[Effects of Long-term Different Tillage Methods on Mercury and Methylmercury Contents in Purple Paddy Soil and Overlying Water].

A long-term experiment was conducted to evaluate the effect of tillage methods on mercury and methylmercury contents in the purple paddy soil and overlying water. The experiment included five tillage methods: no-tillage and fallow in winter, ridge-no-tillage, compartments-no-tillage, paddy-upland rotation and conventional tillage. The results showed that the content of total mercury in soil had the maximum value in the 10-20 cm layer of no-tillage and fallow in winter, ridge-no-tillage and compartments-no-tillage, and the enrichment effect of no-tillage and fallow in winter was especially significant. The concentration of total mercury in soil of paddy-upland rotation and conventional tillage decreased with the increase of the soil depth, and paddy-upland rotation was specifically beneficial to the migration of mercury. The distribution of soil methylmercury was similar to that of total mercury in the soil profile. The methylation ability of soil mercury in the surface and middle of the soil profile was weaker than that at the bottom, while there was an opposite trend for other tillage methods. The concentrations of dissolved mercury ( DHg) and dissolved methylmercury ( DMeHg) in the overlaying water declined with the rise of the water depth in all treatments. The content of DHg in sediment porewater was related to the value of soil total mercury, and they had the same distribution in the soil profile. The content of DMeHg and its proportion accounted for DHg in porewater owned their largest value in the 10-20 cm layer of no-tillage and fallow in winter and ridge-no-tillage, where showed the lowest value of DMeHg in porewater for paddy-upland rotation and conventional tillage. And the percentage of DMeHg in DHg in porewater grew with the increase of soil depth of the latter two methods. Noticeably, the concentration of DMeHg and its proportion accounted for DHg in porewater were both higher than the values in overlying water for all tillage methods.

[Spatial Distribution Characteristics of Different Species Mercury in Water Body of Changshou Lake in Three Gorges Reservoir Region].

An investigation on the concentrations and the spatial distribution characteristics of different species of mercury in the water body of Changshou Lake in Three Gorges Reservoir region was carried out based on the AreGIS statistics module. The results showed that the concentration of the total mercury in Changshou Lake surface water ranged from 0.50 to 3.78 ng x L(-1), with an average of 1.51 ng x L(-1); the concentration of the total MeHg (methylmercury) ranged from 0.10 to 0.75 ng x L(-1), with an average of 0.23 ng x L(-1). The nugget effect value of total mercury in surface water (50.65%), dissolved mercury (49.80%), particulate mercury (29.94%) and the activity mercury (26.95%) were moderate spatial autocorrelation. It indicated that the autocorrelation was impacted by the intrinsic properties of sediments (such as parent materials and rocks, geological mineral and terrain), and on the other hand it was also disturbed by the exogenous input factors (such as aquaculture, industrial activities, farming etc). The nugget effect value of dissolved methylmercury (DMeHg) in Changshou lake surface water (3.49%) was less than 25%, showing significant strong spatial autocorrelation. The distribution was mainly controlled by environmental factors in water. The proportion of total MeHg in total Hg in Changshou Lake water reached 30% which was the maximum ratio of the total MeHg to total Hg in freshwater lakes and rivers. It implied that mercury was easily methylated in the environment of Chanashou Lake.

[Distribution of Mercury in Plants at Water-Level-Fluctuating Zone in the Three Gorges Reservoir].

The mercury (Hg) distribution and storage in plants at water-level-fluctuating zone (WLFZ) in the Three Gorges Reservoir were investigated by analyzing the total mercury(THg) and methylmercury ( MeHg) levels in different parts of plants collected from three typical sites including Shibaozhai, Zhenxi and Hanfeng Lake in WLFZ. The results indicated that THg and MeHg concentrations in plants ranged from (1.62 ± 0.57) to (49.42 ± 3.93) µg x kg(-1) and from (15.27 ± 7.09) to (1 974.67 ± 946.10) ng x kg(-1), respectively. In addition, THg levels in different plant parts followed the trend: root > leaf > stem, and similar trend for MeHg was observed with the highest level in root. An obvious spatial distribution was also found with the THg and MeHg levels in plants in Hanfeng higher than those in the same plants in the other two sampling sites (Shibaozhai and Zhenxi), and there was a difference of THg and MeHg storage in plants in various attitudes. The corresponding THg and MeHg storages were 145.3, 166.4, 124.3 and 88.2 mg x hm(-2), and 1.9, 2.7, 3.6 and 3.2 mg x hm(-2) in 145-150, 150-160, 160-170 and 170-175 m attitudes. The accumulation ability of dominant plants in WLFZ for THg (bioaccumulation factor, BAF < 1) was weaker than that for MeHg (BAF > 1).

