SummaryCell division is characterized by a sequence of events by which a cell gives rise to two daughter cells. Quantitative measurements of cell-cycle dynamics in single cells showed that despite variability in G1-, S-, and G2 phases, duration of mitosis is short and remarkably constant. Surprisingly, there is no correlation between cell-cycle length and mitotic duration, suggesting that mitosis is temporally insulated from variability in earlier cell-cycle phases. By combining live cell imaging and computational modeling, we showed that positive feedback is the molecular mechanism underlying the temporal insulation of mitosis. Perturbing positive feedback gave rise to a sluggish, variable entry and progression through mitosis and uncoupled duration of mitosis from variability in cell cycle length. We show that positive feedback is important to keep mitosis short, constant, and temporally insulated and anticipate it might be a commonly used regulatory strategy to create modularity in other biological systems.

The Drosophila melanogaster G protein-coupled receptor gene, methuselah (mth), has been described as a novel gene that is less than 10 million years old. Nevertheless, it shows a highly specific expression pattern in embryos, larvae, and adults, and has been implicated in larval development, stress resistance, and in the setting of adult lifespan, among others. Although mth belongs to a gene subfamily with 16 members in D. melanogaster, there is no evidence for functional redundancy in this subfamily. Therefore, it is surprising that a novel gene influences so many traits. Here, we explore the alternative hypothesis that mth is an old gene. Under this hypothesis, in species distantly related to D. melanogaster, there should be a gene with features similar to those of mth. By performing detailed phylogenetic, synteny, protein structure, and gene expression analyses we show that the D. virilis GJ12490 gene is the orthologous of mth in species distantly related to D. melanogaster. We also show that, in D. americana (a species of the virilis group of Drosophila), a common amino acid polymorphism at the GJ12490 orthologous gene is significantly associated with developmental time, size, and lifespan differences. Our results imply that GJ12490 orthologous genes are candidates for developmental time and lifespan differences in Drosophila in general.

Background: Food allergy is a potentially fatal condition (in the case of anaphylaxis, for example) and is characterized by an increasing prevalence. The main purpose of this study is to identify preschool children with parent-reported food allergies and characterize this population and type of allergy.Methods: This is a cross-sectional study, based on questionnaires to parents/legal guardians. All children who attend daycare or preschool in an area of the city of Porto, Portugal, were included.Results: A total of 740 questionnaires were distributed to nine schools, and responses were obtained from 363 (49.1%). Self-reported food reaction and/or allergy was related in 11.2% of children. The median age of the first reaction was 12 months and the most registered foods were milk, dry seed, and peanut. Cutaneous (48.7%) and gastrointestinal (35.9%) symptoms were the main manifestations. History of parents' and siblings' food allergies had statistically significant associations with food reactions and/or allergies of the child, with OR 3.05 (p=0.04, 95% CI 1.01-8.81) and OR 8.69 (p<0.01, 95% CI 2.11-35.79), respectively. Besides that, children's atopic dermatitis also had a statistically significant association with self-reported food reactions and/or allergies, with OR 2.30 (p<0.05, 95% CI 1.01-5.21).Conclusion: Food reactions and/or allergies were reported in 11.2% of children. The history of parents' and siblings' food allergies and children's atopic dermatitis had statistically significant associations with food reactions and/or allergies, which shows that it may be an important factor to consider.

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