Two sex pheromone receptors for sexual communication in the American cockroach.

Volatile sex pheromones are vital for sexual communication between males and females. Females of the American cockroach, Periplaneta americana, produce and emit two sex pheromone components, periplanone-A (PA) and periplanone-B (PB). Although PB is the major sex attractant and can attract males, how it interacts with PA in regulating sexual behaviors is still unknown. In this study, we found that in male cockroaches, PA counteracted PB attraction. We identified two odorant receptors (ORs), OR53 and OR100, as PB/PA and PA receptors, respectively. OR53 and OR100 were predominantly expressed in the antennae of sexually mature males, and their expression levels were regulated by the sex differentiation pathway and nutrition-responsive signals. Cellular localization of OR53 and OR100 in male antennae further revealed that two types of sensilla coordinate a complex two-pheromone-two-receptor pathway in regulating cockroach sexual behaviors. These findings indicate distinct functions of the two sex pheromone components, identify their receptors and possible regulatory mechanisms underlying the male-specific and age-dependent sexual behaviors, and can guide novel strategies for pest management.

Healthy lifestyle mediates the association between health locus of control and life satisfaction among college students in Hubei, China: during the normalization stage of COVID-19 epidemic prevention and control.

BACKGROUND: Previous studies have primarily focused on the relationships among the health locus of control (HLC), healthy lifestyle and life satisfaction of college students. However, little is known about the mediating mechanism of healthy lifestyle on the other two aspects. This study aims to address this issue. METHODS: A total of 2394 students from six colleges in Hubei Province validly completed self-report questionnaires, including the Satisfaction with Life Scale (SWLS), Healthy Lifestyle Questionnaire for college students and Multidimensional Health Locus of Control Scale (MHLC), which covered three dimensions: internal HLC, powerful others HLC and chance HLC. Partial least squares structural equation modelling (PLS-SEM) was employed to analyses the hypothesized relationships in the path model, and a mediation analysis was used to verify the indirect relationships. RESULTS: Healthy lifestyle and life satisfaction showed positive relations with both internal HLC and powerful others HLC, but a significant negative association with chance HLC. In addition, healthy lifestyle mediated the relationships of internal HLC, powerful others HLC and chance HLC with life satisfaction. CONCLUSIONS: Healthy lifestyle mediates the impact of HLC on life satisfaction. Students with high IHLC tend to develop a healthier lifestyle and have higher LS. Powerful others also exert positive effects in collectivist cultural backgrounds. Thus, colleges should give full play to the positive role of psychological health and physical education courses in improving students' IHLC. Meanwhile, the positive guiding effect of powerful others should be stressed. Further, particular emphasis should also be placed on the peer influence, new media publicity functions, community intervention, and college systematic appraisal, especially during and after public health emergencies.

Reutilization of waste oyster shell as filler for filter for drinking water pretreatment: Feasibility and implication.

Oyster shell (OS) is a kind of reusable resource that can serve as carbon source, biofilms carrier and basifying agent, suggesting it is an attractive filler option for biofiltration, but studies on its application in drinking water treatment are limited. In this study, one pilot-scale up-flow filter filled with OS media were designed to pretreat surface source water. Filter performance and biological functions were investigated to determine its application scope. The results showed that effluent pH increased and was stable around 7.5 due to the alkalinity provided by OS and its buffering capacity. High and stable removal efficiencies of turbidity (mostly >60%) were achieved. The removal efficiencies of NH4+-N changed in a wide range (mostly <30%). TOC and UV254 removal rate was low (<10%). The biofilms formation period took about 45 days. During this period, this filter mainly removed pollutants through adsorption by OS. High-throughput sequencing results showed that functional taxa did not play a key role after adsorption saturation in early operation period. Functional microbial taxa formed on the OS surface after long-term operation and NH4+-N removal rate increased to some extent. Our results suggested that unburned OS filter can be used as rough filter for turbidity removal instead of coagulation and sedimentation process. Preoxidation, calcination of OS, mixed with other filler and are recommended to improve the performance if it would be used for biofiltration. This study provides an insight for the reuse of OS in drinking water treatment.

