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81.
Translesion replication of benzo[a]pyrene and benzo[c]phenanthrene diol epoxide adducts of deoxyadenosine and deoxyguanosine by human DNA polymerase iota 下载免费PDF全文
Frank EG Sayer JM Kroth H Ohashi E Ohmori H Jerina DM Woodgate R 《Nucleic acids research》2002,30(23):5284-5292
Human DNA polymerase ι (polι) is a Y-family polymerase whose cellular function is presently unknown. Here, we report on the ability of polι to bypass various stereoisomers of benzo[a]pyrene (BaP) diol epoxide (DE) and benzo[c]phenanthrene (BcPh) DE adducts at deoxyadenosine (dA) or deoxyguanosine (dG) bases in four different template sequence contexts in vitro. We find that the BaP DE dG adducts pose a strong block to polι-dependent replication and result in a high frequency of base misincorporations. In contrast, misincorporations opposite BaP DE and BcPh DE dA adducts generally occurred with a frequency ranging between 2 × 10–3 and 6 × 10–4. Although dTMP was inserted efficiently opposite all dA adducts, further extension was relatively poor, with one exception (a cis opened adduct derived from BcPh DE) where up to 58% extension past the lesion was observed. Interestingly, another human Y-family polymerase, polκ, was able to extend dTMP inserted opposite a BaP DE dA adduct. We suggest that polι might therefore participate in the error-free bypass of DE-adducted dA in vivo by predominantly incorporating dTMP opposite the damaged base. In many cases, elongation would, however, require the participation of another polymerase more specialized in extension, such as polκ. 相似文献
82.
Isolation and identification of EG-VEGF/prokineticins as cognate ligands for two orphan G-protein-coupled receptors 总被引:8,自引:0,他引:8
Masuda Y Takatsu Y Terao Y Kumano S Ishibashi Y Suenaga M Abe M Fukusumi S Watanabe T Shintani Y Yamada T Hinuma S Inatomi N Ohtaki T Onda H Fujino M 《Biochemical and biophysical research communications》2002,293(1):396-402
Endocrine gland-derived vascular endothelial growth factor (EG-VEGF, identical to prokineticin 1) is a novel peptide recently identified as a selective mitogen for endocrine gland endothelial cells. The present study demonstrates that EG-VEGF/prokineticin 1 and a peptide closely related to EG-VEGF, prokineticin 2, are cognate ligands of two orphan G-protein-coupled receptors designated ZAQ (=EG-VEGF/PK-R1) and I5E (=EG-VEGF/PK-R2). EG-VEGF/prokineticin 1 and prokineticin 2 induced a transient increase in intracellular calcium ion concentration ([Ca(2+)](i)) with nanomolar potency in Chinese hamster ovary (CHO) cells expressing EG-VEGF/PK-R1 and -R2 and bind to these cells with high affinity and with different receptor selectivity. EG-VEGF/prokineticins provoke rapid phosphorylation of p44/42 MAP kinase and DNA synthesis in the bovine adrenal capillary endothelial cells (BACE). The mRNAs of both EG-VEGF/PK-R1 and -R2 were expressed in BACE. The identification of the receptors for EG-VEGF/prokineticins may provide a novel molecular basis for the regulation of angiogenesis in endocrine glands. 相似文献
83.
Complete genome sequence and comparative analysis of the industrial microorganism Streptomyces avermitilis 总被引:25,自引:0,他引:25
Ikeda H Ishikawa J Hanamoto A Shinose M Kikuchi H Shiba T Sakaki Y Hattori M Omura S 《Nature biotechnology》2003,21(5):526-531
Species of the genus Streptomyces are of major pharmaceutical interest because they synthesize a variety of bioactive secondary metabolites. We have determined the complete nucleotide sequence of the linear chromosome of Streptomyces avermitilis. S. avermitilis produces avermectins, a group of antiparasitic agents used in human and veterinary medicine. The genome contains 9,025,608 bases (average GC content, 70.7%) and encodes at least 7,574 potential open reading frames (ORFs). Thirty-five percent of the ORFs (2,664) constitute 721 paralogous families. Thirty gene clusters related to secondary metabolite biosynthesis were identified, corresponding to 6.6% of the genome. Comparison with Streptomyces coelicolor A3(2) revealed that an internal 6.5-Mb region in the S. avermitilis genome was highly conserved with respect to gene order and content, and contained all known essential genes but showed perfectly asymmetric structure at the oriC center. In contrast, the terminal regions were not conserved and preferentially contained nonessential genes. 相似文献
84.
