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51.
Morphological and physiological responses of rice seedlings to complete submergence (flash flooding) 总被引:2,自引:0,他引:2
Background and Aims
Reducing damage to rice seedlings caused by flash flooding will improve the productivity of rainfed lowland rice in West Africa. Accordingly, the morphological and physiological responses of different forms of rice to complete submergence were examined in field and pot experiments to identify primary causes of damage.Methods
To characterize the physiological responses, seedlings from a wide genetic base including Oryza sativa, O. glaberrima and interspecific hybrids were compared using principle component analysis.Key Results
Important factors linked to flash-flood tolerance included minimal shoot elongation underwater, increase in dry matter weight during submergence and post-submergence resistance to lodging. In particular, fast shoot elongation during submergence negatively affected plant growth after de-submergence. Also shoot-elongating cultivars showed a strong negative correlation between dry matter weight of the leaves that developed before submergence and leaves developing during submergence.Conclusions
Enhancement of shoot elongation during submergence in water that is too deep to permit re-emergence by small seedlings represents a futile escape strategy that takes place at the expense of existing dry matter in circumstances where underwater photosynthetic carbon fixation is negligible. Consequently, it compromises survival or recovery growth once flood water levels recede and plants are re-exposed to the aerial environment. Tolerance is greater in cultivars where acceleration of elongation caused by submergence is minimal.Key words: Africa, flash floods, Oryza glaberrima, rainfed lowland, rice, shoot elongation, stress tolerance, submergence 相似文献52.
Ikeda K Sato K Kitani S Suzuki T Maki N Suzuki Y Sato M 《Bioorganic & medicinal chemistry》2006,14(23):7893-7897
To explore the influence of binding to human parainfluenza virus type 1 (hPIV-1), a series of 4-O-substituted Neu5Ac2en derivatives 6a-e was synthesized and tested for their ability to inhibit hPIV-1 sialidase. Among compounds 6a-e, the 4-O-ethyl-Neu5Ac2en derivative 6b showed the most potent inhibitory activity (IC50 6.3 microM) against hPIV-1 sialidase. 相似文献
53.
Risa Nakamura Naoyoshi Maeda Kensuke Shibata Hisakata Yamada Tetsuo Kase Yasunobu Yoshikai 《Journal of virology》2010,84(11):5574-5582
Highly pathogenic influenza A viruses cause acute severe pneumonia to which the occurrence of “cytokine storm” has been proposed to contribute. Here we show that interleukin-15 (IL-15) knockout (KO) mice exhibited reduced mortality after infection with influenza virus A/FM/1/47 (H1N1, a mouse-adapted strain) albeit the viral titers of these mice showed no difference from those of control mice. There were significantly fewer antigen-specific CD44+ CD8+ T cells in the lungs of infected IL-15 KO mice, and adoptive transfer of the CD8+ T cells caused reduced survival of IL-15 KO mice following influenza virus infection. Mice deficient in β2-microglobulin by gene targeting and those depleted of CD8+ T cells by in vivo administration of anti-CD8 monoclonal antibody displayed a reduced mortality rate after infection. These results indicate that IL-15-dependent CD8+ T cells are at least partly responsible for the pathogenesis of acute pneumonia caused by influenza A virus.Highly pathogenic influenza A viruses cause acute severe pneumonia that results in high morbidity and significant mortality (11, 12, 24, 26). Elevated levels of serum cytokines and chemokines accompany these clinical manifestations, and the possibility that this “cytokine storm” contributes to increased severity of the disease caused by avian H5N1 virus and by other strains of influenza A virus has been proposed (10, 21, 33). In fact, CCR2-deficient mice [CCR2 is chemokine (C-C motif) receptor 2] were protected from early pathological manifestations despite higher pulmonary titers of the influenza virus A/PR/8/34 (H1N1) strain (7). Tumor necrosis factor receptor 1 (TNFR-1)-deficient mice exhibited significantly reduced morbidity following challenge with H5N1 virus (31). Other cytokines or chemokines have also been investigated (8, 28, 34, 35, 38). Thus, at least some of the elevated proinflammatory cytokines may contribute to the pathogenesis of influenza A virus.Interleukin-15 (IL-15) is a pleiotropic cytokine involved in both innate and adaptive immune responses (20, 36). IL-15 utilizes the β-chain of the IL-2 receptor (IL-2R) (CD122) and the common cytokine receptor γ-chain (CD132) for signal transduction in lymphocytes and therefore shares many biological properties with IL-2 (3). Memory CD8+ T cells, natural killer (NK) cells, NKT cells, and intraepithelial lymphocyte (IEL) T cells (15, 23, 42) decrease in mice with defective IL-15 signaling, indicating the importance of IL-15 in their development and/or maintenance. IL-15 regulates not only the number of memory CD8+ T cells but also activation of their functions, including gamma interferon (IFN-γ) production and cytotoxic activity (40), which are important to target the virus (9). Therefore, it is possible that we may be able to use IL-15 as an immune-enhancing molecular adjuvant in vaccines for protection against various pathogens, including influenza A virus (37).In the present study, we demonstrate that IL-15 knockout (KO) mice exhibited high resistance against infection with mouse-adapted influenza virus A/FM/1/47 (H1N1) strain. We show for the first time that IL-15-dependent CD8+ T cells are at least partly responsible for the pathogenesis of acute pneumonia caused by influenza A virus. In addition, our observations are important in the light of recent research into the use of IL-15 as an adjuvant for vaccination. 相似文献
54.
