Evaluation and optimization of the protocols for measuring cytochrome P450 activity in aphids.

Insect cytochrome P450 plays major roles in detoxification of phytotoxin and insecticides. However, determination of P450 activity in aphids has variable success and there is no reliable method yet. In this study, we found that homogenizing the green peach aphid, Myzus persicae, in the 96-well microplate resulted in significantly higher P450 activities than those in Eppendorf tube. Homogenizing aphids in Eppendorf tube released uncharacterized compounds that inhibited aphids and pig liver P450 activities, whereas aphids homogenized in the microplate may not be completely ground and thus released fewer such inhibitors. Then, the microplate homogenization method was optimized as follows: one or two aphids were placed in one well of the 96 well-microplate and ground in phosphate buffer using pipette tips for 20 cycles, followed by addition of 7-ethoxycoumarin, and then incubated for 1 h at room temperature, after which glycine buffer-ethanol mixture was added to stop the reaction. This method is also suitable for the pea aphid, Acyrthosiphon pisum, and the bird cherry-oat aphid, Rhopalosiphum padi. These results highlight the importance of considering inhibitory effects of endogenous compounds in insects on their P450 activities and provide one possible method to reduce these inhibitory effects.

Evaluation of a Cryptococcus capsular polysaccharide detection FungiXpert LFA (lateral flow assay) for the rapid diagnosis of Cryptococcosis.

Cryptococcus is an opportunistic pathogenic fungus and is the major cause of fungal meningitis. The cryptococcal antigen (CrAg) lateral flow assay (LFA) is an immunochromatographic test system that has simplified diagnosis as a point-of-care test. In this study, we evaluated the diagnostic performance of Cryptococcal capsular polysaccharide detection FungiXpert (Genobio Pharmaceutical, Tianjin, China) using serum and cerebrospinal fluid (CSF) samples for the diagnosis of cryptococcosis and investigated the cross-reaction of the assays to pathogenic fungi and bacterium by comparing it to the U.S. Food and Drug Administration (US FDA)-approved IMMY CrAg LFA. Eighty CSF and 119 serum/plasma samples from 158 patients were retrospectively collected to test for qualitative or semi-quantitative detection of CrAg. Cross-reaction of the assays was tested using 28 fungi and 1 bacterium. Compared to IMMY CrAg LFA, the FungiXpert LFA demonstrated 99.1% sensitivity and 98.9% specificity in the qualitative test. In the 96 semi-quantitative CrAg assay results, 39 (40.6%) test titers of FungiXpert LFA were 1-2 dilutions higher than those of IMMY CrAg LFA. The Intraclass Correlation Coefficient of the Semi-quantitative results of CrAg titer tests via the two assays was 0.976. Similar to IMMY CrAg LFA, FungiXpert LFA showed cross-reactivity with Trichosporon asahii. Compared with the IMMY CrAg LFA, the FungiXpert LFA showed an equal, yet, excellent performance. However, it is important to note that these two assays have potential cross-reactivity to T. asahii when diagnosing patients. FungiXpert LFA is a rapid screening method for the effective and practical diagnosis and treatment of cryptococcosis. LAY SUMMARY: The FungiXpert LFA was developed to diagnose fungal meningitis caused by Cryptococcus yeasts, by using serum or cerebrospinal fluid. It was compared to an existing lateral flow assay (LFA). The FungiXpert LFA performed well in qualitative and semi-quantitative tests.

Pri-miR-144 rs9279 is associated with type 2 diabetes and regulation of stress response.

Single-nucleotide polymorphisms (SNPs) of microRNAs (miRNAs) may alter miRNA expression, binding affinity, and/or messenger RNA expression levels of the target genes, thus leading to disease susceptibility. This study explored the association between SNPs in neuroendocrine stress response-related miRNAs and type 2 diabetes (T2D). In the screening stage, the association between six candidate SNPs of miRNAs and T2D was analyzed in a case-control study including 504 T2D cases and 494 healthy controls. Homozygous GG genotype of pri-miR-144 rs9279 showed significant association with increased risk of T2D compared with homozygous TT genotype (adjusted odds ratio [OR] = 1.62, 95% confidence interval [CI]: 1.07-2.45; p = .023) and the combined TT/TG genotype (adjusted OR = 1.59, 95% CI: 1.08-2.36; p = .020). In the validation stage, the association was further validated in a second independent set of subjects. The GG genotype showed consistent directions and effect sizes that were identified in previous additive and recessive models. The expression levels of miRNAs were further compared between different genotypes in the 179 newly diagnosed cases and 183 frequency-matched healthy controls. As a result, the GG genotype carriers had significantly upregulated expression of plasma miR-144 and cortisol, as compared to individuals with TT and TG genotypes, respectively, in total subjects and subgroups (p < .05). Eventually, NR3C1 was proved to be a stress-related target gene of miR-144, indicating that pri-miR-144 rs9279 may contribute to the development of T2D by altering regulation of stress response.

