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41.
Nagakubo D Murai T Tanaka T Usui T Matsumoto M Sekiguchi K Miyasaka M 《Journal of immunology (Baltimore, Md. : 1950)》2003,171(2):553-561
We previously reported that mac25/angiomodulin (AGM), a 30-kDa secretory protein, is abundantly expressed in high endothelial venules (HEVs), which play a crucial role in lymphocyte trafficking to the lymph nodes and Peyer's patches. We report that mac25/AGM interacts preferentially with certain molecules that are expressed in or around HEVs. In particular, mac25/AGM interacted with not only the extracellular matrix proteins and glycosaminoglycans that are expressed in most blood vessels including HEVs, but also with some chemokines that are implicated in the regulation of lymphocyte trafficking, such as the secondary lymphoid-tissue chemokine (SLC; CCL21), IFN-gamma-inducible protein 10 (IP-10; CXCL10), and RANTES (CCL5). The binding of mac25/AGM to SLC and IP-10 was dose-dependent and saturable. The binding to IP-10 could be inhibited by SLC but not by a non-mac25/AGM-binding chemokine, EBI1-ligand chemokine (ELC; CCL19). Interestingly, mac25/AGM failed to interact with 18 other chemokines, suggesting that it binds to certain chemokines preferentially. Immunohistochemical analysis indicated that mac25/AGM colocalizes at least partially with SLC and IP-10 at the basal lamina of HEVs. Upon binding with mac25/AGM, SLC and IP-10 retained all their Ca(2+)-signaling activity in vitro, suggesting that mac25/AGM can hold and present chemokines in the basal lamina of HEVs. These results imply that mac25/AGM plays a multifunctional role, serving not only as an adhesion protein to interact with glycosaminoglycans and extracellular matrix proteins but also as a molecule to present chemokines so that lymphocytes extravasating through HEVs receive further directional cues subsequent to the luminal encounter with lymphoid chemokines. 相似文献
42.
Growth of and hydrogen production by wild-type (WT) Rhodovulum sulfidophilum were compared with those by one of its mutants lacking the poly(3-hydroxybutyrate) (PHB) biosynthesis ability (PNM2). During phototrophic growth under aerobic conditions with fixed illumination, changes in the extinction coefficient and PHB content of WT and PNM2 cells revealed interference of light penetration by PHB. WT cells synthesized PHB at an early stage of the cultivation. PHB degradation after exhaustion of acetate during the cultivation of WT resulted in a decrease of the extinction coefficient. The hydrogen production rate under anaerobic conditions with fixed illumination was examined in WT and PNM2 cell suspensions at different densities. The hydrogen production rate was determined not by the light penetration but by the kinds of hydrogen donors and the density of suspension. The highest value of the rate of hydrogen production from PHB, 33.0 ml/l/h, was improved compared with 26.6 ml/l/h, which was the highest value in hydrogen production from succinate. Under the same illumination, conversion to hydrogen from PHB is more efficient than that from succinate, which is one of the best substrates for hydrogen production. These results suggest that the hydrogen production rate can be maximized in the hydrogen production system based on PHB degradation, which is achieved in high-density suspension under external-substrate-depleted conditions after aerobic cultivation in the presence of an excess amount of acetate. 相似文献
43.
The unc-52 gene of Claenorhabditis elegans encodes a homologue of the basement membrane heparan sulfate proteoglycan perlecan. Viable alleles reduce the abundance of UNC-52 in late larval stages and increase the frequency of distal tip cell (DTC) migration defects caused by mutations disrupting the UNC-6/netrin guidance system. These unc-52 alleles do not cause circumferential DTC migration defects in an otherwise wild-type genetic background. The effects of unc-52 mutations on DTC migrations are distinct from effects on myofilament organization and can be partially suppressed by mutations in several genes encoding growth factor-like molecules, including EGL-17/FGF, UNC-129/TGF-beta, DBL-1/TGF-beta, and EGL-20/WNT. We propose that UNC-52 serves dual roles in C. elegans larval development in the maintenance of muscle structure and the regulation of growth factor-like signaling pathways. 相似文献
44.
