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131.
132.
In order to initiate studies on chemical carcinogenesis in an in vitro system analogous to mouse epidermis, primary epidermal cell cultures from perinatal mouse skin were established. A standardized method for the large-scale isolation of epidermal cells from late embryonic or newborn mouse dorsal skin has been developed. The epidermal cells were separated from fibroblasts by two series of discontinuous Ficoll density gradients. Using 80 to 100 animals/experiment, an average yield of 3×106 viable epidermal cells/animal was obtained. The viability of the purified cell suspension exceeded 85%, and the plating efficiency, representing the growing cell fraction 24 h after plating, was about 43%.The cultures started as epithelial monolayers without fibroblast contamination. Their epidermal nature and origin was proved immunologically by an in vivo absorbed rabbit anti-mouse epidermis antiserum. The purity of the epidermal cells was quantitatively determined in trypsinized suspensions by the indirect immunofluorescence test yielding more than 95% epidermal antigen-positive cells. About half of the remaining antigen-negative cells could be identified as melanocytes. These highly purified epidermal cells grew in vitro for 2–3 weeks without dermal constituents or diffusible mesenchymal factors. The monolayers differentiated in culture giving rise to keratinizing cell sheets on top of the proliferating basal layer. By morphological, histochemical and physical methods, it could be evidenced that the differentiation processes in vitro are quite similar to keratinization in vivo. 相似文献
133.
134.
Elham Yezdani Jalal Jalali Sendi Arash Zibaee Mohammad Ghadamyari 《Comptes rendus biologies》2010,333(1):17-22
The pyralid moth, Glyphode pyloalis Walker, is an important pest of the mulberry. Amylases are the hydrolytic enzymes that catalyze the hydrolysis of the α-D-(1,4)-glucan linkage in glycogen and other related carbohydrates. Laboratory-reared fifth stadium larvae were randomly selected; the midgut (MG) and the salivary glands (SG) were removed by dissection under a dissecting microscope and α-amylase activity was assayed using the dinitrosalicylic acid procedure. The activity of α-amylase in the MG and the SG were 0.011 and 0.0018 μmol/min, respectively. The optimal pH and temperature for α-amylase were 9 for MG at 37–40 °C and 10 for SG at 37 °C respectively. Various concentrations of compounds (NaCl, KCl, MgCl2, Urea, EDTA, SDS and CaCl2) had differential effects on the enzyme activity. Plant amylase inhibitors may play an important role against insect pests. Hence, the characterization of digestive enzymes and the examination of their inhibitors may be a useful tool in future management of this important mulberry pest. 相似文献
135.
Airong Liu Shuangchen Chen Rui Chang Dilin Liu Haoran Chen Golam Jalal Ahammed Xiaomin Lin Chaoxing He 《Journal of plant research》2014,127(6):775-785
The combined effects of arbuscular mycorrhizal fungi (AMF) and low temperature (LT) on cucumber plants were investigated with respect to biomass production, H2O2 accumulation, NADPH oxidase, ATPase activity and related gene expression. Mycorrhizal colonization ratio was gradually increased after AMF-inoculation. However, LT significantly decreased mycorrhizal colonization ability and mycorrhizal dependency. Regardless of temperature, the total fresh and dry mass, and root activity of AMF-inoculated plants were significantly higher than that of the non-AMF control. The H2O2 accumulation in AMF-inoculated roots was decreased by 42.44 % compared with the control under LT. H2O2 predominantly accumulated on the cell walls of apoplast but was hardly detectable in the cytosol or organelles of roots. Again, NADPH oxidase activity involved in H2O2 production was significantly reduced by AMF inoculation under LT. AMF-inoculation remarkably increased the activities of P-type H+-ATPase, P-Ca2+-ATPase, V-type H+-ATPase, total ATPase activity, ATP concentration and plasma membrane protein content in the roots under LT. Additionally, ATP concentration and expression of plasma membrane ATPase genes were increased by AMF-inoculation. These results indicate that NADPH oxidase and ATPase might play an important role in AMF-mediated tolerance to chilling stress, thereby maintaining a lower H2O2 accumulation in the roots of cucumber. 相似文献
136.
Aspergilli are filamentous, cosmopolitan and ubiquitous fungi which have significant impact on human, animal and plant welfare worldwide. Due to their extraordinary metabolic diversity, Aspergillus species are used in biotechnology for the production of a vast array of biomolecules. However, little is known about Aspergillus species that are able to adapt an endophytic lifestyle in Cupressaceae plant family and are capable of producing cytotoxic, antifungal and antibacterial metabolites. In this work, we report a possible ecological niche for pathogenic fungi such as Aspergillus fumigatus and Aspergillus flavus. Indeed, our findings indicate that A. fumigatus, A. flavus, Aspergillus niger var. niger and A. niger var. awamori adapt an endophytic lifestyle inside the Cupressaceous plants including Cupressus arizonica, Cupressus sempervirens var. fastigiata, Cupressus semipervirens var. cereiformis, and Thuja orientalis. In addition, we found that extracts of endophytic Aspergilli showed significant growth inhibition and cytotoxicity against the model fungus Pyricularia oryzae and bacteria such as Bacillus sp., Erwinia amylovora and Pseudomonas syringae. These endophytic Aspergilli also showed in vitro antifungal effects on the cypress fungal phytopathogens including Diplodia seriata, Phaeobotryon cupressi and Spencermartinsia viticola. In conclusion, our findings clearly support the endophytic association of Aspergilli with Cupressaceae plants and their possible role in protection of host plants against biotic stresses. Observed bioactivities of such endophytic Aspergilli may represent a significant potential for bioindustry and biocontrol applications. 相似文献
137.
