Simultaneous determination of diastereoisomeric and enantiomeric impurities in (1R, 3R)-1-(1,3-benzodioxol-5-yl)-2-(chloroacetyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid methyl ester a key intermediate of tadalafil by chiral high-performance liquid chromatography

(1R, 3R)-1-(1, 3-Benzodioxol-5-yl)-2-(chloroacetyl)-2, 3, 4, 9-tetrahydro-1H-pyrido[3, 4-b]indole-3-carboxylic acid methyl ester ((1R, 3R)-Cpe) is a key intermediate used in the synthesis of tadalafil, a highly selective phosphodiesterase type-5 inhibitor. In the present study, a chiral high-performance liquid chromatography method was developed for the simultaneous determination of diastereoisomeric and enantiomeric impurities in (1R, 3R)-Cpe. Separation was performed on an Ultron ES-OVM chiral column (150 mm × 4.6 mm, 5 μm,) with a guard column at a column temperature of 30°C. The gradient elution used was acetonitrile (solvent A) and water (solvent B), and the following elution program was used at a flow rate of 1 ml/min: 0-5 min (80% B), 5-10 min (80-60% B), 10-12 min (60% B). The detection wavelength was 220 nm. The four isomers of Cpe were baseline separated in 12 min. The results of method validation indicated that the method was specific and sensitive and was suitable for the quality control of diastereoisomeric and enantiomeric impurities in (1R, 3R)-Cpe.     

Effects of sap velocity on the daytime increase of stem CO2 efflux from stems of Schima superba trees

Stem CO₂ efflux (E _s) has been estimated from a temperature-related equation, but sap flux often affects measurements of E _s, which leads to misunderstanding real stem respiration. In order to observe the relationship between E _s and stem temperature and to analyze the effect of sap velocity on E _s, stem temperature, E _s and sap flux were measured from a subtropical Schima superba plantation in South China on three trees for consecutive 3 days in July and October 2009. Stem temperature, E _s and sap velocity were significantly higher in July than in October. Stem temperature could explain 17–41 and 54–75% variations of E _s in July and October, respectively. A negative relationship between E _s and stem temperature was found during 1800–2300 hours in July. The daytime E _s was 9.2, 4.3 and 2.4% higher than the predicted for three trees in July, and this occurred only on Tree 1 in October. Sap velocity was positively correlated with E _s for three trees in July, and the increase of E _s with the increase of sap velocity was only observed on Tree 1 in October. These results demonstrated that the occurrence of sap flux could account for the increase of daytime E _s, and the effect of sap velocity on E _s varied with the seasons from the S. superba stem.     

Tunable pores for measuring concentrations of synthetic and biological nanoparticle dispersions

Scanning ion occlusion sensing (SIOS), a technique that uses a tunable pore to detect the passage of individual nano-scale objects, is applied here for the rapid, accurate and direct measurement of synthetic and biological nanoparticle concentrations. SIOS is able to characterize smaller particles than other direct count techniques such as flow cytometry or Coulter counters, and the direct count avoids approximations such as those necessary for turbidity measurements. Measurements in a model system of 210-710 nm diameter polystyrene particles demonstrate that the event frequency scales linearly with applied pressure and concentration, and that measured concentrations are independent of particle type and size. Both an external-calibration and a calibration-free measurement method are demonstrated. SIOS is then applied to measure concentrations of Baculovirus occlusion bodies, with a diameter of ~1 μm, and the marine photosynthetic cyanobacterium Prochlorococcus, with a diameter of ~600 nm. The determined concentrations agree well with results from counting with microscopy (a 17% difference between the mean concentrations) and flow cytometry (6% difference between the mean concentrations), respectively.     

