Sostdc1 defines the size and number of skin appendage placodes

Mammary glands and hair follicles develop as ectodermal organs sharing common features during embryonic morphogenesis. The molecular signals controlling the initiation and patterning of skin appendages involve the bone morphogenetic proteins and Wnt family members, which are commonly thought to serve as inhibitory and activating cues, respectively. Here, we have examined the role of the Bmp and Wnt pathway modulator Sostdc1 in mammary gland, and hair and vibrissa follicle development using Sostdc1-null mice. Contrary to previous speculations, loss of Sostdc1 did not affect pelage hair cycling. Instead, we found that Sostdc1 limits the number of developing vibrissae and other muzzle hair follicles, and the size of primary hair placodes. Sostdc1 controls also the size and shape of mammary buds. Furthermore, Sostdc1 is essential for suppression of hair follicle fate in the normally hairless nipple epidermis, but its loss also promotes the appearance of supernumerary nipple-like protrusions. Our data suggest that functions of Sostdc1 can be largely attributed to its ability to attenuate Wnt/β-catenin signaling.     

18F]fluoro-deoxy-glucose folate: a novel PET radiotracer with improved in vivo properties for folate receptor targeting

The folate receptor (FR) is upregulated in various cancer types (FR-α isoform) and in activated macrophages (FR-β isoform) which are involved in inflammatory and autoimmune diseases, but its expression in healthy tissues and organs is highly restricted to only a few sites (e.g kidneys). Therefore, the FR is a promising target for imaging and therapy of cancer and inflammation using folate-based radiopharmaceuticals. Herein, we report the synthesis and evaluation of a novel folic acid conjugate with improved properties suitable for positron emission tomography (PET). [(18)F]-fluoro-deoxy-glucose folate ([(18)F]3) was synthesized based on the click chemistry approach using 2-deoxy-2-[(18)F]fluoroglucopyranosyl azide and a folate alkyne derivative. The novel radiotracer [(18)F]3 was produced in good radiochemical yields (25% d.c.) and high specific radioactivity (90 GBq/μmol). Compared to previously published (18)F-folic acid derivatives, an increase in hydrophilicity was achieved by using a glucose entity as a prosthetic group. Biodistribution and PET imaging studies in KB tumor-bearing mice showed a high and specific uptake of the radiotracer in FR-positive tumors (10.03 ± 1.12%ID/g, 60 min p.i.) and kidneys (42.94 ± 2.04%ID/g, 60 min p.i.). FR-unspecific accumulation of radioactivity was only found in the liver (9.49 ± 1.13%ID/g, 60 min p.i.) and gallbladder (17.59 ± 7.22%ID/g, 60 min p.i.). No radiometabolites were detected in blood, urine, and liver tissue up to 30 min after injection of [(18)F]3. [(18)F]-fluoro-deoxy-glucose-folate ([(18)F]3) is thus a promising PET radioligand for imaging FR-positive tumors.     

Habitat stability affects dispersal and the ability to track climate change

Habitat persistence should influence dispersal ability, selecting for stronger dispersal in habitats of lower temporal stability. As standing (lentic) freshwater habitats are on average less persistent over time than running (lotic) habitats, lentic species should show higher dispersal abilities than lotic species. Assuming that climate is an important determinant of species distributions, we hypothesize that lentic species should have distributions that are closer to equilibrium with current climate, and should more rapidly track climatic changes. We tested these hypotheses using datasets from 1988 and 2006 containing all European dragon- and damselfly species. Bioclimatic envelope models showed that lentic species were closer to climatic equilibrium than lotic species. Furthermore, the models over-predicted lotic species ranges more strongly than lentic species ranges, indicating that lentic species track climatic changes more rapidly than lotic species. These results are consistent with the proposed hypothesis that habitat persistence affects the evolution of dispersal.     

Classification of vegetational diversity in managed boreal forests in eastern Finland

Diversity of vegetation in managed forests is studied. A classification based on forest stand structure, the abundances of vegetation species and variations in these abundances is developed and diversity indices are calculated for the classes to describe the diversity of the vegetation within the classes. The classes were formed using detrended correspondence analysis (DCA), global nonmetric multidimensional scaling (GNMDS) and TWINSPAN classification. Discriminant analysis was used to determine the environmental variables differentiating between the classes, and Duncan's multiple range test was used to examine the ability of the diversity measures to distinguish the classes. Beta diversity was estimated with Økland's method based on DCA ordination of the sample plots. The results point to fertility and the successional stage of the stand as the main factors affecting species diversity, in addition to which soil type, the number of tree species, crown cover, basal area and certain variables describing the management of the stand were relevant to the classification. The most distinct diversity indices were the reciprocal of Simpson, Pielou's J' and species richness, while the highest alpha diversity was found in young stands with a low crown cover on herb-rich or mesic forest sites. Beta diversity was quite high, its highest values of all for the whole data being recorded along the fertility gradient.     

