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Intra‐trophic isotopic discrimination of 15N/14N for amino acids in autotrophs: Implications for nitrogen dynamics in ecological studies 下载免费PDF全文
Yuko Takizawa Prarthana S. Dharampal Shawn A. Steffan Yoshinori Takano Naohiko Ohkouchi Yoshito Chikaraishi 《Ecology and evolution》2017,7(9):2916-2924
The differential discrimination of nitrogen isotopes (15N/14N) within amino acids in consumers and their diets has been routinely used to estimate organismal tropic position (TP). Analogous isotopic discrimination can occur within plants, particularly in organs lacking chloroplasts. Such discrimination likely arises from the catabolic deamination of amino acids, resulting in a numerical elevation of estimated TP, within newly synthesized biomass. To investigate this phenomenon, we examined the 15N/14N of amino acids (δ15NAA) in spring leaves and flowers from eight deciduous and two annual plants. These plants were classified on the basis of their time of bloom, plants that bloomed when their leaves were absent (Type I) versus plants that bloomed while leaves were already present (Type II). Based on the δ15NAA values from leaves, both plant types occupied comparable and ecologically realistic mean TPs (=1.0 ± 0.1, mean ± 1σ). However, the estimated TPs of flowers varied significantly (Type I: 2.2 ± 0.2; Type II: 1.0 ± 0.1). We hypothesize that these results can be interpreted by the following sequence of events: (1) Type I floral biomass is synthesized in absence of active photosynthesis; (2) the catabolic deamination of amino acids in particular, leaves behind 15N in the residual pool of amino acids; and (3) the incorporation of these 15N‐enriched amino acids within the biomass of Type I flowers results in the numerical elevation of the TPs. In contrast, the actively photosynthesizing Type II leaves energetically sustain the synthesis of Type II flower biomass, precluding any reliance on catabolic deamination of amino acids. Amino acids within Type II flowers are therefore isotopically comparable to the Type II leaves. These findings demonstrate the idiosyncratic nature of the δ15NAA values within autotrophic organs and have implications for interpreting trophic hierarchies using primary producers and their consumers. 相似文献
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Makiko Suto Hidekazu Tanaka Yasuhide Mochizuki Jun Mukai Hiroki Takada Fumitaka Soga Kumiko Dokuni Yutaka Hatani Keiko Hatazawa Hiroki Matsuzoe Hiroyuki Sano Hiroyuki Shimoura Junichi Ooka Kensuke Matsumoto Yushi Hirota Wataru Ogawa Ken-ichi Hirata 《Cardiovascular diabetology》2017,16(1):145
Background
Coexistence of left ventricular (LV) longitudinal myocardial systolic dysfunction with LV diastolic dysfunction could lead to heart failure with preserved ejection fraction (HFpEF). Diabetes mellitus (DM) is known as a significant factor associated with HFpEF. Although the mechanisms of DM-related LV myocardial injury are complex, it has been postulated that overweight contributes to the development of LV myocardial injury in type 2 diabetes mellitus (T2DM) patients. However, the precise impact of overweight on LV longitudinal myocardial systolic function in T2DM patients remains unclear.Methods
We studied 145 asymptomatic T2DM patients with preserved LV ejection fraction (LVEF) without coronary artery disease. LV longitudinal myocardial systolic function was assessed by global longitudinal strain (GLS), which was defined as the average peak strain of 18-segments obtained from standard apical views. Overweight was defined as body mass index (BMI) ≥ 25 kg/m2. Ninety age-, gender- and LVEF-matched healthy volunteers served as controls.Results
GLS of overweight T2DM patients was significantly lower than that of non-overweight patients (17.9 ± 2.4% vs. 18.9 ± 2.6%, p < 0.05), whereas GLS of both overweight and non-overweight controls was similar (19.8 ± 1.3% vs. 20.4 ± 2.1%, p = 0.38). Furthermore, multiple regression analysis revealed that for T2DM patients, BMI was the independent determinant parameters for GLS as well as LV mass index.Conclusions
Overweight has a greater effect on LV longitudinal myocardial systolic function in T2DM patients than on that in non-DM healthy subjects. Our finding further suggests that the strict control of overweight in T2DM patients may be associated with prevention of the development of HFpEF.4.
