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111.
Takahashi Kazushi; Yoshioka Takahito; Wada Eitaro; Sakamoto Mitsuru 《Journal of plankton research》1990,12(4):799-808
Temporal variations in carbon isotope ratio of phytoplanktonand dissolved inorganic carbon (DIC) in Lake Suwa were reported.In summer, blooming of Microcystis spp. resulted in low concentrationsof DIC and high pH, and HCO3 was the prominent speciesof DIC. Chlorophyll-specific rates of photosynthesis were relativelyconstant irrespective of the algal biomass during summer. Carboxylationin photosynthesis of Microcystis spp. was mainly catalyzed byribulose bisphosphate carboxylase (RuBPCase). Carbon isotopediscrimination between 13C of phytoplankton and DIC was considerablysmall in early summer and appeared to be negatively correlatedto DIC concentration. We concluded that carbon fixation by phytoplanktonin Lake Suwa is controlled not by the switch of photosyntheticpathways, but by low DIC concentration and high pH, suggestingthat photosynthesis of Microcystis spp. in Lake Suwa is governedby uptake kinetics other than the carboxylation step. 相似文献
112.
113.
Inoue A Kang M Fujimura L Takamori Y Sasagawa K Itoh H Tokuhisa T Hatano M 《DNA and cell biology》2005,24(1):30-34
The murine Nd1 gene encodes two forms of protein, Nd1-L and Nd1-S, both of which share the BTB/POZ domain, but Nd1-S lacks the kelch repeats. Although Nd1-L ubiquitously expresses, localizes in the cytoplasm and functions as a stabilizer of actin filaments, expression and function of Nd1-S were unknown. Here we show that Nd1-S were expressed in all tissues examined and localized in the nucleus as a speckled-like pattern. Furthermore, overexpression of Nd1-S perturbed cell growth of NIH3T3 cells at the G1/S phase of the cell cycle. These results suggest that Nd1-S may play a role in cell cycle progression in the nucleus. 相似文献
114.
Arita S Ando S Hosoda H Sakaue K Nagata T Murata Y Shimoishi Y Tada M 《Bioscience, biotechnology, and biochemistry》2005,69(9):1786-1789
The photodegradation of carotenoids by UVA irradiation in the presence of sulfides was investigated. The sulfides accelerated the photodegradation of carotenoids. A larger number of sulfur atoms of coexistent sulfides was more favorable to the acceleration effect of sulfides on the photodegradation of beta-carotene, but the alk(en)yl group of sulfides was less favorable to the acceleration effect of sulfur compounds. The acceleration effect depended on light intensity, temperature, and the initial concentrations of beta-carotene and sulfide. 相似文献
115.
Sugahara T Onda H Shinohara Y Horii M Akiyama K Nakamoto K Hara K 《Biochimica et biophysica acta》2005,1725(2):233-240
Fat-free bovine milk fermented by 12 kinds of lactic acid bacteria and yeast enhanced monoclonal antibody production of human hybridoma HB4C5 cells 2.8-fold in serum-free medium. Immunoglobulin production of human peripheral blood lymphocytes (PBL) was also stimulated in vitro. IgM and IgG production of human PBL was accelerated up to 2.8-fold and 5.4-fold, respectively. Interferon-gamma production of human PBL was also accelerated 6.0-fold by 50 microg/ml of the fermented milk. However, interleukin-4 production of PBL was not affected, and tumor necrosis factor-alpha production was suppressed. The activity was enhanced 2.5-fold by the thermal treatment for 30 min at 65 degrees C and was completely lost by trypsin digestion. The findings suggested that the active substance in the fermented milk was heat stable protein. Gel-filtration and the SDS-PAGE analysis revealed that the molecular weight of the active substance was estimated as 19.0 kDa, which was not detected in fat-free bovine milk before fermentation. N-terminal amino acid sequence of the 19.0 kDa protein was highly homologous to proteose-peptone component 3 (PP3). Since molecular weight of PP3 is 28 kDa, it is suggested that the 19.0 kDa protein is derived from degradation of PP3 during fermentation of fat-free milk. Moreover, PP3 purified from fat-free milk also enhanced IgM production of HB4C5 cells. 相似文献
116.
