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91.
92.
L. W. Zhu P. Zhao X. A. Cai X. P. Zeng G. Y. Ni J. Y. Zhang L. L. Zou T. T. Mei M. H. Yu 《Trees - Structure and Function》2012,26(2):535-542
Stem CO2 efflux (E
s) has been estimated from a temperature-related equation, but sap flux often affects measurements of E
s, which leads to misunderstanding real stem respiration. In order to observe the relationship between E
s and stem temperature and to analyze the effect of sap velocity on E
s, stem temperature, E
s and sap flux were measured from a subtropical Schima superba plantation in South China on three trees for consecutive 3 days in July and October 2009. Stem temperature, E
s and sap velocity were significantly higher in July than in October. Stem temperature could explain 17–41 and 54–75% variations
of E
s in July and October, respectively. A negative relationship between E
s and stem temperature was found during 1800–2300 hours in July. The daytime E
s was 9.2, 4.3 and 2.4% higher than the predicted for three trees in July, and this occurred only on Tree 1 in October. Sap
velocity was positively correlated with E
s for three trees in July, and the increase of E
s with the increase of sap velocity was only observed on Tree 1 in October. These results demonstrated that the occurrence
of sap flux could account for the increase of daytime E
s, and the effect of sap velocity on E
s varied with the seasons from the S. superba stem. 相似文献
93.
Effect of cryopreservation on sperm parameters, lipid peroxidation and antioxidant enzymes activity in fowl semen 总被引:1,自引:0,他引:1
The aim of the present study was to determine the influence of chicken semen cryopreservation on sperm parameters, lipid peroxidation and antioxidant enzymes activities. Pooled semen from 10 Black Minorca roosters was used in the study. Semen samples were subjected to cryopreservation using the “pellet” method and dimethylacetamide (DMA) as a cryoprotectant. In the fresh and the frozen-thawed semen sperm membrane integrity (SYBR-14/propidium iodide (PI)), acrosomal damage (PNA-Alexa Fluor®488) and mitochondrial activity (Rhodamine 123) were assessed using flow cytometry. Malondialdehyde (MDA) concentration, catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were determined in sperm cells and seminal plasma by spectrophotometry. All sperm characteristics evaluated using flow cytometry were affected by cryopreservation. After freezing-thawing, there was significant (P < 0.01) reduction in sperm membrane integrity, sperm acrosome integrity and mitochondrial activity. Following cryopreservation, MDA concentration significantly increased in chicken seminal plasma and spermatozoa (P < 0.01, P < 0.05). The CAT activity in seminal plasma significantly decreased (P < 0.05), while intracellular activity of this enzyme did not significantly change in frozen-thawed semen. In seminal plasma of frozen-thawed semen the significant increase (P < 0.01) in GPx activity was detected. Whereas GPx activity in spermatozoa remained statistically unchanged after thawing. The SOD activity significantly increased (P < 0.01) in cryopreserved seminal plasma with simultaneous decrease (P < 0.01) of its activity in cells. In conclusion, this is probably the first report describing the level of antioxidant enzymes in frozen-thawed avian semen. The present study showed that the activity of CAT, GPx and SOD in chicken semen was affected by cryopreservation, what increased the intensity of lipid peroxidation (LPO). Catalase appeared to play an important role in the sperm antioxidant defense strategy at cryopreservation since, opposite to SOD and GPx, its content was clearly reduced by the cryopreservation process. Change in the antioxidant defense status of the chicken spermatozoa and surrounding seminal plasma might affect the semen quality and sperm fertilizing ability. 相似文献
94.
Zhigang Chen Xin He Wenjie Xia Qi Huang Zhigang Zhang Jun Ye Chao Ni Pin Wu Dang Wu Jinghong Xu Fuming Qiu Jian Huang 《PloS one》2013,8(12)
Background
The prognostic value of HIFs in colorectal cancer was evaluated in a large number of studies, but the conclusions were inconclusive. Meanwhile, clinicopathologic differences of HIF-1α and HIF-2α were rarely compared in recent studies.Methodology
Identical search strategies were used to search relevant literatures in the PubMed and Web of Science databases. The prognostic significances and clinicopathological differences of HIFs in CRC were analyzed.Principal Findings
A total of 23studies comprising 2984 CRC patients met the inclusion criteria. The results indicated that overexpressed HIFs were significantly associated with increase of mortality risk, including overall survival (OS) (HR 2.06 95%CI 1.55–2.74) and disease free survival (HR 2.84, 95%CI 1.87–4.31). Subgroup analysis revealed that both overexpressed HIF-1α and HIF-2α had correlations with worse prognosis. The pooled HRs were 2.01 (95% CI: 1.55–2.6) and 2.07(95% CI: 1.01–4.26). Further subgroup analysis on HIF-1α was performed by study location, number of patients, quality score and cut-off value. The results showed that HIF-1α overexpression was significantly associated with poor OS, particularly in Asian countries (HR 2.3, 95% CI: 1.74–3.01), while not in European or other countries. In addition, overexpression of HIF-1α was closely related with these clinicopathological features, including Dukes'' stages (OR 0.39, 95% CI: 0.17–0.89), UICC stages (OR 0.42 95% CI: 0.3–0.59), depth of invasion (OR 0.71, 95% CI: 0.51–0.99), lymphnode status (OR 0.49, 95% CI: 0.32–0.73) and metastasis (OR 0.29, 95% CI: 0.11–0.81). While overexpression of HIF-2α was only associated with grade of differentiation (OR 0.48, 95% CI: 0.29–0.81).Conclusions
This study showed that both HIF-1α and HIF-2α overexpression were associated with an unfavorable prognosis. HIF-1α overexpression seemed to be associated with worse prognosis in Asian countries. Additionally, HIF-1α and HIF-2α indicated distinct clinicopathologic features. 相似文献95.
