Isolation and characterization of subgenomic DNAs encapsidated in "single" T = 1 isometric particles of Maize streak virus

"Single" T = 1 isometric particles of Maize streak virus (MSV) have been isolated from infected maize leaves. Biochemical and genetic characterizations show that these particles contain subgenomic (sg) MSV DNA encapsidated by the MSV coat protein. The largest sg DNA is 1.56 kb, slightly larger than half genome size, although sg DNAs as small as 0.2 kb were also cloned. The sg DNAs are not infectious, and they do not appear to play a role in the pathogenicity of MSV. This is the first report of sg DNAs for MSV and, to our knowledge, the first time that encapsidated sg DNAs have been characterized at the sequence level for any geminivirus. These data will assist in our investigations into the role of genomic DNA in the formation of the unique geminate capsid architecture of the Geminiviridae.     

Effect of soybean fortification on Ghanaian fermented maize dough aroma

The effect of soy fortification on the development of aroma compounds, dough acidity and growth of the predominant microorganisms were investigated in Ghanaian maize dough fermented spontaneously over a period of 72 h. The fortified maize dough was prepared from a milled mixture of soaked maize grains and pre-soaked, blanched and dehulled soybeans added at 20% replacement level. Extracts of volatiles from the soy-fortified and unfortified dough samples were obtained by Likens–Nickerson simultaneous distillation and extraction method analysed by gas chromatography-mass spectrometry and gas chromatography-olfactometry (gas chromatography-sniffing). Major aroma compound groups identified in the fermented dough samples were carbonyls, alcohols, esters and volatile organic acids. Twenty-nine carbonyls were found in soy-fortified maize dough compared with 21 in the unfortified dough. Although the same alcohols were found in both dough samples, the total concentration of alcohols was slightly different, being less for the soy-fortified sample. Total concentration of esters in soy-fortified dough decreased after 72 h while levels in the unfortified dough increased. Increases in the production of lactic and acetic acids occurred in soy-fortified samples, but the maximum concentrations of acetic acid achieved did not differ significantly between the two types of dough. Twenty-three compounds were perceived to be contributing to the typical aroma of soy-fortified maize dough by the method of gas chromatography-sniffing. These included 12 carbonyls, six alcohols, two esters, two acids and one furan.     

Ultra-high-pressure liquid chromatography–solid-phase clean-up for determining aflatoxins in Egyptian food commodities

In this work, we determined the content of regulated aflatoxins (ATs) B1, B2, G1, and G2 in food commodities using solid-phase extraction (SPE) and ultra-high-pressure liquid chromatography with fluorescence detection without derivatization. We extracted ATs from the ground samples by mixing in NaCl and 80% (v/v) methanol. The sample was enriched and cleaned up by SPE technique using Bakerbond^® C18 cartridges. The extract that we obtained was immediately analyzed using isocratic elution with a mobile phase consisting of acetonitrile, methanol and deionized water in a ratio of 64:18:18. Method validation was carried out by determining these ATs in a quality control material consisting of almond T02445QC and with the add-found test. The results provided satisfactory recovery within the range of 89.6–103.3%. Repeatability and intermediate precisions were assessed as RSD (%) which were found in the range of 1.1–11.3% and 1.5–12.0%, respectively. The limit of detection (S/N = 3) was 0.03, 0.02, 0.04, and 0.02 μg kg⁻¹ for B1, B2, G1 and G2, respectively. Finally, the method was successfully applied to determine ATs in raw Egyptian food commodities, namely maize, popcorn, pistachio, corn, peanuts, chilli, wheat, green coffee and almond, and the corresponding RSD did not exceed 11%.     

