Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 50
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Artigo em Inglês | MEDLINE | ID: mdl-32519252

RESUMO

Allitol is a kind of rare sugar alcohol with potential application value. An engineered strain, which simultaneously expressed D-psicose-3-epimerase (DPE), ribitol dehydrogenase (RDH), and formate dehydrogenase (FDH) three enzymes, was constructed by cloning above three genes into one plasmid and transformed into the host E. coli strain, and used as the whole-cell catalysts for biotransformation of allitol from the low-cost substrate of D-fructose. The whole cell allitol biotransformation conditions were optimized. The medium, recombinant gene induction conditions, and the substrate feeding rate for cultivation of the catalytic cells were optimized. Then, the fed-batch culture was made and scaled up to 10 L fermentor. Finally, 63.44 g/L allitol was obtained from 100 g/L D-fructose after 3 h of biotransformation, and the allitol crystals of 99.9% purity were obtained by using cooling recrystallization. The allitol production method developed in this research has high product purity, and is highly efficient, easily scaled up, and suitable for large-scale production of highly purified allitol.

2.
Curr Microbiol ; 2020 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-32556477

RESUMO

A strain SDU10 was isolated from swine manure compost and identified as Pseudomonas stutzeri SDU10. It demonstrated excellent capability in NH4+-N removal. Optimal conditions of NH4+-N removal were determined, which were sodium acetate as the optimal carbon source, carbon to nitrogen (C/N) ratio of 10, temperature of 30 °C, pH of 7.0. Especially, P. stutzeri SDU10 could remove high concentration NH4+-N of 1500.0 and 2000.0 mg/l in 120 h with the NH4+-N removal rates of 91.1% and 61.6%, respectively. In batch experiments, the highest NH4+-N removal rate of 97.6% and chemical oxygen demand (COD) removal rate of 94.2% were obtained at initial C/N ratio 10 during piggery wastewater treatment using P. stutzeri SDU10. Results showed that P. stutzeri SDU10 had the potential for treatment of wastewater of high NH4+-N concentration.

3.
Biotechnol Lett ; 2020 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-32451803

RESUMO

OBJECTIVE: To develop a method combining enzymatic catalysis and resting-cell biotransformation to produce allitol from low cost substrate D-glucose. RESULTS: The recombinant E. coli expressing D-psicose-3-epimerase (DPE), ribitol dehydrogenase (RDH) and formate dehydrogenase (FDH) for allitol production from D-fructose was constructed. The optimizations of the cell catalytic conditions and the cell cultivation conditions were made. Then, 63.4 g allitol L-1 was obtained from 100 g D-fructose L-1 in 4 h catalyzed by the recombinant E. coli cells. In order to decrease the substrate cost, D-glucose was used as the substrate instead of D-fructose and immobilized glucose isomerase was used to convert D-glucose into D-fructose. In order to simplify allitol production process from D-glucose, one-pot reaction using the mixed catalysts was used and the reaction conditions were optimized. Finally, 12.7 g allitol L-1 was obtained from 50 g D-glucose L-1 catalyzed by the mixed catalysts of immobilized glucose isomerase and the recombinant E. coli cells. CONCLUSIONS: Allitol can be efficiently produced from low cost substrate D-glucose by using the method combining enzymatic catalysis and resting-cell biotransformation, which is the first report.

