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81.
The rate of actin polymerization gradually decreased without changing the final level of polymerization, when incubated in the presence of 0.2 mM ATP at pH 8.0 and 25 degrees C. This change was much faster in Mg2+-actin than Ca2+-actin, and Mg2+-actin became denatured and unpolymerizable on prolonged incubation. The drop in the polymerization rate was due both to weakened nucleation and a slowed elongation rate in the incubated actin. The change in the polymerization rate was partially reversible by storing the sample at 0 degrees C. When the rate of polymerization dropped markedly on prolonged incubation, a gel filtration profile showed that Ca2+-actin existed as monomer not as oligomer. On the other hand, Mg2+-actin formed dimers, and other oligomers, as revealed by crosslinking analysis. There were changes in fluorescence intensities due to tyrosine and/or tryptophan residues of the actin molecule, and in difference absorption spectra, suggesting that conformational changes intermediate between native and denatured states occurred during incubation. 相似文献
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83.
A new regulatory protein which we have designated as gamma-actinin has been isolated from native thin filaments of rabbit skeletal muscle. Depolymerized native thin filaments were fractionated by salting out with ammonium sulfate, and the precipitates obtained at 40--60% ammonium sulfate saturation were further subjected to DEAE-Sephadex and Sephadex G-200 column chromatography. The purified gamma-actinin was shown to have a chain weight of 35,000 daltons and had a strong inhibitory action on the polymerization of G-actin. The results of amino acid analysis indicated a unique amino acid composition of gamma-actinin as compared with other structural proteins of muscle. Non-polar and neutral amino acid residues were abundant. One cysteine residue was contained per one molecule of gamma-actinin and played a critical role in the maintenance of the inhibitory activity. Pelleting of gamma-actinin with F-actin showed that gamma-actinin binds to F-action. 相似文献
84.
The polymerization process of actin was examined by measuring the amount of flow birefringence and by analyzing release of labeled inorganic phosphate from the bound [gamma-32P]ATP upon polymerization of G-actin to F-actin. Comparison of the above experimental results with the electron microscopic data of Kawamura and Maruyama (J. Biochem., 67, 437-457, 1970) suggested that growth and redistribution steps occurred simultaneously during polymerization. Attempt was made to simulate the polymerization process of actin by calculating the kinetic equations numerically. The results of simulation suggested that it was necessary to take into consideration the association and dissociation between F-actin particles as well as the association and dissociation between F-actin and G-actin. 相似文献
85.
86.
Akari Nishigaki Mihoko Maruyama Munenori Numata Chisako Kanzaki Shun‐Ichi Tanaka Hiroshi Y. Yoshikawa Masayuki Imanishi Masashi Yoshimura Yusuke Mori Kazufumi Takano 《Engineering in Life Science》2020,20(9-10):395-401
It is known that interfaces have various impacts on crystallization from a solution. Here, we describe crystallization of acetaminophen using a microflow channel, in which two liquids meet and form a liquid–liquid interface due to laminar flow, resulting in uniform mixing of solvents on the molecular scale. In the anti‐solvent method, the microflow mixing promoted the crystallization more than bulk mixing. Furthermore, increased flow rate encouraged crystal formation, and a metastable form appeared under a certain flow condition. This means that interface management by the microchannel could be a beneficial tool for crystallization and polymorph control. 相似文献
87.
88.
Kensaku Maejima Masayoshi Hashimoto Yuka Hagiwara-Komoda Akio Miyazaki Masanobu Nishikawa Ryosuke Tokuda Kohei Kumita Noriko Maruyama Shigetou Namba Yasuyuki Yamaji 《Molecular Plant Pathology》2020,21(4):475-488
Plum pox virus (PPV) is one of the most important plant viruses causing serious economic losses. Thus far, strain typing based on the definition of 10 monophyletic strains with partially differentiable biological properties has been the sole approach used for epidemiological characterization of PPV. However, elucidating the genetic determinants underlying intra-strain biological variation among populations or isolates remains a relevant but unexamined aspect of the epidemiology of the virus. In this study, based on complete nucleotide sequence information of 210 Japanese and 47 non-Japanese isolates of the PPV-Dideron (D) strain, we identified five positively selected sites in the PPV-D genome. Among them, molecular studies showed that amino acid substitutions at position 2,635 in viral replicase correlate with viral titre and competitiveness at the systemic level, suggesting that amino acid position 2,635 is involved in aphid transmission efficiency and symptom severity. Estimation of ancestral genome sequences indicated that substitutions at amino acid position 2,635 were reversible and peculiar to one of two genetically distinct PPV-D populations in Japan. The reversible amino acid evolution probably contributes to the dissemination of the virus population. This study provides the first genomic insight into the evolutionary epidemiology of PPV based on intra-strain biological variation ascribed to positive selection. 相似文献
89.
Satsuki Tsuji Atsushi Maruyama Masaki Miya Masayuki Ushio Hirotoshi Sato Toshifumi Minamoto Hiroki Yamanaka 《Molecular ecology resources》2020,20(5):1248-1258
Environmental DNA (eDNA) analysis has recently been used as a new tool for estimating intraspecific diversity. However, whether known haplotypes contained in a sample can be detected correctly using eDNA‐based methods has been examined only by an aquarium experiment. Here, we tested whether the haplotypes of Ayu fish (Plecoglossus altivelis altivelis) detected in a capture survey could also be detected from an eDNA sample derived from the field that contained various haplotypes with low concentrations and foreign substances. A water sample and Ayu specimens collected from a river on the same day were analysed by eDNA analysis and Sanger sequencing, respectively. The 10 L water sample was divided into 20 filters for each of which 15 PCR replications were performed. After high‐throughput sequencing, denoising was performed using two of the most widely used denoising packages, unoise3 and dada2 . Of the 42 haplotypes obtained from the Sanger sequencing of 96 specimens, 38 (unoise3 ) and 41 (dada2 ) haplotypes were detected by eDNA analysis. When dada2 was used, except for one haplotype, haplotypes owned by at least two specimens were detected from all the filter replications. Accordingly, although it is important to note that eDNA‐based method has some limitations and some risk of false positive and false negative, this study showed that the eDNA analysis for evaluating intraspecific genetic diversity provides comparable results for large‐scale capture‐based conventional methods. Our results suggest that eDNA‐based methods could become a more efficient survey method for investigating intraspecific genetic diversity in the field. 相似文献