Negotiating the transition to middle school: the role of self-regulatory processes.

The present research examined the role of maladaptive self-regulatory beliefs as vulnerability factors for academic and emotional difficulties during the transition to middle school. A short-term longitudinal design was employed to follow two groups of early adolescents: 187 adolescents who experienced a school transition between the fifth and sixth grades, and 142 adolescents who did not experience a school transition between the fifth and sixth grades. Adolescents completed measures of perceptions of academic control and importance of academic success, experience of chronic academic strain, daily school hassles, and depressive symptoms. Teachers reported on students' academic engagement, including levels of helpless behavior, effort, and academic performance. Consistent with the proposed model of self-regulation, maladaptive self-regulatory beliefs (i.e., decreased perceptions of academic control and importance) predicted individual differences in perceived school-related stress and depressive symptoms over the course of the middle school transition, but were not associated with academic and emotional difficulties in adolescents who remained in a stable school environment. Moreover, a self-regulatory sequence was identified proceeding from maladaptive self-regulatory beliefs, to academic disengagement, to enhanced perceptions of school-related stress, to depressive symptoms. This study bridges prior theory and research concerning the psychological impact of normative developmental transitions, the developmental context of depression, and the associations among self-regulatory beliefs, achievement-related behavior, and emotional experience.

Lysine-containing DNA-binding regions on the surface of the histone octamer in the nucleosome core particle.

The DNA bound on the surface of the histone octamer in the nucleosome core particle partially protects the epsilon-amino side-chains of a subset of the lysine residues from reductive methylation. Most of the strongly protected lysines, which probably define the path of the DNA on the octamer surface, are in the globular ('structured') regions of the core histones rather than in the N-terminal or C-terminal 'tails'. Analysis of the protected peptides shows that the three strongest lysine-containing DNA-binding sites in the core histones contain the sequence-Lys/Arg-Lys-Thr/Ser-. On the assumption that the lysine-containing regions protected from chemical modification are also those found in lysine-DNA cross-links in another study [Mirzabekov et al. (1978) Proc. Natl Acad. Sci. USA 75, 4184-4188], particular DNA-protected peptides may be tentatively assigned to particular DNA contact points. This leads to a more detailed description of the DNA-binding regions on the octamer surface in the nucleosome core particle. Strong contacts, reflected in strongly protected lysines, may well contribute to the distortion of the DNA from smooth bending [Richmond et al. (1984) Nature (Lond.) 311, 532-537].

Limited proteolysis of pig liver CoA synthase: evidence for subunit identity.

The bifunctional enzyme CoA synthase can be nicked by trypsin without loss of its activities. The original dimer of subunit Mr approx. 61 000 yields fragments of Mr 41 000 and 22 000 as seen on gel electrophoresis in the presence of SDS, but the nicked enzyme retains the native Mr of 118 000. Further proteolysis occurs rapidly in the absence of protecting substrates. The N-terminal of native CoA synthase is proline, and proteolysis exposes glycine as a second N-terminal. This evidence strongly suggests that the subunits are identical.