A novel class of xylanases specifically degrade marine red algal ß1,3/1,4-mixed-linkage xylan.

Xylans are polysaccharides composed of xylose and include ß1,4-xylan, ß1,3-xylan, and ß1,3/1,4-mixed-linkage xylan (MLX). MLX is widely present in marine red algae and constitutes a significant organic carbon in the ocean. Xylanases are hydrolase enzymes that play an important role in xylan degradation. While a variety of ß1,4-xylanases and ß1,3-xylanases involved in the degradation of ß1,4-xylan and ß1,3-xylan have been reported, no specific enzyme has yet been identified that degrades MLX. Herein, we report the characterization of a new MLX-specific xylanase from the marine bacterium Polaribacter sp. Q13 which utilizes MLX for growth. The bacterium secretes xylanases to degrade MLX, among which is Xyn26A, an MLX-specific xylanase that shows low sequence similarities (<27%) to ß1,3-xylanases in the glycoside hydrolase family 26 (GH26). We show that Xyn26A attacks MLX precisely at ß1,4-linkages, following a ß1,3-linkage toward the reducing end. We confirm that Xyn26A and its homologs have the same specificity and mode of action on MLX, and thus represent a new xylanase group which we term as MLXases. We further solved the structure of a representative MLXase, AlXyn26A. Structural and biochemical analyses revealed that the specificity of MLXases depends critically on a precisely positioned ß1,3-linkage at the -2/-1 subsite. Compared to the GH26 ß1,3-xylanases, we found MLXases have evolved a tunnel-shaped cavity that is fine-tuned to specifically recognize and hydrolyze MLX. Overall, this study offers a foremost insight into MLXases, shedding light on the biochemical mechanism of bacterial degradation of MLX.

Structural and molecular basis for urea recognition by Prochlorococcus.

Nitrogen (N) is an essential element for microbial growth and metabolism. The growth and reproduction of microorganisms in more than 75% of areas of the ocean are limited by N. Prochlorococcus is numerically the most abundant photosynthetic organism on the planet. Urea is an important and efficient N source for Prochlorococcus. However, how Prochlorococcus recognizes and absorbs urea still remains unclear. Prochlorococcus marinus MIT 9313, a typical Cyanobacteria, contains an ABC-type transporter, UrtABCDE, which may account for the transport of urea. Here, we heterologously expressed and purified UrtA, the substrate-binding protein of UrtABCDE, detected its binding affinity toward urea, and further determined the crystal structure of the UrtA/urea complex. Molecular dynamics simulations indicated that UrtA can alternate between "open" and "closed" states for urea binding. Based on structural and biochemical analyses, the molecular mechanism for urea recognition and binding was proposed. When a urea molecule is bound, UrtA undergoes a state change from open to closed surrounding the urea molecule, and the urea molecule is further stabilized by the hydrogen bonds supported by the conserved residues around it. Moreover, bioinformatics analysis showed that ABC-type urea transporters are widespread in bacteria and probably share similar urea recognition and binding mechanisms as UrtA from P. marinus MIT 9313. Our study provides a better understanding of urea absorption and utilization in marine bacteria.

Active site architecture of an acetyl xylan esterase indicates a novel cold adaptation strategy.

SGNH-type acetyl xylan esterases (AcXEs) play important roles in marine and terrestrial xylan degradation, which are necessary for removing acetyl side groups from xylan. However, only a few cold-adapted AcXEs have been reported, and the underlying mechanisms for their cold adaptation are still unknown because of the lack of structural information. Here, a cold-adapted AcXE, AlAXEase, from the Arctic marine bacterium Arcticibacterium luteifluviistationis SM1504T was characterized. AlAXEase could deacetylate xylooligosaccharides and xylan, which, together with its homologs, indicates a novel SGNH-type carbohydrate esterase family. AlAXEase showed the highest activity at 30 °C and retained over 70% activity at 0 °C but had unusual thermostability with a Tm value of 56 °C. To explain the cold adaption mechanism of AlAXEase, we next solved its crystal structure. AlAXEase has similar noncovalent stabilizing interactions to its mesophilic counterpart at the monomer level and forms stable tetramers in solutions, which may explain its high thermostability. However, a long loop containing the catalytic residues Asp200 and His203 in AlAXEase was found to be flexible because of the reduced stabilizing hydrophobic interactions and increased destabilizing asparagine and lysine residues, leading to a highly flexible active site. Structural and enzyme kinetic analyses combined with molecular dynamics simulations at different temperatures revealed that the flexible catalytic loop contributes to the cold adaptation of AlAXEase by modulating the distance between the catalytic His203 in this loop and the nucleophilic Ser32. This study reveals a new cold adaption strategy adopted by the thermostable AlAXEase, shedding light on the cold adaption mechanisms of AcXEs.

