Highly sensitive and simple fluorescence staining of proteins in sodium dodecyl sulfate-polyacrylamide-based gels by using hydrophobic tail-mediated enhancement of fluorescein luminescence

Fluorescein has an extremely low luminescence intensity in acidic aqueous media. However, when it was bound to proteins, subsequent increase of luminescence intensity took place. Furthermore, when a hydrophobic tail, such as aliphatic hydrocarbons, was introduced to fluorescein, more dramatic increase of luminescence intensity was observed upon binding to proteins. In the present study, by utilizing this luminescence enhancement, three hydrophobic fluorescein dyes (5-dodecanoyl amino fluorescein, 5-hexadecanoyl amino fluorescein, and 5-octadecanoyl amino fluorescein) were examined as noncovalent fluorescent stains of protein bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Effective incorporation of the dyes to proteins in gels was accomplished either simply by adding dyes at the protein fixation step, or by treating gels with a staining solution after the fixation. The sensitivity of this staining method using the fluorescein derivatives was approximately 1 ng/band for most proteins. For some cases, protein bands containing as low as 0.1 ng were successfully visualized. In addition, the detection sensitivity showed much less protein-to-protein variation than silver staining. This new staining method was also successfully applied to two-dimensional electrophoresis of rat brain proteins. Its overall sensitivity was comparable to that of silver staining.     

Calix[4]crown in dual sensing functions with FRET

A new calix[4]crown chemosensor based on dual sensing probes reveals Pb²⁺ ion selectivity over other metal ions, which arises from a hypsochromic shift of azo units in UV spectrum as well as a fluorescence enhancement of pyrenyl parts in fluorescence spectrum via a suppressed FRET.     

Synthesis and biological evaluation of 5′-O-dicarboxylic fatty acyl monoester derivatives of anti-HIV nucleoside reverse transcriptase inhibitors

A number of 5′-O-dicarboxylic fatty acyl monoester derivatives of 3′-azido-3′-deoxythymidine (zidovudine, AZT), 2′,3′-didehydro-2′,3′-dideoxythymidine (stavudine, d4T), and 3′-fluoro-3′-deoxythymidine (alovudine, FLT) were synthesized to improve the lipophilicity and potentially the cellular delivery of parent polar 2′,3′-dideoxynucleoside (ddN) analogs. The compounds were evaluated for their anti-HIV activity. Three different fatty acids with varying chain length of suberic acid (octanedioic acid), sebacic acid (decanedioic acid), and dodecanedioic acid were used for the conjugation with the nucleosides. The compounds were evaluated for anti-HIV activity and cytotoxicity. All dicarboxylic ester conjugates of nucleosides exhibited significantly higher anti-HIV activity than that of the corresponding parent nucleoside analogs. Among all the tested conjugates, 5′-O-suberate derivative of AZT (EC₅₀ = 0.10 nM) was found to be the most potent compound and showed 80-fold higher anti-HIV activity than AZT without any significant toxicity (TC₅₀ >500 nM).     

Profiling of phospholipids in lipoproteins by multiplexed hollow fiber flow field-flow fractionation and nanoflow liquid chromatography–tandem mass spectrometry

This study describes a coupled analytical method to carry out the systematic profiling of phospholipids (PLs) in high-density lipoproteins (HDL) and low-density lipoproteins (LDL) from human blood plasma. HDL and LDL of healthy human plasma samples were separated by size and collected on a semi-preparative scale using multiplexed hollow fiber flow field-flow fractionation (MxHF5). Phospholipid mixtures contained in the resulting HDL and LDL fractions were analyzed by shotgun nanoflow liquid chromatography–tandem mass spectrometry (nLC–ESI-MS–MS). We utilized a dual scan method for the separation and simultaneous characterization of complicated PL mixtures by nLC–ESI-MS–MS, such that phosphatidylcholine (PC) and phosphatidylethanolamine (PE) molecules were detected in positive ion mode in a first LC run. In a second LC run, phosphatidylinositol (PI), phosphatidylglycerol (PG), and phosphatidic acid (PA) were detected in negative ion mode. In this study, a total of 56 PLs from HDL and 52 PLs from LDL particles were characterized by their molecular structures from data dependent collision-induced dissociation (CID) experiments, and their relative abundances were compared.     

