Enantioselective reduction of C=N double bond by chromium(II) complexes of natural amino acids

Asymmetric reduction of oximes was performed by chromium(II) complexes of natural amino acids in aqueous phase or in H(2)O/DMF (1:1) solvent. Medium-to-quantitative chemoselectivity (54% to >95%) and low-to-medium enantioselectivity (5-50% ee) were found.     

Analysis of yeast isolates related to Metschnikowia pulcherrima using the partial sequences of the large subunit rDNA and the actin gene; description of Metschnikowia andauensis sp. nov

Thirty-two yeast isolates were cultured from guts or excrements of three different pests of corn or from the stem of healthy corn. The strains were analyzed using MSP-PCR (micro/minisatellite-primed polymerase chain reaction), sequences of the D1/D2 region of the large subunit rDNA and a 979 bp long part of the actin gene (act-1). They seem to belong to three groups that are all sister groups of Metschnikowia pulcherrima, M. fructicola and M. chrysoperlae. A new species, Metschnikowia andauensis (HA 1657^T) is described. In contrast to M. pulcherrima and M. fructicola, M. andauensis is well separated in the act-1 phylogenetic tree too.     

Mapping a syntenic modifier on mouse chromosome 1 influencing the expressivity of the compact phenotype in the myostatin mutant (MstnCmpt-dl1Abc) compact mouse

A novel method for mapping a modifier gene that is syntenic to its major gene was used to map a male-sex-limited modifier of the expressivity of the Compact phenotype in the myostatin mutant (Mstn(Cmpt-dl1Abc)) Compact mouse. The modifier was mapped to the general region of D1Mit262, 40 cM distal to Mstn on chromosome 1. Myogenin, a postulated downstream target of myostatin, maps to the same region.     

Structure of (KIAGKIA)3 aggregates in phospholipid bilayers by solid-state NMR

The interchain (13)C-(19)F dipolar coupling measured in a rotational-echo double-resonance (REDOR) experiment performed on mixtures of differently labeled KIAGKIA-KIAGKIA-KIAGKIA (K3) peptides (one specifically (13)C labeled, and the other specifically (19)F labeled) in multilamellar vesicles of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol (1:1) shows that K3 forms close-packed clusters, primarily dimers, in bilayers at a lipid/peptide molar ratio (L/P) of 20. Dipolar coupling to additional peptides is weaker than that within the dimers, consistent with aggregates of monomers and dimers. Analysis of the sideband dephasing rates indicates a preferred orientation between the peptide chains of the dimers. The combination of the distance and orientation information from REDOR is consistent with a parallel (N-N) dimer structure in which two K3 helices intersect at a cross-angle of approximately 20 degrees. Static (19)F NMR experiments performed on K3 in oriented lipid bilayers show that between L/P = 200 and L/P = 20, K3 chains change their absolute orientation with respect to the membrane normal. This result suggests that the K3 dimers detected by REDOR at L/P = 20 are not on the surface of the bilayer but are in a membrane pore.     

Altered active site flexibility and a structural metal-binding site in eukaryotic dUTPase: kinetic characterization, folding, and crystallographic studies of the homotrimeric Drosophila enzyme

dUTPase is responsible for preventive DNA repair via exclusion of uracil. Developmental regulation of the Drosophila enzyme is suggested to be involved in thymine-less apoptosis. Here we show that in addition to conserved dUTPase sequence motifs, the gene of Drosophila enzyme codes for a unique Ala-Pro-rich segment. Kinetic and structural analyses of the recombinant protein and a truncation mutant show that the Ala-Pro segment is flexible and has no regulatory role in vitro. The homotrimer enzyme unfolds reversibly as a trimeric entity with a melting temperature of 54 degrees C, 23 degrees C lower than Escherichia coli dUTPase. In contrast to the bacterial enzyme, Mg(2+) binding modulates conformation of fly dUTPase, as identified by spectroscopy and by increment in melting temperature. A single well folded, but inactive, homotrimeric core domain is generated through three distinct steps of limited trypsinolysis. In fly, but not in bacterial dUTPase, binding of the product dUMP induces protection against proteolysis at the tryptic site reflecting formation of the catalytically competent closed conformer. Crystallographic analysis argues for the presence of a stable monomer of Drosophila dUTPase in crystal phase. The significant differences between prototypes of eukaryotic and prokaryotic dUTPases with respect to conformational flexibility of the active site, substrate specificity, metal ion binding, and oligomerization in the crystal phase are consistent with alteration of the catalytic mechanism and hydropathy of subunit interfaces.     

