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81.
A study of the ontogeny of the lateral line system in leptocephali of the Japanese eel Anguilla japonica reveals the existence of three morphologically different types of lateral line organs. Type I is a novel sensory organ with hair cells bearing a single kinocilium, lacking stereocilia, distributed mainly on the head of larvae, and morphologically different from typical superficial neuromasts of the lateral line system. Its developmental sequence suggests that it may be a presumptive canal neuromast. Type II is an ordinary superficial neuromast, common in other teleost larvae, which includes presumptive canal neuromasts that first appear on the trunk and accessory superficial neuromasts that later appear on the head and trunk. Type III is a very unusual neuromast located just behind the orbit, close to the otic vesicle, with radially oriented hair cells, suggesting that these serve as multiple axes of sensitivity for mechanical stimuli. The behavior of larval eels suggests that the radially oriented neuromasts may act as the sole mechanosensory organ until the ordinary superficial neuromasts develop. The finding that larval eels possess a well-developed mechanosensory system suggests the possibility that they are also capable of perceiving weak environmental mechanical stimuli, like other teleost larvae. 相似文献
82.
Purification and characterization of formate oxidase from a formaldehyde-resistant fungus 总被引:6,自引:0,他引:6
A formate oxidase activity was found in the crude extract of a formaldehyde-resistant fungus isolated from soil. The fungus was classified and designated as Aspergillus nomius IRI013, which could grow on a medium containing up to 0.45% formaldehyde and consumed formaldehyde completely. The specific activity of formate oxidase in the extract of the fungus grown on formaldehyde was found to be considerably higher than that in the extracts of the fungus grown on formate and methanol. Formate oxidase from the fungus grown on formaldehyde was purified to homogeneity. The enzyme had a relative molecular mass of 100000 and was composed of two apparently identical subunits that had a relative molecular mass of 59000. The enzyme showed the highest activity using formate as substrate. Hydrogen peroxide was formed during the oxidation of formate. The Michaelis constant for formate was 15.9 mM; highest enzyme activity was found at pH 4.5-5.0. The enzyme activity was strongly inhibited by NaN(3), p-chloromercuribenzoate and HgCl(2). 相似文献
83.
Iwabuchi N Sunairi M Urai M Itoh C Anzai H Nakajima M Harayama S 《Applied and environmental microbiology》2002,68(5):2337-2343
Rhodococcus rhodochrous S-2 produces extracellular polysaccharides (S-2 EPS) containing D-glucose, D-galactose, D-mannose, D-glucuronic acid, and lipids, which is important to the tolerance of this strain to an aromatic fraction of (AF) Arabian light crude oil (N. Iwabuchi, N. Sunairi, H. Anzai, M. Nakajima, and S. Harayama, Appl. Environ. Microbiol. 66:5073-5077, 2000). In the present study, we examined the effects of S-2 EPS on the growth of indigenous marine bacteria on AF. Indigenous bacteria did not grow significantly in seawater containing AF even when nitrogen, phosphorus, and iron nutrients were supplemented. The addition of S-2 EPS to seawater containing nutrients and AF resulted in the emulsification of AF, promotion of the growth of indigenous bacteria, and enhancement of the degradation of AF by the bacteria. PCR-denaturing gradient gel electrophoresis analyses show that addition of S-2 EPS to the seawater containing nutrients and AF changed the composition of the bacterial populations in the seawater and that bacteria closely related to the genus Cycloclasticus became the major population. These results suggest that Cycloclasticus was responsible for the degradation of hydrocarbons in AF. The effects of 15 synthetic surfactants on the degradation of AF by indigenous marine bacteria were also examined, but enhancement of the degradation of AF was not significant. S-2 EPS was hence the most effective of the surfactants tested in promoting the biodegradation of AF and may thus be an attractive agent to use in the bioremediation of oil-contaminated marine environments. 相似文献
84.
