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PubMed1997

Microcolinearity in sh2-homologous regions of the maize, rice, and sorghum genomes.

Large regions of genomic colinearity have been demonstrated among grass species by recombinational mapping, but the degree of chromosomal conservation at the sub-centimorgan level has not been extensively investigated. We cloned the rice and sorghum genes homologous to the sh2 locus of maize on bacterial artificial chromosomes (BACs), and observed that a homologue of the maize a1 gene was also present on each of these BACs. In sorghum, we found a direct duplication of a1 homologues separated by about 10 kb. In maize, sh2 and a1 are approximately 140 kb apart and transcribed in the same direction, with sh2 upstream of a1. In rice and sorghum, this arrangement is fully conserved. However, the sh2 and a1 homologues are separated by about 19 kb in both rice and sorghum. We found low-copy-number and repetitive DNAs between the sh2 and a1 homologues of sorghum and rice. The sh2 and a1 homologues cross-hybridized, but the repetitive DNA and most low-copy-number sequences between these genes did not. These results indicate that maize, sorghum, and rice have conserved gene order and composition in the sh2-a1 region, but have acquired extensive qualitative and quantitative differences in the sequences between these genes.

Base Sequence↗

PubMed1998

A knob-associated tandem repeat in maize capable of forming fold-back DNA segments: are chromosome knobs megatransposons?

A class of tandemly repeated DNA sequences (TR-1) of 350-bp unit length was isolated from the knob DNA of chromosome 9 of Zea mays L. Comparative fluorescence in situ hybridization revealed that TR-1 elements are also present in cytologically detectable knobs on other maize chromosomes in different proportions relative to the previously described 180-bp repeats. At least one knob on chromosome 4 is composed predominantly of the TR-1 repeat. In addition, several small clusters of the TR-1 and 180-bp repeats have been found in different chromosomes, some not located in obvious knob heterochromatin. Variation in restriction fragment fingerprints and copy number of the TR-1 elements was found among maize lines and among maize chromosomes. TR-1 tandem arrays up to 70 kilobases in length can be interspersed with stretches of 180-bp tandem repeat arrays. DNA sequence analysis and restriction mapping of one particular stretch of tandemly arranged TR-1 units indicate that these elements may be organized in the form of fold-back DNA segments. The TR-1 repeat shares two short segments of homology with the 180-bp repeat. The longest of these segments (31 bp; 64% identity) corresponds to the conserved region among 180-bp repeats. The polymorphism and complex structure of knob DNA suggest that, similar to the fold-back DNA-containing giant transposons in Drosophila, maize knob DNA may have some properties of transposable elements.

Base Sequence↗

PubMed1996

Maize chromosomal HMGc. Two closely related structure-specific DNA-binding proteins specify a second type of plant high mobility group box protein.

The chromosomal high mobility group (HMG) proteins are small and abundant non-histone proteins common to eukaryotes. We have purified the maize HMGc protein from immature kernels and characterized it by mass spectrometry and amino acid sequence analysis. HMGc could be resolved into two similar proteins by reversed phase chromatography. Cloning and characterization of the corresponding cDNAs revealed that they encode two closely related maize HMGc proteins, now termed HMGc1 and HMGc2. Their theoretical masses of 15,316 and 15,007 Da are >300 Da lower than the masses determined for the proteins purified from maize, indicating post-translational modifications of the proteins. Despite sequence similarity to maize HMGa (and previously described homologous proteins of other species) amino acid sequence alignments reveal that HMGc is in several conserved regions distinct from these proteins. Consequently, we have identified a novel type of plant protein containing an HMG box DNA binding domain and belonging to the HMG1 protein family. HMGc1 and HMGc2 were expressed in Escherichia coli, purified to homogeneity, and analyzed for their DNA binding properties. They proved to bind to DNA structure-specifically since they formed complexes with DNA minicircles at concentrations approximately 100-fold lower than the concentrations required to form complexes with linear fragments of identical sequence. Furthermore, HMGc1 and HMGc2 can constrain negative superhelical turns in plasmid DNA.