4.
Appl Environ Microbiol ; 86(11)2020 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-32245756

RESUMO

Acidophiles play a dominant role in driving elemental cycling in natural acid mine drainage (AMD) habitats and exhibit important application value in bioleaching and bioremediation. Acidity is an inevitable environmental stress and a key factor that affects the survival of acidophiles in their acidified natural habitats; however, the regulatory strategies applied by acidophilic bacteria to withstand low pH are unclear. We identified the significance of the ferric uptake regulator (Fur) in acidophiles adapting to acidic environments and discovered that Fur is ubiquitous as well as highly conserved in acidophilic bacteria. Mutagenesis of the fur gene of Acidithiobacillus caldus, a prototypical acidophilic sulfur-oxidizing bacterium found in AMD, revealed that Fur is required for the acid resistance of this acidophilic bacterium. Phenotypic characterization, transcriptome sequencing (RNA-seq), mutagenesis, and biochemical assays indicated that the Acidithiobacillus caldus ferric uptake regulator (AcFur) is involved in extreme acid resistance by regulating the expression of several key genes of certain cellular activities, such as iron transport, biofilm formation, sulfur metabolism, chemotaxis, and flagellar biosynthesis. Finally, a Fur-dependent acid resistance regulatory strategy in A. caldus was proposed to illustrate the ecological behavior of acidophilic bacteria under low pH. This study provides new insights into the adaptation strategies of acidophiles to AMD ecosystems and will promote the design and development of engineered biological systems for the environmental adaptation of acidophiles.IMPORTANCE This study advances our understanding of the acid tolerance mechanism of A. caldus, identifies the key fur gene responsible for acid resistance, and elucidates the correlation between fur and acid resistance, thus contributing to an understanding of the ecological behavior of acidophilic bacteria. These findings provide new insights into the acid resistance process in Acidithiobacillus species, thereby promoting the study of the environmental adaptation of acidophilic bacteria and the design of engineered biological systems.

5.
J Pineal Res ; : e12660, 2020 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-32323368

RESUMO

Choroidal neovascularization (CNV) is an important characteristic of advanced wet age-related macular degeneration (AMD) and leads to severe visual impairment among elderly patients. Previous studies have demonstrated that melatonin induces several biological effects related to antioxidation, anti-inflammation, and anti-angiogenesis. However, the role of melatonin in CNV, and its underlying mechanisms, has not been investigated thus far. In this study, we found that melatonin administration significantly reduced the scale and volume of CNV lesions, suppressed vascular leakage, and inhibited the capacity of vascular proliferation in the laser-induced mouse CNV model. Additionally, the results also show that the melatonin-treated retinal microglia in the laser-induced mice exhibited enhanced expression of M1-type markers, such as iNOS, CCL-3, CCL-5, and TNF-α, as well as decreased production of M2-type markers, such as Arg-1, Fizz-1, IL-10, YM-1, and CD206, indicating that melatonin switched the macrophage/microglia polarization from pro-angiogenic M2 phenotype to anti-angiogenic M1 phenotype. Furthermore, the RhoA/ROCK signaling pathway was activated during CNV formation, yet was suppressed after an intraperitoneal injection of melatonin. In conclusion, melatonin attenuated CNV, reduced vascular leakage, and inhibited vascular proliferation by switching the macrophage/microglia polarization from M2 phenotype to M1 phenotype via inhibition of RhoA/ROCK signaling pathway in CNV. This suggests that melatonin could be a novel agent for the treatment of AMD.

6.
BMJ Open ; 10(3): e030434, 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-32169922

RESUMO

OBJECTIVES: The aim of our study is to give insight into congenital ectopia lentis (CEL) patients' care-seeking behaviour and explore the factors affecting their follow-up visits. DESIGN: Cross-sectional study; in-depth and face-to-face semistructured interview. SETTING: A large-scale ophthalmology hospital in China. PARTICIPANTS: 35 patients with CEL and their parents from May 2017 to August 2017. MAIN OUTCOME MEASURES: Themes and categories. The interviews were audio-recorded, transcribed verbatim, coded and analysed using grounded theory. Data collection was closed when new themes did not emerge in subsequent dialogues. RESULTS: The factors affecting the timely visits included insufficient awareness of CEL, shame on hereditary disease, lack of effective doctor-patient communication, lack of reliable information online and daily stressors. CONCLUSION: Continuing medical education of severe and rare disease, reforming the pattern of medical education, constructing an interactive platform of the disease on the internet and improving healthcare policy are effective ways to improve the diagnosis and treatment status of CEL in China.