Ohta N Hiroi T Kweon MN Kinoshita N Jang MH Mashimo T Miyazaki J Kiyono H 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(1):460-468
To clarify the role of IL-15 at local sites, we engineered a transgenic (Tg) mouse (T3(b)-IL-15 Tg) to overexpress human IL-15 preferentially in intestinal epithelial cells by the use of T3(b)-promoter. Although IL-15 was expressed in the entire small intestine (SI) and large intestines of the Tg mice, localized inflammation developed in the proximal SI only. Histopathologic study revealed reduced villus length, marked infiltration of lymphocytes, and vacuolar degeneration of the villus epithelium, beginning at approximately 3-4 mo of age. The numbers of CD8(+) T cells, especially CD8alphabeta(+) T cells expressing NK1.1, were dramatically increased in the lamina propria of the involved SI. The severity of inflammation corresponded to increased numbers of CD8alphabeta(+)NK1.1(+) T cells and levels of production of the Th1-type cytokines IFN-gamma and TNF-alpha. Locally overexpressed IL-15 was accompanied by increased resistance of CD8alphabeta(+) NK1.1(+) T cells to activation-induced cell death. Our results suggest that chronic inflammation in the SI in this murine model is mediated by dysregulation of epithelial cell-derived IL-15. The model may contribute to understanding the role of CD8(+) T cells in human Crohn's disease involving the SI. 相似文献
85.
Sato Y Nabeta Y Tsukahara T Hirohashi Y Syunsui R Maeda A Sahara H Ikeda H Torigoe T Ichimiya S Wada T Yamashita T Hiraga H Kawai A Ishii T Araki N Myoui A Matsumoto S Umeda T Ishii S Kawaguchi S Sato N 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(3):1611-1618
To investigate the immunogenic property of peptides derived from the synovial sarcoma-specific SYT-SSX fusion gene, we synthesized four peptides according to the binding motif for HLA-A24. The peptides, SS391 (PYGYDQIMPK) and SS393 (GYDQIMPKK), were derived from the breakpoint of SYT-SSX, and SS449a (AWTHRLRER) and SS449b (AWTHRLRERK) were from the SSX region. These peptides were tested for their reactivity with CTL precursors (CTLps) in 16 synovial sarcoma patients using HLA-A24/SYT-SSX peptide tetramers and also for induction of specific CTLs from four HLA-A24(+) synovial sarcoma patients. Tetramer analysis indicated that the increased CTLp frequency to the SYT-SSX was associated with pulmonary metastasis in synovial sarcoma patients (p < 0.03). CTLs were induced from PBLs of two synovial sarcoma patients using the peptide mixture of SS391 and SS393, which lysed HLA-A24(+) synovial sarcoma cells expressing SYT-SSX as well as the peptide-pulsed target cells in an HLA class I-restricted manner. These findings suggest that aberrantly expressed SYT-SSX gene products have primed SYT-SSX-specific CTLps in vivo and increased their frequency in synovial sarcoma patients. The identification of SYT-SSX peptides may offer an opportunity to design peptide-based immunotherapeutic approaches for HLA-A24(+) patients with synovial sarcoma. 相似文献
86.
87.
Molecular characterization of mammalian dicarbonyl/L-xylulose reductase and its localization in kidney 总被引:6,自引:0,他引:6
Nakagawa J Ishikura S Asami J Isaji T Usami N Hara A Sakurai T Tsuritani K Oda K Takahashi M Yoshimoto M Otsuka N Kitamura K 《The Journal of biological chemistry》2002,277(20):17883-17891
In this report, we first cloned a cDNA for a protein that is highly expressed in mouse kidney and then isolated its counterparts in human, rat hamster, and guinea pig by polymerase chain reaction-based cloning. The cDNAs of the five species encoded polypeptides of 244 amino acids, which shared more than 85% identity with each other and showed high identity with a human sperm 34-kDa protein, P34H, as well as a murine lung-specific carbonyl reductase of the short-chain dehydrogenase/reductase superfamily. In particular, the human protein is identical to P34H, except for one amino acid substitution. The purified recombinant proteins of the five species were about 100-kDa homotetramers with NADPH-linked reductase activity for alpha-dicarbonyl compounds, catalyzed the oxidoreduction between xylitol and l-xylulose, and were inhibited competitively by n-butyric acid. Therefore, the proteins are designated as dicarbonyl/l-xylulose reductases (DCXRs). The substrate specificity and kinetic constants of DCXRs for dicarbonyl compounds and sugars are similar to those of mammalian diacetyl reductase and l-xylulose reductase, respectively, and the identity of the DCXRs with these two enzymes was demonstrated by their co-purification from hamster and guinea pig livers and by protein sequencing of the hepatic enzymes. Both DCXR and its mRNA are highly expressed in kidney and liver of human and rodent tissues, and the protein was localized primarily to the inner membranes of the proximal renal tubules in murine kidneys. The results imply that P34H and diacetyl reductase (EC ) are identical to l-xylulose reductase (EC ), which is involved in the uronate cycle of glucose metabolism, and the unique localization of the enzyme in kidney suggests that it has a role other than in general carbohydrate metabolism. 相似文献
88.
