[Heavy Metal Content and Resistance Gene Abundance and Related Properties in the Surface Soil around Qinghai Lake].

Soil heavy metal pollution and the prevalence of resistance genes have been a global concern, and thus many studies have reported the content of heavy metals and resistance genes in soils; however, the contents of heavy metals and antibiotic resistance genes (ARGs) in the soil in highland areas is still unclear. In this study, the environmental residues and distribution of heavy metals and resistance genes in the soil in Qinghai were analyzed, and the relationship between the concentration of heavy metals and antibiotic resistance genes in the soil was explored. Among the soil samples, the content of heavy metal zinc was the highest ï¼»mean: (50.27±19.88) mg·kg-1ï¼½, followed by the content of heavy metal cadmium ï¼»mean: (30.27±9.45) mg·kg-1ï¼½, and the content of heavy metal mercury was the lowest ï¼»mean: (0.027±0.019) mg·kg-1ï¼½. The subtypes of heavy metal resistance genes in soils were mainly czcA, merA, and merP, whose main function was to be responsible for developing mercury resistance. The relative abundance of ß-lactamase resistance genes (0.1505) was the highest in soil, accounting for 47.54% of the total abundance of ARGs; tetracycline resistance genes accounted for 16.93% of the total abundance of ARGs, FCA accounted for approximately 14.56%, and MLSB accounted for approximately 8.77%. The diversity and relative abundance of movable genetic elements (MGEs) were low, and only the [STBX]tnpA01[STBZ] gene was detected; intl[STBX]1[STBZ] and intl[STBX]2[STBZ] were not detected. Correlation studies showed that Cu content (r=-0.533, P=0.006) and Hg (r=0.692, P=0.006) in soil were significantly negatively correlated with altitude, whereas other heavy metals were not significantly correlated with altitude. In addition, heavy metal content was significantly correlated with soil type (P<0.05). There was a significant positive correlation between heavy metal mercury content in soils and czcA (r=0.692, P=0.006), merA (r=0.816, P=0.007), and merP (r=0.594, P=0.02). The results of this study elucidated the occurrence and distribution of heavy metals and ARGs in the Tibetan Plateau region and found that the content of heavy metals in the soil was significantly related to resistance genes.

[Analysis of Three Polycyclic Aromatic Hydrocarbons in Solution Based on Two-Dimensional Fluorescence Correlation Spectroscopy].

Polycyclic aromatic hydrocarbons (PAHs) are listed as the priority pollutants. It is difficult to resolve effectively the peaks of PAHs by conventional one-dimensional fluorescence spectroscopy due to its low content and the overlapping fluorescence three mixed ystems and a total of 27 samples, are to be prepared with different concentrations of three PAHs. Concentrations of three PAHS are monotonically increasing or decreasing in each mixed system. Then the 2D fluorescence correlation spectrum of each mixed systems will be calculated under the perturbation of the concentration of anthracene, phenanthrene and pyrene in solution. There are seven strong autopeaks at 425, 402, 381, 373, 365, 393 and 347 nm in synchronous 2D correlation spectrum. The fluorescence peak of phenanthrene at 347 nm is uncovered in three mixed systems, so the band at 347 nm is to be used as clues for further assignment. According to positive or negative cross peaks at 347 nm in synchronous 2D correlation spectrum, we can know that the peaks at 402, 381, 425 and 452 nm are assigned to anthracene, the peaks at 373 and 393 nm are assigned to pyrene, and the peaks at 365, 356 and 347 nm are assigned to phenanthrene. The fluorescence peak of phenanthrene at 385 nm is shown in asynchronous 2D correlation spectrum; it means the spectral resolution of asynchronous spectrum is better than the synchronous spectrum. The results are that it is feasible to analyze serious overlapping multi-component PAHs using two-dimensional fluorescence correlation spectroscopy, which can be extended to the detection of other pollutants in the air.

Crosstalk between Wnt/ß-catenin and Hedgehog/Gli signaling pathways in colon cancer and implications for therapy.

Wnt/ß-catenin and Hedgehog/Gli signalings play key roles in multiple biogenesis such as embryonic development and tissue homeostasis. Dysregulations of these 2 pathways are frequently found in most cancers, particularly in colon cancer. Their crosstalk has been increasingly appreciated as an important mechanism in regulating colon cancer progression. Our studies into the link between Wnt/ß-catenin and Hedgehog/Gli signalings in colon cancer revealed several possible crosstalk points and suggested potential therapeutic strategies for colon cancer.

Radiation induces acid tolerance of Clostridium tyrobutyricum and enhances bioproduction of butyric acid through a metabolic switch.

