Cooperative adsorption of critical metal ions using archaeal poly-γ-glutamate

Antimony, beryllium, chromium, cobalt (Co), gallium (Ga), germanium, indium (In), lithium, niobium, tantalum, the platinoids, the rare-earth elements (including dysprosium, Dy), and tungsten are generally regarded to be critical (rare) metals, and the ions of some of these metals are stabilized in acidic solutions. We examined the adsorption capacities of three water-soluble functional polymers, namely archaeal poly-γ-glutamate (L-PGA), polyacrylate (PAC), and polyvinyl alcohol (PVA), for six valuable metal ions (Co²⁺, Ni²⁺, Mn²⁺, Ga³⁺, In³⁺, and Dy³⁺). All three polymers showed apparently little or no capacity for divalent cations, whereas L-PGA and PAC showed the potential to adsorb trivalent cations, implying the beneficial valence-dependent selectivity of anionic polyelectrolytes with multiple carboxylates for metal ions. PVA did not adsorb metal ions, indicating that the crucial role played by carboxyl groups in the adsorption of crucial metal ions cannot be replaced by hydroxyl groups under the conditions. In addition, equilibrium studies using the non-ideal competitive adsorption model indicated that the potential for L-PGA to be used for the removal (or collection) of water-soluble critical metal ions (e.g., Ga³⁺, In³⁺, and Dy³⁺) was far superior to that of any other industrially-versatile PAC materials.     

An HTRF based high-throughput screening for discovering chemical compounds that inhibit the interaction between Trypanosoma brucei Pex5p and Pex14p

The glycosome, a peroxisome-related organelle, is essential for the growth and survival of trypanosomatid protozoa. In glycosome biogenesis, Pex5p recognizes newly synthesized glycosomal matrix proteins via peroxisome-targeting signal type-1 (PTS-1) and transports them into glycosomes through an interaction with Pex14p, a component of the matrix protein import machinery on the glycosomal membrane. Knockdown of the PEX5 or PEX14 with RNAi has been shown to inhibit the growth of Trypanosoma brucei. Thus, compounds that inhibit the interaction of TbPex5p–TbPex14p are expected to become lead compounds in the development of anti-trypanosomal drugs. Here, we report a homogenous time-resolved fluorescence (HTRF) assay for the screening of compounds that inhibit the TbPex5p–TbPex14p interaction. The binding of GST-TbPex14p and TbPex5p-His with or without additional compounds was evaluated by measuring the energy transfer of the HTRF pair, using a terbium-labeled anti GST antibody as the donor and an FITC-labeled anti His antibody as the acceptor. The assay was performed in a 384-well plate platform and exhibits a Z’-factor of 0.85–0.91, while the coefficiency of variation is 1.1–7.7%, suggesting it can be readily adapted to a high-throughput format for the automated screening of chemical libraries. We screened 20,800 compounds and found 11 compounds that inhibited energy transfer. Among them, in a pull-down assay one compound exhibited selective inhibition of TbPex5p–TbPex14p without any HsPex5p–HsPex14p interaction.     

Importance of antecedent environmental conditions in modeling species distributions

Although species distributions can change in an unexpectedly short period of time, most species distribution models (SDMs) use only long‐term averaged environmental conditions to explain species distributions. We aimed to demonstrate the importance of incorporating antecedent environmental conditions into SDMs in comparison to long‐term averaged environmental conditions. We modeled the presence/absence of 18 fish species captured across 108 sampling events along a 50‐km length of the Sagami River in Japan throughout the 1990s (one to four times per site at 45 sites). We constructed and compared the two types of SDMs: 1) a conventional model that uses only long‐term averaged (10‐yr) environmental conditions; and 2) a proposed model that incorporates environmental conditions 2 yr prior to a sampling event (antecedent conditions) together with long‐term averages linked to life‐history stages. These models both included geomorphological, hydrological, and sampling conditions as predictors. A random forest algorithm was applied for modeling and quantifying the relative importance of the predictors. For seven species, antecedent hydrological conditions were more important than the long‐term averaged hydrological conditions. Furthermore, the distributions of two species with low prevalence could not be predicted using long‐term averaged hydrological conditions but only using antecedent hydrological conditions. In conclusion, incorporating antecedent environmental factors linked with life‐history stages at appropriate time scales can better explain changes in species distribution through time.     

