriculture and Engineering (MHZU GR0413, MHZU GR0414). Microscopic examination of the pustules of the samples revealed the presence of uredial paraphyses and urediniospores (Fig.1 d-f). Uredial paraphyses were hyaline, incurved, length 20-25 µm and dorsal wall 4.5-8.5 µm thick. Urediniospores were subglobose to ovoid, 16-24.5 × 10.5-17 µm. The wall of the urediniospore was hyaline or pale yellow, echinulate, and 1.0-2.0 µm thick. Telial structures were not observed. The morphological characteristics of uredial paraphyses and urediniospores were consistent with Yoshitaka's description of Neophysopella vitis (Yoshitaka 2000). Ten uredinia were picked using a sterile tweezer and the FlaPure Plant DNA Extraction Kit (Genesand Biotech Co., Ltd) was used to extract genomic DNA. Primers ITS4-rust (5'-CAGATTACAAATTTGGGCT-3') /ITS 5u (5'-CAAGGTTTCTGTAGGTG-3') were used to amplify internal transcribed spacer (ITS) and Rust2inv (5'-GATGAAGAACACAGTGAAA-3') /LR6 (5'-CGCCAGTTCTGCTTACC-3') to amplify large subunit (LSU) rDNA regions (Zhao et al. 2021). The sequences were submitted to NCBI (ITS: OQ991182 OQ991183, LSU: OQ979612 OQ979613), and blastn analyses of ITS and LSU showed 99.81% and 99.84% identity with the sequences from N. vitis (ITS: OQ304336, LSU: OM420266), respectively, found in GenBank. ITS combined with LSU sequences from the current study and reference sequences from Zhao et al. (2021) were used to construct Maximum likelihood (ML) and Bayesian inference (BI) phylogenetic trees using CIPRES website. ML and BI phylogenetic trees showed that the sequences from the current study grouped with N. vitis, with bootstrap support and posterior probability of 98% and 1.0, respectively (Fig. 2). Morphological and molecular analyses confirmed that the rust fungus was N. vitis. In the pathogenicity test, urediniospores were picked from fresh diseased leaves with sterile tweezers, prepared into spore suspensions (1.0 × 106 urediniospores/ml), and sprayed on a one-week-old leaf from three healthy of potted plants of P. semicordata, while three other healthy leaves were sprayed with sterile water as control. Each treated leaf was wrapped in a plastic bag and incubated in the dark at 25℃ for 48 h after which plastic bags were removed and the plant were moved to a greenhouse at 25℃. At 15 days after inoculation, symptoms and the morphology of urediniospores were confirmed to be the same as those observed in the field collection and no symptoms or uredinia were observed in the control group (Fig.1 g, h). Yoshitaka first discovered leaf rust on P. semicordata caused by N. vitis in Nepal(Yoshitaka 2000). To our knowledge, this is the first report of N. vitis causing leaf rust on P. semicordata in China. P. semicordata is often used as an ornamental plant for exterior wall decoration in urban landscaping and court. The occurrence of this disease can lead to the decline of the P. semicordata leaves and the impairment of the plants aesthetically.

[Effects of acute fear stress on spatial memory and neuronal plasticity in the medial prefrontal cortex in mice].

The purpose of this study was to investigate the effects of acute fear stress on the spatial memory and neuronal plasticity of medial prefrontal cortex (mPFC) neurons in mice, and to elucidate the mechanisms underlying mPFC plasticity and post-stress memory regulation. Male C57BL/6 mice (6 weeks old) were randomly divided into control group and stress group. Foot shock stress was applied to establish an acute fear stress model. Changes in spatial memory were examined by the Morris water maze test, and the dynamic changes in the spike encoding of pyramidal neurons and GABAergic neurons in the prelimbic cortex (PrL) and infralimbic cortex (IL) of mPFC were detected by whole-cell recording. The results showed that acute fear stress significantly enhanced the percentage of freezing and the number of freezing, reduced the average speed, decreased the escape latency during acquisition phase, extended the probing time in the first quadrant and shortened the probing time in the third quadrant during probe trial, increased inter-spike interval, energy barrier and absolute refractory period of GABAergic neurons in the PrL and pyramidal neurons in the IL, while decreased inter-spike interval, energy barrier and absolute refractory period of pyramidal neurons in the PrL and GABAergic neurons in the IL. These results suggest that acute fear stress can enhance the spatial memory of mice, elevate the excitability and function of the PrL, while deteriorate the excitability and function of the IL, and the underlying mechanism may involve the role of mPFC microcircuitry plasticity in spatial memory after stress.

