Isolation,Structure and Physiological Activities of Piericidin B,Natural Insecticide Produced by a Streptomyces

Piericidin B was isolated from mycellia of Streptomyces mobaraensis besides piericidin A. On the basis of IR, NMR and mass spectral studies together with chemical evidences, its structure was assigned as Id. Its physiological activities are also deescribd.     

Isolation and Structure Elucidation of Three New Insecticidal Cyclodepsipeptides,Destruxins C and D and Desmethyldestruxin B,Produced by Metarrhizium anisopliae

A multi-channel continuous-flow analyzer equipped with biosensing devices was developed for multi-component measurement and its use in automating routine analysis was evaluated.

Biosensing was achieved by the aid of an immobilized enzyme reactor installed in the channel, and the channel switching process for the sensing of a different compound was made by using a column-switching rotary valve. Another rotary valve was used for auto-sampling. Both of the two rotary valves were interfaced to a system controller and work conjugatively in a programmed manner. Signal subtraction between different channels was found to be more precise compared with the multi-channel flow-injection analysis method, which is of merit for an analysis utilizing enzyme relay reaction (as for sucrose analysis) or for background signal subtraction. Glucose, lactate, and sucrose content in real samples were measured automatically with high reproducibility, and the results agree well with the kit method.     

Chemical Structure of Piericidin A

Molecular formula C₂₅H_37–39NO₄ was assigned to Piericidin A. Through the examination of the ultraviolet, infrared and n.m.r. spectra and of chemical evidences, it was shown that Piericidin A contains one secondary alcohol, one acidic hydroxyl group, two methoxyl groups, tri- and tetra-substituted conjugated dienes and one polysubstituted heteroaromatic ring.     

Relationship Between Amino Acid Properties and Protein Stability: Buried Mutations

In order to understand the mechanism of protein stability and to develop a simple method for predicting mutation-induced stability changes, we analyzed the relationship between stability changes caused by buried mutations and changes in 48 amino acid properties. As expected from the importance of hydrophobicity, properties reflecting hydrophobicity are strongly correlated with the stability of proteins. We found that subgroup classification based on secondary structure increased correlations significantly, and mutations within -strand segments correlated better than did those in -helical segments, which may result from stronger hydrophobicity of the -strands. Multiple regression analyses incorporating combinations of three properties from among all possible combinations of the 48 properties increased the correlation coefficient to 0.88 and by an average of 13% for all data sets. Analyzing the stability of tryptophan synthase mutants with Glu49 replaced by all other residues except Arg revealed that combining buriedness, solvent-accessible surface area for denatured protein, and unfolding Gibbs free energy change increased the correlation to 0.95. Consideration of sequence and structural information (neighboring residues in sequence and in space) did not significantly strengthen the correlations in buried mutations, suggesting that nonspecific interactions dominate in the interior of proteins.     

Extensive and prolonged restoration of dystrophin expression with vivo-morpholino-mediated multiple exon skipping in dystrophic dogs

Duchenne muscular dystrophy (DMD) is a severe and the most prevalent form of muscular dystrophy, characterized by rapid progression of muscle degeneration. Antisense-mediated exon skipping is currently one of the most promising therapeutic options for DMD. However, unmodified antisense oligos such as morpholinos require frequent (weekly or bi-weekly) injections. Recently, new generation morpholinos such as vivo-morpholinos are reported to lead to extensive and prolonged dystrophin expression in the dystrophic mdx mouse, an animal model of DMD. The vivo-morpholino contains a cell-penetrating moiety, octa-guanidine dendrimer. Here, we sought to test the efficacy of multiple exon skipping of exons 6-8 with vivo-morpholinos in the canine X-linked muscular dystrophy, which harbors a splice site mutation at the boundary of intron 6 and exon 7. We designed and optimized novel antisense cocktail sequences and combinations for exon 8 skipping and demonstrated effective exon skipping in dystrophic dogs in vivo. Intramuscular injections with newly designed cocktail oligos led to high levels of dystrophin expression, with some samples similar to wild-type levels. This is the first report of successful rescue of dystrophin expression with morpholino conjugates in dystrophic dogs. Our results show the potential of phosphorodiamidate morpholino oligomer conjugates as therapeutic agents for DMD.     

CENP-B interacts with CENP-C domains containing Mif2 regions responsible for centromere localization

Recently, human artificial chromosomes featuring functional centromeres have been generated efficiently from naked synthetic alphoid DNA containing CENP-B boxes as a de novo mechanism in a human cultured cell line, but not from the synthetic alphoid DNA only containing mutations within CENP-B boxes, indicating that CENP-B has some functions in assembling centromere/kinetochore components on alphoid DNA. To investigate whether any interactions exist between CENP-B and the other centromere proteins, we screened a cDNA library by yeast two-hybrid analysis. An interaction between CENP-B and CENP-C was detected, and the CENP-C domains required were determined to overlap with three Mif2 homologous regions, which were also revealed to be involved in the CENP-C assembly of centromeres by expression of truncated polypeptides in cultured cells. Overproduction of truncated CENP-B containing no CENP-C interaction domains caused abnormal duplication of CENP-C domains at G2 and cell cycle delay at metaphase. These results suggest that the interaction between CENP-B and CENP-C may be involved in the correct assembly of CENP-C on alphoid DNA. In other words, a possible molecular linkage may exist between one of the kinetochore components and human centromere DNA through CENP-B/CENP-B box interaction.