Amino Acid Sequence↗

PubMed2000

The high mobility group I/Y protein is hypophosphorylated in endoreduplicating maize endosperm cells and is involved in alleviating histone H1-mediated transcriptional repression.

During maize endosperm development, cells shift from a mitotic cycle to endoreduplication, driving the massive synthesis of storage proteins (zeins) and starch. In this developmental context, we studied changes in expression levels of histone H1 and high mobility group I/Y (HMG-I/Y), two chromatin architectural proteins that are known to affect gene transcription. Almost no change was found in the level of histone H1 during endosperm development, despite a dramatic increase in DNA content (endoreduplication); hence, the histone H1/DNA ratio decreased substantially. Concurrently with a reduction in the Cdc2 kinase activity at the shift to endoreduplication, significant changes were found in the level and mobility of the HMG-I/Y protein; the faster migrating forms were, at least partly, hypophosphorylated. Purified maize HMG-I/Y protein was found to be phophorylated in vitro by the Cdc2 kinase and bound efficiently to the gamma-zein promoter AT-rich tract (gammaZ-AT). Using an in vitro transcription assay, we demonstrated the capability of the maize HMG-I/Y protein to relieve the inhibitory effect exerted by histone H1 on templates containing the gammaZ-AT sequence. These data suggest that during maize endosperm development transcription and perhaps replication are controlled, at least partly, by the activity of the Cdc2 kinase and the interplay between histone H1 and HMG-I/Y proteins.

Base Sequence↗

PubMed1985

Absorption and metabolism of glucose by the mesenteric-drained viscera of sheep fed on dried-grass or ground, maize-based diets.

Sheep fitted with re-entrant canulas in the proximal duodenum and terminal ileum were used to determine the amount of alpha-glucoside entering, and apparently disappearing from, the small intestine when either dried-grass or ground maize-based diets were fed. The fate of any alpha-glucoside entering the small intestine was studied by comparing the net disappearance of such alpha-glucoside from the small intestine with the absorption of glucose into the mesenteric venous blood. Glucose absorption from the small intestine was measured in sheep equipped with catheters in the mesenteric vein and carotid artery. A continuous infusion of [6-3H]glucose was used to determine glucose utilization by the mesenteric-drained viscera and the whole-body glucose turnover rate (GTR). The amounts of alpha-glucoside entering the small intestine when the dried-grass and maize-based diets were given were 13.9 (SE 1.5) and 95.4 (SE 16.2) g/24 h respectively; apparent digestibilities of such alpha-glucoside in the small intestine were 60 and 90% respectively. The net absorption of glucose into the mesenteric venous blood was -2.03 (SE 1.20) and 19.28 (SE 0.75) mmol/h for the dried-grass and maize-based diets respectively. Similarly, total glucose absorption amounted to 1.52 (SE 1.35) and 23.33 (SE 1.86) mmol/h (equivalent to 7 and 101 g/24 h respectively). These values represented 83 and 111% of the alpha-glucoside apparently disappearing from the small intestine, determined using the re-entrant cannulated sheep. Total glucose absorption represented 8 and 61% of the whole-body GTR for the dried-grass and maize-based diets respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed2003

The effect of retinyl palmitate added to iron-fortified maize porridge on erythrocyte incorporation of iron in African children with vitamin A deficiency.

