A step-by-step method to quantify coloration with digital photography.

Coloration is often used in biological studies, for example when studying social signaling or antipredator defense. Yet, few detailed and standardized methods are available to measure coloration using digital photography. Here we provide a step-by-step guide to help researchers quantify coloration from digital images. We first identify the do's and don'ts of taking pictures for coloration analysis. We then describe how to i) extract reflectance values with the software ImageJ; ii) fit and apply linearization equations to reflectance values; iii) scale and select the areas of interest in ImageJ; iv) standardize pictures; and v) binarize and measure the proportion of different colors in an area of interest. We apply our methodological protocol to digital pictures of painted turtles (Chrysemys picta), but the approach could be easily adapted to any species. More specifically, we wished to calculate the proportion of red and yellow on the neck and head of turtles. With this protocol, our main aims are to make coloration analyses with digital photography:•More accessible to researchers without a background in photography.•More consistent between studies.

Fear of falling in community-dwelling older adults presenting to the emergency department for minor injuries: Impact on return to the ED and future falls.

OBJECTIVES: 1) To characterize mild, moderate, and severe fear of falling in older emergency department (ED) patients for minor injuries, and 2) to assess whether fear of falling could predict falls and returns to the ED within 6 months of the initial ED visit. METHODS: This study was part of the Canadian Emergency and Trauma Initiative (CETI) prospective cohort (2011-2016). Patients ages ≥ 65, who were independent in their basic daily activities and who were discharged from the ED after consulting for a minor injury, were included. Fear of falling was measured by the Short Falls Efficacy Scale International (SFES-I) in order to stratify fear of falling as mild (SFES-I = 7-8/28), moderate (SFES-I = 9-13/28), or severe (SFES-I = 14-28/28). Many other physical and psychological characteristics where collected. Research assistants conducted follow-up phone interviews at 3 and 6 months' post-ED visit, in which patients were asked to report returns to the ED. RESULTS: A total of 2,899 patients were enrolled and 2,009 had complete data at 6 months. Patients with moderate to severe fear of falling were more likely to be of ages ≥ 75, female, frailer with multiple comorbidities, and decreased mobility. Higher baseline fear of falling increased the risk of falling at 3 and 6 months (odds ratio [OR]-moderate-fear of falling: 1.63, p < 0.05, OR-severe-fear of falling 2.37, p < 0.05). Fear of falling positive predictive values for return to the ED or future falls were 7.7% to 17%. CONCLUSION: Although a high fear of falling is associated with increased risk of falling within 6 months of a minor injury in older patients, fear of falling considered alone was not shown to be a strong predictor of return to the ED and future falls.

Effects of blood parasite infection and innate immune genetic diversity on mating patterns in a passerine bird breeding in contrasted habitats.

Genetic diversity at immune genes and levels of parasitism are known to affect patterns of (dis)assortative mating in several species. Heterozygote advantage and/or good genes should shape mate choice originating from pathogen/parasite-driven selection at immune genes. However, the stability of these associations, and whether they vary with environmental conditions, are still rarely documented. In this study, we describe mating patterns in a wild population of tree swallows (Tachycineta bicolor) over 4 years and assess the effects of haemosporidian parasite infection and immune genetic diversity at ß-defensin genes on those patterns within two habitats of contrasting environmental quality, in southern Québec, Canada. We first show that mating patterns were only very weakly related to individual status of infection by haemosporidian parasites. However, we found a difference between habitats in mating patterns related to infection status, which was likely due to a non-random distribution of individuals, as non-infected mating pairs were more frequent in lower quality habitats. Mating patterns also differed depending on ß-defensin heterozygosity at AvBD2, but only for genetic partners outside of the social couple, with heterozygous individuals pairing together. Our study underlines the importance of considering habitat heterogeneity in studies of sexual selection.

Environmental determinants of haemosporidian parasite prevalence in a declining population of Tree swallows.

The prevalence of vector-borne parasites such as haemosporidian species is influenced by several environmental factors. While the negative effects of parasitism on hosts are well documented, these can also be amplified by interactions with environmental stressors, many of which are anthropogenic. Yet, we know little about the possible effects of anthropogenic perturbations on parasite prevalence. The goals of this study were to assess the prevalence and environmental determinants of haemosporidian parasites in a declining population of Tree swallows (Tachycineta bicolor) living in an agricultural landscape in southern Québec, Canada. Overall, a low prevalence and a moderate lineage diversity were identified in both adults and nestlings, confirming that transmission can occur during the breeding period. Anthropic areas, extensive cultures (hayfields and pastures) and forest cover within 500 km of nest boxes, as well as daily temperature fluctuations, were all related to infection by haemosporidian parasites. These findings suggest that anthropogenic alterations of landscape composition can modulate the prevalence of haemosporidian parasites in Tree swallows. Our results represent a baseline for future comparative studies assessing haemosporidian parasite prevalence in human-modified landscapes.

Three-Dimensional Culture Assay to Explore Cancer Cell Invasiveness and Satellite Tumor Formation.

Mammalian cell culture in monolayers is widely used to study various physiological and molecular processes. However, this approach to study growing cells often generates unwanted artifacts. Therefore, cell culture in a three-dimensional (3D) environment, often using extracellular matrix components, emerged as an interesting alternative due to its close similarity to the native in vivo tissue or organ. We developed a 3D cell culture system using two compartments, namely (i) a central compartment containing cancer cells embedded in a collagen gel acting as a pseudo-primary macrospherical tumor and (ii) a peripheral cell-free compartment made of a fibrin gel, i.e. an extracellular matrix component different from that used in the center, in which cancer cells can migrate (invasion front) and/or form microspherical tumors representing secondary or satellite tumors. The formation of satellite tumors in the peripheral compartment is remarkably correlated to the known aggressiveness or metastatic origin of the native tumor cells, which makes this 3D culture system unique. This cell culture approach might be considered to assess cancer cell invasiveness and motility, cell-extracellular matrix interactions and as a method to evaluate anti-cancer drug properties.

Dynamics of depletion and replenishment of water storage in stem and roots of black spruce measured by dendrometers.

In the short term, trees rely on the internal storage of water because it affects their ability to sustain photosynthesis and growth. However, water is not rapidly available for transpiration from all the compartments of the plant and the living tissues of the stem act as a buffer to preclude low water potentials during peaks of transpiration. In this paper, electronic dendrometers were used from mid-June to mid-September 2008 to compare the radius variations in stem and roots of black spruce [Picea mariana (Mill.) B.S.P.] in two sites of the boreal forest of Quebec, Canada, with different soil characteristics and water retention. The duration of the daily cycles was similar between sites and measurement heights but greater amplitudes of contraction and expansion were observed on the stem and in the site with the shallowest soil organic layer. The expansion phase had higher amplitudes and lasted longer than contraction. On average, the contraction phase occurred between 07:00 and 16:30 (legal time), while expansion lasted 14.5 h. The roots in the site with the deepest organic layer showed a wider variation in the onset of contraction, which could be as late as 13:00. The probability of observing the contraction phase depended on precipitation. With a precipitation <0.5 mm (h-1), the bivariate posterior probabilities estimated >60% probability of observing contraction between 05:00 and 21:00, decreasing to 20% with precipitation >1.1 mm h(-1). These findings demonstrated that the depth of the organic layer plays an important role in maintaining the internal water reserve of trees. The dynamics of water depletion and replenishment can modify the water potential of xylem and cell turgor during the enlargement phase, thus affecting radial growth. Changes in temperature and precipitation regime could influence the dynamics of internal water storage in trees growing on shallower and drier soils.