Decreasing arsenic accumulation but promoting arsenate biotransformation in Microcystis aeruginosa regulated by nano-Fe2O3.

Iron oxide nanoparticles (nano-Fe2O3) widely distribute in waters with low toxicity to aquatic organisms. But it is unclear for nano-Fe2O3 to affect the fate of coexisting arsenic (As) with its bioaccumulation and biotransformation. In this study, we thus mainly investigated arsenate (As(V)) toxicity, uptake kinetics, biotransformation and subcellular distribution in Microcystis aeruginosa influenced by nano-Fe2O3. The results showed that M. aeruginosa was more sensitive to As(V) associated with nano-Fe2O3. Due to the exaggerated increase of efflux rate constants of As compared with the uptake rate constants in algal cells affected by different levels of nano-Fe2O3, the As(V) bioconcentration factor decreased with nano-Fe2O3 increasing correspondingly, indicating that As bioaccumulation was diminished by nano-Fe2O3. The decreased As accumulation in M. aeruginosa could be supported by the evidential As(V) sequestration through high adsorption of nano-Fe2O3, which resulted in decreasing free As level for algae uptake in media. Meanwhile, As subcellular distribution was adjusted by nano-Fe2O3 with decreasing in cell walls and rising in cytoplasmic organelles compared with nano-Fe2O3 free. As(V) reduction and methylation were enhanced with increasing nano-Fe2O3, stimulating by its sensitivity to the interaction of nano-Fe2O3 and As(V) as well as the rising level of As in cytoplasmic organelles of this algae. It is confirmed by the higher relative gene expression levels of arsC and arsM in elevated nano-Fe2O3. Accordingly, it is highlighted to be deserved more attention that the changing behavior of As(V) by nano-Fe2O3 that reduce As bioaccumulation and accelerate its biotransformation in algae in As contaminated water.

Relationship between suicidal ideation, daily stress and positive mental health among college freshmem in Wuhan / 中国学校卫生

Objective@#To investigate the prevalence and influencing factors of suicidal ideation and the effects of daily stress and positive mental health on suicidal ideation among college freshmen in Wuhan. This study aims to provide a scientific basis for mental health improvement and suicide prevention among college students from the perspective of positive psychology.@*Methods@#In December 2020, a convenient sampling method was used to select 2 592 freshmen from three universities in Wuhan. Demographic information, suicidal ideation, positive mental health, and daily stress were assessed. T test and Logistic regression analysis were used to analyze the status and influencing factors of suicidal ideation among college freshmen.@*Results@#The one year prevalence of suicidal ideation was 27.5%. Freshmen with suicidal ideation had higher daily stress scores and daily stress scores in different domains than freshmen without suicidal ideation( t =-13.00--4.68)， the positive mental health scores of freshmen with suicidal ideation were lower than freshmen without suicidal ideation ( t =17.14， P <0.01). Female ( OR=1.72, 95%CI =1.44-2.05), the higher education level of the mother (OR=1.27, 95%CI=1.05-1.53) and total experience of daily stress ( OR=1.11, 95%CI =1.09- 1.13 ) were associated with risk of oneyear suicidal ideation. Positive mental health was negatively associated with suicidal ideation ( OR=0.88, 95%CI=0.87-0.90, P <0.01) and had a moderating effect on the association between daily stress and suicidal ideation.@*Conclusion@#Suicidal ideation among college freshmen is closely related to daily stress and positive mental health. It is necessary to pay close attention to daily stress of freshmen and reduce suicidal ideation by improving positive mental health.