Physiological changes in Triticum durum, Zea mays, Pisum sativum and Lens esculenta cultivars, caused by irrigation with water contaminated with microcystins: A laboratory experimental approach

The aim of the present study was to investigate the effect of exposure to a microcystin (MC)-containing extract from a cyanobacteria bloom on growth, development, mineral nutrient accumulation, and photosynthetic activity of Triticum durum, Zea mays, Pisum sativum and Lens esculenta cultivars. The MCs in the extract, identified by HPLC and/or mass spectrometry (MS) were: MC-RR, -LR, -YR, -(H4)YR, -WR, and -FR. Plant growth and development was tested along 30 exposure days. After this period, MC-extract caused a clear reduction in plant growth and productivity, as well as deleterious effects on development and Photosystem II activity, measured by Fv/Fm fluorescence. However, the chlorophyll (a + b) content hardly varied, and the accumulation of Na⁺, K⁺, Ca²⁺, P and N was enhanced. All the effects observed were plant species, MC concentration, and exposure-time dependent. Relative accumulation of each MC variant greatly varied among plant species and plant organ. The data obtained supports the idea that the use of surface water containing MCs for crop irrigation can affect both plant yield and quality, and secondly, that MC accumulation in edible plants might pose a potential risk for human and animal health, if the MC intake exceeded the recommended tolerable limits.     

Inhibitory effect of cyclic terpenes (limonene, menthol, menthone and thymol) on Fusarium verticillioides MRC 826 growth and fumonisin B1 biosynthesis

The minimum inhibitory concentration (MIC) of cyclic terpenes (limonene, menthol, menthone and thymol) against Fusarium verticillioides MRC 826 was assessed by using the semisolid agar antifungal susceptibility (SAAS) technique. Limonene, menthol, menthone and thymol were evaluated at final concentrations of 25, 50, 75, 150, 200, 250, 500 and 1000 μL/L of culture medium. Limonene and thymol showed the highest inhibitory effects on F. verticillioides development. Thus, the effects of monoterpenes on fumonisin B1 (FB1) biosynthesis were evaluated by using corn grain (Zea mays) as substrate. The monoterpenes were inserted on maize 1 day before inoculation with a conidial suspension of F. verticillioides to give final concentrations of 75 ppm. At this concentration, thymol was the most active inhibitor on FB1 biosynthesis.     

Allergic reactions due to glove-lubricant-powder in health-care workers

Eight glove-wearing hospital personnel were evaluated for suspected type I-like allergic manifestations due to corn-starch powder. All subjects were clinically examined, the presence of atopy was assessed by administration of a questionnaire, the on-off test was verified (the clinical feature behavior was verified with regard to the beginning and the cessation of the work shift), levels of specific serum IgE for maize and latex were measured, and prick tests for the same allergens were performed. The on-off test was positive for everyone. The symptom associated with glove use was urticaria, which was also associated in one case with intermittent dyspnea and in another with oculorhinitis, angioedema, and asthma. Five workers were atopic. The serum IgE test found three positive responses to maize, three positive responses to both latex and maize, and two negative responses to both. However, in the two patients testing negative to IgE, the prick tests were positive: one for maize and the other for both maize and latex. All workers evaded further relapses by avoiding exposure to powdered gloves. There is general agreement that corn-starch powder may cause irritant dermatitis and that it may be a vehicle for other allergens. This study seems to suggest that corn-starch powder may act as a type I allergen itself. Further studies on a larger number of subjects and further research on the chemical properties of corn-starch powder, in particular on its protein content, are needed to confirm this hypothesis. Received: 30 December 1996 / Accepted: 5 May 1997     

贝母／春玉米／番薯旱地高产栽培技术应用

浙江省磐安县发展贝母/春玉米/番薯为代表的药材与粮食作物的间套种植,取得了较好的效益。通过几年的试验示范,确定了相应的套种布局和品种配置,并推广了行之有效的高产高效配套技术。目前,全县采用高产栽培技术的贝母/春玉米/番薯间套种植的面积已占全县贝母种植面积的82.4％。     

Peripheral neuropathy in ageing rats fed clioquinol and a maize diet

Summary Rats fed clioquinol and a maize diet developed much more severe neuropathy in old age than did rats fed only a maize diet. The findings suggest that, in the rat, clioquinol can accentuate other known causes of neuropathy.