Significant Bacterial Distance-Decay Relationship in Continuous, Well-Connected Southern Ocean Surface Water.

Recently, an increasing number of studies have focused on the biogeographic distribution of marine microorganisms. However, the extent to which geographic distance can affect marine microbial communities is still unclear, especially for the microbial communities in well-connected surface seawaters. In this study, the bacterial community compositions of 21 surface seawater samples, that were distributed over a distance of 7800 km, were surveyed to investigate how bacterial community similarity changes with increasing geographical distance. Proteobacteria and Bacteroidetes were the dominant bacterial phyla, with Proteobacteria accounting for 52.6-92.5% and Bacteroidetes comprising 3.5-46.9% of the bacterial communities. A significant bacterial distance-decay relationship was observed in the well-connected Southern Ocean surface seawater. The number of pairwise shared operational taxonomic units (OTUs), and community similarities tended to decrease with increasing geographic distance. Calculation of the similarity indices with all, abundant or rare OTUs did not affect the observed distance-decay relationship. Spatial distance can largely explain the observed bacterial community variation. This study shows that even in well-connected surface waters, bacterial distance-decay patterns can be found as long as the geographical distance is great enough. The biogeographic patterns should then be present for marine microorganisms considering the large size and complexity of the marine ecosystem.

Construction, properties, and application of the pCB5 plasmid, a novel conjugative shuttle vector with a Cupriavidus basilensis origin of replication.

Cupriavidus basilensis is a species with diverse metabolic capabilities, including degradation of xenobiotics and heavy metal resistance. Although the genomes of several strains of this species have been sequenced, no plasmid has yet been constructed for genetic engineering in this species. In this study, we identified a novel plasmid, designated pWS, from C. basilensis WS with a copy number of 1-3 per cell and a length of 2150 bp. pWS contained three protein-coding genes, among which only rep was required for plasmid replication. Rep showed no homology with known plasmid replication initiators. Unlike most plasmids, pWS did not have a cis-acting replication origin outside the region of rep. The minimal replicon of pWS was stable in C. basilensis WS without selection. A conjugative C. basilensis/Escherichia coli shuttle vector, pCB5, was constructed using the minimal replicon of pWS. Interestingly, the copy number of pCB5 was flexible and could be manipulated. Enhancing the expression level of Rep in pCB5 by either doubling the promoter or coding region of rep resulted in doubling of the plasmid copy number. Moreover, replacing the native promoter of rep with the lac promoter increased the copy number by over fivefold. Finally, using two different ß-galactosidase reporting systems constructed with pCB5, we successfully demonstrated the different regulatory patterns of bph and dmp operons during diphenyl ether (DE) degradation in C. basilensis WS. Thus, this shuttle vector provided an efficient tool for DNA cloning and metabolic engineering in C. basilensis.

Molecular insights into the catalytic mechanism of a phthalate ester hydrolase.

Phthalate esters (PAEs) are emerging hazardous and toxic chemicals that are extensively used as plasticizers or additives. Diethyl phthalate (DEP) and dimethyl phthalate (DMP), two kinds of PAEs, have been listed as the priority pollutants by many countries. PAE hydrolases are the most effective enzymes in PAE degradation, among which family IV esterases are predominate. However, only a few PAE hydrolases have been characterized, and as far as we know, no crystal structure of any PAE hydrolases of the family IV esterases is available to date. HylD1 is a PAE hydrolase of the family IV esterases, which can degrade DMP and DEP. Here, the recombinant HylD1 was characterized. HylD1 maintained a dimer in solution, and functioned under a relatively wide pH range. The crystal structures of HylD1 and its complex with monoethyl phthalate were solved. Residues involved in substrate binding were identified. The catalytic mechanism of HylD1 mediated by the catalytic triad Ser140-Asp231-His261 was further proposed. The hylD1 gene is widely distributed in different environments, suggesting its important role in PAEs degradation. This study provides a better understanding of PAEs hydrolysis, and lays out favorable bases for the rational design of highly-efficient PAEs degradation enzymes for industrial applications in future.

