The osmoregulatory role of the filter-chamber in relation to phloem-feeding in Eurymela distincta (Cicadelloidea, Homoptera)

ABSTRACT. The cicadelloid leaf-hoppers, Eurymela distincta (Signoret) and Eurymela fenestrata (Le Pelletier & Serville), feed on the phloem sap of Eucalyptus spp. The osmotic pressure profile of haemolymph and gut fluids is consistent with a filtration mechanism based on passive osmosis. This is responsible for shunting water rapidly from foregut to hindgut in the relatively simple filter chamber. The osmotic gradient which drives the system is probably produced by active secretion of sodium and potassium into the Malpighian tubules and posterior midgut. Although the osmotic pressures in all parts of the system are higher, the mechanism is probably similar to that previously described for xylem-feeding cicadas.
The major haemolymph cations are sodium and magnesium and the concentrations of sodium and magnesium in the urine are higher than potassium. A variety of storage granules in the midgut contain calcium, phosphorus (as phosphate), ferric iron, zinc, magnesium, manganese and copper.     

A study of the concentrically laminated concretions, 'spherites' in the regenerative cells of the midgut of Lepidopterous larvae

Concentrically laminated granules, spherites, are sometimes found in the regenerative cells of midgut of some species of lepidopterous larvae. The spherites are formed in cytoplasmic vesicles just before ecdysis and disappear during the differentiation of the regenerative cells to columnar and goblet cells. They function as intracellular stores of compounds used in the growth of the cell. Phosphates of magnesium and perhaps calcium are probable constituents. Spherites are sometimes also found in the degenerating columnar cells where they are excreted into the lumen with the exfoliating epithelium. The phenomenon of periodic precipitation which is the physical-chemical basis of the formation of spherites is discussed.     

Studies on water and ion transport in homopteran insects: ultrastructure and cytochemistry of the cicadoid and cercopoid midgut

The midgut of cicadoid and cercopoid insects is differentiated at the anatomical, ultrastructural and cytochemical levels into a conical segment, anterior, mid, and posterior midgut. The cells of the conical segment and anterior midgut are cytochemically very similar. They differ in ultrastructure, the anterior midgut cells having a submicrovillar row of mitochondria and a very marked mucoprotein coat investing the microvilli. The mid-midgut contains mineral spherites, which are formed in cisternae in the endoplasmic reticulum, and ferritin. The posterior midgut differs cytochemically from the anterior midgut and the cells are characterized by deep narrow basal invaginations and the absence of a mucoprotein coat investing the microvilli. It is suggested that nutrient absorption occurs in the conical segment and anterior midgut. Ion absorption may also occur in the anterior midgut. Storage excretion of calcium, magnesium and phosphate occurs in the mid-midgut. Ferritin is also stored here but may be found in other regions of the midgut, particularly in the cicada. The posterior midgut may be involved in ion secretion which could be related to filter chamber function.     

Metamorphosis of midgut epithelial cells in the silkworm (Bombyx Mori L.) with special regard to the calcium salt deposits in the cytoplasm. I. light microscopy

The morphological changes of the metamorphosing midgut cell in the silkworm were traced light-microscopically. The regenerative cells of the larval midgut proliferate rapidly during larval-pupal molt and finally replace the larval midgut, establishing new pupal midgut tissue composed of only one cell type. Pupal midgut cells contain numerous basophilic granules which are believed on histological grounds to be the deposits of calcium salts. Calcium seems to be transported from hemolymph to the pupal midgut cells and stored there temporarily as insoluble salts such as phosphate or carbonate, and then finally discharged into the lumen in a merocrine fashion. The midgut cells of the adult no longer contain calcium deposits.     

A comparison of iron availability from commercial iron preparations using an in vitro digestion/Caco-2 cell culture model

The objectives of this study were to compare iron availability from commercial preparations of FeSO(4), ferrous gluconate, ferrous fumarate, and a polysaccharide-iron complex using an in vitro digestion/Caco-2 cell culture model. In addition, we sought to determine if calcium carbonate and calcium acetate (common phosphate binding agents) inhibited iron availability from an oral iron supplement when digested simultaneously. Caco-2 cell ferritin formation following exposure to simulated gastric and intestinal digests of the iron supplements was used as a measure of iron uptake and availability. Plates without cell monolayers were included in each replication of the experiment to measure the total amount of soluble iron that resulted from the in vitro digestion. Significantly more iron was taken up from the FeSO(4), ferrous gluconate, and ferrous fumarate than the polysaccharide-iron complex. Similar results comparing FeSO(4) and the polysaccharide-iron complex have been observed in humans. In addition, less iron was taken up from digests with calcium carbonate relative to calcium acetate even though similar amounts of soluble iron were observed in these experiments. The results indicate that when iron supplements and phosphate binders are consumed simultaneously, calcium acetate may be the preferred phosphate binder to maximize iron availability.     

Chemical Purity of Shewanella oneidensis-Induced Magnetites

Magnetite is a common iron oxide produced both inorganically and biogenically. Biologically-induced magnetite is often originated, under appropriate conditions, as a result of the Fe³⁺ reduction by dissimilatory iron reducing bacteria, which are usually found in anoxic environments or at the oxic-anoxic interface. Such a Fe³⁺ bioreduction occurs upon this cation acting as an electron acceptor of an anaerobic respiration, thus creating favorable conditions for magnetite precipitation. This biologically-induced magnetite is an important biomineral in the environments inhabited by iron reducing bacteria. The presence of a variety of cations may influence both the biomineralization process and the resulting biomineral, however this phenomenon has not been investigated extensively. In the present study, we study the effect on the magnetite biomineralization process of the presence of calcium, magnesium and manganese in the culture medium where Shewanella oneidensis lives. We also test the incorporation of these cations into the crystalline structure of inorganic and biogenic magnetite induced by S. oneidensis. According to our findings, manganese ions likely become incorporated into the crystal structure of biologically produced magnetites, while magnesium ions are incorporated in inorganic magnetites, and calcium ions are excluded from the crystal structure of both inorganic and biotic magnetites. We hypothesize that the incorporation of cations into magnetite depends not only on the relative cation radii, but also on the mechanisms of magnetite formation.     

Trans-epidermal Transport and Storage of Calcium in Holthuisana transversa (Brachyura; Sundathelphusidae) During Premoult

Holthuisana transversa reabsorbs much of its exoskeletal calcium in the last 3 days before ecdysis and stores it in circulating granules in the haemocoel and in non-circulating granules in the subepidermal connective tissue. Calcium enters the epidermal cells from the moulting fluid, probably through their apical microvilli and is either incorporated into intracellular calcium granules or exits the cell via the basolateral membranes to be used in formation of two other granule types. Intracellular granules (0.4–2 μm long) form in large masses in the apical cytoplasm of the epidermal cells. They are formed as membrane-bound vesicles by the Golgi, and calcium and organic matrix material are added from the surrounding cytoplasm. As development proceeds, lamellae appear and calcium carbonate is deposited in the matrix. Granule masses move basally and are stored in the connective tissue. Calcium is also incorporated into extracellular large granules (0.8–3.8 μm long) which are formed in narrow intercellular channels between epidermal cells. A third granule type (small granules, 0.26 μm diameter) is formed in subepidermal connective tissue cells and released into the haemolymph in very large numbers. Calcium was identified in the two larger granule types using X-ray microanalysis and significant amounts of phosphorus and potassium were also present in the large granules. A model for ion cycling between the exoskeleton and granules is presented.     

Magnesium and Calcium in Isolated Cell Nuclei

The calcium and magnesium contents of thymus nuclei have been determined and the nuclear sites of attachment of these two elements have been studied. The nuclei used for these purposes were isolated in non-aqueous media and in sucrose solutions. Non-aqueous nuclei contain 0.024 per cent calcium and 0.115 per cent magnesium. Calcium and magnesium are held at different sites. The greater part of the magnesium is bound to DNA, probably to its phosphate groups. Evidence is presented that the magnesium atoms combined with the phosphate groups of DNA are also attached to mononucleotides. There is reason to believe that those DNA-phosphate groups to which magnesium is bound, less than 1/10th of the total, are metabolically active, while those to which histones are attached seem to be inactive.     

