DEY, A. | bioRxiv Science

bioRxiv2024

Effects of nano urea on growth and gene expression of Arabidopsis thaliana in hydroponics

IntroductionHydroponics enables precise control over nutrient delivery, optimized water requirements and growing conditions. The combination of nanotechnology and hydroponics paves the way towards sustainable agriculture with less environmental footprints. We investigated the effects of nano urea on the model plant Arabidopsis thaliana in hydroponics. MethodsA growth experiment in a nitrogen-free hydroponic medium compared the effects of a liquid nano urea formulation (NUF) marketed by Indian Farmers Fertilizer Cooperative (IFFCO) to an equimolar bulk urea. Transcriptome analysis identified the molecular mechanisms of growth enhancement. Dynamic light scattering and transmission electron microscopy confirmed NUFs negative surface charge and sub-100 nm size, correlating its uptake and distribution in the plant. Results and discussionA two-week growth in the hydroponic medium with 70 M NUF led to a 20% higher biomass and 16% higher chlorophyll content than a medium with 70 M urea. Higher doses of NUF inhibited growth, whereas higher equivalent urea doses did not. NUF led to the differential expression of more genes than urea at 12 h to seven days of treatment. Nitrogen assimilation, growth, photosynthesis, and stress tolerance genes showed higher transcript levels in NUF than in urea. On the other hand, NUF led to greater suppression of many negative growth-regulating genes. After seven days of treatment, chlorophyll biosynthesis genes got up-regulated, while chlorophyll catabolism genes got down-regulated at higher levels by NUF than by urea, correlating with the higher chlorophyll content of NUF-treated seedlings. In conclusion, NUF outperformed equimolar urea for the growth promotion of A. thaliana at a low concentration in hydroponics, leading to a greater regulation of genes for nitrogen metabolism and chlorophyll biosynthesis. Our results suggest a potential use of NUF as a nitrogen fertilizer for hydroponic agriculture.

plant biology↗

bioRxiv2024

Single-molecule Mapping of Amyloid-β Oligomer Insertion intoLipid Bilayers

The interaction of disease-causing amyloid oligomers with lipid membranes is implicated in their toxicity. However, understanding the membrane interaction of different oligomers, and each constituent monomer in a given oligomer, has remained a challenge. Here we employed a recently developed single-molecule technique, called QSLIP, which can simultaneously determine the stoichiometry and membrane location of individual fluorescent labels on oligomeric membrane proteins. Using QSLIP, we measured the membrane insertion of small amyloid-beta (A{beta}) oligomers of three different isoforms at the single-molecule level, and found that their toxicity is correlated with the depth of penetration of their amino-terminal into the bilayer. Such single-molecule maps provide a detailed assay for measuring the effect of any drug candidate on oligomer-membrane interactions.

biophysics↗