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101.
102.
Ito Y Ozawa A Sawasaki T Endo Y Ochi K Tozawa Y 《Bioscience, biotechnology, and biochemistry》2002,66(12):2727-2731
A rice gene, OsRALyase1, encoding a product similar to wheat ribosomal RNA apurinic site specific lyase (RALyase), was isolated and expressed in vitro. An open reading frame of the gene predicted a protein of 476 amino acid residues with 75% identity to RALyase and contained an F-box-like motif in its amino terminal region. The rice gene product expressed in a wheat-germ protein expression system had the same characteristics as its wheat counterpart, cleaving a specific depurinated site of the 28S rRNA sarcin-ricin domain. 相似文献
103.
Arf1 GTPase plays roles in the protein traffic between the endoplasmic reticulum and the Golgi apparatus in tobacco and Arabidopsis cultured cells 总被引:12,自引:0,他引:12
Takeuchi M Ueda T Yahara N Nakano A 《The Plant journal : for cell and molecular biology》2002,31(4):499-515
Arf GTPases are known to be key regulators of vesicle budding in various steps of membrane traffic in yeast and animal cells. We cloned the Arabidopsis Arf1 homologue, AtArf1, and examined its function. AtArf1 complements yeast arf1 arf2 mutants and its GFP-fusion is localized to the Golgi apparatus in plant cells like its animal counterpart. The expression of dominant negative mutants of AtArf1 in tobacco and Arabidopsis cultured cells affected the localization of co-expressed GFP-tagged proteins in a variety of ways. AtArf1 Q71L and AtArf1 T31N, GTP- and GDP-fixed mutants, respectively, changed the localization of a cis-Golgi marker, AtErd2-GFP, from the Golgi apparatus to the endoplasmic reticulum but not that of GFP-AtRer1B or GFP-AtSed5. GFP-AtRer1B and GFP-AtSed5 were accumulated in aberrant structures of the Golgi by AtArf1 Q71L. A soluble vacuolar protein, sporamin-GFP, was also located to the ER by AtArf1 Q71L. These results indicate that AtArf1 play roles in the vesicular transport between the ER and the Golgi and in the maintenance of the normal Golgi organization in plant cells. 相似文献
104.
Perry G Taddeo MA Nunomura A Zhu X Zenteno-Savin T Drew KL Shimohama S Avila J Castellani RJ Smith MA 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2002,133(4):507-513
In this review, we consider comparative aspects of the biology and pathology of oxygen radicals in neurodegenerative disease and how these findings have influenced our concept of oxidative stress. The common definition of oxidative stress is a breach of antioxidant defenses by oxygen radicals leading to damage to critical molecules and disrupted physiology. Inherent in this definition is that oxidative stress is an unstable situation, for if there is net damage, viability of the system decreases with time, leading to disequilibria and death. While this circumstance defines acute conditions, such as stroke and head trauma which result in dysfunction and death, it does not fit physiological situations or chronic diseases closely aligned to normal physiology. Therefore, we propose that oxidative modifications in Alzheimer disease may actually serve as a homeostatic response to stress resulting in a shift of neuronal priority from normal function to basic survival. This phenomenon is comparable to normal physiological conditions of metabolic decrease, such as those seen in hibernation and estivation. Thus, Alzheimer disease could be seen as part of normal aging that includes additional pathology due to inadequate homeostatic response. 相似文献
105.
The skeletal attachment of tendons--tendon "entheses" 总被引:9,自引:0,他引:9
Benjamin M Kumai T Milz S Boszczyk BM Boszczyk AA Ralphs JR 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2002,133(4):931-945
Tendon entheses can be classed as fibrous or fibrocartilaginous according to the tissue present at the skeletal attachment site. The former can be "bony" or "periosteal", depending on whether the tendon is directly attached to bone or indirectly to it via the periosteum. At fibrocartilaginous entheses, the uncalcified fibrocartilage dissipates collagen fibre bending and tendon narrowing away from the tidemark; calcified fibrocartilage anchors the tendon to the bone and creates a diffusion barrier between the two. Where there are additional fibrocartilaginous specialisations in the tendon and/or bone next to the enthesis, an "enthesis organ" is created that reduces wear and tear. Little attention has been paid to bone at entheses, despite the obvious bearing this has on the mechanical properties of the interface and the clinical importance of avulsion fractures. Disorders at entheses (enthesopathies) are common and occur in conditions such as diffuse idiopathic skeletal hyperostosis and the seronegative spondyloarthropathies. They are also commonly seen as sporting injuries such as tennis elbow and jumper's knee. 相似文献
106.
