Silica gel medium to detect molds that produce aflatoxin.

A chemically defined nutrient solution containing tartaric acid was made solid by mixing it with an alkaline silicate solution. Production of aflatoxin by asperfilli growing on the silica gel medium coincided with the presence of a blue fluorescent area surrounding colonies, as observed under long-wave ultraviolet light. Presence of aflatoxin in the medium was confirmed by drying the gels, extracting them with chloroform-methanol, and examining extracts for fluorescent materials by viewing them on thin-layer chromatograms under ultraviolet light.     

Histofluorescence technique for the intracellular localization of chemical carcinogens

Summary Many carcinogens exhibit a fluorescent emission when excited with ultraviolet light. Advantage has been taken of this property to develop a technique that can detect microquantities of these carcinogens on conventional microscopic tissue preparations. This work describes the localization of aflatoxin B₁, N-2-fluorenylacetamide and benzo(a)pyrene both in the cell cytoplasm and nucleus afterin vivo administration of these compounds.     

Rapid Method for Detection of Pseudomonas aeruginosa on MacConkey Agar Under Ultraviolet Light

A simple screening technique for the detection of Pseudomonas aeruginosa colonies by their fluorescence on MacConkey agar under ultraviolet light is proposed. From 306 nonlactose fermenting cultures screened under the ultraviolet light, 108 fluorescent isolates were obtained. These were screened biochemically, with 103 (94.8%) being verified as P. aeruginosa. From the 198 nonfluorescing cultures, only one suspected P. aeruginosa was isolated.     

Fluorescent-light-induced lethality and DNA repair in normal and xeroderma pigmentosum fibroblasts

Cell survival and induction of endonuclease-sensitive sites in DNA were measured in human fibroblast cells exposed to fluorescent light or germicidal ultraviolet light. Cells from a xeroderma pigmentosum patient were hypersensitive to cell killing by fluorescent light, although less so than for germicidal ultraviolet light. Xeroderma pigmentosum cells were deficient in the removal of fluorescent light-induced endonuclease sites that are probably pyrimidine dimers, and both the xeroderma pigmentosum and normal cells removed these sites with kinetics indistinguishable from those for ultraviolet light-induced sites. A comparison of fluorescent with ultraviolet light data demonstrates that there are markedly fewer pyrimidine dimers per lethal event for fluorescent than for ultraviolet light, suggesting a major role for non-dimer damage in fluorescent light lethality.     

Effect of climate and type of storage container on aflatoxin production in corn and its associated risks to wildlife species

The effects of grain storage containers on aflatoxin production, and the relationship between the level of aflatoxin and the number and weight of fluorescing kernels were determined in corn (Zea maize) stored in controlled climate regimes. Two hundred and forty 100-g samples were held up to 3 mos using four types of storage containers placed in four climates. Storage containers included corn placed in metal cans, paper bags, plastic bags, and paper bags placed in plastic bags. Climates were constant during the duration of the project and included a combination of temperatures and humidities. Temperatures were 29-32 C and 14-18 C; relative humidities were 85-88% and 35-40%. In addition, corn was exposed to environmental conditions conductive for aflatoxin production and 100 g samples were randomly collected, examined under ultraviolet light for fluorescence, and then quantified for aflatoxin levels. Corn samples tested negative for aflatoxin at the beginning of the project. Main (i.e., container, climate, and month) and interactive effects were not observed. Mean levels of aflatoxin ranged from 0 to 151 microg/kg. Aflatoxin was produced regardless of type of storage container, time of storage, and climatic conditions; however, only 8% of the samples produced aflatoxin levels that exceeded 50 microg/kg. Fluorescing corn ranged from 0 to 19 kernels per sample, while aflatoxin levels ranged from 0 to 1,375 microg/kg for the same samples. No relationships were found between the number and weight of fluorescing kernels of corn and aflatoxin levels. The black light test yielded a false negative rate of 23% when in fact the aflatoxin concentrations exceeded 50 microg/kg. Therefore, quantifying fluorescing grain under UV light should not be considered a feasible alternative for aflatoxin testing of grain intended for wildlife.     