Trichoderma fungal species are universal soil residents that are also isolated from decaying wood, vegetables, infected mushroom and immunocompromised patients. Trichoderma species usually biosynthesize a plethora of secondary metabolites. In an attempt to explore endophytic fungi from healthy foliar tissues of the plant family Cuppressaceae, we explored Cupressus arizonica, C. sempervirens var. cereiformis, C. sempervirens var. fastigiata, C. sempervirens var. horizontalis, Juniperus excelsa, Juniperus sp. and Thuja orientalis plants and recovered several endophytic Trichoderma fungal strains from Trichoderma atroviride and Trichoderma koningii species. We found that the host plant species and biogeographical location of sampling affected the biodiversity and bioactivity of endophytic Trichoderma species. Furthermore, the bioactivity of Trichoderma isolates and the methanol extracts of their intra- and extra-cellular metabolites were assessed against a panel of pathogenic fungi and bacteria. Fungal growth inhibition, conidial cytotoxicity, minimum inhibitory concentration and minimum bactericidal concentration were evaluated and analyzed by statistical methods. Our data showed that both intra- and extracellular secondary metabolites from all endophytic isolates had significant cytotoxic and antifungal effects against the model target fungus Pyricularia oryzae and the cypress fungal phytopathogens Diplodia seriata, Phaeobotryon cupressi and Spencermartinsia viticola. Further research indicated their significant antimicrobial bioactivity against the model phytopathogenic bacteria Pseudomonas syringae, Erwinia amylovora and Bacillus sp., as well. Altogether, the above findings show for the first time the presence of T. atroviride and T. koningii as endophytic fungi in Cupressaceae plants and more importantly, the Trichoderma isolates demonstrate significant bioactivity that could be used in future for agrochemical/drug discovery and pathogen biocontrol. 相似文献
138.
Radioprotective effects of hawthorn against genotoxicity induced by gamma irradiation in human blood lymphocytes 总被引:1,自引:0,他引:1
Hosseinimehr SJ Mahmoudzadeh A Azadbakht M Akhlaghpoor S 《Radiation and environmental biophysics》2009,48(1):95-98
The radioprotective effect of hawthorn (Crataegus microphylla) fruit extract was investigated in cultured blood lymphocytes from human volunteers. Peripheral blood samples were collected
from five human volunteers 10 min before and 1, 2 and 3 h after a single oral ingestion of 500 mg hawthorn powder extract.
At each time point, the whole blood was exposed in vitro to 150 cGy of cobalt-60 gamma irradiation, and then the lymphocytes
were cultured with mitogenic stimulation to determine the micronuclei in cytokinesis-blocked binucleated cell. The lymphocytes
in the blood samples collected after extract ingestion exhibited a significant decrease in the incidence of binucleated cells
containing micronuclei as compared to similarly irradiated lymphocytes collected prior to extract ingestion. The maximum decrease
in the frequency of micronuclei-containing cells was observed at 1 h after ingestion of Hawthorn extract (on average a 44%
decrease). These data suggest that it may be possible to use Hawthorn extracts in personnel exposed to radiation in order
to protect lymphocytes from radiation effects. 相似文献
139.
Diane Fournier Jalal Hawari Sheryl H. Streger Kevin McClay Paul B. Hatzinger 《Applied microbiology》2006,72(10):6693-6698
N-Nitrosodimethylamine (NDMA) is a potent carcinogen and an emerging contaminant in groundwater and drinking water. The metabolism of NDMA in mammalian cells has been widely studied, but little information is available concerning the microbial transformation of this compound. The objective of this study was to elucidate the pathway(s) of NDMA biotransformation by Pseudomonas mendocina KR1, a strain that possesses toluene-4-monooxygenase (T4MO). P. mendocina KR1 was observed to initially oxidize NDMA to N-nitrodimethylamine (NTDMA), a novel metabolite. The use of 18O2 and H218O revealed that the oxygen added to NDMA to produce NTDMA was derived from atmospheric O2. Experiments performed with a pseudomonad expressing cloned T4MO confirmed that T4MO catalyzes this initial reaction. The NTDMA produced by P. mendocina KR1 did not accumulate, but rather it was metabolized further to produce N-nitromethylamine (88 to 94% recovery) and a trace amount of formaldehyde (HCHO). Small quantities of methanol (CH3OH) were also detected when the strain was incubated with NDMA but not during incubation with either NTDMA or HCHO. The formation of methanol is hypothesized to occur via a second, minor pathway mediated by an initial α-hydroxylation of the nitrosamine. Strain KR1 did not grow on NDMA or mineralize significant quantities of the compound to carbon dioxide, suggesting that the degradation process is cometabolic. 相似文献
140.