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101.
Hydrocarbon composition of newly isolated strains of the green microalga Botryococcus braunii 总被引:1,自引:0,他引:1
Four new strains of Botryococcus braunii were isolated from Japanese waters and cultured under defined conditions. Their hydrocarbon content and composition were analyzed and compared with those of the Darwin and Berkeley strains. The Yamanaka strain produced only alkadienes characteristic of the A race, whereas the others, the Yayoi, Kawaguchi-1 and -2 strains as well as the Darwin and Berkeley strains, produced botryococcenes peculiar to the B race. The hydrocarbon content of the Yamanaka strain was 16.1 % dry weight and that of the B race strains ranged from 9.7 to 37.9%. Botryococcene composition of the Japanese strains differed from each other as well as from the Darwin and Berkeley strains. More than 50% of the hydrocarbons in the Yayoi, Darwin, and Berkeley strains were composed of C34H58, but the main components were different from one another as isomers. The Kawaguchi-1 and -2 strains did not have a high level of C34 botryococcenes, C32 ones being the main components. In these strains significant amounts of squalene-related compounds were detected. 相似文献
102.
103.
Methionine aminopeptidase, known to be encoded by single genes in prokaryotes, is a cobalt-dependent enzyme that catalyzes the removal of N-terminal methionine residues from nascent polypeptides. Three ORFs encoding putative methionine aminopeptidases from the genome of cyanobacterium Synechocystis sp. strain PCC6803, designated as slr0786 (map-1), slr0918 (map-2) and sll0555 (map-3) were cloned and expressed in Escherichia coli. The purified recombinant proteins encoded by map-1 and map-3 had much higher methionine aminopeptidase activity than the recombinant protein encoded by map-2. Comparative analysis revealed that the three recombinant enzymes differed in their substrate specificity, divalent ion requirement, pH, and temperature optima. The broad activities of the iso-enzymes are discussed in light of the structural similarities with other peptidase families and their levels of specificity in the cell. Potential application of cyanobacterial MetAPs in the production of recombinant proteins used in medicine is proposed. This is the first report of a prokaryote harboring multiple methionine aminopeptidases.Abbreviations map Gene encoding methionine aminopeptidase - MetAP Methionine aminopeptidase - eMetAP-Ia Escherichia coli methionine aminopeptidase type Ia - yMetAP-Ib Yeast methionine aminopeptidase type Ib - yMetAP-IIa Yeast methionine aminopeptidase type IIa - hMetAP-IIb Human methionine aminopeptidase type IIb - pfMetAP–IIa Pyrococcus furiosis methionine aminopeptidase type Ia - bst MetAP-Ia Bacillus stearothermophilus methionine aminopeptidase type Ia - c1MetAP-Ia Cyanobacterial methionine aminopeptidase type Ia encoded by map-1 - c2MetAP-Ia Cyanobacterial methionine aminopeptidase type Ia encoded by map-2 - c3MetAP-Ib Cyanobacterial methionine aminopeptidase type Ib, ncoded by map-3 相似文献
104.
Tsutomu Enoki Tohru Nakashizuka Shin-ichi Nakano Takeshi Miki Yu-Pin Lin Masahiro Nakaoka Eri Mizumachi Hideaki Shibata 《Ecological Research》2014,29(3):357-368
The primary goal of the 60th anniversary symposium of the Ecological Society of Japan (ESJ) was to re-examine the role of the Society. The first of five lectures, “Development of Long-term Ecological Research in Japan,” discussed the increasingly important role of long-term and networked research studies. Ecological research in Asia faces many challenges, because Asia features natural and anthropogenic landscapes with highly diverse ecosystems. “Developing Strategies of the Ecological Society of Japan for Worldwide Societies of Ecology with Special Reference to Strategies for Asia” emphasized the role of ESJ in promoting ecological research and outreach in Asia. Ecosystem sustainability is a key issue in both the theory and practice of ecosystem management. A framework concept of an environmental and biodiversity cycle was proposed in the session “Linking Community and Ecosystem Dynamics” for understanding the mechanisms driving the sustainability of ecosystems. Ecosystem services are essential aspects of land use and conservation planning and management. “Integrating Models of Ecosystem Services and Land Use Changes” reviewed recently-developed models that simulate patterns of land-use change and analyze its effects on ecosystem services and also recommended future directions for collaboration among researchers. “Disaster Resilience and Coastal Ecology” highlighted the contributions of ecologists to evaluating the resilience of damaged coastal ecosystems and provided sound proposals to local communities and governments for rehabilitation plans. The past achievements and future directions of ESJ were discussed by the panelists and the audience in “Past and Future of the Ecological Society of Japan.” 相似文献
105.