Retinyl palmitate added to Fe-fortified maize bread has been reported to enhance Fe absorption in adult Venezuelan subjects but not in Western Europeans. It is not known to what extent these results were influenced by differences in vitamin A status of the study subjects. The objective of the present study was to evaluate the influence of retinyl palmitate added to Fe-fortified maize porridge on erythrocyte incorporation of Fe in children with vitamin A deficiency, before and after vitamin A supplementation. Erythrocyte incorporation of Fe-stable isotopes was measured 14 d after intake of maize porridge (2.0 mg Fe added as ferrous sulfate) with and without added retinyl palmitate (3.5 micromol; 3300 IU). The study was repeated 3 weeks after vitamin A supplementation (intake of a single dose of 210 micromol retinyl palmitate; 'vitamin A capsule'). Vitamin A status was evaluated by the modified relative dose-response (MRDR) technique. Retinyl palmitate added to the test meal reduced the geometric mean erythrocyte incorporation of Fe at baseline from 4.0 to 2.6 % (P=0.008, n 13; paired t test). At 3 weeks after vitamin A supplementation, geometric mean erythrocyte incorporation was 1.9 and 2.3 % respectively from the test meal with and without added retinyl palmitate (P=0.283). Mean dehydroretinol:retinol molar ratios were 0.156 and 0.125 before and after intake of the single dose of 210 micromol retinyl palmitate; 'vitamin A capsule' (P=0.15). In conclusion, retinyl palmitate added to the labelled test meals significantly decreased erythrocyte incorporation of Fe in children with vitamin A deficiency at baseline but had no statistically significant effect 3 weeks after vitamin A supplementation. The difference in response to retinyl palmitate added to Fe-fortified maize porridge on erythrocyte incorporation of Fe before and after intake of the vitamin A capsule indicates, indirectly, changes in vitamin A status not measurable by the MRDR technique. The lack of conclusive data on the effect of retinyl palmitate on Fe absorption indicates the complexity of the interactions between vitamin A status, dietary vitamin A and Fe metabolism.

Adolescent↗

PubMed1985

Food intake of the laying hen following crop loads of maize oil and other nutrients.

The metabolisable energy (ME) of the diet of laying hens at an ambient temperature (Ta) of 20 degrees C was abruptly changed from 10.9 MJ/kg to 12.9 MJ/kg, or vice versa. Food intake during the next 14 d was significantly reduced by the low ME diet and was increased by the high ME diet, that is, the expected compensatory changes in food intake did not occur. Laying hens given the same change of diet as above but kept at 32 degrees C did not show any change in food intake within 14 d. Thus ME intake increased with the high ME diet and decreased with the low ME diet. Daily doses of 10 ml maize oil/kg body weight given directly into the crop of laying hens at a Ta of 20 degrees C, resulted in an immediate, significant, reduction of food intake such that total ME intake remained the same as with normal feeding. Daily doses of 3 ml maize oil/kg, given as before, resulted in an immediate, significant, reduction in food intake at a Ta of 20 degrees C but at a Ta of 32 degrees C food intake remained unchanged; consequently daily ME intake increased. Loading the crop with glucose or sucrose, at Ta 20 degrees C, in quantities which provided a similar ME as 3 ml maize oil/kg, reduced food intake but the adjustment was less precise and daily ME intake increased. Loading with glycerol or protein hydrolysate decreased both food and ME intake. Crop loads of starch were as effective as maize oil in bringing about a significant and compensatory reduction of food intake. Similar volumes of water or liquid paraffin placed in the crop did not affect food or ME intake. A similar weight or cellulose placed in the crop reduced food and ME intake.

Animals↗

PubMed1997

A comparative study between mature ostriches (Struthio camelus) and adult cockerels with respect to true and apparent metabolisable energy values for maize, barley, oats and triticale.

1. In three successive trials with cockerels and mature ostrich males the apparent and true metabolisable energy values, corrected for nitrogen retention (AMEn and TMEn) were determined by a balance method for malting barley, oats, triticale and yellow maize. All these ingredients were used as sole dietary components with the exception of triticale for ostriches which was diluted with 440 g/kg lucerne meal. The balance trial lasted for 5 d after an adaption period of 7 d for ostriches, and 3 d after an adaption period of one day for cockerels. 2. AMEn values for cockerels of malting barley, oats, triticale and maize were 11.6, 10.48, 11.44 and 14.42 MJ/kg respectively. Significantly higher values of 14.21, 12.65, 12.60 and 14.89 MJ/kg were determined for malting barley, oats, triticale and maize for ostriches. 3. TMEn values determined by regression yielded values in ostriches of 13.92, 12.27, 13.21 and 15.22 MJ/kg for malting barley, oats, triticale and maize respectively. The corresponding TMEn values in cockerels were 11.33, 10.63, 11.82 and 14.07 MJ/kg. 4. The ostrich is capable of utilising fibre more efficiently than poultry. The higher energy values observed for the various ingredients also indicated that the non-starch polysaccharides such as beta-glucans and arabinoxylans in the more fibrous energy sources had little if any effect on the available energy of these ingredients as found with poultry. 5. The potential of ostriches to utilise the more fibrous energy sources like barley, oats and triticale allows for their economical use in diet formulation. This possibility may result in markedly lower food costs for ostriches.