Association between locus of control and health risk behaviors among college students / 中国学校卫生

Objective@#To explore the prevalence of health risk behaviors and the association between locus of control and health risk behaviors among college students, and to provide reference for the formulation of health risk behavior intervention for college students.@*Methods@#A multi stage cluster random sampling method was used to select 2 provinces from the east, central and west regions of China, respectively. Two universities were then randomly selected from each selected province. A total of 3 951 college students from 12 universities completed the electronic and anonymous questionnaires, which included demographic characteristics, Multidimensional Health Locus of Control Questionnaire (MHLC) and Health Risk Behaviors Questionnaire. Chi square test and binary Logistic regression were applied to analyze data.@*Results@#Totally 2 287(57.88%) students reported having three or more kinds of health risk behaviors. The prevalence of excessive screen time, insufficient physical exercise, poor eating behaviors, drinking and smoking were 97.34%(3 846), 74.72%(2 952), 72.21%(2 853), 13.62%(538) and 5.57%(220). Internal locus of control was associated with lower risk of three or more kinds of health risk behavior ( OR =0.98) and inadequate physical activity ( OR =0.93) and associated with higher risk of smoking ( OR =1.07). The powerful others was associated with lower risk of three or more kinds of health risk behavior ( OR =0.98), drinking ( OR =0.95) and unhealthy eating behavior ( OR =0.97). And the chance was associated with higher risk of three or more kinds of health risk behavior ( OR = 1.04 ), drinking ( OR =1.04) and inadequate physical activity ( OR =1.03)( P <0.01).@*Conclusion@#College students have serious health risk behavior problems, the locus of control is associated with health risk behaviors among college students. Which might be helpful to prevent the occurrence of health risk behaviors, and improve overall health of college students.

Impact of Family Cohesion and Adaptability on Academic Burnout of Chinese College Students: Serial Mediation of Peer Support and Positive Psychological Capital.

This study aimed to explore the association between the functioning of family environment (i.e., family cohesion and family adaptability) and academic burnout of Chinese college students as well as the mediating effects of the interpersonal resource (i.e., peer support) and intrapersonal resource [i.e., positive psychological capital (PsyCap)] in this relationship. A total of 1971 Chinese undergraduates were involved in an online questionnaire survey and data analysis. It was found that family cohesion and adaptability was negatively related to academic burnout. Mediation analyses demonstrated that family cohesion and adaptability did not directly affect academic burnout, but indirectly through increasing PsyCap (characterized by optimism, hope, resilience, and self-efficacy), and through enhancing peer support and then increasing PsyCap in serial. Meanwhile, the relationship between family cohesion and adaptability and academic burnout was not mediated by peer support alone. These findings highlight the family environment's crucial role in youth mental health and positive development in the college context.

Prevalence of and Factors Associated With Depressive Symptoms Among College Students in Wuhan, China During the Normalization Stage of COVID-19 Prevention and Control.

Objectives: The 2019 coronavirus disease (COVID-19) epidemic has led to persistent negative psychological effects on the general public, especially on college students, who are highly susceptible to psychological difficulties, such as fear, anxiety, and depression. Little information is known about depressive symptoms among college students during the normalization stage of COVID-19 prevention and control in China. This study aimed to understand the prevalence of and factors associated with depressive symptoms after a long quarantine time and online learning at home among college students in Wuhan, China. Materials and Methods: A web-based survey was conducted from July to August 2020 during the Chinese summer holiday to collect data on sociodemographic variables, depressive symptoms, and their potential associated factors using an electronic questionnaire among college students in Wuhan, China. The Patient Health Questionnaire-9 (PHQ-9) was used to measure depressive symptoms. Binary logistic regression was used to explore the factors associated with depressive symptoms. Results: A total of 9,383 college students were included in the analysis. The prevalence of depressive symptoms was 15.8% (1,486/9,383) among college students. The binary logistic regression showed that the experience of being quarantined for observation or treatment, family members or friends dying of COVID-19, rarely or never seeking help from others, fewer supportive relatives or friends, less support from family in the past month, a worse relationship with parents at home, a longer time spent daily on electronic devices except for online learning, and feeling anxious in the face of returning to school were independently associated with a higher risk of depressive symptoms. Academic stress and concern about the epidemic were the main reasons for their anxiety. Conclusions: Targeted psychological intervention measures are recommended for college students to improve their mental health during the normalization stage of COVID-19 prevention and control.

