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91.
Litterfall Production Along Successional and Altitudinal Gradients of Subtropical Monsoon Evergreen Broadleaved Forests in Guangdong, China 总被引:3,自引:0,他引:3
Guoyi Zhou Lili Guan Xiaohua Wei Deqiang Zhang Qianmei Zhang Junhua Yan Dazhi Wen Juxiu Liu Shuguang Liu Zhongliang Huang Guohui Kong Jiangming Mo Qingfa Yu 《Plant Ecology》2007,188(1):77-89
Evaluation of litterfall production is important for understanding nutrient cycling, forest growth, successional pathways, and interactions with environmental variables in forest ecosystems. Litterfall was intensively studied during the period of 1982–2001 in two subtropical monsoon vegetation gradients in the Dinghushan Biosphere Reserve, Guangdong Province, China. The two gradients include: (1) a successional gradient composed of pine forest (PF), mixed pine and broadleaved forest (MF) and monsoon evergreen broadleaved forest (BF), and (2) an altitudinal gradient composed of Baiyunci ravine rain forest (BRF), Qingyunci ravine rain forest (QRF), BF and mountainous evergreen broadleaved forest (MMF). Mean annual litterfall production was 356, 861 and 849 g m−2 for PF, MF and BF of the successional gradient, and 1016, 1061, 849 and 489 g m−2 for BRF, QRF, BF and MMF of the altitudinal gradient, respectively. As expected, mean annual litterfall of the pioneer forest PF was the lowest, but rapidly increased over the observation period while those in other forests were relatively stable, confirming that forest litterfall production is closely related to successional stages and growth patterns. Leaf proportions of total litterfall in PF, MF, BF, BRF, QRF and MMF were 76.4%, 68.4%, 56.8%, 55.7%, 57.6% and 69.2%, respectively, which were consistent with the results from studies in other evergreen broadleaved forests. Our analysis on litterfall monthly distributions indicated that litterfall production was much higher during the period of April to September compared to other months for all studied forest types. Although there were significant impacts of some climate variables (maximum and effective temperatures) on litterfall production in some of the studied forests, the mechanisms of how climate factors (temperature and rainfall) interactively affect litterfall await further study. 相似文献
92.
Kong WN Zhao SE Duan XL Yang Z Qian ZM Chang YZ 《Journal of cellular biochemistry》2008,104(2):629-641
Recycled iron from reticuloendothelial macrophages to erythroid precursors is important to maintain the iron homeostasis. However, the molecular mechanisms underlying iron homeostasis in macrophages are poorly understood. In this study, male Sprague-Dawley rats were treated with recombinant human erythropoietin (rHuEpo, 500 IU/day, s.c.) for 3 days. At the fifth day, peritoneal exudate macrophages were harvested, and then (55)Fe uptake and release were measured by liquid scintillation counting method. The expression of divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) in peritoneal exudate macrophages was detected by RT-PCR and Western blot. In order to exclude the direct effect of rHuEpo on macrophages, the parallel experiments were performed with incubation normal peritoneal exudate macrophages with rHuEpo (2 IU/ml). Our results showed rHuEpo injection reduced the peritoneal exudate macrophages iron retention. The uptake of Fe(II) was decreased via the suppression of DMT1 (+IRE) expression and the release of Fe(II) was increased with increasing the expression of FPN1 in macrophages. Moreover, the expression of HAMP mRNA was four times lower in rHuEpo-treated liver of rats than control group (CG). HAMP mRNA expression was increased; the synthesis of DMT1 had no significant change, whereas the FPN1 was decreased in normal peritoneal exudate macrophages after treatment with rHuEpo in vitro. We conclude that hepcidin may play a major, causative role in the change of FPN1 synthesis and that decreased the iron retention in macrophages of rHuEpo-treated rats. 相似文献
93.
SN Park SW Kong MS Park JW Lee E Cho YK Lim MH Choi HS Kim YH Chang JH Shin HS Park SH Choi JK Kook 《Journal of bacteriology》2012,194(19):5445-5446
Fusobacterium nucleatum, one of the major causative bacteria of periodontitis, is classified into five subspecies (nucleatum, polymorphum, vincentii, animalis, and fusiforme) on the basis of the several phenotypic characteristics and DNA homology. This is the first report of the draft genome sequence of F. nucleatum subsp. fusiforme ATCC 51190(T). 相似文献
94.
