阿比哚致突变作用的研究

目的研究阿比哚的致突变作用。方法应用微生物回复突变试验、小鼠微核试验、哺乳动物培养细胞染色体试验 ,观察阿比哚对细胞的诱变性。结果阿比哚的Ames实验、小鼠体内微核试验、CHL细胞染色体畸变试验均呈阴性结果 ,阿比哚无诱变性。结论阿比哚无致突变作用。     

长春西汀的致突变研究

目的 :检测长春西汀是否有致突变作用。方法 :采用Ames试验 ,小鼠微核试验及哺乳动物培养细胞染色体畸变试验观察长春西汀的诱变性。结果 :Ames试验 ,微核试验及染色体畸变试验结果均为阴性。结论 :长春西汀在所试条件下未见致突变作用。     

氨磷汀的两项遗传毒理学实验

目的：考察受试物氨磷汀（ALD）是否具有遗传毒性,方法：采用活体小鼠同髓嗜多染色性红细胞（PEC）微核试验和体外中国仓鼠肺细胞（CHL）染色体畸变试验,对ALD进行诱变性研究,结果：ALD的小鼠骨髓PEC微核试验为阴性,CHL染色体畸变试验为阴性,结论：ALD在一定计是一范围内无致突变性和遗传毒性。     

国产环丙沙星的诱变性和致癌性研究

应用小鼠骨髓细胞微核试验、CHL细胞染色体畸变试验及叙利亚地鼠胚胎细胞转化试验,对国产环丙沙星进行了诱变性和致癌研究。结果: 环丙沙星在小鼠骨髓细胞微核试验和CHL细胞染色体畸变试验中均为阴性;在细胞转化试验中不诱发SHE细胞发生形态转化。实验结果提示环丙沙星在体内、外不引起染色体损伤;无体外致癌作用。     

大鼠骨髓微核试验制片技术的改进

小鼠骨髓微核试验已成为一种致突变性的常规测试系统,它主要用于检测化学物诱变红细胞生成过程中前期细胞的染色体或纺锤体损伤。骨髓微核试验作为体内试验与Ames试验合用,可以预示受试化学物的致癌性,巳被国际环境致突变研究机构建议作为一种基本的体内致突变试验。并发表测试规范.大鼠的动物模型在毒理学研究中起着重要作用,有关化学物对大鼠的毒性和代谢动力学等资料较易获得,所以进行大鼠骨髓微核试验有     

藿莲香Ⅱ号复方的致突变性研究

目的根据《食品安全性毒理学评价程序和方法》(GB15193-2003)对中药复方藿莲香Ⅱ号进行相关的毒理学评价。方法应用急性毒性试验、小鼠骨髓嗜多染红细胞微核试验、小鼠骨髓细胞染色体畸变试验和Ames试验检测该复方的急性毒性和致突变性。结果急性经口毒性试验:雌性、雄性小鼠经口最大无毒浓度(MTD)为10g/kg体质量,属实际无毒;致突变实验:小鼠骨髓嗜多染红细胞微核试验、小鼠骨髓细胞染色体畸变试验和Ames试验结果均为阴性,显示在本实验条件下,该配伍未见有致突变性作用。结论藿莲香Ⅱ号未见有致突变性作用。     

中药复方藿莲香Ⅰ号的遗传毒理学研究

目的：根据前期藿莲香Ⅰ号药效学研究结果,进一步研究该复方的急性毒性和致突变作用,为其进一步应用的安全性提供理论依据。方法应用急性毒性实验、小鼠骨髓嗜多染红细胞微核试验、小鼠骨髓细胞染色体畸变试验和Ames试验检测该组分配伍复方的急性毒性和致突变性。结果急性经口毒性试验：雌性、雄性小鼠经口MTD均大于10g＆#183;kg-1,属实际无毒。致突变实验：小鼠骨髓嗜多染红细胞微核试验、小鼠骨髓细胞染色体畸变试验和Ames试验结果均为阴性,显示在本实验条件下,该中药复方未见有致突变性作用。结论中药复方藿莲香Ⅰ号未见有明显的急性毒性和致突变作用,表明该药物安全性良好。     

中药浮海石致突变的实验研究

目的研究中药浮海石致突变性。方法本试验采用鼠伤寒沙门菌回复突变试验(Ames试验),哺乳动物培养细胞(CHL)染色体畸变试验和小鼠骨髓细胞微核试验观察了浮海石的致突变作用。结果浮海石生理盐水浸提液0.5~5000μg/皿剂量下Ames试验结果阴性;250~1000μg/mL剂量下对CHL细胞无损伤作用,10~40g/kg剂量下对小鼠骨髓细胞染色体无致畸变作用。结论浮海石无致突变作用,用于临床是安全的。     

长春西汀的致突变研究

检测长春西汀是否有致突变作用。方法：要用Ａｍｅｓ试验,小鼠微核试验及哺乳动物培养细胞染色体畸变试验观察长春西汀的诱导性。结果：Ａｍｅｓ试验,微核试验及染色体畸变试验结果为阴性,结论：长春西汀在所试条件下未见致突变作用。     

