L. C. Norris

A microbiological assay for vitamin B12 using Lactobacillus leichmannii.

Summary A microbiological assay for vitamin B12 using Lactobacillus leichmannii (ATCC 4797) has been developed. The assay medium contains crystalline amino acids as the nitrogen source and adsorbed tomato juice filtrate as a source of unidentified growth factors. A high level of cysteine and ferrous sulfate are present in the medium to keep it in the necessary reduced state. Data are given to show the degree of precision and reproducibility to be expected from the assay.

The Need for Manganese in Bone Development by the Rat.

Summary The length, density, breaking strength, and phosphatase content of the bones of manganese-deficient rats were lower than in pairmates of the same weight receiving adequate manganese. There was no difference between the two groups in percentage of ash, calcium, phosphorus, and magnesium in the fat-free dry bone.

The Folic Acid Requirement of Chicks for Growth, Feathering and Hemoglobin Formation.∗

Summary The folic acid requirement of chicks for growth, feathering, and hemoglobin formation has been determined using a purified diet containing 2.0 μg of preformed folic acid per 100 g of diet. The total folic acid content of the basal diets as determined microbiologically following incubation with chick liver was 5 μg per 100 g of diet for Experiment 1 and 15 μg for Experiments 2 and 3. The following amounts of folic acid, which include the amount in the basal diet, were required for its several functions: for survival to 6 weeks of age, approximately 25 μg per 100 g; for growth and hemoglobin formation at 4 weeks of age, 45 μg; for growth at 6 weeks, 45 μg, but for hemoglobin formation at 6 weeks, 35 μg; and for feathering at 6 weeks of age, not less than 55 μg per 100 g of diet. In these experiments the addition of succinylsulfathiazole at 1 or 2% of the diet did not have any effect on growth, feathering, or hemoglobin formation in chicks to 6 weeks of age.

Studies on Unidentified Chick Growth Factors Apparently Organic in Nature

a mixture of crude sources of unidentified growth factors was fed to chicks, the ob served growth increases appeared to be due to the presence in these materials of both unidentified organic and inorganic constituents. The evidence for the exist ence of growth-stimulating substances or ganic in nature was based upon the mark edly greater growth which occurred in chicks when the diet contained the intact supplements in comparison with that ob tained with an equivalent amount of min eral matter produced by ashing at temper atures of 525 to 700°C. The procedure of

Distribution of Vitamin B12 in the Organs and Tissues of the Chick.

Summary Microbiological data have been presented on the distribution of vit. B12 in the tissues and organs of chicks fed a purified diet containing a high level of vit. B12. Kidney was found to contain the most vit. B12 while liver and pancreas contain lesser quantities. Muscle, except for the heart, is low in vit. B12 under these conditions. A comparison of these results with other published data indicates that certain organs, particularly the kidney, liver and pancreas, have the ability to store appreciable quantities of vit. B12.

Methylation of Homocystine by Chicks Deficient in Vitamin B12.

Conclusions Chicks very deficient in vit B12 grew as well when homocystine and betaine were added to a methionine-deficient diet as when a comparable amount of methionine was added. No evidence was obtained that vit B12 increased the efficiency with which preformed methyl groups were tranferred to homocystine since the effects of vit B12 were additive to those of methionine or its equivalents of homocystine plus labile methyl. It appears likely, however, that when the chicks diet lacks methyl groups vit B12 is concerned in the synthesis of such groups and their combination with homocystine to form methionine. Formation of methionine by this procedure, however, is limited and insufficient to meet the needs of the chick.

Effect of oxythiamine on the growth of chicks.

Summary Oxythiamine, the 4′-OH analogue of thiamine, has been shown to be an effective thiamine antagonist in the nutrition of the chick. By increasing the level of oxythiamine fed, the chick weight was decreased until typical thiamine-deficiency symptoms occurred and death ensued. The addition of large amounts of thiamine to the diet prevented the toxicity due to oxythiamine, and the parenteral and oral administration of thiamine to oxythiamine-toxic chicks tended to overcome the inhibition. The chick, as well as the mouse, has been shown to be very sensitive to the addition of oxythiamine to the diet. It seems probable, therefore, that oxythiamine is an antagonist of thiamine in the nutrition of all species that require this vitamin as an essential nutrient. Evidence has been presented which indicates that the thiamine requirement of growing White Leghorn cockerels is greater in the absence of sufficient of the unidentified chick growth factors.

An Improved Method for the Microbiological Assay of Growth Factors on Paper Chromatograms.

Summary A simple, quantitative method for the microbiological assay of filter paper chromatograms has been described. Some possible applications have also been pointed out.

Further Studies of Factor R.

Summary The growth and hemoglobin responses obtained in chicks receiving a purified diet supplemented with factor R were found not to be due to the preformed folic acid present in factor R. By means of chick liver, rat liver, and hog kidney incubation procedures the folic acid content of factor R was greatly increased. This indicated the presence of potential folic acid which did not stimulate the growth of S. faecalis, but which was available to the chick. The potential folic acid liberated by hog kidney enzymes was found to account for all of the responses obtained in the chick, whereas chick and rat liver enzymes were not as effective in liberating folic acid. The most probable explanation for the discrepancy in the folic acid content of factor R obtained following hog kidney and rat or chick liver incubations is that factor R is a mixture of conjugates of folic acid rather than one conjugate. The response to factor R was not affected by the presence of succinylsulfathiazole in the diet. Conjugated folic acid appeared, therefore, to be available as such to the chick, or was made available by metabolic processes.

Response of anemic chicks to peteroylglutamic acid.

Summary Chicks deprived of pteroylglutamic acid (folic acid) for the first 4 weeks of life respond dramatically to a single administration of the vitamin given either orally or intramuscularly. The reticulocyte response preceded hemoglobin increase and reached a peak 4 to 6 days following administration. Intramuscular injection of pteroylglutamic acid was more than twice as effective as the same amount administered orally. The hemoglobin increase in 7 days was proportional to the amount of pteroylglutamic acid administered either by mouth or by intramuscular injection.