Takahashi I Shimada M Akimoto T Kishi T Sugi H 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2003,134(1):115-120
The anterior byssal retractor muscle (ABRM) of a bivalve mollusc Mytilus edulis is known to exhibit catch state, i.e. a prolonged tonic contraction maintained with very little energy expenditure. Two different hypotheses have been put forward concerning the catch state; one assumes actin-myosin linkages between the thick and thin filaments that dissociate extremely slowly (linkage hypothesis), while the other postulates a load-bearing structure other than actin-myosin linkages (parallel hypothesis). We explored the possible load-bearing structure responsible for the catch state by examining the arrangement of the thick and thin filaments within the ABRM fibers, using techniques of quick freezing and freeze substitution. No thick filament aggregation was observed in the cross-section of the fibers quickly frozen not only in the relaxed and actively contracting states but also in the catch state. The thick filaments were, however, occasionally interconnected with each other either directly or by distinct projections in all the three states studied. The proportion of the interconnected thick filaments relative to the total thick filaments in a given cross-sectional area was much larger in the catch state than in the relaxed and actively contracting states, providing evidence that the thick filament interconnection is responsible for the catch state. 相似文献
85.
Expression of placental lactogen and cytokeratin in bovine placental binucleate cells in culture 总被引:1,自引:0,他引:1
Binucleate cells are present in ruminant placenta and play an endocrine role in the production of many hormones during pregnancy. We isolated and cultured binucleate cells from bovine placenta at middle to late gestation and characterized these cells using immunofluorescence techniques. Enriched preparations of binucleate cells were obtained using Percoll density gradient centrifugation following collagenase digestion. Binucleate cells in culture preferentially attached to collagen-coated dishes rather than to noncoated plastic dishes. The cells gradually extended their edges on collagen substrata, and finally assumed a flattened morphology. Antibodies to placental lactogen (PL) and pregnancy-associated glycoprotein-1 (PAG-1) specifically stained the majority of round binucleate cells, but not the flat cells. We found that PL-positive binucleate cells were consistently devoid of cytokeratin. In contrast, cytokeratin was expressed in PL-negative binucleate cells as well as mononuclear epithelial cells. Furthermore, the PL-negative flat binucleate cells also developed intense cytokeratin networks in the cytoplasm. These results indicate that cytokeratin expression is inversely proportionate to that of PL in cultured binucleate cells. We conclude that downregulation of cytokeratin in binucleate cells is a function of the state of cellular differentiation. 相似文献
86.
Miyasaka Hitoshi Kanaboshi Haruo Ikeda Kazunori 《World journal of microbiology & biotechnology》2000,16(1):23-29
To isolate anti-stress genes from a halotolerant marine green alga, a simple screening method based on the bacterial expression system was examined. The method consisted of three steps: (i) directional cDNA library construction in a ZAPII vector, (ii) in vivo mass excision of a ZAPII library into phagemid DNA, and (iii) screening for anti-salt-stress and anti-oxidative-stress genes by culturing bacterial cells carrying the in vivo excised phagemid on selection agar plates with a high concentration of NaCl and/or methyl viologen (MV), and by isolating stress-tolerant bacterial colonies. By this method, we screened the cDNA library of halotolerant Chlamydomonas sp. strain W-80, and isolated several stress-related gene homologs, such as glutathione peroxidase, ascorbate peroxidase, bbc1 (breast basic conserved; a low temperature induced gene in Brassica napus), and cyanide-resistant alternative oxidase. 相似文献
87.
Tsukasa Tameyasu Naokata Ishii Noboru Oishi Mitsuyo Shimada Ibuki Shirakawa Tsuyoshi Akimoto Naoto Yamamoto Shoichi Kosuge Haruo Sugi 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》1998,120(4):731-736
To investigate characteristics of ATP-dependent sliding of a non-muscle cell myosin, obtained from a cellular slime mold Dictyostelium discoideum, on actin filament, we prepared hybrid thick filaments, in which Dictyostelium myosin was regularly arranged around paramyosin filaments obtained from a molluscan smooth muscle. A single to a few hybrid filaments were attached to a polystyrene bead (diameter, 4.5 μm; specific gravity, 1.5), and the filaments were made to slide on actin filament arrays (actin cables) in the internodal cell of an alga Chara corallina, mounted on the rotor of a centrifuge microscope. The filament-attached bead was observed to move with a constant velocity under a constant external load for many seconds. The steady-state force–velocity relation of Dictyostelium myosin sliding on actin cables was hyperbolic in shape except for large loads ≤0.7–0.8 P0, being qualitatively similar to that of skeletal muscle fibres, despite a considerable variation in the number of myosin molecules interacting with actin cables. Comparison of the P–V curves between Dictyostelium myosin and muscle myosins sliding on actin cables suggests that the time of attachment to actin in a single attachment–detachment cycle is much longer in Dictyostelium myosin than in muscle myosins. 相似文献
88.
