Expression, purification and evaluation of recombinant L-asparaginase inmehthylotrophic yeast Pichia pastoris: Expression, purification and evaluation of recombinant L-asparaginase in mehthylotrophic yeast Pichia pastoris: Research article

L-asparaginase (EC 3.5.1.1), a therapeutic enzyme used in the treatment of childhood acute lymphoblastic leukemia (ALL). Hence, the goal of this work is study the expression and evaluation of hydrolysis activity of native sequence (X12746) encoding for L-asparaginase from Erwinia chrysanthemi NCPBB1125 in the popular expression system Pichia pastoris. The sequence of asn encoded for mature protein was expressed in P. pastoris SMD1168 and X33. SDS-PAGE analysis showed recombinant L-asparaginase was secreted efficiently. Stable and high hydrolysis activity of extracellular L-asparaginase in P. pastoris SMD1168 making it a potential candidate to produce recombinant protein. After purification, a specific band whose appearance approximately 45 kDa indicating the glycosylated protein with specific activity by 6.251 Umg-1 and about 3 folds purifications.L-asparaginase (EC 3.5.1.1), một loại enzyme được sử dụng trong điều trị bệng ung thư bạch cầu mãn tính ở trẻ em. Mục tiêu của nghiên cứu này là biểu hiện và đánh giá hoạt tính thủy phân của L-asparaginase mã hóa bởi đoạn gene (X12746) tương ứng từ Erwinia chrysanthemi NCPBB1125 được biểu hiện trong nấm men Pichia pastoris. Gene đã được cắt signal peptide và biểu hiện trong P. pastoris SMD1168 and X33. Qua phân tích kết quả điện di SDS-PAGE của môi trường sau lên men, L-asparaginase tái tổ hợp được tìm thấy trong dịch ngoại bào của P. pastoris. Với khả năng sản xuất protein có hoạt tính cao hơn so với chủng P. pastoris X33, SMD1168 được lựa chọn để biểu hiện L-asparaginase tái tổ hợp. Sau khi tinh sạch, sự xuất hiện của một băng có kích khối lượng phân tử xấp xỉ 45 kDa trên điện di SDS-PAGE cho thấy protein tái tổ hợp đã bị glycosyl hóa với hoạt tính riêng 6.251 Umg-1 và đạt độ sạch 3.471 lần

Optimization of L-asparaginase production from Escherichia coli using response surface methodology

Among the antitumor drugs, bacterial enzyme L-asparaginase has been employed as the most effective chemotherapeutic agent in pediatric oncotherapy especially for acute lymphoblastic leukemia. In previous study, the L-asparaginase from Erwinia chrysanthermy was expressed in Escherichia coli BL21(DE3). The recombinant L-asparaginase was produced from recombinant E.coli BL21(DE3) under different cultivation conditions (inducer concentration, inoculum concentration and KH2PO4 concentration). The optimized conditions by response surface methodology using face centered central composite design. The analysis of variance coupled with larger value of R2 (0.9) showed that the quadratic model used for the prediction was highly significant (p 0.05). Under the optimized conditions, the model produced L-asparaginase activity of 123.74 U/ml at 1.03 mM IPTG, 3% (v/v) inoculum and 0.5% (w/v) KH2PO4. Recombinant protein was purified by two step using gel filtration and DEAE chromatography. The purified L-asparaginase had a molecular mass of 37 kDa with specific activity of 462 U/mg and identified by MALDI-TOF mass spectrometry. Results of MALDI-TOF analysis confirmed that recombinant protein was L-asparaginase II. Recombinant L-asparaginase has antiproliferative activity with K562 cell line. In conclusion, this study has innovatively developed cultivation conditions for better production of recombinant L-asparaginase in shake flask culture

COUNTERFEITS AND THEIR COSTS

Counterfeiting is increasing and becoming a complicated issue across different countries in the world and Vietnam is not exceptional, so the policy makers and managers always try to find ways to face with the counterfeiting and reduce counterfeit products in the market. This paper attempts to investigate determinants that impact on consumers’ attitude toward non-deceptive counterfeit products and behavioral intention to purchase them. Using a data set collected from a sample of 176 consumers we found that social cost has an impact on consumers’ attitude and purchase intentiontoward counterfeit products. Moreover, the result indicates that intention to buy counterfeit products is influenced by consumers’ attitude toward these products. These findings suggest that companies should rely on the social cost as the main component of marketing communication messages to discourage consumption of fake products by implying the seriously harmful consequences of these goods to society and economy

Gender income gap in Vietnam in the 2000s : evidence from household surveys

This paper investigates the determinants and characteristics of changes in the gender wage gap between 2004 and 2010 in Vietnam. Labour force structure, employment by gender, education, and skill level, labour force participation, types of enterprises, geographical area, and wage structure are key determinants analyzed in this study. Results reaffirm that traditional concepts and social bias towards women prevent their access to education and training, selection of occupations, and opportunities to improve professional and technical qualifications. Policy implications are reviewed