BACKGROUND: Butyric acid as a renewable resource has become an increasingly attractive alternative to petroleum-based fuels. Clostridium tyrobutyricum ATCC 25755T is well documented as a fermentation strain for the production of acids. However, it has been reported that butyrate inhibits its growth, and the accumulation of acetate also inhibits biomass synthesis, making production of butyric acid from conventional fermentation processes economically challenging. The present study aimed to identify whether irradiation of C. tyrobutyricum cells makes them more tolerant to butyric acid inhibition and increases the production of butyrate compared with wild type. RESULTS: In this work, the fermentation kinetics of C. tyrobutyricum cultures after being classically adapted for growth at 3.6, 7.2 and 10.8 g·L-1 equivalents were studied. The results showed that, regardless of the irradiation used, there was a gradual inhibition of cell growth at butyric acid concentrations above 10.8 g·L-1, with no growth observed at butyric acid concentrations above 3.6 g·L-1 for the wild-type strain during the first 54 h of fermentation. The sodium dodecyl sulfate polyacrylamide gel electrophoresis also showed significantly different expression levels of proteins with molecular mass around the wild-type and irradiated strains. The results showed that the proportion of proteins with molecular weights of 85 and 106 kDa was much higher for the irradiated strains. The specific growth rate decreased by 50% (from 0.42 to 0.21 h-1) and the final concentration of butyrate increased by 68% (from 22.7 to 33.4 g·L-1) for the strain irradiated at 114 AMeV and 40 Gy compared with the wild-type strains. CONCLUSIONS: This study demonstrates that butyric acid production from glucose can be significantly improved and enhanced by using 12C6+ heavy ion-irradiated C. tyrobutyricum. The approach is economical, making it competitive compared with similar fermentation processes. It may prove useful as a first step in a combined method employing long-term continuous fermentation of acid-production processes.

Dichlorodiphenyltrichloroethane exposure induces the growth of hepatocellular carcinoma via Wnt/ß-catenin pathway.

Dichlorodiphenyltrichloroethane (DDT) is a persistent organic pollutant, involved in the progression of many cancers, including liver cancer. However, the underlying mechanism(s) of DDT, especially how low doses DDT cause liver cancer, is poorly understood. In this study, we evaluated the impact of p,p'-DDT on the growth of hepatocellular carcinoma using both in vitro and in vivo models. The present data indicated that the proliferation of HepG2 cells was strikingly promoted after exposed to p,p'-DDT for 4 days. In addition, reactive oxygen species (ROS) content was significantly elevated, accompanied with inhibitions of γ-glutamylcysteine synthetase (γ-GCS) and superoxide dismutase (SOD) activities. Interestingly, the levels of ß-catenin and its downstream target genes (c-Myc and CyclinD1) were significantly up-regulated, and co-treatment of NAC, the ROS inhibitor, inhibited these over-expressed proteins. Moreover, the p,p'-DDT-stimulated proliferation of HepG2 cells could be reversed after NAC or ß-catenin siRNA co-treatment. Likewise, p,p'-DDT treatment increased the growth of tumor in nude mice, stimulated oxidative stress and Wnt/ß-catenin pathway. Our study indicates that low doses p,p'-DDT exposure promote the growth of hepatocellular carcinoma via Wnt/ß-catenin pathway which is activated by oxidative stress. The finding suggests an association between low dose DDT exposure and liver cancer growth.

The effect of microdosimetric 12C6+ heavy ion irradiation and Mg2+ on canthaxanthin production in a novel strain of Dietzia natronolimnaea.

BACKGROUND: Dietzia natronolimnaea is one of the most important bacterial bioresources for high efficiency canthaxanthin production. It produces the robust and stable pigment canthaxanthin, which is of special interest for the development of integrated biorefineries. Mutagenesis employing 12C6+ irradiation is a novel technique commonly used to improve microorganism productivity. This study presents a promising route to obtaining the highest feasible levels of biomass dry weight (BDW), and total canthaxanthin by using a microdosimetric model of 12C6+ irradiation mutation in combination with the optimization of nutrient medium components. RESULTS: This work characterized the rate of both lethal and non-lethal dose mutations for 12C6+ irradiation and the microdosimetric kinetic model using the model organism, D. natronolimnaea svgcc1.2736. Irradiation with 12C6+ ions resulted in enhanced production of canthaxanthin, and is therefore an effective method for strain improvement of D. natronolimnaea svgcc1.2736. Based on these results an optimal dose of 0.5-4.5 Gy, Linear energy transfer (LET) of 80 keV µm-1and energy of 60 MeV u-1 for 12C6+ irradiation are ideal for optimum and specific production of canthaxanthin in the bacterium. Second-order empirical calculations displaying high R-squared (0.996) values between the responses and independent variables were derived from validation experiments using response surface methodology. The highest canthaxanthin yield (8.14 mg) was obtained with an optimized growth medium containing 21.5 g L-1 D-glucose, 23.5 g L-1 mannose and 25 ppm Mg2+ in 1 L with an irradiation dose of 4.5 Gy. CONCLUSIONS: The microdosimetric 12C6+ irradiation model was an effective mutagenic technique for the strain improvement of D. natronolimnaea svgcc1.2736 specifically for enhanced canthaxanthin production. At the very least, random mutagenesis methods using 12C6+ions can be used as a first step in a combined approach with long-term continuous fermentation processes. Central composite design-response surface methodologies (CCD-RSM) were carried out to optimize the conditions for canthaxanthin yield. It was discovered D-glucose, Mg2+ and mannose have significant influence on canthaxanthin biosynthesis and growth of the mutant strain.

