THE ELONGATION OF MYOFIBRILS FROM THE INDIRECT FLIGHT MUSCLE OF DROSOPHILA

Myofibrils which lengthen by several per cent in the presence of ATP and magnesium ions were prepared by teasing indirect flight muscle of Drosophila in solutions containing ethylenediaminetetraacetate. A study was made of the hydrogen ion, magnesium ion, ATP, and potassium chloride concentrations with which this effect could be observed. The lack of elongation with pyrophosphate and several nucleoside triphosphates suggests that the lengthening is ATP specific. A relaxing factor system comparable to that described for rabbit muscle was not demonstrable, as elongated fibrils did not shorten with calcium ions, carnosine, or digitonin.     

The pH of body fluids from marine intertidal invertebrates

The pH of the body fluids of 25 species of marine invertebrates from nine phyla was determined at temperatures to which these animals were acclimated. The gastrovascular fluid of several coelenterates and one species of flatworm was found to have pH values approximating to that of sea water. The coelomic fluid of nemertine, sipinculid, echiuroid, and annelid worms, as well as the heart fluid of several molluscs and the sternal sinus fluid of decapod crustaceans, were characterized by more alkaline pH values. Echinoderm polian vesicle fluid was characterized by slightly acidic pH values. The importance of the pH of the body to the respiratory physiology of marine invertebrates is discussed.     

CALCULATIONS OF BIOELECTRIC POTENTIALS : VI. SOME EFFECTS OF GUAIACOL ON NITELLA

Values have been calculated for apparent mobilities and partition coefficients in the outer non-aqueous layer of the protoplasm of Nitella. Among the alkali metals (with the exception of cesium) the order of mobilities resembles that in water and the partition coefficients (except for cesium) follow the rule of Shedlovsky and Uhlig, according to which the partition coefficient increases with the ionic radius. Taking the mobility of the chloride ion as unity, we obtain the following: lithium 2.04, sodium 2.33, potassium 8.76, rubidium 8.76, cesium 1.72, ammonium 4.05, ½ magnesium 20.7, and ½ calcium 7.52. After exposure to guaiacol these values become: lithium 5.83, sodium 7.30, potassium 8.76, rubidium 8,76, cesium 3.38, ammonium 4.91, ½ magnesium 20.7, and ½ calcium 14.46. The partition coefficients of the chlorides are as follows, when that of potassium chloride is taken as unity: lithium 0.0133, sodium 0.0263, rubidium 1.0, cesium 0.0152, ammonium 0.0182, magnesium 0.0017, and calcium 0.02. These are raised by guaiacol to the following: lithium 0.149, sodium 0.426, rubidium 1.0, cesium 0.82, ammonium 0.935, magnesium 0.0263, and calcium 0.323 (that of potassium is not changed). The effect of guaiacol on the mobilities of the sodium and potassium ions resembles that seen in Halicystis but differs from that found in Valonia where guaiacol increases the mobility of the sodium ion but decreases that of the potassium ion.     

THE EXTRACELLULAR RELEASE OF ECHINOCHROME

A study was made of the diffusion of the red pigment echinochrome from the eggs of the sea urchin, Arbacia punctulata, into sea water. Unfertilized eggs retained their pigment, over periods of hours. Outward diffusion of pigment from unfertilized eggs normally is entirely negligible, or does not occur at all. Enchancing the calcium or potassium content of the artificial sea water (while retaining isosmotic conditions) did not induce pigment release. Under anaerobic conditions, unfertilized eggs release pigment in small quantities. Fertilization alone brings about echinochrome release. Fertilized eggs invariably released pigment, whether in normal sea water, or sea water with increased calcium or potassium. This diffusion of the pigment began during the first cleavage, possibly soon after fertilization. The pigment release is not a consequence solely of the cell''s permeability to echinochrome (or chromoprotein, or other pigment combination) but is preceded by events leading to a release of echinochrome from the granules in which it is concentrated within the cell. These events may be initiated by activation or by anaerobiosis. The phenomenon was not due to cytolysis.     