Assessment of anti-PD-(L)1 for patients with coexisting malignant tumor and tuberculosis classified by active, latent, and obsolete stage.

BACKGROUND: It is not a rare clinical scenario to have patients presenting with coexisting malignant tumor and tuberculosis. Whether it is feasible to conduct programmed death-(ligand) 1 [PD-(L)1] inhibitors to these patients, especially those with active tuberculosis treated with concurrent anti-tuberculosis, is still unknown. METHODS: This study enrolled patients with coexisting malignancy and tuberculosis and treated with anti-PD-(L)1 from Jan 2018 to July 2021 in 2 institutions. The progression-free survival (PFS), objective response rate (ORR), and safety of anti-PD-(L)1 therapy, as well as response to anti-tuberculosis treatment, were evaluated. RESULTS: A total of 98 patients were screened from this cohort study, with 45 (45.9%), 21 (21.4%), and 32 (32.7%) patients diagnosed with active, latent, and obsolete tuberculosis, respectively. The overall ORR was 36.0% for anti-PD-(L)1 therapy, with 34.2%, 35.5%, and 41.2% for each subgroup. Median PFS was 8.0 vs 6.0 vs 6.0 months (P=0.685) for each subgroup at the time of this analysis. For patients with active tuberculosis treated with concurrent anti-tuberculosis, median duration of anti-tuberculosis therapy was 10.0 (95% CI, 8.01-11.99) months. There were 83.3% (20/24) and 93.3% (42/45) patients showing sputum conversion and radiographic response, respectively, after anti-tuberculosis therapy, and two patients experienced tuberculosis relapse. Notably, none of the patients in latent and only one patient in obsolete subgroups showed tuberculosis induction or relapse after anti-PD-(L)1 therapy. Treatment-related adverse events (TRAEs) occurred in 33 patients (73.3%) when treated with concurrent anti-PD-(L)1 and anti-tuberculosis. Grade 3 or higher TRAEs were hematotoxicity (n = 5, 11.1%), and one patient suffered grade 3 pneumonitis leading to the discontinuation of immunotherapy. CONCLUSIONS: This study demonstrated that patients with coexisting malignant tumor and tuberculosis benefited equally from anti-PD-(L)1 therapy, and anti-tuberculosis response was unimpaired for those with active tuberculosis. Notably, the combination of anti-PD-(L)1 and anti-tuberculosis therapy was well-tolerated without significant unexpected toxic effects.

Identification of Spodoptera frugiperda importin alphas that facilitate the nuclear import of Autographa californica multiple nucleopolyhedrovirus DNA polymerase.

Proteins containing nuclear localization signals (NLSs) are actively transported into the nucleus via the classic importin-α/ß-mediated pathway, and NLSs are recognized by members of the importin-α family. Most studies of insect importin-αs have focused on Drosophila to date, little is known about the importin-α proteins in Lepidoptera insects. In this study, we identified four putative importin-α homologues, Spodoptera frugiperda importin-α1 (SfIMA1), SfIMA2, SfIMA4 and SfIMA7, from Sf9 cells. Immunofluorescence analysis showed that SfIMA2, SfIMA4 and SfIMA7 localized to the nucleus, while SfIMA1 distributed in cytoplasm. Additionally, SfIMA4 and SfIMA7 were also detected in the nuclear membrane of Sf9 cells. SfIMA1, SfIMA4 and SfIMA7, but not SfIMA2, were found to associate with the C terminus of AcMNPV DNA polymerase (DNApol) that harbours a typical monopartite NLS and a classic bipartite NLS. Further analysis of protein-protein interactions revealed that SfIMA1 specifically recognizes the bipartite NLS, while SfIMA4 and SfIMA7 bind to both monopartite and bipartite NLSs. Together, our results suggested that SfIMA1, SfIMA4 and SfIMA7 play important roles in the nuclear import of AcMNPV DNApol C terminus in Sf9 cells.