7.
Artigo em Inglês | MEDLINE | ID: mdl-32209989

RESUMO

Chromium contamination has been an increasing threat to the environment and to human health. Cr(VI) and Cr(III) are the most common states of chromium. However, compared with Cr(III), Cr(VI) is more toxic and more easily absorbed, therefore, it is more harmful to human beings. Thus, the conversion of toxic Cr(VI) into Cr(III) is an accepted strategy for chromium detoxification. Here, we isolated two Bacillus cereus strains with a high chromium tolerance and reduction ability, named B. cereus D and 332, respectively. Both strains demonstrated a strong pH and temperature adaptability and survival under 8 mM Cr(VI). B. cereus D achieved 87.8% Cr(VI) removal in 24 h with an initial 2 mM Cr(VI). Cu(II) was found to increase the removal rate of Cr(VI) significantly. With the addition of 0.4 mM Cu(II), 99.9% of Cr(VI) in the culture was removed by B. cereus 332 in 24 h. This is the highest removal efficiency in the literature that we have seen to date. The immobilization experiments found that sodium alginate with diatomite was the better method for immobilization and B. cereus 332 was more efficient in immobilized cells. Our research provided valuable information and new, highly effective strains for the bioremediation of chromium pollution.

8.
Bioprocess Biosyst Eng ; 43(4): 645-653, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31797048

RESUMO

D-Allose is a rare sugar, can be used as an ingredient in a range of foods and dietary supplements, has alimentary activities, especially excellent anti-cancer effects and used in assisting cancer chemotherapy and radiotherapy, etc. To develop a simple and low-cost process for D-allose production, a one-pot enzymatic process using the substrate of D-fructose, and the recombinant enzymes of D-psicose 3-epimerase (DPE) and L-rhamnose isomerase (L-RhI) was developed. These enzymes were cloned from Ruminococcus sp. and B. subtilis, respectively, successfully expressed in E. coli, extracted and immobilized using anion exchange resin and amino resin, respectively. The mass ratio of D-fructose, D-psicose and D-allose was 6.6:2.4:1.0 when the reaction reached equilibrium after 5 h of reaction. Using the low-cost substrate of D-fructose, the reusable immobilized enzymes and the one-pot reaction, the production process is simplified and the production cost is decreased. In addition, to simplify the enzyme extraction and immobilization processes, new methods for enzyme capture and immobilization were developed especially for DPE immobilization. This is the first report for one-pot D-allose production using immobilized L-RhI and DPE.

9.
Mol Med Rep ; 20(1): 559-566, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31180551

RESUMO

It is well known that transforming growth factor ß (TGFß), which is able to stimulate multiple intracellular signaling pathways, exerts an important role in Marfan syndrome, although the effects of TGFß on congenital ectopia lentis (CEL) have yet to be fully elucidated. In the present study, the expression levels of TGFß and matrix metalloproteinases (MMPs) were investigated in the aqueous humor of patients with ectopic lentis who differed in terms of the severity of the disease. A total of 17 CEL patients with 21 eyes (aged 12.76±9.37 years) and 12 congenital cataract (CC) patients with 17 eyes (aged 6.82±9.18 years) were randomized in the present study. The levels of active TGFß and MMPs in the aqueous humor were analyzed with Luminex xMAP® technology by using commercially available Bio­Plex Pro™ Human MMP and TGFß assays. The distance from the lens edge to the pupil edge and the white to white corneal diameter (i.e. the horizontal distance between the borders of the corneal limbus) were measured, and the ratio was calculated as the degree of lens dislocation. The association between TGFß and MMP levels and the degree of lens dislocation was analyzed using Spearman's correlation test. Compared with the patients with CC, the level of TGFß2 in the patients with CEL was increased significantly. Specifically, the level of TGFß2 in the CEL patients was 855.19 pg/ml (744.33, 1,009.24), whereas it was 557.08 (438.24, 692.71) pg/ml in the CC patients (P<0.001). In addition, it was noted that the levels of MMP­2 and ­10 in the aqueous humor of the patients with CEL were higher compared with those in the CC patients, although this increase did not reach the level of statistical significance. Notably, the levels of MMP­8 and ­9 in the aqueous humor of patients with CEL were significantly lower compared with those in the CC patients (P=0.014 and P=0.002, respectively). Furthermore, a marginal correlation was identified between the severity of ectopic lentis and the levels of TGFß2 in the aqueous humor (r2=0.379; P=0.003) of the patients with CEL. Taken together, these results demonstrated that a significant correlation existed between high levels of aqueous humor TGFß2 and the severity of ectopia lentis in patients with CEL. In addition, aqueous humor TGFß2 levels in the CEL patients were significantly higher compared with those in CC patients.