Seasonal changes in the concentrations of Ca,Fe, K,Mg, Mn and Na in eelgrass (Zostera marina L.) in the Limfjord,Denmark

The seasonal changes in concentrations of calcium, iron, potassium, magnesium, manganese and sodium in above- and below-ground parts of eelgrass (Zostera marina L.) were studied at three locations in the Limfjord, Denmark.The concentrations of calcium, iron and manganese in eelgrass differed significantly at the three stations. Above-ground parts of eelgrass contained significantly higher concentrations of potassium and manganese than below-ground parts, whereas the concentrations of iron and sodium were highest in the below-ground parts. Calcium and mangnesium concentrations in the two fractions were not significantly different.Significant seasonal variations were observed in the concentrations of calcium, potassium, manganese and sodium in above-ground parts of eelgrass and in the concentrations of iron, magnesium and sodium in below-ground parts. Iron, potassium, manganese and, to an extent, sodium showed a similar seasonal pattern with maximum concentrations in the summer and minimum concentrations in the spring or fall, whereas calcium concentrations in the above-ground parts showed the opposite pattern.The observed seasonal variation patterns are discussed in relation to the respective metals and changes in environmental factors.     

Mineral congregations, “spherites” in the midgut gland ofCoelotes terrestris (Araneae): Structure,composition and function

Summary Spherites in the digestive and secretory cells of the midgut gland of the agelenid spiderCoelotes terrestris were studied by electron microscopy and histochemical methods. Spherites measured 1–6 m in diameter and were characterized by alternating layers of electron dense and electron lucent material. The main-components of spherites were calcium phosphates and calcium carbonates. Guanine and barium, as well as aminopeptidase and alkaline phosphatase were also present. The matrix consisted of proteins and carbohydrates. Numerous spherites were found together with excretory products within the excretory vacuoles of the digestive cells.Spiders fed with food containing lead, showed deposition of the metall in the spherites. It is then proposed that spherites, aside from their role in storing calcium and other ions, may function in detoxification of heavy metals.     

On the effect of ferrous sulphate on the available manganese in the soil and the uptake of manganese by the plant

Summary Application of iron as ferrous sulphate or chloride to a loam not deficient in manganese had no effect on the yield but increased the uptake of manganese even in barley which grew vigorously.In an experiment with sugar beet on two soils contrasted with regard to their available manganese supply, applications of manganese, iron and nitrogen were tested in all combinations. On the Købelev soil, not deficient in manganese, no increases in yields were obtained on addition of ferrous sulphate while increases in manganese uptake were found for all combinations of treatments except where iron was added in the presence of manganese.On the manganese deficient Faarevejle soil, significantly higher increases in yields of roots were obtained from ferrous sulphate in the presence of nitrogen than in the presence of manganese. The effect of iron in the presence of nitrogen on the yield of tops was also significant. These treatments also gave the highest increases in manganese uptake.The amounts of manganese extractable from the soils by magnesium nitrate over a range of pH 2–8 could be increased considerably by addition of ferrous sulphate.The results support the suggestion that application of ferrous sulphate to some soils has the same effect as an addition of manganese.     

UPTAKE OF MANGANESE BY CHROMAFFIN GRANULES IN VITRO

Abstract– The distribution of metal ions in the chromaffin granule is anomalous. Calcium ions are accumulated but magnesium ions excluded. We have used the manganese ion as a convenient divalent element for following metal ion uptake because it can usefully be employed as a substitute for magnesium.
The kinetics of the manganese incorporation were followed by radio tracer technique and its transport was characterized as being non-energy dependent and having a small thermal activation factor. The presence in the incubation medium of a membrane-bound ATPase inhibitor (NEM) or addition of CN⁻ or NaN₃ did not affect the metal incorporation into chromaffin granules. Little endogenous magnesium exchanges for manganese when the latter is incorporated, but magnesium competitively prevented manganese uptake. The binding of manganese inside the vesicle was strong and it was not exchangeable with magnesium even in the presence of ATP.
Manganese when incorporated binds to ATP and displaces catecholamines resulting in a decrease in the CA/ATP ratio.     