[Seasonal Variations in Vertical Profile of Hg Species and the Influential Factors in Changshou Reservior].

The vertical distribution of mercury (Hg) species were investigated in water and porewater of Changshou reservoir during the period from September 2013 to July 2014. Water samples were collected seasonally from five sampling sites, and the concentrations of Hg species were evaluated. Diffusion fluxes of Hg from sediment to overlaying water were also obtained. The results showed that the average concentrations of total Hg and total methylmercury (MeHg) were (14.77 ± 12.24) ng x L(-1) and (0.41 ± 0.47) ng x L(1), respectively. The concentrations of dissolved MeHg (DMeHg) was highest in 4-8 m under surface water, and then decreased with the increasing water depth with a subsequent increase in the bottom of Changshou Reservior. Peak particulate MeHg (PMeHg) values were found in 8-20 m under surface water, but not in the interface of sediment-water, suggesting that the increasing PMeHg might be related to the deposition of MeHg adsorbed to particulates from upper water. Two peak MeHg levels in pore water appeared in 16 and 28 cm under sediment surface, probably due to the extension of living region for sulfate reduction bacteria (SRB) to deeper sediment which resulted in increased methylation rate there. The diffusion fluxes of DMeHg from pore water to overlaying water were 28.2 ng x (m2 x d)(1) and 30.0 ng x (m2 x d)(-1) in autumn and summer, which were significantly higher than that in winter 3.8 ng x (m2 x d)(-1). It may be associated with the higher temperature in those two seasons. An obvious negative correlation was observed between DMeHg and dissolved oxygen (DO) in summer and spring (r = -0.482**, P < 0.05; r = -0.339, P < 0.01); however, similar correlations were not found in autumn and winter.

In-vivo effects and mechanisms of celecoxib-reduced growth of cyclooxygenase-2 (COX-2)-expressing versus COX-2-deleted human HCC xenografts in nude mice.

We previously reported that celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, suppresses growth of human hepatocellular carcinoma (HCC) cells through both COX-2 dependence and independence. Recently, we established COX-2-deleted human HCC cells, C2D-HuH7, and C2D-HuH7-bearing nude mice. Using this novel model, we examined the pharmacological effects and mechanisms of celecoxib on in-vivo growth of HCC xenografts in relation to COX-2 expression. After treatment with celecoxib, the mice bearing HuH7 or C2D-HuH7 xenografts were assessed for the pharmacological effects and mechanisms of celecoxib on HCC xenograft growth in relation to COX-2 expression. Celecoxib resulted in an effective and comparable growth reduction of both COX-2-expressing and COX-2-deleted HuH7 xenografts in association with decreased Ki-67 expression. These results demonstrated celecoxib's COX-2-independent in-vivo anti-HCC effects. Celecoxib increased peroxisome proliferator-activated receptor gamma predominantly in HuH7 xenografts, indicating its COX-2 dependency. Celecoxib reduced p-Rb and DP1/E2F1 complex predominantly via upregulated p21/CDK4 complex in HuH7 xenograft, but p27/CDK4 complex in C2D-HuH7 xenografts. The effects of celecoxib on phosphatase and tensin homolog deleted on chromosome ten/PI3K/Akt signaling were COX-2 independent, but its effects on extracellular-regulated kinase signaling seemed COX-2 dependent. In addition, the effects of celecoxib on AC-H3, AC-H4, and histone deacetylase 2 could be both COX-2 dependent and independent. In conclusion, celecoxib suppresses growth of HuH7 xenografts regardless of COX-2 expression, which may be mediated through different signaling.

TIMP-3 ameliorates hepatic ischemia/reperfusion injury through inhibition of tumor necrosis factor-alpha-converting enzyme activity in rats.

