Electron paramagnetic resonance studies on the high-salt form of bovine spleen purple acid phosphatase.

The EPR spectra of the high-salt form of reduced bovine spleen purple acid phosphatase (BSPAPr) and its complexes with inhibitory tetrahedral oxyanions, AMP, and fluorine have been examined in the 4-30 K temperature range. The EPR spectrum of the high-salt form of BAPAPr is identical to that previously reported for the low-salt form (Averill et al. (1987) J. Am. Chem. Soc. 109, 3760-3767), indicating that the substantial differences in conformation of the two forms result in undetectable alterations in the electronic structure of the binuclear iron center. Phosphate, AMP, and arsenate all result in broadened, highly anisotropic EPR spectra with decreased values of the antiferromagnetic coupling constant, -2J, while molybdate and tungstate produce a sharp axial or slightly rhombic spectrum, respectively, and fluoride produces an anomalous spectrum with an inverted g-tensor. These results are consistent with binding of the two classes of oxyanions (and AMP) to distinct sites at or near the binuclear iron center, while fluoride binds in yet a third mode. EPR spectra of the BSPAPr complex with molybdate show altered relaxation behavior in the presence of phosphate, consistent with a 50% decrease in the magnitude of -2J, suggesting that phosphate binds to the molybdate complex to produce a ternary complex analogous to that proposed for molybdate inhibition on the basis of kinetics studies.     

Mitochondrial protein import

Most polypeptides of mitochondria are imported from the cytosol. Precursor proteins contain targeting and sorting information, often in the form of amino-terminal presequences. Precursors first bind to receptors in the outer membrane. Two putative import receptors have been identified: a 19-kilodalton protein (MOM19) inNeurospora mitochondria, and a 70-kilodalton protein (MAS70) in yeast. Some precursors integrate directly into the outer membrane, but the majority are translocated through one or both membranes. This process requires an electrochemical potential across the inner membrane. Import appears to occur through a hydrophilic pore, although the inner and outer membranes may contain functionally separate translocation machineries. In yeast, a 42-kilodalton protein (ISP42) probably forms part of the outer membrane channel. After import, precursors interact with chaperonin ATPases in the matrix. Presequences then are removed by the matrix protease. Finally, some proteins are retranslocated across the inner membrane to the intermembrane space.     

A short history of nuclear activation analysis

The major developments in the field of nuclear activation analysis, from 1936 to 1989, are discussed. The developments are grouped into five consecutive time periods. The impact of various scientists on the development of the field in the first 35 years is also discussed.     

Search for unstable DNA in schizophrenia families with evidence for genetic anticipation.

Evidence for genetic anticipation has recently become an important subject of research in clinical psychiatric genetics. Renewed interest in anticipation was evoked by molecular genetic findings of a novel type of mutation termed "unstable DNA." The unstable DNA model can be construed as the "best fit" for schizophrenia twin and family epidemiological data. We have performed a large-scale Southern blot hybridization, asymmetrical PCR-based, and repeat expansion-detection screening for (CAG)n/(CTG)n and (CCG)n/(CGG)n expansions in eastern Canadian schizophrenia multiplex families demonstrating genetic anticipation. There were no differences in (CAG)n/(CTG)n and (CCG)n/(CGG)n pattern distribution either between affected and unaffected individuals or across generations. Our findings do not support the hypothesis that large (CAG)n/(CTG)n or (CCG)n/(CGG)n expansions are the major etiologic factor in schizophrenia. A separate set of experiments directed to the analysis of small (30-130 trinucleotides), Huntington disease-type expansions in individual genes is required in order to fully exclude the presence of (CAG)n/(CTG)n- or (CCG)n/(CGG)n-type unstable mutation.     

Maintenance of Weight Loss: A Needs Assessment

This study identified facilitators and obstacles to maintenance of weight loss following a very-low-calorie-diet and behavior modification program. A survey was mailed to a random sample of 178 program completers and received a 61% response rate; the most frequent follow-up period was more than 2 years. Twenty-nine percent reported weighing the same (within 10 lbs) or less than the end of their participation in the treatment program (maintainers), while 71% reported their present weight was a mean of 65% higher than their initial weight loss (regainers). Maintainers were significantly more likely to report engaging in regular aerobic exercise, attending a maintenance support group, and confidence in their ability to manage their weight in the future, while regainers were more likely to report stress and motivation as frequent weight management obstacles. Respondents consistently identified the need for low/no cost ongoing support. Maintainers and relapsers reported similar challenges in managing their weight, yet with different results, suggesting the need to identify subgroups for which different post-treatment support options could be applied.     

Control of flower development and phyllotaxy by meristem identity genes in antirrhinum.

The flower meristem identity genes floricaula (flo) and squamosa (squa) promote a change in phyllotaxy from spiral to whorled in Antirrhinum. To determine how this might be achieved, we have performed a combination of morphological, genetic, and expression analyses. Comparison of the phenotypes and RNA expression patterns of single and double mutants with the wild type showed that flo and squa act together to promote flower development but that flo is epistatic to squa with respect to early effects on phyllotaxy. We propose that a common process underlies the phyllotaxy of wildtype, flo, and squa meristem development but that the relative timing of primordium initiation or growth is altered. This process depends on two separable events: setting aside zones for potential primordium initiation and partitioning these zones into discrete primordia. Failure of the second event can lead to the formation of continuous double spirals, which are occasionally seen in flo mutants.     

Analysis of HLA and Disease Susceptibility: Chromosome 6 Genes and Sex Influence Long-QT Phenotype

The long-QT (LQT) syndrome is a genetically complex disorder that is characterized by syncope and fatal ventricular arrhythmias. LQT syndrome, as defined by a prolonged electrocardiographic QT interval, has a higher incidence in females than in males and does not exhibit Mendelian transmission patterns in all families. Among those families that are nearly consistent with Mendelian transmission, linkage between a locus for LQT syndrome and the H-ras-1 locus on the short arm of chromosome 11 has been reported in some families but not in others. Earlier analyses suggesting that LQT syndrome might be caused by a gene in the HLA region of chromosome 6 were not confirmed by standard linkage analyses. Here, we present an analysis of HLA haplotype sharing among affected pedigree members, showing an excess of haplotype sharing in a previously published Japanese pedigree and possibly also in 15 families of European descent. The haplotypes shared by affected individuals derive from both affected and unaffected parents. In an analysis of independent (unrelated) HLA haplotypes, we also found a nonrandom distribution of HLA-DR genes in LQT syndrome patients compared with controls, suggesting an association between the LQT phenotype and specific HLA-DR genes. Our data indicate that DR2 has a protective effect and, particularly in males, that DR7 may increase susceptibility to the LQT syndrome. Thus, LQT syndrome may be influenced by genes on chromosomes 11 and 6, possibly with a sex-specific effect. These results provide a model for an effect of HLA-region genes inherited from either parent on the expression of an illness that may be determined principally by alleles at loci not linked to HLA.