白障明的诱变性试验研究

作者用鼠伤寒沙门氏菌回变试验,小鼠骨髓红细胞微核试验及CHL细胞染色体畸变试验,对白障明进行了诱变性试验研究。结果表明鼠伤寒沙门氏菌回变试验为阴性,该药可能不诱发基因突变,NIH小鼠骨髓红细胞微核试验及CHL细胞染色体畸变试验均为阴性,说明该药可能不诱发体内,体外染色体损伤作用。     

Genotoxic and antigenotoxic evaluation of extracts from Arenosclera brasiliensis, a Brazilian marine sponge

The marine environment is a rich source of biological active compounds and the sponges can be considered the most productive one. This diversity gives rise to unique chemical compounds with potential pharmacological properties. Our study is focused on the genotoxic and antigenotoxic evaluation of two crude extracts obtained from the Brazilian endemic marine sponge Arenosclera brasiliensis. Salmonella typhimurium reverse mutation test with TA97, TA98, TA100 and TA102 strains were performed. For antimutagenic analysis, a pre-, co-, and post-treatment to evaluate, respectively, intracellular and extracellular reactions and possible modulation on DNA repair. Additionally, in order to verify the influence of the crude extracts on DNA damage induction, a plasmid-DNA treatment was assayed. No mutagenicity was observed in Salmonella reverse mutation test, neither DNA strand induced damage. Antimutagenic activity was observed in pre-, co-, and post-treatment. A significant antigenotoxic effect was observed in the crude extract, which suggests that A. brasiliensis extract has the potential to protect DNA from the action of 4NQO, 2-aminofluorene, sodium azide and mitomycin C.     

The organospecific activity of metronidazole and azanidazole in the intrasanguineous host-mediated assay

The genotoxicity of nitroimidazoles and, in particular, their potential carcinogenicity has been demonstrated. In order to investigate the specific target organ(s) for these drugs or their metabolites, a method for measuring mutations in microorganisms, with reference to the metabolism of mammals, was used in mice. Metronidazole and azanidazole were tested for their ability to induce genetic effects in a diploid strain (D7) of Saccharomyces cerevisiae in the Intrasanguineous Host-Mediated Assay. The test compounds showed dose-related increases of point mutation and mitotic gene conversion frequencies in liver, kidney and lung. Azanidazole seemed to favour the kidney and the liver, although increases in genotoxicity were observed also in the lung. Metronidazole was toxic and induced both point mutation and mitotic gene conversion when recovered from the liver. Yeast recovered from the kidney and the lung showed an increase especially in point mutation. This work provides more information about the mechanisms involved in the mutagenicity of nitroimidazoles at the site of action.     

Knockout Corner: 5-HT(1A) receptor inactivation: anxiety or depression as a murine experience

5-HT(1A) receptors play a critical role in the pathophysiology of anxiety and depression as well as in the mode of action of anxiolytic and antidepressant drugs. Mice with a targeted inactivation of the 5HT(1A) receptor show a phenotype that is associated with a gender-modulated and gene/dose-dependent increase of anxiety-related and antidepressant-like behaviours. Since this behavioural phenotype was observed in animals in which the mutation was bred into mice of different genetic backgrounds, 5-HT(1A) receptor knockout mice represent a useful model system for advanced investigations of 5-HT(1A) genotype/phenotype interaction.     

化学诱变技术在微生物育种研究中的应用

化学诱变是一种传统而经典的微生物育种技术,不仅在高产工业菌株选育中得到广泛应用,而且近来还用于改造野生菌株代谢功能,以发现新产活性产物。本文简要综述常用化学诱变剂及其作用机制,以及化学诱变技术在微生物育种领域中的新近应用研究进展。     

Dual mode of stimulation by the beta-carboline ZK 91085 of recombinant GABA(A) receptor currents: molecular determinants affecting its action.

In electrophysiological measurements the beta-carboline ethyl 6-benzyloxy-beta-carboline-3-carboxylate (ZK 91085) acts as a positive allosteric modulator on rat recombinant alpha1beta2gamma2 GABA(A) receptors and binds with high affinity (IC50-1.5 nM) to the [3H]-flunitrazepam site. Flumazenil was able to partially counteract the current modulation. These observations indicate an action of ZK 91085 at the benzodiazepine binding site. At the dual subunit combination alpha1beta2, which lacks the gamma subunit required for benzodiazepine modulation, we still observed a potentiation of GABA currents. Thus ZK 91085 acts via an additional site on the channel. At the subunit combination alpha1beta1, ZK 91085 potentiation is strongly reduced as compared to alpha1beta2. In binding studies, ZK 91085 was able to decrease [35S]-TBPS binding in alpha1beta2gamma2 and alpha1beta2 but not in alpha1beta1. This selectivity of ZK 91085 for receptors containing the beta2 isoform over those containing the beta1 isoform is reminiscent of the action of loreclezole. To identify amino acid residues important for the second type of modulation, we functionally compared wild type alpha1beta2 and mutant receptors for stimulation by ZK 91085. The mutation beta2N265S, that abolishes loreclezole effects, also abolishes ZK 91085 stimulation. The mutation beta2Y62L increased stimulation by ZK 91085 3-4 fold, locating an influencing entity of the second type of action of ZK 91085 at an alpha/beta subunit interface. Structural intermediates of ZK 91085 and the beta-carboline abecarnil, the latter of which only slightly potentiated GABA currents in alpha1/beta2, were analysed to determine structural requirements for modulation. ZK 91085 thus allosterically stimulates the GABA(A) receptor through two sites of action: the benzodiazepine site and the loreclezole site in contrast to classical beta-carbolines, that confer negative allosteric modulation through the benzodiazepine site.     