Microbial predation accelerates granulation and modulates microbial community composition.

BACKGROUND: Bacterial communities are responsible for biological nutrient removal and flocculation in engineered systems such as activated floccular sludge. Predators such as bacteriophage and protozoa exert significant predation pressure and cause bacterial mortality within these communities. However, the roles of bacteriophage and protozoan predation in impacting granulation process remain limited. Recent studies hypothesised that protozoa, particularly sessile ciliates, could have an important role in granulation as these ciliates were often observed in high abundance on surfaces of granules. Bacteriophages were hypothesized to contribute to granular stability through bacteriophage-mediated extracellular DNA release by lysing bacterial cells. This current study investigated the bacteriophage and protozoan communities throughout the granulation process. In addition, the importance of protozoan predation during granulation was also determined through chemical killing of protozoa in the floccular sludge. RESULTS: Four independent bioreactors seeded with activated floccular sludge were operated for aerobic granulation for 11 weeks. Changes in the phage, protozoa and bacterial communities were characterized throughout the granulation process. The filamentous phage, Inoviridae, increased in abundance at the initiation phase of granulation. However, the abundance shifted towards lytic phages during the maturation phase. In contrast, the abundance and diversity of protozoa decreased initially, possibly due to the reduction in settling time and subsequent washout. Upon the formation of granules, ciliated protozoa from the class Oligohymenophorea were the dominant group of protozoa based on metacommunity analysis. These protozoa had a strong, positive-correlation with the initial formation of compact aggregates prior to granule development. Furthermore, chemical inhibition of these ciliates in the floccular sludge delayed the initiation of granule formation. Analysis of the bacterial communities in the thiram treated sludge demonstrated that the recovery of 'Candidatus Accumulibacter' was positively correlated with the formation of compact aggregates and granules. CONCLUSION: Predation by bacteriophage and protozoa were positively correlated with the formation of aerobic granules. Increases in Inoviridae abundance suggested that filamentous phages may promote the structural formation of granules. Initiation of granules formation was delayed due to an absence of protozoa after chemical treatment. The presence of 'Candidatus Accumulibacter' was necessary for the formation of granules in the absence of protozoa.

Sofosbuvir and Ribavirin Therapy for Children Aged 3 to <12 Years With Hepatitis C Virus Genotype 2 or 3 Infection.

Currently, the only approved hepatitis C virus (HCV) treatment for children aged <12 years is pegylated interferon plus ribavirin. In an open-label study, we evaluated the safety and efficacy of sofosbuvir plus ribavirin for 12 weeks in children aged 3 to <12 years chronically infected with genotype 2 or for 24 weeks in patients with genotype 3. Patients aged 3 to <6 years weighing <17 kg received sofosbuvir 150 mg, and patients aged 3 to <6 years weighing ≥17 kg and all patients aged 6 to <12 years received sofosbuvir 200 mg once daily. Intensive pharmacokinetic sampling conducted in each age group confirmed the appropriateness of sofosbuvir doses. For all patients, ribavirin dosing was determined by baseline weight (up to 1,400 mg/day, two divided doses). The primary efficacy endpoint was sustained virologic response 12 weeks after therapy (SVR12). Fifty-four patients were enrolled (41 aged 6 to <12 years and 13 aged 3 to <6 years). Most were treatment naïve (98%) and infected perinatally (94%). All but one patient achieved SVR12 (53/54, 98%; 95% confidence interval, 90%-100%). The patient who did not achieve SVR12 was a 4-year-old who discontinued treatment after 3 days because of "abnormal drug taste." The most commonly reported adverse events in patients aged 6 to <12 years were vomiting (32%) and headache (29%), and those in patients aged 3 to <6 years were vomiting (46%) and diarrhea (39%). One 3-year-old patient had a serious adverse event of accidental ribavirin overdose requiring hospitalization for monitoring; this patient completed treatment and achieved SVR12. Conclusion: Sofosbuvir plus ribavirin was well tolerated and highly effective in children aged 3 to <12 years with chronic HCV genotype 2 or 3 infection.

Colorectal cancer survivorship: A systematic review and thematic synthesis of qualitative research.