Prospective study of ALDH1A1 gene polymorphisms associated with antituberculosis drug-induced liver injury in western Chinese Han population.

Antituberculosis drug-induced liver injury (ATDILI) has received increasing attention globally, which may limit the effectiveness of antituberculosis (anti-TB) treatment. Many host genetic determinants of ATDILI have been identified recently. As little knowledge is currently available about the association between aldehyde dehydrogenase 1 family member A1 (ALDH1A1) polymorphisms and ATDILI, the association between their variants and the susceptibility to ATDILI was investigated. A total of 747 patients with TB treated by first-line anti-TB drugs were prospectively enrolled at West China Hospital. Genomic DNA was extracted from the peripheral blood sample of each patient and seven single-nucleotide polymorphisms (SNPs) of ALDH1A1 gene were screened and genotyped with a custom-designed 2×48-plex SNP Scan TM kit. The patients were followed up monthly to monitor the development of ATDILI. The C allele and the CA genotype of rs7852860 were significantly associated with an elevated risk for ATDILI (p = .006 and 0.005, respectively), which was consistent with the results in the dominant and additive models. No allele, genotype, or genetic model of the other six SNPs (rs3764435, rs348471, rs63319, rs610529, rs7027604, rs8187876) were found to be associated with susceptibility to ATDILI. The findings first demonstrate that rs7852860 variants in ALDH1A1 gene is associated with susceptibility to ATDILI in the Chinese Han population. Validation studies with larger sample sizes and other ethnic groups are needed to confirm the findings.

Platelet count trends and response to fondaparinux in a cohort of heparin-induced thrombocytopenia suspected patients after pulmonary endarterectomy.

A definitive diagnosis of heparin-induced thrombocytopenia (HIT) is difficult to make, especially in patients undergoing cardiac surgery. In this retrospective cohort study, we assessed the platelet count trends and the response to fondaparinux in a population of patients of suspected HIT after pulmonary endarterectomy (PEA). Patients enrolled in this study were over the age of 18 years, and survived longer than 7 days after PEA between January 1, 2011 and December 31, 2015. HIT likelihood was assessed by the 4 T's score and interpreted by our institutional algorithm. 54 patients were operated, and 49 patients met the inclusion criteria. Six patients met the criteria for suspected HIT and were treated with fondaparinux until the platelet recovered. No significant difference was observed of clinical characteristics between intermediate to high HIT likelihood patients (HIT SUSPECTED) and low HIT likelihood patients (NO HIT SUSPECTED). HIT SUSPECTED patients reached platelet count lowest later (about 5.5 days after PEA), while NO HIT SUSPECTED patients is about 4.0 days after PEA. Percentage of platelet counts decrease (> 50%) was larger than NO HIT SUSPECTED patients (< 50%). There was no difference in mortality or residual pulmonary hypertension between HIT SUSPECTED and NO HIT SUSPECTED patients. Two HIT SUSPECTED patients who used heparin after PEA died, the other four survived by replacing heparin or low molecular weight heparin with fondaparinux. Suspected HIT patients should be surveilled carefully. Platelet counts trends may have some hints in the prevention of HIT. Fondaparinux may be effective for patients with suspected HIT.

Natural product-based semisynthesis and biological evaluation of thiol/amino-Michael adducts of xanthatin derived from Xanthium strumarium as potential pesticidal agents.

