Effects of ionic valency of interacting metal elements in ion uptake by carrot (Daucas carota cv. U.S. harumakigosun)

Interaction of elements in the course of element uptake by carrot (Daucas carota cv. U.S. harumakigosun) exerted by the addition of elements, such as Rb, Zn, and Al, was investigated. For the purpose of precise evaluation of uptake behavior, the simultaneous determination of absorption of Na, Be, Sr, Mn, Co, Zn, Ce, Pm, and Gd was conducted by the multitracer technique. For root uptakes, Al exhibited its influence on the uptake of essential elements and on the uptake of toxic or unbeneficial ones, presumably as a result of the large electric valency that caused cell membrane disintegrity. On the other hand, Zn as a divalent cation only affected the uptake of essential and beneficial elements. Rubidium, which is a monovalent cation, did not exhibit any effect on the uptake of other ions. Concerning shoot uptakes, inhibition by Zn and Al, but not by Rb, was observed for the uptake of Sr, Mn, Co, and Zn. From the present investigation, it is suggested that there exists an interaction between added ions and the elements taken into plants and that the degree of interaction increases in the increasing order of ionic valency: M+ (Rb), M2+ (Zn), and M3+ (Al).     

Optimization of parameters for semiempirical methods IV: extension of MNDO,AM1, and PM3 to more main group elements

The NDDO semiempirical methods MNDO, AM1, and PM3 have been extended to all the remaining non-radioactive elements of the main group, excluding the noble gases. Most of the new elements are of Groups I and II. 44 sets of parameters are presented for the following methods and elements. MNDO: Na, Mg, K, Ca, Ga, As, Se, Rb, Sr, In, Sb, Te, Cs, Ba, Tl, and Bi; AM1: Li, Be, Na, Mg, K, Ca, Ga, As, Se, Rb, Sr, In, Sn, Sb, Te, Cs, Ba, Tl, Pb, and Bi; PM3: B, Na, K, Ca, Rb, Sr, Cs, and Ba. Average errors are presented for heats of formation, molecular geometries, etc.     

Multivariate analysis of elements in chinese brake fern as determined using neutron activation analysis

Pytoremediaton of arsenic (As) contamination using Chinese brake fern (Pteris vittata L.), an As hyperaccumulator has proven potential because of its cost-effectiveness and environmental harmonies. Aiming to investigate the elemental correlation in Chinese brake fern, 20 elements (As, Br, Ca, Ce, Co, Cr, Eu, Fe, Hf, La, Na, Nd, K, Rb, Se, Sm, Sr, Th, Yb and Zn) were measured in the fronds and roots of the fern by neutron activation analysis. The ferns were sampled from two sites with high geogenic As levels: Zimudang (ZMD) and Lanmuchang (LMC) in Guizhou Province, China. Multivariate statistic analysis was performed to explore the interrelationship between these elements, especially between As and other elements. As was found to be positively related to K, Na, La, and Sm in both the roots and the fronds, suggesting that these four elements might operate as synergies to As during uptake and transportation processes. Se was positively related to most of the other cations measured, except in the fronds of the fern at ZMD, where Br replaced Se as positively related to the other cations. The difference of As and Se in correlation with other cationic elements suggested that the two anionic elements play different roles in elemental uptake processes. Our findings of elemental correlation highlight the importance of the anioncation balance in Chinese brake fern.     

Accumulation of Minerals by Leccinum scabrum from Two Large Forested Areas in Central Europe: Notecka Wilderness and Tuchola Forest (Pinewoods)

Leccinum scabrum sporocarps and associated topsoils from two areas in Poland have been characterized for contents and bioconcentration potential of Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sr and Zn. Topsoil and fruitbody element composition varied between the two study sites, most likely as a result of local soil geochemistry. Element content of the labile fraction in topsoil from both sites followed the ‘pseudo‐total’ fraction and median values (mg kg^?1 dry matter) were: K 380 and 340, Mg 760 and 840, P 1100 and 920, Al 3800 and 8100, Ag 0.31 and 0.28, Ba 28 and 37, Ca 920 and 790, Cd 0.23 and 0.23, Co 2.0 and 1.7, Cu 3.2 and 3.6, Fe 2800 and 6300, Mn 280 and 180, Na 99 and 110, Ni 7.8 and 8.8, Pb 12 and 18, Rb 1.3 and 2.1, Sr 4.8 and 4.0 and Zn 22 and 19, respectively. Only for some elements such as K, Mg, Al, Ag, Ca, Co, Mn, Na, Ni, Sr and Zn we found concentration differences between the two study sites for the caps of sporocarps. With the exception of Al, Mn, Na and Pb, stipes showed a similar tendency. Caps had a higher concentration of K, Rb, P, Mg, Al, Ag, Cu, Fe, Zn, Cd, Pb and Ni compared to stipes, while Na, Ba and Sr contents were higher in stipes. The comparison of soil and fruitbody concentrations indicates that L. scabrum bioconcentrate some elements while others are bioexcluded.     

