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 %

The Situation of Antibiotic Resistance in Klebsiella Pneumoniae and Carbapenemase-Producing Klebsiella Pneumoniae in Vietnam: A Cross-Sectional Study

Objective: Klebsiella pneumoniae (K. pneumoniae) is one of the most prevalent human pathogens. Carbapenemaseproducing klebsiella pneumoniae (CPKP) has recently developed significant antibiotic resistance, not just to carbapenem antibiotics but also to the majority of other currently available antibiotics. Prior to this point, there have been few international studies or publications on the situation of CPKP in Vietnam. Hence, this study was conducted to determine the antibiotic resistance of K. pneumoniae and CPKP strains in Can Tho, Vietnam.  Material and Methods: In total, 345 K. pneumoniae strains were isolated. Antibiotic susceptibility was assessed via an automated microbiological system. A modified carbapenem inactivation assay was applied to identify CPKP strains, followed by the use of the MASTDISCS combi Carba plus disc system to classify certain carbapenemases.  Results: Of the 345 K. pneumoniae strains, 110 represented an isolation rate of 31.9%. There was a significant correlation (p-value<0.05) between the specimen type, hospital unit and CPKP ratio. All the examined CPKP strains exhibited complete resistance to penicillin and cefazolin. The CPKP strains were also significantly more resistant to PTZ, cefepime, ciprofloxacin and imipenem than the non-CPKP strains (p-value<0.05). Amikacin, gentamicin and TMP/SMX have been shown to be effective in treating patients infected with CPKP strains.  Conclusion: CPKP accounts for 31.9% of all K. pneumoniae infections. K. pneumoniae and CPKP exhibited the highest levels of resistance to ampicillin, cefazoline, ciprofloxacin, ceftriaxone and ceftazidime. Amikacin, gentamicin and TMP/ SMX were the least resistant antibiotics tested

KHẢ NĂNG KHÁNG NẤM Colletotrichum sp. GÂY BỆNH THÁN THƯ TRÊN XOÀI SAU THU HOẠCH CỦA DỊCH NGOẠI BÀO Streptomyces murinus NARZ

Anthracnose, caused by Colletotrichum spp., is among the most prevalent postharvest diseases affecting mango fruit. In this study, the strain Streptomyces murinus NARZ was used to assess its antifungal efficacy against Colletotrichum gloeosporioides D3, which was isolated from mango fruit infected by anthracnose, by measuring the fungal colony diameter in vitro. The results demonstrated that cell free culture of S. murinus NARZ, at ratio ranging from 20% to 50%, exhibited a superior antifungal effect against C. gloeosporioides D3 in PDA medium, achieving a 74.46% inhibitory effect at the ratio of 50%, surpassing the performance of Nystatin (10 µg/mL) or Erythromycin (30 µg/mL). The antifungal ability of cell free culture of S. murinus NARZ against C. gloeosporioides D3 is maintained when treated at temperatures from 30 °C to 121 °C and pH from 3 to 9. Cell free culture of S. murinus NARZ treated at 30 °C and pH = 5 has the best antifungal effect against C. gloeosporioides D3.Bệnh thán thư do nấm Colletotrichum sp. là bệnh gây hại phổ biến trên xoài sau thu hoạch. Trong nghiên cứu này, chủng xạ khuẩn Streptomyces murinus NARZ được sử dụng để đánh giá khả năng kháng nấm Colletotrichum gloeosporioides D3 được phân lập từ quả xoài nhiễm bệnh thán thư thông qua đường kính tản nấm ở điều kiện in vitro. Kết quả cho thấy, dịch ngoại bào của chủng xạ khuẩn S. murinus NARZ ở tỷ lệ từ 20–50% có tác dụng kháng nấm C. gloeosporioides D3 tốt hơn mẫu bổ sung thuốc diệt nấm Nystatin                         (10 µg/mL) hay kháng sinh Erythromycin (30 µg/mL) trong môi trường PDA, và đạt hiệu lực ức chế 74,46% ở tỷ lệ 50%. Khả năng kháng nấm C. gloeosporioides D3 của dịch ngoại bào chủng xạ khuẩn S. murinus NARZ duy trì khi xử lý ở nhiệt độ từ 30 °C đến 121 °C và pH từ 3 đến 9. Dịch ngoại bào của chủng xạ khuẩn S. murinus NARZ được xử lý ở 30 °C và pH = 5 có tác dụng kháng nấm C. gloeosporioides D3 tốt nhất.            

Impact of equity structure on risk of financial distress in Vietnam

This study aims to evaluate the impact of transparency of budget structure on risk of getting into financial distress in Vietnam. The article uses data regarding equity proportion from the financial reports of business entities on Hanoi Stock Exchange (HNX), divided into four main categories, namely large ownership, institutional ownership, managerial ownership, and state ownership ratio, to find the relation between the allocation of equity and the chance a company having financial failure. From the mentioned information, the research attempts to explain the relations, as well as suggestions for companies to prepare and avoid financial distress from an equity structure perspective. Results from the study’s sample show insignificant correlations between the share of owners and financial distress situation of a company, which plays a part to help the overall estimation of risk in businesses as a whole

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