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121.
Studies on chemical modifications of bacterial and mitochondrial complex I by synthetic chemical probes as well as endogenous chemicals have provided useful information on the structural and functional aspects of this enzyme. We herein reviewed recent studies that investigated chemical modifications of complex I by endogenous chemicals (e.g. Cys-S-nitrosation, Cys-S-glutathionylation, and Ser-O-phosphorylation) and synthetic reagents (e.g. Cys-SH modification by SH-reagents and the cross-linking of nearby subunits by bifunctional cross-linkers). We also reviewed recent photoaffinity labeling studies using complex I inhibitors, which can be recognized as “site-specific modification” by synthetic chemicals. In addition, we discussed the possibility of site-specific modification by various functional probes via ligand-directed tosylate (LDT) chemistry as a promising approach for unique biophysical studies on complex I. 相似文献
122.
Misato Kobayashi Tamio Ohno Kunio Ihara Atsushi Murai Mayumi Kumazawa Hiromi Hoshino Koichiro Iwanaga Hiroshi Iwai Yoshiki Hamana Mikako Ito Kinji Ohno Fumihiko Horio 《PloS one》2014,9(5)
SMXA-5 mice are a high-fat diet-induced type 2 diabetes animal model established from non-diabetic SM/J and A/J mice. By using F2 intercross mice between SMXA-5 and SM/J mice under feeding with a high-fat diet, we previously mapped a major diabetogenic QTL (T2dm2sa) on chromosome 2. We then produced the congenic strain (SM.A-T2dm2sa (R0), 20.8–163.0 Mb) and demonstrated that the A/J allele of T2dm2sa impaired glucose tolerance and increased body weight and body mass index in the congenic strain compared to SM/J mice. We also showed that the combination of T2dm2sa and other diabetogenic loci was needed to develop the high-fat diet-induced type 2 diabetes. In this study, to narrow the potential genomic region containing the gene(s) responsible for T2dm2sa, we constructed R1 and R2 congenic strains. Both R1 (69.6–163.0 Mb) and R2 (20.8–128.2 Mb) congenic mice exhibited increases in body weight and abdominal fat weight and impaired glucose tolerance compared to SM/J mice. The R1 and R2 congenic analyses strongly suggested that the responsible genes existed in the overlapping genomic interval (69.6–128.2 Mb) between R1 and R2. In addition, studies using the newly established R1A congenic strain showed that the narrowed genomic region (69.6–75.4 Mb) affected not only obesity but also glucose tolerance. To search for candidate genes within the R1A genomic region, we performed exome sequencing analysis between SM/J and A/J mice and extracted 4 genes (Itga6, Zak, Gpr155, and Mtx2) with non-synonymous coding SNPs. These four genes might be candidate genes for type 2 diabetes caused by gene-gene interactions. This study indicated that one of the genes responsible for high-fat diet-induced diabetes exists in the 5.8 Mb genomic interval on mouse chromosome 2. 相似文献
123.
Tetsuya Akaishi Takuhiro Yamaguchi Yasushi Suzuki Yuriko Nagane Shigeaki Suzuki Hiroyuki Murai Tomihiro Imai Masakatsu Motomura Kazuo Fujihara Masashi Aoki Kimiaki Utsugisawa 《PloS one》2014,9(9)
Background and Purpose
Myasthenia gravis (MG) is often categorized into thymoma-associated MG, early-onset MG with onset age <50 years, and late-onset MG with onset age ≥50 years. However, the boundary age of 50 years old between early- and late-onset MG remains controversial, and each category contains further subtypes. We attempted to classify MG from a statistical perspective.Methods
We analyzed 640 consecutive MG patients using two-step cluster analysis with clinical variables and discrimination analysis, using onset age as a variable.Results
Two-step cluster analyses categorized MG patients into the following five subtypes: ocular MG; MG with thymic hyperplasia (THMG); generalized anti-acetylcholine receptor antibody (AChR-Ab)-negative MG; thymoma-associated MG; and generalized AChR-Ab-positive (SP) MG without thymic abnormalities. Among these 5 subtypes, THMG showed a distribution of onset age skewed toward a younger age (p<0.01), whereas ocular MG and SPMG without thymic abnormalities showed onset age skewed toward an older age (p<0.001 and p<0.0001, respectively). The other 2 subtypes showed normal distributions. THMG appeared as the main component of early-onset MG, and ocular MG and SPMG without thymic abnormalities as the main components of late-onset MG. Discrimination analyses between THMG and ocular MG and/or SPMG without thymic abnormalities demonstrated a boundary age of 45 years old.Conclusions
From a statistical perspective, the boundary age between early- and late-onset MG is about 45 years old. 相似文献124.