Serum γ-glutamyltransferase and uric acid levels are associated with impaired fasting glucose in adults from Inner Mongolia, China.

BACKGROUND: Serum γ-glutamyltransferase (GGT) and uric acid (UA) levels are elevated in patients with diabetes or cardiovascular disease. Prediabetes, characterized by impaired glucose tolerance, is an important risk factor for overt diabetes as well as cardiovascular disease. Therefore, the aim of this study was to explore the relationship between GGT, UA and prediabetes in a Chinese population, and provide a scientific basis for the early prevention and treatment of diabetes. METHODS: We performed a cross-sectional population-based study in a cohort of 2694 subjects (1211 men and 1483 women, aged 35-86 years). Questionnaires and physical examinations were performed using standardized procedures. Fasting blood was collected to measure glucose and other biochemical parameters. The subjects were divided into two groups with either normal fasting glucose (NFG) or impaired fasting glucose (IFG), according to international diagnostic criteria. Logistic regression analysis was performed to estimate odds ratios (OR) and 95% confidence intervals. RESULTS: Compared with the NFG group, the IFG group had significantly higher blood pressure but lower high-density lipoprotein-cholesterol in women. Body mass index, waist circumference, triglyceride, glucose, GGT, and UA levels were significantly higher in males and females in the IFG group than those in the NFG group. Logistic regression analysis revealed that the OR for prediabetes increased with increasing serum GGT quartiles and UA quartiles. GGT and UA were positively associated with prediabetes in men and women, independent of age, ethnicity, smoking, alcohol consumption, blood pressure, physical labor, and other confounders. CONCLUSIONS: We found that serum GGT and UA levels were positively associated with prediabetes in men and women living in areas inhabited by Chinese ethnic minorities. As elevated GGT and UA levels were associated with significantly increased risk of prediabetes, they may be used as sensitive biological markers of prediabetes.

Prevalence of hyperuricemia and its related risk factors in healthy adults from Northern and Northeastern Chinese provinces.

BACKGROUND: Hyperuricemia (HUA) is a potential risk factor for developing insulin resistance, hypertension, dyslipidemia and cardiovascular disease. Therefore, we studied the prevalence of HUA and associated risk factors in the population of two provinces in northern China. METHODS: Based on the research of Chinese Physiological Constant and Health Conditions conducted in 2008-2010, we enrolled 29,639 subjects in a randomized, stratified study in four sampling areas in Heilongjiang Province and the Inner Mongolia Autonomous Region. We collected 13,140 serum samples to determine biochemical indicators including uric acid(UA), glucose, blood lipids, liver function, and renal function, and finally a representative sample of 8439 aged 18 years and older was determined. We also defined and stratified HUA, hypertension, diabetes, obesity and lipid abnormalities according to international guidelines. RESULTS: There were significant differences in the UA levels between different genders and regions. The total prevalence of HUA is 13.7%. Men had a higher prevalence of HUA than women (21% vs. 7.9%; P < 0.0001). As age increased, HUA prevalence decreased in men but rose in women. The suburbs of big cities had the highest HUA prevalence (18.7%), and in high-prevalence areas the proportion of women with HUA also increased. A stepwise logistic regression model was used to filter out twelve HUA risk factors, including age, gender, residence, hypercholesterolemia, hypertriglyceridemia, impaired fasting glucose, hypertension, obesity, abdominal obesity, CKD, drinking and sleeping. After adjusting for these factors, the odds ratio of HUA was 1.92 times higher in men than in women. Compared with agricultural and pastoral areas, the odds ratio of having HUA was 2.14 for participants in the suburbs of big cities and 1.57 in the center of big cities. CONCLUSIONS: The prevalence of HUA is high in northern China. The differences in HUA prevalence by geographic region suggested that unbalanced economic development and health education, therefore HUA prevention measures should be strengthened to improve quality of life and reduce health care costs.

Structure of Vibrio collagenase VhaC provides insight into the mechanism of bacterial collagenolysis.

