Damage to wheat by enclosed populations of Rattus norvegicus

Small enclosed populations of the common brown rat (ten to twenty-six rats), each with access to one ton of sacked wheat for 12–28 weeks, caused a loss in weight of 4·4% of the wheat. 70·4% of the wheat was fouled and had to be cleaned before use. The main monetary loss was due to damage to sacks. Total monetary loss was 18·23% of the original value of the wheat and sacks.

The digestibility of English and Canadian wheats with special reference to the digestibility of wheat protein by man

1. Two men and four women carried out digestibility experiments on English and Canadian wheats at 90 and 80% extractions. The flour was the only source of protein and contributed 77−93% of the total dietary calories.

2. At 90% extraction the digestibility of the diets in terms of calories was unaffected by the source of the flour and amounted to 93·3%. At 80% extraction the digestibility of the diet containing English wheat amounted to 95·6% and of those containing Manitoba wheat to 96·7%. The difference is attributed to mild intestinal upsets on the English flour.

3. The apparent digestibility of the protein depended upon the amount of N in the wheat and fell as the extraction rose. A quantitative analysis of the results indicates that the protein in wheat flour of 90 and 80% extraction is completely digested and absorbed, and that the N found in the faeces is entirely derived from the secretions of the gut.

The Medical Research Council paid for the expenses of this investigation. We are very much indebted to Drs T. Moran, C. R. Jones and other members of the Cereals Research Station, St Albans, without whose help this study would hardly have been possible. We have also very much appreciated the help we have received from the subjects, Miss M. Costain, Miss C. M. Walsham, Miss E. Wilkinson and Mr R. Tayler, and also from Flt.-Sergeant Childs, who kindly made the bomb calorimeter determinations.

The distribution of nicotinic acid in wheat and maize

The principal parts of the grain of two varieties of wheat and two varieties of maize have been separated by manual dissection and the nicotinic acid of the fractions assayed microbiologieally. It is shown that the aleurone layer contains 82% of the total nicotinic acid in wheat and approximately 60% in maize. The scutellum contains 1⋅3% of the total in wheat and, because of its greater bulk, approximately 11% in maize. The carbohydrate endosperm of sweet maize showed a concentration of nicotinic acid twice that of flint maize, though the total nicotinic acid content of each type was similar. Dissected embryos of wheat have grown to flowering successfully, though weakly, without any external supply of nicotinic acid, though 99% of the nicotinic acid of the grain is thereby dispensed with. The provision of an external supply had only a slight stimulating effect.

GEL FILTRATION APPLIED TO THE STUDY OF LIPASES AND OTHER ESTERASES

1. Sephadex G-100 and G-200 gel-filtration columns were calibrated for molecular-weight estimation with proteins of known molecular weights, and used to study the composition of several lipase or esterase preparations. 2. Enzymes from cow's milk, rat adipose tissue and pig pancreas were detected in the column effluents by their ability to liberate free acid from emulsified tributyrin at pH 8.5. 3. Four tributyrinases were detected in preparations from individual cow's milks. Molecular weights 62000, 75000 and 112000 were estimated for three of them, but although the fourth may be of unusually low molecular weight an estimate was not possible. 4. Extracts of rat adipose tissue apparently contained six tributyrinases (molecular weights 39000, 47000, 55000, 68000, 75000 and 200000) but the relative amounts of these enzymes varied widely from rat to rat. 5. Tributyrinase activity in juice expressed from pig pancreatic tissue was due mainly to one enzyme (molecular weight 42000). On the other hand, activity in extracts of acetone-dried pancreas was confined to material of molecular weight > 10(6), which may be an aggregated form of the lower-molecular-weight enzyme. 6. Activity in fractionated wheat-germ extracts was assayed with emulsified triacetin substrate, and was evidently due to one enzyme (molecular weight 51000). 7. Some problems arising in the application of gel filtration to the study of lipase-esterase systems were indicated.

