Molybdenum Absorption Research Articles

Effects of mining on the molybdenum absorption and translocation of plants in the Luanchuan molybdenum mine.

BackgroundThere is a critical need to examine whether mining of molybdenum (Mo) ore will affect Mo absorption and translocation by plants at a community level.MethodsIndigenous plants and their rhizospheric soil (0–20 cm) growing in two different areas including the mining and the unexploited areas were collected from the Luanchuan Mo mine—one of the largest Mo mines in Asia. The concentrations of Mo and other heavy metals of plants or soil were measured by ICP-AES. Mo absorption and translocation in plants growing in two areas were investigated and compared. Heavy metal pollution in soil was also evaluated by the potential ecological hazard index method.ResultsMo concentration in mining soils was higher with the changes from 108.13 to 268.13 mg kg−1 compared to unexploited area. Mo concentrations in shoots and roots of plants growing in the mining area were also significant higher than those growing in the unexploited area with 2.59 and 2.99 times, respectively. The Mo translocation factor of plants growing in the unexploited area was 1.61, which reached 1.69 times that of plants growing in the mining area. Mo was the main heavy metal pollutant in the soil of both the mining and the unexploited areas.ConclusionMining of Mo had changed not only the Mo concentration in soil but also Mo absorption and translocation in plants. Plants growing in the mining area absorbed more Mo from the soil but translocated relatively less to shoots than plants of the unexploited area. However, the mechanisms of Mo absorption and translocation of plants in mining area should be further studied in the future.

Molybdenum absorption and utilization in humans from soy and kale intrinsically labeled with stable isotopes of molybdenum

Stable-isotope studies of molybdenum metabolism have been conducted in which molybdenum was added to the diet and was assumed to be absorbed and utilized similarly to the molybdenum in foods. Our objective was to establish whether the molybdenum in foods is metabolized similarly to molybdenum added to the diet. We first studied whether sufficient amounts of molybdenum stable isotopes could be incorporated into wheat, kale, and soy for use in a human study. Enough molybdenum could be incorporated into soy and kale to study molybdenum absorption and excretion. Two studies were then conducted, one in women and one in men. In the first study, each meal contained approximately 100 microg Mo from soy, kale, and extrinsic molybdenum. In the second study, soy and extrinsic molybdenum were compared; the meal contained approximately 300 microg Mo. In the first study, molybdenum was absorbed equally well from kale and an extrinsic source. However, the molybdenum in soy was less well absorbed than the molybdenum in kale or that added to the diet. In the second study, absorption of molybdenum from soy was less than from the extrinsic label. Urinary excretion of soy molybdenum was also lower than urinary excretion of the extrinsic label, but excretion as a percentage of the absorbed dose was not significantly different between treatments. The molybdenum in soy is less available than molybdenum added to the diet, but the molybdenum in kale is as available as molybdenum added to the diet. Once absorbed, excretion is not significantly different for soy, kale, and extrinsic molybdenum.

Molybdenum absorption, excretion, and retention studied with stable isotopes in young men at five intakes of dietary molybdenum

A study of molybdenum absorption, excretion, and balance was conducted in four young men fed five amounts of dietary molybdenum, ranging from 22 to 1490 micrograms/d, for 24 d each. The study was conducted to obtain scientific data on which to base a recommendation on dietary molybdenum intake for healthy young men. Stable isotopes of molybdenum were used as tracers. 100Mo was fed five times during the study and 97Mo was infused three times. 94Mo was used to quantify the molybdenum isotopes and total molybdenum in urine, fecal collections, and diets by isotope dilution. Adverse effects were not observed at any of the dietary intakes. Molybdenum was very efficiently absorbed, 88-93%, at all dietary molybdenum intakes, and adsorption was most efficient at the highest amounts of dietary molybdenum. The amount and percentage of molybdenum excreted in the urine increased as dietary molybdenum increased, suggesting that molybdenum turnover is slow when dietary molybdenum is low and increases as dietary molybdenum increases. We conclude from these results that dietary intakes between 22 and 1500 micrograms/d by adult men are safe for > or = 24 d and that molybdenum retention is regulated by urinary excretion. Molybdenum is conserved at low intakes and excess molybdenum is rapidly excreted in the urine when intake is high.

Application of thermal ionization mass spectrometry to investigations of molybdenum absorption in humans

Thermal ionization mass spectrometry (TIMS) has been developed for the detection of Mo in biological samples in order to enable investigations on absorption and biokinetics in humans. A double rhenium filament technique is employed for sample evaporation and ionization, coupled with a quadrupole filter. The negative MoO 3 ions that are produced are then collected on a secondary electron multiplier and isotopic ratios are measured. A correction must be performed to take into account the isotopic composition of oxygen. The technique has been optimized for the determination of Mo down to 10 ng loaded on the evaporation filament. Preliminary tests were applied to aqueous solutions. Subsequently, measurements were performed on human urine samples, and finally the technique was applied to investigations on the intestinal absorption of Mo in humans. The technique proves to be quite simple and reliable in application, and enables widely ranging studies on molybdenum metabolism and biokinetics in humans to be performed without employing radioactive tracers.

Molybdenum absorption, excretion, and retention studied with stable isotopes in young men during depletion and repletion

A study of molybdenum absorption, excretion, and balance was conducted in four young men fed a low-molybdenum diet (22 micrograms/d) for 102 d followed by 18 d of the same diet supplemented to contain 467 micrograms/d. The study was conducted to determine the minimum dietary molybdenum requirement of healthy young men. Stable isotopes of molybdenum were used as tracers. 100Mo was fed four times during the study, 97Mo was infused twice, and 94Mo was used as an isotopic diluent to quantify the molybdenum isotopes and total molybdenum in complete urine and fecal collections and in the diets. The study demonstrated that subjects could not consistently attain balance with the low-molybdenum diet, but balance improved with time, and no signs of molybdenum deficiency were observed. Molybdenum was very efficiently absorbed at both intakes of dietary molybdenum and urinary excretion increased as dietary molybdenum increased. Molybdenum turnover was significantly slower when dietary molybdenum was low. We estimate from these results that the minimum dietary molybdenum requirement is approximately 25 micrograms/d or possibly less. This suggests that the lower end of the recommended range could be less than the current recommended amount of 75 micrograms/d.

Characteristics of molybdenum absorption and translocation in soybean plants

Abstract Investigations on the absorption and translocation of molybdenum (Mo) in soybean plants (Glycine max) grown in the field were conducted, and the following results were obtained. Up to the flower-bud-appearing stage, little absorption of Mo was detected. The Mo accumulation in the nodules may thus be highly dependent on the Mo contained in the seeds during the early growing period, and it can be said that the Mo contained in the seeds may play an important role in the early plant growth and probably in the nitrogen fixation by nodules. After the middle of June, the soybean plants began to absorb soii-Mo, and the Mo concentrations. in all the plant parts increased, especially in the nodules. During the podfilling stage, the Mo concentrations in the roots and pod shells decreased rapidly, whiie, in contrast, that in the seeds Increased. The Mo concentrations in the nodules, stems and leaves did not decrease so much, probably indicating negligible translocation to the seeds from these organs. Soybean...

Copper and molybdenum absorption by rats given ammonium tetrathiomolybdate

Previous studies have shown that the tetrathiomolybdate ion [MoS 4 2− ] is a potent antagonist of Cu metabolism. Effects of orally administered MoS 4 2− on the absorption and tissue distribution of 64Cu in rats have now been investigated. Four or 12 mg Mo/kg diet, when given as MoS 4 2− , strongly inhibited 64Cu absorption and modified the fate of absorbed Cu, decreasing hepatic and renal uptake but increasing plasma retention of 64Cu. These effects were not induced by equivalent dietary concentrations of Mo as MoS 4 2− or when S 2− was given as CaS. Clinical and biochemical effects induced by orally administered MoS 4 2− were abolished by increasing dietary concentrations of Cu. Such treatment also inhibited the absorption and tissue retention of 99Mo derived from 99MoS 4 2− . Intraperitoneal administration of Cu ameliorated clinical effects attributable to MoS 4 2− but neither inhibited 99Mo absorption nor the appearance of systemic defects in Cu metabolism. Since the absorption of MoS 4 2− (or its derivatives) from the gastrointestinal tract is inhibited by Cu, it is evident that the site of its action as an antagonist influencing either the absorption or the subsequent metabolic fate of Cu depends upon the ratio Cu/MoS 4 2− in the diet.

Effects of boron on nitrogen metabolism and sugar levels of sugar beet

The effects of deficient and toxic levels of boron on various aspects of nitrogen metabolism in sugar beet are studied. Plant analysis shows a nitrate ion accumulation, a decrease in the activity of the nitrate reductase enzyme and a lower molybdenum absorption.

Studies on Molybdenum Absorption and Transport in Bean and Rice

The patterns of molybdenum (MoO(4) (2-)) absorption and transport were investigated in intact bean (Phaseolus vulgaris L.) and rice (Oryza sativa L. cv. I.R.8) plants. The mobility of MoO(4) (2-) absorbed by roots and by leaves was compared with that of a freely mobile element, Rb(+). Although MoO(4) (2-) absorption by bean roots was nearly as high as that of Rb(+), its transport to the shoot was considerably less. When MoO(4) (2-) was fed to one of the primary leaves, most of it was transported to the stem and root. Evidence obtained here showed that MoO(4) (2-) was mobile. Experiments with intact rice seedlings revealed large differences in the absorption and transport of MoO(4) (2-) between the plants grown in CaSO(4) and those in Hoagland solution. Molybdate uptake by excised rice roots was suggested to be an active process since it was greatly inhibited by a metabolic inhibitor. The presence of Mn(2+), Zn(2+), Cu(2+), CI(-), or SO(4) (2-) in the absorption medium reduced MoO(4) (2-) uptake which was markedly enhanced by the presence of Fe(2+).

Atomic Absorption Spectrometric Determination of Molybdenum in Steel

The interference of iron on atomic absorption of molybdenum and its elimination were investigated for a determination of01ybdenum in steel using a nitrous oxide-acetylene flame, Iron caused the prominent interference with the molybdenum absorption. The molybdenum absorption was enhanced, it became constant i n various fiame onditions irrespective of irop c-oncentration, provided that the solution containing molybdenum and iron was heated with hydro xylamine hYdrochloride before spraying into the flame.Hydrazine suJfate, isodiu.m sglijtg andu nietailic zific were tested for the reduction of iron and the constant absorption of molybdenum was given in the fuel-lean fiame. ln the fuel-rich flame, the rpolybdenum.absorpti.op was ghtly decrclEised by the elevation of iron concentration. The effects of iron on the molybdenum absorp, tion becamr constant in 0.05 mol/ I phosphoric acid solution, but enhancement effect was lower than that of hydroxylamine hydrochloride.method. The sample was de60mposed with hydrochloric acid and nitric acid, followed by heatinge, ayhoe standard values. The coe ice nt of variations was about 2%.