Assuntos
Humor Aquoso/química , Ectopia do Cristalino/patologia , Metaloproteinases da Matriz/análise , Fator de Crescimento Transformador beta2/análise , Adolescente , Adulto , Catarata/congênito , Catarata/patologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Fator de Crescimento Transformador beta/análise , Adulto Jovem
10.
Front Microbiol ; 10: 1130, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31178842

RESUMO

Acidithiobacillaceae, an important family of acidophilic and chemoautotrophic sulfur or iron oxidizers, participate in geobiochemical circulation of the elements and drive the release of heavy metals in mining associated habitats. Because of their environmental adaptability and energy metabolic systems, Acidithiobacillus spp. have become the dominant bacteria used in bioleaching for heavy metal recovery. Flagella-driven motility is associated with bacterial chemotaxis and bacterial responses to environmental stimuli. However, little is known about how the flagellum of Acidithiobacillus spp. is regulated and how the flagellum affects the growth of these chemoautotrophic bacteria. In this study, we analyzed the flagellar gene clusters in Acidithiobacillus strains and uncovered the close relationship between flagella and the sulfur-oxidizing systems (Sox system). The σ28 gene (rpoF) knockout and overexpression strains of Acidithiobacillus caldus were constructed. Scanning electron microscopy shows that A. caldus ΔrpoF cells lacked flagella, indicating the essential role of RpoF in regulating flagella synthesis in these chemoautotrophic bacteria. Motility analysis suggests that the deletion of rpoF resulted in the reduction of swarming capability, while this capability was enhanced in the rpoF overexpression strain. Both static cultivation and low concentration of energy substrates (elemental sulfur or tetrathionate) led to weak growth of A. caldus ΔrpoF cells. The deletion of rpoF promoted bacterial attachment to the surface of elemental sulfur in static cultivation. The absence of RpoF caused an obvious change in transcription profile, including genes in flagellar cluster and those involved in biofilm formation. These results provide an understanding on the regulation of flagellar hierarchy and the flagellar function in these sulfur or iron oxidizers.

11.
Front Neurosci ; 12: 856, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30555289

RESUMO

Information in the central nervous system (CNS) is conducted via electrical signals known as action potentials and is encoded in time. Several neurological disorders including depression, Attention Deficit Hyperactivity Disorder (ADHD), originate in faulty brain signaling frequencies. Here, we present a Hodgkin-Huxley model analog for a strongly correlated VO2 artificial neuron system that undergoes an electrically-driven insulator-metal transition. We demonstrate that tuning of the insulating phase resistance in VO2 threshold switch circuits can enable direct mimicry of neuronal origins of disorders in the CNS. The results introduce use of circuits based on quantum materials as complementary to model animal studies for neuroscience, especially when precise measurements of local electrical properties or competing parallel paths for conduction in complex neural circuits can be a challenge to identify onset of breakdown or diagnose early symptoms of disease.