Prevalence of and Factors Associated with Club Drug Use among Secondary Vocational Students in China.

To understand the prevalence of and factors associated with club drug use among Chinese secondary vocational students, a nationally representative survey was conducted. The multistage cluster sampling strategy was employed to select participants. A total of 9469 students from eleven secondary vocational schools in five cities completed self-reported questionnaires, which included information on club drug use, sociodemographic variables, individual factors, as well as peer and family related factors. The data were separately analyzed with Poisson regression models for female and male students. The overall lifetime prevalence of club drug use was 2.7% (258/9469), and male students had higher prevalence than female students (3.5% vs. 1.9%, p < 0.001). Female and male students shared four risk factors (i.e., having ever smoked, perceiving social benefit expectancies, peer drug using and perceiving peer's approval of drug use) and one protective factor (i.e., having medium or high levels of refusal skills) for club drug use. Moreover, family drug using and having a part-time job were two additionally independent risk factors for club drug use among male students. These findings indicate that the problem of club drug use among Chinese secondary vocational students is worthy of attention. The prevention of club drug use should address multiple risks and protective factors on individual, peer and family levels.

Anxiety, Depression, and Satisfaction With Life Among College Students in China: Nine Months After Initiation of the Outbreak of COVID-19.

BACKGROUND/OBJECTIVE: Mental health problems are common among college students. This study sought to assess the prevalence and risk factors of depressive and anxiety symptoms and well-being among Chinese college students 9 months after initiation of the outbreak of COVID-19. METHOD: A cross-sectional study (N = 3,951, mean age = 19.58) was conducted from October to December 2020. An online survey was used to collect socio-demographic data, and the symptoms of depression and anxiety and satisfaction with life using Disorder 7-Item Scale (GAD-7), the Patient Health Questionnaire 9-Item Scale (PHQ-9), and the 5-items Satisfaction with Life Scale (SWLS). RESULTS: The prevalence of depressive and anxiety symptoms was 59.35 and 54.34%, respectively, and the score of satisfaction with life was 20.51 ± 6.42 among Chinese college students during the pandemic. After controlling for covariates, students in urban areas (AOR = 0.73, 95% CI = 0.61-0.87), with good family economic levels (AOR = 0.77, 95% CI = 0.66-0.91), and having psychological counseling (AOR = 0.55, 95% CI = 0.42-0.73) were positively associated with depression symptoms; meanwhile, higher anxiety symptoms were observed among medical students (AOR = 0.81, 95% CI = 0.69-0.95). Besides, healthy lifestyle such as regular physical activity and diet was associated with depression and anxiety symptoms. Multiple linear models revealed that medical students (ß = 0.479, P = 0.031), those with good family economic level by self-evaluation (ß = 1.283, P < 0.001 for good; ß = 3.013, P < 0.001 for general), good academic performance by self-evaluation (ß = 1.786, P < 0.001 for good; ß = 3.386, P < 0.001 for general), learning burden (ß = 1.607, P < 0.001 for general; ß = 2.117, P < 0.001 for light), regular physical activity (ß = 0.859, P < 0.001), daily routine (ß = 1.289, P < 0.001), diet (ß = 1.714, P < 0.001), and sufficient sleep (ß = 1.408, P < 0.001) had more score of SWLS (all ß > 0, P < 0.05), while senior students (ß = -1.053, P=0.009), students having psychological counseling (ß = -1.753, P < 0.001), and drinking (ß = -0.743, P = 0.012) had lower satisfaction with life. CONCLUSIONS: These findings suggest that more attention should be paid to psychological health among college students, especially during and after the COVID-19 outbreak. Policy makers and educators should help college students develop a healthy lifestyle with regular diet and exercise to promote the psychological health of college students.

Abstinence Following a Motivation-Skill-Desensitization-Mental Energy Intervention for Heroin Dependence: A Three-year Follow-up Result of a Randomized Controlled Trial.