The collagenases of Vibrio species, many of which are pathogens, have been regarded as an important virulence factor. However, there is little information on the structure and collagenolytic mechanism of Vibrio collagenase. Here, we report the crystal structure of the collagenase module (CM) of Vibrio collagenase VhaC and the conformation of VhaC in solution. Structural and biochemical analyses and molecular dynamics studies reveal that triple-helical collagen is initially recognized by the activator domain, followed by subsequent cleavage by the peptidase domain along with the closing movement of CM. This is different from the peptidolytic mode or the proposed collagenolysis of Clostridium collagenase. We propose a model for the integrated collagenolytic mechanism of VhaC, integrating the functions of VhaC accessory domains and its collagen degradation pattern. This study provides insight into the mechanism of bacterial collagenolysis and helps in structure-based drug design targeting of the Vibrio collagenase.

High prevalence of coexisting prehypertension and prediabetes among healthy adults in northern and northeastern China.

BACKGROUND: Prehypertension and prediabetes are major risk factors of cardiovascular disease, and their combined presence may result in more serious cardiovascular outcomes than expected with either prehypertension or prediabetes alone. The aim of the present study was to evaluate the prevalence of coexisting prehypertension and prediabetes, and the associated risk profiles in a Chinese population. METHODS: A cross-sectional survey in a representative sample of 3,595 men and 4,593 women aged 18 years and older was performed between 2008 and 2010. Prehypertension and prediabetes were diagnosed using the guidelines from the Seventh Report of the Joint National Committee on prevention, detection, and treatment of high blood pressure and American Diabetes Association, respectively. Prehypertension was defined as a systolic blood pressure of 120-139 mmHg and/or diastolic blood pressure of 80-89 mmHg, and prediabetes was defined as a fasting blood glucose of 5.6-6.9 mmol/L. RESULTS: The prevalence of coexisting prehypertension and prediabetes was 11.0%. Men had a higher prevalence of coexisting prehypertension and prediabetes than women (14.2% vs. 8.4%; P < 0.0001). This prevalence increased with age and body mass index, and was the lowest among Mongolian-Chinese (5.1%). A multivariate analysis showed that γ-glutamyltransferase and uric acid were significantly and positively correlated with body mass index, waist circumference, blood pressure, triglycerides, and total cholesterol, and negatively correlated with high density lipoprotein cholesterol in subjects with prehypertension and prediabetes. CONCLUSIONS: There is a large proportion of Chinese adults with coexisting prehypertension and prediabetes. Thus, there is a need for more efforts that implement public health programs that target the earlier stages of hypertension and diabetes.

Isolation and characterization of Rhodococcus sp. NB5 capable of degrading a high concentration of nitrobenzene.

An efficient nitrobenzene degrading bacterium strain NB5, which was able to utilize nitrobenzene as a sole source of carbon, nitrogen and energy under aerobic condition, was isolated from activated sludge in an oil refinery at Hangzhou, China. Based on phenotypic features, 16S rDNA gene sequencing and G + C content analysis, strain NB5 was identified as Rhodococcus sp. NB5. Nitrobenzene degradation experiments using high performance liquid chromatograph (HPLC) showed that strain NB5 could tolerate a high nitrobenzene concentration and completely degrade nitrobenzene with initial concentration ranging from 100 mg · l(-1) to 1000 mg · l(-1) within 144 h. The optimal degradation and cell growth were observed at 30 °C, pH 7.0. The addition of second nitrogen source (0.1%) such as urea, peptone, yeast extract and beef extract generally enhanced degradation of nitrobenzene. Rhodococcus sp. strain NB5 could be an excellent candidate for biotreatment of industrial wastewater containing high concentration of nitrobenzene.

Efficacy and safety profile of neuroendoscopic hematoma evacuation combined with intraventricular lavage in severe intraventricular hemorrhage patients.

