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21.
Three B. subitilis serine tRNAs were sequenced including modified nucleosides. All the serine tRNAs contained 1-methyl-adenosine in the D-loop. As other characteristic modified nucleosides, 5-methoxyuridine was found in the first letter of the anticodon in the tRNA(UGA). 相似文献
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Streptomyces subtilisin inhibitor, a dimeric protein proteinase inhibitor isolated in crystalline form by Murae et al. in 1972, contains three tyrosine and one tryptophan residues per monomer unit and has unusual fluorescence properties. When excited at 280 nm, it shows a characteristic fluorescence spectrum having a peak at 307 nm and a shoulder near 340 nm, a feature which has been recognized only for a very few cases in proteins containing both tryosine and tryptophan residues. When excited at 295 nm, at which tryrosine scarcely absorbs, the inhibitor shows an emission spectrum with a peak at 340 nm characteristic of a tryptophan residue. The emission with a peak at 307 nm is considered to arise from the tryrosine residues. The tryptophan quantum yield of Streptomyces subtilisin inhibitor excited at 295 nm is very small, indicating that the tryptophan florescence is strongly quenched in the native state of the inhibitor. Below pH 4 the peak of the fluorescence spectrum of the inhibitor excited at 280 nm shifts toward 340-350 nm with a concomitant increase in the quantum yield. The structural change induced by low pH seems to release the tryptophan fluorescence from the quenching. 相似文献
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Abstract In order to determine whether non-elastase-producing strains of Pseudomonas aeruginosa such as N-10, PA103 and IFO3080 can express foreign elastase genes, we introduced elastase genes from P. aeruginosa IFO3455 (elastase-producing) as well as from PA103 and N-10 into non-elastase-producing P. aeruginosa strains. Results suggested that gene expression, secretion, and precursor processing systems of elastase were essentially normal in P. aeruginosa N-10 and IFO3080. Our studies using various elastase genes showed that both the elastase structural gene and 5'-upstream regions of P. aeruginosa PA103 were also normal. This was confirmed by the finding that P. aeruginosa N-10 and IFO3080 which carry the PA103 elastase gene produced elastase. Several deleted or chimeric genes were constructed using the 5'-upstream regions of elastase genes from P. aeruginosa N-10 or PA103 and studies of expression revealed that two individual DNA bases seem to be important in suppressing P. aeruginosa N-10 elastase gene expression. Possible reasons for the lack of elastase in these non-elastase-producing strains are discussed. 相似文献
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Spatial variation in phenology can occur at small spatial scales over which individuals can disperse or forage within one generation. Previous studies have assumed that variations in phenological peaks are caused by differences in abiotic environmental characteristics. However, environments should generally be similar among local habitats over small spatial scales. When the local population size is small, the phenological peak of the local population should be strongly affected by the variation in timing expressed by individuals. If a regional population consists of small local subpopulations (e.g., a metapopulation), the stochastic processes regulated by population sizes may explain the spatial variation in phenology. In this study, we quantitatively evaluated the extent of the spatial and annual variations in the breeding phenology of the forest green tree frog, Rhacophorus arboreus habiting a small area (<10 km2). The spatial variation in phenological peaks among 25 breeding sites was large over 6 years. This spatial variation was not explained by differences in air temperature or water depth. Randomization tests revealed that a large portion of the spatial variation could be explained by differences in population size, without considering site-specific factors. Annual variations in phenological peaks tended to be greater for smaller populations. These results imply that the stochastic process might have caused the spatial and annual variations in the phenological peaks of R. arboreus observed in the study region. Understanding spatiotemporal variation in phenology determined by stochastic process would be important to better predict interspecific interactions and (meta)population dynamics at small spatial scales. 相似文献
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Takuya Kobayashi Yamato Ishida Tomoaki Hirano Yohei Katoh Kazuhisa Nakayama 《Molecular biology of the cell》2021,32(1):45
Cilia sense and transduce extracellular signals via specific receptors. The intraflagellar transport (IFT) machinery mediates not only bidirectional protein trafficking within cilia but also the import/export of ciliary proteins across the ciliary gate. The IFT machinery is known to comprise two multisubunit complexes, namely, IFT-A and IFT-B; however, little is known about how the two complexes cooperate to mediate ciliary protein trafficking. We here show that IFT144–IFT122 from IFT-A and IFT88–IFT52 from IFT-B make major contributions to the interface between the two complexes. Exogenous expression of the IFT88(Δα) mutant, which has decreased binding to IFT-A, partially restores the ciliogenesis defect of IFT88-knockout (KO) cells. However, IFT88(Δα)-expressing IFT88-KO cells demonstrate a defect in IFT-A entry into cilia, aberrant accumulation of IFT-B proteins at the bulged ciliary tips, and impaired import of ciliary G protein–coupled receptors (GPCRs). Furthermore, overaccumulated IFT proteins at the bulged tips appeared to be released as extracellular vesicles. These phenotypes of IFT88(Δα)-expressing IFT88-KO cells resembled those of IFT144-KO cells. These observations together indicate that the IFT-A complex cooperates with the IFT-B complex to mediate the ciliary entry of GPCRs as well as retrograde trafficking of the IFT machinery from the ciliary tip. 相似文献
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Yoichi Toyama Seiya Yoshida Ryota Saito Hiroaki Kitamura Norimitsu Okui Ryo Miyake Ryusuke Ito Kyonsu Son Teruyuki Usuba Takuya Nojiri Katsuhiko Yanaga 《World journal of surgical oncology》2013,11(1):1-9