Childhood temperament: passive gene-environment correlation, gene-environment interaction, and the hidden importance of the family environment.

Biological parents pass on genotypes to their children, as well as provide home environments that correlate with their genotypes; thus, the association between the home environment and children's temperament can be genetically (i.e., passive gene-environment correlation) or environmentally mediated. Furthermore, family environments may suppress or facilitate the heritability of children's temperament (i.e., gene-environment interaction). The sample comprised 807 twin pairs (mean age = 7.93 years) from the longitudinal Wisconsin Twin Project. Important passive gene-environment correlations emerged, such that home environments were less chaotic for children with high effortful control, and this association was genetically mediated. Children with high extraversion/surgency experienced more chaotic home environments, and this correlation was also genetically mediated. In addition, heritability of children's temperament was moderated by home environments, such that effortful control and extraversion/surgency were more heritable in chaotic homes, and negative affectivity was more heritable under crowded or unsafe home conditions. Modeling multiple types of gene-environment interplay uncovered the complex role of genetic factors and the hidden importance of the family environment for children's temperament and development more generally.

Detection of multiple network-based allosteric interactions between peptides and arrays of DNA binding sites.

Quantitative DNase I footprinting shows that three designed peptides containing N-methylpyrrole (Py) moieties display different types of network-based allosteric communication in binding to DNA: circuit type, incomplete-circuit type, and non-circuit type characterized by interstrand bidentate interactions. Positive cooperative binding of all three peptides to individual DNA binding sites is commonly observed. CD spectral characterization of the interaction between peptides and model undecanucleotide duplexes is consistent with the footprinting results and supports the allosteric model. This study provides insights relating to the interaction network nature of allostery in complex DNA-small molecule interactions.

Novel DNA-peptide interaction networks.

Allostery in the binding of peptides to DNA has been studied by quantitative DNase I footprinting using four newly designed peptides containing the XP(Hyp)RK motif and N-methylpyrrole (Py) moieties. Apparent binding constants in the micromolar range as well as Hill coefficients were determined for each peptide. The results, together with previous studies on five other peptides support the proposal that interaction network cooperativity is highly preferred in DNA-peptide interactions that involve multiple recognition sites. It is envisaged that interstrand bidentate interactions participate in the relay of conformational changes between recognition sites on the complementary strands. Models for interpreting DNA allostery based upon interaction networks are outlined. Circular dichroism experiments involving the titration of peptides against a short oligonucleotide duplex indicate that some of these peptides bind in a dimeric manner to DNA via the minor groove, inducing characteristic conformational changes. These insights should prompt the design of new DNA-binding peptides for investigating allosteric interactions between peptides and DNA, as well as novel interaction networks, and ultimately may shed light upon the fundamental chemical rules that govern allostery in more complex biological process such as DNA-protein interaction networks.

Emotion understanding, theory of mind, and prosocial orientation: Relations over time in early childhood.

Data were collected when children were 42, 54, and 72 months of age (Ns=210, 191, and 172 for T1, T2, and T3, respectively). Children's emotion understanding (EU) and theory of mind (ToM) were examined as predictors of children's prosocial orientation within and across time. EU positively related to children's sympathy across 2.5 years, and T1 EU positively related to parent-reported prosocial orientation concurrently and across 1 year (T2). T2 ToM positively related to parents' reports of sympathy and prosocial orientation concurrently and 18 months later (T3); in contrast, T3 ToM did not relate to sympathy or prosocial orientation. T2 ToM accounted for marginally significant variance (p<0.058) in T3 mother-reported prosocial orientation over and above that accounted for by T2 prosocial orientation. Fostering the development of EU and ToM may contribute to children's prosocial orientation.