Vitamin B12 Requirement Research Articles

Vitamin B12 nutrition and metabolism in the baboon (Papio cynocephalus).

1. Measurement of the vitamin B12 content of baboon tissues showed that the liver contained the highest concentration, followed by the pituitary, kidney, heart, spleen and pancreas. 2. The dietary vitamin B12 requirement of the baboon for the maintenance of satisfactory body stores was between 1 and 2 mug/d. 3. Satisfactory liver vitamin B12 stores were invariably associated with serum levels above 125 pg/ml, whereas liver levels were usually low when the serum level was below 50 pg/ml. 4. Increased methylmalonic acid (MMA) excretion after a valine load occurred when the liver vitamin B12 level was less than 0-40 mug/g. L- and DL-valine were approximately equally effective as precursors of MMA, whereas sodium propionate, whether given orally or intraperitoneally, was less effective. 5. The distribution of radioactivity along the wall of the intestinal tract after an oral dose of [57-Co]cyanocobalamin suggested that the distal half of the small intestine was the main site of vitamin B12 absorption. However, the utilization of vitamin B12 put direct into the middle part of the small intestine was much lower than that of an oral dose. 6. The unsaturated vitamin B12-binding capacity of baboon serum was not related to the serum vitamin B12 level. There was a significant difference between the unsaturated vitamin B12-binding capacities of the two subspecies of baboon (Papio cynocephalus cynocephalus and P. cynocephalus anubis) studied.

Nutrition in the Australian aborginines--effects of the fortification of white flour.

The nutritional status of 66 part Aborginines was re-examined in 1974--with particular reference to blood levels of haemoglobin and vitamins--after white bread fortified with iron and the vitamins B1 and PP (niacin) had been available for six and half months to the population of Bourke, New South Wales. The results found in 1971 and 1974 are compared. A significant improvement from deficient to acceptable blood levels of vitamins B1 and B6 was found in 44% and 52% of the subjects respectively. This attributed to the comsumption of fortified bread since the levels of the other vitamins had remained either unchanged or worsened. The biochemical improvement in vitamin B6 is attributed to the sparing effect of vitamin PP on vitamin B6 requirement because the conversion of tryptophan to niacin is impaired in vitamin B6 deficiency. Iron deficiency anaemia in children had decreased by 50% but this could have been due to many other factors besides the iron which had been added to the bread. Clinically there was a marked decrease in angular stomatitis and skin xerosis which could be related to the biochemical improvement of the two B-vitamins and a decrease in active trachoma and suppurative otitis media probably due to intensive treatment received since 1971. The results of this study and the extent of biochemical vitamin B1 and B6 deficiency found in other groups, indicate that fortification of bread may be of benefit to the community as a whole.

Urinary 4-pyridoxic acid, plasma pyridoxal phosphate, and erythrocyte aminotransferase levels in oral contraceptive users receiving controlled intakes of vitamin B6

Fifteen women who had used combination type oral contraceptives (estrogen plus progestogen) and 9 control women who had never used these agents were given a diet deficient in vitamin B6. After 1 month, this diet was supplemented daily with 0.8, 2.0 or 20.0 mg of pyridoxine hydrocholride for an additional month. At weekly intervals, measurements were made of urinary 4-pyridoxic acid, plasma pyridoxal phosphate, and erythocyte alanine and aspartate aminotransterases. No significan differences were observed between oral contraceptive users and controls in any of the above measured indices. The data suggest that if the use of oral contraceptives of the combined estrogen-progestogen type does alter the requirement for vitamin B6, the effect is a mild one and of doubtful clinical significance to the majority of women taking these steroid preparations. The amount of vitamin B6 (as pyridoxine) needed to maintain normal levels of the above indices of vitamin B6 nutrition in these subjects were between 0.8 and 2.0 mg/day.

Studies on a Possible Interaction Between Riboflavin and Vitamin B12 as it Affects Hatchability of the Hen’s Egg

Experiments were conducted using Single Comb White Leghorn chickens to investigate a possible interaction between the requirements for riboflavin and vitamin B12 for hatchability and to determine how important such an interaction might be in altering the requirements for one or both of these vitamins. The vitamin B12 requirement for optimum hatchability was found to be 3.45–3.60 μg./kg. of diet, and the requirement for dietary riboflavin, approximately 2.75 mg./kg. of diet. Dietary riboflavin at deficient or practical levels of feeding was found not to affect the vitamin B12 concentration in egg yolk, or the vitamin B12 requirement for optimum hatchability. Although a slight sparing effect of vitamin B12 upon the riboflavin requirement was suggested by the present studies, the effect was not statistically significant (p < .05). High levels of dietary vitamin B12 exerted a striking negative effect on riboflavin concentrations in egg yolk (p < .05). Egg production and food consumption were not affected by dietary riboflavin levels ranging from 1.61 to 5.51 mg./kg. of diet or vitamin B12 ranging from 1.0 to 11.0 μg./kg. of diet. However, optimum egg size was achieved only when the highest level of vitamin B12 was fed.

