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Biomedical subjects

A Philpott

Publications and source records attributed to A Philpott.

4 recordsLinked to original sources

Nucleoplasmin remodels sperm chromatin in Xenopus egg extracts.

Nucleoplasmin is necessary and sufficient for the initial stage of Xenopus sperm decondensation in egg extracts. In this article we show that sperm decondensation is accompanied by loss of two sperm-specific basic proteins (X and Y) and gain of histones H2A and H2B, resulting in nucleosome formation. Purified nucleoplasmin alone removes X and Y and assembles purified H2A and H2B on decondensing sperm chromatin, forming nucleosome cores. Immunodepletion of nucleoplasmin from extract prevents removal of X and Y and addition of H2A and H2B, while adding back nucleoplasmin restores decondensation and X and Y removal. Thus, nucleoplasmin acts as both an assembly and a disassembly factor for remodeling sperm chromatin at fertilization.

Animals

Academic performance in children of divorce: psychological resilience and vulnerability.

Parental divorce can be conceptualized as a stressful event for all children, but one must recognize that reactions to divorce can vary widely among children. This investigation was based on two basic ideas: 1) children of divorce as a group would show deficits in academic performance compared to children from intact families, even several years after their parents' separation, and 2) because factors that promote psychological resilience and vulnerability, we expected to find normal heterogeneity within the divorce sample. Among 96 middle-school adolescents from a suburban school district near Denver, children of divorce showed significant performance deficits in academic achievement, as reflected in grade-point average and scholastic motivation in middle school, but not in nationally normed tests of scholastic aptitude and other less direct measures of behavioral conformity. An analysis of GPA over time revealed strikingly disparate patterns of achievement between divorce and control groups. Corresponding patterns of scholastic aptitude scores, absence from school and comportment revealed no systematic differences over time. These results suggest strongly that parental divorce can be a critical event in the academic development of children. Large differences in academic achievement between our divorce group as a whole and the controls cannot be attributed, at least at the time of sampling, to differences in social class or intellectual ability. Despite a similar family background, i.e., marital dissolution, a minority of the children of divorce showed vulnerability in the pattern of academic achievement over time while the majority demonstrated academic careers not unlike that of the controls.

Achievement

Semantic interference from subliminal stimuli in a dichoptic viewing situation.

In Expt 1 subjects named words, shapes or colours presented to one eye while words or shapes were presented to the other eye subliminally. The subliminal stimuli were found to slow naming responses when they had the same name as the stimulus to be named or a closely related name, compared with random letter strings or blank cards. This result was replicated in a second experiment which also included unrelated words as subliminal stimuli. On these trials latencies were midway between those for trials with blank cards or random letter strings as the subliminal stimuli, and trials with the same name or a closely related name as the subliminal stimuli. The results imply that stimuli related in meaning compete for common analysing mechanisms.

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