INTRODUCTION: With rapid changes in treatments for colorectal cancer (CRC), qualitative research into CRC survivorship requires greater synthesis. This paper aims to fill this gap through a systematic review (PROSPERO CRD42019131576) and thematic synthesis of the qualitative literature on survivorship experiences across early-stage and advanced CRC survivors. METHODS: CINAHL, Embase, MEDLINE, PsycINFO and PubMed were searched for qualitative CRC survivorship papers. Titles, abstracts and full texts were screened. Included articles (n = 81) underwent data extraction, CASP qualitative bias ratings and thematic synthesis. RESULTS: Bowel dysfunction caused functional limitations and negative quality of life (QoL), while stomas posed threats to body image and confidence. Physical symptoms hindered return to work, increasing financial burdens. Survivors' unmet needs included information regarding symptom expectations and management, and ongoing support throughout recovery. Advanced and early-stage survivors shared similar experiences. Advanced survivors struggled with fear of cancer recurrence/progression and feelings of powerlessness. Functional limitations, financial impacts and sexuality in advanced survivors were underexplored areas. CONCLUSION: CRC and its treatments impact survivors' QoL in all areas. A coordinated supportive care response is required to address survivors' unmet needs. Future qualitative studies should explore advanced CRC subpopulations, treatment-specific impacts on QoL and long-term (>5 years) impacts on CRC survivors.

Convection and the Extracellular Matrix Dictate Inter- and Intra-Biofilm Quorum Sensing Communication in Environmental Systems.

The mechanisms and impact of bacterial quorum sensing (QS) for the coordination of population-level behaviors are well studied under laboratory conditions. However, it is unclear how, in otherwise open environmental systems, QS signals accumulate to sufficient concentration to induce QS phenotypes, especially when quorum quenching (QQ) organisms are also present. We explore the impact of QQ activity on QS signaling in spatially organized biofilms in scenarios that mimic open systems of natural and engineered environments. Using a functionally differentiated biofilm system, we show that the extracellular matrix, local flow, and QQ interact to modulate communication. In still aqueous environments, convection facilitates signal dispersal while the matrix absorbs and relays signals to the cells. This process facilitates inter-biofilm communication even at low extracellular signal concentrations. Within the biofilm, the matrix further regulates the transport of the competing QS and QQ molecules, leading to heterogenous QS behavior. Importantly, only extracellular QQ enzymes can effectively control QS signaling, suggesting that the intracellular QQ enzymes may not have evolved to degrade environmental QS signals for competition.

Hepatitis C in 2020: A North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Position Paper.

In 1989, a collaboration between the Centers for Disease Control (CDC) and a California biotechnology company identified the hepatitis C virus (HCV, formerly known as non-A, non-B hepatitis virus) as the causative agent in the epidemic of silent posttransfusion hepatitis resulting in cirrhosis. We now know that, the HCV genome is a 9.6 kb positive, single-stranded RNA. A single open reading frame encodes a 3011 amino acid residue polyprotein that undergoes proteolysis to yield 10 individual gene products, consisting of 3 structural proteins (core and envelope glycoproteins E1 and E2) and 7 nonstructural (NS) proteins (p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B), which participate in posttranslational proteolytic processing and replication of HCV genetic material. Less than 25 years later, a new class of medications, known as direct-acting antivirals (DAAs) which target these proteins, were introduced to treat HCV infection. These highly effective antiviral agents are now approved for use in children as young as 3 years of age and have demonstrated sustained virologic responses exceeding 90% in most genotypes. Although tremendous scientific progress has been made, the incidence of acute HCV infections has increased by 4-fold since 2005, compounded in the last decade by a surge in opioid and intravenous drug use. Unfortunately, awareness of this deadly hepatotropic virus among members of the lay public remains limited. Patient education, advocacy, and counseling must, therefore, complement the availability of curative treatments against HCV infection if this virus is to be eradicated.

Emerging New Diagnostic Modalities and Therapies of Nonalcoholic Fatty Liver Disease.

PURPOSE OF REVIEW: Nonalcoholic fatty liver disease (NAFLD) has emerged as the leading cause of chronic liver disease in both adults and children. In this article, we review recent developments in the screening, diagnosis, and treatment of pediatric NAFLD. RECENT FINDINGS: Although alanine aminotransferase (ALT) remains the best screening test for NAFLD in children, and liver biopsy is still required for the diagnosis of nonalcoholic steatohepatitis (NASH), other noninvasive biomarker/imaging studies (MRI-PDFF and VCTE) have emerged as diagnostic methods for pediatric NAFLD. Two large clinical therapeutic trials testing vitamin E, metformin, and cysteamine in pediatric NAFLD yielded mostly inconclusive results. Bariatric surgery has begun to be used in adolescents with severe obesity. An adult phase 2 study using obeticholic acid (OCA) to treat NASH patients with fibrosis showed some positive results. As we continue to await the first FDA-approved therapeutic agent for NASH, lifestyle change remains the main modality of treatment. Newer diagnostic and treatment modalities for pediatric NAFLD continue to be in development under FDA guidance.