OBJECTIVE: The present study was conducted to explore the effect of neuroendoscopic hematoma evacuation in severe intraventricular hemorrhage (IVH). METHODS: Totally 81 patients with severe IVH in our hospital from November 2017 to March 2019 were divided into the intervention group (38 cases who received neuroendoscopic hematoma evacuation combined with intraventricular lavage) and the control group (40 cases who received trepanation drainage). The perioperative condition, hematoma clearance rate, Glasgow coma score (GCS), hematoma recurrence rate, and prognosis were observed and compared between the two groups after treatment. RESULTS: The operative time, time of cerebrospinal fluid drainage, and intracranial infection rate in the intervention group elicited superior results to those in the control group (p < .05). The clearance rate of hematoma in the intervention group was higher than that in the control group at 6 hr, 1, 3, and 7 days postoperatively (p < .05). The postoperative 3- and 7-day GCS scores in the intervention group were higher than those in the control group, and the recurrence rate of hematoma in the intervention group was significantly lower than that in the control group (p < .05), and the good/excellent rate of ADL in the intervention group was significantly higher than that in the control group (p < .05). CONCLUSION: Neuroendoscopic hematoma evacuation combined with intraventricular lavage showed evident beneficial outcomes in patients with severe IVH. It can effectively improve the perioperative condition and improve the hematoma clearance rate and is beneficial to the prognosis of patients with severe IVH.

Programmed fabrication of bimetallic nanobarcodes for miniature multiplexing bioanalysis.

Nanobarcodes with Morse code patterns are fabricated by a programmed electrochemical deposition process. These bimetallic nanobarcodes are stable and easy to decode using optical or electrical devices. Their discretionally patterned codes offer mass memory capacity for information carriers. They show promising features as probe molecules' carriers in multiplexing bioanalysis.

[Correlation of genes expression on MyD 88-dependent signaling pathway in progression of knee osteoarthritis].

OBJECTIVE: To investigate expression features and correlation of genes expression on MyD88-dependent signaling pathway in synovial membrane (SM) of progression of knee osteoarthritis (OA). METHODS: Sixty Wistar rats were randomly divided into 6 groups, including blank group (N), false surgical group, model groups[2 weeks (2W), 4 weeks (4W), 8 weeks (8W) and 12 weeks (12W)], with 10 rats in each group. The models were established by using Hulth method. Control group was experienced no surgery, while false surgical group was only opened joint cavity and sutured. The SM samples was collected according to the time designed above. The relative expression quantity of MyD88, TLR4 and NF-κB was detected by Real-time PCR after the extraction of the total RNA and reverse transcription. The correlation analysis was obtained by SPSS. RESULTS: There was no significant difference in each gene mRNA expression between false surgical and blank group(P> 0.05), while enhanced expression was found in the model groups(P<0.05). The correlation index among MyD88, TLR4 and NF-κB was 0.91 and 0.86 respectively, and had significant difference among them. CONCLUSIONS: Positively relative among MyD88, TLR4 and NF-κB played main role in TLR4/NF-κB signal passway, and could predicate the expression of other genes in the passway. It also could further provide the basis for clarify the pathologic mechanism of knee OA.

[Study on the clinical effect of the massage method of micro-regulating with vertical cross pressing lying on one side in treating cervicogenic headache].

OBJECTIVE: To evaluate the clinical effects of the massage method of micro-regulating with vertical cross pressing lying on one side in treating cervicogenic headache (CEH). METHODS: Total 136 patients with CEH were collected in the study from August 2012 to April 2014. They were divided randomly into two groups according to random digits table. Sixty-nine patients accepted the treatment of micro-regulating with vertical cross pressing lying on one side (pressing micro-regulating group), including 29 males and 40 females with an average age of (50.55 ± 11.38) years old; 67 patients received the treatment of traditional massage (traditional massage group), including 28 males and 39 females with an average age of (51.20 ± 11.90) years old. Clinical effect was observed according to the standard of curative effect of State Administration of Traditional Chinese Medicine; the function of cervical vertebra and all body status were evaluated according to NDI score. VAS score, frequency and time of headache were recorded and compared before and after treatment. RESULTS: No adverse reactions were found after treatment, all patients were followed up from 1 to 6 months with an average of 3.1 months. In pressing micro-regulating group, 25 cases got fully recover, 26 excellence, 14 effectiveness and 4 inefficiency; and in traditional massage group, the results were 12,21,22, 12;clinical effect of pressing micro-regulating group was better than that of traditional massage group (P<0.01). NDI score in pressing micro-regulating group decreased from preoperative 13.48 ± 4.83 to postoperative 6.23 ± 3.76; in traditional massage group also decreased from preoperative 13.82 ± 5.78 to postoperative 8.25 ± 4.75; the improvement of the pressing micro-regulating group was obviously better than that of traditional massage group (P < 0.01). VAS score in pressing micro-regulating group decreased from preoperative 4.75 ± 0.97 to postoperative 1.88 ± 1.78; and in traditional massage group decreased from pre-operative 4.78 ± 0.98 to postoperative 2.84 ± 1.94; pressing micro-regulating group was more notable than that of traditional massage group (P < 0.01). The frequency per week,the pain time in pressing micro-regulating group decreased from preoperative (5.38 ± 1.96) times and (6.87 ± 3.67) hours to postoperative (1.71 ± 2.04) times and (0.97 ± 1.74) hours,respectively,in traditional massage group the above parameters decreased from preoperative (5.22 ± 1.81) times and (6.90 ± 3.79) hours to postoperative (2.81 ± 2.42) times and (1.83 ± 2.21) hours;pressing micr-regulating group was more notable than that of traditional massage group (P < 0.01 or P < 0.05). CONCLUSION: Using the tuina method of micro-regulating with vertical cross pressing lying on one side to treat CEH can improve function of cervical vertebra and all body status, lessen the intensity, frequency, duration time of pain, and had advantage of higher security, simple operation, and evident effect.