Kazuyuki Wakabayashi Kouichi Soga Takayuki Hoson Toshihisa Kotake Takashi Yamazaki Akira Higashibata Noriaki Ishioka Toru Shimazu Keiji Fukui Ikuko Osada Haruo Kasahara Motoshi Kamada 《PloS one》2015,10(9)
Network structures created by hydroxycinnamate cross-links within the cell wall architecture of gramineous plants make the cell wall resistant to the gravitational force of the earth. In this study, the effects of microgravity on the formation of cell wall-bound hydroxycinnamates were examined using etiolated rice shoots simultaneously grown under artificial 1 g and microgravity conditions in the Cell Biology Experiment Facility on the International Space Station. Measurement of the mechanical properties of cell walls showed that shoot cell walls became stiff during the growth period and that microgravity suppressed this stiffening. Amounts of cell wall polysaccharides, cell wall-bound phenolic acids, and lignin in rice shoots increased as the shoot grew. Microgravity did not influence changes in the amounts of cell wall polysaccharides or phenolic acid monomers such as ferulic acid (FA) and p-coumaric acid, but it suppressed increases in diferulic acid (DFA) isomers and lignin. Activities of the enzymes phenylalanine ammonia-lyase (PAL) and cell wall-bound peroxidase (CW-PRX) in shoots also increased as the shoot grew. PAL activity in microgravity-grown shoots was almost comparable to that in artificial 1 g-grown shoots, while CW-PRX activity increased less in microgravity-grown shoots than in artificial 1 g-grown shoots. Furthermore, the increases in expression levels of some class III peroxidase genes were reduced under microgravity conditions. These results suggest that a microgravity environment modifies the expression levels of certain class III peroxidase genes in rice shoots, that the resultant reduction of CW-PRX activity may be involved in suppressing DFA formation and lignin polymerization, and that this suppression may cause a decrease in cross-linkages within the cell wall architecture. The reduction in intra-network structures may contribute to keeping the cell wall loose under microgravity conditions. 相似文献
89.
Yoshiaki Tsuda Haruo Sawada Takafumi Ohsawa Katsuhiro Nakao Hiroki Nishikawa Yuji Ide 《Tree Genetics & Genomes》2010,6(3):377-387
We evaluated the genetic structure of 16 Betula maximowicziana populations in the Chichibu mountain range, central Japan, located within a 25-km radius; all but two populations were at
altitudes of 1,100–1,400 m. The results indicate the effects of geographic topology on the landscape genetic structure of
the populations and should facilitate the development of local-scale strategies to conserve and manage them. Analyses involving
11 nuclear simple sequence repeat loci showed that most populations had similar intrapopulation genetic diversity parameters.
Population differentiation (F
ST = 0.021, G′ST = 0.033) parameters for the populations examined were low but were relatively high compared to those obtained in a previous
study covering populations in a much larger area with a radius of approximately 1,000 km (F
ST = 0.062, G′ST = 0.102). Three populations (Iriyama, Kanayamasawa, and Nishizawa) were differentiated from the other populations by Monmonier’s
and spatial analysis of molecular variance algorithms or by STRUCTURE analysis. Since a high mountain ridge (nearly 2,000 m)
separates the Kanayamasawa and Nishizawa populations from the other 14 populations and the Kanayamasawa and Nishizawa populations
are themselves separated by another mountain ridge, the genetic structure appears to be partly due to mountain ridges acting
as genetic barriers and restricting gene flow. However, the Iriyama population is genetically different but not separated
by any clear geographic barrier. These results show that the landscape genetic structure is complex in the mountain range
and we need to pay attention, within landscape genetic studies and conservation programs, to geographic barriers and local
population differentiation. 相似文献
90.
Transmembrane mucins Hkr1 and Msb2 are putative osmosensors in the SHO1 branch of yeast HOG pathway 总被引:3,自引:0,他引:3
Tatebayashi K Tanaka K Yang HY Yamamoto K Matsushita Y Tomida T Imai M Saito H 《The EMBO journal》2007,26(15):3521-3533
To cope with life-threatening high osmolarity, yeast activates the high-osmolarity glycerol (HOG) signaling pathway, whose core element is the Hog1 MAP kinase cascade. Activated Hog1 regulates the cell cycle, protein translation, and gene expression. Upstream of the HOG pathway are functionally redundant SLN1 and SHO1 signaling branches. However, neither the osmosensor nor the signal generator of the SHO1 branch has been clearly defined. Here, we show that the mucin-like transmembrane proteins Hkr1 and Msb2 are the potential osmosensors for the SHO1 branch. Hyperactive forms of Hkr1 and Msb2 can activate the HOG pathway only in the presence of Sho1, whereas a hyperactive Sho1 mutant activates the HOG pathway in the absence of both Hkr1 and Msb2, indicating that Hkr1 and Msb2 are the most upstream elements known so far in the SHO1 branch. Hkr1 and Msb2 individually form a complex with Sho1, and, upon high external osmolarity stress, appear to induce Sho1 to generate an intracellular signal. Furthermore, Msb2, but not Hkr1, can also generate an intracellular signal in a Sho1-independent manner. 相似文献