The high rate of relapse among heroin users remains a significant public concern in China. In the present study, we utilized a Motivation-Skill-Desensitization-Mental Energy (MSDE) intervention and evaluated its effects on abstinence and mental health. Eighty-nine male heroin users in a drug rehabilitation center were enrolled in the study. The participants in the MSDE intervention group (n=46) received MSDE intervention, which included motivational interviewing, coping skills training, eye movement desensitization and reprocessing, and mindfulness-based psychotherapy. The participants in the control group (n=43) received a series of lectures on skills training. A significant increase in Contemplation Ladder score (P<0.001) and decreases in scores on the Obsessive Compulsive Drug Use Scale (P<0.001), Beck Depression Inventory (P<0.001), and Aggression Questionnaire (P=0.033) were found immediately after intervention. Compared to the control group, the MSDE intervention group reported significantly higher abstinence rates (P=0.027) and retention rates (P<0.001) at follow-up. Overall, the MSDE intervention, which uses a combined strategy for relapse prevention, could be a promising approach for preventing relapse among heroin users in China.

Tranexamic acid reduces blood loss in intertrochanteric fractures: A meta-analysis from randomized controlled trials.

BACKGROUND: This meta-analysis aims to assess the efficacy and safety of tranexamic acid for reducing blood loss and transfusion requirements in patients with intertrochanteric fractures. METHODS: We conduct electronic searches of Medline (1966-2017.09), PubMed (1966-2017.09), Embase (1980-2017.09), ScienceDirect (1985-2017.09), and the Cochrane Library. Only randomized controlled trials (RCTs) are included. The quality assessments are performed according to the Cochrane systematic review method. Fixed/random-effect model is used according to the heterogeneity tested by I statistic. Meta-analysis is performed using Stata 11.0 software. RESULTS: A total of 4 RCTs are retrieved involving 514 participants. The present meta-analysis indicated that there were significant differences between groups in terms of total blood loss (weighted mean differences = -131.49, 95% confidence interval (CI): -163.63 to -99.35, P = .00), hemoglobin decline (weighted mean differences = -0.31, 95% CI, -0.44 to -0.19, P = .00), and transfusion rate (risk differences = -1.11, 95% CI, -0.19 to -0.04, P = .00). In addition, no increased risk of adverse effects was identified in both groups. CONCLUSION: Local administration of tranexamic acid is associated with a reduced total blood loss, postoperative hemoglobin decline, and transfusion requirements in patients with intertrochanteric fractures. High-quality RCTs are still required for further investigation.

Tryptophan for the sleeping disorder and mental symptom of new-type drug dependence: A randomized, double-blind, placebo-controlled trial.

INTRODUCTION: New-type drugs are popular with adolescents and could lead to psychiatry disorders, but no medications have been proven to be effective for these disorders of new-type drug dependence. We aimed to evaluate the efficacy of tryptophan on sleeping disorders and mental symptoms in detoxified individuals with new-type drug dependence. METHODS: This randomized, placebo-controlled trial included 80 detoxified individuals with new-type drug dependence, recruited successively from a Compulsory Residential Drug Abstinence Institution in Wuhan, China, from April 2012 to November 2012. Eligible participants were randomly allocated to be treated with tryptophan (1000 mg/d, n = 40) or placebo (n = 40) for 2 weeks. The sleeping disorders and mental symptoms were assessed using Athens Insomnia Scale and Symptom Check-List-90 at baseline and 2 weeks. Results were analyzed according to the "intention-to-treat" approach. RESULTS: Forty-five participants completed the 2-week study, 24 in the tryptophan group and 21 in the placebo group. There were no statistically significant differences in baseline characteristics between groups and the treatment adherence was similar between groups. The reduction in the Athens Insomnia Scale score in the tryptophan group was significantly greater than that in the placebo group (P = 0.017). However, no significant differences were found in Symptom Check-List-90 scores (either by individual dimension or the overall score) between groups (all P > 0.05). The frequency of adverse events was similar and no serious adverse events were reported during the study. CONCLUSION: Tryptophan was unlikely to be effective for mental symptoms, but could alleviate sleep disorders in short term among detoxified individuals with new-type drug dependence. Future large-scale trials are required to confirm findings from this study.

