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21.
Stable carbon isotope composition (δ13C), net photosynthetic rate (P
N), actual quantum yield of photosystem 2 (PS2) electron transport (ΦPS2), nitrogen content (Nc), and photosynthetic nitrogen use efficiency (PNUE) in the leaves of six broadleaf tree species were determined under field
environmental conditions. The six tree species were Magnolia liliflora Desr., M. grandiflora Linn., M. denudata Desr., Prunus mume (Sieb.) Sieb. et Zucc. cv. Meiren Men, P. mume (Sieb.) Sieb. et Zucc. f. alphandii (Carr.) Rehd., and P. persica (L.) Batsch. var. rubro-plena. The relationships among δ13C, ΦPS2, P
N, and PNUE, as well as their responses to Nc in the six species were also studied. Both P
N and δ13C negatively correlated with Nc, but ΦPS2 positively correlated with Nc. This indicated that with Nc increase, P
N and δ13C decreased, while ΦPS2 increased. There were weak negative correlations between δ13C and PNUE, and strong negative correlations (p<0.01) between ΦPS2 and PNUE. According to the variance analysis of parameters, there existed significant interspecific differences (p<0.001) of δ13C, P
N, ΦPS2, PNUE, and Nc among the tree seedlings of the six tree species, which suggests that the potential photosynthetic capacities depend on plant
species, irradiance, and water use capacity under field conditions. 相似文献
22.
J Xiong W Zhang J Su J Shangguan Y Lin Y Yang R Zhang L Xie H Wang 《World journal of microbiology & biotechnology》2012,28(2):721-727
Nucleoside analogues are used widely for the treatment of viral diseases and cancer, however the preparation of some important
intermediates of these nucleoside analogues, including 2′-deoxyadenosine (dAR) and 5-methyluridine (5-MU), remains inconvenient.
To optimize the synthesis of dAR and 5-MU, recombinant strains and auto-induction medium were employed in this study. E. coli
BL21(DE3) strains overexpressing purine nucleoside phosphorylase (PNP), uridine phosphorylase (UP) and thymidine phosphorylase
(TP) were constructed and cultured in auto-induction ZYM-Fe-5052 medium for 8 h. The cultures of these strains were then used
directly to synthesize dAR and 5-MU. Under optimized conditions, 30 mM adenine was converted to 29 mM dAR in 1 h, and 32 mM
5-MU was obtained from 60 mM thymine, using 6% (v/v) cell solutions as biocatalysts. These results indicate that our convenient
and efficient method is ideal for the preparation of dAR and 5-MU, and has potential for the preparation of other nucleoside
analogue intermediates. 相似文献
23.
Genetic control of seed shattering in rice by the APETALA2 transcription factor shattering abortion1 总被引:3,自引:0,他引:3
24.
25.
Spatial patterns of leaf nutrient traits of the plants in the Loess Plateau of China 总被引:4,自引:0,他引:4
The spatial patterns of leaf nutrient traits of plants in seven sites, Yangling, Yongshou, Tongchuan, Fuxian, Ansai, Mizhi
and Shenmu, standing from south to north in the Loess Plateau of China, were studied. The results showed that of the 126 plant
samples in the Loess Plateau, the mean leaf organic carbon (C), nitrogen (N), phosphorus (P) and potassium (K) were 43.8,
2.41, 0.16 and 1.67%, respectively, and ranked in the order of C > N > K > P. Leaf C, N, P and K ranged from 32.6 to 54.8%,
0.82 to 4.58%, 0.06 to 0.35%, and 0.24 to 4.21%, respectively. The mean leaf C/N, C/P and N/P ratios were 21.2, 312 and 15.4,
respectively. It is indicated that leaf N in the Loess Plateau was significantly higher than those in Chinese and global flora,
but leaf P was significantly lower than that in global flora, which resulted in a higher N/P ratio in the Loess Plateau. The
results also showed that leaf C, N, P, K, C/N and C/P ratios varied significantly among the seven life-form groups, which
were trees, shrubs, herbages, evergreen trees, deciduous trees, C3 and C4 herbages, but leaf N/P ratio differed little among the seven life-forms. In the sampled species in the Loess Plateau, leaf
C was negatively correlated with leaf N, P and K, while leaf N, P and K were positively correlated with one another. In general,
leaf N/P ratio increased as the latitude and annual solar radiation increased and the mean annual rainfall and mean annual
temperature decreased. 相似文献
26.
27.
Xiaohong Cheng Xiangjun Liu Tao Bing Rui Zhao Shaoxiang Xiong Dihua Shangguan 《Biopolymers》2009,91(10):874-883
A significant number of G‐quadruplex‐forming sequences have been revealed in human genome by bioinformatic searches, implying that G‐quadruplexes may be involved in important biological processes and may be new chemotherapeutic targets. Therefore, it is important to discover the potential interactions of G‐quadruplexes with other molecules or groups. Here we describe a class of G‐quadruplexes, which can bind to ethanolamine groups that widely exist in biomolecules and drug molecules. The specific interaction of these G‐quadruplexes with ethanolamine groups was identified by high performance affinity chromatography (HPAC) using immobilized ethanolamine and diethanolamine as stationary phase reagents. The circular dichroism (CD) spectra and native polyacrylamide gel electrophoresis (PAGE) show that these ethanolamine binding quadruplexes adopt an intramolecularly parallel structure. The relationship of ethanolamine binding and G‐quadruplexe structure provides new clues for the G‐quadruplex‐related studies as well as for the molecular designs of therapeutic reagents. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 874–883, 2009. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com 相似文献
28.
29.
Juan Song Lei Gou Qing-Ran Wu Xiao-Le Yang Yi-Qing Shangguan Fa-Xin Dong Gang-Lin Xue 《Inorganica chimica acta》2011,366(1):134-6870
Two novel Zn(II) coordination polymers, [Zn(2-pytpy)(fum)]n·nH2O (1) and [Zn6(4-pytpy)3(mal)4]n·5n(H2O) (2), (2-pytpy = 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine, 4-pytpy = 4′-(4-pyridyl)-4,2′:6′,4″-terpyridine, H2fum = fumaric acid and H2mal = malic acid) have been hydrothermally synthesized and structurally characterized. Notably, in situ ligand reactions occur in the formation of complexes 1 and 2, in which maleic acid is converted into fumaric acid and malic acid, respectively. Complex 1 is a 1D infinite chain structure, which is extended into a supramolecular layer by intermolecular π…π stacking interactions. Complex 2 is a 3D network structure, in which the bidentate-bridging 4-pytpy ligands link the layers based on the tetranuclear Zn(II) subunits to form the (4,10)-connected network. The luminescent properties of 1 and 2 have been investigated with emission spectra and UV-Vis diffuse reflectance spectra in the solid state. Additionally, these two complexes possess great thermal stabilities. 相似文献
30.