Florian A. Busch Jun Tominaga Masato Muroya Norihiko Shirakami Shunichi Takahashi Wataru Yamori Takuya Kitaoka Sara E. Milward Kohji Nishimura Erika Matsunami Yosuke Toda Chikako Higuchi Atsuko Muranaka Tsuneaki Takami Shunsuke Watanabe Toshinori Kinoshita Wataru Sakamoto Atsushi Sakamoto Hiroshi Shimada 《The Plant journal : for cell and molecular biology》2020,102(1):129-137
Bundle Sheath Defective 2, BSD2, is a stroma‐targeted protein initially identified as a factor required for the biogenesis of ribulose 1,5‐bisphosphate carboxylase/oxygenase (RuBisCO) in maize. Plants and algae universally have a homologous gene for BSD2 and its deficiency causes a RuBisCO‐less phenotype. As RuBisCO can be the rate‐limiting step in CO2 assimilation, the overexpression of BSD2 might improve photosynthesis and productivity through the accumulation of RuBisCO. To examine this hypothesis, we produced BSD2 overexpression lines in Arabidopsis. Compared with wild type, the BSD2 overexpression lines BSD2ox‐2 and BSD2ox‐3 expressed 4.8‐fold and 8.8‐fold higher BSD2 mRNA, respectively, whereas the empty‐vector (EV) harbouring plants had a comparable expression level. The overexpression lines showed a significantly higher CO2 assimilation rate per available CO2 and productivity than EV plants. The maximum carboxylation rate per total catalytic site was accelerated in the overexpression lines, while the number of total catalytic sites and RuBisCO content were unaffected. We then isolated recombinant BSD2 (rBSD2) from E. coli and found that rBSD2 reduces disulfide bonds using reductants present in vivo, for example glutathione, and that rBSD2 has the ability to reactivate RuBisCO that has been inactivated by oxidants. Furthermore, 15% of RuBisCO freshly isolated from leaves of EV was oxidatively inactivated, as compared with 0% in BSD2‐overexpression lines, suggesting that the overexpression of BSD2 maintains RuBisCO to be in the reduced active form in vivo. Our results demonstrated that the overexpression of BSD2 improves photosynthetic efficiency in Arabidopsis and we conclude that it is involved in mediating RuBisCO activation. 相似文献
55.
So Nishimura Naoyoshi Nagata Takuro Shimbo Naoki Asayama Junichi Akiyama Norio Ohmagari Hirohisa Yazaki Shinichi Oka Naomi Uemura 《PloS one》2013,8(3)
Background
Candidia esophagitis (CE) is an AIDS-defining condition, usually occurring in individuals with low CD4 counts of <200 cells/µL. Endoscopy is a valuable definitive diagnostic method for CE but may not be indicated for asymptomatic patients or for those with high CD4 counts or without oral candidiasis. This study assessed such patients to clarify the factors associated with CE and its severity on endoscopy in the highly active antiretroviral therapy (HAART) era.Methodology/ Principal Findings
A total of 733 HIV-infected patients who underwent upper gastrointestinal (GI) endoscopy were analyzed. Sexual behavior, CD4+ count, HIV-RNA viral load (VL), history of HAART, GI symptoms, GI diseases, and oral candidiasis were assessed. Endoscopic severity of CE was classified as mild (Kodsi''s grade I/II) or severe (grade III/IV). Of the 733 subjects, 62 (8.46%) were diagnosed with CE (mild, n = 33; severe, n = 29). Of them, 56.5% (35/62) had no GI symptoms, 30.6% (19/62) had CD4 + ≥200 cells/μL, and 55.3% (21/38) had no oral candidiasis. Univariate analysis found lower CD4+ counts, higher HIV VL, and no history of HAART to be significantly associated with CE. With lower CD4+ counts and higher HIV VL, CE occurrence increased significantly (P<0.01 for trend in odds). Multivariate analysis showed low CD4+ counts and high HIV VL to be independently associated with CE. Of the severe CE patients, 55.2% (16/29) had no GI symptoms and 44.4% (8/18) had no oral candidiasis. Median CD4+ counts in severe cases were significantly lower than in mild cases (27 vs. 80; P = 0.04).Conclusions
Low CD4+ counts and high HIV VL were found to be factors associated with CE, and advanced immunosuppression was associated with the development of severity. Endoscopy is useful as it can detect CE, even severe CE, in patients without GI symptoms, those with high CD4 counts, and those without oral candidiasis. 相似文献56.