Mitsue Shibata Satoshi Kikuchi Hiroshi Tanaka Masahiro Sueyoshi Hiroshi Yoshimaru Kaoru Niiyama 《Ecological Research》2009,24(1):1-9
The effects of local population density, sex morph [protogynous (PG) or protandrous (PA)], and individual tree size on the
demographic processes of seed production were investigated in a heterodichogamous maple, Acer mono Maxim. var. Marmoratum (Nichols.) Hara f. dissectum, in a temperate forest of Japan. As the distance from conspecific reproductive adults increased, the percentage of immature
seed fall and empty seeds increased significantly, indicating higher pollination success along with local population density.
Although the difference was not distinct, pollination success was affected by the local population density of the reciprocal
sex morph rather than that of both sex morphs. The trees at higher local population density sites suffered higher seed mortality
due to predation and decay, and tended to produce smaller seeds. Thus, the impacts of local population density operated both
positively and negatively on reproduction. As a factor of individual traits, tree size scarcely affected any demographic processes.
On the other hand, sex morph did affect pollination success. Trees of PG type had lower immature seed fall than those of PA
type, suggesting that the former has higher efficiency of pollen acceptance than the latter. The results on seed demography
presented here partly support previous suggestions that heterodichogamous plants exhibit reciprocal cross-pollination and
gender specialization as reproductive traits. 相似文献
106.
Cooperation between the chloroplast psbA 5′‐untranslated region and coding region is important for translational initiation: the chloroplast translation machinery cannot read a human viral gene coding region 下载免费PDF全文
Masayuki Nakamura Yurina Hibi Takashi Okamoto Masahiro Sugiura 《The Plant journal : for cell and molecular biology》2016,85(6):772-780
Chloroplast mRNA translation is regulated by the 5′‐untranslated region (5′‐UTR). Chloroplast 5′‐UTRs also support translation of the coding regions of heterologous genes. Using an in vitro translation system from tobacco chloroplasts, we detected no translation from a human immunodeficiency virus tat coding region fused directly to the tobacco chloroplast psbA 5′‐UTR. This lack of apparent translation could have been due to rapid degradation of mRNA templates or synthesized protein products. Replacing the psbA 5′‐UTR with the E. coli phage T7 gene 10 5′‐UTR, a highly active 5′‐UTR, and substituting synonymous codons led to some translation of the tat coding region. The Tat protein thus synthesized was stable during translation reactions. No significant degradation of the added tat mRNAs was observed after translation reactions. These results excluded the above two possibilities and confirmed that the tat coding region prevented its own translation. The tat coding region was then fused to the psbA 5′‐UTR with a cognate 5′‐coding segment. Significant translation was detected from the tat coding region when fused after 10 or more codons. That is, translation could be initiated from the tat coding region once translation had started, indicating that the tat coding region inhibits translational initiation but not elongation. Hence, cooperation/compatibility between the 5′‐UTR and its coding region is important for translational initiation. 相似文献
107.