12.
Int J Ophthalmol ; 11(9): 1545-1549, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30225232

RESUMO

AIM: To elucidate the trends and characteristics of congenital ectopia lentis (CEL) in southern China. METHODS: CEL patients from China admitted to Zhongshan Ophthalmic Center (ZOC) from January 2006 to December 2015 were recruited in our study. Residence, gender, hospitalization time, age at surgery, and the presence of other ocular abnormalities and system disease were statistically analyzed in different subgroups. RESULTS: Four hundred and thirty-seven hospitalizations (306 in-patients) diagnosed with CEL from a total of 283 308 hospitalizations were identified, which accounted for 0.15% of the total in-patients. Of the identified CEL in-patients, the total ratio of boys to girls was 2.22:1. Based on a subgroup analysis according to age, patients aged 12-18 years old constituted the highest proportion (31.70%) of all hospitalized CEL patients, and those 0-3 year old constituted the lowest proportion (8.82%) of the total number. The number of CEL increased from 18 to 72 and the hospital based prevalence increased from 8.60% to 18.10% from 2006 to 2015, and the average age at surgery decreased from 9 years old in 2006 to 7.6 years old in 2015. CONCLUSION: The results reveal upward trends in both the number of CEL hospitalizations and hospital based prevalence of CEL in this 10-year study period, but a reduction in the age at surgery, which may reflect the increase of public awareness of children's eye care in China.

13.
Curr Eye Res ; 43(8): 972-976, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29698085

RESUMO

PURPOSE: This study aims to describe the characteristics of corneal astigmatism before surgery in congenital ectopia lentis (CEL) patients. METHODS: This retrospective study reviewed 306 CEL patients from 1st January 2006 to 31st December 2015. One eye was randomly selected from each patient when the patient had bilateral EL. The influence of sex, laterality, and Marfan syndrome on corneal astigmatism in different age subgroups was evaluated and compared. The correlation between age and corneal astigmatism was evaluated. RESULTS: Two hundred fifty-two eyes were included in this study. The mean corneal astigmatism of CEL patients was 2.00 ± 1.28 D. There was a statistical difference in corneal astigmatism between CEL eyes with and without Marfan syndrome. However, no statistical difference was found between male and female patients, or between the EL-affected eye and the unaffected eye in monocular EL patients. There was a positive correlation between age and corneal astigmatism in CEL eyes. CONCLUSIONS: This study suggests that CEL patients' corneal astigmatism is higher in patients with Marfan syndrome, and corneal astigmatism of the CEL eye increases with age. Our results are useful for surgeons to make appropriate incision and intraocular lens (IOL) choices for patients, as well as a useful reference for designs of new IOLs.


Assuntos
Astigmatismo/diagnóstico , Córnea/diagnóstico por imagem , Ectopia do Cristalino/complicações , Procedimentos Cirúrgicos Oftalmológicos , Refração Ocular/fisiologia , Acuidade Visual , Adolescente , Astigmatismo/epidemiologia , Astigmatismo/etiologia , Criança , Pré-Escolar , China/epidemiologia , Ectopia do Cristalino/diagnóstico , Ectopia do Cristalino/cirurgia , Feminino , Seguimentos , Humanos , Interferometria/métodos , Masculino , Período Pré-Operatório , Prevalência , Estudos Retrospectivos , Adulto Jovem
14.
Nanoscale ; 10(20): 9441-9449, 2018 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-29663006

RESUMO

Large banks of cheap, fast, non-volatile, energy efficient, scalable solid-state memories are an increasingly essential component for today's data intensive computing. Conductive-bridge random access memory (CBRAM) - which involves voltage driven formation and dissolution of Cu or Ag filaments in a Cu (or Ag) anode/dielectric (HfO2 or Al2O3)/inert cathode device - possesses the necessary attributes to fit the requirements. Cu and Ag are, however, fast diffusers and known contaminants in silicon microelectronics. Herein, employing a criterion for electrode metal selection applicable to cationic filamentary devices and using first principles calculations for estimating diffusion barriers in HfO2, we identify tin (Sn) as a rational, silicon CMOS compatible replacement for Cu and Ag anodes in CBRAM devices. We then experimentally fabricate Sn based CBRAM devices and demonstrate very fast, steep-slope memory switching as well as threshold switching, comparable to Cu or Ag based devices. Furthermore, time evolution of the cationic filament formation along with the switching mechanism is discussed based on time domain measurements (I vs. t) carried out under constant voltage stress. The time to threshold is shown to be a function of both the voltage stress (Vstress) as well as the initial leakage current (I0) through the device.