Influence of Parental Monitoring, Sensation Seeking, Expected Social Benefits, and Refusal Efficacy on Tobacco and Alcohol Use in Chinese Adolescents.

The relationships between parental monitoring (PM), sensation seeking (SS), expected social benefits (ESB), refusal efficacy (RE), and tobacco and alcohol use (TAU) have been well documented among adolescents. However, the mechanisms by which these 4 determinants affect TAU remain unclear. Based on the Theory of Triadic Influence, this study aimed to explore how PM, SS, ESB, and RE simultaneously influenced TAU in Chinese adolescents. From September 2013 to June 2014, we used multistage cluster sampling to select 6269 students from 179 classes of 7 vocational high schools in 3 cities of China. Each student completed a battery of 5 measures: PM, SS, ESB, RE, and TAU. Then, we used structural equation modeling techniques and mediation analyses to investigate the relationships among these 5 measures, with TAU as the final dependent variable. Results demonstrated that the relationship between PM and TAU was fully mediated by ESB and RE (b = -0.18, P < 0.001), that SS influenced TAU directly (b = 0.10, P < 0.001) and indirectly through ESB and RE (b = 0.15, P < 0.001), and that ESB influenced TAU directly (b = 0.09, P < 0.001) and indirectly through RE (b = 0.28, P < 0.001).These findings indicate that the link between PM and SS to TAU among Chinese adolescents can be explained by ESB and RE. These 4 precursory determinants can play an important role in TAU prevention among adolescents in China.

Nonmedical Use of Cough Syrup Among Secondary Vocational School Students: A National Survey in China.

Nonmedical use of cough syrup (NUCS) among secondary vocational school (SVS) students has been an increasing concern for public health in China, but no data were available. This cross-sectional study aimed to investigate the epidemiological characters of NUCS as well as its risk factors among SVS students in China.From September 2013 to December 2014, a total of 13,614 SVS students were purposively selected through multistage sampling in 6 cities of China. Information on NUCS, demographics, family background, smoking and alcohol consumption, impulsiveness, sensation seeking, and parental monitoring were collected. Logistic regression was used to explore factors related to NUCS.The 12,923 (94.9%) valid responses (16.3 ±â€Š1.0 years old, and 52.6% men) reported 3.47% (95% confidence interval: 3.15-3.79%) lifetime NUCS. Logistic regression indicated that smoking, part-time job experience, high level of impulsiveness, and sensation seeking were risk factors for NUCS, whereas urban living and high parental monitoring were protective ones.NUCS was prevalent among SVS students. Interventions that target on smoking, impulsiveness and sensation seeking control, improvement on parental monitoring may have considerable impact on NUCS among SVS students.

The Effect of a Brief Intervention for Patients with Ischemic Stroke: A Randomized Controlled Trial.

BACKGROUND: Depression and anxiety are common after stroke. There is inconclusive evidence of the benefit of psychotherapy for poststroke depression and anxiety. Here, we used a brief intervention, Neuro-Linguistic Programming (NLP) brief therapy plus health education, to evaluate the changes in patients with ischemic stroke. METHODS: One hundred eighty patients were randomly allocated to receive 4 sessions of NLP plus health education (n = 90) or usual care (n = 90). A set of questionnaires was used preintervention and postintervention as well as at the 6-month follow-up. The primary outcomes were the prevalence of depression and anxiety, and the awareness of stroke knowledge. RESULTS: More patients in the intervention group achieved remission of depressive (odds ratio [OR], 2.81; 95% confidence interval [CI], 1.41-5.59) and anxious symptoms (OR, 2.19; 95% CI, 1.15-4.18) after intervention. At the 6-month follow-up, we found no differences between groups in both the prevalence of depression and anxiety. After intervention, the intervention group had better awareness rates on most of the stroke knowledge items (P < .05). It also had better quality of life and physical function both after intervention and at the follow-up (P < .05). CONCLUSIONS: NLP plus health education could reduce depression and anxiety immediately after intervention, but not at the 6-month follow-up. The intervention could also improve the awareness of stroke knowledge and benefit patients on quality of life and physical function.