Kaori Yamada Tatsunori Saraike Naoki Shitsukawa Chizuru Hirabayashi Shigeo Takumi Koji Murai 《Plant molecular biology》2009,71(1-2):1-14
Homeotic transformation of stamens into pistil-like structures (pistillody) has been reported in cytoplasmic substitution (alloplasmic) lines of bread wheat (Triticum aestivum L.) that have the cytoplasm of a related wild species, Aegilops crassa. An ectopic ovule differentiates in the pistil-like stamen in the alloplasmic wheat. The SEEDSTICK (STK)—like class D MADS-box gene, wheat STK (WSTK), was expressed in the primordia of ectopic ovules in the pistil-like stamens as well as in the true pistil, suggesting that ectopic ovule formation results from WSTK expression in the pistil-like stamens of alloplasmic wheat. The ectopic ovule is abnormal as it fails to form complete integuments. Based on the expression pattern of WSTK and Bsister MADS-box gene, WBsis (wheat B sister ), we conclude that WSTK plays a role in determination of ovule identity in the pistil-like stamen, but complete ovule development fails due to aberrant expression of WBsis. 相似文献
125.
Qiu R Wang X Davy A Wu C Murai K Zhang H Flanagan JG Soriano P Lu Q 《The Journal of cell biology》2008,181(6):973-983
Maintaining a balance between self-renewal and differentiation in neural progenitor cells during development is important to ensure that correct numbers of neural cells are generated. We report that the ephrin-B-PDZ-RGS3 signaling pathway functions to regulate this balance in the developing mammalian cerebral cortex. During cortical neurogenesis, expression of ephrin-B1 and PDZ-RGS3 is specifically seen in progenitor cells and is turned off at the onset of neuronal differentiation. Persistent expression of ephrin-B1 and PDZ-RGS3 prevents differentiation of neural progenitor cells. Blocking RGS-mediated ephrin-B1 signaling in progenitor cells through RNA interference or expression of dominant-negative mutants results in differentiation. Genetic knockout of ephrin-B1 causes early cell cycle exit and leads to a concomitant loss of neural progenitor cells. Our results indicate that ephrin-B function is critical for the maintenance of the neural progenitor cell state and that this role of ephrin-B is mediated by PDZ-RGS3, likely via interacting with the noncanonical G protein signaling pathway, which is essential in neural progenitor asymmetrical cell division. 相似文献
126.
Using food network unfolding to evaluate food–web complexity in terms of biodiversity: theory and applications 下载免费PDF全文
Yoshikazu Kato Michio Kondoh Naoto F. Ishikawa Hiroyuki Togashi Yukihiro Kohmatsu Mayumi Yoshimura Chikage Yoshimizu Takashi F. Haraguchi Yutaka Osada Nobuhito Ohte Naoko Tokuchi Noboru Okuda Takeshi Miki Ichiro Tayasu 《Ecology letters》2018,21(7):1065-1074
Food–web complexity often hinders disentangling functionally relevant aspects of food–web structure and its relationships to biodiversity. Here, we present a theoretical framework to evaluate food–web complexity in terms of biodiversity. Food network unfolding is a theoretical method to transform a complex food web into a linear food chain based on ecosystem processes. Based on this method, we can define three biodiversity indices, horizontal diversity (DH), vertical diversity (DV) and range diversity (DR), which are associated with the species diversity within each trophic level, diversity of trophic levels, and diversity in resource use, respectively. These indices are related to Shannon's diversity index (H′), where H′ = DH + DV ? DR. Application of the framework to three riverine macroinvertebrate communities revealed that D indices, calculated from biomass and stable isotope features, captured well the anthropogenic, seasonal, or other within‐site changes in food–web structures that could not be captured with H′ alone. 相似文献
127.
