Spiropiperidine CCR5 antagonists

A novel series of CCR5 antagonists has been identified, utilizing leads from high-throughput screening which were further modified based on insights from competitor molecules. Lead optimization was pursued by balancing opposing trends of metabolic stability and potency. Selective and potent analogs with good pharmacokinetic properties were successfully developed.     

The mechanism of autocatalytic activation of plant-type L-asparaginases

Plant l-asparaginases and their bacterial homologs, such as EcAIII found in Escherichia coli, form a subgroup of the N-terminal nucleophile (Ntn)-hydrolase family. In common with all Ntn-hydrolases, they are expressed as inactive precursors that undergo activation in an autocatalytic manner. The maturation process involves intramolecular hydrolysis of a single peptide bond, leading to the formation of two subunits (alpha and beta) folded as one structural domain, with the nucleophilic Thr residue located at the freed N terminus of subunit beta. The mechanism of the autocleavage reaction remains obscure. We have determined the crystal structure of an active site mutant of EcAIII, with the catalytic Thr residue substituted by Ala (T179A). The modification has led to a correctly folded but unprocessed molecule, revealing the geometry and molecular environment of the scissile peptide bond. The autocatalytic reaction is analyzed from the point of view of the Thr(179) side chain rotation, identification of a potential general base residue, and the architecture of the oxyanion hole.     

Genetic counseling in Usher syndrome: linkage and mutational analysis of 10 Colombian families

Usher Syndrome (US), an autosomal recessive disease, is characterized by retinitis pigmentosa (RP), vestibular dysfunction, and congenital sensorineural deafness. There are three recognized clinical types of the disorder. In order to improve genetic counseling for affected families, we conducted linkage analysis and DNA sequencing in 10 Colombian families with confirmed diagnosis of US (4 type I and 6 type II). Seventy-five percent of the US1 families showed linkage to locus USH1B, while the remaining 25% showed linkage to loci USH1B and USH1C. Among families showing linkage to USH1B we found two different mutations in the MYO7A gene: IVS42-26insTTGAG in exon 43 (heterozygous state) and R634X (CGA-TGA) in exon 16 (homozygous state). All six US2 families showed linkage to locus USH2A. Of them, 4 had c.2299delG mutation (1 homozygote state and 3 heterozygous); in the remaining 2 we did not identify any pathologic DNA variant. USH2A individuals with a 2299delG mutation presented a typical and homogeneous retinal phenotype with bilateral severe hearing loss, except for one individual with a heterozygous 2299delG mutation, whose hearing loss was asymmetric, but more profound than in the other cases. The study of these families adds to the genotype-phenotype characterization of the different types and subtypes of US and facilitates genetic counseling in these families. We would like to emphasize the need to perform DNA studies as a prerequisite for genetic counseling in affected families.     

Preliminary compositional nutrient diagnosis norms for cowpea (Vigna unguiculata (L.) Walp.) grown on desert calcareous soil

This study calculated the compositional nutrient diagnosis (CND) norms of cowpea (Vigna unguiculata (L.) Walp.), as well as identified significant nutrient interactions of this crop growing in an irrigated calcareous desert soil. Three genotypes were distributed in rows in a 2-ha field. The soil showed high heterogeneity in its chemical properties. For statistical analysis, 86 foliar composite samples from healthy plants were used. Preliminary CND norms were developed using a cumulative variance ratio function and the ² distribution function. Means and standard deviations of row-centered log ratios V_X of five nutrients (N, P, K, Ca, and Mg) and a filling value R, which included all nutrients not chemically analyzed. Preliminary CND norms are: V_N^*=0.174±0.095, V_P^*=–2.172±0.234, V_K^*=–0.007±0.267, V_Ca^*=–0.022±0.146, V_Mg^*=–1.710±0.132, and V_R5^*=3.728±0.084. These CND norms are associated with dry bean yields higher than 1.88 t ha^–1, and are associated with the following foliar concentrations: 26.2 g N kg^–1, 2.5 g P kg^–1, 22.9 g K kg^–1, 21.6 g Ca kg^–1, and 4 g Mg kg^–1. Cowpea plants growing in desert calcareous soils took up lower amounts of N, P, and K than those considered as optimum in a previous report. Six interactions were strongly indicated for cowpea through principal component analyses: positive for Ca–Mg, and negative for N–Ca, N–Mg, Ca–P, Mg–P, and K–P. Furthermore, two interactions were identified using simple correlations, negative N–P and positive K–Ca.     

Developing a taxonomic identification system of Phytophthora species based on microsatellites

BackgroundPhytophthora is the most important genus of the Oomycete plant pathogens. Nowadays, there are 117 described species in this genus, most of them being primary invaders of plant tissues. The different species are causal agents of diseases in a wide range of crops and plants in natural environments. In order to develop control strategies against Phytophthoraspecies, it is important to know the biology, ecology and evolutionary processes of these important pathogens.AimsThe aim of this study was to propose and validate a low cost identification system for Phytophthora species based on a set of polymorphic microsatellite (SSRs) markers.MethodsThirty-three isolates representing Phytophthora infestans, Phytophthora andina, Phytophthora sojae, Phytophthora cryptogea, Phytophthora nicotianae, Phytophthora capsici and Phytophthora cinnamomi species were obtained, and 13 SSRs were selected as potentially transferable markers between these species. Amplification conditions, including annealing temperatures, were standardized for several markers.ResultsA subset of these markers amplified in all species, showing species-specific alleles.ConclusionsThe adaptability and impact of the identification system in Colombia, an Andean agricultural country where different Phytophthora species co-exist in the same or in several hosts grown together, are discussed.     