Differences in the Composition of the Cell Walls of Two Morphologically Different Lines of Suspension-Cultured Catharanthus roseus Cells

Differences in the composition of cell walls of two morphologicallydifferent lines (A and B) of suspension-cultured Catharanthusroseus cells, which have the same origin, were investigated.The cells of strain A are nearly spherical, while those of strainB are cylindrical. In strain A, the amount of cell wall pergram fresh weight of cells increased during the logarithmicphase. In strain B, the amount of cell wall per cell decreasedduring the logarithmic phase. The level of matrix polysaccharides increased markedly duringthe logarithmic phase in strain A. The amount of cellulose incell wall was relatively larger in strain B than in strain A.The following differences in sugar composition between the twostrains were observed: (a) there was an increase in the relativelevels of 4-linked galactose in the EDTA-soluble fraction andof 3-linked glucose in the 5% KOH-soluble fraction during thelogarithmic phase in strain A; (b) there were significantlyhigher levels of arabinose, probably derived from 2,5- and/or3,5-linked arabinan, in the EDTA-soluble fraction and in theextracellular polysaccharides in strain B; (c) there were decreasesin the relative amounts of some kinds of sugar, probably thosederived from xyloglucan, during the stationary phase in strainB. (Received March 31, 1989; Accepted October 12, 1989)     

High resolution scanning electron-microscopic study on the three-dimensional structure of the sarcoplasmic reticulum in the slow (tonic) muscle fibers of the frog,Rana nigromaculata

Summary The three-dimensional structure of the sarcoplasmic reticulum (SR) in the slow (tonic) fibers of the reclus abdominis muscle of the Japanese meadow frog (Rana nigromaculata nigromaculata Hallowell) was examined by high resolution scanning electron microscopy, after removal of the cytoplasmic matrices by the osmium-DMSO-osmium procedure. The SR forms a repetitive network throughout these fibers. At the level of the Z-line, a slender transverse tubule (T-tubule) runs transversely to the longitudinal axis of the myofibril. Small, spherical or ovoid terminal cisternae couple laterally with the T-tubule at intervals of 0.4–1.0 m, and form a terminal cisterna-T-tubule complex on whose surface tiny indentations are occasionally seen. Each terminal cisterna gives rise to a few sarcotubules that run in various directions, divide frequently and form circular or oval meshes of diverse sizes in front of the A- and I-bands. The sarcotubules usually form small meshes in the middle of the A-band, but occasionally fuse and form a poorly developed H-band (fenestrated) collar.     

113Cd-NMR evidence for cooperative interaction between amino- and carboxyl-terminal domains of calmodulin

113Cd-NMR experiments were performed to characterize the nature of Cd2+ binding to calmodulin in the presence of a tetradecapeptide mastoparan or a 26-residue peptide M13 (calmodulin-binding region of skeletal muscle myosin light-chain kinase). The results indicate that binding of these peptides to calmodulin induces a positive cooperativity between Ca2+ binding to C- and N-terminal domains. The results imply that the activation of myosin light-chain kinase caused by the increase in Ca2+ concentration occurs as a result of cooperative interactions not only between two Ca2+ binding sites in each domain but also between the two domains. The interdomain interaction manifests itself only in the presence of such peptides.     

Measurement of human granulocyte-macrophage colony-stimulating factor (GM-CSF) by enzyme-linked immunosorbent assay

Summary An IgG monoclonal antibody against recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), designated HGMI, was produced by fusion of immune mouse splenocytes with HAT-sensitive murine myeloma cells. A sandwich enzyme-linked immunosorbent assay (ELISA) for measurement of human GM-CSF was developed using this HGMI and a polyclonal antibody against GM-CSF raised in a rabbit. GM-CSF in culture supernatants of phytohemagglutinin (PHA)- or concanavalin A (Con A)-stimulated peripheral blood mononuclear cells (PBMC) were measured by this ELISA system and the conventional CFU-GM colony formation method. The data indicated that the ELISA was highly efficient and sensitive for the detection of as little as 50 pg/ml recombinant GM-CSF. The CFU-GM colony assay may be influenced by other cytokines which can enhance or suppress colony formation, and ELISA for GM-CSF is more useful for kinetic studies of precise levels of production from PBMC.