A novel technique for observing the internal ultrastructure of human chromosomes with known karyotype

Observation of the internal ultrastructure of human chromosomes by transmission electron microscopy (TEM) has frequently been attempted in spite of the difficulties in detaching metaphase chromosome spreads from the glass slide for further processing. In this study we have used a method in which metaphase chromosome spreads were prepared on a flexible thermoplastic membrane (ACLAR) film. To assess chromosome identity, a diamidino-phenylindole staining and karyotying was first done using a conventional cytogenetic system. The chromosome spreads were then fixed with 1% osmium tetroxide, stained with freshly prepared 2% tannic acid, dehydrated, and flat-embedded in epoxy resin. The resin sheet was easily detachable and carried whole chromosome spreads. By this method, TEM observation of chromosomes from normal human lymphocytes allowed a thorough examination of the ultrastructure of centromeres, telomeres, fragile sites, and other chromosomal regions. Various ultrastructural patterns including thick electron dense boundaries, less dense internal regions, and extended chromatin loops at the periphery of the chromosomes were discernible. Application of the present method to chromosome research is expected to provide comprehensive information on the internal ultrastructure of different chromosomal regions in relation to function.     

Ariakemicins A and B, novel polyketide-peptide antibiotics from a marine gliding bacterium of the genus Rapidithrix

Ariakemicins A (1) and B (2), unusual linear hybrid polyketide-nonribosomal peptide antibiotics, were discovered from the fermentation extract of the marine gliding bacterium Rapidithrix sp. These metabolites were positional isomers with regard to a double bond and chromatographically inseparable, rendering the structure study on a mixture basis. The ariakemicins were composed of threonine, two omega-amino-(omega-3)-methyl carboxylic acids with diene or triene units, and delta-isovanilloylbutyric acid. The antibiotics selectively inhibited the growth of Gram-positive bacteria.     

Environment‐Sensitive Fluorophores with Benzothiadiazole and Benzoselenadiazole Structures as Candidate Components of a Fluorescent Polymeric Thermometer

An environment‐sensitive fluorophore can change its maximum emission wavelength (λ_em), fluorescence quantum yield (Φ_f), and fluorescence lifetime in response to the surrounding environment. We have developed two new intramolecular charge‐transfer‐type environment‐sensitive fluorophores, DBThD‐IA and DBSeD‐IA, in which the oxygen atom of a well‐established 2,1,3‐benzoxadiazole environment‐sensitive fluorophore, DBD‐IA, has been replaced by a sulfur and selenium atom, respectively. DBThD‐IA is highly fluorescent in n‐hexane (Φ_f=0.81, λ_em=537 nm) with excitation at 449 nm, but is almost nonfluorescent in water (Φ_f=0.037, λ_em=616 nm), similarly to DBD‐IA (Φ_f=0.91, λ_em=520 nm in n‐hexane; Φ_f=0.027, λ_em=616 nm in water). A similar variation in fluorescence properties was also observed for DBSeD‐IA (Φ_f=0.24, λ_em=591 nm in n‐hexane; Φ_f=0.0046, λ_em=672 nm in water). An intensive study of the solvent effects on the fluorescence properties of these fluorophores revealed that both the polarity of the environment and hydrogen bonding with solvent molecules accelerate the nonradiative relaxation of the excited fluorophores. Time‐resolved optoacoustic and phosphorescence measurements clarified that both intersystem crossing and internal conversion are involved in the nonradiative relaxation processes of DBThD‐IA and DBSeD‐IA. In addition, DBThD‐IA exhibits a 10‐fold higher photostability in aqueous solution than the original fluorophore DBD‐IA, which allowed us to create a new robust molecular nanogel thermometer for intracellular thermometry.     

Novel Orange Color Pigments Based on La3LiMnO7

La₃LiMn_1−xTi_xO₇ (0 ≤ x ≤ 0.05) samples were synthesized by a solid-state reaction method, and a single-phase form was observed for the samples in the range of x ≤ 0.03. Crystal structure, optical properties, and color of the La₃LiMn_1−xTi_xO₇ (0 ≤ x ≤ 0.03) samples were characterized. Strong optical absorption was observed at a wavelength between 400 and 550 nm, and a shoulder absorption peak also appeared around 690 nm in all samples; orange colors were also exhibited. Among the samples synthesized, the most brilliant orange color was obtained at La₃LiMn_0.97Ti_0.03O₇. The redness (a*) and yellowness (b*) values of this pigment were higher than those of the commercially available orange pigments. Therefore, the orange color of this pigment is brighter than those of the commercial products. Since the La₃LiMn_0.97Ti_0.03O pigment is composed of non-toxic elements, it could be a new environmentally friendly inorganic orange pigment.     