[Effect of Acupuncture Stimulation of Different Acupoint Groups on Levels of Stress Hormones and Serum Brain-derived Neurotrophic Factor in Depression Rats].

OBJECTIVE: To screen the effective acupoints for anti-depression in depression rats and to explore the mechanisms of acupuncture for relieving depression. METHODS: Fifty rats were randomly divided into normal control, model, "Yin-tang" (EX-HN 3)-"Baihui" (GV 20, 2-acupoints), EX-HN 3-GV 20-"Fengchi" (GB 20)-"Shenshu" (BL 23, 4-acupoints) and medication groups, with 10 rats in each group. The depression model was established by unpredictable chronic mild stress (UCMS) for 28 days. For rats of the 2-acupoints and 4-acupoints groups, EX-HN 3 and GV 20, and EX-HN 3, GV 20, GB 20 and BL 23 were punctured with filiform needles respectively before performing mild stress every time. The acupuncture needles were retained for 30 min during each intervention and the treatment was conducted once daily for 28 days. The rats of the medication group were treated by intragastric administration of Fluoxetine (0.18 mg/kg) once a day for 28 days. The rats' anxiety-like behavior (rearing and crossing times) was detected by open-field test. The contents of adrenocorticotropic hormone (ACTH) in the pituitary, 5-hydroxytryptamine (5-HT) in the hippocampus, the cortisol (CORT) in the adrenal gland, and the brain derived neurotrophic factor (BDNF) in the serum were examined by ELISA. RESULTS: Compared to the normal control group, the numbers of both rearing and crossing motions in the model group were significantly decreased (P<0.01, P<0.05), while in comparison with the model group, the rearing and crossing numbers of rats in the 2-acupoints and 4-acupoints and medication groups were significantly increased (P<0.01). ELISA showed that after modeling, the content of adrenal CORT was significantly increased (P<0.01), and those of hippocampal 5-HT and serum BDNF were obviously down-regulated in the model group (P<0.01). After the treatment, the adrenal CORT levels in the three intervention groups were notably down-regulated, and hippocampal 5-HT and serum BONE evidently up-regulated in these 3 intervention groups (P<0.05, P<0.01). No marked changes were found in the pituitary ACTH contents of the model and 3 intervention groups (P>0.05), and no significant differences were shown among the three intervention groups in the levels of the aforementioned 6 indexes (P>0.05). CONCLUSION: Acupuncture intervention can effectively improve the unprompted activates of the depression rats, which may be related to its effects in up-regulating hippocampal 5-HT and serum BONE levels, and in down-regulating adrenal CORT content.

Cloning, expression, and characterization of a wide-pH-range stable phosphite dehydrogenase from Pseudomonas sp. K in Escherichia coli.

