Germination of piriquiti (Adenanthera pavonina L.) under saline stress conditions / Germinação de piriquiti (Adenanthera pavonina L.) sob condições de estresse salinas

 Adenanthera pavonina L. (Piriquiti) is a pioneer Brazilian forest species belonging to the botanical family Fabaceae of characteristics that make it of important economic interest both for its high timber potential, as for ecology and uses as Ornamental plant. Some factors may be limiting to the germination of plant seeds, especially forest, conditions of salt stress can be one of the factors. The present study aimed to show the germination behavior of A. Pavonina when placed under conditions of saline stress, in different levels of NaCl salt, to point to future studies other possibilities of use for the species. The maximum limiting saline concentration found was 2.0% of sodium chloride, below this concentration does not hear statistical difference in the percentage of germination, however, the increase in the saline concentration up to the maximum limit, negatively affected the Germination velocity, levels above 2.0% were not observed germination. 

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Responses of Arabica coffee (Coffea arabica L. var. Catuaí) cell suspensions to chemically induced mutagenesis and salinity stress under in vitro culture conditions

Crop improvement of Coffea arabica L. (coffee) via mutagenesis could accelerate breeding programs; thus, the present study aimed to develop an in vitro protocol using the chemical mutagens sodium azide (NaN3) and ethyl methanesulfonate (EMS) on embryogenic cell suspensions of Arabica coffee variety Catuaí and, subsequently, to evaluate the responses of the resulting mutagenized tissues to salinity stress. Embryogenic suspension cultures were incubated with 0.0, 2.5, 5.0, or 10.0 mM NaN3 or 0.0, 185.2, 370.5, or 741.0 mM EMS. As the concentration of NaN3 or EMS increased, the survival of embryogenic suspension cultures decreased compared to controls. The median lethal dose (LD50) for NaN3 was 5 mM for 15 min and for EMS it was 185.2 mM for 120 min. Embryogenic suspension cultures treated with NaN3 or EMS were cultured on selective medium supplemented with 0, 50, 100, 150, 250, or 300 mM NaCl showed that 50 mM NaCl could be used as selection pressure. Plantlet growth and total amino acid content were affected by NaCl stress; some mutants had longer shoots and higher amino acid content than controls. Random amplified polymorphic DNA (RAPD) analysis was performed to determine whether the NaN3 or EMS treatments could induce genetic variability and resulted in identifiable polymorphic markers. A total of 18 10-mer primers were used to amplify genomic DNA of putative mutant and non-mutant arabica coffee embryogenic cultures and produced 50 scorable bands, of which 22% were polymorphic.Universidad de Costa Rica/[111-B5-140]/UCR/Costa RicaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí