Calcium requirements of Azotobacter

Summary Calcium was essential for the growth of A. vinelandii, A. chroococcum, A. beijerinckii and A. insigne in the presence and absence of combined nitrogen. A. agile and A. macrocytogenes were able to grow in the absence of calcium but growth was stimulated by the cation.Calcium could be replaced by strontium at roughly the same molar concentration.The authors present evidence suggesting that the calcium sparing effect of ammonium and sodium acetates reported in the literature may be dependent on the size of inoculum used.Professor Dr. Dr. h. c. A. Rippel zum 70. Geburtstag.     

Effects of calcium preloading on the growth of calcium carbonate crystals in the endolymphatic sac of the tree frog,Hyla arbores japonica

Summary Tree frogs, either with or without calcium chloride preloading, were maintained in a 0.8% strontium chloride solution for 1 week, then studied by X-ray microanalysis and scanning electron microscopy to determine the distribution of incorporated strontium in the endolymphatic crystals. In the absence of calcium preloading, strontium was detected on every surface of all the crystals, but after calcium preloading for 5 or 7 weeks, strontium incorporation was partially or completely inhibited, suggesting that an inhibition of the growth of the endolymphatic crystals had taken place in these preloaded specimens.     

Calcium and Salt Toleration by Bean Plants

The role of calcium in the salt relations of the bean plant, Phaseolus vulgaris, was examined. Brittle wax bush bean plants were cultured in nutrient solutions containing 50 mM NaCl. In the absence of added calcium the plants showed a general breakdown of the roots. A low concentration of calcium in the nutrient solution (0.1 mM) prevented this. Without added calcium the plants absorbed and translocated sodium at such a rate that high concentrations of it built up in the leaves within two days. With increasing concentrations of calcium in the nutrient solution the leaves contained progressively less sodium, and at 3 mM CaSO₄ the concentrations of sodium in the leaves was equal to that of the control plants grown without addition of salt. Even after both roots and stems had reached a high concentration of sodium, the leaves of plants grown in the presence of adequate concentrations of calcium contained little sodium.     

Activity of Stereoisomers of Serricornin,Sex Pheromone of the Cigarette Beetle ( Lasioderma serricorne F.)

Formation of quinoprotein methanol dehydrogrnase (MDH) in Methylobacillus glycogenes, an obligate methylotroph, was strictly controlled by calcium (Ca) in the culture medium. Both the growth of the organism and the total enzyme activity of MDH were also repressed at less than 1 ppm of Ca, although specific activity of MDH showed a similar level. Ca in MDH was replaced with other metals during cultivation of M. glycogenes. When strontium (Sr) chloride was fed instead of CaCl₂, Ca in MDH was completely replaced by Sr and showed a specific activity over ten times higher than Ca-containing MDH, although there was no appreciable increase in the MDH content in cells cultured in Sr medium. Methanol oxidase activity was also elevated in the cells that were cultured in the medium with Sr.     

A calcium oxalate-secreting tissue in branchlets of the Casuarinaceae

Summary Deciduous branchlets of casuarina trees have an unusual calcium oxalate-secreting system in which the epidermal tissue deposits calcium oxalate crystals in cell walls of the branchlet surface. These prismatic crystals were identified by light and electron microscopy, histochemistry, and elemental X-ray analysis. This calcium oxalate-secreting tissue was found in all species of casuarinas examined, including three of the four genera of the Casuarinaceae:Allocasuarina sp.,Casuarina sp., andGymnostoma papuanum. Because crystals were present throughout the epidermis soon after it formed, the mechanism for their induction was likely to be different than that for calcium oxalate crystal idioblasts. Secreting cells had a complex endoplasmic reticulum that may be involved in the secretory process.Abbreviations EDS energy-dispersive X-ray spectroscopy - HPF/FS high pressure-frozen/freeze-substituted - SEM scanning electron microscopy - TEM transmission electron microscopy Dedicated to the memory of Professor John G. Torrey     