Kong X Zhang C Jin X Wu X Zhang S Zhong Z Feng Q Liu T Yuan H 《BioFactors (Oxford, England)》2011,37(4):323-327
The objective of this study is to observe the effect of high-mobility group protein B1 A Box (HMGB1 A) box on lung injury in mice with acute pancreatitis and its effect on the level of high-mobility group protein B1 (HMGB1) in lung, to explore the mechanism. A total of 60 male Institute of Cancer Research mice were randomly divided into control group (n = 30) and treatment group (n = 30). Severe acute pancreatitis mice model was induced by 20% L-Arg intraperitoneal injection. The recombination HMGB1 A box was used in treatment after modeling. All the mice were killed under anesthesia at 24 and 48 h after the modeling injection. The level of HMGB1 and activity of myeloperoxidase (MPO) in lung were measured. The pathological changes of lung were observed. The level of HMGB1 in lung of A box treatment group decreased more significantly 24 h and 48 h after modeling compared with control group. The activity of MPO in lung of A box treatment group decreased more significantly 24 h after modeling compared with control group. The lung tissue pathologic score of A box treatment group decreased more significantly 48 h after modeling compared with control group. HMGB1 expression levels in the lungs were positively related to histological score of injured lung in acute pancreatitis. It indicates that HMGB1 A box is remarkably protective to lung injury induced by acute pancreatitis. 相似文献
95.
The Telomerase/vault-associated protein TEP1 is required for vault RNA stability and its association with the vault particle 总被引:7,自引:0,他引:7
Kickhoefer VA Liu Y Kong LB Snow BE Stewart PL Harrington L Rome LH 《The Journal of cell biology》2001,152(1):157-164
Vaults and telomerase are ribonucleoprotein (RNP) particles that share a common protein subunit, TEP1. Although its role in either complex has not yet been defined, TEP1 has been shown to interact with the mouse telomerase RNA and with several of the human vault RNAs in a yeast three-hybrid assay. An mTep1(-/-) mouse was previously generated which resulted in no apparent change in telomere length or telomerase activity in six generations of mTep1-deficient mice. Here we show that the levels of the telomerase RNA and its association with the telomerase RNP are also unaffected in mTep1(-/-) mice. Although vaults purified from the livers of mTep1(-/-) mice appear structurally intact by both negative stain and cryoelectron microscopy, three-dimensional reconstruction of the mTep1(-/-) vault revealed less density in the cap than previously observed for the intact rat vault. Furthermore, the absence of TEP1 completely disrupted the stable association of the vault RNA with the purified vault particle and also resulted in a decrease in the levels and stability of the vault RNA. Therefore, we have uncovered a novel role for TEP1 in vivo as an integral vault protein important for the stabilization and recruitment of the vault RNA to the vault particle. 相似文献
96.
Background
In the past decades the rapid growth of molecular diagnostics (based on either traditional PCR or isothermal amplification technologies) meet the demand for fast and accurate testing. Although isothermal amplification technologies have the advantages of low cost requirements for instruments, the further improvement on sensitivity, speed and robustness is a prerequisite for the applications in rapid pathogen detection, especially at point-of-care diagnostics. Here, we describe and explore several strategies to improve one of the isothermal technologies, helicase-dependent amplification (HDA). 相似文献97.
98.
Tao Chen Yu Wu Yuzi Wang Jigao Zhu Haiying Chu Li Kong Liangwei Yin Haiying Ma 《Neurochemical research》2017,42(11):3073-3083
Brain-derived neurotrophic factor (BDNF) plays an important role in promoting the growth, differentiation, survival and synaptic stability of neurons. Presently, the transplantation of neural stem cells (NSCs) is known to induce neural repair to some extent after injury or disease. In this study, to investigate whether NSCs genetically modified to encode the BDNF gene (BDNF/NSCs) would further enhance synaptogenesis, BDNF/NSCs or naive NSCs were directly engrafted into lesions in a rat model of traumatic brain injury (TBI). Immunohistochemistry, western blotting and RT-PCR were performed to detect synaptic proteins, BDNF-TrkB and its downstream signaling pathways, at 1, 2, 3 or 4 weeks after transplantation. Our results showed that BDNF significantly increased the expression levels of the TrkB receptor gene and the phosphorylation of the TrkB protein in the lesions. The expression levels of Ras, phosphorylated Erk1/2 and postsynaptic density protein-95 were elevated in the BDNF/NSCs-transplanted groups compared with those in the NSCs-transplanted groups throughout the experimental period. Moreover, the nuclear factor (erythroid-derived 2)-like 2/Thioredoxin (Nrf2/Trx) axis, which is a specific therapeutic target for the treatment of injury or cell death, was upregulated by BDNF overexpression. Therefore, we determined that the increased synaptic proteins level implicated in synaptogenesis might be associated with the activation of the MAPK/Erk1/2 signaling pathway and the upregulation of the antioxidant agent Trx modified by BDNF-TrkB following the BDNF/NSCs transplantation after TBI. 相似文献
99.