Akinobu Echigo Miki Hino Tadamasa Fukushima Toru Mizuki Masahiro Kamekura Ron Usami 《Aquatic biosystems》2005,1(1):1-13
Background
Natural microbial communities are extremely complex and dynamic systems in terms of their population structure and functions. However, little is known about the in situ functions of the microbial communities.Results
This study describes the application of proteomic approaches (metaproteomics) to observe expressed protein profiles of natural microbial communities (metaproteomes). The technique was validated using a constructed community and subsequently used to analyze Chesapeake Bay microbial community (0.2 to 3.0 μm) metaproteomes. Chesapeake Bay metaproteomes contained proteins from pI 4–8 with apparent molecular masses between 10–80 kDa. Replicated middle Bay metaproteomes shared ~92% of all detected spots, but only shared 30% and 70% of common protein spots with upper and lower Bay metaproteomes. MALDI-TOF analysis of highly expressed proteins produced no significant matches to known proteins. Three Chesapeake Bay proteins were tentatively identified by LC-MS/MS sequencing coupled with MS-BLAST searching. The proteins identified were of marine microbial origin and correlated with abundant Chesapeake Bay microbial lineages, Bacteroides and α-proteobacteria.Conclusion
Our results represent the first metaproteomic study of aquatic microbial assemblages and demonstrate the potential of metaproteomic approaches to link metagenomic data, taxonomic diversity, functional diversity and biological processes in natural environments. 相似文献108.
Solvent polarity effects on supramolecular chirality of a polyfluorene‐thiophene copolymer 下载免费PDF全文
Takashi Hirahara Masahiro Yoshizawa‐Fujita Yuko Takeoka Masahiro Rikukawa 《Chirality》2018,30(6):699-707
This study demonstrates the supramolecular chirality control of a conjugated polymer via solvent polarity. We designed and synthesized a chiral polyfluorene‐thiophene copolymer having two different chiral side chains at the 9‐position of the fluorene unit. Chiral cyclic and alkyl ethers with different polarities were selected as the chiral side chains. The sign of the circular dichroism spectra in the visible wavelength region was affected by the solvent system, resulting from the change of supramolecular structure. The estimation of the solubility parameter revealed that the solubility difference of the side chains contributed to the change of the circular dichroism sign, which was also observed in spin‐coated films prepared from good solvents having different polarities. 相似文献
109.
110.
Induction of Bcl-xL Expression by Human T-Cell Leukemia Virus Type 1 Tax through NF-κB in Apoptosis-Resistant T-Cell Transfectants with Tax 下载免费PDF全文
Tomonori Tsukahara Mari Kannagi Takashi Ohashi Hirotomo Kato Masaaki Arai Gabriel Nunez Youichi Iwanaga Naoki Yamamoto Kiyoshi Ohtani Masataka Nakamura Masahiro Fujii 《Journal of virology》1999,73(10):7981-7987
Human T-cell leukemia virus type 1 (HTLV-1) Tax is thought to play a pivotal role in immortalization of T cells. We have recently shown that the expression of Tax protected the mouse T-cell line CTLL-2 against apoptosis induced by interleukin-2 (IL-2) deprivation and converted its growth from being IL-2 dependent to being IL-2 independent. In this study, we demonstrate that constitutive expression of bcl-xl but not bcl-2, bcl-xs, bak, bad, or bax was associated with apoptosis resistance after IL-2 deprivation in CTLL-2 cells that expressed Tax. Transient-transfection assays showed that bcl-x promoter was transactivated by wild-type Tax. Similar effects were observed in mutant Tax retaining transactivating ability through NF-kappaB. Deletion or substitution of a putative NF-kappaB binding site identified in the bcl-x promoter significantly decreased Tax-induced transactivation. This NF-kappaB-like element was able to form a complex with NF-kappaB family proteins in vitro. Furthermore, Tax-induced transactivation of the bcl-x promoter was also diminished by the mutant IkappaBalpha, which specifically inhibits NF-kappaB activity. Our findings suggest that constitutive expression of Bcl-x(L) induced by Tax through the NF-kappaB pathway contributes to the inhibition of apoptosis in CTLL-2 cells after IL-2 deprivation. 相似文献