Some aspects of the mechanism of thermal acclimation in the earthworm Lampito mauritii

Summary Inorganic ions (Ca, Mg, Na, K, Cl, SO₄) and free amino acids of the body fluids of the normal, cold and warm acclimated worms (laboratory as well as seasonal populations) are estimated. Calcium increased and chloride and sodium decreased on both cold and warm acclimation in relation to normal. But magnesium and sulphate and free amino acids increased on warm acclimation whereas potassium increased and magnesium decreased on cold acclimation. Changes in different ions in the same direction are observed in the seasonal populations. Attention is drawn to the adaptive significance of these changes in the different ions during thermal acclimation.Changes in the glycogen, RNA, protein and non-protein nitrogen, and water content in the tissues of normal and acclimated worms are studied. Glycogen increased on warm and cold acclimation, whereas RNA content, protein nitrogen and dry weight of the cold worms increased over normal. No change is observed in non-protein nitrogen on thermal acclimation. The role of these substances and the significance of the changes observed, in the operation of homeostatic mechanism compensating to temperature changes in the metabolic rate of the worms, are also discussed.Changes in the pattern of neurosecretory activity are followed with thermal acclimation and it is shown that the activity of the neurosecretory cells increased on cold and warm acclimation, but the positions of these cells, which are active, are different from normal worms in warm acclimated worms.Studies on the effect of the body fluids of acclimated worms on the tissues of normal and acclimated worms showed that the body fluids of cold acclimated worms increased the respiration of the tissues of normal and warm acclimated worms and vice-versa.     

Ion concentrations in oviduct and uterine fluid and blood serum during the estrous cycle in the bovine

In the bovine up to 40% of embryos die before implantation but despite the importance of ions in oviduct and uterine fluid formation and in gamete, zygote and early embryo development there is very little published information on the ion concentrations of oviduct or uterine fluid. The free anions chloride, phosphate and sulphate and the free cations sodium, calcium, magnesium and potassium were measured in oviduct fluid on days 0, 2, 4 and 6 and in uterine fluid on days 6, 8 and 14 and in corresponding blood samples. Oviduct and uterine fluids were collected in situ. Sodium was 25-fold higher than potassium and 80-fold higher than the other ions and chloride was 10-fold higher than potassium and 40-fold higher than the other ions in oviduct and uterine fluid. Phosphate, sulphate, magnesium, potassium and calcium were at lower concentrations in all fluids. Oviduct calcium and sodium were higher on day 0 than other days. The most striking uterine differences were the higher potassium and lower chloride, sodium and magnesium on day 14 than other days. There were significant positive associations between oviduct and blood chloride, sulphate, magnesium and calcium while only uterine sulphate was positively related to its blood concentration. There was no relationship between fluid secretion rate and no association between the concentrations of systemic progesterone or oestradiol and any ion in oviduct or uterine fluid. The different concentrations and associations between ions in the oviduct, uterus and blood suggest a differential regulation of ion secretion by the oviduct and uterine epithelia.     

THE KINETICS OF PENETRATION : XVII. THE EXIT OF AMMONIA IN LIGHT AND DARKNESS

The exit of accumulated ammonia from the sap of Valonia macrophysa, Kütz., into normal (nearly ammonia-free) sea water, has been studied in light (alternation of daylight and darkness) and in darkness. Exit is always preceded by an induction period lasting 1 or more days. This is longer in darkness. After exit starts the rate is greater in light than in darkness. The pH of the sap drops off soon after the cells are exposed to normal sea water even before any definite decrease in the ammonia concentration of the sap has occurred. This suggests that the decrease in the pH is due to the loss of a very small amount of NH₃ or NH4OH without a corresponding gain of sodium as a base. In most cases sodium replaced the ammonia lost during exit, but there is some evidence that potassium may also replace ammonia. To account for the induction period it is suggested that other species than NH₄ X are concerned in the transport of ammonia, for example urea or amino acids.     