We report here the molecular cloning and characterization of a glucocerebrosidase [EC 3.2.1.45] from Paenibacillus sp. TS12. The open reading frame of the glucocerebrosidase gene consisted of 2,493 bp nucleotides and encoded 831 amino acid residues. The enzyme exhibited no sequence similarity with a classical glucocerebrosidase belonging to glycoside hydrolase (GH) family 30, but rather showed significant similarity with GH family 3 beta-glucosidases from Clostridium thermocellum, Ruminococcus albus, and Aspergillus aculeateus. The recombinant enzyme, expressed in Escherichia coli BL21(DE3)pLysS, had a molecular weight of 90.7 kDa and hydrolyzed NBD-labeled glucosylceramide, but not galactosylceramide, GM1a or sphingomyelin. The enzyme was most active at pH 6.5, and its apparent Km and Vmax values for NBD-labeled glucosylceramide and p-nitrophenyl-beta-glucopyranoside were 223 microM and 1.60 micromol/min/mg of protein, and 593 microM and 112 micromol/min/mg of protein, respectively. Site-directed mutagenesis indicated that Asp-223 is an essential amino acid for the catalytic reaction and possibly functions a catalytic nucleophile, as in GH family 3 beta-glucosidases. This is the first report of the molecular cloning and characterization of a glucocerebrosidase from a procaryote. 相似文献
89.
SHIP-deficient mice are severely osteoporotic due to increased numbers of hyper-resorptive osteoclasts 总被引:16,自引:0,他引:16
Takeshita S Namba N Zhao JJ Jiang Y Genant HK Silva MJ Brodt MD Helgason CD Kalesnikoff J Rauh MJ Humphries RK Krystal G Teitelbaum SL Ross FP 《Nature medicine》2002,8(9):943-949
The hematopoietic-restricted protein Src homology 2-containing inositol-5-phosphatase (SHIP) blunts phosphatidylinositol-3-kinase-initiated signaling by dephosphorylating its major substrate, phosphatidylinositol-3,4,5-trisphosphate. As SHIP(-/-) mice contain increased numbers of osteoclast precursors, that is, macrophages, we examined bones from these animals and found that osteoclast number is increased two-fold. This increased number is due to the prolonged life span of these cells and to hypersensitivity of precursors to macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-kappa B ligand (RANKL). Similar to pagetic osteoclasts, SHIP(-/-) osteoclasts are enlarged, containing upwards of 100 nuclei, and exhibit enhanced resorptive activity. Moreover, as in Paget disease, serum levels of interleukin-6 are markedly increased in SHIP(-/-) mice. Consistent with accelerated resorptive activity, 3D trabecular volume fraction, trabecular thickness, number and connectivity density of SHIP(-/-) long bones are reduced, resulting in a 22% loss of bone-mineral density and a 49% decrease in fracture energy. Thus, SHIP negatively regulates osteoclast formation and function and the absence of this enzyme results in severe osteoporosis. 相似文献
90.
Noriyuki Hatae Kumiko Yamaoka Yukihiko Sugimoto Manabu Negishi Atsushi Ichikawa 《Biochemical and biophysical research communications》2002,290(1):162-168
We previously demonstrated that the mouse EP3beta receptor and its C-terminal tail-truncated receptor (abbreviated T-335) expressed in Chinese hamster ovary cells showed agonist-dependent and fully constitutive Gi activity in forskolin-stimulated cAMP accumulation, respectively. Here we examined the effect of the EP3beta receptor or T-335 receptor on adenylyl cyclase activity stimulated by the Gs-coupled EP2 subtype receptor in COS-7 cells. As a result, sulprostone, a selective EP3 agonist, dose dependently augmented butaprost-stimulated adenylyl cyclase activity in EP3beta receptor- or T-335 receptor-expressing COS-7 cells. However, such adenylyl cyclase augmentation was not attenuated by either pertussis toxin treatment or expression of the PH domain of rat betaARK1, which serves as a scavenger of Gbetagamma subunits, but was partially attenuated by treatment with either 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl)ester, an intracellular Ca(2+) chelator, or W-7, a calmodulin inhibitor. These findings suggest that the C-terminal tail of the EP3beta receptor is not essentially involved in activation of EP2 receptor-stimulated adenylyl cyclase in a Ca(2+)/calmodulin-dependent but Gbetagamma subunit-independent manner. 相似文献