BACKGROUND: Tumor necrosis factor (TNF)-alpha and its receptors play a critical role in the inflammatory cascade after hepatic ischemia/reperfusion injury. TNF-alpha converting enzyme (TACE) or disintegrin and metalloproteinase (ADAM)-17 is a metalloproteinase disintegrin that specifically cleaves precursor TNF-alpha to its mature form and is involved in the ectodomain shedding of TNF receptors. The regulation of TACE is poorly understood and its role in liver injury and/or regeneration is unknown. METHODS: Male Wistar rats were subjected to 10 or 30 min of partial warm hepatic ischemia followed by 3 to 24 hr of reperfusion. Serum and/or hepatic TACE, TNF-alpha, TNF receptor 1 (TNFR1), and interleukin (IL)-6 levels were assessed by enzyme-linked immunosorbent assay, real-time reverse-transcriptase polymerase chain reaction, and/or Western blot. RESULTS: Low levels of TACE were detected in normal liver tissue. Both 10 and 30 min warm ischemia resulted in a rise in TACE expression which peaked six hr after reperfusion. TNF-alpha, TNFR1, and IL-6 levels were up-regulated in a pattern similar to TACE messenger RNA (mRNA) levels. Moreover, selective inhibition of TACE activity by specific inhibitor tissue inhibitor of metalloproteinase (TIMP)-3 at dosages of 100 or 1000 ng/kg body weight showed significant decrease of circulating TNF-alpha and serum alanine transferase (ALT) levels and histological improvement of hepatic ischemia/reperfusion injuries. CONCLUSIONS: TACE expression and its activity, as measured by increases in TNF-alpha, TNFR1, and IL-6 levels, are increased following hepatic ischemia/reperfusion injury, implying that TACE plays an important role in hepatic ischemia/reperfusion injury. Amelioration of hepatic ischemia/reperfusion injury after inhibition of TACE activity by TIMP-3 suggests that TACE inhibition may play an important role in preventing liver ischemia/reperfusion injury warranting further experimental and clinical study.

Activation of Src kinase Lyn by the Kaposi sarcoma-associated herpesvirus K1 protein: implications for lymphomagenesis.

The K1 gene of Kaposi sarcoma-associated herpesvirus (KSHV) encodes a transmembrane glycoprotein bearing a functional immunoreceptor tyrosine-based activation motif (ITAM). Previously, we reported that the K1 protein induced plasmablastic lymphomas in K1 transgenic mice, and that these lymphomas showed enhanced Lyn kinase activity. Here, we report that systemic administration of the nuclear factor kappa B (NF-kappaB) inhibitor Bay 11-7085 or an anti-vascular endothelial growth factor (VEGF) antibody significantly reduced K1 lymphoma growth in nude mice. Furthermore, in KVL-1 cells, a cell line derived from a K1 lymphoma, inhibition of Lyn kinase activity by the Src kinase inhibitor PP2 decreased VEGF induction, NF-kappaB activity, and the cell proliferation index by 50% to 75%. In contrast, human B-cell lymphoma BJAB cells expressing K1, but not the ITAM sequence-deleted mutant K1, showed a marked increase in Lyn kinase activity with concomitant VEGF induction and NF-kappaB activation, indicating that ITAM sequences were required for the Lyn kinase-mediated activation of these factors. Our results suggested that K1-mediated constitutive Lyn kinase activation in K1 lymphoma cells is crucial for the production of VEGF and NF-kappaB activation, both strongly implicated in the development of KSHV-induced lymphoproliferative disorders.

Tumorigenesis and aberrant signaling in transgenic mice expressing the human herpesvirus-8 K1 gene.

BACKGROUND: The K1 gene of human herpesvirus-8 (HHV-8; also known as Kaposi's sarcoma-associated herpesvirus) encodes a transmembrane signaling protein that elicits cellular activation events. To evaluate the potential role of K1 in HHV-8-associated pathogenesis, we produced transgenic mice expressing the HHV-8 K1 gene under the transcriptional control of the simian virus 40 promoter. METHODS: Three independent heterozygous transgenic K1 mouse lines were generated from founder mice. Mouse splenic and thymic lymphocytes and tumor tissues were analyzed for the expression of cytokines involved in inflammatory and immune responses, including tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), basic fibroblast growth factor (bFGF), and interleukin 12 (IL-12); for the activation of the transcription factors nuclear factor-kappaB (NF-kappaB) and the B cell-specific transcription factor Oct-2; and for the activation of the Src and Syk family kinases, components of B-cell receptor-induced signal-transduction pathways. RESULTS: Expression of bFGF was increased in K1-transgenic mice as compared with nontransgenic mice, whereas expression of TNF-alpha and IL-6 did not differ using reverse transcriptase-polymerase chain reaction. K1-transgenic mice showed substantially less serum IL-12 induction than did nontransgenic mice when challenged with a lipopolysaccharide. B lymphocytes from K1-transgenic mice but not from nontransgenic mice showed constitutive activation of NF-kappaB and Oct-2. K1 expression in human B lymphocytes stimulated NF-kappaB-dependent promoter activity. B lymphocytes from K1-transgenic mice also showed increased phosphorylation of Lyn, a Src family tyrosine kinase, and enhanced Lyn activity. Tumors in K1-transgenic mice showed features indicative of a spindle-cell sarcomatoid tumor and a malignant plasmablastic lymphoma. The pattern of cytokine, transcription factor, and Lyn kinase activity in the lymphoma was similar to that in B lymphocytes from K1-transgenic mice. CONCLUSION: K1 may be involved in the activation of NF-kappaB signaling. The enhanced NF-kappaB activity in nonmalignant lymphocytes of K1 mice and its persistence in lymphoma tumors of these mice suggest that the K1 mouse may be a model of premalignancy.