Distribution of 14 elements in various rat tissues following hypophysectomy,thyroparathyroidectomy, adrenalectomy,and castration

The tissue distribution of 14 elements was simulatneously determined in rats 28 d after hypophysectomy (HPY), thyroparathyroidectomy (TPTY), adrenalectomy (ADY), and castration (CTN). The elements Na, K, Ca, Mg, Fe, S, P, Rb, Sr, Mn, Cu, and Zn were investigated in whole blood, plasma, brain, liver, kidney, heart, skeletal muscle, and bone. Additionally Mo was determined in kidney and liver. The following results were obtained: 1) With regard to hormone deficiency: HPY induced the most noticeable, variations on all the elements tested owing probably to the direct and indirect effects of adenohypophyseal hormones. ADY led to the expected modification of Na and K but also to a Sr accumulation and a Rb depletion. TPTY induced a sharp decrease in plasma and tissues Ca, an increase in plasma P, but did not disturb the two elements in bone. An increase of Rb in many tissues and of Fe in heart, kidney, and liver were also observed. CTN had little consequences except in bone whose Cu and Fe contents were increased: 2) With regard to element variations: K, Mg, and S underwent little change. Discriminations were revealed between elements such as K and Rb, Ca and Sr, Ca and Mg, and Cu and Zn. The changes of Rb and Sr were consistent with regulatory mechanisms. The accumulation of Fe and Cu in tissues such as liver after HPY, TPTY, and ADY, suggest that the hormonal deficiencies could worsen the hemochromatosis with Wilson's disease; 3), With regard to plasma and tissues: No correlation appeared in element levels between plasma and other tissues. Brain was the least affected and liver, kidney and bone the most.     

Concentrations of trace elements in osteoarthritic knee-joint effusions

Concentrations of the 18 elements, barium (Ba), beryllium (Be), bismuth (Bi), calcium (Ca), cadmium (Cd), cesium (Cs), copper (Cu), lanthanum (La), lithium (Li), magnesium (Mg), molybdenum (Mo), lead (Pb), rubidium (Rb), antimony (Sb), tin (Sn), strontium (Sr), thallium (Tl), and zinc (Zn), were determined in the synovial fluids of osteoarthritic knee joints and in the corresponding sera of 16 patients by inductively coupled plasma-mass spectrometry. Knee-joint effusions have lower elemental concentrations than their corresponding sera. For the essential elements Ca, Cu, Mg, and Zn and for the nonessential and toxic elements Ba, Be, Bi, La, and Sb, this difference was highly significant. Strong positive correlations between concentrations in effusions and sera for the essential elements Cu and Mg and for the nonessential elements Cs, Li, Rb, and Sr could be established. The grade of localized hyperperfusion of the knee region in the blood pool phase of ^99mTc HDP bone scan indicating inflammation did not correlate with any elemental concentration determined. Deceased.     

Influence of the coat color on the trace elemental status measured by particle-induced x-ray emission in horse hair

The influence of hair color on the trace elemental status in horse's hair has been studied. A current analytical technique such as particle-induced X-ray emission (PIXE) used in this study has provided reliable, rapid, easy, and relatively inexpensive diagnostic methods. Twenty-eight elements (Al, Br, Ca, Cl, Co, Cu, Cr, Fe, Ga, Hg, K, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Se, Si, Sr, Ti, V, Y, and Zn) in mane hair were detected by the PIXE method. The gray hair contains significantly greter amounts of Cu, Ti, and Zn, and lower amounts of Br, Ca, Se, and Sr than those in other colored horse hairs (p<0.05). Those results measured in the horse's hair were similar to those found in human and dog hair. When interpreting a result, it should be kept in mind that hair color, especially gray hair, influences the concentrations of some elements in horse hair.     