Safety and Efficacy of Ledipasvir-Sofosbuvir With or Without Ribavirin for Chronic Hepatitis C in Children Ages 6-11.

Currently, there are no interferon-free treatments available for hepatitis C virus (HCV)-infected patients younger than 12 years. We evaluated the safety and effectiveness of the all-oral regimen ledipasvir-sofosbuvir ± ribavirin in HCV-infected children aged 6 to <12 years. In an open-label study, patients aged 6 to <12 years received ledipasvir 45 mg-sofosbuvir 200 mg as two fixed-dose combination tablets 22.5/100 mg once daily, with or without ribavirin, for 12 or 24 weeks, depending on HCV genotype and cirrhosis status. The primary efficacy endpoint was sustained virologic response 12 weeks after therapy (SVR12). Twelve patients underwent intensive pharmacokinetic sampling to confirm the appropriateness of the ledipasvir and sofosbuvir dosages. Ninety-two patients were enrolled (88 genotype 1, 2 genotype 3, and 2 genotype 4), with a median age of 9 years (range, 6-11). Most were perinatally infected (97%) and treatment-naive (78%). Two were confirmed to have cirrhosis, while the degree of fibrosis was unknown in 55 patients. The overall SVR12 rate was 99% (91/92; 95% confidence interval, 94%-100%). The single patient not reaching SVR relapsed 4 weeks after completing 12 weeks of treatment. The most common adverse events were headache and pyrexia. One patient had three serious adverse events, which were considered to be not related to study treatment: tooth abscess, abdominal pain, and gastroenteritis. The area under the concentration-time curve and maximum concentration values for sofosbuvir, its primary metabolite GS-331007, and ledipasvir were within predefined pharmacokinetic equivalence boundaries (50%-200%) compared to values in adults in phase 2/3 of the ledipasvir and sofosbuvir studies. Conclusion: Ledipasvir-sofosbuvir was well tolerated and highly effective in children 6 to <12 years old with chronic HCV.

Doubly Nonnegative and Semidefinite Relaxations for the Densest k-Subgraph Problem.

The densest k-subgraph (DkS) maximization problem is to find a set of k vertices with maximum total weight of edges in the subgraph induced by this set. This problem is in general NP-hard. In this paper, two relaxation methods for solving the DkS problem are presented. One is doubly nonnegative relaxation, and the other is semidefinite relaxation with tighter relaxation compare with the relaxation of standard semidefinite. The two relaxation problems are equivalent under the suitable conditions. Moreover, the corresponding approximation ratios' results are given for these relaxation problems. Finally, some numerical examples are tested to show the comparison of these relaxation problems, and the numerical results show that the doubly nonnegative relaxation is more promising than the semidefinite relaxation for solving some DkS problems.

An RNAi-based screen reveals PLK1, CDK1 and NDC80 as potential therapeutic targets in malignant pleural mesothelioma.

This corrects the article DOI: 10.1038/bjc.2017.85.

Sofosbuvir and ribavirin in adolescents 12-17 years old with hepatitis C virus genotype 2 or 3 infection.

Children with chronic hepatitis C virus infection have limited treatment options. We evaluated the all-oral combination of sofosbuvir and ribavirin in adolescents aged 12-17 with hepatitis C virus genotype 2 or 3 (ClinicalTrials.gov NCT02175758). Fifty-two patients received sofosbuvir 400 mg once daily and weight-based ribavirin twice daily for 12 (genotype 2) or 24 (genotype 3) weeks. The pharmacokinetics of sofosbuvir and its metabolite GS-331007 were evaluated by intensive plasma sampling at day 7 in the first 10 patients enrolled and by sparse sampling in all patients throughout treatment. The primary efficacy endpoint was the percentage of patients with a sustained virologic response 12 weeks after treatment (SVR12). The median age of patients was 15 years, and 75% had genotype 3. Eighty-three percent of patients were treatment-naive, and 73% were infected by vertical transmission. Forty percent were assessed as not having cirrhosis; the remainder did not have a cirrhosis determination. Overall, SVR12 was achieved by 98% of patients (51/52; 95% confidence interval, 90%-100%). SVR12 rates were 100% (13/13) for patients with genotype 2 and 97% (38/39) for those with genotype 3. The single patient who did not achieve SVR12 was lost to follow-up after achieving SVR4. The most commonly reported adverse events were nausea (27%) and headache (23%). When compared with the exposure in adults treated in phase 2 and 3 sofosbuvir studies, the area under the curve and maximum concentration for sofosbuvir and GS-331007 in adolescents were within predefined pharmacokinetic equivalence boundaries of 50%-200%. CONCLUSION: Sofosbuvir and ribavirin was safe and highly effective in adolescents with chronic hepatitis C virus genotype 2 or 3 infection. (Hepatology 2017;66:1102-1110).

The safety and effectiveness of ledipasvir-sofosbuvir in adolescents 12-17 years old with hepatitis C virus genotype 1 infection.

No all-oral, direct-acting antiviral regimens have been approved for children with chronic hepatitis C virus (HCV) infection. We conducted a phase 2, multicenter, open-label study to evaluate the efficacy and safety of ledipasvir-sofosbuvir in adolescents with chronic HCV genotype 1 infection. One hundred patients aged 12-17 years received a combination tablet of 90 mg ledipasvir and 400 mg sofosbuvir once daily for 12 weeks. On the tenth day following initiation of dosing, 10 patients underwent an intensive pharmacokinetic evaluation of the concentrations of sofosbuvir, ledipasvir, and the sofosbuvir metabolite GS-331007. The primary efficacy endpoint was the percentage of patients with a sustained virologic response at 12 weeks posttreatment. Median age of patients was 15 years (range 12-17). A majority (80%) were HCV treatment-naive, and 84% were infected through perinatal transmission. One patient had cirrhosis, and 42 did not; in 57 patients the degree of fibrosis was unknown. Overall, 98% (98/100; 95% confidence interval 93%-100%) of patients reached sustained virologic response at 12 weeks. No patient had virologic failure. The 2 patients who did not achieve sustained virologic response at 12 weeks were lost to follow-up either during or after treatment. The three most commonly reported adverse events were headache (27% of patients), diarrhea (14%), and fatigue (13%). No serious adverse events were reported. Area under the concentration-time curve (tau) and maximum concentration values for sofosbuvir, ledipasvir, and GS-331007 were within the predefined pharmacokinetic equivalence boundaries of 50%-200% when compared with adults from phase 2 and 3 studies of ledipasvir and sofosbuvir. CONCLUSION: Ledipasvir-sofosbuvir was highly effective at treating adolescents with chronic HCV genotype 1 infection; the dose of ledipasvir-sofosbuvir currently used in adults was well tolerated in adolescents and had an appropriate pharmacokinetic profile. (Hepatology 2017;66:371-378).

All together now: experimental multispecies biofilm model systems.

Studies of microorganisms have traditionally focused on single species populations, which have greatly facilitated our understanding of the genetics and physiology that underpin microbial growth, adaptation and biofilm development. However, given that most microorganisms exist as multispecies consortia, the field is increasingly exploring microbial communities using a range of technologies traditionally limited to populations, including meta-omics based approaches and high resolution imaging. The experimental communities currently being explored range from relatively low diversity, for example, two to four species, to significantly more complex systems, comprised of several hundred species. Results from both defined and undefined communities have revealed a number of emergent properties, including improved stress tolerance, increased biomass production, community level signalling and metabolic cooperation. Based on results published to date, we submit that community-based studies are timely and increasingly reveal new properties associated with multispecies consortia that could not be predicted by studies of the individual component species. Here, we review a range of defined and undefined experimental systems used to study microbial community interactions.

Sphingobacterium cellulitidis sp. nov., isolated from clinical and environmental sources.

The taxonomic position of two isolates belonging to the genus Sphingobacterium was determined. The first isolate, R-53603T, was obtained from purulent discharge from the toe of a cellulitis patient in Kuwait. Comparative 16S rRNA gene sequence analysis revealed 99.87 % similarity of R-53603T with environmental isolate P031 (=R-53745) originating from activated sludge in Singapore. The two isolates were phylogenetically positioned on the same sub-branch. Highest 16S rRNA gene sequence similarity was found with the type strains of Sphingobacterium mizutaii (98.23 %), Sphingobacterium lactis (97.78 %) and Sphingobacterium daejeonense (97.14 %). DNA-DNA hybridizations revealed <70 % relatedness between the two isolates and the type strains of the close phylogenetic neighbours S. mizutaii(18.0-24.5 %), S. lactis(20.3-25.9 %) and S. daejeonense(13.2-20.0 %). The high relative contribution of iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c) in the cellular fatty acid profiles of R-53603T and R-53745, the presence of sphingophospholipids, MK-7 as the dominant menaquinone and phosphatidylethanolamine as the major polar lipid in strain R-53603T are typical chemotaxonomic characteristics for members of the genus Sphingobacterium. Phenotypic features most useful for differentiation of the two novel strains from the most closely related species S. mizutaii include growth on MacConkey agar, and utilization of stachyose, guanidine HCl and lithium chloride in Biolog GEN III tests. Strains R-53603T and R-53745 thus represent a novel species, for which the name Sphingobacterium cellulitidis sp. nov. is proposed. The type strain is R-53603T (=LMG 28764T=DSM 102028T).

