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At least 1,225 records · Page 68Linked to original sources
PubMed1983

The relationship of pellagra to corn and the low availability of niacin in cereals.

The poorest inhabitants of an area generally eat the narrowest range of foods, and one staple (which serves as a cheap source of calories) dominates. In turn, the specific type of malnutrition seen in that area depends upon that predominant staple and how it is processed before consumption. Corn, used here in the sense of "Indian corn" or maize, was brought to Europe from America, and over the period 1750-1850 became the typical peasant's staple in many of the areas bordering the Mediterranean. By the end of that period, it had also come to be recognized that pellagra had become a serious, chronic disease in these same countries, flaring up each spring amongst the poorest people living on diets containing much corn and very little animal food (i.e., meat, eggs or dairy products) or wine and being generally in a state of wretchedness. Nothing of the sort was seen in areas where wheat and rice were the staple foods, even when they were highly milled. Most scientists agreed on this association with corn, though not on what was the true cause-and-effect relationship. Research in the present century has shown that pellagra is primarily due to a dietary deficiency of niacin. However, the niacin content of different foods did not tie in well with their pellagra-preventive value. But then it was discovered that a second nutrient, tryptophan, could act as precursor of the vitamin with approximately one sixtieth of the activity of the actual vitamin. The "niacin equivalent" values of foods (calculated from their content of both nutrients) show a much better correlation with their pellagra-preventive value. Thus, mature corn is lower in niacin content than are wheat and rice; also the mixed proteins of corn are lower in their tryptophan content. What is not explained by the calculation of "niacin equivalent" is the general freedom from pellagra of the peasants in Mexico and Central America, where corn has been the staple for millenia and where poverty, the consequent lack of animal foods in the diet, and general misery, have been fully equal to the conditions in Europe. It has been known for 40 years that analytical values for the niacin content of foods depended greatly on the method of extraction used, with the highest values being obtained after treatment with alkali. We have confirmed with rat growth assays that the niacin in corn, wheat and rice is only about one-third available to this species, even after ordinary cooking at neutral pH.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

A cereal haemoglobin gene is expressed in seed and root tissues under anaerobic conditions.

Legumes, and a very few non-legume plant species, are known to possess functioning haemoglobin genes. We describe here the characterization of a haemoglobin cDNA isolated from barley. The deduced amino acid sequence shows 71% amino acid identity with a non-legume haemoglobin gene, a further 16% of the residues being conservative replacements. The barley cDNA also hybridizes to genomic sequences in rye, maize and wheat. The demonstration of a gene from a monocotyledon with close sequence homology to the known non-legume plant haemoglobins fills a major gap in the known distribution of haemoglobin genes in the plant kingdom. The expression of the gene is induced in isolated barley aleurone layers exposed to anaerobic conditions, and the roots of flooding-stressed barley plants. The expression of the RNA under anoxic conditions is similar to that of a known anaerobic response gene, alcohol dehydrogenase. Our results suggest that the increased expression of haemoglobin RNA is an integral part of the normal anaerobic response in barley. The findings are discussed in the light of current theories of haemoglobin function and evolution.

Alcohol Dehydrogenase↗
PubMed1992

A novel cereal storage protein: molecular genetics of the 19 kDa globulin of rice.

A lambda gt11 cDNA library, constructed from poly(A)+ RNA isolated from immature rice seed endosperm, was screened with affinity-purified antibodies against the rice storage protein called alpha-globulin (previously), or the 19 kDa globulin (our term). A positive clone was isolated and sequenced and shown to encode a 21 kDa precursor for the 19 kDa globulin, based on the identity of portions of the inferred amino acid sequence and the sequence of three cyanogen bromide peptides of the 19 kDa globulin. Analysis of genomic DNA by Southern blotting using the cDNA clone probe revealed one hybridizing band in Eco RI, Hind III, and Bam HI digests. This strongly suggests that the 19 kDa globulin is encoded by a single-copy gene. Because of its single-copy nature and its abundance of Arg and lack of Lys, the 19 kDa rice globulin appears to be a particularly attractive target for genetically engineering increased Lys content in rice seeds.

Amino Acid Sequence↗
PubMed1993

Fine structure and evolution of the rDNA intergenic spacer in rice and other cereals.

