摘要：
In order to improve the efficiency of comet assay, which can be used in epidemiological research to detect genotoxicity of air pollutants, we undertook this study. Formaldehyde at 50 mu M was employed as contaminating agent to poison the human buccal cell before comet assay. During the process of comet assay, each pair of contaminated samples was treated with proteinase K of three different concentrations at 0.1mg/ml, 1mg/ml and 10mg/ml, respectively while other steps are kept the same. The result turned out to be that the 1mg/ml proteinase K could lead to an ideal incubating effect. It was also proved that a 45-minute lysis had almost the same effect as the 120-min one. A further try was the reduction of the enzyme-incubation period to 45 min; the result showed that with the treatment of 1mg/ml proteinase K, a 45-minute lysis and a 45-minute enzyme-incubation as well can achieve a relatively ideal result.
作者机构：
[Liu, Kaiyu; Peng, Jianxin; Peng, Rong; Hong, Huazhu; Hong, HZ; Yang, Hong; Zheng, Jin] Cent China Normal Univ, Inst Entomol, Wuhan 430079, Peoples R China.
通讯机构：
[Hong, Huazhu] C;Cent China Normal Univ, Inst Entomol, Wuhan 430079, Peoples R China.
关键词：
Bacillus thuringiensis;Chemical pesticide;Esterase;Osmotic lysis;Resistance;Trichoplusia ni cell line
摘要：
Cabbage looper moth (Trichoplusia ni) cell line BTI-Tn-5B1-4 (TnH5) has developed high-level resistance (>1000 fold) by the selection of Bt Cry1Ac10 toxin. In order to examine mechanisms of resistance to Cry1Ac10 toxin (biological pesticide), both general esterase activities and cell tolerance to osmotic lysis were compared between non-selected Cry1Ac10-susceptible Trichoplusia ni cell line TnH5-S and Cry1Ac10-resistant Trichoplusia ni cell line TnH5-R selected by Bt Cry1Ac10. The Cry1Ac10-resistant TnH5-R cells had lower general esterase activity than the non-selected TnH5-S cells, and the esterase isozyme bands for the Cry1Ac10-resistant TnH5-R cells were much weaker than that for the non-selected TnH5-S cells. Both activated Cry1Ac10 toxin and multi-toxin from Bacillus thuringiensis subsp. aizawai GC-91 (an engineering bacterium) could not inhibit the esterase activity both in the Cry1Ac10-susceptible and Cry1Ac10-resistant cells, but two chemical pesticides, chlopyrifos and methomyl, could greatly inhibit the esterase activities both in the TnH5-R and TnH5-S cells. On the other hand, cell tolerance to osmotic lysis caused by hypotonic solution for the Cry1Ac10-resistant TnH5-R cells was higher than that for the non-selected TnH5-S cells (2.5×). Based on these results, we made the following conclusions. The general esterase activities in the Cry1Ac10-resistant TnH5-R cells was not related to Bt Cry1Ac10 resistance, but the susceptibility to the two tested chemical pesticides increased in TnH5-R cells because of their lower esterase activity. The increase of cell tolerance to osmotic lysis for the Cry1Ac10-resistant TnH5-R cells may be one of the mechanisms for Bt toxin resistance because midgut cells of insects are also disrupted by an osmotic lysis caused by Bt toxin.
摘要：
The purpose of the present study was to determine gene expression pattern of chemosensitive receptor VR1 in the brain stem of the neonatal rat after low-level gaseous formaldehyde exposure. Male Sprague-Dawley newborn rats were exposed to clean air or 1.8 mg/m(3) formaldehyde for consecutive 72 h and the brain stems were dissected for RNA extraction. The mRNA levels of VR1 and cytokine NGF gene were determined with semiquantitative RT-PCR. We observed that the mRNA expression of VR1 and NGF was significantly increased in the brain of the tested neonatal rats. These findings suggest that successive formaldehyde exposure may increase cytokine NGF expression and then NGF up-regulates VR1 gene expression synchronously. This may have implications for the nervous central neuro-immunological mechanisms mediating multiple chemical sensitivity (MCS), sick building syndromes (SBS), bronchial hyperresponsiveness (BHR) and asthma in humans.
期刊：
INDOOR AIR 2005: PROCEEDINGS OF THE 10TH INTERNATIONAL CONFERENCE ON INDOOR AIR QUALITY AND CLIMATE, VOLS 1-5,2005年15:3920-3923 ISSN：0908-5920
通讯作者：
Yang, X
作者机构：
[Duan, LJ; Lu, ZS; Yan, Y; Cao, Y; Yang, X; Wang, GX] Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Peoples R China.