TT-232: An Anti-tumour and Anti-inflammatory Peptide Therapeutic in Clinical Development

TT-232 is a structural derivative of the peptide hormone somatostatin with selective anti-proliferative and anti-inflammatory properties. It has a strong anti-tumour activity both in vitro and in vivo on a wide range of tumour models and induces apoptosis. Its anti-tumour activity is mediated through the SSTR1 receptor and by the tumour specific isoform of pyruvate kinase. TT-232 has been shown to be a potent neurogenic inflammation inhibitory, anti-inflammatory and analgesic agent with a broader spectrum than presently available anti-inflammatory/analgesic drugs. In animal models it is effective against neurogenic inflammation and blocks neuropathic hyperalgesia where COX-1 or COX-2 inhibitors (e.g. diclofenac or meloxicam) proved ineffective. TT-232 has passed phase I clinical trials without toxicity and significant side effects. Human phase II efficacy studies are ongoing in melanoma indication. Two more oncological indications and phase II clinical trials in inflammatory diseases, including rheumatoid arthritis and burn injuries are in preparation. This compound has the perspective to become the first drug in molecularly targeted therapy of inflammation where a combined effect of anti-inflammatory, analgesic and neurogenic inflammation inhibiting activity can be achieved.     

Ecosystem engineering by foxes is mediated by the landscape context—A case study from steppic burial mounds

In intensively used landscapes, remnant grassland fragments are often restricted to places unsuitable for agricultural cultivation. Such refuges are the ancient burial mounds called “kurgans,” which are typical landscape elements of the Eurasian steppe and forest steppe zone. Due to their hill‐like shape, loose soil structure and undisturbed status kurgans provide proper habitats for burrowing mammals. Accordingly, grassland vegetation on kurgans is often exposed to bioturbation, which can influence the habitat structure and plant species pool. In our study, we explored the effect of fox burrows and landscape context on the habitat properties and vegetation composition of small landscape elements, using kurgans as model habitats. We surveyed the vegetation of fox burrows and that of the surrounding grassland on five kurgans situated in cleared landscapes surrounded by arable lands and five kurgans in complex landscapes surrounded by grazed grasslands. We recorded the percentage cover of vascular plants, the amount of litter, and soil moisture content in twelve 0.5 m × 0.5 m plots per kurgan, in a total of 120 plots. We found that foxes considerably transformed habitat conditions and created microhabitats by changing the soil nutrient availability and reducing total vegetation cover and litter. Several grassland specialist species, mostly grasses (Agropyron cristatum, Elymus hispidus, and Stipa capillata) established in the newly created microhabitats, although the cover of noxious species was also considerable. We found that landscape context influenced the sort of species which could establish on kurgans by affecting the available species pool and soil moisture. Our results revealed that foxes act as ecosystem engineers on kurgans by transforming abiotic and biotic conditions by burrowing. Their engineering activity maintains disturbance‐dependent components of dry grasslands and increases local environmental heterogeneity.     

Spatial variation in climate mediates gene flow across an island archipelago

High levels of gene flow among partially isolated populations can overwhelm selection and limit local adaptation. This process, known as “gene swamping,” can homogenize genetic diversity among populations and reduce the capacity of a species to withstand rapid environmental change. We studied brown anole lizards (Anolis sagrei) distributed across seven islands in The Bahamas. We used microsatellite markers to estimate gene flow among islands and then examined the correlation between thermal performance and island temperature. The thermal optimum for sprint performance was correlated with both mean and maximum island temperature, whereas performance breadth was not correlated with any measure of temperature variation. Gene flow between islands decreased as the difference between mean island temperatures increased, even when those islands were adjacent to one another. These data suggest that phenotypic variation is the result of either (1) local genetic adaptation with selection against immigrants maintaining variation in the thermal optimum, (2) irreversible forms of adaptive plasticity such that immigrants have reduced fitness, or (3) an interaction between fixed genetic differences and plasticity. In general, the patterns of gene flow we observed suggest that local thermal environments represent important ecological filters that can mediate gene flow on relatively fine geographic scales.     

Climate rather than geography separates two European honeybee subspecies

Both climatic and geographical factors play an important role for the biogeographical distribution of species. The Carpathian mountain ridge has been suggested as a natural geographical divide between the two honeybee subspecies Apis mellifera carnica and A. m. macedonica. We sampled one worker from one colony each at 138 traditional apiaries located across the Carpathians spanning from the Hungarian plains to the Danube delta. All samples were sequenced at the mitochondrial tRNA^Leu‐cox2 intergenic region and genotyped at twelve microsatellite loci. The Carpathians had only limited impact on the biogeography because both subspecies were abundant on either side of the mountain ridge. In contrast, subspecies differentiation strongly correlated with the various temperature zones in Romania. A. m. carnica is more abundant in regions with the mean average temperature below 9 °C, whereas A. m. macedonica honeybees are more frequent in regions with mean temperatures above 9 °C. This range selection may have impact on the future biogeography in the light of anticipated global climatic changes.