Linking SNPs to CAG repeat length in Huntington's disease patients

Allele-specific silencing using small interfering RNAs targeting heterozygous single-nucleotide polymorphisms (SNPs) is a promising therapy for human trinucleotide repeat diseases such as Huntington's disease. Linking SNP identities to the two HTT alleles, normal and disease-causing, is a prerequisite for allele-specific RNA interference. Here we describe a method, SNP linkage by circularization (SLiC), to identify linkage between CAG repeat length and nucleotide identity of heterozygous SNPs using Huntington's disease patient peripheral blood samples.     

Autophagy in hematopoietic stem/progenitor cells exposed to heavy metals: Biological implications and toxicological relevance

The inherent toxicity of many metal compounds, together with their widespread environmental distribution, raises concerns of potential health hazards. Little is known about the impact of these important environmental toxicants on adult stem/progenitor cells, necessary for tissue homeostasis and repair. We recently reported that autophagy is implicated in the response of hematopoietic stem/progenitor cells to toxic concentrations of hexavalent chromium (Cr[VI]) and cadmium (Cd), two well known carcinogenic heavy metal cations. Autophagy may lead to cell death if carried out too extensively, but also acts as a survival pathway in cells under stress. In stem/progenitor cells, an autophagic phenotype could mitigate metal-induced toxicity, contributing to the conservation of tissue renewal capability. Given the key role of toxic damage to adult stem/progenitor cells in cancer, it is necessary to investigate whether autophagic responses modulate the carcinogenic potential of exposure to heavy metals during stem/progenitor cell differentiation.     

Synthesis and activity of N-cyanoguanidine-piperazine P2X7 antagonists

A novel series of cyanoguanidine-piperazine P2X₇ antagonists were identified and structure–activity relationship (SAR) studies described. Compounds were assayed for activity at human and rat P2X₇ receptors in addition to their ability to inhibit IL-1β release from stimulated human whole blood cultures. Compound 27 possesses potent activity (0.12 μM) in this latter assay and demonstrates moderate clearance in-vivo.     

In vitro SAR of pyrrolidine-containing histamine H3 receptor antagonists: trends across multiple chemical series

Structure-activity relationships (SAR) were analyzed within a library of diverse yet simple compounds prepared as histamine H3 antagonists. The libraries were constructed with a variety of low molecular weight pyrrolidines, selected from (R)-2-methylpyrrolidine, (S)-2-methylpyrrolidine, and pyrrolidine.     

Progressive island colonization and ancient origin of Hawaiian Metrosideros (Myrtaceae)

Knowledge of the evolutionary history of plants that are ecologically dominant in modern ecosystems is critical to understanding the historical development of those ecosystems. Metrosideros is a plant genus found in many ecological and altitudinal zones throughout the Pacific. In the Hawaiian Islands, Metrosideros polymorpha is an ecologically dominant species and is also highly polymorphic in both growth form and ecology. Using 10 non-coding chloroplast regions, we investigated haplotype diversity in the five currently recognized Hawaiian Metrosideros species and an established out-group, Metrosideros collina, from French Polynesia. Multiple haplotype groups were found, but these did not match morphological delimitations. Alternative morphologies sharing the same haplotype, as well as similar morphologies occurring within several distinct island clades, could be the result of developmental plasticity, parallel evolution or chloroplast capture. The geographical structure of the data is consistent with a pattern of age progressive island colonizations and suggests de novo intra-island diversification. If single colonization events resulted in a similar array of morphologies on each island, this would represent parallel radiations within a single, highly polymorphic species. However, we were unable to resolve whether the pattern is instead explained by ancient introgression and incomplete lineage sorting resulting in repeated chloroplast capture. Using several calibration methods, we estimate the colonization of the Hawaiian Islands to be potentially as old as 3.9 (-6.3) Myr with an ancestral position for Kaua'i in the colonization and evolution of Metrosideros in the Hawaiian Islands. This would represent a more ancient arrival of Metrosideros to this region than previous studies have suggested.     