Alterations in cerebrospinal fluid glycerophospholipids and phospholipase A2 activity in Alzheimer's disease

Our aim is to study selected cerebrospinal fluid (CSF) glycerophospholipids (GP) that are important in brain pathophysiology. We recruited cognitively healthy (CH), minimally cognitively impaired (MCI), and late onset Alzheimer''s disease (LOAD) study participants and collected their CSF. After fractionation into nanometer particles (NP) and supernatant fluids (SF), we studied the lipid composition of these compartments. LC-MS/MS studies reveal that both CSF fractions from CH subjects have N-acyl phosphatidylethanolamine, 1-radyl-2-acyl-sn-glycerophosphoethanolamine (PE), 1-radyl-2-acyl-sn-glycerophosphocholine (PC), 1,2-diacyl-sn-glycerophosphoserine (PS), platelet-activating factor-like lipids, and lysophosphatidylcholine (LPC). In the NP fraction, GPs are enriched with a mixture of saturated, monounsaturated, and polyunsaturated fatty acid species, while PE and PS in the SF fractions are enriched with PUFA-containing molecular species. PC, PE, and PS levels in CSF fractions decrease progressively in participants from CH to MCI, and then to LOAD. Whereas most PC species decrease equally in LOAD, plasmalogen species account for most of the decrease in PE. A significant increase in the LPC-to-PC ratio and PLA₂ activity accompanies the GP decrease in LOAD. These studies reveal that CSF supernatant fluid and nanometer particles have different GP composition, and that PLA₂ activity accounts for altered GPs in these fractions as neurodegeneration progresses.     

Hematological indicators of stress in longline-captured sharks

For many shark species, little information exists about the stress response to capture and release in commercial longline fisheries. Recent studies have used hematological profiling to assess the secondary stress response, but little is known about how, and to what degree, these indicators vary interspecifically. Moreover, there is little understanding of the extent to which the level of relative swimming activity (e.g., sluggish vs. active) or the general ecological classification (e.g., coastal vs. pelagic) correlates to the magnitude of the exercise-induced (capture-related) stress response. This study compared plasma electrolytes (Na(+), Cl(-), Mg(2+), Ca(2+), and K(+)), metabolites (glucose and lactate), blood hematocrit, and heat shock protein (Hsp70) levels between 11 species of longline-captured sharks (n=164). Statistical comparison of hematological parameters revealed species-specific differences in response to longline capture, as well as differences by ecological classification. Taken together, the blood properties of longline-captured sharks appear to be useful indicators of interspecific variation in the secondary stress response to capture, and may prove useful in the future for predicting survivorship of longline-captured sharks where new technologies (i.e., pop-up satellite tags) can verify post-release mortality.     

The CarD/CarG regulatory complex is required for the action of several members of the large set of Myxococcus xanthus extracytoplasmic function σ factors

Extracytoplasmic function (ECF) σ factors are critical players in signal transduction networks involved in bacterial response to environmental changes. The Myxococcus xanthus genome reveals ～45 putative ECF‐σ factors, but for the overwhelming majority, the specific signals or mechanisms for selective activation and regulation remain unknown. One well‐studied ECF‐σ, CarQ, binds to its anti‐σ, CarR, and is inactive in the dark but drives its own expression from promoter P_QRS on illumination. This requires the CarD/CarG complex, the integration host factor (IHF) and a specific CarD‐binding site upstream of P_QRS. Here, we show that DdvS, a previously uncharacterized ECF‐σ, activates its own expression in a CarD/CarG‐dependent manner but is inhibited when specifically bound to the N‐terminal zinc‐binding anti‐σ domain of its cognate anti‐σ, DdvA. Interestingly, we find that the autoregulatory action of 11 other ECF‐σ factors studied here depends totally or partially on CarD/CarG but not IHF. In silico analysis revealed possible CarD‐binding sites that may be involved in direct regulation by CarD/CarG of target promoter activity. CarD/CarG‐linked ECF‐σ regulation likely recurs in other myxobacteria with CarD/CarG orthologous pairs and could underlie, at least in part, the global regulatory effect of the complex on M. xanthus gene expression.     

Small‐scale Farming and Grazing Reduce Regeneration of Polylepis tomentella (Rosaceae) in the Semiarid Andes of Bolivia

In the Andean highlands, Polylepis woodlands are a rare and unique ecosystem of the treeline. Although human activities have caused the loss of extensive forested areas and decreased woodland regeneration, few systematic and quantitative assessments have been carried out in Polylepis forests. This study compares differences in habitat characteristics, population structure, and reproductive output in populations of Polylepis tomentella subject to different levels of human disturbance in the south‐central Andes of Bolivia. We selected P. tomentella because the species still covers large extensions in the form of fragmented forest patches. Results show that human activities affected all the studied populations. Moderately disturbed populations exhibited a lower percentage of farmed area (0.6%) and browsed plants (4%) than strongly disturbed populations (5% and 12%, respectively). All populations exhibited similar proportion of plants with logging scars. Potassium content and canopy closure were 1.5 and 2.5 higher, respectively, in strongly disturbed populations. The density of saplings and seedlings were 75 percent and 80 percent lower in strongly disturbed populations than in moderately disturbed population, even though reproductive individuals produced twice more flowers and fruits. Our results suggest that fruit production does not limit regeneration of P. tomentella and post‐dispersal mechanisms may decrease seed germination and increase seedling mortality. Overall, strongly disturbed populations will be less likely to regenerate, leading to population decline. Conservation programs should facilitate forest recovery by promoting seedling establishment, reducing overharvesting and over‐browsing, and protecting remaining adult plants.     

Eutrophication decreases distance decay of similarity in diatom communities

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