Probe droplet arrays generated in the capillary for microarray analysis

Microarray technology is a useful tool for nucleic acid detection and has been widely used in biology and related research fields. However, the procedure is labor intensive and time consuming. Microfluidic chip-based microarrays save time with better performance, but the low spot density and probe number limit its applications. To develop high performance microarrays with high spot density within a microchannel, a method is reported here for preparing microarrays in a capillary by generating probe droplet arrays. The probes in droplets are immobilized onto the inner wall of the capillary to form a one-dimensional probe array, and then a sample solution is introduced to hybridize with the probe array. The effect of the capillary's inner diameter was evaluated to realize a high-density probe array. The processes of array generation and probe immobilization were studied to avoid possible cross contamination. The background from probe immobilization during the array generation and incubation was quantified to assure sensitivity. Multiple sample detection was also demonstrated within one capillary. The capillary based microarray assay had high spot density, easy fabrication, fast detection, high sensitivity and multiple sample capacity.     

Predation of the oriental fruit fly,Bactrocera dorsalis puparia by the red imported fire ant,Solenopsis invicta: role of host olfactory cues and soil depth

Predation by red imported fire ants, Solenopsis invicta on oriental fruit fly, Bactrocera dorsalis puparia was evaluated. No significant olfactory response of the workers was observed at 0, 2 and 4 days after fly pupation, whereas the workers were significantly attracted by the 6th day old puparia. We found S. invicta that predated on puparia of B. dorsalis in the field. The predation rate was negatively correlated with the depth of puparia in the soil. The predation rate was 70% at 4 cm depth; whereas, zero predation rate was observed at 6 cm depth. The predation rate was also significantly affected by soil moisture. The predation rate was 66.5% and 72.1% at soil moisture values of 40% and 80%, respectively, and no predation occurred at soil moisture value of 0%.     

Distinctive expression patterns and roles of the miRNA393/TIR1 homolog module in regulating flag leaf inclination and primary and crown root growth in rice (Oryza sativa)

? MicroRNA (miRNA)-mediated regulation of auxin signaling components plays a critical role in plant development. miRNA expression and functional diversity contribute to the complexity of regulatory networks of miRNA/target modules. ? This study functionally characterizes two members of the rice (Oryza sativa) miR393 family and their target genes, OsTIR1 and OsAFB2 (AUXIN SIGNALING F-BOX), the two closest homologs of Arabidopsis TRANSPORT INHIBITOR RESPONSE 1 (TIR1). ? We found that the miR393 family members possess distinctive expression patterns, with miR393a expressed mainly in the crown and lateral root primordia, as well as the coleoptile tip, and miR393b expressed in the shoot apical meristem. Transgenic plants overexpressing miR393a/b displayed a severe phenotype with hallmarks of altered auxin signaling, mainly including enlarged flag leaf inclination and altered primary and crown root growth. Furthermore, OsAFB2- and OsTIR1-suppressed lines exhibited increased inclination of flag leaves at the booting stage, resembling miR393-overexpressing plants. Moreover, yeast two-hybrid and bimolecular fluorescence complementation assays showed that OsTIR1 and OsAFB2 interact with OsIAA1. ? Expression diversification of miRNA393 implies the potential role of miRNA regulation during species evolution. The conserved mechanisms of the miR393/target module indicate the fundamental importance of the miR393-mediated regulation of auxin signal transduction in rice.     

Highly conserved low-copy nuclear genes as effective markers for phylogenetic analyses in angiosperms

? Organismal phylogeny provides a crucial evolutionary framework for many studies and the angiosperm phylogeny has been greatly improved recently, largely using organellar and rDNA genes. However, low-copy protein-coding nuclear genes have not been widely used on a large scale in spite of the advantages of their biparental inheritance and vast number of choices. ? Here, we identified 1083 highly conserved low-copy nuclear genes by genome comparison. Furthermore, we demonstrated the use of five nuclear genes in 91 angiosperms representing 46 orders (73% of orders) and three gymnosperms as outgroups for a highly resolved phylogeny. ? These nuclear genes are easy to clone and align, and more phylogenetically informative than widely used organellar genes. The angiosperm phylogeny reconstructed using these genes was largely congruent with previous ones mainly inferred from organellar genes. Intriguingly, several new placements were uncovered for some groups, including those among the rosids, the asterids, and between the eudicots and several basal angiosperm groups. ? These conserved universal nuclear genes have several inherent qualities enabling them to be good markers for reconstructing angiosperm phylogeny, even eukaryotic relationships, further providing new insights into the evolutionary history of angiosperms.