Correlation between serum cholesterols and trace element uptake in liver,kidney, and blood of hypercholesterolemic mice

The radioactive multitracer technique was applied to the simultaneous determination of the uptake of 17 trace elements (Be, Na, Sc, V, Cr, Mn, Fe, Co, Zn, As, Se, Rb, Sr, Y, Zr, Nb, and Ru) in the liver, kidney, and blood of hypercholesterolemic model mice. The uptakes of Be, Sc, V, Cr, Fe, As, Rb, Y, Zr, Nb, and Ru in liver increased with an increasing feeding period of a cholesterol-rich diet, whereas the uptakes of Zn and Se decreased. Feeding of the diet resulted in a marked increase in serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol. The metabolism of trace elements between cholesterolemic and normal mice was compared with respect to their serum cholesterol levels. A significant positive correlation was found between the concentration of serum triglycerides and liver uptakes of Cr, Fe, and As and a negative correlation for the uptake of Zn. A significant positive correlation was found between the concentrations of serum high- and low-density lipoprotein cholesterols and kidney uptakes of Cr and Rb. A negative correlation was found between the uptake of Be in the blood and the concentration of serum triglycerides. These results suggest that cholesterolemia have some specific effects on the metabolism of some elements.     

Effects of adrenalectomy and of adrenal hormones on the tissue distribution of 14 elements in the rat

The effects of adrenalectomy (ADY) and of replacement therapy using a mineralocorticoid, deoxycorticosterone (DOC) and a glucocorticoid, dexamethasone (DEX) on the tissue distribution of elements in the rat, were studied under semichronic conditions. The elements, Na, K, Ca, Mg, Fe, S, P, Rb, Sr, Mn, Cu, and Zn were determined in whole blood, plasma, brain liver, kidney, heart, skeletal muscle, spleen, thymus, and bone. Additionally Mo was determined in kidney and liver and Ba in bone. ADY modified concentrations of all elements tested. Small changes were observed for K, Mg, Ca, S, and P, whereas much larger changes were noted for Na, Rb, and Sr. Cu, Zn, and Fe were mainly modified in liver and kidney, organs involved in storage and/or elimination. The consequences of ADY were corrected fairly well by DEX for Mg, Mn, Ca, Cu, and Mo; by DOC for Na and K, and by the two corticoids for Zn, Fe, Sr, and Rb. This study revealed that corticoids, mainly glucocorticoids, play an important role in the plasma and tissue balance of elements. It is suggested that these results may have a pathological and clinical significance.     

The ethylene/metal(0) and ethylene/metal(I) redox system: model ab initio calculations

Ab initio calculations (coupled cluster with single and double excitations; CCSD) have been used to investigate the model redox systems ethylene:M(0) (M = Li, Na, K, Rb, Cs) and ethylene:M(I) (M = Be, Mg, Ca, Sr, Ba, Zn, Cd, Hg). Within C2v symmetry, the ground (2A1) states correspond to the charge distribution given in the title. The lowest (2B2) excited states correspond, somewhat counter intuitively, to the ethylene*-/=M(II)ion pair. These trends can be rationalized on the basis of simple electrostatic and configuration-mixing arguments that lead to two simple equations for predicting the electron-transfer energies for oxidation or reduction of the ethylene. The electron-transfer energies to the 2B2 ion pairs are dominated by the electrostatic ion-pairing energies.     

Plant uptake of major and minor mineral elements as influenced by soil acidity and liming

This study reports effects on soil solution chemistry and plant uptake of 55 elements (Ag, Al, As, B, Ba, Be, Bi, Br, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Gd, Ge, Hf, Hg, Ho, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Pr, Rb, S, Sb, Sc, Se, Si, Sm, Sr, Tb, Th, Tl, U, V, W, Y, Yb, Zn, Zr) by raising the pH using addition of fine-grained precipitated calcium carbonate at 20 rates (yielding a soil solution pH range of 5.2 – 7.8) to A horizon samples of an acid Cambisol, cultivating a common grass (Agrostis capillaris L.) and determining the soil solution, root and shoot concentrations of these elements at the end of the experiment. For many of these elements, there is little or no previous information about concentrations in soil solutions, or in plant biomass, as related to soil pH/acidity or addition of calcium carbonate. Soil solutions were obtained by high speed centrifugation and ultrafiltration (0.2 m) of samples at 60% water-holding capacity. Concentrations of elements were determined by ICP-ES or (in most elements) ICP-MS, using isotopes specified. Soil solution pH, HCO₃ and organic C were also determined.Concentrations of elements in the biomass of A. capillaris were usually inversely related to soil solution pH. The most apparent (p<0.001) inverse, though often curvilinear, relationships between pH and concentrations in shoot biomass were measured for Ag, As, B, Ba, Eu, Ge, Li, Mn, Ni, P and Sr. Positive relationships (p<0.05) were only measured in Ca, Hg, Mg, Mo and S. For concentrations in root biomass, relationships were mostly, but not always, of the same sign and of a similar strength. Though soil solution pH and concentrations of elements were usually quite closely correlated, pH and/or HCO^– ₃ concentration more often accounted for a higher share of the variability in biomass concentration of elements than did soil solution concentration of the same element.     

The effect of ions on the adhesion and internalization of Chlamydia trachomatis by HeLa cells

The adhesion and internalization of Chlamydia trachomatis by HeLa cells was unaffected by removal of K+, Mg2+, or glucose from the incubation medium, slightly reduced by removal of Na+, and significantly reduced by omission of Ca2+, Sr2+, Mg2+, and Mn2+ could replace Ca2+ in the adhesion but only Sr2+ supported internalization, and La3+, Co2+, Fe3+, Ba2+, and Zn2+ all reduced internalization more than adhesion. During initial infection there was no measurable difference in the uptake or release of 45Ca2+ or 86Rb+ between infected and noninfected HeLa monolayers. Infection was not prevented by pretreatment of the monolayers with the calcium channel blockers, verapamil, D600, and nitrendipine, or the calmodulin inhibitors, TMB-8 or trifluperazine. The results suggest that divalent cations are not essential for chlamydial infection but that the process of internalization is facilitated by the presence of cations, particularly Na+ and Ca2+.     

Rapid release of 45Ca from an occluded state of the Na,K-pump

45Ca is bound to the occluded state of the Na,K-pump, apparently at K+ sites. Only one 45Ca ion is bound in place of two K+ ions, with an affinity approximately 0.08 mM; K+ competes with an apparent affinity approximately 0.04 mM. 45Ca is released rapidly from Na,K-ATPase in the presence of ATP or ADP, presumably to the intracellular medium. The rate constant of 45Ca release with ATP is greater than 100 s-1 at 20 degrees C, more than twice as fast as the rate of release of 42K from the occluded state. Phosphorylation of Na,K-ATPase with MgPi, which would lead to release of occluded K+ or Rb+ to the extracellular face of the membrane, stabilizes occluded 45Ca. 45Ca release is slower immediately after exposure to MgPi than after a rinse in the absence of Pi indicating that in the former circumstance the rate of 45Ca release is limited by dephosphorylation; 45Ca release is even slower after exposure to Mg2+ arsenate, consistent with dearsenylation being slower than dephosphorylation. When limited by dephosphorylation, the rate of 45Ca release is dependent on the species of monovalent cation present, increasing in the order N-methylglucamine less than Cs+ less than Li+ less than Na+ less than Rb+ less than K+. When the 45Ca occluded state is exposed to K + Mg + Pi and then to Na+ + Mg2+ + ATP, the exposure to K+ is "remembered," indicating simultaneous occlusion of 45Ca and K+. The apparent affinity for K+ in formation of this state is 10-50 mM, and the rate of release of K+ is approximately 2 s-1. Ca2+ has effects on the release of 86Rb from the occluded state: With ATP, Ca2+ acts like Mg2+ by stimulating 86Rb release at low concentrations and inhibiting at high concentrations; with MgPi, Ca2+ inhibits 86Rb release, presumably by preventing phosphorylation. Thus, Ca2+ has two actions on the Na,K-pump as studied here: one as a Mg2+ congener, and another as a K+ congener at transport sites. In the latter role Ca2+ is unusual in that it appears to be able to bind to the transport sites from the intracellular face of the pump and to become occluded, but unable to be released from extracellular sites.     

Significance of Trace Element Profile of Blood of Persons with Multiple Caries versus Sound Teeth

In order to determine any possible relation between chemical composition of a person’s blood to formation of dental caries, whole blood was analyzed for 35 inorganic elements (Si, Al, Fe, Ca, Mg, K, Mn, Ti, P, Li, Be, B, V, Cr, Co, Ni, Cu, Zn, As, Sr, Y, Nb, Mo, Ag, Cd, Sn, Sb, Ba, La, Ce, W, Pb, Bi, Zr, and F) in the 15 people having sound teeth as well as an equal number of those having multiple caries. The results showed the absence of 13 elements (Si, Al, Mn, Ti, Be, Co, As, Y, Cd, Ba, La, Ce, and Zr) in the blood of both groups. Of the remaining 22 elements, the results of only seven elements (Fe, P, B, V, Sr, Sn, and F) were significantly different between the two groups. The most remarkable finding of this study was significantly decreased amount of phosphorus, strontium, and fluorine and perhaps increased boron in the blood of persons with caries.     

Determination of major and trace elements in the liver of Wistar rats by inductively coupled plasma-atomic emission spectrometry and mass spectrometry

Inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) were used to determine age-related changes in the concentrations of constituent elements in the livers of Wistar rats of 1 week to 12 months old. At first, sample preparation and analytical conditions were investigated in order to set up a simple routine procedure for measuring multiple elements simultaneously. Seventeen elements in the standard reference samples of bovine and pork livers as well as rat liver samples could be determined with a reasonable precision and reproducibility. They were P, K, Na, Fe, Mg, Ca, Zn, Rb, Cu, Mn, Mo, Al, Co, Sr, Cs, Pb, and Cd in order of the levels of concentration in the adult rat livers. Of these elements, the five major elements (P, K, Na, Fe, Mg, Ca) were determined with ICP-AES and the others with ICP-MS. Although the number of animals was too small to draw a statistically definite conclusion, it seems that age-related changes in the concentrations of these elements could be categorized into three general patterns: (1) remaining essentially constant throughout the animal ages, as observed for P, K, Na, Mg, Ca, Rb, Sr, Cs, and Pb, (2) increasing with age, as observed for Fe, Mn, Mo, Co, and Cd, and (3) decreasing with age, especially in the early stages of growth, as observed for Cu and Zn.     

Characterization of Na/Ca exchange in plasmalemmal vesicles from zona fasciculata cells of the bovine adrenal gland

The presence of an Na/Ca exchange system in fasciculata cells of the bovine adrenal gland was tested using isolated plasmalemmal vesicles. In the presence of an outwardly Na(+) gradient, Ca(2+) uptake was about 2-fold higher than in K(+) condition. Li(+) did not substitute for Na(+) and 5 mM Ni(2+) inhibited Ca(2+) uptake. Ca(2+) efflux from Ca(2+)-loaded vesicles was Na(+)-stimulated and Ni(2+)-inhibited. The saturable part of Na(+)-dependent Ca(2+) uptake displayed Michaelis-Menten kinetics. The relationship of Na(+)-dependent Ca(2+) uptake versus intravesicular Na(+) concentration was sigmoid (apparent K(0.5) approximately 24 mM; Hill number approximately 3) and Na(+) acted on V(max) without significant effect on K(m). Na(+)-stimulated Ca(2+) uptake was temperature-dependent (apparent Q(10) approximately 2.2). The inhibition properties of several divalent cations (Cd(2+), Sr(2+), Ni(2+), Ba(2+), Mn(2+), Mg(2+)) were tested and were similar to those observed in kidney basolateral membrane. The above results indicate the presence of an Na/Ca exchanger located on plasma membrane of zona fasciculata cells of bovine adrenal gland. This exchanger displays similarities with that of renal basolateral cell membrane.     

Age-related changes in the concentrations of major and trace elements in the brain of rats and mice

Age-related changes in the concentrations of constituent elements in the brains of rats and mice 1 wk to 24 mo old were determined with inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). Seventeen elements could be determined with reasonable accuracy and reproducibility. They were P, K, Na, Mg, Ca, Fe, Zn, Cu, Rb, Al, Mn, Sr, Mo, Co, Pb, Cs, and Cd in order of concentrations in the adult rat brains. In these elements, six major elements (P, K, Na, Fe, Mg, Ca) were determined with ICP-AES and the others with ICP-MS. The concentrations of each element and the pattern of age-related changes were similar between the rat and mouse brains. The elements of which concentrations decreased with aging were K and Rb. On the other hand, the concentrations of some metal elements, including Fe, Cu, Sr, and Co, appeared to increase with growth and aging. The concentrations of other elements were relatively constant throughout the age examined.     

A Discriminant Analysis of Trace Elements in Scalp Hair of Healthy Controls and Stage-IIIB Non-small Cell Lung Cancer (NSCLC) Patients

Our work aimed at extending the search for the trace elements (TE) abnormalities in patients with lung cancer and in healthy controls who smoke, and also for evidence of a possible association between lung cancer and TE. The analysis of the hair from patients with Stage-IIIB non-small cell lung cancer (group 1) and healthy controls (group 2) were analyzed using the inductively coupled plasma mass spectrometry technique in order to obtain information on the correlation between the lung cancer patients and healthy controls. Sixty-seven one-hair samples in group 1 were individually collected before chemoradiotherapy. For comparison, 74 hair samples were collected from group 2. In group 1, the trace elements present at the highest levels were measured to be Ca, Zn, Sn, Na and Mg, respectively, and they were quantified as 68.2, 53.2, 33.9, 23.3, and 28.9?μg.kg(-1), respectively. In group 2, the trace elements present at the highest levels were Zn, Mg, Ca, Fe, and Se, respectively, and they were quantified as 109.7, 31.9, 30.8, 25.0, and 20.1?μg.kg(-1). In group 1, the highest levels of Ca, Sn, and Na were 2.03, 1.06, and 1.01 times higher, respectively, compared with group 2. In group 2, Zn, Mg, Fe, and Se were 2, 1.01, 2.7, and 1.6 times higher, respectively, compared with group 1. When the levels of trace elements were compared between groups 1 and 2 using Student's t test, the levels of Ag, Au, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Hg, K, Ni, Rb, Rh, Sb, Sc, Ti, V, and Zn were found to be statistically different (p?相似文献   

Correlation between 25 element contents in mane hair in riding horses and atrioventricular block

The influence of atrioventricular block (AV-block) on the trace elemental status in a horse hair was studied. The particle-induced X-ray emission (PIXE) method has provided a reliable, rapid, easy, and relatively inexpensive diagnostic method. Twenty-five elements (Al, Br, Ca, Cl, Co, Cu, Cr, Fe, Hg, K, Mg, Mn, Na, Nb, Ni, P, Pb, Rb, S, Se, Si, Ti, Y, and Zn) in mane hair and serum were measured by the PIXE method. A horse hair with first- and second-degree AV-block contained significantly greater amounts of Br, Ca, Sr, and Zn than those of horses without electrocardiographic abnormalities, whereas there was no significant differences in the elemental contents of the serum of the both groups. Those results in contents of a horse hair suggest that the evaluation of the degree of ionic imbalance by this method might be used to predict the susceptibility of a horse to heart disease much before symptoms appear.     

Changes in Soybean Fruit Ca2+ (Sr2+) and K+ (Rb+) Transport Ability during Development

Mineral uptake by soybean (Glycine max [L.] Merrill) seeds during development can significantly affect seed quality and value. Little is known about seed mineral transport mechanisms and control processes, although it is clear that each mineral displays a characteristic accumulation pattern. Ion-specific accumulation patterns could result from changes in source availability, in transport kinetics through the seed pod and seed coat, or in the mineral uptake capability of the embryo. Ca2+ and K+ have negligible and high phloem mobilities, respectively. Ca2+ accumulation lags behind dry matter (C and N) and K+ accumulation in soybean embryos. To eliminate source availability influences, the Ca2+ and K+ uptake ability of isolated embryos and of seeds in pod culture was examined during seed development. Sr2+ and Rb+ were used as transport analogs of Ca2+ and K+, respectively. Sr2+ and Rb+ uptake rates by isolated embryos increased with seed fresh weight, indicating that the embryo was not limiting Ca2+ accumulation. However, the pod-cultured embryo Sr2+ and Rb+ uptake rate trends differed: Rb+ uptake increased with seed fresh weight, whereas Sr2+ uptake rates remained constant or decreased slightly. Ovule Sr2+ influx data suggest that the pod and seed coat impose a transport barrier that could account for the relative decline in embryo Ca2+ content during development.