GROWTH OF VITAMIN B12‐REQUIRING MARINE DIATOMS IN MIXED LABORATORY CULTURES WITH VITAMIN B12‐PRODUCING MARINE BACTERIA12

SUMMARYThe vitamin B12 requirement of several marine diatoms can be satisfied in B12−limited laboratory cultures by heterotrophic marine bacteria isolated from the same waters and from sediments. The bacteria can utilize diatom excretory products, or the remains of dead diatom cells, in the production of the vitamin.The growth of 12 B121− requiring diatoms (7 genera) in mixed cultures with 14 different bacteria (without added B12) was compared to the growth of those same diatoms in axenic cultures with excess added B12. Diatom growth was generally rapid in the first few days, followed by sustained, slower growth. The diatom yields in mixed cultures ranged from 0.8 to 84% of the yields in axenic cultures with added B12.In a detailed study of one mixed culture, increases in diatom densities were paralleled by increases in cell densities of the bacterium during the first few days of exponential diatom growth. During the period of slow diatom growth, when diatom densities oscillated but steadily increased, the decreases in diatom densities were associated with increased bacterial growth. This suggests that death of a fraction of the B12‐limited diatom population releases sufficient organic matter to stimulate growth of the bacteria and their subsequent excretion of B12; this B12 in turn stimulates further growth of the diatoms.Diatom‐bacteria interactions leading to the production of B12 may be important in maintaining viable populations of B12‐requiring diatoms in nutrient‐poor waters during periods between blooms, when conditions are unfavorable for rapid growth.

The effect of dietary propionic acid on the requirement of chicks for vitamin B12.

1. Test diets were given to chicks from 1 to 28 d of age. The basal diet contained soyabean meal as the sole source of protein and contained no vitamin B12.2. The basal diet supported poorer growth and feed conversion efficiency than did the same diet supplemented with 0.01, 0.03 or 0.3 mg cyanocobalamin/kg.3. Each of the four diets was also offered with a supplement of 20 g propionic acid/kg. This caused a significant growth depression at all but the highest level of cyanocobalamin addition.4. Methylmalonic acid was detected in the excreta of chicks that received the supplements of 0 and 0.01 mg cyanocobalamin/kg diet, and in those of chicks receiving 0.03 mg only for the chicks that were also receiving propionic acid.5. The results suggest that giving the odd-carbon, propionic acid to chicks may increase their requirement for vitamin B12.

Vitamin B12 antagonism by monocarboxylic acids and anilides of cyanocobalamin.

VARIOUS test systems have been used to examine the anti-metabolite activity of vitamin B12 analogues1. In general, the tests have relied on the demonstration of growth inhibition or depression in either vitamin B12-requiring microorganisms or vitamin B12-deficient experimental animals. I have investigated the effect of the mixed isomeric monocarboxylic acids of cyanocobalamin and the anilides derived from these acids on the in vivo biochemical function of vitamin B12 in vitamin B12-depleted baboons.

Axenic Rearing of Larvae and Adults of the Boll Weevil1 on Defined Diets: Additional Tests with Amino Acids and Vitamins2

Studies of the requirements of Anthonomus grandis Boheman for the indispensable amino acids were extended. Semiquantitative requirements for histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine were established for weevils grown on an amino acid diet that had proved satisfactory previously. Tryrosine neither replaced nor spared phenylalanine when it was substituted for all or part of the phenylalanine. The boll weevil was found to require dietary biotin when it was fed an amino acid diet, but no requirement for vitamin B12 was observed for a single generation. Four generations of boll weevils were reared under aseptic conditions when both larvae and adults were fed a sterile defined diet.