Occupational safety and health status of sanitation workers in urban areas: a pilot study from Wuhan, China.

Sanitation workers' workload increases quickly with rapid urbanization, but there is almost no evidence or policy recommendations for their management in developing countries. This study describes the health status and occupational protection of sanitation workers; it also explores risk factors related to their health status in Wuhan City, China. Three hundred and eighty-five sanitation workers from 54 streets of Wuhan were surveyed. Their prevalence of 2-week illness and arthritis was relatively higher than in the general population in China. Findings related to occupational protection showed that both sanitation workers (users) and their managers (providers) neglected the role of low-cost protection measures, especially masks, soap/hand sanitizer and prejob training (use rate of 7.27%, 26.75% and 43.64%, respectively). High-intensity workload was an important risk factor for 2-week illness, and prejob training was an important protective factor against arthritis.

[Expression of glycerol dehydrogenase gene in Escherichia coli by codon optimization].

OBJECTIVE: To improve expression level of glycerol dehydrogenase gene gldA in Escherichia coli by means of codon optimization. METHODS: For immediately downstream region of initiation codon in gldA, we designed optimized sequence by choosing higher AT-content synonymous, in order that this region's AT-content was increased without changing the corresponding amino acids. Then we had wild gene gldA-WT site-directed mutagenesis depending on mega-primers PCR, so that physically optimized gene gldA-4 was acquired. We cloned gldA-4 into pET-32a(+) to construct expression plasmid pET-gldA4, which was transformed into Escherichia coli BL21 (DE3) for gaining engineering bacteria E. coli-4, by contrast engineering bacteria involved gldA-WT named E. coli-WT. After E. coli-4 and E. coli-WT were fermented in shake flasks,we measured enzyme activities of expression products with glycerol as substrate. RESULTS: Four gldA-4's bases in the second, fifth and sixth codon were different with gldA-WT, so AT-content of the optimized gene was up to 80.0% higher than the wild gene's 53.3%. Furthermore, enzyme activity of E. coli-4's crude extract was 191.3 U/mL more three times than E. coli-WT's 48.3 U/mL. CONCLUSION: This optimization scheme was quick and easy, but indeed increased dehydrogenase's activity. It possible becomes a universal method to improve heterogenous expression level of target genes.

Codon optimization of 1, 3-propanediol oxidoreductase expression in escherichia coli and enzymatic properties

The gene dhaT from Klebsiella pneumoniae encoding 1,3-propanediol oxidoreductase (PDOR) was de novo synthesized by splicing overlap extension polymerase chain reaction (SOE-PCR) primarily according to Escherichia coli’s codon usage, as well as mRNA secondary structure. After optimization, Codon Adaptation Index (CAI) value was improved from 0.75 to 0.83, meanwhile energy of mRNA secondary structure was increased from -400.1 to -86.8 kcal/mol. This synthetic DNA was under control by phage T7 promoter in the expression vector pET-15b and transformed into the E. coli BL21 (DE3) strain. Inducers such as isopropyl beta-D-thiogalactoside (IPTG) and lactose were compared by activity at different inducing time. The activity of PDOR after codon optimized was 385.4 +/- 3.6 U/mL, which was almost 5-fold higher than wild type (82.3 +/- 1.5 U/ml) under the flask culture at 25ºC for 10 hrs. Then his-tagged enzyme was separated by using Ni-IDA column. The favorite environment for enzyme activity was at 5°C and pH 10.0, PDOR showed a certainly stability in potassium carbonate buffer for 2 hrs at diverse temperatures, enzyme activity was significantly improved by Mn2+.