Ethanol decreases the efficiency of phosphorylation of thymidine kinase in a human T-lymphocytic cell line.

BACKGROUND: Thymidine kinase (TK) and thymidylate kinase (TMPK) are the two rate-limiting enzymes in the cascade of activation of the anti-human immunodeficiency virus (HIV) drug 3'-azido-3'-deoxythymidine (AZT) to its active triphosphate form. We examined the effect of ethanol and a combination of ethanol and AZT on TK and TMPK activities in human Jurkat T cells. METHODS: Jurkat T cells were exposed to 0.2 and 0.5% (v/v) ethanol concentrations alone or in combination with 5 or 10 microM AZT for 48 hr in growth medium. TK and TMPK activities were determined by measuring the conversion of [3H] substrates (thymidine or AZT for TK and thymidine monophosphate for TMPK) to their respective monophosphate or diphosphate forms. The effect of ethanol on the transcriptional activity of TK was determined by reverse transcription-polymerase chain reaction and on the growth of Jurkat cells by [3H]-thymidine incorporation and cell-cycle analysis. RESULTS: Treatment of Jurkat cells with 0.2 and 0.5% ethanol concentrations resulted in 25 and 50% decreases (p < or = 0.05) in TK activity, respectively. No significant changes were observed in the TMPK activities. However, ethanol decreased the formation of thymidine diphosphate from thymidine in coupled TK/TMPK reactions, suggesting that decreases in TK activity could result in an overall decrease in the phosphorylation of AZT. The effect of ethanol on TK was independent of its transcript level. AZT in combination with ethanol decreased the inhibitory effect of ethanol on TK activity. However, it did not block the ethanol effect even at higher concentrations. Ethanol significantly decreased the proliferative capacity and cell cycle progression of the Jurkat cells. CONCLUSIONS: Our in vitro study in human Jurkat T cells indicates that at physiologically achievable concentrations in humans, ethanol can decrease TK activity through decreases in cell proliferation, and it suggests that ethanol ingestion in HIV-1-infected individuals could compromise activation of AZT and related drugs through decreased TK activity.

Primary hepatocytes of Tupaia belangeri as a potential model for hepatitis C virus infection.

Hepatitis C virus (HCV) is a major cause of chronic hepatitis worldwide, but the study of HCV infection has been hampered by the lack of an in vitro or in vivo small animal model. The tree shrew Tupaia belangeri is susceptible to infection with a variety of human viruses in vivo, including hepatitis viruses. We show that primary Tupaia hepatocytes can be infected with serum- or plasma-derived HCV from infected humans, as measured by de novo synthesis of HCV RNA, analysis of viral quasispecies evolution, and detection of viral proteins. Production of infectious virus could be demonstrated by passage to naive hepatocytes. To assess whether viral entry in Tupaia hepatocytes was dependent on the recently isolated HCV E2 binding protein CD81, we identified and characterized Tupaia CD81. Sequence analysis of cloned Tupaia cDNA revealed a high degree of homology between Tupaia and human CD81 large extracellular loops (LEL). Cellular binding of E2 and HCV infection could not be inhibited by anti-CD81 antibodies or soluble CD81-LEL, suggesting that viral entry can occur through receptors other than CD81. Thus, primary Tupaia hepatocytes provide a potential model for the study of HCV infection of hepatocytes.