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PubMed2006

Impact of mechanical shelling and dehulling on Fusarium infection and fumonisin contamination in maize.

Mechanical shelling and dehulling methods were tested to evaluate their impact on Fusarium infection and fumonisin contamination in maize. All shelling methods which were tested were found to damage the grains. The IITA sheller caused the highest level (up to 3.5%) of damage. Fusarium populations were higher on damaged grains, the highest being recorded from grains damaged by the IITA sheller (2,533.3 cfu g(-1)). Fumonisin levels were higher in damaged grains, the highest being in maize shelled with the IITA sheller (2.2 mg kg(-1)). Fumonisin levels were positively and significantly correlated with the percentage of damage caused by the shelling methods, and with the number of Fusarium colonies in maize. Mechanical dehulling methods significantly reduced fumonisin levels in maize, resulting in a mean reduction of 62% for Mini-PRL, 65% for Engelberg, and 57% for the attrition disc mill. It is important for farmers to choose appropriate shelling methods to reduce mycotoxin contamination. Dehulling should be widely promoted for the reduction of mycotoxins in maize.

Agriculture↗

PubMedDate not supplied

Deoxynivalenol in wheat and maize flour reference materials. 2. Preparation and certification.

The preparation of four cereal reference materials (two wheat and two maize) and the certification of their 4-deoxynivalenol (DON) contents is described. The materials were prepared and certified within the BCR programme of the Commission of the European Community as part of a broad activity to improve accuracy and agreement of measurements of importance in food and agriculture. Reference material RM 379 was prepared from naturally contaminated wheat four blended with 'blank' material to achieve the desired DON content. The reference material RM 378 was prepared from naturally contaminated maize identified as containing approximately the desired DON content. Details are given of the milling, blending and packaging procedure, and the checks to ensure homogeneity and stability of the materials. The reference materials RM 396 and 377 were similarly prepared from the blank wheat and maize samples respectively. The certification exercise was carried out by five laboratories (with a further two to three laboratories providing supporting data) using a variety of extraction and clean-up procedures with either high performance liquid chromatography (HPLC) or gas chromatography (GC) as the determinative stages. Wheat RM 379 was certified as containing DON at a level of 673 +/- 21 micrograms/kg and wheat RM 396 as containing less than 50 micrograms/kg. Maize RM 378 was certified as containing DON at 425 +/- 38 micrograms/kg and maize RM 377 as containing less than 50 micrograms/kg. The materials are intended for the verification of methods used to determine DON in cereal samples.

Certification↗

PubMedDate not supplied

Sap beetles and mycotoxins in maize.

Sap beetles (Coleoptera: Nitidulidae) are important in vectoring mycotoxigenic species of Aspergillus and Fusarium to maize. Species examined are attracted to fungal and maize volatiles, and are resistant to most mycotoxins compared to maize ear-infesting caterpillars. They will invade ears damaged by birds or caterpillars or those ears that have poor husk coverage. An integrated control programme for these insects under development presently includes pheromones and host coattractants for trapping; identification and dispersal of pathogenic nematodes and fungi; identification of maize varieties cross-resistant to mycotoxigenic fungi and other insects, and the potential mechanisms involved; and formulations of insecticides for single treatment, low active ingredient, selective control of insect pests of ears including sap beetles and caterpillars that preserve naturally occurring predators and parasites. Autoinoculative devices are also being tested to use sap beetles to deliver biocompetitors of mycotoxigenic fungi to maize.

Adaptation, Physiological↗

PubMedDate not supplied

Stability of fumonisins at different storage periods and temperatures in gamma-irradiated maize.