Hemolymph osmolality and cation concentrations in Litopenaeus vannamei during exposure to artificial sea salt or a mixed-ion solution: relationship to potassium flux

Interest in culturing the Pacific white shrimp Litopenaeus vannamei in low-salinity and brackish-well waters has led to questions about the ability of this species to osmo- and ionoregulate in environments containing low concentrations of ions and in environments with ionic ratios that differ from those found in sea water. After seven days, hemolymph osmolality and potassium, sodium and calcium values were all significantly affected by salinity (as artificial sea salt) with values decreasing with decreasing salinity. These decreases were small, however, relative to decreases in salinity, indicating iono- and osmoregulation with adjustment for gradients. The hemolymph osmolality and sodium and calcium concentrations in shrimp exposed to either 2 g/L artificial sea salt or 2 g/L mixed-ion solution (a mixture of sodium, potassium, calcium, and magnesium chlorides that approximate the concentrations and ratios of these cations found in 2 g/L dilute seawater) did not differ significantly. However, hemolymph potassium levels were significantly lower in shrimp held in the mixed-ion environment. Potassium influx rates were similar in shrimp held in either artificial sea salt or mixed ions. The results of this study indicate that salinity affects hemolymph-cation concentrations and osmolality. Further, differential potassium-influx rates do not appear to be the basis for low hemolymph potassium levels observed in shrimp held in mixed-ion environments.     

Influences of Ca and Mg ions on the egg survival of grey mullet, Mugil cephalus L.

Five kinds of artificial sea water with similar salinity, pH and osmolarity were prepared with different concentrations of calcium and magnesium ions. They were complete sea water, calcium-free sea water, half calcium-free sea water, magnesium-free sea water and half magnesium-free sea water. The fertilized eggs from induced spawnings of grey mullet Mugil cephalus , were transferred to these sea waters at two development stages, i.e. before the formation of 2-blastomere stage and at the gastrula stage. Survivals of fertilized egg in different sea waters were checked after several hours incubation, the percentage survival was used as an index of the importance of calcium and magnesium to the embryonic development. The results showed that calcium is indispensable to the embryonic development of mullet egg. Magnesium, however, is not the necessary element in the incubation medium.     

Visual imaging of ion distribution in human epidermis

The distribution of calcium, magnesium, potassium, sodium, and hydrogen ions in the human epidermis was visualized by blotting to gel containing chemical indicators and the effects of skin barrier disruption were examined. In normal skin, both calcium and magnesium were localized with high concentration in the upper epidermis. EDTA blocked these imaging. The hydrogen ion was also high in the upper epidermis. Sodium did not show obvious gradation in the epidermis. The potassium concentration was the lowest in the upper epidermis. After the barrier disruption, the gradients of calcium, magnesium, and potassium disappeared while the pH gradation was not altered. Observation at a high magnification revealed lower calcium and sodium concentrations in the nucleus. The concentration of magnesium was slightly higher in the nucleus. The novel method of the present study could show the visual image of the ions in frozen tissue without further preparation.     

THE ACCUMULATION OF ELECTROLYTES : VI. THE EFFECT OF EXTERNAL pH

It would be natural to suppose that potassium enters Valonia as KCl since it appears in this form in the sap. We find, however, that on this basis we cannot predict the behavior of potassium in any respect. But we can readily do so if we assume that it penetrates chiefly as KOH. We may then say that under normal conditions potassium enters the cell because the ionic activity product (K) (OH) is greater outside than inside. This hypothesis.leads to the following predictions: 1. When the product (K) (OH) becomes greater inside (because the inside concentration of OH^- rises, or the outside concentration of K⁺ or of OH^- falls) potassium should leave the cell, though sodium continues to enter. Previous experiments, and those in this paper, indicate that this is the case. 2. Increasing the pH value of the sea water should increase the rate of entrance of potassium, and vice versa. This appears to be shown by the results described in the present paper. It appears that photosynthesis increases the rate of entrance of potassium by increasing the pH value just outside the protoplasm. In darkness there is little or no growth or absorption of electrolytes. The entrance of potassium by ionic exchange (K⁺ exchanged for H⁺ produced in the cell), the ions passing as such through the protoplasmic surface, does not seem to be important.     

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.     

Patterns in moss element concentrations in fens across species,habitats, and regions