In a theoretical analysis of the present study, we quantitatively indicate a potential threat of congenital toxoplasmosis to Japanese young women by the use of a simple mathematical model or a special case of the well-known catalytic infection model. For introducing a risk function of congenital toxoplasmosis, an annual infection rate, r, was divided into r(1), the rate before age a(0 < a < 15), and r(2), the rate after age a. Presuming the values of r(1), r(2) and a on the basis of the current situation of Toxoplasma infection in Japan, simulation analyses were performed with the mathematical model. As the simulation clearly demonstrated, Japanese young women are potentially facing a threat of congenital toxoplasmosis, although the current risk of it is relatively lower. From the viewpoint of risk management, public intervention programs are required. Based on our analyses, public intervention programs can be classified into two groups: group 1 for women before age a and group 2 for those after age a, and each group is expected to give a different kind of effect to the risk of congenital toxoplasmosis. The present study implies that a certain public intervention program could augment the risk, inadvertently. 相似文献
107.
Hori H Nagasawa H Ishibashi M Uto Y Hirata A Saijo K Ohkura K Kirk KL Uehara Y 《Bioorganic & medicinal chemistry》2002,10(10):3257-3265
A series of 2-hydroxyarylidene-4-cyclopentene-1,3-diones were designed, synthesized, and evaluated with respect to protein tyrosine kinase (PTK) inhibition, mitochondrial toxicity, and antitumor activity. Our results show that the cyclopentenedione-derived TX-1123 is a more potent antitumor tyrphostin and also shows lower mitochondrial toxicity than the malononitrile-derived AG17, a potent antitumor tyrphostin. The O-methylation product of TX-1123 (TX-1925) retained its tyrphostin-like properties, including mitochondrial toxicity and antitumor activities. However, the methylation product of AG17 (TX-1927) retained its tyrphostin-like antitumor activities, but lost its mitochondrial toxicity. Our comprehensive evaluation of these agents with respect to protein tyrosine kinase inhibition, mitochondrial inhibition, antitumor activity, and hepatotoxicity demonstrates that PTK inhibitors TX-1123 and TX-1925 are more promising candidates for antitumor agents than tyrphostin AG17. 相似文献
108.
Gene Transfer and Cloning of Flanking Chromosomal Regions Using the Medaka Fish Tol2 Transposable Element 总被引:1,自引:0,他引:1
For the ultimate purpose of developing genetic tools using the medaka fish Tol2 transposable element, we examined whether it can transfer a marker gene into the fish genome and also be applied for cloning
of chromosomal regions adjacent to insertion points. An internal region of Tol2 was removed and replaced with the green fluorescent protein (GFP) gene and a bacterial plasmid replication origin. This modified
Tol2 clone was microinjected into fertilized eggs together with messenger RNA for the Tol2 transposase. The GFP gene was found to be integrated into chromosomes and transmitted to subsequent generations. Restriction
enzyme digestion of genomic DNA of a transformant fish, followed by ligation and introduction into bacteria, produced a plasmid
containing the entire element and flanking chromosomal regions. Sequencing analysis of this clone demonstrated transposition
of the element in the germline of the first generation. Thus, the basic requirements for a gene transfer vector and gene tagging
system were fulfilled.
Received July 30, 2001; accepted October 4, 2001 相似文献
109.