Effect of Dietary Protein Level on Vitamin B6 Requirement of Chicks

Two experiments using 180 day-old, male broiler type chicks were conducted to study the effects of changing dietary protein level on chicks receiving diets varying in vitamin B6 content. Birds were fed graded levels of vitamin B6 (1.1, 3.1, 5.1, 6.1 and 10.1 mg./kg. of diet) at three dietary protein levels (15, 20 and 25% of the diet).Birds receiving 1.1 mg. of vitamin B6/kg. of diet showed depressed growth, feed consumption, feed efficiency and serum aspartate aminotransferase (S.A.A.) activities at all dietary protein levels studied. Increasing the vitamin B6 level from 3.1 to 6.1 mg./kg. diet resulted in a significant increase in body weight gains, feed efficiency, and S.A.A. activities at dietary protein levels of 20 an d 25% but not at 15%. Carcass fat was significantly reduced in the deficient groups while carcass moisture was significantly increased. Carcass protein content was not significantly affected by the vitamin B6 level of the diet. Since all the parameters observed gave an improved response by increasing vitamin B6 level with increased dietary protein levels, it is concluded that just as observed with other species, an increase in dietary protein should also be accompanied by an increase in vitamin B6 level in poultry rations.

The Vitamin B6 Requirement of the Male Rat as Determined by Behavioral Patterns, Brain Pyridoxal Phosphate and Nucleic Acid Composition and Erythrocyte Alanine Aminotransferase Activity

The Vitamin B6 Requirement of the Male Rat as Determined by Behavioral Patterns, Brain Pyridoxal Phosphate and Nucleic Acid Composition and Erythrocyte Alanine Aminotransferase Activity

Normal and pathological conditions which may alter the human requirement for vitamin B 6 .

Normal and pathological conditions which may alter the human requirement for vitamin B 6 .

Methylmalonate, Formiminoglutamate and Aminoimidazolecarboxamide Excretion of Vitamin B12-deficient Germfree and Conventional Rats

In order to evaluate the net influence of microbial metabolism on vitamin B12 nutriture, growth and urinary methylmalonic acid (MMA), aminoimidazolecarboxamide (AIC) and formiminoglutamic acid (FIGLU) were measured in male germfree and conventional rats fed a low methionine diet with or without vitamin B12 and during dietary supplementation with 1% of DL-methionine. Growth was retarded significantly among vitamin B12-deficient rats of both environments in comparison with their respective vitamin B12-supplemented controls. MMA excretion rose to 20 times the control level in conventional deficient rats but was only slightly elevated among germfree deficient animals. Though less dramatic, the same trend was true of AIC excretion. FIGLU excretion was elevated significantly in deficient animals of both environments. Methionine ingestion further enhanced MMA excretion of conventional deficient rats, suggesting that it served as a metabolic precursor. AIC excretion was unaffected by methionine feeding in contradiction to an earlier report. FIGLU excretion was depressed by DL-methionine supplementation to a greater extent among conventional than among germfree rats, perhaps indicating poor utilization of the D-isomer by germfree animals. These results show that MMA excretion is an unreliable index of vitamin B12 deficiency in the absence of conventional microbial metabolism and that the vitamin B12 requirement may be reduced in the germfree state.

Cholesterol, Pantothenic Acid, Pyridoxine and Thiamine Requirements of Honeybees for Brood Rearing

SummaryColonies of newly emerged bees which had never eaten pollen were offered diets consisting of (A) vitamin-free casein and minerals, or A supplemented with cholesterol and the vitamins of the B group (B), or with the B vitamins but without cholesterol (C), or with cholesterol and the vitamins except pantothenic acid (D), or with cholesterol and the B vitamins except pyridoxine (E), or with cholesterol and the B vitamins except thiamine (F). The colonies reared 5 cycles of brood on diets B, D and F, and 3 cycles on diet C. No adults were produced on diet E, and no larvae were reared to the sealing stage on diet A. It therefore appears that pyridoxine is required for normal brood rearing.

Interrelationships Between Methionine and Vitamin B6 in Chick Diets

ALTHOUGH various functions of vitamin B6 in protein metabolism have been well established, several others have not yet been clearly defined. Christensen (1962, 1963) presented evidence for the participation of vitamin B6 in the cellular uptake of amino acids. Sauberlich (1961) proposed that when an amino acid is limiting, added amounts of vitamin B6 in the diet may have a “sparing effect” by allowing more incorporation of the limiting amino acid into protein and growth instead of being channeled into oxidative pathways.Both quality and quantity of protein in a ration have been shown to play an important role in determining the need of the animal for vitamin B6. Cercedo and Foy (1944) observed that the onset of the characteristic dermatitis of vitamin B6 deficiency in rats was accelerated on a high-protein diet. Kirchgessner and Frienecke (1963) concluded that, as in the rat, the vitamin B6 requirement in growing cockerels…