Characterization of nucleotide binding sites of the isolated H(+)-ATPase from spinach chloroplasts, CF(0)F(1)

Soluble purified CF(0)F(1) from chloroplasts was either oxidized or reduced and then incubated with [alpha-(32)P]ATP in the presence or in the absence of Mg(2+). Depending on the conditions of incubation, the enzyme showed different tight-nucleotide binding sites. In the presence of EDTA, two sites bind [alpha-(32)P]ATP from the reaction medium at different rates. Both sites promote ATP hydrolysis, since equimolar amounts of [alpha-(32)P]ATP and [alpha-(32)P]ADP are bound to the enzyme. In the presence of Mg(2+), only one site appears during the first hour of incubation, with characteristics similar to those described in the absence of Mg(2+). However, after this time a third site appears also permitting binding of ATP from the reaction medium, but in this case the bound ATP is not hydrolyzed. Covalent derivatization by 2-azido-[alpha-(32)P]ATP was used to distinguish between catalytic and noncatalytic sites. In the presence of Mg(2+), there are at least three distinct nucleotide binding sites that bind nucleotide tightly from the reaction medium: two of them are catalytic and one is noncatalytic.     

Identification of and spatio-temporal differences between microbial assemblages from two neighboring sulfurous lakes: comparison by microscopy and denaturing gradient gel electrophoresis

The microbial assemblages of Lake Cisó and Lake Vilar (Banyoles, northeast Spain) were analyzed in space and time by microscopy and by performing PCR-denaturing gradient gel electrophoresis (DGGE) and sequence analysis of 16S rRNA gene fragments. Samples obtained from different water depths and at two different times of the year (in the winter during holomixis and in the early spring during a phytoplankton bloom) were analyzed. Although the lakes have the same climatic conditions and the same water source, the limnological parameters were different, as were most of the morphologically distinguishable photosynthetic bacteria enumerated by microscopy. The phylogenetic affiliations of the predominant DGGE bands were inferred by performing a comparative 16S rRNA sequence analysis. Sequences obtained from Lake Cisó samples were related to gram-positive bacteria and to members of the division Proteobacteria. Sequences obtained from Lake Vilar samples were related to members of the Cytophaga-Flavobacterium-Bacteroides phylum and to cyanobacteria. Thus, we found that like the previously reported differences between morphologically distinct inhabitants of the two lakes, there were also differences among the community members whose morphologies did not differ conspicuously. The changes in the species composition from winter to spring were also marked. The two lakes both contained sequences belonging to phototrophic green sulfur bacteria, which is consistent with microscopic observations, but these sequences were different from the sequences of cultured strains previously isolated from the lakes. Euryarchaeal sequences (i.e., methanogen- and thermoplasma-related sequences) also were present in both lakes. These euryarchaeal group sequences dominated the archaeal sequences in Lake Cisó but not in Lake Vilar. In Lake Vilar, a new planktonic population related to the crenarchaeota produced the dominant archaeal band. The phylogenetic analysis indicated that new bacterial and archaeal lineages were present and that the microbial diversity of these assemblages was greater than previously known. We evaluated the correspondence between the abundances of several morphotypes and DGGE bands by comparing microscopy and sequencing results. Our data provide evidence that the sequences obtained from the DGGE fingerprints correspond to the microorganisms that are actually present at higher concentrations in the natural system.     

Structural evidence for ligand specificity in the binding domain of the human androgen receptor. Implications for pathogenic gene mutations

The crystal structures of the human androgen receptor (hAR) and human progesterone receptor ligand-binding domains in complex with the same ligand metribolone (R1881) have been determined. Both three-dimensional structures show the typical nuclear receptor fold. The change of two residues in the ligand-binding pocket between the human progesterone receptor and hAR is most likely the source for the specificity of R1881 to the hAR. The structural implications of the 14 known mutations in the ligand-binding pocket of the hAR ligand-binding domains associated with either prostate cancer or the partial or complete androgen receptor insensitivity syndrome were analyzed. The effects of most of these mutants could be explained on the basis of the crystal structure.     

Denaturation of phosphofructokinase-1 from Saccharomyces cerevisiae by guanidinium chloride and reconstitution of the unfolded subunits to their catalytically active form

Unfolding and refolding of heterooctameric phosphofructokinase-1 from Saccharomyces cerevisiae were investigated by application of kinetic, hydrodynamic, and spectroscopic methods and by use of guanidinium chloride (GdmCl) as denaturant. Inactivation of the enzyme starts at about 0.3 M GdmCl and undergoes a sharp unfolding transition in a narrow range of the denaturant concentration. The inactivation is accompanied by a dissociation of the enzyme into dimers (at 0.6 M GdmCl), which could be detected by changes of the circular dichroism and intrinsic fluorescence. Protein aggregates were observed from 0.7 to 1.5 M GdmCl that unfold at higher denaturant concentrations. Refolding of chemically denatured phosphofructokinase proceeds as a stepwise process via the generation of elements of secondary structure, the formation of assembly-competent monomers that associate to heterodimers and the assembly of dimers to heterotetramers and heterooctamers. The assembly reactions seem to be rate-limiting. Recovery of the enzyme activity (maximum 65%) competes with an nonproductive aggregation of the subunits. alpha-Cyclodextrin functions as an artificial chaperone by preventing aggregation of the subunits, whereas ATP is suggested to support the generation of heterodimers that are competent to a further assembly.