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

Hematological parameters of red tilapia (Oreochromis sp.) fed lemongrass essential oil (Cymbopogon citratus) after challenge with Streptococcus agalactiae

The study involved feeding lemongrass essential oil (LEO) supplements to red tilapia (Oreochromis sp.) at concentrations including Control - 0 mg, T1 – 200 mg, T2 – 300 mg, and T3 – 400 mg per kg of feed. The research investigated changes in hematological (HCT, Hb, RBC, WBC & thrombocytes) and erythrocyte’s morphological (major/minor axis; perimeter, and area of erythrocyte) parameters before infection, 5- and 10-days post-infection (DPI). According to analytical findings, a diet containing LEO enhanced the synthesis of both erythrocytes and leukocytes in the peripheral blood of red tilapia after 20 days of being used. Therefore, the indicators of this group of fish showed better performance than those that did not use LEO supplement five days after bacterial infection. Fish fed 200 mg/kg of LEO after being challenged with S. agalactiae for ten days showed an improved effect on red blood cell production. White blood cells decreased at all concentrations because of citral’s immunomodulatory properties

Optimization of Total Flavonoid Extraction From the Helicteres hirsuta Lour. Roots by Bath Ultrasound Assisted method and cytotoxic activities of these Flavonoids

This study was carried out to optimize the various approaches to analyze the effects of various variables on the total flavonoid content extraction from the roots of Helicteres hirsuta L. The existence of various compounds in the methanol fraction was accessed by using LC-MS/MS analysis. The results of the study identified the ideal parameters such as times (30 minutes); methanol solvent concentration (50%); ultrasonic frequency (12 Hz); and material/solvent ratio [1:30 (w/v)] for extracting the highest total flavonoids from the roots of H. Hirsuta. The study's results suggested that the total flavonoid value was 3.52684 (mg Catechin/g extract). The verified experiment obtained an actual value of 5.205 (mg Catechin/g extract). Further, the results of the study suggested the presence of 20 compounds of a flavonoid nature (66.667%) appearing in the purified methanol fractional extract. These compounds can inhibit DPPH free radicals at 50%, with an IC50 value of 536.760 g/mL, and they also have inhibitory activity on the growth of cancer cell lines with IC50 values ranging from 115.81 and 219.17g/mL. The human leukemia cell line (HL-60) exhibits the most significant cytotoxic response to a methanol extract from H. hirsuta root with an IC50 value of 115.81 g/mL

VIETNAMESE STUDENT RESEARCHERS’ EXPECTATIONS OF THEIR SUPERVISOR AND SUPERVISION PROCESS

In Vietnam, scientific research is no longer just the work of scientists, graduate students, scholars, or lecturers; tertiary students are also encouraged to conduct scientific research. Therefore, the scientific research work of students receives more attention from educators. The research on carrying out scientific research of students is also therefore increasing. However, researchers do not seem to have paid enough attention to the role of supervisors during the supervision process. The evidence is that there are few studies on supervisors in Vietnam. Therefore, this study was conducted to learn about the role of supervisors from the student's perspective and expectations. Specifically, this study was conducted quantitatively with the use of a questionnaire consisting of 49 questions with a 5-point Likert scale. A total of 100 English-major students at a university in Southwest Vietnam participated in this study by answering the questionnaire. The results from the questionnaire show that students had high expectations from their supervisors. Specifically, students expect their supervisor to be someone who respects their opinions, has good scientific research knowledge, can give constructive comments, and is always willing to help them when needed. Based on research findings, supervisors are encouraged to participate in professional development training related to scientific research to improve their research knowledge and skills. Along with that, supervisors need to be aware of their role during the process of guiding students to do scientific research.  Article visualizations

TỔNG HỢP VẬT LIỆU Ni/UiO-66 THEO PHƯƠNG PHÁP TRỰC TIẾP VÀ GIÁN TIẾP

An archetypal metal-organic framework, UiO-6,6, synthesized with the solvo-thermal method, has a large specific surface area of 1071 m2·g–1. This material was modified with NiCl2 in the direct (Nix(tt)/UiO-66) and indirect (Nix(gt)/UiO-66) methods. The two modified materials were characterized by using powder X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. Their crystalline and chemical structure is not much different. However, the thermal and porous properties differ from each other.UiO-66 là họ vật liệu khung hữu cơ kim loại tổng hợp bằng phương pháp nhiệt dung môi có diện tích bề mặt riêng lớn (1071 m2·g–1). Vật liệu UiO-66 này được biến tính bằng NiCl2 theo phương pháp trực tiếp (Nix(tt)/UiO-66) và gián tiếp (Niy(gt)/UiO-66). Kết quả đặc trưng hai vật liệu biến tính này bằng nhiễu xạ tia X, hiển vi điện tử quét và phổ hồng ngoại khác nhau không đáng kể. Tuy nhiên, phân tích nhiệt trọng lượng và đẳng nhiệt hấp phụ – khử hấp phụ N2 cho thấy có sự khác nhau giữa các phương pháp tổng hợp