Synthesis,spectral properties and antimicrobial activity of a new cationic water‐soluble pH‐dependent poly(propylene imine) dendrimer modified with 1,8‐naphthalimides

A three‐step synthesis was implemented to prepare a quaternary ammonium functionalized blue fluorescent poly(propylene imine) dendrimer modified with pyridinium salt of 4‐acylamino‐1,8‐naphthalimide. The new cationic dendrimer absorbs in the ultraviolet light region and emits blue fluorescence. Its spectral characteristics in organic solvents and in an aqueous solution were studied. The influence of pH on the fluorescence intensity of the dendrimer was established with regard to its use as a pH sensor. The effect of hydroxyl ions on the absorption and fluorescence spectra in dry N,N‐dimethylformamide was also investigated. The antimicrobial activity of the dendrimer was assessed against model pathogenic microorganisms in agar, liquid medium, and after its deposition on cotton fabric.     

Factors influencing survival of mammalian cells exposed to hypothermia. V. Effects of hepes, free radicals, and H2O2 under light and dark conditions

Cytotoxicity resulting from the interaction of fluorescent light from a flow hood with Hepes-buffered cell culture medium at room temperature was demonstrated. Toxicity was prevented by keeping both cells (V79 Chinese hamster) and medium shielded from direct fluorescent light ("dark conditions") or by supplementing the medium with 10 micrograms/ml catalase; this suggests that extracellular hydrogen peroxide is a major cause of the lethal effect under "lighted conditions." No sensitization resulted from the exposure of cells in a sodium bicarbonate (SBC)-buffered medium to fluorescent light, nor in a catalase supplemented SBC-buffered medium. The Hepes/light reaction during routine cell manipulations presensitized cells to hypothermia damage in the dark with the presensitization being more severe for 5 than for 10 degrees C hypothermic exposure. Presensitization was prevented by performing the complete experiment under dark conditions or by supplementing the medium with 10 micrograms/ml catalase. However, catalase did not improve the hypothermic survival when experiments were performed under dark conditions. Hence, 10 micrograms/ml catalase does not protect cells from hypothermic (5 and 10 degrees C) damage per se, but rather from Hepes/light sublethal damage which interacts with hypothermic sublethal damage to result in lethal lesions. Additionally, under dark conditions, superoxide dismutase (SOD), allopurinol, catalase plus SOD, DMSO, or mannitol did not improve survival when present during hypothermic storage, suggesting that extracellular superoxide anion, hydrogen peroxide, or hydroxyl radicals are not the cause of cell killing under conditions of pure hypothermia uncomplicated by prehypothermic ischemia or hypoxia.     

Direct visual detection of aflatoxin synthesis by minicolonies of Aspergillus species

Single-spore colonies of Aspergillus flavus and Aspergillus parasiticus, grown for 4 to 5 days at 25 degrees C on a coconut extract agar containing sodium desoxycholate as a growth inhibitor, produced aflatoxin, readily detectable as blue fluorescent zones under long-wave (365 nm) UV light. Over 100 colonies per standard petri dish were scored for aflatoxin production by this procedure. Progeny from some strains remained consistently stable for toxin production after repeated subculture, whereas instability for toxin synthesis was revealed among progeny from other strains. Spore color markers were used to rule out cross-contamination in monitoring strains. A yellow-spored and nontoxigenic strain of A. flavus, reported previously to produce aflatoxin in response to cycloheximide treatment, proved to be toxin negative even after repeated exposure to cycloheximide. Extended series of progeny from another strain of A. flavus and from a strain of A. parasiticus were each compared by this plating procedure and by fluorometric analysis for aflatoxin when grown in a coconut extract broth. Both of these strains showed variation for toxin synthesis among their respective progeny, and specific progeny showed a good correlation for aflatoxin synthesis when examined by the two procedures.     

Direct visual detection of aflatoxin synthesis by minicolonies of Aspergillus species.

