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1.
Sci Rep ; 4: 3763, 2014 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-24441731

RESUMO

Atmospheric nitrogen (N) deposition, an important component in the global N cycle, has increased sharply in recent decades in China. Here, we constructed national-scale inorganic N wet deposition (Ndep) patterns in China based on data from 280 observational sites and analysed the effects of anthropogenic sources and precipitation on Ndep. Our results showed that the mean Ndep over China increased approximately 25%, from 11.11 kg ha(-1) a(-1) in the 1990s to 13.87 in the 2000s. Ndep was highest over southern China and exhibited a decreasing gradient from southern to western and northern China. The decadal difference in Ndep between the 1990s and 2000s was primarily caused by increases in energy consumption and N fertiliser use. Our findings conformed that anthropogenic activities were the main reason for the Ndep increase and provide a scientific background for studies on ecological effects of N deposition in China.


Assuntos
Monitoramento Ambiental , Atividades Humanas , Compostos de Nitrogênio/química , Nitrogênio/química , Poluentes Atmosféricos , Atmosfera , China , Ecossistema , Humanos
2.
Ying Yong Sheng Tai Xue Bao ; 23(3): 587-94, 2012 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-22720598

RESUMO

Based on the measurements of the foliar carbon content (Cmass, nitrogen content (Nmass), isotope abundance (delta13C and delta15N), and light response curve of 10 dominant plant species (Larix gmelinii, Quercus mongolica, Fraxinus mandshurica, Tilia amurensis, Acer mono, Pinus koraiensis, Cunninghamia lanceolata, Schima superba, Pinus massoniana, and Castanea henryi) in the main forests along the North-South Transect of Eastern China (NSTEC), this paper analyzed the differences and the relationships between the foliar water use efficiency and nitrogen use efficiency of the plant species. There existed significant differences in the foliar Nmass and delta15N among the plant species, manifesting as broadleaved species > coniferous species, and deciduous species > evergreen species. The maximum photosynthetic rate (Pn max) was coniferous species > broadleaved species, and deciduous species > evergreen species. Broadleaved and evergreen species tended to have higher foliar instantaneous water use efficiency (WUEi) and long-term water use efficiency (WUE), as compared to coniferous and deciduous species, but an opposite trend was observed in the foliar instantaneous nitrogen use efficiency (NUE) and long-term nitrogen use efficiency (NUE). Moreover, there was a significant difference in the foliar NUE between evergreen and deciduous species. No significant correlation was observed between WUEi and WUE, but a significant positive correlation existed between NUEi and NUE. There was a significant negative correlation between the foliar water use efficiency and nitrogen use efficiency at instantaneous or long-term time scales. In sum, the foliar water use efficiency and nitrogen use efficiency were dominated by plant life-form, and a trade-off existed between the two resources use efficiencies.


Assuntos
Ecossistema , Nitrogênio/metabolismo , Árvores/metabolismo , Água/metabolismo , China , Fraxinus/química , Fraxinus/metabolismo , Larix/química , Larix/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Quercus/química , Quercus/metabolismo , Árvores/química
3.
PLoS One ; 6(10): e26842, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22046376

RESUMO

It is well demonstrated that the responses of plants to elevated atmospheric CO(2) concentration are species-specific and dependent on environmental conditions. We investigated the responses of a subshrub legume species, Caragana microphylla Lam., to elevated CO(2) and nitrogen (N) addition using open-top chambers in a semiarid temperate grassland in northern China for three years. Measured variables include leaf photosynthetic rate, shoot biomass, root biomass, symbiotic nitrogenase activity, and leaf N content. Symbiotic nitrogenase activity was determined by the C(2)H(2) reduction method. Elevated CO(2) enhanced photosynthesis and shoot biomass by 83% and 25%, respectively, and the enhancement of shoot biomass was significant only at a high N concentration. In addition, the photosynthetic capacity of C. microphylla did not show down-regulation under elevated CO(2). Elevated CO(2) had no significant effect on root biomass, symbiotic nitrogenase activity and leaf N content. Under elevated CO(2), N addition stimulated photosynthesis and shoot biomass. By contrast, N addition strongly inhibited symbiotic nitrogenase activity and slightly increased leaf N content of C. microphylla under both CO(2) levels, and had no significant effect on root biomass. The effect of elevated CO(2) and N addition on C. microphylla did not show interannual variation, except for the effect of N addition on leaf N content. These results indicate that shoot growth of C. microphylla is more sensitive to elevated CO(2) than is root growth. The stimulation of shoot growth of C. microphylla under elevated CO(2) or N addition is not associated with changes in N(2)-fixation. Additionally, elevated CO(2) and N addition interacted to affect shoot growth of C. microphylla with a stimulatory effect occurring only under combination of these two factors.


