Agrobacterium tumefaciens gene transfer to Casuarina glauca : a tropical nitrogen-fixing tree

Transgenic calli of the tropical tree #Casuarina glauca were produced using #Agrobacterium tumefaciens-mediated gene transfer. Hypocotyls, cotyledons and epicotyls were excised from 30-60-day old #Casuarina seedlings and cocultivated with #Agrobacterium strain C58C1(pGV2260) containing the binary vector BIN19GUSINT. Transformed calli were selected on nutrient medium supplemented with 0,5 microM NAA, 2,5 microM BA and 50 mg/l kanamycin. Some of the factors influencing T-DNA transfer to #C. glauca$ explants were studied. Optimal transformation rates were obtained when explants from 45-day old seedlings were cocultivated for 3 days in the presence of 25 microM acetosyringone. Transgenic buds differentiated on 10% of the calli grown on transformed epicotyls. Evidence for genetic transformation was obtained by beta-glucuronidase assay, PCR and Southern hybridization. (Résumé d'auteur

Creep and relaxation functions of a heterogeneous viscoelastic porous medium using the Mori-Tanaka homogenization scheme and a discrete microscopic retardation spectrum

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Comparison stripmap COSMOS SkyMed X-band and tops Sentinel-1 C-band in estimating ground subsidence using irstea TOMOSAR platform: Ho Chi Minh City case study

International audienceThe objective of this paper is to provide a better understanding of Persistent Scatterers Interferometry (PSI) capabilities in subsidence estimations of TOPSAR Sentinel-1 data. This work has presented an advanced PSI analysis, to provide unprecedented spatial extent and continuous temporal coverage of the subsidence in Ho Chi Minh City by using 49 stripmap Cosmos SkyMED (CSK) X-band and TOPS Sentinel-1 Cband 23 images acquired from 2014 to 2016. The analysis was carried out by using the Irstea TomoSAR platform, which supports the entire processing from SAR, Interferometry, Polarimetry, to Tomography (so called TomoSAR). The study shows that the performance of stripmap CSK and TOPS Sentinel-1 is quite similar and effective to detect the subsidence phenomena. Subsidence is most severe in the Holocene silt loam areas along Sai Gon river and in the Southwest of the city, with the maximum value up to-30 mm/yr, similar with the previous study using ALOS PALSAR. Index Terms-Synthetic Aperture Radar, TOPS Sentinel-1, Comos SkyMED, TomoSAR platform, service as demand, subsidence, Ho Chi Minh City, Vietnam

Carbon and graphene quantum dots: A review on syntheses, characterization, biological and sensing applications for neurotransmitter determination

Neuro-transmitters have been considered to be essential biochemical molecules, which monitor physiological and behavioral function in the peripheral and central nervous systems. Thus, it is of high pharmaceutical and biological significance to analyze neuro-transmitters in the biological samples. So far, researchers have devised a lot of techniques for assaying these samples. It has been found that electro-chemical sensors possess features of robustness, selectivity, and sensitivity as well as real-time measurement. Graphene quantum dots (GQDs) and carbon QDs (CQDs) are considered some of the most promising carbon-based nanomaterials at the forefront of this research area. This is due to their characteristics including lower toxicity, higher solubility in various solvents, great electronic features, strong chemical inertness, high specific surface areas, plenty of edge sites for functionalization, and versatility, in addition to their ability to be modified via absorbent surface chemicals and the addition of modifiers or nano-materials. Hence in the present review, the synthesis methods of GQDs and CQDs has been summarized and their characterization methods also been analyzed. The applications of carbon-based QDs (GQDs and CQDs) in biological and sensing areas, such as biological imaging, drug/gene delivery, antibacterial and antioxidant activity, photoluminescence sensors, electrochemiluminescence sensors and electrochemical sensors, have also been discussed. This study then covers sensing features of key neurotransmitters, including dopamine, tyrosine, epinephrine, norepinephrine, serotonin and acetylcholine. Hence, issues and challenges of the GQDs and CQDs were analyzed for their further development. This journal is © 2020 The Royal Society of Chemistry

Recent advances in the aptamer-based electrochemical biosensors for detecting aflatoxin b1 and its pertinent metabolite aflatoxin m1

The notable toxicological impacts of aflatoxin B1 (AFB1) and its main metabolite, aflatoxin M1 (AFM1), on human being health make the evaluation of food quality highly significant. Due to the toxicity of those metabolites�even very low content in foodstuffs�it is crucial to design a sensitive and reliable procedure for their detection. Electrochemical aptamer-based biosensors are considered the most encouraging option, based on multi-placed analysis, rapid response, high sensitivity and specificity. The present review specifically emphasizes the potential utilization of the electrochemical aptasensors for determining the AFM1 and AFB1 with different electrodes. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Genetic transformation of the actinorhizal tree Allocasuarina verticillata by Agrobacterium tumefaciens

We have developed an efficient transformation system for the tropical actinorhizal tree #Allocasuarina verticillata using #Agrobacterium tumefaciens mediated gene transfer. Mature zygotic embryos were inoculated with the disarmed strain C58C1 carrying, in the binary vector BIN19, the nptll gene, providing kanamycin resistance as a selectable marker, and the reporter gene beta-glucuronidase containing an intron. The transformed embryos were cultivated on nutrient medium supplemented with 0,5 microM NAA, 2,5 microM BA, 100 mg/l kanamycin and 250 mg/l cefotaxime. After 2 months, a 21% transformation frequency was obtained. Within 6-9 months, transgenic plants were recovered from 70% of the transformed calli. The presence of the trangenes was demonstrated by PCR analysis and by the expression of the beta-glucuronidase; integration of the T-DNA was confirmed by Southern hybridization. More than 100 transgenic plants from a total of 23 independent events have been successfully established in soil. The possibility to obtain nitrogen-fixing nodules after inoculation of transgenic #A. verticillata$ plants by the actinomycetal strain of Frankia Allo2 was established. (Résumé d'auteur