Single-spore colonies of Aspergillus flavus and Aspergillus parasiticus, grown for 4 to 5 days at 25 degrees C on a coconut extract agar containing sodium desoxycholate as a growth inhibitor, produced aflatoxin, readily detectable as blue fluorescent zones under long-wave (365 nm) UV light. Over 100 colonies per standard petri dish were scored for aflatoxin production by this procedure. Progeny from some strains remained consistently stable for toxin production after repeated subculture, whereas instability for toxin synthesis was revealed among progeny from other strains. Spore color markers were used to rule out cross-contamination in monitoring strains. A yellow-spored and nontoxigenic strain of A. flavus, reported previously to produce aflatoxin in response to cycloheximide treatment, proved to be toxin negative even after repeated exposure to cycloheximide. Extended series of progeny from another strain of A. flavus and from a strain of A. parasiticus were each compared by this plating procedure and by fluorometric analysis for aflatoxin when grown in a coconut extract broth. Both of these strains showed variation for toxin synthesis among their respective progeny, and specific progeny showed a good correlation for aflatoxin synthesis when examined by the two procedures.     

A novel method for non-invasive detection of aflatoxin contaminated dried figs with deep transfer learning approach

Aflatoxins are the most dangerous mycotoxin produced by Aspergillus fungal species, such as Aspergillus flavus and Aspergillus parasiticus, and can cause various health problems, including liver cancer, in humans. Figs and many agricultural products are affected by aflatoxins. It is crucial to detect it before consumption since it is impossible to clean aflatoxin from contaminated foods. Chromatographic methods are considered the gold standard for aflatoxin detection, but these methods are pretty expensive, time-consuming, and destructive. Therefore, various studies have been conducted on non-invasive aflatoxin detection using optical spectroscopic methods. Specifically, aflatoxin-contaminated figs are sorted manually by employees in production facilities using the Bright Greenish Yellow Fluorescence (BGYF) method under ultraviolet (UV) light. However, accurate and safe manual sorting depends on expertise of employees, along with this long exposure time to UV radiation may cause employees skin cancer and eye disorders. This study presents a deep transfer learning-based approach for non-invasive detection and classification of aflatoxin-contaminated dried figs using images captured under UV light. Pre-trained transfer learning models, such as DenseNet, ResNet, VGG, and InceptionNet, are applied to the dataset, but the accuracy of these models does not outperform the other methods that detect aflatoxin with the BGYF method. Therefore, fine-tuning is performed on the models. As a result, training accuracy of 98.57% and validation accuracy of 97.50% is obtained using the DenseNet169 model. The experimental results show that our proposed method achieves the highest accuracy among other methods. Also, the proposed method shows that deep CNN can be used to automatically, rapidly, and effectively detect aflatoxin-contaminated figs.     

The Effects of Light and Photo- and Protein-synthetic Inhibitors on the Sekiguchi Lesion Formation by Magnaporthe grisea in Rice cv. Sekiguchi-asahi*

The significance of light irradiation in Sekiguchi lesion (SL) formation by infection with Magnaporthe grisea on rice cv. Sekiguchi-asahi was investigated. When the leaf blades of cv. Sekiguchi-asahi inoculated with M. grisea spores were kept under different wavelengths of light. SLs were formed under visible light regardless of the compatibility between fungal race and cv. Sekiguchi-asahi. On the contrary, typical blast and/or nectrotic spot lesions were formed under near ultraviolet radiation from the black light fluorescent lamps and near infrared radiation from infrared fluorescent lamps. The effective wavelength for light-dependent SL formation was 400–700 nm. Furthermore, the longer the wavelength of radiation, the bigger were the SLs. Such light-dependent induction of the SL was suppressed by pretreatment of 3-(3,4-dichlorophenyl)-l,l-dimethylurea (DCMU) and cycloheximide (CY). These results suggested that photosynthetic and protein synthetic activities were involved in SL formation.     

Coconut as a Medium for the Experimental Production of Aflatoxin

Fresh, grated coconut has been found to be an excellent medium for aflatoxin production by Aspergillus flavus. Under optimal conditions, yields of 8 mg of total aflatoxin per g of substrate were obtained. Continuous agitation of the growth medium under moist conditions at 24 C produced highest yields. Aflatoxin was assayed both biologically and chromatographically. The aflatoxin content of cultures varied biphasically with the duration of incubation. It is suggested that this pattern could result from the sequential operation of factors promoting aflatoxin formation on the one hand and a detoxifying mechanism on the other.     