Distribution and Characteristics of Microplastics in Nhue - Day River Basin, Vietnam

The prevalence of microplastics (MPs) in the environment has had a significant impact on ecosystems and posed a major threat to human health. This study investigated the distribution and characteristics of MPs in the Nhue - Day River basin in Vietnam, which is a critical source of biodiversity and used to support the economic growth of about 12 million people. The effect of seasonal variation and anthropogenic activities on the MP abundance was assessed. The findings revealed that the MPs abundance was significant in this study area. The average abundance of MPs in the dry season (754 items/m3) was insignificantly higher than that in the rainy season (706 items/m3) with n=9. The range in the abundance of MPs in the dry and rainy seasons was 49-2,827 and 400-1,133 items/m3, respectively. Microplastics in fiber forms were dominant in both seasons. The majority of the collected MPs were in the 0.5-2.0 mm size range, varying from 71% to 100% of the total MPs depend on sampling point. The total percentage of MPs size 0.3-0.5 mm in the dry season was 56.97% compared to 119.85% in the rainy season, indicating that the MPs were broken into smaller pieces due to UV exposure and weather conditions. Colored items occupied the majority of the MPs. This study can be used to gain a better knowledge of MP pollution in Vietnam’s river water

EFFECT OF MODIFIED ATMOSPHERE PACKAGING (MAP) AND POSTHARVEST TREATMENTS ON QUALITY OF LITCHI FRUITS DURING STORAGE

In this article, effect of modified atmosphere packaging (MAP) and different postharvest treatments on quality of litchi (Litchi chinensis Sonn.) fruit was investigated. Quality indexes of litchi during cold storage at 4 ± 1 oC were measured in terms of decay, total soluble solids, titratable acidity, color, anthocyanin content and incidence of microbiological infection. These indexes were determined at harvest and 7, 14, 21, 28 and 35 days after storage. The results suggested that after 35 days of storage, the pericarp browning and fruit quality deterioration can be improved compared to the control by dipping fruit is hot water at 47 oC in 7 min., followed by oxalic acid solution (pH = 3 in 6 min.) and finally packed in MAP bag (LDPE, thickness of 30 µm incorporated 3-5 % silica additive) and stored at 4 ± 10C and relative humidity of 90 %

ĐIỆN CỰC NANO CẤU TRÚC 3D - PHÂN LỚP DỊ THỂ CỦA CdS/ZnO/Pt/WO3 TRONG VIỆC NÂNG CAO HIỆU SUẤT TÁCH NƯỚC QUANG ĐIỆN HÓA

In this work, we report the synthesis of the hierarchical structure of a CdS/ZnO/Pt/WO3 electrode for photoeletrochemical water splitting application. The photoanode was synthesized via the hydrothermal and atomic layer deposition methods. The morphological and structural properties of CdS/ZnO/Pt/WO3 nanoplates were carefully investigated by using SEM, TEM, and XRD techniques. The CdS/ZnO/Pt/WO3-based photoelectrode has a photocurrent density of 8,5 mA·cm-2 and a photoconversion efficiency of 7.9% at a supplied potential of –0,85 V in a 0.5 M Na2S solution. This photocurrent density is twice higher than that of the CdS/ZnO/FTO electrode. Due to built-in potential and efficiently collecting the photo-carriers generated from the ZnO/CdS heterojunction under illumination, the CdS/ZnO/Pt/WO3 electrode exhibits enhanced performance of the photoelectrochemical cell. This is a promising approach to the synthesis of heterojunction layers of semiconductor together with nanostructures for fabricating photoelectrodes of the photoelectrochemical cell to enhance hydrogen production efficiency.Trong bài báo này, chúng tôi nghiên cứu chế tạo điện cực có cấu trúc 3D phân lớp dị thể (cây – cành – nhánh) CdS/ZnO/Pt/WO3 ứng dụng cho tách nước quang điện hóa. Điện cực được tổng hợp bằng phương pháp thủy nhiệt và lắng đọng lớp nguyên tử. Hình thái học, cấu trúc tinh thể, và thành phần nguyên tố của điện cực này được nghiên cứu bằng kính hiển vi điện tử quét (FE–SEM), kính hiển vị điện tử truyền qua (HR–TEM) và nhiễu xạ tia X (XRD). Nghiên cứu tính chất quang điện hóa của cấu trúc CdS/ZnO/Pt/WO3, chúng tôi thu được mật độ dòng quang điện là 8,5 mA·cm-2 và hiệu suất chuyển đổi năng lượng ánh sáng mặt trời thành năng lượng hydro 7,9 %% tại thế cung cấp –0,85 V trong dung dịch chất điện ly Na2S với nồng độ 0,5 mol/L. Cấu trúc 3D phân lớp này có mật độ dòng quang điện của điện cực cao hơn gấp hai lần so với các cấu trúc CdS/ZnO trên điện cực thủy tinh phủ oxit thiếc pha tạp bằng flo. Đây là một hướng tiếp cận rất hứa hẹn tổng hợp các cấu trúc nano phân lớp dị thể nhằm nâng cao hiệu quả sản xuất hydro