Erratum to “Lower bounds for the eigenvalues of the basic Dirac operator on a Riemannian foliation” [J. Geom. Phys. 51 (2004) 166–182]

We correct some statements in the paper mentioned in the title.     

A radiofrequency plasma in a polydimethylsiloxane (PDMS) microchip

This is the first report of an analytical plasma in a polymer (polydimethylsiloxane, PDMS) microchip. The plasma channel has dimensions 2 mm diameter × 50 mm long, is operated at atmospheric pressure in Ar, 27.12 MHz and 70 W, and is viewed axially through a purged fiber optic cable. CF₄ gas at 0.1% in argon yields mainly C₂ emission bands. This PDMS microchip is manufactured easily, inexpensive, and more tolerant to fluorocarbons than microchip plasmas in silica. Based on these initial results, this PDMS microchip plasma could become useful as a sensor for the fluorocarbon gases emitted in semiconductor process or as a gas chromatography (GC) detector for potential application.     

Pressure- and heat-induced insertion of CO2 into an auxetic small-pore zeolite

When the small-pore zeolite natrolite is compressed at ca. 1.5 GPa and heated to ca. 110 °C in the presence of CO(2), the unit cell volume of natrolite expands by 6.8% and ca. 12 wt % of CO(2) is contained in the expanded elliptical channels. This CO(2) insertion into natrolite is found to be reversible upon pressure release.     

Matrix-assisted laser desorption/ionization-mass spectrometry of cuticular lipid profiles can differentiate sex, age, and mating status of Anopheles gambiae mosquitoes

Malaria is a devastating mosquito-borne disease, which affects hundreds of millions of people each year. It is transmitted predominantly by Anopheles gambiae, whose females must be >10 days old to become infective. In this study, cuticular lipids from a laboratory strain of this mosquito species were analyzed using a mass spectrometry method to evaluate their utility for age, sex and mating status differentiation. Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS), in conjunction with an acenaphthene/silver nitrate matrix preparation, was shown to be 100% effective in classifying A. gambiae females into 1, 7–10, and 14 days of age. MALDI-MS analysis, supported by multivariate statistical methods, was also effective in detecting cuticular lipid differences between the sexes and between virgin and mated females. The technique requires further testing, but the obtained results suggest that MALDI-MS cuticular lipid spectra could be used for age grading of A. gambiae females with precision greater than with other available methods.     

A new look at the moduli space of stable hyperelliptic curves

We carry out the log minimal model program for the moduli space ${\bar H_g}We carry out the log minimal model program for the moduli space [`(H)]<sub>g</sub>{\bar H_g} of stable hyperelliptic curves and show that certain log canonical models of [`(H)]_g{\bar H_g} are isomorphic to the proper transform of [`(H)]<sub>g</sub>{\bar H_g} in the corresponding log canonical models of [`(M)]_g{\bar M_g}. For g = 3, we retrieve the compact moduli space [`(B)]<sub>8</sub>{\bar B_{8}} of binary forms as a log canonical model, and obtain a decomposition of the natural map [`(H)]₃ ? [`(B)]<sub>8</sub>{\bar H_3 \to \bar B_{8}} into successive divisorial contractions of the boundary divisors. As a byproduct, we also obtain an isomorphism of [`(B)]₈{\bar B_8} with the GIT quotient of the Chow variety of bicanonically embedded hyperelliptic curves of genus three.     

Diastereoselective diaza-Cope rearrangement reaction

Steric effect is used to obtain a highly diastereoselective rearrangement reaction.