Incorporation of strontium into plant calcium oxalate crystals

Summary Lemna minor, which produces many calcium oxalate raphide crystals, was grown on media containing in addition to Ca, 200 M of one of the following divalent cations: Ba, Cd, Co, Mn or Sr. Energy dispersive X-ray analysis showed that only Sr was incorporated into the raphides at levels detectable by the analysis technique. Incorporation of Sr into other insoluble compounds, such as cell wall material, could not be detected. Plant species which form different crystal types in their leaves (Beta vulgaris, crystal sand;Arthrostema ciliatum, druse;Glycine canescens, prismatic) also incorporated Sr into their crystals when grown hydroponically on nutrient medium containing 200 M Sr.Axenic cultures ofL. minor were used to examine further the process of Sr incorporation into plant crystals. When grown on nutrient solution with 5 M Ca, increasing the Sr concentration resulted in increases of the amount of Sr incorporated into the raphide crystals. The ratio of Sr to Ca became greater as the Sr concentration was increased. This ratio change was due to both an increase in the amount of Sr incorporated and a decrease in the Ca incorporated. Analysis of the number of crystal idioblasts formed as a function of Sr concentration shows fewer idioblasts are produced as Sr became high. Competition with Ca and interference of Ca utilization by Sr is indicated.     

Calcium-rich hypha encrustations on Piloderma

Piloderma species are broad-host-range fungi associated with a wide variety of conifer and hardwood species to form ectomycorrhizae (ECM). In this study, we investigated the hypha crystals collected from Piloderma– Picea glauca× engelmannii ECM as an initial step in the elucidation of the role of mycorrhizal fungi in mineral weathering and nutrient cycling. We compared the morphology and composition of hypha encrustation between field and cultured Piloderma samples. For field samples, the morphology of encrustations was dominated by elongated crystals often underlain by verrucose crystals. Cultured samples had mostly verrucose crystals. Generally, encrustations on field samples had higher calcium contents than cultured samples. Calcium contents ranged from 3% in the verrucose crystals of cultured samples to 17% in verrucose and elongated crystals of field samples. Encrustations had infrared absorption bands at 1333 and 781 cm^–1 wavenumbers, indicative of the presence of oxalate. High amounts of C and O in verrucose crystals are likely associated with the crystal sheath around all encrustations. This composition suggests an intracellular origin for the crystals. It is possible that encrustations start as verrucose crystals and develop into euhedral elongated crystals susceptible to dislod- gement into the soil environment. These crystals may prevent the desiccation of the hyphae and inhibit the build-up of calcium and oxalate in fungus cells. Accepted: 15 October 2000     

Studies on the Inhibition of Intestinal Absorption of Radioactive Strontium: V. The Effect of Administration of Calcium Alginate

A method of selective suppression of absorption of radioactive strontium from ingested food material is described which allows calcium to be available to the body. In the present study the effects of administering calcium alginate were determined. Studies on the relative binding of Ca and Sr by calcium alginate in vivo are also important to the investigation of calcium-strontium exchange.Samples of calcium alginate were obtained commercially or prepared from sodium salts and the binding properties with Ca⁴⁵ and Sr⁸⁹ were tested in vivo. There was a free exchange of radioactive calcium as well as of strontium with bound inactive calcium. The amount of Ca⁴⁵ retained in the gut by calcium alginate is proportionally less than Sr⁸⁹, so that the ratio Sr⁸⁹/Ca⁴⁵ in the bone is consistently and significantly lower in treated rats. Calcium alginate acts differently from other calcium salts, although in a manner similar to sodium alginate.     

Cytoplasmic streaming of calcium oxalate crystals in Callipsygma wilsonis (Bryopsidales, Chlorophyta)

Light microscopic study of the giant‐celled, marine green alga Callipsygma wilsonis J. Agardh (Udoteaceae, Bryopsidales) revealed numerous birefringent crystalline inclusions in the terminal segments of the assimilatory axes. The inclusions were thin plates with a triangular shape in face view, a base up to 75 μm in length, and a height that was one‐seventh the length of the base. Crystals of various sizes commonly were stacked face‐to‐face with one or more edges coinciding, but removal of organic material by treatment in sodium hypochlorite resulted in disaggregation. The crystals were soluble in dilute hydrochloric acid without effervescence but were insoluble in acetic acid. These diagnostic chemical solubility tests and a positive reaction to the Yasue staining reaction indicated that the crystals were composed of calcium oxalate. Scanning electron microscopy showed that most crystals had smoothly curving edges, but some had truncate or beveled margins. Calcium oxalate crystals have been reported to occur in the large central vacuoles of several bryopsidalean species, but the crystals in C. wilsonis were present in the parietal cytoplasm, which was evident from the presence of crystals in streaming cytoplasm. Calcium oxalate crystals, amyloplasts, chloroplasts, and other cytoplasmic constituents moved along cytoskeletal cables at rates of approximately 2.8 μm s⁻¹. These findings add to a growing body of evidence that calcium oxalate crystals in diverse algae may be present in cellular compartments other than the central vacuole.     