SEASONAL VARIATION OF PHYTOPLANKTON FUNCTIONAL GROUPS IN TUYEN LAM RESERVOIR, CENTRAL HIGHLANDS, VIETNAM

Seasonal changes in freshwater phytoplankton assemblages at Tuyen Lam Reservoir in the Central Highlands of Vietnam were classified into 23 functional groups based on physiological, morphological, and ecological characteristics. A total of 168 species were recorded during 10 surveys from 2015 to 2019 at 7 sampling sites, with Chlorophyta dominating in number of species. Phytoplankton abundance varied from 0.18×105 to 21.2×105 cells/L during the study period, mainly due to cyanobacteria. Seven of the 23 functional groups were considered to be dominant (relative density > 5%).  The dominant functional groups were groups M and G in the dry season and groups M, G, P, and E in the rainy season. Group M (Microcystis aeruginosa) was the most common in both seasons, while group P (Closterium, Staurastrum, Aulacoseira), group E (Dinobryon, Synura), and group G (Sphaerocystis, Eudorina) were more common in the rainy season. The Shannon diversity index (H¢) showed that phytoplankton communities were relatively diverse and that most of the study sites were lightly polluted. However, the ecological status has deteriorated at some locations due to the overgrowth of group M, leading to eutrophication in this reservoir. This study highlights the usefulness of functional groups in the study of seasonal changes in phytoplankton dynamics. Functional groups are applied for the first time at Tuyen Lam Reservoir and can be used to predict early-stage cyanobacterial blooms in future studies

Genetic characteristics of Panax vietnamensis Ha & Grushv. populations based on ssr

The results of genetic analysis of two Panax vietnamensis populations, collected in Tac-ngo ginseng garden, Tra Linh commune, Quang Nam Province and Mang ri ginseng garden, Kon Tum Province, showed that the population of ngoc linh ginseng in Quang Nam has higher alen frequency compared to the Ngoc Linh ginseng population in Kon Tum (AR = 2.27 AR = 2.05). The population of ngoc linh ginseng in Quang Nam has the expected heterozygous frequency (He) higher than the expected heterozygous frequency of the ginseng population in Kon Tum (0.42 0.4). The observed heterozygous frequency (Ho) of the ngoc linh population in Quang Nam was also higher than the observed heterozygous frequency compared to the ngoc linh ginseng population in Kon Tum (0.49 0.43). These results demonstrated that both populations of ngoc linh ginseng in Quang Nam and Kon Tum are maintaining high heterozygous frequencies; self-pollination has not affected to the genetic structure of these both populations yet. However, the population of ngoc linh ginseng in Quang Nam showed a higher level of diversity and heterozygous frequency than the ngoc linh ginseng population in Kon Tum.

Para-Social Interaction and Trust in Live-Streaming Sellers

Live streaming is one of the modern methods that allows sellers to create, transmit, or broadcast some content on the internet in real-time, and it has been used by many small individual merchants. Understanding how live streaming contributes to online consumption is becoming increasingly important in social commerce as the live-streaming industry has grown more and more popular. However, the number of studies on live streaming is still quite limited in Vietnam. Therefore, this research will look at the mechanism that enables live streaming to boost customer trust in streamers. Using PLS-SEM on a sample of 360 respondents who viewed selling live streams on social network sites in Vietnam, we discovered that other members' endorsement, value similarity, hedonic value, and utilitarian value contribute to good para-social interaction. Next, utilitarian and hedonic values, streamer product expertise, and para-social interaction all positively affect trust in the streamers. The findings could help live-streaming sellers better understand their social interactions with viewers, resulting in increased customer trust. Doi: 10.28991/ESJ-2023-07-03-06 Full Text: PD

Teaching English vocabulary to young learners through total physical response method

This study attempts to investigate the effect of the Total Physical Response (TPR) Method on vocabulary retention and explore the young learners’ attitudes toward it. It involved sixty two English young learners (YLs) aging from 10 to 11. All of them were attending English classes at Viet Uc English Language Center (henceforth called VUC) in Bien Hoa City where the current study was conducted. Both quantitative and qualitative data was obtained through the three instruments, namely pre- and post-test and interview. Descriptive statistics was employed for data analysis. The results revealed that TPR had effect on the YLs’ vocabulary knowledge through an increase in their vocabulary retention after they underwent the treatment. Similarly, the findings of the study also revealed that the YLs had positive attitudes toward the use TPR in vocabulary teaching and learning. This study is expected to shed light to the implementation of teaching vocabulary methods in the VUC context and other similar contexts