Mamoru Sugiura Masakazu Isobe Noriyuki Muroya Tsutomu Yamaguchi 《Bioscience, biotechnology, and biochemistry》2013,77(5):947-952
A lipase with a high molecular weight was purified from Chromobacterium viscosum by chromatography using the Amberlite CG–50 and Sephadex G–75. The purified lipase (Lipase A) was found to be homogeneous by disc electrophoresis.Lipase A had an optimum pH around 7 for lipolysis of olive oil and the enzyme was stable at the range of pH 4 to 9 and below 50°C. Zn2+, Cu2+, Fe3+ and high concentrations of l-cysteine, iodoacetic acid and NBS had remarkable inhibitory effects. Bile salts were activator. Lipase A was more active on water insoluble esters than water soluble esters. The isoelectric point of the enzyme was pH 4.7. 相似文献
57.
Haiying Fu Mingzhang Lin Yusa Muroya Kuniki Hata Yosuke Katsumura Akinari Yokoya 《Free radical research》2013,47(9):887-897
Silybin (extracted from Silybum marianum) is the major active constituent of silymarin which possesses a wide range of medicinal properties. These properties may be, in part, due to the potent scavenging capacity of oxidizing free radicals. In this context, scavenging radicals (hydroxyl, azide, dibromide anion radicals, nitrite, carbonate, etc.) of silybin have been studied to understand the mechanistic aspects of its action against free radicals. The transients produced in these reactions have been assigned and the rate constants have been measured by pulse radiolysis techniques. Reduction potential determined both by cyclic voltammetry gave a value 0.62±0.02 V vs NHE at pH 9. Quantum chemical calculations have been performed to further confirm the different activities of individual hydroxyl groups with the difference of heat of formation. Moreover, silybin also protected plasmid pUC18 DNA from soft X-ray radiation which induced strand breaks. These results are expected to be helpful for a better understanding of the anti-oxidative properties of silybin. 相似文献
58.
Naoyoshi Nagata Takuro Shimbo Hirohisa Yazaki Naoki Asayama Junichi Akiyama Katsuji Teruya Toru Igari Norio Ohmagari Shinichi Oka Naomi Uemura 《PloS one》2012,7(11)
Background
The diagnosis of gastrointestinal (GI) involvement in Kaposi''s sarcoma (KS) is important to make because the need for treatment depends on the extent of the disease. Moreover, severe GI lesions can cause serious complications. Endoscopy with biopsy is an extremely useful method to diagnose GI-KS. However, determining the indications for endoscopy is difficult because KS can occur without GI symptoms or cutaneous KS. This study sought to clarify predictive clinical factors for GI-KS and its severity on endoscopy.Methodology/Principal Findings
A total of 1,027 HIV-infected patients who underwent endoscopy were analyzed. Sexual behavior, CD4 count, HIV RNA, history of highly active antiretroviral therapy (HAART), GI symptoms, and cutaneous KS were assessed. Endoscopic severity including bulky tumor, ulceration, and number of lesions were evaluated. Thirty-three patients had GI-KS and 46 patients cutaneous KS. Among the GI-KS patients, 78.8% (26/33) had no GI symptoms and 24.2% (8/33) had no cutaneous KS. Univariate analysis identified men who have sex with men (MSM), CD4 <100 cells/µL, HIV RNA ≥10,000 copies/mL, no history of HAART, and cutaneous KS were significantly associated with GI-KS. Among these factors, cutaneous KS was closely related to GI-KS on multivariable analysis. Among patients without cutaneous KS, MSM and CD4 count <100 cells/µL were the only independent clinical factors related to GI-KS. Bulky tumor was significantly associated with CD4 <100 cells/µL and large number of lesions was significantly associated with HIV-RNA ≥10,000 copies/mL.Conclusions
To diagnose GI-KS, clinical factors need to be considered before endoscopy. The presence of GI symptoms is not useful in predicting GI-KS. MSM and CD4 count <100 cells/µL are predictive factors among patients without cutaneous KS. Caution should be exercised especially in patients with low CD4 counts or high HIV viral loads as they are more likely to develop severe GI-KS lesions. 相似文献59.
Xian-Yang Qin Hideko Sone Yoshiyuki Kojima Kentaro Mizuno Katsuhiko Ueoka Koji Muroya Mami Miyado Aya Hisada Hiroko Zaha Tomokazu Fukuda Jun Yoshinaga Junzo Yonemoto Kenjiro Kohri Yutaro Hayashi Maki Fukami Tsutomu Ogata 《PloS one》2012,7(12)