Ng HoiMan Zhang Teng Wang Guoliang Kan SiMeng Ma Guoyi Li Zhe Chen Chang Wang Dandan Wong MengIn Wong ChioHang Ni Jinliang Zhang Xiaohua Douglas 《中国病毒学》2021,36(5):1144-1153
Virologica Sinica - Influenza is one of the major respiratory diseases in humans. Macau is a tourist city with high density of population and special population mobility. The study on the... 相似文献
96.
To investigate the water-air diffusive greenhouse gases (GHGs) fluxes from the Three Gorges Reservoir (TGR), a field experiment on carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes from water surface was carried out from March 2011 to August 2012 by floating static chamber method. The results showed that CO2 was released to the atmosphere all the time and was less in autumn than in other seasons (P < 0.05). CH4 was also released to the atmosphere throughout the year but more in summer than other three seasons (P < 0.05). N2O flux was higher in autumn than other seasons (P < 0.05), and N2O was absorbed from the atmosphere mainly in summer. Moreover, correlation analysis illustrated that CO2 flux had significantly negative correlation with wind velocity (P < 0.05), whereas positive correlation with pH (P < 0.01) had been found. There was no significant correlation between CH4 (or N2O) flux and the measured environmental variables respectively (P > 0.05). Additionally, the annual fluxes of CO2, CH4 and N2O were 140.45 ± 12.57 mg CO2·m?2 h?1, 1.35 ± 0.14 mg CH4·m?2 h?1 and 34.34 ± 11.64 μg N2O·m?2 h?1, respectively. When compared to other reservoirs worldwide, the CO2 and N2O fluxes from TGR were higher than those from boreal and temperate reservoirs, but much lower than those from tropical reservoirs. CH4 flux was lower than those from boreal, temperate and most tropical reservoirs. In our study, the surface area of the TGR emitted 1.42 × 106 t CO2, 1.19 × 104 t CH4 and 589.93 t N2O in a year. The total GWP was 17.68 t CO2-eq ha?1 yr?1, of which CO2 flux was dominant (74.38%). Therefore, CO2 was the main contributor of GHGs fluxes in our study and thus future researches should focus on how to reduce CO2 fluxes from the surface of the TGR. TGR has a considerable contribution to regional GHG emissions. 相似文献
97.
98.
Haowei Ni Xiaoyan Jing Xian Xiao Na Zhang Xiaoyue Wang Yueyu Sui Bo Sun Yuting Liang 《The ISME journal》2021,15(9):2561
Understanding the effects of changing climate and long-term human activities on soil organic carbon (SOC) and the mediating roles of microorganisms is critical to maintain soil C stability in agricultural ecosystem. Here, we took samples from a long-term soil transplantation experiment, in which large transects of Mollisol soil in a cold temperate region were translocated to warm temperate and mid-subtropical regions to simulate different climate conditions, with a fertilization treatment on top. This study aimed to understand fertilization effect on SOC and the role of soil microorganisms featured after long-term community incubation in warm climates. After 12 years of soil transplantation, fertilization led to less reduction of SOC, in which aromatic C increased and the consumption of O-alkyl C and carbonyl C decreased. Soil live microbes were analyzed using propidium monoazide to remove DNAs from dead cells, and their network modulization explained 60.4% of variations in soil labile C. Single-cell Raman spectroscopy combined with D2O isotope labeling indicated a higher metabolic activity of live microbes to use easily degradable C after soil transplantation. Compared with non-fertilization, there was a significant decrease in soil α- and β-glucosidase and delay on microbial growth with fertilization in warmer climate. Moreover, fertilization significantly increased microbial necromass as indicated by amino sugar content, and its contribution to soil resistant C reached 22.3%. This study evidentially highlights the substantial contribution of soil microbial metabolism and necromass to refractory C of SOC with addition of nutrients in the long-term.Subject terms: Microbial ecology, Biodiversity 相似文献
99.
100.
The great shortage of human hepatic cells makes it desirable to generate extrahepatic stem or precursor cells. In recent years, it has been reported that human multipotential mesenchymal stem cells (hMSCs) differentiate into hepatocyte-like cells. The fetal lung is one of the largest organs containing many MSCs that can be easily obtained. Whether MSCs from fetal lung can differentiate into hepatocytes or bile duct cells is an important issue in basic medicine and clinical application. We isolated fetal lung cells, and expanded and analyzed them. At passage 4, their morphologic, immunophenotyping and cytokine secretions were similar to adult bone marrow-derived MSCs. We conclude that these cells from fetal lung are MSCs, indicating that human fetal lung is an ideal source of hMSCs. hMSCs from fetal lung induced in special differentiation medium showed homogeneous and small polygonal endothelial-like morphology, expressing weak mRNA, as well as Alb and AFP. This implies that hMSCs from fetal lung can differentiate into hepatocyte-like cells. 相似文献