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Genetic and environmental influences on parenting, sibling conflict, and childhood sleep in five-year-old twins

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Understanding how interpersonal relationships, such as parenting and sibling relationships, may contribute to early sleep development is important, as early sleep dysregulation has been shown to impact later sleep behavior (Sadeh & Anders, 1993), as well as cognitive and behavioral

Understanding how interpersonal relationships, such as parenting and sibling relationships, may contribute to early sleep development is important, as early sleep dysregulation has been shown to impact later sleep behavior (Sadeh & Anders, 1993), as well as cognitive and behavioral functioning (Gregory et al., 2006; Soffer-Dudek et al., 2011). In addition, twin studies provide an optimal opportunity to estimate genetic and environmental contributions to parenting, sibling relationships and child sleep, as they are influenced by both genetic and contextual factors. As such, the current thesis examined whether parental punitive discipline and sibling conflict were associated with child sleep duration, dysregulation and daytime sleepiness at 12 months, 30 months, and five years in a longitudinal sample of young twins recruited through birth records (Lemery-Chalfant et al., 2013). Mixed model regression analyses and quantitative behavioral genetic models (univariate and bivariate) were conducted to explore bidirectional relations and estimate genetic and environmental contributions to parental punitive punishment, sibling conflict and child sleep parameters. Sleep duration and dysregulation showed stability over time. Parental punitive discipline did not predict concurrent or future sleep parameters, nor were there bidirectional relations between punitive discipline and child sleep behaviors. Greater sibling conflict at five years was associated with shorter concurrent child sleep duration and greater daytime sleepiness, suggesting that sibling conflict may be a critical interpersonal stressor that negatively impacts child sleep. Shared environmental factors also accounted for the greatest proportion of the covariance between sibling conflict and sleep duration and daytime sleepiness at five years. These findings hold promise for sleep and sibling interaction interventions, including educating parents about fostering positive sibling relations and teaching caregivers to utilize specific parenting behaviors that may encourage better child sleep behaviors (e.g., establishing bedtime routines). Future studies should aim to understand the nuances of associations between family relationships (like punitive discipline and sibling conflict) and child sleep, as well as other explore person- and family-level factors, such as child negative emotions and parenting, that may influence associations between family relationships and child sleep.

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Date Created
2015

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Genetic and Environmental Influences on Executive Functioning in Middle Childhood: The Role of Early Adversity

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This study examined whether early adversity at 30-months moderated the heritability of common and individual components of EF at 8 years. It was hypothesized that early adversity would not moderate the common EF factor, but instead moderate individual EF components.

This study examined whether early adversity at 30-months moderated the heritability of common and individual components of EF at 8 years. It was hypothesized that early adversity would not moderate the common EF factor, but instead moderate individual EF components. The sample included 208 twin pairs from the Arizona Twin Project. Early Adversity, assessed at 30 months of age, included Parenting Daily Hassles, low perceived MOS social support, punitive punishment (Parental Responses to Child Misbehavior), home chaos (Confusion, Hubbub, and Order Scale), CES-D maternal depression, and low maternal emotional availability. EF at 8 years included the Eriksen Flanker Task, Continuous Performance Task, Digit Span Forward and Backward, and parent-reported Attentional Focusing and Inhibitory Control (Temperament in Middle Childhood Questionnaire). For both early adversity and EF, the first principal components were extracted as composites. A confirmatory factor analysis was also conducted to index common EF. Genetic analyses were tested on the common EF composites as well as each individual task using umx. Univariate models revealed genetic influences on all individual measures and common EF, with broad sense heritability from .22 (Digit Span Backwards) to .61 (parent-reported inhibitory control). Shared environmental influences were found for the Flanker Task (.13) and parent-reported inhibitory control (.24), and E was moderate to high (.40-.73) for all measures except parent-report inhibitory control (.15) and attentional focusing (.31). Moderation of heritability was not observed in for Digit Span Forward, Digit Span Backward, and Attentional Focusing. However, the nonshared environment was moderated for Common EF, and the Flanker Task, and additive genes and the nonshared environment were moderated for the Continuous Performance Task and Inhibitory Control. Generally, total variance decreased as early adversity increased, suggesting that homes with low levels of adversity may allow children to interact with more proximal processes that can promote EF development.

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Date Created
2018

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Comparative genomics and novel bioinformatics methodology applied to the green anole reveal unique sex chromosome evolution

Description

In species with highly heteromorphic sex chromosomes, the degradation of one of the sex chromosomes can result in unequal gene expression between the sexes (e.g., between XX females and XY males) and between the sex chromosomes and the autosomes. Dosage

In species with highly heteromorphic sex chromosomes, the degradation of one of the sex chromosomes can result in unequal gene expression between the sexes (e.g., between XX females and XY males) and between the sex chromosomes and the autosomes. Dosage compensation is a process whereby genes on the sex chromosomes achieve equal gene expression which prevents deleterious side effects from having too much or too little expression of genes on sex chromsomes. The green anole is part of a group of species that recently underwent an adaptive radiation. The green anole has XX/XY sex determination, but the content of the X chromosome and its evolution have not been described. Given its status as a model species, better understanding the green anole genome could reveal insights into other species. Genomic analyses are crucial for a comprehensive picture of sex chromosome differentiation and dosage compensation, in addition to understanding speciation.

In order to address this, multiple comparative genomics and bioinformatics analyses were conducted to elucidate patterns of evolution in the green anole and across multiple anole species. Comparative genomics analyses were used to infer additional X-linked loci in the green anole, RNAseq data from male and female samples were anayzed to quantify patterns of sex-biased gene expression across the genome, and the extent of dosage compensation on the anole X chromosome was characterized, providing evidence that the sex chromosomes in the green anole are dosage compensated.

In addition, X-linked genes have a lower ratio of nonsynonymous to synonymous substitution rates than the autosomes when compared to other Anolis species, and pairwise rates of evolution in genes across the anole genome were analyzed. To conduct this analysis a new pipeline was created for filtering alignments and performing batch calculations for whole genome coding sequences. This pipeline has been made publicly available.

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Date Created
2016