Évaluation de la fréquence des micronoyaux et du potentiel clastogène et/ou aneugène du benzo-a-pyrène suite à une exposition in vitro des lymphocytes humains

Le benzo-a-pyrène (BaP) est un cancérogène reconnu pour l'homme, contaminant présent dans notre environnement. Il cause des dommages à l'ADN que nous avons mesurés dans les lymphocytes exposés à de faibles concentrations de BaP, provenant de 20 jeunes volontaires non fumeurs et en santé. Suite à l’exposition, la fréquence des micronoyaux (MN) augmente significativement et décrit une courbe dose-réponse non linéaire, suggérant le déclenchement du processus de détoxification et la réparation de l’ADN. Des différences entre les individus et entre les sexes sont présentes dans la réponse génotoxique produite par le BaP. Le test des aberrations chromosomiques montre que le pourcentage de chromosomes cassés augmente significativement dans les cellules exposées au BaP. Combinés avec l'augmentation de la fréquence des MN, nos résultats confirment l'effet clastogène du BaP déjà rapporté dans la littérature. L’hybridation in situ en fluorescence (FISH) des MN avec une sonde pancentromérique est aussi utilisée pour établir leur mécanisme de formation. La FISH révèle que la majorité des MN formés après une exposition au BaP contient un centromère et plus, ce qui est significativement différent de la condition non exposée. Plus précisément, dans nos conditions expérimentales, les MN induits par le BaP contiennent surtout trois centromères et plus, indiquant également la présence d'un effet aneugène. L'effet clastogène du BaP est relié à son rôle d'initiateur dans la cancérogenèse, alors que l'effet aneugène le relierait à l'étape de progression. Ces résultats sont importants puisque l'exposition aux composés de la classe du BaP est de longue durée (cigarette, air pollué).Benzo-a-pyrene (BaP) is a known human carcinogen, contaminating all spheres of our environment. In human cells, BaP can induce various genotoxic effects on DNA, such as micronuclei (MNs) and chromosomal aberrations (CAs). MNs and CAs are measured in human lymphocytes in vitro exposed to low BaP concentrations, taken from 20 young healthy non-smoking subjects. Following BaP exposure, MN frequency increases significantly and shows a non-linear dose-response curve, suggesting the induction of detoxification process and/or DNA repair. Also, interindividual and sex differences in BaP-induced genotoxic damages are present. CA test shows that chromosome breaks increase significantly in cells exposed to BaP even at low concentrations. Combined to the observed MN frequency increase, our results confirm the clastogenic properties of BaP, as already reported in literature. In addition, fluorescence in situ hybridization (FISH) on MN using a pancentromeric probe is done to assess MN content. FISH reveals that most BaP-induced MNs contain centromeres, and specifically three or more centromeres. This difference is significant when compared to the unexposed condition, and suggest presence of an aneugenic effect. Clastogenic effect of BaP is associated with initiation step of carcinogenesis, while the aneugenic effect would link it with cancer progression. These results could be particularly important because exposure to BaP and other member of its chemical class usually last for decades (smoking, air pollution, etc.), and need to be confirm in future studies

Building a Model of Organizational Activities Experience in Natural Sciences under Stem Education Orientation

STEM educational-oriented Natural Science experience activities are learner-oriented activities Taking learners as the center in all natural science research activities applying engineering technology and mathematics STEM in solving practical problems Based on theoretical research on experiential activities STEM education and the characteristics of Natural Sciences the article studies the educational forces inside and outside the school From there it is proposed to build a model of organizational structure for experiential activities in Natural Sciences oriented toward STEM education The results of this research are meaningful in helping principals see the importance and significance of coordinating educational forces inside and outside the school in organizing experiential activities in Natural Sciences according to orientation STEM education for student

Forms and Factors Affecting Collective Adaptation to Saline Intrusion: A case of Kien Giang Province, Vietnam

Saline intrusion (SI) is causing serious risks for agriculture and coastal life in the Vietnamese Mekong Delta. Maintaining agricultural production under that challenging condition places more tremendous pressure on rural societies. This study aimed to get insight into adaptive adaptation's forms and factors influencing farmers' participation process by applying the social and ecological approach. The research was conducted in An Bien district, Kien Giang province, a province in the Mekong Delta in Vietnam. A mixed-method integrating quantitative and qualitative methods were used to collect data using key informant panel interviews, group discussion, and household survey. The results showed that local farmers had changed the farming system from double rice crops to shrimp-rice models to deal with the impacts of SI. Group response has emerged as the appropriate adaption in both formal and informal forms. The adaptive group plays an essential role in connecting community members, and two forms of adaptation have worked closely to adapt to SI. Factors affecting the informal group related to relatives, households living close to each other; For the formal group, the main factor affecting participation is when joining the group, the members receive benefits from the group. Besides, prestige and having a lot of experience in the leader's production activities affect the official group participation. In addition to the positive factors, two negative factors affect group adaptation: unfavorable farm location and distrus

Factors Affecting the Agricultural Restructuration: A Case of Cham Community in Chau Phu District, An Giang Province, Vietnam

The national policy of agricultural restructuring plays a vital role in adapting to climate change's effects and economic development in the Mekong Delta of Vietnam. Unproductive areas have been converted into other crops with higher efficiency. Drawn by the sustainable livelihoods approach, this article explores the current situation and factors challenging the Cham community in implementing the agricultural restructuring. The mixed method included in-depth interviews, focus group discussions, and a questionnaire survey. The results showed that the Xuong Com Vang longan (Dimocarpus longan) variety has occurred in Khanh Hoa commune for a long time as an indigenous fruit tree of this area. In terms of the farming system, the polyculture system combining fruit trees and upland crops brought more income sources than the monoculture system. The asset abilities of the Cham farmers are various from one to the others. Soil and weather conditions are appropriate for planting. But farm size is small, which is one of the difficulties of developing fruit areas. Human and social assets were good since farmers had enough knowledge to manage the gardens, and a close connection existed among the Cham community. It was not a case of the financial status since a lot of money needs to be invested in the starting year. Therefore, the private loan still exists as one of the farmer's choices. For better future development, land management and financial resource should be considered for better agricultural restructuring aims. To increase farmers' incomes, create production chains helping enterprises and farmers work more efficiently for the better life of Cham gardeners in An Giang province in Vietnam

Invited review. Bond dissociation enthalpies in benzene derivatives and effect of substituents: an overview of density functional theory (B3LYP) based computational approach

In this review, we have mainly focused on the recent computational studies on the bond dissociation enthalpies (BDE) of the X‒H bonds of the para and meta substituted benzene derivatives (3Y-C6H4X‒H and 4Y-C6H4X‒H with X = O, S, Se, NH, PH, CH2, SiH2 and Y = H, F, Cl, CH3, OCH3, NH2, CF3, CN, NO2). In addition, the remote substituent effects on the BDE(X‒H), the radical stability and parent one have also been discussed in terms of the calculated ground state effect, radical effect and total effect. Model chemistry of ROB3LYP/6-311++G(d,p)//B3LYP/6-311G(d,p) can reproduce the BDE values with the accuracy of 1.0‒2.0 kcal/mol. The good linear correlations between Hammett constants and BDE values were discovered for both para and meta substitutions in phenols, thiophenols, benzeneselenols, anilines and phenylposphines with the R-squared lager than 0.94. In contrast, it does not occur in case of toluenes and phenylsilanes.Keywords. Benzene derivatives, density functional theory, bond dissociation enthalpies, substituent effects, radical effect, ground state effect, total effect, Hammett constants

Geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost Mekong Delta, Vietnam

Study region Ca Mau Province (CMP), Mekong Delta (MD), Vietnam. Study focus Groundwater from deep aquifers is the most reliable source of freshwater in the MD but extensive overexploitation in the last decades led to the drop of hydraulic heads and negative environmental impacts. Therefore, a comprehensive groundwater investigation was conducted to evaluate its composition in the context of Quaternary marine transgression and regression cycles, geochemical processes as well as groundwater extraction. New hydrological insights for the region The abundance of groundwater of Na-HCO$_{3}$ type and distinct ion ratios, such as Na$^{+}$/Cl$^{-}$, indicate extensive freshwater intrusion in an initially saline hydrogeological system, with decreasing intensity from upper Pleistocene to deeper Miocene aquifers, most likely during the last marine regression phase 60–12 ka BP. Deviations from the conservative mixing line between the two endmembers seawater and freshwater are attributed to ion-exchange processes on mineral surfaces, making ion ratios in combination with a customized water type analysis a useful tool to distinguish between salinization and freshening processes. Elevated salinity in some areas is attributed to HCO$_{3}$$^{-}$ generation by organic matter decomposition in marine sediments rather than to seawater intrusion. Nevertheless, a few randomly distributed locations show strong evidence of recent salinization in an early stage, which may be caused by the downwards migration of saline Holocene groundwater through natural and anthropogenic pathways into deep aquifers

Groundwater Use Habits and Environmental Awareness in Ca Mau Province, Vietnam: Implications for Sustainable Water Resource Management

The Vietnamese Mekong Delta including Ca Mau province (CMP) is seriously affected by land subsidence. Groundwater over-extraction is considered to be a major driver for this process. To address the reduction of groundwater (GW) extraction as a potential counter measure for further subsidence, this study focuses on understanding the importance of GW in people\u27s life and water using habits as well as their awareness with current environmental problems in Ca Mau. Therefore, GW sampling campaigns and surveys were conducted in all 9 districts of Ca Mau province in 2019 and 2020. The analyzed water samples showed a connection with information from questionnaires and created a general picture of water using habits. GW plays an important role in people\u27s lives, it is used for washing, cooking, drinking and other activities. People use GW for different purposes depending on their perception of water quality. For important and direct health related purposes, such as cooking or drinking, people prepare to treat water more carefully or choose another alternative water resource. The analytical approach to evaluation results based on viewpoints from general to detail helped to dig deeper into people\u27s stories to explain research results with their behavior in each situation. When people are dependent on GW and have no option to use alternative water resources, the importance level of GW in their life increases and their awareness of GW over-extraction becomes less. If people have another water source to use such as tap water (TW), habits of using GW change. This opens up the idea that a potential alternative water will reduce the dependence of people on GW and protect GW from over-exploitation. Besides, people in Ca Mau do not have much awareness of land subsidence or the reason leading to environmental problems. Therefore, raising the awareness of people by well-design education campaigns should be strongly considered

Survey on Vietnamese teachers’ perspectives and perceived support during COVID-19

The COVID-19 pandemic has caused unprecedented damage to the educational system worldwide. Besides the measurable economic impacts in the short-term and long-term, there is intangible destruction within educational institutions. In particular, teachers – the most critical intellectual resources of any schools – have to face various types of financial, physical, and mental struggles due to COVID-19. To capture the current context of more than one million Vietnamese teachers during COVID-19, we distributed an e- survey to more than 2,500 randomly selected teachers from two major teacher communities on Facebook from 6th to 11th April 2020. From over 373 responses, we excluded the observations which violated our cross-check questions and retained 294 observations for further analysis. This dataset includes: (i) Demographics of participants; (ii) Teachers' perspectives regarding the operation of teaching activities during the pandemic; (iii) Teachers' received support from their schools, government bodies, other stakeholders such as teacher unions, and parents' associations; and (iv) teachers' evaluation of school readiness toward digital transformation. Further, the dataset was supplemented with an additional question on the teachers' primary source of professional development activities during the pandemic