A bHLH transcription factor mediates organ, region and flower type specific signals on dihydroflavonol-4-reductase ( dfr ) gene expression in the inflorescence of Gerbera hybrida (Asteraceae)

The angiosperm family Asteraceae is characterized by composite inflorescences, which are highly organized structures consisting of different types of flowers. In order to approach the control of floral organ differentiation in Asteraceae at molecular level, we are studying regulation of flavonoid biosynthesis in Gerbera hybrida . Dihydroflavonol-4-reductase ( dfr ) expression is regulated according to anthocyanin pigmentation patterns in all tested gerbera varieties at several anatomical levels. We have isolated a promoter for one of the dfr genes, Pgdfr2 . Gerbera plants transgenic for a Pgdfr2 - uidA construct reveal that the activity of the Pgdfr2 promoter from one variety follows the pigmentation in other varieties which have different color patterns. It is thus evident that the observed complex regulation of dfr expression occurs in trans . In order to identify the trans -acting regulators, we isolated a cDNA ( gmyc1 ) homologous to the previously characterized genes encoding bHLH-type regulators of the anthocyanin pathway in plants. The expression of gmyc1 in different varieties suggests that it has a major role in regulating dfr activity in corolla and carpel, but not in pappus and stamen. Specifically in gerbera, the identical patterns of gmyc1 and dfr expression in corolla tissue suggest that GMYC1 also regulates dfr expression in a region and flower type specific manner. Our studies show that in gerbera GMYC1– dfr interaction is part of several developmental processes characteristic for Asteraceae (such as specification of flower types across the composite inflorescence), whereas in other processes (such as differentiation of sepal as pappus) other regulators control dfr expression to determine the spatial specificity.     

Structural basis of GDP release and gating in G protein coupled Fe2+ transport

G proteins are key molecular switches in the regulation of membrane protein function and signal transduction. The prokaryotic membrane protein FeoB is involved in G protein coupled Fe²⁺ transport, and is unique in that the G protein is directly tethered to the membrane domain. Here, we report the structure of the soluble domain of FeoB, including the G protein domain, and its assembly into an unexpected trimer. Comparisons between nucleotide free and liganded structures reveal the closed and open state of a central cytoplasmic pore, respectively. In addition, these data provide the first observation of a conformational switch in the nucleotide‐binding G5 motif, defining the structural basis for GDP release. From these results, structural parallels are drawn to eukaryotic G protein coupled membrane processes.     

SAF,a New Cell Aggregation Factor Produced by Streptomyces murinus Strain No. A-2805

We searched for a new cell aggregation factor, and found one we called SAF in the mycelia of a strain of Streptomyces murinus. SAF was purified by active carbon and ion exchange column chromatographies and gel filtration of Sepharose 2B from the homogenized mycelia by sonication. SAF was stable from pH 7 to 9 at 37°C and up to 40°C at pH 8.0. The aggregation activity of SAF was maximum around pH 8.0 at 30°C, and the factor required for its activity metallic ions such as calcium and manganese. The aggregation activity of SAF was inhibited by laminarin, but it was not influenced by various other saccharides. SAF aggregated E. coli, S. aureus, M. luteus, sarcoma 180, and HeLa cells as well as S. marcescens, above all, its highest activity was toward B. subtilis, but P. vulgaris, P. aeruginosa, C. albicans, each type of human erythrocytes, and hepatoma 109A cells were quite resistant to SAF. These properties has proved that SAF is completely different from the other aggregation factors so far reported.     

Cross-cultural variation in men's preference for sexual dimorphism in women's faces

Both attractiveness judgements and mate preferences vary considerably cross-culturally. We investigated whether men''s preference for femininity in women''s faces varies between 28 countries with diverse health conditions by analysing responses of 1972 heterosexual participants. Although men in all countries preferred feminized over masculinized female faces, we found substantial differences between countries in the magnitude of men''s preferences. Using an average femininity preference for each country, we found men''s facial femininity preferences correlated positively with the health of the nation, which explained 50.4% of the variation among countries. The weakest preferences for femininity were found in Nepal and strongest in Japan. As high femininity in women is associated with lower success in competition for resources and lower dominance, it is possible that in harsher environments, men prefer cues to resource holding potential over high fecundity.     