Tumor cells enhance their own CD44 cleavage and motility by generating hyaluronan fragments 总被引:13,自引:0,他引:13
Sugahara KN Hirata T Hayasaka H Stern R Murai T Miyasaka M 《The Journal of biological chemistry》2006,281(9):5861-5868
Hyaluronan (HA) is an extracellular matrix glycosaminoglycan that interacts with cell-surface receptors, including CD44. Although HA usually exists as a high molecular mass polymer, HA of a much lower molecular mass that shows a variety of biological activities can be detected under certain pathological conditions, particularly in tumors. We previously reported that low molecular weight HAs (LMW-HAs) of a certain size range induce the proteolytic cleavage of CD44 from the surface of tumor cells and promote tumor cell migration in a CD44-dependent manner. Here, we show that MIA PaCa-2, a human pancreatic carcinoma cell line, secreted hyaluronidases abundantly and generated readily detectable levels of LMW-HAs ranging from approximately 10- to 40-mers. This occurred in the absence of any exogenous stimulation. The tumor-derived HA oligosaccharides were able to enhance CD44 cleavage and tumor cell motility. Inhibition of the CD44-HA interaction resulted in the complete abrogation of these cellular events. These results are consistent with the concept that tumor cells generate HA oligosaccha-rides that bind to tumor cell CD44 through the expression of their own constitutive hyaluronidases. This enhances their own CD44 cleavage and cell motility, which would subsequently promote tumor progression. Such an autocrine/paracrine-like process may represent a novel activation mechanism that would facilitate and promote the malignant potential of tumor cells. 相似文献
128.
The plant knotted1 (kn1)-like homeobox genes are known to play important roles in the maintenance of shoot apical meristem (SAM), determination of cell fate and differentiation of vegetative tissues. To study structural diversity of the three homologous loci encoding a KN1-like homeobox protein in the hexaploid wheat genome, we isolated clones from a cDNA library of young spikes of Japanese common wheat cultivar 'Norin 26'. Three different but highly homologous cDNAs were isolated and their sequences were determined. The mean homology of the deduced amino acid sequences was 96% as compared to the barley ortholog KNOX3. The wheat kn1-like homeobox proteins named WKNOX1 are encoded by a single set of homologous genes on the homologous group 4 chromosomes in the three component genomes of common wheat, i.e. 4A, 4B and 4D. The nucleotide sequence data and the Southern blot pattern suggested that the three homologous loci of wknox1 genes are highly conserved through polyploid evolution of wheat. They were expressed in SAM-containing shoots and young spikes but not in developed leaves, glumes and lemmas and callus tissues. The ectopic expression of the wknox1 was observed in lemma of wheat Hooded (Hd) mutants. The result suggested that the Hd gene is a dominant allele of the wknox1 locus on chromosome 4A. 相似文献
129.
130.
Junji Sakurada Li Zhijun Keiko Seki Miyo Murai Akemi Usui Mami Morihigashi Hiroko Jitsukawa Hee Kyung Seong Mitsuaki Mutou Shogo Masuda 《FEMS microbiology letters》1994,119(1-2):59-63
Abstract We investigated the biochemical and genetic heterogeneity of protein A from Staphylococcus aureus . SpA genes ( spas ) of various strains were heterogeneous when detected as Dra I and Eco RV fragments of chromosomal DNA. Polymerase chain reaction using primers to detect DNA encoding the IgG-binding domains in spa revealed that they numbered between 2 and 5. Protein A from several S. aureus strains showed two types of reactivities to immunoglobulins in normal canine serum according to the number of active domains. 相似文献