High efficiency degradation crude oil by a novel mutant irradiated from Dietzia strain by 12C6+ heavy ion using response surface methodology.

Crude oil is an extremely complex mixture of hydrocarbons; also contaminate environmental, leading to carcinogenic, teratogenic and mutagenic. Petroleum hydrocarbons degradation Dietzia strain DMYR9 was isolated from oilfield. Response surface methodology was applied for statistical designing of process parameters for dry weight of biomass production in the process of degradation. The optimization process parameters were successfully employed for degradation crude oil and confirmed through confirmatory experiments. On 28th day, analysis was done by GC-MS, These data show that the crude oil samples of n-Hexadecane, Octadecane, n-Nonadecanec, n-Pentacosane, n-Hexacosane, n-Heneicosane, n-Docosane, n-Tetracosane, n-Octacosane and Tetraethyl removal efficiency could reach up to 0%. RSM optimization and use of effective (12)C(6+)-ion irradiation methods can considerably enhance ability to degradation of microbial. Hence, bioresource Dietzia strain DMYR9, high ability to degradation, can be further used for subsequent repair hydrocarbons polluted of environment.

Characterization of a wheat (Triticum aestivum L.) expansin gene, TaEXPB23, involved in the abiotic stress response and phytohormone regulation.

Expansins are proteins that are generally accepted to be key regulators of cell wall extension and plant growth. We examined the expression pattern of TaEXPB23, a wheat (Triticum aestivum L.) expansin gene, under exogenous phytohormone and abiotic stress treatments. In addition, we evaluated its function in the tolerance to salt stress and high temperature (HT) by overexpressing it in transgenic tobacco plants. In subcellular localization assays, TaEXPB23 localized to the cell wall. Expression analysis demonstrated that the transcription pattern of TaEXPB23 corresponded to wheat coleoptile growth. Real-time RT-PCR analysis revealed that TaEXPB23 transcript expression was upregulated by exogenous methyl jasmonate (MeJA) and salt stress, but downregulated by exogenous gibberellins (GA3), ethylene (ET), indole-3-acetic acid (IAA) and α-naphthlcetic acid (NAA). Overexpression of TaEXPB23 in tobacco (tabacum) conferred tolerance to salt stress by enhancing water retention ability (WRA) and decreasing osmotic potential (OP). However, transgenic plants overexpressing TaEXPB23 did not show any improvement in the tolerance to HT stress. These results suggested that TaEXPB23 is regulated by phytohormones and is involved in the regulation of salt stress tolerance.

Expansins are involved in cell growth mediated by abscisic acid and indole-3-acetic acid under drought stress in wheat.

Expansin protein is a component of the cell wall generally accepted to be the key regulator of cell wall extension during plant growth. Plant hormones regulate expansin gene expression as well as plant growth during drought stress. However, the relationship between expansin and plant hormone is far from clear. Here, we studied the involvement of expansin in plant cell growth mediated by the hormones indole-3-acetic acid (IAA) and abscisic acid (ABA) under osmotic stress which was induced by polyethylene glycol (PEG)-6000. Wheat coleoptiles from a drought-resistant cultivar HF9703 and a drought-sensitive cultivar 921842 were used to evaluate cell growth and expansin activity. Osmotic stress induced the accumulation of ABA. ABA induced expansin activity mainly by enhancing expansin expression, since ABA induced cell wall basification via decreasing plasma membrane H(+)-ATPase activity, which was unfavorable for expansin activity. Although ABA induced expansin activity and cell wall extension, treatment with exogenous ABA and/or fluridone (FLU, an ABA inhibitor) suggested that ABA was involved in the coleoptile growth inhibition during osmotic stress. IAA application to detached coleoptiles also enhanced coleoptile growth and increased expansin activity, but unlike ABA, IAA-induced expansin activity was mainly due to the decrease of cell wall pH by increasing plasma membrane H(+)-ATPase activity. Compared with drought-sensitive cultivar, the drought-resistant cultivar could maintain greater expansin activity and cell wall extension, which was contributive to its resultant faster growth under water stress.

Expansin-regulated cell elongation is involved in the drought tolerance in wheat.

