Cloning, characterization, and properties of seven triplet repeat DNA sequences

Several neuromuscular and neurodegenerative diseases are caused by genetically unstable triplet repeat sequences (CTG.CAG, CGG.CCG, or AAG.CTT) in or near the responsible genes. We implemented novel cloning strategies with chemically synthesized oligonucleotides to clone seven of the triplet repeat sequences (GTA.TAC, GAT.ATC, GTT.AAC, CAC.GTG, AGG.CCT, TCG.CGA, and AAG.CTT), and the adjoining paper (Ohshima, K., Kang, S., Larson, J. E., and Wells, R. D.(1996) J. Biol. Chem. 271, 16784-16791) describes studies on TTA.TAA. This approach in conjunction with in vivo expansion studies in Escherichia coli enabled the preparation of at least 81 plasmids containing the repeat sequences with lengths of approximately 16 up to 158 triplets in both orientations with varying extents of polymorphisms. The inserts were characterized by DNA sequencing as well as DNA polymerase pausings, two-dimensional agarose gel electrophoresis, and chemical probe analyses to evaluate the capacity to adopt negative supercoil induced non-B DNA conformations. AAG.CTT and AGG.CCT form intramolecular triplexes, and the other five repeat sequences do not form any previously characterized non-B structures. However, long tracts of TCG.CGA showed strong inhibition of DNA synthesis at specific loci in the repeats as seen in the cases of CTG.CAG and CGG.CCG (Kang, S., Ohshima, K., Shimizu, M., Amirhaeri, S., and Wells, R. D.(1995) J. Biol. Chem. 270, 27014-27021). This work along with other studies (Wells, R. D.(1996) J. Biol. Chem. 271, 2875-2878) on CTG.CAG, CGG.CCG, and TTA.TAA makes available long inserts of all 10 triplet repeat sequences for a variety of physical, molecular biological, genetic, and medical investigations. A model to explain the reduction in mRNA abundance in Friedreich's ataxia based on intermolecular triplex formation is proposed.     

Attributions of complex cause and the perception of marital conflict.

Although most causal attribution research has focused on beliefs about simple, singular causes, I hypothesized that people may develop more complex causal accounts, which may be particularly important in understanding how people make sense of social interactions. Male and female undergraduates (N?=?72) observed three videotapes of actors portraying an argument between husband and wife from the perspectives of the husband, the wife, and a counselor. Following each observation, participants completed free-response items concerning cause of an argument and Likert scales concerning responsibility for the argument and conditional expectancy for outcome. Results indicate that observers are likely to consider joint cause in describing social interaction. Explicit instructions to take the perspective of one of the participants reduced the levels of joint cause being reported and of shared responsibility perceived. Perspective also influenced expectancies for changes in the relationship given changes in behavior by either partner. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Boundary evaluation using inner and outer sets: the ISOS method

A boundary-evaluation algorithm for constructive solid geometry is presented for representations in which the primitives can be bounded by complex surfaces (such as splines) as well as by simpler polynomial surfaces. A fundamental part of the algorithm is the spatial decomposition of each primitive in a way that yields three planar bounded volumes, one containing the primitive (outer set), one contained within the primitive (inner set), and the third being the set difference of the first two, containing the boundary of the primitive. A positive feature of this approach is that the geometric coverage can be extended to any family of solid primitives for which an initial inner-solid-outer-solid segmentation and a subdivision procedure can be devices. Satisfying these two requirements ensures that the resulting primitive definitions are in the canonical form necessary for evaluation. Therefore the cost in terms of software development of adding primitive types does not depend on the number or type of existing primitives     

Creep deformation cracking of polyethylene in methanol

Compression-moulded high-density polyethylene with a large spherulite size was deformed in methanol, an environment cracking agent. The mechanical test involved constant load creep in tension. At smaller loads corresponding to longer lifetimes, the final failure consisted of a macroscopic crack oriented perpendicular to the tensile axis. Deformed specimens were etched in permanganic acid and the spherulitic and lamellar structures near the macroscopic crack were examined using optical, scanning electron and transmission electron microscopy. The large-scale fracture was the result of crack nucleation in the interlamellar regions and subsequent sub-critical crack growth with micro-cracks joining up to form larger cracks.