Family and Community in Ireland.

Family and Community in Ireland. Conrad M. Arensberg and Solon T. Kimball. Third edition, with. new introduction by Anne Byrne, Ricca Edmondson, and Tony Varley. Ennis, Ireland: Clasp Press, 2001. 417 pp.     

Biochemical characterization and novel isolation of pure estrogen receptor hormone-binding domain

Biologically active, mouse estrogen receptor hormone-binding domain (residues 313–599) overexpressed in Escherichia coli was purified to apparent homogeneity as a single component with a molecular mass of 32.831 kDa determined by electrospray ionization mass spectrometry, and was identical to the mass predicted from the amino acid sequence. The intact domain was isolated using a novel, rapid purification scheme without recourse to any chromatographic process. Pure ERhbd maintained both high affinity estradiol binding (at optimum pH 8.0) and specificity for estrogens and anti-estrogens. The steroid-binding domain sedimented as a 4S component in the presence or absence of bound [³H]estradiol and at 2S in the presence of urea. The molecular mass of the 4S steroid unoccupied ERhbd (from dynamic light scattering) was 72 kDa, suggesting that the pure, unlabelled ERhbd formed homodimers. Steroid-labelled ERhbd electrofocussed as a single, acidic component at a pI of 5.6. Binding of ERhbd to [³H]estradiol was unaffected by Ca²⁺ and Mg²⁺ ions up to 1 mM but was significantly inhibited by Zn²⁺ ions at concentrations above 10 μM, an effect reversed by EDTA.     

Expression of a human cytomegalovirus gp58 antigenic domain fused to the hepatitis B virus nucleocapsid protein

Abstract Hepatitis B virus core antigen (HBcAg) has been used as a carrier for expression and presentation of a variety of heterologous viral epitopes in particulate form. The aim of this study was to produce hybrid antigens comprising HBcAg and an immunogenic epitope of human cytomegalovirus (HCMV). A direct comparison was made of amino and carboxyl terminal fusions in order to investigate the influence of position of the foreign epitope on hybrid core particle formation, antigenicity and immunogenicity. HCMV DNA encoding a neutralising epitope of the surface glycoprotein gp58 was either inserted at the amino terminus or fused to the truncated carboxyl terminus of HBcAg and expressed in Escherichia coli . The carboxyl terminal fusion (HBc_3–144-HCMV) was expressed at high levels and assembled into core like particles resembling native HBcAg. Protein with a similar fusion at the amino terminus (HCMV-HBc_1–183) could not be purified or characterised immunologically, although it formed core like particles. HBc_3–144-HCMV displayed HBc antigenicity but HCMV antigenicity could not be detected by radioimmunoassay or western blotting using anti-HCMV monoclonal antibody 7–17 or an anti-HCMV human polyclonal antiserum. Following immunisation of rabbits with HBc_3–144-HCMV, a high titre of anti-HBc specific antibody was produced along with lower titres of HCMV/gp58 specific antibody.     

Folded Structures in Protonated Reduced Dipeptides

Reduced dipeptides with the general formula RCO-Xaa- rXbb-N⁺HR′R′′ (rXbb, reduced analogue of residue Xbb: NH-C^α HR¹ -C_r H₂) are shown to adopt a folded conformation in solution and in the solid state. The protonated reduced amide bond is an active proton donor capable of interacting with a peptide carbonyl to give a strong hydrogen bond topologically equivalent to the i+2 or i+3? i interaction. The resulting conformation is similar to the γ- or β-turn structure found in peptides and proteins.     

The Influence of Genotype and Environment on the Physiological and Metabolic Diversity ofFusarium compactum

Talbot, N. J., Vincent, P., and Wildman, H. G. 1996. The influence of genotype and environment on the physiological and metabolic diversity ofFusarium compactum. Fungal Genetics and Biology20,254–267. Fungal species produce a large variety of secondary metabolites which are of considerable interest to the pharmaceutical industry. It is clear that the secondary metabolite production of a species varies significantly in strains from different geographic locations and from different habitats. The influence of genotype and environment on metabolite production is, however, poorly understood. In this study we examined the influence of genotypic variability, physiological variability, environmental location, and habitat on metabolite production byFusarium compactum.Isolates of the fungus from two geographic locations and two distinct habitat types were examined for growth on 95 different carbon sources, and genotypic variability was determined using RAPDs and rDNA–RFLP analysis. In a blind test secondary metabolite production was assessed using HPLC profiles of methanolic cell extracts. A number of correlations were observed between genotypic groupings, as determined using parsimony, and specific metabolite production. Similar correlations were also observed with physiological groups although genotypic analysis proved to be a more sensitive predictor of metabolite variability. The data suggest a complex relationship between environment, genotype, and metabolite production but highlight the use of genetic screening as a means of optimizing the chances of identifying a wide range of metabolites from a given species.     

Imprecise exposure assessment and the sample size requirements of case-control studies of residential magnetic field exposure and cancer in adults

A computer program simulating case-control studies is described. It is used to estimate the minimum sample size required and to assess how this is affected by imprecise exposure assessment. In particular, the consequences of neglecting measurements of nonresidential exposure in case-control studies of residentially exposed adults are investigated. According to this model, while the consequent loss of power is not as large as was predicted by algebraic methods, it would be unwise to neglect it when planning a study. © 1995 Wiley-Liss, Inc.     

Photophysics of the fluorescent K+ indicator PBFI.

The fluorescent indicator PBFI is widely used for the determination of intracellular concentrations of K+. To investigate the binding reaction of K+ to PBFI in the ground and excited states, steady-state and time-resolved measurements were performed. The fluorescence decay surface was analyzed with global compartmental analysis yielding the following values for the rate constants at room temperature in aqueous solution at pH 7.2: k01 = 1.1 x 10(9) s-1, k21 = 2.7 x 10(8) M-1s-1, k02 = 1.8 x 10(9) s-1, and k12 = 1.4 x 10(9) s-1. k01 and k02 denote the respective deactivation rate constants of the K+ free and bound forms of PBFI in the excited state. k21 represents the second-order rate constant of binding of K+ to the indicator in the excited state whereas k12 is the first-order rate constant of dissociation of the excited K(+)-PBFI complex. From the estimated values of k12 and k21, the dissociation constant Kd* in the excited state was calculated. It was found that pKd* (-0.7) is smaller than pKd (2.2). The effect of the excited-state reaction can be neglected in the determination of Kd and/or the K+ concentration. Therefore, intracellular K+ concentrations can be accurately determined from fluorimetric measurements by using PBFI as K+ indicator.