Jacques Friborg Jr. Wing-Pui Kong C. Clay Flowers Scarlett L. Flowers Yongnian Sun Kimberly E. Foreman Brian J. Nickoloff Gary J. Nabel 《Journal of virology》1998,72(12):10073-10082
The DNA sequence for Kaposi’s sarcoma-associated herpesvirus was originally detected in Kaposi’s sarcoma biopsy specimens. Since its discovery, it has been possible to detect virus in cell lines established from AIDS-associated body cavity-based B-cell lymphoma and to propagate virus from primary Kaposi’s sarcoma lesions in a human renal embryonic cell line, 293. In this study, we analyzed the infectivity of Kaposi’s sarcoma-associated herpesvirus produced from these two sources. Viral isolates from cultured cutaneous primary KS cells was transmitted to an Epstein-Barr virus-negative Burkitt’s B-lymphoma cell line, Louckes, and compared to virus induced from a body cavity-based B-cell lymphoma cell line. While propagation of body cavity-based B-cell lymphoma-derived virus was not observed in 293 cell cultures, infection with viral isolates obtained from primary Kaposi’s sarcoma lesions induced injury in 293 cells typical of herpesvirus infection and was associated with apoptotic cell death. Interestingly, transient overexpression of the Kaposi’s sarcoma-associated herpesvirus v-Bcl-2 homolog delayed the process of apoptosis and prolonged the survival of infected 293 cells. In contrast, the broad-spectrum caspase inhibitors Z-VAD-fmk and Z-DEVD-fmk failed to protect infected cell cultures, suggesting that Kaposi’s sarcoma-associated herpesvirus-induced apoptosis occurs through a Bcl-2-dependent pathway. Kaposi’s sarcoma-associated herpesvirus isolates from primary Kaposi’s sarcoma lesions and body cavity-based lymphomas therefore may differ and are likely to have distinct contributions to the pathophysiology of Kaposi’s sarcoma. 相似文献
100.
Hydrological regulation drives regime shifts: evidence from paleolimnology and ecosystem modeling of a large shallow Chinese lake 总被引:2,自引:0,他引:2 下载免费PDF全文
Xiangzhen Kong Qishuang He Bin Yang Wei He Fuliu Xu Annette B. G. Janssen Jan J. Kuiper Luuk P. A. van Gerven Ning Qin Yujiao Jiang Wenxiu Liu Chen Yang Zelin Bai Min Zhang Fanxiang Kong Jan H. Janse Wolf M. Mooij 《Global Change Biology》2017,23(2):737-754
Quantitative evidence of sudden shifts in ecological structure and function in large shallow lakes is rare, even though they provide essential benefits to society. Such ‘regime shifts’ can be driven by human activities which degrade ecological stability including water level control (WLC) and nutrient loading. Interactions between WLC and nutrient loading on the long‐term dynamics of shallow lake ecosystems are, however, often overlooked and largely underestimated, which has hampered the effectiveness of lake management. Here, we focus on a large shallow lake (Lake Chaohu) located in one of the most densely populated areas in China, the lower Yangtze River floodplain, which has undergone both WLC and increasing nutrient loading over the last several decades. We applied a novel methodology that combines consistent evidence from both paleolimnological records and ecosystem modeling to overcome the hurdle of data insufficiency and to unravel the drivers and underlying mechanisms in ecosystem dynamics. We identified the occurrence of two regime shifts: one in 1963, characterized by the abrupt disappearance of submerged vegetation, and another around 1980, with strong algal blooms being observed thereafter. Using model scenarios, we further disentangled the roles of WLC and nutrient loading, showing that the 1963 shift was predominantly triggered by WLC, whereas the shift ca. 1980 was attributed to aggravated nutrient loading. Our analysis also shows interactions between these two stressors. Compared to the dynamics driven by nutrient loading alone, WLC reduced the critical P loading and resulted in earlier disappearance of submerged vegetation and emergence of algal blooms by approximately 26 and 10 years, respectively. Overall, our study reveals the significant role of hydrological regulation in driving shallow lake ecosystem dynamics, and it highlights the urgency of using multi‐objective management criteria that includes ecological sustainability perspectives when implementing hydrological regulation for aquatic ecosystems around the globe. 相似文献