The ionome and stoichiometry of fen mosses have not yet been studied in extensive data sets despite their potential to explain ecological behaviour of the species and to indicate nutrient limitation or oversupply. We analysed element concentrations (N, P, K, Ca, Mg, and Fe) in apical parts of dominant peat and brown mosses along the complete pH/calcium gradient in fens of three Central European regions (the Western Carpathians, the Bohemian Massif and, marginally, the West-Bohemian mineral springs). We obtained data from 143 localities for 56 species, with the most replicates for calcium-tolerant Sphagnum warnstorfii. Tissue element concentrations were to a great extent determined by species identity, except for magnesium, iron, and potassium (in the potassium-poor region). Water chemistry determined substantially species’ magnesium, potassium (in the potassium-poor region), and partially also calcium concentrations. Calcium and potassium concentrations were generally most predictable by water chemistry, water table depth (WTD), and species identity, while concentrations of nitrogen, phosphorus, and especially iron were least predictable. Principal component analysis across the species showed the same two principal gradients in all regions. One reflected the ratios between iron and the other ions and the other the ratios between calcium + magnesium and other ions, sorting the species from calcicole (Scorpidium cossonii) to acidicole (Sphagnum fallax). Particular species differed strongly with respect to calcium concentration in both the biomass and the water, and median calcium concentration in a species coincided greatly with median concentration in the water. Tissue phosphorus, nitrogen, and potassium also differed significantly among the species, but analogous coincidences with the concentrations in water were not found. The results for iron and magnesium were inconsistent between the regions. Within particular species, correlations between biomass and water element concentrations were either positive or negative, but largely nonsignificant. The rare moss Hamatocaulis vernicosus had higher element concentrations (except for nitrogen) than would be predicted from water chemistry, resembling the pattern of R-strategy plants. In the Western Carpathians, calcium concentrations in S. warnstorfii decreased significantly with WTD, becoming stabilised at around 5 mg/g at WTD >15 cm. The inter-regional differences in species element concentrations were usually explainable by different iron, magnesium, and potassium concentrations in water, with signs of phosphorus immobilisation by iron such as generally higher N:P ratios in the iron- and simultaneously phosphorus-richer region (Bohemian Massif). Because moss chemical composition combines the effects of species identity and various effects of the environment, caution is needed in any meta-analysis.     

SALT EFFECTS ON SWARMERS OF DUNALIELLA VIRIDIS TEOD

1. Dunaliella viridis Teodoresco thrives equally well in solutions of NaCl 1 to 4 mol and pH 6 to 9. 2. The organism is sensitive to calcium and magnesium, especially in acid medium. 3. Calcium and magnesium are antagonistic. In a molar solution of NaCl the antagonistic relation Mg:Ca is 4 to 5. In a 4 molar solution of NaCl the proportion becomes many times as great (20:1). 4. Although the strains used in this investigation did not occur in sea water concentrates, the increase in the antagonistic ratio Mg:Ca in which they can live closely paralleled the changes in this ratio which take place when sea water evaporates. 5. The other organisms which occurred in the cultures each show a specific relation to Ca and Mg. 6. The size of the cells of Dunaliella does not decrease with increasing NaCl content.     

THE DISTRIBUTION OF INORGANIC CATIONS IN MOUSE TESTIS : Electron Microscope and Microprobe Analysis

For localization of pyroantimonate-precipitable cations, mouse testes were fixed with a saturated aqueous solution of potassium pyroantimonate (pH about 9.2, without addition of any conventional fixative), hardened with formaldehyde, and postosmicated. A good preservation of the cell membranes and over-all cell morphology is obtained as well as a consistent and reproducible localization of the insoluble antimonate salts of magnesium, calcium, and sodium. Four sites of prominent antimonate deposits are revealed, besides a more or less uniform distribution of the precipitates. These sites are: (a) In the walls of the seminiferous tubules, localized in two concentric layers corresponding to the inner and outer layers of the tubular wall; (b) Around the blood vessels and adjacent connective tissue; (c) At the area of contact between the Sertoli cell and spermatids, where a double line of precipitate surrounds the head of the mature spermatids; and (d) In the cell nuclei, disposed between regions of the condensed chromatin. The nucleus of mature spermatids did not show any sign of antimonate precipitation. The implications of this inorganic cation distribution are discussed with relation to their anionic counterparts, their localization in other animal and plant tissues, and the possibility that those sites may represent barriers to the free passage of ions.     

THE KINETICS OF PENETRATION : XVI. THE ACCUMULATION OF AMMONIA IN LIGHT AND DARKNESS

The accumulation of ammonia takes place more rapidly in light than in darkness. The accumulation appears to go on until a steady state is attained. The steady state concentration of ammonia in the sap is about twice as great in light as in darkness. Both effects are possibly due to the fact that the external pH (and hence the concentration of undissociated ammonia) outside is raised by photosynthesis. Certain "permeability constants" have been calculated. These indicate that the rate is proportional to the concentration gradient across the protoplasm of NH₄ X which is formed by the interaction of NH₃ or NH₄OH and HX, an acid elaborated in the protoplasm. The results are interpreted to mean that HX is produced only at the sap-protoplasm interface and that on the average its concentration there is about 7 times as great as at the sea water-protoplasm interface. This ratio of HX at the two surfaces also explains why the concentration of undissociated ammonia in the steady state is about 7 times as great in the sea water as in the sap. The permeability constant P'''''' appears to be greater in the dark. This is possibly associated with an increase in the concentration of HX at both interfaces, the ratio at the two surfaces, however, remaining about the same. The pH of sap has been determined by a new method which avoids the loss of gas (CO₂), an important source of error. The results indicate that the pH rises during accumulation but the extent of this rise is smaller than has hitherto been supposed. As in previous experiments, the entering ammonia displaced a practically equivalent amount of potassium from the sap and the sodium concentration remained fairly constant. It seems probable that the pH increase is due to the entrance of small amounts of NH₃ or NH₄OH in excess of the potassium lost as a base.     

FURTHER ASPECTS OF THE RELATIONSHIP BETWEEN NICKEL TOXICITY AND IRON SUPPLY

Absorption of nickel by oat plants increased with increasing pH for a fixed iron supply. Nickel uptake and toxicity symptoms (necrosis and chlorosis) were both reduced when the concentration of iron in the nutrient solution was high. Nickel-iron ratio in the nutrient solution. For solutions with the same nickel-iron ratio, toxicity symptoms increased with increase in the absolute amount of nickel. There was a linear relationship between the degree of necrotic symptoms and the nickel-iron ratio in the plant.
Nickel consistently reduced the iron content of roots and tops. In the absence of nickel, the iron content of the roots but not of the tops, increased with iron supply. In nickel-toxic plants, the magnesium, calcium and phosphorus contents of the tops and the potassium, calcium and phosphorus contents of the roots were higher than in healthy plants, but the potassium content of the tops and the magnesium content of the roots were lower.
Similar results were found with tomato.     

Marine invertebrates of the Sea of Okhotsk as a new source of lypopolysaccharide-binding proteins

Invertebrates from the Sea of Okhotsk were studied as a source of proteins that are capable of binding to lipopolysaccharides (LPSs) of gram-negative bacteria. A DOT analysis using dansyl-labeled LPS that we developed revealed LPS-binding proteins in blood-cell lysates of 21 out of 33 investigated species of invertebrates. Most of the investigated species with positive LPS-binding activity were decapod crustaceans (class Malacostraca, phylum Arthropoda). Hemocyte lysates from the red king crab Paralithodes camtschaticus and the sculptured shrimp Sclerocrangon boreas contained several LPS-binding proteins with different molecular weights. LPS-binding proteins were found for the first time in echinoderms (classes Holothuroidea, Asteroidea, and Echinoidea), sipunculans, and brachiopods.     

Analysis of the effects of calcium or magnesium on voltage-clamp currents in perfused squid axons bathed in solutions of high potassium

Isolated axons from the squid, Dosidicus gigas, were internally perfused with potassium fluoride solutions. Membrane currents were measured following step changes of membrane potential in a voltage-clamp arrangement with external isosmotic solution changes in the order: potassium-free artificial seawater; potassium chloride; potassium chloride containing 10, 25, 40 or 50, mM calcium or magnesium; and potassium-free artificial seawater. The following results suggest that the currents measured under voltage clamp with potassium outside and inside can be separated into two components and that one of them, the predominant one, is carried through the potassium system. (a) Outward currents in isosmotic potassium were strongly and reversibly reduced by tetraethylammonium chloride. (b) Without calcium or magnesium a progressive increase in the nontime-dependent component of the currents (leakage) occurred. (c) The restoration of calcium or magnesium within 15–30 min decreases this leakage. (d) With 50 mM divalent ions the steady-state current-voltage curve was nonlinear with negative resistance as observed in intact axons in isosmotic potassium. (e) The time-dependent components of the membrane currents were not clearly affected by calcium or magnesium. These results show a strong dependence of the leakage currents on external calcium or magnesium concentration but provide no support for the involvement of calcium or magnesium in the kinetics of the potassium system.