Inorganic polyphosphates are stored in spherites within the midgut of Anticarsia gemmatalis and play a role in copper detoxification

Inorganic polyphosphates (PolyP) are widespread molecules that have been shown to play a role in metal detoxification and heavy-metal tolerance. In the present report, we investigated the functional role of spherites as PolyP-metal binding stores in epithelial cells of the midgut of Anticarsia gemmatalis, a lepidopteran pest of soybean. PolyP stores were detected by DAPI staining and indirect immunohistochemistry as vesicles distributed in columnar cells and around goblet cell cavities. These PolyP vesicles were identified as spherites by their elemental profile in cell lysates that were partially modulated by P- or V-ATPases. PolyP levels along the midgut were detected using a recombinant exopolyphosphatase assay. When copper was added in the diet of larva, copper detection in spherites by X-ray microanalysis correlated with an increase in the relative phosphorous X-ray signal and with an increase in PolyP levels in epithelia cell lysate. Transmission electron microscopy of chemically fixed or cryofixed and freeze substituted tissues confirmed a preferential localization of spherites around the goblet cell cavity. Taken together, these results suggest that spherites store high levels of PolyP that are modulated during metal uptake and detoxification. The similarity between PolyP granules and spherites herein described also suggest that PolyP is one of the main phosphorous source of spherites found in different biological models. This suggests physiological roles played by spherites in the midgut of arthropods and mechanisms involved in heavy metal resistance among different insect genera.     

The effect of iron supply on the yield and composition of leaves of tomato plants

Summary This paper describes a factorial experiment which was designed to elucidate the effect of total iron supply and rate of iron supply on the yield of tomato plants. Information was also obtained on the effect of iron supply and leaf age on the concentration of a number of nutrient elements in the leaf tissue.Increasing the total iron supply increases the yield, and the iron concentration in the leaves, while the manganese, phosphorus, sodium, calcium and magnesium decrease in concentration. The young leaves have a lower concentration of iron, manganese, potassium, sodium, calcium and magnesium than the older leaves, while the reverse is true of nitrogen and phosphorus. A slow rate of iron supply decreases the yield and sodium concentration in the leaves but increases the manganese and phosphorus concentrations.Interaction between total iron supply and leaf position affects the manganese, potassium, calcium and magnesium concentrations in the leaves, while the interaction between total-iron level and rate of iron supply affects the phosphorus and calcium concentration in the leaves.     

On the effect of ferrous sulphate on the available manganese in the soil and the uptake of manganese by the plant II

Summary Pot experiments with oats on manganese deficient sandy and moor soils, which are not deficient in iron, showed a steady increase in yield and manganese uptake by the plants with increasing additions of ferrous sulphate at four levels of manganese. Residual effects from ferrous sulphate application were not found either in the case of yields or manganese uptake by oats on a sandy soil.The effect observed following application of ferrous sulphate was due to a manganese effect. This is corroborated by the coincidence of the yield curves, showing the relationship between absorbed manganese and yield of dry matter, following the application of manganese sulphate and ferrous sulphate.Soils treated withM magnesium nitrate in the presence of equivalent quantities of either ferrous sulphate or hydroquinone yielded the same amounts of manganese. This result suggests that the manganese effect of ferrous sulphate is due to reduction of higher manganese oxides by ferrous sulphate.     

Early pattern of calcification in the dorsal carapace of the blue crab, Callinectes sapidus

The pattern of calcium carbonate deposition was observed in the dorsal carapace of premolt (D2-D3) and early postmolt (0-48 h) blue crabs, Callinectes sapidus, using scanning (SEM) and transmission (TEM) electron microscopy. Samples of dorsal carapace for SEM were quick-frozen in liquid nitrogen, subsequently lyophilized, and viewed using secondary and backscattered electrons as well as X-ray maps of calcium. Pieces of lyophilized cuticle were also embedded in epoxy resin and subsequently sectioned and viewed with TEM and SEM. Fresh pieces of dorsal carapace for TEM were also fixed in 2.5% glutaraldehyde in phosphate buffer followed by postfixation in 1% OsO4 in cacodylate buffer. Calcium concentrations were determined using atomic absorption spectrophotometry and quantitative X-ray microanalysis. Calcium accumulation began in the cuticle at 3 h postmolt at the epicuticle/exocuticle boundary and at the distal and proximal margins of the interprismatic septa (IPS). The bidirectional calcification of the IPS continued until the two fronts met at 5-8 h postmolt. The roughly hexagonal walls of the IPS formed a honeycomb-like structure that resulted in a rigid cuticle. The walls of the canal containing sensory neurons also calcified at 3 h, thereby imparting rigidity to the structure and additional strength to the cuticle. Examination of thin sections of lyophilized cuticle and fixed cuticle revealed that the first mineral deposited is more soluble than calcite and is probably amorphous calcium carbonate. The amorphous calcium carbonate is transformed to calcite along a front that follows the original deposition and is probably controlled by a specialized matrix within the IPS. Since amorphous calcium carbonate is isotropic, it would also make the mineral in the exocuticle stronger by an equal distribution of mechanical stress.     