Xanthatin, a natural sesquiterpene lactone, occurs as one of the major constituents of Xanthium plants (Compositae) and exhibits many important biological properties. To discover natural products-based pesticides, forty-nine Michael-type thiol/amino adducts of xanthatin were synthesized and characterized, while their pesticidal activities were investigated. Among them, compounds 2c, 2h, 2i, and 2t exhibited more potent antifungal activity against Botrytis cinerea (IC50 = 0.96, 0.38, 6.33, and 7.21 µg/mL, respectively) than xanthatin and the two commercial fungicides. Compounds 2t and 2u displayed broad-spectrum and excellent antifungal effects against all tested phytopathogenic fungi, while their IC50 values ranged from 7.21 to 75.88 µg/mL. Compounds 2a, 2f, 2l, 2m, 2v, 7c, 7e, 7h, 7i, and 7j showed moderate larvicidal activity against Plutella xylostella Linnaeus. Furthermore, compounds 2b, 7g, and 7h demonstrated significant ovicidal activity against P. xylostella with the LC50 values of 14.04, 10.00, and 11.95 mg/L, respectively. These findings suggest that thiol/amino appended in the C-13 position of xanthatin may improve antifungal and ovicidal activities for the derivatives. It was also noticed that the exocyclic double bond of xanthatin is crucial for its larvicidal activity. This work also provides some important hints for further design, synthesis, and structural modification of the xanthanolides sesquiterpene lactones toward development of the new environmentally friendly pesticides for sustainable agricultural production.

Diagnostic accuracy of LAMP assay for HBV infection.

BACKGROUND: Detection of hepatitis B virus (HBV) is vital for the diagnosis of hepatitis B infection. A novel test loop-mediated isothermal amplification (LAMP) has been successfully applied to detect various pathogens. However, the accuracy of LAMP in diagnosing HBV remains unclear. Therefore, in the present study, the accuracy of LAMP for HBV detection was evaluated systematically. METHODS: Embase, Cochrane Library, and PubMed databases were searched for studies using LAMP to detect HBV. Then, two researchers extracted data and assessed the quality of literature using the QUADAS-2 tool independently. I2 statistic and chi-square test were analyzed to investigate the heterogeneity, and Deek's funnel plot assessed the publication bias. The pooled sensitivity (SEN), specificity (SPE), positive LR (PLR), negative LR (NLR), diagnostic odds ratio (DOR), and 95% confidence intervals were displayed in forest plots. We calculated the area under the curve (AUC) to assess the overall efficiency of LAMP for HBV detection. RESULTS: A total of nine studies with 1298 samples were finally included in this evaluation. The pooled sensitivity and specificity of HBV detection were 0.91 (95% CI: 0.89 ~ 0.92) and 0.97 (95% CI: 0.94 ~ 0.99), respectively. The PLR, NLR, and DOR were 16.93 (95% CI: 6.15 ~ 46.55), 0.08 (95% CI: 0.05 ~ 0.14), and 397.57 (95% CI: 145.41 ~ 1087.07). Besides, the AUC was 0.9872, and Deek's plot suggested that there existed publication bias in the studies. CONCLUSION: Compared with PCR, LAMP is a simple, rapid, and effective assay to diagnose HBV. However, additional evidence is essential to confirm that LAMP can replace other methods in diagnosing HBV infection.

Nursing care for infants after enterostomy: Experience with 483 cases over a 5-year period.

AIM: To explore and improve nursing care for infants after enterostomy. METHODS: A total of 483 infants who underwent enterostomy from January 2014 to January 2019 were enrolled in this study. RESULTS: During hospitalization and follow-up, there were 30 infants with peripheral skin complications, including 15 cases of allergic dermatitis, 13 cases of faecal dermatitis and two cases of avulsion injury. CONCLUSION: Without proper and effective nursing care, the peripheral skin complications of enterostomy-related can easily develop. Therefore, careful postoperative care and effective family follow-up and guidance are essential after discharge, and using WeChat to follow-up can provide timely and effective follow-up and guidance to patients. IMPLICATIONS FOR NURSING MANAGEMENT: This study summarizes the experience of nursing care for infants over a 5-year period. Nurses must provide sound care for infants after enterostomy, timely and effectively address complications, guide nursing care performed by family members and strengthen follow-up through the WeChat online support group to reduce the occurrence of complications.

[Retraction Note: Association of Gene Polymorphisms in Wnt Signal Pathway with Tuberculosis in Chinese Tibetan Population.2016,47(6):920-925.]

This corrects the article DOI: 10.13464/j.scuxbyxb.2016.06.021.

[Relationship Between the VNTR Loci Polymorphism and MALDI-TOF MS Protein Profile Diversity in Mycobacterium tuberculosis Complex].

OBJECTIVE: To study the relationship between the copy numbers of repetitive units at variable number tandem repeat (VNTR) loci of Mycobacterium tuberculosis complex (MTBC) with its diversity of protein profiles. METHODS: The MTBC strains were subjected to genotyping using multiple locus variable number tandem repeat analysis (MLVA). Also, the principal component analysis (PCA) was performed for bacterial protein profiles of MTBC using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The relationship between the polymorphism of VNTR loci and PCA clustering was analyzed. RESULTS: A total of 157 MTBC strains were collected. 146 MTBC strains (MS identification score values ≥1.700) were performed PCA and three clusters, clusterⅠ(61 strains), clusterⅡ(26 strains) and cluster Ⅲ(59 strains), were generated. Polymorphic diversities were observed in 24 VNTR loci, among them, 7 were highly various, 7 were moderately, and 10 were low various. The polymorphism of Mtub39, QUB26 and QUB4156 loci were correlated with the results of MALDI-TOF MS clustering (P=0.000, P=0.035, P=0.017). CONCLUSION: The polymorphism of Mtub39, QUB26 and QUB4156 loci in MTBC was correlated with the difference of MALDI-TOF MS protein profiles, suggesting that these loci may play a role in regulating the composition of protein profiles of MTBC strains.

[Methylation Chip Screening and Verification of Differential Genes Related to Tuberculosis Infection].

OBJECTIVE: To screen the genes with significant changes in DNA methylation level in active tuberculosis patients, we used the methylation chips and expanded the sample size to verify candidate genes. METHODS: ① This study enrolled 9 cases of active tuberculosis patients, 3 cases of latent tuberculosis patients and 3 cases of healthy controls whose age and gender were all matched. Genome DNA was extracted from peripheral blood mononuclear cell in blood samples collected from these candidates, and bisulfite conversion treatment was then conducted. After hybridization with the Illumina HD 450K Infinium Mehtylation BeadChip, the results were compared between patients group and control group, and GO and KEGG pathway analyses were performed to evaluate the function of differentially expressed genes. ② We further enrolled 60 cases of active tuberculosis patients and 60 cases of health controls (age-and gender-matched), DNA was extracted from their peripheral blood and also followed bisulfite conversion treatment. Pyrosequencing method was used to detect the methylation levels of candidate genes (IFNGR2, PTPN6, CRK1, ATP6V0B, WIF1, DKK1 and SFRP1) screened by gene chip. RESULTS: Compared with healthy controls, the fragments in the patients that showed low methylation change accounted for the vast majority. Most of the methylation differential fragments (DMRs) were located in the main body region, followed by the upstream region of transcription initiation site, and the lowest DMRs distribution area was 3´UTR area. GO and Pathway analysis showed that the functions of the differentially methylated regions related genes are mainly enriched in the biological processes of the regulation of leukocyte differentiation, apoptosis, cytokine regulation and inflammatory response which are closely related to tuberculosis. There were 32 CpG sites involved in the verified 7 tuberculosis related genes, and 16 CpG locus showed significant difference (P<0.05), they were distributed in 6 genes: PTPN6, WIF1, CRK1, SFRP1, DKK1 and IFNGR2.Of these genes with significant difference, PTPN6 genes showed hypermethylation status and WIF1, CRK1, SFRP1, DKK1 and IFNGR2 genes exhibited demethylation status in the patients group compared to the health controls. SFRP1 and CRK-1 mRNA up-regulated in the patients group compared with health controls. CONCLUSION: In the course of MTB infection, the methylation status of genomic DNA is altered, and most of the differentially methylated regions (DMRs) are showed status of demethylation. The expressions ofSFRP1and CRK-1gene up-regulate in tuberculosis infection.

The changes of immunoglobulin G N-glycosylation in blood lipids and dyslipidaemia.

BACKGROUND: Alternative N-glycosylation has significant structural and functional consequences on immunoglobulin G (IgG) and can affect immune responses, acting as a switch between pro- and anti-inflammatory IgG functionality. Studies have demonstrated that IgG N-glycosylation is associated with ageing, body mass index, type 2 diabetes and hypertension. METHODS: Herein, we have demonstrated patterns of IgG glycosylation that are associated with blood lipids in a cross-sectional study including 598 Han Chinese aged 20-68 years. The IgG glycome composition was analysed by ultra-performance liquid chromatography. RESULTS: Blood lipids were positively correlated with glycan peak GP6, whereas they were negatively correlated with GP18 (P < 0.05/57). The canonical correlation analysis indicated that initial N-glycan structures, including GP4, GP6, GP9-12, GP14, GP17, GP18 and GP23, were significantly correlated with blood lipids, including total cholesterol, total triglycerides (TG) and low-density lipoprotein (r = 0.390, P < 0.001). IgG glycans patterns were able to distinguish patients with dyslipidaemia from the controls, with an area under the curve of 0.692 (95% confidence interval 0.644-0.740). CONCLUSIONS: Our findings indicated that a possible association between blood lipids and the observed loss of galactose and sialic acid, as well as the addition of bisecting GlcNAcs, which might be related to the chronic inflammation accompanying with the development and procession of dyslipidaemia.

[Electrophysiological identification of human induced pluripotent stem cell-derived cardiomyocytes].

The present study was aimed to characterize the electrophysiology of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). IMR90-4 cells were induced to differentiate into cardiomyocytes by temporal modulation of regulators of canonical Wnt signaling. The protein expression of cardiac troponin T (cTnT) was detected by immunofluorescence staining and flow cytometry, and the differentiation rate of hiPSC-CMs was calculated. The action potentials (APs) of hiPSC-CMs were recorded by patch clamp and used to classify different types of cardiomyocytes. The electrophysiological characteristics of hiPSC-CMs were further analyzed. The results showed that the cTnT positive rate of hiPSC-CMs was above 95%. hiPSC-CMs were differentiated into 3 types of cardiomyocytes based on the properties of AP: ventricular-, atrial- and nodal-like cells. In comparison with the other two types of cells, the APs of ventricular-like cells exhibited longer duration, higher amplitude and higher dV/dtmax. The nodal-like cells had the lowest dV/dtmax among all the three types. These results indicate that hiPSC can be differentiated into the cardiomyocytes with high purity and the differentiated hiPSC-CMs have similar electrophysiological characteristics to adult cardiomyocytes.

[Triton X-100 Enhanced the Detection of Hodge Test and Carba NP Test for Carbapenemase-producing Acinetobacter baumannii Complex].

OBJECTIVE: To find out highly effective phenotypic methods to detect carbapenemase-producing Acinetobacter baumannii (A. baumannii complex) so as to support the epidemiological investigation and clinical application. METHODS: We included 113 A. baumannii complex and compared the detection performance of modified Hodge test, Carba NP test, Triton Hodge test, and the simplified Carba NP-direct test with Tritont X-100. RESULTS: We tested 83 carbapenemase-producing A. baumannii complex and 30 non-carbapenemase producers. The sensitivity and specificity of Hodge test were significantly higher than those of Carba NP test (71.1% versus 35.0%, 100% versus 86.7%, P<0.05, respectively). The sensitivity of Triton Hodge test and Carba NP-direct test was respectively significantly higher than Hodge test and Carba NP test (98.8% versus 71.1%, 85.5% versus 35.0%, P<0.001, respectively ). However, the specificities were comparable (P>0.05). The positive additive effects of the two methods with Triton X-100 were more obvious than those of the methods without Triton X-100 (P<0.001). CONCLUSION: Triton X-100 could increase the sensitivity and positive additive effect on phenotypic detection of A. baumannii complex. Triton Hodge test and Carba NP-direct test were more applicable for clinical routine procedure.

MucR Is Required for Transcriptional Activation of Conserved Ion Transporters to Support Nitrogen Fixation of Sinorhizobium fredii in Soybean Nodules.

To achieve effective symbiosis with legume, rhizobia should fine-tune their background regulation network in addition to activating key genes involved in nodulation (nod) and nitrogen fixation (nif). Here, we report that an ancestral zinc finger regulator, MucR1, other than its paralog, MucR2, carrying a frameshift mutation, is essential for supporting nitrogen fixation of Sinorhizobium fredii CCBAU45436 within soybean nodules. In contrast to the chromosomal mucR1, mucR2 is located on symbiosis plasmid, indicating its horizontal transfer potential. A MucR2 homolog lacking the frameshift mutation, such as the one from S. fredii NGR234, can complement phenotypic defects of the mucR1 mutant of CCBAU45436. RNA-seq analysis revealed that the MucR1 regulon of CCBAU45436 within nodules exhibits significant difference compared with that of free-living cells. MucR1 is required for active expression of transporters for phosphate, zinc, and elements essential for nitrogenase activity (iron, molybdenum, and sulfur) in nodules but is dispensable for transcription of key genes (nif/fix) involved in nitrogen fixation. Further reverse genetics suggests that S. fredii uses high-affinity transporters to meet the demand for zinc and phosphate within nodules. These findings, together with the horizontal transfer potential of the mucR homolog, imply an intriguing evolutionary role of this ancestral regulator in supporting nitrogen fixation.

Construction and pilot screening of a signature-tagged mutant library of Sinorhizobium fredii.

Sinorhizobium fredii is well known for its ability to establish symbiosis with diverse legumes such as Glycine max (soybean, determinate nodules) and Cajanus cajan (pigeon pea, indeterminate nodules). In order to make screening of S. fredii genes related to symbiosis cost-effective, we constructed a large Tn5 insertion mutant library of S. fredii CCBAU45436 using the signature-tagged mutagenesis (STM) technique. This STM library contains a total of 25,500 independent mutants distributed in 17 sublibraries tagged by corresponding distinct DNA bar-code sequences. After the pilot screening of 255 mutants in 15 batches, Tag85-4, Tag4-17, Tag4-11 and Tag10-13 were found to have attenuated competitiveness (0-30 % in nodule occupation) compared to the wild-type strain when inoculated on soybean. Further characterization of these mutants suggests that Tag4-11 (a pyrC mutant) and Tag10-13 (a nrdJ mutant) are defective in establishing symbiosis with soybean. The pyrC mutant induced uninfected pseudonodules while the nrdJ mutant formed significantly more nodules containing bacteroids with poor persistence ability. When these two mutants were tested on pigeon pea, host-specific symbiotic defects were found. These results demonstrated the STM library as a valuable resource for identifying S. fredii genes relevant to symbiosis.

First-principles study of photovoltaics and carrier mobility for non-toxic halide perovskite CH3NH3SnCl3: theoretical prediction.

Promising candidates in this respect are organometal perovskites ABX3, which have been intensely investigated during the last years. In this paper, we calculate the crystal structures, optical properties and carrier mobility for three phases of non-toxic perovskite halide CH3NH3SnCl3 by applying density functional theory with the nonlocal van der Waals (vdW) correlation. The results show that CH3NH3SnCl3 has superior performance in terms of its optical absorption coefficient, which reaches as high as 10(5) cm(-1) and has proven itself to be a perfect solar light harvester. Most importantly, the results of intrinsic carrier mobility of CH3NH3SnCl3 show that the electron mobility of the triclinic phase can achieve a large magnitude of 1700 cm(2) V(-1) s(-1), which is mainly due to the small effective mass. We ascribe the superior photoelectric property to the ferroelectricity, which may be caused by the distorted octahedral SnCl6(-).

Tuning the Schottky contacts in the phosphorene and graphene heterostructure by applying strain.

The structures and electronic properties of the phosphorene and graphene heterostructure are investigated by density functional calculations using the hybrid Heyd-Scuseria-Ernzerhof (HSE) functional. The results show that the intrinsic properties of phosphorene and graphene are preserved due to the weak van der Waals contact. But the electronic properties of the Schottky contacts in the phosphorene and graphene heterostructure can be tuned from p-type to n-type by the in-plane compressive strains from -2% to -4%. After analyzing the total band structure and density of states of P atom orbitals, we find that the Schottky barrier height (SBH) is determined by the P-pz orbitals. What is more, the variation of the work function of the phosphorene monolayer and the graphene electrode and the Fermi level shift are the nature of the transition of Schottky barrier from n-type Schottky contact to p-type Schottky contact in the phosphorene and graphene heterostructure under different in-plane strains. We speculate that these are general results of tuning of the electronic properties of the Schottky contacts in the phosphorene and graphene heterostructure by controlling the in-plane compressive strains to obtain a promising method to design and fabricate a phosphorene-graphene based field effect transistor.