Probing the interaction of the cytotoxic bisdioxopiperazine ICRF-193 with the closed enzyme clamp of human topoisomerase IIalpha

Topoisomerase II is an ATP-operated protein clamp that captures a DNA helix and transports it through another DNA duplex, allowing chromosome segregation at mitosis. A number of cytotoxic bisdioxopiperazines such as ICRF-193 target topoisomerase II by binding and trapping the closed enzyme clamp. To investigate this unusual mode of action, we have used yeast to select plasmid-borne human topoisomerase IIalpha alleles resistant to ICRF-193. Mutations in topoisomerase IIalpha of Leu-169 to Phe (L169F) (in the N-terminal ATPase domain) and Ala-648 to Pro (A648P) (in the core domain) were identified as conferring >50-fold and 5-fold resistance to ICRF-193 in vivo, respectively. The L169F mutation, located next to the Walker A box ATP-binding sequence, resulted in a mutant enzyme displaying ICRF-193-resistant topoisomerase and ATPase activities and whose closed clamp was refractory to ICRF-193-mediated trapping as an annulus on closed circular DNA. These data imply that the mutation interferes directly with ICRF-193 binding to the N-terminal ATPase gate. In contrast, the A648P enzyme displayed topoisomerase activities exhibiting wild-type sensitivity to ICRF-193. We suggest that the inefficient trapping of the A648P closed clamp results either from the observed increased ATP requirement, or more likely, from lowered salt stability, perhaps involving destabilization of ICRF-193 interactions with the B'-B' interface in the core domain. These results provide evidence for at least two different phenotypic classes of ICRF-193 resistance mutations and suggest that bisdioxopiperazine action involves the interplay of both the ATPase and core domains of topoisomerase IIalpha.     

Difficidin and oxydifficidin: novel broad spectrum antibacterial antibiotics produced by Bacillus subtilis. III. Mode of action of difficidin

The mode of action of difficidin (DIF) was investigated. Upon addition of DIF to log phase cultures of Escherichia coli, growth ceased immediately and small round cells accumulated after 30 minutes incubation. No cell lysis was observed. DIF was rapidly bactericidal to both growing and stationary phase cultures, and inhibited protein synthesis more rapidly than RNA, DNA, or cell-wall synthesis in growing cells. Protein synthesis was also inhibited in a cell-free system. The frequency of natural mutation to resistance in E. coli was less than 1 in 10(10) cells.     

Sites in the fourth membrane-associated domain regulate alcohol sensitivity of the NMDA receptor

N-methyl-D-aspartate (NMDA) receptors are important target sites of alcohol action in the central nervous system. Alcohol inhibits NMDA receptor current by an action on ion channel gating, apparently through a direct action on a region of the NMDA receptor accessible from the extracellular environment. Our previous studies have revealed an important role for a methionine residue (Met823) in membrane-associated domain 4 (M4) of the NR2A subunit in channel gating as well as alcohol sensitivity of the NMDA receptor. The role of sites in M4 of the NMDA receptor NR2A subunit adjacent to Met823 was investigated using tryptophan-scanning mutagenesis and electrophysiological recording. Receptors containing NR1 and NR2A(V820W) or NR2A(M817W) mutant subunits expressed in HEK 293 cells were not functional. The mutation Ala826Trp modified apparent desensitization, and the mutations Ala825Trp and Ala826Trp changed the mean open time of the channel as determined by fluctuation analysis. In addition, the mutations Tyr822Trp and Ala825Trp significantly altered the concentration-response curves for ethanol inhibition. The changes in mean open time did not appear to be able to account for the observed differences in ethanol sensitivity. These results indicate that this region in M4 of the NR2A subunit may be involved in the action of alcohol.     

The effect of autonomous alpha-CaMKII expression on sensory responses and experience-dependent plasticity in mouse barrel cortex.

The calcium/calmodulin kinase II (CaMKII) autophosphorylation site is thought to be important for plasticity, learning and memory. If autophosphorylation is prevented by a point mutation (T286A) LTP is blocked in the hippocampus and cortex. Conversely, if the point mutation mimics autophosphorylation (T286D) a range of frequencies that normally produce LTP in wild types cause LTD instead. In order to test whether the alphaCaMKII-T286D mutation increases levels of depression in vivo, we examined the effect of the alphaCaMKII-T286D transgene on plasticity induced in the barrel cortex by whisker deprivation. Surprisingly, the mutation did not affect depression or potentiation. However, in animals reared with the transgene turned on from birth, the surround receptive field responses were greater than normal. This effect may be due to the potentiating action of autophosphorylated CaMKII during early development.