Influence of dietary protein type and iron source on the absorption of amino acids and minerals

The apparent digestibility coefficient (ADC) of amino acids and the balance of minerals (calcium, phosphorus, magnesium and iron) has been determined in rats fed four diets differing in the protein type (casein or soy protein) and iron source (ferrous sulphate or lactate) in order to study the possible interactions of these nutrients. The availability of amino acids, especially essential amino acids, was greater in the diet made with animal protein (casein). The iron source also affected the absorption of most amino acids in all the diets assayed with ferrous sulphate being greater. The balance of iron, magnesium and phosphorus was higher in the diets containing animal protein. The retention of calcium and magnesium was significantly greater when ferrous sulphate was used as iron source. These results demonstrate the important interaction between amino acids and minerals and between the minerals themselves, which must be carefully studied when selecting different types of protein or mineral sources in human or animal nutrition.     

The calcified puparium of the face fly, Musca autumnalis (Diptera: Muscidae)

The general composition of the calcified puparium of Musca autumnalis was determined. Ash-weight analyses show that 62% of the puparium is inorganic material. The major components of the puparium are calcium, magnesium, phosphate and carbonate. Calcium and magnesium phosphate are the predominant salts in the puparium, with a lesser contribution by their respective carbonates. Scanning electron microscopy revealed that the exocuticle was the site of calcification in the puparium. Inorganic analyses of the insoluble salt isolated from face fly larvae showed it to be compositionally identical with the puparial salt. Major organic components of the puparium are lipid, chitin and protein. The presence of carbonic anhydrase and alkaline phosphatase activity in post-feeding larvae was confirmed.     

Biomineralization by photosynthetic organisms: Evidence of coevolution of the organisms and their environment?

Biomineralization is widespread among photosynthetic organisms in the ocean, in inland waters and on land. The most quantitatively important biogeochemical role of land plants today in biomineralization is silica deposition in vascular plants, especially grasses. Terrestrial plants also increase the rate of weathering, providing the soluble substrates for biomineralization on land and in water bodies, a role that has had global biogeochemical impacts since the Devonian. The dominant photosynthetic biomineralizers in today's ocean are diatoms and radiolarians depositing silica and coccolithophores and foraminifera depositing calcium carbonate. Abiotic precipitation of silica from supersaturated seawater in the Precambrian preceded intracellular silicification dominated by sponges, then radiolarians and finally diatoms, with successive declines in the silicic acid concentration in the surface ocean, resulting in some decreases in the extent of silicification and, probably, increases in the silicic acid affinity of the active influx mechanisms. Calcium and bicarbonate concentrations in the surface ocean have generally been supersaturating with respect to the three common calcium carbonate biominerals through geological time, allowing external calcification as well as calcification in compartments within cells or organisms. The forms of calcium carbonate in biominerals, and presumably the evolution of the organisms that produce them, have been influenced by abiotic variations in calcium and magnesium concentrations in seawater, and calcium carbonate deposition has probably also been influenced by carbon dioxide concentration whose variations are in part biologically determined. Overall, there has been less biological feedback on the availability of substrates for calcification than is the case for silicification.     

A Stopped-Flow Method for the Determination of Ascorbic Acid in Orange Juice Containing Triose Reductone

The adsorption of uranium by chitin phosphate and chitosan phosphate was investigated to obtain information on uranium recovery from aqueous systems, especially sea water and uranium mine waste water. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid during the first 10 min and was affected by pH of the solution, temperature, granule radius and the co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate.