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

<b>Biologia e pesca do timbiro, <em>Pterengraulis atherinoides</em>, do açude Pereira de Miranda (Pentecoste, Estado do Ceará, Brasil)</b> - DOI: 10.4025/actascianimsci.v27i4.1156 <b>Biology and fishing of the timbiro, <em>Pterengraulis atherinoides</em>, at Pereira de Miranda reservoir (Pentecoste, Ceará State, Brazil)</b> - DOI: 10.4025/actascianimsci.v27i4.1156

O trabalho aborda a biologia e a pesca do timbiro, <em>Pterengraulis atherinoides</em>, do açude Pereira de Miranda, Pentecoste, Estado do Ceará. Coletas mensais foram realizadas durante o período de agosto de 1994 a julho de 1995. Com os dados morfométricos, uma distribuição de freqüência de comprimento foi feita para ser analisada através do Programa FAO-ICLARM Stock Assessment Tools - FISAT. Assim, os seguintes parâmetros foram estimados: crescimento, mortalidade, taxa de exploração, probabilidade de captura, recrutamento e intensidade do esforço de pesca. Desta forma, conclui-se que a espécie possui vida curta e uma taxa de crescimento alta. Os coeficientes de mortalidade natural e por pesca mostraram-se equilibrados, por se tratar de um estoque não explorado comercialmente. Mesmo com um tamanho médio de primeira captura abaixo do valor do de primeira maturação gonadal, que se deve à baixa seletividade da rede-de-espera, a espécie é muito prolífera, garantindo, assim, o equilíbrio da população<br>Biological aspects and fishing information of timbiro <em>Pterengraulis atherinoides</em> from Pereira de Miranda reservoir, Pentecoste, Ceará State, Brazil, were studied in the present work. Monthly samples were obtained from August 1994 to July 1995. During this period 5,140 individuals were analyzed. Based on each species’ morphometrical data, the following parameters were estimated using projection models: growth, mortality, exploration rate, capture probability, recruitment and fishing effort intensity. A frequency distribution table on length was elaborated and analyzed by FAO-ICLARM Stock Assessment Tools - FISAT. P. atherinoides has been shown to be a medium-life fish whose growth rate is quite high. Both natural and fishing mortality rates are coherent to other growth parameters, as it is a commercially unexplored resource. Individuals have been captured before they reach their first gonadal maturation, due to the low selectivity of fishing apparatus. Since timbiro is highly proliferous, this fact has kept the population in natural equilibriu

Diversificação intra-específica do pargo, Lutjanus purpureus Poey, no Norte e Nordeste do Brasil

The red snapper, Lutjanus purpureus Poey (Perciformes, Lutjanidae), is captured along the North and Northeast coast of Brazil. It consists of one of the main fishing resources of these areas, being considered economically important as source of exchange value. This work has verified the occurrence of intro-specific diversification of the red snapper in the North and Northeast of Brazil. A total of 556 individuals were investigated among Amapá (319), Pará (176) and Maranhão (61). Sex ratio has shown that 43.71% were male and 56.29% female. The higher proportion of females is statistically significant according to χ2 test. The results of ANOVA showed significant differences of morphometrical variables in all areas studied. In order to show which averages presented significant difference, the Tukey’s test was used, and revealed that from the 48 comparative analyses, 100% were shown significant. Each area (AP, PA and MA) presented significant difference for each one of the morphometrical variables. To calculate the overlap degree, the method was used by comparison of averages for morphometrical characters. Out of 112 analyses, 46.43% presented diversification process at the intro-specific level, possibly suggesting the existence of natural barriers and/or geographical isolation. This information may be considered very important for the correct formulation of environmental policies.O pargo, Lutjanus purpureus Poey (Perciformes, Lutjanidae), é capturado em toda a costa Norte e Nordeste do Brasil, constituindo um dos principais recursos pesqueiros da região, sendo reconhecido como fonte de divisa importante para a economia. Este trabalho verifica a ocorrência de diversificação intra-específica do pargo no Norte e Nordeste do Brasil. Foi amostrado um total de 556 indivíduos entre os Estados do AP (319), PA (176) e MA (61). Na análise das proporções entre sexos, verificou-se que dos indivíduos amostrados, 43,71% eram machos e 56,29% fêmeas. Essa vantagem de fêmeas é estatisticamente significativa de acordo com o teste do χ2. Os resultados da ANOVA mostraram diferenças significativas das variáveis morfométricas em todas as subáreas. Para mostrar quais médias apresentavam contrastes significativos foi usado o teste de Tukey, que revelou que das 48 análises comparativas, 100% mostraram-se significativas. Cada subárea (AP, PA e MA) apresentou diferença significativa para cada uma das variáveis morfométricas testadas. Para estimar o grau de sobreposição, utilizou-se o método por comparação de médias para caracteres morfométricos. Do total de 112 análises, 46,43% apresentaram processo de diversificação intra-específica, sugerindo possíveis barreiras naturais e/ou isolamento geográfico. Informações dessa natureza são imprescindíveis para a correta formulação de uma política ambiental para o setor

Rock n' Seeds: A database of seed functional traits and germination experiments from Brazilian rock outcrop vegetation

Advancing functional ecology depends fundamentally on the availability of data on reproductive traits, including those from tropical plants, which have been historically underrepresented in global trait databases. Although some valuable databases have been created recently, they are mainly restricted to temperate areas and vegetative traits such as leaf and wood traits. Here, we present Rock n' Seeds, a database of seed functional traits and germination experiments from Brazilian rock outcrop vegetation, recognized as outstanding centers of diversity and endemism. Data were compiled through a systematic literature search, resulting in 103 publications from which seed functional traits were extracted. The database includes information on 16 functional traits for 383 taxa from 148 genera, 50 families, and 25 orders. These 16 traits include two dispersal, six production, four morphological, two biophysical, and two germination traits-the major axes of the seed ecological spectrum. The database also provides raw data for 48 germination experiments, for a total of 10,187 records for 281 taxa. Germination experiments in the database assessed the effect of a wide range of abiotic and biotic factors on germination and different dormancy-breaking treatments. Notably, 8255 of these records include daily germination counts. This input will facilitate synthesizing germination data and using this database for a myriad of ecological questions. Given the variety of seed traits and the extensive germination information made available by this database, we expect it to be a valuable resource advancing comparative functional ecology and guiding seed-based restoration and biodiversity conservation in tropical megadiverse ecosystems. There are no copyright restrictions on the data; please cite this paper when using the current data in publications; also the authors would appreciate notification of how the data are used in publications