The effect of gamma-irradiation on fumonisin B1 (FB1) and fumonisin B2 (FB2) occurring in maize materials has been investigated together with the stability of fumonisins in gamma-irradiated maize stored at different temperatures (-18 to +40 degrees C) for different periods (2, 4, 13 and 26 weeks). Fifteen KGy gamma-irradiation was required to sterilize efficiently maize flour. This process caused a decrease in fumonisin content of about 20%. The stability studies showed that fumonisins are stable in gamma-irradiated maize for at least 6 months at 25 degrees C or at least 4 weeks at 40 degrees C. These data indicate that gamma-irradiation is an appropriate technique for obtaining sterilized maize materials to be used for intercomparison studies on analytical procedures for the measurement of the fumonisin content.

Carboxylic Acids↗

PubMed1995

Clinical trial of fermented maize-based oral rehydration solution in the management of acute diarrhoea in children.

In an effort to identify appropriate fluids available in the home for oral rehydration therapy in Ghana, a study was designed to investigate the efficacy of fermented maize gruel, a popular Ghanaian traditional food, in the management of acute diarrhoea. Altogether 108 children aged between 4 and 27 months presenting with acute diarrhoea at the Princess Marie Louise Children's Hospital in Accra, with mild to moderately severe dehydration, were randomly assigned to treatment with either WHO/UNICEF oral rehydration solution (ORS) or fermented and unfermented maize solutions. About 35 children were admitted to each of the three treatment groups. Treatment with the rehydration fluid was maintained for 24 h. Efficacy of the various treatments, assessed in terms of fluid intake, stool output, stool frequency, weight gain and duration of diarrhoea, showed no significant variation among the three groups. The results indicate that the maize solutions were as effective as WHO/UNICEF ORS for oral rehydration therapy. However, the fermented maize was more readily accepted by the children than the unfermented solution. Because fermented maize gruel is widely consumed, inexpensive, readily available, and culturally acceptable to most communities in Ghana, it may be recommended as an appropriate home-available fluid for the management of acute diarrhoea in children at the community level.

Acute Disease↗

PubMed2002

Microbiological evaluation of ghanaian maize dough co-fermented with cowpea.

Fermented maize dough meals form a large proportion of people's diet in Ghana. To enhance the nutritive value of these carbohydrate-rich foods, protein complementation was introduced. In this study, microbial ecology of fermenting maize dough fortified with 20% cowpea was investigated. A total of 106 microbial strains were isolated from different batches of the fermenting dough at periodic intervals. Ten genera of microorganisms namely Lactobacillus, Leuconostoc, Saccharomyces, Debaryomyces, Candida, Bacillus, Micrococcus, Klebsiella, Escherichia and Aspergillus were identified, with lactic acid bacteria species being predominant. A lactic count of log 9.9 cfu/g was obtained at the end of 72 h fermentation relative to log 6.6 cfu/g recorded for aerobic mesophiles. At the 12 h fermentation period, the population of yeasts was less than log 1.0 cfu/g, but gradually rose to log 5.36 cfu/g by 48 h followed a slight decline at the end of 72 h fermentation period (log 4.08 cfu/g). Enteric microorganisms that were isolated from the raw cowpea were less than log 1.0 cfu/g at 12 h of fermentation, while the Aspergillus species were isolated from the raw maize and the dough subjected to drying treatment. The growth of inoculated enteropathogenic E. coli and S. typhimurium was inhibited in the cooked, fermented maize-cowpea dough, and at 72 h, they were not within detectable limit. The study concluded that addition of cowpea at 20% level did not affect the natural fermentation characteristics of the maize dough.

Colony Count, Microbial↗

PubMed2005

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.

Acetic Acid↗

PubMed2004

(15)N investigation of nitrogen released from tobacco-waste to be utilized by maize crop.

The (15)N study aimed to estimate the portion of nitrogen released from tobacco-waste to be utilized by maize crop. Tobacco-waste at the levels of 0, 2, 4, 6 and 8 g pot(-1) and ((15)NH(4))(2)SO(4) as nitrogen fertilizer labelled with 5 at.% exc. at the levels of 0, 4, 8, 12 and 16 mg N pot(-1) together with a basal dressing of some nutrients were added to pots with Pioneer maize variety. After the harvest, dry matter yield was recorded and (15)N determinations and calculations were made. Tobacco-waste had a positive effect on the growth and on the nitrogen uptake of maize crop. Increasing the rates of tobacco-waste increased the dry matter yield of maize crop from 4.64 g pot(-1) (at control) to 7.22 g pot(-1) (at the tobacco-waste treatment of 8 g pot(-1)). The values of (15)N in the plant derived from nitrogenous fertilizer also increased with increasing nitrogen fertilizer levels, whereas they decreased from 0.427 % to 0.249 % with increasing tobacco-waste treatments from 0 to 8 g pot(-1), respectively. The average values of per cent nitrogen derived from nitrogenous fertilizer (Ndff) varied from 4.32 % to 7.95 % at the rates of 4-16 mg N pot(-1), respec-tively. However, Ndff decreased from 8.54 % to 4.99 % with increasing tobacco-waste treatments from 0 to 8 g pot(-1), respectively. Per cent nitrogen derived from tobacco-waste (Ndft) increased from 21.8 % to 38.5 % with increasing tobacco-waste treatments from 2 to 8 g pot(-1), respectively. The results have revealed that (15)N tracer technique was confidently used for the investigation of nitrogen levels released from tobacco-waste as organic waste to be utilized by maize crop.

Agriculture↗

PubMed2001

Genetically modified feeds in animal nutrition. 2nd communication: glufosinate tolerant sugar beets (roots and silage) and maize grains for ruminants and pigs.

To analyse substantial equivalence of genetically modified sugar-beets and maize, in which the glufosinate-tolerant (Pat) gene is inserted, crude nutrients, the amino acid and the fatty acid profiles as well as the composition of the NDF-fraction of maize grains were determined and compared with those of the corresponding non-transgenic cultivars. Due to the genetic manipulation differences in crude nutrient contents including sugar and starch were not detected. The amino acid profile of maize grains was analysed to be the same. Fatty acid profile and composition of cell wall constituents did not show any influences as well. Digestibility of Pat-sugar-beets and maize grains for pigs did not demonstrate meaningful differences as compared to the corresponding non-transgenic cultivars. Digestibility of sugar-beet roots and sugar-beet top silage for ruminants proved to be also in the scope of natural variance. As the digestibility of the macro nutrients remained unaffected, the Pat-gene introduction into both crops did not show an influence on the energetic feeding value. For pigs the ME-content of Pat-sugar-beets was determined to be 14.1 MJ/kg DM versus 13.7 MJ of the non-transgenic cultivars. ME-content of Pat-maize grains was 16.0 MJ/kg DM versus 15.8 MJ for controls. For ruminants the feeding value of Pat-sugar-beets was found to be 8.5 MJ NEL/kg DM or 13.2 MJ ME/kg DM, regardless of whether the Pat-gene was inserted or not. The corresponding energy values of sugar-beet top silage ranged between 5.2 and 5.5 MJ NEL/kg DM or 8.6 and 9.1 MJ ME/kg DM, with differences considered in the biological range.

Amino Acids↗

PubMed1998

Effect of genetically modified, low-phytic acid maize on absorption of iron from tortillas.

BACKGROUND: Genetically modified, low-phytic acid strains of maize were developed to enhance mineral absorption, but have not been tested previously in humans. OBJECTIVES: We evaluated the mineral and phytic acid contents of a low-phytic acid "flint" maize (LPM, the lpa-1-1 mutant) and its parent, wild-type strain (WTM) and measured iron absorption from tortillas prepared with each type of maize and from a reference dose of ferrous ascorbate. DESIGN: Proximate composition and mineral and phytic acid contents were measured by standard techniques. Iron absorption from tortillas was evaluated by using the extrinsic tag method and was measured as the incorporation of radiolabeled iron into the red blood cells of 14 nonanemic men 2 wk after intake. RESULTS: The phytic acid content of LPM was 3.48 mg/g, approximately 35% of the phytic acid content of WTM; concentrations of macronutrients and most minerals were not significantly different between strains. Iron absorption results were adjusted to 40% absorption of ferrous ascorbate. Iron absorption was 49% greater from LPM (8.2% of intake) than from WTM (5.5% of intake) tortillas (P < 0.001, repeated-measures analysis of variance). CONCLUSION: Consumption of genetically modified, low-phytic acid strains of maize may improve iron absorption in human populations that consume maize-based diets.

Adult↗

PubMed2000

Iron absorption from ferrous bisglycinate and ferric trisglycinate in whole maize is regulated by iron status.

BACKGROUND: There is a need to determine whether iron absorption from iron amino acid chelates is protected from inhibition by dietary phytate and regulated normally by iron status. OBJECTIVE: The objective of this study was to compare iron absorption from ferrous sulfate, ferrous bisglycinate, and ferric trisglycinate in whole-maize meal; to determine whether iron from ferrous bisglycinate and ferrous sulfate exchanges in the intestinal pool; and to assess iron absorption from ferrous bisglycinate and ferric trisglycinate over a range of iron statuses. DESIGN: In study 1A, 10 iron-sufficient men consumed ferrous sulfate-fortified whole-maize meal porridge equilibrated with (59)Fe-sulfate on day 1 and (55)Fe-bisglycinate on day 2. In study 1B, these volunteers consumed ferrous sulfate-fortified porridge equilibrated with (59)Fe-sulfate and (55)Fe-bisglycinate simultaneously. In studies 2A and 2B, iron absorption from 3 mg Fe as (59)Fe-ascorbate, (55)Fe-bisglycinate, or (59)Fe-trisglycinate in water and in porridge was compared in 23 subjects with a range of iron statuses. Iron absorption was determined from blood radioactivity on day 16. RESULTS: In study 1A, geometric mean iron absorption from ferrous bisglycinate was 6.0% (range: 2.6-13.6%), 4 times higher than that from ferrous sulfate (1. 7%; range: 1.0-3.3%; P < 0.05). In study 1B, absorption from neither source was different from that in study 1A. In studies 2A and 2B, absorption from all sources was strongly inversely related to serum ferritin, with geometric means of 32.5% (iron ascorbate), 9.1% (bisglycinate), and 15.3% (trisglycinate). Iron from ferric trisglycinate was poorly absorbed (2.3%; range: 0.5-9.2%) from maize. CONCLUSION: In whole-maize meal, iron from ferrous bisglycinate is better absorbed than is iron from ferrous sulfate and does not exchange with iron from maize or ferrous sulfate in the intestinal pool. Absorption of iron from bisglycinate and trisglycinate is regulated normally by iron status.

Absorption↗

PubMed2004

Genetic dissection of root formation in maize (Zea mays) reveals root-type specific developmental programmes.

BACKGROUND: Maize (Zea mays) forms a complex root system comprising embryonic and post-embryonic roots. The embryonically formed root system is made up of the primary root and a variable number of seminal roots. Later in development the post-embryonic shoot-borne root system becomes dominant and is responsible together with its lateral roots for the major portion of water and nutrient uptake. Although the anatomical structure of the different root-types is very similar they are initiated from different tissues during embryonic and post-embryonic development. Recently, a number of mutants specifically affected in maize root development have been identified. These mutants indicate that various root-type specific developmental programmes are involved in the establishment of the maize root stock. SCOPE: This review summarizes these genetic data in the context of the maize root morphology and anatomy and gives an outlook on possible perspectives of the molecular analysis of maize root formation.

Mutation↗

PubMed1988

Comparison of non-mutant and mutant waxy genes in rice and maize.