Calcium,Calcium Oxalate Crystals,and Leaf Differentiation in the Common Bean (Phaseolus vulgaris L.)*

Young plants of Phaseolus vulgaris were grown in nutrient solutions at different levels of calcium concentration. When the calcium concentration was low more palisade parenchyma and less extended bundle sheath was formed at the adaxial side of minor veins of the leaves as compared to leaves of plants grown with higher calcium supply. The number of calcium oxalate crystals in the bundle sheath extensions was positively correlated to the amount of calcium fed to the plants. The ion induces additional cell divisions in the bundle sheath extensions. A high supply of calcium leads to the formation of a second type of crystal in the bundle sheath.     

The Absorption and Distribution of Strontium in Plants: I. PRELIMINARY STUDIES IN WATER CULTURE

The absorption and distribution of strontium in barley plantshas been studied, in water culture, both in the presence andabsence of calcium. Tracer methods have been employed. When no other bivalent ions were present in the external solutionthe absorption of strontium was proportional to the concentrationover a wide concentration range (10^–6 to 10^–1 m.equiv./l.).In the presence of calcium, however, absorption was reducedand appeared to be dependent on the total concentration of calciumplus strontium rather than on that of 8trontlum alone. The translocationof stron tium from the root to the shoot increased as the externalconcentration of both ions was raised. In plants of low initialcalcium status the rate of translocation of strontium was markedlyreduced, apparently because of its retention at or near theroot surface. Autoradiographs of plants treated with labelled strontium for24 hours at different stages of growth and grown subsequentlyfor varying periods of time in unlabelled nutrient solutionsshowed that very little redistribution of strontium occurredwithin the plant. Leaves which developed after treatment inthe labelled solutions contained little or no strontium evenwhen the concentration in the older leaves was very high. Strontiumwas initially retained in the nodes of the stems, but the greatestaccumulation was later found to be in the leaves which had beengrowing most actively at the time of absorption.     

香樟叶肉含晶细胞季节变化研究

为探讨香樟(Cinnamomum camphora)叶肉含晶细胞超微结构的季节变化,阐明香樟叶肉中草酸钙晶体在春夏秋冬的变化规律。该研究以多年生香樟(C. camphora)叶片为材料,分别于春夏秋冬四个季节露地取样,制作超薄切片,用透射电子显微镜(TEM)观察叶肉含晶细胞超微结构的变化。结果表明:春季时香樟叶肉中只有少数细胞有草酸钙晶体,数量较少,晶体结构多为柱状晶、方晶; 夏季时香樟叶肉细胞中随机分布于液泡的草酸钙晶体明显比春季的数量多、体积大、形态丰富,晶体多为柱状晶、方晶、针晶、簇晶; 秋季时香樟叶肉细胞草酸钙晶体和夏季的类似,数量较多,形态多样,以方晶和柱状晶针晶为主,伴有晶簇; 冬季时香樟叶肉含晶细胞晶体形态为柱状晶、方晶、针晶,数量比夏季和秋季的数量略有减少。该研究结果表明在一年四季中香樟叶肉细胞液泡中均有草酸钙晶体结构存在。     

Changes in "calcium" action potentials in neurons of the rat spinal ganglia during replacement of divalent cations in the extracellular medium

Single neurons of rat spinal ganglia were investigated in adult rats using a voltage clamping technique and intracellular microelectrodes. Removing sodium ions from the extracellular medium and adding tetraethylammonium to it enabled the calcium component of action potentials to be recorded. It was found that progressive selective suppression of this component takes place during extracellular recording, indicating a decrease in calcium conductivity, while sodium and potassium levels are maintained. It is suggested that this disturbance is caused by excessive influx of calcium, strontium, or barium ions into the cell. The calcium component of action potentials was also found to depend on stimulation rate; this dependence differed where calcium ions were replaced by strontium or barium ions. A possible connection between this effect and the process of voltage-dependent inactivation of calcium channels is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 2, pp. 202–207, March–April, 1986.     