A phosphite dehydrogenase gene (ptdhK) consisting of 1,011-bp nucleotides which encoding a peptide of 336 amino acid residues was cloned from Pseudomonas sp. K. gene ptdhK was expressed in Escherichia coli BL21 (DE3) and the corresponding recombinant enzyme was purified by metal affinity chromatography. The recombinant protein is a homodimer with a monomeric molecular mass of 37.2 kDa. The specific activity of PTDH-K was 3.49 U mg(-1) at 25 °C. The recombinant PTDH-K exhibited maximum activity at pH 3.0 and at 40 °C and displayed high stability within a wide range of pHs (5.0 to 10.5). PTDH-K had a high affinity to its natural substrates, with K (m) values for sodium phosphite and NAD of 0.475 ± 0.073 and 0.022 ± 0.007 mM, respectively. The activity of PTDH-K was enhanced by Na(+), NH (4) (+) , Mg(2+), Fe(2+), Fe(3+), Co(2+), and EDTA, and PTDH-K exhibited different tolerance to various organic solvents.

Cloning and expression in E. coli of an organic solvent-tolerant and alkali-resistant glucose 1-dehydrogenase from Lysinibacillus sphaericus G10.

The gene gdh encoding an organic solvent-tolerant and alkaline-resistant NAD(P)-dependent glucose 1-dehydrogenase (LsGDH) was cloned from Lysinibacillus sphaericus G10 and expressed in Escherichia coli. The recombinant LsGDH exhibited maximum activity at pH 9.5 and 50 °C. LsGDH displayed high stability at a wide pH ranging from 6.5 to 10.0 and was stable after incubation at 30 °C for 1 week in 25 mM sodium phosphate buffer (pH 6.5) in the absence or presence of NaCl. The activity of LsGDH was enhanced by Li+, Na+, K+, NH4+, Mg2+, and EDTA at pH 8.0. LsGDH exhibited high tolerance to 60% DMSO, 30% acetone, 30% methanol, 30% ethanol, 10% n-propanol, 30% isopropanol, 60% n-hexanol and 30% n-hexane. The relationship between stability and chain length of the alcohols fit a Gaussian distribution model (R2≥0.94), and demonstrated lowest enzyme stability in C4-alcohol. The results suggested that LsGDH was potentially useful for coenzyme regeneration in organic solvents or under alkaline conditions.

Direct microbial conversion of wheat straw into lipid by a cellulolytic fungus of Aspergillus oryzae A-4 in solid-state fermentation.

Direct microbial conversion of wheat straw into lipid by a cellulolytic fungus of Aspergillus oryzae A-4 in solid-state fermentation (SSF) was investigated. In submerged fermentation, A. oryzae A-4 accumulated lipid to 15-18.15% of biomass when pure cellulose was utilized as the sole substrate. In SSF of the wheat straw and bran mixture, A. oryzae A-4 yielded lipid of 36.6mg/g dry substrate (gds), and a cellulase activity of 1.82 FPU/gds with 25.25% of holocellulose utilization in the substrates were detected on the 6th day. The lipid yield reached 62.87 mg/gds in SSF on the 6th day under the optimized conditions from Plackett-Burman design (PBD). Cellulase secretion of A. oryzae A-4 was found to influence the lipid yield. Dilute acid pretreatment of the straw and addition of some agro-industrial wastes to the straw could enhance lipid production of A. oryzae A-4.

Fibronectin enhances in vitro vascular calcification by promoting osteoblastic differentiation of vascular smooth muscle cells via ERK pathway.

The process of vascular calcification presents several features similar to osteogenesis in which fibronectin (FN) acts as a regulator of osteoblastic differentiation and the ERK signal pathway is involved. In order to find whether FN promotes the osteoblastic differentiation of vascular smooth muscle cells (VSMCs) through the ERK signal pathway, we investigated the effect of FN on the calcification of VSMCs by using an in vitro cell model. VSMCs cultured in plates with FN (0-20 microg/cm2) coating were induced to calcify by 10 mM sodium beta-glycerophosphate (beta-GP). FN exacerbated VSMC calcification in a dose- and time-dependent manner, as indicated by the number of calcifying nodules per slide and the amount of calcium in the deposition. Data from RT-PCR and immunoblotting assay revealed that FN also enhanced the expression of several phenotypic markers of osteoblasts, including alkaline phosphatase (ALP) activity, osteocalcin (OC), and Osf2/Cbfa1, a key transcription factor in osteoblastic differentiation. Furthermore, a specific inhibitor for ERK, PD98059 (10 microM), significantly suppressed the effect of FN on calcification and phenotypic marker expression. These findings seem to suggest that FN enhanced vascular calcification by promoting the osteoblastic differentiation of VSMCs via ERK signal pathway.