Fertilization is a significant event for reproducing offspring. It is achieved under a species-specific environment, which influences the conditions to assure the successful fertilization in some cases. Several studies about the basic mechanism of fertilization suggest that the fertilization mechanism is modified among species to be suited for the fertilization environment. In amphibians, many anurans undergo external fertilization while most urodeles do internal fertilization. An amphibian egg is surrounded by egg-coats, which are composed of vitelline envelope and layered egg-jelly. They are significant as fields for the sperm-egg interaction at fertilization. The fertilization processes that take place in the egg-coats are supposed to be easily influenced by the fertilization environment, because they, especially egg-jelly, are exposed to the surroundings at fertilization. In the present article, we describe the fertilization system equipped in newt egg-coats. Newt sperm are stored in spermatheca that exists in cloaca of a female and directly inseminated on the surface of egg-jelly. Sperm motility and acrosome reaction are induced in the outermost portion of the egg-jelly. Motion of the moving sperm becomes vigorous in the egg-jelly and sperm are guided to vitelline envelope by the aid of egg-jelly structure. Most of the sperm passing through the egg-jelly, as the result, has been induced acrosome reaction and those sperm can bind to the vitelline envelope to contribute to the successful fertilization. This fertilization system has a distinct feature from the known system in species undergoing external fertilization. The feature of the system in the newt egg-jelly is discussed with the view to achieving the successful fertilization in the internal environment. 相似文献
110.
Harada N Himeno A Shigematsu K Sumikawa K Niwa M 《Cellular and molecular neurobiology》2002,22(2):207-226
1. Interaction in the recognition of endothelin-1 (ET-1), a typical bivalent ET receptor-ligand, between ETA and ETB receptors was investigated in the rat anterior pituitary gland, using our quantitative receptor autoradiographic method with tissue sections preserving the cell-membrane structure and ET receptor-related compounds.2. In saturation binding studies with increasing concentrations (0.77–200 pM) of 125I-ET-1 (nonselective bivalent radioligand), 125I-ET-1 binding to the rat anterior pituitary gland was saturable and single with a K
D of 71 pM and a B
max of 120 fmol mg–1. When 1.0 M BQ-123 (ETA antagonist) was added to the incubation buffer, binding parameters were 8.3 pM of K
D and 8.0 fmol mg–1 of B
max, whereas 10 nM sarafotoxin S6c (ETB agonist) exerted little change in these binding parameters (K
D, 72 pM; B
max, 110 fmol mg–1).3. Competition binding studies with a fixed amount (3.8 pM) of 125I-ET-1 revealed that when 1.0 M BQ-123 was present in the incubation buffer, ETB receptor-related compounds such as sarafotoxin S6c, ET-3, IRL1620 (ETB agonist), and BQ-788 (ETB antagonist) competitively inhibited 125I-ET-1 binding with K
is of 140, 18, 350 pM, and 14 nM, respectively, however, these compounds were not significant competitors for 125I-ET-1 binding in the case of absence of BQ-123.4. In cold-ligand saturation studies with a fixed amount (390 pM) of 125I-IRL 1620 (ETB radioligand), IRL1620 bound to a single population of the ETB receptor, and no change was observed in binding characteristics in the presence of 1.0 M BQ-123. 125I-IRL1620 binding was competitively inhibited by ET-1 and ET-3 in the absence of BQ-123, with K
is of 20 and 29 pM, respectively, the affinities being much the same as those of 29 nM, in the presence of 1.0 M BQ-123.5. Two nonbivalent ETA antagonists, BQ-123 and PD151242, were highly sensitive and full competitors for 125I-ET-1 binding (5.0 pM), in the presence of 10 nM sarafotoxin S6c.6. Taken together with the present finding that mRNAs encoding the rat ETA and the ETB receptors are expressed in the anterior pituitary gland, we tentatively conclude that although there are ETA and ETB receptors with a functional binding capability for ET receptor-ligands, the ETB receptor does not independently recognize ET-1 without the aid of the ETA receptor. If this thesis is tenable, then ET-1 can bridge between the two receptors to form an ETA–ETB receptor heterodimer. 相似文献