Masaru Kubota Ying-Wei Lin Keigo Hamahata Machiko Sawada Seiji Koishi Haruyo Hirota Yoshihiro Wakazono 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2000,470(2):21
The occurrence of a second neoplasm is one of the major obstacles in cancer chemotherapy. The elucidation of the genotoxic effects induced by anti-cancer drugs is considered to be helpful in identifying the degree of cancer risk. Numerous investigations on cancer patients after chemotherapy have demonstrated: (i) an increase in the in vivo somatic cell mutant frequency (Mf) at three genetic loci, including hypoxanthine–guanine phosphoribosyl-transferase (hprt), glycophorin A (GPA), and the T-cell receptor (TCR), and (ii) alterations in the mutational spectra of hprt mutants. However, the time required for and the degree of such changes are quite variable among patients even if they have received the same chemotherapy, suggesting the existence of underlying genetic factor(s). Accordingly, some cancer patients prior to chemotherapy as well as patients with cancer-prone syndrome have been found to show an elevated Mf. Based on the information obtained from somatic cell mutation assays, an individualized chemotherapy should be considered in order to minimize the risk of a second neoplasm. 相似文献
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Y Niho N Kimura Y Yamano Y Yamamoto Y Hirota J Ono R Takaki 《International journal of cell cloning》1985,3(1):22-32
Erythroid-potentiating activity (EPA) was detected in culture medium conditioned by a human cancer cell line (KONT) that produces colony-stimulating activity (CSA), using erythroid colony formation in vitro. EPA in the medium conditioned by the KONT cells (KONT-CM) was markedly heat stable. After treating KONT-CM at 80 degrees C for 30 min, 30% EPA remained, while CSA was completely inactivated. Both EPA and CSA appeared in approximately the same fractions of the gel filtration, indicating a molecular weight of approximately 30,000 daltons. EPA bound partially to Concanavalin-A Sepharose, whereas CSA almost did not bind. Our results indicate that EPA can be separated from CSA based on heat stability and binding to Concanavalin-A Sepharose. 相似文献
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Function of phospholipids in Escherichia coli. Characterization of a mutant deficient in cardiolipin synthesis. 总被引:6,自引:0,他引:6
Screening of a collection of temperature-sensitive mutants of Escherichia coli for defects in phospholipid metabolism led to the isolation of a mutant deficient in cardiolipin synthesis. The defective gene, named cls, is closely linked to the trp marker and maps at about Minute 27 on the E. coli chromosome. After transfer of cls to a defined genetic background by transduction, the mutant has the following properties as compared to an isogenic wild type. Exponentially growing cells show a reduction in cardiolipin content by a factor of at least 15 (less than 0.2 mol % of the total phospholipids). A crude membrane fraction derived from the mutant is unable to synthesize cardiolipin from phosphatidylglycerol in vitro. The mutant has no distinctive phenotype regarding its growth properties, membrane-associated respiratory functions, or the ability to insert bacteriophage M13 coat protein into the cell envelope. The cls mutation confers a 5-times reduction in the turnover of the phosphate moiety of phosphatidylglycerol. 相似文献
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Masahira Nakagawa Heiichi Sakai Akira Isogai Akira Hirota 《Bioscience, biotechnology, and biochemistry》2013,77(9):2279-2283
Four neutral sesquiterpenes were isolated from the culture filtrate of of Aspergillus terreus THOM NO. 14 which produces two sesquiterpene antibiotics, terrecyclic acid A and terrecyclol. On the basis of spectroscopic data the structures of four neutral sesquiterpenes were elucidated. One of these is quadrone, a known antitumor substance, but isoquadrone, 8-hydroxyquadrone and 6-hydroxyisoquadrone are new sesquiterpenes. Although terrecyclic acid A exhibits antimicrobial and antitumor activities, these four scarcely show these activities. 相似文献