Aging↗

PubMed1999

Performance of laying pullets fed on cereal-free diets based on maize offal, cassava peel and reject cashew nut meal.

1. A 70-d experiment was conducted to determine the response of 26-week-old laying pullets to cereal-free diets based on maize offal, cassava peel and full-fat cashew nut meal (CNM) in comparison with a standard 550 g maize/kg reference diet. The 4 test diets all contained 315 g CNM/kg 232.5, 155.0, 77.5 and 0.0 g/kg of maize offal in combination with 77.5, 155.0, 232.5 and 315.0 g/kg of cassava peel, respectively. 2. Pullets fed on the 4 CNM-based diets consumed (P<0.05) less food than those fed on the reference diet; they also had lower (P<0.05) rates of lay, produced less (P<0.05) egg mass, had lower (P<0.05) food conversion efficiencies and their eggs had a lighter (P<0.05) yolk colour. Pullets fed some of the CNM-based diets also gained more (P<0.05) weight, the heaviest (P<0.05) being birds reared on the diet containing 315 g/kg cassava peel. Egg weight, shell thickness and albumen height from all eggs were similar. Pullets fed on the CNM-based diets had inferior (P<0.05) retention of dry matter and protein. 4. It was concluded that feeding full-fat CNM allowed for high dietary inclusion rates of cassava peel and maize offal and the resultant diets, which contained no maize, supported satisfactory performance of laying hens.

Animal Feed↗

PubMed2000

Survey for aflatoxins, ochratoxin A, zearalenone and fumonisins in maize imported into the United Kingdom.

This survey examined 140 samples of raw maize as received at ports or at major maize mills in the UK and 12 after initial cleaning. Samples were examined for aflatoxins B1, B2, G1 and G2, ochratoxin A, zearalenone and fumonisins B1, B2 and B3 using fully validated analytical HPLC methods with detection limits of 0.1 microgram/kg for each aflatoxin and ochratoxin A, 4 micrograms/kg for zearalenone and 10 micrograms/kg for each fumonisin. 95.0% and 92.1% of samples met the new EC statutory maximum permissible level for total aflatoxins and aflatoxin B1 respectively. The maximum concentration of ochratoxin A found was 1.5 micrograms/kg. Zearalenone and fumonisins were detected in almost every sample with 41.7% of maize containing more than 100 micrograms/kg of zearalenone and 48% of samples containing more than 1000 micrograms/kg total fumonisins. Initial cleaning of raw maize reduced aflatoxin concentrations by about 40% and total fumonisins by 32%.

Aflatoxins↗

PubMed2001

Fusarium species (section Liseola) and its mycotoxins in maize harvested in northern Argentina.

Maize and maize products harvested in small fields and stored by farmers in northern Argentina were assayed for Fusarium and fumonisin and beauvericin contamination. Fumonisins were present in six of the 18 samples. The levels of fumonisins ranged from 603 to 1888 ng/kg. Fumonisin B3 (FB3) and beauvericin were not detected in the samples evaluated. Fusarium subglutinans was one of the most prevalent species isolated. Twenty-five strains of F. subglutinans isolated from maize kernels and belonging to Gibberella fujikuroi mating population E were beauvericin-producers in culture. Seven of these strains also produced moniliformin. This is the first report on beauvericin-production by maize isolates of F. subglutinans from Argentina.

Anti-Bacterial Agents↗

PubMed2003

Survey of the natural occurrence of zearalenone in maize from northern Iran by thin-layer chromatography densitometry.

