Communication between DNA and nucleotide binding sites facilitates stepping by the RecBCD helicase.

Double-strand DNA breaks are the severest type of genomic damage, requiring rapid response to ensure survival. RecBCD helicase in prokaryotes initiates processive and rapid DNA unzipping, essential for break repair. The energetics of RecBCD during translocation along the DNA track are quantitatively not defined. Specifically, it's essential to understand the mechanism by which RecBCD switches between its binding states to enable its translocation. Here, we determine, by systematic affinity measurements, the degree of coupling between DNA and nucleotide binding to RecBCD. In the presence of ADP, RecBCD binds weakly to DNA that harbors a double overhang mimicking an unwinding intermediate. Consistently, RecBCD binds weakly to ADP in the presence of the same DNA. We did not observe coupling between DNA and nucleotide binding for DNA molecules having only a single overhang, suggesting that RecBCD subunits must both bind DNA to 'sense' the nucleotide state. On the contrary, AMPpNp shows weak coupling as RecBCD remains strongly bound to DNA in its presence. Detailed thermodynamic analysis of the RecBCD reaction mechanism suggests an 'energetic compensation' between RecB and RecD, which may be essential for rapid unwinding. Our findings provide the basis for a plausible stepping mechanism' during the processive translocation of RecBCD.

Personal hygiene, environmental conditions, and toilet use of children in primary schools: A cohort study.

BACKGROUND: Many primary school children withhold urine and stool whilst at school for various reasons. Limited toilet access and the failure to provide safe, sanitary toilets are putting children at risk for toilet avoidance behavior. OBJECTIVE: We aimed to examine personal hygiene, environmental conditions, the perception of these on children, and their toilet use in primary schools. STUDY DESIGN: Children aged 6-12 and their parents were asked to complete a self-report questionnaire regarding toilet behavior and the perception of school toilet standards. RESULTS: The main findings are listed below using the data from the questionnaire. DISCUSSION: We found that 9% and 63% of the children avoided urination and defecating at school, respectively. Similar results were reported previously. The participants' perceptions regarding the environmental conditions of school toilets and conditions revealed that 34% of the children felt that the toilets were dirty or very dirty. Around one-third of them reported a lack of toilet paper sometimes or most of the time. These unsatisfying hygienic conditions of school toilets can be easily solved. Unfortunately, 46% of the children in our study experienced bullying in school toilets. These worrisome data are seldom reported in other studies. The urination habits of the girls, who mostly preferred to partially squat or stand may lead to dysfunctional voiding and incomplete bladder emptying. Our study was limited by the relatively small population, the subjectiveness of the self-reporting questionnaire, and the voiding and defecation habits of the investigated children during school hours. These hours do not necessarily reflect the children's habits after school hours and during the weekends. Despite these limitations, the discussed issues regarding personal hygiene and the environmental conditions in the sampled primary schools are extremely important. CONCLUSION: Nearly half of the school children had negative perceptions of school toilets. This should raise awareness and concern for school staff to consider and investigate potential facilities improvement in light of the impact observed here. Implementation of appropriate education and a better environment of toilet facilities and security is important for the children's well-being.

Situational determinants of young children's gratitude: The effects of perceived intentionality and the value of the benefit on gratitude and prosocial behavior.

Across a series of studies, we examined the effects of the intentionality of the benefactor and the value of the benefit on 3- to 6-year-old children's gratitude, using an experimental design. Feelings and expressions of gratitude were used as indicators of gratitude, and prosocial behavior toward the benefactor was examined as a possible behavioral correlate. Experiment 1 (N = 175) showed that the benevolent intention of the benefactor affected preschool children's gratitude and helping behavior toward the benefactor. Experiment 2 (N = 172) found significant effects for the perceived value of the benefit on children's gratitude and prosociality. Experiment 3 (N = 218) showed that children's gratitude was influenced by both the value of the gift and the benefactor's benevolent intentions. Children's theory-of-mind abilities mediated the relationship between children's age and gratitude. The results suggest that intention and gift value may act as determinants of gratitude in early childhood. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Grateful and kind: The prosocial function of gratitude in young children's relationships.

Three experiments showed that gratitude positively affected preschool children's prosocial behavior. In the studies, the experimenter induced gratitude by giving a token gift and then making a request for help or to share resources. Experiment 1 (N = 126, 4- to 6-year-olds) showed that gratitude increased helping behaviors toward the benefactor, and that emphasis on the benefactor's intention had a significant effect on helping behaviors. Experiment 2 (N = 129, 4- to 6-year-olds) indicated that grateful emotions increased the likelihood that the children would help not only the benefactor but also a stranger. Experiment 3 (N = 133, 3- to 6-year-olds) showed that gratitude motivated preschoolers' sharing behavior with the benefactor. Children's theory-of-mind and their understanding of the benefactor's intention mediated the relationship between children's age, gratitude, and prosociality. (PsycInfo Database Record (c) 2020 APA, all rights reserved).