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Antimutagenic and antitumorigenic activities of nordihydroguaiaretic acid.   总被引:5,自引:0,他引:5  
Nordihydroguaiaretic acid (NDGA), which occurs in the resinous exudates of many plants is used as an antioxidant in fats and oils. In this study we show that NDGA inhibited the mutagenicity of methyl methanesulfonate, benzo[a]pyrene (BP), 2-aminofluorene, and aflatoxin B1 in Salmonella typhimurium strain TA100 or TA98 in the absence and presence of rat hepatic microsomal activation system. The addition of NDGA during and after nitrosation of methylurea (MU) resulted in a dose-dependent inhibition of mutagenicity induced by nitrosation products of MU. In a two-stage skin tumorigenesis protocol using 7,12-dimethylbenz[a]anthracene (DMBA) as the initiating agent followed by twice weekly applications of 12-O-tetradecanoylphorbol-13-acetate (TPA) as tumor promoter, pretreatment of animals with NDGA prior to DMBA application, afforded significant protection against skin tumorigenicity in female SENCAR mice. In additional studies, skin application of NDGA also inhibited the binding of topically applied [3H]BP and [3H]DMBA to epidermal DNA. When assessed in the anti-tumor promotion protocol, pretreatment of animals with NDGA before each application of TPA in DMBA-initiated mouse skin, resulted in 72% decrease in the total number of tumors when compared to non-NDGA pretreated animals. The possible mechanism(s) of the antimutagenic and anti-tumorigenic activities may be due to the multiple effects of NDGA as inhibitor of the carcinogen metabolism and DNA-adduct formation, scavenger of carcinogen free radicals, and as inhibitor of TPA-induced ornithine decarboxylase activity.  相似文献   
23.
Three new species of Ancistrohaptor n. g. are described from the gills of three species of Triportheus (Characidae) collected from the environs of Manaus, Amazonas, Brazil: A. falcatum n. sp. from T. elongatus; and A. falciferum n. sp. and A. falcunculum n. sp. from T. angulatus, T. albus and T. elongatus. Ancistrohaptor n. g. is proposed for species possessing overlapping gonads, a dextral or dextroventral vaginal aperture, a coiled (counter-clockwise) male copulatory organ, two accessory pieces in the copulatory complex, and a haptor armed with two pairs of anchors (ventral anchor with elongate shaft), dorsal and ventral bars and 14 hooks; hook pair 1 (ventral) anterior to ventral bar, pairs 2–4 (ventral) lying bilaterally anterior to ventral anchor bases, pair 5 (ventral) associated with distal end of ventral anchor shafts, and pairs 6 and 7 (dorsal) bilateral about midway along haptoral length. Parasite-host and host-parasite lists of the Ancyrocephalinae from neotropical Characiformes are provided.  相似文献   
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We describe a new class of reagents for identifying substrates, adaptors, and regulators of HECT and RING E3s. UBAITs (Ub iquitin‐A ctivated I nteraction T raps) are E3‐ubiquitin fusion proteins and, in an E1‐ and E2‐dependent manner, the C‐terminal ubiquitin moiety forms an amide linkage to proteins that interact with the E3, enabling covalent co‐purification of the E3 with partner proteins. We designed UBAITs for both HECT (Rsp5, Itch) and RING (Psh1, RNF126, RNF168) E3s. For HECT E3s, trapping of interacting proteins occurred in vitro either through an E3 thioester‐linked lariat intermediate or through an E2 thioester intermediate, and both WT and active‐site mutant UBAITs trapped known interacting proteins in yeast and human cells. Yeast Psh1 and human RNF126 and RNF168 UBAITs also trapped known interacting proteins when expressed in cells. Human RNF168 is a key mediator of ubiquitin signaling that promotes DNA double‐strand break repair. Using the RNF168 UBAIT, we identify H2AZ—a histone protein involved in DNA repair—as a new target of this E3 ligase. These results demonstrate that UBAITs represent powerful tools for profiling a wide range of ubiquitin ligases.  相似文献   
26.
