The nuclear scaffold exhibits DNA-binding sites selective for supercoiled DNA

Binding of exogenous DNA to the nuclear scaffold was investigated using a plasmid DNA (pBR322, EcoRI site deleted) of various topological forms and nuclear subfractions with different levels of nuclear DNA depletion. When supercoiled DNA was incubated with histone-depleted nuclei (nuclear halo), a dose-dependent binding of the DNA occurred, whereas no binding was observed with relaxed and linear forms of DNA. The bound DNA was released upon linearization with BamHI or digestion of the scaffolding structure with proteinase K. Extensive digestion of the halo with micrococcal nuclease generated additional sites which bind both relaxed and linear DNA. In the presence of a large excess of calf thymus DNA, these sites were effectively blocked and the specificity to supercoiled DNA was restored. The binding of all forms of DNA was abolished by heat-denatured DNA. There was no detectable change in linking number of the scaffold-associated supercoils. Competitive binding was observed between supercoiled DNAs with unrelated sequences, indicating that no specific nucleotide sequence is required for the binding. RNA was found to be a weak competitor. A DNA binding assay performed on electrophoretic blots of solubilized nuclear scaffold revealed a protein component with apparent molecular weight of 120,000 which retained selective binding to supercoils. These results suggest that the nuclear scaffold possesses DNA-binding sites for torsionally strained domains of chromatin and that an integral protein factor is involved in the binding. Implications of the findings are discussed in connection with proposed functions of the nuclear scaffold and topoisomerase II.     

Comparison of EcoRI restriction MHC genes in man and several primate species

EcoRI restriction fragments of the major histocompatibility complex (MHC) from different primate species and the rat were hybridized using identical conditions with the human HLA ³²P probe of Sood. After agarose gel electrophoresis and Southern Blot analysis, all gave a positive autoradiographic signal. The similarity between these species reflects a common genomic structure and conservation of MHC. A tentative arrangement of the different species is proposed according to the similarities in blotting patterns: man, baboon, marmoset, lemurian and rat.     

Tattoo removal by CO laser dermabrasion

A method of tattoo removal by partial-thickness dermal ablation, using a microsurgically adapted CO2 laser, is described. Provided that meticulous attention is paid to each detail of surgical technique, the procedure can be relied upon to produce good cosmetic results with scant risk of complications.     

Acknowledgement to referees

Acknowledgement to referees     

On intensity reinforcements in small-angle light scattering patterns of erythrocytes under shear

On small-angle light scattering patterns obtained with erythrocytes under shear, intensity reinforcements in rings can be noticed. Why should one be interested in them and how does one explain their presence? After examining several hypotheses, analysis shows that this is the consequence of a shape effect: The red cells under stress are not three-axis ellipsoids but rather ellipsoid-like particles whose extremities are thinned.     

Recovery after Work: The Role of Work Beliefs in the Unwinding Process

According to the Effort-Recovery model, mental or physical detachment from work is an important mechanism of work related recovery, as delayed recovery has been associated with range of negative health symptoms. In this paper, we examine whether recovery from work (in the form of mentally disengagement from work) is affected by the concept of ‘work ethic’, which refers to beliefs workers hold about their work and leisure and the effects of experiencing interruptions at work. Two indices of post-work recovery were utilized: problem solving pondering and psychological detachment. The study was conducted with 310 participants employed from diverse occupational sectors. Main effects of positive and negative appraisal of work interruption and beliefs were analysed using mediated and moderated regression analysis on problem-solving pondering and detachment. Weakened belief in wasted time as a partial mediator, reduced problem-solving pondering post work when interruptions were appraised as positive, and a high evaluation of leisure partially mediated problem-solving pondering when interruptions were appraised as positive. The results also showed that a high evaluation of centrality of work and leisure moderated the effect of negative appraisal of work interruption on elevated problem-solving pondering. Positive appraisal of work interruption was related to problem-solving pondering, and the strength of this association was further moderated by a strong belief in delay of gratification. In addition, employees'' positive appraisal of work interruption was related to work detachment, and the strength of this association was further moderated by strong beliefs in hard work and self-reliance. These findings are discussed in terms of their theoretical and practical implications for employees who are strongly influenced by such work beliefs.