During September 2000, forty samples of preharvest maize from the province of Mazandaran, north Iran, were randomly collected. Samples were analysed for zearalenone (ZEA) by a thin-layer chromatography (TLC) method (AOAC Official Method). ZEA was extracted with chloroform, purified through a chromatographic column containing silica gel, separated on a TLC plate and quantified by densitometry. The analytical method was validated and was adequately reliable and sensitive. The mean recovery rate of ZEA from spiked samples was 92%. The absolute amount of ZEA standard detectable on a TLC plate was 20 ng, giving a limit of detection (LOD) of 100 ng g(-1). In some samples, it was shown that aflatoxins interfere with ZEA. Therefore, to remove this interference, the TLC mobile phase was changed. Data revealed that three of 40 (7.5%) maize samples contained ZEA in the range 100-212 ng g(-1), with a mean of 141+/-51 ng g(-1). This study, which is the first report of ZEA occurrence in Iranian maize, showed that the ZEA level in maize of Mazandaran province was lower than maximum limit for this mycotoxin in Iran.

Chromatography, Thin Layer↗

PubMedDate not supplied

Incidence of mycotoxins in maize grains in Bihar State, India.

A regular survey of some maize-growing areas of Bihar state, India, for three consecutive years (September 1984 to September 1986) revealed heavy infestations of mycotoxin-producing fungi with different maize samples. Aflatoxin-producing fungi had the highest frequency of occurrence in all the cases and aflatoxins were the most common mycotoxins elaborated by these fungi. Maize samples of the Kharif crop had a greater incidence of aflatoxins (47%) than the samples of rabi crop (17%). Stored maize grains also had a high incidence of aflatoxins (43%). Most of the contaminated samples contained aflatoxins at levels above 20 micrograms/kg.

Aflatoxins↗

PubMedDate not supplied

European intercomparison study for the determination of the fumonisins content in two maize materials.

The results of an intercomparison study for the analysis of fumonisin B1 (FB1) and fumonisin B2 (FB2) in a contaminated maize material (Maize B, containing approximately 2 micrograms/g FB1 and 1 micrograms/g FB2) and its 'blank' counterpart (Maize A, containing less than 20 ng/g FB1 and FB2) are reported. Maize materials were distributed in 60 g sachets, submitted to gamma-irradiation at 15 kGy, and distributed to participating laboratories. The study was carried out by 24 European laboratories, most of which have national or international responsibilities for food/feed quality control. Participants used basically one method with some modifications, based on clean-up through SAX minicolumn and reversed phase HPLC with fluorescence detection of the OPA-fumonisin derivatives. The intercomparison study generated data (after correction for recoveries) with repeatability and reproducibility levels of: RSDr = 10% and RSDR = 11% for FB1; RSDr = 11% and RDSR = 13% for FB2. The recoveries obtained by most participants were considered low (70% for FB1 and 69% for FB2), being considerably affected by the extraction mode. Average recoveries for laboratories using blending were 62% and 60%, whereas for laboratories using shaking they were 85% and 86% for FB1 and FB2, respectively. The day-to-day- data showed a between-day, within-laboratory repeatability lower than 15% (CV < 15%) for FB1 for all laboratories, whereas only three laboratories obtained a between-day, within-laboratory reproducibility higher than 15% (CV > 15%) for FB2.

Animal Feed↗

PubMedDate not supplied

Surveillance of fumonisins in UK maize-based foods and other cereals.

A survey has been carried out to determine the levels of fumonisins in a variety of maize-based foods and cereals available in the UK. The fate of fumonisins during commercial processing of maize was also assessed at each stage of the process. Fumonisins were not detected in samples of barley, wheat, soya, oats, rice, corn syrup or oil, corn-on-the-cob, corn-fed chicken or wheat flour tortilla. Despite detectable fumonisin contamination in samples of the original maize, fumonisins were not detected in samples of the food products obtained from commercial maize processing. Low levels were detected in samples of tacos and in some foods containing corn-based thickeners, such as instant semolina pudding and instant custard powder. Approximately 78% of corn snack samples contained fumonisins (11-220 micrograms/kg), while 24% of breakfast cereals contained total fumonisins at between 11 and 194 micrograms/kg. Although none of the ready-made popcorn samples contained detectable levels of fumonisins, 46% of popping corn samples and microwaveable popcorn contained fumonisins at 14-784 micrograms/kg. The highest levels of fumonisins were detected in samples of polenta with concentrations ranging from 16 to 2124 micrograms/kg. Overall, fumonisins were detected in 26% (76) of the 291 retail samples analysed.