15.
Biotechnol Lett ; 40(4): 649-657, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29349627

RESUMO

OBJECTIVES: Production of gluconic acid by using immobilized enzyme and continuous stirred tank reactor-plug flow tubular reactor (CSTR-PFTR) circulation reaction system. RESULTS: A production system is constructed for gluconic acid production, which consists of a continuous stirred tank reactor (CSTR) for pH control and liquid storage and a plug flow tubular reactor (PFTR) filled with immobilized glucose oxidase (GOD) for gluconic acid production. Mathematical model is developed for this production system and simulation is made for the enzymatic reaction process. The pH inhibition effect on GOD is modeled by using a bell-type curve. CONCLUSIONS: Gluconic acid can be efficiently produced by using the reaction system and the mathematical model developed for this system can simulate and predict the process well.


Assuntos
Reatores Biológicos , Enzimas Imobilizadas/química , Gluconatos/metabolismo , Glucose Oxidase/química , Enzimas Imobilizadas/genética , Gluconatos/síntese química , Glucose Oxidase/genética , Concentração de Íons de Hidrogênio , Modelos Teóricos
16.
Front Microbiol ; 9: 3290, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30687275

RESUMO

Sulfur oxidation is an essential component of the earth's sulfur cycle. Acidithiobacillus spp. can oxidize various reduced inorganic sulfur compounds (RISCs) with high efficiency to obtain electrons for their autotrophic growth. Strains in this genus have been widely applied in bioleaching and biological desulfurization. Diverse sulfur-metabolic pathways and corresponding regulatory systems have been discovered in these acidophilic sulfur-oxidizing bacteria. The sulfur-metabolic enzymes in Acidithiobacillus spp. can be categorized as elemental sulfur oxidation enzymes (sulfur dioxygenase, sulfur oxygenase reductase, and Hdr-like complex), enzymes in thiosulfate oxidation pathways (tetrathionate intermediate thiosulfate oxidation (S4I) pathway, the sulfur oxidizing enzyme (Sox) system and thiosulfate dehydrogenase), sulfide oxidation enzymes (sulfide:quinone oxidoreductase) and sulfite oxidation pathways/enzymes. The two-component systems (TCSs) are the typical regulation elements for periplasmic thiosulfate metabolism in these autotrophic sulfur-oxidizing bacteria. Examples are RsrS/RsrR responsible for S4I pathway regulation and TspS/TspR for Sox system regulation. The proposal of sulfur metabolic and regulatory models provide new insights and overall understanding of the sulfur-metabolic processes in Acidithiobacillus spp. The future research directions and existing barriers in the bacterial sulfur metabolism are also emphasized here and the breakthroughs in these areas will accelerate the research on the sulfur oxidation in Acidithiobacillus spp. and other sulfur oxidizers.

17.
PLoS One ; 12(9): e0183668, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28873420

RESUMO

Acidithiobacillus caldus is a chemolithoautotrophic sulfur-oxidizing bacterium that is widely used for bioleaching processes. Acidithiobacillus spp. are suggested to contain sulfur dioxygenases (SDOs) that facilitate sulfur oxidation. In this study, two putative sdo genes (A5904_0421 and A5904_1112) were detected in the genome of A. caldus MTH-04 by BLASTP searching with the previously identified SDO (A5904_0790). We cloned and expressed these genes, and detected the SDO activity of recombinant protein A5904_0421 by a GSH-dependent in vitro assay. Phylogenetic analysis indicated that A5904_0421and its homologous SDOs, mainly found in autotrophic bacteria, were distantly related to known SDOs and were categorized as a new subgroup of SDOs. The potential functions of genes A5904_0421 (termed sdo1) and A5904_0790 (termed sdo2) were investigated by generating three knockout mutants (Δsdo1, Δsdo2 and Δsdo1&2), two sdo overexpression strains (OE-sdo1 and OE-sdo2) and two sdo complemented strains (Δsdo1/sdo1' and Δsdo2/sdo2') of A. caldus MTH-04. Deletion or overexpression of the sdo genes did not obviously affect growth of the bacteria on S0, indicating that the SDOs did not play an essential role in the oxidation of extracellular elemental sulfur in A. caldus. The deletion of sdo1 resulted in complete inhibition of growth on tetrathionate, slight inhibition of growth on thiosulfate and increased GSH-dependent sulfur oxidation activity on S0. Transcriptional analysis revealed a strong correlation between sdo1 and the tetrathionate intermediate pathway. The deletion of sdo2 promoted bacterial growth on tetrathionate and thiosulfate, and overexpression of sdo2 altered gene expression patterns of sulfide:quinone oxidoreductase and rhodanese. Taken together, the results suggest that sdo1 is essential for the survival of A. caldus when tetrathionate is used as the sole energy resource, and sdo2 may also play a role in sulfur metabolism.