Hyaluronan oligosaccharides induce CD44 cleavage and promote cell migration in CD44-expressing tumor cells 总被引:9,自引:0,他引:9
Sugahara KN Murai T Nishinakamura H Kawashima H Saya H Miyasaka M 《The Journal of biological chemistry》2003,278(34):32259-32265
CD44 is an adhesion molecule that serves as a cell surface receptor for several extracellular matrix components, including hyaluronan (HA). The proteolytic cleavage of CD44 from the cell surface plays a critical role in the migration of tumor cells. Although this cleavage can be induced by certain stimuli such as phorbol ester and anti-CD44 antibodies in vitro, the physiological inducer of CD44 cleavage in vivo is unknown. Here, we demonstrate that HA oligosaccharides of a specific size range induce CD44 cleavage from tumor cells. Fragmented HA containing 6-mers to 14-mers enhanced CD44 cleavage dose-dependently by interacting with CD44, whereas a large polymer HA failed to enhance CD44 cleavage, although it bound to CD44. Examination using uniformly sized HA oligosaccharides revealed that HAs smaller than 36 kDa significantly enhanced CD44 cleavage. In particular, the 6.9-kDa HA (36-mers) not only enhanced CD44 cleavage but also promoted tumor cell motility, which was completely inhibited by an anti-CD44 monoclonal antibody. These results raise the possibility that small HA oligosaccharides, which are known to occur in various tumor tissues, promote tumor invasion by enhancing the tumor cell motility that may be driven by CD44 cleavage. 相似文献
45.
Diurnal changes in needle gas exchange in alpine Pinus pumila during snow-melting and summer seasons
Atsushi Ishida Takashi Nakano Seikoh Sekikawa Emiko Maruta Takehiro Masuzawa 《Ecological Research》2001,16(1):107-116
Pinus pumila (Pallas) Regel. is a dominant dwarf tree in alpine regions of Japan. The possible factors limiting the net photosynthetic rate (Pn) of the needles of P. pumila were examined in the snow-melting (May) and the summer (August) seasons. In August, in situ maximum Pn was 20 mol kg–1 needle s–1 in the current-year needles and 25 mol kg–1 needle s–1 in the 1-year-old needles. Diurnal trends of Pn in August were positively related to fluctuations in photosynthetic photon flux density (PPFD) and no midday depression of Pn was found, indicating that a decrease in PPFD rather than an increase in needle-to-air vapor pressure deficit (W) might cause the reduction of Pn. Both stomatal conductance (gs) and Pn were lower in May than in August. In May, Pn and gs were almost zero in the morning, but gradually increased with decreasing W, reaching maximum Pn values (4 mol kg–1 needle s–1) and gs (60 mmol kg–1 needle s–1) at 16.00 hours. The daytime Pn in May was positively related to gs. Relative water content in the exposed needles above the snow in May was 83%, which was far above the lethal level. This indicates that the water flow from stems or soils to needles was enough to compensate for a small amount of water loss due to the low gs in May, although the water supplied to needles would be impeded by the low temperatures. Thus, the reduced gs in May would be important for avoiding needle desiccation, and would result in a reduced Pn. 相似文献
46.
Sasano N Vesely AE Hayano J Sasano H Somogyi R Preiss D Miyasaka K Katsuya H Iscoe S Fisher JA 《American journal of physiology. Heart and circulatory physiology》2002,282(3):H973-H976
Respiratory sinus arrhythmia (RSA) may improve the efficiency of pulmonary gas exchange by matching the pulmonary blood flow to lung volume during each respiratory cycle. If so, an increased demand for pulmonary gas exchange may enhance RSA magnitude. We therefore tested the hypothesis that CO2 directly affects RSA in conscious humans even when changes in tidal volume (V(T)) and breathing frequency (F(B)), which indirectly affect RSA, are prevented. In seven healthy subjects, we adjusted end-tidal PCO2 (PET(CO2)) to 30, 40, or 50 mmHg in random order at constant V(T) and F(B). The mean amplitude of the high-frequency component of R-R interval variation was used as a quantitative assessment of RSA magnitude. RSA magnitude increased progressively with PET(CO2) (P < 0.001). Mean R-R interval did not differ at PET(CO2) of 40 and 50 mmHg but was less at 30 mmHg (P < 0.05). Because V(T) and F(B) were constant, these results support our hypothesis that increased CO2 directly increases RSA magnitude, probably via a direct effect on medullary mechanisms generating RSA. 相似文献
47.