Chromatography, High Pressure Liquid↗

PubMed1999

Linking extraction and purification of maize samples for fumonisin analysis.

Fumonisins are produced by several fungal species that are common contaminants of maize. The most abundant naturally occurring fumonisin, fumonisin B1 (FB1), has been shown to induce several animal disease syndromes. The development of analytical methods is therefore important. A new method is described that integrates extraction and purification of maize samples in one step. It efficiency is compared against well-known methods, and shows similar results for naturally contaminated maize. It is concluded that the proposed method can be applied to fumonisin B1 and fumonisin B2 (FB2) analysis in maize at least within the concentration range found.

Carboxylic Acids↗

PubMed1993

Biogenic amines in silage. 3. The occurrence of six biogenic amines in farm-scale grass and maize silages.

Concentrations of putrescine (PUT), cadaverine (CAD), spermidine (SPD), spermine (SPM), histamine (HIS) and tyramine (TYR) in 53 grass silages and 54 maize silages were determined using an HPLC method. Concentrations of all amines excluding SPD in grass silages decreased significantly with increasing dry matter (DM) contents and decreasing acetic acid concentrations. The mean concentrations were 1310, 642, 414, 139, 120 and 33.6 mg/kg for TYR, CAD, PUT, SPM, HIS and SPD respectively in grass silages of 20-30% DM. The maximal values found were twice to five times higher than the mean values. The effect of increasing DM on the amines concentrations was not evident in maize silages. The mean concentrations, regardless of the DM content, were surprisingly high: 435, 388, 341, 71.7, 25.1 and 5.4 mg/kg for TYR, PUT, CAD, HIS, SPD and SPM. The maximal values in maize silages were three times to ten times higher than the mean values. Considering that maize silage forms the great proportion of the diets of cattle during long-term winter feeding, further toxicological and physiological research should be carried out.

Animals↗

PubMed1999

Comparison of Aspergillus niger phytase and Trichoderma reesei phytase and acid phosphatase on phytate phosphorus availability in pigs fed on maize-soybean meal or barley-soybean meal diets.

The efficacy of Aspergillus niger (APhy) phytase, Trichoderma reesei (TPhy) phytase and acid phosphatase (TAcPh) preparations in improving the utilization of phytin-phosphorus in the maize-soybean meal (SBM) or barley-SBM (800:200 g kg-1) diets was studied in two separate digestibility and balance trials with ten growing pigs using 5 x 5 Latin square designs. The positive control diet contained a total phosphorus (P) of 6.5 g kg-1, while the negative control as well as the APhy, TPhy and TAcPh supplemented diets which did not contain additional inorganic-P, had a total P of 4.1 g kg-1. The APhy and TPhy supplements provided phytase activity of 1000 PU g-1 together with AcPh of 8000 HFU g-1. TAcPh at a level of 8000 HFU g-1 was the only addition to one diet. The intrinsic phytase activity of barley was 355 PU g-1 while maize and soybean meal showed no phytase activity. Phytase supplements of the APhy and TPhy sources increased ash digestibility in both diets but had only a minor effect on nitrogen utilization. The addition of phytase improved absorption of P by 21%-units in barley-SBM diet and 29%-units in maize-SBM diet, without any difference between the two phytase sources. The retained P in diets with phytase was higher than in diets without phytase, 4.4 (APhy), 4.5 (TPhy) vs. 2.9 g d-1 in barley-SBM-diets and 3.7 (APhy), 4.0 (TPhy) vs. 1.8 g d-1 in maize-SBM-diets. No difference was found between the two sources of phytase. TAcPh without additional phytase did not show any effect on P absorption or retention. Ca absorption and retention were improved due to the phytase treatments. Supplementing pig diets with either APhy or TPhy sources seems to be equally effective in enhancing the availability of phytate-P. Consequently, these supplements can reduce the P-excretion of pigs by 32-40% as compared with the diet supplemented with inorganic-P.

6-Phytase↗