Assuntos
Acidithiobacillus/enzimologia , Dioxigenases/metabolismo , Redes e Vias Metabólicas , Enxofre/metabolismo , Acidithiobacillus/genética , Acidithiobacillus/crescimento & desenvolvimento , Sequência de Aminoácidos , Regulação Bacteriana da Expressão Gênica , Técnicas de Inativação de Genes , Teste de Complementação Genética , Glutationa/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Mutação/genética , Oxirredução , Filogenia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Sulfatos/metabolismo , Temperatura , Transcrição Genética
18.
PLoS One ; 12(8): e0183307, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28813510

RESUMO

BACKGROUND: Acidithiobacillus caldus, a Gram-negative, chemolithotrophic sulfur-oxidizing bacterium, is widely applied in bioleaching. The absence of an ideal selection marker has become a major obstacle to achieve high efficiency of the gene transfer system for A. caldus. Plasmid pJRD215, widely used in Acidithiobacillus spp., has severe drawbacks in molecular manipulations and potential biosafety issues due to its mobility. Therefore, finding a new selection marker and constructing new plasmids have become an urgent and fundamental work for A. caldus. RESULTS: Effective inhibitory effect of chloramphenicol on the growth of A. caldus was elucidated for the first time. The P2-cat gene cassette, including a chloramphenicol acetyltransferase gene (cat) from plasmid pACBSR and a promoter (P2) upstream of the tetracycline resistance gene on pBR322, was designed, chloramphenicol acetyltransferase was expressed in A. caldus, and the enzyme activity was assessed. A new vector pSDU1 carrying the replication and mobilization regions derived from pJRD215, the P2-cat gene cassette and a multiple cloning site from pUC19 was successfully constructed. Compared with pJRD215, pSDU1 had a 27-fold increase in electrotransformation efficiency (30.43±0.88×104 CFU/µg DNA for pSDU1 and 1.09±0.11×104 CFU/µg DNA for pJRD215), better carrying capacity and could offer more convenience for the restriction enzyme digestion. In addition, the generated plasmid pSDU1Δmob, a novel non-mobilizable derivative of pSDU1 lacking some DNA sequences involved in the mobilization process, had increased copy number in A. caldus and lost its mobility for biosafety considerations. Both pSDU1 and pSDU1Δmob exhibited stable maintenance in A. caldus within 50 passages. However, further deletion of orfEF region involved in regulating repAC operon resulted in a negative effect on transformation efficiency, copy number and stability of plasmid pSDU1ΔmobΔorfEF in A. caldus. CONCLUSION: Chloramphenicol was proved to be an ideal selection marker for A. caldus. Novel plasmids carrying cat gene were constructed. The utilization of these vectors will undoubtedly facilitate efficient genetic manipulations and accelerate the research progress in A. caldus.