The waxy gene, which is responsible for the synthesis of amylose in endosperm and pollen, is genetically well characterized in many grasses including maize and rice. Homology between the previously cloned maize waxy gene and the rice gene has facilitated our cloning of a 15-kb HindIII fragment that contains the entire rice gene. A comparison of the restriction maps of the maize and rice genes indicates that many restriction sites within translated exons are conserved. In addition, the rice gene encodes a 2.4-kb transcript that programs the in vitro synthesis of a 64-kD pre-protein which is efficiently precipitated with maize waxy antisera. We demonstrate that these gene products are altered in rice strains containing mutant waxy genes. Southern blot analysis of 16 rice strains, ten containing waxy mutations, reveals that the waxy gene and flanking restriction fragments are virtually identical. These results contrast dramatically with the high level of insertions and deletions associated with restriction fragment length polymorphism and spontaneous mutations among the waxy alleles of maize.

Alleles↗

PubMed1990

DNA sequence variation within maize and melon: observations from polymerase chain reaction amplification and direct sequencing.

While compiling genetic linkage maps in several plant species based upon restriction fragment length polymorphisms (RFLPs), it was noted that the incidence of polymorphism differs among species. The basis of this disparity was investigated in this study by examining the nucleotide sequence at homologous loci among distinct cultivars within two species which exhibit considerably different levels of RFLPs. Using the polymerase chain reaction, homologous regions from different cultivars were first amplified and the nucleotide sequence of the products were determined. Four genomic regions of seven maize cultivars and three genomic regions of eight melon cultivars were examined to compare the respective levels of sequence variation between the two species. Levels of variation for both base substitutions and insertions/deletions varied widely among the maize sequences and between maize and melon for base substitutions. Estimates of theta (a measure of polymorphism) ranged from 0 to 0.002 in melon and from 0.006 to 0.040 for base substitutions and from 0.002 to 0.023 for insertions/deletions in maize. Critical value tests and chi-squared tests suggested that in maize the underlying processes generating and maintaining neutral mutations differ among the regions. The results not only suggest that several mechanisms are necessary to explain the variation seen in these two species, but also point to some basic dissimilarities in the organization and maintenance of the genomes of different plant species.

Base Sequence↗

PubMed2001

Characterization of a maize chromosome 4 centromeric sequence: evidence for an evolutionary relationship with the B chromosome centromere.

Previous work has identified sequences specific to the B chromosome that are a major component of the B centromere. To address the issue of the origin of the B and the evolution of centromere-localized sequences, DNA prepared from plants without B chromosomes was probed to seek evidence for related sequences. Clones were isolated from maize line B73 without B chromosomes by screening DNA at reduced stringency with a B centromeric probe. These clones were localized to maize centromere 4 using fluorescence in situ hybridization. They showed homology to a maize centromere-mapped sequence, to maize B chromosome centromere sequences, and to a portion of the unit repeat of knobs, which act as neocentromeres in maize. A representative copy was used to screen a BAC library to obtain these sequences in a larger context. Each of the six positive BACs obtained was analyzed to determine the nature of centromere 4-specific sequences present. Fifteen subclones of one BAC were sequenced and the organization of this chromosome 4-specific repeat was examined.

Base Sequence↗

PubMed2002

Population genetics of duplicated disease-defense genes, hm1 and hm2, in maize (Zea mays ssp. mays L.) and its wild ancestor (Zea mays ssp. parviglumis).

Plant defense genes are subject to nonneutral evolutionary dynamics. Here we investigate the evolutionary dynamics of the duplicated defense genes hm1 and hm2 in maize and its wild ancestor Zea mays ssp. parviglumis. Both genes have been shown to confer resistance to the fungal pathogen Cochliobolus carbonum race 1, but the effectiveness of resistance differs between loci. The genes also display different population histories. The hm1 locus has the highest nucleotide diversity of any gene yet sampled in the wild ancestor of maize, and it contains a large number of indel polymorphisms. There is no evidence, however, that high diversity in hm1 is a product of nonneutral evolution. In contrast, hm2 has very low nucleotide diversity in the wild ancestor of maize. The distribution of hm2 polymorphic sites is consistent with nonneutral evolution, as indicated by Tajima's D and other neutrality tests. In addition, one hm2 haplotype is more frequent than expected under the equilibrium neutral model, suggesting hitchhiking selection. Both defense genes retain >80% of the level of genetic variation in maize relative to the wild ancestor, and this level is similar to other maize genes that were not subject to artificial selection during domestication.