THE NATURE OF THE ANTIPERISTALTIC FACTOR FROM WHEAT GLUTEN

The ultrafiltrate of an aqueous extract of gluten depressed the peristaltic reflex of the rat isolated jejunum. Further purification increased the activity of the extract 200-fold. Biochemical analysis showed that this purified gluten ultrafiltrate contained over 50% of adenosine. Comparative studies of the effects of adenosine and crude gluten ultrafiltrate were carried out on various biological preparations in vitro and in vivo. Both substances depressed all preparations that contained smooth or cardiac muscle, adenosine being 200- to 1,000-times more active than gluten ultrafiltrate. Large doses of gluten ultrafiltrate were spasmogenic to guinea-pig isolated intestine; this was not found with adenosine. Neither substance had any demonstrable effect on striated muscle or on neuromuscular transmission. Both substances were inactivated by incubation with mammalian small intestinal mucosa and with purified adenosine deaminase. Therefore there seems little doubt that gluten ultrafiltrate owes its antiperistaltic action to its adenosine content.

STUDIES ON THE RELATIONSHIPS BETWEEN NEMATODES AND OTHER SOIL MICROORGANISMS. IV. INCIDENCE OF NEMATODE-TRAPPING FUNGI IN THE VICINITY OF PLANT ROOTS

A study was made of the occurrence of nematode-trapping fungi in the rhizosphere and on the root surface of different plants. Arthrobotrys oligospora was the predominant predaceous fungus isolated. It was almost completely absent from plant roots but occurred in varying frequency in rhizosphere soil and in root-free soil. The incidence of this fungus was consistently greater in the soybean rhizosphere and lower in the wheat rhizosphere than in corresponding soil devoid of roots, whereas for other plants, red clover, flax, etc., there was no obvious rhizosphere effect. Spore germination tests and growth of A. oligospora in root extracts of soybeans and wheat failed to account for the differences observed. However, bacterial isolates from the wheat rhizosphere were, on the whole, more antagonistic to this fungus than those from the soybean rhizosphere, whereas isolates from the latter appeared to exert a favorable effect.

STUDIES ON THE MECHANISM OF DESTRUCTION OF THE TOXIC ACTION OF WHEAT GLUTEN IN COELIAC DISEASE BY CRUDE PAPAIN

The toxic action of wheat gluten on two patients was eliminated after predigestion of gluten by crude papain. This change is thought to be due to an enzyme which liberates ammonia from gluten. It is not thought that this particular mechanism operates in the normal intestinal cell but it is envisaged that one of the peptide bonds of the coeliac active constituent (possibly a N-glutaminyl peptide) is normally split by a specific intestinal peptidase which is defective in coeliac patients.

CERIUM-144 AND CESIUM-137 MEASUREMENTS IN THE 1963 UNITED STATES WHEAT CROP AND MILLING PRODUCTS

The distribution of an abundant short-lived (285 days) nuclide, cerium-144, and a long-lived (30.5 years) nuclide, cesium-137, has been measured in wheat samples and milling products by means of radiochemical methods. The patent flour fraction contained approximately 10 and 15 percent of the measured cerium and cesium.

THE ALKALI-STABLE DINUCLEOTIDE SEQUENCES IN 18S+28S RIBONUCLEATES FROM WHEAT GERM

The 2′-O-methyl substitution of ribose residues of ribonucleate chains can give rise to 16 alkali-stable dinucleotides having the general structure NxpNp in which N is any of the four major ribonucleosides and Nx is the 2′-O-methyl derivative of any of the four major ribonucleosides. Quantitative data are presented which show that all of these 16 alkali-stable dinucleotides occur in characteristic amounts in alkali hydrolyzates of the 18 S + 28 S ribonucleates from wheat germ. The alkali-stable dinucleotides cumulatively account for 3 mole% of the total nucleotides of the 18 S + 28 S wheat germ ribonucleates. The relative amounts of the four 2′-O-methyl ribosides responsible for the alkali stability of the dinucleotides have been shown to be distinctly different from the relative amounts of the four corresponding normal ribosides which participate in either the alkali-stable dinucleotide sequences or in the ribonucleate chains as a whole. Quantitative end group data show that the alkali-stable dinucleotide sequences occur internally in high molecular weight ribonucleate chains. Preliminary data are presented on the occurrence of alkali-stable trinucleotides in alkali hydrolyzates of the 18 S + 28 S wheat germ ribonucleates.