Histone Tail Sequences Balance Their Role in Genetic Regulation and the Need To Protect DNA against Destruction in Nucleosome Core Particles Containing Abasic Sites

Abasic sites (AP) are produced 10 000 times per day in a single cell. Strand cleavage at AP is accelerated ≈100-fold within a nucleosome core particle (NCP) compared to free DNA. The lysine-rich N-terminal tails of histone proteins catalyze single-strand breaks through a mechanism used by base-excision-repair enzymes, despite the general dearth of glutamic acid, aspartic acid, and histidine—the amino acids that are typically responsible for deprotonation of Schiff base intermediates. Incorporating glutamic acid, aspartic acid, or histidine proximal to lysine residues in histone N-terminal tails increases AP reactivity as much as sixfold. The rate acceleration is due to more facile DNA cleavage of Schiff-base intermediates. These observations raise the possibility that histone proteins could have evolved to minimize the presence of histidine, glutamic acid, and aspartic acid in their lysine-rich N-terminal tails to guard against enhancing the toxic effects of DNA damage.     

Electron-microscopic examination of the transition zone of aluminum-tantalum bimetallic joints (explosion welding)

A study of the structure of an aluminum-tantalum joint and a comparison of this structure with the structures of iron-silver and copper-tantalum joints have revealed the following processes of the interpenetration of the materials that occur during explosion welding: the formation of protrusions, the injection of particles of one material into the other, and the formation of zones of local melting. Regardless of the mutual solubility of the metals being welded, two types of fragmentation occur, i.e., (1) a granulating fragmentation (GF), which includes the formation, explosion-governed (EG) dispersion, and partial consolidation of particles, and (2) the fragmentation that is usually observed during severe plastic deformation. It is important that this traditional fragmentation is not accompanied by the formation and EG dispersion of particles. This feature allows one to easily distinguish these types of fragmentation (traditional and GF fragmentation).     

Is it possible for dislocations to self-lock after high-pressure torsion?

The evolution of the dislocation structure of the intermetallic compound Ni₃Ge upon high-pressure torsion has been investigated. It has been determined that, under certain conditions, subsequent heating without loading leads to the self-locking of dislocations, while in other cases, this does not take place. The role played by the lattice distortions that arise under torsion is emphasized.     

Structure of the transition zone and its influence on the strength of copper-tantalum joint (Explosion welding)

The joint of copper and tantalum, metals without mutual solubility, formed by explosion welding is studied. The mechanism of the influence of mutual solubility on the structure of the transition zone is established. It is demonstrated that the interface contains heterogeneities, and their role in the strength of the materials joint is revealed. A microheterogeneous structure of the joint zones is detected.     

Self-blocking of dislocations in intermetallic compound Ni<Subscript>3</Subscript>Ge: Cubic slip

Self-blocking of dislocations belonging to the cube plane has been detected in the intermetallic compound Ni₃Ge. The nature of cubic slip has been clarified. The experiments included deformation at a temperature above T _max (the temperature of the yield-stress peak) and subsequent heating without stress. In addition, changes in the dislocation structure upon slow cooling from the temperature of the preliminary deformation have been investigated; in doing so, self-blocking of dislocations has been revealed for the first time. Based on the totality of experimental data, a conclusion has been made on the two-valley potential relief for a dislocation motion in the cube plane. It is the difference in the depths between the Peierls valley (a diffuse core in the cube plane) and the deepest valley (a superpartial dislocation split in the octahedron plane) that provides for the driving force of self-blocking in the absence of an external stress. Different aspects of cubic slip have been considered: the disappearance of cubic slip at T < T _max and, correspondingly, the nonobservation of an anomalous behavior of the yield stress, as well as the disappearance of octahedral slip at T > T _max.     

Trajectories of emotional well-being in mothers of adolescents and adults with autism.

Raising an adolescent or adult child with a developmental disability confers exceptional caregiving challenges on parents. We examined trajectories of 2 indicators of emotional well-being (depressive symptoms and anxiety) in a sample of primarily Caucasian mothers (N = 379; M age = 51.22 years at Time 1) of adolescent and adult children with an autism spectrum disorder (ASD; M age = 21.91 years at Time 1, 73.2% male). We also investigated within-person associations of child context time-varying covariates (autism symptoms, behavior problems, residential status) and maternal context time-varying covariates (social support network size and stressful family events) with the trajectories of emotional well-being. Data were collected on 5 occasions across a 10-year period. Average patterns of stable (depressive symptoms) and improved (anxiety) emotional well-being were evident, and well-being trajectories were sensitive to fluctuations in both child and maternal context variables. On occasions when behavior problems were higher, depressive symptoms and anxiety were higher. On occasions after which the grown child moved out of the family home, anxiety was lower. Anxiety was higher on occasions when social support networks were smaller and when more stressful life events were experienced. These results have implications for midlife and aging families of children with an ASD and those who provide services to these families. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Is a sense of inequity an ancestral primate trait? Testing social inequity in cotton top tamarins (Saguinus oedipus).

To address a controversy in the literature concerning whether monkeys show an aversion to inequity, individuals of a New World monkey species, cotton top tamarins (Saguinus oedipus) were tested in an offering task and in a bartering task. At issue was whether the monkeys rejected rewards because of a violation of expectancy of the preferred reward, or whether they rejected rewards because of a sensitivity to socially mediated inequity. The data from both tasks indicated that the subjects were more likely to reject when preferred rewards were presented, either because of another animal eating the reward (the social condition) or because of rewards being presented but inaccessible. The bartering task led to the only behavioral indication of aversion due specifically to social inequity, which was demonstrated when tamarins' sensitivity to the difference in rewards increased with exposure to other tamarins working to receive the preferred rewards. The results suggest that social inequity aversion will be assessed by tamarins, and possibly by other primates, only under conditions of limited resources and a requirement of work, which may make the situation a bit more competitive and thus drives attention toward both social and reward evaluation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Not all faces are processed equally: Evidence for featural rather than holistic processing of one's own face in a face-imaging task.

The present work considers the mental imaging of faces, with a focus in own-face imaging. Experiments 1 and 3 demonstrated an own-face disadvantage, with slower generation of mental images of one's own face than of other familiar faces. In contrast, Experiment 2 demonstrated that mental images of facial parts are generated more quickly for one's own face. Finally, Experiment 4 established that a bias toward local processing is advantageous for one's own face, whereas a global-processing bias produces an enhanced own-face disadvantage. The results suggest that own-face imaging is more synchronized with retrieval of face features and less attuned to a face's holistic pattern than is imaging of other people's faces. The authors propose that the salient information for own and other face identification reflects, in part, differences in the purpose and experiences (expertise) generally associated with processing of own and other faces. Consistent with work examining the range of face processing, including other-race faces, our results suggest that not all faces receive the same holistic emphasis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)