Effects of dietary tryptophan on cannibalism, survival and growth of Wallago attu (Bloch & Schneider, 1801) juveniles

This study aims to evaluate the effects of supplemented commercial diets with tryptophan (TRP) on plasma serotonin, cannibalism, survival rate, and growth of Wallago attu (helicopter catfish). After one week of acclimation, 3,200 juveniles of helicopter catfish (BW = 2.5 ± 0.27 g, total length = 5.6 ± 0.43 cm) were randomly assigned for the experiment in fifteen plastic tanks (200 L). The experiment was conducted with five treatments (CT – 0 g TRP/kg – control group, T1 – 5 g TRP/kg, T2 – 10 g TRP/kg, T3 – 20 g TRP/kg, and T4 – 40 g TRP/kg) in a completely randomized design with three replications for four weeks. The results from the enzyme-linked immunosorbent assay reveal that TRP-supplemented diets effectively increased the serotonin level (5-HT) in the plasma of the catfish. The serotonin level increased with the dose of TRP added to the feed. Furthermore, a higher TRP level significantly decreased cannibalism and improved the final survival of the fish. However, the fish’s growth rate among treatments T1, T2, T3, and T4 was not significantly different, but there was a statistical difference between the experimental treatments and the CT treatment. The findings of this study suggest that TRP could be supplemented at a dose of 20 g·kg–1 to the feed to reduce cannibalism and improve the final survival of helicopter catfish

CHANGES IN PLASMA LEVELS OF STEROID HORMONES DURING SEXUAL MATURATION OF MALE HELICOPTER CATFISH (WALLAGO ATTU) IN CAPTIVITY

In order to provide reliable indicators of the spawning season of captive helicopter catfish (Wallago attu), this study evaluated the temporal variation in gonadosomatic index (GSI), plasma levels of testosterone (T), and 11-ketotestosterone (11-KT) in male broodstock in captivity. GSI was estimated as the percentage of the relative weight of testis to total body weight. Plasma levels of sex steroids were determined by enzyme-linked immunosorbent assay (EIA). Testis samples were dehydrated and embedded in paraffin, then sectioned at 5 μm thickness. The highest level of T (402.1 ± 16.7 pg/mL) was found in June, followed by a peak in 11-KT level (76.9 ± 4.7 pg/mL) in May. Testes containing the highest concentrations of spermatozoa were observed from June to August. The GSI of males increased significantly from January to June and peaked in July (2.14%). Taken together, we conclude that the spawning season of captive helicopter catfish occurs from June to August. These results will contribute to the basic knowledge of the reproductive biology of helicopter catfish, which can be useful in artificial breeding

FACTORS RELATED TO THE AWARENESS AND BEHAVIOR OF MARIJUANA USE AMONG UNIVERSITY STUDENTS IN CAPITAL HANOI, VIETNAM

Abstract The increasing use of addictive substances, especially marijuana, among university students has increased the burden of disease and social issues. However, the specific data about the prevalence and factors relating to marijuana use among university students is still limited. This study aims to provide the initial research literature about factors affecting the awareness and behavior of marijuana use among university students in Hanoi. The study employed two primary methods: a survey questionnaire and an in-depth interview with a sample of 324 diverse university students. According to research findings, students are generally uncertain about the effects of marijuana and take a neutral stance on its social acceptability. The overall prevalence of marijuana use among university students in Hanoi is 7.4%, of which the rate of use in males is 9.4% and in females is 4.1%. Marijuana use is also influenced by peers' behavior, and parents' false perception of their children's drug prevention capability and marijuana's accessibility may also play a factor

Classification Methods for Mapping Mangrove Extents and Drivers of Change in Thanh Hoa Province, Vietnam during 2005-2018

Mangrove forests have been globally recognised as their vital functions in preventing coastal erosion, mitigating effects of wave actions and protecting coastal habitats and adjacent shoreline land-uses from extreme coastal events. However, these functions are under severe threats due to the rapid growth of population, intensive shrimp farming and the increased intensity of severe storms in Hau Loc and Nga Son districts, Thanh Hoa province. This research was conducted to monitor spatial-temporal changes in mangrove extents using Landsat and Sentinel imageries from 2005 to 2018. Unsupervised and supervised classification methods and vegetation indices were tested to select the most suitable classification method for study sites, then to quantify mangrove extents and their changes in selected years. The findings show that supervised classification was the most suitable in study sites compared to vegetation indices and unsupervised classification. Mangrove forest extents increased by 7.5 %, 38.6 %, and 47.8 % during periods of 2005 - 2010, 2010 - 2015 and 2015 - 2018, respectively. An increase of mangrove extents resulted from national programs of mangrove rehabilitation and restoration during 2005- 2018, increased by 278.0 ha (123.0 %)