金桂与丹桂醇溶性色素的提取及其稳定性比较

用不同体积分数的乙醇从金桂和丹桂的花瓣中浸提所含的花色苷类色素,用光谱扫描法检测该色素的光吸收特性,比较不同乙醇体积分数、不同浸提时间对色素浸提效果的影响,并进行光敏感性试验和酸碱影响试验。结果显示,金桂和丹桂的花色素用体积分数90%的乙醇浸提具较高的浸出率;延长浸提时间可提高色素浸出率;紫外线直射可使色素的色度大幅度下降,日光灯和散射光也会导致色度在一定程度上的下降;色素在酸性溶液中具一定的稳定性,但在碱性溶液中表现出不稳定性。     

Substrate-induced lipase gene expression and aflatoxin production in Aspergillus parasiticus and Aspergillus flavus

AIMS: To establish a relationship between lipase gene expression and aflatoxin production by cloning the lipA gene and studying its expression pattern in several aflatoxigenic and nontoxigenic isolates of Aspergillus flavus and A. parasiticus. METHODS AND RESULTS: We have cloned a gene, lipA, that encodes a lipase involved in the breakdown of lipids from aflatoxin-producing A. flavus, A. parasiticus and two nonaflatoxigenic A. flavus isolates, wool-1 and wool-2. The lipA gene was transcribed under diverse media conditions, however, no mature mRNA was detected unless the growth medium was supplemented with 0.5% soya bean or peanut oil or the fungus was grown in lipid-rich medium such as coconut medium. The expression of the lipase gene (mature mRNA) under substrate-induced conditions correlated well with aflatoxin production in aflatoxigenic species A. flavus (SRRC 1007) and A. parasiticus (SRRC 143). CONCLUSIONS: Substrate-induced lipase gene expression might be indirectly related to aflatoxin formation by providing the basic building block 'acetate' for aflatoxin synthesis. No direct relationship between lipid metabolism and aflatoxin production can be ascertained, however, lipase gene expression correlates well with aflatoxin formation. SIGNIFICANCE AND IMPACT OF THE STUDY: Lipid substrate induces and promotes aflatoxin formation. It gives insight into genetic and biochemical aspects of aflatoxin formation.     

Sodium bicarbonate reduces viability and alters aflatoxin distribution of Aspergillus parasiticus in Czapek's agar

The potential of sodium bicarbonate to inhibit growth of and aflatoxin synthesis by Aspergillus parasiticus was examined in Czapek's agar (CA), a medium in which fluorescence under UV light indicates aflatoxin production. Incorporation of sodium bicarbonate (SB) into CA at 0.011, 0.022, and 0.033 mol% reduced cell viability 63-, 10(3)-, and greater than 10(7)-fold, respectively. Colonies resulting from surviving cells did not fluoresce under UV light, but thin-layer chromatography analysis of culture extracts detected aflatoxins. Potassium bicarbonate (KB) at 0.011 and 0.022 mol% produced inhibitory effects similar to those of SB, but NaCl and silica had no effect. After 7 days, control cultures had the normal aflatoxin distribution (B1 greater than G1 greater than B2 greater than G2), but this distribution shifted to B2 greater than B1 approximately equal to G2 greater than G1 during prolonged incubation. Cultures supplemented with SB and KB contained mostly aflatoxins B1 and G1 after 28 days. Both SB and KB raised the pH of CA to 7.5 to 8.5 at the time of growth. Culture growth on CA adjusted to pH 7.5 to 8.5 with NaOH was not inhibited but exhibited reduced fluorescence and elevated levels of aflatoxins B1 and G1. Thus, while bicarbonate inhibition of growth could not be attributed to pH elevation, the lack of culture fluorescence on CA-SB and CA-KB and the altered aflatoxin distribution were caused by the ability of SB and KB to elevate pH.     

Sodium bicarbonate reduces viability and alters aflatoxin distribution of Aspergillus parasiticus in Czapek's agar.