Microbial Photoelectrotrophic Denitrification as a Sustainable and Efficient Way for Reducing Nitrate to Nitrogen.

Biological removal of nitrate, a highly concerning contaminant, is limited when the aqueous environment lacks bioavailable electron donors. In this study, we demonstrated, for the first time, that bacteria can directly use the electrons originated from the photoelectrochemical process to carry out the denitrification. In such photoelectrotrophic denitrification (PEDeN) systems (denitrification biocathode coupling with TiO2 photoanode), nitrogen removal was verified solely relying on the illumination dosing without consuming additional chemical reductant or electric power. Under the UV illumination (30 mW·cm-2, wavelength at 380 ± 20 nm), nitrate reduction in PEDeN apparently followed the first-order kinetics with a constant of 0.13 ± 0.023 h-1. Nitrate was found to be almost completely converted to nitrogen gas at the end of batch test. Compared to the electrotrophic denitrification systems driven by organics (OEDeN, biocathode/acetate consuming bioanode) or electricity (EEDeN, biocathode/abiotic anode), the denitrification rate in PEDeN equaled that in OEDeN with a COD/N ratio of 9.0 or that in EEDeN with an applied voltage at 2.0 V. This study provides a sustainable technical approach for eliminating nitrate from water. PEDeN as a novel microbial metabolism may shed further light onto the role of sunlight played in the nitrogen cycling in certain semiconductive and conductive minerals-enriched aqueous environment.

[Study on Si-PIN and CdTe Detectors Used in Energy Dispersive X-Ray Fluorescence Measurements].

Semiconductor detector is widely used in energy dispersive X-ray fluorescence measurements due to its excellent performance. In this paper, Si-PIN and CdTe semiconductor detectors were studied, performances of the two detectors were compared in material properties, detection efficiency, energy resolution and other aspects. Focused on the performance of the detectors influenced by the thickness of detector sensitive area, energy of incident X-ray, shaping time of post-stage circuit, and analyzed the differences of energy spectrum caused by escape peaks and hole trailing. Aiming at the problem of incomplete hole collection in detector, a digital multi-channel analyzer (DMCA) based on FPGA with rise-time discriminator was designed, it could reduce the influence of hole trailing effectively and improve energy resolution. The experimentation results indicate that the detection efficiency of Si-PIN and CdTe is roughly equal when energy is below 15 keV while CdTe has much higher detection efficiency than Si-PIN when energy is above 15 keV. The optimum forming time of the Si-PIN detector is about 10 µs, and the CdTe detector is about 2.6 µs, so the CdTe detector is more suitable for the high count rate condition. Si-PIN detector has better energy resolution than CdTe detector for different energy incident X-ray. CdTe detector has obvious hole tailing effect and the energy resolution of CdTe detector is significantly improved by using DMCA with rise-time discrimination.

Living and Conducting: Coating Individual Bacterial Cells with In†Situ Formed Polypyrrole.

Coating individual bacterial cells with conjugated polymers to endow them with more functionalities is highly desirable. Here, we developed an in situ polymerization method to coat polypyrrole on the surface of individual Shewanella oneidensis MR-1, Escherichia coli, Ochrobacterium anthropic or Streptococcus thermophilus. All of these as-coated cells from different bacterial species displayed enhanced conductivities without affecting viability, suggesting the generality of our coating method. Because of their excellent conductivity, we employed polypyrrole-coated Shewanella oneidensis MR-1 as an anode in microbial fuel cells (MFCs) and found that not only direct contact-based extracellular electron transfer is dramatically enhanced, but also the viability of bacterial cells in MFCs is improved. Our results indicate that coating individual bacteria with conjugated polymers could be a promising strategy to enhance their performance or enrich them with more functionalities.