Vitamin B6requirement of young adult women

Vitamin B6requirement of young adult women

The Cellular Approach to the Determination of Pyridoxine Requirements in Pregnant and Nonpregnant Rats

The cellular approach was used in evaluating the pyridoxine requirements of pregnant and nonpregnant rats. A plateau in hepatic DNA and RNA concentrations occurred at the 10 μg level of pyridoxine intake in nonpregnant animals. The DNA concentration of maternal and fetal livers also plateaued at the 10 μg level, whereas the DNA content of fetal brain did not plateau until 15 μg. RNA concentrations in fetal and maternal liver also plateaued at the 15 μg level. Hepatic polysomal activity maximized in animals fed the 10 μg level of pyridoxine; however, fetal brain ribosomal activity did not plateau until the level of intake was 20 μg. Total protein content was related to polysomal and ribosomal activities; a plateau in protein content in maternal and fetal liver occurred at the 15 μg level of pyridoxine intake and in fetal brain at 20 μg. Among the measurements used, alanine aminotransferase activities, protein and RNA content, and polysomal activities had the highest correlations with the level of pyridoxine intake. On the basis of these parameters, the pyridoxine requirement for nonpregnant rats appeared to be between 10 and 15 μg daily and between 15 and 20 μg for pregnant animals.

Mutants of Escherichia coli with a growth requirement for either lysine or pyridoxine.

Two distinct phenotypic classes of lysine requiring auxotrophs of Escherichia coli are described. Mutants of the LysA class produce little or no active diaminopimelic acid (DAP) decarboxylase and specifically require lysine for growth. Mutants of the LysB class produce a cryptic DAP decarboxylase which can be activated both in vivo and in vitro by higher than normal levels of its cofactor, pyridoxal 5'-phosphate. The LysB mutants have an alternate requirement for lysine or pyridoxine. Both LysA and LysB mutations map at 55 min, close to the thyA locus of E. coli. The association between pyridoxal phosphate and DAP decarboxylase appears to be much weaker in LysB mutants than in wild-type bacteria, and the mutant enzyme also sediments more slowly than wild-type enzyme in sucrose density gradients. The results suggest that the LysB mutations alter a specific region (or subunit) of the enzyme molecule which is needed to stabilize the binding of pyridoxal phosphate. These studies help to resolve certain contradictory observations on DAP decarboxylase reported earlier and may have relevance to pyridoxal phosphate enzymes in general. Prototrophic revertants of LysB mutants arise by second site mutations that result in increased availability of intracellular pyridoxal phosphate. These revertants appear to be derepressed for pyridoxine biosynthesis.

Inhibition of cobamide coenzyme activity by a polypeptide derived from the cell wall of Lactobacillus leichmannii.

The cell wall and ribosomes of Lactobacillus leichmannii ATCC 7830, a vitamin B12-requiring organism, have been shown to inhibit the cobamide coenzyme-dependent propanediol hydro-lyase (EC 4.2.1.28) reaction. A B12-binder (polypeptide) of the wall was isolated and purified as a B12-polypeptide complex (4). The complex, when treated with an alkaline solution, resulted in detachment of B12 from the polypeptide. The free polypeptide, upon neutralization, could bind B12 again and cobamide coenzyme as well, thus capable of inhibiting the enzyme reaction. Comparison was also made of this polypeptide with a hog intrinsic factor preparation in the inhibition.

Causes of the Increased Requirement for Vitamin B12 in Rats Subsisting on an Unheated Soybean Flour Diet

Possible causes of the increased requirement for vitamin B12 by rats fed a diet of unheated soybean flour were investigated. Decreased intestinal synthesis or increased destruction, as well as decreased absorption from the intestine were excluded. However, the vitamin B12 formed by the intestinal flora was less available for absorption when synthesized by rats subsisting on unheated soybean flour. Furthermore, turnover of vitamin B12 in these rats, as estimated by the rate of disappearance of injected 57Co-labeled vitamin B12 from kidneys, liver and spleen, was slightly accelerated.

Identification and cultivation of European Volvox spp.

The three European species ofVolvox have repeatedly been described, also from other countries. There have remained, however, some open questions, particularly in connexion with the morphological differences betweenV. aureus andV. tertius. These species, up to now, could not readily be distinguished but can be told apart on the strength of the structure of the covering layers of the colonial envelope. The nutritional requirements have attracted little attention. The scarce statements in the literature have only been attained in investigations of a general character and needed a more thorough investigation. It was found that all three species require vitamin B12, andV. globator also vitamin B1. This species flourished only when provided with small amounts of acetate.