Three pathogenic strains of Pseudomonas phaseolicola (strain 1 and 3 virulent and strain 5 weakly virulent) were tested for their toxic activity. All three strains produced detectable amounts of toxin in vitro. Cultural conditions and length of incubation greatly influenced toxin production. Maximum amount of toxin was produced at 20°C and pH 6.5. Glycerol served as the best carbon source and 1-cysteine as the best amino acid for toxin production.  相似文献   
27.
As part of the development of carbon-coated prosthetic devices, the adhesion of thin carbon films to metallic substrates has been studied. The bond strength of carbon films about 5000 A thick on Ti-6A1-4V and stainless steel was measured in a pull test and found to be greater than 4700 psi. Auger electron spectroscopy showed a reactive film/substrate interface. The ultimate bond strength was found to be dependent on the substrate and the deposition parameters.  相似文献   
28.
Green capping is one of the popular methods to re-vegetate abandoned ash ponds of coal based thermal power plants thereby lowering the risk of contamination to the surrounding environment. It has innumerable advantages such as prevention of dust emission, checking soil erosion, stabilizing the surface areas of ash, preventing potential ground water contamination, and finally, adding native vegetation cover, which is very vital in the long term. During the early nineties and later, various reclamation projects were carried out on fly ash dumps, but until date, there have not been any initiatives to assess the alterations in physicochemical and biological properties of fly ash resulting from implementation of these reclamation projects. In the present study, three abandoned ash ponds, located in India, that were reclaimed during 1998–2003 are investigated. Marked alterations in nutritional status, microbial population, and microbial activities have been observed in reclaimed ash ponds.  相似文献   
29.
We evaluated the status of 16 of 22 recognized Sri Lankan Cnemaspis Strauch species, and flagged overlooked diversity with two mitochondrial (cyt b & ND2) and two nuclear markers (RAG1 & PDC) totalling 2829 base pairs. A fossil-calibrated timetree and sampling of other South Asian Cnemaspis provide insights into the diversification of the genus in peninsular India and Sri Lanka. Phylogenetic analyses consistently inferred two broad clades within South Asian Cnemaspis, with Sri Lankan species in two clades, which we call the podihuna and kandiana clades. Each Sri Lankan clade as a whole is sister to Indian taxa and nested within Indian lineages. Cnemaspis modigliani Das from Indonesia is a member of the kandiana clade. This suggests a minimum of two dispersal events between India and Sri Lanka and one between Sri Lanka/India and South-east Asia. South Asian Cnemaspis date back to at least the Eocene, in Sri Lanka to the early Miocene, with late Miocene diversification in the kandiana clade. All but one of the named species we sampled is likely to be valid, and 10 divergent unnamed lineages may warrant specific recognition. A resolution of Sri Lankan Cnemaspis taxonomy will require thorough sampling and the use of both morphological and molecular data.  相似文献   
30.
A cell line, CTE, derived from catla (Catla catla) thymus has been established by explant method and subcultured for more than 70 passages over a period of 400 days. The cell line has been maintained in L-15 (Leibovitz) medium supplemented with 10% fetal bovine serum. CTE cell line consists of homogeneous population of epithelial-like cells and grows optimally at 28 °C. Karyotype analysis revealed that the modal chromosome number of CTE cells was 50. Partial amplification, sequencing and alignment of fragments of two mitochondrial genes 16S rRNA and COI confirmed that CTE cell line originated from catla. Significant green fluorescent signals were observed when the cell line was transfected with phrGFP II-N mammalian expression vector, indicating its potential utility for transgenic and genetic manipulation studies. The CTE cells showed strong positivity for cytokeratin, indicating that cell line was epithelial in nature. The flow cytometric analysis of cell line revealed a higher number of cells in S-phase at 48 h, suggesting a high growth rate. The extracellular products of Vibrio cholerae MTCC 3904 were toxic to the CTE cells. This cell line was not susceptible to fish betanodavirus, the causative agent of viral nervous necrosis in a large variety of marine fish.  相似文献   
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