Monitoring Changes in Coastal Mangrove Extents Using Multi-Temporal Satellite Data in Selected Communes, Hai Phong City, Vietnam

Mangrove forests are important and known as one of the most productive ecosystems in the tropics. They reduce the impacts of extreme events, provide important breeding grounds for aquatic species and build the resilience of ecosystem-dependent coastal communities. On the contrary, they are also known as one of the most threatened and vulnerable ecosystems worldwide, which have experienced a dramatic decline due to extensive coastal development during the last half-century. Remote sensing techniques have demonstrated a high potential to detect, identify, map, and monitor mangrove conditions and its changes, which is reflected by a large number of scientific papers published on this topic. The aim of this study was to investigate the multi-decadal changes of mangrove forests selected communes in Hai Phong city, North Vietnam, based on using Landsat and Sentinel 2 data from 2000 to 2018. The study used these continuous steps: 1) data pre-processing; 2) image classification using Normalized Difference Vegetation Index; 3) accuracy assessments; and 4) multi-temporal change detection and spatial analysis of mangrove forests. The classification maps in comparison with the ground reference data showed the satisfactory agreement with the overall accuracy was higher than 80.0%. From 2000 to 2018, the areas of mangrove forests in the study regions  increased by 584.2 ha in Dai Hop and Bang La communes (Region 1) and by 124.2 ha in Tan Thanh, Ngoc Xuyen and Ngoc Hai communes (Region 2), mainly due to the boom of mangrove planting projects and good mangrove management at the local community level

The Status of Educational Sciences In Vietnam: A Bibliometric Analysis From Clarivate Web Of Science Database Between 1991 And 2018

Since 2013, Vietnam has implemented a plan to reform the whole education sector. However, there is little understanding on the status of educational research in Vietnam, which may lay the foundation for such plan. Thus, this research aims to analyze the whole picture of educational research from Vietnam, as seen from the Clarivate Web of Science (WOS) database: 215 publications were recorded, ranging from 1991 to 2018. These 215 publications were further analyzed from five perspectives: 1) number of publications by year; 2) research fields and levels of education; 3) top institutions with the highest number of publications; 4) international collaboration; and 5) quality. Some of the most notable results are: 1) the educational sciences in Vietnam have been still under-developed until recently; 2) among different research topics research among educational sciences, some (e.g., Vocational Education and Training or Early Childhood Education) seemed to be overlooked whereas others (e.g., Higher Education and Teaching and Learning) seemed to receive more attention from educational scholars; 3) all the most major education – specialized universities did not appear among the top five institutions with highest number of publications; 4) Australia, Thailand, the USA, New Zealand and China were the countries with the highest number of co-publications with Vietnamese researchers; and 5) The majority of publications belonged to low-ranked journals. Implications would be withdrawn for Vietnamese policymakers, education leaders, educational researchers and teachers in order to adjust their policies and/or action plans; thus, enhancing the performance and impacts of educational research in the future

Can a Short Food Supply Chain Create Sustainable Benefits for Small Farmers in Developing Countries? An Exploratory Study of Vietnam

A number of studies have indicated that short food supply chains could create economic, social, and environmental benefits, but most of those chains were implemented in developed countries. This research aims to find out the characteristics of short food supply chains and their benefits to small farmers in Vietnam, which is a developing country, based on the survey results from 338 small farmers in the third quarter of 2020, with the support of Stata 14 software. The results showed that the short food supply chains in the survey sample in Vietnam were characterized by two main actors: small farmers and distributors. Farmers could sell products flexibly at the local market. There was some initial evidence to prove that these chains helped to stabilize the input, output price, and revenue; formulated sustainable income; and increased the satisfaction and confidence of farmers. They eliminated gender discrimination in rural areas and improved livelihood for ethnic minorities. These chains also enhanced the mindset on green, organic, and clean production of farmers, which in turn created environmental benefits. COVID-19 has posed a negative impact on the income of farmers and made them change their production and sales method. Therefore, the research could suggest some policies to sustainably develop the short food supply chains in Vietnam in the future

Redondoviridae: High Prevalence and Possibly Chronic Shedding in Human Respiratory Tract, But No Zoonotic Transmission

Redondoviridae is a recently discovered DNA virus family consisting of two species, vientovirus and brisavirus. Here we used PCR amplification and sequencing to characterize redondoviruses in nasal/throat swabs collected longitudinally from a cohort of 58 individuals working with animals in Vietnam. We additionally analyzed samples from animals to which redondovirus DNA-positive participants were exposed. Redondoviruses were detected in approximately 60% of study participants, including 33% (30/91) of samples collected during episodes of acute respiratory disease and in 50% (29/58) of baseline samples (with no respiratory symptoms). Vientovirus (73%; 24/33) was detected more frequently in samples than brisaviruses (27%; 9/33). In the 23 participants with at least 2 redondovirus-positive samples among their longitudinal samples, 10 (43.5%) had identical redondovirus replication-gene sequences detected (sampling duration: 35–132 days). We found no identical redondovirus replication genes in samples from different participants, and no redondoviruses were detected in 53 pooled nasal/throat swabs collected from domestic animals. Phylogenetic analysis described no large-scale geographical clustering between viruses from Vietnam, the US, Spain, and China, indicating that redondoviruses are highly genetically diverse and have a wide geographical distribution. Collectively, our study provides novel insights into the Redondoviridae family in humans, describing a high prevalence, potentially associated with chronic shedding in the respiratory tract with lack of evidence of zoonotic transmission from close animal contacts. The tropism and potential pathogenicity of this viral family remain to be determined

Redondoviridae: High Prevalence and Possibly Chronic Shedding in Human Respiratory Tract, But No Zoonotic Transmission

Redondoviridae is a recently discovered DNA virus family consisting of two species, vientovirus and brisavirus. Here we used PCR amplification and sequencing to characterize redondoviruses in nasal/throat swabs collected longitudinally from a cohort of 58 individuals working with animals in Vietnam. We additionally analyzed samples from animals to which redondovirus DNA-positive participants were exposed. Redondoviruses were detected in approximately 60% of study participants, including 33% (30/91) of samples collected during episodes of acute respiratory disease and in 50% (29/58) of baseline samples (with no respiratory symptoms). Vientovirus (73%; 24/33) was detected more frequently in samples than brisaviruses (27%; 9/33). In the 23 participants with at least 2 redondovirus-positive samples among their longitudinal samples, 10 (43.5%) had identical redondovirus replication-gene sequences detected (sampling duration: 35–132 days). We found no identical redondovirus replication genes in samples from different participants, and no redondoviruses were detected in 53 pooled nasal/throat swabs collected from domestic animals. Phylogenetic analysis described no large-scale geographical clustering between viruses from Vietnam, the US, Spain, and China, indicating that redondoviruses are highly genetically diverse and have a wide geographical distribution. Collectively, our study provides novel insights into the Redondoviridae family in humans, describing a high prevalence, potentially associated with chronic shedding in the respiratory tract with lack of evidence of zoonotic transmission from close animal contacts. The tropism and potential pathogenicity of this viral family remain to be determined

The Virome of Acute Respiratory Diseases in Individuals at Risk of Zoonotic Infections

The ongoing coronavirus disease 2019 (COVID-19) pandemic emphasizes the need to actively study the virome of unexplained respiratory diseases. We performed viral metagenomic next-generation sequencing (mNGS) analysis of 91 nasal-throat swabs from individuals working with animals and with acute respiratory diseases. Fifteen virus RT-PCR-positive samples were included as controls, while the other 76 samples were RT-PCR negative for a wide panel of respiratory pathogens. Eukaryotic viruses detected by mNGS were then screened by PCR (using primers based on mNGS-derived contigs) in all samples to compare viral detection by mNGS versus PCR and assess the utility of mNGS in routine diagnostics. mNGS identified expected human rhinoviruses, enteroviruses, influenza A virus, coronavirus OC43, and respiratory syncytial virus (RSV) A in 13 of 15 (86.7%) positive control samples. Additionally, rotavirus, torque teno virus, human papillomavirus, human betaherpesvirus 7, cyclovirus, vientovirus, gemycircularvirus, and statovirus were identified through mNGS. Notably, complete genomes of novel cyclovirus, gemycircularvirus, and statovirus were genetically characterized. Using PCR screening, the novel cyclovirus was additionally detected in 5 and the novel gemycircularvirus in 12 of the remaining samples included for mNGS analysis. Our studies therefore provide pioneering data of the virome of acute-respiratory diseases from individuals at risk of zoonotic infections. The mNGS protocol/pipeline applied here is sensitive for the detection of a variety of viruses, including novel ones. More frequent detections of the novel viruses by PCR than by mNGS on the same samples suggests that PCR remains the most sensitive diagnostic test for viruses whose genomes are known. The detection of novel viruses expands our understanding of the respiratory virome of animal-exposed humans and warrant further studies