The intergenic spacer of a rice ribosomal RNA gene repeating unit has been completely sequenced. The spacer contains three imperfect, direct repeated regions of 264-253 bp, followed by a related but more highly divergent region. Detailed analysis of the sequence allows the presentation of an evolutionary scenario in which the 264-253-bp repeats are derived from an ancestral 150-bp sequence by deletion and amplification. Comparison of the rice sequence with those of maize, wheat, and rye shows that, despite considerable divergence from the ancestral sequence, several regions have been highly conserved, suggesting that they may play an important role in the structure and/or expression of the ribosomal genes.

Base Sequence↗
PubMed1992

Ochratoxin A production in Bavarian cereal grains stored at 15 and 19% moisture content.

Wheat, barley, and maize, each in 15-kg parcels at 15 and 19% initial moisture content (IMC), were kept in a Bavarian farm granary from June through November 1990. During this period, the grain at each IMC was analyzed for mycotoxins and monitored for grain temperature, carbon dioxide, seed germination, and microfloral incidence and abundance. Barley and maize stored for 20 weeks at 19% IMC contained ochratoxin A in amounts of 70 and 90 microg/kg, respectively. This mycotoxin was not detected in wheat stored at 19% IMC, nor in the grains stored at 15% IMC. Aflatoxin B1, sterigmatocystin, citrinin, and zearalenone were also assayed but not detected in grains stored at either IMC. Principal component analysis of the data indicated that ochratoxin A was produced in a damp niche in maize, when abundant metabolic activity and CO2 production by Penicillium glandicola and Aspergillus spp. were common.

Edible Grain↗
PubMed1996

Behavioral effects of acute sublethal exposure to dimethoate on wood mice, Apodemus sylvaticus: II--Field studies on radio-tagged mice in a cereal ecosystem.

The effects of direct exposure to an organophosphate (OP) pesticide, dimethoate, were examined in free-living wood mice, Apodemus sylvaticus, in a wheat field. Male mice were radio-tagged at night and followed during 2-3-d periods, before and after an intraperitoneal injection of 50 mg/kg dimethoate which previous laboratory studies had demonstrated causes a maximum depression in brain acetylcholinesterase (AChE) activity of 75% relative to non-exposed mice. In subsequent weeks, survival was estimated by tracking and trapping data. Exposure to dimethoate significantly decreased locomotor activity in the first 6 h after administration resulting in a significant decrease in the area over which animals moved. These effects were limited to the night of treatment and disappeared 24 h later. The transient behavioral impairment of the dimethoate-treated animals appeared to have no effect on medium-term survival. Direct exposure to OPs sufficient to cause 75% depression of brain AChE is unlikely to be hazardous to wood mice if exposure is transient, as in the present study; it would be expected that sustained exposure sufficient to cause such behavioral effects would, however, be detrimental.

Animals↗
PubMed1991

Nucleotide sequence and molecular analysis of the low temperature induced cereal gene, BLT4.

The nucleotide sequence and derived amino acid sequence of a cDNA clone (BLT4) for a low temperature induced barley gene were determined. This gene, together with a small family of related genes, was shown to reside on chromosome 3. The BLT4 clone has homology with genes in wheat and oats. Its expression was studied in oats and in barley doubled haploid lines segregating for spring/winter habit and for frost hardiness. These analyses show that elevated steady state levels of BLT4 mRNA are produced in shoot meristematic tissue after 3 days low positive temperature treatment. The low temperature response was found in all barley doubled haploid lines and was therefore not associated specifically with either the spring/winter habit or frost hardiness. Elevated levels of BLT4 mRNA were also seen in drought-stressed barley and it is likely that this is a gene encoding a low molecular weight protein that is responsive to dehydrative stresses, such as cold and drought.

Amino Acid Sequence↗
PubMed1990

Physical organization of the 18S and 5S ribosomal RNA genes in the mitochondrial genome of rye (Secale cereale L.).

The mitochondrial 18S and 5S ribosomal RNA (rRNA) genes of rye, plus a total of about 90 kilobase pairs of flanking DNA, have been cloned and maps of restriction enzyme cleavage sites have been constructed. Like their homologs from hexaploid wheat, the rye genes are closely linked and are part of a three-copy family of recombining repeats (the "18S/5S repeat"). The rye repeat probably also contains a mitochondrial tRNA(fMet) gene, which the wheat repeat is known to carry. However, despite the overall organizational similarity between the wheat and rye 18S/5S repeats in the immediate vicinity of their coding regions, extensive rearrangement of flanking sequences has taken place during evolutionary divergence of the two species. Our data provide additional support for an emerging picture of plant mitochondrial genomes as evolving much more rapidly in structure than in sequence.

Base Sequence↗