Assuntos
Dióxido de Carbono/farmacologia , Fabaceae/crescimento & desenvolvimento , Fixação de Nitrogênio , Nitrogênio/farmacologia , Biomassa , China , Fabaceae/metabolismo , Fotossíntese , Estruturas Vegetais/crescimento & desenvolvimento
4.
J Environ Qual ; 39(1): 251-9, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20048313

RESUMO

The impact of elevated atmospheric CO(2) concentration on plant communities is varied and strongly dependent on the dominant species response, as well as nutrient conditions. Responses of a dominant species (Leymus chinensis) to elevated CO(2) and N application were examined with open-top chambers in a typical temperate grassland in northern China for 3 yr. The significant effect of elevated CO(2) on L. chinensis growth was mainly reflected in the higher photosynthetic rates, increased leaf number, larger shoot and root biomass, and higher root/shoot (R/S) ratio. Enhancement of root biomass induced by elevated CO(2) was larger (40%) than that of shoot biomass (9%). In contrast, N application had a significant impact on most growth indices examined in this study, which was reflected in the enhanced aboveground growth and depressed belowground growth. Nitrogen application significantly reduced the R/S ratio by an average of 40%. Nitrogen addition significantly enhanced the proportion of senescent biomass and decreased the proportion of green leaf biomass under elevated CO(2). There were no CO(2) x N interactions on most of the measured variables, except on photosynthetic rate and the proportion of aboveground biomass. Plant growth variables showed high interannual variation. These results indicate that belowground growth of L. chinensis is more sensitive to elevated CO(2) than is the aboveground. Aboveground growth of L. chinensis is much more sensitive to N application than to CO(2) enrichment. Therefore, the effect of elevated CO(2) on L. chinensis steppe is more likely to be underestimated if only aboveground parts are considered.


Assuntos
Dióxido de Carbono/metabolismo , Dióxido de Carbono/farmacologia , Nitrogênio/metabolismo , Nitrogênio/farmacologia , Poaceae/efeitos dos fármacos , Biomassa , Dióxido de Carbono/química , China , Nitrogênio/química , Fotossíntese/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Brotos de Planta , Transpiração Vegetal , Poaceae/crescimento & desenvolvimento , Poaceae/metabolismo , Fatores de Tempo
5.
Biotechnol Appl Biochem ; 41(Pt 2): 137-43, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15202936

RESUMO

To improve the antisense activity of AS ODN (antisense oligodeoxynucleotide), a conjugate covalently linked to DOX (doxorubicin) at its 3'-end was synthesized and its antisense activity in human carcinoma DOX-resistant cells (KB-A-1) was investigated in vitro. The intracellular DOX concentration in KB-A-1 cells treated with the conjugate was detected in vitro by HPLC. Results showed that the intracellular DOX concentration was 6.4-fold higher in KB-A-1 cells treated with the conjugate when compared with that in the cells treated with DOX alone. In contrast, a 1.8-fold increase in the concentration of DOX was observed when the cells were treated with AS ODN. Reverse transcriptase PCR and Western-blot analysis showed a more significant decrease in the amount of mdr1 (multidrug resistance 1 gene) mRNA and P-glycoprotein in KB-A-1 cells. Chemosensitivity of KB-A-1 cells to DOX was also investigated in vitro. When the cells were first exposed to the conjugate (0.5 microM) for 24 h and then exposed to DOX for 24 h, the IC(50) value of DOX decreased from 21.5 to 2.2 microM, whereas the IC(50) value of DOX decreased only to 16.8 microM when the cells were treated with the mixture of the same concentration of AS ODN. These results suggest that the conjugate is effective in reversing multidrug resistance. Further studies will be conducted to explore the effect of the conjugate on tumours in vivo.


Assuntos
Subfamília B de Transportador de Cassetes de Ligação de ATP/antagonistas & inibidores , Antineoplásicos/farmacologia , Doxorrubicina/análogos & derivados , Oligodesoxirribonucleotídeos/farmacologia , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Antineoplásicos/química , Sequência de Bases , Carcinoma de Células Escamosas/patologia , Linhagem Celular Tumoral , Sobrevivência Celular , Doxorrubicina/química , Doxorrubicina/farmacologia , Humanos , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos/química , Oligonucleotídeos Antissenso/síntese química , Oligonucleotídeos Antissenso/química , Oligonucleotídeos Antissenso/farmacologia , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa
6.
Biomed Pharmacother ; 58(9): 520-6, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15511610

RESUMO

A conjugate of antisense oligodeoxynucleotide (AS ODN) covalently linked with deoxorubicin (DOX) was synthesized. Its properties and antitumour activity in human carcinoma DOX resistant cells (KB-A-1) were investigated in vitro. The results showed that the conjugate was strongly stable both in Dulbecco's Phosphate-Buffered Saline (PBS) and in culture medium. The intracellular concentration of the conjugate was higher than that of the AS DON by HPLC analysis. The conjugate showed potent dose-dependent inhibition to the growth of KB-A-1 cells. Chemosensitivity of KB-A-1 cells to DOX was also investigated in vitro. When the cells were first exposed to the conjugate (0.5 microM) and then exposed to DOX for 24 h, the IC50 value of DOX decreased from 21.5 to 2.2 microM. In contrast, when treated with the mixture of the same concentration of the AS ODN with equivalent DOX, the IC50 value of DOX was 16.8 microM. Intracellular DOX concentration was detected in KB-A-1 treatment with the conjugate in vitro by HPLC. The results showed that the intracellular DOX concentration was 6.4-fold increased in KB-A-1 cells treated with the conjugate compared to treatment with DOX alone. In contrast, 1.8-fold increasing was observed when treated with the AS ODN. Western blot analysis showed a significantly decrease in the amount of P-glycoprotein in KB-A-1 cells. These results suggest that the conjugate is effective in reversing multidrug resistance. Certainly, further studies are conducting to explore the antitumour effect of the conjugate in vivo.


Assuntos
Doxorrubicina/farmacologia , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Oligonucleotídeos Antissenso/farmacologia , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Doxorrubicina/química , Resistência a Múltiplos Medicamentos/fisiologia , Resistencia a Medicamentos Antineoplásicos/fisiologia , Humanos , Oligonucleotídeos Antissenso/química
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