Alkyl deoxy-arabino-hexopyranosides: synthesis, surface properties, and biological activities

Octyl and dodecyl glycosides possessing 2-deoxy-arabino-hexopyranoside moieties belonging to the D- and L-series in their alpha- and beta-forms were synthesized by reaction of an acetyl protected glycal with octanol or dodecanol, catalyzed by triphenylphosphine hydrobromide, followed by deprotection. Their surface properties were studied and discussed in terms of the adsorption and aggregation parameters, pC(20), CMC, and gamma(CMC). The antimicrobial activities were assessed using the paper disk diffusion and broth dilution methods. Both the octyl and dodecyl 2-deoxy beta-D-glycosides inhibited significantly Enterococcus faecalis, a microbe also highly susceptible to dodecyl 2,6-dideoxy-alpha-L-arabino-hexopyranoside. This compound was particularly active against Bacillus cereus and Bacillus subtilis, presenting for both Bacillus species a minimal inhibitory concentration of the same order of magnitude and a minimal lethal concentration even smaller than that obtained for chloramphenicol, a bioactivity which remained unaltered after 1 year solution storage at 4 degrees C. In addition, activity over Listeria monocytogenes was also observed. Direct cytotoxicity and genotoxicity of the glycosides were determined by proliferative index (mitotic index) evaluation in peripheral human lymphocytes of healthy donors. All compounds induced acute toxicity effects, and the response was dose dependent for the alpha-anomer of both the alkyl 2-deoxy-arabino-hexopyranosides and for the corresponding dodecyl beta-anomer, what suggests that non-toxic but still bioactive concentrations may be found for these compounds.     

Use of positive reinforcement conditioning to monitor pregnancy in an unanesthetized snow leopard (Uncia uncia) via transabdominal ultrasound

Closely monitoring snow leopard (Uncia uncia) fetal developments via transabdominal ultrasound, with minimal stress to the animal, was the goal of this project. The staff at Potter Park Zoo has used the principles of habituation, desensitization, and positive reinforcement to train a female snow leopard (U. uncia). Ultrasound examinations were preformed on an unanesthetized feline at 63 and 84 days. The animal remained calm and compliant throughout both procedures. Fetuses were observed and measured on both occasions. The absence of anesthesia eliminated components of psychologic and physiologic stress associated with sedation. This was the first recorded instance of transabdominal ultrasound being carried out on an unanesthetized snow leopard. It documents the feasibility of detecting pregnancy and monitoring fetal development via ultrasound. Zoo Biol 27:78–85, 2008. © 2007 Wiley‐Liss, Inc.     

Identification of an amino acid determinant of pH regiospecificity in a seed lipoxygenase from Momordica charantia

Lipoxygenases (LOX) form a heterogeneous family of lipid peroxidizing enzymes, which catalyze specific dioxygenation of polyunsaturated fatty acids. According to their positional specificity of linoleic acid oxygenation plant LOX have been classified into linoleate 9- and linoleate 13-LOX and recent reports identified a critical valine at the active site of 9-LOX. In contrast, more bulky phenylalanine or histidine residues were found at this position in 13-LOX. We have recently cloned a LOX-isoform from Momordica charantia and multiple amino acid alignments indicated the existence of a glutamine (Gln599) at the position were 13-LOX usually carry histidine or phenylalanine residues. Analyzing the pH-dependence of the positional specificity of linoleic acid oxygenation we observed that at pH-values higher than 7.5 this enzyme constitutes a linoleate 13-LOX whereas at lower pH, 9-H(P)ODE was the major reaction product. Site-directed mutagenesis of glutamine 599 to histidine (Gln599His) converted the enzyme to a pure 13-LOX. These data confirm previous observation suggesting that reaction specificity of certain LOX-isoforms is not an absolute enzyme property but may be impacted by reaction conditions such as pH of the reaction mixture. We extended this concept by identifying glutamine 599 as sequence determinant for such pH-dependence of the reaction specificity. Although the biological relevance for this alteration switch remains to be investigated it is of particular interest that it occurs at near physiological conditions in the pH-range between 7 and 8.     

Bromoperoxidase activity and vanadium level of the brown alga Ascophyllum nodosum

Vanadium-dependent peroxidase activity in extracts of Ascophyllum nodosum growing in the intertidal region close to Roscoff/France, and algal vanadium levels, followed approximately similar seasonal variation, as deduced from a study lasting from April 2005 to March 2006. High peroxidase (PO) activity was found in extracts obtained from algae collected in between midwinter to spring [∼100-190 U per g dry mass (dm), triiodide assay] with a maximum in April. Periods of reduced PO activity lasted from summer to early winter (∼50-90 U per g dm). High vanadium levels (1.5-2.2 mg kg⁻¹ dm) were found in algae collected from midwinter to spring, whereas reduced levels (0.6-1.4 mg kg⁻¹ dm) were found in summer to early winter.