XRCC3 deficiency results in a defect in recombination and increased endoreduplication in human cells 总被引:1,自引:0,他引:1
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Yoshihara T Ishida M Kinomura A Katsura M Tsuruga T Tashiro S Asahara T Miyagawa K 《The EMBO journal》2004,23(3):670-680
XRCC3 was inactivated in human cells by gene targeting. Consistent with its role in homologous recombination, XRCC3(-/-) cells showed a two-fold sensitivity to DNA cross-linking agents, a mild reduction in sister chromatid exchange, impaired Rad51 focus formation and elevated chromosome aberrations. Furthermore, endoreduplication was increased five- seven-fold in the mutants. The T241M variant of XRCC3 has been associated with an increased cancer risk. Expression of the wild-type cDNA restored this phenotype, while expression of the variant restored the defective recombinational repair, but not the increased endoreduplication. RPA, a protein essential for homologous recombination and DNA replication, is associated with XRCC3 and Rad52. Overexpression of RPA promoted endoreduplication, which was partially complemented by overexpression of the wild-type XRCC3 protein, but not by overexpression of the variant protein. Overexpression of Rad52 prevented endoreduplication in RPA-overexpressing cells, in XRCC3(-/-) cells and in the variant-expressing cells, suggesting that deregulated RPA was responsible for the increased endoreduplication. These observations offer the first genetic evidence for the association between homologous recombination and replication initiation having a role in cancer susceptibility. 相似文献
117.
Okamoto R Ito M Suzuki N Kongo M Moriki N Saito H Tsumura H Imanaka-Yoshida K Kimura K Mizoguchi A Hartshorne DJ Nakano T 《Transgenic research》2005,14(3):337-340
Myosin phosphatase (MP) is a major phosphatase responsible for the dephosphorylation of the regulatory light chain of myosin II. MYPT1, a target subunit of smooth and nonmuscle MP, is responsible for activation and regulation of MP. To identity the physiological roles of MP, we have generated MYPT1-deficient mice by gene targeting. The heterozygous mice showed no changes in expression levels of MYPT1 and no distinct phenotype compared to wild-type mice was observed. None of the F2 mice were homozygous for the MYPT1 deletion, indicating that the targeted disruption of the MYPT1 gene resulted in embryonic lethality. The point of embryonic lethality is before 7.5 dpc. These findings indicate that MYPT1 is essential for mouse embryogenesis. 相似文献
118.
Murakoshi K 《Bio Systems》2005,80(1):37-40
Overfitting in multilayer perceptron (MLP) training is a serious problem. The purpose of this study is to avoid overfitting in on-line learning. To overcome the overfitting problem, we have investigated feeling-of-knowing (FOK) using self-organizing maps (SOMs). We propose MLPs with FOK using the SOMs method to overcome the overfitting problem. In this method, the learning process advances according to the degree of FOK calculated using SOMs. The mean square error obtained for the test set using the proposed method is significantly less than that in a conventional MLP method. Consequently, the proposed method avoids overfitting. 相似文献
119.
Hitoshi Okada Hideaki Kawaguchi Toshiyuki Kudo Hirofumi Sawa Hiroshi Okamoto Shouzi Watanabe Kazushi Urasawa Takeshi Murakami Akira Kitabatake 《Molecular and cellular biochemistry》1996,156(1):9-15
The purpose of this study was to characterize the collagen in hereditary dilated cardiomyopathic hamster hearts, and to examine the participation of the collagen in the occurrence and progression of cardiomyopathy.BIO 53.58 hamsters (5, 10, 20 weeks old) were used as the model of dilated cardiomyopathy. Flb hamsters were used as controls. The collagen content was almost constant at any age in the Flb hamsters, but increased with age in BIO 53.58 hamsters. Type III collagen increased significantly in BIO 53.58 hamsters at 10 weeks. The acetic acid solubility of collagen decreased in BIO 53.58 hamsters as the fibrosis progressed, but was unchanged in controls. Reducible crosslinks showed a tendency to decrease progressively in BIO 53.58 hamsters. There were no differences between Flb and BIO 53.58 hamsters at 5 weeks, but its expression in BIO 53.58 hamsters at 10 and 20 weeks of age increased compared to Flb controls.These findings indicate that in the early phase of cardiomyopathy the extracellular matrix of the myocardium is rich in type III collagen. In the later phase, the matrix resembles that of hard tissues, whose collagen is mainly of type I collagen and is insoluble. These data suggest that the increased collagen synthesis may impair the cardiac function in the development of cardiomyopathy. 相似文献
120.
2,3,5,6-Tetrabromohydroquinone was isolated as a luminous substance from Ptychodera flava. This compound emitted light after addition of hydrogen peroxide under basic conditions. Since hydroquinone had no fluorescence, further investigation by spectral analysis revealed that riboflavin was the only possible light emitter having green fluorescence. In the presence of both tetrabromohydroquinone and riboflavin under a basic condition containing 70% 1,4-dioxane, green light emission was observed following the addition of hydrogen peroxide. We succeeded in recording the same emission spectrum as that in the bioluminescence caused by the addition of aqueous diluted hydrogen peroxide solution in P. flava. 相似文献