Chihiro Kachi-TerajimaHitoshi Miyasaka Tomohiko IshiiKen-ichi Sugiura Masahiro Yamashita 《Inorganica chimica acta》2002,332(1):210-215
The ligand substitution reaction of Ru2(O2CCH3)4Cl with 2-amino-4,6-dimethylpyrimidine (Hadmpym) under gentle refluxing conditions in methanol led to the formation of a bridging-ligand mono-substituted compound, [Ru2(O2CCH3)3(admpym)(Cl)(MeOH)] (1). Compound 1 crystallized in monoclinic space group P21/n (no. 14) with a=8.3074(8) Å, b=12.3722(8) Å, c=18.913(1) Å, β=95.559(3)°, V=1934.8(3) Å3, and Z=4. Temperature dependence of the magnetic susceptibility of 1 revealed it to be in a spin ground state S=3/2 arising from the electronic configuration of σ2π4δ2(δ*π*)3. Compound 1 undergoes three metal-centered redox reactions in electrochemistry: E1/2 (ox)=+0.72 V (Ia/Ic<1, ΔEp=0.17 V); E1/2 (1,red)=−0.65 V (Ia/Ic≈1, ΔEp=0.10 V); and E1/2 (2,red)=−1.80 V (Ia/Ic?1, ΔEp=0.16 V). Then, the redox species produced by electrolysis were characterized by spectroscopic studies. 相似文献
48.
Kim CS Morisawa J Nishiyama N Kashiwagi T Tebayashi SI Horiike M 《Bioscience, biotechnology, and biochemistry》2002,66(9):1997-2000
The absolute configuration of (+)-2,7(14),10-bisabolatrien-1-ol-4-one, a peculiar sesquiterpenol in the Japanese cedar, Cryptomeria japonica, was determined as (1S,6R)-2,7(14),10-bisabolatrien-1-ol-4-one by comparing the specific rotation values of cryptomeriones respectively converted from (+)-2,7(14),10-bisabolatrien-1-ol-4-one and synthesized from (R)-(-)-carvone. 相似文献
49.
Takabe K Mase N Matsumura H Hasegawa T Iida Y Kuribayashi H Adachi K Yoda H Ao M 《Bioorganic & medicinal chemistry letters》2002,12(17):2295-2297
Lipase-catalyzed kinetic resolution of the N,N-dialkyl-3-benzyloxymethyl-4-hydroxybutanamide 10a,b afforded the acetate 11a,b with (R) configuration, whereas the N-monoalkyl-3-benzyloxymethyl-4-hydroxybutanamide 10c-e gave the acetate 11c-e with (S) configuration. The butanamide 10 smoothly cyclized to give chiral 4-benzyloxymethyldihydrofuran-2-one 9 without racemization, which was effectively transformed into highly stereocontrolled virginiae butanolide C (VB C). 相似文献
50.
Almeida AM Navet R Jarmuszkiewicz W Vercesi AE Sluse-Goffart CM Sluse FE 《Journal of bioenergetics and biomembranes》2002,34(6):487-498
Bioenergetics of tomato (Lycopersicon esculentum) development on the plant was followed from the early growing stage to senescence in wild type (climacteric) and nonripening mutant (nor, nonclimacteric) fruits. Fruit development was expressed in terms of evolution of chlorophyll a content allowing the assessment of a continuous time-course in both cultivars. Measured parameters: the cytochrome pathway-dependent respiration, i.e., the ATP synthesis-sustained respiration (energy-conserving), the uncoupling protein (UCP) activity-sustained respiration (energy-dissipating), the alternative oxidase(AOX)-mediated respiration (energy-dissipating), as well as the protein expression of UCP and AOX, and free fatty acid content exhibited different evolution patterns in the wild type and nor mutant that can be attributed to their climacteric/nonclimacteric properties, respectively. In the wild type, the climacteric respiratory burst observed in vitro depended totally on an increse in the cytochrome pathway activity sustained by ATP synthesis, while the second respiratory rise during the ripening stage was linked to a strong increase in AOX activity accompanied by an overexpression of AOX protein. In wild type mitochondria, the 10-M linoleic acid-stimulated UCP-activity-dependent respiration remained constant during the whole fruit development except in senescence where general respiratory decay was observed. 相似文献