通讯机构：
[Yang, X] C;Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Peoples R China.
会议名称：
第十届室内空气品质和质量国际学术会议(Proceedings of the 10th International Conference on Indoor Air Quality and Climate)
会议时间：
2005-09-04
会议地点：
北京
会议主办单位：
Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Peoples R China.
会议论文集名称：
第十届室内空气品质和质量国际学术会议
关键词：
formaldehyde;hormesis;biphasic;dual effects
摘要：
Hormesis is a dose-response phenomenon, which is characterized by a counterintuitive switchover from low-dose stimulation to high-dose inhibition that is not infrequently encountered in the course of a toxicity assay. In this paper we provided various data, mainly our findings, to show that hormesis is a common phenomenon in the study of formaldehyde toxicity and these findings have great implications affecting study design, animal model, and endpoint selection as well as clinical applications. In the central nervous system, it has been noticed that formaldehyde can do harm to learning and memory abilities. Our findings in mice exposure to I and 3 mg/m(3) formaldehyde testified this. It is interested to notice, however, mice exposure to 0.5 mg/m(3) formaldehyde have better memory ability than control group. It has also been noticed that formaldehyde can induce the damage of supermolecules such as DNA and proteins, because formaldehyde is highly chemically active.
作者机构：
College of Life Science, Central China Normal University, Wuhan 430079, China;Nanyang Technological;Nanyang Technological University, Nanyang Avenue, 639798, Singapore
会议名称：
第十届室内空气品质和质量国际学术会议(Proceedings of the 10th International Conference on Indoor Air Quality and Climate)
摘要：
Purpose: Whether formaldehyde induces DNA breakage or not is still in debate. So far it is not clear whether dose-effect between formaldehyde and DNA breakage takes place while the DPC exists. Approach: In this study we had chosen human buccal cells as materials to explore the genotoxicity of liquid and gaseous formaldehyde with comet assay. Findings: The results showed that liquid formaldehyde induced DNA breakage in the range from 5 μM to 10 μM (P＜0.05, compared with control group), and 7.5 μM was found to induce DNA breakage most. The DNA crosslinks were significantly found at 15 μM, 30 μM and 50 μM (P＜0.01, compared with 7.5 μM group).DNA breakage caused by gaseous formaldehyde was found at 0.5 mg/m3 and 1.0 mg/m3 (P＜0.01, compared with control group) but DNA crosslinks at 3.0 mg/m3 significantly. Conclusions: The results suggest that formaldehyde induces DNA breakage in a very low concentration range but induces DNA crosslinks in a higher range.
摘要：
Purpose: Numerous studies have confirmed that formaldehyde is genotoxic and mutagenic to mammalian cells. It can induce a broad spectrum of genetic effects. In order to investigate the direct effect of formaldehyde on the proliferation of cells, we undertook this study. Approach: The L-02 and hepatoma SSMC 7721 cell lines were exposed to various concentrations of formaldehyde in vitro. MTT assay was used to evaluate the effects of formaldehyde on the proliferation. Finding: The results showed that the cells' proliferation was enhanced after being treated with low dosages of formaldehyde. However, it was decreased after exposure to high dosages of formaldehyde. A predominant accelerating effect was found at the concentrations of 50 mu g/ml in L-02 cells and 10 mu g/ml in SSMC-7721 cells, respectively. Conclusions: The results suggested that different kinds of cells had different formaldehyde equilibrium system. The cells would present different reactions at the same dosages of endogenous or exogenous formaldehyde.
摘要：
A bacterium strain HS-03 isolated from farm active sludge in Wuhan was found capable of aerobic denitrification. The effect of different inoculated amounts of pre-culture was analyzed. The denitrifying rates of this strain under aerobic and micro-anaerobic conditions were compared. The result indicated that the rate was almost not affected by the presence of oxygen. More than 90% of 10 mmol/L nitrate was removed within 36 hours by this bacterium in the specific medium. During denitrifying process, nitrite was always kept at very low level. The denitrification potential of this bacterium was evaluated for treating artificial wastewater under fully aerobic conditions. More than 90% of 10 mmol/L nitrate in the wastewater was removed when it co-denitrified with fungi Aspergillus oryzae. The main biochemical and physiological features of this strain were characterized. The 16S rDNA sequence was compared with the published data in GenBank by using BLAST. The BLAST level of similarity to Pseudomonas stutzeri, is 99.1%. These results proved that strain HS-03 was a new strain belonging to P. stutzeri.