Water stress restrains plant growth. Expansin is a cell wall protein that is generally accepted to be the key regulator of cell wall extension during plant growth. In this study, we used two different wheat cultivars to study the involvement of expansin in drought tolerance. Wheat coleoptile was used as the material in experiment. Our results indicated that water stress induced an increase in acidic pH-dependant cell wall extension, which is related to expansin activity; however, water stress inhibited coleoptile elongation growth. The increased expansin activity was mainly due to increased expression of expansin protein that was upregulated by water stress, but water stress also resulted in a decrease in cell wall acidity, a negative factor for cell wall extension. Decreased plasma membrane H(+)-ATPase activity was involved in the alkalinization of the cell wall under water stress. The activity of expansin in HF9703 (a drought-tolerant wheat cultivar) was always higher than that in 921842 (a drought-sensitive wheat cultivar) under both normal and water stress conditions, which may be correlated with the higher expansin protein expression and plasma membrane H(+)-ATPase activity observed in HF9703 versus 921842. However, water stress did not change the susceptibility of the wheat cell wall to expansin, and no difference in this susceptibility was observed between the drought-tolerant and drought-sensitive wheat cultivars. These results suggest the involvement of expansin in cell elongation and the drought resistance of wheat.

The characteristics of expansins in wheat coleoptiles and their responses to water stress.

As the key regulators of cell wall extension during plant growth, expansins play an important role in regulating the development and response of plants to adverse environment. The characteristics of expansins in wheat coleoptiles and their responses to water stress were studied. Expansin proteins were extracted from wheat coleoptiles by the methods of Hepes or SDS. The activities of expansins were measured with an improved extensometer and the amount of expansins was measured by immunoblot analysis with the expansin antibody. The results showed that in coleoptiles, the extension of native cell walls depended on acidic pH, and the expansins were found to be located at cell walls by location analysis. Expansins from wheat coleoptiles could induce cell wall extension both of cucumber hypocotyls and coleoptiles, and vice versa, albeit with differences noted in extension activity. The changes in activity and abundance of expansins in wheat coleoptiles in response to water stress suggest that expansins may play a significant role in the tolerance of wheat plants to water stress.

Dual effect of transforming growth factor beta1 on cell adhesion and invasion in human placenta trophoblast cells.

Transforming growth factor beta (TGFbeta) has been shown to be a multifunctional cytokine required for embryonic development and regulation of trophoblast cell behaviors. In the present study, a non-transformed cell-line representative of normal human trophoblast (NPC) was used to examine the effect of TGFbeta1 on trophoblast cell adhesion and invasion. In vitro assay showed that TGFbeta1 could significantly promote intercellular adhesion, while inhibiting cell invasion across the collagen I-coated filter. Reverse transcription (RT)-PCR and gelatin zymography demonstrated that TGFbeta1 evidently repressed the mRNA expression and proenzyme production of matrix metalloproteinase (MMP)-9, but exerted no effect on mRNA expression and secretion of MMP-2. On the other hand, both the mRNA and protein expression of epithelial-cadherin and beta-catenin were obviously upregulated by TGFbeta1 in dose-dependent fashion, as revealed by RT-PCR and western-blot analysis. What is more, one of the critical TGFbeta signaling molecules - Smad2 was notably phosphorylated in TGFbeta1-treated NPC cells. The data indicates that cell invasion and adhesion are coordinated processes in human trophoblasts and that there exists paracrine regulation on adhesion molecules and invasion-associated enzymes in human placenta.

Spatio-temporal expression of matrix metalloproteinase-26 in human placental trophoblasts and fetal red cells during normal placentation.

The processes of implantation and placentation involve the degradation and remodeling of extracellular matrix, cellular proliferation, apoptosis, and differentiation. Evidence indicates that members of the matrix metalloproteinase (MMP) family play crucial roles in these processes. In the present study, we identified the expression and localization of MMP26/endometase/ matrilysin-2 in human placentae at different stages of gestation using methods of reverse transcriptase-polymerase chain reaction, in situ hybridization, and immunohistochemistry. MMP26 was widely localized to villous cytotrophoblast cells, syncytiotrophoblast cells, and to column trophoblasts during early pregnancy. The mRNA and protein level of MMP26 in chorionic villi was highest at Weeks 6-7, and decreased thereafter, reaching its lowest level at the second trimester. The mRNA level was significantly up-regulated in term placenta, while the immunoreactivity remained undetectable. Notably, intense expression of MMP26 was found in fetal nucleated red cells inside the villous capillaries during gestational Weeks 6-9. Strong expression of MMP26 mRNA was also demonstrated in fetal red cells isolated from the whole blood of fetuses at midpregnancy. The expression patterns of MMP26 in human placenta suggests complicated roles for MMP26 during the processes of placentation and hematopoiesis, perhaps working in concert with other members of the MMP family, such as MMP9.