The potential of sodium bicarbonate to inhibit growth of and aflatoxin synthesis by Aspergillus parasiticus was examined in Czapek's agar (CA), a medium in which fluorescence under UV light indicates aflatoxin production. Incorporation of sodium bicarbonate (SB) into CA at 0.011, 0.022, and 0.033 mol% reduced cell viability 63-, 10(3)-, and greater than 10(7)-fold, respectively. Colonies resulting from surviving cells did not fluoresce under UV light, but thin-layer chromatography analysis of culture extracts detected aflatoxins. Potassium bicarbonate (KB) at 0.011 and 0.022 mol% produced inhibitory effects similar to those of SB, but NaCl and silica had no effect. After 7 days, control cultures had the normal aflatoxin distribution (B1 greater than G1 greater than B2 greater than G2), but this distribution shifted to B2 greater than B1 approximately equal to G2 greater than G1 during prolonged incubation. Cultures supplemented with SB and KB contained mostly aflatoxins B1 and G1 after 28 days. Both SB and KB raised the pH of CA to 7.5 to 8.5 at the time of growth. Culture growth on CA adjusted to pH 7.5 to 8.5 with NaOH was not inhibited but exhibited reduced fluorescence and elevated levels of aflatoxins B1 and G1. Thus, while bicarbonate inhibition of growth could not be attributed to pH elevation, the lack of culture fluorescence on CA-SB and CA-KB and the altered aflatoxin distribution were caused by the ability of SB and KB to elevate pH.     

Phototherapy and dithranol treatment of psoriasis: new lamps for old.

The response of psoriasis to ultraviolet radiation and dithranol was compared with the response to dithranol alone in 24 patients. The difference in rate of response, measured as change in plaque thickness, and the difference in time to complete clearance of psoriasis between irradiated and non-irradiated forearm lesions was significantly greater for patients treated using fluorescent lamps with negligible ultraviolet C emission (Wolff Helarium) than for those patients treated with a medium pressure mercury arc lamp (p less than 0.01) or an array of fluorescent sunlamps (p less than 0.05). The difference in therapeutic response shows that ultraviolet B phototherapy is effective when used in combination with dithranol. Nevertheless, radiation sources with substantial ultraviolet C emission, such as the medium pressure mercury arc lamp most commonly used to treat psoriasis in the United Kingdom, have little effect because delivery of therapeutic doses of ultraviolet B is limited by erythema induced by ultraviolet C.     

Improved method of screening for aflatoxin with a coconut agar medium.

Nine isolates of Aspergillus flavus and Aspergillus parasiticus were screened for aflatoxin production on a coconut extract agar medium. Aflatoxin-producing colonies were detected under long-wave UV light (365 nm) by blue fluorescence on the reverse side after 2 to 5 days of growth. Aflatoxin production was verified by chemical analysis. Several types of shredded coconut available in the United States were tested and found to be satisfactory. No additives were required. Various parameters affecting the test were investigated.     

Improved method of screening for aflatoxin with a coconut agar medium

Nine isolates of Aspergillus flavus and Aspergillus parasiticus were screened for aflatoxin production on a coconut extract agar medium. Aflatoxin-producing colonies were detected under long-wave UV light (365 nm) by blue fluorescence on the reverse side after 2 to 5 days of growth. Aflatoxin production was verified by chemical analysis. Several types of shredded coconut available in the United States were tested and found to be satisfactory. No additives were required. Various parameters affecting the test were investigated.     

滤光膜对黄檗离体再生能力及其生理生化指标影响

以黄檗（Phellodendron amurense）无菌苗茎段为材料,MS附加1.5 mg·L^-1 BA和0.5 mg·L^-1 NAA为基本培养基,研究了不同滤光膜对黄檗茎段离体再生影响,并对再生过程中生理生化指标变化进行了研究。结果表明,蓝膜对不定芽再生有着明显的促进作用,再生频率达75.4%,平均每个外植体再生的不定芽数为14.7,其次为荧光和黄膜,红膜和绿膜不利于芽的分化。同时发现,蓝膜和荧光有较高的叶绿素含量、较低的chla/b比值。抗氧化酶的活性和可溶性蛋白的含量以蓝膜最高,荧光次之,绿膜最低。