Preparation and release characteristics of cisplatin albumin microspheres containing chitin and treated with chitosan

Cisplatin (CDDP) containing albumin microspheres and microcapsules incorporating biodegradable macromolecules, chitin and chitosan, were prepared, and their CDDP content and releasing ability and susceptibility to various enzymes were examined. Chitin was incorporated during preparation of the microspheres, while chitosan was used to treat preformed microspheres. CDDP content was remarkably increased by chitin; when chitin was incorporated at a concentration of 1.5%, the CDDP content of the microspheres was found to be 16.2% (1.8 times that with no addition of chitin). CDDP release was suppressed by chitin and chitosan. The 50% CDDP release time was about 1.5 h when no chitin was added, but about 16 h was required when chitin was incorporated into the microspheres at a concentration of 1.5%. Chitin and chitosan suppressed the decomposition by protease. The microspheres treated with 70% deacetylated chitosan showed the greatest susceptibility to lysozyme. In conclusion, CDDP release can be controlled by the use of chitin or chitosan, and the microspheres should show no immunogenicity in vivo because of their susceptibility to lysozyme.     

Stark beats of Lyman-α emission of foil-excited hydrogen atom

The Stark beats of Lyman-α emission due ton=1 ? 2 transition of hydrogen atom have been studied by the beam-foil method. After passage through a thin carbon foil, the static electric field of 500 V/cm was applied to the beam in the direction either parallel to or anti-parallel to the the beam velocity. The linearly polarized emission was measured by using a toroidal mirror at a Brewster's angle reflection. When the direction of the applied electric field is reversed, an appreciable phase shift was observed. The analysis of the data leads to the complete determination of the density matrix of the H(n=2) atoms at the time of their production.     

Stepwise Reduction of Azapentabenzocorannulene

Mono‐ and dianions of 2‐tert‐butyl‐3a²‐azapentabenzo[bc,ef,hi,kl,no]corannulene ( 1 a ) were synthesized by chemical reduction with sodium and cesium metals, and crystallized as the corresponding salts in the presence of 18‐crown‐6 ether. X‐ray diffraction analysis of the sodium salt, [{Na⁺(18‐crown‐6)(THF)₂}₃{Na⁺(18‐crown‐6)(THF)}( 1 a ^2?)₂], revealed the presence of a naked dianion. In contrast, controlled reaction of 1 a with Cs allowed the isolation of singly and doubly reduced forms of 1 a , both forming π‐complexes with cesium ions in the solid state. In [{Cs⁺(18‐crown‐6)}( 1 a ^?)]?THF, asymmetric binding of the Cs⁺ ion to the concave surface of 1 a ^? is observed, whereas in [{Cs⁺(18‐crown‐6)}₂( 1 a ^2?)], two Cs⁺ ions bind to both the concave and convex surfaces of the dianion. The present study provides the first successful isolation and characterization of the reduced products of heteroatom‐containing buckybowl molecules.     

Dynamic analysis of aggregation of methylene blue with polarized optical waveguide spectroscopy

Polarized optical waveguide (POW) spectroscopy permits analysis of the changing molecular state of methylene blue (MB), including aggregate order and orientation at the waveguide surface. Monomer or dimer, dissolved randomly in MB aqueous solution, tends to aggregate at the waveguide surface during air drying. Furthermore, POW spectroscopy dynamically revealed that MB molecules became oriented vertically to the waveguide surface with increasing aggregation order.     

High sequence-coverage detection of proteolytic peptides using a bis(terpyridine)ruthenium(II) complex

The use of a bis(terpyridine)ruthenium(ii) complex for peptide labeling (Ru-CO labeling) supplied high intensity peaks in mass spectrometry (MS) analysis that overcame the contribution of protonation or sodiated adduction to peptides. Ru-CO-labeled insulin A- and B-chains were detected simultaneously in comparable peak abundance by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The mass spectra of chymotryptic peptide fragments of Ru-CO-labeled insulin also simultaneously indicated both N-terminal fragment ions, and amino acid sequences were determined easily by matrix-assisted laser desorption/ionization post-source-decay (MALDI-PSD). The sensitivity of detecting Ru-CO-labeled peptide fragment ions was not dependent on the length or the sequences of the peptides. The Ru-CO labeling method was applied to tryptic myoglobin fragments. The method indicated that each fragment ion is detected nearly equal in abundance and enabled the desired fragment ions to be distinguished from matrix clusters or their in-source fragments in lower mass regions. The desired fragment ions can be found in the mass region higher than 670.70 (= Ru-CO). This method provided a high sequence coverage (96%) by peptide mass fingerprinting (PMF). Application of this method to a protein mixture (myoglobin, lysozyme and ubiquitin) successfully achieved high sequence-coverage characterization (>90%) of these proteins simultaneously.