Ascomycota↗

PubMed2003

Impact of a nucleopolyhedrovirus bioinsecticide and selected synthetic insecticides on the abundance of insect natural enemies on maize in southern Mexico.

The impact of commonly used organophosphate (chlorpyrifos, methamidophos), carbamate (carbaryl), and pyrethroid (cypermethrin) insecticides on insect natural enemies was compared with that of a nucleopolyhedrovirus (Baculoviridae) of Spodoptera frugiperda (J. E. Smith) (Lepidoptera Noctuidae) in maize grown in southern Mexico. Analyses of the SELECTV and Koppert Side Effects (IOBC) databases on the impact of synthetic insecticides on arthropod natural enemies were used to predict approximately 75-90% natural enemy mortality after application, whereas the bioinsecticide was predicted to have no effect. Three field trails were performed in mid- and late-whorl stage maize planted during the growing season in Chiapas State, Mexico. Synthetic insecticides were applied at product label recommended rates using a manual knapsack sprayer fitted with a cone nozzle. The biological pesticide was applied at a rate of 3 x 10(12) occlusion bodies (OBs)/ha using identical equipment. Pesticide impacts on arthropods on maize plants were quantified at intervals between 1 and 22 d postapplication. The biological insecticide based on S. frugiperda nucleopolyhedrovirus had no adverse effect on insect natural enemies or other nontarget insect populations. Applications of the carbamate, pyrethroid, and organophosphate insecticides all resulted in reduced abundance of insect natural enemies, but for a relatively short period (8-15 d). Pesticide applications made to late-whorl stage maize resulted in lesser reductions in natural enemy populations than applications made at the mid-whorl stage, probably because of a greater abundance of physical refuges and reduced spray penetration of late-whorl maize.

Animals↗

PubMed2003

Digestion of maize sphingolipids in rats and uptake of sphingadienine by Caco-2 cells.

We investigated the digestion of cerebrosides of plant origin prepared from maize, focusing especially on the digestive fates of trans-4, cis-8- and trans-4, trans-8-sphingadienine, which are common in higher plants. In the small intestinal mucosa and cecal contents of rats, the cerebrosidase activity at pH 5.2 toward the glucosyl linkage in maize cerebrosides (glucosylceramides) was similar to that in cerebrosides of mammalian origin. Similarly, the ceramidase activity toward the amide linkage in ceramides prepared from maize cerebrosides at pH 7.0 was the same as that toward ceramides of mammalian origin. In addition, maize cerebrosides were hydrolyzed to ceramide and free sphingoid bases in the digestive tract of rats after oral administration. To further evaluate the uptake by enterocytes of 4,8-sphingadienine, we used differentiated Caco-2 cells, derived from human colonic carcinoma, as a model of intestinal epithelial cells. The accumulation of sphingoid bases in Caco-2 cells incubated with each isomer of sphingadienine was lower than that after incubation with sphingosine (P < 0.05). Verapamil, a P-glycoprotein inhibitor, increased the accumulation of each sphingadienine but not of sphingosine, suggesting that the efflux of sphingadienine of plant origin, but not sphingosine of mammalian origin, was affected by P-glycoprotein. The digestibility of maize cerebrosides appears similar to that of cerebrosides of mammalian origin, but the metabolic fate of sphingoid bases of plant origin within enterocytes differs from that of sphingosine. Isomers of 4,8-sphingadienine degraded from dietary plant cerebrosides appear to be poorly absorbed from the digestive tract.

Animals↗