Impacts of gene bioaugmentation with pJP4-harboring bacteria of 2,4-D-contaminated soil slurry on the indigenous microbial community

Gene bioaugmentation is a bioremediation strategy that enhances biodegradative potential via dissemination of degradative genes from introduced microorganisms to indigenous microorganisms. Bioremediation experiments using 2,4-dichlorophenoxyacetic acid (2,4-D)-contaminated soil slurry and strains of Pseudomonas putida or Escherichia coli harboring a self-transmissible 2,4-D degradative plasmid pJP4 were conducted in microcosms to assess possible effects of gene bioaugmentation on the overall microbial community structure and ecological functions (carbon source utilization and nitrogen transformation potentials). Although exogenous bacteria decreased rapidly, 2,4-D degradation was stimulated in bioaugmented microcosms, possibly because of the occurrence of transconjugants by the transfer of pJP4. Terminal restriction fragment length polymorphism analysis revealed that, although the bacterial community structure was disturbed immediately after introducing exogenous bacteria to the inoculated microcosms, it gradually approached that of the uninoculated microcosms. Biolog assay, nitrate reduction assay, and monitoring of the amoA gene of ammonia-oxidizing bacteria and nirK and nirS genes of denitrifying bacteria showed no irretrievable depressive effects of gene bioaugmentation on the carbon source utilization and nitrogen transformation potentials. These results may suggest that gene bioaugmentation with P. putida and E. coli strains harboring pJP4 is effective for the degradation of 2,4-D in soil without large impacts on the indigenous microbial community.     

Key issues in the acquisition and analysis of qualitative and quantitative mass spectrometry data for peptide-centric proteomic experiments

Proteomic technologies have matured to a level enabling accurate and reproducible quantitation of peptides and proteins from complex biological matrices. Analysis of samples as diverse as assembled protein complexes, whole cell lysates or sub-cellular proteomes from cell cultures, and direct analysis of animal and human tissues and fluids demonstrate the incredible versatility of the fundamental nature of the technique that forms the basis of most proteomic applications today (mass spectrometry). Determining the mass of biomolecules and their fragments or related products with high accuracy can convey a highly specific assay for detection and identification. Importantly, ion currents representative of these specifically identified analytes can be accurately quantified with the correct application of smart isobaric tagging chemistries, heavy and light isotopically derivatised samples or standards, or by careful application of workflows to compare unlabelled samples in so-called 'label-free' and targeted selected reaction monitoring experiments. In terms of exploring biology, a myriad of protein changes and modifications are being increasingly probed and quantified, including diverse chemical changes from relatively decisive modifications such as protein splicing and truncation, to more transient dynamic modifications such as phosphorylation, acetylation and ubiquitination. Proteomic workflows can be complex beasts and several key considerations to ensure effective applications have been outlined in the recent literature. The past year has witnessed the publication of several excellent reviews that thoroughly describe the fundamental principles underlying the state of the art. This review further elaborates on specific critical issues introduced by these publications and raises other important unaddressed considerations and new developments that directly impact on the effectiveness of proteomic technologies, in particular for, but not necessarily exclusive to peptide-centric experiments. These factors are discussed both in terms of qualitative analyses, including dynamic range and sampling issues, and developments to improve the translation of peptide fragmentation data into peptide and protein identities, as well as quantitative analyses, including data normalisation and the utility of ontology or functional annotation, the effects of modified peptides, and considered experimental design to facilitate the use of robust statistical methods.     

Fused bicyclic heteroarylpiperazine-substituted l-prolylthiazolidines as highly potent DPP-4 inhibitors lacking the electrophilic nitrile group

Hypoglycemic agents with a mechanism of depeptidyl peptidase IV (DPP-4) inhibition are suitable for once daily oral dosing. It is difficult to strike a balance between inhibitory activity and duration of action in plasma for inhibitors bearing an electrophilic nitrile group. We explored fused bicyclic heteroarylpiperazine substituted at the γ-position of the proline structure in the investigation of l-prolylthiazolidines lacking the electrophilic nitrile. Among them, 2-trifluoroquinolyl compound 8g is the most potent, long-lasting DPP-4 inhibitor (IC(50)=0.37nmol/L) with high selectivity against other related peptidases. X-ray crystal structure determination of 8g indicates that CH-π interactions generated between the quinolyl ring and the guanidinyl group of Arg358 enhances the DPP-4 inhibitory activity and selectivity.