Genetic variation and outcrossing rate of Dipterocarpus dyeri in the Tan Phu tropical rain forest (Dong Nai), Vietnam

Dipterocarpus dyeri (Dipterocarpaceae) is widely distributed in lowland rainforests in southeastern Vietnam. Due to over- exploitation and habitat destruction in the 1980s and 1990s, this species is listed as threatened. Understanding the genetic variation and mating rate among D. dyeri population that occurs in forest patches is necessary to establish effectively conservation strategies for this species. To conserve the species in tropical forests, genetic diversity and mating rate were investigated using eight microsatellites (single sequence repeat, SSR) as markers. All of the eight loci were polymorphic. A total of 36 different alleles were observed across the loci screened. The SSR data indicated high genetic diversity (NA = 4.5; HO = 0.542 and HE = 0.667) and high inbreeding value, FIS= 0,182. The mating system parameters were determined using the mixed mating model and the results indicated high outcrossing rate (tm=0.81 and ts=0.675) and lowselfing rate (0.19). Difference of tm-ts value indicated that inbreeding contributed to selfing rate for this species in the Tan Phu tropical rain forest. The results reflected that D. dyeri habitat in this area has been restored and the number of individuals was high, about 500 individuals. However, seedlings were not found so far in this study. These results indicated the importance of conserving of the genetic resources of Dipterocarpus dyeri species in the Tan Phu rain forest. The conservation strategy should include an establishment of an ex-situ conservation site with new big population for this species from all genetic groups, which might improve its fitness under different environmental stresses. 

Reasons for Increased Caesarean Section Rate in Vietnam: A Qualitative Study among Vietnamese Mothers and Health Care Professionals.

The Caesarean section rate in urban Vietnam is 43% in 2014, which is more than twice the recommended rate (10%-15%) by the World Health Organization. This qualitative study aims to identify the perceptions of pregnant mothers and health care professionals on the medical and social factors related to the increased Caesarean section rate in Vietnam. A qualitative descriptive study was conducted among pregnant mothers and healthcare professionals at two public hospitals in Nha Trang city. A content analysis was adopted in order to identify social and medical factors. As a result, 29 pregnant women and 19 health care professionals were invited to participate in the qualitative interviews. Private interviews were conducted with 10 women who wished to have a Caesarean section, and the others participated in focus group interviews. The main themes of the social factors were 'request for Caesarean section,' 'mental strain of obstetricians,' and 'decision-making process.' To conclude, this qualitative study suggests that there were unnecessary caesarean sections without a clear medical indication, which were requested by women and family members. Psychological fear occurred among women and family, and doctors were the main determinants for driving the requests for Caesarean section, which implies that education and emotional encouragement is necessary by midwives. In addition, a multi-faced approach including a mandatory reporting system in clinical fields and involving family members in antenatal education is important

Chemical composition and cytotoxic activity of the essential oils of Cymbopogon citratus L. Grown in phu tho province

Culms and leaves of Cymbopogon citratus L. were collected from two regions of Phu Tho province (Thanh Son and Phu Ninh) and used as materials for essential oil extraction. Oils obtained were steam-distilled, analyzed for chemical composition and evaluated for cytotoxic activity against three different cancer cell lines. The GC/MS analysis showed that citral is the major content of the steam-distilled essential oils which was found in the range of 64.15-76.22%. Camphene was found only in culm oils of both regions but it was not detected in the leaf oils. Interestingly, the isomer forms of ocimene present at higher content in the culm oils than in the leaf oils whereas myrcene content in the leaf oils is higher than that in the culm oils. In a cytotoxicity test, four essential oils of culms and leaves of C. citratus from Thanh Son and Phu Ninh showed potent activity against A549 (human lung carcinoma) cell line with the IC50 values ranging from 4.01±0.39 to 6.3±0.54 µg/ml. The essential oils (culms and leaves) from Phu Ninh exhibited moderate effects on the Hela (human cervical adenocarcinoma) cells with the IC50 values of 19.43±1.16 and 42±2.41 µg/ml, respectively. However, they were inactive against the human hepatocellular carcinoma Hep3B cell line. The essential oils from Thanh Son exhibited potent cytotoxic activity against Hela and Hep3B cell lines with the IC50 values ranging from 1.18±0.26 to 8.91±0.32 µg/ml. The results indicated that the essential oils of C. citratus from Thanh Son, Phu Tho could be considered as a promising candidate for the natural sources of anticancer agents