Assuntos
Acidithiobacillus/metabolismo , Cloranfenicol O-Acetiltransferase/genética , Plasmídeos/genética , Acidithiobacillus/efeitos dos fármacos , Acidithiobacillus/genética , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Cloranfenicol/farmacologia , Vetores Genéticos/genética , Regiões Promotoras Genéticas/genética
19.
BMC Ophthalmol ; 17(1): 113, 2017 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-28673264

RESUMO

BACKGROUND: Congenital ectopia lentis (CEL) usually leads to refractive error and may influence the axial length development. But few investigations have reported patient demographics and the distribution of axial length (AL) before surgery in Chinese pediatric patients with CEL. To describe the distribution of AL before surgery in CEL patients and its relationship with patients' demographics, such as age, Marfan syndrome, sex, and laterality. METHODS: This retrospective study reviewed 306 CEL patients from January 1, 2006 to December 31, 2015. One eye was randomly selected from each patient if both eyes were EL. The influences of Marfan syndrome, sex, and laterality to AL in different age subgroups were evaluated and compared. The differences of the AL between groups were assessed using the student t test or paired t-test. P-values less than 0.05 were considered statistically significant. RESULTS: Two hundred forty-seven eyes were enrolled. 58.3% of all the patients had binoculus EL, 70% of all the patients were male and 36% of all the patients were diagnosed with Marfan syndrome. The mean AL of EL patients was 25.1 ± 2.5 mm. There was no statistical difference in the AL between patients with and without Marfan syndrome, and in the AL between male and female patients. There was statistical difference in AL between the EL-affected eye and the unaffected eye in monocular EL patients younger than 12 years old. CONCLUSIONS: This study suggests that AL can be influenced by CEL, but the influence of CEL may be reduced after the age of 12 years old, which will likely provide a useful reference when considering the most appropriate time of surgery.


Assuntos
Comprimento Axial do Olho/patologia , Ectopia do Cristalino/diagnóstico , Refração Ocular , Adolescente , Criança , Pré-Escolar , China/epidemiologia , Ectopia do Cristalino/epidemiologia , Ectopia do Cristalino/fisiopatologia , Feminino , Humanos , Incidência , Masculino , Estudos Retrospectivos , Acuidade Visual
20.
Appl Microbiol Biotechnol ; 101(5): 2079-2092, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27966049

RESUMO

The sulfur oxidization (Sox) system is the central sulfur oxidization pathway of phototrophic and chemotrophic sulfur-oxidizing bacteria. Regulation and function of the Sox system in the chemotrophic Paracoccus pantotrophus has been elucidated; however, to date, no information is available on the regulation of this system in the chemolithotrophic Acidithiobacillus caldus, which is widely utilized in bioleaching. We described the novel tspSR-sox-like clusters in A. caldus and other chemolithotrophic sulfur-oxidizing bacteria containing Sox systems. The highly homologous σ54-dependent two-component signaling system (TspS/R), upstream of the sox operons in these novel clusters, was identified by phylogenetic analyses. A typical σ54-dependent promoter, P1, was identified upstream of soxX-I in the sox-I cluster of A. caldus MTH-04. The transcriptional start site (G) and the -12/-24 regions (GC/GG) of P1 were determined by rapid amplification of cDNA ends (5'RACE), and the upstream activator sequences (UASs; TGTCCCAAATGGGACA) were confirmed by electrophoretic mobility shift assays (EMSAs) in vitro and by UAS-probe-plasmids assays in vivo. Sequence analysis of promoter regions in tspSR-sox-like clusters revealed that there were similar σ54-dependent promoters upstream of the soxX genes. Based on our results, we proposed a TspSR-mediated signal transduction and transcriptional regulation pathway for the Sox system in A. caldus. The regulation of σ54-dependent two-component systems (TCSs) for Sox pathways were explained for the first time in A. caldus, A. thiooxidans, T. tepidarius, and T. denitrificans, indicating the significance of modulating the sulfur oxidization in these chemolithotrophic sulfur oxidizers.


Assuntos
Acidithiobacillus/genética , Regulação Bacteriana da Expressão Gênica , RNA Polimerase Sigma 54/genética , Sequências Reguladoras de Ácido Nucleico/genética , Enxofre/metabolismo , Acidithiobacillus/metabolismo , Sequência de Bases , Ensaio de Desvio de Mobilidade Eletroforética , Oxirredução , Regiões Promotoras Genéticas/genética , Análise de Sequência de DNA , Transdução de Sinais/genética , Ativação Transcricional/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA