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

Insecticide resistance and genetic variability in natural populations of Aedes (Stegomyia) aegypti (Diptera: Culicidae) from Colombia

Mosquito control prevails as the most efficient method to protect humans from the dengue virus, despite recent efforts to find a vaccine for this disease. We evaluated insecticide resistance and genetic variability in natural populations of Aedes aegypti (Linnaeus, 1762) from Colombia. This is the first Colombian study examining kdr mutations and population structure. Bioassays with larvae of three mosquito populations (Armenia, Calarcá and Montenegro) were performed according to the World Health Organization (WHO) guidelines, using Temephos. For the analysis of the Val1016Ile mutation and genetic diversity, we sampled recently-emerged adults from four mosquito populations (Armenia, Calarcá, Montenegro and Barcelona). Following the WHO protocol, bioassays implemented with larvae showed resistance to Temephos in mosquito populations from Armenia (77% ± 2) and Calarcá (62% ± 14), and an incipient altered susceptibility at Montenegro (88% ± 8). The RR95 of mosquito populations ranged from 3.7 (Montenegro) to 6.0 (Calarca). The Val1016Ile mutation analysis of 107 genotyped samples indicates that 94% of the specimens were homozygous for the wild allele (1016Val) and 6% were heterozygous (Val1016Ile). The 1016Ile allele was not found in Barcelona. Genetic variability analysis found three mitochondrial lineages with low genetic diversity and gene flow. In comparison with haplotypes from the American continent, those from this study suggest connections with Mexican and North American populations. These results confirm that a continuous monitoring and managing program of A. aegypti resistance in the state of Quindío is required

RAILWAY INDUSTRY ROADMAP IN THE STATE OF SANTA CATARINA, BRAZIL

This article aims to identify the main requirements to strengthen the railroad industry in Santa Catarina by using technology roadmapping. The railway industry is composed of carriers, manufacturers, suppliers, operators, logistics, services and education. The survey aimed to provide guidelines for the Federation of the State of Santa Catarina Industry (FIESC) to develop its strategic plan for the next eight years. Based on the survey, the roadmap defined vision, mission, a list of key concepts, drivers and actions for the Federation to support the railway industry development, since this industrial sector is still economically unrepresented when compared to other sectors in Santa Catarina. The survey also pointed out there is a strong expansion program of the railway freight and railway transport for people in Brazil, both in government and private sectors

Micropropagación y estimativa de producción de mudas de bananos para la Amazonia Occidental Micropropagation and estimates of banana plantlets production for Western Amazon

El objetivo del trabajo fue de determinar tasas de multiplicación y estimar la producción in vitro de microplantas de las cultivares del banano Preciosa, Maravilha, Pacovan Ken y Japira, durante seis subcultivos y con diferentes concentraciones de BAP. Después de multiplicadas, las microplantas enraizadas fueron aclimatadas, y la sobrevivencia fue determinada después de 30 días. Las tasas de multiplicación fueron de 2,3 y 2,1 brotes por explante de 'Preciosa' y 'Maravilha', respectivamente, y 2,7 brotes por explante de 'Pacovan Ken' y 'Japira', en 4 mg L-1 de BAP. Las pérdidas por contaminación fueron de 22,4%, y la sobrevivencia por lo menos 96%.<br>The objective of this work was to determine multiplication rates and to estimate the in vitro plantlets production of the banana cultivars Preciosa, Maravilha, Pacovan Ken and Japira, during six subcultures at different BAP concentrations. After the multiplication, the rooted microplants were acclimatized, and the survival was determined after 30 days. Multiplication rates reached 2.3 and 2.1 shoots per explant of 'Preciosa' and 'Maravilha', respectively, and 2.7 shoots per explant for 'Pacovan Ken' and 'Japira', in 4 mg L-1 of BAP. Losses due contamination were 22.4%, and seedlings survival was superior to 96%

Efeito de agentes geleificantes alternativos no meio de cultura no cultivo in vitro de abacaxizeiro e bananeira Effect of alternative gelling agents in culture medium in the in vitro cultivation of pineapple and banana

Com este trabalho, objetivou-se avaliar a ação do ágar e sua substituição parcial e total pelo amido de mandioca na composição de meios de cultura de bananeira e abacaxizeiro. Gemas axilares de abacaxizeiro, cvs. Rio Branco e Quinari foram estabelecidas e avaliadas por quatro subcultivos quanto à multiplicação em meio de MS, suplementado com 2 mg.L-1 de BAP e 0,25 mg.L-1 de ANA, e os seguintes tratamentos: M1: ágar (5 g.L-1), M2: ágar (2,5 g.L-1) + fécula de mandioca (60 g.L-1), M3: fécula de mandioca (60 g.L-1), e M4: ágar (2,5 g.L-1) + fécula de mandioca (30 g.L-1). Num segundo experimento, por três subcultivos sucessivos brotações de bananeira da cv. Grand Naine foram avaliadas quanto à multiplicação em meio de cultura composto por: MM1: ágar (6 g.L-1) ; MM2: ágar (3 g.L-1) + fécula de mandioca (30 g.L-1); MM3: fécula de mandioca (60 g.L-1) e; MM4: meio de consistência líquida estacionário.Estes meios foram suplementados com 0, 2, 4 e 6 mg.L-1 de BAP. Para o abacaxizeiro, verificou-se quea substituição total do ágar pela fécula proporcionou resultados similares aos obtidos com o tratamento com ágar. Na combinação ágar + fécula os resultados foram inferiores aos obtidos com os solidificantes usados isoladamente. Para a bananeira, o uso isolado ou combinado da fécula com ágar não proporcionou melhora nas taxas de multiplicação. Os melhores resultados foram obtidos em meio com ágar e 2 mg.L-1 de BAP. O cultivo em meio líquido apresentou o menor índice de multiplicação.<br>The objective of this work was to test the agar action and its partial and total substitution for cassava starch as gelling agents in the culture media of banana and pineapple. Axillary buds of 'Rio Branco' and 'Quinari' cultivars were established and the multiplication rate evaluated by four subcultives in media with 2 mg.L-1 BAP and 0,25 mg.L-1 NAA, with the following combination of gelling agents: M1: agar (5 g.L-1), M2: agar (2,5 g.L-1) + cassava starch (60 g.L-1), M3: cassava starch (60 g.L-1), and M4: agar (2,5 g.L-1) + cassava starch (30 g.L-1). In a second experiment, for three successive subcultivation shoots of banana, 'Grand Naine' cultivar were evaluated in media composed with the following gelling treatments: MM1: agar (6 g.L-1); MM2: agar (3 g.L-1) + cassava starch (30 g.L-1); MM3: cassava starch (60 g.L-1) and; MM4: stationary liquid medium. To these media were added 0, 2, 4 and 6 mg.L-1 BA. To pineapple it was verified similar results when agar was completely substituted for cassava starch as gelling agent, but the combination agar + cassava starch provided the worse results when compared with gelling agents used separately. For banana shoots multiplication, the isolated or combined use of cassava starch did not improve the multiplication rates. The best results were obtained in medium with 2 mg.L-1 BA and agar as gelling agent. The shoot cultivation in liquid medium presented the lowest multiplication index