Growth inhibition ofChlorella pyrenoidosa produced by sodium dihydrogen phosphate and its reversal by calcium

Summary The growth ofChlorella pyrenoidosa in a special medium based on the critical concentrations of nutrients for autotrophic growth has been shown to be stimulated more by chloride with the sodium salt than with the potassium salt, more by sulphate in the presence of sodium than in the presence of potassium, and to be inhibited by sodium dihydrogen phosphate and not by potassium dihydrogen phosphate. Furthermore, it has been found that calcium reversed the growth inhibition produced by sodium dihydrogen phosphate, and that strontium only partially substituted for calcium.     

Spent medium analysis for liquid culture micropropagation of <Emphasis Type="Italic">Hemerocallis</Emphasis> on Murashige and Skoog medium

Residual nutrients from Murashige and Skoog medium were analyzed following a 5-wk multifactor experiment. Plant density, sugar concentration, and plant growth regulators (benzyladenine and ancymidol) were examined using four genotypes of daylily (Hemerocallis) to determine which factors most influenced nutrient use. Active nutrient uptake was observed for 11 nutrients (potassium, sodium, copper, phosphorus, iron, calcium, magnesium, manganese, boron, sulfur, and zinc) with lower concentrations in spent medium than in the tissue water volume (fresh-dry mass expressed as mL H₂O). Two patterns of nutrient use were visualized by correlative analysis of nutrient uptake. Greatest growth lowered plant nutrient concentrations of potassium, sodium, phosphorus, iron, and copper in all genotypes, and luxuriant uptake was indicated with least growth. Potassium, sodium, iron, and copper concentrations in plant dry matter were equal to or exceeded what is observed in vigorously growing nursery plants. However, phosphorus concentration in plant dry matter was low enough to be considered deficient when compared to Hemerocallis plants in nursery production. With a second group of nutrients (calcium, magnesium, manganese, and boron), the genotype, “Barbara Mitchell” lacked active uptake and was deficient. Calcium concentration was low in all plants compared to Hemerocallis grown under nursery conditions (“Barbara Mitchell” was the lowest concentration) despite active uptake by the other three genotypes—“Brocaded Gown,” “Mary’s Gold,” and “Heart of a Missionary.” Magnesium concentration in these three genotypes was low enough in vessels with greatest growth to question its adequacy at high densities. Increased sucrose in medium reduced the dry matter concentrations of all tested nutrients. Plant growth regulators had less impact on nutrient use than genotype and plant density. Nutrient uptake may be an important physiological component of genotypic variation.     

Selective mineral transport barriers at Cuscuta-host infection sites

The uptake of inorganic nutrients by rootless parasitic plants, which depend on host connections for all nutrient supplies, is largely uncharted. Using X-ray fluorescence spectroscopy (XRF), we analyzed the element composition of macro- and micronutrients at infection sites of the parasitic angiosperm Cuscuta reflexa growing on hosts of the genus Pelargonium. Imaging methods combining XRF with 2-D or 3-D (confocal) microscopy show that most of the measured elements are present at similar concentrations in the parasite compared to the host. However, calcium and strontium levels drop pronouncedly at the host/parasite interface, and manganese appears to accumulate in the host tissue surrounding the interface. Chlorine is present in the haustorium at similar levels as in the host tissue but is decreased in the stem of the parasite. Thus, our observations indicate a restricted uptake of calcium, strontium, manganese and chlorine by the parasite. Xylem-mobile dyes, which can probe for xylem connectivity between host and parasite, provided evidence for an interspecies xylem flow, which in theory would be expected to carry all of the elements indiscriminately. We thus conclude that inorganic nutrient uptake by the parasite Cuscuta is regulated by specific selective barriers whose existence has evaded detection until now.     

Cell wall sheath surrounding calcium oxalate crystals in mulberry idioblasts

Summary. The distribution and ultrastructural features of idioblasts containing calcium oxalate crystals were studied in leaf tissues of mulberry, Morus alba L. In addition to the calcium carbonate crystals formed in epidermal idioblasts, large calcium oxalate crystals were deposited in cells adjacent to the veins and surrounded by a cell wall sheath which had immunoreactivity with an antibody recognizing a xyloglucan epitope. The wall sheath formation indicates exclusion of the mature crystal from the protoplast. Correspondence: Y. Sugimura, Graduate School of Science and Technology, Kyoto Institute of Technology, Goshokaido, Matsugasaki, Sakyo, Kyoto 606-8585, Japan.     

Ion binding by repeat hexapeptide of elastin

Synthetic elastin hexapeptides, N-formyl-Val-Ala-Pro-Gly-Val-Gly-O-methyl, n-formyl-Ala-Pro-Gly-Val-Gly-Val-O-methyl, and N-formyl-Pro-Gly-Val-Gly-Val-Ala-O-methyl were studied in order to determine their affinity and selectivity for calcium, magnesium, strontium, sodium, and potassium ions. Of the three permutations N-forrnyl-Val-Ala-Pro-Gly-Val-Gly-O-methyl had the highest calcium affinity, k_a ～- 0.5 × 10⁶. All three hexamers displayed a selectivity toward calcium, although strontium did bind well also. The peptides could not compete effectively with water for magnesium ions and had little affinity for sodium and potassium ions. The significance of these results lies in the possible role of this hexameric sequence in calcium binding in natural elastin.     

Ionic analyses and effects of ions on contractions of sponge tissues

Summary Contractions of oscular membranes of several marine sponges in response to mechanical stimuli were recorded in various ionic media. Previously, failure to record action potentials and to stimulate electrically was reported.Contractions persisted when sodium was replaced by lithium or potassium but not when the replacement was by choline or sucrose. Contractions were maintained in sea water in which the only univalent cation was potassium; they also persisted in Na-sea water without potassium.Contractions stopped when either calcium or magnesium was omitted, but addition of an equivalent extra amount of the other divalent cation then restored contractions. Contractions were also maintained when strontium was substituted for calcium and magnesium.Analyses of contractile membranes yielded average values for Naples sponges of Na 375 mM/kg H₂O, K 29.8 mM/kg H₂O and inulin space 48.9% of H₂O; for Woods Hole Microciona in mM/kg H₂O: Na 300, K 66, Ca 8.4, Cl 225, inulin space 40% H₂O. The calculated intracellular concentrations for Microciona in mM/kg H₂O were: Na 216, K 104.5, Ca 7.8, Cl 45 yielding i/o ratios of Na 0.5, K 11.6, Ca 0.84, Cl 0.09.It is concluded that, despite relatively normal ionic ratios, mechanical stimuli activate the contractile system in sponges more directly than in muscle.Dedicated to Prof. H. Autrum on the occasion of his 60th birthday.This work was done in part while the author held a Guggenheim Fellowship. Support from NSF grant G 8795 is acknowledged.Assistance of Donald Job, particularly in making all calcium and magnesium measurements, is gratefully acknowledged.     

Blockage of a pump-related calcium-efflux pathway in light sarcoplasmic reticulum vesicles by Mops

Mops, used as a proton buffer, specifically enhances the accumulation of calcium or strontium by light sarcoplasmic reticulum vesicles driven by ATP or dinitrophenylphosphate as energy-yielding substrates when calcium-precipitating agents are absent. The enhancement of ion uptake by Mops is much greater for strontium than for calcium and is further increased when potassium is replaced by sodium as the dominant monovalent cation. Mops affects neither the activity of the calcium- or strontium-activated transport enzyme nor the active accumulation of calcium in the presence of oxalate, i.e. when the pump runs unidirectionally forward. Passive calcium and strontium efflux rates of approximately 40-50 nmol.mg-1.min-1 are considerably reduced when histidine/glycerophosphate or Tris/maleate are exchanged for Mops. The observed passive efflux rates and their modulation by Mops are too small, in relation to the rate of ion influx, to account for either the relatively small calcium and strontium load in the absence of precipitating agents or for its modulation by Mops. The results imply that the pump itself mediates ion efflux dependent on pump activity and the different degree of saturation of lumenal ion-binding sites by calcium and strontium, as well as their susceptibility to Mops.